A Turbine Based Combined Cycle Engine Inlet Model and Mode Transition Simulation Based on HiTECC Tool

NASA Technical Reports Server (NTRS)

Csank, Jeffrey; Stueber, Thomas

2012-01-01

An inlet system is being tested to evaluate methodologies for a turbine based combined cycle propulsion system to perform a controlled inlet mode transition. Prior to wind tunnel based hardware testing of controlled mode transitions, simulation models are used to test, debug, and validate potential control algorithms. One candidate simulation package for this purpose is the High Mach Transient Engine Cycle Code (HiTECC). The HiTECC simulation package models the inlet system, propulsion systems, thermal energy, geometry, nozzle, and fuel systems. This paper discusses the modification and redesign of the simulation package and control system to represent the NASA large-scale inlet model for Combined Cycle Engine mode transition studies, mounted in NASA Glenn s 10-foot by 10-foot Supersonic Wind Tunnel. This model will be used for designing and testing candidate control algorithms before implementation.

A Turbine Based Combined Cycle Engine Inlet Model and Mode Transition Simulation Based on HiTECC Tool

NASA Technical Reports Server (NTRS)

Csank, Jeffrey T.; Stueber, Thomas J.

2012-01-01

An inlet system is being tested to evaluate methodologies for a turbine based combined cycle propulsion system to perform a controlled inlet mode transition. Prior to wind tunnel based hardware testing of controlled mode transitions, simulation models are used to test, debug, and validate potential control algorithms. One candidate simulation package for this purpose is the High Mach Transient Engine Cycle Code (HiTECC). The HiTECC simulation package models the inlet system, propulsion systems, thermal energy, geometry, nozzle, and fuel systems. This paper discusses the modification and redesign of the simulation package and control system to represent the NASA large-scale inlet model for Combined Cycle Engine mode transition studies, mounted in NASA Glenn s 10- by 10-Foot Supersonic Wind Tunnel. This model will be used for designing and testing candidate control algorithms before implementation.

Keeping the Spirit of Community Partnerships Alive in the Scale Up of HIV/AIDS Prevention: Critical Reflections on the Roll Out of DEBI (Diffusion of Effective Behavioral Interventions)

PubMed Central

Pinto, Rogério M.; Hunter, Joyce; Rapkin, Bruce; Remien, Robert H.

2009-01-01

DEBI, or the Diffusion of Effective Behavioral Interventions is the largest centralized effort to diffuse evidence-based prevention science to fight HIV/AIDS in the United States. DEBI seeks to ensure that the most effective science-based prevention interventions are widely implemented across the country in community-based organizations. Thus, this is a particularly timely juncture in which to critically reflect on the extent to which known principles of community collaboration have guided key processes associated with the DEBI rollout. We review the available evidence on how the dissemination of packaged interventions is necessary but not sufficient for ensuring the success of technology transfer. We consider additional principles that are vital for successful technology transfer, which were not central considerations in the rollout of the DEBI initiative. These issues are: (1) community perceptions of a top-down mode of dissemination; (2) the extent to which local innovations are being embraced, bolstered, or eliminated; and (3) contextual and methodological considerations that shape community preparedness. Consideration of these additional factors is necessary in order to effectively document, manage, and advance the science of dissemination and technology transfer in centralized prevention efforts within and outside of HIV/AIDS. PMID:18612809

Conjugate gradient filtering of instantaneous normal modes, saddles on the energy landscape, and diffusion in liquids.

PubMed

Chowdhary, J; Keyes, T

2002-02-01

Instantaneous normal modes (INM's) are calculated during a conjugate-gradient (CG) descent of the potential energy landscape, starting from an equilibrium configuration of a liquid or crystal. A small number (approximately equal to 4) of CG steps removes all the Im-omega modes in the crystal and leaves the liquid with diffusive Im-omega which accurately represent the self-diffusion constant D. Conjugate gradient filtering appears to be a promising method, applicable to any system, of obtaining diffusive modes and facilitating INM theory of D. The relation of the CG-step dependent INM quantities to the landscape and its saddles is discussed.

A study of the feasibility and performance of an active/passive imager using silicon focal plane arrays and incoherent continuous wave laser diodes

NASA Astrophysics Data System (ADS)

Vollmerhausen, Richard H.

This dissertation describes an active/passive imager (API) that provides reliable, nighttime, target acquisition in a man-portable package with effective visual range of about 4 kilometers. The reflective imagery is easier to interpret than currently used thermal imagery. Also, in the active mode, the API provides performance equivalent to the big-aperture, thermal systems used on weapons platforms like tanks and attack helicopters. This dissertation describes the research needed to demonstrate both the feasibility and utility of the API. Part of the research describes implementation of a silicon focal plane array (SFPA) capable of both active and passive imaging. The passive imaging mode exceeds the nighttime performance of currently fielded, man-portable sensors. Further, when scene illumination is insufficient for passive imaging, the low dark current of SFPA makes it possible to use continuous wave laser diodes (CWLD) to add an active imaging mode. CWLD have advantages of size, efficiency, and improved eye safety when compared to high peak-power diodes. Because of the improved eye safety, the API provides user-demanded features like video output and extended range gates in the active as well as passive imaging modes. Like any other night vision device, the API depends on natural illumination of the scene for passive operation. Although it has been known for decades that "starlight" illumination is actually from diffuse airglow emissions, the research described in this dissertation provides the first estimates of the global and temporal variation of ground illumination due to airglow. A third related element of the current research establishes the impact of atmospheric aerosols on API performance. We know from day experience that atmospheric scattering of sunlight into the imager line-of-sight can blind the imager and drastically degrade performance. Atmospheric scattering of sunlight is extensively covered in the literature. However, previous literature did not cover the impact of atmospheric scattering when the target is diffusely illuminated by airglow.

Air cycle machine for an aircraft environmental control system

NASA Technical Reports Server (NTRS)

Decrisantis, Angelo A. (Inventor); O'Coin, James R. (Inventor); Taddey, Edmund P. (Inventor)

2010-01-01

An ECS system includes an ACM mounted adjacent an air-liquid heat exchanger through a diffuser that contains a diffuser plate. The diffuser plate receives airflow from the ACM which strikes the diffuser plate and flows radially outward and around the diffuser plate and into the air-liquid heat exchanger to provide minimal pressure loss and proper flow distribution into the air-liquid heat exchanger with significantly less packaging space.

Asteroseismic modelling of the solar-like star β Hydri

NASA Astrophysics Data System (ADS)

Doğan, G.; Brandão, I. M.; Bedding, T. R.; Christensen-Dalsgaard, J.; Cunha, M. S.; Kjeldsen, H.

2010-07-01

We present the results of modelling the subgiant star β Hydri using seismic observational constraints. We have computed several grids of stellar evolutionary tracks using the Aarhus STellar Evolution Code (ASTEC, Christensen-Dalsgaard in Astrophys. Space Sci. 316:13, 2008a), with and without helium diffusion and settling. For those models on each track that are located at the observationally determined position of β Hydri in the Hertzsprung-Russell (HR) diagram, we have calculated the oscillation frequencies using the Aarhus adiabatic pulsation package (ADIPLS, Christensen-Dalsgaard in Astrophys. Space Sci. 316:113, 2008b). Applying the near-surface corrections to the calculated frequencies using the empirical law presented by Kjeldsen et al. (Astrophys. J. 683:L175, 2008), we have compared the corrected model frequencies with the observed frequencies of the star. We show that after correcting the frequencies for the near-surface effects, we have a fairly good fit for both l=0 and l=2 frequencies. We also have good agreement between the observed and calculated l=1 mode frequencies, although there is room for improvement in order to fit all the observed mixed modes simultaneously.

ECCD-induced tearing mode stabilization in coupled IPS/NIMROD/GENRAY HPC simulations

NASA Astrophysics Data System (ADS)

Jenkins, Thomas; Kruger, S. E.; Held, E. D.; Harvey, R. W.; Elwasif, W. R.; Schnack, D. D.; SWIM Project Team

2011-10-01

We present developments toward an integrated, predictive model for determining optimal ECCD-based NTM stabilization strategies in ITER. We demonstrate the capability of the SWIM Project's Integrated Plasma Simulator (IPS) framework to choreograph multiple executions of, and data exchanges between, physics codes modeling various spatiotemporal scales of this coupled RF/MHD problem on several thousand HPC processors. As NIMROD evolves fluid equations to model bulk plasma behavior, self-consistent propagation/deposition of RF power in the ensuing plasma profiles is calculated by GENRAY. A third code (QLCALC) then interfaces with computational geometry packages to construct the RF-induced quasilinear diffusion tensor from NIMROD/GENRAY data, and the moments of this tensor (entering as additional terms in NIMROD's fluid equations due to the disparity in RF/MHD spatiotemporal scales) influence the dynamics of current, momentum, and energy evolution. Initial results are shown to correctly capture the physics of magnetic island stabilization [Jenkins et al., PoP 17, 012502 (2010)]; we also discuss the development of a numerical plasma control system for active feedback stabilization of tearing modes. Funded by USDoE SciDAC.

A satellite observation test bed for cloud parameterization development

NASA Astrophysics Data System (ADS)

Lebsock, M. D.; Suselj, K.

2015-12-01

We present an observational test-bed of cloud and precipitation properties derived from CloudSat, CALIPSO, and the the A-Train. The focus of the test-bed is on marine boundary layer clouds including stratocumulus and cumulus and the transition between these cloud regimes. Test-bed properties include the cloud cover and three dimensional cloud fraction along with the cloud water path and precipitation water content, and associated radiative fluxes. We also include the subgrid scale distribution of cloud and precipitation, and radiaitive quantities, which must be diagnosed by a model parameterization. The test-bed further includes meterological variables from the Modern Era Retrospective-analysis for Research and Applications (MERRA). MERRA variables provide the initialization and forcing datasets to run a parameterization in Single Column Model (SCM) mode. We show comparisons of an Eddy-Diffusivity/Mass-FLux (EDMF) parameterization coupled to micorphsycis and macrophysics packages run in SCM mode with observed clouds. Comparsions are performed regionally in areas of climatological subsidence as well stratified by dynamical and thermodynamical variables. Comparisons demonstrate the ability of the EDMF model to capture the observed transitions between subtropical stratocumulus and cumulus cloud regimes.

Evaporation Flux Distribution of Drops on a Hydrophilic or Hydrophobic Flat Surface by Molecular Simulations.

PubMed

Xie, Chiyu; Liu, Guangzhi; Wang, Moran

2016-08-16

The evaporation flux distribution of sessile drops is investigated by molecular dynamic simulations. Three evaporating modes are classified, including the diffusion dominant mode, the substrate heating mode, and the environment heating mode. Both hydrophilic and hydrophobic drop-substrate interactions are considered. To count the evaporation flux distribution, which is position dependent, we proposed an azimuthal-angle-based division method under the assumption of spherical crown shape of drops. The modeling results show that the edge evaporation, i.e., near the contact line, is enhanced for hydrophilic drops in all the three modes. The surface diffusion of liquid molecular absorbed on solid substrate for hydrophilic cases plays an important role as well as the space diffusion on the enhanced evaporation rate at the edge. For hydrophobic drops, the edge evaporation flux is higher for the substrate heating mode, but lower than elsewhere of the drop for the diffusion dominant mode; however, a nearly uniform distribution is found for the environment heating mode. The evidence shows that the temperature distribution inside drops plays a key role in the position-dependent evaporation flux.

NASA DOD Lead Free Electronics Project

NASA Technical Reports Server (NTRS)

Kessel, Kurt R.

2008-01-01

The primary'technical objective of this project is to undertake comprehensive testing to generate information on failure modes/criteria to better understand the reliability of: Packages (e.g., Thin Small Outline Package [TSOP], Ball Grid Array [BGA], Plastic Dual In-line Package [PDIPD assembled and reworked with lead-free alloys Packages (e.g., TSOP, BGA, PDIP) assembled and reworked with mixed (lead/lead-free) alloys.

An AMR capable finite element diffusion solver for ALE hydrocodes [An AMR capable diffusion solver for ALE-AMR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fisher, A. C.; Bailey, D. S.; Kaiser, T. B.

2015-02-01

Here, we present a novel method for the solution of the diffusion equation on a composite AMR mesh. This approach is suitable for including diffusion based physics modules to hydrocodes that support ALE and AMR capabilities. To illustrate, we proffer our implementations of diffusion based radiation transport and heat conduction in a hydrocode called ALE-AMR. Numerical experiments conducted with the diffusion solver and associated physics packages yield 2nd order convergence in the L 2 norm.

Effects of melamine formaldehyde resin and CaCO3 diffuser-loaded encapsulation on correlated color temperature uniformity of phosphor-converted LEDs.

PubMed

Yang, Liang; Lv, Zhicheng; Jiaojiao, Yuan; Liu, Sheng

2013-08-01

Phosphor-free dispensing is the most widely used LED packaging method, but this method results in poor quality in angular CCT uniformity. This study proposes a diffuser-loaded encapsulation to solve the problem; the effects of melamine formaldehyde (MF) resin and CaCO3 loaded encapsulation on correlated color temperature (CCT) uniformity and luminous efficiency reduction of the phosphor-converted LEDs are investigated. Results reveal that MF resin loaded encapsulation has better light diffusion performance compared to MF resin loaded encapsulation at the same diffuser concentration, but CaCO3 loaded encapsulation has better luminous efficiency maintenance. The improvements in angular color uniformity for the LEDs emitting with MF resin and CaCO3 loaded encapsulation can be explained by the increase in photon scattering. The utility of this low cost and controllable mineral diffuser packaging method provides a practical approach for enhancing the angular color uniformity of LEDs. The diffuser mass ratio of 1% MF resin or 10% CaCO3 is the optimum condition to obtain low angular CCT variance and high luminous efficiency.

PANDA: a pipeline toolbox for analyzing brain diffusion images.

PubMed

Cui, Zaixu; Zhong, Suyu; Xu, Pengfei; He, Yong; Gong, Gaolang

2013-01-01

Diffusion magnetic resonance imaging (dMRI) is widely used in both scientific research and clinical practice in in-vivo studies of the human brain. While a number of post-processing packages have been developed, fully automated processing of dMRI datasets remains challenging. Here, we developed a MATLAB toolbox named "Pipeline for Analyzing braiN Diffusion imAges" (PANDA) for fully automated processing of brain diffusion images. The processing modules of a few established packages, including FMRIB Software Library (FSL), Pipeline System for Octave and Matlab (PSOM), Diffusion Toolkit and MRIcron, were employed in PANDA. Using any number of raw dMRI datasets from different subjects, in either DICOM or NIfTI format, PANDA can automatically perform a series of steps to process DICOM/NIfTI to diffusion metrics [e.g., fractional anisotropy (FA) and mean diffusivity (MD)] that are ready for statistical analysis at the voxel-level, the atlas-level and the Tract-Based Spatial Statistics (TBSS)-level and can finish the construction of anatomical brain networks for all subjects. In particular, PANDA can process different subjects in parallel, using multiple cores either in a single computer or in a distributed computing environment, thus greatly reducing the time cost when dealing with a large number of datasets. In addition, PANDA has a friendly graphical user interface (GUI), allowing the user to be interactive and to adjust the input/output settings, as well as the processing parameters. As an open-source package, PANDA is freely available at http://www.nitrc.org/projects/panda/. This novel toolbox is expected to substantially simplify the image processing of dMRI datasets and facilitate human structural connectome studies.

PANDA: a pipeline toolbox for analyzing brain diffusion images

PubMed Central

Cui, Zaixu; Zhong, Suyu; Xu, Pengfei; He, Yong; Gong, Gaolang

2013-01-01

Diffusion magnetic resonance imaging (dMRI) is widely used in both scientific research and clinical practice in in-vivo studies of the human brain. While a number of post-processing packages have been developed, fully automated processing of dMRI datasets remains challenging. Here, we developed a MATLAB toolbox named “Pipeline for Analyzing braiN Diffusion imAges” (PANDA) for fully automated processing of brain diffusion images. The processing modules of a few established packages, including FMRIB Software Library (FSL), Pipeline System for Octave and Matlab (PSOM), Diffusion Toolkit and MRIcron, were employed in PANDA. Using any number of raw dMRI datasets from different subjects, in either DICOM or NIfTI format, PANDA can automatically perform a series of steps to process DICOM/NIfTI to diffusion metrics [e.g., fractional anisotropy (FA) and mean diffusivity (MD)] that are ready for statistical analysis at the voxel-level, the atlas-level and the Tract-Based Spatial Statistics (TBSS)-level and can finish the construction of anatomical brain networks for all subjects. In particular, PANDA can process different subjects in parallel, using multiple cores either in a single computer or in a distributed computing environment, thus greatly reducing the time cost when dealing with a large number of datasets. In addition, PANDA has a friendly graphical user interface (GUI), allowing the user to be interactive and to adjust the input/output settings, as well as the processing parameters. As an open-source package, PANDA is freely available at http://www.nitrc.org/projects/panda/. This novel toolbox is expected to substantially simplify the image processing of dMRI datasets and facilitate human structural connectome studies. PMID:23439846

THE IMPLICIT CONTRIBUTION OF SLAB MODES TO THE PERPENDICULAR DIFFUSION COEFFICIENT OF PARTICLES INTERACTING WITH TWO-COMPONENT TURBULENCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shalchi, A., E-mail: andreasm4@yahoo.com

2016-10-20

We explore the transport of energetic particles in two-component turbulence in which the stochastic magnetic field is assumed to be a superposition of slab and two-dimensional modes. It is known that in magnetostatic slab turbulence, the motion of particles across the mean magnetic field is subdiffusive. If a two-dimensional component is added, diffusion is recovered. It was also shown before that in two-component turbulence, the slab modes do not explicitly contribute to the perpendicular diffusion coefficient. In the current paper, the implicit contribution of slab modes is explored and it is shown that this contribution leads to a reduction ofmore » the perpendicular diffusion coefficient. This effect improves the agreement between simulations and analytical theory. Furthermore, the obtained results are relevant for investigations of diffusive shock acceleration.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanz, Alejandro; Ezquerra, Tiberio A.; Nogales, Aurora, E-mail: aurora.nogales@csic.es

The dynamics of lower disorder-order temperature diblock copolymer leading to phase separation has been observed by X ray photon correlation spectroscopy. Two different modes have been characterized. A non-diffusive mode appears at temperatures below the disorder to order transition, which can be associated to compositional fluctuations, that becomes slower as the interaction parameter increases, in a similar way to the one observed for diblock copolymers exhibiting phase separation upon cooling. At temperatures above the disorder to order transition T{sub ODT}, the dynamics becomes diffusive, indicating that after phase separation in Lower Disorder-Order Transition (LDOT) diblock copolymers, the diffusion of chainmore » segments across the interface is the governing dynamics. As the segregation is stronger, the diffusive process becomes slower. Both observed modes have been predicted by the theory describing upper order-disorder transition systems, assuming incompressibility. However, the present results indicate that the existence of these two modes is more universal as they are present also in compressible diblock copolymers exhibiting a lower disorder-order transition. No such a theory describing the dynamics in LDOT block copolymers is available, and these experimental results may offer some hints to understanding the dynamics in these systems. The dynamics has also been studied in the ordered state, and for the present system, the non-diffusive mode disappears and only a diffusive mode is observed. This mode is related to the transport of segment in the interphase, due to the weak segregation on this system.« less

NASA-DoD Lead-Free Electronics Project

NASA Technical Reports Server (NTRS)

Kessel, Kurt R.

2009-01-01

The primary technical objective of this project is to undertake comprehensive testing to generate information on failure modes/criteria to better understand the reliability of: (1) Packages (e.g., Thin Small Outline Package [TSOP], Ball Grid Array [BGA], Plastic Dual In-line Package [PDIP]) assembled and reworked with lead-free alloys, (2) Packages (e.g., TSOP, BGA, PDIP) assembled and reworked with mixed (lead/lead-free) alloys.

Characterization of Ultrasound Energy Diffusion Due to Small-Size Damage on an Aluminum Plate Using Piezoceramic Transducers

PubMed Central

Lu, Guangtao; Feng, Qian; Li, Yourong; Wang, Hao; Song, Gangbing

2017-01-01

During the propagation of ultrasonic waves in structures, there is usually energy loss due to ultrasound energy diffusion and dissipation. The aim of this research is to characterize the ultrasound energy diffusion that occurs due to small-size damage on an aluminum plate using piezoceramic transducers, for the future purpose of developing a damage detection algorithm. The ultrasonic energy diffusion coefficient is related to the damage distributed in the medium. Meanwhile, the ultrasonic energy dissipation coefficient is related to the inhomogeneity of the medium. Both are usually employed to describe the characteristics of ultrasound energy diffusion. The existence of multimodes of Lamb waves in metallic plate structures results in the asynchronous energy transport of different modes. The mode of Lamb waves has a great influence on ultrasound energy diffusion as a result, and thus has to be chosen appropriately. In order to study the characteristics of ultrasound energy diffusion in metallic plate structures, an experimental setup of an aluminum plate with a through-hole, whose diameter varies from 0.6 mm to 1.2 mm, is used as the test specimen with the help of piezoceramic transducers. The experimental results of two categories of damages at different locations reveal that the existence of damage changes the energy transport between the actuator and the sensor. Also, when there is only one dominate mode of Lamb wave excited in the structure, the ultrasound energy diffusion coefficient decreases approximately linearly with the diameter of the simulated damage. Meanwhile, the ultrasonic energy dissipation coefficient increases approximately linearly with the diameter of the simulated damage. However, when two or more modes of Lamb waves are excited, due to the existence of different group velocities between the different modes, the energy transport of the different modes is asynchronous, and the ultrasonic energy diffusion is not strictly linear with the size of the damage. Therefore, it is recommended that only one dominant mode of Lamb wave should be excited during the characterization process, in order to ensure that the linear relationship between the damage size and the characteristic parameters is maintained. In addition, the findings from this paper demonstrate the potential of developing future damage detection algorithms using the linear relationships between damage size and the ultrasound energy diffusion coefficient or ultrasonic energy dissipation coefficient when a single dominant mode is excited. PMID:29207530

Dynamical modes of two almost identical chemical oscillators connected via both pulsatile and diffusive coupling.

PubMed

Safonov, Dmitry A; Vanag, Vladimir K

2018-05-03

The dynamical regimes of two almost identical Belousov-Zhabotinsky oscillators with both pulsatile (with time delay) and diffusive coupling have been studied theoretically with the aid of ordinary differential equations for four combinations of these types of coupling: inhibitory diffusive and inhibitory pulsatile (IDIP); excitatory diffusive and inhibitory pulsatile; inhibitory diffusive and excitatory pulsatile; and finally, excitatory diffusive and excitatory pulsatile (EDEP). The combination of two types of coupling creates a condition for new feedback, which promotes new dynamical modes for the IDIP and EDEP coupling.

48 CFR 47.305-1 - Solicitation requirements.

Code of Federal Regulations, 2012 CFR

2012-10-01

... much of the following data as is applicable to the particular acquisition: (a) Modes of transportation... packaging; e.g., box, carton, crate, drum, bundle, skids, and when applicable, package number from the...

48 CFR 47.305-1 - Solicitation requirements.

Code of Federal Regulations, 2013 CFR

2013-10-01

... much of the following data as is applicable to the particular acquisition: (a) Modes of transportation... packaging; e.g., box, carton, crate, drum, bundle, skids, and when applicable, package number from the...

48 CFR 47.305-1 - Solicitation requirements.

Code of Federal Regulations, 2014 CFR

2014-10-01

... much of the following data as is applicable to the particular acquisition: (a) Modes of transportation... packaging; e.g., box, carton, crate, drum, bundle, skids, and when applicable, package number from the...

48 CFR 47.305-1 - Solicitation requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... much of the following data as is applicable to the particular acquisition: (a) Modes of transportation... packaging; e.g., box, carton, crate, drum, bundle, skids, and when applicable, package number from the...

48 CFR 47.305-1 - Solicitation requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... much of the following data as is applicable to the particular acquisition: (a) Modes of transportation... packaging; e.g., box, carton, crate, drum, bundle, skids, and when applicable, package number from the...

Raman spectroscopy, electronic microscopy and SPME-GC-MS to elucidate the mode of action of a new antimicrobial food packaging material.

PubMed

Clemente, Isabel; Aznar, Margarita; Salafranca, Jesús; Nerín, Cristina

2017-02-01

One critical challenge when developing a new antimicrobial packaging material is to demonstrate the mode of action of the antimicrobials incorporated into the packaging. For this task, several analytical techniques as well as microbiology are required. In this work, the antimicrobial properties of benzyl isothiocyanate, allyl isothiocyanate and essential oils of cinnamon and oregano against several moulds and bacteria have been evaluated. Benzyl isothiocyanate showed the highest antimicrobial activity and it was selected for developing the new active packaging material. Scanning electron microscopy and Raman spectroscopy were successfully used to demonstrate the mode of action of benzyl isothiocyanate on Escherichia coli. Bacteria exhibited external modifications such as oval shape and the presence of septum surface, but they did not show any disruption or membrane damage. To provide data on the in vitro action of benzyl isothiocyanate and the presence of inhibition halos, the transfer mechanism to the cells was assessed using solid-phase microextraction-gas chromatography-mass spectrometry. Based on the transfer system, action mechanism and its stronger antimicrobial activity, benzyl isothiocyanate was incorporated to two kinds of antimicrobial labels. The labels were stable and active for 140 days against two mould producers of ochratoxin A; Penicillium verrucosum is more sensitive than Aspergillus ochraceus. Details about the analytical techniques and the results obtained are shown and discussed. Graphical Abstract Antimicrobial evaluation of pure compounds, incorporation in the packaging and study for mode of action on S. coli by Raman, SEM and SPME-GC-MS.

One-dimensional energetic particle quasilinear diffusion for realistic TAE instabilities

NASA Astrophysics Data System (ADS)

Duarte, Vinicius; Ghantous, Katy; Berk, Herbert; Gorelenkov, Nikolai

2014-10-01

Owing to the proximity of the characteristic phase (Alfvén) velocity and typical energetic particle (EP) superthermal velocities, toroidicity-induced Alfvén eigenmodes (TAEs) can be resonantly destabilized endangering the plasma performance. Thus, it is of ultimate importance to understand the deleterious effects on the confinement resulting from fast ion driven instabilities expected in fusion-grade plasmas. We propose to study the interaction of EPs and TAEs using a line broadened quasilinear model, which captures the interaction in both regimes of isolated and overlapping modes. The resonance particles diffuse in the phase space where the problem essentially reduces to one dimension with constant kinetic energy and the diffusion mainly along the canonical toroidal angular momentum. Mode structure and wave particle resonances are computed by the NOVA code and are used in a quasilinear diffusion code that is being written to study the evolution of the distribution function, under the assumption that they can be considered virtually unalterable during the diffusion. A new scheme for the resonant particle diffusion is being proposed that builds on the 1-D nature of the diffusion from a single mode, which leads to a momentum conserving difference scheme even when there is mode overlap.

Copper Gas Diffusers For Purging Line-Focus Laser Welds

NASA Technical Reports Server (NTRS)

Fonteyne, Steve L.; Hosking, Timothy J.; Shelley, D. Mark

1996-01-01

Modified flow diffusers built for inert-gas purging of welds made with 5-kW CO(2) lasers operating with line-focus optics in conduction mode instead of with point-focus optics in customary keyhole mode. Diffusers made of copper components brazed together, robust enough to withstand strong reflections of line-focused laser energy.

Packaging-induced failure of semiconductor lasers and optical telecommunications components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharps, J.A.

1996-12-31

Telecommunications equipment for field deployment generally have specified lifetimes of > 100,000 hr. To achieve this high reliability, it is common practice to package sensitive components in hermetic, inert gas environments. The intent is to protect components from particulate and organic contamination, oxidation, and moisture. However, for high power density 980 nm diode lasers used in optical amplifiers, the authors found that hermetic, inert gas packaging induced a failure mode not observed in similar, unpackaged lasers. They refer to this failure mode as packaging-induced failure, or PIF. PIF is caused by nanomole amounts of organic contamination which interact with highmore » intensity 980 nm light to form solid deposits over the emitting regions of the lasers. These deposits absorb 980 nm light, causing heating of the laser, narrowing of the band gap, and eventual thermal runaway. The authors have found PIF is averted by packaging with free O{sub 2} and/or a getter material that sequesters organics.« less

PAINeT: An object-oriented software package for simulations of flow-field, transport coefficients and flux terms in non-equilibrium gas mixture flows

NASA Astrophysics Data System (ADS)

Istomin, V. A.

2018-05-01

The software package Planet Atmosphere Investigator of Non-equilibrium Thermodynamics (PAINeT) has been devel-oped for studying the non-equilibrium effects associated with electronic excitation, chemical reactions and ionization. These studies are necessary for modeling process in shock tubes, in high enthalpy flows, in nozzles or jet engines, in combustion and explosion processes, in modern plasma-chemical and laser technologies. The advantages and possibilities of the package implementation are stated. Within the framework of the package implementation, based on kinetic theory approximations (one-temperature and state-to-state approaches), calculations are carried out, and the limits of applicability of a simplified description of shock-heated air flows and any other mixtures chosen by the user are given. Using kinetic theory algorithms, a numerical calculation of the heat fluxes and relaxation terms can be performed, which is necessary for further comparison of engineering simulation with experi-mental data. The influence of state-to-state distributions over electronic energy levels on the coefficients of thermal conductivity, diffusion, heat fluxes and diffusion velocities of the components of various gas mixtures behind shock waves is studied. Using the software package the accuracy of different approximations of the kinetic theory of gases is estimated. As an example state-resolved atomic ionized mixture of N/N+/O/O+/e- is considered. It is shown that state-resolved diffusion coefficients of neutral and ionized species vary from level to level. Comparing results of engineering applications with those given by PAINeT, recommendations for adequate models selection are proposed.

Thermal diffusion behavior of nonionic surfactants in water.

PubMed

Ning, Hui; Kita, Rio; Kriegs, Hartmut; Luettmer-Strathmann, Jutta; Wiegand, Simone

2006-06-08

We studied the thermal diffusion behavior of hexaethylene glycol monododecyl ether (C12E6) in water by means of thermal diffusion forced Rayleigh scattering (TDFRS) and determined Soret coefficients, thermal diffusion coefficients, and diffusion constants at different temperatures and concentrations. At low surfactant concentrations, the measured Soret coefficient is positive, which implies that surfactant micelles move toward the cold region in a temperature gradient. For C12E6/water at a high surfactant concentration of w1 = 90 wt % and a temperature of T = 25 degrees C, however, a negative Soret coefficient S(T) was observed. Because the concentration part of the TDFRS diffraction signal for binary systems is expected to consist of a single mode, we were surprised to find a second, slow mode for C12E6/water system in a certain temperature and concentration range. To clarify the origin of this second mode, we investigated also, tetraethylene glycol monohexyl ether (C6E4), tetraethylene glycol monooctyl ether (C8E4), pentaethylene glycol monododecyl ether (C12E5), and octaethylene glycol monohexadecyl ether (C16E8) and compared the results with the previous results for octaethylene glycol monodecyl ether (C10E8). Except for C6E4 and C10E8, a second slow mode was observed in all systems usually for state points close to the phase boundary. The diffusion coefficient and Soret coefficient derived from the fast mode can be identified as the typical mutual diffusion and Soret coefficients of the micellar solutions and compare well with the independently determined diffusion coefficients in a dynamic light scattering experiment. Experiments with added salt show that the slow mode is suppressed by the addition of w(NaCl) = 0.02 mol/L sodium chloride. This suggests that the slow mode is related to the small amount of absorbing ionic dye, less than 10(-5) by weight, which is added in TDFRS experiments to create a temperature grating. The origin of the slow mode of the TDFRS signal will be tentatively interpreted in terms of a ternary mixture of neutral micelles, dye-charged micelles, and water.

THEMIS Observations of the Magnetopause Electron Diffusion Region: Large Amplitude Waves and Heated Electrons

NASA Technical Reports Server (NTRS)

Tang, Xiangwei; Cattell, Cynthia; Dombeck, John; Dai, Lei; Wilson, Lynn B. III; Breneman, Aaron; Hupack, Adam

2013-01-01

We present the first observations of large amplitude waves in a well-defined electron diffusion region based on the criteria described by Scudder et al at the subsolar magnetopause using data from one Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellite. These waves identified as whistler mode waves, electrostatic solitary waves, lower hybrid waves, and electrostatic electron cyclotron waves, are observed in the same 12 s waveform capture and in association with signatures of active magnetic reconnection. The large amplitude waves in the electron diffusion region are coincident with abrupt increases in electron parallel temperature suggesting strong wave heating. The whistler mode waves, which are at the electron scale and which enable us to probe electron dynamics in the diffusion region were analyzed in detail. The energetic electrons (approx. 30 keV) within the electron diffusion region have anisotropic distributions with T(sub e(right angle))/T(sub e(parallel)) > 1 that may provide the free energy for the whistler mode waves. The energetic anisotropic electrons may be produced during the reconnection process. The whistler mode waves propagate away from the center of the "X-line" along magnetic field lines, suggesting that the electron diffusion region is a possible source region of the whistler mode waves.

In-Package Chemistry Abstraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

E. Thomas

2004-11-09

This report was developed in accordance with the requirements in ''Technical Work Plan for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]). The purpose of the in-package chemistry model is to predict the bulk chemistry inside of a breached waste package and to provide simplified expressions of that chemistry as function of time after breach to Total Systems Performance Assessment for the License Application (TSPA-LA). The scope of this report is to describe the development and validation of the in-package chemistry model. The in-package model is a combination of two models, amore » batch reactor model that uses the EQ3/6 geochemistry-modeling tool, and a surface complexation model that is applied to the results of the batch reactor model. The batch reactor model considers chemical interactions of water with the waste package materials and the waste form for commercial spent nuclear fuel (CSNF) waste packages and codisposed waste packages that contain both high-level waste glass (HLWG) and DOE spent fuel. The surface complexation model includes the impact of fluid-surface interactions (i.e., surface complexation) on the resulting fluid composition. The model examines two types of water influx: (1) the condensation of water vapor that diffuses into the waste package, and (2) seepage water that enters the waste package from the drift as a liquid. (1) Vapor Influx Case: The condensation of vapor onto the waste package internals is simulated as pure H2O and enters at a rate determined by the water vapor pressure for representative temperature and relative humidity conditions. (2) Water Influx Case: The water entering a waste package from the drift is simulated as typical groundwater and enters at a rate determined by the amount of seepage available to flow through openings in a breached waste package. TSPA-LA uses the vapor influx case for the nominal scenario for simulations where the waste package has been breached but the drip shield remains intact, so all of the seepage flow is diverted from the waste package. The chemistry from the vapor influx case is used to determine the stability of colloids and the solubility of radionuclides available for transport by diffusion, and to determine the degradation rates for the waste forms. TSPA-LA uses the water influx case for the seismic scenario, where the waste package has been breached and the drip shield has been damaged such that seepage flow is actually directed into the waste package. The chemistry from the water influx case that is a function of the flow rate is used to determine the stability of colloids and the solubility of radionuclides available for transport by diffusion and advection, and to determine the degradation rates for the CSNF and HLW glass. TSPA-LA does not use this model for the igneous scenario. Outputs from the in-package chemistry model implemented inside TSPA-LA include pH, ionic strength, and total carbonate concentration. These inputs to TSPA-LA will be linked to the following principle factors: dissolution rates of the CSNF and HLWG, dissolved concentrations of radionuclides, and colloid generation.« less

Effect of chlorine dioxide gas on physical, thermal, mechanical, and barrier properties of p[olymeric packaging materials

USDA-ARS?s Scientific Manuscript database

In the first part of our study we determined permeability, diffusion, and solubility coefficients of gaseous chlorine dioxide (ClO2) through the following packaging material: biaxial-oriented polypropylene (BOPP); polyethylene terephthalate (PET); poly lactic acid (PLA); multilayer structure of ethy...

Installation package for a solar heating system

NASA Technical Reports Server (NTRS)

1978-01-01

Installation information is given for a solar heating system installed in Concho Indian School at El Reno, Oklahoma. This package includes a system Operation and Maintenance Manual, hardware brochures, schematics, system operating modes and drawings.

A software package for interactive motor unit potential classification using fuzzy k-NN classifier.

PubMed

Rasheed, Sarbast; Stashuk, Daniel; Kamel, Mohamed

2008-01-01

We present an interactive software package for implementing the supervised classification task during electromyographic (EMG) signal decomposition process using a fuzzy k-NN classifier and utilizing the MATLAB high-level programming language and its interactive environment. The method employs an assertion-based classification that takes into account a combination of motor unit potential (MUP) shapes and two modes of use of motor unit firing pattern information: the passive and the active modes. The developed package consists of several graphical user interfaces used to detect individual MUP waveforms from a raw EMG signal, extract relevant features, and classify the MUPs into motor unit potential trains (MUPTs) using assertion-based classifiers.

Correlations, soliton modes, and non-Hermitian linear mode transmutation in the one-dimensional noisy Burgers equation.

PubMed

Fogedby, Hans C

2003-08-01

Using the previously developed canonical phase space approach applied to the noisy Burgers equation in one dimension, we discuss in detail the growth morphology in terms of nonlinear soliton modes and superimposed linear modes. We moreover analyze the non-Hermitian character of the linear mode spectrum and the associated dynamical pinning, and mode transmutation from diffusive to propagating behavior induced by the solitons. We discuss the anomalous diffusion of growth modes, switching and pathways, correlations in the multisoliton sector, and in detail the correlations and scaling properties in the two-soliton sector.

Turing patterns and a stochastic individual-based model for predator-prey systems

NASA Astrophysics Data System (ADS)

Nagano, Seido

2012-02-01

Reaction-diffusion theory has played a very important role in the study of pattern formations in biology. However, a group of individuals is described by a single state variable representing population density in reaction-diffusion models and interaction between individuals can be included only phenomenologically. Recently, we have seamlessly combined individual-based models with elements of reaction-diffusion theory. To include animal migration in the scheme, we have adopted a relationship between the diffusion and the random numbers generated according to a two-dimensional bivariate normal distribution. Thus, we have observed the transition of population patterns from an extinction mode, a stable mode, or an oscillatory mode to the chaotic mode as the population growth rate increases. We show our phase diagram of predator-prey systems and discuss the microscopic mechanism for the stable lattice formation in detail.

Diffusion of Radionuclides in Concrete and Soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mattigod, Shas V.; Wellman, Dawn M.; Bovaird, Chase C.

2012-04-25

One of the methods being considered for safely disposing of Category 3 low-level radioactive wastes is to encase the waste in concrete. Such concrete encasement would contain and isolate the waste packages from the hydrologic environment and would act as an intrusion barrier. Any failure of concrete encasement may result in water intrusion and consequent mobilization of radionuclides from the waste packages. The mobilized radionuclides may escape from the encased concrete by mass flow and/or diffusion and move into the surrounding subsurface environment. Therefore, it is necessary to assess the performance of the concrete encasement structure and the ability ofmore » the surrounding soil to retard radionuclide migration. The objective of our study was to measure the diffusivity of Re, Tc and I in concrete containment and the surrounding vadose zone soil. Effects of carbonation, presence of metallic iron, and fracturing of concrete and the varying moisture contents in soil on the diffusivities of Tc and I were evaluated.« less

NOx Sensor for Direct Injection Emission Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Betteridge, William J

2006-02-28

The Electricore/Delphi team continues to leverage the electrochemical planar sensor technology that has produced stoichiometric planar and wide range oxygen sensors as the basis for development of a NOx sensor. Zirconia cell technology with an integrated heater will provide the foundation for the sensor structure. Proven materials and packaging technology will help to ensure a cost-effective approach to the manufacture of this sensor. The electronics technique and interface is considered to be an area where new strategies need to be employed to produce higher S/N ratios of the NOx signal with emphasis on signal stability over time for robustness andmore » durability Both continuous mode and pulse mode control techniques are being evaluated. Packaging the electronics requires careful design and circuit partitioning so that only the necessary signal conditioning electronics are coupled directly in the wiring harness, while the remainder is situated within the ECM for durability and costs reasons. This task continues to be on hold due to the limitation that the definition of the interface electronics was unavailable until very late in the project. The sense element is based on the amperometric method utilizing integrated alumina and zirconia ceramics. Precious metal electrodes are used to form the integrated heater, the cell electrodes and leads. Inside the actual sense cell structure, it is first necessary to separate NOx from the remaining oxygen constituents of the exhaust, without reducing the NOx. Once separated, the NOx will be measured using a measurement cell. Development or test coupons have been used to facilitate material selection and refinement, cell, diffusion barrier, and chamber development. The sense element currently requires elaborate interconnections. To facilitate a robust durable connection, mechanical and metallurgical connections are under investigation. Materials and process refinements continue to play an important role in the development of the sensor.« less

Slow relaxation mode in concentrated oil-in-water microemulsions consisting of repulsive droplets

NASA Astrophysics Data System (ADS)

Hattori, Y.; Ushiki, H.; Courbin, L.; Panizza, P.

2007-02-01

The present contribution reports on the observation of two diffusive relaxation modes in a concentrated microemulsion made of repulsive droplets. These two modes can be interpreted in the frame of Weissman’s and Pusey’s theoretical pioneering works. The fast mode is associated to the collective diffusion of droplets whereas the slow one corresponds to the relaxation of droplet concentration fluctuations associated with composition and/or size. We show that (i) repulsive interactions considerably slow down the latter and (ii) a generalized Stokes Einstein relationship between its coefficient of diffusion and the Newtonian viscosity of the solutions, similar to the Walden’s rule for electrolytes, holds for concentrated microemulsion systems made of repulsive droplets.

Power module packaging with double sided planar interconnection and heat exchangers

DOEpatents

Liang, Zhenxian; Marlino, Laura D.; Ning, Puqi; Wang, Fei

2015-05-26

A double sided cooled power module package having a single phase leg topology includes two IGBT and two diode semiconductor dies. Each IGBT die is spaced apart from a diode semiconductor die, forming a switch unit. Two switch units are placed in a planar face-up and face-down configuration. A pair of DBC or other insulated metallic substrates is affixed to each side of the planar phase leg semiconductor dies to form a sandwich structure. Attachment layers are disposed on outer surfaces of the substrates and two heat exchangers are affixed to the substrates by rigid bond layers. The heat exchangers, made of copper or aluminum, have passages for carrying coolant. The power package is manufactured in a two-step assembly and heating process where direct bonds are formed for all bond layers by soldering, sintering, solid diffusion bonding or transient liquid diffusion bonding, with a specially designed jig and fixture.

Cross-diffusion-induced subharmonic spatial resonances in a predator-prey system

NASA Astrophysics Data System (ADS)

Gambino, G.; Lombardo, M. C.; Sammartino, M.

2018-01-01

In this paper we investigate the complex dynamics originated by a cross-diffusion-induced subharmonic destabilization of the fundamental subcritical Turing mode in a predator-prey reaction-diffusion system. The model we consider consists of a two-species Lotka-Volterra system with linear diffusion and a nonlinear cross-diffusion term in the predator equation. The taxis term in the search strategy of the predator is responsible for the onset of complex dynamics. In fact, our model does not exhibit any Hopf or wave instability, and on the basis of the linear analysis one should only expect stationary patterns; nevertheless, the presence of the nonlinear cross-diffusion term is able to induce a secondary instability: due to a subharmonic spatial resonance, the stationary primary branch bifurcates to an out-of-phase oscillating solution. Noticeably, the strong resonance between the harmonic and the subharmonic is able to generate the oscillating pattern albeit the subharmonic is below criticality. We show that, as the control parameter is varied, the oscillating solution (sub T mode) can undergo a sequence of secondary instabilities, generating a transition toward chaotic dynamics. Finally, we investigate the emergence of sub T -mode solutions on two-dimensional domains: when the fundamental mode describes a square pattern, subharmonic resonance originates oscillating square patterns. In the case of subcritical Turing hexagon solutions, the internal interactions with a subharmonic mode are able to generate the so-called "twinkling-eyes" pattern.

Nonlinear ELM simulations based on a nonideal peeling–ballooning model using the BOUT++ code

DOE PAGES

Xu, X. Q.; Dudson, B. D.; Snyder, P. B.; ...

2011-09-23

A minimum set of equations based on the peeling–ballooning (P–B) model with nonideal physics effects (diamagnetic drift, E × B drift, resistivity and anomalous electron viscosity) is found to simulate pedestal collapse when using the BOUT++ simulation code, developed in part from the original fluid edge code BOUT. Linear simulations of P–B modes find good agreement in growth rate and mode structure with ELITE calculations. The influence of the E × B drift, diamagnetic drift, resistivity, anomalous electron viscosity, ion viscosity and parallel thermal diffusivity on P–B modes is being studied; we find that (1) the diamagnetic drift and Emore » × B drift stabilize the P–B mode in a manner consistent with theoretical expectations; (2) resistivity destabilizes the P–B mode, leading to resistive P–B mode; (3) anomalous electron and parallel ion viscosities destabilize the P–B mode, leading to a viscous P–B mode; (4) perpendicular ion viscosity and parallel thermal diffusivity stabilize the P–B mode. With addition of the anomalous electron viscosity under the assumption that the anomalous kinematic electron viscosity is comparable to the anomalous electron perpendicular thermal diffusivity, or the Prandtl number is close to unity, it is found from nonlinear simulations using a realistic high Lundquist number that the pedestal collapse is limited to the edge region and the ELM size is about 5–10% of the pedestal stored energy. Furthermore, this is consistent with many observations of large ELMs. The estimated island size is consistent with the size of fast pedestal pressure collapse. In the stable α-zones of ideal P–B modes, nonlinear simulations of viscous ballooning modes or current-diffusive ballooning mode (CDBM) for ITER H-mode scenarios are presented.« less

Parameter analysis on the ultrasonic TSV-filling process and electrochemical characters

NASA Astrophysics Data System (ADS)

Wang, Fuliang; Ren, Xinyu; Wang, Yan; Zeng, Peng; Zhou, Zhaohua; Xiao, Hongbin; Zhu, Wenhui

2017-10-01

As one of the key technologies in 3D packaging, through silicon via (TSV) interconnection technology has become a focus recently. In this paper, an electrodeposition method for TSV filling with the assistance of ultrasound and additives are introduced. Two important parameters i.e. current density and ultrasonic power are studied for TSV filling process and electrochemical properties. It is found that ultrasound can improve the quality of TSV-filling and change the TSV-filling mode. The experimental results also indicate that the filling rate enhances more significantly with decreasing current density under ultrasonic conditions than under silent conditions. In addition, according to the voltammetry curve, the increase of ultrasonic power can significantly increase the current density of cupric reduction, and decrease the thickness of diffusion layer. So that the reduction speed of copper ions is accelerated, resulting in a higher TSV-filling rate.

Re-evaluation of model-based light-scattering spectroscopy for tissue spectroscopy

PubMed Central

Lau, Condon; Šćepanović, Obrad; Mirkovic, Jelena; McGee, Sasha; Yu, Chung-Chieh; Fulghum, Stephen; Wallace, Michael; Tunnell, James; Bechtel, Kate; Feld, Michael

2009-01-01

Model-based light scattering spectroscopy (LSS) seemed a promising technique for in-vivo diagnosis of dysplasia in multiple organs. In the studies, the residual spectrum, the difference between the observed and modeled diffuse reflectance spectra, was attributed to single elastic light scattering from epithelial nuclei, and diagnostic information due to nuclear changes was extracted from it. We show that this picture is incorrect. The actual single scattering signal arising from epithelial nuclei is much smaller than the previously computed residual spectrum, and does not have the wavelength dependence characteristic of Mie scattering. Rather, the residual spectrum largely arises from assuming a uniform hemoglobin distribution. In fact, hemoglobin is packaged in blood vessels, which alters the reflectance. When we include vessel packaging, which accounts for an inhomogeneous hemoglobin distribution, in the diffuse reflectance model, the reflectance is modeled more accurately, greatly reducing the amplitude of the residual spectrum. These findings are verified via numerical estimates based on light propagation and Mie theory, tissue phantom experiments, and analysis of published data measured from Barrett’s esophagus. In future studies, vessel packaging should be included in the model of diffuse reflectance and use of model-based LSS should be discontinued. PMID:19405760

Investigating Whistler Mode Wave Diffusion Coefficients at Mars

NASA Astrophysics Data System (ADS)

Shane, A. D.; Liemohn, M. W.; Xu, S.; Florie, C.

2017-12-01

Observations of electron pitch angle distributions have suggested collisions are not the only pitch angle scattering process occurring in the Martian ionosphere. This unknown scattering process is causing high energy electrons (>100 eV) to become isotropized. Whistler mode waves are one pitch angle scattering mechanism known to preferentially scatter high energy electrons in certain plasma regimes. The distribution of whistler mode wave diffusion coefficients are dependent on the background magnetic field strength and thermal electron density, as well as the frequency and wave normal angle of the wave. We have solved for the whistler mode wave diffusion coefficients using the quasi-linear diffusion equations and have integrated them into a superthermal electron transport (STET) model. Preliminary runs have produced results that qualitatively match the observed electron pitch angle distributions at Mars. We performed parametric sweeps over magnetic field, thermal electron density, wave frequency, and wave normal angle to understand the relationship between the plasma parameters and the diffusion coefficient distributions, but also to investigate what regimes whistler mode waves scatter only high energy electrons. Increasing the magnetic field strength and lowering the thermal electron density shifts the distribution of diffusion coefficients toward higher energies and lower pitch angles. We have created an algorithm to identify Mars Atmosphere Volatile and EvolutioN (MAVEN) observations of high energy isotropic pitch angle distributions in the Martian ionosphere. We are able to map these distributions at Mars, and compare the conditions under which these are observed at Mars with the results of our parametric sweeps. Lastly, we will also look at each term in the kinetic diffusion equation to determine if the energy and mixed diffusion coefficients are important enough to incorporate into STET as well.

Generalized thermoelastic diffusive waves in heat conducting materials

NASA Astrophysics Data System (ADS)

Sharma, J. N.

2007-04-01

Keeping in view the applications of diffusion processes in geophysics and electronics industry, the aim of the present paper is to give a detail account of the plane harmonic generalized thermoelastic diffusive waves in heat conducting solids. According to the characteristic equation, three longitudinal waves namely, elastodiffusive (ED), mass diffusion (MD-mode) and thermodiffusive (TD-mode), can propagate in such solids in addition to transverse waves. The transverse waves get decoupled from rest of the fields and hence remain unaffected due to temperature change and mass diffusion effects. These waves travel without attenuation and dispersion. The other generalized thermoelastic diffusive waves are significantly influenced by the interacting fields and hence suffer both attenuation and dispersion. At low frequency mass diffusion and thermal waves do not exist but at high-frequency limits these waves propagate with infinite velocity being diffusive in character. Moreover, in the low-frequency regions, the disturbance is mainly dominant by mechanical process of transportation of energy and at high-frequency regions it is significantly dominated by a close to diffusive process (heat conduction or mass diffusion). Therefore, at low-frequency limits the waves like modes are identifiable with small amplitude waves in elastic materials that do not conduct heat. The general complex characteristic equation is solved by using irreducible case of Cardano's method with the help of DeMoivre's theorem in order to obtain phase speeds, attenuation coefficients and specific loss factor of energy dissipation of various modes. The propagation of waves in case of non-heat conducting solids is also discussed. Finally, the numerical solution is carried out for copper (solvent) and zinc (solute) materials and the obtained phase velocities, attenuation coefficients and specific loss factor of various thermoelastic diffusive waves are presented graphically.

On a common critical state in localized and diffuse failure modes

NASA Astrophysics Data System (ADS)

Zhu, Huaxiang; Nguyen, Hien N. G.; Nicot, François; Darve, Félix

2016-10-01

Accurately modeling the critical state mechanical behavior of granular material largely relies on a better understanding and characterizing the critical state fabric in different failure modes, i.e. localized and diffuse failure modes. In this paper, a mesoscopic scale is introduced, in which the organization of force-transmission paths (force-chains) and cells encompassed by contacts (meso-loops) can be taken into account. Numerical drained biaxial tests using a discrete element method are performed with different initial void ratios, in order to investigate the critical state fabric on the meso-scale in both localized and diffuse failure modes. According to the displacement and strain fields extracted from tests, the failure mode and failure area of each specimen are determined. Then convergent critical state void ratios are observed in failure area of specimens. Different mechanical features of two kinds of meso-structures (force-chains and meso-loops) are investigated, to clarify whether there exists a convergent meso-structure inside the failure area of granular material, as the signature of critical state. Numerical results support a positive answer. Failure area of both localized and diffuse failure modes therefore exhibits the same fabric in critical state. Hence, these two failure modes prove to be homological with respect to the concept of the critical state.

Changes in electrical and thermal parameters of led packages under different current and heating stresses

NASA Astrophysics Data System (ADS)

Jayawardena, Adikaramge Asiri

The goal of this dissertation is to identify electrical and thermal parameters of an LED package that can be used to predict catastrophic failure real-time in an application. Through an experimental study the series electrical resistance and thermal resistance were identified as good indicators of contact failure of LED packages. This study investigated the long-term changes in series electrical resistance and thermal resistance of LED packages at three different current and junction temperature stress conditions. Experiment results showed that the series electrical resistance went through four phases of change; including periods of latency, rapid increase, saturation, and finally a sharp decline just before failure. Formation of voids in the contact metallization was identified as the underlying mechanism for series resistance increase. The rate of series resistance change was linked to void growth using the theory of electromigration. The rate of increase of series resistance is dependent on temperature and current density. The results indicate that void growth occurred in the cap (Au) layer, was constrained by the contact metal (Ni) layer, preventing open circuit failure of contact metal layer. Short circuit failure occurred due to electromigration induced metal diffusion along dislocations in GaN. The increase in ideality factor, and reverse leakage current with time provided further evidence to presence of metal in the semiconductor. An empirical model was derived for estimation of LED package failure time due to metal diffusion. The model is based on the experimental results and theories of electromigration and diffusion. Furthermore, the experimental results showed that the thermal resistance of LED packages increased with aging time. A relationship between thermal resistance change rate, with case temperature and temperature gradient within the LED package was developed. The results showed that dislocation creep is responsible for creep induced plastic deformation in the die-attach solder. The temperatures inside the LED package reached the melting point of die-attach solder due to delamination just before catastrophic open circuit failure. A combined model that could estimate life of LED packages based on catastrophic failure of thermal and electrical contacts is presented for the first time. This model can be used to make a-priori or real-time estimation of LED package life based on catastrophic failure. Finally, to illustrate the usefulness of the findings from this thesis, two different implementations of real-time life prediction using prognostics and health monitoring techniques are discussed.

Renormalization of the diffusion tensor for high-frequency, electromagnetic modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Litwin, C.; Sudan, R.N.

The resonance broadening theory is used to derive the diffusion tensor for resonant particles in a spectrum of electromagnetic modes propagating parallel to the magnetic field. The magnetic trapping limit for saturation of wave amplitudes is discussed.

Spatial Resolution Versus Data Acquisition Efficiency in Mapping an Inhomogeneous System with Species Diffusion

DOE PAGES

Chen, Fengxiang; Zhang, Yong; Gfroerer, T. H.; ...

2015-06-02

Traditionally, spatially-resolved photoluminescence (PL) has been performed using a point-by-point scan mode with both excitation and detection occurring at the same spatial location. But with the availability of high quality detector arrays like CCDs, an imaging mode has become popular for performing spatially-resolved PL. By illuminating the entire area of interest and collecting the data simultaneously from all spatial locations, the measurement efficiency can be greatly improved. However, this new approach has proceeded under the implicit assumption of comparable spatial resolution. We show here that when carrier diffusion is present, the spatial resolution can actually differ substantially between the twomore » modes, with the less efficient scan mode being far superior. We apply both techniques in investigation of defects in a GaAs epilayer – where isolated singlet and doublet dislocations can be identified. A superposition principle is developed for solving the diffusion equation to extract the intrinsic carrier diffusion length, which can be applied to a system with arbitrarily distributed defects. The understanding derived from this work is significant for a broad range of problems in physics and beyond (for instance biology) – whenever the dynamics of generation, diffusion, and annihilation of species can be probed with either measurement mode.« less

The effects of the Asselin time filter on numerical solutions to the linearized shallow-water wave equations

NASA Technical Reports Server (NTRS)

Schlesinger, R. E.; Johnson, D. R.; Uccellini, L. W.

1983-01-01

In the present investigation, a one-dimensional linearized analysis is used to determine the effect of Asselin's (1972) time filter on both the computational stability and phase error of numerical solutions for the shallow water wave equations, in cases with diffusion but without rotation. An attempt has been made to establish the approximate optimal values of the filtering parameter nu for each of the 'lagged', Dufort-Frankel, and Crank-Nicholson diffusion schemes, suppressing the computational wave mode without materially altering the physical wave mode. It is determined that in the presence of diffusion, the optimum filter length depends on whether waves are undergoing significant propagation. When moderate propagation is present, with or without diffusion, the Asselin filter has little effect on the spatial phase lag of the physical mode for the leapfrog advection scheme of the three diffusion schemes considered.

Analysis of Particle Transport in DIII-D H-mode Plasma with a Generalized Pinch-Diffusion Model

NASA Astrophysics Data System (ADS)

Owen, L. W.; Stacey, W. M.; Groebner, R. J.; Callen, J. D.; Bonnin, X.

2009-11-01

Interpretative analyses of particle transport in the pedestal region of H-mode plasmas typically yield diffusion coefficients that are very small (<0.1 m^2/s) in the steep gradient region when a purely diffusive particle flux is fitted to the experimental density gradients. Previous evaluation of the particle and momentum balance equations using the experimental data indicated that the pedestal profiles are consistent with transport described by a pinch-diffusion particle flux relation [1]. This type of model is used to calculate the diffusion coefficient and pinch velocity in the core for an inter-ELM H-mode plasma in the DIII-D discharge 98889. Full-plasma SOPLS simulations using neutral beam particle and energy sources from ONETWO calculations and the model transport coefficients show good agreement with the measured density pedestal profile. 6pt [1] W.M. Stacey and R.J. Groebner, Phys. Plasmas 12, 042504 (2005).

Modeling Diffusion Induced Stresses for Lithium-Ion Battery Materials

NASA Astrophysics Data System (ADS)

Chiu Huang, Cheng-Kai

Advancing lithium-ion battery technology is of paramount importance for satisfying the energy storage needs in the U.S., especially for the application in the electric vehicle industry. To provide a better acceleration for electric vehicles, a fast and repeatable discharging rate is required. However, particle fractures and capacity loss have been reported under high current rate (C-rate) during charging/discharging and after a period of cycling. During charging and discharging, lithium ions extract from and intercalate into electrode materials accompanied with the volume change and phase transition between Li-rich phase and Li-poor phase. It is suggested that the diffusion-induced-stress is one of the main reasons causing capacity loss due to the mechanical degradation of electrode particles. Therefore, there is a fundamental need to provide a mechanistic understanding by considering the structure-mechanics-property interactions in lithium-ion battery materials. Among many cathode materials, the olivine-based lithium-iron-phosphate (LiFePO4) with an orthorhombic crystal structure is one of the promising cathode materials for the application in electric vehicles. In this research we first use a multiphysic approach to investigate the stress evolution, especially on the phase boundary during lithiation in single LiFePO4 particles. A diffusion-controlled finite element model accompanied with the experimentally observed phase boundary propagation is developed via a finite element package, ANSYS, in which lithium ion concentration-dependent anisotropic material properties and volume misfits are incorporated. The stress components on the phase boundary are used to explain the Mode I, Mode II, and Mode III fracture propensities in LiFePO4 particles. The elastic strain energy evolution is also discussed to explain why a layer-by-layer lithium insertion mechanism (i.e. first-order phase transformation) is energetically preferred. Another importation issue is how current rate (C-rate) during charging/discharging affects diffusion induced stresses inside electrode materials. For the experimental part we first conduct charging/discharging under different C-rates to observe the voltage responses for commercial LiFePO4 batteries. Then Time-of-Flight Secondary Ion Mass Spectrometry technique is applied to measure the lithium ion intensities in different C-rate charged/discharged samples. These experimental results could be used to support that a more significant voltage fluctuation under high C-rates is due to different lithium insertion mechanisms, rather than the amount of lithium ions intercalated into electrode materials. Thus the investigation of C-rate-dependent stress evolution is required for the development of a more durable lithium ion battery. In this dissertation, we extend the single particle finite element model to investigate the C-rate-dependent diffusion induced stresses in a multi-particle system. Concentration dependent anisotropic material properties, C-rate-dependent volume misfits and concentration dependent Li-ion diffusivity are incorporated in the model. The concentration gradients, diffusion induced stresses, and strain energies under different C-rates are discussed in this study. Particle fractures have been observed in many experimental results, in this study we further discuss the effect of the crack surface orientation on the lithium concentration profile and stress level in cathode materials. The results of this dissertation provide a better understanding of diffusion induced stresses in electrode materials and contribute to our fundamental knowledge of interplay between lithium intercalations, stress evolutions, particle fractures and the capacity fade in lithium-ion batteries.

Modelling of nitrogen seeding experiments in the ASDEX Upgrade tokamak

NASA Astrophysics Data System (ADS)

Casali, L.; Fable, E.; Dux, R.; Ryter, F.; ASDEX Upgrade Team

2018-03-01

Experiments using nitrogen were conducted in H-mode plasmas at ASDEX Upgrade that has a full-W wall. The edge region of H-mode plasmas is modulated by the edge-localized modes (ELMs) which lead to a loss of energy and particles from the confined plasma. In order to gain a better understanding of the complex physical mechanisms which govern the behaviour of radiation and impurities in the presence of ELMs, the evolution of impurities and radiation has been modelled in a time-dependent way. The simulations have been carried out with the ASTRA-STRAHL package featuring the self-consistent interplay between impurity transport, radiation, heat and particle transport of the background plasma, and the effects of ELMs. ELMs are modelled based on the two different assumptions of a diffusive and a convective transport, respectively. The experimental discharge behaviour was reproduced providing only transport coefficients, heat, and particle source. The results underlie the importance of non-coronal effects through the ELM-induced transport which lead to a strong enhancement of the nitrogen radiation. Taking these effects into account is crucial in order to not underestimate the radiation. The radiation properties of high-Z impurities such as tungsten are instead very weakly influenced by non-coronal effects due to its faster equilibration time. While the nitrogen density does not change significantly decreasing the ELM frequency, tungsten density and consequently the radiation increase strongly. The degree to which W is flushed out depends on whether the ELM transport is diffusive or convective. Simulations show that for the N seeded cases considered here, the diffusive model reproduces more accurately the experimental observations. The different behaviour of N and W can be explained in terms of profile peaking which increases with Z (neoclassical pinch). The strong increase in W radiation when the ELM frequency is decreased is not only due to the lack of a sufficiently strong flush out of this impurity but also to the fact that the long time between two crashes gives the impurities time to penetrate further into the plasma escaping the region where they can be flushed out. This is in agreement with the experimental observations and highlights the importance of maintaining high ELM frequencies for the stability and performance of the discharges.

ANALYTIC FORMS OF THE PERPENDICULAR DIFFUSION COEFFICIENT IN NRMHD TURBULENCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shalchi, A., E-mail: andreasm4@yahoo.com

2015-02-01

In the past different analytic limits for the perpendicular diffusion coefficient of energetic particles interacting with magnetic turbulence were discussed. These different limits or cases correspond to different transport modes describing how the particles are diffusing across the large-scale magnetic field. In the current paper we describe a new transport regime by considering the model of noisy reduced magnetohydrodynamic turbulence. We derive different analytic forms of the perpendicular diffusion coefficient, and while we do this, we focus on the aforementioned new transport mode. We show that for this turbulence model a small perpendicular diffusion coefficient can be obtained so thatmore » the latter diffusion coefficient is more than hundred times smaller than the parallel diffusion coefficient. This result is relevant to explain observations in the solar system where such small perpendicular diffusion coefficients have been reported.« less

DEsubs: an R package for flexible identification of differentially expressed subpathways using RNA-seq experiments.

PubMed

Vrahatis, Aristidis G; Balomenos, Panos; Tsakalidis, Athanasios K; Bezerianos, Anastasios

2016-12-15

DEsubs is a network-based systems biology R package that extracts disease-perturbed subpathways within a pathway network as recorded by RNA-seq experiments. It contains an extensive and customized framework with a broad range of operation modes at all stages of the subpathway analysis, enabling so a case-specific approach. The operation modes include pathway network construction and processing, subpathway extraction, visualization and enrichment analysis with regard to various biological and pharmacological features. Its capabilities render DEsubs a tool-guide for both the modeler and experimentalist for the identification of more robust systems-level drug targets and biomarkers for complex diseases. DEsubs is implemented as an R package following Bioconductor guidelines: http://bioconductor.org/packages/DEsubs/ CONTACT: tassos.bezerianos@nus.edu.sgSupplementary information: Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Diffusion of Small Solute Particles in Viscous Liquids: Cage Diffusion, a Result of Decoupling of Solute-Solvent Dynamics, Leads to Amplification of Solute Diffusion.

PubMed

Acharya, Sayantan; Nandi, Manoj K; Mandal, Arkajit; Sarkar, Sucharita; Bhattacharyya, Sarika Maitra

2015-08-27

We study the diffusion of small solute particles through solvent by keeping the solute-solvent interaction repulsive and varying the solvent properties. The study involves computer simulations, development of a new model to describe diffusion of small solutes in a solvent, and also mode coupling theory (MCT) calculations. In a viscous solvent, a small solute diffuses via coupling to the solvent hydrodynamic modes and also through the transient cages formed by the solvent. The model developed can estimate the independent contributions from these two different channels of diffusion. Although the solute diffusion in all the systems shows an amplification, the degree of it increases with solvent viscosity. The model correctly predicts that when the solvent viscosity is high, the solute primarily diffuses by exploiting the solvent cages. In such a scenario the MCT diffusion performed for a static solvent provides a correct estimation of the cage diffusion.

The R package "sperrorest" : Parallelized spatial error estimation and variable importance assessment for geospatial machine learning

NASA Astrophysics Data System (ADS)

Schratz, Patrick; Herrmann, Tobias; Brenning, Alexander

2017-04-01

Computational and statistical prediction methods such as the support vector machine have gained popularity in remote-sensing applications in recent years and are often compared to more traditional approaches like maximum-likelihood classification. However, the accuracy assessment of such predictive models in a spatial context needs to account for the presence of spatial autocorrelation in geospatial data by using spatial cross-validation and bootstrap strategies instead of their now more widely used non-spatial equivalent. The R package sperrorest by A. Brenning [IEEE International Geoscience and Remote Sensing Symposium, 1, 374 (2012)] provides a generic interface for performing (spatial) cross-validation of any statistical or machine-learning technique available in R. Since spatial statistical models as well as flexible machine-learning algorithms can be computationally expensive, parallel computing strategies are required to perform cross-validation efficiently. The most recent major release of sperrorest therefore comes with two new features (aside from improved documentation): The first one is the parallelized version of sperrorest(), parsperrorest(). This function features two parallel modes to greatly speed up cross-validation runs. Both parallel modes are platform independent and provide progress information. par.mode = 1 relies on the pbapply package and calls interactively (depending on the platform) parallel::mclapply() or parallel::parApply() in the background. While forking is used on Unix-Systems, Windows systems use a cluster approach for parallel execution. par.mode = 2 uses the foreach package to perform parallelization. This method uses a different way of cluster parallelization than the parallel package does. In summary, the robustness of parsperrorest() is increased with the implementation of two independent parallel modes. A new way of partitioning the data in sperrorest is provided by partition.factor.cv(). This function gives the user the possibility to perform cross-validation at the level of some grouping structure. As an example, in remote sensing of agricultural land uses, pixels from the same field contain nearly identical information and will thus be jointly placed in either the test set or the training set. Other spatial sampling resampling strategies are already available and can be extended by the user.

Sentiment Diffusion of Public Opinions about Hot Events: Based on Complex Network

PubMed Central

Hao, Xiaoqing; An, Haizhong; Zhang, Lijia; Li, Huajiao; Wei, Guannan

2015-01-01

To study the sentiment diffusion of online public opinions about hot events, we collected people’s posts through web data mining techniques. We calculated the sentiment value of each post based on a sentiment dictionary. Next, we divided those posts into five different orientations of sentiments: strongly positive (P), weakly positive (p), neutral (o), weakly negative (n), and strongly negative (N). These sentiments are combined into modes through coarse graining. We constructed sentiment mode complex network of online public opinions (SMCOP) with modes as nodes and the conversion relation in chronological order between different types of modes as edges. We calculated the strength, k-plex clique, clustering coefficient and betweenness centrality of the SMCOP. The results show that the strength distribution obeys power law. Most posts’ sentiments are weakly positive and neutral, whereas few are strongly negative. There are weakly positive subgroups and neutral subgroups with ppppp and ooooo as the core mode, respectively. Few modes have larger betweenness centrality values and most modes convert to each other with these higher betweenness centrality modes as mediums. Therefore, the relevant person or institutes can take measures to lead people’s sentiments regarding online hot events according to the sentiment diffusion mechanism. PMID:26462230

An Urban Diffusion Simulation Model for Carbon Monoxide

ERIC Educational Resources Information Center

Johnson, W. B.; And Others

1973-01-01

A relatively simple Gaussian-type diffusion simulation model for calculating urban carbon (CO) concentrations as a function of local meteorology and the distribution of traffic is described. The model can be used in two ways: in the synoptic mode and in the climatological mode. (Author/BL)

The TriLab, a Novel ICT Based Triple Access Mode Laboratory Education Model

ERIC Educational Resources Information Center

Abdulwahed, Mahmoud; Nagy, Zoltan K.

2011-01-01

This paper introduces a novel model of laboratory education, namely the TriLab. The model is based on recent advances in ICT and implements a three access modes to the laboratory experience (virtual, hands-on and remote) in one software package. A review of the three modes is provided with highlights of advantages and disadvantages of each mode.…

Nonadiabatic nonradial p-mode frequencies of the standard solar model, with and without helium diffusion

NASA Technical Reports Server (NTRS)

Guenther, D. B.

1994-01-01

The nonadiabatic frequencies of a standard solar model and a solar model that includes helium diffusion are discussed. The nonadiabatic pulsation calculation includes physics that describes the losses and gains due to radiation. Radiative gains and losses are modeled in both the diffusion approximation, which is only valid in optically thick regions, and the Eddington approximation, which is valid in both optically thin and thick regions. The calculated pulsation frequencies for modes with l less than or equal to 1320 are compared to the observed spectrum of the Sun. Compared to a strictly adiabatic calculation, the nonadiabatic calculation of p-mode frequencies improves the agreement between model and observation. When helium diffusion is included in the model the frequencies of the modes that are sensitive to regions near the base of the convection zone are improved (i.e., brought into closer agreement with observation), but the agreement is made worse for other modes. Cyclic variations in the frequency spacings of the Sun as a function of frequency of n are presented as evidence for a discontinuity in the structure of the Sun, possibly located near the base of the convection zone.

Transition from diffuse to self-organized discharge in a high frequency dielectric barrier discharge

NASA Astrophysics Data System (ADS)

Belinger, Antoine; Naudé, Nicolas; Gherardi, Nicolas

2017-05-01

Depending on the operating conditions, different regimes can be obtained in a dielectric barrier discharge (DBD): filamentary, diffuse (also called homogeneous) or self-organized. For a plane-to-plane DBD operated at high frequency (160 kHz) and at atmospheric pressure in helium gas, we show that the addition of a small amount of nitrogen induces a transition from the diffuse regime to a self-organized regime characterized by the appearance of filaments at the exit of the discharge. In this paper, we detail mechanisms that could be responsible of the transition from diffuse mode to this self-organized mode. We point out the critical role of the power supply and the importance of the gas memory effect from one discharge to the following one on the transition to the self-organised mode. The self-organized mode is usually attributed to a surface memory effect. In this work, we show an additional involvement of the gas memory effect on the self-organized mode. Contribution to the topical issue "The 15th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XV)", edited by Nicolas Gherardi and Tomáš Hoder

Large-scale 3D simulations of ICF and HEDP targets

NASA Astrophysics Data System (ADS)

Marinak, Michael M.

2000-10-01

The radiation hydrodynamics code HYDRA continues to be developed and applied to 3D simulations of a variety of targets for both inertial confinement fusion (ICF) and high energy density physics. Several packages have been added enabling this code to perform ICF target simulations with similar accuracy as two-dimensional codes of long-time historical use. These include a laser ray trace and deposition package, a heavy ion deposition package, implicit Monte Carlo photonics, and non-LTE opacities, derived from XSN or the linearized response matrix approach.(R. More, T. Kato, Phys. Rev. Lett. 81, 814 (1998), S. Libby, F. Graziani, R. More, T. Kato, Proceedings of the 13th International Conference on Laser Interactions and Related Plasma Phenomena, (AIP, New York, 1997).) LTE opacities can also be calculated for arbitrary mixtures online by combining tabular values generated by different opacity codes. Thermonuclear burn, charged particle transport, neutron energy deposition, electron-ion coupling and conduction, and multigroup radiation diffusion packages are also installed. HYDRA can employ ALE hydrodynamics; a number of grid motion algorithms are available. Multi-material flows are resolved using material interface reconstruction. Results from large-scale simulations run on up to 1680 processors, using a combination of massively parallel processing and symmetric multiprocessing, will be described. A large solid angle simulation of Rayleigh-Taylor instability growth in a NIF ignition capsule has resolved simultaneously the full spectrum of the most dangerous modes that grow from surface roughness. Simulations of a NIF hohlraum illuminated with the initial 96 beam configuration have also been performed. The effect of the hohlraum’s 3D intrinsic drive asymmetry on the capsule implosion will be considered. We will also discuss results from a Nova experiment in which a copper sphere is crushed by a planar shock. Several interacting hydrodynamic instabilities, including the Widnall instability, cause breakup of the resulting vortex ring.

Evaluation of gallic acid loaded zein sub-micron electrospun fibre mats as novel active packaging materials.

PubMed

Neo, Yun Ping; Swift, Simon; Ray, Sudip; Gizdavic-Nikolaidis, Marija; Jin, Jianyong; Perera, Conrad O

2013-12-01

The applicability of gallic acid loaded zein (Ze-GA) electrospun fibre mats towards potential active food packaging material was evaluated. The surface chemistry of the electrospun fibre mats was determined using X-ray photon spectroscopy (XPS). The electrospun fibre mats showed low water activity and whitish colour. Thermogravimetric analysis (TGA) and Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy revealed the stability of the fibre mats over time. The Ze-GA fibre mats displayed similar rapid release profiles, with Ze-GA 20% exhibiting the fastest release rate in water as compared to the others. Gallic acid diffuses from the electrospun fibres in a Fickian diffusion manner and the data obtained exhibited a better fit to Higuchi model. L929 fibroblast cells were cultured on the electrospun fibres to demonstrate the absence of cytotoxicity. Overall, the Ze-GA fibre mats demonstrated antibacterial activity and properties consistent with those considered desirable for active packaging material in the food industry. Copyright © 2013 Elsevier Ltd. All rights reserved.

Comparison of particle tracking algorithms in commercial CFD packages: sedimentation and diffusion.

PubMed

Robinson, Risa J; Snyder, Pam; Oldham, Michael J

2007-05-01

Computational fluid dynamic modeling software has enabled microdosimetry patterns of inhaled toxins and toxicants to be predicted and visualized, and is being used in inhalation toxicology and risk assessment. These predicted microdosimetry patterns in airway structures are derived from predicted airflow patterns within these airways and particle tracking algorithms used in computational fluid dynamics (CFD) software packages. Although these commercial CFD codes have been tested for accuracy under various conditions, they have not been well tested for respiratory flows in general. Nor has their particle tracking algorithm accuracy been well studied. In this study, three software packages, Fluent Discrete Phase Model (DPM), Fluent Fine Particle Model (FPM), and ANSYS CFX, were evaluated. Sedimentation and diffusion were each isolated in a straight tube geometry and tested for accuracy. A range of flow rates corresponding to adult low activity (minute ventilation = 10 L/min) and to heavy exertion (minute ventilation = 60 L/min) were tested by varying the range of dimensionless diffusion and sedimentation parameters found using the Weibel symmetric 23 generation lung morphology. Numerical results for fully developed parabolic and uniform (slip) profiles were compared respectively, to Pich (1972) and Yu (1977) analytical sedimentation solutions. Schum and Yeh (1980) equations for sedimentation were also compared. Numerical results for diffusional deposition were compared to analytical solutions of Ingham (1975) for parabolic and uniform profiles. Significant differences were found among the various CFD software packages and between numerical and analytical solutions. Therefore, it is prudent to validate CFD predictions against analytical solutions in idealized geometry before tackling the complex geometries of the respiratory tract.

High-throughput migration modelling for estimating exposure to chemicals in food packaging in screening and prioritization tools.

PubMed

Ernstoff, Alexi S; Fantke, Peter; Huang, Lei; Jolliet, Olivier

2017-11-01

Specialty software and simplified models are often used to estimate migration of potentially toxic chemicals from packaging into food. Current models, however, are not suitable for emerging applications in decision-support tools, e.g. in Life Cycle Assessment and risk-based screening and prioritization, which require rapid computation of accurate estimates for diverse scenarios. To fulfil this need, we develop an accurate and rapid (high-throughput) model that estimates the fraction of organic chemicals migrating from polymeric packaging materials into foods. Several hundred step-wise simulations optimised the model coefficients to cover a range of user-defined scenarios (e.g. temperature). The developed model, operationalised in a spreadsheet for future dissemination, nearly instantaneously estimates chemical migration, and has improved performance over commonly used model simplifications. When using measured diffusion coefficients the model accurately predicted (R 2  = 0.9, standard error (S e ) = 0.5) hundreds of empirical data points for various scenarios. Diffusion coefficient modelling, which determines the speed of chemical transfer from package to food, was a major contributor to uncertainty and dramatically decreased model performance (R 2  = 0.4, S e  = 1). In all, this study provides a rapid migration modelling approach to estimate exposure to chemicals in food packaging for emerging screening and prioritization approaches. Copyright © 2017 Elsevier Ltd. All rights reserved.

High-Fidelity Thermal Radiation Models and Measurements for High-Pressure Reacting Laminar and Turbulent Flows

DTIC Science & Technology

2013-06-26

flow code used ( OpenFOAM ) to include differential diffusion and cell-based stochastic RTE solvers. The models were validated by simulation of laminar...wavenumber selection is improved about by a factor of 10. (5) OpenFOAM Improvements for Laminar Flames A laminar-diffusion combustion solver, taking into...account the effects of differential diffusion, was developed within the open source CFD package OpenFOAM [18]. In addition, OpenFOAM was augmented to take

Development of PIV for Microgravity Diffusion Flames

NASA Technical Reports Server (NTRS)

Greenberg, Paul S.; Wernet, Mark P.; Yanis, William; Urban, David L.; Sunderland, Peter B.

2003-01-01

Results are presented from the application of Particle Image Velocimetry(PIV) to the overfire region of a laminar gas jet diffusion flame in normal gravity. A methane flame burning in air at 0.98 bar was considered. The apparatus demonstrated here is packaged in a drop rig designed for use in the 2.2 second drop tower.

Installation package for Hyde Memorial Observatory, Lincoln, Nebraska

NASA Technical Reports Server (NTRS)

1978-01-01

Installation information for a solar heating system installed in Hyde Memorial Observatory at Lincoln, Nebraska is presented. This package included a system operation and maintenance manual, hardware brochures, schematics, system operating modes, and drawings. This prototype solar heating system consisted of the following subsystems: solar collector, control, and storage.

View of the Challenger's payload bay and the Plasma Diagnostic package

NASA Image and Video Library

1985-08-01

51F-33-024 (29 July-6 Aug 1985) --- The Challenger's remote manipulator system (RMS) arm grasps the plasma diagnostics package (PDP) over the experiment-laden cargo bay of the earth orbiting spacecraft. The instrument pointing system, in a resting mode here, is prominent in the bay.

Response of corrugated fiberboard to moisture flow : a 3-D finite element transient nonlinear analysis

Treesearch

Adeeb A. Rahman; Thomas J. Urbanik; Mustafa Mahamid

2003-01-01

Collapse of fiberboard packaging boxes, in the shipping industry, due to rise in humidity conditions is common and very costly. A 3D FE nonlinear model is developed to predict the moisture flow throughout a corrugated packaging fiberboard sandwich structure. The model predicts how the moisture diffusion will permeate through the layers of a fiberboard (medium and...

The comparison of antimicrobial packaging properties with different applications incorporation method of active material

NASA Astrophysics Data System (ADS)

Anwar, R. W.; Sugiarto; Warsiki, E.

2018-03-01

Contamination after the processing of products during storage, distribution and marketing is one of the main causes of food safety issues. Handling of food products after processing can be done during the packaging process. Antimicrobial (AM) active packaging is one of the concept of packaging product development by utilize the interaction between the product and the packaging environment that can delay the bacterial damage by killing or reducing bacterial growth. The active system is formed by incorporating an antimicrobial agent against a packaging matrix that will function as a carrier. Many incorporation methods have been developed in this packaging-making concept which were direct mixing, polishing, and encapsulation. The aims of this research were to examine the different of the AM packaging performances including its stability and effectiveness of its function that would be produced by three different methods. The stability of the packaging function was analyzed by looking at the diffusivity of the active ingredient to the matrix using SEM. The effectiveness was analyzed by the ability of the packaging to prevent the growing of the microbial. The results showed that different incorporation methods resulted on different characteristics of the AM packaging.

[Study on brand traceability of vinegar based on near infrared spectroscopy technology].

PubMed

Guan, Xiao; Liu, Jing; Gu, Fang-Qing; Yang, Yong-Jian

2014-09-01

In the present paper, 152 vinegar samples with four different brands were chosen as research targets, and their near infrared spectra were collected by diffusion reflection mode and transmission mode, respectively. Furthermore, the brand traceability models for edible vinegar were constructed. The effects of the collection mode and pretreatment methods of spectrum on the precision of traceability models were investigated intensively. The models constructed by PLS1-DA modeling method using spectrum data of 114 training samples were applied to predict 38 test samples, and R2, RMSEC and RMSEP of the model based on transmission mode data were 0.92, 0.113 and 0.127, respectively, with recognition rate of 76.32%, and those based on diffusion reflection mode data were 0.97, 0.102 and 0.119, with recognition rate of 86.84%. The results demonstrated that the near infrared spectrum combined with PLS1-DA can be used to establish the brand traceability models for edible vinegar, and diffuse reflection mode is more beneficial for predictive ability of the model.

The connectome mapper: an open-source processing pipeline to map connectomes with MRI.

PubMed

Daducci, Alessandro; Gerhard, Stephan; Griffa, Alessandra; Lemkaddem, Alia; Cammoun, Leila; Gigandet, Xavier; Meuli, Reto; Hagmann, Patric; Thiran, Jean-Philippe

2012-01-01

Researchers working in the field of global connectivity analysis using diffusion magnetic resonance imaging (MRI) can count on a wide selection of software packages for processing their data, with methods ranging from the reconstruction of the local intra-voxel axonal structure to the estimation of the trajectories of the underlying fibre tracts. However, each package is generally task-specific and uses its own conventions and file formats. In this article we present the Connectome Mapper, a software pipeline aimed at helping researchers through the tedious process of organising, processing and analysing diffusion MRI data to perform global brain connectivity analyses. Our pipeline is written in Python and is freely available as open-source at www.cmtk.org.

Recycled poly(ethylene terephthalate) for direct food contact applications: challenge test of an inline recycling process.

PubMed

Franz, R; Welle, F

2002-05-01

Of all the plastics used for packaging, due to its low diffusivity and chemical inertness, poly(ethylene terephthalate) (PET) is one of the favoured candidate plastics for closed-loop recycling for new packaging applications. In the work reported here, a PET-recycling process was investigated with respect to its cleaning efficiency and compliance of the PET recyclate with food law. The key technology of the investigated PET-recycling process to remove contaminants consists of a predecontamination-extruder combination. At the end of the recycling process, there is either a pelletizing system or downstream equipment to produce preforms or flat sheets. Therefore, the process has two process options, an inline production of PET preforms and a batch option producing PET pellets. In the case of possible misuse of PET bottles by the consumer, the inline process produces higher concentrations in the bottle wall of the recyclate containing preforms. Owing to the dilution of the PET output material by large amounts of uncontaminated PET, the batch option is the less critical process in terms of consumer protection. Regarding an appropriate testing procedure for the evaluation of a bottle-to-bottle recycling process, both process options have their own specific requirements with respect to the design of a challenge test. A novel challenge test approach to the inline mode of a recycling process is presented here.

Selective mode excitation in finite size plasma crystals by diffusely reflected laser light

NASA Astrophysics Data System (ADS)

Schablinski, Jan; Block, Dietmar

2015-02-01

The possibility to use diffuse reflections of a laser beam to exert a force on levitating dust particles is studied experimentally. Measurements and theoretical predictions are found to be in good agreement. Further, the method is applied to test the selective excitation of breathing-like modes in finite dust clusters.

ATE-TM mode splitter on lithium niobate using Ti, Ni, and MgO diffusions

NASA Astrophysics Data System (ADS)

Wei, Pei-Kuen; Wang, Way-Seen

1994-02-01

A new TE-TM mode splitter with an asymmetric Y-junction structure fabricated by diffusing different materials into y-cut lithium niobate is presented. Randomly polarized light launched into a titanium indiffused waveguide is split into TE and TM modes by two different single-polarization waveguides. The ordinary-polarized waveguide is made by nickel indiffusion and the extraordinary-polarized waveguide by magnesium-oxide induced lithium outdiffusion. The measured extinction ratios are greater than 20 dB for both TE and TM modes. The devices operate over a wide wavelength range and have a large fabrication tolerance.

NASA-DoD Lead-Free Electronics Project

NASA Technical Reports Server (NTRS)

Kessel, Kurt

2007-01-01

The primary technical objective of the project is to undertake comprehensive testing to generate information on failure modes/criteria to better understand the reliability of: Packages (e.g., TSOP, BGA, PDIP) assembled and reworked with lead-free alloys Packages (e.g., TSOP, BGA, PDIP) assembled and reworked with mixed (lead/lead-free) alloys.

10 CFR 430.32 - Energy and water conservation standards and their effective dates.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Rated Lamp Life ≥6,000 hours as declared by the manufacturer on packaging. At 80% of rated life... and/or other specified positions. Use wattages place on packaging to select proper specification... manufactured on or after July 1, 2008, shall meet the following standards: Active Mode Nameplate Output...

Spatial-temporal evolution of self-organized loop-patterns on a water surface and a diffuse discharge in the gap

NASA Astrophysics Data System (ADS)

Li, Xuechen; Geng, Jinling; Jia, Pengying; Zhang, Panpan; Zhang, Qi; Li, Yaru

2017-11-01

Excited by an alternating current voltage, a patterned discharge and a diffuse discharge are generated in a needle to liquid configuration. Using an intensified charge-coupled device (ICCD), temporal evolution of the discharge between the two electrodes is investigated for the diffuse mode and the patterned mode, respectively. For the diffuse mode, the positive discharge is in a glow regime, and the negative discharge is in a Townsend discharge regime. For the patterned mode, the discharge always belongs to the Townsend discharge regime. Moreover, in the patterned mode, various patterns including the single loop, single loop with the surrounding corona, triple loops, and concentric loops with a central spot are observed on the water surface with the increasing positive peak-value of the applied voltage (Upp). Temporally resolved images of the loop-patterns are captured on the water surface. From the electrical measurements and the ICCD imaging, it is found that the loop pattern emerges after the discharge bridges the two electrodes. Then, it begins to evolve and finally degenerates with the decrease in the discharge current. The pattern does not disappear until the discharge quenches. Formation of the loop-patterns is attributed to the role of negative ions.

Evaluation of Particle Pinch and Diffusion Coefficients in the Edge Pedestal of DIII-D H-mode Discharges

NASA Astrophysics Data System (ADS)

Stacey, W. M.; Groebner, R. J.

2009-11-01

Momentum balance requires that the radial particle flux satisfy a pinch-diffusion relationship. The pinch can be evaluated in terms of measurable quantities (rotation velocities, Er, etc.) by the use of momentum and particle balance [1,2], the radial particle flux can be determined by momentum balance, and then the diffusion coefficient can be evaluated from the pinch diffusion relation using the measured density gradient. Applications to several DIII-D H-mode plasmas are presented. 6pt [1] W.M. Stacey, Contr. Plasma Phys. 48, 94 (2008). [2] W.M. Stacey and R.J. Groebner, Phys. Plasmas 15, 012503 (2008).

Thermal diffusivity of ferrofluids as a function of particle size determined using the mode-mismatched dual-beam thermal lens technique

NASA Astrophysics Data System (ADS)

Lenart, V. M.; Astrath, N. G. C.; Turchiello, R. F.; Goya, G. F.; Gómez, S. L.

2018-02-01

Ferrofluids are colloids of superparamagnetic nanoparticles that are envisaged for use in hyperthermia, which is based on nonradiative relaxation after interaction with a high-frequency magnetic field or light. For such applications, an important parameter is the thermal diffusivity. In this communication, we present an experimental study of the dependence of thermal diffusivity of ferrofluids on the size of the magnetite nanoparticles by employing the mode-mismatched thermal lens technique. The results show a huge enhancement of the thermal diffusivity by increasing the average size of the nanoparticles, while the number density of the nanoparticles is maintained as constant.

Steepest Ascent Low/Non-Low-Frequency Ratio in Empirical Mode Decomposition to Separate Deterministic and Stochastic Velocities From a Single Lagrangian Drifter

NASA Astrophysics Data System (ADS)

Chu, Peter C.

2018-03-01

SOund Fixing And Ranging (RAFOS) floats deployed by the Naval Postgraduate School (NPS) in the California Current system from 1992 to 2001 at depth between 150 and 600 m (http://www.oc.nps.edu/npsRAFOS/) are used to study 2-D turbulent characteristics. Each drifter trajectory is adaptively decomposed using the empirical mode decomposition (EMD) into a series of intrinsic mode functions (IMFs) with corresponding specific scale for each IMF. A new steepest ascent low/non-low-frequency ratio is proposed in this paper to separate a Lagrangian trajectory into low-frequency (nondiffusive, i.e., deterministic) and high-frequency (diffusive, i.e., stochastic) components. The 2-D turbulent (or called eddy) diffusion coefficients are calculated on the base of the classical turbulent diffusion with mixing length theory from stochastic component of a single drifter. Statistical characteristics of the calculated 2-D turbulence length scale, strength, and diffusion coefficients from the NPS RAFOS data are presented with the mean values (over the whole drifters) of the 2-D diffusion coefficients comparable to the commonly used diffusivity tensor method.

Multi-mode Li diffusion in natural zircons: Evidence for diffusion in the presence of step-function concentration boundaries

NASA Astrophysics Data System (ADS)

Tang, Ming; Rudnick, Roberta L.; McDonough, William F.; Bose, Maitrayee; Goreva, Yulia

2017-09-01

Micron- to submicron-scale observations of Li distribution and Li isotope composition profiles can be used to infer the mechanisms of Li diffusion in natural zircon. Extreme fractionation (20-30‰) within each single crystal studied here confirms that Li diffusion commonly occurs in zircon. Sharp Li concentration gradients frequently seen in zircons suggest that the effective diffusivity of Li is significantly slower than experimentally determined (Cherniak and Watson, 2010; Trail et al., 2016), otherwise the crystallization/metamorphic heating of these zircons would have to be unrealistically fast (years to tens of years). Charge coupling with REE and Y has been suggested as a mechanism that may considerably reduce Li diffusivity in zircon (Ushikubo et al., 2008; Bouvier et al., 2012). We show that Li diffused in the direction of decreasing Li/Y ratio and increasing Li concentration (uphill diffusion) in one of the zircons, demonstrating charge coupling with REE and Y. Quantitative modeling reveals that Li may diffuse in at least two modes in natural zircons: one being slow and possibly coupled with REE+Y, and the other one being fast and not coupled with REE+Y. The partitioning of Li between these two modes during its diffusion may depend on the pre-diffusion substitution mechanism of REE and Y in the zircon lattice. Based on our results, sharp Li concentration gradients are not indicative of limited diffusion, and can be preserved at temperatures >700 °C on geologic timescales. Finally, large δ7 Li variations observed in the Hadean Jack Hills zircons may record kinetic fractionation, rather than a record of ancient intense weathering in the granite source materials.

Quantum dark soliton: Nonperturbative diffusion of phase and position

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dziarmaga, J.

2004-12-01

The dark soliton solution of the Gross-Pitaevskii equation in one dimension has two parameters that do not change the energy of the solution: the global phase of the condensate wave function and the position of the soliton. These degeneracies appear in the Bogoliubov theory as Bogoliubov modes with zero frequencies and zero norms. These 'zero modes' cannot be quantized as the usual Bogoliubov quasiparticle harmonic oscillators. They must be treated in a nonperturbative way. In this paper I develop a nonperturbative theory of zero modes. This theory provides a nonperturbative description of quantum phase diffusion and quantum diffusion of solitonmore » position. An initially well localized wave packet for soliton position is predicted to disperse beyond the width of the soliton.« less

Application of FTIR microscopy in the study of pharmaceutical packaging materials and formulations

NASA Astrophysics Data System (ADS)

Hu, John J.; Johnson, James B.

1992-08-01

Fourier transform infrared microscopy offers many unique advantages in studying pharmaceutical packaging materials and formulations because of its sensitivity and variety of measurement modes with precise control of the area to the analyzed. This report discusses the application of FTIR microscopy in studying commonly encountered pharmaceutical packaging components such as multi-layer laminate films, disposable syringes and rubber stoppers. The use of the instrument to study pharmaceutical formulation parameters such as polymorphism and component identification is also presented.

A dual-mode generalized likelihood ratio approach to self-reorganizing digital flight control system design

NASA Technical Reports Server (NTRS)

Bueno, R.; Chow, E.; Gershwin, S. B.; Willsky, A. S.

1975-01-01

The research is reported on the problems of failure detection and reliable system design for digital aircraft control systems. Failure modes, cross detection probability, wrong time detection, application of performance tools, and the GLR computer package are discussed.

Comparison between the intra-particle diffusivity in the hydrophilic interaction chromatography and reversed phase liquid chromatography modes. Impact on the column efficiency.

PubMed

Gritti, Fabrice; Guiochon, Georges

2013-07-05

The effective diffusion coefficients of five low molecular weigh compounds (naphthalene, uracil, uridine, adenosine, and cytosine) were measured at room temperature in a 4.6mm×100mm column packed with 3.5μm XBridge HILIC particles. The mobile phase was an acetonitrile-water mixture (92.5/7.5, v/v) containing 10mM ammonium acetate and 0.02% acetic acid. Using a physically reliable model of effective diffusion in binary composite media (Torquato's model), accurate estimates of the intra-particle diffusivities in the HILIC particles were obtained as a function of the retention of these analytes. The HILIC diffusion coefficients were compared to those previously obtained for endcapped RPLC-C18 particles (5.0μm Gemini-C18). The experimental results confirm that adsorption sites are not localized in RPLC whereas they are so in the HILIC mode. In contrast to RPLC columns, HILIC columns provide longitudinal diffusion B/u terms that increase very little with increasing retention factors. This confirms the absence of surface diffusion in HILIC. The impact of intra-particle diffusivity on the column efficiency was projected in HILIC and RPLC on the basis of the measured intra-particle diffusivities and on the well established theory of band broadening in particulate columns. Accordingly, RPLC columns generate short-range eddy dispersion and solid-liquid mass transfer resistance Cu terms that increase less than do HILIC column with increasing retention factors. The HETP contribution caused by the trans-column structure heterogeneity is smaller in the HILIC than in the RPLC modes because the transverse excursion length is smaller in HILIC. Even though the overall column efficiencies are comparable in HILIC and RPLC, this study shows that the individual mass transfer phenomena are inherently different in the HILIC and the RPLC retention modes. Copyright © 2013 Elsevier B.V. All rights reserved.

Tritium waste package

DOEpatents

Rossmassler, Rich; Ciebiera, Lloyd; Tulipano, Francis J.; Vinson, Sylvester; Walters, R. Thomas

1995-01-01

A containment and waste package system for processing and shipping tritium xide waste received from a process gas includes an outer drum and an inner drum containing a disposable molecular sieve bed (DMSB) seated within outer drum. The DMSB includes an inlet diffuser assembly, an outlet diffuser assembly, and a hydrogen catalytic recombiner. The DMSB absorbs tritium oxide from the process gas and converts it to a solid form so that the tritium is contained during shipment to a disposal site. The DMSB is filled with type 4A molecular sieve pellets capable of adsorbing up to 1000 curies of tritium. The recombiner contains a sufficient amount of catalyst to cause any hydrogen add oxygen present in the process gas to recombine to form water vapor, which is then adsorbed onto the DMSB.

Tritium waste package

DOEpatents

Rossmassler, R.; Ciebiera, L.; Tulipano, F.J.; Vinson, S.; Walters, R.T.

1995-11-07

A containment and waste package system for processing and shipping tritium oxide waste received from a process gas includes an outer drum and an inner drum containing a disposable molecular sieve bed (DMSB) seated within the outer drum. The DMSB includes an inlet diffuser assembly, an outlet diffuser assembly, and a hydrogen catalytic recombiner. The DMSB absorbs tritium oxide from the process gas and converts it to a solid form so that the tritium is contained during shipment to a disposal site. The DMSB is filled with type 4A molecular sieve pellets capable of adsorbing up to 1000 curies of tritium. The recombiner contains a sufficient amount of catalyst to cause any hydrogen and oxygen present in the process gas to recombine to form water vapor, which is then adsorbed onto the DMSB. 1 fig.

Single-mode 850-nm vertical-cavity surface-emitting lasers with Zn-diffusion and oxide-relief apertures for > 50 Gbit/sec OOK and 4-PAM transmission

NASA Astrophysics Data System (ADS)

Shi, Jin-Wei; Wei, Chia-Chien; Chen, Jyehong; Ledentsov, N. N.; Yang, Ying-Jay

2017-02-01

Vertical-cavity surface-emitting lasers (VCSELs) has become the most important light source in the booming market of short-reach (< 300 meters) optical interconnect (OI). The next generation OI has been targeted at 56 Gbit/sec data rate per channel (CEI-56G) with the total data rate up to 400 Gbit/sec. However, the serious modal dispersion of multi-mode fiber (MMF), limited speed of VCSEL, and its high resistance (> 150 Ω) seriously limits the >50 Gbit/sec linking distance (< 10 m) by using only on-off keying (OOK) modulation scheme without any signal processing techniques. In contrast to OOK, 4-PAM modulation format is attractive for >50 Gbit/sec transmission due to that it can save one-half of the required bandwidth. Nevertheless, a 4.7 dB optical power penalty and the linearity of transmitter would become issues in the 4-PAM linking performance. Besides, in the modern OI system, the optics transreceiver module must be packaged as close as possible with the integrated circuits (ICs). The heat generated from ICs will become an issue in speed of VSCEL. Here, we review our recent work about 850 nm VCSEL, which has unique Zn-diffusion/oxide-relief apertures and special p- doping active layer with strong wavelength detuning to further enhance its modulation speed and high-temperature (85°C) performances. Single-mode (SM) devices with high-speed ( 26 GHz), reasonable resistance ( 70 Ω) and moderate output power ( 1.5 mW) can be achieved. Error-free 54 Gbit/sec OOK transmission through 1km MMF has been realized by using such SM device with signal processing techniques. Besides, the volterra nonlinear equalizer has been applied in our 4-PAM 64 Gbit/sec transmission through 2-km OM4 MMF, which significantly enhance the linearity of device and outperforms fed forward equalization (FFE) technique. Record high bit-rate distance product of 128.km is confirmed for optical-interconnect applications.

Modeling, design, packing and experimental analysis of liquid-phase shear-horizontal surface acoustic wave sensors

NASA Astrophysics Data System (ADS)

Pollard, Thomas B

Recent advances in microbiology, computational capabilities, and microelectromechanical-system fabrication techniques permit modeling, design, and fabrication of low-cost, miniature, sensitive and selective liquid-phase sensors and lab-on-a-chip systems. Such devices are expected to replace expensive, time-consuming, and bulky laboratory-based testing equipment. Potential applications for devices include: fluid characterization for material science and industry; chemical analysis in medicine and pharmacology; study of biological processes; food analysis; chemical kinetics analysis; and environmental monitoring. When combined with liquid-phase packaging, sensors based on surface-acoustic-wave (SAW) technology are considered strong candidates. For this reason such devices are focused on in this work; emphasis placed on device modeling and packaging for liquid-phase operation. Regarding modeling, topics considered include mode excitation efficiency of transducers; mode sensitivity based on guiding structure materials/geometries; and use of new piezoelectric materials. On packaging, topics considered include package interfacing with SAW devices, and minimization of packaging effects on device performance. In this work novel numerical models are theoretically developed and implemented to study propagation and transduction characteristics of sensor designs using wave/constitutive equations, Green's functions, and boundary/finite element methods. Using developed simulation tools that consider finite-thickness of all device electrodes, transduction efficiency for SAW transducers with neighboring uniform or periodic guiding electrodes is reported for the first time. Results indicate finite electrode thickness strongly affects efficiency. Using dense electrodes, efficiency is shown to approach 92% and 100% for uniform and periodic electrode guiding, respectively; yielding improved sensor detection limits. A numerical sensitivity analysis is presented targeting viscosity using uniform-electrode and shear-horizontal mode configurations on potassium-niobate, langasite, and quartz substrates. Optimum configurations are determined yielding maximum sensitivity. Results show mode propagation-loss and sensitivity to viscosity are correlated by a factor independent of substrate material. The analysis is useful for designing devices meeting sensitivity and signal level requirements. A novel, rapid and precise microfluidic chamber alignment/bonding method was developed for SAW platforms. The package is shown to have little effect on device performance and permits simple macrofluidic interfacing. Lastly, prototypes were designed, fabricated, and tested for viscosity and biosensor applications; results show ability to detect as low as 1% glycerol in water and surface-bound DNA crosslinking.

MODFLOW-2000 Ground-Water Model?User Guide to the Subsidence and Aquifer-System Compaction (SUB) Package

USGS Publications Warehouse

Hoffmann, Jörn; Leake, S.A.; Galloway, D.L.; Wilson, Alicia M.

2003-01-01

This report documents a computer program, the Subsidence and Aquifer-System Compaction (SUB) Package, to simulate aquifer-system compaction and land subsidence using the U.S. Geological Survey modular finite-difference ground-water flow model, MODFLOW-2000. The SUB Package simulates elastic (recoverable) compaction and expansion, and inelastic (permanent) compaction of compressible fine-grained beds (interbeds) within the aquifers. The deformation of the interbeds is caused by head or pore-pressure changes, and thus by changes in effective stress, within the interbeds. If the stress is less than the preconsolidation stress of the sediments, the deformation is elastic; if the stress is greater than the preconsolidation stress, the deformation is inelastic. The propagation of head changes within the interbeds is defined by a transient, one-dimensional (vertical) diffusion equation. This equation accounts for delayed release of water from storage or uptake of water into storage in the interbeds. Properties that control the timing of the storage changes are vertical hydraulic diffusivity and interbed thickness. The SUB Package supersedes the Interbed Storage Package (IBS1) for MODFLOW, which assumes that water is released from or taken into storage with changes in head in the aquifer within a single model time step and, therefore, can be reasonably used to simulate only thin interbeds. The SUB Package relaxes this assumption and can be used to simulate time-dependent drainage and compaction of thick interbeds and confining units. The time-dependent drainage can be turned off, in which case the SUB Package gives results identical to those from IBS1. Three sample problems illustrate the usefulness of the SUB Package. One sample problem verifies that the package works correctly. This sample problem simulates the drainage of a thick interbed in response to a step change in head in the adjacent aquifer and closely matches the analytical solution. A second sample problem illustrates the effects of seasonally varying discharge and recharge to an aquifer system with a thick interbed. A third sample problem simulates a multilayered regional ground-water basin. Model input files for the third sample problem are included in the appendix.

77 FR 76602 - Office of Hazardous Materials Safety; Actions on Special Permit Applications

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-28

...), transportation in 173.465(c), commerce of certain 173.465(d). Radioactive material in alternative packaging by... material in alternative packaging. (modes 1, 3) 15626-N......... EC Source 49 CFR 49 CFR To authorize the...); radioactive 175.702(b). material on cargo only aircraft when the combined transport index exceeds 50.0 and/or...

Large amplitude m=1 diocotron mode measurements in the Electron Diffusion Gauge experiment

NASA Astrophysics Data System (ADS)

Jenkins, Thomas G.; Morrison, Kyle A.; Davidson, Ronald C.; Paul, Stephen F.

2002-01-01

Smaller-diameter pure electron plasmas are generated in the Electron Diffusion Gauge (EDG) using a thoriated tungsten filament wound into a spiral shape with an outer diameter which is 1/4 of the trap wall diameter. The m=1 diocotron mode is excited in the plasma by means of the resistive-wall instability, using a resistor-relay circuit which allows the mode to be induced at various initial amplitudes. The dynamics of this mode may be predicted using linear theory when the amplitude is small. However, it has been observed [e.g., Fine et al., Phys. Rev. Lett. 63, 2232 (1989)] [1] that at larger amplitudes the frequency of this mode (relative to the small-amplitude frequency) exhibits a quadratic dependence on the mode amplitude. In this paper, the frequency shift and nonlinear dynamics of the m=1 diocotron mode in the EDG device are investigated.

Fibonacci family of dynamical universality classes.

PubMed

Popkov, Vladislav; Schadschneider, Andreas; Schmidt, Johannes; Schütz, Gunter M

2015-10-13

Universality is a well-established central concept of equilibrium physics. However, in systems far away from equilibrium, a deeper understanding of its underlying principles is still lacking. Up to now, a few classes have been identified. Besides the diffusive universality class with dynamical exponent [Formula: see text], another prominent example is the superdiffusive Kardar-Parisi-Zhang (KPZ) class with [Formula: see text]. It appears, e.g., in low-dimensional dynamical phenomena far from thermal equilibrium that exhibit some conservation law. Here we show that both classes are only part of an infinite discrete family of nonequilibrium universality classes. Remarkably, their dynamical exponents [Formula: see text] are given by ratios of neighboring Fibonacci numbers, starting with either [Formula: see text] (if a KPZ mode exist) or [Formula: see text] (if a diffusive mode is present). If neither a diffusive nor a KPZ mode is present, all dynamical modes have the Golden Mean [Formula: see text] as dynamical exponent. The universal scaling functions of these Fibonacci modes are asymmetric Lévy distributions that are completely fixed by the macroscopic current density relation and compressibility matrix of the system and hence accessible to experimental measurement.

A Student Diffusion Activity

ERIC Educational Resources Information Center

Kutzner, Mickey; Pearson, Bryan

2017-01-01

Diffusion is a truly interdisciplinary topic bridging all areas of STEM education. When biomolecules are not being moved through the body by fluid flow through the circulatory system or by molecular motors, diffusion is the primary mode of transport over short distances. The direction of the diffusive flow of particles is from high concentration…

m=1 diocotron mode damping in the Electron Diffusion Gauge (EDG) experiment

NASA Astrophysics Data System (ADS)

Paul, Stephen F.; Morrison, Kyle A.; Davidson, Ronald C.; Jenkins, Thomas G.

2002-01-01

The evolution of the amplitude of the m=1 diocotron mode is used to measure the background neutral pressure in the Electron Diffusion Gauge (EDG), a Malmberg-Penning trap. Below 5×10-8 Torr, the dependence on pressure scales as P1/4, and is sensitive to pressure changes as small as ΔP=5×10-11 Torr. Previous studies on the EDG showed that the diocotron mode is more strongly damped at higher neutral pressures. Both the diocotron mode damping rate and the plasma expansion rate depend similarly on experimental parameters, i.e., conditions which favor expansion also favor suppression of the diocotron mode. The sensitivity of the mode evolution is examined as a function of the resistive growth driving conditions, which are controlled by the amount of wall resistance connected to the trap.

Antimicrobial agent-free hybrid cationic starch/sodium alginate polyelectrolyte films for food packaging materials.

PubMed

Şen, Ferhat; Uzunsoy, İrem; Baştürk, Emre; Kahraman, Memet Vezir

2017-08-15

This study aimed to develop polyelectrolyte structured antimicrobial food packaging materials that do not contain any antimicrobial agents. Cationic starch was synthesized and characterized by FT-IR spectroscopy and 1 H NMR spectroscopy. Its nitrogen content was determined by Kjeldahl method. Polyelectrolyte structured antimicrobial food packaging materials were prepared using starch, cationic starch and sodium alginate. Antimicrobial activity of materials was defined by inhibition zone method (disc diffusion method). Thermal stability of samples was evaluated by TGA and DSC. Hydrophobicity of samples was determined by contact angle measurements. Surface morphology of samples was investigated by SEM. Moreover, gel contents of samples were determined. The obtained results prove that produced food packaging materials have good thermal, antimicrobial and surface properties, and they can be used as food packaging material in many industries. Copyright © 2017 Elsevier Ltd. All rights reserved.

77 FR 8946 - Notice of Application for Special Permits

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-15

... service motor vehicles for use in transporting a corrosive solid material in alternative packaging. (modes... the ``Nature of Application'' portion of the table below as follows: 1--Motor vehicle, 2--Rail freight... limitations and certain loading and stowage requirements. (mode 4) 15536-N ......... WavesinSolids LLC, 49 CFR...

Distributed feedback lasers

NASA Technical Reports Server (NTRS)

Ladany, I.; Andrews, J. T.; Evans, G. A.

1988-01-01

A ridge waveguide distributed feedback laser was developed in InGaAsP. These devices have demonstrated CW output powers over 7 mW with threshold currents as low as 60 mA at 25 C. Measurements of the frequency response of these devices show a 3 dB bandwidth of about 2 GHz, which may be limited by the mount. The best devices have a single mode spectra over the entire temperature range tested with a side mode suppression of about 20 dB in both CW and pulsed modes. The design of this device, including detailed modeling of the ridge guide structure, effective index calculations, and a discussion of the grating configuration are presented. Also, the fabrication of the devices is presented in some detail, especially the fabrication of and subsequent growth over the grating. In addition, a high frequency fiber pigtailed package was designed and tested, which is a suitable prototype for a commercial package.

On the Stability of Shocks with Particle Pressure

NASA Astrophysics Data System (ADS)

Finazzi, Stefano; Vietri, Mario

2008-11-01

We perform a linear stability analysis for corrugations of a Newtonian shock, with particle pressure included, for an arbitrary diffusion coefficient. We study first the dispersion relation for homogeneous media, showing that, besides the conventional pressure waves and entropy/vorticity disturbances, two new perturbation modes exist, dominated by the particles' pressure and damped by diffusion. We show that, due to particle diffusion into the upstream region, the fluid will be perturbed also upstream; we treat these perturbation in the short-wavelength (WKBJ) regime. We then show how to construct a corrugational mode for the shock itself, one, that is, where the shock executes free oscillations (possibly damped or growing) and sheds perturbations away from itself; this global mode requires the new modes. Then, using the perturbed Rankine-Hugoniot conditions, we show that this leads to the determination of the corrugational eigenfrequency. We solve numerically the equations for the eigenfrequency in the WKBJ regime for the models of Amato & Blasi, showing that they are stable. We then discuss the differences between our treatment and previous work.

Evaluating the operational risks of biomedical waste using failure mode and effects analysis.

PubMed

Chen, Ying-Chu; Tsai, Pei-Yi

2017-06-01

The potential problems and risks of biomedical waste generation have become increasingly apparent in recent years. This study applied a failure mode and effects analysis to evaluate the operational problems and risks of biomedical waste. The microbiological contamination of biomedical waste seldom receives the attention of researchers. In this study, the biomedical waste lifecycle was divided into seven processes: Production, classification, packaging, sterilisation, weighing, storage, and transportation. Twenty main failure modes were identified in these phases and risks were assessed based on their risk priority numbers. The failure modes in the production phase accounted for the highest proportion of the risk priority number score (27.7%). In the packaging phase, the failure mode 'sharp articles not placed in solid containers' had the highest risk priority number score, mainly owing to its high severity rating. The sterilisation process is the main difference in the treatment of infectious and non-infectious biomedical waste. The failure modes in the sterilisation phase were mainly owing to human factors (mostly related to operators). This study increases the understanding of the potential problems and risks associated with biomedical waste, thereby increasing awareness of how to improve the management of biomedical waste to better protect workers, the public, and the environment.

Resonant Mode-hopping Micromixing

PubMed Central

Jang, Ling-Sheng; Chao, Shih-Hui; Holl, Mark R.; Meldrum, Deirdre R.

2009-01-01

A common micromixer design strategy is to generate interleaved flow topologies to enhance diffusion. However, problems with these designs include complicated structures and dead volumes within the flow fields. We present an active micromixer using a resonating piezoceramic/silicon composite diaphragm to generate acoustic streaming flow topologies. Circulation patterns are observed experimentally and correlate to the resonant mode shapes of the diaphragm. The dead volumes in the flow field are eliminated by rapidly switching from one discrete resonant mode to another (i.e., resonant mode-hop). Mixer performance is characterized by mixing buffer with a fluorescence tracer containing fluorescein. Movies of the mixing process are analyzed by converting fluorescent images to two-dimensional fluorescein concentration distributions. The results demonstrate that mode-hopping operation rapidly homogenized chamber contents, circumventing diffusion-isolated zones. PMID:19551159

Mode-locking in advection-reaction-diffusion systems: An invariant manifold perspective

NASA Astrophysics Data System (ADS)

Locke, Rory A.; Mahoney, John R.; Mitchell, Kevin A.

2018-01-01

Fronts propagating in two-dimensional advection-reaction-diffusion systems exhibit a rich topological structure. When the underlying fluid flow is periodic in space and time, the reaction front can lock to the driving frequency. We explain this mode-locking phenomenon using the so-called burning invariant manifolds (BIMs). In fact, the mode-locked profile is delineated by a BIM attached to a relative periodic orbit (RPO) of the front element dynamics. Changes in the type (and loss) of mode-locking can be understood in terms of local and global bifurcations of the RPOs and their BIMs. We illustrate these concepts numerically using a chain of alternating vortices in a channel geometry.

49.6 Gb/s direct detection DMT transmission over 40 km single mode fibre using an electrically packaged silicon photonic modulator.

PubMed

Lacava, C; Cardea, I; Demirtzioglou, I; Khoja, A E; Ke, Li; Thomson, D J; Ruan, X; Zhang, F; Reed, G T; Richardson, D J; Petropoulos, P

2017-11-27

We present the characterization of a silicon Mach-Zehnder modulator with electrical packaging and show that it exhibits a large third-order intermodulation spurious-free dynamic range (> 100 dB Hz 2/3 ). This characteristic renders the modulator particularly suitable for the generation of high spectral efficiency discrete multi-tone signals and we experimentally demonstrate a single-channel, direct detection transmission system operating at 49.6 Gb/s, exhibiting a baseband spectral efficiency of 5 b/s/Hz. Successful transmission is demonstrated over various lengths of single mode fibre up to 40 km, without the need of any amplification or dispersion compensation.

Simulation-based Bayesian inference for latent traits of item response models: Introduction to the ltbayes package for R.

PubMed

Johnson, Timothy R; Kuhn, Kristine M

2015-12-01

This paper introduces the ltbayes package for R. This package includes a suite of functions for investigating the posterior distribution of latent traits of item response models. These include functions for simulating realizations from the posterior distribution, profiling the posterior density or likelihood function, calculation of posterior modes or means, Fisher information functions and observed information, and profile likelihood confidence intervals. Inferences can be based on individual response patterns or sets of response patterns such as sum scores. Functions are included for several common binary and polytomous item response models, but the package can also be used with user-specified models. This paper introduces some background and motivation for the package, and includes several detailed examples of its use.

Slaved diffusion in phospholipid bilayers

PubMed Central

Zhang, Liangfang; Granick, Steve

2005-01-01

The translational diffusion of phospholipids in supported fluid bilayers splits into two populations when polyelectrolytes adsorb at incomplete surface coverage. Spatially resolved measurements using fluorescence correlation spectroscopy show that a slow mode, whose magnitude scales inversely with the degree of polymerization of the adsorbate, coexists with a fast mode characteristic of naked lipid diffusion. Inner and outer leaflets of the bilayer are affected nearly equally. Mobility may vary from spot to spot on the membrane surface, despite the lipid composition being the same. This work offers a mechanism to explain how nanosized domains with reduced mobility arise in lipid membranes. PMID:15967988

Worst case prediction of additives migration from polystyrene for food safety purposes: a model update.

PubMed

Martínez-López, Brais; Gontard, Nathalie; Peyron, Stéphane

2018-03-01

A reliable prediction of migration levels of plastic additives into food requires a robust estimation of diffusivity. Predictive modelling of diffusivity as recommended by the EU commission is carried out using a semi-empirical equation that relies on two polymer-dependent parameters. These parameters were determined for the polymers most used by packaging industry (LLDPE, HDPE, PP, PET, PS, HIPS) from the diffusivity data available at that time. In the specific case of general purpose polystyrene, the diffusivity data published since then shows that the use of the equation with the original parameters results in systematic underestimation of diffusivity. The goal of this study was therefore, to propose an update of the aforementioned parameters for PS on the basis of up to date diffusivity data, so the equation can be used for a reasoned overestimation of diffusivity.

Space Shuttle Main Engine Quantitative Risk Assessment: Illustrating Modeling of a Complex System with a New QRA Software Package

NASA Technical Reports Server (NTRS)

Smart, Christian

1998-01-01

During 1997, a team from Hernandez Engineering, MSFC, Rocketdyne, Thiokol, Pratt & Whitney, and USBI completed the first phase of a two year Quantitative Risk Assessment (QRA) of the Space Shuttle. The models for the Shuttle systems were entered and analyzed by a new QRA software package. This system, termed the Quantitative Risk Assessment System(QRAS), was designed by NASA and programmed by the University of Maryland. The software is a groundbreaking PC-based risk assessment package that allows the user to model complex systems in a hierarchical fashion. Features of the software include the ability to easily select quantifications of failure modes, draw Event Sequence Diagrams(ESDs) interactively, perform uncertainty and sensitivity analysis, and document the modeling. This paper illustrates both the approach used in modeling and the particular features of the software package. The software is general and can be used in a QRA of any complex engineered system. The author is the project lead for the modeling of the Space Shuttle Main Engines (SSMEs), and this paper focuses on the modeling completed for the SSMEs during 1997. In particular, the groundrules for the study, the databases used, the way in which ESDs were used to model catastrophic failure of the SSMES, the methods used to quantify the failure rates, and how QRAS was used in the modeling effort are discussed. Groundrules were necessary to limit the scope of such a complex study, especially with regard to a liquid rocket engine such as the SSME, which can be shut down after ignition either on the pad or in flight. The SSME was divided into its constituent components and subsystems. These were ranked on the basis of the possibility of being upgraded and risk of catastrophic failure. Once this was done the Shuttle program Hazard Analysis and Failure Modes and Effects Analysis (FMEA) were used to create a list of potential failure modes to be modeled. The groundrules and other criteria were used to screen out the many failure modes that did not contribute significantly to the catastrophic risk. The Hazard Analysis and FMEA for the SSME were also used to build ESDs that show the chain of events leading from the failure mode occurence to one of the following end states: catastrophic failure, engine shutdown, or siccessful operation( successful with respect to the failure mode under consideration).

Analytical tools for identification of non-intentionally added substances (NIAS) coming from polyurethane adhesives in multilayer packaging materials and their migration into food simulants.

PubMed

Félix, Juliana S; Isella, Francesca; Bosetti, Osvaldo; Nerín, Cristina

2012-07-01

Adhesives used in food packaging to glue different materials can provide several substances as potential migrants, and the identification of potential migrants and migration tests are required to assess safety in the use of adhesives. Solid-phase microextraction in headspace mode and gas chromatography coupled to mass spectrometry (HS-SPME-GC-MS) and ChemSpider and SciFinder databases were used as powerful tools to identify the potential migrants in the polyurethane (PU) adhesives and also in the individual plastic films (polyethylene terephthalate, polyamide, polypropylene, polyethylene, and polyethylene/ethyl vinyl alcohol). Migration tests were carried out by using Tenax(®) and isooctane as food simulants, and the migrants were analyzed by gas chromatography coupled to mass spectrometry. More than 63 volatile and semivolatile compounds considered as potential migrants were detected either in the adhesives or in the films. Migration tests showed two non-intentionally added substances (NIAS) coming from PU adhesives that migrated through the laminates into Tenax(®) and into isooctane. Identification of these NIAS was achieved through their mass spectra, and 1,6-dioxacyclododecane-7,12-dione and 1,4,7-trioxacyclotridecane-8,13-dione were confirmed. Caprolactam migrated into isooctane, and its origin was the external plastic film in the multilayer, demonstrating real diffusion through the multilayer structure. Comparison of the migration values between the simulants and conditions will be shown and discussed.

High Performance Hermetic Package For LiNbO3 Electro-Optic Waveguide Devices

NASA Astrophysics Data System (ADS)

Preston, K. R.; Macdonald, B. M.; Harmon, R. A.; Ford, C. W.; Shaw, R. N.; Reid, I.; Davidson, J. H.; Beaumont, A. R.; Booth, R. C.

1989-02-01

A high performance fibre-tailed package for LiNbO3 electro-optic waveguide devices is described. The package is based around a hermetic metal submodule which contains no epoxy or other organic materials. The LiNbO3 chip is mounted using a soldering technique, and laser welding is used for fibre fixing to give stable, low loss optical coupling to single mode fibres. Optical reflections are minimised by the use of antireflective coatings on the fibre ends and waveguide facets. High speed electrical connections are made via coplanar glass-sealed leadthroughs to LiNb03 travelling wave devices, and packaged device operation to frequencies in excess of 4GHz is demonstrated.

Spectral response characteristics of the transmission-mode aluminum gallium nitride photocathode with varying aluminum composition.

PubMed

Hao, Guanghui; Liu, Junle; Ke, Senlin

2017-12-10

In order to research spectral response characteristics of transmission-mode nanostructure aluminum gallium nitride (AlGaN) photocathodes, the AlGaN photocathodes materials with varied aluminum (Al) composition were grown by metalorganic chemical vapor deposition (MOCVD) and its optical properties were measured. The Al compositions of each AlGaN film of the photocathodes were analyzed from their adsorption properties curves; their thickness was also calculated by the matrix formula of thin-film optics. The nanostructure AlGaN photocathodes were activated with the Caesium-Oxygen (Cs-O) alternation, and after the photocathode was packaged in vacuum, their spectrum responses were measured. The experimental results showed that the trend of spectrum response curves first increased and then decreased along with the increasing of the incident light wavelength. The peak spectrum response value was 17.5 mA/W at 255 nm, and its quantum efficiency was 8.5%. The lattice defects near the interface of the AlGaN heterostructure could impede the electron motion crossing this region and moving toward the photocathode surface; this was a factor that reduces the electron emission performance of the photocathodes. Also, the experimental result showed that the thickness of each AlGaN layer affected the electron diffusion characteristics; this was a key factor that influenced the spectrum response performance.

Resistance switching mode transformation in SrRuO3/Cr-doped SrZrO3/Pt frameworks via a thermally activated Ti out-diffusion process

PubMed Central

Jo, Yongcheol; Jung, Kyooho; Kim, Jongmin; Woo, Hyeonseok; Han, Jaeseok; Kim, Hyungsang; Hong, Jinpyo; Lee, Jeon-Kook; Im, Hyunsik

2014-01-01

This work reports on a mechanism for irreversible resistive switching (RS) transformation from bipolar to unipolar RS behavior in SrRuO3 (SRO)/Cr-doped SrZrO3 (SZO:Cr)/Pt capacitor structures prepared on a Ti/SiO2/Si substrate. Counter-clockwise bipolar RS memory current-voltage (I–V) characteristics are observed within the RS voltage window of −2.5 to +1.9 V, with good endurance and retention properties. As the bias voltage increases further beyond 4 V under a forward bias, a forming process occurs resulting in irreversible RS mode transformation from bipolar to unipolar mode. This switching mode transformation is a direct consequence of thermally activated Ti out-diffusion from a Ti adhesion layer. Transition metal Ti effectively out-diffuses through the loose Pt electrode layer at high substrate temperatures, leading to the unintended formation of a thin titanium oxide (TiOx where x < 2) layer between the Pt electrode and the SZO:Cr layer as well as additional Ti atoms in the SZO:Cr layer. Cross-sectional scanning electron microscopy, transmission electron microscopy and Auger electron spectroscopy depth-profile measurements provided apparent evidence of the Ti out-diffusion phenomenon. We propose that the out-diffusion-induced additional Ti atoms in the SZO:Cr layer contributes to the creation of the metallic filamentary channels. PMID:25483325

Azimuthal ULF Structure and Radial Transport of Charged Particles

NASA Astrophysics Data System (ADS)

Ali, A.; Elkington, S. R.

2015-12-01

The Van Allen radiation belts contain highly energetic particles which interact with a variety of plasma and MHD waves. Waves with frequencies in the ULF range are understood to play an important role in loss and acceleration of energetic particles. There is still much to be understood about the interaction between charged particles and ULF waves in the inner magnetosphere and how they influence particle diffusion. We investigate how ULF wave power distribution in azimuth affects radial diffusion of charged particles. Analytic treatments of the diffusion coefficients generally assume uniform distribution of power in azimuth but in situ measurements suggest otherwise. The power profiles obtained from in situ measurements will be used to conduct particle simulations to see how well do the simulated diffusion coefficients agree with diffusion coefficients estimated directly from in situ measurements. We also look at the ULF wave power distribution across different modes. In order to use in situ point measurements from spacecraft, it is typically assumed that all of the wave power exists in m=1 mode. How valid is this assumption? Do higher modes contain a major fraction of the total power? If yes, then under what conditions? One strategy is to use the obtained realistic azimuthal power profiles from in situ measurements (such as from the Van Allen Probes) to drive simulations and see how the power distributions across modes larger than one depends on parameters such as the level of geomagnetic activity.

Modes of Meaning in High School Science. CELA Research Report.

ERIC Educational Resources Information Center

Young, Richard F.; Nguyen, Hanh Thi

Using the framework of systematic functional grammar, this study compares two modes of presenting the same scientific topic: in a physics textbook and in interactive teacher talk. Three aspects of scientific meaning making are analyzed: representations of physical and mental reality, lexical packaging, and the rhetorical structure of reasoning.…

Enhancing Effective Chemistry Learning through Hypermedia Instructional Mode of Delivery

ERIC Educational Resources Information Center

Abanikannda, Mutahir Oluwafemi

2016-01-01

This study provides a framework for the production of Hypermedia Instructional package. It also assessed the effectiveness of hypermedia instructional mode of delivery on students? performance in Chemistry. This is with a view of improving the learning of Chemistry which may eventually help to improve students? performance. The developmental study…

Product Support Manager Guidebook

DTIC Science & Technology

2011-04-01

package is being developed using supportability analysis concepts such as Failure Mode, Effects and Criticality Analysis (FMECA), Fault Tree Analysis ( FTA ...Analysis (LORA) Condition Based Maintenance + (CBM+) Fault Tree Analysis ( FTA ) Failure Mode, Effects, and Criticality Analysis (FMECA) Maintenance Task...Reporting and Corrective Action System (FRACAS), Fault Tree Analysis ( FTA ), Level of Repair Analysis (LORA), Maintenance Task Analysis (MTA

Square Turing patterns in reaction-diffusion systems with coupled layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Jing; Wang, Hongli, E-mail: hlwang@pku.edu.cn, E-mail: qi@pku.edu.cn; Center for Quantitative Biology, Peking University, Beijing 100871

Square Turing patterns are usually unstable in reaction-diffusion systems and are rarely observed in corresponding experiments and simulations. We report here an example of spontaneous formation of square Turing patterns with the Lengyel-Epstein model of two coupled layers. The squares are found to be a result of the resonance between two supercritical Turing modes with an appropriate ratio. Besides, the spatiotemporal resonance of Turing modes resembles to the mode-locking phenomenon. Analysis of the general amplitude equations for square patterns reveals that the fixed point corresponding to square Turing patterns is stationary when the parameters adopt appropriate values.

Reliability evaluation of hermetic dual in-line flat microcircuit packages

NASA Technical Reports Server (NTRS)

Johnson, G. M.; Conaway, L. K.

1977-01-01

The relative strengths and weaknesses of 35 commonly used hermetic flat and dual in-line packages were determined and used to rank each of the packages according to a numerical weighting scheme for package attributes. The list of attributes included desirable features in five major areas: lead and lead seal, body construction, body materials, lid and lid seal, and marking. The metal flat pack and multilayer integral ceramic flat pack and DIP received the highest rankings, and the soft glass Cerdip and Cerpak types received the lowest rankings. Loss of package hermeticity due to lead and lid seal problems was found to be the predominant failure mode from the literature/data search. However, environmental test results showed that lead and lid seal failures due to thermal stressing was only a problem with the hard glass (Ceramic) body DIP utilizing a metal lid and/or bottom. Insufficient failure data were generated for the other package types tested to correlate test results with the package ranking.

Fibonacci family of dynamical universality classes

PubMed Central

Popkov, Vladislav; Schadschneider, Andreas; Schmidt, Johannes; Schütz, Gunter M.

2015-01-01

Universality is a well-established central concept of equilibrium physics. However, in systems far away from equilibrium, a deeper understanding of its underlying principles is still lacking. Up to now, a few classes have been identified. Besides the diffusive universality class with dynamical exponent z=2, another prominent example is the superdiffusive Kardar−Parisi−Zhang (KPZ) class with z=3/2. It appears, e.g., in low-dimensional dynamical phenomena far from thermal equilibrium that exhibit some conservation law. Here we show that both classes are only part of an infinite discrete family of nonequilibrium universality classes. Remarkably, their dynamical exponents zα are given by ratios of neighboring Fibonacci numbers, starting with either z1=3/2 (if a KPZ mode exist) or z1=2 (if a diffusive mode is present). If neither a diffusive nor a KPZ mode is present, all dynamical modes have the Golden Mean z=(1+5)/2 as dynamical exponent. The universal scaling functions of these Fibonacci modes are asymmetric Lévy distributions that are completely fixed by the macroscopic current density relation and compressibility matrix of the system and hence accessible to experimental measurement. PMID:26424449

LC-MS/MS analytical procedure to quantify tris(nonylphenyl)phosphite, as a source of the endocrine disruptors 4-nonylphenols, in food packaging materials.

PubMed

Mottier, Pascal; Frank, Nancy; Dubois, Mathieu; Tarres, Adrienne; Bessaire, Thomas; Romero, Roman; Delatour, Thierry

2014-01-01

Tris(nonylphenyl)phosphite, an antioxidant used in polyethylene resins for food applications, is problematic since it is a source of the endocrine-disrupting chemicals 4-nonylphenols (4NP) upon migration into packaged foods. As a response to concerns surrounding the presence of 4NP-based compounds in packaging materials, some resin producers and additive suppliers have decided to eliminate TNPP from formulations. This paper describes an analytical procedure to verify the "TNPP-free" statement in multilayer laminates used for bag-in-box packaging. The method involves extraction of TNPP from laminates with organic solvents followed by detection/quantification by LC-MS/MS using the atmospheric pressure chemical ionisation (APCI) mode. A further acidic treatment of the latter extract allows the release of 4NP from potentially extracted TNPP. 4NP is then analysed by LC-MS/MS using electrospray ionisation (ESI) mode. This two-step analytical procedure ensures not only TNPP quantification in laminates, but also allows the flagging of other possible sources of 4NP in such packaging materials, typically as non-intentionally added substances (NIAS). The limits of quantification were 0.50 and 0.48 µg dm⁻² for TNPP and 4NP in laminates, respectively, with recoveries ranging between 87% and 114%. Usage of such analytical methodologies in quality control operations has pointed to a lack of traceability at the packaging supplier level and cross-contamination of extrusion equipment at the converter level, when TNPP-containing laminates are processed on the same machine beforehand.

Three distinct modes in a surface micro-discharge in atmospheric pressure He + N{sub 2} mixtures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Dong; Liu, Dingxin, E-mail: liudingxin@mail.xjtu.edu.cn; He, Tongtong

2015-12-15

A surface micro-discharge in atmospheric pressure He + N{sub 2} mixtures is studied in this paper with an emphasis on the discharge modes. With the N{sub 2} admixture increasing from 0.1% to 20%, the discharge evolves from a spatially diffuse mode to a filamentary mode during positive half-cycles of the applied voltage. However during the negative half-cycles, an additional patterned mode emerges between the diffuse and the filamentary modes, which has not been reported before to exist in surface micro-discharges. In the diffuse and patterned modes, the plasmas cover almost the entirety of the mesh area during one cycle after plasma ignitionmore » in all mesh elements, and the discharge power increases linearly with the applied voltage. In contrast, plasma coverage of the mesh area is only partial in the filamentary mode and the plasma is more unstable with the discharge power increasing exponentially with the applied voltage. As the surface micro-discharge evolves through the three modes, the density of excited species changes significantly, for instance, the density of N{sub 2}{sup +}(B) drops by ∼20-fold from [N{sub 2}] = 0.2% to 20%. The N{sub 2}{sup +}(B) is predicted to be generated mainly through successive processes of Penning ionization by helium metastables and electron-impact excitation of N{sub 2}{sup +}(X), the latter is most responsible for the density decrease of N{sub 2}{sup +}(B) because much more N{sub 2}{sup +}(X) is converted to N{sub 4}{sup +}(X) as the increase of N{sub 2} fraction. Also, the electron density and electron temperature decrease with the discharge mode transition.« less

Correlation Between the Field Line and Particle Diffusion Coefficients in the Stochastic Fields of a Tokamak

NASA Astrophysics Data System (ADS)

Calvin, Mark; Punjabi, Alkesh

1996-11-01

We use the method of quasi-magnetic surfaces to calculate the correlation between the field line and particle diffusion coefficients. The magnetic topology of a tokamak is perturbed by a spectrum of neighboring resonant resistive modes. The Hamiltonian equations of motion for the field line are integrated numerically. Poincare plots of the quasi-magnetic surfaces are generated initially and after the field line has traversed a considerable distance. From the areas of the quasi-magnetic surfaces and the field line distance, we estimate the field line diffusion coefficient. We start plasma particles on the initial quasi-surface, and calculate the particle diffusion coefficient from our Monte Carlo method (Punjabi A., Boozer A., Lam M., Kim H. and Burke K., J. Plasma Phys.), 44, 405 (1990). We then estimate the correlation between the particle and field diffusion as the strength of the resistive modes is varied.

Simulation of stationary glow patterns in dielectric barrier discharges at atmospheric pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Fucheng, E-mail: hdlfc@hbu.cn; He, Yafeng; Dong, Lifang

2014-12-15

Self-organized stationary patterns in dielectric barrier discharges operating in glow regime at atmospheric pressure are investigated by a self-consistent two-dimensional fluid model. The simulation results show that two different modes, namely, the diffuse mode and the static patterned mode, can be formed in different ranges of the driving frequency. The discharge operates in Townsend regime in the diffuse mode, while it operates in a glow regime inside the filaments and in a Townsend regime outside the filaments in the stable pattered mode. The forming process of the stationary filaments can be divided into three stages, namely, destabilizing stage, self-assembling stage,more » and stable stage. The space charge associated with residual electron density and surface charge is responsible for the formation of these stationary glow patterns.« less

Pitch Angle Scattering of Upgoing Electron Beams in Jupiter's Polar Regions by Whistler Mode Waves

NASA Astrophysics Data System (ADS)

Elliott, S. S.; Gurnett, D. A.; Kurth, W. S.; Clark, G.; Mauk, B. H.; Bolton, S. J.; Connerney, J. E. P.; Levin, S. M.

2018-02-01

The Juno spacecraft's Jupiter Energetic-particle Detector Instrument has observed field-aligned, unidirectional (upgoing) electron beams throughout most of Jupiter's entire polar cap region. The Waves instrument detected intense broadband whistler mode emissions occurring in the same region. In this paper, we investigate the pitch angle scattering of the upgoing electron beams due to interactions with the whistler mode waves. Profiles of intensity versus pitch angle for electron beams ranging from 2.53 to 7.22 Jovian radii show inconsistencies with the expected adiabatic invariant motion of the electrons. It is believed that the observed whistler mode waves perturb the electron motion and scatter them away from the magnetic field line. The diffusion equation has been solved by using diffusion coefficients which depend on the magnetic intensity of the whistler mode waves.

Migration and sorption phenomena in packaged foods.

PubMed

Gnanasekharan, V; Floros, J D

1997-10-01

Rapidly developing analytical capabilities and continuously evolving stringent regulations have made food/package interactions a subject of intense research. This article focuses on: (1) the migration of package components such as oligomers and monomers, processing aids, additives, and residual reactants in to packaged foods, and (2) sorption of food components such as flavors, lipids, and moisture into packages. Principles of diffusion and thermodynamics are utilized to describe the mathematics of migration and sorption. Mathematical models are developed from first principles, and their applicability is illustrated using numerical simulations and published data. Simulations indicate that available models are system (polymer-penetrant) specific. Furthermore, some models best describe the early stages of migration/sorption, whereas others should be used for the late stages of these phenomena. Migration- and/or sorption-related problems with respect to glass, metal, paper-based and polymeric packaging materials are discussed, and their importance is illustrated using published examples. The effects of migrating and absorbed components on food safety, quality, and the environment are presented for various foods and packaging materials. The impact of currently popular packaging techniques such as microwavable, ovenable, and retortable packaging on migration and sorption are discussed with examples. Analytical techniques for investigating migration and sorption phenomena in food packaging are critically reviewed, with special emphasis on the use and characteristics of food-simulating liquids (FSLs). Finally, domestic and international regulations concerning migration in packaged foods, and their impact on food packaging is briefly presented.

A model for the selective amplification of spatially coherent waves in a centrifugal compressor on the verge of rotating stall

NASA Technical Reports Server (NTRS)

Lawless, Patrick B.; Fleeter, Sanford

1993-01-01

A simple model for the stability zones of a low speed centrifugal compressor is developed, with the goal of understanding the driving mechanism for the changes in stalling behavior predicted for, and observed in, the Purdue Low Speed Centrifugal Research Compressor Facility. To this end, earlier analyses of rotating stall suppression in centrifugal compressors are presented in a reduced form that preserves the essential parameters of the model that affect the stalling behavior of the compressor. The model is then used to illuminate the relationship between compressor geometry, expected mode shape, and regions of amplification for weak waves which are indicative of the susceptibility of the system to rotating stall. The results demonstrate that increasing the stagger angle of the diffuser vanes, and consequently the diffusion path length, results in the compressor moving towards a condition where higher-order spatial modes are excited during stall initiation. Similarly, flow acceleration in the diffuser section caused by an increase in the number of diffuser vanes also results in the excitation of higher modes.

Compact structure and non-Gaussian dynamics of ring polymer melts.

PubMed

Brás, Ana R; Goossen, Sebastian; Krutyeva, Margarita; Radulescu, Aurel; Farago, Bela; Allgaier, Jürgen; Pyckhout-Hintzen, Wim; Wischnewski, Andreas; Richter, Dieter

2014-05-28

We present a neutron scattering analysis of the structure and dynamics of PEO polymer rings with a molecular weight 2.5 times higher than the entanglement mass. The melt structure was found to be more compact than a Gaussian model would suggest. With increasing time the center of mass (c.o.m.) diffusion undergoes a transition from sub-diffusive to diffusive behavior. The transition time agrees well with the decorrelation time predicted by a mode coupling approach. As a novel feature well pronounced non-Gaussian behavior of the c.o.m. diffusion was found that shows surprising analogies to the cage effect known from glassy systems. Finally, the longest wavelength Rouse modes are suppressed possibly as a consequence of an onset of lattice animal features as hypothesized in theoretical approaches.

Saturation of the lower-hybrid-drift instability by mode coupling

NASA Technical Reports Server (NTRS)

Drake, J. F.; Guzdar, P. N.; Huba, J. D.

1983-01-01

A nonlinear mode-coupling theory of the lower-hybrid-drift instability is presented. It is found that the instability saturates by transferring energy from the growing, long wavelength modes to the damped, short wavelength modes. The saturation energy, mean square of the potential fluctuations, and diffusion coefficient are calculated self-consistently.

Kinetic theory of nonlinear diffusion in a weakly disordered nonlinear Schrödinger chain in the regime of homogeneous chaos.

PubMed

Basko, D M

2014-02-01

We study the discrete nonlinear Schröinger equation with weak disorder, focusing on the regime when the nonlinearity is, on the one hand, weak enough for the normal modes of the linear problem to remain well resolved but, on the other, strong enough for the dynamics of the normal mode amplitudes to be chaotic for almost all modes. We show that in this regime and in the limit of high temperature, the macroscopic density ρ satisfies the nonlinear diffusion equation with a density-dependent diffusion coefficient, D(ρ) = D(0)ρ(2). An explicit expression for D(0) is obtained in terms of the eigenfunctions and eigenvalues of the linear problem, which is then evaluated numerically. The role of the second conserved quantity (energy) in the transport is also quantitatively discussed.

Calculations of lattice vibrational mode lifetimes using Jazz: a Python wrapper for LAMMPS

NASA Astrophysics Data System (ADS)

Gao, Y.; Wang, H.; Daw, M. S.

2015-06-01

Jazz is a new python wrapper for LAMMPS [1], implemented to calculate the lifetimes of vibrational normal modes based on forces as calculated for any interatomic potential available in that package. The anharmonic character of the normal modes is analyzed via the Monte Carlo-based moments approximation as is described in Gao and Daw [2]. It is distributed as open-source software and can be downloaded from the website http://jazz.sourceforge.net/.

Mitigating leakage errors due to cavity modes in a superconducting quantum computer

NASA Astrophysics Data System (ADS)

McConkey, T. G.; Béjanin, J. H.; Earnest, C. T.; McRae, C. R. H.; Pagel, Z.; Rinehart, J. R.; Mariantoni, M.

2018-07-01

A practical quantum computer requires quantum bit (qubit) operations with low error probabilities in extensible architectures. We study a packaging method that makes it possible to address hundreds of superconducting qubits by means of coaxial Pogo pins. A qubit chip is housed in a superconducting box, where both box and chip dimensions lead to unwanted modes that can interfere with qubit operations. We analyze these interference effects in the context of qubit coherent leakage and qubit decoherence induced by damped modes. We propose two methods, half-wave fencing and antinode pinning, to mitigate the resulting errors by detuning the resonance frequency of the modes from the qubit frequency. We perform electromagnetic field simulations indicating that the resonance frequency of the modes increases with the number of installed pins and can be engineered to be significantly higher than the highest qubit frequency. We estimate that the error probabilities and decoherence rates due to suitably shifted modes in realistic scenarios can be up to two orders of magnitude lower than the state-of-the-art superconducting qubit error and decoherence rates. Our methods can be extended to different types of packages that do not rely on Pogo pins. Conductive bump bonds, for example, can serve the same purpose in qubit architectures based on flip chip technology. Metalized vias, instead, can be used to mitigate modes due to the increasing size of the dielectric substrate on which qubit arrays are patterned.

Impurity confinement and transport in high confinement regimes without edge localized modes on DIII-D [Impurity confinement and transport in high confinement regimes without ELMs on DIII-D

DOE PAGES

Grierson, Brian A.; Burrell, Keith H.; Nazikian, Raffi M.; ...

2015-04-17

Here, impurity transport in the DIII-D tokamak is investigated in stationary high confinement (H-mode) regimes without edge localized modes (ELMs). In plasmas maintained by resonant magnetic perturbation (RMP) ELM-suppression and QH-mode the confinement time of fluorine (Z=9) is equivalent to that in ELMing discharges with 40 Hz ELMs. For selected discharges with impurity injection the impurity particle confinement time compared to the energy confinement time is in the range of τ p/τ e ≈ 2 $-$ 3. In QH-mode operation the impurity confinement time is shown to be smaller for intense, coherent magnetic and density fluctuations of the edge harmonicmore » oscillation than weaker fluctuations. Transport coefficients are derived from the time evolution of the impurity density profile and compared to neoclassical and turbulent transport models NEO and TGLF. Neoclassical transport of fluorine is found to be small compared to the experimental values. In the ELMing and RMP ELM-suppressed plasma the impurity transport is affected by the presence of tearing modes. For radii larger than the mode radius the TGLF diffusion coefficient is smaller than the experimental value by a factor of 2-3, while the convective velocity is within error estimates. Low levels of diffusion are observed for radii smaller than the tearing mode radius. In the QH-mode plasma investigated, the TGLF diffusion coefficient higher inside of ρ = 0.4 and lower outside of 0.4 than the experiment, and the TGLF convective velocity is more negative by a factor of approximately 1.7.« less

Final system instrumentation design package for Decade 80 solar house

NASA Technical Reports Server (NTRS)

1978-01-01

The final configuration of the Decade 80 solar house to monitor and collect system performance data is presented. A review demonstrated by actual operation that the system and the data acquisition subsystem operated satisfactorily and installation of instrumentation was in accordance with the design. This design package is made up of (1) site and system description, (2) operating and control modes, and (3) instrumentation program (including sensor schematic).

Fiber optic interconnect and optoelectronic packaging challenges for future generation avionics

NASA Astrophysics Data System (ADS)

Beranek, Mark W.

2007-02-01

Forecasting avionics industry fiber optic interconnect and optoelectronic packaging challenges that lie ahead first requires an assumption that military avionics architectures will evolve from today's centralized/unified concept based on gigabit laser, optical-to-electrical-to-optical switching and optical backplane technology, to a future federated/distributed or centralized/unified concept based on gigabit tunable laser, electro-optical switch and add-drop wavelength division multiplexing (WDM) technology. The requirement to incorporate avionics optical built-in test (BIT) in military avionics fiber optic systems is also assumed to be correct. Taking these assumptions further indicates that future avionics systems engineering will use WDM technology combined with photonic circuit integration and advanced packaging to form the technical basis of the next generation military avionics onboard local area network (LAN). Following this theme, fiber optic cable plants will evolve from today's multimode interconnect solution to a single mode interconnect solution that is highly installable, maintainable, reliable and supportable. Ultimately optical BIT for fiber optic fault detection and isolation will be incorporated as an integral part of a total WDM-based avionics LAN solution. Cost-efficient single mode active and passive photonic component integration and packaging integration is needed to enable reliable operation in the harsh military avionics application environment. Rugged multimode fiber-based transmitters and receivers (transceivers) with in-package optical BIT capability are also needed to enable fully BIT capable single-wavelength fiber optic links on both legacy and future aerospace platforms.

WavePropaGator: interactive framework for X-ray free-electron laser optics design and simulations.

PubMed

Samoylova, Liubov; Buzmakov, Alexey; Chubar, Oleg; Sinn, Harald

2016-08-01

This article describes the WavePropaGator ( WPG ) package, a new interactive software framework for coherent and partially coherent X-ray wavefront propagation simulations. The package has been developed at European XFEL for users at the existing and emerging free-electron laser (FEL) facilities, as well as at the third-generation synchrotron sources and future diffraction-limited storage rings. The WPG addresses the needs of beamline scientists and user groups to facilitate the design, optimization and improvement of X-ray optics to meet their experimental requirements. The package uses the Synchrotron Radiation Workshop ( SRW ) C/C++ library and its Python binding for numerical wavefront propagation simulations. The framework runs reliably under Linux, Microsoft Windows 7 and Apple Mac OS X and is distributed under an open-source license. The available tools allow for varying source parameters and optics layouts and visualizing the results interactively. The wavefront history structure can be used for tracking changes in every particular wavefront during propagation. The batch propagation mode enables processing of multiple wavefronts in workflow mode. The paper presents a general description of the package and gives some recent application examples, including modeling of full X-ray FEL beamlines and start-to-end simulation of experiments.

Diffuse-direct ultraviolet ratios with a compact double monochromator

NASA Technical Reports Server (NTRS)

Garrison, L. M.; Murray, L. E.; Doda, D. D.; Green, A. E. S.

1978-01-01

An improved system has been implemented for measuring the ratio of the diffuse skylight to the direct sunlight in the biologically active region of the UV near the atmospheric limit. It combines a double monochromator employing holographic gratings for reduction of stray light with a cooled photomultiplier tube to provide a greatly improved SNR below 300 nm. Data may be obtained in either a scan mode or a narrowband photometry mode; in the latter mode accurate ratios have been obtained near 290 nm. Representative data are discussed along with a theoretical model of the ratio. The system is compact enough for use in a mobile monitoring system.

The optimal thickness of a transmission-mode GaN photocathode

NASA Astrophysics Data System (ADS)

Wang, Xiao-Hui; Shi, Feng; Guo, Hui; Hu, Cang-Lu; Cheng, Hong-Chang; Chang, Ben-Kang; Ren, Ling; Du, Yu-Jie; Zhang, Jun-Ju

2012-08-01

A 150-nm-thick GaN photocathode with a Mg doping concentration of 1.6 × 1017 cm-3 is activated by Cs/O in an ultrahigh vacuum chamber, and a quantum efficiency (QE) curve of the negative electron affinity transmission-mode (t-mode) of the GaN photocathode is obtained. The maximum QE reaches 13.0% at 290 nm. According to the t-mode QE equation solved from the diffusion equation, the QE curve is fitted. From the fitting results, the electron escape probability is 0.32, the back-interface recombination velocity is 5 × 104 cm·s-1, and the electron diffusion length is 116 nm. Based on these parameters, the influence of GaN thickness on t-mode QE is simulated. The simulation shows that the optimal thickness of GaN is 90 nm, which is better than the 150-nm GaN.

A strong diffusive ion mode in dense ionized matter predicted by Langevin dynamics

PubMed Central

Mabey, P.; Richardson, S.; White, T. G.; Fletcher, L. B.; Glenzer, S. H.; Hartley, N. J.; Vorberger, J.; Gericke, D. O.; Gregori, G.

2017-01-01

The state and evolution of planets, brown dwarfs and neutron star crusts is determined by the properties of dense and compressed matter. Due to the inherent difficulties in modelling strongly coupled plasmas, however, current predictions of transport coefficients differ by orders of magnitude. Collective modes are a prominent feature, whose spectra may serve as an important tool to validate theoretical predictions for dense matter. With recent advances in free electron laser technology, X-rays with small enough bandwidth have become available, allowing the investigation of the low-frequency ion modes in dense matter. Here, we present numerical predictions for these ion modes and demonstrate significant changes to their strength and dispersion if dissipative processes are included by Langevin dynamics. Notably, a strong diffusive mode around zero frequency arises, which is not present, or much weaker, in standard simulations. Our results have profound consequences in the interpretation of transport coefficients in dense plasmas. PMID:28134338

Survey of upper band chorus and ECH waves: Implications for the diffuse aurora

NASA Astrophysics Data System (ADS)

Meredith, Nigel; Horne, Richard; Thorne, Richard; Anderson, Roger

2010-05-01

The origin of the diffuse aurora has been a source of controversy for many years. More recently the question has taken a new significance in view of the associated changes in atmospheric chemistry which may affect the middle atmosphere. Here we use CRRES data to assess the importance of upper band chorus and electron cyclotron harmonic (ECH) waves in the production of the diffuse aurora. Both wave modes increase with increasing geomagnetic activity, suggesting they are related to periods of enhanced convection and/or substorm activity. They are confined to the near-equatorial region which excludes the pre-noon sector from the wave survey. During active conditions intense ECH waves and upper band chorus, with amplitudes exceeding 1 mVm-1, are observed in the region 4 < L < 7 from 2100 to 0600 MLT approximately 20% and 6% of the time respectively. This suggests that both wave modes can put electrons on strong diffusion, but only during active conditions and not at all local times. Scattering rates fall below the strong diffusion limit at other times when the wave amplitudes are weaker. Fluxes of low energy electrons (100 eV < E < 30 keV) also increase with increasing geomagnetic activity in approximately the same region of geospace as the waves, suggesting that these electrons are responsible for the generation of the waves. The patterns of the upper band chorus, ECH waves and low energy electrons are similar to the global morphology of the diffuse aurora, suggesting that both wave modes play significant roles in the production of the diffuse aurora.

Retrospective correction of bias in diffusion tensor imaging arising from coil combination mode.

PubMed

Sakaie, Ken; Lowe, Mark

2017-04-01

To quantify and retrospectively correct for systematic differences in diffusion tensor imaging (DTI) measurements due to differences in coil combination mode. Multi-channel coils are now standard among MRI systems. There are several options for combining signal from multiple coils during image reconstruction, including sum-of-squares (SOS) and adaptive combine (AC). This contribution examines the bias between SOS- and AC-derived measures of tissue microstructure and a strategy for limiting that bias. Five healthy subjects were scanned under an institutional review board-approved protocol. Each set of raw image data was reconstructed twice-once with SOS and once with AC. The diffusion tensor was calculated from SOS- and AC-derived data by two algorithms-standard log-linear least squares and an approach that accounts for the impact of coil combination on signal statistics. Systematic differences between SOS and AC in terms of tissue microstructure (axial diffusivity, radial diffusivity, mean diffusivity and fractional anisotropy) were evaluated on a voxel-by-voxel basis. SOS-based tissue microstructure values are systematically lower than AC-based measures throughout the brain in each subject when using the standard tensor calculation method. The difference between SOS and AC can be virtually eliminated by taking into account the signal statistics associated with coil combination. The impact of coil combination mode on diffusion tensor-based measures of tissue microstructure is statistically significant but can be corrected retrospectively. The ability to do so is expected to facilitate pooling of data among imaging protocols. Copyright © 2016 Elsevier Inc. All rights reserved.

Reviews.

ERIC Educational Resources Information Center

Journal of Chemical Education, 1988

1988-01-01

Reviews three computer software packages for chemistry education including "Osmosis and Diffusion" and "E.M.E. Titration Lab" for Apple II and "Simplex-V: An Interactive Computer Program for Experimental Optimization" for IBM PC. Summary ratings include ease of use, content, pedagogic value, student reaction, and…

Using optical fibers with different modes to improve the signal-to-noise ratio of diffuse correlation spectroscopy flow-oximeter measurements

PubMed Central

He, Lian; Lin, Yu; Shang, Yu; Shelton, Brent J.

2013-01-01

Abstract. The dual-wavelength diffuse correlation spectroscopy (DCS) flow-oximeter is an emerging technique enabling simultaneous measurements of blood flow and blood oxygenation changes in deep tissues. High signal-to-noise ratio (SNR) is crucial when applying DCS technologies in the study of human tissues where the detected signals are usually very weak. In this study, single-mode, few-mode, and multimode fibers are compared to explore the possibility of improving the SNR of DCS flow-oximeter measurements. Experiments on liquid phantom solutions and in vivo muscle tissues show only slight improvements in flow measurements when using the few-mode fiber compared with using the single-mode fiber. However, light intensities detected by the few-mode and multimode fibers are increased, leading to significant SNR improvements in detections of phantom optical property and tissue blood oxygenation. The outcomes from this study provide useful guidance for the selection of optical fibers to improve DCS flow-oximeter measurements. PMID:23455963

Methods to Control EMI Noises Produced in Power Converter Systems

NASA Astrophysics Data System (ADS)

Mutoh, Nobuyoshi; Ogata, Mitukatu

A new method to control EMI noises produced in power converters (rectifier and inverter) composed of IPMs (Intelligent Power Modules) is studied especially focusing on differential mode noises. The differential mode noises are occurred due to switching operations of the PWM control. As they are diffused into the ground through stray capacitors distributed between the ground and the power transmission lines and machine frames, differential mode noises should be confined and suppressed within the smallest area where power converters are laid out. It is impossible to control differential mode noises easily occurring diffusion by the conventional methods like filtering techniques. So, a new EMI noise control method using a multi-power circuit technique is proposed. The proposed method of the effectiveness has been verified through simulations and experiments.

Packaged integrated opto-fluidic solution for harmful fluid analysis

NASA Astrophysics Data System (ADS)

Allenet, T.; Bucci, D.; Geoffray, F.; Canto, F.; Couston, L.; Jardinier, E.; Broquin, J.-E.

2016-02-01

Advances in nuclear fuel reprocessing have led to a surging need for novel chemical analysis tools. In this paper, we present a packaged lab-on-chip approach with co-integration of optical and micro-fluidic functions on a glass substrate as a solution. A chip was built and packaged to obtain light/fluid interaction in order for the entire device to make spectral measurements using the photo spectroscopy absorption principle. The interaction between the analyte solution and light takes place at the boundary between a waveguide and a fluid micro-channel thanks to the evanescent part of the waveguide's guided mode that propagates into the fluid. The waveguide was obtained via ion exchange on a glass wafer. The input and the output of the waveguides were pigtailed with standard single mode optical fibers. The micro-scale fluid channel was elaborated with a lithography procedure and hydrofluoric acid wet etching resulting in a 150+/-8 μm deep channel. The channel was designed with fluidic accesses, in order for the chip to be compatible with commercial fluidic interfaces/chip mounts. This allows for analyte fluid in external capillaries to be pumped into the device through micro-pipes, hence resulting in a fully packaged chip. In order to produce this co-integrated structure, two substrates were bonded. A study of direct glass wafer-to-wafer molecular bonding was carried-out to improve detector sturdiness and durability and put forward a bonding protocol with a bonding surface energy of γ>2.0 J.m-2. Detector viability was shown by obtaining optical mode measurements and detecting traces of 1.2 M neodymium (Nd) solute in 12+/-1 μL of 0.01 M and pH 2 nitric acid (HNO3) solvent by obtaining an absorption peak specific to neodymium at 795 nm.

Mixing with applications to inertial-confinement-fusion implosions

NASA Astrophysics Data System (ADS)

Rana, V.; Lim, H.; Melvin, J.; Glimm, J.; Cheng, B.; Sharp, D. H.

2017-01-01

Approximate one-dimensional (1D) as well as 2D and 3D simulations are playing an important supporting role in the design and analysis of future experiments at National Ignition Facility. This paper is mainly concerned with 1D simulations, used extensively in design and optimization. We couple a 1D buoyancy-drag mix model for the mixing zone edges with a 1D inertial confinement fusion simulation code. This analysis predicts that National Ignition Campaign (NIC) designs are located close to a performance cliff, so modeling errors, design features (fill tube and tent) and additional, unmodeled instabilities could lead to significant levels of mix. The performance cliff we identify is associated with multimode plastic ablator (CH) mix into the hot-spot deuterium and tritium (DT). The buoyancy-drag mix model is mode number independent and selects implicitly a range of maximum growth modes. Our main conclusion is that single effect instabilities are predicted not to lead to hot-spot mix, while combined mode mixing effects are predicted to affect hot-spot thermodynamics and possibly hot-spot mix. Combined with the stagnation Rayleigh-Taylor instability, we find the potential for mix effects in combination with the ice-to-gas DT boundary, numerical effects of Eulerian species CH concentration diffusion, and ablation-driven instabilities. With the help of a convenient package of plasma transport parameters developed here, we give an approximate determination of these quantities in the regime relevant to the NIC experiments, while ruling out a variety of mix possibilities. Plasma transport parameters affect the 1D buoyancy-drag mix model primarily through its phenomenological drag coefficient as well as the 1D hydro model to which the buoyancy-drag equation is coupled.

Mixing with applications to inertial-confinement-fusion implosions.

PubMed

Rana, V; Lim, H; Melvin, J; Glimm, J; Cheng, B; Sharp, D H

2017-01-01

Approximate one-dimensional (1D) as well as 2D and 3D simulations are playing an important supporting role in the design and analysis of future experiments at National Ignition Facility. This paper is mainly concerned with 1D simulations, used extensively in design and optimization. We couple a 1D buoyancy-drag mix model for the mixing zone edges with a 1D inertial confinement fusion simulation code. This analysis predicts that National Ignition Campaign (NIC) designs are located close to a performance cliff, so modeling errors, design features (fill tube and tent) and additional, unmodeled instabilities could lead to significant levels of mix. The performance cliff we identify is associated with multimode plastic ablator (CH) mix into the hot-spot deuterium and tritium (DT). The buoyancy-drag mix model is mode number independent and selects implicitly a range of maximum growth modes. Our main conclusion is that single effect instabilities are predicted not to lead to hot-spot mix, while combined mode mixing effects are predicted to affect hot-spot thermodynamics and possibly hot-spot mix. Combined with the stagnation Rayleigh-Taylor instability, we find the potential for mix effects in combination with the ice-to-gas DT boundary, numerical effects of Eulerian species CH concentration diffusion, and ablation-driven instabilities. With the help of a convenient package of plasma transport parameters developed here, we give an approximate determination of these quantities in the regime relevant to the NIC experiments, while ruling out a variety of mix possibilities. Plasma transport parameters affect the 1D buoyancy-drag mix model primarily through its phenomenological drag coefficient as well as the 1D hydro model to which the buoyancy-drag equation is coupled.

Evolution of Edge Pedestal Profiles Between ELMs

NASA Astrophysics Data System (ADS)

Floyd, J. P.; Stacey, W. M.; Groebner, R. J.

2012-10-01

The measured edge profile evolution in DIII-D discharges is analyzed in terms of the implied thermal diffusivities, ion diffusion coefficients and pinch velocities, using the momentum-balance methodology of Ref. [1], extended to take into account ion orbit loss and X-point loss. The evolution of the density, temperature, rotation and radial electric field profiles in the edge pedestal between edge localized modes (ELMs) provides information of these diffusive and non-diffusive transport processes in the pedestal of H-mode plasmas. This methodology is incorporated in the GTEDGE code developed for DIII-D data interpretation. Using a smaller integration time for the charge exchange recombination measurements than in Ref. [1] allows a more detailed examination of the time evolution of the ion temperature and rotation profiles. 6pt [1] W.M. Stacey and R.J. Groebner, Nucl. Fusion 51, 063024 (2011).

Near Field Imaging of Gallium Nitride Nanowires for Characterization of Minority Carrier Diffusion

DTIC Science & Technology

2009-12-01

diffusion length in nanowires is critical to potential applications in solar cells , spectroscopic sensing, and/or lasers and light emitting diodes (LED...technique has been successfully demonstrated with thin film solar cell materials [4, 5]. In these experiments, the diffusion length was measured using a...minority carrier diffusion length . This technique has been used in the near-field collection mode to image the diffusion of holes in n-type GaN

New Edible Bionanocomposite Prepared by Pectin and Clove Essential Oil Nanoemulsions.

PubMed

Sasaki, Ronaldo S; Mattoso, Luiz H C; de Moura, Márcia Regina

2016-06-01

Nanocomposites are being extremely investigated to provide packaging with interesting characteristics for packages. Because of essential oils' natural occurrence and antibacterial activity, they are considered as an alternative for synthetic additives in the food industry. In this paper, we studied an edible bionanocomposite film made up of pectin and clove essential oil nanoemulsion for application as edible package. Mechanical properties, water vapor permeability (WVP), and antibacterial activity were analyzed. From mechanical and WVP analyses, we noticed an interesting improvement in film properties. In the antibacterial activity test, disk diffusion was used to assess the inhibition zones of Escherichia coli and Staphylococcus aureus. With these results, we concluded that the most interesting results were promoted by smaller nanodroplets (diameter of approximately 142 nm).

Benthic marine litter in four Gulfs in Greece, Eastern Mediterranean; abundance, composition and source identification

NASA Astrophysics Data System (ADS)

Koutsodendris, Andreas; Papatheodorou, George; Kougiourouki, Ourania; Georgiadis, Michalis

2008-04-01

The types, abundance, distribution and sources of benthic marine litter found in four Greek Gulfs (Patras, Corinth, Echinades and Lakonikos) were studied using bottom trawl nets. Mean distribution and weight densities range between 72-437 Item/km 2 and 6.7-47.4 kg/km 2. Litter items were sorted into material and usage categories. Plastic litter (56%) is the most dominant material category followed by metal (17%) and glass (11%). Beverage packaging (32%) is the dominant usage category followed by general packaging (28%) and food packaging (21%). Based on the typological results three dominant litter sources were identified; land-based, vessel-based and fishery-based. Application of factor analysis (R- and Q-mode) conducted on both material and usage litter datasets confirmed the existence of the three dominant litter sources. Q-mode analysis further resulted in the quantification of the litter sources; land-based ones provided the majority (69%) of the total litter items followed by vessel-based (26%) and fishery-based (5%) sources. Diverse environmental parameters influence significantly these amounts among the four Gulfs.

ICEG2D: An Integrated Software Package for Automated Prediction of Flow Fields for Single-Element Airfoils with Ice Accretion

NASA Technical Reports Server (NTRS)

Thompson, David S.; Soni, Bharat K.

2000-01-01

An integrated software package, ICEG2D, was developed to automate computational fluid dynamics (CFD) simulations for single-element airfoils with ice accretion. ICEG2D is designed to automatically perform three primary functions: (1) generating a grid-ready, surface definition based on the geometrical characteristics of the iced airfoil surface, (2) generating a high-quality grid using the generated surface point distribution, and (3) generating the input and restart files needed to run the general purpose CFD solver NPARC. ICEG2D can be executed in batch mode using a script file or in an interactive mode by entering directives from a command line. This report summarizes activities completed in the first year of a three-year research and development program to address issues related to CFD simulations for aircraft components with ice accretion. Specifically, this document describes the technology employed in the software, the installation procedure, and a description of the operation of the software package. Validation of the geometry and grid generation modules of ICEG2D is also discussed.

ConcreteWorks v3 training/user manual (P1) : ConcreteWorks software (P2).

DOT National Transportation Integrated Search

2017-04-01

ConcreteWorks is designed to be a user-friendly software package that can help concrete : professionals optimize concrete mixture proportioning, perform a concrete thermal analysis, and : increase the chloride diffusion service life. The software pac...

Leadless Chip Carrier Packaging and CAD/CAM-Supported Wire Wrap Interconnect Technology for Subnanosecond ECL.

DTIC Science & Technology

1981-11-01

Showing Wire . 99 Impregnanted Silicone Rubber Contacts, Chip Carrier, ard Lid 35. Technit Connector For 68-Pad JEDEC Type A Leadless . . 100 Chip Carrier...Points of Various . . . . 124 Solders 4. Composition of Alloys Employed in Dual-In-Line . . . . 128 Package Pins and Plating by Mass Spectrographic...swings, and subnanosecond gate delays and risetimes. Presently, emitter coupled logic (ECL) and current mode logic (CML), both fabricated with silicon tech

The effect of gravity modulation on thermosolutal convection in an infinite layer of fluid

NASA Astrophysics Data System (ADS)

Saunders, B. V.; Murray, B. T.; McFadden, G. B.; Coriell, S. R.; Wheeler, A. A.

1992-06-01

The effect of time-periodic vertical gravity modulation on the onset of thermosolutal convection in an infinite horizontal layer with stress-free boundaries is investigated using Floquet theory for the linear stability analysis. Situations for which the fluid layer is stably stratified in either the fingering or diffusive regimes of double-diffusive convection are considered. Results are presented both with and without steady background acceleration. Modulation may stabilize an unstable base solution or destabilize a stable base solution. In addition to synchronous and subharmonic response to the modulation frequency, instability in the double diffusive system can occur via a complex conjugate mode. In the diffusive regime, where oscillatory onset occurs in the unmodulated system, regions of resonant instability occur and exhibit strong coupling with the unmodulated oscillatory frequency. The response to modulation of the fundamental instability of the unmodulated system is described both analytically and numerically; in the double-diffusive system this mode persists under subcritical conditions as a high-frequency lobe.

The effect of gravity modulation on thermosolutal convection in an infinite layer of fluid

NASA Technical Reports Server (NTRS)

Saunders, B. V.; Murray, B. T.; Mcfadden, G. B.; Coriell, S. R.; Wheeler, A. A.

1992-01-01

The effect of time-periodic vertical gravity modulation on the onset of thermosolutal convection in an infinite horizontal layer with stress-free boundaries is investigated using Floquet theory for the linear stability analysis. Situations for which the fluid layer is stably stratified in either the fingering or diffusive regimes of double-diffusive convection are considered. Results are presented both with and without steady background acceleration. Modulation may stabilize an unstable base solution or destabilize a stable base solution. In addition to synchronous and subharmonic response to the modulation frequency, instability in the double diffusive system can occur via a complex conjugate mode. In the diffusive regime, where oscillatory onset occurs in the unmodulated system, regions of resonant instability occur and exhibit strong coupling with the unmodulated oscillatory frequency. The response to modulation of the fundamental instability of the unmodulated system is described both analytically and numerically; in the double-diffusive system this mode persists under subcritical conditions as a high-frequency lobe.

Ultraviolet spectroscopy of meteoric debris of comets

NASA Technical Reports Server (NTRS)

Wdowiak, T. J.; Kubinec, W. R.; Nuth, J. A.

1986-01-01

It is proposed to carry out slitless spectroscopy at ultraviolet wavelengths from orbit of meteoric debris associated with comets. The Eta Aquarid and Orionid/Halley and the Perseid/1962 862 Swift-Tuttle showers would be principal targets. Low light level, ultraviolet video technique will be used during night side of the orbit in a wide field, earthward viewing mode. Data will be stored in compact video cassette recorders. The experiment may be configured as a GAS package or in the HITCHHIKER mode. The latter would allow flexible pointing capability beyond that offered by shuttle orientation of the GAS package, and doubling of the data record. The 1100 to 3200 A spectral region should show emissions of atomic, ionic, and molecular species of interest on cometary and solar system studies.

Ultraviolet spectroscopy of meteoric debris: In situ calibration experiments from Earth orbit

NASA Technical Reports Server (NTRS)

Nuth, J. A., III; Wdowiak, T. J.; Kubinec, W. R.

1986-01-01

It is proposed to carry out slitless spectroscopy at ultraviolet wavelengths from orbit of meteoric debris associated with comets. The Eta Aquarid, Orionid/Halley, and the Persied/1962 862 Swift-Tuttle showers would be principal targets. Low light level, ultraviolet video technique will be used during night side of the orbit in a wide field, earthward viewing mode. Data will be stored in compact video cassette recorders. The experiment may be configured as a GAS package or in the HITCHHIKER mode. The latter would allow flexible pointing capability beyond that offered by shuttle orientation of the GAS package, and doubling of the data record. The 1100 to 3200 A spectral region should show emissions of atomic, ionic, and molecular species of interest on cometary and solar system studies.

Ultraviolet spectroscopy of meteoric debris: In situ calibration experiments from earth orbit

NASA Technical Reports Server (NTRS)

Nuth, Joseph A.; Wdowiak, Thomas J.; Kubinec, William R.

1987-01-01

It is proposed to carry out slitless spectroscopy at ultraviolet wavelengths from orbit of meteoric debris associated with comets. The Eta Aquarid, Orionid/Halley, and the Persied/1962 862 Swift-Tuttle showers would be principal targets. Low light level, ultraviolet video technique will be used during the night side of the orbit in a wide field, earthward viewing mode. Data will be stored in compact video cassette recorders. The experiment may be configured as a GAS package or in the HITCHHIKER mode. The latter would allow flexible pointing capability beyond that offered by shuttle orientation of the GAS package, and doubling of the data record. The 1100 to 3200 A spectral region should show emissions of atomic, ionic, and molecular species of interest on cometary and solar system studies.

Python-based geometry preparation and simulation visualization toolkits for STEPS

PubMed Central

Chen, Weiliang; De Schutter, Erik

2014-01-01

STEPS is a stochastic reaction-diffusion simulation engine that implements a spatial extension of Gillespie's Stochastic Simulation Algorithm (SSA) in complex tetrahedral geometries. An extensive Python-based interface is provided to STEPS so that it can interact with the large number of scientific packages in Python. However, a gap existed between the interfaces of these packages and the STEPS user interface, where supporting toolkits could reduce the amount of scripting required for research projects. This paper introduces two new supporting toolkits that support geometry preparation and visualization for STEPS simulations. PMID:24782754

IN-PACKAGE CHEMISTRY ABSTRACTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

E. Thomas

2005-07-14

This report was developed in accordance with the requirements in ''Technical Work Plan for Postclosure Waste Form Modeling'' (BSC 2005 [DIRS 173246]). The purpose of the in-package chemistry model is to predict the bulk chemistry inside of a breached waste package and to provide simplified expressions of that chemistry as a function of time after breach to Total Systems Performance Assessment for the License Application (TSPA-LA). The scope of this report is to describe the development and validation of the in-package chemistry model. The in-package model is a combination of two models, a batch reactor model, which uses the EQ3/6more » geochemistry-modeling tool, and a surface complexation model, which is applied to the results of the batch reactor model. The batch reactor model considers chemical interactions of water with the waste package materials, and the waste form for commercial spent nuclear fuel (CSNF) waste packages and codisposed (CDSP) waste packages containing high-level waste glass (HLWG) and DOE spent fuel. The surface complexation model includes the impact of fluid-surface interactions (i.e., surface complexation) on the resulting fluid composition. The model examines two types of water influx: (1) the condensation of water vapor diffusing into the waste package, and (2) seepage water entering the waste package as a liquid from the drift. (1) Vapor-Influx Case: The condensation of vapor onto the waste package internals is simulated as pure H{sub 2}O and enters at a rate determined by the water vapor pressure for representative temperature and relative humidity conditions. (2) Liquid-Influx Case: The water entering a waste package from the drift is simulated as typical groundwater and enters at a rate determined by the amount of seepage available to flow through openings in a breached waste package.« less

Comparison of the removal of hydrophobic trace organic contaminants by forward osmosis and reverse osmosis.

PubMed

Xie, Ming; Nghiem, Long D; Price, William E; Elimelech, Menachem

2012-05-15

We compared the rejection behaviours of three hydrophobic trace organic contaminants, bisphenol A, triclosan and diclofenac, in forward osmosis (FO) and reverse osmosis (RO). Using erythritol, xylose and glucose as inert reference organic solutes and the membrane pore transport model, the mean effective pore size of a commercial cellulose-based FO membrane was estimated to be 0.74 nm. When NaCl was used as the draw solute, at the same water permeate flux of 5.4 L/m(2) h (or 1.5 μm/s), the adsorption of all three compounds to the membrane in the FO mode was consistently lower than that in the RO mode. Rejection of bisphenol A and diclofenac were higher in the FO mode compared to that in the RO mode. Because the molecular width of triclosan was larger than the estimated mean effective membrane pore size, triclosan was completely rejected by the membrane and negligent difference between the FO and RO modes could be observed. The difference in the separation behaviour of these hydrophobic trace organics in the FO (using NaCl the draw solute) and RO modes could be explained by the phenomenon of retarded forward diffusion of solutes. The reverse salt flux of NaCl hinders the pore diffusion and subsequent adsorption of the trace organic compounds within the membrane. The retarded forward diffusion effect was not observed when MgSO(4) and glucose were used as the draw solutes. The reverse flux of both MgSO(4) and glucose was negligible and thus both adsorption and rejection of BPA in the FO mode were identical to those in the RO mode. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Diffusive Tidal Evolution for Migrating Hot Jupiters

NASA Astrophysics Data System (ADS)

Wu, Yanqin

2018-03-01

I consider a Jovian planet on a highly eccentric orbit around its host star, a situation produced by secular interactions with its planetary or stellar companions. The tidal interactions at every periastron passage exchange energy between the orbit and the planet’s degree-2 fundamental-mode. Starting from zero energy, the f-mode can diffusively grow to large amplitudes if its one-kick energy gain is ≥10‑5 of the orbital energy. This requires a pericenter distance of ≤4 tidal radii (or 1.6 Roche radii). If the f-mode has a non-negligible initial energy, diffusive evolution can occur at a lower threshold. The first effect can stall the secular migration as the f-mode can absorb orbital energy and decouple the planet from its secular perturbers, parking all migrating jupiters safely outside the zone of tidal disruption. The second effect leads to rapid orbit circularization as it allows an excited f-mode to continuously absorb orbital energy as the orbit eccentricity decreases. So without any explicit dissipation, other than the fact that the f-mode will damp nonlinearly when its amplitude reaches unity, the planet can be transported from a few au to ∼0.2 au in ∼104 years. Such a rapid circularization is equivalent to a dissipation factor Q ∼ 1, and it explains the observed deficit of super-eccentric Jovian planets. Lastly, the repeated f-mode breaking likely deposits energy and angular momentum in the outer envelope and avoids thermally ablating the planet. Overall, this work boosts the case for hot Jupiter formation through high-eccentricity secular migration.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zaveri, Rahul A.; Shilling, John E.; Zelenyuk, Alla

Low bulk diffusivity inside viscous semisolid atmospheric secondary organic aerosol (SOA) can prolong equilibration time scale, but its broader impacts on aerosol growth and size distribution dynamics are poorly understood. In this article, we present quantitative insights into the effects of bulk diffusivity on the growth and evaporation kinetics of SOA formed under dry conditions from photooxidation of isoprene in the presence of a bimodal aerosol consisting of Aitken (ammonium sulfate) and accumulation (isoprene or α-pinene SOA) mode particles. Aerosol composition measurements and evaporation kinetics indicate that isoprene SOA is composed of several semivolatile organic compounds (SVOCs), with some reversiblymore » reacting to form oligomers. Model analysis shows that liquid-like bulk diffusivities can be used to fit the observed evaporation kinetics of accumulation mode particles but fail to explain the growth kinetics of bimodal aerosol by significantly under-predicting the evolution of the Aitken mode. In contrast, the semisolid scenario successfully reproduces both evaporation and growth kinetics, with the interpretation that hindered partitioning of SVOCs into large viscous particles effectively promotes the growth of smaller particles that have shorter diffusion time scales. This effect has important implications for the growth of atmospheric ultrafine particles to climatically active sizes.« less

Growth Kinetics and Size Distribution Dynamics of Viscous Secondary Organic Aerosol

DOE PAGES

Zaveri, Rahul A.; Shilling, John E.; Zelenyuk, Alla; ...

2017-12-15

Low bulk diffusivity inside viscous semisolid atmospheric secondary organic aerosol (SOA) can prolong equilibration time scale, but its broader impacts on aerosol growth and size distribution dynamics are poorly understood. In this article, we present quantitative insights into the effects of bulk diffusivity on the growth and evaporation kinetics of SOA formed under dry conditions from photooxidation of isoprene in the presence of a bimodal aerosol consisting of Aitken (ammonium sulfate) and accumulation (isoprene or α-pinene SOA) mode particles. Aerosol composition measurements and evaporation kinetics indicate that isoprene SOA is composed of several semivolatile organic compounds (SVOCs), with some reversiblymore » reacting to form oligomers. Model analysis shows that liquid-like bulk diffusivities can be used to fit the observed evaporation kinetics of accumulation mode particles but fail to explain the growth kinetics of bimodal aerosol by significantly under-predicting the evolution of the Aitken mode. In contrast, the semisolid scenario successfully reproduces both evaporation and growth kinetics, with the interpretation that hindered partitioning of SVOCs into large viscous particles effectively promotes the growth of smaller particles that have shorter diffusion time scales. This effect has important implications for the growth of atmospheric ultrafine particles to climatically active sizes.« less

Growth Kinetics and Size Distribution Dynamics of Viscous Secondary Organic Aerosol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zaveri, Rahul A.; Shilling, John E.; Zelenyuk, Alla

Low bulk diffusivity inside viscous semisolid atmospheric secondary organic aerosol (SOA) can prolong equilibration time scale, but its broader impacts on aerosol growth and size distribution dynamics are poorly understood. In this article, we present quantitative insights into the effects of bulk diffusivity on the growth and evaporation kinetics of SOA formed under dry conditions from photooxidation of isoprene in the presence of a bimodal aerosol consisting of Aitken (ammonium sulfate) and accumulation (isoprene or α-pinene SOA) mode particles. Aerosol composition measurements and evaporation kinetics indicate that isoprene SOA is composed of several semivolatile organic compounds (SVOCs), with some reversiblymore » reacting to form oligomers. Model analysis shows that liquid-like bulk diffusivities can be used to fit the observed evaporation kinetics of accumulation mode particles but fail to explain the growth kinetics of bimodal aerosol by significantly under-predicting the evolution of the Aitken mode. In contrast, the semisolid scenario successfully reproduces both evaporation and growth kinetics, with the interpretation that hindered partitioning of SVOCs into large viscous particles effectively promotes the growth of smaller particles that have shorter diffusion time scales. This effect has important implications for the growth of atmospheric ultrafine particles to climatically active sizes.« less

Theoretical and Experimental Beam Plasma Physics (TEBPP)

NASA Technical Reports Server (NTRS)

Roberts, W. T.

1985-01-01

The theoretical and experimental beam plasma physics (TEBPP) consists of a package of five instruments to measure electric and magnetic fields, plasma density and temperature, neutral density, photometric emissions, and energetic particle spectra during firings of the particle injector (SEPAC) electron beam. The package is deployed on a maneuverable boom (or RMS) and is used to measure beam characteristics and induced perturbations in the near field ( 10 m) and mid field (10 m to 100 m) along the electron beam. The TEBPP package will be designed to investigate induced oscillations and induced electromagnetic mode waves, neutral and ion density and temperature effects, and beam characteristics as a function of axial distance.

Theoretical and Experimental Beam Plasma Physics (TEBPP)

NASA Technical Reports Server (NTRS)

Roberts, B.

1986-01-01

The theoretical and experimental beam plasma physics (TEBPP) consists of a package of five instruments to measure electric and magnetic fields, plasma density and temperature, neutral density, photometric emissions, and energetic particle spectra during firings of the particle injector (SEPAC) electron beam. The package is developed on a maneuverable boom (or RMS) and is used to measure beam characteristics and induced perturbations field ( 10 m) and mid field ( 10 m to 100 m) along the electron beam. The TEBPP package will be designed to investigate induced oscillations and induced electromagnetic mode waves, neutral and ion density and temperature effects, and beam characteristics as a function of axial distance.

Characterization of the diffusion of epidermal growth factor receptor clusters by single particle tracking.

PubMed

Boggara, Mohan; Athmakuri, Krishna; Srivastava, Sunit; Cole, Richard; Kane, Ravi S

2013-02-01

A number of studies have shown that receptors of the epidermal growth factor receptor family (ErbBs) exist as higher-order oligomers (clusters) in cell membranes in addition to their monomeric and dimeric forms. Characterizing the lateral diffusion of such clusters may provide insights into their dynamics and help elucidate their functional relevance. To that end, we used single particle tracking to study the diffusion of clusters of the epidermal growth factor (EGF) receptor (EGFR; ErbB1) containing bound fluorescently-labeled ligand, EGF. EGFR clusters had a median diffusivity of 6.8×10(-11)cm(2)/s and were found to exhibit different modes of transport (immobile, simple, confined, and directed) similar to that previously reported for single EGFR molecules. Disruption of actin filaments increased the median diffusivity of EGFR clusters to 10.3×10(-11)cm(2)/s, while preserving the different modes of diffusion. Interestingly, disruption of microtubules rendered EGFR clusters nearly immobile. Our data suggests that microtubules may play an important role in the diffusion of EGFR clusters either directly or perhaps indirectly via other mechanisms. To our knowledge, this is the first report probing the effect of the cytoskeleton on the diffusion of EGFR clusters in the membranes of live cells. Copyright © 2012 Elsevier B.V. All rights reserved.

Development of an active food packaging system with antioxidant properties based on green tea extract.

PubMed

Carrizo, Daniel; Gullo, Giuseppe; Bosetti, Osvaldo; Nerín, Cristina

2014-01-01

A formula including green tea extract (GTE) was developed as an active food packaging material. This formula was moulded to obtain an independent component/device with antioxidant properties that could be easily coupled to industrial degassing valves for food packaging in special cases. GTE components (i.e., gallic acid, catechins and caffeine) were identified and quantified by HPLC-UV and UPLC-MS and migration/diffusion studies were carried out. Antioxidant properties of the formula alone and formula-valve were measured with static and dynamic methods. The results showed that the antioxidant capacity (scavenging of free radicals) of the new GTE formula was 40% higher than the non-active system (blank). This antioxidant activity increased in parallel with the GTE concentration. The functional properties of the industrial target valve (e.g., flexibility) were studied for different mixtures of GTE, and good results were found with 17% (w/w) of GTE. This new active formula can be an important addition for active packaging applications in the food packaging industry, with oxidative species-scavenging capacity, thus improving the safety and quality for the consumer and extending the shelf-life of the packaged food.

Modes of Diffusion of Cholera Toxin Bound to GM1 on Live Cell Membrane by Image Mean Square Displacement Analysis

PubMed Central

Moens, Pierre D.J.; Digman, Michelle A.; Gratton, Enrico

2015-01-01

The image-mean square displacement technique applies the calculation of the mean square displacement commonly used in single-molecule tracking to images without resolving single particles. The image-mean square displacement plot obtained is similar to the mean square displacement plot obtained using the single-particle tracking technique. This plot is then used to reconstruct the protein diffusion law and to identify whether the labeled molecules are undergoing pure isotropic, restricted, corralled, transiently confined, or directed diffusion. In our study total internal reflection fluorescence microscopy images were taken of Cholera toxin subunit B (CtxB) membrane-labeled NIH 3T3 mouse fibroblasts and MDA 231 MB cells. We found a population of CTxB undergoing purely isotropic diffusion and one displaying restricted diffusion with corral sizes ranging from 150 to ∼1800 nm. We show that the diffusion rate of CTxB bound to GM1 is independent of the size of the confinement, suggesting that the mechanism of confinement is different from the mechanism controlling the diffusion rate of CtxB. We highlight the potential effect of continuous illumination on the diffusion mode of CTxB. We also show that aggregation of CTxB/GM1 in large complexes occurs and that these aggregates tend to have slower diffusion rates. PMID:25809257

Modes of diffusion of cholera toxin bound to GM1 on live cell membrane by image mean square displacement analysis.

PubMed

Moens, Pierre D J; Digman, Michelle A; Gratton, Enrico

2015-03-24

The image-mean square displacement technique applies the calculation of the mean square displacement commonly used in single-molecule tracking to images without resolving single particles. The image-mean square displacement plot obtained is similar to the mean square displacement plot obtained using the single-particle tracking technique. This plot is then used to reconstruct the protein diffusion law and to identify whether the labeled molecules are undergoing pure isotropic, restricted, corralled, transiently confined, or directed diffusion. In our study total internal reflection fluorescence microscopy images were taken of Cholera toxin subunit B (CtxB) membrane-labeled NIH 3T3 mouse fibroblasts and MDA 231 MB cells. We found a population of CTxB undergoing purely isotropic diffusion and one displaying restricted diffusion with corral sizes ranging from 150 to ∼1800 nm. We show that the diffusion rate of CTxB bound to GM1 is independent of the size of the confinement, suggesting that the mechanism of confinement is different from the mechanism controlling the diffusion rate of CtxB. We highlight the potential effect of continuous illumination on the diffusion mode of CTxB. We also show that aggregation of CTxB/GM1 in large complexes occurs and that these aggregates tend to have slower diffusion rates. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Natural biopolimers in organic food packaging

NASA Astrophysics Data System (ADS)

Wieczynska, Justyna; Cavoski, Ivana; Chami, Ziad Al; Mondelli, Donato; Di Donato, Paola; Di Terlizzi, Biagio

2014-05-01

Concerns on environmental and waste problems caused by use of non-biodegradable and non-renewable based plastic packaging have caused an increase interest in developing biodegradable packaging using renewable natural biopolymers. Recently, different types of biopolymers like starch, cellulose, chitosan, casein, whey protein, collagen, egg white, soybean protein, corn zein, gelatin and wheat gluten have attracted considerable attention as potential food packaging materials. Recyclable or biodegradable packaging material in organic processing standards is preferable where possible but specific principles of packaging are not precisely defined and standards have to be assessed. There is evidence that consumers of organic products have specific expectations not only with respect to quality characteristics of processed food but also in social and environmental aspects of food production. Growing consumer sophistication is leading to a proliferation in food eco-label like carbon footprint. Biopolymers based packaging for organic products can help to create a green industry. Moreover, biopolymers can be appropriate materials for the development of an active surfaces designed to deliver incorporated natural antimicrobials into environment surrounding packaged food. Active packaging is an innovative mode of packaging in which the product and the environment interact to prolong shelf life or enhance safety or sensory properties, while maintaining the quality of the product. The work will discuss the various techniques that have been used for development of an active antimicrobial biodegradable packaging materials focusing on a recent findings in research studies. With the current focus on exploring a new generation of biopolymer-based food packaging materials with possible applications in organic food packaging. Keywords: organic food, active packaging, biopolymers , green technology

Simulation tools for particle-based reaction-diffusion dynamics in continuous space

PubMed Central

2014-01-01

Particle-based reaction-diffusion algorithms facilitate the modeling of the diffusional motion of individual molecules and the reactions between them in cellular environments. A physically realistic model, depending on the system at hand and the questions asked, would require different levels of modeling detail such as particle diffusion, geometrical confinement, particle volume exclusion or particle-particle interaction potentials. Higher levels of detail usually correspond to increased number of parameters and higher computational cost. Certain systems however, require these investments to be modeled adequately. Here we present a review on the current field of particle-based reaction-diffusion software packages operating on continuous space. Four nested levels of modeling detail are identified that capture incrementing amount of detail. Their applicability to different biological questions is discussed, arching from straight diffusion simulations to sophisticated and expensive models that bridge towards coarse grained molecular dynamics. PMID:25737778

Mode-converted diffuse ultrasonic backscatter.

PubMed

Hu, Ping; Kube, Christopher M; Koester, Lucas W; Turner, Joseph A

2013-08-01

Diffuse ultrasonic backscatter describes the scattering of elastic waves from interfaces within heterogeneous materials. Previously, theoretical models have been developed for the diffuse backscatter of longitudinal-to-longitudinal (L-L) wave scattering within polycrystalline materials. Following a similar formalism, a mode-conversion scattering model is presented here to quantify the component of an incident longitudinal wave that scatters and is converted to a transverse (shear) wave within a polycrystalline sample. The model is then used to fit experimental measurements associated with a pitch-catch transducer configuration performed using a sample of 1040 steel. From these measurements, an average material correlation length is determined. This value is found to be in agreement with results from L-L scattering measurements and is on the order of the grain size as determined from optical micrographs. Mode-converted ultrasonic backscatter is influenced much less by the front-wall reflection than an L-L measurement and it provides additional microstructural information that is not accessible in any other manner.

Dynamical transition for a particle in a squared Gaussian potential

NASA Astrophysics Data System (ADS)

Touya, C.; Dean, D. S.

2007-02-01

We study the problem of a Brownian particle diffusing in finite dimensions in a potential given by ψ = phi2/2 where phi is Gaussian random field. Exact results for the diffusion constant in the high temperature phase are given in one and two dimensions and it is shown to vanish in a power-law fashion at the dynamical transition temperature. Our results are confronted with numerical simulations where the Gaussian field is constructed, in a standard way, as a sum over random Fourier modes. We show that when the number of Fourier modes is finite the low temperature diffusion constant becomes non-zero and has an Arrhenius form. Thus we have a simple model with a fully understood finite size scaling theory for the dynamical transition. In addition we analyse the nature of the anomalous diffusion in the low temperature regime and show that the anomalous exponent agrees with that predicted by a trap model.

Conserved linear dynamics of single-molecule Brownian motion.

PubMed

Serag, Maged F; Habuchi, Satoshi

2017-06-06

Macromolecular diffusion in homogeneous fluid at length scales greater than the size of the molecule is regarded as a random process. The mean-squared displacement (MSD) of molecules in this regime increases linearly with time. Here we show that non-random motion of DNA molecules in this regime that is undetectable by the MSD analysis can be quantified by characterizing the molecular motion relative to a latticed frame of reference. Our lattice occupancy analysis reveals unexpected sub-modes of motion of DNA that deviate from expected random motion in the linear, diffusive regime. We demonstrate that a subtle interplay between these sub-modes causes the overall diffusive motion of DNA to appear to conform to the linear regime. Our results show that apparently random motion of macromolecules could be governed by non-random dynamics that are detectable only by their relative motion. Our analytical approach should advance broad understanding of diffusion processes of fundamental relevance.

Conserved linear dynamics of single-molecule Brownian motion

PubMed Central

Serag, Maged F.; Habuchi, Satoshi

2017-01-01

Macromolecular diffusion in homogeneous fluid at length scales greater than the size of the molecule is regarded as a random process. The mean-squared displacement (MSD) of molecules in this regime increases linearly with time. Here we show that non-random motion of DNA molecules in this regime that is undetectable by the MSD analysis can be quantified by characterizing the molecular motion relative to a latticed frame of reference. Our lattice occupancy analysis reveals unexpected sub-modes of motion of DNA that deviate from expected random motion in the linear, diffusive regime. We demonstrate that a subtle interplay between these sub-modes causes the overall diffusive motion of DNA to appear to conform to the linear regime. Our results show that apparently random motion of macromolecules could be governed by non-random dynamics that are detectable only by their relative motion. Our analytical approach should advance broad understanding of diffusion processes of fundamental relevance. PMID:28585925

Conserved linear dynamics of single-molecule Brownian motion

NASA Astrophysics Data System (ADS)

Serag, Maged F.; Habuchi, Satoshi

2017-06-01

Macromolecular diffusion in homogeneous fluid at length scales greater than the size of the molecule is regarded as a random process. The mean-squared displacement (MSD) of molecules in this regime increases linearly with time. Here we show that non-random motion of DNA molecules in this regime that is undetectable by the MSD analysis can be quantified by characterizing the molecular motion relative to a latticed frame of reference. Our lattice occupancy analysis reveals unexpected sub-modes of motion of DNA that deviate from expected random motion in the linear, diffusive regime. We demonstrate that a subtle interplay between these sub-modes causes the overall diffusive motion of DNA to appear to conform to the linear regime. Our results show that apparently random motion of macromolecules could be governed by non-random dynamics that are detectable only by their relative motion. Our analytical approach should advance broad understanding of diffusion processes of fundamental relevance.

Instantaneous Normal Modes and the Protein Glass Transition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schulz, Roland; Krishnan, Marimuthu; Daidone, Isabella

2009-01-01

In the instantaneous normal mode method, normal mode analysis is performed at instantaneous configurations of a condensed-phase system, leading to modes with negative eigenvalues. These negative modes provide a means of characterizing local anharmonicities of the potential energy surface. Here, we apply instantaneous normal mode to analyze temperature-dependent diffusive dynamics in molecular dynamics simulations of a small protein (a scorpion toxin). Those characteristics of the negative modes are determined that correlate with the dynamical (or glass) transition behavior of the protein, as manifested as an increase in the gradient with T of the average atomic mean-square displacement at ~ 220more » K. The number of negative eigenvalues shows no transition with temperature. Further, although filtering the negative modes to retain only those with eigenvectors corresponding to double-well potentials does reveal a transition in the hydration water, again, no transition in the protein is seen. However, additional filtering of the protein double-well modes, so as to retain only those that, on energy minimization, escape to different regions of configurational space, finally leads to clear protein dynamical transition behavior. Partial minimization of instantaneous configurations is also found to remove nondiffusive imaginary modes. In summary, examination of the form of negative instantaneous normal modes is shown to furnish a physical picture of local diffusive dynamics accompanying the protein glass transition.« less

Instantaneous Normal Modes and the Protein Glass Transition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schultz, Roland; Krishnan, Marimuthu; Daidone, Isabella

2009-01-01

In the instantaneous normal mode method, normal mode analysis is performed at instantaneous configurations of a condensed-phase system, leading to modes with negative eigenvalues. These negative modes provide a means of characterizing local anharmonicities of the potential energy surface. Here, we apply instantaneous normal mode to analyze temperature-dependent diffusive dynamics in molecular dynamics simulations of a small protein (a scorpion toxin). Those characteristics of the negative modes are determined that correlate with the dynamical (or glass) transition behavior of the protein, as manifested as an increase in the gradient with T of the average atomic mean-square displacement at 220 K.more » The number of negative eigenvalues shows no transition with temperature. Further, although filtering the negative modes to retain only those with eigenvectors corresponding to double-well potentials does reveal a transition in the hydration water, again, no transition in the protein is seen. However, additional filtering of the protein double-well modes, so as to retain only those that, on energy minimization, escape to different regions of configurational space, finally leads to clear protein dynamical transition behavior. Partial minimization of instantaneous configurations is also found to remove nondiffusive imaginary modes. In summary, examination of the form of negative instantaneous normal modes is shown to furnish a physical picture of local diffusive dynamics accompanying the protein glass transition.« less

10 CFR 431.86 - Uniform test method for the measurement of energy efficiency of commercial packaged boilers.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Boiler That is Capable of Supplying Either Steam or Hot Water—(A) Testing. For purposes of EPCA, before... supplying either steam or hot water either by testing the boiler in the steam mode or by testing it in both... supplying either steam or hot water either by testing the boiler for both efficiencies in steam mode, or by...

Containing diffusion: the tobacco industry's multipronged trade strategy to block tobacco standardised packaging.

PubMed

Crosbie, Eric; Eckford, Robert; Bialous, Stella

2018-04-21

To analyse the tobacco industry's strategy of using trade and investment agreements to prevent the global diffusion of standardised packaging (SP) of tobacco products. Review of tobacco industry documents, relevant government documents and media items. The data were triangulated and thematically analysed. Internal tobacco industry documents reveal that during the early 1990s, tobacco companies developed a multipronged trade strategy to prevent the global diffusion of progressive tobacco packaging and labelling proposals, including SP. This strategy consisted of (1) framing the health issue in terms of trade and investment, (2) detailing alleged legal violations concerning trade barriers, intellectual property and investment rights, (3) threatening legal suits and reputational damage, and (4) garnering third-party support. These efforts helped delay SP until 2010 when Australia became the first country to reintroduce SP proposals, followed by governments in the UK and New Zealand in 2012, Ireland in 2013 and France in 2014. Review of government documents and media sources in each of the five countries indicate the industry continues to employ this multipronged strategy throughout the SP policy's progression. Although this strategy is tailored towards each domestic context, the overall tobacco industry's trade strategy remains consistently focused on shifting the attention away from public health and towards the realm of trade and investment with more corporate-friendly allies. Governments seeking to implement SP need to be prepared to resist and counter the industry's multipronged trade strategy by avoiding trade diversions, exposing false industry legal and reputational claims, and monitoring third-party support. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Local Electron Density Measurements from Sounding Experiments by RPI on IMAGE

NASA Astrophysics Data System (ADS)

Proddaturi, R.; Sonwalkar, V. S.; Li, J.; Venkatasubramanian, A.; Carpenter, D.; Benson, R.; Reinisch, B.

2004-12-01

RPI sounding experiments lead to a variety of echoes, propagating in various plasma wave modes, and local resonances. Characteristic frequencies of these echoes and resonances can be used to determine the local plasma frequency and thus the local electron density. In this work we have estimated plasma frequency by two methods: (1) using upper hybrid frequency measured from the diffuse Z mode echo upper cutoff and gyro-frequency measured from a gap in the diffuse Z mode echo or from resonances at the multiples of gyrofrequency, (2) upper hybrid frequency from the diffuse Z mode and the free space cutoff frequency fR=0 from the R-X mode echo. Broadband diffuse Z-mode echoes occur 90% of the time at high latitudes (λ m>45oS) near perigee in the southern hemisphere, where fpe << fce. In the middle and low latitudes (λ m<45oS), where fpe >> fce, Z-mode echoes are narrowband and are often accompanied by Qn and Dn resonances. The free space R-X mode echoes are commonly observed at both high and low latitudes. Multiples of gyrofrequency are typically observed at mid- to low-latitude in both the northern and southern hemisphere and at high latitude in the northern hemisphere. RPI plasmagrams were analyzed for three orbits (apogee to apogee) in the year 2002. These three orbits were selected because suitable sounding programs, those that can cover Z mode bandwidth over a wide range of latitude, were used, and also because a large number of diffuse Z mode echoes were actually observed. Electron densities as low as 10 el/cc and as high as 9000 el/cc were measured. The transmission frequencies place a limitation on the upper and lower limits of measurable fpe. The measured fpe values showed good agreement with measurements made from the thermal noise but showed large deviations when compared with model fpe values. For a particular orbit on August 26, 2002, Ne measured was as low as ˜20 el/cc at higher altitudes outside the plasmasphere (λ m > 60oN, altitude >7000 km, MLT=1.89) and increased as IMAGE approached the plasmasphere. A maximum of ˜8900 el/cc was measured well within the plasmasphere (L = 1.56, λ m = 17oN, altitude =2700 km, MLT = 2.44). As the satellite left the plasmasphere, measured electron density decreased to a minimum of about 55 el/cc near the auroral zone (L = 6.83, λ m = 57oS, altitude = 6277 km, MLT=13.66) and then started to rise again. A sharper change in Ne was seen at both the inbound and outbound crossings of the plasmapause. As the satellite again entered the plasmasphere (L = 3.94, λ m = 21oS, altitude = 15500 km, MLT = 14.34) at a higher altitude the maximum value of Ne measured was lower ( ˜520 el/cc) as expected. Our results demonstrate that magnetospheric sounding experiments employing Z mode and free space modes provide a powerful means of making local plasma density measurements.

Modified atmosphere packaging of fruits and vegetables.

PubMed

Kader, A A; Zagory, D; Kerbel, E L

1989-01-01

Modified atmospheres (MA), i.e., elevated concentrations of carbon dioxide and reduced levels of oxygen and ethylene, can be useful supplements to provide optimum temperature and relative humidity in maintaining the quality of fresh fruits and vegetables after harvest. MA benefits include reduced respiration, ethylene production, and sensitivity to ethylene; retarded softening and compositional changes; alleviation of certain physiological disorders; and reduced decay. Subjecting fresh produce to too low an oxygen concentration and/or to too high a carbon dioxide level can result in MA stress, which is manifested by accelerated deterioration. Packaging fresh produce in polymeric films can result in a commodity-generated MA. Atmosphere modification within such packages depends on film permeability, commodity respiration rate and gas diffusion characteristics, and initial free volume and atmospheric composition within the package. Temperature, relative humidity, and air movement around the package can influence the permeability of the film. Temperature also affects the metabolic activity of the commodity and consequently the rate of attaining the desired MA. All these factors must be considered in developing a mathematical model for selecting the most suitable film for each commodity.

Preliminary quantification of the permeability, solubility and diffusion coefficients of major aroma compounds present in herbs through various plastic packaging materials.

PubMed

Leelaphiwat, Pattarin; Auras, Rafael A; Burgess, Gary J; Harte, Janice B; Chonhenchob, Vanee

2018-03-01

Aroma permeation through packaging material is an important factor when designing a package for food products. The masses of aroma compounds permeating through films over time were measured at 25 °C using a quasi-isostatic system. A model was proposed for estimating the permeability coefficients (P) of key aroma compounds present in fresh herbs (i.e. eucalyptol, estragole, linalool and citral) through major plastic films used by the food industry [i.e. low-density polyethylene (LDPE), polypropylene (PP), nylon (Nylon), polyethylene terephthalate (PET), metalised-polyethylene terephthalate (MPET) and poly(lactic acid) (PLA)]. Solubility coefficients (S) were estimated from the amount of aroma compound sorbed in the films. Diffusion coefficients (D) were estimated following from the relation P = D*S. P and D for all four aroma compounds were highest in LDPE, except for eucalyptol, which P was slightly higher in PLA. The solubility coefficients and contact angles were highest in PLA suggesting the highest affinity of PLA to these aroma compounds. The theoretical solubility parameters were correlated with the solubility coefficients for estragole and citral, but not for eucalyptol and linalool. The preliminary P, D and S of eucalyptol, estragole, linalool and citral through LDPE, PP, Nylon, PET, MPET and PLA can be useful in selecting the proper packaging material for preserving these specific aroma compounds in food products and can potentially be used for estimating the shelf life of food products based on aroma loss. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Two species drag/diffusion model for energetic particle driven modes

NASA Astrophysics Data System (ADS)

Aslanyan, V.; Sharapov, S. E.; Spong, D. A.; Porkolab, M.

2017-12-01

A nonlinear bump-on-tail model for the growth and saturation of energetic particle driven plasma waves has been extended to include two populations of fast particles—one dominated by dynamical friction at the resonance and the other by velocity space diffusion. The resulting temporal evolution of the wave amplitude and frequency depends on the relative weight of the two populations. The two species model is applied to burning plasma with drag-dominated alpha particles and diffusion-dominated ICRH accelerated minority ions, showing the stabilization of bursting modes. The model also suggests an explanation for the recent observations on the TJ-II stellarator, where Alfvén Eigenmodes transition between steady state and bursting as the magnetic configuration varied.

The specific diffusion behaviour in paper and migration modelling from recycled board into dry foodstuffs.

PubMed

Hauder, J; Benz, H; Rüter, M; Piringer, O-G

2013-01-01

Recycled board plays an important role in food packaging, but the great variety of organic impurities must be considered as potential food contaminants. The diffusion behaviour of the impurities is significantly different from that in plastic materials. The two-layer concept for paper and board introduced recently is now treated in more detail. In the rate-determining surface region the diffusion coefficients of the n-alkanes in the homologous series with 15-35 carbon atoms decrease proportionally as their vapour pressures. This leads to a different equation of the diffusion coefficients in comparison with that for the core layer. Different polarities of the migrants have additional influences on the diffusion due to their interactions with the fibre matrix. A new analytical method for the quantification of aromatic impurities has previously been developed. Based on this method and on the described diffusion behaviour, a migration model for specific and global mass transfer of impurities from recycled board into dry food and food simulants is given.

Generation of Z mode radiation by diffuse auroral electron precipitation

NASA Astrophysics Data System (ADS)

Dusenbery, P. B.; Lyons, L. R.

1985-03-01

The generation of Z mode waves by diffuse auroral electron precipitation is investigated assuming that a loss cone exists in the upgoing portion of the distribution due to electron interactions with the atmosphere. The waves are generated at frequencies above, but very near, the local electron cyclotron frequency omega(e) and at wave normal angles larger than 90 deg. In agreement with Hewitt et al. (1983), the group velocity is directed downward in regions where the ratio of the upper hybrid frequency omega(pe) to Omega(e) is less than 0.5, so that Z mode waves excited above a satellite propagate toward it and away from the upper hybrid resonance. Z mode waves are excited in a frequency band between Omega(e) and about 1.02 Omega(e), and with maximum growth rates of about 0.001 Omega(e). The amplification length is about 100 km, which allows Z mode waves to grow to the intensities observed by high-altitude satellites.

Generation of Z mode radiation by diffuse auroral electron precipitation

NASA Technical Reports Server (NTRS)

Dusenbery, P. B.; Lyons, L. R.

1985-01-01

The generation of Z mode waves by diffuse auroral electron precipitation is investigated assuming that a loss cone exists in the upgoing portion of the distribution due to electron interactions with the atmosphere. The waves are generated at frequencies above, but very near, the local electron cyclotron frequency omega(e) and at wave normal angles larger than 90 deg. In agreement with Hewitt et al. (1983), the group velocity is directed downward in regions where the ratio of the upper hybrid frequency omega(pe) to Omega(e) is less than 0.5, so that Z mode waves excited above a satellite propagate toward it and away from the upper hybrid resonance. Z mode waves are excited in a frequency band between Omega(e) and about 1.02 Omega(e), and with maximum growth rates of about 0.001 Omega(e). The amplification length is about 100 km, which allows Z mode waves to grow to the intensities observed by high-altitude satellites.

A strong diffusive ion mode in dense ionized matter predicted by Langevin dynamics

DOE PAGES

Mabey, P.; Richardson, S.; White, T. G.; ...

2017-01-30

We determined the state and evolution of planets, brown dwarfs and neutron star crusts by the properties of dense and compressed matter. Furthermore, due to the inherent difficulties in modelling strongly coupled plasmas, however, current predictions of transport coefficients differ by orders of magnitude. Collective modes are a prominent feature, whose spectra may serve as an important tool to validate theoretical predictions for dense matter. With recent advances in free electron laser technology, X-rays with small enough bandwidth have become available, allowing the investigation of the low-frequency ion modes in dense matter. Here, we present numerical predictions for these ionmore » modes and demonstrate significant changes to their strength and dispersion if dissipative processes are included by Langevin dynamics. Notably, a strong diffusive mode around zero frequency arises, which is not present, or much weaker, in standard simulations. These results have profound consequences in the interpretation of transport coefficients in dense plasmas.« less

A theory of growing crystalline nanorods - Mode I

NASA Astrophysics Data System (ADS)

Du, Feng; Huang, Hanchen

2018-08-01

Nanorods grow in two possible modes during physical vapor deposition (PVD). In mode I, monolayer surface steps dictate the diameter of nanorods. In mode II, multiple-layer surface steps dictate the diameter, which is the smallest possible under physical vapor deposition [5,10]. This paper reports closed-form theories of terrace lengths and nanorod diameter during the growth in mode I, as a function of deposition conditions. The accompanying lattice kinetic Monte Carlo simulations verify these theories. This study reveals that (1) quasi-steady growth exists for each set of nanorod growth conditions, and (2) the characteristic length scales, including terrace lengths and nanorod diameter at the quasi-steady state, depend on the deposition conditions - deposition rate F, substrate temperature T, and incidence angle θ - only as a function of l2D/tan θ, with l2 D = 2(v2 D/Fcosθ) 1/3 as a diffusion-limited length scale and v2D as the atomic diffusion jump rate over monolayer surface steps.

Transverse mode selection in vertical-cavity surface-emitting lasers via deep impurity-induced disordering

NASA Astrophysics Data System (ADS)

O'Brien, Thomas R.; Kesler, Benjamin; Dallesasse, John M.

2017-02-01

Top emission 850-nm vertical-cavity surface-emitting lasers (VCSELs) demonstrating transverse mode selection via impurity-induced disordering (IID) are presented. The IID apertures are fabricated via closed ampoule zinc diffusion. A simple 1-D plane wave model based on the intermixing of Group III atoms during IID is presented to optimize the mirror loss of higher-order modes as a function of IID strength and depth. In addition, the impact of impurity diffusion into the cap layer of the lasers is shown to improve contact resistance. Further investigation of the mode-dependent characteristics of the device imply an increase in the thermal impedance associated with the fraction of IID contained within the oxide aperture. The optimization of the ratio of the IID aperture to oxide aperture is experimentally determined. Single fundamental mode output of 1.6 mW with 30 dBm side mode suppression ratio is achieved by a 3.0 μm oxide-confined device with an IID aperture of 1.3 μm indicating an optimal IID aperture size of 43% of the oxide aperture.

Estimation of water diffusion coefficient into polycarbonate at different temperatures using numerical simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nasirabadi, P. Shojaee; Jabbari, M.; Hattel, J. H.

2016-06-08

Nowadays, many electronic systems are exposed to harsh conditions of relative humidity and temperature. Mass transport properties of electronic packaging materials are needed in order to investigate the influence of moisture and temperature on reliability of electronic devices. Polycarbonate (PC) is widely used in the electronics industry. Thus, in this work the water diffusion coefficient into PC is investigated. Furthermore, numerical methods used for estimation of the diffusion coefficient and their assumptions are discussed. 1D and 3D numerical solutions are compared and based on this, it is shown how the estimated value can be different depending on the choice ofmore » dimensionality in the model.« less

Diffusion and Leaching Behavior of Radionuclides in Category 3 Waste Encasement Concrete and Soil Fill Material – Summary Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mattigod, Shas V.; Wellman, Dawn M.; Bovaird, Chase C.

2011-08-31

One of the methods being considered for safely disposing of Category 3 low-level radioactive wastes is to encase the waste in concrete. Such concrete encasement would contain and isolate the waste packages from the hydrologic environment and would act as an intrusion barrier. The current plan for waste isolation consists of stacking low-level waste packages on a trench floor, surrounding the stacks with reinforced steel, and encasing these packages in concrete. These concrete-encased waste stacks are expected to vary in size with maximum dimensions of 6.4 m long, 2.7 m wide, and 4 m high. The waste stacks are expectedmore » to have a surrounding minimum thickness of 15 cm of concrete encasement. These concrete-encased waste packages are expected to withstand environmental exposure (solar radiation, temperature variations, and precipitation) until an interim soil cover or permanent closure cover is installed, and to remain largely intact thereafter. Any failure of concrete encasement may result in water intrusion and consequent mobilization of radionuclides from the waste packages. The mobilized radionuclides may escape from the encased concrete by mass flow and/or diffusion and move into the surrounding subsurface environment. Therefore, it is necessary to assess the performance of the concrete encasement structure and the ability of the surrounding soil to retard radionuclide migration. The retardation factors for radionuclides contained in the waste packages can be determined from measurements of diffusion coefficients for these contaminants through concrete and fill material. Some of the mobilization scenarios include (1) potential leaching of waste form before permanent closure cover is installed; (2) after the cover installation, long-term diffusion of radionuclides from concrete waste form into surrounding fill material; (3) diffusion of radionuclides from contaminated soils into adjoining concrete encasement and clean fill material. Additionally, the rate of diffusion of radionuclides may be affected by the formation of structural cracks in concrete, the carbonation of the buried waste form, and any potential effect of metallic iron (in the form of rebars) on the mobility of radionuclides. The radionuclides iodine-129 ({sup 129}I), technetium-99 ({sup 99}Tc), and uranium-238 ({sup 238}U) are identified as long-term dose contributors in Category 3 waste (Mann et al. 2001; Wood et al. 1995). Because of their anionic nature in aqueous solutions, {sup 129}I, {sup 99}Tc, and carbonate-complexed {sup 238}U may readily leach into the subsurface environment (Serne et al. 1989, 1992a, b, 1993, and 1995). The leachability and/or diffusion of radionuclide species must be measured to assess the long-term performance of waste grouts when contacted with vadose-zone pore water or groundwater. Although significant research has been conducted on the design and performance of cementitious waste forms, the current protocol conducted to assess radionuclide stability within these waste forms has been limited to the Toxicity Characteristic Leaching Procedure, Method 1311 Federal Registry (EPA 1992) and ANSI/ANS-16.1 leach test (ANSI 1986). These tests evaluate the performance under water-saturated conditions and do not evaluate the performance of cementitious waste forms within the context of waste repositories which are located within water-deficient vadose zones. Moreover, these tests assess only the diffusion of radionuclides from concrete waste forms and neglect evaluating the mechanisms of retention, stability of the waste form, and formation of secondary phases during weathering, which may serve as long-term secondary hosts for immobilization of radionuclides. The results of recent investigations conducted under arid and semi-arid conditions (Al-Khayat et al. 2002; Garrabrants et al. 2002; Garrabrants and Kosson 2003; Garrabrants et al. 2004; Gervais et al. 2004; Sanchez et al. 2002; Sanchez et al. 2003) provide valuable information suggesting structural and chemical changes to concrete waste forms which may affect contaminant containment and waste form performance. However, continued research is necessitated by the need to understand: the mechanism of contaminant release; the significance of contaminant release pathways; how waste form performance is affected by the full range of environmental conditions within the disposal facility; the process of waste form aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of waste form aging on chemical, physical, and radiological properties, and the associated impact on contaminant release. Recent reviews conducted by the National Academies of Science recognized the efficacy of cementitious materials for waste isolation, but further noted the significant shortcomings in our current understanding and testing protocol for evaluating the performance of various formulations.« less

Active food packaging based on molecularly imprinted polymers: study of the release kinetics of ferulic acid.

PubMed

Otero-Pazos, Pablo; Rodríguez-Bernaldo de Quirós, Ana; Sendón, Raquel; Benito-Peña, Elena; González-Vallejo, Victoria; Moreno-Bondi, M Cruz; Angulo, Immaculada; Paseiro-Losada, Perfecto

2014-11-19

A novel active packaging based on molecularly imprinted polymer (MIP) was developed for the controlled release of ferulic acid. The release kinetics of ferulic acid from the active system to food simulants (10, 20, and 50% ethanol (v/v), 3% acetic acid (w/v), and vegetable oil), substitutes (95% ethanol (v/v) and isooctane), and real food samples at different temperatures were studied. The key parameters of the diffusion process were calculated by using a mathematical modeling based on Fick's second law. The ferulic acid release was affected by the temperature as well as the percentage of ethanol of the simulant. The fastest release occurred in 95% ethanol (v/v) at 20 °C. The diffusion coefficients (D) obtained ranged between 1.8 × 10(-11) and 4.2 × 10(-9) cm(2)/s. A very good correlation between experimental and estimated data was obtained, and consequently the model could be used to predict the release of ferulic acid into food simulants and real food samples.

An electron-beam dose deposition experiment: TIGER 1-D simulation code versus thermoluminescent dosimetry

NASA Astrophysics Data System (ADS)

Murrill, Steven R.; Tipton, Charles W.; Self, Charles T.

1991-03-01

The dose absorbed in an integrated circuit (IC) die exposed to a pulse of low-energy electrons is a strong function of both electron energy and surrounding packaging materials. This report describes an experiment designed to measure how well the Integrated TIGER Series one-dimensional (1-D) electron transport simulation program predicts dose correction factors for a state-of-the-art IC package and package/printed circuit board (PCB) combination. These derived factors are compared with data obtained experimentally using thermoluminescent dosimeters (TLD's) and the FX-45 flash x-ray machine (operated in electron-beam (e-beam) mode). The results of this experiment show that the TIGER 1-D simulation code can be used to accurately predict FX-45 e-beam dose deposition correction factors for reasonably complex IC packaging configurations.

An Integrated Software Package to Enable Predictive Simulation Capabilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Yousu; Fitzhenry, Erin B.; Jin, Shuangshuang

The power grid is increasing in complexity due to the deployment of smart grid technologies. Such technologies vastly increase the size and complexity of power grid systems for simulation and modeling. This increasing complexity necessitates not only the use of high-performance-computing (HPC) techniques, but a smooth, well-integrated interplay between HPC applications. This paper presents a new integrated software package that integrates HPC applications and a web-based visualization tool based on a middleware framework. This framework can support the data communication between different applications. Case studies with a large power system demonstrate the predictive capability brought by the integrated software package,more » as well as the better situational awareness provided by the web-based visualization tool in a live mode. Test results validate the effectiveness and usability of the integrated software package.« less

IPS guidestar selection for stellar mode (ASTRO)

NASA Technical Reports Server (NTRS)

Mullins, Larry; Wooten, Lewis

1988-01-01

This report describes how guide stars are selected for the Optical Sensor Package (OSP) for the Instrument Pointing System (IPS) when it is operating in the stellar mode on the ASTRO missions. It also describes how the objective loads are written and how the various roll angles are related; i.e., the celestial roll or position angle, the objective load roll angles, and the IPS gimbal angles. There is a brief description of how the IPS operates and its various modes of operation; i.e., IDOP, IDIN, and OSPCAL.

Simulation of transverse modes with their intrinsic Landau damping for bunched beams in the presence of space charge

DOE PAGES

Macridin, Alexandru; Burov, Alexey; Stern, Eric; ...

2015-07-22

Transverse dipole modes in bunches with space charge are simulated using the synergia accelerator modeling package and analyzed with dynamic mode decomposition. The properties of the first three space charge modes, including their shape, damping rates, and tune shifts are described over the entire range of space charge strength. As a result, the intrinsic Landau damping predicted and estimated in 2009 by one of the authors is confirmed with a reasonable scaling factor of ≃2.4. For the KV distribution, very good agreement with PATRIC simulations performed by Kornilov and Boine-Frankenheim is obtained.

Holographic wavefront sensor, based on diffuse Fourier holography

NASA Astrophysics Data System (ADS)

Gorelaya, Alina; Orlov, Vyacheslav; Venediktov, Vladimir

2017-09-01

Many areas of optical science and technology require fast and accurate measurement of the radiation wavefront shape. Today there are known a lot of wavefront sensor (WFS) techniques, and their number is growing up. The last years have brought a growing interest in several schematics of WFS, employing the holography principles and holographic optical elements (HOE). Some of these devices are just the improved versions of the standard and most popular Shack-Hartman WFS, while other are based on the intrinsic features of HOE. A holographic mode wavefront sensor is proposed, which makes it possible to measure up to several tens of wavefront modes. The increase in the number of measured modes is implemented using the conversion of a light wave entering the sensor into a wide diffuse light beam, which allows one to record a large number of holograms, each intended for measuring one of the modes.

Risk assessment of failure modes of gas diffuser liner of V94.2 siemens gas turbine by FMEA method

NASA Astrophysics Data System (ADS)

Mirzaei Rafsanjani, H.; Rezaei Nasab, A.

2012-05-01

Failure of welding connection of gas diffuser liner and exhaust casing is one of the failure modes of V94.2 gas turbines which are happened in some power plants. This defect is one of the uncertainties of customers when they want to accept the final commissioning of this product. According to this, the risk priority of this failure evaluated by failure modes and effect analysis (FMEA) method to find out whether this failure is catastrophic for turbine performance and is harmful for humans. By using history of 110 gas turbines of this model which are used in some power plants, the severity number, occurrence number and detection number of failure determined and consequently the Risk Priority Number (RPN) of failure determined. Finally, critically matrix of potential failures is created and illustrated that failure modes are located in safe zone.

Orthogonal Invariant Sets of the Diffusion Tensor and the Development of a Curvilinear Set Suitable for Low-Anisotropy Tissues

PubMed Central

Damion, Robin A.; Radjenovic, Aleksandra; Ingham, Eileen; Jin, Zhongmin; Ries, Michael E.

2013-01-01

We develop a curvilinear invariant set of the diffusion tensor which may be applied to Diffusion Tensor Imaging measurements on tissues and porous media. This new set is an alternative to the more common invariants such as fractional anisotropy and the diffusion mode. The alternative invariant set possesses a different structure to the other known invariant sets; the second and third members of the curvilinear set measure the degree of orthotropy and oblateness/prolateness, respectively. The proposed advantage of these invariants is that they may work well in situations of low diffusion anisotropy and isotropy, as is often observed in tissues such as cartilage. We also explore the other orthogonal invariant sets in terms of their geometry in relation to eigenvalue space; a cylindrical set, a spherical set (including fractional anisotropy and the mode), and a log-Euclidean set. These three sets have a common structure. The first invariant measures the magnitude of the diffusion, the second and third invariants capture aspects of the anisotropy; the magnitude of the anisotropy and the shape of the diffusion ellipsoid (the manner in which the anisotropy is realised). We also show a simple method to prove the orthogonality of the invariants within a set. PMID:24244366

Inferring diffusion in single live cells at the single-molecule level

PubMed Central

Robson, Alex; Burrage, Kevin; Leake, Mark C.

2013-01-01

The movement of molecules inside living cells is a fundamental feature of biological processes. The ability to both observe and analyse the details of molecular diffusion in vivo at the single-molecule and single-cell level can add significant insight into understanding molecular architectures of diffusing molecules and the nanoscale environment in which the molecules diffuse. The tool of choice for monitoring dynamic molecular localization in live cells is fluorescence microscopy, especially so combining total internal reflection fluorescence with the use of fluorescent protein (FP) reporters in offering exceptional imaging contrast for dynamic processes in the cell membrane under relatively physiological conditions compared with competing single-molecule techniques. There exist several different complex modes of diffusion, and discriminating these from each other is challenging at the molecular level owing to underlying stochastic behaviour. Analysis is traditionally performed using mean square displacements of tracked particles; however, this generally requires more data points than is typical for single FP tracks owing to photophysical instability. Presented here is a novel approach allowing robust Bayesian ranking of diffusion processes to discriminate multiple complex modes probabilistically. It is a computational approach that biologists can use to understand single-molecule features in live cells. PMID:23267182

Diffusion-cooled high-power single-mode waveguide CO2 laser for transmyocardial revascularization

NASA Astrophysics Data System (ADS)

Berishvili, I. I.; Bockeria, L. A.; Egorov, E. N.; Golubev, Vladimir S.; Galushkin, Michail G.; Kheliminsky, A. A.; Panchenko, Vladislav Y.; Roshin, A. P.; Sigaev, I. Y.; Vachromeeva, M. N.; Vasiltsov, Victor V.; Yoshina, V. I.; Zabelin, Alexandre M.; Zelenov, Evgenii V.

1999-01-01

The paper presents the results on investigations and development of multichannel waveguide CO2 laser with diffusion cooling of active medium excited by discharge of audio-frequency alternating current. The description of high-power single-mode CO2 laser with average beam power up to 1 kW is presented. The result of measurement of the laser basic parameters are offered, as well as the outcomes of performances of the laser head with long active zone, operating in waveguide mode. As an example of application of these laser, various capabilities a description of the developed medical system 'Genom' used in the transmyocardial laser revascularization (TMLR) procedure and clinical results of the possibilities of the TMLR in the surgical treatment are presented.

Isolator-combustor interaction in a dual-mode scramjet engine

NASA Technical Reports Server (NTRS)

Pratt, David T.; Heiser, William H.

1993-01-01

A constant-area diffuser, or 'isolator', is required in both the ramjet and scramjet operating regimes of a dual-mode engine configuration in order to prevent unstarts due to pressure feedback from the combustor. Because the nature of the combustor-isolator interaction is different in the two operational modes, however, attention is presently given to the use of thermal vs kinetic energy coordinates for these interaction processes' visualization. The results of the analysis thus conducted indicate that the isolator requires severe flow separation at combustor entry, and that its entropy-generating characteristics are more severe than an equivalent oblique shock. A constant-area diffuser is only marginally able to contain the equivalent normal shock required for subsonic combustor entry.

Progress on 3-D ICF simulations and Ray-Traced Power Deposition Method

NASA Astrophysics Data System (ADS)

Schmitt, Andrew J.; Fyfe, David E.

2016-10-01

We have performed 3D simulations of Omega-scale and NIF-scale spherical direct-drive targets with the massively parallel fastrad3d code. Of particular interest is the robustness of the targets to the low mode perturbations impressed on the target by the laser system and how it compares to the influence of the perturbations produced by laser imprinting. As part of this simulation capability, we have upgraded our smoothed 3D raytrace package to run in spherical geometry. This package, which connects rays to form bundles and performs power deposition calculations on the bundles, can decrease laser absorption noise while using fewer rays and less message passing. This model produces both the imprint and the low-mode asymmetry drive that we are interested in here. We show recent simulation results of directly-driven targets using conventional ignition drive, and report on the influences of the two sources - low mode asymmetry and laser imprint - as the pellet conditions (e.g. adiabat) are varied. Work supported by DoE/NNSA.

Investigation of Thermal Interface Materials Using Phase-Sensitive Transient Thermoreflectance Technique: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, X.; King, C.; DeVoto, D.

2014-08-01

With increasing power density in electronics packages/modules, thermal resistances at multiple interfaces are a bottleneck to efficient heat removal from the package. In this work, the performance of thermal interface materials such as grease, thermoplastic adhesives and diffusion-bonded interfaces are characterized using the phase-sensitive transient thermoreflectance technique. A multi-layer heat conduction model was constructed and theoretical solutions were derived to obtain the relation between phase lag and the thermal/physical properties. This technique enables simultaneous extraction of the contact resistance and bulk thermal conductivity of the TIMs. With the measurements, the bulk thermal conductivity of Dow TC-5022 thermal grease (70 tomore » 75 um bondline thickness) was 3 to 5 W/(m-K) and the contact resistance was 5 to 10 mm2-K/W. For the Btech thermoplastic material (45 to 80 μm bondline thickness), the bulk thermal conductivity was 20 to 50 W/(m-K) and the contact resistance was 2 to 5 mm2-K/W. Measurements were also conducted to quantify the thermal performance of diffusion-bonded interface for power electronics applications. Results with the diffusion-bonded sample showed that the interfacial thermal resistance is more than one order of magnitude lower than those of traditional TIMs, suggesting potential pathways to efficient thermal management.« less

NUMERICAL ANALYSES FOR TREATING DIFFUSION IN SINGLE-, TWO-, AND THREE-PHASE BINARY ALLOY SYSTEMS

NASA Technical Reports Server (NTRS)

Tenney, D. R.

1994-01-01

This package consists of a series of three computer programs for treating one-dimensional transient diffusion problems in single and multiple phase binary alloy systems. An accurate understanding of the diffusion process is important in the development and production of binary alloys. Previous solutions of the diffusion equations were highly restricted in their scope and application. The finite-difference solutions developed for this package are applicable for planar, cylindrical, and spherical geometries with any diffusion-zone size and any continuous variation of the diffusion coefficient with concentration. Special techniques were included to account for differences in modal volumes, initiation and growth of an intermediate phase, disappearance of a phase, and the presence of an initial composition profile in the specimen. In each analysis, an effort was made to achieve good accuracy while minimizing computation time. The solutions to the diffusion equations for single-, two-, and threephase binary alloy systems are numerically calculated by the three programs NAD1, NAD2, and NAD3. NAD1 treats the diffusion between pure metals which belong to a single-phase system. Diffusion in this system is described by a one-dimensional Fick's second law and will result in a continuous composition variation. For computational purposes, Fick's second law is expressed as an explicit second-order finite difference equation. Finite difference calculations are made by choosing the grid spacing small enough to give convergent solutions of acceptable accuracy. NAD2 treats diffusion between pure metals which form a two-phase system. Diffusion in the twophase system is described by two partial differential equations (a Fick's second law for each phase) and an interface-flux-balance equation which describes the location of the interface. Actual interface motion is obtained by a mass conservation procedure. To account for changes in the thicknesses of the two phases as diffusion progresses, a variable grid technique developed by Murray and Landis is employed. These equations are expressed in finite difference form and solved numerically. Program NAD3 treats diffusion between pure metals which form a two-phase system with an intermediate third phase. Diffusion in the three-phase system is described by three partial differential expressions of Fick's second law and two interface-flux-balance equations. As with the two-phase case, a variable grid finite difference is used to numerically solve the diffusion equations. Computation time is minimized without sacrificing solution accuracy by treating the three-phase problem as a two-phase problem when the thickness of the intermediate phase is less than a preset value. Comparisons between these programs and other solutions have shown excellent agreement. The programs are written in FORTRAN IV for batch execution on the CDC 6600 with a central memory requirement of approximately 51K (octal) 60 bit words.

Comparative study of silver nanoparticle permeation using Side-Bi-Side and Franz diffusion cells

NASA Astrophysics Data System (ADS)

Trbojevich, Raul A.; Fernandez, Avelina; Watanabe, Fumiya; Mustafa, Thikra; Bryant, Matthew S.

2016-03-01

Better understanding the mechanisms of nanoparticle permeation through membranes and packaging polymers has important implications for the evaluation of drug transdermal uptake, in food safety and the environmental implications of nanotechnology. In this study, permeation of 21 nm diameter silver nanoparticles (AgNPs) was tested using Side-Bi-Side and Franz static diffusion cells through hydrophilic 0.1 and 0.05 µm pore diameter 125 µm thick synthetic cellulose membranes, and 16 and 120 µm thick low-density polyethylene (LDPE) films. Experiments performed with LDPE films discarded permeation of AgNPs or Ag ions over the investigated time-frame in both diffusion systems. But controlled release of AgNPs has been quantified using semipermeable hydrophilic membranes. The permeation followed a quasi-linear time-dependent model during the experimental time-frame, which represents surface reaction-limited permeation. Diffusive flux, diffusion coefficients, and membrane permeability were determined as a function of pore size and diffusion model. Concentration gradient and pore size were key to understand mass transfer phenomena in the diffusion systems.

General technique for the integration of MIC/MMIC'S with waveguides

NASA Technical Reports Server (NTRS)

Geller, Bernard D. (Inventor); Zaghloul, Amir I. (Inventor)

1987-01-01

A technique for packaging and integrating of a microwave integrated circuit (MIC) or monolithic microwave integrated circuit (MMIC) with a waveguide uses a printed conductive circuit pattern on a dielectric substrate to transform impedance and mode of propagation between the MIC/MMIC and the waveguide. The virtually coplanar circuit pattern lies on an equipotential surface within the waveguide and therefore makes possible single or dual polarized mode structures.

An Analysis of the Joint Modular Intermodal Distribution System

DTIC Science & Technology

2007-06-01

the differing airframes. “Two methods are available to move a CROP-load of ammunition: 1. Reconfigure the load from the CROP onto multiple 463L...used among the services lack: • Transportability across different modes without re-handling/packaging • Quick reconfiguration for onward movement...numerous linkages among different channels of distribution. In the world of integrated logistics, that means that ground, rail, air, and sea modes of

Model-free adaptive sliding mode controller design for generalized projective synchronization of the fractional-order chaotic system via radial basis function neural networks

NASA Astrophysics Data System (ADS)

Wang, L. M.

2017-09-01

A novel model-free adaptive sliding mode strategy is proposed for a generalized projective synchronization (GPS) between two entirely unknown fractional-order chaotic systems subject to the external disturbances. To solve the difficulties from the little knowledge about the master-slave system and to overcome the bad effects of the external disturbances on the generalized projective synchronization, the radial basis function neural networks are used to approach the packaged unknown master system and the packaged unknown slave system (including the external disturbances). Consequently, based on the slide mode technology and the neural network theory, a model-free adaptive sliding mode controller is designed to guarantee asymptotic stability of the generalized projective synchronization error. The main contribution of this paper is that a control strategy is provided for the generalized projective synchronization between two entirely unknown fractional-order chaotic systems subject to the unknown external disturbances, and the proposed control strategy only requires that the master system has the same fractional orders as the slave system. Moreover, the proposed method allows us to achieve all kinds of generalized projective chaos synchronizations by turning the user-defined parameters onto the desired values. Simulation results show the effectiveness of the proposed method and the robustness of the controlled system.

Modeling Impact-induced Failure of Polysilicon MEMS: A Multi-scale Approach.

PubMed

Mariani, Stefano; Ghisi, Aldo; Corigliano, Alberto; Zerbini, Sarah

2009-01-01

Failure of packaged polysilicon micro-electro-mechanical systems (MEMS) subjected to impacts involves phenomena occurring at several length-scales. In this paper we present a multi-scale finite element approach to properly allow for: (i) the propagation of stress waves inside the package; (ii) the dynamics of the whole MEMS; (iii) the spreading of micro-cracking in the failing part(s) of the sensor. Through Monte Carlo simulations, some effects of polysilicon micro-structure on the failure mode are elucidated.

Steamer Training System and Graphics Editor, 1987 Version

DTIC Science & Technology

1987-09-01

NIIHAU : >simenv>documentation>simenv-read me.text.24 7/30/87 18:29:51 Page 1 SMode: Text-- Herewith are instructions for installing the Genera 7.0 (should...lowercase: t; package: file-system; - (set-logical-pathname-host "simenv" : physical-host " niihau " :translations ((C"simenv;" ">3imenv>") steamer-system...translations ;;--- mode: lisp; base: 10; lowercase: t; package: file-system;-- (fS:set-logical-pathname-host "steamer-system" :physical-host " niihau

Apparent Activation Energies Associated with Protein Dynamics on Hydrophobic and Hydrophilic Surfaces

PubMed Central

Langdon, Blake B.; Kastantin, Mark; Schwartz, Daniel K.

2012-01-01

With the use of single-molecule total internal reflection fluorescence microscopy (TIRFM), the dynamics of bovine serum albumin (BSA) and human fibrinogen (Fg) at low concentrations were observed at the solid-aqueous interface as a function of temperature on hydrophobic trimethylsilane (TMS) and hydrophilic fused silica (FS) surfaces. Multiple dynamic modes and populations were observed and characterized by their surface residence times and squared-displacement distributions (surface diffusion). Characteristic desorption and diffusion rates for each population/mode were generally found to increase with temperature, and apparent activation energies were determined from Arrhenius analyses. The apparent activation energies of desorption and diffusion were typically higher on FS than on TMS surfaces, suggesting that protein desorption and mobility were hindered on hydrophilic surfaces due to favorable protein-surface and solvent-surface interactions. The diffusion of BSA on TMS appeared to be activationless for several populations, whereas diffusion on FS always exhibited an apparent activation energy. All activation energies were small in absolute terms (generally only a few kBT), suggesting that most adsorbed protein molecules are weakly bound and move and desorb readily under ambient conditions. PMID:22713578

Thin Layer Drying Kinetics of By-Products from Olive Oil Processing

PubMed Central

Montero, Irene; Miranda, Teresa; Arranz, Jose Ignacio; Rojas, Carmen Victoria

2011-01-01

The thin-layer behavior of by-products from olive oil production was determined in a solar dryer in passive and active operation modes for a temperature range of 20–50 °C. The increase in the air temperature reduced the drying time of olive pomace, sludge and olive mill wastewater. Moisture ratio was analyzed to obtain effective diffusivity values, varying in the oil mill by-products from 9.136 × 10−11 to 1.406 × 10−9 m2/s in forced convection (ma = 0.22 kg/s), and from 9.296 × 10−11 to 6.277 × 10−10 m2/s in natural convection (ma = 0.042 kg/s). Diffusivity values at each temperature were obtained using the Fick’s diffusion model and, regardless of the convection, they increased with the air temperature. The temperature dependence on the effective diffusivity was determined by an Arrhenius type relationship. The activation energies were found to be 38.64 kJ/mol, 30.44 kJ/mol and 47.64 kJ/mol for the olive pomace, the sludge and the olive mill wastewater in active mode, respectively, and 91.35 kJ/mol, 14.04 kJ/mol and 77.15 kJ/mol in natural mode, in that order. PMID:22174639

Intermode light diffusion in multimode optical waveguides with rough surfaces.

PubMed

Stepanov, S; Chaikina, E I; Leskova, T A; Méndez, E R

2005-06-01

A theoretical analysis of incoherent intermode light power diffusion in multimode dielectric waveguides with rough (corrugated) surfaces is presented. The correlation length a of the surface-profile variations is assumed to be sufficiently large (a less less than lambda/2pi) to permit light scattering into the outer space only from the modes close to the critical angles of propagation and yet sufficiently small (a less less than d, where d is the average width of the waveguide) to permit direct interaction between a given mode and a large number of neighboring ones. The cases of a one-dimensional (1D) slab waveguide and a two-dimensional cylindrical waveguide (optical fiber) are analyzed, and we find that in both cases the partial differential equations that govern the evolution of the angular light power profile propagating along the waveguide are 1D and of the diffusion type. However, whereas in the former case the effective conductivity coefficient proves to be linearly dependent on the transverse-mode wave number, in the latter one the linear dependence is for the effective diffusion coefficient. The theoretical predictions are in reasonable agreement with experimental results for the intermode power diffusion in multimode (700 x 700) optical fibers with etched surfaces. The characteristic length of dispersion of a narrow angular power profile evaluated from the correlation length and standard deviation of heights of the surface profile proved to be in good agreement with the experimentally observed changes in the output angular power profiles.

Strength of Default Mode Resting-State Connectivity Relates to White Matter Integrity in Children

ERIC Educational Resources Information Center

Gordon, Evan M.; Lee, Philip S.; Maisog, Jose M.; Foss-Feig, Jennifer; Billington, Michael E.; VanMeter, John; Vaidya, Chandan J.

2011-01-01

A default mode network of brain regions is known to demonstrate coordinated activity during the resting state. While the default mode network is well characterized in adults, few investigations have focused upon its development. We scanned 9-13-year-old children with diffusion tensor imaging and resting-state functional magnetic resonance imaging.…

Analysis of XMM-Newton Data from Extended Sources and the Diffuse X-Ray Background

NASA Technical Reports Server (NTRS)

Snowden, Steven

2011-01-01

Reduction of X-ray data from extended objects and the diffuse background is a complicated process that requires attention to the details of the instrumental response as well as an understanding of the multiple background components. We present methods and software that we have developed to reduce data from XMM-Newton EPIC imaging observations for both the MOS and PN instruments. The software has now been included in the Science Analysis System (SAS) package available through the XMM-Newton Science Operations Center (SOC).

Modeling of radiation damage recovery in particle detectors based on GaN

NASA Astrophysics Data System (ADS)

Gaubas, E.; Ceponis, T.; Pavlov, J.

2015-12-01

The pulsed characteristics of the capacitor-type and PIN diode type detectors based on GaN have been simulated using the dynamic and drift-diffusion models. The drift-diffusion current simulations have been implemented by employing the commercial software package Synopsys TCAD Sentaurus. The bipolar drift regime has been analyzed. The possible internal gain in charge collection through carrier multiplication processes determined by impact ionization has been considered in order to compensate carrier lifetime reduction due to radiation defects introduced into GaN material of detector.

Simulations of Operation Dynamics of Different Type GaN Particle Sensors

PubMed Central

Gaubas, Eugenijus; Ceponis, Tomas; Kalesinskas, Vidas; Pavlov, Jevgenij; Vysniauskas, Juozas

2015-01-01

The operation dynamics of the capacitor-type and PIN diode type detectors based on GaN have been simulated using the dynamic and drift-diffusion models. The drift-diffusion current simulations have been implemented by employing the software package Synopsys TCAD Sentaurus. The monopolar and bipolar drift regimes have been analyzed by using dynamic models based on the Shockley-Ramo theorem. The carrier multiplication processes determined by impact ionization have been considered in order to compensate carrier lifetime reduction due to introduction of radiation defects into GaN detector material. PMID:25751080

Batch calculations in CalcHEP

NASA Astrophysics Data System (ADS)

Pukhov, A.

2003-04-01

CalcHEP is a clone of the CompHEP project which is developed by the author outside of the CompHEP group. CompHEP/CalcHEP are packages for automatic calculations of elementary particle decay and collision properties in the lowest order of perturbation theory. The main idea prescribed into the packages is to make available passing on from the Lagrangian to the final distributions effectively with a high level of automation. According to this, the packages were created as a menu driven user friendly programs for calculations in the interactive mode. From the other side, long-time calculations should be done in the non-interactive regime. Thus, from the beginning CompHEP has a problem of batch calculations. In CompHEP 33.23 the batch session was realized by mean of interactive menu which allows to the user to formulate the task for batch. After that the not-interactive session was launched. This way is too restricted, not flexible, and leads to doubling in programming. In this article I discuss another approach how one can force an interactive program to work in non-interactive mode. This approach was realized in CalcHEP 2.1 disposed on http://theory.sinp.msu.ru/~pukhov/calchep.html.

Elasticity and hydrodynamic properties of ``doped solvent dilute'' lamellar phases

NASA Astrophysics Data System (ADS)

Nallet, Frédéric; Roux, Didier; Quilliet, Catherine; Fabre, Pascale; Milner, Scott T.

1994-09-01

The equilibrium fluctuations and weakly out-of-equilibrium relaxation properties of “doped solvent" dilute lamellar phases are investigated, both theoretically and experimentally, in the low-frequency, long-wavelength limit. The physical system of interest is a three-component smectic A lyotropic liquid crystal where surfactant bilayers infinite in extent are periodically stacked along one direction in space and separated by a colloidal solution. Two experimentally relevant modes are found in the lowest frequency part of the fluctuation spectrum of such multicomponent systems. Both are associated to the relaxation of coupled layer displacement and colloid concentration waves. In the limit of small coupling, one mode is close to the well-known undulation/baroclinic mode of two-component lamellar phases, while the other corresponds to the Brownian diffusive motion of the colloid in an anisotropic medium. Elastic constants of the smectic liquid crystal and diffusion parameters of the colloidal solution may be deduced from a measurement of the anisotropic dispersion relation of these two modes, as illustrated by dynamic light scattering experiments on the ferrosmectic system. Les fluctuations à l'équilibre ainsi que la relaxation des états légèrement en dehors de l'équilibre des phases lamellaires à “solvant dopé” sont étudiées, aussi bien d'un point de vue théorique qu'expérimental, dans la limite de basses fréquences et de grandes longueurs d'onde. Les systèmes décrits sont des cristaux-liquides smectiques A lyotropes formés de trois constituants : un tensioactif en solution dans une suspension colloïdale forme des bicouches de grande extension latérale qui s'empilent de façon périodique le long d'une direction dans l'espace. Avec de tels systèmes anisotropes et à plusieurs constituants deux modes présents dans la partie à basse fréquence du spectre des fluctuations (associés à la relaxation d'ondes, couplées, de concentration colloïdale et de déplacement des couches smectiques) ont une certaine importance expérimentale. Dans la limite d'un couplage faible, l'un des deux modes est similaire au mode barocline des phases lamellaires à deux constituants ; le second s'identifie au mouvement brownien de diffusion d'un colloïde dans un substrat anisotrope. Les constantes élastiques du cristal liquide smectique de même que le coefficient de diffusion du colloïde peuvent en principe être déduits de la mesure des relations anisotropes de dispersion de ces deux modes ; cela est illustré par des expériences de diffusion quasi-élastique de la lumière sur des ferrosmectiques.

A new diffusion matrix for whistler mode chorus waves

NASA Astrophysics Data System (ADS)

Horne, Richard B.; Kersten, Tobias; Glauert, Sarah A.; Meredith, Nigel P.; Boscher, Daniel; Sicard-Piet, Angelica; Thorne, Richard M.; Li, Wen

2013-10-01

Global models of the Van Allen radiation belts usually include resonant wave-particle interactions as a diffusion process, but there is a large uncertainty over the diffusion rates. Here we present a new diffusion matrix for whistler mode chorus waves that can be used in such models. Data from seven satellites are used to construct 3536 power spectra for upper and lower band chorus for 1.5≤L∗≤10 MLT, magnetic latitude 0°≤|λm|≤60° and five levels of Kp. Five density models are also constructed from the data. Gaussian functions are fitted to the spectra and capture typically 90% of the wave power. The frequency maxima of the power spectra vary with L∗ and are typically lower than that used previously. Lower band chorus diffusion increases with geomagnetic activity and is largest between 21:00 and 12:00 MLT. Energy diffusion extends to a few megaelectron volts at large pitch angles >60° and at high energies exceeds pitch angle diffusion at the loss cone. Most electron diffusion occurs close to the geomagnetic equator (<12°). Pitch angle diffusion rates for lower band chorus increase with L∗ and are significant at L∗=8 even for low levels of geomagnetic activity, while upper band chorus is restricted to mainly L∗<6. The combined drift and bounce averaged diffusion rates for upper and lower band chorus extend from a few kiloelectron volts near the loss cone up to several megaelectron volts at large pitch angles indicating loss at low energies and net acceleration at high energies.

Spectral Analysis of Non-ideal MRI Modes: The Effect of Hall Diffusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohandas, Gopakumar; Pessah, Martin E., E-mail: gopakumar@nbi.ku.dk, E-mail: mpessah@nbi.ku.dk

The effect of magnetic field diffusion on the stability of accretion disks is a problem that has attracted considerable interest of late. In particular, the Hall effect has the potential to bring about remarkable changes in the dynamical behavior of disks that are without parallel. In this paper, we conduct a systematic examination of the linear eigenmodes in a weakly magnetized differentially rotating gas with a special focus on Hall diffusion. We first develop a geometrical representation of the eigenmodes and provide a detailed quantitative description of the polarization properties of the oscillatory modes under the combined influence of themore » Coriolis and Hall effects. We also analyze the effects of magnetic diffusion on the structure of the unstable modes and derive analytical expressions for the kinetic and magnetic stresses and energy densities associated with the non-ideal magnetorotational instability (MRI). Our analysis explicitly demonstrates that, if the dissipative effects are relatively weak, the kinetic stresses and energies make up the dominant contribution to the total stress and energy density when the equilibrium angular momentum and magnetic field vectors are anti-parallel. This is in sharp contrast to what is observed in the case of the ideal or dissipative MRI. We conduct shearing box simulations and find very good agreement with the results derived from linear theory. Because the modes under consideration are also exact solutions of the nonlinear equations, the unconventional nature of the kinetic and magnetic stresses may have significant implications for the nonlinear evolution in some regions of protoplanetary disks.« less

The Effect of Weak Resistivity and Weak Thermal Diffusion on Short-wavelength Magnetic Buoyancy Instability

NASA Astrophysics Data System (ADS)

Gradzki, Marek J.; Mizerski, Krzysztof A.

2018-03-01

Magnetic buoyancy instability in weakly resistive and thermally conductive plasma is an important mechanism of magnetic field expulsion in astrophysical systems. It is often invoked, e.g., in the context of the solar interior. Here, we revisit a problem introduc`ed by Gilman: the short-wavelength linear stability of a plane layer of compressible isothermal and weakly diffusive fluid permeated by a horizontal magnetic field of strength decreasing with height. In this physical setting, we investigate the effect of weak resistivity and weak thermal conductivity on the short-wavelength perturbations, localized in the vertical direction, and show that the presence of diffusion allows to establish the wavelength of the most unstable mode, undetermined in an ideal fluid. When diffusive effects are neglected, the perturbations are amplified at a rate that monotonically increases as the wavelength tends to zero. We demonstrate that, when the resistivity and thermal conduction are introduced, the wavelength of the most unstable perturbation is established and its scaling law with the diffusion parameters depends on gradients of the mean magnetic field, temperature, and density. Three main dynamical regimes are identified, with the wavelength of the most unstable mode scaling as either λ /d∼ {{ \\mathcal U }}κ 3/5 or λ /d∼ {{ \\mathcal U }}κ 3/4 or λ /d∼ {{ \\mathcal U }}κ 1/3, where d is the layer thickness and {{ \\mathcal U }}κ is the ratio of the characteristic thermal diffusion velocity scale to the free-fall velocity. Our analytic results are backed up by a series of numerical solutions. The two-dimensional interchange modes are shown to dominate over three-dimensional ones when the magnetic field and/or temperature gradients are strong enough.

Analysis of drift effects on the tokamak power scrape-off width using SOLPS-ITER

NASA Astrophysics Data System (ADS)

Meier, E. T.; Goldston, R. J.; Kaveeva, E. G.; Makowski, M. A.; Mordijck, S.; Rozhansky, V. A.; Senichenkov, I. Yu; Voskoboynikov, S. P.

2016-12-01

SOLPS-ITER, a comprehensive 2D scrape-off layer modeling package, is used to examine the physical mechanisms that set the scrape-off width ({λq} ) for inter-ELM power exhaust. Guided by Goldston’s heuristic drift (HD) model, which shows remarkable quantitative agreement with experimental data, this research examines drift effects on {λq} in a DIII-D H-mode magnetic equilibrium. As a numerical expedient, a low target recycling coefficient of 0.9 is used in the simulations, resulting in outer target plasma that is sheath limited instead of conduction limited as in the experiment. Scrape-off layer (SOL) particle diffusivity (D SOL) is scanned from 1 to 0.1 m2 s-1. Across this diffusivity range, outer divertor heat flux is dominated by a narrow (˜3-4 mm when mapped to the outer midplane) electron convection channel associated with thermoelectric current through the SOL from outer to inner divertor. An order-unity up-down ion pressure asymmetry allows net ion drift flux across the separatrix, facilitated by an artificial mechanism that mimics the anomalous electron transport required for overall ambipolarity in the HD model. At {{D}\\text{SOL}}=0.1 m2 s-1, the density fall-off length is similar to the electron temperature fall-off length, as predicted by the HD model and as seen experimentally. This research represents a step toward a deeper understanding of the power scrape-off width, and serves as a basis for extending fluid modeling to more experimentally relevant, high-collisionality regimes.

Analysis of drift effects on the tokamak power scrape-off width using SOLPS-ITER

DOE PAGES

Meier, E. T.; Goldston, R. J.; Kaveeva, E. G.; ...

2016-11-02

SOLPS-ITER, a comprehensive 2D scrape-off layer modeling package, is used to examine the physical mechanisms that set the scrape-off width (more » $${{\\lambda}_{q}}$$ ) for inter-ELM power exhaust. Guided by Goldston's heuristic drift (HD) model, which shows remarkable quantitative agreement with experimental data, this research examines drift effects on $${{\\lambda}_{q}}$$ in a DIII-D H-mode magnetic equilibrium. As a numerical expedient, a low target recycling coefficient of 0.9 is used in the simulations, resulting in outer target plasma that is sheath limited instead of conduction limited as in the experiment. Scrape-off layer (SOL) particle diffusivity (D SOL) is scanned from 1 to 0.1 m2 s –1. Across this diffusivity range, outer divertor heat flux is dominated by a narrow (~3–4mm when mapped to the outer midplane) electron convection channel associated with thermoelectric current through the SOL from outer to inner divertor. An order-unity up–down ion pressure asymmetry allows net ion drift flux across the separatrix, facilitated by an artificial mechanism that mimics the anomalous electron transport required for overall ambipolarity in the HD model. At $${{D}_{\\text{SOL}}}=0.1$$ m2 s –1, the density fall-off length is similar to the electron temperature fall-off length, as predicted by the HD model and as seen experimentally. Furthermore, this research represents a step toward a deeper understanding of the power scrape-off width, and serves as a basis for extending fluid modeling to more experimentally relevant, high-collisionality regimes.« less

Apollo 17 Lunar Surface Experiments package

NASA Image and Video Library

1972-05-10

S72-37260 (November 1972) --- The remote antenna for the Lunar Seismic Profiling Experiment, Numbered S-203, a component of the Apollo Lunar Surface Experiments Package which will be carried on the Apollo 17 lunar landing mission. LSPE components are four geophones similar to those used in earlier active seismic experiments an electronics package in the ALSEP central station, and eight explosive packages which will be deployed during the geology traverse. The four geophones will be placed one in the center and at each corner of a 90-meter equilateral triangle. Explosive charges placed on the surface will generate seismic waves of varying strengths to provide data on the structural profile of the landing site. After the charges have been fired by ground command, the experiment will settle down into a passive listening mode, detecting moonquakes, meteorite impacts and the thump caused by the Lunar Module ascent stage impact. The antenna is of the telescoping type.

NASA-DoD Lead-Free Electronics Project

NASA Technical Reports Server (NTRS)

Kessel, Kurt

2009-01-01

In response to concerns about risks from lead-free induced faults to high reliability products, NASA has initiated a multi-year project to provide manufacturers and users with data to clarify the risks of lead-free materials in their products. The project will also be of interest to component manufacturers supplying to high reliability markets. The project was launched in November 2006. The primary technical objective of the project is to undertake comprehensive testing to generate information on failure modes/criteria to better understand the reliability of: (1) Packages (e.g., Thin Small Outline Package [TSOP], Ball Grid Array [BGA], Plastic Dual In-line Package [PDIP]) assembled and reworked with solder interconnects consisting of lead-free alloys (2) Packages (e.g., TSOP, BGA, PDIP) assembled and reworked with solder interconnects consisting of mixed alloys, lead component finish/lead-free solder and lead-free component finish/SnPb solder

Dynamic Theory of Relativistic Electrons Stochastic Heating by Whistler Mode Waves with Application to the Earth Magnetosphere

NASA Technical Reports Server (NTRS)

Khazanov, G. V.; Tel'nikhin, A. A.; Kronberg, T. K.

2007-01-01

In the Hamiltonian approach an electron motion in a coherent packet of the whistler mode waves propagating along the direction of an ambient magnetic field is studied. The physical processes by which these particles are accelerated to high energy are established. Equations governing a particle motion were transformed in to a closed pair of nonlinear difference equations. The solutions of these equations have shown there exists the energetic threshold below that the electron motion is regular, and when the initial energy is above the threshold an electron moves stochastically. Particle energy spectra and pitch angle electron scattering are described by the Fokker-Planck-Kolmogorov equations. Calculating the stochastic diffusion of electrons due to a spectrum of whistler modes is presented. The parametric dependence of the diffusion coefficients on the plasma particle density, magnitude of wave field, and the strength of magnetic field is studies. It is shown that significant pitch angle diffusion occurs for the Earth radiation belt electrons with energies from a few keV up to a few MeV.

A Search for Plasma "Fingers" in the Io Torus

NASA Astrophysics Data System (ADS)

Jaggar, S.; Schneider, N. M.; Bagenal, F.; Trauger, J. T.

1996-09-01

We have compared model and data images of the Io plasma torus to test the radial diffusion model of Yang et al. (J. Geophys. Res., Vol 99, p. 8755, 1994). They predict that radial diffusion takes the form of `fingers' of dense plasma flowing outward due to the centrifugal force. Furthermore, they show that the spatial scale of these significant longitudinal variations is approximately 15(o) . The observations used in this study were obtained using a 2.4m telescope at Las Campanas Observatory using a narrowband filter to isolate emissions from S(++) at 9531 Angstroms. S(++) images are dominated by emission from the warm torus where outward radial transport is expected. Although S(+) images are brighter, they are contaminated by emission from the cold torus where fingers are not expected. We used the Colorado Io Torus Emission Package (CITEP)(Taylor et al., J. Geophys. Res., Vol. 100, p. 19541, 1995) to simulate images of the torus with fingers. CITEP is a comprehensive program which incorporates accurate atomic physics, plasma physics and magnetic field models to simulate the brightness and morphology or torus emissions. We used a Voyager empirical model (Bagenal, J. Geophys. Res., Vol. 99, p. 11043, 1994) modulated by a sinusoidal longitudinal density variation with a 15(o) period and an amplitude proportional to the density at that L-shell. We compared simulated images with data to determine the minimum density contrast necessary to make fingers detectable. We place an upper limit on the density contrast of +/- 20% on a 15(o) spatial scale. We conclude that either the density contrast of this mode of transport is small, or other processes are more important for radial transport. This constraint can also be used in other radial diffusion models which predict density variations on this spatial scale. This work has been supported by NASA's Planetary Astronomy and Planetary Atmospheres programs.

Magnon diffusion theory for the spin Seebeck effect in ferromagnetic and antiferromagnetic insulators

NASA Astrophysics Data System (ADS)

Rezende, Sergio M.; Azevedo, Antonio; Rodríguez-Suárez, Roberto L.

2018-05-01

In magnetic insulators, spin currents are carried by the elementary excitations of the magnetization: spin waves or magnons. In simple ferromagnetic insulators there is only one magnon mode, while in two-sublattice antiferromagnetic insulators (AFIs) there are two modes, which carry spin currents in opposite directions. Here we present a theory for the diffusive magnonic spin current generated in a magnetic insulator layer by a thermal gradient in the spin Seebeck effect. We show that the formulations describing magnonic perturbation using a position-dependent chemical potential and those using a magnon accumulation are completely equivalent. Then we develop a drift–diffusion formulation for magnonic spin transport treating the magnon accumulation governed by the Boltzmann transport and diffusion equations and considering the full boundary conditions at the surfaces and interfaces of an AFI/normal metal bilayer. The theory is applied to the ferrimagnetic yttrium iron garnet and to the AFIs MnF2 and NiO, providing good quantitative agreement with experimental data.

78 FR 3967 - Notice of Application for Special Permits

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-17

...). transportation in Branchburg, NJ. commerce of PG II corrosive materials described as Potassium Hydroxide Solution, UN 1814 and Sodium Hydroxide Solution, UN 1824 in a UN 50G Fiberboard Large Packaging. (modes 1, 2, 3...

Application of ISO22000 and Failure Mode and Effect Analysis (fmea) for Industrial Processing of Poultry Products

NASA Astrophysics Data System (ADS)

Varzakas, Theodoros H.; Arvanitoyannis, Ioannis S.

Failure Mode and Effect Analysis (FMEA) model has been applied for the risk assessment of poultry slaughtering and manufacturing. In this work comparison of ISO22000 analysis with HACCP is carried out over poultry slaughtering, processing and packaging. Critical Control points and Prerequisite programs (PrPs) have been identified and implemented in the cause and effect diagram (also known as Ishikawa, tree diagram and fishbone diagram).

SEAWAT Version 4: A Computer Program for Simulation of Multi-Species Solute and Heat Transport

USGS Publications Warehouse

Langevin, Christian D.; Thorne, Daniel T.; Dausman, Alyssa M.; Sukop, Michael C.; Guo, Weixing

2008-01-01

The SEAWAT program is a coupled version of MODFLOW and MT3DMS designed to simulate three-dimensional, variable-density, saturated ground-water flow. Flexible equations were added to the program to allow fluid density to be calculated as a function of one or more MT3DMS species. Fluid density may also be calculated as a function of fluid pressure. The effect of fluid viscosity variations on ground-water flow was included as an option. Fluid viscosity can be calculated as a function of one or more MT3DMS species, and the program includes additional functions for representing the dependence on temperature. Although MT3DMS and SEAWAT are not explicitly designed to simulate heat transport, temperature can be simulated as one of the species by entering appropriate transport coefficients. For example, the process of heat conduction is mathematically analogous to Fickian diffusion. Heat conduction can be represented in SEAWAT by assigning a thermal diffusivity for the temperature species (instead of a molecular diffusion coefficient for a solute species). Heat exchange with the solid matrix can be treated in a similar manner by using the mathematically equivalent process of solute sorption. By combining flexible equations for fluid density and viscosity with multi-species transport, SEAWAT Version 4 represents variable-density ground-water flow coupled with multi-species solute and heat transport. SEAWAT Version 4 is based on MODFLOW-2000 and MT3DMS and retains all of the functionality of SEAWAT-2000. SEAWAT Version 4 also supports new simulation options for coupling flow and transport, and for representing constant-head boundaries. In previous versions of SEAWAT, the flow equation was solved for every transport timestep, regardless of whether or not there was a large change in fluid density. A new option was implemented in SEAWAT Version 4 that allows users to control how often the flow field is updated. New options were also implemented for representing constant-head boundaries with the Time-Variant Constant-Head (CHD) Package. These options allow for increased flexibility when using CHD flow boundaries with the zero-dispersive flux solute boundaries implemented by MT3DMS at constant-head cells. This report contains revised input instructions for the MT3DMS Dispersion (DSP) Package, Variable-Density Flow (VDF) Package, Viscosity (VSC) Package, and CHD Package. The report concludes with seven cases of an example problem designed to highlight many of the new features.

Preliminary design package for solar heating and cooling systems

NASA Technical Reports Server (NTRS)

1978-01-01

Summarized preliminary design information on activities associated with the development, delivery and support of solar heating and cooling systems is given. These systems are for single family dwellings and commercial applications. The heating/cooling system use a reversible vapor compression heat pump that is driven in the cooling mode by a Rankine power loop, and in the heating mode by a variable speed electric motor. The heating/cooling systems differ from the heating-only systems in the arrangement of the heat pump subsystem and the addition of a cooling tower to provide the heat sink for cooling mode operation.

A novel multiple headspace extraction gas chromatographic method for measuring the diffusion coefficient of methanol in water and in olive oil.

PubMed

Zhang, Chun-Yun; Chai, Xin-Sheng

2015-03-13

A novel method for the determination of the diffusion coefficient (D) of methanol in water and olive oil has been developed. Based on multiple headspace extraction gas chromatography (MHE-GC), the methanol released from the liquid sample of interest in a closed sample vial was determined in a stepwise fashion. A theoretical model was derived to establish the relationship between the diffusion coefficient and the GC signals from MHE-GC measurements. The results showed that the present method has an excellent precision (RSD<1%) in the linear fitting procedure and good accuracy for the diffusion coefficients of methanol in both water and olive oil, when compared with data reported in the literature. The present method is simple and practical and can be a valuable tool for the determination of the diffusion coefficient of volatile analyte(s) into food simulants from food and beverage packaging material, both in research studies and in actual applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Diffusion for holographic lattices

NASA Astrophysics Data System (ADS)

Donos, Aristomenis; Gauntlett, Jerome P.; Ziogas, Vaios

2018-03-01

We consider black hole spacetimes that are holographically dual to strongly coupled field theories in which spatial translations are broken explicitly. We discuss how the quasinormal modes associated with diffusion of heat and charge can be systematically constructed in a long wavelength perturbative expansion. We show that the dispersion relation for these modes is given in terms of the thermoelectric DC conductivity and static susceptibilities of the dual field theory and thus we derive a generalised Einstein relation from Einstein's equations. A corollary of our results is that thermodynamic instabilities imply specific types of dynamical instabilities of the associated black hole solutions.

Dry-film polymer waveguide for silicon photonics chip packaging.

PubMed

Hsu, Hsiang-Han; Nakagawa, Shigeru

2014-09-22

Polymer waveguide made by dry film process is demonstrated for silicon photonics chip packaging. With 8 μm × 11.5 μm core waveguide, little penalty is observed up to 25 Gbps before or after the light propagate through a 10-km long single-mode fiber (SMF). Coupling loss to SMF is 0.24 dB and 1.31 dB at the polymer waveguide input and output ends, respectively. Alignment tolerance for 0.5 dB loss increase is +/- 1.0 μm along both vertical and horizontal directions for the coupling from the polymer waveguide to SMF. The dry-film polymer waveguide demonstrates promising performance for silicon photonics chip packaging used in next generation optical multi-chip module.

A pilot DTI analysis in patients with recent onset post-traumatic stress disorder

NASA Astrophysics Data System (ADS)

Liu, Yang; Li, Liang; Li, Baojuan; Zhang, Xi; Lu, Hongbing

2016-03-01

To explore the alteration in white matter between survivors with recent onset post-traumatic stress disorder (PTSD) and without PTSD, who survived from the same coal mine flood disaster, the diffusion tensor imaging (DTI) sequences were analyzed using DTI studio and statistical parametric mapping (SPM) packages in this paper. From DTI sequence, the fractional anisotropy (FA) value describes the degree of anisotropy of a diffusion process, while the apparent diffusion coefficient (ADC) value reflects the magnitude of water diffusion. The DTI analyses between PTSD and non-PTSD indicate lower FA values in the right caudate nucleus, right middle temporal gyrus, right fusiform gyrus, and right superior temporal gyrus, and higher ADC values in the right superior temporal gyrus and right corpus callosum of the subjects with PTSD. These results are partly in line with our previous volume and cortical thickness analyses, indicating the importance of multi-modality analysis for PTSD.

A New Feature-Enhanced Speckle Reduction Method Based on Multiscale Analysis for Ultrasound B-Mode Imaging.

PubMed

Kang, Jinbum; Lee, Jae Young; Yoo, Yangmo

2016-06-01

Effective speckle reduction in ultrasound B-mode imaging is important for enhancing the image quality and improving the accuracy in image analysis and interpretation. In this paper, a new feature-enhanced speckle reduction (FESR) method based on multiscale analysis and feature enhancement filtering is proposed for ultrasound B-mode imaging. In FESR, clinical features (e.g., boundaries and borders of lesions) are selectively emphasized by edge, coherence, and contrast enhancement filtering from fine to coarse scales while simultaneously suppressing speckle development via robust diffusion filtering. In the simulation study, the proposed FESR method showed statistically significant improvements in edge preservation, mean structure similarity, speckle signal-to-noise ratio, and contrast-to-noise ratio (CNR) compared with other speckle reduction methods, e.g., oriented speckle reducing anisotropic diffusion (OSRAD), nonlinear multiscale wavelet diffusion (NMWD), the Laplacian pyramid-based nonlinear diffusion and shock filter (LPNDSF), and the Bayesian nonlocal means filter (OBNLM). Similarly, the FESR method outperformed the OSRAD, NMWD, LPNDSF, and OBNLM methods in terms of CNR, i.e., 10.70 ± 0.06 versus 9.00 ± 0.06, 9.78 ± 0.06, 8.67 ± 0.04, and 9.22 ± 0.06 in the phantom study, respectively. Reconstructed B-mode images that were developed using the five speckle reduction methods were reviewed by three radiologists for evaluation based on each radiologist's diagnostic preferences. All three radiologists showed a significant preference for the abdominal liver images obtained using the FESR methods in terms of conspicuity, margin sharpness, artificiality, and contrast, p<0.0001. For the kidney and thyroid images, the FESR method showed similar improvement over other methods. However, the FESR method did not show statistically significant improvement compared with the OBNLM method in margin sharpness for the kidney and thyroid images. These results demonstrate that the proposed FESR method can improve the image quality of ultrasound B-mode imaging by enhancing the visualization of lesion features while effectively suppressing speckle noise.

E. coli chemotaxis and super-diffusion

NASA Astrophysics Data System (ADS)

Dobnikar, Jure; Matthäus, Franziska; Jagodic, Marko

2010-03-01

The bacteria E. coli actively propel by switching between clockwise and anti-clockwise rotation of the flagella attached to their cell membranes. This results in two modes of motion: tumbling and swimming. The switching between the two modes is coupled to the ligand sensing through the chemotactic signalling pathway inside the cell. We modelled the signalling pathway and performed numerical simulations of the chemotactic motion of a large number of E. coli bacteria under various external conditions. We have shown that under certain conditions the thermal noise in the level of receptor-bound CheR (an enzyme responsible for methylation of the receptor sites) leads to super-diffusive behaviour (L'evy walk) which is advantageous for the bacterial populations in environments with scarce food. Exerting external pressure we might observe evolution of the wild-type to the super-diffusive populations.

The role of assessment packages for diagnostic consultations: A conversation analytic perspective.

PubMed

Rossen, Camilla B; Buus, Niels; Stenager, Egon; Stenager, Elsebeth

2015-05-01

This article reports a conversation analysis of assessment package consultations. Healthcare delivery packages belong to a highly structured mode of healthcare delivery, in which specific courses of healthcare interventions related to assessment and treatment are predefined, both as to timing and content. Assessment packages are widely used in an increasing number of medical specialities; however, there is a lack of knowledge about how packaged assessment influences the interaction between doctor and patient. In this study, we investigate the final consultation in assessment packages, which is when the final clarification of the patient's symptoms takes place. The primary data of the study were eight audio recordings of consultations, and the secondary data were ethnographic field descriptions. In most consultations, packaged assessment was a resource as it provided fast and efficient clarification. In most cases, clarification was treated as good news since it either confirmed the absence of a serious disease or resulted in a diagnosis leading to relevant treatment offers. However, in some cases, clarification was not perceived as good news. This was the case in consultations with patients whose goal was to leave the consultation with clarification in the form of a definite diagnosis, but who were not offered such clarification. These patients negotiated the outcome of the consultation by applying implicit and explicit pressure, which induced the doctors to disregard the boundaries of the package and offer the patient more tests. The study highlights some of the problems related to introducing narrow, specialized package assessment. © The Author(s) 2014.

Manifestation of two-channel nonlocal spin transport in the shapes of Hanle curves

NASA Astrophysics Data System (ADS)

Roundy, R. C.; Prestgard, M. C.; Tiwari, A.; Mishchenko, E. G.; Raikh, M. E.

2014-09-01

The dynamics of charge-density fluctuations in a system of two tunnel-coupled wires contains two diffusion modes with dispersion iω =Dq2 and iω =Dq2+2/τt, where D is the diffusion coefficient and τt is the tunneling time between the wires. The dispersion of corresponding spin-density modes depends on magnetic field as a result of the spin precession with Larmour frequency ωL. The presence of two modes affects the shape of the Hanle curve describing the spin-dependent resistance R between the ferromagnetic strips covering the nonmagnetic wires. We demonstrate that the relative shapes of the R (ωL) curves, one measured within the same wire and the other measured between the wires, depends on the ratio τt/τs, where τs is the spin-diffusion time. If the coupling between the wires is local, i.e., only at the point x =0, then the difference of the shapes of intrawire and interwire Hanle curves reflects the difference in statistics of diffusive trajectories, which "switch" or do not switch near x =0. When one of the coupled wires is bent into a loop with a radius a, the shape of the Hanle curve reflects the statistics of random walks on the loop. This statistics is governed by the dimensionless parameter a /√Dτs .

ERTS-C (Landsat 3) cryogenic heat pipe experiment definition

NASA Technical Reports Server (NTRS)

Brennan, P. J.; Kroliczek, E. J.

1975-01-01

A flight experiment designed to demonstrate current cryogenic heat pipe technology was defined and evaluated. The experiment package developed is specifically configured for flight aboard an ERTS type spacecraft. Two types of heat pipes were included as part of the experiment package: a transporter heat pipe and a thermal diode heat pipe. Each was tested in various operating modes. Performance data obtained from the experiment are applicable to the design of cryogenic systems for detector cooling, including applications where periodic high cooler temperatures are experienced as a result of cyclic energy inputs.

Extensions to the instantaneous normal mode analysis of cluster dynamics: Diffusion constants and the role of rotations in clusters

NASA Astrophysics Data System (ADS)

Adams, John E.; Stratt, Richard M.

1990-08-01

For the instantaneous normal mode analysis method to be generally useful in studying the dynamics of clusters of arbitrary size, it ought to yield values of atomic self-diffusion constants which agree with those derived directly from molecular dynamics calculations. The present study proposes that such agreement indeed can be obtained if a sufficiently sophisticated formalism for computing the diffusion constant is adopted, such as the one suggested by Madan, Keyes, and Seeley [J. Chem. Phys. 92, 7565 (1990)]. In order to implement this particular formalism, however, we have found it necessary to pay particular attention to the removal from the computed spectra of spurious rotational contributions. The utility of the formalism is demonstrated via a study of small argon clusters, for which numerous results generated using other approaches are available. We find the same temperature dependence of the Ar13 self-diffusion constant that Beck and Marchioro [J. Chem. Phys. 93, 1347 (1990)] do from their direct calculation of the velocity autocorrelation function: The diffusion constant rises quickly from zero to a liquid-like value as the cluster goes through (the finite-size equivalent of) the melting transition.

Building 1D resonance broadened quasilinear (RBQ) code for fast ions Alfvénic relaxations

NASA Astrophysics Data System (ADS)

Gorelenkov, Nikolai; Duarte, Vinicius; Berk, Herbert

2016-10-01

The performance of the burning plasma is limited by the confinement of superalfvenic fusion products, e.g. alpha particles, which are capable of resonating with the Alfvénic eigenmodes (AEs). The effect of AEs on fast ions is evaluated using a resonance line broadened diffusion coefficient. The interaction of fast ions and AEs is captured for cases where there are either isolated or overlapping modes. A new code RBQ1D is being built which constructs diffusion coefficients based on realistic eigenfunctions that are determined by the ideal MHD code NOVA. The wave particle interaction can be reduced to one-dimensional dynamics where for the Alfvénic modes typically the particle kinetic energy is nearly constant. Hence to a good approximation the Quasi-Linear (QL) diffusion equation only contains derivatives in the angular momentum. The diffusion equation is then one dimensional that is efficiently solved simultaneously for all particles with the equation for the evolution of the wave angular momentum. The evolution of fast ion constants of motion is governed by the QL diffusion equations which are adapted to find the ion distribution function.

Extremely Low Frequency-Magnetic Field (ELF-MF) Exposure Characteristics among Semiconductor Workers

PubMed Central

Choi, Sangjun; Cha, Wonseok; Kim, Won; Yoon, Chungsik; Park, Ju-Hyun; Ha, Kwonchul; Park, Donguk

2018-01-01

We assessed the exposure of semiconductor workers to extremely low frequency-magnetic fields (ELF-MF) and identified job characteristics affecting ELF-MF exposure. These were demonstrated by assessing the exposure of 117 workers involved in wafer fabrication (fab) and chip packaging wearing personal dosimeters for a full shift. A portable device was used to monitor ELF-MF in high temporal resolution. All measurements were categorized by operation, job and working activity during working time. ELF-MF exposure of workers were classified based on the quartiles of ELF-MF distribution. The average levels of ELF-MF exposure were 0.56 µT for fab workers, 0.59 µT for chip packaging workers and 0.89 µT for electrical engineers, respectively. Exposure to ELF-MF differed among types of factory, operation, job and activity. Workers engaged in the diffusion and chip testing activities showed the highest ELF-MF exposure. The ELF-MF exposures of process operators were found to be higher than those of maintenance engineers, although peak exposure and/or patterns varied. The groups with the highest quartile ELF-MF exposure level are operators in diffusion, ion implantation, module and testing operations, and maintenance engineers in diffusion, module and testing operations. In conclusion, ELF-MF exposure among workers can be substantially affected by the type of operation and job, and the activity or location. PMID:29614730

Optical measurement of transverse molecular diffusion in a microchannel.

PubMed Central

Kamholz, A E; Schilling, E A; Yager, P

2001-01-01

Quantitative analysis of molecular diffusion is a necessity for the efficient design of most microfluidic devices as well as an important biophysical method in its own right. This study demonstrates the rapid measurement of diffusion coefficients of large and small molecules in a microfluidic device, the T-sensor, by means of conventional epifluorescence microscopy. Data were collected by monitoring the transverse flux of analyte from a sample stream into a second stream flowing alongside it. As indicated by the low Reynolds numbers of the system (< 1), flow is laminar, and molecular transport between streams occurs only by diffusion. Quantitative determinations were made by fitting data with predictions of a one-dimensional model. Analysis was made of the flow development and its effect on the distribution of diffusing analyte using a three-dimensional modeling software package. Diffusion coefficients were measured for four fluorescently labeled molecules: fluorescein-biotin, insulin, ovalbumin, and streptavidin. The resulting values differed from accepted results by an average of 2.4%. Microfluidic system parameters can be selected to achieve accurate diffusion coefficient measurements and to optimize other microfluidic devices that rely on precise transverse transport of molecules. PMID:11259309

Verification of component mode techniques for flexible multibody systems

NASA Technical Reports Server (NTRS)

Wiens, Gloria J.

1990-01-01

Investigations were conducted in the modeling aspects of flexible multibodies undergoing large angular displacements. Models were to be generated and analyzed through application of computer simulation packages employing the 'component mode synthesis' techniques. Multibody Modeling, Verification and Control Laboratory (MMVC) plan was implemented, which includes running experimental tests on flexible multibody test articles. From these tests, data was to be collected for later correlation and verification of the theoretical results predicted by the modeling and simulation process.

Vault Nanoparticles Packaged with Enzymes as an Efficient Pollutant Biodegradation Technology.

PubMed

Wang, Meng; Abad, Danny; Kickhoefer, Valerie A; Rome, Leonard H; Mahendra, Shaily

2015-11-24

Vault nanoparticles packaged with enzymes were synthesized as agents for efficiently degrading environmental contaminants. Enzymatic biodegradation is an attractive technology for in situ cleanup of contaminated environments because enzyme-catalyzed reactions are not constrained by nutrient requirements for microbial growth and often have higher biodegradation rates. However, the limited stability of extracellular enzymes remains a major challenge for practical applications. Encapsulation is a recognized method to enhance enzymatic stability, but it can increase substrate diffusion resistance, lower catalytic rates, and increase the apparent half-saturation constants. Here, we report an effective approach for boosting enzymatic stability by single-step packaging into vault nanoparticles. With hollow core structures, assembled vault nanoparticles can simultaneously contain multiple enzymes. Manganese peroxidase (MnP), which is widely used in biodegradation of organic contaminants, was chosen as a model enzyme in the present study. MnP was incorporated into vaults via fusion to a packaging domain called INT, which strongly interacts with vaults' interior surface. MnP fused to INT and vaults packaged with the MnP-INT fusion protein maintained peroxidase activity. Furthermore, MnP-INT packaged in vaults displayed stability significantly higher than that of free MnP-INT, with slightly increased Km value. Additionally, vault-packaged MnP-INT exhibited 3 times higher phenol biodegradation in 24 h than did unpackaged MnP-INT. These results indicate that the packaging of MnP enzymes in vault nanoparticles extends their stability without compromising catalytic activity. This research will serve as the foundation for the development of efficient and sustainable vault-based bioremediation approaches for removing multiple contaminants from drinking water and groundwater.

Long-term lumen depreciation behavior and failure modes of multi-die array LEDs

NASA Astrophysics Data System (ADS)

Jayawardena, Asiri; Marcus, Daniel; Prugue, Ximena; Narendran, Nadarajah

2013-09-01

One of the main advantages of multi-die array light-emitting diodes (LEDs) is their high flux density. However, a challenge for using such a product in lighting fixture applications is the heat density and the need for thermal management to keep the junction temperatures of all the dies low for long-term reliable performance. Ten multi-die LED array samples for each product from four different manufacturers were subjected to lumen maintenance testing (as described in IES-LM-80-08), and their resulting lumen depreciation and failure modes were studied. The products were tested at the maximum case (or pin) temperature reported by the respective manufacturer by appropriately powering the LEDs. In addition, three samples for each product from two different manufacturers were subjected to rapid thermal cycling, and the resulting lumen depreciation and failure modes were studied. The results showed that the exponential lumen decay model using long-term lumen maintenance data as recommended in IES TM-21 does not fit for all package types. The failure of a string of dies and single die failure in a string were observed in some of the packages.

Optimization of transonic wind tunnel data acquisition and control systems for providing continuous mode tests

NASA Astrophysics Data System (ADS)

Petronevich, V. V.

2016-10-01

The paper observes the issues related to the increase of efficiency and information content of experimental research in transonic wind tunnels (WT). In particular, questions of optimizing the WT Data Acquisition and Control Systems (DACS) to provide the continuous mode test method are discussed. The problem of Mach number (M number) stabilization in the test section of the large transonic compressor-type wind tunnels at subsonic flow conditions with continuous change of the aircraft model angle of attack is observed on the example of T-128 wind tunnel. To minimize the signals distortion in T-128 DACS measurement channels the optimal MGCplus filter settings of the data acquisition system used in T-128 wind tunnel to measure loads were experimentally determined. As a result of the tests performed a good agreement of the results of balance measurements for pitch/pause and continuous test modes was obtained. Carrying out balance tests for pitch/pause and continuous test methods was provided by the regular data acquisition and control system of T-128 wind tunnel with unified software package POTOK. The architecture and functional abilities of POTOK software package are observed.

Two distinct modes of metal ion binding in the nuclease active site of a viral DNA-packaging terminase: insight into the two-metal-ion catalytic mechanism

PubMed Central

Zhao, Haiyan; Lin, Zihan; Lynn, Anna Y.; Varnado, Brittany; Beutler, John A.; Murelli, Ryan P.; Le Grice, Stuart F. J.; Tang, Liang

2015-01-01

Many dsDNA viruses encode DNA-packaging terminases, each containing a nuclease domain that resolves concatemeric DNA into genome-length units. Terminase nucleases resemble the RNase H-superfamily nucleotidyltransferases in folds, and share a two-metal-ion catalytic mechanism. Here we show that residue K428 of a bacteriophage terminase gp2 nuclease domain mediates binding of the metal cofactor Mg2+. A K428A mutation allows visualization, at high resolution, of a metal ion binding mode with a coupled-octahedral configuration at the active site, exhibiting an unusually short metal-metal distance of 2.42 Å. Such proximity of the two metal ions may play an essential role in catalysis by generating a highly positive electrostatic niche to enable formation of the negatively charged pentacovalent phosphate transition state, and provides the structural basis for distinguishing Mg2+ from Ca2+. Using a metal ion chelator β-thujaplicinol as a molecular probe, we observed a second mode of metal ion binding at the active site, mimicking the DNA binding state. Arrangement of the active site residues differs drastically from those in RNase H-like nucleases, suggesting a drifting of the active site configuration during evolution. The two distinct metal ion binding modes unveiled mechanistic details of the two-metal-ion catalysis at atomic resolution. PMID:26450964

Application of the Finite Elemental Analysis to Modeling Temperature Change of the Vaccine in an Insulated Packaging Container during Transport.

PubMed

Ge, Changfeng; Cheng, Yujie; Shen, Yan

2013-01-01

This study demonstrated an attempt to predict temperatures of a perishable product such as vaccine inside an insulated packaging container during transport through finite element analysis (FEA) modeling. In order to use the standard FEA software for simulation, an equivalent heat conduction coefficient is proposed and calculated to describe the heat transfer of the air trapped inside the insulated packaging container. The three-dimensional, insulated packaging container is regarded as a combination of six panels, and the heat flow at each side panel is a one-dimension diffusion process. The transit-thermal analysis was applied to simulate the heat transition process from ambient environment to inside the container. Field measurements were carried out to collect the temperature during transport, and the collected data were compared to the FEA simulation results. Insulated packaging containers are used to transport temperature-sensitive products such as vaccine and other pharmaceutical products. The container is usually made of an extruded polystyrene foam filled with gel packs. World Health Organization guidelines recommend that all vaccines except oral polio vaccine be distributed in an environment where the temperature ranges between +2 to +8 °C. The primary areas of concern in designing the packaging for vaccine are how much of the foam thickness and gel packs should be used in order to keep the temperature in a desired range, and how to prevent the vaccine from exposure to freezing temperatures. This study uses numerical simulation to predict temperature change within an insulated packaging container in vaccine cold chain. It is our hope that this simulation will provide the vaccine industries with an alternative engineering tool to validate vaccine packaging and project thermal equilibrium within the insulated packaging container.

A Simple Molecular Dynamics Lab to Calculate Viscosity as a Function of Temperature

ERIC Educational Resources Information Center

Eckler, Logan H.; Nee, Matthew J.

2016-01-01

A simple molecular dynamics experiment is described to demonstrate transport properties for the undergraduate physical chemistry laboratory. The AMBER package is used to monitor self-diffusion in "n"-hexane. Scripts (available in the Supporting Information) make the process considerably easier for students, allowing them to focus on the…

Detailed Wave Function Analysis for Multireference Methods: Implementation in the Molcas Program Package and Applications to Tetracene.

PubMed

Plasser, Felix; Mewes, Stefanie A; Dreuw, Andreas; González, Leticia

2017-11-14

High-level multireference computations on electronically excited and charged states of tetracene are performed, and the results are analyzed using an extensive wave function analysis toolbox that has been newly implemented in the Molcas program package. Aside from verifying the strong effect of dynamic correlation, this study reveals an unexpected critical influence of the atomic orbital basis set. It is shown that different polarized double-ζ basis sets produce significantly different results for energies, densities, and overall wave functions, with the best performance obtained for the atomic natural orbital (ANO) basis set by Pierloot et al. Strikingly, the ANO basis set not only reproduces the energies but also performs exceptionally well in terms of describing the diffuseness of the different states and of their attachment/detachment densities. This study, thus, not only underlines the fact that diffuse basis functions are needed for an accurate description of the electronic wave functions but also shows that, at least for the present example, it is enough to include them implicitly in the contraction scheme.

Multiple Mode Actuation of a Turbulent Jet

NASA Technical Reports Server (NTRS)

Pack, LaTunia G.; Seifert, Avi

2001-01-01

The effects of multiple mode periodic excitation on the evolution of a circular turbulent jet were studied experimentally. A short, wide-angle diffuser was attached to the jet exit. Streamwise and cross-stream excitations were introduced at the junction between the jet exit and the diffuser inlet on opposing sides of the jet. The introduction of high amplitude, periodic excitation in the streamwise direction enhances the mixing and promotes attachment of the jet shear-layer to the diffuser wall. Cross-stream excitation applied over a fraction of the jet circumference can deflect the jet away from the excitation slot. The two modes of excitation were combined using identical frequencies and varying the relative phase between the two actuators in search of an optimal response. It is shown that, for low and moderate periodic momentum input levels, the jet deflection angles depend strongly on the relative phase between the two actuators. Optimum performance is achieved when the phase difference is pi +/- pi/6. The lower effectiveness of the equal phase excitation is attributed to the generation of an azimuthally symmetric mode that does not produce the required non-axisymmetric vectoring. For high excitation levels, identical phase becomes more effective, while phase sensitivity decreases. An important finding was that with proper phase tuning, two unsteady actuators can be combined to obtain a non-linear response greater than the superposition of the individual effects.

The feasibility of thermal and compositional convection in Earth's inner core

NASA Astrophysics Data System (ADS)

Lythgoe, Karen H.; Rudge, John F.; Neufeld, Jerome A.; Deuss, Arwen

2015-05-01

Inner core convection, and the corresponding variations in grain size and alignment, has been proposed to explain the complex seismic structure of the inner core, including its anisotropy, lateral variations and the F-layer at the base of the outer core. We develop a parametrized convection model to investigate the possibility of convection in the inner core, focusing on the dominance of the plume mode of convection versus the translation mode. We investigate thermal and compositional convection separately so as to study the end-members of the system. In the thermal case the dominant mode of convection is strongly dependent on the viscosity of the inner core, the magnitude of which is poorly constrained. Furthermore recent estimates of a large core thermal conductivity result in stable thermal stratification, hindering convection. However, an unstable density stratification may arise due to the pressure dependant partition coefficient of certain light elements. We show that this unstable stratification leads to compositionally driven convection, and that inner core translation is likely to be the dominant convective mode due to the low compositional diffusivity. The style of convection resulting from a combination of both thermal and compositional effects is not easy to understand. For reasonable parameter estimates, the stabilizing thermal buoyancy is greater than the destabilizing compositional buoyancy. However we anticipate complex double diffusive processes to occur given the very different thermal and compositional diffusivities.

The Feasibility of Thermal and Compositional Convection in Earth's Inner Core

NASA Astrophysics Data System (ADS)

Lythgoe, K.; Rudge, J. F.; Neufeld, J. A.; Deuss, A. F.

2014-12-01

Inner core convection, and the corresponding variations in grain size and alignment, has been proposed to explain the complex seismic structure of the inner core, including its anisotropy, lateral variations and the F-layer at the base of the outer core. We develop a parameterised convection model to investigate the possibility of convection in the inner core, focusing on the dominance of the plume mode of convection versus the translation mode. We investigate thermal and compositional convection separately so as to study the end-members of the system. In the thermal case the dominant mode of convection is strongly dependent on the viscosity of the inner core, the magnitude of which is poorly constrained. Furthermore recent estimates of a large core thermal conductivity result in stable thermal stratification, hindering convection. However, an unstable density stratification may arise due to the pressure dependant partition coefficient of certain light elements. We show that this unstable stratification leads to compositionally driven convection, and that inner core translation is likely to be the dominant convective mode due to the low compositional diffusivity. The style of convection resulting from a combination of both thermal and compositional effects is not easy to understand. The stabilising thermal buoyancy is greater than the destabilising compositional buoyancy, however we anticipate complex double diffusive processes to occur given the very different thermal and compositional diffusivities and more work is needed to understand these processes.

λ-Repressor Oligomerization Kinetics at High Concentrations Using Fluorescence Correlation Spectroscopy in Zero-Mode Waveguides

PubMed Central

Samiee, K. T.; Foquet, M.; Guo, L.; Cox, E. C.; Craighead, H. G.

2005-01-01

Fluorescence correlation spectroscopy (FCS) has demonstrated its utility for measuring transport properties and kinetics at low fluorophore concentrations. In this article, we demonstrate that simple optical nanostructures, known as zero-mode waveguides, can be used to significantly reduce the FCS observation volume. This, in turn, allows FCS to be applied to solutions with significantly higher fluorophore concentrations. We derive an empirical FCS model accounting for one-dimensional diffusion in a finite tube with a simple exponential observation profile. This technique is used to measure the oligomerization of the bacteriophage λ repressor protein at micromolar concentrations. The results agree with previous studies utilizing conventional techniques. Additionally, we demonstrate that the zero-mode waveguides can be used to assay biological activity by measuring changes in diffusion constant as a result of ligand binding. PMID:15613638

QMCPACK: an open source ab initio quantum Monte Carlo package for the electronic structure of atoms, molecules and solids

NASA Astrophysics Data System (ADS)

Kim, Jeongnim; Baczewski, Andrew D.; Beaudet, Todd D.; Benali, Anouar; Chandler Bennett, M.; Berrill, Mark A.; Blunt, Nick S.; Josué Landinez Borda, Edgar; Casula, Michele; Ceperley, David M.; Chiesa, Simone; Clark, Bryan K.; Clay, Raymond C., III; Delaney, Kris T.; Dewing, Mark; Esler, Kenneth P.; Hao, Hongxia; Heinonen, Olle; Kent, Paul R. C.; Krogel, Jaron T.; Kylänpää, Ilkka; Li, Ying Wai; Lopez, M. Graham; Luo, Ye; Malone, Fionn D.; Martin, Richard M.; Mathuriya, Amrita; McMinis, Jeremy; Melton, Cody A.; Mitas, Lubos; Morales, Miguel A.; Neuscamman, Eric; Parker, William D.; Pineda Flores, Sergio D.; Romero, Nichols A.; Rubenstein, Brenda M.; Shea, Jacqueline A. R.; Shin, Hyeondeok; Shulenburger, Luke; Tillack, Andreas F.; Townsend, Joshua P.; Tubman, Norm M.; Van Der Goetz, Brett; Vincent, Jordan E.; ChangMo Yang, D.; Yang, Yubo; Zhang, Shuai; Zhao, Luning

2018-05-01

QMCPACK is an open source quantum Monte Carlo package for ab initio electronic structure calculations. It supports calculations of metallic and insulating solids, molecules, atoms, and some model Hamiltonians. Implemented real space quantum Monte Carlo algorithms include variational, diffusion, and reptation Monte Carlo. QMCPACK uses Slater–Jastrow type trial wavefunctions in conjunction with a sophisticated optimizer capable of optimizing tens of thousands of parameters. The orbital space auxiliary-field quantum Monte Carlo method is also implemented, enabling cross validation between different highly accurate methods. The code is specifically optimized for calculations with large numbers of electrons on the latest high performance computing architectures, including multicore central processing unit and graphical processing unit systems. We detail the program’s capabilities, outline its structure, and give examples of its use in current research calculations. The package is available at http://qmcpack.org.

QMCPACK: an open source ab initio quantum Monte Carlo package for the electronic structure of atoms, molecules and solids.

PubMed

Kim, Jeongnim; Baczewski, Andrew T; Beaudet, Todd D; Benali, Anouar; Bennett, M Chandler; Berrill, Mark A; Blunt, Nick S; Borda, Edgar Josué Landinez; Casula, Michele; Ceperley, David M; Chiesa, Simone; Clark, Bryan K; Clay, Raymond C; Delaney, Kris T; Dewing, Mark; Esler, Kenneth P; Hao, Hongxia; Heinonen, Olle; Kent, Paul R C; Krogel, Jaron T; Kylänpää, Ilkka; Li, Ying Wai; Lopez, M Graham; Luo, Ye; Malone, Fionn D; Martin, Richard M; Mathuriya, Amrita; McMinis, Jeremy; Melton, Cody A; Mitas, Lubos; Morales, Miguel A; Neuscamman, Eric; Parker, William D; Pineda Flores, Sergio D; Romero, Nichols A; Rubenstein, Brenda M; Shea, Jacqueline A R; Shin, Hyeondeok; Shulenburger, Luke; Tillack, Andreas F; Townsend, Joshua P; Tubman, Norm M; Van Der Goetz, Brett; Vincent, Jordan E; Yang, D ChangMo; Yang, Yubo; Zhang, Shuai; Zhao, Luning

2018-05-16

QMCPACK is an open source quantum Monte Carlo package for ab initio electronic structure calculations. It supports calculations of metallic and insulating solids, molecules, atoms, and some model Hamiltonians. Implemented real space quantum Monte Carlo algorithms include variational, diffusion, and reptation Monte Carlo. QMCPACK uses Slater-Jastrow type trial wavefunctions in conjunction with a sophisticated optimizer capable of optimizing tens of thousands of parameters. The orbital space auxiliary-field quantum Monte Carlo method is also implemented, enabling cross validation between different highly accurate methods. The code is specifically optimized for calculations with large numbers of electrons on the latest high performance computing architectures, including multicore central processing unit and graphical processing unit systems. We detail the program's capabilities, outline its structure, and give examples of its use in current research calculations. The package is available at http://qmcpack.org.

77 FR 49861 - Notice of Application for Special Permits

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-17

.... transportation in commerce of certain Radioactive material in alternative packaging by highway. (mode 1). 15671-N... DEPARTMENT OF TRANSPORTATION Pipeline and Hazardous Materials Safety Administration Notice of Application for Special Permits AGENCY: Pipeline and Hazardous Materials Safety Administration (PHMSA), DOT...

A new vector radiative transfer model as a part of SCIATRAN 3.0 software package.

NASA Astrophysics Data System (ADS)

Rozanov, Alexei; Rozanov, Vladimir; Burrows, John P.

The SCIATRAN 3.0 package is a result of further development of the SCIATRAN 2.x software family which, similar to previous versions, comprises a radiative transfer model and a retrieval block. A major improvement was achieved in comparison to previous software versions by adding the vector mode to the radiative transfer model. Thus, the well-established Discrete Ordinate solver can now be run in the vector mode to calculate the scattered solar radiation including polarization, i.e., to simulate all four components of the Stockes vector. Similar to the scalar version, the simulations can be performed for any viewing geometry typical for atmospheric observations in the UV-Vis-NIR spectral range (nadir, limb, off-axis, etc.) as well as for any observer position within or outside the Earth's atmosphere. Similar to the precursor version, the new model is freely available for non-commercial use via the web page of the University of Bremen. In this presentation a short description of the software package, especially of the new vector radiative transfer model will be given, including remarks on the availability for the scientific community. Furthermore, comparisons to other vector models will be shown and some example problems will be considered where the polarization of the observed radiation must be accounted for to obtain high quality results.

Application of screened Coulomb potential in fitting DBV star PG 0112+104

NASA Astrophysics Data System (ADS)

Chen, Y. H.

2018-03-01

With 78.7 d of observations for PG 0112+104, a pulsating DB star, from Campaign 8 of Kepler 2 mission, Hermes et al. made a detailed mode identification. A reliable mode identification, with 5 l = 1 modes, 3 l = 2 modes, and 3 l = 1 or 2 modes, was identified. Grids of DBV star models are evolved by WDEC with element diffusion effect of pure Coulomb potential and screened Coulomb potential. Fitting the identified modes of PG 0112+104 by the calculated ones, we studied the difference of element diffusion effect between adopting pure Coulomb potential and screened Coulomb potential. Our aim is to reduce the fitting error by studying new input physics. The starting models including their chemical composition profile are from white dwarf models evolved by MESA. They were calculated following the stellar evolution from the main sequence to the start of the white dwarf cooling sequences. The optimal parameters are basically consistent with that of previous spectroscopic and asteroseismological studies. The pure and screened Coulomb potential lead to different composition profiles of the C/O-He interface area. High k modes are very sensitive to the area. However, most of the observed modes for PG 0112+104 are low k modes. The σRMS taking the screened Coulomb potential is reduced by 4 per cent compared with taking the pure Coulomb potential when fitting the identified low k modes of PG 0112+104. Fitting the Kepler 2 data with our models improved the σRMS of the fit by 27 per cent.

Decentralized control experiments on the JPL flexible spacecraft

NASA Technical Reports Server (NTRS)

Ozguner, U.; Ossman, K.; Donne, J.; Boesch, M.; Ahmed, A.

1990-01-01

Decentralized control experiments were successfully demonstrated for the JPL/AFAL Flexible Structure. A simulation package using MATRIXx showed strong correlation between the simulations and experimental result, while providing a means for test and debug of the various control strategies. Implementation was simplified by a modular software design that was easily transported from the simulation environment to the experimental environment. Control designs worked well for suppression of the dominant modes of the structure. Static decentralized output feedback dampened the excited modes of the structure, but sometimes excited higher order modes upon startup of the controller. A second-order frequency shaping controller helped to eliminate excitation of the higher order modes by attenuating high frequencies in the control effort. However, it also resulted in slightly longer settling times.

Banded Structures in Electron Pitch Angle Diffusion Coefficients from Resonant Wave Particle Interactions

NASA Technical Reports Server (NTRS)

Tripathi, A. K.; Singhal, R. P.; Khazanov, G. V.; Avanov, L. A.

2016-01-01

Electron pitch angle (D (alpha)) and momentum (D(pp)) diffusion coefficients have been calculated due to resonant interactions with electrostatic electron cyclotron harmonic (ECH) and whistler mode chorus waves. Calculations have been performed at two spatial locations L = 4.6 and 6.8 for electron energies 10 keV. Landau (n = 0) resonance and cyclotron harmonic resonances n = +/-1, +/-2,...+/-5 have been included in the calculations. It is found that diffusion coefficient versus pitch angle (alpha) profiles show large dips and oscillations or banded structures. The structures are more pronounced for ECH and lower band chorus (LBC) and particularly at location 4.6. Calculations of diffusion coefficients have also been performed for individual resonances. It is noticed that the main contribution of ECH waves in pitch angle diffusion coefficient is due to resonances n = +1 and n = +2. A major contribution to momentum diffusion coefficients appears from n = +2. However, the banded structures in D alpha and Dpp coefficients appear only in the profile of diffusion coefficients for n = +2. The contribution of other resonances to diffusion coefficients is found to be, in general, quite small or even negligible. For LBC and upper band chorus waves, the banded structures appear only in Landau resonance. The Dpp diffusion coefficient for ECH waves is one to two orders smaller than D alpha coefficients. For chorus waves, Dpp coefficients are about an order of magnitude smaller than D alpha coefficients for the case n does not = 0. In case of Landau resonance, the values of Dpp coefficient are generally larger than the values of D alpha coefficients particularly at lower energies. As an aid to the interpretation of results, we have also determined the resonant frequencies. For ECH waves, resonant frequencies have been estimated for wave normal angle 89 deg and harmonic resonances n = +1, +2, and +3, whereas for whistler mode waves, the frequencies have been calculated for angle 10 deg and Landau resonance. Further, in ECH waves, the banded structures appear for electron energies (is) greater than1 keV, and for whistler mode chorus waves, structures appear for energies greater than 2 keV at L = 4.6 and above 200 eV for L = 6.8. The results obtained in the present work will be helpful in the study of diffusion curves and will have important consequences for diffuse aurora and pancake distributions.

Banded Structures in Electron Pitch Angle Diffusion Coefficients from Resonant Wave-Particle Interactions

NASA Technical Reports Server (NTRS)

Tripathi, A. K.; Singhal, R. P.; Khazanov, G. V.; Avanov, L. A.

2016-01-01

Electron pitch angle (D(sub (alpha alpha))) and momentum (D(sub pp)) diffusion coefficients have been calculated due to resonant interactions with electrostatic electron cyclotron harmonic (ECH) and whistler mode chorus waves. Calculations have been performed at two spatial locations L=4.6 and 6.8 for electron energies less than or equal to 10 keV. Landau (n=0) resonance and cyclotron harmonic resonances n= +/- 1, +/-2, ... +/-5 have been included in the calculations. It is found that diffusion coefficient versus pitch angle (alpha) profiles show large dips and oscillations or banded structures. The structures are more pronounced for ECH and lower band chorus (LBC) and particularly at location 4.6. Calculations of diffusion coefficients have also been performed for individual resonances. It is noticed that the main contribution of ECH waves in pitch angle diffusion coefficient is due to resonances n=+1 and n=+2. A major contribution to momentum diffusion coefficients appears from n=+2. However, the banded structures in D(sub alpha alpha) and D(sub pp) coefficients appear only in the profile of diffusion coefficients for n=+2. The contribution of other resonances to diffusion coefficients is found to be, in general, quite small or even negligible. For LBC and upper band chorus waves, the banded structures appear only in Landau resonance. The D(sub pp) diffusion coefficient for ECH waves is one to two orders smaller than D(sub alpha alpha) coefficients. For chorus waves, D(sub pp) coefficients are about an order of magnitude smaller than D(sub alpha alpha) coefficients for the case n does not equal 0. In case of Landau resonance, the values of D(sub pp) coefficient are generally larger than the values of D(sub alpha alpha) coefficients particularly at lower energies. As an aid to the interpretation of results, we have also determined the resonant frequencies. For ECH waves, resonant frequencies have been estimated for wave normal angle 89 deg and harmonic resonances n= +1, +2, and +3, whereas for whistler mode waves, the frequencies have been calculated for angle 10 deg and Landau resonance. Further, in ECH waves, the banded structures appear for electron energies 1 greater than or equal to keV, and for whistler mode chorus waves, structures appear for energies greater than 2 keV at L=4.6 and above 200 eV for L=6.8. The results obtained in the present work will be helpful in the study of diffusion curves and will have important consequences for diffuse aurora and pancake distributions.

Mechanisms of the Diffusion of Nonpolar Substances in a Hydrophilic Ionic Liquid

NASA Astrophysics Data System (ADS)

Atamas', N. A.

2018-01-01

The structural-dynamic features of ionic liquid-nonpolar substance systems are studied by means of molecular dynamics using Frenkel's fundamental theory of a liquid and the phonon theory of the thermodynamics of a liquid, in combination with the DL_POLY_4.05 software package. Argon, methane, and benzene molecules serve as the dissolved substances. Model concepts are proposed and analyzed to describe the diffusion of molecules of a dissolved substance in an ionic liquid. It is shown that an increase in the mass of the molecules of a dissolved nonpolar substance correlates with their mobility in a hydrophilic ionic liquid (IL). This determines the diffusion of the components of dmim+/Cl- IL solutions and is responsible for the anomalous behavior of the solubility of nonpolar substances in them.

Numerical simulation of gas distribution in goaf under Y ventilation mode

NASA Astrophysics Data System (ADS)

Li, Shengzhou; Liu, Jun

2018-04-01

Taking the Y type ventilation of the working face as the research object, diffusion equation is introduced to simulate the diffusion characteristics of gas, using Navier-Stokes equation and Brinkman equation to simulate the gas flow in working face and goaf, the physical model of gas flow in coal mining face was established. With numerical simulation software COMSOL multiphysics methods, gas distribution in goaf under Y ventilation mode is simulated and gas distribution of the working face, the upper corner and goaf is analysised. The results show that the Y type ventilation system can effectively improve the corner gas accumulation and overrun problem.

Stability of wave processes in a rotating electrically conducting fluid

NASA Astrophysics Data System (ADS)

Peregudin, S. I.; Peregudina, E. S.; Kholodova, S. E.

2018-05-01

The paper puts forward a mathematical model of dynamics of spatial large-scale motions in a rotating layer of electrically conducting incompressible perfect fluid of variable depth with due account of dissipative effects. The resulting boundary-value problem is reduced to a vector system of partial differential equations for any values of the Reynolds number. Theoretical analysis of the so-obtained analytical solution reveals the effect of the magnetic field diffusion on the stability of the wave mode — namely, with the removed external magnetic field, the diffusion of the magnetic field promotes its damping. Besides, a criterion of stability of a wave mode is obtained.

Divergent series and memory of the initial condition in the long-time solution of some anomalous diffusion problems.

PubMed

Yuste, S Bravo; Borrego, R; Abad, E

2010-02-01

We consider various anomalous d -dimensional diffusion problems in the presence of an absorbing boundary with radial symmetry. The motion of particles is described by a fractional diffusion equation. Their mean-square displacement is given by r(2) proportional, variant t(gamma)(00 , the emergence of such series in the long-time domain is a specific feature of subdiffusion problems. We present a method to regularize such series, and, in some cases, validate the procedure by using alternative techniques (Laplace transform method and numerical simulations). In the normal diffusion case, we find that the signature of the initial condition on the approach to the steady state rapidly fades away and the solution approaches a single (the main) decay mode in the long-time regime. In remarkable contrast, long-time memory of the initial condition is present in the subdiffusive case as the spatial part Psi1(r) describing the long-time decay of the solution to the steady state is determined by a weighted superposition of all spatial modes characteristic of the normal diffusion problem, the weight being dependent on the initial condition. Interestingly, Psi1(r) turns out to be independent of the anomalous diffusion exponent gamma .

Stabilization of aroma compounds through sorption-release by packaging polymers.

PubMed

Reynier, Alain; Dole, Patrice; Fricoteaux, Florence; Saillard, Philippe; Feigenbaum, Alexandre E

2004-09-08

Plastic packaging materials are often associated to aroma losses and to a decrease of the organoleptic quality of foods. This work defines situations where, on the contrary, plastics play a regulating role on the concentration of reactive aroma compounds in foods. These systems can be described by a two step mechanism; first, aroma is sorbed in the polymer, while the fraction in solution degrades quickly; in a second step, as the concentration is close to zero in the solution, the polymer liberates progressively the sorbed aroma back to the food. A simple numerical model is proposed, describing competitive processes of aroma degradation in solution and sorption by a polymer in contact with a homogeneous aqueous food. The classical limonene/low density polyethylene (LDPE) system is studied experimentally for the validation of the model: in an acidic medium, limonene both degrades quickly and is sorbed quickly, with a large solubility in LDPE. To define which aroma packaging systems could also display this interesting behavior, all types of possible interactions, using thermodynamic and kinetic parameters describing most practical situations, are simulated. For that purpose, 35 values of reference diffusion coefficients and 35 partition coefficients of usual aroma compounds between polymers and water have been measured and combined with the few available data from literature. The situations where polymers regulate the aroma concentration in food correspond to large partition coefficients (above 10), large diffusion coefficients (>10(-9) cm2 x s(-1)), and large degradation constants.

Transport properties of NSTX-U L- and H-mode plasmas

NASA Astrophysics Data System (ADS)

Kaye, Stanley; Guttenfelder, Walter; Bell, Ron; Diallo, Ahmed; Leblanc, Ben; Podesta, Mario

2016-10-01

The confinement and transport properties of L- and H-mode plasmas in NSTX-U has been studied using the TRANSP code. A dedicated series of L-mode discharges was obtained to study the dependence of confinement and transport on power level and beam aiming angle. The latter is made possible by having two beamlines with 3 sources each, capable of injecting with tangency radii from Rtan = 50 to 130 cm (Rgeo = 92 cm). L-mode plasmas typically have confinement enhancement factors with H98y,2 =0.6 to 0.65, exhibiting a 25% decrease in confinement time as the beam power is raised from 1 to 3 MW. Associated with this is an increase in the electron thermal diffusivity in the core of the plasma from 3.5 to 10 m2/s. Electron thermal transport is the dominant energy loss channel in these plasmas. H-mode plasmas exhibit improved confinement, with H98y,2 =1 or above, and core electron thermal diffusivity values <1 m2/s. Details of these studies will be presented, along with the results of the beam tangency radius scan in L-mode plasmas. This research was supported by the U.S. Department of Energy contract # DE-AC02-09CH11466.

Multiple periodicities in the solar magnetic field - Possible origin in a multiple-mode solar dynamo

NASA Technical Reports Server (NTRS)

Boyer, D. W.; Levy, E. H.

1992-01-01

The solar magnetic field is generated in an oscillatory mode with a 22 yr full period and gives rise to the 11 yr sunspot cycle. However, analyses of contemporary solar records, as well as other surrogate indicators of solar activity, suggest the presence also of longer term periodicities in the solar magnetic cycle. This paper suggests that the solar dynamo can operate in a multiply periodic state, with several periodicites being generated simultaneously at different depths in the convection zone. A simple two-layer model of the solar convection zone is used to illustrate the physical mechanism of spatially localized, multiple-periodicity-mode dynamo regeneration. The two layers are characterized by differences in their respective turbulent magnetic diffusivities. Although the magnetic modes interact with one another, each mode is produced large in one layer or the other, and has an oscillation period approximately equal to the time characteristic of magnetic diffusion across the layer. The observed complicated periodicity pattern in the solar magnetic field could be a combination of two (or more) dynamo modes generated in this manner. The calculations are carried out using a differential rotation model consistent with recent helioseismological measurements, illustrating the challenge to dynamo theory raised by those observational results.

Logarithmic Superdiffusion in Two Dimensional Driven Lattice Gases

NASA Astrophysics Data System (ADS)

Krug, J.; Neiss, R. A.; Schadschneider, A.; Schmidt, J.

2018-03-01

The spreading of density fluctuations in two-dimensional driven diffusive systems is marginally anomalous. Mode coupling theory predicts that the diffusivity in the direction of the drive diverges with time as (ln t)^{2/3} with a prefactor depending on the macroscopic current-density relation and the diffusion tensor of the fluctuating hydrodynamic field equation. Here we present the first numerical verification of this behavior for a particular version of the two-dimensional asymmetric exclusion process. Particles jump strictly asymmetrically along one of the lattice directions and symmetrically along the other, and an anisotropy parameter p governs the ratio between the two rates. Using a novel massively parallel coupling algorithm that strongly reduces the fluctuations in the numerical estimate of the two-point correlation function, we are able to accurately determine the exponent of the logarithmic correction. In addition, the variation of the prefactor with p provides a stringent test of mode coupling theory.

Validation of nonlinear gyrokinetic simulations of L- and I-mode plasmas on Alcator C-Mod

DOE Office of Scientific and Technical Information (OSTI.GOV)

Creely, A. J.; Howard, N. T.; Rodriguez-Fernandez, P.

New validation of global, nonlinear, ion-scale gyrokinetic simulations (GYRO) is carried out for L- and I-mode plasmas on Alcator C-Mod, utilizing heat fluxes, profile stiffness, and temperature fluctuations. Previous work at C-Mod found that ITG/TEM-scale GYRO simulations can match both electron and ion heat fluxes within error bars in I-mode [White PoP 2015], suggesting that multi-scale (cross-scale coupling) effects [Howard PoP 2016] may be less important in I-mode than in L-mode. New results presented here, however, show that global, nonlinear, ion-scale GYRO simulations are able to match the experimental ion heat flux, but underpredict electron heat flux (at most radii),more » electron temperature fluctuations, and perturbative thermal diffusivity in both L- and I-mode. Linear addition of electron heat flux from electron scale runs does not resolve this discrepancy. These results indicate that single-scale simulations do not sufficiently describe the I-mode core transport, and that multi-scale (coupled electron- and ion-scale) transport models are needed. In conclusion a preliminary investigation with multi-scale TGLF, however, was unable to resolve the discrepancy between ion-scale GYRO and experimental electron heat fluxes and perturbative diffusivity, motivating further work with multi-scale GYRO simulations and a more comprehensive study with multi-scale TGLF.« less

Validation of nonlinear gyrokinetic simulations of L- and I-mode plasmas on Alcator C-Mod

DOE PAGES

Creely, A. J.; Howard, N. T.; Rodriguez-Fernandez, P.; ...

2017-03-02

New validation of global, nonlinear, ion-scale gyrokinetic simulations (GYRO) is carried out for L- and I-mode plasmas on Alcator C-Mod, utilizing heat fluxes, profile stiffness, and temperature fluctuations. Previous work at C-Mod found that ITG/TEM-scale GYRO simulations can match both electron and ion heat fluxes within error bars in I-mode [White PoP 2015], suggesting that multi-scale (cross-scale coupling) effects [Howard PoP 2016] may be less important in I-mode than in L-mode. New results presented here, however, show that global, nonlinear, ion-scale GYRO simulations are able to match the experimental ion heat flux, but underpredict electron heat flux (at most radii),more » electron temperature fluctuations, and perturbative thermal diffusivity in both L- and I-mode. Linear addition of electron heat flux from electron scale runs does not resolve this discrepancy. These results indicate that single-scale simulations do not sufficiently describe the I-mode core transport, and that multi-scale (coupled electron- and ion-scale) transport models are needed. In conclusion a preliminary investigation with multi-scale TGLF, however, was unable to resolve the discrepancy between ion-scale GYRO and experimental electron heat fluxes and perturbative diffusivity, motivating further work with multi-scale GYRO simulations and a more comprehensive study with multi-scale TGLF.« less

Novel approaches to increasing the brightness of broad area lasers

NASA Astrophysics Data System (ADS)

Crump, P.; Winterfeldt, M.; Decker, J.; Ekterai, M.; Fricke, J.; Knigge, S.; Maaßdorf, A.; Erbert, G.

2016-03-01

Progress in studies to increase the lateral brightness Blat of broad area lasers is reviewed. Blat=Pout/BPPlat is maximized by developing designs and technology for lowest lateral beam parameter product, BPPlat, at highest optical output power Pout. This can be achieved by limiting the number of guided lateral modes and by improving the beam quality of low-order lateral modes. Important effects to address include process and packaging induced wave-guiding, lateral carrier accumulation and the thermal lens profile. A careful selection of vertical design is also shown to be important, as are advanced techniques to filter out higher order modes.

Precipitation of Inner-Zone Electrons by Whistler-Mode Waves from the VLF Transmitters UMS and NWC

DTIC Science & Technology

1980-12-01

model plasmasphere in diffusive equilibrium [ Angerami and Thomas ,1964]. The diffusive-equilibrium model used a 90 to 10 percent H+ to O mixture at 16000...Experiments with the Kosmos- 142 and Kosmos-Z59 artificial satellites, Izv. Vyssh. Uchebn. Zaved., Radiofiz, Engl. Transl., 18, 996, 1975. Angerami

Diffusion phenomenon at the interface of Cu-brass under a strong gravitational field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogata, Yudai; Tokuda, Makoto; Januszko, Kamila

2015-03-28

To investigate diffusion phenomenon at the interface between Cu and brass under a strong gravitational field generated by ultracentrifuge apparatus, we performed gravity experiments on samples prepared by electroplating with interfaces normal and parallel to the direction of gravity. For the parallel-mode sample, for which sedimentation cannot occur thorough the interface, the concentration change was significant within the lower gravity region; many pores were observed in this region. Many vacancies arising from crystal strain due to the strong gravitational field moved into the lower gravity region, and enhanced the atoms mobilities. For the two normal-mode samples, which have interface normalmore » to the direction of gravity, the composition gradient of the brass-on-Cu sample was steeper than that for Cu-on-brass. This showed that the atoms of denser Cu diffuse in the direction of gravity, whereas Zn atoms diffuse in the opposite direction by sedimentation. The interdiffusion coefficients became higher in the Cu-on-brass sample, and became lower in the brass-on-Cu sample. This rise may be related to the behavior of the vacancies.« less

77 FR 58216 - Notice of Applications for Modification of Special Permit

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-19

... DEPARTMENT OF TRANSPORTATION Pipeline and Hazardous Materials Safety Administration Notice of... Department of Transportation's Hazardous Material Regulations (49 CFR Part 107, Subpart B), notice is hereby... hazardous materials, packaging design changes, additional mode of transportation, etc.) are described in...

77 FR 23541 - Notice of Applications for Modification of Special Permit

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-19

... DEPARTMENT OF TRANSPORTATION Pipeline and Hazardous Materials Safety Administration Notice of... Department of Transportation's Hazardous Material Regulations (49 CFR part 107, subpart B), notice is hereby... hazardous materials, packaging design changes, additional mode of transportation, etc.) are described in...

77 FR 64845 - Notice of Applications for Modification of Special Permit

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-23

... DEPARTMENT OF TRANSPORTATION Pipeline and Hazardous Materials Safety Administration Notice of... Department of Transportation's Hazardous Material Regulations (49 CFR part 107, subpart B), notice is hereby... hazardous materials, packaging design changes, additional mode of transportation, etc.) are described in...

Hypercard Another Computer Tool.

ERIC Educational Resources Information Center

Geske, Joel

1991-01-01

Describes "Hypercard," a computer application package usable in all three modes of instructional computing: tutor, tool, and tutee. Suggests using Hypercard in scholastic journalism programs to teach such topics as news, headlines, design, photography, and advertising. Argues that the ability to access, organize, manipulate, and comprehend…

Preliminary analysis techniques for ring and stringer stiffened cylindrical shells

NASA Technical Reports Server (NTRS)

Graham, J.

1993-01-01

This report outlines methods of analysis for the buckling of thin-walled circumferentially and longitudinally stiffened cylindrical shells. Methods of analysis for the various failure modes are presented in one cohesive package. Where applicable, more than one method of analysis for a failure mode is presented along with standard practices. The results of this report are primarily intended for use in launch vehicle design in the elastic range. A Microsoft Excel worksheet with accompanying macros has been developed to automate the analysis procedures.

Preliminary design of a solar central receiver for a site-specific repowering application (Saguaro Power Plant). Volume IV. Appendixes. Final report, October 1982-September 1983

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weber, E.R.

1983-09-01

The appendixes for the Saguaro Power Plant includes the following: receiver configuration selection report; cooperating modes and transitions; failure modes analysis; control system analysis; computer codes and simulation models; procurement package scope descriptions; responsibility matrix; solar system flow diagram component purpose list; thermal storage component and system test plans; solar steam generator tube-to-tubesheet weld analysis; pipeline listing; management control schedule; and system list and definitions.

Diffusion of Zonal Variables Using Node-Centered Diffusion Solver

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, T B

2007-08-06

Tom Kaiser [1] has done some preliminary work to use the node-centered diffusion solver (originally developed by T. Palmer [2]) in Kull for diffusion of zonal variables such as electron temperature. To avoid numerical diffusion, Tom used a scheme developed by Shestakov et al. [3] and found their scheme could, in the vicinity of steep gradients, decouple nearest-neighbor zonal sub-meshes leading to 'alternating-zone' (red-black mode) errors. Tom extended their scheme to couple the sub-meshes with appropriate chosen artificial diffusion and thereby solved the 'alternating-zone' problem. Because the choice of the artificial diffusion coefficient could be very delicate, it is desirablemore » to use a scheme that does not require the artificial diffusion but still able to avoid both numerical diffusion and the 'alternating-zone' problem. In this document we present such a scheme.« less

Effects of whistler mode hiss waves on the radiation belts structure during quiet times

NASA Astrophysics Data System (ADS)

Ripoll, J. F.; Santolik, O.; Reeves, G. D.; Kurth, W. S.; Denton, M.; Loridan, V.; Thaller, S. A.; Cunningham, G.; Kletzing, C.; Turner, D. L.; Henderson, M. G.; Ukhorskiy, S.; Drozdov, A.; Cervantes Villa, J. S.; Shprits, Y.

2017-12-01

We present dynamic Fokker-Planck simulations of the electron radiation belts and slot formation during the quiet days that can follow a storm. Simulations are made for all energies and L-shells between 2 and 6 in the view of recovering the observations of two particular events. Pitch angle diffusion is essential to energy structure of the belts and slot region. Pitch angle diffusion is computed from data-driven spatially and temporally-resolved whistler mode hiss wave and ambient plasma observations from the Van Allen Probes satellites. The simulations are performed either with a 3D formulation that uses pitch angle diffusion coefficients or with a simpler 1D Fokker-Planck equation based on losses computed from a lifetime. Validation is carried out globally against Magnetic Electron and Ion Spectrometer observations of the belts at all energy. Results are complemented with a sensitivity study involving different radial diffusion coefficients, electron lifetimes, and pitch angle diffusion coefficients. We discuss which models allow to recover the observed "S-shaped" energy-dependent inner boundary to the outer zone that results from the competition between diffusive radial transport and losses. Periods when the plasmasphere extends beyond L 5 favor long-lasting hiss losses from the outer belt. Through these simulations, we explain the full structure in energy and L-shell of the belts and the slot formation by hiss scattering during quiet storm recovery.

Microphysics of liquid complex plasmas in equilibrium and non-equilibrium systems

NASA Astrophysics Data System (ADS)

Piel, Alexander; Block, Dietmar; Melzer, André; Mulsow, Matthias; Schablinski, Jan; Schella, André; Wieben, Frank; Wilms, Jochen

2018-05-01

The dynamic evolution of the microscopic structure of solid and liquid phases of complex plasmas is studied experimentally and by means of molecular dynamics (MD) simulations. In small finite systems, the cooperative motion can be described in terms of discrete modes. These modes are studied with different experimental approaches. Using diffuse scattered laser light, applying laser tweezer forces to individual particles, and periodic laser pulses, the excitation of modes is investigated. The instantaneous normal mode analysis of experimental data from two-dimensional liquid clusters gives access to the local dynamics of the liquid phase. Our investigations shed light on the role of compressional and shear modes as well as the determination of diffusion constants and melting temperatures in finite systems. Special attention is paid to hydrodynamic situations with a stationary inhomogeneous dust flow. MD simulations allow to study the collective motion in the shell of nearest neighbors, which can be linked to smooth and sudden changes of the macroscopic flow. Finally, the observed micro-motion in all situations above allows to shed light on the preference of shear-like over compressional motion in terms of a minimized potential energy and a dynamic incompressibility.

Mode and polarization state selected guided wave spectroscopy of orientational anisotrophy in model membrane cellulosic polymer films: relevance to lab-on-a-chip

NASA Astrophysics Data System (ADS)

Andrews, Mark P.; Kanigan, Tanya

2007-06-01

Orientation anisotropies in structural properties relevant to the use of cellulosic polymers as membranes for lab-on-chips were investigated for cellulose acetate (CA) and regenerated cellulose (RC) films deposited as slab waveguides. Anisotropy was probed with mode and polarization state selected guided wave Raman spectroscopy. CA exhibits partial chain orientation in the plane of the film, and this orientation is independent of sample substrate and film preparation conditions. RC films also show in-plane anisotropy, where the hexose sugar rings lie roughly in the plane of the film. Explanations are given of the role of artifacts in interpreting waveguide Raman spectra, including anomalous contributions to Raman spectra that arise from deviations from right angle scattering geometry, mode-dependent contributions to longitudinal electric field components and TE<-->TM mode conversion. We explore diffusion profiles of small molecules in cellulosic films by adaptations of an inverse-Wentzel-Kramers-Brillouin (iWKB) recursive, noninteger virtual mode index algorithm. Perturbations in the refractive index distribution, n(z), are recovered from the measured relative propagation constants, neffective,m, of the planar waveguide. The refractive index distribution then yields the diffusion profile.

Packaging and testing of multi-wavelength DFB laser array using REC technology

NASA Astrophysics Data System (ADS)

Ni, Yi; Kong, Xuan; Gu, Xiaofeng; Chen, Xiangfei; Zheng, Guanghui; Luan, Jia

2014-02-01

Packaging of distributed feedback (DFB) laser array based on reconstruction-equivalent-chirp (REC) technology is a bridge from chip to system, and influences the practical process of REC chip. In this paper, DFB laser arrays of 4-channel @1310 nm and 8-channel @1550 nm are packaged. Our experimental results show that both these laser arrays have uniform wavelength spacing and larger than 35 dB average Side Mode Suppression Ratio (SMSR). When I=35 mA, we obtain the total output power of 1 mW for 4-channel @1310 nm, and 227 μw for 8-channel @1550 nm respectively. The high frequency characteristics of the packaged chips are also obtained, and the requirements for 4×10 G or even 8×10 G systems can be reached. Our results demonstrate the practical and low cost performance of REC technology and indicate its potential in the future fiber-to-the-home (FTTH) application.

Integrating protein structural dynamics and evolutionary analysis with Bio3D.

PubMed

Skjærven, Lars; Yao, Xin-Qiu; Scarabelli, Guido; Grant, Barry J

2014-12-10

Popular bioinformatics approaches for studying protein functional dynamics include comparisons of crystallographic structures, molecular dynamics simulations and normal mode analysis. However, determining how observed displacements and predicted motions from these traditionally separate analyses relate to each other, as well as to the evolution of sequence, structure and function within large protein families, remains a considerable challenge. This is in part due to the general lack of tools that integrate information of molecular structure, dynamics and evolution. Here, we describe the integration of new methodologies for evolutionary sequence, structure and simulation analysis into the Bio3D package. This major update includes unique high-throughput normal mode analysis for examining and contrasting the dynamics of related proteins with non-identical sequences and structures, as well as new methods for quantifying dynamical couplings and their residue-wise dissection from correlation network analysis. These new methodologies are integrated with major biomolecular databases as well as established methods for evolutionary sequence and comparative structural analysis. New functionality for directly comparing results derived from normal modes, molecular dynamics and principal component analysis of heterogeneous experimental structure distributions is also included. We demonstrate these integrated capabilities with example applications to dihydrofolate reductase and heterotrimeric G-protein families along with a discussion of the mechanistic insight provided in each case. The integration of structural dynamics and evolutionary analysis in Bio3D enables researchers to go beyond a prediction of single protein dynamics to investigate dynamical features across large protein families. The Bio3D package is distributed with full source code and extensive documentation as a platform independent R package under a GPL2 license from http://thegrantlab.org/bio3d/ .

Single-longitudinal-mode, narrow bandwidth double-ring fiber laser stabilized by an efficiently taper-coupled high roundness microsphere resonator

NASA Astrophysics Data System (ADS)

Wan, Hongdan; Liu, Linqian; Ding, Zuoqin; Wang, Jie; Xiao, Yu; Zhang, Zuxing

2018-06-01

This paper proposes and demonstrates a single-longitudinal-mode, narrow bandwidth fiber laser, using an ultra-high roundness microsphere resonator (MSR) with a stabilized package as the single-longitudinal-mode selector inside a double-ring fiber cavity. By improving the heating technology and surface cleaning process, MSR with high Q factor are obtained. With the optimized coupling condition, light polarization state and fiber taper diameter, we achieve whispering gallery mode (WGM) spectra with a high extinction ratio of 23 dB, coupling efficiency of 99.5%, a 3 dB bandwidth of 1 pm and a side-mode-suppression-ratio of 14.5 dB. The proposed fiber laser produces single-longitudinal-mode laser output with a 20-dB frequency linewidth of about 340 kHz, a signal-to-background ratio of 54 dB and a high long-term stability without mode-hopping, which is potential for optical communication and sensing applications.

Design considerations for FET-gated power transistors

NASA Technical Reports Server (NTRS)

Chen, D. Y.; Chin, S. A.

1983-01-01

An FET-bipolar combinational power transistor configuration (tested up to 300 V, 20 A at 100 kHz) is described. The critical parameters for integrating the chips in hybrid form are examined, and an effort to optimize the overall characteristics of the configuration is discussed. Chip considerations are examined with respect to the voltage and current rating of individual chips, the FET surge capability, the choice of triple diffused transistor or epitaxial transistor for the bipolar element, the current tailing effect, and the implementation of the bipolar transistor and an FET as single chip or separate chips. Package considerations are discussed with respect to package material and geometry, surge current capability of bipolar base terminal bonding, and power losses distribution.

Predictive microbiology for food packaging applications

USDA-ARS?s Scientific Manuscript database

Mathematical modeling has been applied to describe the microbial growth and inactivation in foods for decades and is also known as ‘Predictive microbiology’. When models are developed and validated, their applications may save cost and time. The Pathogen Modeling Program (PMP), a collection of mode...

Independent Orbiter Assessment (IOA): Analysis of the electrical power generation/power reactant storage and distribution subsystem

NASA Technical Reports Server (NTRS)

Gotch, S. M.

1986-01-01

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NAA FMEA/CIL documentation. The independent analysis results corresponding to the Orbiter Electrical Power Generation (EPG)/Power Reactants Storage and Distribution (PRSD) System Hardware is documented. The EPG/PRSD hardware is required for performing critical functions of cryogenic hydrogen and oxygen storage and distribution to the Fuel Cell Powerplants (FCP) and Atmospheric Revitalization Pressure Control Subsystem (ARPCS). Specifically, the EPG/PRSD hardware consists of the following: Hydryogen (H2) tanks; Oxygen (O2) tanks; H2 Relief Valve/Filter Packages (HRVFP); O2 Relief Valve/Filter Packages (ORVFP); H2 Valve Modules (HVM); O2 Valve Modules (OVM); and O2 and H2 lines, components, and fittings.

PyVCI: A flexible open-source code for calculating accurate molecular infrared spectra

NASA Astrophysics Data System (ADS)

Sibaev, Marat; Crittenden, Deborah L.

2016-06-01

The PyVCI program package is a general purpose open-source code for simulating accurate molecular spectra, based upon force field expansions of the potential energy surface in normal mode coordinates. It includes harmonic normal coordinate analysis and vibrational configuration interaction (VCI) algorithms, implemented primarily in Python for accessibility but with time-consuming routines written in C. Coriolis coupling terms may be optionally included in the vibrational Hamiltonian. Non-negligible VCI matrix elements are stored in sparse matrix format to alleviate the diagonalization problem. CPU and memory requirements may be further controlled by algorithmic choices and/or numerical screening procedures, and recommended values are established by benchmarking using a test set of 44 molecules for which accurate analytical potential energy surfaces are available. Force fields in normal mode coordinates are obtained from the PyPES library of high quality analytical potential energy surfaces (to 6th order) or by numerical differentiation of analytic second derivatives generated using the GAMESS quantum chemical program package (to 4th order).

Bird impact analysis package for turbine engine fan blades

NASA Technical Reports Server (NTRS)

Hirschbein, M. S.

1982-01-01

A computer program has been developed to analyze the gross structural response of turbine engine fan blades subjected to bird strikes. The program couples a NASTRAN finite element model and modal analysis of a fan blade with a multi-mode bird impact analysis computer program. The impact analysis uses the NASTRAN blade model and a fluid jet model of the bird to interactively calculate blade loading during a bird strike event. The analysis package is computationaly efficient, easy to use and provides a comprehensive history of the gross structual blade response. Example cases are presented for a representative fan blade.

Fatigue failure of pb-free electronic packages under random vibration loads

NASA Astrophysics Data System (ADS)

Saravanan, S.; Prabhu, S.; Muthukumar, R.; Gowtham Raj, S.; Arun Veerabagu, S.

2018-03-01

The electronic equipment are used in several fields like, automotive, aerospace, consumer goods where they are subjected to vibration loads leading to failure of solder joints used in these equipment. This paper presents a methodology to predict the fatigue life of Pb-free surface mounted BGA packages subjected to random vibrations. The dynamic characteristics of the PCB, such as the natural frequencies, mode shapes and damping ratios were determined. Spectrum analysis was used to determine the stress response of the critical solder joint and the cumulative fatigue damage accumulated by the solder joint for a specific duration was determined.

Perturbative studies of toroidal momentum transport in KSTAR H-mode and the effect of ion temperature perturbation

NASA Astrophysics Data System (ADS)

Yang, S. M.; Na, Yong-Su; Na, D. H.; Park, J.-K.; Shi, Y. J.; Ko, W. H.; Lee, S. G.; Hahm, T. S.

2018-06-01

Perturbative experiments have been carried out using tangential neutral beam injection (NBI) and non-resonant magnetic perturbation (NRMP) to analyze the momentum transport properties in KSTAR H-modes. Diffusive and non-diffusive terms of momentum transport are evaluated from the transient analysis. Although the operating conditions and methodologies applied in the two cases are similar, the momentum transport properties obtained show clear differences. The estimated momentum diffusivity and pinch obtained in the NBI modulation experiments is larger than that in the NRMP modulation experiments. We found that this discrepancy could be a result of uncertainties in the assumption for the analysis. By introducing time varying momentum transport coefficients depending on the temperature gradient, the linearized equation shows that if the temperature perturbation exists, the evolution of toroidal rotation perturbation could be faster than the transport rate of mean quantity, since the evolution of toroidal rotation perturbation is related to , a momentum diffusivity from perturbative analysis. This could explain the estimated higher momentum diffusivity using time independent transport coefficients in NBI experiments with higher ion temperature perturbation compared to that in NRMP modulation experiments. The differences in the momentum transport coefficient with NRMP and NBI are much reduced by considering time varying momentum transport coefficients in the time dependent transport simulation.

Quasi-linear diffusion coefficients for highly oblique whistler mode waves

NASA Astrophysics Data System (ADS)

Albert, J. M.

2017-05-01

Quasi-linear diffusion coefficients are considered for highly oblique whistler mode waves, which exhibit a singular "resonance cone" in cold plasma theory. The refractive index becomes both very large and rapidly varying as a function of wave parameters, making the diffusion coefficients difficult to calculate and to characterize. Since such waves have been repeatedly observed both outside and inside the plasmasphere, this problem has received renewed attention. Here the diffusion equations are analytically treated in the limit of large refractive index μ. It is shown that a common approximation to the refractive index allows the associated "normalization integral" to be evaluated in closed form and that this can be exploited in the numerical evaluation of the exact expression. The overall diffusion coefficient formulas for large μ are then reduced to a very simple form, and the remaining integral and sum over resonances are approximated analytically. These formulas are typically written for a modeled distribution of wave magnetic field intensity, but this may not be appropriate for highly oblique whistlers, which become quasi-electrostatic. Thus, the analysis is also presented in terms of wave electric field intensity. The final results depend strongly on the maximum μ (or μ∥) used to model the wave distribution, so realistic determination of these limiting values becomes paramount.

Helium, Iron and Electron Particle Transport and Energy Transport Studies on the TFTR Tokamak

DOE R&D Accomplishments Database

Synakowski, E. J.; Efthimion, P. C.; Rewoldt, G.; Stratton, B. C.; Tang, W. M.; Grek, B.; Hill, K. W.; Hulse, R. A.; Johnson, D .W.; Mansfield, D. K.; McCune, D.; Mikkelsen, D. R.; Park, H. K.; Ramsey, A. T.; Redi, M. H.; Scott, S. D.; Taylor, G.; Timberlake, J.; Zarnstorff, M. C. (Princeton Univ., NJ (United States). Plasma Physics Lab.); Kissick, M. W. (Wisconsin Univ., Madison, WI (United States))

1993-03-01

Results from helium, iron, and electron transport on TFTR in L-mode and Supershot deuterium plasmas with the same toroidal field, plasma current, and neutral beam heating power are presented. They are compared to results from thermal transport analysis based on power balance. Particle diffusivities and thermal conductivities are radially hollow and larger than neoclassical values, except possibly near the magnetic axis. The ion channel dominates over the electron channel in both particle and thermal diffusion. A peaked helium profile, supported by inward convection that is stronger than predicted by neoclassical theory, is measured in the Supershot The helium profile shape is consistent with predictions from quasilinear electrostatic drift-wave theory. While the perturbative particle diffusion coefficients of all three species are similar in the Supershot, differences are found in the L-Mode. Quasilinear theory calculations of the ratios of impurity diffusivities are in good accord with measurements. Theory estimates indicate that the ion heat flux should be larger than the electron heat flux, consistent with power balance analysis. However, theoretical values of the ratio of the ion to electron heat flux can be more than a factor of three larger than experimental values. A correlation between helium diffusion and ion thermal transport is observed and has favorable implications for sustained ignition of a tokamak fusion reactor.

Flexible packaging for PV modules

NASA Astrophysics Data System (ADS)

Dhere, Neelkanth G.

2008-08-01

Economic, flexible packages that provide needed level of protection to organic and some other PV cells over >25-years have not yet been developed. However, flexible packaging is essential in niche large-scale applications. Typical configuration used in flexible photovoltaic (PV) module packaging is transparent frontsheet/encapsulant/PV cells/flexible substrate. Besides flexibility of various components, the solder bonds should also be flexible and resistant to fatigue due to cyclic loading. Flexible front sheets should provide optical transparency, mechanical protection, scratch resistance, dielectric isolation, water resistance, UV stability and adhesion to encapsulant. Examples are Tefzel, Tedlar and Silicone. Dirt can get embedded in soft layers such as silicone and obscure light. Water vapor transmittance rate (WVTR) of polymer films used in the food packaging industry as moisture barriers are ~0.05 g/(m2.day) under ambient conditions. In comparison, light emitting diodes employ packaging components that have WVTR of ~10-6 g/(m2.day). WVTR of polymer sheets can be improved by coating them with dense inorganic/organic multilayers. Ethylene vinyl acetate, an amorphous copolymer used predominantly by the PV industry has very high O2 and H2O diffusivity. Quaternary carbon chains (such as acetate) in a polymer lead to cleavage and loss of adhesional strength at relatively low exposures. Reactivity of PV module components increases in presence of O2 and H2O. Adhesional strength degrades due to the breakdown of structure of polymer by reactive, free radicals formed by high-energy radiation. Free radical formation in polymers is reduced when the aromatic rings are attached at regular intervals. This paper will review flexible packaging for PV modules.

Bionanocomposites materials for food packaging applications: Concepts and future outlook.

PubMed

Youssef, Ahmed M; El-Sayed, Samah M

2018-08-01

Bionanocomposites materials open a chance for the usage of novel, high performance, lightweight, and ecofriendly composite materials making them take place the traditional non-biodegradable plastic packaging materials. Biopolymers like polysaccharides such as chitosan (CS), carboxymethyl cellulose (CMC), starch and cellophane could be used to resolve environmental hazards owing to their biodegradability and non-toxicity. In addition these advantages, polysaccharides have some disadvantages for example poor mechanical properties and low resistance to water. Therefore, nanomaterials are used to improve the thermal, mechanical and gas barrier properties without hindering their biodegradable and non-toxic characters. Furthermore, the most favorable nanomaterials are layered silicate nanoclays for example montmorillonite (MMT) and kaolinite, zinc oxide (ZnO-NPs), titanium dioxide (TiO 2 -NPs), and silver nanoparticles (Ag-NPs). In packaging application, the improvement of barrier properties of prepared films against oxygen, carbon dioxide, flavor compounds diffusion through the packaging films. Wide varieties of nanomaterials are suitable to offer smart and/or intelligent properties for food packaging materials, as demonstrated by oxygen scavenging capability, antimicrobial activity, and sign of the level of exposure to various harmful features for instance oxygen levels or insufficient temperatures. The compatibility between nanomaterials and polymers matrix consider the most challenge for the preparation of bionanocomposites as well as getting whole distribution of nanoparticles into the polymer matrix. We keen in this review the development of packaging materials performance and their mechanical, degradability and thermal stability as well as antibacterial activity for utilization of bionanocomposites in different packaging application is considered. Copyright © 2018 Elsevier Ltd. All rights reserved.

Wave theory of turbulence in compressible media

NASA Technical Reports Server (NTRS)

Kentzer, C. P.

1975-01-01

An acoustical theory of turbulence was developed to aid in the study of the generation of sound in turbulent flows. The statistical framework adopted is a quantum-like wave dynamical formulation in terms of complex distribution functions. This formulation results in nonlinear diffusion-type transport equations for the probability densities of the five modes of wave propagation: two vorticity modes, one entropy mode, and two acoustic modes. This system of nonlinear equations is closed and complete. The technique of analysis was chosen such that direct applications to practical problems can be obtained with relative ease.

Trapping saturation of the bump-on-tail instability and electrostatic harmonic excitation in earth's foreshock

NASA Technical Reports Server (NTRS)

Klimas, Alexander J.

1990-01-01

The Vlasov simulation is used to examine the trapping saturation of the bump-on-tail instability both with and without mode-mode coupling and subsequent harmonic excitation. It is found that adding the pumped harmonic modes leads to a significant difference in the behavior of the phase-space distribution function near the unstable bump at the saturation time of the instability. The pumped modes permit rapid plateau formation on the space-averaged velocity distribution, in effect preventing the onset of the quasi-linear velocity-diffusion saturation mechanism.

Spectral diffusion and electron-phonon coupling of the B800 BChl a molecules in LH2 complexes from three different species of purple bacteria.

PubMed

Baier, J; Gabrielsen, M; Oellerich, S; Michel, H; van Heel, M; Cogdell, R J; Köhler, J

2009-11-04

We have investigated the spectral diffusion and the electron-phonon coupling of B800 bacteriochlorophyll a molecules in the peripheral light-harvesting complex LH2 for three different species of purple bacteria, Rhodobacter sphaeroides, Rhodospirillum molischianum, and Rhodopseudomonas acidophila. We come to the conclusion that B800 binding pockets for Rhodobacter sphaeroides and Rhodopseudomonas acidophila are rather similar with respect to the polarity of the protein environment but that the packaging of the alphabeta-polypeptides seems to be less tight in Rb. sphaeroides with respect to the other two species.

Small, high pressure ratio compressor: Aerodynamic and mechanical design

NASA Technical Reports Server (NTRS)

Bryce, C. A.; Erwin, J. R.; Perrone, G. L.; Nelson, E. L.; Tu, R. K.; Bosco, A.

1973-01-01

The Small, High-Pressure-Ratio Compressor Program was directed toward the analysis, design, and fabrication of a centrifugal compressor providing a 6:1 pressure ratio and an airflow rate of 2.0 pounds per second. The program consists of preliminary design, detailed areodynamic design, mechanical design, and mechanical acceptance tests. The preliminary design evaluate radial- and backward-curved blades, tandem bladed impellers, impeller-and diffuser-passage boundary-layer control, and vane, pipe, and multiple-stage diffusers. Based on this evaluation, a configuration was selected for detailed aerodynamic and mechanical design. Mechanical acceptance test was performed to demonstrate that mechanical design objectives of the research package were met.

The use of optimization techniques to design controlled diffusion compressor blading

NASA Technical Reports Server (NTRS)

Sanger, N. L.

1982-01-01

A method for automating compressor blade design using numerical optimization, and applied to the design of a controlled diffusion stator blade row is presented. A general purpose optimization procedure is employed, based on conjugate directions for locally unconstrained problems and on feasible directions for locally constrained problems. Coupled to the optimizer is an analysis package consisting of three analysis programs which calculate blade geometry, inviscid flow, and blade surface boundary layers. The optimizing concepts and selection of design objective and constraints are described. The procedure for automating the design of a two dimensional blade section is discussed, and design results are presented.

sfDM: Open-Source Software for Temporal Analysis and Visualization of Brain Tumor Diffusion MR Using Serial Functional Diffusion Mapping.

PubMed

Ceschin, Rafael; Panigrahy, Ashok; Gopalakrishnan, Vanathi

2015-01-01

A major challenge in the diagnosis and treatment of brain tumors is tissue heterogeneity leading to mixed treatment response. Additionally, they are often difficult or at very high risk for biopsy, further hindering the clinical management process. To overcome this, novel advanced imaging methods are increasingly being adapted clinically to identify useful noninvasive biomarkers capable of disease stage characterization and treatment response prediction. One promising technique is called functional diffusion mapping (fDM), which uses diffusion-weighted imaging (DWI) to generate parametric maps between two imaging time points in order to identify significant voxel-wise changes in water diffusion within the tumor tissue. Here we introduce serial functional diffusion mapping (sfDM), an extension of existing fDM methods, to analyze the entire tumor diffusion profile along the temporal course of the disease. sfDM provides the tools necessary to analyze a tumor data set in the context of spatiotemporal parametric mapping: the image registration pipeline, biomarker extraction, and visualization tools. We present the general workflow of the pipeline, along with a typical use case for the software. sfDM is written in Python and is freely available as an open-source package under the Berkley Software Distribution (BSD) license to promote transparency and reproducibility.

Molecular modeling of polymers 16. Gaseous diffusion in polymers: a quantitative structure-property relationship (QSPR) analysis.

PubMed

Patel, H C; Tokarski, J S; Hopfinger, A J

1997-10-01

The purpose of this study was to identify the key physicochemical molecular properties of polymeric materials responsible for gaseous diffusion in the polymers. Quantitative structure-property relationships, QSPRs were constructed using a genetic algorithm on a training set of 16 polymers for which CO2, N2, O2 diffusion constants were measured. Nine physicochemical properties of each of the polymers were used in the trial basis set for QSPR model construction. The linear cross-correlation matrices were constructed and investigated for colinearity among the members of the training sets. Common water diffusion measures for a limited training set of six polymers was used to construct a "semi-QSPR" model. The bulk modulus of the polymer was overwhelmingly found to be the dominant physicochemical polymer property that governs CO2, N2 and O2 diffusion. Some secondary physicochemical properties controlling diffusion, including conformational entropy, were also identified as correlation descriptors. Very significant QSPR diffusion models were constructed for all three gases. Cohesive energy was identified as the main correlation physicochemical property with aqueous diffusion measures. The dominant role of polymer bulk modulus on gaseous diffusion makes it difficult to develop criteria for selective transport of gases through polymers. Moreover, high bulk moduli are predicted to be necessary for effective gas barrier materials. This property requirement may limit the processing and packaging features of the material. Aqueous diffusion in polymers may occur by a different mechanism than gaseous diffusion since bulk modulus does not correlate with aqueous diffusion, but rather cohesive energy of the polymer.

Activation energies of diffusion of organic migrants in cyclo olefin polymer.

PubMed

Welle, Frank

2014-10-01

Cyclo olefin polymer (COP) is an amorphous polymer with good optical transparency and barrier properties, which is increasingly used for pharmaceutical packaging applications like pre-filled syringes, plastic vials, nutrition bags and blisters as well as for micro-well plates. For regulatory purposes, it is important to know the amount and quantity of compounds which migrate from the polymer into the pharmaceutical product. Within the study, diffusion coefficients of organic (model) compounds in COP at various temperatures were determined and the activation energies of diffusion were calculated according to the Arrhenius approach. Correlations were established between the molecular volume V of the migrating compound and the activation energy of diffusion EA as well as between the pre-exponential factor in the Arrhenius equation D0 and EA. From these correlations a prediction model was established for the migration of organic compounds in COP. This might be a useful tool supporting the evaluation process of COP packed pharmaceutical products. Copyright © 2014 Elsevier B.V. All rights reserved.

Hera - The HEASARC's New Data Analysis Service

NASA Technical Reports Server (NTRS)

Pence, William

2006-01-01

Hera is the new computer service provided by the HEASARC at the NASA Goddard Space Flight Center that enables qualified student and professional astronomical researchers to immediately begin analyzing scientific data from high-energy astrophysics missions. All the necessary resources needed to do the data analysis are freely provided by Hera, including: * the latest version of the hundreds of scientific analysis programs in the HEASARC's HEASOFT package, as well as most of the programs in the Chandra CIAO package and the XMM-Newton SAS package. * high speed access to the terabytes of data in the HEASARC's high energy astrophysics Browse data archive. * a cluster of fast Linw workstations to run the software * ample local disk space to temporarily store the data and results. Some of the many features and different modes of using Hera are illustrated in this poster presentation.

[Simultaneous determination of 9 ultraviolet stabilizers in food plastic packaging materials by solid phase extraction-high performance liquid chromatography].

PubMed

Zhang, Juzhou; Li, Jing; Shao, Dongliang; Yao, Bangben; Jiang, Junshu

2012-02-01

An effective high performance liquid chromatographic (HPLC) method has been developed for the simultaneous determination of 9 ultraviolet stabilizers in food plastic packaging materials. The food packaging samples were firstly extracted by methanol-ethyl acetate, and then purified by a C18 solid-phase extraction (SPE) column. The target compounds were separated on a ZORBAX SB-C18 column (250 mm x 4.6 mm, 5 microm) in gradient elution mode using methanol and water as mobile phases. The detection wavelength was at 310 nm. The linear plots of the nine ultraviolet stabilizers were obtained between 0.2 and 10 mg/L, with the correlation coefficients of above 0. 999 for the nine ultraviolet stabilizers. The limits of detection for this method were in the range from 0.05 to 0.1 mg/L. The recoveries spiked in commercial food plastic packaging materials were in the range of 70.2% - 89.0% with the relative standard deviations of 0.4% - 4.5%. The results indicated that the method is simple, accurate, and suitable for the simultaneous determination of the nine ultraviolet stabilizers in food plastic packaging materials.

Towards co-packaging of photonics and microelectronics in existing manufacturing facilities

NASA Astrophysics Data System (ADS)

Janta-Polczynski, Alexander; Cyr, Elaine; Bougie, Jerome; Drouin, Alain; Langlois, Richard; Childers, Darrell; Takenobu, Shotaro; Taira, Yoichi; Lichoulas, Ted W.; Kamlapurkar, Swetha; Engelmann, Sebastian; Fortier, Paul; Boyer, Nicolas; Barwicz, Tymon

2018-02-01

The impact of integrated photonics on optical interconnects is currently muted by challenges in photonic packaging and in the dense integration of photonic modules with microelectronic components on printed circuit boards. Single mode optics requires tight alignment tolerance for optical coupling and maintaining this alignment in a cost-efficient package can be challenging during thermal excursions arising from downstream microelectronic assembly processes. In addition, the form factor of typical fiber connectors is incompatible with the dense module integration expected on printed circuit boards. We have implemented novel approaches to interfacing photonic chips to standard optical fibers. These leverage standard high throughput microelectronic assembly tooling and self-alignment techniques resulting in photonic packaging that is scalable in manufacturing volume and in the number of optical IOs per chip. In addition, using dense optical fiber connectors with space-efficient latching of fiber patch cables results in compact module size and efficient board integration, bringing the optics closer to the logic chip to alleviate bandwidth bottlenecks. This packaging direction is also well suited for embedding optics in multi-chip modules, including both photonic and microelectronic chips. We discuss the challenges and rewards in this type of configuration such as thermal management and signal integrity.

[Lateral diffusion of saturated phosphatidylcholines in cholesterol-containing bilayers].

PubMed

Filippov, A V; Rudakova, M A; Oradd, G; Lindblom, J

2007-01-01

Lateral diffusion in oriented bilayers of saturated cholesterol-containing phosphatidylcholines, dipalmitoylphosphatidylcholine and dimyrilstoylphosphatidylcholine upon their limiting hydration has been studied by NMR with impulse gradient of magnetic field. For both systems, similar dependences of the coefficient of lateral diffusion on temperature and cholesterol concentration were observed, which agree with the phase diagram showing the presence of regions of ordered and unordered liquid-crystalline phases and a two-phase region. Under similar conditions, the coefficient of lateral diffusion for dipalmytoylphosphatidylcholine has lower values, which is in qualitative agreement with its greater molecular mass. A comparison of data for dipalmytoylphosphatidylcholine with the results obtained earlier for dipalmytoylsphyngomyelin/cholesterol under the same conditions shows, despite a similarity in phase diagrams, greater (two- to threefold) differences in the values of the coefficient of lateral diffusion and a different mode of dependence of the coefficient on cholesterol concentration. A comparison of data for dimyrilstoylphosphatidylcholine with the results obtained previously shows that the values of the coefficient of lateral diffusion and the mode of its dependence on cholesterol concentration coincide in the region of higher concentrations (more than 15 mole %) and differ in the region of lower concentrations (below 15 mole %). The discrepancies may be explained by different contents of water in the systems during the measurements. At a limiting hydration (more than 35%) of water, the coefficient of lateral diffusion decreases with increasing cholesterol concentration. If the content of water is about 25% (as a result of equilibrium hydration from vapors), the coefficient of lateral diffusion of phosphatidylcholine is probably independent of cholesterol concentration. This results from a denser packing of molecules in the bilayer at a lower water concentration, an effect that competes with the ordering effect of cholesterol.

Theoretical issues on the spontaneous rotation of axisymmetric plasmas

NASA Astrophysics Data System (ADS)

Coppi, B.; Zhou, T.

2014-09-01

An extensive series of experiments have confirmed that the observed ‘spontaneous rotation’ phenomenon in axisymmetric plasmas is related to the confinement properties of these plasmas and connected to the excitation of collective modes associated with these properties (Coppi 2000 18th IAEA Fusion Energy Conf. (Sorrento, Italy, 2000) THP 1/17, www-pub.iaea.org/MTCD/publications/PDF/csp_008c/html/node343.htm and Coppi 2002 Nucl. Fusion 42 1). In particular, radially localized modes can extract angular momentum from the plasma column from which they grow while the background plasma has to recoil in the direction opposite to that of the mode phase velocity. In the case of the excitation of the plasma modes at the edge, the loss of their angular momentum can be connected to the directed particle ejection to the surrounding medium. The recoil angular momentum is then redistributed inside the plasma column mainly by the combination of an effective viscous diffusion and an inward angular momentum transport velocity that is connected, for instance, to ion temperature gradient (ITG) driven modes. The linear and quasi-linear theories of the collisionless trapped electron modes and of the toroidal ITG driven modes are re-examined in the context of their influence on angular momentum transport. Internal modes that produce magnetic reconnection and are electromagnetic in nature, acquire characteristic phase velocity directions in high temperature regimes and become relevant to the ‘generation’ of angular momentum. The drift-tearing mode, the ‘complex’ reconnecting mode and the m0 = 1 internal mode belong to this category, the last mode acquiring different features depending on the strength of its driving factor. Toroidal velocity profiles that reproduce the experimental observations are obtained considering a global angular momentum balance equation that includes the localized sources associated with the excited internal electrostatic and electromagnetic modes besides the appropriate diffusive and the inward angular momentum transparent terms.

Criteria for the Evaluation of Microcomputer Courseware.

ERIC Educational Resources Information Center

Cohen, Vicki Blum

1983-01-01

Discusses attributes which are offered as set of standards to judge instructional software--those unique to design of microcomputer courseware and those included in design of all instruction. Curriculum role, modes of interaction, computer managed instruction, graphics, feedback, packaging, and manuals are noted. Fourteen references are included.…

77 FR 36607 - Office of Hazardous Materials Safety Notice of Application for Special Permits

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-19

... commerce of certain DOT Specification 20WC radioactive material packagings after October 1, 2008. (mode 1... DEPARTMENT OF TRANSPORTATION Pipeline and Hazardous Materials Safety Administration Office of Hazardous Materials Safety Notice of Application for Special Permits AGENCY: Pipeline and Hazardous...

The RIACS Intelligent Auditing and Categorizing System

NASA Technical Reports Server (NTRS)

Bishop, Matt

1988-01-01

The organization of the RIACS auditing package is described along with how to installation instructions and how to interpret the output. How to set up both local and remote file system auditing is given. Logging is done on a time driven basis, and auditing in a passive mode.

Utilizing Diffusion Theory to predict carbon dioxide concentration in an indoor environment

NASA Astrophysics Data System (ADS)

Kramer, Andrew R.

This research details a new method of relating sources of carbon dioxide to carbon dioxide concentration in a room operating in a reduced ventilation mode by utilizing Diffusion Theory. The theoretical basis of this research involved solving Fick's Second Law of Diffusion in spherical coordinates for a source of carbon dioxide flowing at a constant rate and located in the center of an impermeable spherical boundary. The solution was developed using a Laplace Transformation. A spherical diffusion test chamber was constructed and used to validate and benchmark the developed theory. The method was benchmarked by using Dispersion Coefficients for large carbon dioxide flow rates due to diffusion induced convection. The theoretical model was adapted to model a room operating with restricted ventilation in the presence of a known, constant source of carbon dioxide. The room was modeled as a sphere of volume equal to the room and utilized a Dispersion Coefficient that is consistent with published values. The developed Diffusion Model successfully predicted the spatial concentration of carbon dioxide in a room operating in a reduced ventilation mode in the presence of a source of carbon dioxide. The flow rates of carbon dioxide that were used in the room are comparable to the average flow rate of carbon dioxide from a person during quiet breathing, also known as the Tidal Breathing. This indicates the Diffusion Model developed from this research has the potential to correlate carbon dioxide concentration with static occupancy levels which can lead to energy savings through a reduction in air exchange rates when low occupancy is detected.

Anomalous plasma diffusion and the magnetopause boundary layer

NASA Technical Reports Server (NTRS)

Treumann, Rudolf A.; Labelle, James; Haerendel, Gerhard; Pottelette, Raymond

1992-01-01

An overview of the current state of anomalous diffusion research at the magnetopause and its role in the formation of the magnetopause boundary layer is presented. Plasma wave measurements in the boundary layer indicate that most of the relevant unstable wave modes contribute negligibly to the diffusion process at the magnetopause under magnetically undisturbed northward IMF conditions. The most promising instability is the lower hybrid drift instability, which may yield diffusion coefficients of the right order if the highest measured wave intensities are assumed. It is concluded that global stationary diffusion due to wave-particle interactions does not take place at the magnetopause. Microscopic wave-particle interaction and anomalous diffusion may contribute to locally break the MD frozen-in conditions and help in transporting large amounts of magnetosheath plasma across the magnetospheric boundary.

Wilkinson Microwave Anisotropy Probe (WMAP) Attitude Estimation Filter Comparison

NASA Technical Reports Server (NTRS)

Harman, Richard R.

2005-01-01

The Wilkinson Microwave Anisotropy Probe (WMAP) spacecraft was launched in June of 2001. The sensor complement of WMAP consists of two Autonomous Star Trackers (ASTs), two Fine Sun Sensors (FSSs), and a gyro package which contains redundancy about one of the WMAP body axes. The onboard attitude estimation filter consists of an extended Kalman filter (EKF) solving for attitude and gyro bias errors which are then resolved into a spacecraft attitude quaternion and gyro bias. A pseudo-linear Kalman filter has been developed which directly estimates the spacecraft attitude quaternion, rate, and gyro bias. In this paper, the performance of the two filters is compared for the two major control modes of WMAP: inertial mode and observation mode.

An efficient and numerically stable procedure for generating sextic force fields in normal mode coordinates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sibaev, M.; Crittenden, D. L., E-mail: deborah.crittenden@canterbury.ac.nz

In this paper, we outline a general, scalable, and black-box approach for calculating high-order strongly coupled force fields in rectilinear normal mode coordinates, based upon constructing low order expansions in curvilinear coordinates with naturally limited mode-mode coupling, and then transforming between coordinate sets analytically. The optimal balance between accuracy and efficiency is achieved by transforming from 3 mode representation quartic force fields in curvilinear normal mode coordinates to 4 mode representation sextic force fields in rectilinear normal modes. Using this reduced mode-representation strategy introduces an error of only 1 cm{sup −1} in fundamental frequencies, on average, across a sizable testmore » set of molecules. We demonstrate that if it is feasible to generate an initial semi-quartic force field in curvilinear normal mode coordinates from ab initio data, then the subsequent coordinate transformation procedure will be relatively fast with modest memory demands. This procedure facilitates solving the nuclear vibrational problem, as all required integrals can be evaluated analytically. Our coordinate transformation code is implemented within the extensible PyPES library program package, at http://sourceforge.net/projects/pypes-lib-ext/.« less

Automated analysis of biological oscillator models using mode decomposition.

PubMed

Konopka, Tomasz

2011-04-01

Oscillating signals produced by biological systems have shapes, described by their Fourier spectra, that can potentially reveal the mechanisms that generate them. Extracting this information from measured signals is interesting for the validation of theoretical models, discovery and classification of interaction types, and for optimal experiment design. An automated workflow is described for the analysis of oscillating signals. A software package is developed to match signal shapes to hundreds of a priori viable model structures defined by a class of first-order differential equations. The package computes parameter values for each model by exploiting the mode decomposition of oscillating signals and formulating the matching problem in terms of systems of simultaneous polynomial equations. On the basis of the computed parameter values, the software returns a list of models consistent with the data. In validation tests with synthetic datasets, it not only shortlists those model structures used to generate the data but also shows that excellent fits can sometimes be achieved with alternative equations. The listing of all consistent equations is indicative of how further invalidation might be achieved with additional information. When applied to data from a microarray experiment on mice, the procedure finds several candidate model structures to describe interactions related to the circadian rhythm. This shows that experimental data on oscillators is indeed rich in information about gene regulation mechanisms. The software package is available at http://babylone.ulb.ac.be/autoosc/.

Reliability and Characteristics of Wafer-Level Chip-Scale Packages under Current Stress

NASA Astrophysics Data System (ADS)

Chen, Po-Ying; Kung, Heng-Yu; Lai, Yi-Shao; Hsiung Tsai, Ming; Yeh, Wen-Kuan

2008-02-01

In this work, we present a novel approach and method for elucidating the characteristics of wafer-level chip-scale packages (WLCSPs) for electromigration (EM) tests. The die in WLCSP was directly attached to the substrate via a soldered interconnect. The shrinking of the area of the die that is available for power, and the solder bump also shrinks the volume and increases the density of electrons for interconnect efficiency. The bump current density now approaches to 106 A/cm2, at which point the EM becomes a significant reliability issue. As known, the EM failure depends on numerous factors, including the working temperature and the under bump metallization (UBM) thickness. A new interconnection geometry is adopted extensively with moderate success in overcoming larger mismatches between the displacements of components during current and temperature changes. Both environments and testing parameters for WLCSP are increasingly demanded. Although failure mechanisms are considered to have been eliminated or at least made manageable, new package technologies are again challenging its process, integrity and reliability. WLCSP technology was developed to eliminate the need for encapsulation to ensure compatibility with smart-mount technology (SMT). The package has good handing properties but is now facing serious reliability problems. In this work, we investigated the reliability of a WLCSP subjected to different accelerated current stressing conditions at a fixed ambient temperature of 125 °C. A very strong correlation exists between the mean time to failure (MTTF) of the WLCSP test vehicle and the mean current density that is carried by a solder joint. A series of current densities were applied to the WLCSP architecture; Black's power law was employed in a failure mode simulation. Additionally, scanning electron microscopy (SEM) was adopted to determine the differences existing between high- and low-current-density failure modes.

Modeling Antimicrobial Activity of Clorox(R) Using an Agar-Diffusion Test: A New Twist On an Old Experiment.

ERIC Educational Resources Information Center

Mitchell, James K.; Carter, William E.

2000-01-01

Describes using a computer statistical software package called Minitab to model the sensitivity of several microbes to the disinfectant NaOCl (Clorox') using the Kirby-Bauer technique. Each group of students collects data from one microbe, conducts regression analyses, then chooses the best-fit model based on the highest r-values obtained.…

Phase-field modeling of diffusional phase behaviors of solid surfaces: A case study of phase-separating Li XFePO 4 electrode particles

DOE PAGES

Heo, Tae Wook; Chen, Long-Qing; Wood, Brandon C.

2015-04-08

In this paper, we present a comprehensive phase-field model for simulating diffusion-mediated kinetic phase behaviors near the surface of a solid particle. The model incorporates elastic inhomogeneity and anisotropy, diffusion mobility anisotropy, interfacial energy anisotropy, and Cahn–Hilliard diffusion kinetics. The free energy density function is formulated based on the regular solution model taking into account the possible solute-surface interaction near the surface. The coherency strain energy is computed using the Fourier-spectral iterative-perturbation method due to the strong elastic inhomogeneity with a zero surface traction boundary condition. Employing a phase-separating Li XFePO 4 electrode particle for Li-ion batteries as a modelmore » system, we perform parametric three-dimensional computer simulations. The model permits the observation of surface phase behaviors that are different from the bulk counterpart. For instance, it reproduces the theoretically well-established surface modes of spinodal decomposition of an unstable solid solution: the surface mode of coherent spinodal decomposition and the surface-directed spinodal decomposition mode. We systematically investigate the influences of major factors on the kinetic surface phase behaviors during the diffusional process. Finally, our simulation study provides insights for tailoring the internal phase microstructure of a particle by controlling the surface phase morphology.« less

A Two Species Bump-On-Tail Model With Relaxation for Energetic Particle Driven Modes

NASA Astrophysics Data System (ADS)

Aslanyan, V.; Porkolab, M.; Sharapov, S. E.; Spong, D. A.

2017-10-01

Energetic particle driven Alfvén Eigenmodes (AEs) observed in present day experiments exhibit various nonlinear behaviours varying from steady state amplitude at a fixed frequency to bursting amplitudes and sweeping frequency. Using the appropriate action-angle variables, the problem of resonant wave-particle interaction becomes effectively one-dimensional. Previously, a simple one-dimensional Bump-On-Tail (BOT) model has proven to be one of the most effective in describing characteristic nonlinear near-threshold wave evolution scenarios. In particular, dynamical friction causes bursting mode evolution, while diffusive relaxation may give steady-state, periodic or chaotic mode evolution. BOT has now been extended to include two populations of fast particles, with one dominated by dynamical friction at the resonance and the other by diffusion; the relative size of the populations determines the temporal evolution of the resulting wave. This suggests an explanation for recent observations on the TJ-II stellarator, where a transition between steady state and bursting occured as the magnetic configuration varied. The two species model is then applied to burning plasma with drag-dominated alpha particles and diffusion-dominated ICRH accelerated minority ions. This work was supported by the US DoE and the RCUK Energy Programme [Grant Number EP/P012450/1].

Comparison of Absolute Apparent Diffusion Coefficient (ADC) Values in ADC Maps Generated Across Different Postprocessing Software: Reproducibility in Endometrial Carcinoma.

PubMed

Ghosh, Adarsh; Singh, Tulika; Singla, Veenu; Bagga, Rashmi; Khandelwal, Niranjan

2017-12-01

Apparent diffusion coefficient (ADC) maps are usually generated by builtin software provided by the MRI scanner vendors; however, various open-source postprocessing software packages are available for image manipulation and parametric map generation. The purpose of this study is to establish the reproducibility of absolute ADC values obtained using different postprocessing software programs. DW images with three b values were obtained with a 1.5-T MRI scanner, and the trace images were obtained. ADC maps were automatically generated by the in-line software provided by the vendor during image generation and were also separately generated on postprocessing software. These ADC maps were compared on the basis of ROIs using paired t test, Bland-Altman plot, mountain plot, and Passing-Bablok regression plot. There was a statistically significant difference in the mean ADC values obtained from the different postprocessing software programs when the same baseline trace DW images were used for the ADC map generation. For using ADC values as a quantitative cutoff for histologic characterization of tissues, standardization of the postprocessing algorithm is essential across processing software packages, especially in view of the implementation of vendor-neutral archiving.

Coupling of light into the fundamental diffusion mode of a scattering medium (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ojambati, Oluwafemi S.; Yılmaz, Hasan; Lagendijk, Ad; Mosk, Allard P.; Vos, Willem L.

2016-03-01

Diffusion equation describes the energy density inside a scattering medium such as biological tissues and paint [1]. The solution of the diffusion equation is a sum over a complete set of eigensolutions that shows a characteristic linear decrease with depth in the medium. It is of particular interest if one could launch energy in the fundamental eigensolution, as this opens the opportunity to achieve a much greater internal energy density. For applications in optics, an enhanced energy density is vital for solid-state lighting, light harvesting in solar cells, low-threshold random lasers, and biomedical optics. Here we demonstrate the first ever selective coupling of optical energy into a diffusion eigensolution of a scattering medium of zinc oxide (ZnO) paint. To this end, we exploit wavefront shaping to selectively couple energy into the fundamental diffusion mode, employing fluorescence of nanoparticles randomly positioned inside the medium as a probe of the energy density. We observe an enhanced fluorescence in case of optimized incident wavefronts, and the enhancement increases with sample thickness, a typical mesoscopic control parameter. We interpret successfully our result by invoking the fundamental eigensolution of the diffusion equation, and we obtain excellent agreement with our observations, even in absence of adjustable parameters [2]. References [1] R. Pierrat, P. Ambichl, S. Gigan, A. Haber, R. Carminati, and R. Rotter, Proc. Natl. Acad. Sci. U.S.A. 111, 17765 (2014). [2] O. S. Ojambati, H. Yilmaz, A. Lagendijk, A. P. Mosk, and W. L. Vos, arXiv:1505.08103.

Method Development for Container Closure Integrity Evaluation via Headspace Gas Ingress by Using Frequency Modulation Spectroscopy.

PubMed

Victor, Ken G; Levac, Lauren; Timmins, Michael; Veale, James

2017-01-01

USP <1207.1> Section 3.5 states that "A deterministic leak test method having the ability to detect leaks at the product's maximum allowable leakage limit is preferred when establishing the inherent integrity of a container-closure system." Ideally, container closure integrity of parenteral packaging would be evaluated by measuring a physical property that is sensitive to the presence of any package defect that breaches package integrity by increasing its leakage above its maximum allowable leakage limit. The primary goals of the work presented herein were to demonstrate the viability of the nondestructive, deterministic method known as laser-based gas headspace analysis for evaluating container closure integrity and to provide a physical model for predicting leak rates for a variety of container volumes, headspace conditions, and defect sizes. The results demonstrate that laser-based headspace analysis provides sensitive, accurate, and reproducible measurements of the gas ingress into glass vial-stopper package assemblies that are under either diffusive or effusive leak conditions. Two different types of positive controls were examined. First, laser-drilled micro-holes in thin metal disks that were crimped on top of 15R glass vials served as positive controls with a well-characterized defect geometry. For these, a strong correlation was observed between the measured ingress parameter and the size of the defect for both diffusive and effusive conditions. Second, laser-drilled holes in the wall of glass vials served as controls that more closely simulate real-world defects. Due to their complex defect geometries, their diffusive and effusive ingress parameters did not necessarily correlate; this is an important observation that has significant implications for standardizing the characterization of container defects. Regardless, laser-based headspace analysis could readily differentiate positive and negative controls for all leak conditions, and the results provide a guide for method development of container closure integrity tests. LAY ABSTRACT: The new USP 39 <1207>, "Package Integrity Evaluation-Sterile Products", states in section 3.4.1: "tracer gas tests performed using … laser-based gas headspace analysis [have] been shown to be sensitive enough to quantitatively analyze leakage through the smallest leak paths found to pose the smallest chance of liquid leakage or microbial ingress in rigid packaging." In addition, USP <1207> also states that "for such methods, the limit of detection can be mathematically predicted on the basis of gas flow kinetics." Using the above statements as a foundation, this paper presents a theoretical basis for predicting the gas ingress through well-defined defects in product vials sealed under a variety of headspace conditions. These calculated predictions were experimentally validated by comparing them to measurements of changes in the headspace oxygen content or total pressure for several different positive controls using laser-based headspace analysis. The results demonstrated that laser-based headspace analysis can, by readily differentiating between negative controls and positive controls with a range of defect sizes on the micron scale, be used to assess container closure integrity. The work also demontrated that caution must be used when attempting to correlate a leak rate to an idealized defect-size parameter. © PDA, Inc. 2017.

RSEIS and RFOC: Seismic Analysis in R

NASA Astrophysics Data System (ADS)

Lees, J. M.

2015-12-01

Open software is essential for reproducible scientific exchange. R-packages provide a platform for development of seismological investigation software that can be properly documented and traced for data processing. A suite of R packages designed for a wide range of seismic analysis is currently available in the free software platform called R. R is a software platform based on the S-language developed at Bell Labs decades ago. Routines in R can be run as standalone function calls, or developed in object-oriented mode. R comes with a base set of routines, and thousands of user developed packages. The packages developed at UNC include subroutines and interactive codes for processing seismic data, analyzing geographic information (GIS) and inverting data involved in a variety of geophysical applications. On CRAN (Comprehensive R Archive Network, http://www.r-project.org/) currently available packages related to seismic analysis are RSEIS, Rquake, GEOmap, RFOC, zoeppritz, RTOMO, and geophys, Rwave, PEIP, hht, rFDSN. These include signal processing, data management, mapping, earthquake location, deconvolution, focal mechanisms, wavelet transforms, Hilbert-Huang Transforms, tomographic inversion, and Mogi deformation among other useful functionality. All software in R packages is required to have detailed documentation, making the exchange and modification of existing software easy. In this presentation, I will focus on packages RSEIS and RFOC, showing examples from a variety of seismic analyses. The R approach has similarities to the popular (and expensive) MATLAB platform, although R is open source and free to down load.

Application of Lemongrass Oil-Containing Polylactic Acid Films to the Packaging of Pork Sausages.

PubMed

Yang, Hyun-Ju; Song, Kyung Bin

2016-01-01

Polylactic acid (PLA) is a biodegradable and renewable polymer, which represents a valuable alternative to plastic packaging films, often associated with environmental problems. In this study, we tested the suitability of PLA as a biodegradable packaging film and assessed the antimicrobial activity of lemongrass oil (LO), incorporated into the PLA film in different concentrations. To obtain the optimal physical properties for PLA films, tensile strength, elongation at break, and water vapor permeability were measured under different preparation conditions. In addition, the antimicrobial activity of the LO contained in the PLA film against Listeria monocytogenes was investigated by disc diffusion and viable cell count. Among all concentrations tested, 2% LO was the most suitable in terms of antimicrobial activity and physical properties of the PLA film. Based on these results, we used the PLA film containing 2% LO to pack pork sausages; after 12 d of storage at 4℃, the population of inoculated L. monocytogenes in the sausage samples wrapped with the PLA film containing 2% LO was reduced by 1.47 Log CFU/g compared with the control samples. Our data indicate that PLA films containing 2% LO represent a valuable means for antimicrobial sausage packaging.

Application of Lemongrass Oil-Containing Polylactic Acid Films to the Packaging of Pork Sausages

PubMed Central

2016-01-01

Polylactic acid (PLA) is a biodegradable and renewable polymer, which represents a valuable alternative to plastic packaging films, often associated with environmental problems. In this study, we tested the suitability of PLA as a biodegradable packaging film and assessed the antimicrobial activity of lemongrass oil (LO), incorporated into the PLA film in different concentrations. To obtain the optimal physical properties for PLA films, tensile strength, elongation at break, and water vapor permeability were measured under different preparation conditions. In addition, the antimicrobial activity of the LO contained in the PLA film against Listeria monocytogenes was investigated by disc diffusion and viable cell count. Among all concentrations tested, 2% LO was the most suitable in terms of antimicrobial activity and physical properties of the PLA film. Based on these results, we used the PLA film containing 2% LO to pack pork sausages; after 12 d of storage at 4℃, the population of inoculated L. monocytogenes in the sausage samples wrapped with the PLA film containing 2% LO was reduced by 1.47 Log CFU/g compared with the control samples. Our data indicate that PLA films containing 2% LO represent a valuable means for antimicrobial sausage packaging. PMID:27433114

Influence of Food with High Moisture Content on Oxygen Barrier Property of Polyvinyl Alcohol (PVA)/Vermiculite Nanocomposite Coated Multilayer Packaging Film.

PubMed

Kim, Jung Min; Lee, Min Hyeock; Ko, Jung A; Kang, Dong Ho; Bae, Hojae; Park, Hyun Jin

2018-02-01

This study investigates the potential complications in applying nanoclay-based waterborne coating to packaging films for food with high moisture content. Multilayer packaging films were prepared by dry laminating commercially available polyvinyl alcohol (PVA)/vermiculite nanocomposite coating films and linear low-density polyethylene film, and the changes in oxygen barrier properties were investigated according to different relative humidity using 3 types of food simulants. When the relative humidity was above 60%, the oxygen permeability increased sharply, but this was reversible. Deionized water and 3% acetic acid did not cause any large structural change in the PVA/vermiculite nanocomposite but caused a reversible deterioration of the oxygen barrier properties. In contrast, 50% ethanol, a simulant for the semifatty food, induced irreversible structural changes with deterioration of the oxygen barrier property. These changes are due to the characteristics of PVA rather than vermiculite. We believe this manuscript would be of interest to the wide group of researchers, organizations, and companies in the field of developing nanoclay-based gas barrier packaging for foods with high moisture content. Hence, we wish to diffuse our knowledge to the scientific community. © 2018 Institute of Food Technologists®.

Evaporation kinetics of sessile water droplets on micropillared superhydrophobic surfaces.

PubMed

Xu, Wei; Leeladhar, Rajesh; Kang, Yong Tae; Choi, Chang-Hwan

2013-05-21

Evaporation modes and kinetics of sessile droplets of water on micropillared superhydrophobic surfaces are experimentally investigated. The results show that a constant contact radius (CCR) mode and a constant contact angle (CCA) mode are two dominating evaporation modes during droplet evaporation on the superhydrophobic surfaces. With the decrease in the solid fraction of the superhydrophobic surfaces, the duration of a CCR mode is reduced and that of a CCA mode is increased. Compared to Rowan's kinetic model, which is based on the vapor diffusion across the droplet boundary, the change in a contact angle in a CCR (pinned) mode shows a remarkable deviation, decreasing at a slower rate on the superhydrophobic surfaces with less-solid fractions. In a CCA (receding) mode, the change in a contact radius agrees well with the theoretical expectation, and the receding speed is slower on the superhydrophobic surfaces with lower solid fractions. The discrepancy between experimental results and Rowan's model is attributed to the initial large contact angle of a droplet on superhydrophobic surfaces. The droplet geometry with a large contact angle results in a narrow wedge region of air along the contact boundary, where the liquid-vapor diffusion is significantly restricted. Such an effect becomes minor as the evaporation proceeds with the decrease in a contact angle. In both the CCR and CCA modes, the evaporative mass transfer shows the linear relationship between mass(2/3) and evaporation time. However, the evaporation rate is slower on the superhydrophobic surfaces, which is more significant on the surfaces with lower solid fractions. As a result, the superhydrophobic surfaces slow down the drying process of a sessile droplet on them.

Facilitated diffusion in chromatin lattices: mechanistic diversity and regulatory potential.

PubMed

Kampmann, Martin

2005-08-01

The interaction between a protein and a specific DNA site is the molecular basis for vital processes in all organisms. Location of the DNA target site by the protein commonly involves facilitated diffusion. Mechanisms of facilitated diffusion vary among proteins; they include one- and two-dimensional sliding along DNA, direct transfer between uncorrelated sites, as well as combinations of these mechanisms. Facilitated diffusion has almost exclusively been studied in vitro. This review discusses facilitated diffusion in the context of the living cell and proposes a theoretical model for facilitated diffusion in chromatin lattices. Chromatin structure differentially affects proteins in different modes of diffusion. The interplay of facilitated diffusion and chromatin structure can determine the rate of protein association with the target site, the frequency of association-dissociation events at the target site, and, under particular conditions, the occupancy of the target site. Facilitated diffusion is required in vivo for efficient DNA repair and bacteriophage restriction and has potential roles in fine-tuning gene regulatory networks and kinetically compartmentalizing the eukaryotic nucleus.

Scalability of Robotic Controllers: Effects of Progressive Autonomy on Intelligence, Surveillance, and Reconnaissance Robotic Tasks

DTIC Science & Technology

2012-09-01

away from the MOCU. The semi-autonomous mode was preferred over the teleoperated mode for multitasking , maintaining SA, avoiding obstacles, and...0 23 Software with icons 0 0 0 0 2 25 Pull-down menu * 0 0 0 0 3 24 Graphics/drawing features in software packages* 3 8 1 4 3 8 Email 1 0 0 0 1...r. Navigate to the next waypoint or set of hash lines 5.27 5.08 6.25 s. Ability to multitask (operate/monitor robot and communicate on the radio

High Coherence Qubit packaging

NASA Astrophysics Data System (ADS)

Pappas, David P.; Wu, Xian; Olivadese, Salvatore B.; Adiga, V. P.; Hertzberg, Jared B.; Bronn, Nicholas T.; Chow, Jerry M.; NIST Team; IBM Team

Development of sockets and associated interconnects for multi-qubit chips is presented. Considerations include thermalization, RF hygiene, non-magnetic environment, and self-alignment of the chips to allow for rapid testing, scalable integration, and high coherence operation. The sockets include wirebond free, vertical take-off launches with pogopins. This allows for high interconnectivity to non-trivial topology of qubits. Furthermore, vertical grounding is accomplished to reduce chip modes and suppress box modes. Low energy loss and high phase coherence is observed using this paradigm. We acknowledge support from IARPA, LPS, and the NIST Quantum Based Metrology Initiative.

Spectroscopic Signatures for Interlayer Coupling in MoS2-WSe2 van der Waals Stacking

DTIC Science & Technology

2014-09-07

theory (DFPT) calculations were carried out using the plane wave code CASTEP as implemented in the Materials Studio package .38 A hexagonal unit cell...transition metal dichalcogenide (TMD) monolayers. The layer-number sensitive Raman out -of-plane mode A2 1g for WSe2 (309 cm1) is found sensitive to the...Raman out -of-plane mode A2 1g for WSe2 (309 cm1) is found sensitive to the coupling between two TMD monolayers. The presence of interlayer excitonic

MAIL LOG, program summary and specifications

NASA Technical Reports Server (NTRS)

Harris, D. K.

1979-01-01

The summary and specifications to obtain the software package, MAIL LOG, developed for the Scout Project Automatic Data System, SPADS are provided. The MAIL LOG program has four modes of operation: (1) input - putting new records into the data base; (2) revise - changing or modifying existing records in the data base; (3) search - finding special records existing in the data base; and (4) archive - store or put away existing records in the data base. The output includes special printouts of records in the data base and results from the input and search modes.

Charged scalar perturbations on charged black holes in de Rham-Gabadadze-Tolley massive gravity

NASA Astrophysics Data System (ADS)

Burikham, Piyabut; Ponglertsakul, Supakchai; Tannukij, Lunchakorn

2017-12-01

We explore the quasistationary profile of a massive charged scalar field in a class of charged black holes in de Rham-Gabadadze-Tolley (dRGT) massive gravity. We discuss how the linear term in the metric, which is a unique character of the dRGT massive gravity, affects the structure of the spacetime. Numerical calculations of the quasinormal modes are performed for a charged scalar field in the dRGT black hole background. For an asymptotically de Sitter (dS) black hole, an improved asymptotic iteration method is used to obtain the associated quasinormal frequencies. The unstable modes are found for the ℓ=0 case, and their corresponding real parts satisfy the superradiant condition. For ℓ=2 , the results show that all the de Sitter black holes considered here are stable against a small perturbation. For an asymptotically dRGT anti-de Sitter (AdS) black hole, unstable modes are found with the frequency satisfying the superradiant condition. Effects of massive-gravity parameters are discussed. Analytic calculation reveals the unique diffusive nature of quasinormal modes in the massive-gravity model with the linear term. Numerical results confirm the existence of the characteristic diffusive modes in both the dS and AdS cases.

Promoting Intrinsic and Extrinsic Motivation among Chemistry Students Using Computer-Assisted Instruction

ERIC Educational Resources Information Center

Gambari, Isiaka A.; Gbodi, Bimpe E.; Olakanmi, Eyitao U.; Abalaka, Eneojo N.

2016-01-01

The role of computer-assisted instruction in promoting intrinsic and extrinsic motivation among Nigerian secondary school chemistry students was investigated in this study. The study employed two modes of computer-assisted instruction (computer simulation instruction and computer tutorial instructional packages) and two levels of gender (male and…

21 CFR 880.2800 - Sterilization process indicator.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Sterilization process indicator. 880.2800 Section 880.2800 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... resistance to the mode of sterilization, in or on a carrier and enclosed in a protective package. Subsequent...

21 CFR 880.2800 - Sterilization process indicator.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Sterilization process indicator. 880.2800 Section 880.2800 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... resistance to the mode of sterilization, in or on a carrier and enclosed in a protective package. Subsequent...

78 FR 43268 - Special Permit Applications

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-19

... certain packagings for spent lithium ion batteries that have not been tested in accordance with the UN... authorize the Cupertino, CA. 173.185(a). transportation in commerce of damaged or defective lithium ion batteries that do not meet the requirements of Sec. 173.185(a) (modes 1, 3) 15827-N......... Advanced 49 CFR...

Diffuse Vibrational Signature of a Single Proton Embedded in the Oxalate Scaffold, HO2CCO2(-).

PubMed

Wolke, Conrad T; DeBlase, Andrew F; Leavitt, Christopher M; McCoy, Anne B; Johnson, Mark A

2015-12-31

To understand how the D2d oxalate scaffold (C2O4)(2-) distorts upon capture of a proton, we report the vibrational spectra of the cryogenically cooled HO2CCO2(-) anion and its deuterated isotopologue DO2CCO2(-). The transitions associated with the skeletal vibrations and OH bending modes are sharp and are well described by inclusion of cubic terms in the normal mode expansion of the potential surface through an extended Fermi resonance analysis. The ground state structure features a five-membered ring with an asymmetric intramolecular proton bond. The spectral signatures of the hydrogen stretches, on the contrary, are surprisingly diffuse, and this behavior is not anticipated by the extended Fermi scheme. We trace the diffuse bands to very strong couplings between the high-frequency OH-stretch and the low-frequency COH bends as well as heavy particle skeletal deformations. A simple vibrationally adiabatic model recovers this breadth of oscillator strength as a 0 K analogue of the motional broadening commonly used to explain the diffuse spectra of H-bonded systems at elevated temperatures, but where these displacements arise from the configurations present at the vibrational zero-point level.

Autocrine signal transmission with extracellular ligand degradation

NASA Astrophysics Data System (ADS)

Muratov, C B; Posta, F; Shvartsman, S Y

2009-03-01

Traveling waves of cell signaling in epithelial layers orchestrate a number of important processes in developing and adult tissues. These waves can be mediated by positive feedback autocrine loops, a mode of cell signaling where binding of a diffusible extracellular ligand to a cell surface receptor can lead to further ligand release. We formulate and analyze a biophysical model that accounts for ligand-induced ligand release, extracellular ligand diffusion and ligand-receptor interaction. We focus on the case when the main mode for ligand degradation is extracellular and analyze the problem with the sharp threshold positive feedback nonlinearity. We derive expressions that link the speed of propagation and other characteristics of traveling waves to the parameters of the biophysical processes, such as diffusion rates, receptor expression level, etc. Analyzing the derived expressions we found that traveling waves in such systems can exhibit a number of unusual properties, e.g. non-monotonic dependence of the speed of propagation on ligand diffusivity. Our results for the fully developed traveling fronts can be used to analyze wave initiation from localized perturbations, a scenario that frequently arises in the in vitro models of epithelial wound healing, and guide future modeling studies of cell communication in epithelial layers.

Minority carrier diffusion and defects in InGaAsN grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Kurtz, Steven R.; Klem, J. F.; Allerman, A. A.; Sieg, R. M.; Seager, C. H.; Jones, E. D.

2002-02-01

To gain insight into the nitrogen-related defects of InGaAsN, nitrogen vibrational mode spectra, Hall mobilities, and minority carrier diffusion lengths are examined for InGaAsN (1.1 eV band gap) grown by molecular beam epitaxy (MBE). Annealing promotes the formation of In-N bonding, and lateral carrier transport is limited by large scale (≫mean free path) material inhomogeneities. Comparing solar cell quantum efficiencies with our earlier results for devices grown by metalorganic chemical vapor deposition (MOCVD), we find significant electron diffusion in the MBE material (reversed from the hole diffusion in MOCVD material), and minority carrier diffusion in InGaAsN cannot be explained by a "universal," nitrogen-related defect.

QMCPACK : an open source ab initio quantum Monte Carlo package for the electronic structure of atoms, molecules and solids

DOE PAGES

Kim, Jeongnim; Baczewski, Andrew T.; Beaudet, Todd D.; ...

2018-04-19

QMCPACK is an open source quantum Monte Carlo package for ab-initio electronic structure calculations. It supports calculations of metallic and insulating solids, molecules, atoms, and some model Hamiltonians. Implemented real space quantum Monte Carlo algorithms include variational, diffusion, and reptation Monte Carlo. QMCPACK uses Slater-Jastrow type trial wave functions in conjunction with a sophisticated optimizer capable of optimizing tens of thousands of parameters. The orbital space auxiliary field quantum Monte Carlo method is also implemented, enabling cross validation between different highly accurate methods. The code is specifically optimized for calculations with large numbers of electrons on the latest high performancemore » computing architectures, including multicore central processing unit (CPU) and graphical processing unit (GPU) systems. We detail the program’s capabilities, outline its structure, and give examples of its use in current research calculations. The package is available at http://www.qmcpack.org.« less

QMCPACK : an open source ab initio quantum Monte Carlo package for the electronic structure of atoms, molecules and solids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Jeongnim; Baczewski, Andrew T.; Beaudet, Todd D.

QMCPACK is an open source quantum Monte Carlo package for ab-initio electronic structure calculations. It supports calculations of metallic and insulating solids, molecules, atoms, and some model Hamiltonians. Implemented real space quantum Monte Carlo algorithms include variational, diffusion, and reptation Monte Carlo. QMCPACK uses Slater-Jastrow type trial wave functions in conjunction with a sophisticated optimizer capable of optimizing tens of thousands of parameters. The orbital space auxiliary field quantum Monte Carlo method is also implemented, enabling cross validation between different highly accurate methods. The code is specifically optimized for calculations with large numbers of electrons on the latest high performancemore » computing architectures, including multicore central processing unit (CPU) and graphical processing unit (GPU) systems. We detail the program’s capabilities, outline its structure, and give examples of its use in current research calculations. The package is available at http://www.qmcpack.org.« less

Interfacial diffusion aided deformation during nanoindentation

DOE PAGES

Samanta, Amit; E., Weinan

2015-07-06

Nanoindentation is commonly used to quantify the mechanical response of material surfaces. Despite its widespread use, a detailed understanding of the deformation mechanisms responsible for plasticity during these experiments has remained elusive. Nanoindentation measurements often show stress values close to a material’s ideal strength which suggests that dislocation nucleation and subsequent dislocation activity dominates the deformation. However, low strain-rate exponents and small activation volumes have also been reported which indicates high temperature sensitivity of the deformation processes. Using an order parameter aided temperature accelerated sampling technique called adiabatic free energy dynamics [J. B. Abrams and M. E. Tuckerman, J. Phys.more » Chem. B, 112, 15742 (2008)], and molecular dynamics we have probed the diffusive mode of deformation during nanoindentation. Localized processes such as surface vacancy and ad-atom pair formation, vacancy diffusion are found to play an important role during indentation. Furthermore, our analysis suggests a change in the dominant deformation mode from dislocation mediated plasticity to diffusional flow at high temperatures, slow indentation rates and small indenter tip radii.« less

Transition from normal to ballistic diffusion in a one-dimensional impact system

NASA Astrophysics Data System (ADS)

Livorati, André L. P.; Kroetz, Tiago; Dettmann, Carl P.; Caldas, Iberê L.; Leonel, Edson D.

2018-03-01

We characterize a transition from normal to ballistic diffusion in a bouncing ball dynamics. The system is composed of a particle, or an ensemble of noninteracting particles, experiencing elastic collisions with a heavy and periodically moving wall under the influence of a constant gravitational field. The dynamics lead to a mixed phase space where chaotic orbits have a free path to move along the velocity axis, presenting a normal diffusion behavior. Depending on the control parameter, one can observe the presence of featured resonances, known as accelerator modes, that lead to a ballistic growth of velocity. Through statistical and numerical analysis of the velocity of the particle, we are able to characterize a transition between the two regimes, where transport properties were used to characterize the scenario of the ballistic regime. Also, in an analysis of the probability of an orbit to reach an accelerator mode as a function of the velocity, we observe a competition between the normal and ballistic transport in the midrange velocity.

Transition from normal to ballistic diffusion in a one-dimensional impact system.

PubMed

Livorati, André L P; Kroetz, Tiago; Dettmann, Carl P; Caldas, Iberê L; Leonel, Edson D

2018-03-01

We characterize a transition from normal to ballistic diffusion in a bouncing ball dynamics. The system is composed of a particle, or an ensemble of noninteracting particles, experiencing elastic collisions with a heavy and periodically moving wall under the influence of a constant gravitational field. The dynamics lead to a mixed phase space where chaotic orbits have a free path to move along the velocity axis, presenting a normal diffusion behavior. Depending on the control parameter, one can observe the presence of featured resonances, known as accelerator modes, that lead to a ballistic growth of velocity. Through statistical and numerical analysis of the velocity of the particle, we are able to characterize a transition between the two regimes, where transport properties were used to characterize the scenario of the ballistic regime. Also, in an analysis of the probability of an orbit to reach an accelerator mode as a function of the velocity, we observe a competition between the normal and ballistic transport in the midrange velocity.

MODFLOW-2000 : the U.S. Geological Survey modular ground-water model--documentation of the Advective-Transport Observation (ADV2) Package

USGS Publications Warehouse

Anderman, Evan R.; Hill, Mary Catherine

2001-01-01

Observations of the advective component of contaminant transport in steady-state flow fields can provide important information for the calibration of ground-water flow models. This report documents the Advective-Transport Observation (ADV2) Package, version 2, which allows advective-transport observations to be used in the three-dimensional ground-water flow parameter-estimation model MODFLOW-2000. The ADV2 Package is compatible with some of the features in the Layer-Property Flow and Hydrogeologic-Unit Flow Packages, but is not compatible with the Block-Centered Flow or Generalized Finite-Difference Packages. The particle-tracking routine used in the ADV2 Package duplicates the semi-analytical method of MODPATH, as shown in a sample problem. Particles can be tracked in a forward or backward direction, and effects such as retardation can be simulated through manipulation of the effective-porosity value used to calculate velocity. Particles can be discharged at cells that are considered to be weak sinks, in which the sink applied does not capture all the water flowing into the cell, using one of two criteria: (1) if there is any outflow to a boundary condition such as a well or surface-water feature, or (2) if the outflow exceeds a user specified fraction of the cell budget. Although effective porosity could be included as a parameter in the regression, this capability is not included in this package. The weighted sum-of-squares objective function, which is minimized in the Parameter-Estimation Process, was augmented to include the square of the weighted x-, y-, and z-components of the differences between the simulated and observed advective-front locations at defined times, thereby including the direction of travel as well as the overall travel distance in the calibration process. The sensitivities of the particle movement to the parameters needed to minimize the objective function are calculated for any particle location using the exact sensitivity-equation approach; the equations are derived by taking the partial derivatives of the semi-analytical particle-tracking equation with respect to the parameters. The ADV2 Package is verified by showing that parameter estimation using advective-transport observations produces the true parameter values in a small but complicated test case when exact observations are used. To demonstrate how the ADV2 Package can be used in practice, a field application is presented. In this application, the ADV2 Package is used first in the Sensitivity-Analysis mode of MODFLOW-2000 to calculate measures of the importance of advective-transport observations relative to head-dependent flow observations when either or both are used in conjunction with hydraulic-head observations in a simulation of the sewage-discharge plume at Cape Cod, Massachusetts. The ADV2 Package is then used in the Parameter-Estimation mode of MODFLOW-2000 to determine best-fit parameter values. It is concluded that, for this problem, advective-transport observations improved the calibration of the model and the estimation of ground-water flow parameters, and the use of formal parameter-estimation methods and related techniques produced significant insight into the physical system.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bornea, A.; Zamfirache, M.; Stefan, L.

ICIT (Institute for Cryogenics and Isotopic Technologies) has used its experience in cryogenic water distillation process to propose a similar process for hydrogen distillation that can be used in detritiation technologies. This process relies on the same packages but a stainless filling is tested instead of the phosphorous bronze filling used for water distillation. This paper presents two types of packages developed for hydrogen distillation, both have a stainless filling but it differs in terms of density, exchange surface and specific volume. Performance data have been obtained on laboratory scale. In order to determine the characteristics of the package, themore » installation was operated in the total reflux mode, for different flow rate for the liquid. There were made several experiments considering different operating conditions. Samples extracted at the top and bottom of cryogenic distillation column allowed mathematical processing to determine the separation performance. The experiments show a better efficiency for the package whose exchange surface was higher and there were no relevant differences between both packages as the operating pressure of the cryogenic column was increasing. For a complete characterization of the packages, future experiments will be considered to determine performance at various velocities in the column and their correlation with the pressure in the column. We plan further experiments to separate tritium from the mixture of isotopes DT, having in view that our goal is to apply this results to a detritiation plant.« less

Gallic Acid as an Oxygen Scavenger in Bio-Based Multilayer Packaging Films

PubMed Central

Pant, Astrid F.; Sängerlaub, Sven; Müller, Kajetan

2017-01-01

Oxygen scavengers are used in food packaging to protect oxygen-sensitive food products. A mixture of gallic acid (GA) and sodium carbonate was used as an oxygen scavenger (OSc) in bio-based multilayer packaging films produced in a three-step process: compounding, flat film extrusion, and lamination. We investigated the film surface color as well as oxygen absorption at different relative humidities (RHs) and temperatures, and compared the oxygen absorption of OSc powder, monolayer films, and multilayer films. The films were initially brownish-red in color but changed to greenish-black during oxygen absorption under humid conditions. We observed a maximum absorption capacity of 447 mg O2/g GA at 21 °C and 100% RH. The incorporation of GA into a polymer matrix reduced the rate of oxygen absorption compared to the GA powder because the polymer acted as a barrier to oxygen and water vapor diffusion. As expected, the temperature had a significant effect on the initial absorption rate of the multilayer films; the corresponding activation energy was 75.4 kJ/mol. Higher RH significantly increased the oxygen absorption rate. These results demonstrate for the first time the production and the properties of a bio-based multilayer packaging film with GA as the oxygen scavenger. Potential applications include the packaging of food products with high water activity (aw > 0.86). PMID:28772849

Gallic Acid as an Oxygen Scavenger in Bio-Based Multilayer Packaging Films.

PubMed

Pant, Astrid F; Sängerlaub, Sven; Müller, Kajetan

2017-05-03

Oxygen scavengers are used in food packaging to protect oxygen-sensitive food products. A mixture of gallic acid (GA) and sodium carbonate was used as an oxygen scavenger (OSc) in bio-based multilayer packaging films produced in a three-step process: compounding, flat film extrusion, and lamination. We investigated the film surface color as well as oxygen absorption at different relative humidities (RHs) and temperatures, and compared the oxygen absorption of OSc powder, monolayer films, and multilayer films. The films were initially brownish-red in color but changed to greenish-black during oxygen absorption under humid conditions. We observed a maximum absorption capacity of 447 mg O₂/g GA at 21 °C and 100% RH. The incorporation of GA into a polymer matrix reduced the rate of oxygen absorption compared to the GA powder because the polymer acted as a barrier to oxygen and water vapor diffusion. As expected, the temperature had a significant effect on the initial absorption rate of the multilayer films; the corresponding activation energy was 75.4 kJ/mol. Higher RH significantly increased the oxygen absorption rate. These results demonstrate for the first time the production and the properties of a bio-based multilayer packaging film with GA as the oxygen scavenger. Potential applications include the packaging of food products with high water activity (a w > 0.86).

Design, Fabrication, and Packaging of Mach-Zehnder Interferometers for Biological Sensing Applications

NASA Astrophysics Data System (ADS)

Novak, Joseph

Optical biological sensors are widely used in the fields of medical testing, water treatment and safety, gene identification, and many others due to advances in nanofabrication technology. This work focuses on the design of fiber-coupled Mach-Zehnder Interferometer (MZI) based biosensors fabricated on silicon-on-insulator (SOI) wafer. Silicon waveguide sensors are designed with multimode and single-mode dimensions. Input coupling efficiency is investigated by design of various taper structures. Integration processing and packaging is performed for fiber attachment and enhancement of input coupling efficiency. Optical guided-wave sensors rely on single-mode operation to extract an induced phase-shift from the output signal. A silicon waveguide MZI sensor designed and fabricated for both multimode and single-mode dimensions. Sensitivity of the sensors is analyzed for waveguide dimensions and materials. An s-bend structure is designed for the multimode waveguide to eliminate higher-order mode power as an alternative to single-mode confinement. Single-mode confinement is experimentally demonstrated through near field imaging of waveguide output. Y-junctions are designed for 3dB power splitting to the MZI arms and for power recombination after sensing to utilize the interferometric function of the MZI. Ultra-short 10microm taper structures with curved geometries are designed to improve insertion loss from fiber-to-chip without significantly increasing device area and show potential for applications requiring misalignment tolerance. An novel v-groove process is developed for self-aligned integration of fiber grooves for attachment to sensor chips. Thermal oxidation at temperatures from 1050-1150°C during groove processing creates an SiO2 layer on the waveguide end facet to protect the waveguide facet during integration etch processing without additional e-beam lithography processing. Experimental results show improvement of insertion loss compared to dicing preparation and Focused Ion Beam methods using the thermal oxidation process.

Using the Schur Complement to Reduce Runtime in KULL's Magnetic Diffusion Package

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brunner, T A; Kolev, T V

2010-12-15

Recently a Resistive Magnetohydrodynamics (MHD) package has been added to the KULL code. In order to be compatible with the underlying hydrodynamics algorithm, a new sub-zonal magnetics discretization was developed that supports arbitrary polygonal and polyhedral zones. This flexibility comes at the cost of many more unknowns per zone - approximately ten times more for a hexahedral mesh. We can eliminate some (or all, depending on the dimensionality) of the extra unknowns from the global matrix during assembly by using a Schur complement approach. This trades expensive global work for cache-friendly local work, while still allowing solution for the fullmore » system. Significant improvements in the solution time are observed for several test problems.« less

Using a two-step matrix solution to reduce the run time in KULL's magnetic diffusion package

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brunner, T A; Kolev, T V

2010-12-17

Recently a Resistive Magnetohydrodynamics (MHD) package has been added to the KULL code. In order to be compatible with the underlying hydrodynamics algorithm, a new sub-zonal magnetics discretization was developed that supports arbitrary polygonal and polyhedral zones. This flexibility comes at the cost of many more unknowns per zone - approximately ten times more for a hexahedral mesh. We can eliminate some (or all, depending on the dimensionality) of the extra unknowns from the global matrix during assembly by using a Schur complement approach. This trades expensive global work for cache-friendly local work, while still allowing solution for the fullmore » system. Significant improvements in the solution time are observed for several test problems.« less

Survivability design for a hybrid underwater vehicle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Biao; Wu, Chao; Li, Xiang

A novel hybrid underwater robotic vehicle (HROV) capable of working to the full ocean depth has been developed. The battery powered vehicle operates in two modes: operate as an untethered autonomous vehicle in autonomous underwater vehicle (AUV) mode and operate under remote control connected to the surface vessel by a lightweight, fiber optic tether in remotely operated vehicle (ROV) mode. Considering the hazardous underwater environment at the limiting depth and the hybrid operating modes, survivability has been placed on an equal level with the other design attributes of the HROV since the beginning of the project. This paper reports themore » survivability design elements for the HROV including basic vehicle design of integrated navigation and integrated communication, emergency recovery strategy, distributed architecture, redundant bus, dual battery package, emergency jettison system and self-repairing control system.« less

Sandwich-Architectured Poly(lactic acid)-Graphene Composite Food Packaging Films.

PubMed

Goh, Kunli; Heising, Jenneke K; Yuan, Yang; Karahan, Huseyin E; Wei, Li; Zhai, Shengli; Koh, Jia-Xuan; Htin, Nanda M; Zhang, Feimo; Wang, Rong; Fane, Anthony G; Dekker, Matthijs; Dehghani, Fariba; Chen, Yuan

2016-04-20

Biodegradable food packaging promises a more sustainable future. Among the many different biopolymers used, poly(lactic acid) (PLA) possesses the good mechanical property and cost-effectiveness necessary of a biodegradable food packaging. However, PLA food packaging suffers from poor water vapor and oxygen barrier properties compared to many petroleum-derived ones. A key challenge is, therefore, to simultaneously enhance both the water vapor and oxygen barrier properties of the PLA food packaging. To address this issue, we design a sandwich-architectured PLA-graphene composite film, which utilizes an impermeable reduced graphene oxide (rGO) as the core barrier and commercial PLA films as the outer protective encapsulation. The synergy between the barrier and the protective encapsulation results in a significant 87.6% reduction in the water vapor permeability. At the same time, the oxygen permeability is reduced by two orders of magnitude when evaluated under both dry and humid conditions. The excellent barrier properties can be attributed to the compact lamellar microstructure and the hydrophobicity of the rGO core barrier. Mechanistic analysis shows that the large rGO lateral dimension and the small interlayer spacing between the rGO sheets have created an extensive and tortuous diffusion pathway, which is up to 1450-times the thickness of the rGO barrier. In addition, the sandwiched architecture has imbued the PLA-rGO composite film with good processability, which increases the manageability of the film and its competency to be tailored. Simulations using the PLA-rGO composite food packaging film for edible oil and potato chips also exhibit at least eight-fold extension in the shelf life of these oxygen and moisture sensitive food products. Overall, these qualities have demonstrated the high potential of a sandwich-architectured PLA-graphene composite film for food packaging applications.

An Analytical Diffusion–Expansion Model for Forbush Decreases Caused by Flux Ropes

NASA Astrophysics Data System (ADS)

Dumbović, Mateja; Heber, Bernd; Vršnak, Bojan; Temmer, Manuela; Kirin, Anamarija

2018-06-01

We present an analytical diffusion–expansion Forbush decrease (FD) model ForbMod, which is based on the widely used approach of an initially empty, closed magnetic structure (i.e., flux rope) that fills up slowly with particles by perpendicular diffusion. The model is restricted to explaining only the depression caused by the magnetic structure of the interplanetary coronal mass ejection (ICME). We use remote CME observations and a 3D reconstruction method (the graduated cylindrical shell method) to constrain initial boundary conditions of the FD model and take into account CME evolutionary properties by incorporating flux rope expansion. Several flux rope expansion modes are considered, which can lead to different FD characteristics. In general, the model is qualitatively in agreement with observations, whereas quantitative agreement depends on the diffusion coefficient and the expansion properties (interplay of the diffusion and expansion). A case study was performed to explain the FD observed on 2014 May 30. The observed FD was fitted quite well by ForbMod for all expansion modes using only the diffusion coefficient as a free parameter, where the diffusion parameter was found to correspond to an expected range of values. Our study shows that, in general, the model is able to explain the global properties of an FD caused by a flux rope and can thus be used to help understand the underlying physics in case studies.

Fast-to-Alfvén Mode Conversion in the Presence of Ambipolar Diffusion

NASA Astrophysics Data System (ADS)

Cally, Paul S.; Khomenko, Elena

2018-03-01

It is known that fast magnetohydrodynamic waves partially convert to upward and/or downward propagating Alfvén waves in a stratified atmosphere where Alfvén speed increases with height. This happens around the fast wave reflection height, where the fast wave’s horizontal phase speed equals the Alfvén speed (in a low-β plasma). Typically, this takes place in the mid to upper solar chromosphere for low-frequency waves in the few-millihertz band. However, this region is weakly ionized and thus susceptible to nonideal MHD processes. In this article, we explore how ambipolar diffusion in a zero-β plasma affects fast waves injected from below. Classical ambipolar diffusion is far too weak to have any significant influence at these low frequencies, but if enhanced by turbulence (in the quiet-Sun chromosphere but not in sunspot umbrae) or the production of sufficiently small-scale structure, can substantially absorb waves for turbulent ambipolar Reynolds numbers of around 20 or less. In that case, it is found that the mode conversion process is not qualitatively altered from the ideal case, though conversion to Alfvén waves is reduced because the fast wave flux reaching the conversion region is degraded. It is also found that any upward propagating Alfvén waves generated in this process are almost immune to further ambipolar attenuation, thereby reducing local ambipolar heating compared to cases without mode conversion. In that sense, mode conversion provides a form of “Alfvén cooling.”

Mode-coupling theoretical analysis of transport and relaxation properties of liquid dimethylimidazolium chloride

NASA Astrophysics Data System (ADS)

Yamaguchi, T.; Koda, S.

2010-03-01

The mode-coupling theory for molecular liquids based on the interaction-site model is applied to a representative molecular ionic liquid, dimethylimidazolium chloride, and dynamic properties such as shear viscosity, self-diffusion coefficients, reorientational relaxation time, electric conductivity, and dielectric relaxation spectrum are analyzed. Molecular dynamics (MD) simulation is also performed on the same system for comparison. The theory captures the characteristics of the dynamics of the ionic liquid qualitatively, although theoretical relaxation times are several times larger than those from the MD simulation. Large relaxations are found in the 100 MHz region in the dispersion of the shear viscosity and the dielectric relaxation, in harmony with various experiments. The relaxations of the self-diffusion coefficients are also found in the same frequency region. The dielectric relaxation spectrum is divided into the contributions of the translational and reorientational modes, and it is demonstrated that the relaxation in the 100 MHz region mainly stems from the translational modes. The zero-frequency electric conductivity is close to the value predicted by the Nernst-Einstein equation in both MD simulation and theoretical calculation. However, the frequency dependence of the electric conductivity is different from those of self-diffusion coefficients in that the former is smaller than the latter in the gigahertz-terahertz region, which is compensated by the smaller dispersion of the former in the 100 MHz region. The analysis of the theoretical calculation shows that the difference in their frequency dependence is due to the different contribution of the short- and long-range liquid structures.

Flight simulation software at NASA Dryden Flight Research Center

NASA Technical Reports Server (NTRS)

Norlin, Ken A.

1995-01-01

The NASA Dryden Flight Research Center has developed a versatile simulation software package that is applicable to a broad range of fixed-wing aircraft. This package has evolved in support of a variety of flight research programs. The structure is designed to be flexible enough for use in batch-mode, real-time pilot-in-the-loop, and flight hardware-in-the-loop simulation. Current simulations operate on UNIX-based platforms and are coded with a FORTRAN shell and C support routines. This paper discusses the features of the simulation software design and some basic model development techniques. The key capabilities that have been included in the simulation are described. The NASA Dryden simulation software is in use at other NASA centers, within industry, and at several universities. The straightforward but flexible design of this well-validated package makes it especially useful in an engineering environment.

1.65 mm diameter forward-viewing confocal endomicroscopic catheter using a flip-chip bonded electrothermal MEMS fiber scanner.

PubMed

Seo, Yeong-Hyeon; Hwang, Kyungmin; Jeong, Ki-Hun

2018-02-19

We report a 1.65 mm diameter forward-viewing confocal endomicroscopic catheter using a flip-chip bonded electrothermal MEMS fiber scanner. Lissajous scanning was implemented by the electrothermal MEMS fiber scanner. The Lissajous scanned MEMS fiber scanner was precisely fabricated to facilitate flip-chip connection, and bonded with a printed circuit board. The scanner was successfully combined with a fiber-based confocal imaging system. A two-dimensional reflectance image of the metal pattern 'OPTICS' was successfully obtained with the scanner. The flip-chip bonded scanner minimizes electrical packaging dimensions. The inner diameter of the flip-chip bonded MEMS fiber scanner is 1.3 mm. The flip-chip bonded MEMS fiber scanner is fully packaged with a 1.65 mm diameter housing tube, 1 mm diameter GRIN lens, and a single mode optical fiber. The packaged confocal endomicroscopic catheter can provide a new breakthrough for diverse in-vivo endomicroscopic applications.

Apollo 17 Lunar Surface Experiment equipment

NASA Image and Video Library

1972-11-30

S72-37259 (November 1972) --- The Geophone Module and Cable Reels of the Lunar Seismic Profiling Experiment (S-203), a component of the Apollo Lunar Surface Experiments Package which will be carried on the Apollo 17 lunar landing mission. LSPE components are four geophones similar to those used in an earlier active seismic experiment, an electronics package in the ALSEP central station, and eight explosive packages which will be deployed during the geology traverse. The four geophones will be placed one in the center and one at each corner of a 90-meter equilateral triangle. Explosive charges placed on the surface will generate seismic waves of varying strengths to provide data on the structural profile of the landing site. After the charges have been fired by ground command, the experiment will settle down into a passive listening mode, detecting moonquakes, meteorite impacts and the thump caused by the Lunar Module ascent stage impact.

Using quantum filters to process images of diffuse axonal injury

NASA Astrophysics Data System (ADS)

Pineda Osorio, Mateo

2014-06-01

Some images corresponding to a diffuse axonal injury (DAI) are processed using several quantum filters such as Hermite Weibull and Morse. Diffuse axonal injury is a particular, common and severe case of traumatic brain injury (TBI). DAI involves global damage on microscopic scale of brain tissue and causes serious neurologic abnormalities. New imaging techniques provide excellent images showing cellular damages related to DAI. Said images can be processed with quantum filters, which accomplish high resolutions of dendritic and axonal structures both in normal and pathological state. Using the Laplacian operators from the new quantum filters, excellent edge detectors for neurofiber resolution are obtained. Image quantum processing of DAI images is made using computer algebra, specifically Maple. Quantum filter plugins construction is proposed as a future research line, which can incorporated to the ImageJ software package, making its use simpler for medical personnel.

Banded structures in electron pitch angle diffusion coefficients from resonant wave-particle interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tripathi, A. K., E-mail: aktrip2001@yahoo.co.in; Singhal, R. P., E-mail: rpsiitbhu@yahoo.com; Khazanov, G. V., E-mail: George.V.Khazanov@nasa.gov

2016-04-15

Electron pitch angle (D{sub αα}) and momentum (D{sub pp}) diffusion coefficients have been calculated due to resonant interactions with electrostatic electron cyclotron harmonic (ECH) and whistler mode chorus waves. Calculations have been performed at two spatial locations L = 4.6 and 6.8 for electron energies ≤10 keV. Landau (n = 0) resonance and cyclotron harmonic resonances n = ±1, ±2, … ±5 have been included in the calculations. It is found that diffusion coefficient versus pitch angle (α) profiles show large dips and oscillations or banded structures. The structures are more pronounced for ECH and lower band chorus (LBC) and particularly at location 4.6. Calculations of diffusionmore » coefficients have also been performed for individual resonances. It is noticed that the main contribution of ECH waves in pitch angle diffusion coefficient is due to resonances n = +1 and n = +2. A major contribution to momentum diffusion coefficients appears from n = +2. However, the banded structures in D{sub αα} and D{sub pp} coefficients appear only in the profile of diffusion coefficients for n = +2. The contribution of other resonances to diffusion coefficients is found to be, in general, quite small or even negligible. For LBC and upper band chorus waves, the banded structures appear only in Landau resonance. The D{sub pp} diffusion coefficient for ECH waves is one to two orders smaller than D{sub αα} coefficients. For chorus waves, D{sub pp} coefficients are about an order of magnitude smaller than D{sub αα} coefficients for the case n ≠ 0. In case of Landau resonance, the values of D{sub pp} coefficient are generally larger than the values of D{sub αα} coefficients particularly at lower energies. As an aid to the interpretation of results, we have also determined the resonant frequencies. For ECH waves, resonant frequencies have been estimated for wave normal angle 89° and harmonic resonances n = +1, +2, and +3, whereas for whistler mode waves, the frequencies have been calculated for angle 10° and Landau resonance. Further, in ECH waves, the banded structures appear for electron energies ≥1 keV, and for whistler mode chorus waves, structures appear for energies >2 keV at L = 4.6 and above 200 eV for L = 6.8. The results obtained in the present work will be helpful in the study of diffusion curves and will have important consequences for diffuse aurora and pancake distributions.« less

A combination of spin diffusion methods for the determination of protein-ligand complex structural ensembles.

PubMed

Pilger, Jens; Mazur, Adam; Monecke, Peter; Schreuder, Herman; Elshorst, Bettina; Bartoschek, Stefan; Langer, Thomas; Schiffer, Alexander; Krimm, Isabelle; Wegstroth, Melanie; Lee, Donghan; Hessler, Gerhard; Wendt, K-Ulrich; Becker, Stefan; Griesinger, Christian

2015-05-26

Structure-based drug design (SBDD) is a powerful and widely used approach to optimize affinity of drug candidates. With the recently introduced INPHARMA method, the binding mode of small molecules to their protein target can be characterized even if no spectroscopic information about the protein is known. Here, we show that the combination of the spin-diffusion-based NMR methods INPHARMA, trNOE, and STD results in an accurate scoring function for docking modes and therefore determination of protein-ligand complex structures. Applications are shown on the model system protein kinase A and the drug targets glycogen phosphorylase and soluble epoxide hydrolase (sEH). Multiplexing of several ligands improves the reliability of the scoring function further. The new score allows in the case of sEH detecting two binding modes of the ligand in its binding site, which was corroborated by X-ray analysis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Diffusion coefficients of nitric oxide in water: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Pokharel, Sunil; Pantha, Nurapati; Adhikari, N. P.

2016-09-01

Self-diffusion coefficients along with the mutual diffusion coefficients of nitric oxide (NO) and SPC/E water (H2O) as solute and solvent of the mixture, have been studied within the framework of classical molecular dynamics level of calculations using GROMACS package. The radial distribution function (RDF) of the constituent compounds are calculated to study solute-solute, solute-solvent and solvent-solvent molecular interactions as a function of temperature. A dilute solution of five NO molecules (mole fraction 0.018) and 280 H2O molecules (mole fraction 0.982) has been taken as the sample. The self-diffusion coefficient of the solvent is calculated by using mean square displacement (MSD) where as that for solute (NO) is calculated by using MSD and velocity auto-correlation function (VACF). The results are then compared with the available experimental values. The results from the present work for water come in good agreement, very precise at low temperatures, with the experimental values. The diffusion coefficients of NO, on the other hands, agree well with the available theoretical studies, and also with experiment at low temperatures (up to 310 K). The results at the higher temperatures (up to 333 K), however, deviate significantly with the experimental observations. Also, the mutual diffusion coefficients of NO in water have been calculated by using Darken’s relation. The temperature dependence of the calculated diffusion coefficients follow the Arrhenius behavior.

Explosibility of Energetic Material Dusts

DTIC Science & Technology

1981-01-01

Leri st ics of hail powder and M-I 78 20 S,11,II11 in1l at 16adford Army Ammmnition Plant 79 2 ;’/ Salp Ii n.g it Ini ana Army Am;wiunition Plant I 2... travel only a short distance. Another mode of dispersion is diffusion, which is relatively slow. The third and primary mode of dispersion is transport by

The two-stage dynamics in the Fermi-Pasta-Ulam problem: From regular to diffusive behavior

NASA Astrophysics Data System (ADS)

Ponno, A.; Christodoulidi, H.; Skokos, Ch.; Flach, S.

2011-12-01

A numerical and analytical study of the relaxation to equilibrium of both the Fermi-Pasta-Ulam (FPU) α-model and the integrable Toda model, when the fundamental mode is initially excited, is reported. We show that the dynamics of both systems is almost identical on the short term, when the energies of the initially unexcited modes grow in geometric progression with time, through a secular avalanche process. At the end of this first stage of the dynamics, the time-averaged modal energy spectrum of the Toda system stabilizes to its final profile, well described, at low energy, by the spectrum of a q-breather. The Toda equilibrium state is clearly shown to describe well the long-living quasi-state of the FPU system. On the long term, the modal energy spectrum of the FPU system slowly detaches from the Toda one by a diffusive-like rising of the tail modes, and eventually reaches the equilibrium flat shape. We find a simple law describing the growth of tail modes, which enables us to estimate the time-scale to equipartition of the FPU system, even when, at small energies, it becomes unobservable.

A method for distinguishing between propagons, diffusions, and locons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seyf, Hamid Reza; Henry, Asegun; School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332

2016-07-14

The majority of intuition on phonon transport has been derived from studies of homogenous crystalline solids, where the atomic composition and structure are periodic. For this specific class of materials, the solutions to the equations of motions for the atoms (in the harmonic limit) result in plane wave modulated velocity fields for the normal modes of vibration. However, it has been known for several decades that whenever a system lacks periodicity, either compositional or structural, the normal modes of vibration can still be determined (in the harmonic limit), but the solutions take on different characteristics and many modes may notmore » be plane wave modulated. Previous work has classified the types of vibrations into three primary categories, namely, propagons, diffusions, and locons. One can use the participation ratio to distinguish locons, from propagons and diffusons, which measures the extent to which a mode is localized. However, distinguishing between propagons and diffusons has remained a challenge, since both are spatially delocalized. Here, we present a new method that quantifies the extent to which a mode's character corresponds to a propagating mode, e.g., exhibits plane wave modulation. This then allows for clear and quantitative distinctions between propagons and diffusons. By resolving this issue quantitatively, one can now automate the classification of modes for any arbitrary material or structure, subject to a single constraint that the atoms must vibrate stably around their respective equilibrium sites. Several example test cases are studied including crystalline silicon and germanium, crystalline silicon with different defect concentrations, as well as amorphous silicon, germanium, and silica.« less

Fast Ion and Thermal Plasma Transport in Turbulent Waves in the Large Plasma Device (LAPD)

NASA Astrophysics Data System (ADS)

Zhou, Shu

2011-10-01

The transport of fast ions and thermal plasmas in electrostatic microturbulence is studied. Strong density and potential fluctuations (δn / n ~ δϕ / kTe ~ 0 . 5 , f ~5-50 kHz) are observed in the LAPD in density gradient regions produced by obstacles with slab or cylindrical geometry. Wave characteristics and the associated plasma transport are modified by driving sheared E ×B drift through biasing the obstacle, and by modification of the axial magnetic fields (Bz) and the plasma species. Cross-field plasma transport is suppressed with small bias and large Bz, and is enhanced with large bias and small Bz. Suppressed cross-field thermal transport coincides with a 180° phase shift between the density and potential fluctuations in the radial direction, while the enhanced thermal transport is associated with modes having low mode number (m = 1) and long radial correlation length. Large gyroradius lithium ions (ρfast /ρs ~ 10) orbit through the turbulent region. Scans with a collimated analyzer and with Langmuir probes give detailed profiles of the fast ion spatial-temporal distribution and of the fluctuating fields. Fast-ion transport decreases rapidly with increasing fast-ion gyroradius. Background waves with different scale lengths also alter the fast ion transport: Beam diffusion is smaller in waves with smaller structures (higher mode number); also, coherent waves with long correlation length cause less beam diffusion than turbulent waves. Experimental results agree well with gyro-averaging theory. When the fast ion interacts with the wave for most of a wave period, a transition from super-diffusive to sub-diffusive transport is observed, as predicted by diffusion theory. A Monte Carlo trajectory-following code simulates the interaction of the fast ions with the measured turbulent fields. Good agreement between observation and modeling is observed. Work funded by DOE and NSF and performed at the Basic Plasma Science Facility.

Neuronal calcium wave propagation varies with changes in endoplasmic reticulum parameters: a computer model

PubMed Central

Neymotin, Samuel A.; McDougal, Robert A.; Sherif, Mohamed A.; Fall, Christopher P.; Hines, Michael L.; Lytton, William W.

2015-01-01

Calcium (Ca2+) waves provide a complement to neuronal electrical signaling, forming a key part of a neuron’s second messenger system. We developed a reaction-diffusion model of an apical dendrite with diffusible inositol triphosphate (IP3), diffusible Ca2+, IP3 receptors (IP3Rs), endoplasmic reticulum (ER) Ca2+ leak, and ER pump (SERCA) on ER. Ca2+ is released from ER stores via IP3Rs upon binding of IP3 and Ca2+. This results in Ca2+-induced-Ca2+-release (CICR) and increases Ca2+ spread. At least two modes of Ca2+ wave spread have been suggested: a continuous mode based on presumed relative homogeneity of ER within the cell; and a pseudo-saltatory model where Ca2+ regeneration occurs at discrete points with diffusion between them. We compared the effects of three patterns of hypothesized IP3R distribution: 1. continuous homogeneous ER, 2. hotspots with increased IP3R density (IP3R hotspots), 3. areas of increased ER density (ER stacks). All three modes produced Ca2+ waves with velocities similar to those measured in vitro (~50–90µm /sec). Continuous ER showed high sensitivity to IP3R density increases, with time to onset reduced and speed increased. Increases in SERCA density resulted in opposite effects. The measures were sensitive to changes in density and spacing of IP3R hotspots and stacks. Increasing the apparent diffusion coefficient of Ca2+ substantially increased wave speed. An extended electrochemical model, including voltage gated calcium channels and AMPA synapses, demonstrated that membrane priming via AMPA stimulation enhances subsequent Ca2+ wave amplitude and duration. Our modeling suggests that pharmacological targeting of IP3Rs and SERCA could allow modulation of Ca2+ wave propagation in diseases where Ca2+ dysregulation has been implicated. PMID:25734493

Excitable dynamics in high-Lewis number premixed gas combustion at normal and microgravity

NASA Technical Reports Server (NTRS)

Pearlman, Howard

1995-01-01

Freely-propagating, premixed gas flames in high-Lewis (Le) number, quiescent mixtures are studied experimentally in tubes of various diameter at normal (lg) and microgravity (mu g). A premixture of lean butane and oxygen diluted with helium, argon, neon, nitrogen or a mixture of multiple diluents is examined such that the thermal diffusivity of the mixture (and to a lesser extent, the mass diffusivity of the rate-limiting component) is systematically varied. In effect, different diluents allow variation of the Le without changing the chemistry. The flames are recorded with high speed cinematography and their stability is visually assessed. Different modes of propagation were observed depending on the diameter of the tubes (different conductive heat loss), the composition of the mixture and the g-level. At 1g, four modes of propagation were observed in small and intermediate diameter tubes (large conductive heat loss): (1) steadily propagating flames, (2) radial and longitudinal pulsating flames, (3) 'wavering' flames, and (4) rotating spiral flames. As the diameter of the tube increases, the radial modes become more pronounced while the longitudinal modes systematically disappear. Also, multiple, simultaneous, spatially-separated 'pacemaker' sites are observed in intermediate and large diameter tubes. Each site starts as a small region of high luminosity and develops into a flamelet which assumes the form of one of the fore mentioned modes. These flamelets eventually interact, annihilate each other in their regions of intersection and merge at their newly created free-ends. For very large tubes, radially-propagating wave-trains (believed to be 'trigger waves') are observed. These are analogous to the radial pulsations observed in the smaller diameter tubes. At mu g, three modes of propagation have been observed: (1) steadily propagating flames, (2) radial and longitudinal pulsating flames, and (3) multi-armed, rotating flames. Since the pulsating mode exists at mu g and 1g, buoyant flicker is not the mechanism which drives the pulsations. Moreover, all of the instabilities at 1g and mu g have characteristic frequencies on the O(100Hz). This value is lower than the fundamental, longitudinal acoustic frequencies of the tubes which suggests that the instabilities are not acoustically driven. The patterns formed by this reaction bear remarkable similarities with the patterns formed in most excitable media when the behavior of the system is driven by couplings between chemical reaction and diffusion (e.g., Belousov-Zhabotinsky reaction, Patterns in slime molds, spiral waves in the retina of a bird's eye). While it is recognized that the chemical mechanism associated with this premixed gas reaction is exponentially sensitive to temperature and undoubtedly different from those which govern previously observed excitable media (most are isothermal, or weakly exothermic, liquid phase reactions), similar spatial and temporal patterns should not come as a complete surprise considering heat and mass diffusion are self similar. It is concluded that this premixed gas system is a definitive example of a diffusive-thermal, gas-phase oscillator based on these experimental results and their favorable comparison with theory.

Eutectic-based wafer-level-packaging technique for piezoresistive MEMS accelerometers and bond characterization using molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Aono, T.; Kazama, A.; Okada, R.; Iwasaki, T.; Isono, Y.

2018-03-01

We developed a eutectic-based wafer-level-packaging (WLP) technique for piezoresistive micro-electromechanical systems (MEMS) accelerometers on the basis of molecular dynamics analyses and shear tests of WLP accelerometers. The bonding conditions were experimentally and analytically determined to realize a high shear strength without solder material atoms diffusing to adhesion layers. Molecular dynamics (MD) simulations and energy dispersive x-ray (EDX) spectrometry done after the shear tests clarified the eutectic reaction of the solder materials used in this research. Energy relaxation calculations in MD showed that the diffusion of solder material atoms into the adhesive layer was promoted at a higher temperature. Tensile creep MD simulations also suggested that the local potential energy in a solder material model determined the fracture points of the model. These numerical results were supported by the shear tests and EDX analyses for WLP accelerometers. Consequently, a bonding load of 9.8 kN and temperature of 300 °C were found to be rational conditions because the shear strength was sufficient to endure the polishing process after the WLP process and there was little diffusion of solder material atoms to the adhesion layer. Also, eutectic-bonding-based WLP was effective for controlling the attenuation of the accelerometers by determining the thickness of electroplated solder materials that played the role of a cavity between the accelerometers and lids. If the gap distance between the two was less than 6.2 µm, the signal gains for x- and z-axis acceleration were less than 20 dB even at the resonance frequency due to air-damping.

Documentation of the seawater intrusion (SWI2) package for MODFLOW

USGS Publications Warehouse

Bakker, Mark; Schaars, Frans; Hughes, Joseph D.; Langevin, Christian D.; Dausman, Alyssa M.

2013-01-01

The SWI2 Package is the latest release of the Seawater Intrusion (SWI) Package for MODFLOW. The SWI2 Package allows three-dimensional vertically integrated variable-density groundwater flow and seawater intrusion in coastal multiaquifer systems to be simulated using MODFLOW-2005. Vertically integrated variable-density groundwater flow is based on the Dupuit approximation in which an aquifer is vertically discretized into zones of differing densities, separated from each other by defined surfaces representing interfaces or density isosurfaces. The numerical approach used in the SWI2 Package does not account for diffusion and dispersion and should not be used where these processes are important. The resulting differential equations are equivalent in form to the groundwater flow equation for uniform-density flow. The approach implemented in the SWI2 Package allows density effects to be incorporated into MODFLOW-2005 through the addition of pseudo-source terms to the groundwater flow equation without the need to solve a separate advective-dispersive transport equation. Vertical and horizontal movement of defined density surfaces is calculated separately using a combination of fluxes calculated through solution of the groundwater flow equation and a simple tip and toe tracking algorithm. Use of the SWI2 Package in MODFLOW-2005 only requires the addition of a single additional input file and modification of boundary heads to freshwater heads referenced to the top of the aquifer. Fluid density within model layers can be represented using zones of constant density (stratified flow) or continuously varying density (piecewise linear in the vertical direction) in the SWI2 Package. The main advantage of using the SWI2 Package instead of variable-density groundwater flow and dispersive solute transport codes, such as SEAWAT and SUTRA, is that fewer model cells are required for simulations using the SWI2 Package because every aquifer can be represented by a single layer of cells. This reduction in number of required model cells and the elimination of the need to solve the advective-dispersive transport equation results in substantial model run-time savings, which can be large for regional aquifers. The accuracy and use of the SWI2 Package is demonstrated through comparison with existing exact solutions and numerical solutions with SEAWAT. Results for an unconfined aquifer are also presented to demonstrate application of the SWI2 Package to a large-scale regional problem.

Electric-field noise from carbon-adatom diffusion on a Au(110) surface: First-principles calculations and experiments

NASA Astrophysics Data System (ADS)

Kim, E.; Safavi-Naini, A.; Hite, D. A.; McKay, K. S.; Pappas, D. P.; Weck, P. F.; Sadeghpour, H. R.

2017-03-01

The decoherence of trapped-ion quantum gates due to heating of their motional modes is a fundamental science and engineering problem. This heating is attributed to electric-field noise arising from the trap-electrode surfaces. In this work, we investigate the source of this noise by focusing on the diffusion of carbon-containing adsorbates on the surface of Au(110). We show by density functional theory, based on detailed scanning probe microscopy, how the carbon adatom diffusion on the gold surface changes the energy landscape and how the adatom dipole moment varies with the diffusive motion. A simple model for the diffusion noise, which varies quadratically with the variation of the dipole moment, predicts a noise spectrum, in accordance with the measured values.

Diffusion in inhomogeneous polymer membranes

NASA Astrophysics Data System (ADS)

Kasargod, Sameer S.; Adib, Farhad; Neogi, P.

1995-10-01

The dual mode sorption solubility isotherms assume, and in instances Zimm-Lundberg analysis of the solubilities show, that glassy polymers are heterogeneous and that the distribution of the solute in the polymer is also inhomogeneous. Under some conditions, the heterogeneities cannot be represented as holes. A mathematical model describing diffusion in inhomogeneous polymer membranes is presented using Cahn and Hilliard's gradient theory. The fractional mass uptake is found to be proportional to the fourth root of time rather than the square root, predicted by Fickian diffusion. This type of diffusion is classified as pseudo-Fickian. The model is compared with one experimental result available. A negative value of the persistence factor is obtained and the results are interpreted.

Energization of Radiation Belt Electrons by High and Low Azimuthal Mode Number Poloidal Mode ULF Waves

NASA Astrophysics Data System (ADS)

Hudson, M. K.; Brito, T.; Elkington, S. R.; Kress, B. T.; Liang, Y.

2011-12-01

CME-shock and CIR-driven geomagnetic storms are characterized by enhanced ULF wave activity in the magnetosphere. This enhanced ULF wave power produces both coherent and diffusive transport and energization, as well as pitch angle modification of radiation belt electrons in drift resonance with azimuthally propagating ULF waves. Recent observations of two CME-driven storms1,2 have suggested that poloidal mode waves with both low and high azimuthal mode number may be efficient at accelerating radiation belt electrons. We extend up to m = 50 the analysis of Ozeke and Mann3 who examined drift resonance for poloidal modes up to m = 40. We calculate radial diffusion coefficients for source population electrons in the 50 -500 keV range, and continued resonance with lower m-numbers at higher energies for ULF waves in the Pc 5, 0.4 - 10 mHz range. We use an analytic model for ULF waves superimposed on a compressed dipole, developed for equatorial plane studies by Elkington et al.4 and extended to 3D by Perry et al.4 Assuming a power spectrum which varies as ω-2, consistent with earlier observations, we find greater efficiency for radial transport and acceleration at lower m number where there is greater power for drift resonance at a given frequency. This assumption is consistent with 3D global MHD simulations using the Lyon-Fedder-Mobarry code which we have carried out for realistic solar wind driving conditions during storms. Coherent interaction with ULF waves can also occur at a rate which exceeds nominal radial diffusion estimates but is slower than prompt injection on a drift time scale. Depending on initial electron drift phase, some electrons are accelerated due to the westward azimuthal electric field Eφ, while others are decelerated by eastward Eφ, decreasing their pitch angle. A subset of trapped electrons are seen to precipitate to the atmosphere in 3D LFM simulations, showing modulation at the coherent poloidal mode ULF wave frequency in both simulations and MINIS balloon observations for the January 21, 2005 CME-driven storm. Thus Pc 5 poloidal mode ULF waves cause competing increase and decrease in relativistic electron flux. The relative efficiencies of both coherent and diffusive processes will be examined. 1Zong et al., JGR, doi:10.1029/2009JA014393, 2009. 2Tan et al., JGR, doi:10.1029/2010JA016226, 2011. 3Ozeke and Mann, JGR, doi:10.1029/2007JA012468, 2008. 4Elkington et al., doi:10.1029/2001JA009202, 2003, 2003. 5Perry et al., doi:10.1029/2004JA010760, 2005.

Apparent diffusion coefficient histogram metrics correlate with survival in diffuse intrinsic pontine glioma: a report from the Pediatric Brain Tumor Consortium

PubMed Central

Poussaint, Tina Young; Vajapeyam, Sridhar; Ricci, Kelsey I.; Panigrahy, Ashok; Kocak, Mehmet; Kun, Larry E.; Boyett, James M.; Pollack, Ian F.; Fouladi, Maryam

2016-01-01

Background Diffuse intrinsic pontine glioma (DIPG) is associated with poor survival regardless of therapy. We used volumetric apparent diffusion coefficient (ADC) histogram metrics to determine associations with progression-free survival (PFS) and overall survival (OS) at baseline and after radiation therapy (RT). Methods Baseline and post-RT quantitative ADC histograms were generated from fluid-attenuated inversion recovery (FLAIR) images and enhancement regions of interest. Metrics assessed included number of peaks (ie, unimodal or bimodal), mean and median ADC, standard deviation, mode, skewness, and kurtosis. Results Based on FLAIR images, the majority of tumors had unimodal peaks with significantly shorter average survival. Pre-RT FLAIR mean, mode, and median values were significantly associated with decreased risk of progression; higher pre-RT ADC values had longer PFS on average. Pre-RT FLAIR skewness and standard deviation were significantly associated with increased risk of progression; higher pre-RT FLAIR skewness and standard deviation had shorter PFS. Nonenhancing tumors at baseline showed higher ADC FLAIR mean values, lower kurtosis, and higher PFS. For enhancing tumors at baseline, bimodal enhancement histograms had much worse PFS and OS than unimodal cases and significantly lower mean peak values. Enhancement in tumors only after RT led to significantly shorter PFS and OS than in patients with baseline or no baseline enhancement. Conclusions ADC histogram metrics in DIPG demonstrate significant correlations between diffusion metrics and survival, with lower diffusion values (increased cellularity), increased skewness, and enhancement associated with shorter survival, requiring future investigations in large DIPG clinical trials. PMID:26487690

Dynamics of proteins: Light scattering study of dilute and dense colloidal suspensions of eye lens homogenates

NASA Astrophysics Data System (ADS)

Giannopoulou, A.; Aletras, A. J.; Pharmakakis, N.; Papatheodorou, G. N.; Yannopoulos, S. N.

2007-11-01

We report a dynamic light scattering study on protein suspensions of bovine lens homogenates at conditions (pH and ionic strength) similar to the physiological ones. Light scattering data were collected at two temperatures, 20 and 37°C, over a wide range of concentrations from the very dilute limit up to the dense regime approaching the physiological lens concentration. A comparison with experimental data from intact bovine lenses was advanced, revealing differences between dispersions and lenses at similar concentrations. In the dilute regime, two scattering entities were detected and identified with the long-time self-diffusion modes of α-crystallins and their aggregates, which naturally exist in lens nucleus. Upon increasing protein concentration, significant changes in time correlation function were observed starting at ˜75mgml-1, where a new mode originating from collective diffusive motions becomes visible. Self-diffusion coefficients are temperature insensitive, whereas the collective diffusion coefficient depends strongly on temperature revealing a reduction of the net repulsive interparticle forces with decreasing temperature. While there are no rigorous theoretical approaches on particle diffusion properties for multicomponent, nonideal hard sphere polydispersed systems, as the suspensions studied here, a discussion of the volume fraction dependence of the long-time self-diffusion coefficient in the context of existing theoretical approaches was undertaken. This study is purported to provide some insight into the complex light scattering pattern of intact lenses and the interactions between the constituent proteins that are responsible for lens transparency. This would lead to understand basic mechanisms of specific protein interactions that lead to lens opacification (cataract) under pathological conditions.

PyRosetta: a script-based interface for implementing molecular modeling algorithms using Rosetta.

PubMed

Chaudhury, Sidhartha; Lyskov, Sergey; Gray, Jeffrey J

2010-03-01

PyRosetta is a stand-alone Python-based implementation of the Rosetta molecular modeling package that allows users to write custom structure prediction and design algorithms using the major Rosetta sampling and scoring functions. PyRosetta contains Python bindings to libraries that define Rosetta functions including those for accessing and manipulating protein structure, calculating energies and running Monte Carlo-based simulations. PyRosetta can be used in two ways: (i) interactively, using iPython and (ii) script-based, using Python scripting. Interactive mode contains a number of help features and is ideal for beginners while script-mode is best suited for algorithm development. PyRosetta has similar computational performance to Rosetta, can be easily scaled up for cluster applications and has been implemented for algorithms demonstrating protein docking, protein folding, loop modeling and design. PyRosetta is a stand-alone package available at http://www.pyrosetta.org under the Rosetta license which is free for academic and non-profit users. A tutorial, user's manual and sample scripts demonstrating usage are also available on the web site.

PyRosetta: a script-based interface for implementing molecular modeling algorithms using Rosetta

PubMed Central

Chaudhury, Sidhartha; Lyskov, Sergey; Gray, Jeffrey J.

2010-01-01

Summary: PyRosetta is a stand-alone Python-based implementation of the Rosetta molecular modeling package that allows users to write custom structure prediction and design algorithms using the major Rosetta sampling and scoring functions. PyRosetta contains Python bindings to libraries that define Rosetta functions including those for accessing and manipulating protein structure, calculating energies and running Monte Carlo-based simulations. PyRosetta can be used in two ways: (i) interactively, using iPython and (ii) script-based, using Python scripting. Interactive mode contains a number of help features and is ideal for beginners while script-mode is best suited for algorithm development. PyRosetta has similar computational performance to Rosetta, can be easily scaled up for cluster applications and has been implemented for algorithms demonstrating protein docking, protein folding, loop modeling and design. Availability: PyRosetta is a stand-alone package available at http://www.pyrosetta.org under the Rosetta license which is free for academic and non-profit users. A tutorial, user's manual and sample scripts demonstrating usage are also available on the web site. Contact: pyrosetta@graylab.jhu.edu PMID:20061306

Use of control umbilicals as a deployment mode for free flying telerobotic work systems

NASA Technical Reports Server (NTRS)

Kuehn, J. S.; Selle, E. D.

1987-01-01

Work to date on telerobotic work systems for use in space generally consider two deployment modes, free flying, or fixed within a limited work envelope. Control tethers may be employed to obtain a number of operational advantages and added flexibility in the basing and deployment of telerobotic work systems. Use of a tether allows the work system to be separated into two major modules, the remote work package and the control module. The Remote Work Package (RWP) comprises the free flying portion of the work system while the Control Module (CM) remains at the work system base. The chief advantage of this configuration is that only the components required for completion of the work task must be located at the work site. Reaction mass used in free flight is stored at the Control module and supplied to the RWP through the tether, eliminating the need for the RWP to carry it. The RWP can be made less massive than a self contained free flying work system. As a result, reaction mass required for free flight is lower than for a self contained free flyer.

Blade Vibration Measurement System

NASA Technical Reports Server (NTRS)

Platt, Michael J.

2014-01-01

The Phase I project successfully demonstrated that an advanced noncontacting stress measurement system (NSMS) could improve classification of blade vibration response in terms of mistuning and closely spaced modes. The Phase II work confirmed the microwave sensor design process, modified the sensor so it is compatible as an upgrade to existing NSMS, and improved and finalized the NSMS software. The result will be stand-alone radar/tip timing radar signal conditioning for current conventional NSMS users (as an upgrade) and new users. The hybrid system will use frequency data and relative mode vibration levels from the radar sensor to provide substantially superior capabilities over current blade-vibration measurement technology. This frequency data, coupled with a reduced number of tip timing probes, will result in a system capable of detecting complex blade vibrations that would confound traditional NSMS systems. The hardware and software package was validated on a compressor rig at Mechanical Solutions, Inc. (MSI). Finally, the hybrid radar/tip timing NSMS software package and associated sensor hardware will be installed for use in the NASA Glenn spin pit test facility.

Annealing of linear birefringence in single-mode fiber coils - Application to optical fiber current sensors

NASA Technical Reports Server (NTRS)

Tang, Dingding; Rose, A. H.; Day, G. W.; Etzel, Shelley M.

1991-01-01

Annealing procedures that greatly reduce linear birefringence in single-mode fiber coils are described. These procedures have been successfully applied to coils ranging from 5 mm to 10 cm in diameter and up to 200 or more turns. They involve temperature cycles that last 3-4 days and reach maximum temperatures of about 850 C. The residual birefringence and induced loss are minimized by proper selection of fiber. The primary application of these coils is optical fiber current sensors, where they yield small sensors that are more stable than those achieved by other techniques. A current sensor with a temperature stability of 8.4 x 10 to the -5th/K over the range from -75 to 145 C has been demonstrated. This is approximately 20 percent greater than the temperature dependence of the Verdet constant. Packaging degrades the stability, but a packaged sensor coil with a temperature stability of about 1.6 + 10 to the -4th/K over the range from -20 to 120 C has also been demonstrated.

Patterns induced by super cross-diffusion in a predator-prey system with Michaelis-Menten type harvesting.

PubMed

Liu, Biao; Wu, Ranchao; Chen, Liping

2018-04-01

Turing instability and pattern formation in a super cross-diffusion predator-prey system with Michaelis-Menten type predator harvesting are investigated. Stability of equilibrium points is first explored with or without super cross-diffusion. It is found that cross-diffusion could induce instability of equilibria. To further derive the conditions of Turing instability, the linear stability analysis is carried out. From theoretical analysis, note that cross-diffusion is the key mechanism for the formation of spatial patterns. By taking cross-diffusion rate as bifurcation parameter, we derive amplitude equations near the Turing bifurcation point for the excited modes by means of weakly nonlinear theory. Dynamical analysis of the amplitude equations interprets the structural transitions and stability of various forms of Turing patterns. Furthermore, the theoretical results are illustrated via numerical simulations. Copyright © 2018. Published by Elsevier Inc.

Antioxidant activity and diffusion of catechin and epicatechin from antioxidant active films made of poly(L-lactic acid).

PubMed

Iñiguez-Franco, Fabiola; Soto-Valdez, Herlinda; Peralta, Elizabeth; Ayala-Zavala, J Fernando; Auras, Rafael; Gámez-Meza, Nohemí

2012-07-04

Active membranes and food packaging containing antioxidants like catechin and epicatechin, combined with the use of materials made of biopolymers obtained from renewable sources, could create a novel alternative to reduce oxidation in food, pharmaceutical, and cosmetic products. Poly(94% L-lactic acid) films containing 1.28% catechin and 1.50% epicatechin were extruded in a pilot plant-scale extrusion machine. The diffusion kinetics of catechin and epicatechin into 95% ethanol at 20, 30, 40, and 50 °C and 50% ethanol at 40 °C displayed Fickian release behavior and diffusion coefficients between 0.5 and 50 × 10(-11) cm(2)/s. According to the Arrhenius equation, the energy of activation for the diffusion of catechin and epicatechin in the films was 110.43 and 98.92 kJ/mol, respectively. The antioxidant activity of the films was measured in methanol extracts containing 46.42 μg/mL of catechin and 57.52 μg/mL of epicatechin as 32.90 and 36.68% of scavenging the 2,2-diphenyl-1-picrylhydrazyl radical, respectively.

Molecular dynamics simulation of three plastic additives' diffusion in polyethylene terephthalate.

PubMed

Li, Bo; Wang, Zhi-Wei; Lin, Qin-Bao; Hu, Chang-Ying

2017-06-01

Accurate diffusion coefficient data of additives in a polymer are of paramount importance for estimating the migration of the additives over time. This paper shows how this diffusion coefficient can be estimated for three plastic additives [2-(2'-hydroxy-5'-methylphenyl) (UV-P), 2,6-di-tert-butyl-4-methylphenol (BHT) and di-(2-ethylhexyl) phthalate (DEHP)] in polyethylene terephthalate (PET) using the molecular dynamics (MD) simulation method. MD simulations were performed at temperatures of 293-433 K. The diffusion coefficient was calculated through the Einstein relationship connecting the data of mean-square displacement at different times. Comparison of the diffusion coefficients simulated by the MD simulation technique, predicted by the Piringer model and experiments, showed that, except for a few samples, the MD-simulated values were in agreement with the experimental values within one order of magnitude. Furthermore, the diffusion process for additives is discussed in detail, and four factors - the interaction energy between additive molecules and PET, fractional free volume, molecular shape and size, and self-diffusion of the polymer - are proposed to illustrate the microscopic diffusion mechanism. The movement trajectories of additives in PET cell models suggested that the additive molecules oscillate slowly rather than hopping for a long time. Occasionally, when a sufficiently large hole was created adjacently, the molecule could undergo spatial motion by jumping into the free-volume hole and consequently start a continuous oscillation and hop. The results indicate that MD simulation is a useful approach for predicting the microstructure and diffusion coefficient of plastic additives, and help to estimate the migration level of additives from PET packaging.

Demonstration of glass-based photonic interposer for mid-board-optical engines and electrical-optical circuit board (EOCB) integration strategy

NASA Astrophysics Data System (ADS)

Schröder, H.; Neitz, M.; Schneider-Ramelow, M.

2018-02-01

Due to its optical transparency and superior dielectric properties glass is regarded as a promising candidate for advanced applications as active photonic interposer for mid-board-optics and optical PCB waveguide integration. The concepts for multi-mode and single-mode photonic system integration are discussed and related demonstration project results will be presented. A hybrid integrated photonic glass body interposer with integrated optical lenses for multi-mode data communication wavelength of 850 nm have been realized. The paper summarizes process developments which allow cost efficient metallization of TGV. Electro-optical elements like photodiodes and VCSELs can be directly flip-chip mounted on the glass substrate according to the desired lens positions. Furthermore results for a silicon photonic based single-mode active interposer integration onto a single mode glass made EOCB will be compared in terms of packaging challenges. The board level integration strategy for both of these technological approaches and general next generation board level integration concepts for photonic interposer will be introductorily discussed.

Semiempirical models of H-mode discharges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singer, C.E.; Redi, M.; Boyd, D.

1985-05-01

The H-mode transition can lead to a rapid increase in tokamak plasma confinement. A semiempirical transport model was derived from global OH and L-mode confinement scalings and then applied to simulation of H-mode discharges. The radial diffusivities in the model also depend on local density and pressure gradients and satisfy an appropriate dimensional constraint. Examples are shown of the application of this and similar models to the detailed simulation of two discharges which exhibit an H-mode transition. The models reproduce essential features of plasma confinement in the ohmic heating, low and high confinement phases of these discharges. In particular, themore » evolution of plasma energy content through the H-mode transition can be reproduced without any sudden or ad hoc modification of the plasma transport formulation.« less

Manifestations of the MHD and kinetic dynamo through soft x-rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chartas, G.A.

1991-08-01

The underlying mechanisms that produce and sustain the reversed toroidal field in RFP's are investigated by analyzing 2Dx-ray emissivity reconstruction and by correlating the evolution of the hot electron properties to the reversed toroidal magnetic field. Reconnection of emissivity surfaces as seen in soft x-ray (SXR) reconstructing occur near the predicted resonant surface for the m=1, n=5, 6,-7 resistive tearing modes. Two distinct rates of reversed magnetic field generation are observed. First, in the MHD relaxation phase a sudden increase in B{sub t}(a) is detected. This event coincides with a large increase in the edge hot electron current density. Themore » second mode of flux generation is observed t have a slower rate and occurs during the diffusion phase. A variation of the edge hot electron current density by a factor of four produced only a small change in the measured B{sub t}(a), implying the contributions of the hot electrons to the dynamo during the diffusion phase is small. {tilde T}{sub e}, / was measured to be approximately 60%, which is much larger than the corresponding quantity for the bulk component which is about 30%. Scaling of the magnetic Reynolds number with the diffusion and MHD relaxation time, {tau}{sub MHD} indicated that the {tau}{sub MHD} does not have a strong dependence on the Spitzer resistivity whereas the diffusion time does depend on the classical resistivity. SXR emission mode analysis during the transition from a rotating to a locked plasma shows a decrease in the m=1 Fourier Bastille component of the emissivity. This is due to the flattening of the emissivity profile as seen in the SXR reconstructions.« less

Quasilinear Line Broadened Model for Energetic Particle Transport

NASA Astrophysics Data System (ADS)

Ghantous, Katy; Gorelenkov, Nikolai; Berk, Herbert

2011-10-01

We present a self-consistent quasi-linear model that describes wave-particle interaction in toroidal geometry and computes fast ion transport during TAE mode evolution. The model bridges the gap between single mode resonances, where it predicts the analytically expected saturation levels, and the case of multiple modes overlapping, where particles diffuse across phase space. Results are presented in the large aspect ratio limit where analytic expressions are used for Fourier harmonics of the power exchange between waves and particles, . Implemention of a more realistic mode structure calculated by NOVAK code are also presented. This work is funded by DOE contract DE-AC02-09CH11466.

Improvement of time-delayed feedback control by periodic modulation: analytical theory of Floquet mode control scheme.

PubMed

Just, Wolfram; Popovich, Svitlana; Amann, Andreas; Baba, Nilüfer; Schöll, Eckehard

2003-02-01

We investigate time-delayed feedback control schemes which are based on the unstable modes of the target state, to stabilize unstable periodic orbits. The periodic time dependence of these modes introduces an external time scale in the control process. Phase shifts that develop between these modes and the controlled periodic orbit may lead to a huge increase of the control performance. We illustrate such a feature on a nonlinear reaction diffusion system with global coupling and give a detailed investigation for the Rössler model. In addition we provide the analytical explanation for the observed control features.

Mode-field adapter for tapered-fiber-bundle signal and pump combiners.

PubMed

Koška, Pavel; Baravets, Yauhen; Peterka, Pavel; Bohata, Jan; Písařík, Michael

2015-02-01

We report on a novel mode-field adapter that is proposed to be incorporated inside tapered fused-fiber-bundle pump and signal combiners for high-power double-clad fiber lasers. Such an adapter allows optimization of signal-mode-field matching on the input and output fibers. Correspondingly, losses of the combiner signal branch are significantly reduced. The mode-field adapter optimization procedure is demonstrated on a combiner based on commercially available fibers. Signal wavelengths of 1.55 and 2 μm are considered. The losses can be further improved by using specially designed intermediate fiber and by dopant diffusion during splicing as confirmed by preliminary experimental results.

Magnetorotational instability in protoplanetary discs

NASA Astrophysics Data System (ADS)

Salmeron, Raquel; Wardle, Mark

2005-07-01

We investigate the linear growth and vertical structure of the magnetorotational instability (MRI) in weakly ionized, stratified accretion discs. The magnetic field is initially vertical and dust grains are assumed to have settled towards the mid-plane, so charges are carried by electrons and ions only. Solutions are obtained at representative radial locations from the central protostar for different choices of the initial magnetic field strength, sources of ionization, disc structure and configuration of the conductivity tensor. The MRI is active over a wide range of magnetic field strengths and fluid conditions in low-conductivity discs. Moreover, no evidence was found of a low-limit field strength below which unstable modes do not exist. For the minimum-mass solar nebula model, incorporating cosmic ray ionization, perturbations grow at 1 au for B<~ 8 G. For a significant subset of these strengths (200mG <~B<~ 5G), the maximum growth rate is of the order of the ideal magnetohydrodynamic (MHD) rate (0.75Ω). Hall conductivity modifies the structure and growth rate of global unstable modes at 1 au for all magnetic field strengths that support MRI. As a result, at this radius, modes obtained with a full conductivity tensor grow faster and are active over a more extended cross-section of the disc than perturbations in the ambipolar diffusion limit. For relatively strong fields (e.g. B>~ 200 mG), ambipolar diffusion alters the envelope shapes of the unstable modes, which peak at an intermediate height, instead of being mostly flat as modes in the Hall limit are in this region of parameter space. Similarly, when cosmic rays are assumed to be excluded from the disc by the winds emitted by the magnetically active protostar, unstable modes grow at this radius for B<~ 2 G. For strong fields, perturbations exhibit a kink at the height where X-ray ionization becomes active. Finally, for R= 5 au (10 au), unstable modes exist for B<~ 800 mG (B<~ 250 mG) and the maximum growth rate is close to the ideal-MHD rate for 20 <~B<~ 500 mG (2 <~B<~ 50 mG). Similarly, perturbations incorporating Hall conductivity have a higher wavenumber and grow faster than solutions in the ambipolar diffusion limit for B<~ 100 mG (B<~ 10 mG). Unstable modes grow even at the mid-plane for B>~ 100 mG (B~ 1 mG), but for weaker fields, a small dead region exists. This study shows that, despite the low magnetic coupling, the magnetic field is dynamically important for a large range of fluid conditions and field strengths in protostellar discs. An example of such magnetic activity is the generation of MRI unstable modes, which are supported at 1 au for field strengths up to a few gauss. Hall diffusion largely determines the structure and growth rate of these perturbations for all studied radii. At radii of order 1 au, in particular, it is crucial to incorporate the full conductivity tensor in the analysis of this instability and more generally in studies of the dynamics of astrophysical discs.

Atmospheric science facility pallet-only mode space transportation system payload (feasibility study), Volume 1

NASA Technical Reports Server (NTRS)

1975-01-01

The economic and technical feasibility is assessed of employing a pallet-only mode for conducting Atmospheric Magnetospheric Plasmas-in-Space experiments. A baseline design incorporating the experiment and instrument descriptions is developed. The prime instruments are packaged into four pallets in a physical and functional manner compatible with the Space Transportation System capabilities and/or constraints and an orbiter seven-day mission timeline. Operational compatibility is verified between the orbiter/payload and supporting facilities. The development status and the schedule requirements applicable to the Atmospheric Science Facility mission are identified. Conclusions and recommendations are presented and discussed.

Turbulent edge transport in the Princeton Beta Experiment-Modified high confinement mode

NASA Astrophysics Data System (ADS)

Tynan, G. R.; Schmitz, L.; Blush, L.; Boedo, J. A.; Conn, R. W.; Doerner, R.; Lehmer, R.; Moyer, R.; Kugel, H.; Bell, R.; Kaye, S.; Okabayashi, M.; Sesnic, S.; Sun, Y.

1994-10-01

The first probe measurements of edge turbulence and transport in a neutral beam induced high confinement mode (H-mode) are reported. A strong negative radial electric field is directly observed in H-mode. A transient suppression of normalized ion saturation and floating potential fluctuation levels occurs at the low confinement mode to high confinement mode (L-H) transition, followed by a recovery to near low mode (L-mode) levels. The average poloidal wave number and the poloidal wave-number spectral width are decreased, and the correlation between fluctuating density and potential is reduced. A large-amplitude coherent oscillation, localized to the strong radial electric field region, is observed in H-mode but does not cause transport. In H-mode the effective turbulent diffusion coefficient is reduced by an order of magnitude inside the last closed flux surface and in the scrape-off layer. The results are compared with a heuristic model of turbulence suppression by velocity-shear stabilization.

TIME-DOMAIN METHODS FOR DIFFUSIVE TRANSPORT IN SOFT MATTER

PubMed Central

Fricks, John; Yao, Lingxing; Elston, Timothy C.; Gregory Forest, And M.

2015-01-01

Passive microrheology [12] utilizes measurements of noisy, entropic fluctuations (i.e., diffusive properties) of micron-scale spheres in soft matter to infer bulk frequency-dependent loss and storage moduli. Here, we are concerned exclusively with diffusion of Brownian particles in viscoelastic media, for which the Mason-Weitz theoretical-experimental protocol is ideal, and the more challenging inference of bulk viscoelastic moduli is decoupled. The diffusive theory begins with a generalized Langevin equation (GLE) with a memory drag law specified by a kernel [7, 16, 22, 23]. We start with a discrete formulation of the GLE as an autoregressive stochastic process governing microbead paths measured by particle tracking. For the inverse problem (recovery of the memory kernel from experimental data) we apply time series analysis (maximum likelihood estimators via the Kalman filter) directly to bead position data, an alternative to formulas based on mean-squared displacement statistics in frequency space. For direct modeling, we present statistically exact GLE algorithms for individual particle paths as well as statistical correlations for displacement and velocity. Our time-domain methods rest upon a generalization of well-known results for a single-mode exponential kernel [1, 7, 22, 23] to an arbitrary M-mode exponential series, for which the GLE is transformed to a vector Ornstein-Uhlenbeck process. PMID:26412904

Skylab program earth resources experiment package: Ground truth data for test sites (SL-2)

NASA Technical Reports Server (NTRS)

1975-01-01

Field measurements were performed at selected ground sites in order to provide comparative calibration measurements of sensors for the Earth Resources Experiment Package. Specifically, the solar radiation (400 to 1300 namometers) and thermal radiation (8-14 micrometers) were measured. Sites employed for the thermal measurements consisted of warm and cold water lakes. The thermal brightness temperature of the lake water, the temperature and humidity profile above the lake, and near surface meteorology (wind speed, pressure, etc.) were measured near the time of overpass. Sites employed for the solar radiation measurements were two desert type sites. Ground measurements consisted of: (1) direct solar radiation - optical depth; (2) diffuse solar radiation; (3) total solar radiation, (4) target directional (normal) reflectance; (5) target hemispherical reflectance; and (6) near surface meteorology.

Spatial-mode storage in a gradient-echo memory

NASA Astrophysics Data System (ADS)

Higginbottom, D. B.; Sparkes, B. M.; Rancic, M.; Pinel, O.; Hosseini, M.; Lam, P. K.; Buchler, B. C.

2012-08-01

Three-level atomic gradient echo memory (Λ-GEM) is a proposed candidate for efficient quantum storage and for linear optical quantum computation with time-bin multiplexing [Hosseini , Nature (London)NATUAS0028-083610.1038/nature08325 461, 241 (2009)]. In this paper we investigate the spatial multimode properties of a Λ-GEM system. Using a high-speed triggered CCD, we demonstrate the storage of complex spatial modes and images. We also present an in-principle demonstration of spatial multiplexing by showing selective recall of spatial elements of a stored spin wave. Using our measurements, we consider the effect of diffusion within the atomic vapor and investigate its role in spatial decoherence. Our measurements allow us to quantify the spatial distortion due to both diffusion and inhomogeneous control field scattering and compare these to theoretical models.

Effect of progressively increasing lithium conditioning on edge transport and stability in high triangularity NSTX H-modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maingi, R.; Canik, J. M.; Bell, R. E.

A sequence of H-mode discharges with increasing levels of pre-discharge lithium evaporation (‘dose’) was conducted in high triangularity and elongation boundary shape in NSTX. Energy confinement increased, and recycling decreased with increasing lithium dose, similar to a previous lithium dose scan in medium triangularity and elongation plasmas. Data-constrained SOLPS interpretive modeling quantified the edge transport change: the electron particle diffusivity decreased by 10-30x. The electron thermal diffusivity decreased by 4x just inside the top of the pedestal, but increased by up to 5x very near the separatrix. These results provide a baseline expectation for lithium benefits in NSTX-U, which ismore » optimized for a boundary shape similar to the one in this experiment.« less

Effect of progressively increasing lithium conditioning on edge transport and stability in high triangularity NSTX H-modes

DOE PAGES

Maingi, R.; Canik, J. M.; Bell, R. E.; ...

2016-07-19

A sequence of H-mode discharges with increasing levels of pre-discharge lithium evaporation (‘dose’) was conducted in high triangularity and elongation boundary shape in NSTX. Energy confinement increased, and recycling decreased with increasing lithium dose, similar to a previous lithium dose scan in medium triangularity and elongation plasmas. Data-constrained SOLPS interpretive modeling quantified the edge transport change: the electron particle diffusivity decreased by 10-30x. The electron thermal diffusivity decreased by 4x just inside the top of the pedestal, but increased by up to 5x very near the separatrix. These results provide a baseline expectation for lithium benefits in NSTX-U, which ismore » optimized for a boundary shape similar to the one in this experiment.« less

Nanostructure control: Nucleation and diffusion studies for predictable ultra thin film morphologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hershberger, Matthew

This thesis covers PhD research on two systems with unique and interesting physics. The first system is lead (Pb) deposited on the silicon (111) surface with the 7x7 reconstruction. Pb and Si are mutually bulk insoluble resulting in this system being an ideal case for studying metal and semiconductor interactions. Initial Pb deposition causes an amorphous wetting layer to form across to surface. Continued deposition results in Pb(111) island growth. Classic literature has classified this system as the Stranski-Krastanov growth mode although the system is not near equilibrium conditions. Our research shows a growth mode distinctly different than classical expectationsmore » and begins a discussion of reclassifying diffusion and nucleation for systems far away from the well-studied equilibrium cases.« less

Influence of magnetic flutter on tearing growth in linear and nonlinear theory

NASA Astrophysics Data System (ADS)

Kreifels, L.; Hornsby, W. A.; Weikl, A.; Peeters, A. G.

2018-06-01

Recent simulations of tearing modes in turbulent regimes show an unexpected enhancement in the growth rate. In this paper the effect is investigated analytically. The enhancement is linked to the influence of turbulent magnetic flutter, which is modelled by diffusion terms in magnetohydrodynamics (MHD) momentum balance and Ohm’s law. Expressions for the linear growth rate as well as the island width in nonlinear theory for small amplitudes are derived. The results indicate an enhanced linear growth rate and a larger linear layer width compared with resistive MHD. Also the island width in the nonlinear regime grows faster in the diffusive model. These observations correspond well to simulations in which the effect of turbulence on the magnetic island width and tearing mode growth is analyzed.

Characterization and antimicrobial properties of food packaging methylcellulose films containing stem extract of Ginja cherry.

PubMed

Campos, Débora; Piccirillo, Clara; Pullar, Robert C; Castro, Paula Ml; Pintado, Maria M E

2014-08-01

Food contamination and spoilage is a problem causing growing concern. To avoid it, the use of food packaging with appropriate characteristics is essential; ideally, the packaging should protect food from external contamination and exhibit antibacterial properties. With this aim, methylcellulose (MC) films containing natural extracts from the stems of Ginja cherry, an agricultural by-product, were developed and characterized. The antibacterial activity of films was screened by the disc diffusion method and quantified using the viable cell count assay. The films inhibited the growth of both Gram-positive and Gram-negative strains (Listeria innocua, methicillin-sensitive Staphylococcus aureus, methicillin-resistant S. aureus, Salmonella Enteritidis, Escherichia coli). For the films with lower extract content, effectiveness against the microorganisms depended on the inoculum concentration. Scanning electron microscope images of the films showed that those containing the extracts had a smooth and continuous structure. UV-visible spectroscopy showed that these materials do not transmit light in the UV. This study shows that MC films containing agricultural by-products, in this case Ginja cherry stem extract, could be used to prevent food contamination by relevant bacterial strains and degradation by UV light. Using such materials in food packaging, the shelf life of food products could be extended while utilizing an otherwise wasted by-product. © 2013 Society of Chemical Industry.

Brownian motion of boomerang colloidal particles.

PubMed

Chakrabarty, Ayan; Konya, Andrew; Wang, Feng; Selinger, Jonathan V; Sun, Kai; Wei, Qi-Huo

2013-10-18

We investigate the Brownian motion of boomerang colloidal particles confined between two glass plates. Our experimental observations show that the mean displacements are biased towards the center of hydrodynamic stress (CoH), and that the mean-square displacements exhibit a crossover from short-time faster to long-time slower diffusion with the short-time diffusion coefficients dependent on the points used for tracking. A model based on Langevin theory elucidates that these behaviors are ascribed to the superposition of two diffusive modes: the ellipsoidal motion of the CoH and the rotational motion of the tracking point with respect to the CoH.

Brownian Motion of Boomerang Colloidal Particles

NASA Astrophysics Data System (ADS)

Chakrabarty, Ayan; Konya, Andrew; Wang, Feng; Selinger, Jonathan V.; Sun, Kai; Wei, Qi-Huo

2013-10-01

We investigate the Brownian motion of boomerang colloidal particles confined between two glass plates. Our experimental observations show that the mean displacements are biased towards the center of hydrodynamic stress (CoH), and that the mean-square displacements exhibit a crossover from short-time faster to long-time slower diffusion with the short-time diffusion coefficients dependent on the points used for tracking. A model based on Langevin theory elucidates that these behaviors are ascribed to the superposition of two diffusive modes: the ellipsoidal motion of the CoH and the rotational motion of the tracking point with respect to the CoH.

First-principles investigation of diffusion and defect properties of Fe and Ni in Cr2O3

NASA Astrophysics Data System (ADS)

Rak, Zs.; Brenner, D. W.

2018-04-01

Diffusion of Fe and Ni and the energetics of Fe- and Ni-related defects in chromium oxide (α-Cr2O3) are investigated using first-principles Density Functional Theory calculations in combination with the climbing-image nudged elastic band method. The orientations of the spin magnetic moments of the migrating ions are taken into account and their effects on migration barriers are examined. Several possible diffusion pathways were explored through interstitial and vacancy mechanisms, and it was found that the principal mode of ion transport in Cr2O3 is via vacancies. Both interstitial- and vacancy-mediated diffusions are anisotropic, with diffusion being faster in the z-direction. The energetics of defect formation indicates that the Ni-related defects are less stable than the Fe-related ones. This is consistent with Ni-diffusion being faster than Fe-diffusion. The results are compared with previous theoretical and experimental data and possible implications in corrosion control are discussed.

Dual view FIDA measurements on MAST

NASA Astrophysics Data System (ADS)

Michael, C. A.; Conway, N.; Crowley, B.; Jones, O.; Heidbrink, W. W.; Pinches, S.; Braeken, E.; Akers, R.; Challis, C.; Turnyanskiy, M.; Patel, A.; Muir, D.; Gaffka, R.; Bailey, S.

2013-09-01

A fast-ion deuterium alpha (FIDA) spectrometer was installed on MAST to measure radially resolved information about the fast-ion density and its distribution in energy and pitch angle. Toroidally and vertically directed collection lenses are employed, to detect both passing and trapped particle dynamics, and reference views are installed to subtract the background. This background is found to contain a substantial amount of passive FIDA emission driven by edge neutrals, and to depend delicately on viewing geometry. Results are compared with theoretical expectations based on the codes NUBEAM (for fast-ion distributions) and FIDASIM. Calibrating via the measured beam emission peaks, the toroidal FIDA signal profile agrees with classical simulations in magnetohydrodynamic quiescent discharges where the neutron rate is also classical. Long-lived modes (LLMs) and chirping modes decrease the core FIDA signal significantly, and the profile can be matched closely to simulations using anomalous diffusive transport; a spatially uniform diffusion coefficient is sufficient for chirping modes, while a core localized diffusion is better for a LLM. Analysis of a discharge with chirping mode activity shows a dramatic drop in the core FIDA signal and rapid increase in the edge passive signal at the onset of the burst indicating a very rapid redistribution towards the edge. Vertical-viewing measurements show a discrepancy with simulations at higher Doppler shifts when the neutron rate is classical, which, combined with the fact that the toroidal signals agree, means that the difference must be occurring for pitch angles near the trapped-passing boundary, although uncertainties in the background subtraction, which are difficult to assess, may contribute to this. Further evidence of an anomalous transport mechanism for these particles is provided by the fact that an increase of beam power does not increase the higher energy vertical FIDA signals, while the toroidal signals do increase.

Implementation of the full viscoresistive magnetohydrodynamic equations in a nonlinear finite element code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haverkort, J.W.; Dutch Institute for Fundamental Energy Research, P.O. Box 6336, 5600 HH Eindhoven; Blank, H.J. de

Numerical simulations form an indispensable tool to understand the behavior of a hot plasma that is created inside a tokamak for providing nuclear fusion energy. Various aspects of tokamak plasmas have been successfully studied through the reduced magnetohydrodynamic (MHD) model. The need for more complete modeling through the full MHD equations is addressed here. Our computational method is presented along with measures against possible problems regarding pollution, stability, and regularity. The problem of ensuring continuity of solutions in the center of a polar grid is addressed in the context of a finite element discretization of the full MHD equations. Amore » rigorous and generally applicable solution is proposed here. Useful analytical test cases are devised to verify the correct implementation of the momentum and induction equation, the hyperdiffusive terms, and the accuracy with which highly anisotropic diffusion can be simulated. A striking observation is that highly anisotropic diffusion can be treated with the same order of accuracy as isotropic diffusion, even on non-aligned grids, as long as these grids are generated with sufficient care. This property is shown to be associated with our use of a magnetic vector potential to describe the magnetic field. Several well-known instabilities are simulated to demonstrate the capabilities of the new method. The linear growth rate of an internal kink mode and a tearing mode are benchmarked against the results of a linear MHD code. The evolution of a tearing mode and the resulting magnetic islands are simulated well into the nonlinear regime. The results are compared with predictions from the reduced MHD model. Finally, a simulation of a ballooning mode illustrates the possibility to use our method as an ideal MHD method without the need to add any physical dissipation.« less

Virtex-5 CN Package Daisy Chain Evaluation Test Report

NASA Technical Reports Server (NTRS)

Suh, Jong-ook

2016-01-01

The board-level temperature cycling reliability of Xilinx Virtex-5 (V5) CN package was investigated. V5s were temperature cycled under two conditions, 0 to +100 C (0/100) and -55 to +100 C (-55/100). During the 0/100 test, no part out of 8 parts failed up to 6586 cycles. During the -55/100 test, one part out of 8 parts failed at 1236 cycle, and there were no additional failures up to 1705 cycles. The failure mode of the part that failed at 1236 cycles indicated that most likely the failure was not a solder fatigue failure, and therefore no obvious solder fatigue failure was observed throughout the tests.

E-Cigarette Liquid Nicotine Ingestion in a Child: Case Report and Discussion.

PubMed

Gill, Natasha; Sangha, Gurinder; Poonai, Naveen; Lim, Rodrick

2015-11-01

Nicotine poisoning is well described in the pediatric population, and even small oral doses may result in toxic effects. The source of nicotine is usually tobacco products and nicotine replacement products such as gum and patches. With the more frequent use of novel products such as e-cigarettes, concern has arisen regarding liquid nicotine. As there are no regulations regarding childproof bottling and packaging, there may be increased potential for unintentional ingestion of these colorfully and appealingly packaged products by children. We present and discuss a case of this nature, as we feel emergency physicians should be aware of this new mode of poisoning, and public health efforts should be made to minimize such exposures.

Thermophysical Properties of Sn-Ag-Cu Based Pb-Free Solders

NASA Astrophysics Data System (ADS)

Kim, Sok Won; Lee, Jaeran; Jeon, Bo-Min; Jung, Eun; Lee, Sang Hyun; Kang, Kweon Ho; Lim, Kwon Taek

2009-06-01

Lead-tin (Pb-Sn) alloys are the dominant solders used for electronic packaging because of their low cost and superior properties required for interconnecting electronic components. However, increasing environmental and health concerns over the toxicity of lead, combined with global legislation to limit the use of Pb in manufactured products, have led to extensive research and development studies of lead-free solders. The Sn-Ag-Cu ternary eutectic alloy is considered to be one of the promising alternatives. Except for thermal properties, much research on several properties of Sn-Ag-Cu alloy has been performed. In this study, five Sn-xAg-0.5Cu alloys with variations of Ag content x of 1.0 mass%, 2.5 mass%, 3.0 mass%, 3.5 mass%, and 4.0 mass% were prepared, and their thermal diffusivity and specific heat were measured from room temperature to 150 °C, and the thermal conductivity was calculated using the measured thermal diffusivity, specific heat, and density values. Also, the linear thermal expansion was measured from room temperature to 170 °C. The results show that Sn-3.5Ag-0.5Cu is the best candidate because it has a maximum thermal conductivity and a low thermal expansion, which are the ideal conditions to be a proper packaging alloy for effective cooling and thermostability.

Active nanocomposite films based on soy proteins-montmorillonite- clove essential oil for the preservation of refrigerated bluefin tuna (Thunnus thynnus) fillets.

PubMed

Echeverría, Ignacio; López-Caballero, María Elvira; Gómez-Guillén, María Carmen; Mauri, Adriana Noemi; Montero, María Pilar

2018-02-02

This manuscript evaluates the potential application of active nanocomposite films based on soy protein isolate (SPI)-montmorillonite (MMT)-clove essential oil (CEO) to the preservation of muscle fillets of bluefin tuna (Thunnus thynnus) during refrigerated storage, and furthermore analyzes whether the clay diffuses from the package to food. SPI films with: CEO (SPI-CEO), MMT (SPI-MMT), or both CEO and MMT (SPI-MMT-CEO), were prepared and used to cover tuna fillets during 17days of storage at 2°C. Polyethylene films were also used as control. Protein films nanoreinforced with 10g MMT/100g SPI and activated with CEO were able to decrease microbial growth (evaluated by TVBN and microorganism counts) and lipid autooxidation (evaluated according to the TBA index, FTIR and color parameters) of tuna fillets during the storage period studied. The presence of clay seemed to favor the release of the active principles of clove oil by prolonging its antimicrobial (especially effective to inhibit Pseudomonas spp.) and antioxidant activity over time without observing the diffusion of the clay's own metals (Si and Al) from the nanocomposite materials to the muscle of fish. These results are encouraging for the use of nanocomposite films in food packaging. Copyright © 2017 Elsevier B.V. All rights reserved.

Can a one-layer optical skin model including melanin and inhomogeneously distributed blood explain spatially resolved diffuse reflectance spectra?

NASA Astrophysics Data System (ADS)

Karlsson, Hanna; Pettersson, Anders; Larsson, Marcus; Strömberg, Tomas

2011-02-01

Model based analysis of calibrated diffuse reflectance spectroscopy can be used for determining oxygenation and concentration of skin chromophores. This study aimed at assessing the effect of including melanin in addition to hemoglobin (Hb) as chromophores and compensating for inhomogeneously distributed blood (vessel packaging), in a single-layer skin model. Spectra from four humans were collected during different provocations using a twochannel fiber optic probe with source-detector separations 0.4 and 1.2 mm. Absolute calibrated spectra using data from either a single distance or both distances were analyzed using inverse Monte Carlo for light transport and Levenberg-Marquardt for non-linear fitting. The model fitting was excellent using a single distance. However, the estimated model failed to explain spectra from the other distance. The two-distance model did not fit the data well at either distance. Model fitting was significantly improved including melanin and vessel packaging. The most prominent effect when fitting data from the larger separation compared to the smaller separation was a different light scattering decay with wavelength, while the tissue fraction of Hb and saturation were similar. For modeling spectra at both distances, we propose using either a multi-layer skin model or a more advanced model for the scattering phase function.

Theory of a time-dependent heat diffusion determination of thermal diffusivities with a single temperature measurement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perez, R. B.; Carroll, R. M.; Sisman, O.

1971-02-01

A method to measure the thermal diffusivity of reactor fuels during irradiation is developed, based on a time-dependent heat diffusion equation. With this technique the temperature is measured at only one point in the fuel specimen. This method has the advantage that it is not necessary to know the heat generation (a difficult evaluation during irradiation). The theory includes realistic boundary conditions, applicable to actual experimental systems. The parameters are the time constants associated with the first two time modes in the temperature-vs-time curve resulting from a step change in heat input to the specimen. With the time constants andmore » the necessary material properties and dimensions of the specimen and specimen holder, the thermal diffusivity of the specimen can be calculated.« less

The Generic Mapping Tools 6: Classic versus Modern Mode

NASA Astrophysics Data System (ADS)

Wessel, P.; Uieda, L.; Luis, J. M. F.; Scharroo, R.; Smith, W. H. F.; Wobbe, F.

2017-12-01

The Generic Mapping Tools (GMT; gmt.soest.hawaii.edu) is a 25-year old, mature open-source software package for the analysis and display of geoscience data (e.g., interpolate, filter, manipulate, project and plot temporal and spatial data). The GMT "toolbox" includes about 80 core and 40 supplemental modules sharing a common set of command options, file structures, and documentation. GMT5, when released in 2013, introduced an application programming interface (API) to allow programmatic access to GMT from other computing environments. Since then, we have released a GMT/MATLAB toolbox, an experimental GMT/Julia package, and will soon introduce a GMT/Python module. In developing these extensions, we wanted to simplify the GMT learning curve but quickly realized the main stumbling blocks to GMT command-line mastery would be ported to the external environments unless we introduced major changes. With thousands of GMT scripts already in use by scientists around the world, we were acutely aware of the need for backwards compatibility. Our solution, to be released as GMT 6, was to add a modern run mode that complements the classic mode offered so far. Modern mode completely eliminates the top three obstacles for new (and not so new) GMT users: (1) The responsibility to properly stack PostScript layers manually (i.e., the -O -K dance), (2) the responsibility of handling output redirection of PostScript (create versus append), and (3) the need to provide commands with repeated information about regions (-R) and projections (-J). Thus, modern mode results in shorter, simpler scripts with fewer pitfalls, without interfering with classic scripts. Our implementation adds five new commands that begin and end a modern session, simplify figure management, automate the conversion of PostScript to more suitable formats, automate region detection, and offer a new automated subplot environment for multi-panel illustrations. Here, we highlight the GMT modern mode and the simplifications it offers, both for command-line use and in external environments. GMT 6 is in beta mode but accessible from our repository. Numerous improvements have been added in addition to modern mode; we expect a formal release in early 2018. Publication partially supported by FCT project UID/GEO/50019/2013 - Instituto D. Luiz.

Dynamic Light Scattering Study of Pig Vitreous Body

NASA Astrophysics Data System (ADS)

Matsuura, Toyoaki; Idota, Naokazu; Hara, Yoshiaki; Annaka, Masahiko

The phase behaviors and dynamical properties of pig vitreous body were studied by macroscopic observation of swelling behavior and dynamic light scattering under various conditions. From the observations of the dynamics of light scattered by the pig vitreous body under physiological condition, intensity autocorrelation functions that revealed two diffusion coefficients, D fast and D slow were obtained. We developed the theory for describing the density fluctuation of the entities in the vitreous gel system with sodium hyaluronate filled in the meshes of collagen fiber network. The dynamics of collagen and sodium hyaluronate explains two relaxation modes of the fluctuation. The diffusion coefficient of collagen obtained from D fast and D slow is very close to that in aqueous solution, which suggests the vitreous body is in the swollen state. Divergent behavior in the measured total scattered light intensities and diffusion coefficients upon varying the concentration of salt (NaCl and CaCl2) was observed. Namely, a slowing down of the dynamic modes accompanied by increased “static” scattered intensities was observed. This is indicative of the occurrence of a phase transition upon salt concentration.

Superthermal Electron Magnetosphere-Ionosphere Coupling in the Diffuse Aurora in the Presence of ECH Waves

NASA Technical Reports Server (NTRS)

Khazanov, G. V.; Tripathi, A. K.; Singhal, R. P.; Himwich, Elizabeth; Glocer, A.; Sibeck, D. G.

2015-01-01

There are two main theories for the origin of the diffuse auroral electron precipitation: first, pitch angle scattering by electrostatic electron cyclotron harmonic (ECH) waves, and second, by whistler mode waves. Precipitating electrons initially injected from the plasma sheet to the loss cone via wave-particle interaction processes degrade in the atmosphere toward lower energies and produce secondary electrons via impact ionization of the neutral atmosphere. These secondary electrons can escape back to the magnetosphere, become trapped on closed magnetic field lines, and deposit their energy back to the inner magnetosphere. ECH and whistler mode waves can also move electrons in the opposite direction, from the loss cone into the trap zone, if the source of such electrons exists in conjugate ionospheres located at the same field lines as the trapped magnetospheric electron population. Such a situation exists in the simulation scenario of superthermal electron energy interplay in the region of diffuse aurora presented and discussed by Khazanov et al. (2014) and will be quantified in this paper by taking into account the interaction of secondary electrons with ECH waves.

Application of interleaving models for the description of intrusive layering at the fronts of deep polar water in the Eurasian Basin (Arctic)

NASA Astrophysics Data System (ADS)

Kuzmina, N. P.; Zhurbas, N. V.; Emelianov, M. V.; Pyzhevich, M. L.

2014-09-01

Interleaving models of pure thermohaline and baroclinic frontal zones are applied to describe intrusions at the fronts found in the upper part of the Deep Polar Water (DPW) when the stratification was absolutely stable. It is assumed that differential mixing is the main mechanism of the intrusion formation. Important parameters of the interleaving such as the growth rate, vertical scale, and slope of the most unstable modes relative to the horizontal plane are calculated. It was found that the interleaving model for a pure thermohaline front satisfactory describes the important intrusion parameters observed at the frontal zone. In the case of a baroclinic front, satisfactory agreement over all the interleaving parameters is observed between the model calculations and observations provided that the vertical momentum diffusivity significantly exceeds the corresponding coefficient of mass diffusivity. Under specific (reasonable) constraints of the vertical momentum diffusivity, the most unstable mode has a vertical scale approximately two-three times smaller than the vertical scale of the observed intrusions. A thorough discussion of the results is presented.

Advanced Silicon Detectors for High Energy Astrophysics Missions

NASA Technical Reports Server (NTRS)

Ricker, George

2005-01-01

A viewgraph presentation on the development of silicon detectors for high energy astrophysics missions is presented. The topics include: 1) Background: Motivation for Event-Driven CCD; 2) Report of Grant Activity; 3) Packaged EDCCD; 4) Measured X-ray Energy Resolution of the Gen1 EDCCDs Operated in "Conventional Mode"; and 5) EDCCD Gen 1.5-Lot 1 Planning.

Computational Analyses in Support of Sub-scale Diffuser Testing for the A-3 Facility. Part 2; Unsteady Analyses and Risk Assessment

NASA Technical Reports Server (NTRS)

Ahuja, Vineet; Hosangadi, Ashvin; Allgood, Daniel

2008-01-01

Simulation technology can play an important role in rocket engine test facility design and development by assessing risks, providing analysis of dynamic pressure and thermal loads, identifying failure modes and predicting anomalous behavior of critical systems. This is especially true for facilities such as the proposed A-3 facility at NASA SSC because of a challenging operating envelope linked to variable throttle conditions at relatively low chamber pressures. Design Support of the feasibility of operating conditions and procedures is critical in such cases due to the possibility of startup/shutdown transients, moving shock structures, unsteady shock-boundary layer interactions and engine and diffuser unstart modes that can result in catastrophic failure. Analyses of such systems is difficult due to resolution requirements needed to accurately capture moving shock structures, shock-boundary layer interactions, two-phase flow regimes and engine unstart modes. In a companion paper, we will demonstrate with the use of CFD, steady analyses advanced capability to evaluate supersonic diffuser and steam ejector performance in the sub-scale A-3 facility. In this paper we will address transient issues with the operation of the facility especially at startup and shutdown, and assess risks related to afterburning due to the interaction of a fuel rich plume with oxygen that is a by-product of the steam ejectors. The primary areas that will be addressed in this paper are: (1) analyses of unstart modes due to flow transients especially during startup/ignition, (2) engine safety during the shutdown process (3) interaction of steam ejectors with the primary plume i.e. flow transients as well as probability of afterburning. In this abstract we discuss unsteady analyses of the engine shutdown process. However, the final paper will include analyses of a staged startup, drawdown of the engine test cell pressure, and risk assessment of potential afterburning in the facility. Unsteady simulations have been carried out to study the engine shutdown process in the facility and understand the physics behind the interactions between the steam ejectors, the test cell and the supersonic diffuser. As a first approximation, to understand the dominant unsteady mechanisms in the engine test cell and the supersonic diffuser, the turning duct in the facility was removed. As the engine loses power a rarefaction wave travels downstream that disrupts the shock cell structure in the supersonic diffuser. Flow from the test cell is seen to expand into the supersonic diffuser section and re-pressurizes the area around the nozzle along with a upstream traveling compression wave that emanates from near the first stage ejectors. Flow from the first stage ejector expands to the center of the duct and a new shock train is formed between the first and second stage ejectors. Both stage ejectors keep the facility pressurized and prevent any large amplitude pressure fluctuations from affecting the engine nozzle. The resultant pressure loads the nozzle experiences in the shutdown process are small.

Instantaneous normal mode analysis of the vibrational relaxation of the amide I mode of alanine dipeptide in water.

PubMed

Farag, Marwa H; Zúñiga, José; Requena, Alberto; Bastida, Adolfo

2013-05-28

Nonequilibrium Molecular Dynamics (MD) simulations coupled to instantaneous normal modes (INMs) analysis are used to study the vibrational relaxation of the acetyl and amino-end amide I modes of the alanine dipeptide (AlaD) molecule dissolved in water (D2O). The INMs are assigned in terms of the equilibrium normal modes using the Effective Atomic Min-Cost algorithm as adapted to make use of the outputs of standard MD packages, a method which is well suited for the description of flexible molecules. The relaxation energy curves of both amide I modes show multiexponential decays, in good agreement with the experimental findings. It is found that ~85%-90% of the energy relaxes through intramolecular vibrational redistribution. The main relaxation pathways are also identified. The rate at which energy is transferred into the solvent is similar for the acetyl-end and amino-end amide I modes. The conformational changes occurring during relaxation are investigated, showing that the populations of the alpha and beta region conformers are altered by energy transfer in such a way that it takes 15 ps for the equilibrium conformational populations to be recovered after the initial excitation of the AlaD molecule.

Modes and emergent time scales of embayed beach dynamics

NASA Astrophysics Data System (ADS)

Ratliff, Katherine M.; Murray, A. Brad

2014-10-01

In this study, we use a simple numerical model (the Coastline Evolution Model) to explore alongshore transport-driven shoreline dynamics within generalized embayed beaches (neglecting cross-shore effects). Using principal component analysis (PCA), we identify two primary orthogonal modes of shoreline behavior that describe shoreline variation about its unchanging mean position: the rotation mode, which has been previously identified and describes changes in the mean shoreline orientation, and a newly identified breathing mode, which represents changes in shoreline curvature. Wavelet analysis of the PCA mode time series reveals characteristic time scales of these modes (typically years to decades) that emerge within even a statistically constant white-noise wave climate (without changes in external forcing), suggesting that these time scales can arise from internal system dynamics. The time scales of both modes increase linearly with shoreface depth, suggesting that the embayed beach sediment transport dynamics exhibit a diffusive scaling.

CarbAl Heat Transfer Material

NASA Technical Reports Server (NTRS)

Fink, Richard

2015-01-01

The increasing use of power electronics, such as high-current semiconductor devices and modules, within space vehicles is driving the need to develop specialty thermal management materials in both the packaging of these discrete devices and the packaging of modules consisting of these device arrays. Developed by Applied Nanotech, Inc. (ANI), CarbAl heat transfer material is uniquely characterized by its low density, high thermal diffusivity, and high thermal conductivity. Its coefficient of thermal expansion (CTE) is similar to most power electronic materials, making it an effective base plate substrate for state-of-the-art silicon carbide (SiC) super junction transistors. The material currently is being used to optimize hybrid vehicle inverter packaging. Adapting CarbAl-based substrates to space applications was a major focus of the SBIR project work. In Phase I, ANI completed modeling and experimentation to validate its deployment in a space environment. Key parameters related to cryogenic temperature scaling of CTE, thermal conductivity, and mechanical strength. In Phase II, the company concentrated on improving heat sinks and thermally conductive circuit boards for power electronic applications.

A fast semi-discrete Kansa method to solve the two-dimensional spatiotemporal fractional diffusion equation

NASA Astrophysics Data System (ADS)

Sun, HongGuang; Liu, Xiaoting; Zhang, Yong; Pang, Guofei; Garrard, Rhiannon

2017-09-01

Fractional-order diffusion equations (FDEs) extend classical diffusion equations by quantifying anomalous diffusion frequently observed in heterogeneous media. Real-world diffusion can be multi-dimensional, requiring efficient numerical solvers that can handle long-term memory embedded in mass transport. To address this challenge, a semi-discrete Kansa method is developed to approximate the two-dimensional spatiotemporal FDE, where the Kansa approach first discretizes the FDE, then the Gauss-Jacobi quadrature rule solves the corresponding matrix, and finally the Mittag-Leffler function provides an analytical solution for the resultant time-fractional ordinary differential equation. Numerical experiments are then conducted to check how the accuracy and convergence rate of the numerical solution are affected by the distribution mode and number of spatial discretization nodes. Applications further show that the numerical method can efficiently solve two-dimensional spatiotemporal FDE models with either a continuous or discrete mixing measure. Hence this study provides an efficient and fast computational method for modeling super-diffusive, sub-diffusive, and mixed diffusive processes in large, two-dimensional domains with irregular shapes.

PLATSIM: An efficient linear simulation and analysis package for large-order flexible systems

NASA Technical Reports Server (NTRS)

Maghami, Periman; Kenny, Sean P.; Giesy, Daniel P.

1995-01-01

PLATSIM is a software package designed to provide efficient time and frequency domain analysis of large-order generic space platforms implemented with any linear time-invariant control system. Time domain analysis provides simulations of the overall spacecraft response levels due to either onboard or external disturbances. The time domain results can then be processed by the jitter analysis module to assess the spacecraft's pointing performance in a computationally efficient manner. The resulting jitter analysis algorithms have produced an increase in speed of several orders of magnitude over the brute force approach of sweeping minima and maxima. Frequency domain analysis produces frequency response functions for uncontrolled and controlled platform configurations. The latter represents an enabling technology for large-order flexible systems. PLATSIM uses a sparse matrix formulation for the spacecraft dynamics model which makes both the time and frequency domain operations quite efficient, particularly when a large number of modes are required to capture the true dynamics of the spacecraft. The package is written in MATLAB script language. A graphical user interface (GUI) is included in the PLATSIM software package. This GUI uses MATLAB's Handle graphics to provide a convenient way for setting simulation and analysis parameters.

Influence of metal bonding layer on strain transfer performance of FBG

NASA Astrophysics Data System (ADS)

Liu, Hao; Chen, Weimin; Zhang, Peng; Liu, Li; Shu, Yuejie; Wu, Jun

2013-01-01

Metal bonding layer seriously affects the strain transfer performance of Fiber Bragg Grating (FBG). Based on the mode of FBG strain transfer, the influence of the length, the thickness, Poisson's ratio, elasticity modulus of metal bonding layer on the strain transfer coefficient of FBG is analyzed by numerical simulation. FBG is packaged to steel wire using metal bonding technology of FBG. The tensile tests of different bonding lengths and elasticity modulus are carried out. The result shows the strain transfer coefficient of FBGs are 0.9848,0.962 and their average strain sensitivities are 1.076 pm/μɛ,1.099 pm/μɛ when the metal bonding layer is zinc, whose lengths are 15mm, 20mm, respectively. The strain transfer coefficient of FBG packaged by metal bonding layer raises 8.9 percent compared to epoxy glue package. The preliminary experimental results show that the strain transfer coefficient increases with the length of metal bonding layer, decreases with the thickness of metal bonding layer and the influence of Poisson's ratio can be ignored. The experiment result is general agreement with the analysis and provides guidance for metal package of FBG.

Addressable microshutter array for a high-performance infrared miniature dispersive spectrometer

NASA Astrophysics Data System (ADS)

Ilias, S.; Picard, F.; Larouche, C.; Kruzelecky, R.; Jamroz, W.

2009-02-01

Programmable microshutter arrays were designed to improve the attainable signal to noise ratio (SNR) of a miniature dispersive spectrometer developed for space applications. Integration of a microshutter array to this instrument provides advantages such as the addition of a binary coded optical input operation mode for the miniature spectrometer which results in SNR benefits without spectral resolution loss. These arrays were successfully fabricated using surface micromachining technology. Each microshutter is basically an electrostatic zipping actuator having a curved shape. Applying critical voltage to one microshutter pulls the actuator down to the substrate and closes the associated slit. Opening of the microslits relies on the restoring force generated within the actuated zippers. High light transmission is obtained with the actuator in the open position and excellent light blocking is observed when the shutter is closed. The pull-in voltage to close the microslits was about 110 V and the response times to close and open the microslits were about 2 ms and 7 ms, respectively. Selected array dies were mounted in modified off-the-shelf ceramic packages and electrically connected to package pins. The packages were hermetically sealed with AR coated sapphire windows. This last packaging step was performed in a dry nitrogen controlled atmosphere.

Density perturbation mode structure of high frequency compressional and global Alfvén eigenmodes in the National Spherical Torus Experiment using a novel reflectometer analysis technique

NASA Astrophysics Data System (ADS)

Crocker, N. A.; Kubota, S.; Peebles, W. A.; Rhodes, T. L.; Fredrickson, E. D.; Belova, E.; Diallo, A.; LeBlanc, B. P.; Sabbagh, S. A.

2018-01-01

Reflectometry measurements of compressional (CAE) and global (GAE) Alfvén eigenmodes are analyzed to obtain the amplitude and spatial structure of the density perturbations associated with the modes. A novel analysis technique developed for this purpose is presented. The analysis also naturally yields the amplitude and spatial structure of the density contour radial displacement, which is found to be 2-4 times larger than the value estimated directly from the reflectometer measurements using the much simpler ‘mirror approximation’. The modes were driven by beam ions in a high power (6 MW) neutral beam heated H-mode discharge (#141398) in the National Spherical Torus Experiment. The results of the analysis are used to assess the contribution of the modes to core energy transport and ion heating. The total displacement amplitude of the modes, which is shown to be larger than previously estimated (Crocker et al 2013 Nucl. Fusion 53 43017), is compared to the predicted threshold (Gorelenkov et al 2010 Nucl. Fusion 50 84012) for the anomalously high heat diffusion inferred from transport modeling in similar NSTX discharges. The results of the analysis also have strong implications for the energy transport via coupling of CAEs to kinetic Alfvén waves seen in simulations with the Hybrid MHD code (Belova et al 2015 Phys. Rev. Lett. 115 15001). Finally, the amplitudes of the observed CAEs fall well below the threshold for causing significant ion heating by stochastic velocity space diffusion (Gates et al 2001 Phys. Rev. Lett. 87 205003).

ADVANTG Shielding Analysis for Closure Operations in an Open-Mode Repository

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bevill, Aaron M; Radulescu, Georgeta; Scaglione, John M

2013-01-01

en-mode repository concepts could require worker entry into access drifts after placement of fuel casks in order to perform activities related to backfill, plug emplacement, routine maintenance, or performance confirmation. An ideal emplacement-drift shielding configuration would minimize dose to workers while maximizing airflow through the emplacement drifts. This paper presents a preliminary investigation of the feasibility and effectiveness of radiation shielding concepts that could be employed to facilitate worker operations in an open-mode repository. The repository model for this study includes pressurized-water reactor fuel assemblies (60 GWd/MTU burnup, 40 year post-irradiation cooldown) in packages of 32 assemblies. The closest fuelmore » packages are 5 meters from dosimetry voxels in the access drift. The unshielded dose to workers in the access drift is 73.7 rem/hour. Prior work suggests that open-mode repository concepts similar to this one would require 15 m3/s of ventilation airflow. Shielding concepts considered here include partial concrete plugs, labyrinthine shields, and stainless steel photon attenuator grids. Maximum dose to workers in the access drift was estimated for each shielding concept using MCNP5 with variance reduction parameters generated by ADVANTG. Because airflow through the shielding is important for open-mode repositories, a semi-empirical estimate of the head loss due to each shielding configuration was also calculated. Airflow and shielding performance vary widely among the proposed shielding configurations. Although the partial plug configuration had the best airflow performance, it allowed dose rates 1500 greater than the specified target. Labyrinthine shielding concepts yield doses on the order of 1 mrem/hour with configurations that impose 3 to 11 J/kg head loss. Adding 1 cm lead lining to the airflow channels of labyrinthine designs further reduces the worker dose by 65% to 95%. Photon-attenuator concepts may reduce worker dose to as low as 29 mrem/hour with head loss on the order of 1.9 J/kg.« less

Fast-sausage oscillations in coronal loops with smooth boundary

NASA Astrophysics Data System (ADS)

Lopin, I.; Nagorny, I.

2014-12-01

Aims: The effect of the transition layer (shell) in nonuniform coronal loops with a continuous radial density profile on the properties of fast-sausage modes are studied analytically and numerically. Methods: We modeled the coronal waveguide as a structured tube consisting of a cord and a transition region (shell) embedded within a magnetic uniform environment. The derived general dispersion relation was investigated analytically and numerically in the context of frequency, cut-off wave number, and the damping rate of fast-sausage oscillations for various values of loop parameters. Results: The frequency of the global fast-sausage mode in the loops with a diffuse (or smooth) boundary is determined mainly by the external Alfvén speed and longitudinal wave number. The damping rate of such a mode can be relatively low. The model of coronal loop with diffuse boundary can support a comparatively low-frequency, global fast-sausage mode of detectable quality without involving extremely low values of the density contrast. The effect of thin transition layer (corresponds to the loops with steep boundary) is negligible and produces small reductions of oscillation frequency and relative damping rate in comparison with the case of step-function density profile. Seismological application of obtained results gives the estimated Alfvén speed outside the flaring loop about 3.25 Mm/s.

Quantifying urban growth patterns in Hanoi using landscape expansion modes and time series spatial metrics.

PubMed

Nong, Duong H; Lepczyk, Christopher A; Miura, Tomoaki; Fox, Jefferson M

2018-01-01

Urbanization has been driven by various social, economic, and political factors around the world for centuries. Because urbanization continues unabated in many places, it is crucial to understand patterns of urbanization and their potential ecological and environmental impacts. Given this need, the objectives of our study were to quantify urban growth rates, growth modes, and resultant changes in the landscape pattern of urbanization in Hanoi, Vietnam from 1993 to 2010 and to evaluate the extent to which the process of urban growth in Hanoi conformed to the diffusion-coalescence theory. We analyzed the spatiotemporal patterns and dynamics of the built-up land in Hanoi using landscape expansion modes, spatial metrics, and a gradient approach. Urbanization was most pronounced in the periods of 2001-2006 and 2006-2010 at a distance of 10 to 35 km around the urban center. Over the 17 year period urban expansion in Hanoi was dominated by infilling and edge expansion growth modes. Our findings support the diffusion-coalescence theory of urbanization. The shift of the urban growth areas over time and the dynamic nature of the spatial metrics revealed important information about our understanding of the urban growth process and cycle. Furthermore, our findings can be used to evaluate urban planning policies and aid in urbanization issues in rapidly urbanizing countries.

Singular value decomposition metrics show limitations of detector design in diffuse fluorescence tomography

PubMed Central

Leblond, Frederic; Tichauer, Kenneth M.; Pogue, Brian W.

2010-01-01

The spatial resolution and recovered contrast of images reconstructed from diffuse fluorescence tomography data are limited by the high scattering properties of light propagation in biological tissue. As a result, the image reconstruction process can be exceedingly vulnerable to inaccurate prior knowledge of tissue optical properties and stochastic noise. In light of these limitations, the optimal source-detector geometry for a fluorescence tomography system is non-trivial, requiring analytical methods to guide design. Analysis of the singular value decomposition of the matrix to be inverted for image reconstruction is one potential approach, providing key quantitative metrics, such as singular image mode spatial resolution and singular data mode frequency as a function of singular mode. In the present study, these metrics are used to analyze the effects of different sources of noise and model errors as related to image quality in the form of spatial resolution and contrast recovery. The image quality is demonstrated to be inherently noise-limited even when detection geometries were increased in complexity to allow maximal tissue sampling, suggesting that detection noise characteristics outweigh detection geometry for achieving optimal reconstructions. PMID:21258566

A dynamic model of the radiation-belt electron phase-space density based on POLAR/HIST measurements

NASA Astrophysics Data System (ADS)

Vassiliadis, D.; Green, J. C.

2007-12-01

The response of the energetic-electron phase-space density (PSD) in the radiation belts is subject to a delicate combination of acceleration and loss processes which are strongly determined by the magnetospheric configuration and field disturbance level. We quantify the response of the density to stormtime fields as observed by the HIST detector on board POLAR. Several distinct modes are identified, characterized by peak second- and third- adiabatic invariants and peak delay time. The modes represent quasiadiabatic transport due to ring current activity; high L* (~6), day-long acceleration linked to ULF wave-particle interaction; and low-L* (~3), minute- to hour-long acceleration interpreted to be due to transient inductive fields or VLF wave-particle interaction. The net transport due to these responses is not always or everywhere diffusive, therefore we quantify the degree of departure from diffusive transport for specific storm intervals and radial ranges. Taken together the response modes comprise a dynamic, nonlinear model which allows us to better understand the historic variability of the high-energy tail of the electron distribution in the inner magnetosphere.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cooke, Ilsa R.; Fayolle, Edith C.; Öberg, Karin I., E-mail: irc5zb@virginia.edu

CO{sub 2} ice is an important reservoir of carbon and oxygen in star- and planet-forming regions. Together with water and CO, CO{sub 2} sets the physical and chemical characteristics of interstellar icy grain mantles, including desorption and diffusion energies for other ice constituents. A detailed understanding of CO{sub 2} ice spectroscopy is a prerequisite to characterize CO{sub 2} interactions with other volatiles both in interstellar ices and in laboratory experiments of interstellar ice analogs. We report laboratory spectra of the CO{sub 2} longitudinal optical (LO) phonon mode in pure CO{sub 2} ice and in CO{sub 2} ice mixtures with H{submore » 2}O, CO, and O{sub 2} components. We show that the LO phonon mode position is sensitive to the mixing ratio of various ice components of astronomical interest. In the era of the James Webb Space Telescope , this characteristic could be used to constrain interstellar ice compositions and morphologies. More immediately, LO phonon mode spectroscopy provides a sensitive probe of ice mixing in the laboratory and should thus enable diffusion measurements with higher precision than has been previously possible.« less

Isotachophoresis-Based Surface Immunoassay.

PubMed

Paratore, Federico; Zeidman Kalman, Tal; Rosenfeld, Tally; Kaigala, Govind V; Bercovici, Moran

2017-07-18

In the absence of amplification methods for proteins, the immune-detection of low-abundance proteins using antibodies is fundamentally limited by binding kinetic rates. Here, we present a new class of surface-based immunoassays in which protein-antibody reaction is accelerated by isotachophoresis (ITP). We demonstrate the use of ITP to preconcentrate and deliver target proteins to a surface decorated with specific antibodies, where effective utilization of the focused sample is achieved by modulating the driving electric field (stop-and-diffuse ITP mode) or applying a counter flow that opposes the ITP motion (counterflow ITP mode). Using enhanced green fluorescent protein (EGFP) as a model protein, we carry out an experimental optimization of the ITP-based immunoassay and demonstrate a 1300-fold improvement in limit of detection compared to a standard immunoassay, in a 6 min protein-antibody reaction. We discuss the design of buffer chemistries for other protein systems and, in concert with experiments, provide full analytical solutions for the two operation modes, elucidating the interplay between reaction, diffusion, and accumulation time scales and enabling the prediction and design of future immunoassays.

Diffusion of chaotic field lines in tokamaks

NASA Astrophysics Data System (ADS)

Ali, Halima; Punjabi, Alkesh

2006-10-01

An important instability for the destruction of magnetic surfaces in tokamaks due to island overlapping is the tearing modes. Magnetic fields perturbed by tearing modes are given by the sinusoidal form Br=-1rR∑m,nbm^n ( mθ-n ) . The sinusoidal nature of perturbation creates islands structure near resonant surfaces. In this work, we consider two modes, ( m1,n1 )and ( m2,n2 )that interact with each other, leading to two chains of islands, called primary islands. We use a previously derived Hamiltonian map, the ψ-θ map, with and without higher order control terms to study the diffusion of chaotic field lines. We will present and discuss the results of this work, and discuss its implications with regard to magnetic transport barriers for a fixed q-profile and increasing strength of magnetic perturbations. This work is done under the DOE grant number DE-FG02-01ER54624. 1.A. Punjabi et al, Phys. Rev. lett., 69, 3322 (1992). 2. H. Ali, A. Punjabi, and A. Boozer, Int. J. Comp. Num. Ana. Applications 6, 17 (2005).

Reaction-diffusion systems in natural sciences and new technology transfer

NASA Astrophysics Data System (ADS)

Keller, André A.

2012-12-01

Diffusion mechanisms in natural sciences and innovation management involve partial differential equations (PDEs). This is due to their spatio-temporal dimensions. Functional semi-discretized PDEs (with lattice spatial structures or time delays) may be even more adapted to real world problems. In the modeling process, PDEs can also formalize behaviors, such as the logistic growth of populations with migration, and the adopters’ dynamics of new products in innovation models. In biology, these events are related to variations in the environment, population densities and overcrowding, migration and spreading of humans, animals, plants and other cells and organisms. In chemical reactions, molecules of different species interact locally and diffuse. In the management of new technologies, the diffusion processes of innovations in the marketplace (e.g., the mobile phone) are a major subject. These innovation diffusion models refer mainly to epidemic models. This contribution introduces that modeling process by using PDEs and reviews the essential features of the dynamics and control in biological, chemical and new technology transfer. This paper is essentially user-oriented with basic nonlinear evolution equations, delay PDEs, several analytical and numerical methods for solving, different solutions, and with the use of mathematical packages, notebooks and codes. The computations are carried out by using the software Wolfram Mathematica®7, and C++ codes.

Diffusivities of Redox-Sensitive Elements in Basalt vs. Oxygen Fugacity Determined by LA-ICP-MS

NASA Technical Reports Server (NTRS)

Szumila, Ian; Danielson, Lisa; Trail, Dustin

2017-01-01

Several diffusion experiments were conducted in a piston cylinder device across a range of oxygen fugacities (FMQ-3 FMQ-1.2, FMQ+6) at 1 GPa and 1300 C. This was done to explore the effects of oxygen fugacity (fO2) on diffusivity of redox sensitive trace elements. This allows investigation of how these elements diffuse across the fO2 range encountered in different reservoirs on planets and moons in our solar system. The University of Rochester LA-ICP-MS system was used for analysis of samples. Analyses were conducted using an Agilent 7900 quadrupole mass spectrometer connected to a Photon Machines 193 nm G2 laser ablation (LA) system equipped with a HelEx 2-volume sample chamber. Spots used were 35 micrometers circles spaced at 65 micrometers intervals. Laser fluence was 7.81 J/cm^2 with a rep rate of 10 Hz. The iolite software package was used to reduce data collected from laser ablation analysis of experiments with Si-29 used as the internal standard isotope. Iolite's global fit module was used to simultaneously fit elements' diffusivities in each experiment while keeping the Matano interface constant. Elements analysed include V, Nb, W, Mo, La, Ce, Pr, Sm, Eu, Gd, Ta, and W. Figures

Wide-Field Imaging Telescope-0 (WIT0) with automatic observing system

NASA Astrophysics Data System (ADS)

Ji, Tae-Geun; Byeon, Seoyeon; Lee, Hye-In; Park, Woojin; Lee, Sang-Yun; Hwang, Sungyong; Choi, Changsu; Gibson, Coyne Andrew; Kuehne, John W.; Prochaska, Travis; Marshall, Jennifer L.; Im, Myungshin; Pak, Soojong

2018-01-01

We introduce Wide-Field Imaging Telescope-0 (WIT0), with an automatic observing system. It is developed for monitoring the variabilities of many sources at a time, e.g. young stellar objects and active galactic nuclei. It can also find the locations of transient sources such as a supernova or gamma-ray bursts. In 2017 February, we installed the wide-field 10-inch telescope (Takahashi CCA-250) as a piggyback system on the 30-inch telescope at the McDonald Observatory in Texas, US. The 10-inch telescope has a 2.35 × 2.35 deg field-of-view with a 4k × 4k CCD Camera (FLI ML16803). To improve the observational efficiency of the system, we developed a new automatic observing software, KAOS30 (KHU Automatic Observing Software for McDonald 30-inch telescope), which was developed by Visual C++ on the basis of a windows operating system. The software consists of four control packages: the Telescope Control Package (TCP), the Data Acquisition Package (DAP), the Auto Focus Package (AFP), and the Script Mode Package (SMP). Since it also supports the instruments that are using the ASCOM driver, the additional hardware installations become quite simplified. We commissioned KAOS30 in 2017 August and are in the process of testing. Based on the WIT0 experiences, we will extend KAOS30 to control multiple telescopes in future projects.

Probabilistic migration modelling focused on functional barrier efficiency and low migration concepts in support of risk assessment.

PubMed

Brandsch, Rainer

2017-10-01

Migration modelling provides reliable migration estimates from food-contact materials (FCM) to food or food simulants based on mass-transfer parameters like diffusion and partition coefficients related to individual materials. In most cases, mass-transfer parameters are not readily available from the literature and for this reason are estimated with a given uncertainty. Historically, uncertainty was accounted for by introducing upper limit concepts first, turning out to be of limited applicability due to highly overestimated migration results. Probabilistic migration modelling gives the possibility to consider uncertainty of the mass-transfer parameters as well as other model inputs. With respect to a functional barrier, the most important parameters among others are the diffusion properties of the functional barrier and its thickness. A software tool that accepts distribution as inputs and is capable of applying Monte Carlo methods, i.e., random sampling from the input distributions of the relevant parameters (i.e., diffusion coefficient and layer thickness), predicts migration results with related uncertainty and confidence intervals. The capabilities of probabilistic migration modelling are presented in the view of three case studies (1) sensitivity analysis, (2) functional barrier efficiency and (3) validation by experimental testing. Based on the predicted migration by probabilistic migration modelling and related exposure estimates, safety evaluation of new materials in the context of existing or new packaging concepts is possible. Identifying associated migration risk and potential safety concerns in the early stage of packaging development is possible. Furthermore, dedicated material selection exhibiting required functional barrier efficiency under application conditions becomes feasible. Validation of the migration risk assessment by probabilistic migration modelling through a minimum of dedicated experimental testing is strongly recommended.

Acrosome reaction inducers impose alterations in repulsive strain and hydration barrier in human sperm membranes.

PubMed

Purohit, S B; Laloraya, M; Kumar, G P

1998-06-01

Spin labeling studies of the lipophilic domains of human spermatozoa during capacitation and during acrosome reaction (AR) under the influence of selected AR-inducers were performed. Significantly enhanced rotational function of molecules was obvious during capacitation, with no significant changes in membrane packaging or the lateral diffusion of molecules. The AR inducers appeared to restrict the rotational freedom of molecules, dramatically enhancing the lateral diffusion and ordering coefficients. A significant decrease in superoxide anion generation was observed in the acrosome reacted groups when compared to the non-acrosome reacted groups. A high level of superoxide anion radical (O2.-) level maintained in capacitated spermatozoa would add to the Van der Waal's repulsive forces at the polar head of phospholipids, holding the membrane in strain where the molecular enjoy little freedom for lateral motion. A sudden drop in the levels of O2.- in spermatozoa upon addition of AR inducers could abruptly release the local hydrophobic repulsive strain within the membrane. This loss of hydration barrier explains the observed enhancement in lateral diffusion profiles of lipids and the packaging of molecules. It is reasonable to assume that these phenomena could be amplified further by interplay of Ca2+ by modifying the local charge aggregation. Thus, we would conclude that AR inducers release the oxyradical load in capacitated spermatozoa, which would modify the repulsive strain and hydration barrier forces in the lipophilic domains permitting vesiculation of the membranes. It appears that various acrosome reaction inducers act as effectors of grossly similar physical alterations in sperm membranes and that the resulting signal cascades proceed through intercalating biochemical sequences.

Hetero-cellular prototyping by synchronized multi-material bioprinting for rotary cell culture system.

PubMed

Snyder, Jessica; Son, Ae Rin; Hamid, Qudus; Wu, Honglu; Sun, Wei

2016-01-13

Bottom-up tissue engineering requires methodological progress of biofabrication to capture key design facets of anatomical arrangements across micro, meso and macro-scales. The diffusive mass transfer properties necessary to elicit stability and functionality require hetero-typic contact, cell-to-cell signaling and uniform nutrient diffusion. Bioprinting techniques successfully build mathematically defined porous architecture to diminish resistance to mass transfer. Current limitations of bioprinted cell assemblies include poor micro-scale formability of cell-laden soft gels and asymmetrical macro-scale diffusion through 3D volumes. The objective of this work is to engineer a synchronized multi-material bioprinter (SMMB) system which improves the resolution and expands the capability of existing bioprinting systems by packaging multiple cell types in heterotypic arrays prior to deposition. This unit cell approach to arranging multiple cell-laden solutions is integrated with a motion system to print heterogeneous filaments as tissue engineered scaffolds and nanoliter droplets. The set of SMMB process parameters control the geometric arrangement of the combined flow's internal features and constituent material's volume fractions. SMMB printed hepatocyte-endothelial laden 200 nl droplets are cultured in a rotary cell culture system (RCCS) to study the effect of microgravity on an in vitro model of the human hepatic lobule. RCCS conditioning for 48 h increased hepatocyte cytoplasm diameter 2 μm, increased metabolic rate, and decreased drug half-life. SMMB hetero-cellular models present a 10-fold increase in metabolic rate, compared to SMMB mono-culture models. Improved bioprinting resolution due to process control of cell-laden matrix packaging as well as nanoliter droplet printing capability identify SMMB as a viable technique to improve in vitro model efficacy.

CSAM Metrology Software Tool

NASA Technical Reports Server (NTRS)

Vu, Duc; Sandor, Michael; Agarwal, Shri

2005-01-01

CSAM Metrology Software Tool (CMeST) is a computer program for analysis of false-color CSAM images of plastic-encapsulated microcircuits. (CSAM signifies C-mode scanning acoustic microscopy.) The colors in the images indicate areas of delamination within the plastic packages. Heretofore, the images have been interpreted by human examiners. Hence, interpretations have not been entirely consistent and objective. CMeST processes the color information in image-data files to detect areas of delamination without incurring inconsistencies of subjective judgement. CMeST can be used to create a database of baseline images of packages acquired at given times for comparison with images of the same packages acquired at later times. Any area within an image can be selected for analysis, which can include examination of different delamination types by location. CMeST can also be used to perform statistical analyses of image data. Results of analyses are available in a spreadsheet format for further processing. The results can be exported to any data-base-processing software.

Selecting and implementing the PBS scheduler on an SGI Onyx 2/Orgin 2000.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bittner, S.

1999-06-28

In the Mathematics and Computer Science Division at Argonne, the demand for resources on the Onyx 2 exceeds the resources available for consumption. To distribute these scarce resources effectively, we need a scheduling and resource management package with multiple capabilities. In particular, it must accept standard interactive user logins, allow batch jobs, backfill the system based on available resources, and permit system activities such as accounting to proceed without interruption. The package must include a mechanism to treat the graphic pipes as a schedulable resource. Also required is the ability to create advance reservations, offer dedicated system modes for largemore » resource runs and benchmarking, and track the resources consumed for each job run. Furthermore, our users want to be able to obtain repeatable timing results on job runs. And, of course, package costs must be carefully considered. We explored several options, including NQE and various third-party products, before settling on the PBS scheduler.« less

IBS: an illustrator for the presentation and visualization of biological sequences.

PubMed

Liu, Wenzhong; Xie, Yubin; Ma, Jiyong; Luo, Xiaotong; Nie, Peng; Zuo, Zhixiang; Lahrmann, Urs; Zhao, Qi; Zheng, Yueyuan; Zhao, Yong; Xue, Yu; Ren, Jian

2015-10-15

Biological sequence diagrams are fundamental for visualizing various functional elements in protein or nucleotide sequences that enable a summarization and presentation of existing information as well as means of intuitive new discoveries. Here, we present a software package called illustrator of biological sequences (IBS) that can be used for representing the organization of either protein or nucleotide sequences in a convenient, efficient and precise manner. Multiple options are provided in IBS, and biological sequences can be manipulated, recolored or rescaled in a user-defined mode. Also, the final representational artwork can be directly exported into a publication-quality figure. The standalone package of IBS was implemented in JAVA, while the online service was implemented in HTML5 and JavaScript. Both the standalone package and online service are freely available at http://ibs.biocuckoo.org. renjian.sysu@gmail.com or xueyu@hust.edu.cn Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press.

Micro-machined resonator oscillator

DOEpatents

Koehler, Dale R.; Sniegowski, Jeffry J.; Bivens, Hugh M.; Wessendorf, Kurt O.

1994-01-01

A micro-miniature resonator-oscillator is disclosed. Due to the miniaturization of the resonator-oscillator, oscillation frequencies of one MHz and higher are utilized. A thickness-mode quartz resonator housed in a micro-machined silicon package and operated as a "telemetered sensor beacon" that is, a digital, self-powered, remote, parameter measuring-transmitter in the FM-band. The resonator design uses trapped energy principles and temperature dependence methodology through crystal orientation control, with operation in the 20-100 MHz range. High volume batch-processing manufacturing is utilized, with package and resonator assembly at the wafer level. Unique design features include squeeze-film damping for robust vibration and shock performance, capacitive coupling through micro-machined diaphragms allowing resonator excitation at the package exterior, circuit integration and extremely small (0.1 in. square) dimensioning. A family of micro-miniature sensor beacons is also disclosed with widespread applications as bio-medical sensors, vehicle status monitors and high-volume animal identification and health sensors. The sensor family allows measurement of temperatures, chemicals, acceleration and pressure. A microphone and clock realization is also available.

IBS: an illustrator for the presentation and visualization of biological sequences

PubMed Central

Liu, Wenzhong; Xie, Yubin; Ma, Jiyong; Luo, Xiaotong; Nie, Peng; Zuo, Zhixiang; Lahrmann, Urs; Zhao, Qi; Zheng, Yueyuan; Zhao, Yong; Xue, Yu; Ren, Jian

2015-01-01

Summary: Biological sequence diagrams are fundamental for visualizing various functional elements in protein or nucleotide sequences that enable a summarization and presentation of existing information as well as means of intuitive new discoveries. Here, we present a software package called illustrator of biological sequences (IBS) that can be used for representing the organization of either protein or nucleotide sequences in a convenient, efficient and precise manner. Multiple options are provided in IBS, and biological sequences can be manipulated, recolored or rescaled in a user-defined mode. Also, the final representational artwork can be directly exported into a publication-quality figure. Availability and implementation: The standalone package of IBS was implemented in JAVA, while the online service was implemented in HTML5 and JavaScript. Both the standalone package and online service are freely available at http://ibs.biocuckoo.org. Contact: renjian.sysu@gmail.com or xueyu@hust.edu.cn Supplementary information: Supplementary data are available at Bioinformatics online. PMID:26069263

High temperature sensing using higher-order-mode rejected sapphire-crystal fiber gratings

NASA Astrophysics Data System (ADS)

Zhan, Chun; Kim, Jae Hun; Lee, Jon; Yin, Stuart; Ruffin, Paul; Luo, Claire

2007-09-01

In this paper, we report the fabrication of higher-order-mode rejected fiber Bragg gratings (FBGs) in sapphire crystal fiber using infrared (IR) femtosecond laser illumination. The grating is tested in high temperature furnace up to 1600 degree Celsius. As sapphire fiber is only available as highly multimode fiber, a scheme to filter out higher order modes in favor for the fundamental mode is theoretically evaluated and experimentally demonstrated. The approach is to use an ultra thin sapphire crystal fiber (60 micron in diameter) to decrease the number of modes. The small diameter fiber also enables bending the fiber to certain radius which is carefully chosen to provide low loss for the fundamental mode LP01 and high loss for the other high-order modes. After bending, less-than-2-nm resonant peak bandwidth is achieved. The grating spectrum is improved, and higher resolution sensing measurement can be achieved. This mode filtering method is very easy to implement. Furthermore, the sapphire fiber is sealed with hi-purity alumina ceramic cement inside a flexible high temperature titanium tube, and the highly flexible titanium tube offers a robust packaging to sapphire fiber. Our high temperature sapphire grating sensor is very promising in extremely high temperature sensing application.

Effect of vortex inlet mode on low-power cylindrical Hall thruster

NASA Astrophysics Data System (ADS)

Ding, Yongjie; Jia, Boyang; Xu, Yu; Wei, Liqiu; Su, Hongbo; Li, Peng; Sun, Hezhi; Peng, Wuji; Cao, Yong; Yu, Daren

2017-08-01

This paper examines a new propellant inlet mode for a low-power cylindrical Hall thruster called the vortex inlet mode. This new mode makes propellant gas diffuse in the form of a circumferential vortex in the discharge channel of the thruster. Simulation and experimental results show that the neutral gas density in the discharge channel increases upon the application of the vortex inlet mode, effectively extending the dwell time of the propellant gas in the channel. According to the experimental results, the vortex inlet increases the propellant utilization of the thruster by 3.12%-8.81%, thrust by 1.1%-53.5%, specific impulse by 1.1%-53.5%, thrust-to-power ratio by 10%-63%, and anode efficiency by 1.6%-7.3%, greatly improving the thruster performance.

Development and fabrication of a high current, fast recovery power diode

NASA Technical Reports Server (NTRS)

Berman, A. H.; Balodis, V.; Devance, D. C.; Gaugh, C. E.; Karlsson, E. A.

1983-01-01

A high voltage (VR = 1200 V), high current (IF = 150 A), fast recovery ( 700 ns) and low forward voltage drop ( 1.5 V) silicon rectifier was designed and the process developed for its fabrication. For maximum purity, uniformity and material characteristic stability, neutron transmutation n-type doped float zone silicon is used. The design features a hexagonal chip for maximum area utilization of space available in the DO-8 diode package, PIN diffused junction structure with deep diffused D(+) anode and a shallow high concentration n(+) cathode. With the high temperature glass passivated positive bevel mesa junction termination, the achieved blocking voltage is close to the theoretical limit of the starting material. Gold diffusion is used to control the lifetime and the resulting effect on switching speed and forward voltage tradeoff. For solder reflow assembly, trimetal (Al-Ti-Ni) contacts are used. The required major device electrical characteristics were achieved. Due to the tradeoff nature of forward voltage drop and reverse recovery time, a compromise was reached for these values.

Formation of alternating interfacial layers in Au-12Ge/Ni joints

PubMed Central

Lin, Shih-kang; Tsai, Ming-yueh; Tsai, Ping-chun; Hsu, Bo-hsun

2014-01-01

Au-Ge alloys are promising materials for high-power and high-frequency packaging, and Ni is frequently used as diffusion barriers. This study investigates interfacial reactions in Au-12Ge/Ni joints at 300°C and 400°C. For the reactions at 300°C, typical interfacial morphology was observed and the diffusion path was (Au) + (Ge)/NiGe/Ni5Ge3/Ni. However, an interesting phenomenon – the formation of (Au,Ni,Ge)/NiGe alternating layers – was observed for the reactions at 400°C. The diffusion path across the interface was liquid/(Au,Ni,Ge)/NiGe/···/(Au,Ni,Ge)/NiGe/Ni2Ge/Ni. The periodic thermodynamic instability at the NiGe/Ni2Ge interface caused the subsequent nucleation of new (Au,Ni,Ge)/NiGe pairs. The thermodynamic foundation and mechanism of formation of the alternating layers are elaborated in this paper. PMID:24690992

Elementary reaction modeling of reversible CO/CO2 electrochemical conversion on patterned nickel electrodes

NASA Astrophysics Data System (ADS)

Luo, Yu; Shi, Yixiang; Li, Wenying; Cai, Ningsheng

2018-03-01

CO/CO2 are the major gas reactant/product in the fuel electrode of reversible solid oxide cells (RSOC). This study proposes a two-charge-transfer-step mechanism to describe the reaction and transfer processes of CO-CO2 electrochemical conversion on a patterned Ni electrode of RSOC. An elementary reaction model is developed to couple two charge transfer reactions, C(Ni)+O2-(YSZ) ↔ CO(Ni)+(YSZ) +2e- and CO(Ni)+O2-(YSZ) ↔ CO2(Ni)+(YSZ)+2e-, with adsorption/desorption, surface chemical reactions and surface diffusion. This model well validates in both solid oxide electrolysis cell (SOEC) and solid oxide fuel cell (SOFC) modes by the experimental data from a patterned Ni electrode with 10 μm stripe width at different pCO (0-0.25 atm), pCO2 (0-0.35 atm) and operating temperature (600-700 °C). This model indicates SOEC mode is dominated by charge transfer step C(Ni)+O2-(YSZ)↔CO(Ni)+(YSZ) +2e-, while SOFC mode by CO(Ni)+ O2-(YSZ)↔CO2(Ni)+(YSZ)+2e- on the patterned Ni electrode. The sensitivity analysis shows charge transfer step is the major rate-determining step for RSOC, besides, surface diffusion of CO and CO2 as well as CO2 adsorption also plays a significant role in the electrochemical reaction of SOEC while surface diffusion of CO and CO2 desorption could be co-limiting in SOFC.

Molecular Dynamics Simulation of Salt Diffusion in Polyelectrolyte Assemblies.

PubMed

Zhang, Ran; Duan, Xiaozheng; Ding, Mingming; Shi, Tongfei

2018-06-05

The diffusion of salt ions and charged probe molecules in polyelectrolyte assemblies is often assumed to follow a theoretical hopping model, in which the diffusing ion is hopping between charged sites of chains based on electroneutrality. However, experimental verification of diffusing pathway at such microscales is difficult, and the corresponding molecular mechanisms remain elusive. In this study, we perform all-atom molecular dynamics (MD) simulations of salt diffusion in polyelectrolyte (PE) assembly of poly (sodium 4-styrenesulfonate) (PSS) and poly (diallyldimethylammonium chloride) (PDAC). Besides the ion hopping mode, the diffusing trajectories are found presenting common features of a jump process, i.e., subjecting to PE relaxation, water pockets in the structure open and close, thus the ion can move from one pocket to another. Anomalous subdiffusion of ions and water is observed due to the trapping scenarios in these water pockets. The jump events are much rarer compared with ion hopping but significantly increases salt diffusion with increasing temperature. Our result strongly indicates that salt diffusion in hydrated PDAC/PSS is a combined process of ion hopping and jump motion. This provides new molecular explanation for the coupling of salt motion with chain motion and the nonlinear increase of salt diffusion at glass transition temperature.

Potential surfaces for O atom-polymer reactions

NASA Technical Reports Server (NTRS)

Laskowski, B. C.; Jaffe, R. L.

1987-01-01

Ab initio quantum chemistry methods are used to study the energetics of interactions of O atoms with organic compounds. Polyethylene (CH2)n has been chosen as the model system to study the interactions of O(3P) and O(1D) atoms with polymers. In particular, H abstraction is investigated and polyethylene is represented by a C3 (propane) oligomeric model. The gradient method, as implemented in the GRADSCF package of programs, is used to determine the geometries and energies of products and reactants. The saddle point, barrier geometry is determined by minimizing the squares of the gradients of the potential with respect to the internal coordinates. To correctly describe the change in bonding during the reaction at least a two configuration MCSCF (multiconfiguration self consistent field) or GVB (generalized valence bond) wave function has to be used. Basis sets include standard Pople and Dunning sets, however, increased with polarization functions and diffuse p functions on both the C and O atoms. The latter is important due to the O(-) character of the wave function at the saddle point and products. Normal modes and vibrational energy levels are given for the reactants, saddle points and products. Finally, quantitative energetics are obtained by implementing a small CAS (complete active space) approach followed by limited configuration interaction (CI) calculations. Comparisons are made with available experimental data.

The surface roughness effect on the performance of supersonic ejectors

NASA Astrophysics Data System (ADS)

Brezgin, D. V.; Aronson, K. E.; Mazzelli, F.; Milazzo, A.

2017-07-01

The paper presents the numerical simulation results of the surface roughness influence on gas-dynamic processes inside flow parts of a supersonic ejector. These simulations are performed using two commercial CFD solvers (Star- CCM+ and Fluent). The results are compared to each other and verified by a full-scale experiment in terms of global flow parameters (the entrainment ratio: the ratio between secondary to primary mass flow rate - ER hereafter) and local flow parameters distribution (the static pressure distribution along the mixing chamber and diffuser walls). A detailed comparative study of the employed methods and approaches in both CFD packages is carried out in order to estimate the roughness effect on the logarithmic law velocity distribution inside the boundary layer. Influence of the surface roughness is compared with the influence of the backpressure (static pressure at the ejector outlet). It has been found out that increasing either the ejector backpressure or the surface roughness height, the shock position displaces upstream. Moreover, the numerical simulation results of an ejector with rough walls in the both CFD solvers are well quantitatively agreed with each other in terms of the mean ER and well qualitatively agree in terms of the local flow parameters distribution. It is found out that in the case of exceeding the "critical roughness height" for the given boundary conditions and ejector's geometry, the ejector switches to the "off-design" mode and its performance decreases considerably.

Long-Term INP Measurements within the BACCHUS project

NASA Astrophysics Data System (ADS)

Schrod, Jann; Bingemer, Heinz; Curtius, Joachim

2016-04-01

The European research project BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding) studies the interactions between aerosols, clouds and the climate system, and tries to reconstruct pre-industrial aerosol and cloud conditions from data collected in pristine environments. The number concentration of Ice Nucleating Particles (INP) is an important, yet scarcely known parameter. As a partner of Work package 1 of BACCHUS we began in September 2014 to operate a globally spanned network of four INP sampling stations, which is the first of its kind. The stations are located at the ATTO observatory in the Brazilian Rainforest, the Caribbean Sea (Martinique), the Zeppelin Observatory at Svalbard in the Arctic, and in central Europe (Germany). Samples are collected routinely every day or every few days by electrostatic precipitation of aerosol particles onto Si substrates. The samples are stored in petri-slides, and shipped to our laboratory in Frankfurt, Germany. The number of ice nucleating particles on the substrate is analyzed in the isothermal static diffusion chamber FRIDGE by growing ice on the INP and photographing and counting the crystals. The measurements in the temperature range from -20°C to -30°C and relative humidities of 100-135% (with respect to ice) address primarily the deposition/condensation nucleation modes. Here we present INP and supporting aerosol data from this novel INP network for the first time.

Electric-field noise from carbon-adatom diffusion on a Au(110) surface: First-principles calculations and experiments

DOE PAGES

Kim, E.; Safavi-Naini, A.; Hite, D. A.; ...

2017-03-01

The decoherence of trapped-ion quantum bits due to heating of their motional modes is a fundamental science and engineering problem. This heating is attributed to electric-field noise arising from processes on the trap-electrode surfaces. In this work, we address the source of this noise by focusing on the diffusion of carbon-containing adsorbates on the surface of Au(110). We show by detailed scanned probe microscopy and density functional theory how the carbon adatom diffusion on the gold surface changes the energy landscape, and how the adatom dipole moment varies with the diffusive motion. Lastly, a simple model for the diffusion noise,more » which varies quadratically with the variation of the dipole moment, qualitatively reproduces the measured noise spectrum, and the estimate of the noise spectral density is in accord with measured values.« less

Combustion diagnostic for active engine feedback control

DOEpatents

Green, Jr., Johney Boyd; Daw, Charles Stuart; Wagner, Robert Milton

2007-10-02

This invention detects the crank angle location where combustion switches from premixed to diffusion, referred to as the transition index, and uses that location to define integration limits that measure the portions of heat released during the combustion process that occur during the premixed and diffusion phases. Those integrated premixed and diffusion values are used to develop a metric referred to as the combustion index. The combustion index is defined as the integrated diffusion contribution divided by the integrated premixed contribution. As the EGR rate is increased enough to enter the low temperature combustion regime, PM emissions decrease because more of the combustion process is occurring over the premixed portion of the heat release rate profile and the diffusion portion has been significantly reduced. This information is used to detect when the engine is or is not operating in a low temperature combustion mode and provides that feedback to an engine control algorithm.

Electric-field noise from carbon-adatom diffusion on a Au(110) surface: First-principles calculations and experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, E.; Safavi-Naini, A.; Hite, D. A.

The decoherence of trapped-ion quantum bits due to heating of their motional modes is a fundamental science and engineering problem. This heating is attributed to electric-field noise arising from processes on the trap-electrode surfaces. In this work, we address the source of this noise by focusing on the diffusion of carbon-containing adsorbates on the surface of Au(110). We show by detailed scanned probe microscopy and density functional theory how the carbon adatom diffusion on the gold surface changes the energy landscape, and how the adatom dipole moment varies with the diffusive motion. Lastly, a simple model for the diffusion noise,more » which varies quadratically with the variation of the dipole moment, qualitatively reproduces the measured noise spectrum, and the estimate of the noise spectral density is in accord with measured values.« less

Enhanced Atom Mobility on the Surface of a Metastable Film

NASA Astrophysics Data System (ADS)

Picone, A.; Riva, M.; Fratesi, G.; Brambilla, A.; Bussetti, G.; Finazzi, M.; Duò, L.; Ciccacci, F.

2014-07-01

A remarkable enhancement of atomic diffusion is highlighted by scanning tunneling microscopy performed on ultrathin metastable body-centered tetragonal Co films grown on Fe(001). The films follow a nearly perfect layer-by-layer growth mode with a saturation island density strongly dependent on the layer on which the nucleation occurs, indicating a lowering of the diffusion barrier. Density functional theory calculations reveal that this phenomenon is driven by the increasing capability of the film to accommodate large deformations as the thickness approaches the limit at which a structural transition occurs. These results disclose the possibility of tuning surface diffusion dynamics and controlling cluster nucleation and self-organization.

Enhanced atom mobility on the surface of a metastable film.

PubMed

Picone, A; Riva, M; Fratesi, G; Brambilla, A; Bussetti, G; Finazzi, M; Duò, L; Ciccacci, F

2014-07-25

A remarkable enhancement of atomic diffusion is highlighted by scanning tunneling microscopy performed on ultrathin metastable body-centered tetragonal Co films grown on Fe(001). The films follow a nearly perfect layer-by-layer growth mode with a saturation island density strongly dependent on the layer on which the nucleation occurs, indicating a lowering of the diffusion barrier. Density functional theory calculations reveal that this phenomenon is driven by the increasing capability of the film to accommodate large deformations as the thickness approaches the limit at which a structural transition occurs. These results disclose the possibility of tuning surface diffusion dynamics and controlling cluster nucleation and self-organization.

Sequential Sampling Models in Cognitive Neuroscience: Advantages, Applications, and Extensions.

PubMed

Forstmann, B U; Ratcliff, R; Wagenmakers, E-J

2016-01-01

Sequential sampling models assume that people make speeded decisions by gradually accumulating noisy information until a threshold of evidence is reached. In cognitive science, one such model--the diffusion decision model--is now regularly used to decompose task performance into underlying processes such as the quality of information processing, response caution, and a priori bias. In the cognitive neurosciences, the diffusion decision model has recently been adopted as a quantitative tool to study the neural basis of decision making under time pressure. We present a selective overview of several recent applications and extensions of the diffusion decision model in the cognitive neurosciences.

Brownian Motion of Boomerang Colloidal Particles

NASA Astrophysics Data System (ADS)

Wei, Qi-Huo; Konya, Andrew; Wang, Feng; Selinger, Jonathan V.; Sun, Kai; Chakrabarty, Ayan

2014-03-01

We present experimental and theoretical studies on the Brownian motion of boomerang colloidal particles confined between two glass plates. Our experimental observations show that the mean displacements are biased towards the center of hydrodynamic stress (CoH), and that the mean-square displacements exhibit a crossover from short-time faster to long-time slower diffusion with the short-time diffusion coefficients dependent on the points used for tracking. A model based on Langevin theory elucidates that these behaviors are ascribed to the superposition of two diffusive modes: the ellipsoidal motion of the CoH and the rotational motion of the tracking point with respect to the CoH.