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Sample records for electromagnetic filamentary structures

  1. Electromagnetic effects on dynamics of high-beta filamentary structures

    SciTech Connect

    Lee, Wonjae; Krasheninnikov, Sergei I.; Umansky, Maxim V.; Angus, J. R.

    2015-01-15

    The impacts of the electromagnetic effects on blob dynamics are considered. Electromagnetic BOUT++ simulations on seeded high-beta blobs demonstrate that inhomogeneity of magnetic curvature or plasma pressure along the filament leads to bending of the blob filaments and the magnetic field lines due to increased propagation time of plasma current (Alfvén time). The bending motion can enhance heat exchange between the plasma facing materials and the inner scrape-off layer (SOL) region. The effects of sheath boundary conditions on the part of the blob away from the boundary are also diminished by the increased Alfvén time. Using linear analysis and BOUT++ simulations, it is found that electromagnetic effects in high temperature and high density plasmas reduce the growth rate of resistive drift wave instability when resistivity drops below a certain value. The blobs temperature decreases in the course of its motion through the SOL and so the blob can switch from the electromagnetic to the electrostatic regime where resistive drift waves become important again.

  2. Electromagnetic effects on dynamics of high-beta filamentary structures

    SciTech Connect

    Lee, Wonjae; Umansky, Maxim V.; Angus, J. R.; Krasheninnikov, Sergei I.

    2015-01-12

    The impacts of the electromagnetic effects on blob dynamics are considered. Electromagnetic BOUT++ simulations on seeded high-beta blobs demonstrate that inhomogeneity of magnetic curvature or plasma pressure along the filament leads to bending of the blob filaments and the magnetic field lines due to increased propagation time of plasma current (Alfvén time). The bending motion can enhance heat exchange between the plasma facing materials and the inner SOL region. The effects of sheath boundary conditions on the part of the blob away from the boundary are also diminished by the increased Alfvén time. Using linear analysis and the BOUT++ simulation, it is found that electromagnetic effects in high temperature and high density plasmas reduce the growth rate of resistive drift wave turbulence when resistivity drops below some certain value. Lastly, in the course of blobs motion in the SOL its temperature is reduced, which leads to enhancement of resistive effects, so the blob can switch from electromagnetic to electrostatic regime, where resistive drift wave turbulence become important.

  3. Electromagnetic effects on dynamics of high-beta filamentary structures

    DOE PAGESBeta

    Lee, Wonjae; Umansky, Maxim V.; Angus, J. R.; Krasheninnikov, Sergei I.

    2015-01-12

    The impacts of the electromagnetic effects on blob dynamics are considered. Electromagnetic BOUT++ simulations on seeded high-beta blobs demonstrate that inhomogeneity of magnetic curvature or plasma pressure along the filament leads to bending of the blob filaments and the magnetic field lines due to increased propagation time of plasma current (Alfvén time). The bending motion can enhance heat exchange between the plasma facing materials and the inner SOL region. The effects of sheath boundary conditions on the part of the blob away from the boundary are also diminished by the increased Alfvén time. Using linear analysis and the BOUT++ simulation,more » it is found that electromagnetic effects in high temperature and high density plasmas reduce the growth rate of resistive drift wave turbulence when resistivity drops below some certain value. Lastly, in the course of blobs motion in the SOL its temperature is reduced, which leads to enhancement of resistive effects, so the blob can switch from electromagnetic to electrostatic regime, where resistive drift wave turbulence become important.« less

  4. Magnetosheath Filamentary Structures

    NASA Astrophysics Data System (ADS)

    Rojas-Castillo, D. I.; Blanco-Cano, X.; Omidi, N.; Kajdic, P.

    2014-12-01

    The terrestrial magnetosheath is full of highly perturbed plasma. The inhomogeneity of this region leads to temperature anisotropies that can originate waves; e.g, mirror mode and ion cyclotron waves. Other structures like the magnetosheath filamentary structures (MFS) can also be present. These are structures reported from results of global hybrid simulations by Omidi et al. (2014) that are formed in the quasi-parallel region of the bow shock and they are convected into the magnetosheath. The MFS are characterized by field aligned enhancements of density and temperature that are anti-correlated. In this work we analyze magnetic field and plasma data from the THEMIS mission to explore the possible existence of MFS.

  5. The filamentary structure in sunspots

    NASA Astrophysics Data System (ADS)

    Hu, Y.-Q.

    1984-03-01

    An analytical model of the filamentary structure of sunspots is developed within the framework of magnetostatic-equilibrium theory and a small-perturbation assumption, neglecting convective motion and considering dynamic equilibrium only. Following the method of Hu et al. (1983), zeroeth and first order solutions of the nonaxisymmetric equilibrium equations are obtained, corresponding to the overall structure of the sunspot and to its filamentary structures. The dark filaments of the penumbral region are shown to be related to stronger magnetic fields, as observed by Beckers and Schroeter (1968).

  6. Method and apparatus for synthesizing filamentary structures

    DOEpatents

    Height, Murray J.; Howard, Jack B.; Vandersande, John B.

    2008-02-26

    Method and apparatus for producing filamentary structures. The structures include single-walled nanotubes. The method includes combusting hydrocarbon fuel and oxygen to establish a non-sooting flame and providing an unsupported catalyst to synthesize the filamentary structure in a post-flame region of the flame. Residence time is selected to favor filamentary structure growth.

  7. New optical filamentary structures in Pegasus

    NASA Astrophysics Data System (ADS)

    Boumis, P.; Mavromatakis, F.; Paleologou, E. V.; Becker, W.

    2002-12-01

    Deep Hα N II CCD images have been obtained in the area of the Pegasus Constellation. The resulting mosaic covers an extent of ~ 7.5 deg × 7.5 and filamentary and diffuse emission was discovered. Several long filaments (up to ~ 1 deg ) are found within the field, while diffuse emission is present mainly in the central and northern areas. The filaments show variations in intensity along their extent suggesting inhomogeneous interstellar clouds. Faint soft X-ray emission was also detected in the ROSAT All-Sky Survey. It is mainly concentrated in the central areas of our field and overlaps the optical emission. The low ionization images of [S II] of selected areas mainly show faint diffuse emission, while in the medium ionization images of [O III] diffuse and faint filamentary structures are present. Spectrophotometric observations were performed on the brightest filaments and indicate emission from photoionized or shock-heated gas. The sulfur line ratios indicate electron densities below ~ 600 cm-3, while the absolute Hα emission lies in the range of 1.1 - 8.8 × 10-17 erg s-1 cm-2 arcsec-2. The detected optical line emission could be part of a single or multiple supernova explosions.

  8. Filamentary structure in the Orion molecular cloud

    NASA Astrophysics Data System (ADS)

    Bally, John; Langer, William D.; Stark, Antony A.; Wilson, Robert W.

    1987-01-01

    A large-scale (C-13)O map (containing 33,000 spectra on a 1-arcmin grid) is presented for the giant molecular cloud located in the southern part of Ori which contains the Ori Nebula, NGC 1977, and the L1641 dark cloud complex. The overall structure of the cloud is filamentary, with individual features having a length up to 40 times their width. The northern portion of the cloud is compressed, dynamically relaxed, and supports massive star formation. In contrast, the southern part of the Ori A cloud is diffuse, exhibits chaotic spatial and velocity structure, and supports only intermediate- to low-mass star formation. This morphology may be the consequence of the formation and evolution of the Ori OB I association centered north of the molecular cloud. The entire cloud, in addition to the 5000-solar-mass filament containing both OMC-1 and OMC-2, exhibits a north-south velocity gradient. Implications of the observed cloud morphology for theories of molecular cloud evolution are discussed.

  9. Filamentary structure in the Orion molecular cloud

    SciTech Connect

    Bally, J.; Stark, A.A.; Wilson, R.W.; Langer, W.D.

    1987-01-01

    A large-scale (C-13)O map (containing 33,000 spectra on a 1-arcmin grid) is presented for the giant molecular cloud located in the southern part of Ori which contains the Ori Nebula, NGC 1977, and the L1641 dark cloud complex. The overall structure of the cloud is filamentary, with individual features having a length up to 40 times their width. The northern portion of the cloud is compressed, dynamically relaxed, and supports massive star formation. In contrast, the southern part of the Ori A cloud is diffuse, exhibits chaotic spatial and velocity structure, and supports only intermediate- to low-mass star formation. This morphology may be the consequence of the formation and evolution of the Ori OB I association centered north of the molecular cloud. The entire cloud, in addition to the 5000-solar-mass filament containing both OMC-1 and OMC-2, exhibits a north-south velocity gradient. Implications of the observed cloud morphology for theories of molecular cloud evolution are discussed. 14 references.

  10. Filamentary structure in the Orion molecular cloud

    NASA Astrophysics Data System (ADS)

    Bally, J.; Dragovan, M.; Langer, W. D.; Stark, A. A.; Wilson, R. W.

    1986-10-01

    A large scale 13CO map (containing 33,000 spectra) of the giant molecular cloud located in the southern part of Orion is presented which contains the Orion Nebula, NGC1977, and the LI641 dark cloud complex. The overall structure of the cloud is filamentary, with individual features having a length up to 40 times their width. This morphology may result from the effects of star formation in the region or embedded magnetic fields in the cloud. We suggest a simple picture for the evolution of the Orion-A cloud and the formation of the major filament. A rotating proto-cloud (counter rotating with respect to the galaxy) contians a b-field aligned with the galaxtic plane. The northern portion of this cloud collapsed first, perhaps triggered by the pressure of the Ori I OB association. The magnetic field combined with the anisotropic pressure produced by the OB-association breaks the symmetry of the pancake instability, a filament rather than a disc is produced. The growth of instabilities in the filament formed sub-condensations which are recent sites of star formation.

  11. Filamentary structure in the Orion molecular cloud

    NASA Technical Reports Server (NTRS)

    Bally, J.; Langer, W. D.; Bally, J.; Langer, W. D.; Bally, J.; Langer, W. D.

    1986-01-01

    A large scale 13CO map (containing 33,000 spectra) of the giant molecular cloud located in the southern part of Orion is presented which contains the Orion Nebula, NGC1977, and the LI641 dark cloud complex. The overall structure of the cloud is filamentary, with individual features having a length up to 40 times their width. This morphology may result from the effects of star formation in the region or embedded magnetic fields in the cloud. We suggest a simple picture for the evolution of the Orion-A cloud and the formation of the major filament. A rotating proto-cloud (counter rotating with respect to the galaxy) contians a b-field aligned with the galaxtic plane. The northern protion of this cloud collapsed first, perhaps triggered by the pressure of the Ori I OB association. The magnetic field combined with the anisotropic pressure produced by the OB-association breaks the symmetry of the pancake instability, a filament rather than a disc is produced. The growth of instabilities in the filament formed sub-condensations which are recent sites of star formation.

  12. Fine-Scale Filamentary Structure in Coronal Streamers

    NASA Technical Reports Server (NTRS)

    Woo, Richard; Armstrong, John W.; Bird, Michael K.; Paetzold, Martin

    1995-01-01

    Doppler scintillation measurements of a coronal streamer lasting several solar rotations have been conducted by Ulysses in 1991 over a heliocentric distance range of 14-77 R(sub 0). By showing that the solar corona is filamentary, and that Doppler frequency is the radio counterpart of white-light eclipse pictures processed to enhance spatial gradients, it is demonstrated that Doppler scintillation measurements provide the high spatial resolution that has long eluded white-light coronagraph measurements. The region of enhanced scintillation, spanning an angular extent of 1.8 deg in heliographic longitude, coincides with the radially expanding streamer stalk and represents filamentary structure with scale sizes at least as small as 340 km (0.5 sec) when extrapolated to the Sun. Within the stalk of the streamer, the fine-scale structure corresponding to scale sizes in the range of 20-340 km at the Sun and associated with closed magnetic fields amounts to a few percent of the mean density, while outside the stalk, the fine-scale structure associated with open fields is an order of magnitude lower. Clustering of filamentary structure that takes place within the stalk of the streamer is suggestive of multiple current sheets. Comparison with ISEE 3 in situ plasma measurements shows that significant evolution resulting from dynamic interaction with increasing heliocentric distance takes place by the time streamers reach Earth orbit.

  13. Filamentary Structure in Orion and Monoceros Molecular Clouds

    NASA Astrophysics Data System (ADS)

    Lahaise, W. H.; Bhavsar, S. P.

    1994-05-01

    The filamentary structure in 13CO radio maps of the Orion A, Orion B and Monoceros R2 molecular clouds was analyzed using the Minimal Spanning Tree. This represents the first time the MST has been applied to an extended region such as maps of molecular clouds. The method of preparing and analyzing the data is presented. Integrated maps over a range of velocities were examined as well as a velocity cube constructed from individual 0.5 km s-1 wide channel maps. The results show that there is overwhelming objective and statistical evidence that the filamentary structure does exist in all three of these regions. Previous techniques to identify filaments were generally visual, and therefore subjective. The major filaments in Orion A show linear features extending throughout the entire length. The structure in the velocity cube clearly shows the continuous velocity gradient. Orion B cloud shows distinct regions with north to south orientations. The velocity cube contains a number of filaments at greatly differing velocities, with little evidence of large scale velocity gradients. Mon R2 cloud exhibits two main filamentary components, one of which is associated with both bright condensed regions. The velocity structure reveals an overall velocity gradient.

  14. ATLASGAL: A Galaxy-wide sample of dense filamentary structures

    NASA Astrophysics Data System (ADS)

    Li, Guang-Xing; Urquhart, James S.; Leurini, Silvia; Csengeri, Timea; Wyrowski, Friedrich; Menten, Karl M.; Schuller, Frederic

    2016-06-01

    Context. Filamentary structures are ubiquitous in the interstellar medium. Investigating their connection to the large-scale structure of the Galaxy and their role in star formation is leading to a paradigm shift in our understanding of star formation. Aims: We study the properties of filamentary structures from the ATLASGAL survey, which is the largest and most sensitive systematic ground-based survey of the inner Galactic plane at submillimeter wavelengths. Methods: We use the DisPerSE algorithm to identify spatially coherent structures located across the inner-Galaxy (300° < ℓ < 60° and |b| < 1.5). As a result we produce a catalogue of ~1800 structures; these were then independently classified by the five lead authors into one of the following types: marginally resolved, elongated structures, filaments, network of filaments and complexes. This resulted in the identification of 517 filamentary structures. We determine their physical properties and investigate their overall Galactic distribution. Results: We find that almost 70% of the total 870 μm flux associated with these structures resides in filaments and networks of filaments and we estimate that they are likely to be associated with a similar fraction of the mass. Correlating these structures with tracers of massive star formation we also find that a similar fraction of the massive star forming clumps are associated with filaments and networks of filaments, which highlights the importance of these types of structures to star formation in the Galaxy. We have determined distances, masses and physical sizes for 241 of the filamentary structures. We find a median distance of 3.8 kpc, a mean mass of a few 103 M⊙, a mean length of ~6 pc and a mass-to-length ratio of (M/L) ~200-2000 M⊙ pc-1. We also find that these filamentary structures are tightly correlated with the spiral arms in longitude and velocity, and that their semi-major axis is preferentially aligned parallel to the Galactic mid-plane and

  15. Magnetosheath Filamentary Structures Formed by Ion Acceleration at the Quasi-Parallel Bow Shock

    NASA Technical Reports Server (NTRS)

    Omidi, N.; Sibeck, D.; Gutynska, O.; Trattner, K. J.

    2014-01-01

    Results from 2.5-D electromagnetic hybrid simulations show the formation of field-aligned, filamentary plasma structures in the magnetosheath. They begin at the quasi-parallel bow shock and extend far into the magnetosheath. These structures exhibit anticorrelated, spatial oscillations in plasma density and ion temperature. Closer to the bow shock, magnetic field variations associated with density and temperature oscillations may also be present. Magnetosheath filamentary structures (MFS) form primarily in the quasi-parallel sheath; however, they may extend to the quasi-perpendicular magnetosheath. They occur over a wide range of solar wind Alfvénic Mach numbers and interplanetary magnetic field directions. At lower Mach numbers with lower levels of magnetosheath turbulence, MFS remain highly coherent over large distances. At higher Mach numbers, magnetosheath turbulence decreases the level of coherence. Magnetosheath filamentary structures result from localized ion acceleration at the quasi-parallel bow shock and the injection of energetic ions into the magnetosheath. The localized nature of ion acceleration is tied to the generation of fast magnetosonic waves at and upstream of the quasi-parallel shock. The increased pressure in flux tubes containing the shock accelerated ions results in the depletion of the thermal plasma in these flux tubes and the enhancement of density in flux tubes void of energetic ions. This results in the observed anticorrelation between ion temperature and plasma density.

  16. Magnetosheath filamentary structures formed by ion acceleration at the quasi-parallel bow shock

    NASA Astrophysics Data System (ADS)

    Omidi, N.; Sibeck, D.; Gutynska, O.; Trattner, K. J.

    2014-04-01

    Results from 2.5-D electromagnetic hybrid simulations show the formation of field-aligned, filamentary plasma structures in the magnetosheath. They begin at the quasi-parallel bow shock and extend far into the magnetosheath. These structures exhibit anticorrelated, spatial oscillations in plasma density and ion temperature. Closer to the bow shock, magnetic field variations associated with density and temperature oscillations may also be present. Magnetosheath filamentary structures (MFS) form primarily in the quasi-parallel sheath; however, they may extend to the quasi-perpendicular magnetosheath. They occur over a wide range of solar wind Alfvénic Mach numbers and interplanetary magnetic field directions. At lower Mach numbers with lower levels of magnetosheath turbulence, MFS remain highly coherent over large distances. At higher Mach numbers, magnetosheath turbulence decreases the level of coherence. Magnetosheath filamentary structures result from localized ion acceleration at the quasi-parallel bow shock and the injection of energetic ions into the magnetosheath. The localized nature of ion acceleration is tied to the generation of fast magnetosonic waves at and upstream of the quasi-parallel shock. The increased pressure in flux tubes containing the shock accelerated ions results in the depletion of the thermal plasma in these flux tubes and the enhancement of density in flux tubes void of energetic ions. This results in the observed anticorrelation between ion temperature and plasma density.

  17. Filamentary structure and magnetic field orientation in Musca

    NASA Astrophysics Data System (ADS)

    Cox, N. L. J.; Arzoumanian, D.; André, Ph.; Rygl, K. L. J.; Prusti, T.; Men'shchikov, A.; Royer, P.; Kóspál, Á.; Palmeirim, P.; Ribas, A.; Könyves, V.; Bernard, J.-Ph.; Schneider, N.; Bontemps, S.; Merin, B.; Vavrek, R.; Alves de Oliveira, C.; Didelon, P.; Pilbratt, G. L.; Waelkens, C.

    2016-05-01

    Herschel has shown that filamentary structures are ubiquitous in star-forming regions, in particular in nearby molecular clouds associated with Gould's Belt. High dynamic range far-infrared imaging of the Musca cloud with SPIRE and PACS reveals at least two types of filamentary structures: (1) the main ~10-pc scale high column-density linear filament; and (2) low column-density striations in close proximity to the main filament. In addition, we find features with intermediate column densities (hair-like strands) that appear physically connected to the main filament. We present an analysis of this filamentary network traced by Herschel and explore its connection with the local magnetic field. We find that both the faint dust emission striations and the plane-of-the-sky (POS) magnetic field are locally oriented close to perpendicular to the high-density main filament (position angle ~25-35°). The low-density striations and strands are oriented parallel to the POS magnetic field lines, which are derived previously from optical polarization measurements of background stars and more recently from Planck observations of dust polarized emission. The position angles are 97 ± 25°, 105 ± 7°, and 105 ± 5°. From these observations, we propose a scenario in which local interstellar material in this cloud has condensed into a gravitationally-unstable filament (with "supercritical" mass per unit length) that is accreting background matter along field lines through the striations. We also compare the filamentary structure in Musca with what is seen in similar Herschel observations of the Taurus B211/3 filament system and find that there is significantly less substructure in the Musca main filament than in the B211/3 filament. We suggest that the Musca cloud may represent an earlier evolutionary stage in which the main filament has not yet accreted sufficient mass and energy to develop a multiple system of intertwined filamentary components. Herschel is an ESA space

  18. Metal aircraft structural elements reinforced with graphite filamentary composites

    NASA Technical Reports Server (NTRS)

    Berg, K. R.; Ramsey, J.

    1972-01-01

    Strain compatibility equations are used to evaluate the thermal stresses existing when unidirectional graphite composites are bonded to aluminum structures. Based on thermal stresses and optimum placement of the composite, skin-stringer aluminum panels are optimized for minimum weight compression panels with selective composite reinforcement. Composite reinforced skin-stringer panels are thermal cycled to determine the effect of thermal fatigue on structural integrity. Both cycled and uncycled panels are tested in compression and tension. Test results are correlated with predicted loads. Use of filamentary graphite composites is an efficient method of reinforcing metal structures, but care must be taken to minimize thermal stresses.

  19. FilFinder: Filamentary structure in molecular clouds

    NASA Astrophysics Data System (ADS)

    Koch, Eric W.; Rosolowsky, Erik W.

    2016-08-01

    FilFinder extracts and analyzes filamentary structure in molecular clouds. In particular, it is capable of uniformly extracting structure over a large dynamical range in intensity. It returns the main filament properties: local amplitude and background, width, length, orientation and curvature. FilFinder offers additional tools to, for example, create a filament-only image based on the properties of the radial fits. The resulting mask and skeletons may be saved in FITS format, and property tables may be saved as a CSV, FITS or LaTeX table.

  20. Structural monitoring of filamentary composites using embedded fiber optics

    NASA Technical Reports Server (NTRS)

    Cashon, John L.; Lehner, David L.; Bower, Mark V.; Gilbert, John A.

    1990-01-01

    The feasibility of monitoring overall integrity of structural components made of filamentary composites, by embedding optical fibers between lamina of a composite beam, is investigated using a beam constructed of Kevlar/epoxy cloth with embedded optical fibers aligned with the longitudinal axis of the beam. Phase changes were monitored in three different optical fibers as the composite beam was subjected to pure bending, and the strain response of the fibers was compared to the strain gage readings taken at the surface, showing a strong correlation between the phase change and the applied deformation.

  1. Crawling the Cosmic Web: An Exploration of Filamentary Structure

    NASA Astrophysics Data System (ADS)

    Bond, Nicholas A.; Strauss, M. A.; Cen, R.

    2006-12-01

    By analyzing the smoothed density field and its derivatives on a variety of scales, we can select strands from the cosmic web in a way which is consistent with our common sense understanding of a "filament". We present results from a twoand three-dimensional filament finder, run on both CDM simulations and a section of the SDSS spectroscopic sample. In both data sets, we will analyze the length and width distribution of filamentary structure and discuss its relation to galaxy clusters. Sources of contamination and error, such as "fingers of god", will also be addressed.

  2. The Filamentary Structure of the Lupus 3 Molecular Cloud

    NASA Astrophysics Data System (ADS)

    Benedettini, Milena

    We present the column density map of the Lupus 3 molecular cloud derived from the Herschel photometric maps. We compared the Herschel continuum maps, tracing the dense and cold dust emission, with the CS (2-1) map observed with the Mopra 22-m antenna, tracing the dense gas. Both the continuum and the CS maps show a well defined filamentary structure, with most of the dense cores being on the filaments. The CS (2-1) line shows a double peak in the central part of the longest filament due to the presence of two distinct gas components along this line of sight. Therefore, what seems a single filament in the Herschel map is actually the overlap of two kinematically distinct filaments. This case clearly shows that kinematical information is essential for the correct interpretation of filaments in molecular clouds.

  3. On the filamentary structure of energetic electrons during flares

    NASA Astrophysics Data System (ADS)

    Drake, J.; Swisdak, M.; Shay, M.

    2007-12-01

    Simulations and analytic arguments are presented that demonstrate that magnetic reconnection in the tenuous high temperature corona does not occur as a single large-scale x-line. Rather the narrow current layers that form at x-lines form secondary magnetic islands at small spatial scales. An electron acceleration model based on the interaction of particles with many contracting islands has been developed. A consequence of particle acceleration in any multi-island system is that energetic particles are released in narrow streams with characteristic widths of the order of the electron skin depth. This is because electrons are released from islands as they reconnect with the macro-scale field of the corona or magnetosphere. The characteristic width of the released energetic electron streams correspond to the width of the reconnection dissipation region. Thus, energetic electrons do not propagate away from the reconnection site in the corona as a single large-scale front but as a filamentary web. As a result, the return current problem is transformed: the narrow filaments of energetic particles propagate parallel to the magnetic field as kinetic Alfven waves with propagation speeds comparable to the thermal velocity of the energetic particles. Simple estimates suggest that the conversion of particle to kinetic Alfven wave energy is efficient so that the wave and particle energy propagates together as a radiation front from the corona toward the solar surface. The structure and dynamics of this radiation front are being explored.

  4. The persistent cosmic web and its filamentary structure - II. Illustrations

    NASA Astrophysics Data System (ADS)

    Sousbie, T.; Pichon, C.; Kawahara, H.

    2011-06-01

    The recently introduced discrete persistent structure extractor (DisPerSE, Sousbie, Paper I) is implemented on realistic 3D cosmological simulations and observed redshift catalogues; it is found that DisPerSE traces very well the observed filaments, walls and voids seen both in simulations and in observations. In either setting, filaments are shown to connect on to haloes, outskirt walls, which circumvent voids, as is topologically required by the Morse theory. Indeed this algorithm returns the optimal critical set while operating directly on the particles. DisPerSE, as illustrated here, assumes nothing about the geometry of the survey or its homogeneity, and yields a natural (topologically motivated) self-consistent criterion for selecting the significance level of the identified structures. It is shown that this extraction is possible even for very sparsely sampled point processes, as a function of the persistence ratio (a measure of the significance of topological connections between critical points). Hence, astrophysicists should be in a position to trace precisely the locus of filaments, walls and voids from such samples and assess the confidence of the post-processed sets as a function of this threshold, which can be expressed relative to the expected amplitude of shot noise. In a cosmic framework, this criterion is shown to level with the friends-of-friends structure finder for the identification of peaks, while it also identifies the connected filaments and walls, and quantitatively recovers the full set of topological invariants (number of holes, etc.) directly from the particles, and at no extra cost as a function of the persistence threshold. This criterion is found to be sufficient even if one particle out of two is noise, when the persistence ratio is set to 3σ or more. The algorithm is also implemented on the SDSS catalogue and used to locate interesting configurations of the filamentary structure. In this context, we carried the identification of an

  5. VizieR Online Data Catalog: ATLASGAL dense filamentary structures (Li+, 2016)

    NASA Astrophysics Data System (ADS)

    Li, G.-X.; Urquhart, J. S.; Leurini, S.; Csengeri, T.; Wyrowski, F.; Menten, K. M.; Schuller, F.

    2016-05-01

    The ATLASGAL survey (Schuller et al., 2009A&A...504..415S) covers 300°filamentary structures in the ATLASGAL survey. This has been achieved through two steps. First, we extract skeleton representations of structures in the dust continuum emission maps with the DisPerSE (Discrete Persistent Extractor; Sousbie, 2011MNRAS.414..350S). Then, the extracted structures are classified, and filamentary structures are identified. (10 data files).

  6. Method and apparatus for fabricating a composite structure consisting of a filamentary material in a metal matrix

    DOEpatents

    Banker, J.G.; Anderson, R.C.

    1975-10-21

    A method and apparatus are provided for preparing a composite structure consisting of filamentary material within a metal matrix. The method is practiced by the steps of confining the metal for forming the matrix in a first chamber, heating the confined metal to a temperature adequate to effect melting thereof, introducing a stream of inert gas into the chamber for pressurizing the atmosphere in the chamber to a pressure greater than atmospheric pressure, confining the filamentary material in a second chamber, heating the confined filamentary material to a temperature less than the melting temperature of the metal, evacuating the second chamber to provide an atmosphere therein at a pressure, placing the second chamber in registry with the first chamber to provide for the forced flow of the molten metal into the second chamber to effect infiltration of the filamentary material with the molten metal, and thereafter cooling the metal infiltrated-filamentary material to form said composite structure.

  7. Ultra-fine-scale filamentary structures in the Outer Corona and the Solar Magnetic Field

    NASA Technical Reports Server (NTRS)

    Woo, Richard

    2006-01-01

    Filamentary structures following magnetic field lines pervade the Sun's atmosphere and offer us insight into the solar magnetic field. Radio propagation measurements have shown that the smallest filamentary structures in the solar corona are more than 2 orders of magnitude finer than those seen in solar imaging. Here we use radio Doppler measurements to characterize their transverse density gradient and determine their finest scale in the outer corona at 20-30 R(circled dot operator), where open magnetic fields prevail. Filamentary structures overly active regions have the steepest gradient and finest scale, while those overlying coronal holes have the shallowest gradient and least finest scale. Their organization by the underlying corona implies that these subresolution structures extend radially from the entire Sun, confirming that they trace the coronal magnetic field responsible for the radial expansion of the solar wind. That they are rooted all over the Sun elucidates the association between the magnetic field of the photosphere and that of the corona, as revealed by the similarity between the power spectra of the photospheric field and the coronal density fluctuations. This association along with the persistence of filamentary structures far from the Sun demonstrate that subresolution magnetic fields must play an important role not only in magnetic coupling of the photosphere and corona, but also in coronal heating and solar wind acceleration through the process of small-scale magnetic reconnection. They also explain why current widely used theoretical models that extrapolate photospheric magnetic fields into the corona do not predict the correct source of the solar wind.

  8. Electromagnetic structure of pion

    SciTech Connect

    Mello, Clayton S.; Cruz Filho, Jose P.; Da Silva, Edson O.; El-Bennich, Bruno; De Melo, J. P.; Filho, Victo S.

    2013-03-25

    In this work, we analyze the electromagnetic structure of the pion, an elementary particle composed by a quark-antiquark bound state, by considering the calculation of its electromagnetic radius and its electromagnetic form factor in low and intermediate energy range. Such observables are determined by means of a theoretical model that takes into account the constituent quark and antiquark of the pion, in the formalism of the light-front field theory. In particular, it is considered a nonsymmetrical vertex for such a model, in which we have calculated the electromagnetic form factor of the pion in an optimized way, by varying its regulator mass, so that we can obtain the best value for the pion electromagnetic radius when compared with the experimental one. The theoretical calculations are also compared with the most recent experimental data involving the pion electromagnetic form factor and the results show very good agreement.

  9. FORMATION OF COLD FILAMENTARY STRUCTURE FROM WIND-BLOWN SUPERBUBBLES

    SciTech Connect

    Ntormousi, Evangelia; Burkert, Andreas; Fierlinger, Katharina; Heitsch, Fabian

    2011-04-10

    The expansion and collision of two wind-blown superbubbles is investigated numerically. Our models go beyond previous simulations of molecular cloud formation from converging gas flows by exploring this process with realistic flow parameters, sizes, and timescales. The superbubbles are blown by time-dependent winds and supernova explosions, calculated from population synthesis models. They expand into a uniform or turbulent diffuse medium. We find that dense, cold gas clumps and filaments form naturally in the compressed collision zone of the two superbubbles. Their shapes resemble the elongated, irregular structure of observed cold, molecular gas filaments, and clumps. At the end of the simulations, between 65% and 80% of the total gas mass in our simulation box is contained in these structures. The clumps are found in a variety of physical states, ranging from pressure equilibrium with the surrounding medium to highly underpressured clumps with large irregular internal motions and structures which are rotationally supported.

  10. Residual stress alleviation of aircraft metal structures reinforced with filamentary composites

    NASA Technical Reports Server (NTRS)

    Kelly, J. B.; June, R. R.

    1973-01-01

    Methods to eliminate or reduce residual stresses in aircraft metal structures reinforced by filamentary composites are discussed. Residual stress level reductions were achieved by modifying the manufacturing procedures used during adhesive bonding. The residual stress alleviation techniques involved various forms of mechanical constraint which were applied to the components during bonding. Nine methods were evaluated, covering a wide range in complexity. All methods investigated during the program affected the residual stress level. In general, residual stresses were reduced by 70 percent or more from the stress level produced by conventional adhesive bonding procedures.

  11. A discussion of the H-alpha filamentary nebulae and galactic structure in the Cygnus region

    NASA Technical Reports Server (NTRS)

    Matthews, T. A.; Simonson, S. C., III

    1971-01-01

    From observation of the galactic structure in Cygnus, the system of filamentary nebulae was found to lie at a distance of roughly 1.5 kpc, in the same region as about half the thermal radio sources in Cygnus X, the supernova remnant near gamma Cygni, and the association Cygnus OB2, in the direction of which the X-ray source Cygnus XR-3 is observed. The source of excitation was probably the pulse of radiation from a supernova explosion, as proposed in the case of Gum nebula. However continuing excitation by early stars in the region of Cygnus X cannot be excluded.

  12. Filamentary structure on the Sun from the magnetic Rayleigh-Taylor instability.

    PubMed

    Isobe, Hiroaki; Miyagoshi, Takehiro; Shibata, Kazunari; Yokoyama, Takaaki

    2005-03-24

    Magnetic flux emerges from the solar surface as dark filaments connecting small sunspots with opposite polarities. The regions around the dark filaments are often bright in X-rays and are associated with jets. This implies plasma heating and acceleration, which are important for coronal heating. Previous two-dimensional simulations of such regions showed that magnetic reconnection between the coronal magnetic field and the emerging flux produced X-ray jets and flares, but left unresolved the origin of filamentary structure and the intermittent nature of the heating. Here we report three-dimensional simulations of emerging flux showing that the filamentary structure arises spontaneously from the magnetic Rayleigh-Taylor instability, contrary to the previous view that the dark filaments are isolated bundles of magnetic field that rise from the photosphere carrying the dense gas. As a result of the magnetic Rayleigh-Taylor instability, thin current sheets are formed in the emerging flux, and magnetic reconnection occurs between emerging flux and the pre-existing coronal field in a spatially intermittent way. This explains naturally the intermittent nature of coronal heating and the patchy brightenings in solar flares. PMID:15791248

  13. A Graph-Theoretical Approach for Tracing Filamentary Structures in Neuronal and Retinal Images.

    PubMed

    De, Jaydeep; Cheng, Li; Zhang, Xiaowei; Lin, Feng; Li, Huiqi; Ong, Kok Haur; Yu, Weimiao; Yu, Yuanhong; Ahmed, Sohail

    2016-01-01

    The aim of this study is about tracing filamentary structures in both neuronal and retinal images. It is often crucial to identify single neurons in neuronal networks, or separate vessel tree structures in retinal blood vessel networks, in applications such as drug screening for neurological disorders or computer-aided diagnosis of diabetic retinopathy. Both tasks are challenging as the same bottleneck issue of filament crossovers is commonly encountered, which essentially hinders the ability of existing systems to conduct large-scale drug screening or practical clinical usage. To address the filament crossovers' problem, a two-step graph-theoretical approach is proposed in this paper. The first step focuses on segmenting filamentary pixels out of the background. This produces a filament segmentation map used as input for the second step, where they are further separated into disjointed filaments. Key to our approach is the idea that the problem can be reformulated as label propagation over directed graphs, such that the graph is to be partitioned into disjoint sub-graphs, or equivalently, each of the neurons (vessel trees) is separated from the rest of the neuronal (vessel) network. This enables us to make the interesting connection between the tracing problem and the digraph matrix-forest theorem in algebraic graph theory for the first time. Empirical experiments on neuronal and retinal image datasets demonstrate the superior performance of our approach over existing methods. PMID:26316029

  14. Optical structure and function of the white filamentary hair covering the edelweiss bracts

    NASA Astrophysics Data System (ADS)

    Vigneron, Jean Pol; Rassart, Marie; Vértesy, Zofia; Kertész, Krisztián; Sarrazin, Michaël; Biró, László P.; Ertz, Damien; Lousse, Virginie

    2005-01-01

    The optical properties of the inflorescence of the high-altitude Leontopodium nivale subsp. alpinum (edelweiss) is investigated, in relation with its submicrometer structure, as determined by scanning electron microscopy. The filaments forming the hair layer have been found to exhibit an internal structure which may be one of the few examples of a photonic structure found in a plant. Measurements of light transmission through a self-supported layer of hair pads taken from the bracts supports the idea that the wooly layer covering the plant absorbs near-ultraviolet radiation before it reaches the cellular tissue. Calculations based on a photonic-crystal model provide insight on the way radiation can be absorbed by the filamentary threads.

  15. Particle Acceleration at Filamentary Structures Downstream of Collisionless Shocks in the Heliosphere.

    NASA Astrophysics Data System (ADS)

    Kucharek, H.; Pogorelov, N. V.; Gamayunov, K. V.

    2015-12-01

    Collisionless shocks are an important feature in astrophysical, heliospheric and magnetospheric settings. At these structures plasma is heated, the properties of flows are changed, and particles are accelerated to high energies. Particles are accelerated throughout the heliosphere. There are no times or conditions where suprathermal ions forming tails are not present on the solar wind ion distribution, and given the low speeds of these particles they must be accelerated locally in the heliosphere. Coronal mass ejections (CMEs) and co-rotating interaction regions (CIRs) accelerate particles up to 10s of MeV/nucleon. The termination shock of the solar and the heliosheath produce energetic particles including the Anomalous Cosmic Rays (ACRs), with energies in excess of 100 MeV. In the last few years' very interesting observations at low energies showing power laws that cannot be explained with commonly accepted acceleration mechanisms and thus increased the need for alternative acceleration processes. Fully consistent kinetic particle simulations such as hybrid simulations appear to be a powerful tool to investigated ion acceleration. Nowadays these simulations can be performed in 3D and relative large simulation domains covering up to hundreds of ion inertial length in size and thus representing the MHD scale. These 3D hybrid simulations show filamentary magnetic and density structures, which could be interpreted as small-scale flux ropes. The growth of these small-scale structures is also associated with ion acceleration. In this talk we will discuss properties of these filamentary structures, their spatial and temporal evolution and the particle dynamics during the acceleration process. The results of this study may be of particular importance for future high resolution magnetospheric and heliospheric mission such as THOR.

  16. VizieR Online Data Catalog: Bright filamentary structures in the ISM (Jackson+, 2003)

    NASA Astrophysics Data System (ADS)

    Jackson, T.; Werner, M.; Gautier, T. N., III

    2003-11-01

    We present a listing of prominent filamentary structures in the interstellar cirrus, selected with an eye toward current and planned far-infrared and submillimeter polarimetry facilities. The filaments were identified on the 100{mu}m plates of the IRAS Sky Survey Atlas (ISSA, Wheelock et al. 1994, IRAS Sky Survey Atlas: Explanatory Supplement (JPL Publ. 94-11; Pasadena: JPL)), using a computer vision algorithm that is unbiased with respect to source intensity. Our catalog is two-tiered: the selection criteria in the Galactic plane are based on the sensitivity limits of airborne polarimeters such as the proposed HALE instrument for SOFIA, and away from the plane the limits are dictated by the sensitivities of balloon-borne cosmic microwave background experiments, such as BOOMERanG and MAXIMA. Infrared detector technology is currently at the point where detecting the polarization of the interstellar cirrus is feasible, and we hope this catalog will assist any experimenter undertaking this task. (3 data files).

  17. The filamentary structure of mixing fronts and its control on reaction kinetics in porous media flows

    NASA Astrophysics Data System (ADS)

    de Anna, Pietro; Dentz, Marco; Tartakovsky, Alexandre; Le Borgne, Tanguy

    2014-07-01

    The mixing dynamics resulting from the combined action of diffusion, dispersion, and advective stretching of a reaction front in heterogeneous flows leads to reaction kinetics that can differ by orders of magnitude from those measured in well-mixed batch reactors. The reactive fluid invading a porous medium develops a filamentary or lamellar front structure. Fluid deformation leads to an increase of the front length by stretching and consequently a decrease of its width by compression. This advective front deformation, which sharpens concentration gradients across the interface, is in competition with diffusion, which tends to increase the interface width and thus smooth concentration gradients. The lamella scale dynamics eventually develop into a collective behavior through diffusive coalescence, which leads to a disperse interface whose width is controlled by advective dispersion. We derive a new approach that quantifies the impact of these filament scale processes on the global mixing and reaction kinetics. The proposed reactive filament model, based on the elementary processes of stretching, coalescence, and fluid particle dispersion, provides a new framework for predicting reaction front kinetics in heterogeneous flows.

  18. Analytical and experimental investigation of aircraft metal structures reinforced with filamentary composites. Phase 3: Major component development

    NASA Technical Reports Server (NTRS)

    Bryson, L. L.; Mccarty, J. E.

    1973-01-01

    Analytical and experimental investigations, performed to establish the feasibility of reinforcing metal aircraft structures with advanced filamentary composites, are reported. Aluminum-boron-epoxy and titanium-boron-epoxy were used in the design and manufacture of three major structural components. The components were representative of subsonic aircraft fuselage and window belt panels and supersonic aircraft compression panels. Both unidirectional and multidirectional reinforcement concepts were employed. Blade penetration, axial compression, and inplane shear tests were conducted. Composite reinforced structural components designed to realistic airframe structural criteria demonstrated the potential for significant weight savings while maintaining strength, stability, and damage containment properties of all metal components designed to meet the same criteria.

  19. Unusual Domain Structure and Filamentary Superfluidity for 2D Hard-Core Bosons in Insulating Charge-Ordered Phase

    NASA Astrophysics Data System (ADS)

    Panov, Yu. D.; Moskvin, A. S.; Rybakov, F. N.; Borisov, A. B.

    2016-01-01

    We made use of a special algorithm for compute unified device architecture for NVIDIA graphics cards, a nonlinear conjugate-gradient method to minimize energy functional, and Monte-Carlo technique to directly observe the forming of the ground state configuration for the 2D hard-core bosons by lowering the temperature and its evolution with deviation away from half-filling. The novel technique allowed us to examine earlier implications and uncover novel features of the phase transitions, in particular, look upon the nucleation of the odd domain structure, emergence of filamentary superfluidity nucleated at the antiphase domain walls of the charge-ordered phase, and nucleation and evolution of different topological structures.

  20. Analytical and experimental investigation of aircraft metal structures reinforced with filamentary composites. Phase 1: Concept development and feasibility

    NASA Technical Reports Server (NTRS)

    Oken, S.; June, R. R.

    1971-01-01

    The analytical and experimental investigations are described in the first phase of a program to establish the feasibility of reinforcing metal aircraft structures with advanced filamentary composites. The interactions resulting from combining the two types of materials into single assemblies as well as their ability to function structurally were studied. The combinations studied were boron-epoxy reinforced aluminum, boron-epoxy reinforced titanium, and boron-polyimide reinforced titanium. The concepts used unidirectional composites as reinforcement in the primary loading direction and metal for carrying the transverse loads as well as its portion of the primary load. The program established that several realistic concepts could be fabricated, that these concepts could perform to a level that would result in significant weight savings, and that there are means for predicting their capability within a reasonable degree of accuracy. This program also encountered problems related to the application of polyimide systems that resulted in their relatively poor and variable performance.

  1. Magnetohydrostatic equilibrium structure and mass of filamentary isothermal cloud threaded by lateral magnetic field

    SciTech Connect

    Tomisaka, Kohji

    2014-04-10

    Herschel observations have recently revealed that interstellar molecular clouds consist of many filaments. Polarization observations in optical and infrared wavelengths indicate that the magnetic field often runs perpendicular to the filament. In this article, we study the magnetohydrostatic configuration of isothermal gas in which the thermal pressure and the Lorentz force are balanced against the self-gravity, and the magnetic field is globally perpendicular to the axis of the filament. The model is controlled by three parameters: center-to-surface density ratio (ρ {sub c}/ρ {sub s}), plasma β of surrounding interstellar gas (β{sub 0}), and the radius of the hypothetical parent cloud normalized by the scale-height (R{sub 0}{sup ′}), although there remains freedom in how the mass is distributed against the magnetic flux (mass loading). In the case where R{sub 0}{sup ′} is small enough, the magnetic field plays a role in confining the gas. However, the magnetic field generally has the effect of supporting the cloud. There is a maximum line-mass (mass per unit length) above which the cloud is not supported against gravity. Compared with the maximum line-mass of a nonmagnetized cloud (2c{sub s}{sup 2}/G, where c{sub s} and G represent, respectively, the isothermal sound speed and the gravitational constant), that of the magnetized filament is larger than the nonmagnetized one. The maximum line-mass is numerically obtained as λ{sub max}≃0.24Φ{sub cl}/G{sup 1/2}+1.66c{sub s}{sup 2}/G, where Φ{sub cl} represents one half of the magnetic flux threading the filament per unit length. The maximum mass of the filamentary cloud is shown to be significantly affected by the magnetic field when the magnetic flux per unit length exceeds Φ{sub cl} ≳ 3 pc μG (c{sub s} /190 m s{sup –1}){sup 2}.

  2. The formation of filamentary structures from molten silicates: Peleʼs hair, angel hair, and blown clinker

    NASA Astrophysics Data System (ADS)

    Villermaux, Emmanuel

    2012-08-01

    We conduct an analysis of the concomitant, competing phenomena at play in the formation of long filamentary structures from a stream of hot, very viscous and cohesive liquid as it is blown by a fast, cool air stream. The situation is relevant to a broad class of problems, namely volcanic glass threads or fibers formed when small particles of molten material are thrown into the air and spun out by the wind into long hair-like strands (called Pele's hair), to the process of prilling, the manufacture of glass fibers, and the formation of coke in furnaces and combustion chambers. The air stream blowing on the molten material both breaks up the liquid into fragments stabilized by capillarity, and cools the liquid down to solidification. There are, in this problem, four characteristic times. First, a deformation time of the liquid masses, setting the rate at which drops elongate into ligaments. Then, two timescales set the time of capillary breakup of these ligaments, one prevailing on the other depending on the relative weight of inertia on viscous slowing (that point is illustrated by an original experiment). Finally, a solidification time of the ligaments. Thin solid strands will only form when solidification occurs before capillary breakup. We have discovered that this condition is likely to apply when the liquid is strongly viscous, as for clinker in the cement industry, considered here as a generic example. We formulate recommendations to remove (or enhance) the formation of these objects.

  3. Electromagnetic structure of light nuclei

    DOE PAGESBeta

    Pastore, Saori

    2016-03-25

    Here, the present understanding of nuclear electromagnetic properties including electromagnetic moments, form factors and transitions in nuclei with A ≤ 10 is reviewed. Emphasis is on calculations based on nuclear Hamiltonians that include two- and three-nucleon realistic potentials, along with one- and two-body electromagnetic currents derived from a chiral effective field theory with pions and nucleons.

  4. Electromagnetic scattering by impedance structures

    NASA Technical Reports Server (NTRS)

    Balanis, Constantine A.; Griesser, Timothy

    1987-01-01

    The scattering of electromagnetic waves from impedance structures is investigated, and current work on antenna pattern calculation is presented. A general algorithm for determining radiation patterns from antennas mounted near or on polygonal plates is presented. These plates are assumed to be of a material which satisfies the Leontovich (or surface impedance) boundary condition. Calculated patterns including reflection and diffraction terms are presented for numerious geometries, and refinements are included for antennas mounted directly on impedance surfaces. For the case of a monopole mounted on a surface impedance ground plane, computed patterns are compared with experimental measurements. This work in antenna pattern prediction forms the basis of understanding of the complex scattering mechanisms from impedance surfaces. It provides the foundation for the analysis of backscattering patterns which, in general, are more problematic than calculation of antenna patterns. Further proposed study of related topics, including surface waves, corner diffractions, and multiple diffractions, is outlined.

  5. The filamentary structure of mixing fronts and its control on reaction kinetics in porous media flows

    SciTech Connect

    de Anna, Pietro; Dentz, Marco; Tartakovsky, Alexandre M.; Le Borgne, Tanguy

    2014-07-08

    We investigate the effective kinetics of a reaction front for mixing limited bimolecular reaction $A+B\\rightarrow C$ in a porous medium. While Fickian diffusion predicts a scaling of the cumulative mass produced as $M_C \\propto t^{1/2}$, we observe two time regimes in which the total product mass evolves faster then $t^{1/2}$. At early times the invading solute is organized in fingers of high velocity. Reactions take place only at the fingers boundaries whose surface grows linearly in time. We show that this configuration leads to a mass scaling $M_C \\propto t^2$. When diffusion mixes reactants and destroy these finger structures, the effective reaction rate slows down and we relate it to the longitudinal advective spreading providing $M_C \\propto \\sigma_x$. The transition time between these two regimes is characterized by the diffusion time over the transverse fingers cross section.

  6. The persistent cosmic web and its filamentary structure - I. Theory and implementation

    NASA Astrophysics Data System (ADS)

    Sousbie, T.

    2011-06-01

    We present DisPerSE, a novel approach to the coherent multiscale identification of all types of astrophysical structures, in particular the filaments, in the large-scale distribution of the matter in the Universe. This method and the corresponding piece of software allows for a genuinely scale-free and parameter-free identification of the voids, walls, filaments, clusters and their configuration within the cosmic web, directly from the discrete distribution of particles in N-body simulations or galaxies in sparse observational catalogues. To achieve that goal, the method works directly over the Delaunay tessellation of the discrete sample and uses the Delaunay tessellation field estimator density computed at each tracer particle; no further sampling, smoothing or processing of the density field is required. The idea is based on recent advances in distinct subdomains of the computational topology, namely the discrete Morse theory which allows for a rigorous application of topological principles to astrophysical data sets, and the theory of persistence, which allows us to consistently account for the intrinsic uncertainty and Poisson noise within data sets. Practically, the user can define a given persistence level in terms of robustness with respect to noise (defined as a 'number of σ') and the algorithm returns the structures with the corresponding significance as sets of critical points, lines, surfaces and volumes corresponding to the clusters, filaments, walls and voids - filaments, connected at cluster nodes, crawling along the edges of walls bounding the voids. From a geometrical point of view, the method is also interesting as it allows for a robust quantification of the topological properties of a discrete distribution in terms of Betti numbers or Euler characteristics, without having to resort to smoothing or having to define a particular scale. In this paper, we introduce the necessary mathematical background and describe the method and implementation

  7. Structural composites with integrated electromagnetic functionality

    NASA Astrophysics Data System (ADS)

    Nemat-Nasser, Syrus C.; Amirkhizi, Alireza V.; Plaisted, Thomas; Isaacs, Jon; Nemat-Nasser, Siavouche

    2002-07-01

    We are studying the incorporation of electromagnetic effective media in the form of arrays of metal scattering elements, such as wires, into polymer-based or ceramic-based composites. In addition to desired structural properties, these electromagnetic effective media can provide controlled response to electromagnetic radiation such as RF communication signals, radar, and/or infrared radiation. With the addition of dynamic components, these materials may be leveraged for active tasks such as filtering. The advantages of such hybrid composites include simplicity and weight savings by the combination of electromagnetic functionality with necessary structural functionality. This integration of both electromagnetic and structural functionality throughout the volume of the composite is the distinguishing feature of our approach. As an example, we present a class of composites based on the integration of artificial plasmon media into polymer matrixes. Such composites can exhibit a broadband index of refraction substantially equal to unity at microwave frequencies and below.

  8. Filamentary structure of plasma produced by compression of puffing deuterium by deuterium or neon plasma sheath on plasma-focus discharge

    SciTech Connect

    Kubes, P.; Cikhardt, J.; Kortanek, J.; Cikhardtova, B.; Rezac, K.; Klir, D.; Kravarik, J.; Paduch, M.; Zielinska, E.

    2014-12-15

    The present experiments were performed on the PF-1000 plasma focus device at a current of 2 MA with the deuterium injected from the gas-puff placed in the axis of the anode face. The XUV frames showed, in contrast with the interferograms, the fine structure: filaments and spots up to 1 mm diameter. In the deuterium filling, the short filaments are registered mainly in the region of the internal plasmoidal structures and their number correlates with the intensity of neutron production. The longer filamentary structure was recorded close to the anode after the constriction decay. The long curve-like filaments with spots were registered in the big bubble formed after the pinch phase in the head of the umbrella shape of the plasma sheath. Filaments can indicate the filamentary structure of the current in the pinch. Together with the filaments, small compact balls a few mm in diameter were registered by both interferometry and XUV frame pictures. They emerge out of the dense column and their life-time can be greater than hundreds of ns.

  9. Computes Generalized Electromagnetic Interactions Between Structures

    Energy Science and Technology Software Center (ESTSC)

    1999-02-20

    Object oriented software for computing generalized electromagnetic interactions between structures in the frequency domains. The software is based on integral equations. There is also a static integral equation capability.

  10. Analytical and experimental investigation of aircraft metal structures reinforced with filamentary composites. Phase 2: Structural fatigue, thermal cycling, creep, and residual strength

    NASA Technical Reports Server (NTRS)

    Blichfeldt, B.; Mccarty, J. E.

    1972-01-01

    Specimens representative of metal aircraft structural components reinforced with boron filamentary composites were manufactured and tested under cyclic loading, cyclic temperature, or continuously applied loading to evaluate some of the factors that affect structural integrity under cyclic conditions. Bonded, stepped joints were used throughout to provide composite-to-metal transition regions at load introduction points. Honeycomb panels with titanium or aluminum faces reinforced with unidirectional boron composite were fatigue tested at constant amplitude under completely reversed loading. Results indicated that the matrix material was the most fatigue-sensitive part of the design, with debonding initiating in the stepped joints. However, comparisons with equal weight all-metal specimens show a 10 to 50 times improved fatigue life. Fatigue crack propagation and residual strength were studied for several different stiffened panel concepts, and were found to vary considerably depending on the configuration. Composite-reinforced metal specimens were also subjected to creep and thermal cycling tests. Thermal cycling of stepped joint tensile specimens resulted in a ten percent decrease in residual strength after 4000 cycles.

  11. Fragmentation in filamentary molecular clouds

    NASA Astrophysics Data System (ADS)

    Contreras, Yanett; Garay, Guido; Rathborne, Jill M.; Sanhueza, Patricio

    2016-02-01

    Recent surveys of dust continuum emission at sub-mm wavelengths have shown that filamentary molecular clouds are ubiquitous along the Galactic plane. These structures are inhomogeneous, with overdensities that are sometimes associated with infrared emission and active of star formation. To investigate the connection between filaments and star formation, requires an understanding of the processes that lead to the fragmentation of filaments and a determination of the physical properties of the overdensities (clumps). In this paper, we present a multiwavelength study of five filamentary molecular clouds, containing several clumps in different evolutionary stages of star formation. We analyse the fragmentation of the filaments and derive the physical properties of their clumps. We find that the clumps in all filaments have a characteristic spacing consistent with the prediction of the `sausage' instability theory, regardless of the complex morphology of the filaments or their evolutionary stage. We also find that most clumps have sufficient mass and density to form high-mass stars, supporting the idea that high-mass stars and clusters form within filaments.

  12. Vector resonances and electromagnetic nucleon structure

    SciTech Connect

    Williams, R.A.; Krewald, S.; Linen, K. )

    1995-02-01

    Motivated by new, precise magnetic proton form factor data in the timelike reigon, a hybrid vector meson dominance (hVMD) formalism is employed to investigate the significance of excited vector meson rsonances on electromagnetic nucleon structure. We find that the [rho](1700), [omega](1600), and two previously unobserved states are required to reproduce the local structure seen in the new LEAR data just above the [ital p[bar p

  13. Controls-structures-electromagnetics interaction program

    NASA Technical Reports Server (NTRS)

    Grantham, William L.; Bailey, Marion C.; Belvin, Wendell K.; Williams, Jeffrey P.

    1987-01-01

    A technology development program is described involving Controls Structures Electromagnetics Interaction (CSEI) for large space structures. The CSEI program was developed as part of the continuing effort following the successful kinematic deployment and RF tests of the 15 meter Hoop/Column antenna. One lesson learned was the importance of making reflector surface adjustment after fabrication and deployment. Given are program objectives, ground based test configuration, Intelsat adaptive feed, reflector shape prediction model, control experiment concepts, master schedule, and Control Of Flexible Structures-II (COFS-II) baseline configuration.

  14. Electromagnetic studies of nucleon and nuclear structure

    SciTech Connect

    Heisenberg, J.H.; Calarco, J.R.; Hersman, F.W.; Dawson, J.F.

    1993-06-01

    Important objectives of the group are the study of subatomic structure through experimental measurements and the interpretation of the data through modeling. The common theme that unifies the studies of strong interactions and hadronic systems is the effort to determine the electromagnetic response as completely as possible. The general approach is coincidence detection of exclusive final states and determination of the dependence on the spin variables using polarized beams and targets and outgoing nucleon polarimetry. Direct reaction and giant resonance studies of electron quasi-elastic scattering on {sup 12}C and {sup 16}O are reported, as well as work on nuclear structure models and instrumentation development.

  15. Filamentary magnetohydrodynamic plasmas

    SciTech Connect

    Kinney, R.; Tajima, T.; Petviashvili, N.; McWilliams, J.C.

    1993-05-01

    A filamentary construct of magnetohydrodynamical plasma dynamics, based on the Elsasser variables was developed. This approach is modeled after discrete vortex models of hydrodynamical turbulence, which cannot be expected in general to produce results identical to ones based on a Fourier decomposition of the fields. In a highly intermittent plasma, the induction force is small compared to the convective motion, and when this force is neglected. the plasma vortex system is described by a Hamiltonian. For a system with many such vortices we present a statistical treatment of a collection of discrete current-vorticity concentrations. Canonical and microcanonical statistical calculations show that both the vorticity and the current spectra are peaked at long wavelengths, and the expected states revert to known hydrodynamical states as the magnetic field vanishes. These results differ from previous Fourier-based statistical theories. but it is found that when the filament calculation is expanded to include the inductive force, the results approach the Fourier equilibria in the low-temperature limit, and the previous Hamiltonian plasma vortex results in the high-temperature limit. Numerical simulations of a large number of filaments are carried out and support the theory. A three-dimensional vortex model is outlined as well, which is also Hamiltonian when the inductive force is neglected.

  16. Filamentary magnetohydrodynamic plasmas

    SciTech Connect

    Kinney, R.; Tajima, T. ); McWilliams, J.C. ); Petviashvili, N. )

    1994-02-01

    A filamentary construct of magnetohydrodynamical plasma dynamics based on the Elsaesser variables is developed. This approach is modeled after discrete vortex models of hydrodynamical turbulence, which cannot be expected in general to produce results identical to those based on a Fourier decomposition of the fields. In a highly intermittent plasma, the induction force is small compared to the convective motion, and when this force is neglected, the plasma vortex system is described by a Hamiltonian. A statistical treatment of a collection of discrete current-vorticity concentrations is given. Canonical and microcanonical statistical calculations show that both the vorticity and the current spectra are peaked at long wavelengths, and the expected states revert to known hydrodynamical states as the magnetic field vanishes. These results differ from previous Fourier-based statistical theories, but it is found that when the filament calculation is expanded to include the inductive force, the results approach the Fourier equilibria in the low-temperature limit, and the previous Hamiltonian plasma vortex results in the high-temperature limit. Numerical simulations of a large number of filaments are carried out and support the theory. A three-dimensional vortex model is presented as well, which is also Hamiltonian when the inductive force is neglected. A statistical calculation in the canonical ensemble and numerical simulations show that a nonzero large-scale magnetic field is statistically favored, and that the preferred shape of this field is a long, thin tube of flux. Possible applications to a variety of physical phenomena are suggested.

  17. Filamentary magnetohydrodynamic plasmas

    NASA Astrophysics Data System (ADS)

    Kinney, R.; Tajima, T.; Petviashvili, N.; McWilliams, J. C.

    1993-05-01

    A filamentary construct of magnetohydrodynamical plasma dynamics, based on the Elsasser variables was developed. This approach is modeled after discrete vortex models of hydrodynamical turbulence, which cannot be expected in general to produce results identical to ones based on a Fourier decomposition of the fields. In a highly intermittent plasma, the induction force is small compared to the convective motion, and when this force is neglected, the plasma vortex system is described by a Hamiltonian. For a system with many such vortices we present a statistical treatment of a collection of discrete current-vorticity concentrations. Canonical and microcanonical statistical calculations show that both the vorticity and the current spectra are peaked at long wavelengths, and the expected states revert to known hydrodynamical states as the magnetic field vanishes. These results differ from previous Fourier-based statistical theories, but it is found that when the filament calculation is expanded to include the inductive force, the results approach the Fourier equilibria in the low-temperature limit, and the previous Hamiltonian plasma vortex results in the high-temperature limit. Numerical simulations of a large number of filaments are carried out and support the theory. A three-dimensional vortex model is outlined as well, which is also Hamiltonian when the inductive force is neglected.

  18. Spatially variant periodic structures in electromagnetics.

    PubMed

    Rumpf, Raymond C; Pazos, Javier J; Digaum, Jennefir L; Kuebler, Stephen M

    2015-08-28

    Spatial transforms are a popular technique for designing periodic structures that are macroscopically inhomogeneous. The structures are often required to be anisotropic, provide a magnetic response, and to have extreme values for the constitutive parameters in Maxwell's equations. Metamaterials and photonic crystals are capable of providing these, although sometimes only approximately. The problem still remains about how to generate the geometry of the final lattice when it is functionally graded, or spatially varied. This paper describes a simple numerical technique to spatially vary any periodic structure while minimizing deformations to the unit cells that would weaken or destroy the electromagnetic properties. New developments in this algorithm are disclosed that increase efficiency, improve the quality of the lattices and provide the ability to design aplanatic metasurfaces. The ability to spatially vary a lattice in this manner enables new design paradigms that are not possible using spatial transforms, three of which are discussed here. First, spatially variant self-collimating photonic crystals are shown to flow unguided waves around very tight bends using ordinary materials with low refractive index. Second, multi-mode waveguides in spatially variant band gap materials are shown to guide waves around bends without mixing power between the modes. Third, spatially variant anisotropic materials are shown to sculpt the near-field around electric components. This can be used to improve electromagnetic compatibility between components in close proximity. PMID:26217058

  19. Spatially variant periodic structures in electromagnetics

    PubMed Central

    Rumpf, Raymond C.; Pazos, Javier J.; Digaum, Jennefir L.; Kuebler, Stephen M.

    2015-01-01

    Spatial transforms are a popular technique for designing periodic structures that are macroscopically inhomogeneous. The structures are often required to be anisotropic, provide a magnetic response, and to have extreme values for the constitutive parameters in Maxwell's equations. Metamaterials and photonic crystals are capable of providing these, although sometimes only approximately. The problem still remains about how to generate the geometry of the final lattice when it is functionally graded, or spatially varied. This paper describes a simple numerical technique to spatially vary any periodic structure while minimizing deformations to the unit cells that would weaken or destroy the electromagnetic properties. New developments in this algorithm are disclosed that increase efficiency, improve the quality of the lattices and provide the ability to design aplanatic metasurfaces. The ability to spatially vary a lattice in this manner enables new design paradigms that are not possible using spatial transforms, three of which are discussed here. First, spatially variant self-collimating photonic crystals are shown to flow unguided waves around very tight bends using ordinary materials with low refractive index. Second, multi-mode waveguides in spatially variant band gap materials are shown to guide waves around bends without mixing power between the modes. Third, spatially variant anisotropic materials are shown to sculpt the near-field around electric components. This can be used to improve electromagnetic compatibility between components in close proximity. PMID:26217058

  20. Filamentary magnetohydrodynamic plasmas

    NASA Astrophysics Data System (ADS)

    Kinney, R.; Tajima, T.; McWilliams, J. C.; Petviashvili, N.

    1994-02-01

    A filamentary construct of magnetohydrodynamical plasma dynamics based on the Elsässer variables is developed. This approach is modeled after discrete vortex models of hydrodynamical turbulence, which cannot be expected in general to produce results identical to those based on a Fourier decomposition of the fields. In a highly intermittent plasma, the induction force is small compared to the convective motion, and when this force is neglected, the plasma vortex system is described by a Hamiltonian. A statistical treatment of a collection of discrete current-vorticity concentrations is given. Canonical and microcanonical statistical calculations show that both the vorticity and the current spectra are peaked at long wavelengths, and the expected states revert to known hydrodynamical states as the magnetic field vanishes. These results differ from previous Fourier-based statistical theories, but it is found that when the filament calculation is expanded to include the inductive force, the results approach the Fourier equilibria in the low-temperature limit, and the previous Hamiltonian plasma vortex results in the high-temperature limit. Numerical simulations of a large number of filaments are carried out and support the theory. A three-dimensional vortex model is presented as well, which is also Hamiltonian when the inductive force is neglected. A statistical calculation in the canonical ensemble and numerical simulations show that a nonzero large-scale magnetic field is statistically favored, and that the preferred shape of this field is a long, thin tube of flux. Possible applications to a variety of physical phenomena are suggested.

  1. Vector resonances and electromagnetic nucleon structure

    SciTech Connect

    Robert Williams; Siegfried Krewald; Kevin Linen

    1995-02-01

    Motivated by new, precise magnetic proton form factor data in the timelike region, a hybrid vector meson dominance (hVMD) formalism is employed to investigate the significance of excited vector meson resonances on electromagnetic nucleon structure. We find that the rho (1700), omega (1600), and two previously unobserved states are required to reproduce the local structure seen in the new LEAR data just above the pp-bar threshold. We also investigate sensitivity to the phi meson. The model dependence of our result is tested by introducing an alternative model which couples the isoscalar vector meson states to a hypothetical vector glueball resonance. We obtain nearly identical results from both models, except for GnE(q2) in the spacelike region which is very sensitive to the glueball mass and the effective phi NN coupling.

  2. The identification of filaments on far-infrared and submillimiter images: Morphology, physical conditions and relation with star formation of filamentary structure

    SciTech Connect

    Schisano, E.; Carey, S.; Paladini, R.; Rygl, K. L. J.; Molinari, S.; Elia, D.; Pestalozzi, M.; Busquet, G.; Billot, N.; Noriega-Crespo, A.; Moore, T. J. T.; Plume, R.; Glover, S. C. O.; Vázquez-Semadeni, E.

    2014-08-10

    Observations of molecular clouds reveal a complex structure, with gas and dust often arranged in filamentary, rather than spherical geometries. The association of pre- and proto-stellar cores with the filaments suggests a direct link with the process of star formation. Any study of the properties of such filaments requires representative samples from different environments for an unbiased detection method. We developed such an approach using the Hessian matrix of a surface-brightness distribution to identify filaments and determine their physical and morphological properties. After testing the method on simulated, but realistic, filaments, we apply the algorithms to column-density maps computed from Herschel observations of the Galactic plane obtained by the Hi-GAL project. We identified ∼500 filaments, in the longitude range of l = 216.°5 to l = 225.°5, with lengths from ∼1 pc up to ∼30 pc and widths between 0.1 pc and 2.5 pc. Average column densities are between 10{sup 20} cm{sup –2} and 10{sup 22} cm{sup –2}. Filaments include the majority of dense material with N{sub H{sub 2}} > 6 × 10{sup 21} cm{sup –2}. We find that the pre- and proto-stellar compact sources already identified in the same region are mostly associated with filaments. However, surface densities in excess of the expected critical values for high-mass star formation are only found on the filaments, indicating that these structures are necessary to channel material into the clumps. Furthermore, we analyze the gravitational stability of filaments and discuss their relationship with star formation.

  3. Planck intermediate results. XXXVIII. E- and B-modes of dust polarization from the magnetized filamentary structure of the interstellar medium

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bracco, A.; Burigana, C.; Calabrese, E.; Cardoso, J.-F.; Catalano, A.; Chamballu, A.; Chary, R.-R.; Chiang, H. C.; Christensen, P. R.; Colombo, L. P. L.; Combet, C.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Dunkley, J.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Ferrière, K.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frolov, A.; Galeotta, S.; Galli, S.; Ganga, K.; Ghosh, T.; Giard, M.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gruppuso, A.; Guillet, V.; Hansen, F. K.; Harrison, D. L.; Helou, G.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hornstrup, A.; Hovest, W.; Huang, Z.; Huffenberger, K. M.; Hurier, G.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Leonardi, R.; León-Tavares, J.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Maino, D.; Mandolesi, N.; Maris, M.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; McGehee, P.; Melchiorri, A.; Mennella, A.; Migliaccio, M.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Novikov, D.; Novikov, I.; Oppermann, N.; Oxborrow, C. A.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Perdereau, O.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Pratt, G. W.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Serra, P.; Soler, J. D.; Stolyarov, V.; Sudiwala, R.; Sunyaev, R.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L. A.; Wandelt, B. D.; Wehus, I. K.; Yvon, D.; Zacchei, A.; Zonca, A.

    2016-02-01

    The quest for a B-mode imprint from primordial gravity waves on the polarization of the cosmic microwave background (CMB) requires the characterization of foreground polarization from Galactic dust. We present a statistical study of the filamentary structure of the 353 GHz Planck Stokes maps at high Galactic latitude, relevant to the study of dust emission as a polarized foreground to the CMB. We filter the intensity and polarization maps to isolate filaments in the range of angular scales where the power asymmetry between E-modes and B-modes is observed. Using the Smoothed Hessian Major Axis Filament Finder (SMAFF), we identify 259 filaments at high Galactic latitude, with lengths larger or equal to 2° (corresponding to 3.5 pc in length for a typical distance of 100 pc). Thesefilaments show a preferred orientation parallel to the magnetic field projected onto the plane of the sky, derived from their polarization angles. We present mean maps of the filaments in Stokes I, Q, U, E, and B, computed by stacking individual images rotated to align the orientations of the filaments. Combining the stacked images and the histogram of relative orientations, we estimate the mean polarization fraction of the filaments to be 11%. Furthermore, we show that the correlation between the filaments and the magnetic field orientations may account for the E and B asymmetry and the CℓTE/CℓEE ratio, reported in the power spectra analysis of the Planck353 GHz polarization maps. Future models of the dust foreground for CMB polarization studies will need to take into account the observed correlation between the dust polarization and the structure of interstellar matter.

  4. The Identification of Filaments on Far-infrared and Submillimiter Images: Morphology, Physical Conditions and Relation with Star Formation of Filamentary Structure

    NASA Astrophysics Data System (ADS)

    Schisano, E.; Rygl, K. L. J.; Molinari, S.; Busquet, G.; Elia, D.; Pestalozzi, M.; Polychroni, D.; Billot, N.; Carey, S.; Paladini, R.; Noriega-Crespo, A.; Moore, T. J. T.; Plume, R.; Glover, S. C. O.; Vázquez-Semadeni, E.

    2014-08-01

    Observations of molecular clouds reveal a complex structure, with gas and dust often arranged in filamentary, rather than spherical geometries. The association of pre- and proto-stellar cores with the filaments suggests a direct link with the process of star formation. Any study of the properties of such filaments requires representative samples from different environments for an unbiased detection method. We developed such an approach using the Hessian matrix of a surface-brightness distribution to identify filaments and determine their physical and morphological properties. After testing the method on simulated, but realistic, filaments, we apply the algorithms to column-density maps computed from Herschel observations of the Galactic plane obtained by the Hi-GAL project. We identified ~500 filaments, in the longitude range of l = 216.°5 to l = 225.°5, with lengths from ~1 pc up to ~30 pc and widths between 0.1 pc and 2.5 pc. Average column densities are between 1020 cm-2 and 1022 cm-2. Filaments include the majority of dense material with N_H_{2} > 6 × 1021 cm-2. We find that the pre- and proto-stellar compact sources already identified in the same region are mostly associated with filaments. However, surface densities in excess of the expected critical values for high-mass star formation are only found on the filaments, indicating that these structures are necessary to channel material into the clumps. Furthermore, we analyze the gravitational stability of filaments and discuss their relationship with star formation.

  5. FILAMENTARY LARGE-SCALE STRUCTURE TRACED BY SIX Ly{alpha} BLOBS AT z = 2.3

    SciTech Connect

    Erb, Dawn K.; Bogosavljevic, Milan; Steidel, Charles C.

    2011-10-10

    Extended nebulae of Ly{alpha} emission ('Ly{alpha} blobs') are known to be associated with overdense regions at high redshift. Here we present six large Ly{alpha} blobs in a previously known protocluster with galaxy overdensity {delta} {approx} 7 at z = 2.3; this is the richest field of giant Ly{alpha} blobs detected to date. The blobs have linear sizes of {approx}> 100 kpc and Ly{alpha} luminosities of {approx}10{sup 43} erg s{sup -1}. The positions of the blobs define two linear filaments with an extent of at least 12 comoving Mpc; these filaments intersect at the center of one of the blobs. Measurement of the position angles of the blobs indicates that five of the six are aligned with these filaments to within {approx}10{sup 0}, suggesting a connection between the physical processes powering extended Ly{alpha} emission and those driving structure on larger scales.

  6. Formation of sub-ion scale filamentary force-free structures in the vicinity of reconnection region

    NASA Astrophysics Data System (ADS)

    Zelenyi, L. M.; Frank, A. G.; Artemyev, A. V.; Petrukovich, A. A.; Nakamura, R.

    2016-05-01

    In this paper we review the results of spacecraft observations of current sheets (CSs) of sub-ion spatial scales in the Earth’s magnetotail as well as experiments with these structures in laboratory devices. We demonstrate that such sub-ion CSs having a thickness less than the ion gyroradius are usually formed in the vicinity of the magnetic reconnection region and are supported by strong electron currents flowing along magnetic field lines. The magnetic field configuration of sub-ion CSs is close to the force-free configuration, with a strong shear magnetic field component in the CS central region. Spacecraft observations suggest that parallel electron currents are generated by electron beams (pronounced enhancement of the phase space density for electrons with small pitch angles and energies  ∼1–3 keV). We discuss several models describing such force-free sub-ion CSs.

  7. Electromagnetic scattering from three dimensional periodic structures

    NASA Astrophysics Data System (ADS)

    Barnes, Andrew L.

    We have developed a numerical method for solving electromagnetic scattering problems from arbitrary, smooth, three dimensional structures that are periodic in two directions and of finite thickness in the third direction. We solve Maxwell's equations via an integral equation that was first formulated by Claus Muller. The Muller integral equation is Fredholm of the second kind, so it is a well-posed problem. The original Muller formulation was for compact scatterers and it used a free space Green's function for the Helmholtz equation. We solve a periodic problem with a periodic Helmholtz Green's function. This Green's function has the same degree of singularity as the free space Helmholtz Green's function, but it is an infinite sum that converges very slowly. We use a resummation technique (due to P. P. Ewald) to perform an efficient calculation of the periodic Green's function. We solve the integral equation by a Galerkin method and use RWG vector basis functions to discretize surface currents on the scatterer. We perform a careful extraction of all singularities from the integrals that we compute. We use a triangular Gaussian quadrature method for calculation of the non-singular parts of the integrals. We analytically compute the remaining singular and nearly singular integrals. We also perform an acceleration technique that treats several frequencies simultaneously and leads to decreased computational times. In addition to the numerical code, we present an alternative way of looking at electromagnetic scattering in terms of Calderon projection operators. We have validated our computer code by comparing the numerical results with results from two separate cases. The first case is that of a flat dielectric slab of finite thickness, for which exact formulae are available. The second case is a periodic array of a row of infinite cylinders. In this case, we compare our results with those obtainedv from a two dimensional code developed by S. P. Shipman, S. Venakides

  8. Electromagnetic Structure of Few-Nucleon Systems: a Critical Review

    SciTech Connect

    R. Schiavilla

    2000-10-01

    Our current understanding of the structure of nuclei with up to A=8, including energy spectra, electromagnetic form factors, and capture reactions, is critically reviewed within the context of a realistic approach to nuclear dynamics based on two- and three-nucleon interactions and associated electromagnetic currents.

  9. Coupled structural/thermal/electromagnetic analysis/tailoring of graded composite structures

    NASA Technical Reports Server (NTRS)

    Mcknight, R. L.; Huang, H.; Hartle, M.

    1992-01-01

    Accomplishments are described for the third years effort of a 5-year program to develop a methodology for coupled structural/thermal/electromagnetic analysis/tailoring of graded composite structures. These accomplishments include: (1) structural analysis capability specialized for graded composite structures including large deformation and deformation position eigenanalysis technologies; (2) a thermal analyzer specialized for graded composite structures; (3) absorption of electromagnetic waves by graded composite structures; and (4) coupled structural thermal/electromagnetic analysis of graded composite structures.

  10. Statistical Behavior of Filamentary Plasmas

    NASA Astrophysics Data System (ADS)

    Kinney, Rodney Michael

    This work describes a study of plasmas with highly intermittent filamentary structures. A statistical model of two-dimensional magnetohydrodynamics is presented, based on a representation of the fluid as a collection of discrete current-vorticity concentrations. This approach is modeled after discrete vortex models of hydrodynamical turbulence, which cannot be expected in general to produce results identical to a theory based on a Fourier decomposition of the fields. In a highly intermittent plasma, the induction force is small compared to the convective motion, and when this force is neglected, the plasma vortex system is described by a Hamiltonian. Canonical and micro-canonical statistical calculations show that both the vorticity and the current may exhibit large-scale structure, and the expected states revert to known hydrodynamical states as the magnetic field vanishes. These results differ from previous Fourier-based statistical theories, but it is found that when the filament calculation is expanded to include the inductive force, the results approach the Fourier equilibria in the low -temperature limit, and the previous Hamiltonian plasma vortex results in the high-temperature limit. Numerical simulations of a large number of filaments are carried out and support the theory. A three-dimensional vortex model is outlined as well, which is also Hamiltonian when the inductive force is neglected. A statistical calculation in the canonical ensemble and numerical simulations show that a non-zero large-scale magnetic field is statistically favored, and that the preferred shape of this field is a long, thin tube of flux. In a tokamak, a stochastic magnetic field will give rise to strongly filamented current distributions. An external magnetic field possesses field lines described by a non-linear map, while current fluctuations along these field lines have a toroidal dependence which takes the same form as the time dependence of a system of hydrodynamical vortices

  11. Filamentary structure and Keplerian rotation in the high-mass star-forming region G35.03+0.35 imaged with ALMA

    NASA Astrophysics Data System (ADS)

    Beltrán, M. T.; Sánchez-Monge, Á.; Cesaroni, R.; Kumar, M. S. N.; Galli, D.; Walmsley, C. M.; Etoka, S.; Furuya, R. S.; Moscadelli, L.; Stanke, T.; van der Tak, F. F. S.; Vig, S.; Wang, K.-S.; Zinnecker, H.; Elia, D.; Schisano, E.

    2014-11-01

    Context. Theoretical scenarios propose that high-mass stars are formed by disk-mediated accretion. Aims: To test the theoretical predictions on the formation of massive stars, we wish to make a thorough study at high-angular resolution of the structure and kinematics of the dust and gas emission toward the high-mass star-forming region G35.03+0.35, which harbors a disk candidate around a B-type (proto)star. Methods: We carried out ALMA Cycle 0 observations at 870 μm of dust of typical high-density, molecular outflow, and cloud tracers with resolutions of < 0''&dotbelow;5. Complementary Subaru COMICS 25 μm observations were carried out to trace the mid-infrared emission toward this star-forming region. Results: The submillimeter continuum emission has revealed a filamentary structure fragmented into six cores, called A-F. The filament could be in quasi-equilibrium taking into account that the mass per unit length of the filament, 200-375 M⊙/pc, is similar to the critical mass of a thermally and turbulently supported infinite cylinder, ~335 M⊙/pc. The cores, which are on average separated by ~0.02 pc, have deconvolved sizes of 1300-3400 AU, temperatures of 35-240 K, H2 densities >107 cm -3, and masses in the range 1-5 M⊙, and they are subcritical. Core A, which is associated with a hypercompact Hii region and could be the driving source of the molecular outflow observed in the region, is the most chemically rich source in G35.03+0.35 with strong emission of typical hot core tracers such as CH3CN. Tracers of high density and excitation show a clear velocity gradient along the major axis of the core, which is consistent with a disk rotating about the axis of the associated outflow. The PV plots along the SE-NW direction of the velocity gradient show clear signatures of Keplerian rotation, although infall could also be present, and they are consistent with the pattern of an edge-on Keplerian disk rotating about a star with a mass in the range 5-13 M⊙. The high

  12. Algebraic structure of general electromagnetic fields and energy flow

    SciTech Connect

    Hacyan, Shahen

    2011-08-15

    Highlights: > Algebraic structure of general electromagnetic fields in stationary spacetime. > Eigenvalues and eigenvectors of the electomagnetic field tensor. > Energy-momentum in terms of eigenvectors and Killing vector. > Explicit form of reference frame with vanishing Poynting vector. > Application of formalism to Bessel beams. - Abstract: The algebraic structures of a general electromagnetic field and its energy-momentum tensor in a stationary space-time are analyzed. The explicit form of the reference frame in which the energy of the field appears at rest is obtained in terms of the eigenvectors of the electromagnetic tensor and the existing Killing vector. The case of a stationary electromagnetic field is also studied and a comparison is made with the standard short-wave approximation. The results can be applied to the general case of a structured light beams, in flat or curved spaces. Bessel beams are worked out as example.

  13. Understanding Io's Interior Structure from Electromagnetic Induction

    NASA Astrophysics Data System (ADS)

    Khurana, K. K.; Keszthelyi, L. P.; Jia, X.

    2015-12-01

    Io has long been suspected of a molten interior based on theoretical models of tidal dissipation in its interior. Extremely high temperature lava erupting on Io's surface would be consistent with an internal magma ocean but the highest reported eruption temperatures are questionable. Currently, the only direct evidence of a subsurface magma ocean in Io is the electromagnetic induction response observed by Galileo (Khurana et al. 2011, Science, 332, 1186). Using Jupiter's rotating magnetic field as a sounding signal, Khurana et al. (2011) provided evidence of a strong dipolar induction signature in Galileo's magnetometer data from four different flybys. They further showed that the signal is consistent with electromagnetic induction from large amounts of rock-melts in the asthenosphere of Io. Modeling showed that the induction response from a completely solid mantle model is inadequate to explain the magnetometer observations. However, a layer of asthenosphere >50 km in thickness with a melt fraction ≥20% is adequate to accurately match the observed magnetic field. Here we summarize our current knowledge of Io's interior from Galileo's induction measurements, and then outline a scheme to further infer properties of Io's interior, especially its internal temperature profile, by marrying the principles of thermodynamics with those of electromagnetism. In particular, we obtain guidance on stable mineral phases and their physical properties (such as density, melt state and electrical conductivity) from thermodynamic principles, whereas guidance on how the resulting internal conductivity profile affects the magnetic environment around Io is obtained from electromagnetic theory. We also explore how induction measurements can be obtained at multiple frequencies from a future mission and be used to constrain both the location and the thickness of the magma ocean. Finally, we explore the consequences of the global magma ocean on Io's physical properties such as the current

  14. Bisous model-Detecting filamentary patterns in point processes

    NASA Astrophysics Data System (ADS)

    Tempel, E.; Stoica, R. S.; Kipper, R.; Saar, E.

    2016-07-01

    The cosmic web is a highly complex geometrical pattern, with galaxy clusters at the intersection of filaments and filaments at the intersection of walls. Identifying and describing the filamentary network is not a trivial task due to the overwhelming complexity of the structure, its connectivity and the intrinsic hierarchical nature. To detect and quantify galactic filaments we use the Bisous model, which is a marked point process built to model multi-dimensional patterns. The Bisous filament finder works directly with the galaxy distribution data and the model intrinsically takes into account the connectivity of the filamentary network. The Bisous model generates the visit map (the probability to find a filament at a given point) together with the filament orientation field. Using these two fields, we can extract filament spines from the data. Together with this paper we publish the computer code for the Bisous model that is made available in GitHub. The Bisous filament finder has been successfully used in several cosmological applications and further development of the model will allow to detect the filamentary network also in photometric redshift surveys, using the full redshift posterior. We also want to encourage the astro-statistical community to use the model and to connect it with all other existing methods for filamentary pattern detection and characterisation.

  15. Filamentary and hierarchical pictures - Kinetic energy criterion

    NASA Technical Reports Server (NTRS)

    Klypin, Anatoly A.; Melott, Adrian L.

    1992-01-01

    We present a new criterion for formation of second-generation filaments. The criterion called the kinetic energy ratio, KR, is based on comparison of peculiar velocities at different scales. We suggest that the clumpiness of the distribution in some cases might be less important than the 'coldness' or 'hotness' of the flow for formation of coherent structures. The kinetic energy ratio is analogous to the Mach number except for one essential difference. If at some scale KR is greater than 1, as estimated at the linear stage, then when fluctuations of this scale reach nonlinearity, the objects they produce must be anisotropic ('filamentary'). In the case of power-law initial spectra the kinetic ratio criterion suggests that the border line is the power-spectrum with the slope n = -1.

  16. Reinforcement of metals with advanced filamentary composites

    NASA Technical Reports Server (NTRS)

    Herakovich, C. T.; Davis, J. G.; Dexter, H. B.

    1974-01-01

    This paper reviews some recent applications of the concept of reinforcing metal structures with advanced filamentary composites, and presents some results of an experimental investigation of the tensile behavior of aluminum and titanium reinforced with unidirectional boron/epoxy. Results are given for tubular and flat specimens, bonded at either room temperature or elevated temperature. The composite reinforced metals showed increased stiffness over the all-metal counterpart, as predicted by the rule of mixtures, and the results were independent of specimen geometry. The tensile strength of the born/epoxy reinforced metals is shown to be a function of the geometry of the test specimen and the method of bonding the composite to the metal.

  17. Computes Generalized Electromagnetic Interactions Between Structures

    SciTech Connect

    Johnson, William A.; Wilton, Donald R.

    2006-05-18

    Eiger is primarily in integral equation code for both frequency-domain electromagnetics and electrostatics. There is also some finiate element capability. In the frequency-domain version there are different Green's functions in the code, 2D, 3D free space, symmetry-plane Green's functions, periodic Green's functions, and layered media Green's functions. There are thin slot models for coupling into cavities. There is a thin wire algorithm as well as junction basis functions for attachment of a wire to a conducting surface. The code is written in Fortran 90 using object oriented design. The code has the capability to run both in parallel and serial modes. The code is a suite consisting of pre-processor (Jungfrau), the physics code (EIGER), and post processor (Moench).

  18. Computes Generalized Electromagnetic Interactions Between Structures

    Energy Science and Technology Software Center (ESTSC)

    2006-05-18

    Eiger is primarily in integral equation code for both frequency-domain electromagnetics and electrostatics. There is also some finiate element capability. In the frequency-domain version there are different Green's functions in the code, 2D, 3D free space, symmetry-plane Green's functions, periodic Green's functions, and layered media Green's functions. There are thin slot models for coupling into cavities. There is a thin wire algorithm as well as junction basis functions for attachment of a wire to amore » conducting surface. The code is written in Fortran 90 using object oriented design. The code has the capability to run both in parallel and serial modes. The code is a suite consisting of pre-processor (Jungfrau), the physics code (EIGER), and post processor (Moench).« less

  19. Some extensions of the concept of complementary electromagnetic structures

    NASA Astrophysics Data System (ADS)

    Popovic, B. D.; Nesic, A.

    1985-04-01

    Extensions of Booker's concept of complementary electromagnetic structures to some cases of inhomogeneous media are presented. Consideration is given to planar antennas and their complement/duals, in the presence of pairs of arbitrarily shaped dielectric and/or magnetic bodies of arbitrary complex permittivity and permeability, positioned symmetrically with respect to the antenna plane. It is shown that a simple correspondence exists between electromagnetic fields in complementary/dual systems. The extension of the concept of complementary structures to transmission lines with transversally inhomogeneous media is discussed and a number of new exact relations between quasi-static parameters of complementary coplanar transmission lines are derived.

  20. Nucleon Structure Studies with Electromagnetic Probes

    SciTech Connect

    Vineyard, Michael F.

    2011-03-31

    Summarized in this report is the progress achieved during the period from March 1, 2008 to June 14, 2009 under contract number DE-FG02-03ER41252. This is the final technical report under this contract. The experimental work described here is part of the electromagnetic nuclear physics program of the CEBAF Large Acceptance Spectrometer (CLAS) Collaboration at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) that published 17 journal articles during the period of this report. One of these journal articles reported on the results of precise measurements of the neutron magnetic form factor. I was a spokesperson on this experiment and the publication of these results is the culmination of years of effort by a small subset of the CLAS Collaboration. As usual, undergraduate students were involved in all aspects of this work. Three Union College students participated in this program during the window of this report and one presented a paper on his work at the 2009 National Conference on Undergraduate Research (NCUR22). In this report, I discuss recent progress on the measurements of the neutron magnetic form factor and describe my service work for the CLAS Collaboration.

  1. Algebraic Sub-Structuring for Electromagnetic Applications

    SciTech Connect

    Yang, C.; Gao, W.G.; Bai, Z.J.; Li, X.Y.S.; Lee, L.Q.; Husbands, P.; Ng, E.G.; /LBL, Berkeley /UC, Davis /SLAC

    2006-06-30

    Algebraic sub-structuring refers to the process of applying matrix reordering and partitioning algorithms to divide a large sparse matrix into smaller submatrices from which a subset of spectral components are extracted and combined to form approximate solutions to the original problem. In this paper, they show that algebraic sub-structuring can be effectively used to solve generalized eigenvalue problems arising from the finite element analysis of an accelerator structure.

  2. Algebraic sub-structuring for electromagnetic applications

    SciTech Connect

    Yang, Chao; Gao, Weiguo; Bai, Zhaojun; Li, Xiaoye; Lee, Lie-Quan; Husbands, Parry; Ng, Esmond G.

    2004-09-14

    Algebraic sub-structuring refers to the process of applying matrix reordering and partitioning algorithms to divide a large sparse matrix into smaller submatrices from which a subset of spectral components are extracted and combined to form approximate solutions to the original problem. In this paper, we show that algebraic sub-structuring can be effectively used to solve generalized eigenvalue problems arising from the finite element analysis of an accelerator structure.

  3. Coupled structural/thermal/electromagnetic analysis/tailoring of graded composite structures

    NASA Technical Reports Server (NTRS)

    Mcknight, R. L.; Huang, H.; Hartle, M.

    1992-01-01

    Accomplishments are described for the fourth years effort of a 5-year program to develop a methodology for coupled structural/thermal/electromagnetic analysis/tailoring of graded component structures. These accomplishments include: (1) demonstration of coupled solution capability; (2) alternate CSTEM electromagnetic technology; (3) CSTEM acoustic capability; (4) CSTEM tailoring; (5) CSTEM composite micromechanics using ICAN; and (6) multiple layer elements in CSTEM.

  4. FILAMENTARY STAR FORMATION: OBSERVING THE EVOLUTION TOWARD FLATTENED ENVELOPES

    SciTech Connect

    Lee, Katherine; Looney, Leslie; Johnstone, Doug; Tobin, John E-mail: lwl@illinois.edu E-mail: jtobin@nrao.edu

    2012-12-20

    Filamentary structures are ubiquitous from large-scale molecular clouds (a few parsecs) to small-scale circumstellar envelopes around Class 0 sources ({approx}1000 AU to {approx}0.1 pc). In particular, recent observations with the Herschel Space Observatory emphasize the importance of large-scale filaments (a few parsecs) and star formation. The small-scale flattened envelopes around Class 0 sources are reminiscent of the large-scale filaments. We propose an observationally derived scenario for filamentary star formation that describes the evolution of filaments as part of the process for formation of cores and circumstellar envelopes. If such a scenario is correct, small-scale filamentary structures (0.1 pc in length) with higher densities embedded in starless cores should exist, although to date almost all the interferometers have failed to observe such structures. We perform synthetic observations of filaments at the prestellar stage by modeling the known Class 0 flattened envelope in L1157 using both the Combined Array for Research in Millimeter-wave Astronomy (CARMA) and the Atacama Large Millimeter/Submillimeter Array (ALMA). We show that with reasonable estimates for the column density through the flattened envelope, the CARMA D array at 3 mm wavelengths is not able to detect such filamentary structure, so previous studies would not have detected them. However, the substructures may be detected with the CARMA D+E array at 3 mm and the CARMA E array at 1 mm as a result of more appropriate resolution and sensitivity. ALMA is also capable of detecting the substructures and showing the structures in detail compared to the CARMA results with its unprecedented sensitivity. Such detection will confirm the new proposed paradigm of non-spherical star formation.

  5. Planar electromagnetic metamaterial with a fish scale structure

    NASA Astrophysics Data System (ADS)

    Fedotov, V. A.; Mladyonov, P. L.; Prosvirnin, S. L.; Zheludev, N. I.

    2005-11-01

    We report on a continuous electromagnetic metal planar metamaterial, which resembles a “fish scale” structure. Apart from the one isolated wavelength, it is highly transparent to electromagnetic radiation throughout a broad spectral range and becomes completely “invisible” at some frequency inflicting no transmission losses and phase delay. When the structure is superimposed on a metallic mirror it becomes a good broadband reflector everywhere apart from one wavelength where the reflectivity is small. At this wavelength the reflected wave shows no phase change with respect to the incident wave, thus resembling a reflection from a hypothetical zero refractive index material, or “magnetic wall.” We also discovered that the structure acts as a local field concentrator and a resonant “amplifier” of losses in the underlying dielectric.

  6. Coupled structural/thermal/electromagnetic analysis/tailoring of graded composite structures

    NASA Technical Reports Server (NTRS)

    Mcknight, R. L.; Chen, P. C.; Dame, L. T.; Huang, H.

    1992-01-01

    Accomplishments are described for the first year effort of a 5-year program to develop a methodology for coupled structural/thermal/electromagnetic analysis/tailoring of graded composite structures. These accomplishments include: (1) the results of the selective literature survey; (2) 8-, 16-, and 20-noded isoparametric plate and shell elements; (3) large deformation structural analysis; (4) eigenanalysis; (5) anisotropic heat transfer analysis; and (6) anisotropic electromagnetic analysis.

  7. Detection of electromagnetic radiation using micromechanical multiple quantum wells structures

    DOEpatents

    Datskos, Panagiotis G [Knoxville, TN; Rajic, Slobodan [Knoxville, TN; Datskou, Irene [Knoxville, TN

    2007-07-17

    An apparatus and method for detecting electromagnetic radiation employs a deflectable micromechanical apparatus incorporating multiple quantum wells structures. When photons strike the quantum-well structure, physical stresses are created within the sensor, similar to a "bimetallic effect." The stresses cause the sensor to bend. The extent of deflection of the sensor can be measured through any of a variety of conventional means to provide a measurement of the photons striking the sensor. A large number of such sensors can be arranged in a two-dimensional array to provide imaging capability.

  8. Multifunctional composites and structures with integrated mechanical and electromagnetic properties

    NASA Astrophysics Data System (ADS)

    Amirkhizi, Alireza Vakil

    Composite materials are used for their excellent structural performance. Load-bearing properties are traditionally the only aspects for which a composite structure is designed. Recent technological advances have made it possible to reach beyond this limited view. Inspired by biological systems, we seek to develop engineering materials that exhibit multiple functionalities in addition to providing structural integrity. Composites are a natural host for embedding elements that can enhance their nonstructural response. The present work is focused on embedding periodic arrays of scattering elements within composites to modify and tune their overall electromagnetic properties. A number of techniques for numerical and analytical modeling of the periodic media are discussed. Based on these methods we have designed and fabricated composites with tuned electromagnetic properties. Examples include fiber-reinforced polymer composites with embedded arrays of straight wires or coils. In both cases, the overall dielectric constant of the medium is reduced and can even be rendered negative within microwave frequencies. The coil medium can exhibit chiral response. Solutions for eliminating this behavior as well as a method for calculation of the bianisotropic material parameters are presented. One can achieve similar response at higher frequencies by reducing the length scale. For example, we show that a polymer film with embedded nano-strips of gold can demonstrate negative dielectric constant in infrared regime. An example of a structural composite is presented for which the magnetic permeability is altered and is turned negative within a microwave band. Finally, a general method for homogenization of the electromagnetic properties of periodic media based on the microstructure is developed. Two independent chapters complete this dissertation. In Chapter 8 the response of a soft hypo-elastic material in a pressure---shear experiment is studied. A nonlinear pressure- and

  9. Structural evidence for electromagnetic resonance in plant morphogenesis.

    PubMed

    Pietak, Alexis Mari

    2012-09-01

    How a homogeneous collective of cells consistently and precisely establishes long-range tissue patterns remains a question of active research. This work explores the hypothesis of plant organs as resonators for electromagnetic radiation. Long-range structural patterns in the developing ovaries and male flower buds of cucurbit plants (zucchini, acorn, and butternut squash), in addition to mature cucurbit fruits (acorn, butternut, and zucchini squash; watermelon, and cucumber), were investigated. A finite element analysis (FEA) model was used to determine resonant EM modes for models with similar geometric and electrical parameters to those of developing organs. Main features of the developing ovaries (i.e. shape of placental lines, ovum location, definition of distinct tissue regions), male flower buds (i.e. early pollen tube features), and mature fruits (i.e. septa placement, seed location, endocarp and mesocarp) showed distinct correlations with electric and magnetic field components of electromagnetic resonant modes. On account of shared pattern signatures in developing organs and the EM resonant modes supported by a modelled structure with similar geometric and electrical properties to those of cucurbit organs, experimental investigations are warranted. The concept of a developing organ as an EM dielectric resonator may extend to a variety of morphogenetic phenomena in a number of living systems. PMID:22326259

  10. Process for application of powder particles to filamentary materials

    NASA Technical Reports Server (NTRS)

    Baucom, Robert M. (Inventor); Snoha, John J. (Inventor); Marchello, Joseph M. (Inventor)

    1991-01-01

    This invention is a process for the uniform application of polymer powder particles to a filamentary material in a continuous manner to form a uniform composite prepreg material. A tow of the filamentary material is fed under carefully controlled tension into a spreading unit, where it is spread pneumatically into an even band. The spread filamentary tow is then coated with polymer particles from a fluidized bed, after which the coated filamentary tow is fused before take-up on a package for subsequent utilization. This process produces a composite prepreg uniformly without imposing severe stress on the filamentary material, and without requiring long, high temperature residence times for the polymer.

  11. Identification of subsurface structures using electromagnetic data and shape priors

    SciTech Connect

    Tveit, Svenn; Bakr, Shaaban A.; Lien, Martha; Mannseth, Trond

    2015-03-01

    We consider the inverse problem of identifying large-scale subsurface structures using the controlled source electromagnetic method. To identify structures in the subsurface where the contrast in electric conductivity can be small, regularization is needed to bias the solution towards preserving structural information. We propose to combine two approaches for regularization of the inverse problem. In the first approach we utilize a model-based, reduced, composite representation of the electric conductivity that is highly flexible, even for a moderate number of degrees of freedom. With a low number of parameters, the inverse problem is efficiently solved using a standard, second-order gradient-based optimization algorithm. Further regularization is obtained using structural prior information, available, e.g., from interpreted seismic data. The reduced conductivity representation is suitable for incorporation of structural prior information. Such prior information cannot, however, be accurately modeled with a gaussian distribution. To alleviate this, we incorporate the structural information using shape priors. The shape prior technique requires the choice of kernel function, which is application dependent. We argue for using the conditionally positive definite kernel which is shown to have computational advantages over the commonly applied gaussian kernel for our problem. Numerical experiments on various test cases show that the methodology is able to identify fairly complex subsurface electric conductivity distributions while preserving structural prior information during the inversion.

  12. Green's Function Analysis of Periodic Structures in Computational Electromagnetics

    NASA Astrophysics Data System (ADS)

    Van Orden, Derek

    2011-12-01

    Periodic structures are used widely in electromagnetic devices, including filters, waveguiding structures, and antennas. Their electromagnetic properties may be analyzed computationally by solving an integral equation, in which an unknown equivalent current distribution in a single unit cell is convolved with a periodic Green's function that accounts for the system's boundary conditions. Fast computation of the periodic Green's function is therefore essential to achieve high accuracy solutions of complicated periodic structures, including analysis of modal wave propagation and scattering from external sources. This dissertation first presents alternative spectral representations of the periodic Green's function of the Helmholtz equation for cases of linear periodic systems in 2D and 3D free space and near planarly layered media. Although there exist multiple representations of the periodic Green's function, most are not efficient in the important case where the fields are observed near the array axis. We present spectral-spatial representations for rapid calculation of the periodic Green's functions for linear periodic arrays of current sources residing in free space as well as near a planarly layered medium. They are based on the integral expansion of the periodic Green's functions in terms of the spectral parameters transverse to the array axis. These schemes are important for the rapid computation of the interaction among unit cells of a periodic array, and, by extension, the complex dispersion relations of guided waves. Extensions of this approach to planar periodic structures are discussed. With these computation tools established, we study the traveling wave properties of linear resonant arrays placed near surfaces, and examine the coupling mechanisms that lead to radiation into guided waves supported by the surface. This behavior is especially important to understand the properties of periodic structures printed on dielectric substrates, such as periodic

  13. Integrated structure electromagnetic optimization of large space antenna reflectors

    NASA Technical Reports Server (NTRS)

    Padula, Sharon L.; Adelman, Howard M.; Bailey, M. C.

    1987-01-01

    The requirements for extremely precise and powerful large space antenna reflectors have motivated the development of a procedure for shape control of the reflector surface. A mathematical optimization procedure has been developed which improves antenna performance while minimizing necessary shape correction effort. In contrast to previous work which proposed controlling the rms distortion error of the surface thereby indirectly improving antenna performance, the current work includes electromagnetic (EM) performance calculations as an integral of the control procedure. The application of the procedure to a radiometer design with a tetrahedral truss backup structure demonstrates the potential for significant improvement. The results indicate the benefit of including EM performance calculations in procedures for shape control of large space antenna reflectors.

  14. S4 : A free electromagnetic solver for layered periodic structures

    NASA Astrophysics Data System (ADS)

    Liu, Victor; Fan, Shanhui

    2012-10-01

    We describe S4, a free implementation of the Fourier modal method (FMM), which has also been commonly referred to as rigorous coupled wave analysis (RCWA), for simulating electromagnetic propagation through 3D structures with 2D periodicity. We detail design aspects that allow S4 to be a flexible platform for these types of simulations. In particular, we highlight the ability to select different FMM formulations, user scripting, and extensibility of program capabilities for eigenmode computations. Program summary Program title: S4 Catalogue identifier: AEMO_v1_0. Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEMO_v1_0..html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License, version 2 No. of lines in distributed program, including test data, etc.: 56910 No. of bytes in distributed program, including test data, etc.: 433883 Distribution format: Programming language: C, C++. Computer: Any computer with a Unix-like environment and a C++ compiler. Developed on 2.3 GHz AMD Phenom 9600. Operating system: Any Unix-like environment; developed under MinGW32 on Windows 7. Has the code been vectorized or parallelized?: Yes. Parallelized using MPI. RAM: Problem dependent (linearly proportional to number of layers and quadratic in number of Fourier components). A single layer calculation with approximately 100 Fourier components uses approximately 10 MB. Classification: 10. Electrostatics and Electromagnetics. External routines: Lua [1] and optionally exploits additional free software packages: FFTW [2], CHOLMOD [3], MPI message-passing interface [4], LAPACK and BLAS linear-algebra software [5], and Kiss FFT [6]. Nature of problem: Time-harmonic electromagnetism in layered bi-periodic structures. Solution method: The Fourier modal method (rigorous coupled wave analysis) and the scattering matrix method. Running time: Problem dependent and highly dependent on quality of the BLAS

  15. Assembly of filamentary void galaxy configurations

    NASA Astrophysics Data System (ADS)

    Rieder, Steven; van de Weygaert, Rien; Cautun, Marius; Beygu, Burcu; Portegies Zwart, Simon

    2013-10-01

    We study the formation and evolution of filamentary configurations of dark matter haloes in voids. Our investigation uses the high-resolution Λ cold dark matter simulation CosmoGrid to look for void systems resembling the VGS_31 elongated system of three interacting galaxies that was recently discovered by the Void Galaxy Survey inside a large void in the Sloan Digital Sky Survey galaxy redshift survey. H I data revealed these galaxies to be embedded in a common elongated envelope, possibly embedded in intravoid filament. In the CosmoGrid simulation we look for systems similar to VGS_31 in mass, size and environment. We find a total of eight such systems. For these systems, we study the distribution of neighbour haloes, the assembly and evolution of the main haloes and the dynamical evolution of the haloes, as well as the evolution of the large-scale structure in which the systems are embedded. The spatial distribution of the haloes follows that of the dark matter environment. We find that VGS_31-like systems have a large variation in formation time, having formed between 10 Gyr ago and the present epoch. However, the environments in which the systems are embedded evolved to resemble each other substantially. Each of the VGS_31-like systems is embedded in an intravoid wall, that no later than z = 0.5 became the only prominent feature in its environment. While part of the void walls retain a rather featureless character, we find that around half of them are marked by a pronounced and rapidly evolving substructure. Five haloes find themselves in a tenuous filament of a few h-1 Mpc long inside the intravoid wall. Finally, we compare the results to observed data from VGS_31. Our study implies that the VGS_31 galaxies formed in the same (proto)filament, and did not meet just recently. The diversity amongst the simulated halo systems indicates that VGS_31 may not be typical for groups of galaxies in voids.

  16. Electromagnetic response of buried cylindrical structures for line current excitation

    NASA Astrophysics Data System (ADS)

    Pajewski, Lara; Ponti, Cristina

    2013-04-01

    arbitrary arrangements of cylinders in the soil. As future work, the presented analysis, carried out in the spectral domain, will be extended to a time-domain solution following an approach analogous to the one developed in [6] for pulsed plane-wave excitation. [1] M. Di Vico, F. Frezza, L. Pajewski, and G. Schettini, "Scattering by a Finite Set of Perfectly Conducting Cylinders Buried in a Dielectric Half-Space: a Spectral-Domain Solution," IEEE Transactions Antennas and Propagation, vol. 53(2), 719-727, 2005. [2] M. Di Vico, F. Frezza, L. Pajewski, and G. Schettini, "Scattering by Buried Dielectric Cylindrical Structures," Radio Science, vol. 40(6), RS6S18, 2005. [3] F. Frezza, L. Pajewski, C. Ponti, and G. Schettini, "Scattering by Perfectly-Conducting Cylinders Buried in a Dielectric Slab through the Cylindrical Wave Approach," IEEE Transactions Antennas and Propagation, vol. 57(4), 1208-1217, 2009. [4] F. Frezza, L. Pajewski, C. Ponti, and G. Schettini, "Accurate Wire-Grid Modeling of Buried Conducting Cylindrical Scatterers," Nondestructive Testing and Evaluation (Special Issue on "Civil Engineering Applications of Ground Penetrating Radar"), vol. 27(3), pp. 199-207, 2012. [5] F. Frezza, L. Pajewski, C. Ponti, G. Schettini, and N. Tedeschi, "Electromagnetic Scattering by a Metallic Cylinder Buried in a Lossy Medium with the Cylindrical Wave Approach," IEEE Geoscience and Remote Sensing Letters, vol. 10(1), pp. 179-183, 2013. [6] F. Frezza, P. Martinelli, L. Pajewski, and G. Schettini, "Short-Pulse Electromagnetic Scattering from Buried Perfectly-Conducting Cylinders," IEEE Geoscience and Remote Sensing Letters, vol. 4(4), pp. 611-615, 2007.

  17. Structural and functional polymer-matrix composites for electromagnetic applications

    NASA Astrophysics Data System (ADS)

    Wu, Junhua

    This dissertation addresses the science and technology of functional and structural polymer-matrix composite materials for electromagnetic applications, which include electromagnetic interference (EMI) shielding and low observability (Stealth). The structural composites are continuous carbon fiber epoxy-matrix composites, which are widely used for airframes. The functional composites are composites with discontinuous fillers and in both bulk and coating forms. Through composite structure variation, attractive electromagnetic properties have been achieved. With no degradation of the tensile strength or modulus, the shielding effectiveness of the structural composites has been improved by enhancing multiple reflections through light activation of the carbon fiber. The multiple reflections loss of the electromagnetic wave increases from 1.1 to 10.2 dB at 1.0 GHz due to the activation. Such a large effect of multiple reflections has not been previously reported in any material. The observability of these composites has been lowered by decreasing the electrical conductivity (and hence decreasing the reflection loss) through carbon fiber coating. The incorporation of mumetal, a magnetic alloy particulate filler (28-40 mum size), in a latex paint has been found to be effective for enhancing the shielding only if the electrical resistivity of the resulting composite coating is below 10 O.cm, as rendered by a conductive particulate filler, such as nickel flake (14-20 mum size). This effectiveness (39 dB at 1.0 GHz) is attributed to the absorption of the electromagnetic wave by the mumetal and the nickel flake, with the high conductivity rendered by the presence of the nickel flake resulting in a relatively high reflection loss of 15.5 dB. Without the nickel flake, the mumetal gives only 3 dB of shielding and 1.5 dB of reflection loss at 1.0 GHz. Nickel powder (0.3-0.5 mum size) has been found to be an effective filler for improving the shielding of polyethersulfone (PES

  18. Structural and functional polymer-matrix composites for electromagnetic applications

    NASA Astrophysics Data System (ADS)

    Wu, Junhua

    This dissertation addresses the science and technology of functional and structural polymer-matrix composite materials for electromagnetic applications, which include electromagnetic interference (EMI) shielding and low observability (Stealth). The structural composites are continuous carbon fiber epoxy-matrix composites, which are widely used for airframes. The functional composites are composites with discontinuous fillers and in both bulk and coating forms. Through composite structure variation, attractive electromagnetic properties have been achieved. With no degradation of the tensile strength or modulus, the shielding effectiveness of the structural composites has been improved by enhancing multiple reflections through light activation of the carbon fiber. The multiple reflections loss of the electromagnetic wave increases from 1.1 to 10.2 dB at 1.0 GHz due to the activation. Such a large effect of multiple reflections has not been previously reported in any material. The observability of these composites has been lowered by decreasing the electrical conductivity (and hence decreasing the reflection loss) through carbon fiber coating. The incorporation of mumetal, a magnetic alloy particulate filler (28-40 mum size), in a latex paint has been found to be effective for enhancing the shielding only if the electrical resistivity of the resulting composite coating is below 10 O.cm, as rendered by a conductive particulate filler, such as nickel flake (14-20 mum size). This effectiveness (39 dB at 1.0 GHz) is attributed to the absorption of the electromagnetic wave by the mumetal and the nickel flake, with the high conductivity rendered by the presence of the nickel flake resulting in a relatively high reflection loss of 15.5 dB. Without the nickel flake, the mumetal gives only 3 dB of shielding and 1.5 dB of reflection loss at 1.0 GHz. Nickel powder (0.3-0.5 mum size) has been found to be an effective filler for improving the shielding of polyethersulfone (PES

  19. Numerical studies of filamentary plasma formation in high power millimeter wave field

    NASA Astrophysics Data System (ADS)

    Takeichi, Tensei; Yamaguchi, Toshikazu; Fukunari, Masafumi; Koizumi, Hiroyuki; Komurasaki, Kimiya; Arakawa, Yoshihiro

    2012-10-01

    Filamentary structure characterizes millimeter-wave discharge in air and the ionization front propagates at supersonic speed in a high power millimeter-wave, generating a shock wave. In this study, the filamentary structure was studied experimentally and analytically using a 170GHz Gyrotron at the peak intensity range of 50 kW/cm^2 to 200kW/cm^2. On the propagation process of ionization front, it is important to investigate steady plasma formation process in a filamentary form through millimeter wave. Each filamentary element observed in the ionization front propagates not along or perpendicular to the electric field, but obliquely. To solve this mechanism, 2-dimensional numerical analysis was conducted assuming this phenomenon as a plasma fluid model. In dozens of times the size of plasma element scale, the steady plasma structure formation was simulated, and the calculation was compared with previous experimental results. The calculated formation patterns were in good qualitative agreement with experiments. The calculation model provides a physical interpretation of the pattern formation and dynamics. From the interpretation, it was found that accurate ionization model in low electric field is needed for good agreement with experiments. Moreover, for a quantitative agreement, not only the ionization model but also consideration of 3-dimensional effects are necessary, since 2-dimensional simulation cannot estimate accurate wave reflection and interaction by plasma.

  20. Electromagnetic structure of few-nucleon ground states

    DOE PAGESBeta

    Marcucci, Laura E.; Istituto Nazionale di Fisica Nucleare; Gross, Franz L.; Thomas Jefferson National Accelerator Facility; Peña, M. T.; Piarulli, M.; Old Dominion Univ., Norfolk, VA; Schiavilla, Rocco; Old Dominion Univ., Norfolk, VA; Sick, Ingo; et al

    2016-01-08

    Experimental form factors of the hydrogen and helium isotopes, extracted from an up-to-date global analysis of cross sections and polarization observables measured in elastic electron scattering from these systems, are compared to predictions obtained in three different theoretical approaches: the first is based on realistic interactions and currents, including relativistic corrections (labeled as the conventional approach); the second relies on a chiral effective field theory description of the strong and electromagnetic interactions in nuclei (labeled ChiEFT); the third utilizes a fully relativistic treatment of nuclear dynamics as implemented in the covariant spectator theory (labeled CST). Furthermore, for momentum transfers belowmore » Q < 5 fm-1 there is satisfactory agreement between experimental data and theoretical results in all three approaches. Conversely, at Q > 5 fm-1, particularly in the case of the deuteron, a relativistic treatment of the dynamics, as is done in the CST, is necessary. The experimental data on the deuteron A structure function extend to Q ~ 12 fm-1, and the close agreement between these data and the CST results suggests that, even in this extreme kinematical regime, there is no evidence for new effects coming from quark and gluon degrees of freedom at short distances.« less

  1. Miniaturization of electromagnetic band gap structures for mobile applications

    NASA Astrophysics Data System (ADS)

    Goussetis, G.; Feresidis, A. P.; Palikaras, G. K.; Kitra, M.; Vardaxoglou, J. C.

    2005-12-01

    It is well known that interference of the human body affects the performance of the antennas in mobile phone handsets. In this contribution, we investigate the use of miniaturized metallodielectric electromagnetic band gap (MEBG) structures embedded in the case of a mobile handset as a means of decoupling the antenna from the user's hand. The closely coupled MEBG concept is employed to achieve miniaturization of the order of 15:1. Full wave dispersion relations for planar closely coupled MEBG arrays are presented and are validated experimentally. The performance of a prototype handset with an embedded conformal MEBG is assessed experimentally and is compared to a similar prototype without the MEBG. Reduction in the detuning of the antenna because of the human hand by virtue of the MEBG is demonstrated. Moreover, the efficiency of the handset when loaded with a human hand model is shown to improve when the MEBG is in place. The improvements are attributed to the decoupling of the antenna from the user's hand, which is achieved by means of suppressing the fields in the locality of the hand.

  2. Space-time structure of weak and electromagnetic interactions

    SciTech Connect

    Hestenes, D.

    1982-02-01

    The generator of electromagnetic gauge transformations in the Dirac equation has a unique geometric interpretation and a unique extension to the generators of the gauge group SU(2) x U(1) for the Weinberg--Salam theory of weak and electromagnetic interactions. It follows that internal symmetries of the weak interactions can be interpreted as space-time symmetries of spinor fields in the Dirac algebra. The possibilities for interpreting strong interaction symmetries in a similar way are highly restricted.

  3. [Electromagnetic studies of nuclear structure and reactions]. Progress summary

    SciTech Connect

    Not Available

    1992-12-31

    The experimental goals are focused on developing an understanding of strong interactions and the structure of hadronic systems by determination of the electromagnetic response; these goals will be accomplished through coincidence detection of final states. Nuclear modeling objectives are to organize and interpret the data through a consistent description of a broad spectrum of reaction observables; calculations are performed in a nonrelativistic diagrammatic framework as well as a relativistic QHD approach. Work is described according to the following arrangement: direct knockout reactions (completion of {sup 16}O(e,e{prime}p), {sup 12}C(e,e{prime}pp) progress, large acceptance detector physics simulations), giant resonance studies (intermediate-energy experiments with solid-state detectors, the third response function in {sup 12}C(e,e{prime}p{sub 0}) and {sup 16}O(e,e{prime}p{sub 0}), comparison of the {sup 12}C(e, e{prime}p{sub 0}) and {sup 16}O(e,e{prime}p{sub 3}) reactions, quadrupole strength in the {sup 16}O(e,e{prime}{alpha}{sub 0}) reaction, quadrupole strength in the {sup 12}C(e,e{prime}{alpha}) reaction, analysis of the {sup 12}C(e,e{prime}p{sub 1}) and {sup 16}O(e,e{prime}p{sub 3}) angular distributions, analysis of the {sup 40}Ca(e,e{prime}x) reaction at low q, analysis of the higher-q {sup 12}C(e,e{prime}x) data from Bates), models of nuclear structure (experimental work, Hartree-Fock calculations, phonon excitations in spherical nuclei, shell model calculations, variational methods for relativistic fields), and instrumentation development efforts (developments at CEBAF, CLAS contracts, BLAST developments).

  4. Geometric algorithms for electromagnetic modeling of large scale structures

    NASA Astrophysics Data System (ADS)

    Pingenot, James

    With the rapid increase in the speed and complexity of integrated circuit designs, 3D full wave and time domain simulation of chip, package, and board systems becomes more and more important for the engineering of modern designs. Much effort has been applied to the problem of electromagnetic (EM) simulation of such systems in recent years. Major advances in boundary element EM simulations have led to O(n log n) simulations using iterative methods and advanced Fast. Fourier Transform (FFT), Multi-Level Fast Multi-pole Methods (MLFMM), and low-rank matrix compression techniques. These advances have been augmented with an explosion of multi-core and distributed computing technologies, however, realization of the full scale of these capabilities has been hindered by cumbersome and inefficient geometric processing. Anecdotal evidence from industry suggests that users may spend around 80% of turn-around time manipulating the geometric model and mesh. This dissertation addresses this problem by developing fast and efficient data structures and algorithms for 3D modeling of chips, packages, and boards. The methods proposed here harness the regular, layered 2D nature of the models (often referred to as "2.5D") to optimize these systems for large geometries. First, an architecture is developed for efficient storage and manipulation of 2.5D models. The architecture gives special attention to native representation of structures across various input models and special issues particular to 3D modeling. The 2.5D structure is then used to optimize the mesh systems First, circuit/EM co-simulation techniques are extended to provide electrical connectivity between objects. This concept is used to connect independently meshed layers, allowing simple and efficient 2D mesh algorithms to be used in creating a 3D mesh. Here, adaptive meshing is used to ensure that the mesh accurately models the physical unknowns (current and charge). Utilizing the regularized nature of 2.5D objects and

  5. Marine electromagnetic constraints on lithosphere/asthenosphere structure

    NASA Astrophysics Data System (ADS)

    Constable, Steven; Key, Kerry; Naif, Samer

    2014-05-01

    Marine controlled-source electromagnetic (CSEM) experiments long ago showed that the oceanic lithosphere is highly resistive, but deeper, conductive asthenospheric structure is beyond the resolution of this method. The development of a "broadband" marine magnetotelluric (MT) instrument allowed deepwater MT data collection down to about 20 second periods, overlapping in sensitivity with CSEM data and capturing the peak sensitivity of the asthenosphere in MT data at around 100 seconds. In two end-member experiments, one at the Pacific mid-ocean ridge at 9.5 degrees north, and one where the same, now 23 Ma, Cocos plate subducts beneath Nicaragua, we carried out joint CSEM and broadband MT data collection. At the mid-ocean ridge, symmetric melting above the wet solidus is consistent with passive upwelling of hydrated mantle. Deeper, carbonate-induced melting shows asymmetry that is consistent with upwelling due to viscous coupling across the nearby Clipperton transform offset. At 100 km off-axis, a 70 km thick resistive layer is consistent with melt-depleted lithosphere and asthenosphere. By the time the plate has migrated to the subduction zone, an anisotropic and conductive asthenosphere 25 km thick has developed at a depth of 45-70 km, again inferred to be melting of hydrated mantle. The nature of the anisotropy is consistent with shearing and alignment in the plate motion direction, suggesting viscous decoupling of the lithosphere and asthenosphere. We observe conductivities consistent with a smaller fraction of isotropic melt in the deeper mantle, suggesting that the melt at the lithosphere-asthenosphere boundary (LAB) is a result of upward migrating melt accumulating beneath a thermal and/or dehydration boundary. At both the ridge and subduction zone we estimate several hundred ppm water in the mantle, but this is dependent on laboratory data and any additional impact from carbon dioxide on the solidus.

  6. Coupled structural/thermal/electromagnetic analysis/tailoring of graded composite structures

    NASA Astrophysics Data System (ADS)

    Hartle, M. S.; McKnight, R. L.; Huang, H.; Holt, R.

    1992-04-01

    Described here are the accomplishments of a 5-year program to develop a methodology for coupled structural, thermal, electromagnetic analysis tailoring of graded component structures. The capabilities developed over the course of the program are the analyzer module and the tailoring module for the modeling of graded materials. Highlighted accomplishments for the past year include the addition of a buckling analysis capability, the addition of mode shape slope calculation for flutter analysis, verification of the analysis modules using simulated components, and verification of the tailoring module.

  7. Coupled structural/thermal/electromagnetic analysis/tailoring of graded composite structures

    NASA Technical Reports Server (NTRS)

    Hartle, M. S.; Mcknight, R. L.; Huang, H.; Holt, R.

    1992-01-01

    Described here are the accomplishments of a 5-year program to develop a methodology for coupled structural, thermal, electromagnetic analysis tailoring of graded component structures. The capabilities developed over the course of the program are the analyzer module and the tailoring module for the modeling of graded materials. Highlighted accomplishments for the past year include the addition of a buckling analysis capability, the addition of mode shape slope calculation for flutter analysis, verification of the analysis modules using simulated components, and verification of the tailoring module.

  8. Low dielectric electromagnetic absorbing material in 18-40 GHz using large scale photonic crystal structures

    NASA Astrophysics Data System (ADS)

    Narita, T.; Matsumura, K.; Kagawa, Y.

    2007-02-01

    The interaction behavior between a monolithic low dielectric block with unidirectionally aligned through holes and an electromagnetic wave at a frequency range from 18to40GHz has been studied. Hexagonally aligned through holes, whose diameters are 8.0, 9.0, and 10.0mm, are introduced to a polymethylmethacrylate block. The electromagnetic wave reflection and transmission spectra perpendicular to the hole axis show a unique structure dependence, which is related to the diameter of the hole and its arrangement. A large decrease in the reflectance and transmittance appears in the spectra, which originates from the interference effect between the electromagnetic wave and material. It is concluded that the material has a potential for controlling the electromagnetic wave at a tailored target frequency and is expected to be usable as monolithic low dielectric electromagnetic wave absorbing material.

  9. Interacting filamentary eruptions in magnetised plasmas

    NASA Astrophysics Data System (ADS)

    Henneberg, S. A.; Cowley, S. C.; Wilson, H. R.

    2015-12-01

    The interaction between multiple filamentary plasma eruptions is investigated by modelling the non-linear ideal MHD ballooning mode envelope equation with a mixed Eulerian and Lagrangian characterisation of the boundary conditions. The study of multiple plasma filaments is performed in a specific slab equilibrium susceptible to Rayleigh-Taylor instabilities. If the unstable system is initiated with three equal sized filaments, they erupt at the same rate, independently of each other, even in the non-linear regime. However, if one is initiated very slightly larger than the other two it causes a down-draft as it erupts upwards, which suppresses the smaller filaments. This suggests that those filaments which first enter the non-linear regime will dominate the plasma eruption dynamics.

  10. Fast wave evanescence in filamentary boundary plasmas

    SciTech Connect

    Myra, J. R.

    2014-02-15

    Radio frequency waves for heating and current drive of plasmas in tokamaks and other magnetic confinement devices must first traverse the scrape-off-layer (SOL) before they can be put to their intended use. The SOL plasma is strongly turbulent and intermittent in space and time. These turbulent properties of the SOL, which are not routinely taken into account in wave propagation codes, can have an important effect on the coupling of waves through an evanescent SOL or edge plasma region. The effective scale length for fast wave (FW) evanescence in the presence of short-scale field-aligned filamentary plasma turbulence is addressed in this paper. It is shown that although the FW wavelength or evanescent scale length is long compared with the dimensions of the turbulence, the FW does not simply average over the turbulent density; rather, the average is over the exponentiation rate. Implications for practical situations are discussed.

  11. Evaluation of a metal fuselage panel selectively reinforced with filamentary composites for space shuttle application

    NASA Technical Reports Server (NTRS)

    Wennhold, W. F.

    1974-01-01

    The use of high strength and modulus of advanced filamentary composites to reduce the structural weight of aerospace vehicles was investigated. Application of the technology to space shuttle components was the primary consideration. The mechanical properties for the boron/epoxy, graphite/epoxy, and polyimide data are presented. Structural testing of two compression panel components was conducted in a simulated space shuttle thermal environment. Results of the tests are analyzed.

  12. Broadband electromagnetic analysis of dispersive, periodic structures for radiometer calibration

    NASA Astrophysics Data System (ADS)

    Sandeep, S.

    This thesis primarily focusses on the full wave electromagnetic analysis of radiometer calibration targets using doubly dispersive 3D Finite Difference Time Domain (FDTD) formulation. The boundary conditions are set up to solve for doubly periodic structures. The thesis contains very detailed derivation and equations regarding this formulation. One of the novelty in this formulation is the handling of magnetically and electrically dispersive media (usually it is just the electrical dispersion which is incorporated). Using a custom developed code which can be run on a distributed computing system, the reflectivity spectrum of calibration targets of different geometries, coating thicknesses and aspect ratios are analyzed. The results are well validated using commercial simulation softwares and custom Geometric Optics (GO) code. The geometries analyzed include square pyramids, conical pyramids, truncated square pyramids and truncated conical pyramids with spherical top. The coating thicknesses used are 1 mm, 2 mm and 3 mm. The aspect ratios (ratio of base to height) used include 1 : 1, 1 : 2 and 1 : 4. The nominal target structure has 1 : 4 aspect ratio and 2mm coating thickness. The material used for simulation is ECCOSORB MF112. The material properties of other materials such as MF110 and MF114 are listed. It should be remarked that measured material properties are available only in the frequency range [8, 26] GHz and a Debye series extrapolation was used for simulation at frequencies outside this range. Throughout this work 0.5 inch base was used. Some significant conclusions include the following: (1) 1:4 aspect ratio or better is required to achieve a -50 dB reflectivity or lower. (2) Low frequency reflectivity is independent of the target geometry. (3) At high frequencies, the conical target results in better performance when compared to square pyramids (by about 10 dB). (4) The reflectivity spectrum exhibits a general trend of high reflectivity at low

  13. Electromagnetic wave band structure due to surface plasmon resonances in a complex plasma

    NASA Astrophysics Data System (ADS)

    Vladimirov, S. V.; Ishihara, O.

    2016-07-01

    The dielectric properties of complex plasma containing either metal or dielectric spherical inclusions (macroparticles, dust) are investigated. We focus on surface plasmon resonances on the macroparticle surfaces and their effect on electromagnetic wave propagation. It is demonstrated that the presence of surface plasmon oscillations can significantly modify plasma electromagnetic properties by resonances and cutoffs in the effective permittivity. This leads to related branches of electromagnetic waves and to the wave band gaps. The conditions necessary to observe the band-gap structure in laboratory dusty plasma and/or space (cosmic) dusty plasmas are discussed.

  14. Electromagnetic wave band structure due to surface plasmon resonances in a complex plasma.

    PubMed

    Vladimirov, S V; Ishihara, O

    2016-07-01

    The dielectric properties of complex plasma containing either metal or dielectric spherical inclusions (macroparticles, dust) are investigated. We focus on surface plasmon resonances on the macroparticle surfaces and their effect on electromagnetic wave propagation. It is demonstrated that the presence of surface plasmon oscillations can significantly modify plasma electromagnetic properties by resonances and cutoffs in the effective permittivity. This leads to related branches of electromagnetic waves and to the wave band gaps. The conditions necessary to observe the band-gap structure in laboratory dusty plasma and/or space (cosmic) dusty plasmas are discussed. PMID:27575225

  15. Structures, systems and methods for harvesting energy from electromagnetic radiation

    DOEpatents

    Novack, Steven D.; Kotter, Dale K.; Pinhero, Patrick J.

    2011-12-06

    Methods, devices and systems for harvesting energy from electromagnetic radiation are provided including harvesting energy from electromagnetic radiation. In one embodiment, a device includes a substrate and one or more resonance elements disposed in or on the substrate. The resonance elements are configured to have a resonant frequency, for example, in at least one of the infrared, near-infrared and visible light spectra. A layer of conductive material may be disposed over a portion of the substrate to form a ground plane. An optical resonance gap or stand-off layer may be formed between the resonance elements and the ground plane. The optical resonance gap extends a distance between the resonance elements and the layer of conductive material approximately one-quarter wavelength of a wavelength of the at least one resonance element's resonant frequency. At least one energy transfer element may be associated with the at least one resonance element.

  16. Fabrication of Filamentary YBCO Coated Conductor by Inkjet Printing

    SciTech Connect

    List III, Frederick Alyious; Kodenkandath, Thomas; Rupich, Marty

    2007-01-01

    Inkjet printing is a potentially low cost, high rate method for depositing precursors for filamentary YBCO coated conductors. The method offers considerable flexibility of filament pattern, width, and thickness. Using standard solution precursors and RABiTSTM substrates, the printing, processing, and properties of some inkjet-derived filamentary YBCO coated conductors for Second Generation (2G) wire are demonstrated on a laboratory scale. Some systematic variations of growth rate and critical transport current with filament width are observed and discussed.

  17. A non-asymptotic homogenization theory for periodic electromagnetic structures

    PubMed Central

    Tsukerman, Igor; Markel, Vadim A.

    2014-01-01

    Homogenization of electromagnetic periodic composites is treated as a two-scale problem and solved by approximating the fields on both scales with eigenmodes that satisfy Maxwell's equations and boundary conditions as accurately as possible. Built into this homogenization methodology is an error indicator whose value characterizes the accuracy of homogenization. The proposed theory allows one to define not only bulk, but also position-dependent material parameters (e.g. in proximity to a physical boundary) and to quantify the trade-off between the accuracy of homogenization and its range of applicability to various illumination conditions. PMID:25104912

  18. Biological Decontamination Using Pulsed Filamentary Microplasma Jet

    NASA Astrophysics Data System (ADS)

    Pothiraja, Ramasamy; Lackmann, Jan-Wilm; Keil, Gernot; Bibinov, Nikita; Awakowicz, Peter

    Microplasma jet for the generation of pulsed filamentary discharge at atmospheric pressure has been devised for biological decontamination as well as for modification of surface properties. Long plasma-filament is generated inside a quartz tube and characterized using optical emission spectroscopy, current voltage measurements, numerical simulations and microphotography. Efficiency of our plasma source for the decontamination on inner surface of the tube as well as on objects placed in proximity of plasma effluent is studied. Escherichia coli (Gram-negative bacteria) and spores of Bacillus atrophaeus (Gram-positive bacteria) are used for the decontamination studies. Decontamination of Bacillus atrophaeus endospores, which are layered on PET polymer material, and placed in the proximity of plasma effluent, shows the mean logarithmic bacterial reduction of 3.67 for the treatment time of 120 s. Inactivation of Escherichia coli coated on inner surface of the tube shows the mean logarithmic bacterial reduction of about 5 for the treatment time of 30 s. In addition to this, inhibition studies of bacteria coated on agar plate are also carried out. It shows plasma effluent generated in our plasma source is very effective for the inhibition of bacterial colonization.

  19. Heating power lowering by downscaling the cell dimensions in nanoscale filamentary resistive switching devices

    NASA Astrophysics Data System (ADS)

    Yin, Qiaonan; Chen, Yan; Xia, Yidong; Xu, Bo; Yin, Jiang; Liu, Zhiguo

    2016-04-01

    In this work, we theoretically investigate the size dependence of the heat process in thermochemical filamentary resistive switching memories of crossbar structure. The equivalent heat resistance of the system increases with the device dimensions scaled down because of the size-dependent electric and thermal conductivity and geometry configurations. The higher equivalent heat resistance by diminishing the cell sizes induces an enhanced self-heating effect of the filament. It promises lower operation voltage and heating power to trigger the thermally activated dissolution of the filament in RESET process. These results strengthen the advantage of filamentary memories in lateral and longitudinal scaling down technologies where less power consumption has long been urged. Our results also show the opposite dependence of the driven electric field on the linewidth and thickness of the device.

  20. One-dimensional electromagnetic band gap structures formed by discharge plasmas in a waveguide

    SciTech Connect

    Arkhipenko, V. I.; Simonchik, L. V. Usachonak, M. S.; Callegari, Th.; Sokoloff, J.

    2014-09-28

    We demonstrate the ability to develop one-dimensional electromagnetic band gap structure in X-band waveguide solely by using the positive columns of glow discharges in neon at the middle pressure. Plasma inhomogeneities are distributed uniformly along a typical X-band waveguide with cross section of 23×10 mm². It is shown that electron densities larger than 10¹⁴ cm ⁻³ are needed in order to create an effective one-dimensional electromagnetic band gap structure. Some applications for using the one-dimensional electromagnetic band gap structure in waveguide as a control of microwave (broadband filter and device for variation of pulse duration) are demonstrated.

  1. Electromagnetic wave propagation in a magneto-plasma filled coaxial structure. I - Theoretical. II - Experimental

    NASA Technical Reports Server (NTRS)

    Askins, H. W., Jr.; Miller, D. B.

    1975-01-01

    This study is concerned with the problem of electromagnetic wave propagation in a magneto-plasma filled coaxial structure. The problem is formulated using the classical boundary value problem approach. A numerical investigation shows the existence of propagating slow modes, backward modes, a quasi-TEM mode, and waveguide-type modes in a magneto-plasma filled coaxial structure. Dispersion curves for these different modes are presented. Measurements have been made of electromagnetic propagation in a coaxial electrode structure filled with longitudinally magnetized plasma. The annular plasma region had a 9.55 cm outer diameter, a 3.82 cm inner diameter and was approximately 60 cm long. A magnetic field of 300 gauss was employed. Electromagnetic wave frequencies were in the range .5 to 2.4 GHz. The plasma was generated by a continuous glow discharge. The resulting dispersion curves closely follow the predicted curves for the quasi-TEM mode.

  2. Dispersion characteristics of spin-electromagnetic waves in planar multiferroic structures

    SciTech Connect

    Nikitin, Andrey A.; Ustinov, Alexey B.; Vitko, Vitaliy V.; Semenov, Alexander A.; Mironenko, Igor G.; Belyavskiy, Pavel Yu.; Kalinikos, Boris A.; Stashkevich, Andrey A.; Lähderanta, E.

    2015-11-14

    A method of approximate boundary conditions is used to derive dispersion relations for spin-electromagnetic waves (SEWs) propagating in thin ferrite films and in multiferroic layered structures. A high accuracy of this method is proven. It was shown that the spin-electromagnetic wave propagating in the structure composed of a thin ferrite film, a thin ferroelectric film, and a slot transmission line is formed as a result of hybridization of the surface spin wave in the ferrite film and the electromagnetic wave in the slot-line. The structure demonstrates dual electric and magnetic field tunability of the SEW spectrum. The electric field tunability is provided by the thin ferroelectric film. Its efficiency increases with an increase in the thicknesses of the ferrite and ferroelectric films and with a decrease in the slot-line gap width. The theory is confirmed by experimental data.

  3. Precision electromagnetic structure of octet baryons in the chiral regime

    SciTech Connect

    Boinepalli, S.; Leinweber, D. B.; Williams, A. G.; Zanotti, J. M.; Zhang, J. B.

    2006-11-01

    The electromagnetic properties of the baryon octet are calculated in quenched QCD on a 20{sup 3}x40 lattice with a lattice spacing of 0.128 fm using the fat-link irrelevant clover (FLIC) fermion action. FLIC fermions enable simulations to be performed efficiently at pion masses as low as 300 MeV. By combining FLIC fermions with an improved-conserved vector current, we ensure that discretization errors occur only at O(a{sup 2}) while maintaining current conservation. Magnetic moments and electric and magnetic radii are extracted from the electric and magnetic form factors for each individual quark sector. From these, the corresponding baryon properties are constructed. Our results are compared with the predictions of quenched chiral perturbation theory. We detect substantial curvature and environment sensitivity of the quark contributions to electric charge radii and magnetic moments in the low quark-mass region.

  4. Propagation of electromagnetic waves in P T -symmetric hyperbolic structures

    NASA Astrophysics Data System (ADS)

    Shramkova, O. V.; Tsironis, G. P.

    2016-07-01

    We investigate theoretically and numerically the propagation of electromagnetic waves in P T -symmetric periodic stacks composed of hyperbolic metamaterial layers separated by dielectric media with balanced loss and gain. We derive the characteristic frequencies governing the dispersion properties of the eigenwaves of P T -symmetric semiconductor-dielectric stacks. By tuning the loss/gain level and thicknesses of the layers, we study the evolution of the dispersion dependencies. We show that the effective-medium approach does not adequately describe the propagating waves in the P T -symmetric hypercrystals, even for wavelengths that are about 100 times larger than the period of the stack. We demonstrate the existence of anisotropic transmission resonances and above-unity reflection in P T -symmetric hyperbolic systems. The P T -symmetry-breaking transition of the scattering matrix is strongly influenced by the constitutive and geometrical parameters of the layers and the angles of wave incidence.

  5. Parallel Computation of Integrated Electromagnetic, Thermal and Structural Effects for Accelerator Cavities

    SciTech Connect

    Akcelik, V.; Candel, A.E.; Kabel, A.C.; Ko, K.; Lee, L.; Li, Z.; Ng, C.K.; Xiao, L.; /SLAC

    2011-11-02

    The successful operation of accelerator cavities has to satisfy both rf and mechanical requirements. It is highly desirable that electromagnetic, thermal and structural effects such as cavity wall heating and Lorentz force detuning in superconducting rf cavities can be addressed in an integrated analysis. Based on the SLAC parallel finite-element code infrastructure for electromagnetic modeling, a novel multi-physics analysis tool has been developed to include additional thermal and mechanical effects. The parallel computation enables virtual prototyping of accelerator cavities on computers, which would substantially reduce the cost and time of a design cycle. The multi-physics tool is applied to the LCLS rf gun for electromagnetic, thermal and structural analyses.

  6. Making structured metals transparent for ultrabroadband electromagnetic waves and acoustic waves

    SciTech Connect

    Fan, Ren-Hao; Peng, Ru-Wen; Huang, Xian-Rong; Wang, Mu

    2015-07-15

    In this review, we present our recent work on making structured metals transparent for broadband electromagnetic waves and acoustic waves via excitation of surface waves. First, we theoretically show that one-dimensional metallic gratings can become transparent and completely antireflective for extremely broadband electromagnetic waves by relying on surface plasmons or spoof surface plasmons. Second, we experimentally demonstrate that metallic gratings with narrow slits are highly transparent for broadband terahertz waves at oblique incidence and high transmission efficiency is insensitive to the metal thickness. Further, we significantly develop oblique metal gratings transparent for broadband electromagnetic waves (including optical waves and terahertz ones) under normal incidence. In the third, we find the principles of broadband transparency for structured metals can be extended from one-dimensional metallic gratings to two-dimensional cases. Moreover, similar phenomena are found in sonic artificially metallic structures, which present the transparency for broadband acoustic waves. These investigations provide guidelines to develop many novel materials and devices, such as transparent conducting panels, antireflective solar cells, and other broadband metamaterials and stealth technologies. - Highlights: • Making structured metals transparent for ultrabroadband electromagnetic waves. • Non-resonant excitation of surface plasmons or spoof surface plasmons. • Sonic artificially metallic structures transparent for broadband acoustic waves.

  7. Electromagnetic structure of decuplet baryons towards the chiral regime

    SciTech Connect

    Boinepalli, S.; Leinweber, D. B.; Moran, P. J.; Williams, A. G.; Zanotti, J. M.; Zhang, J. B.

    2009-09-01

    The electromagnetic properties of the baryon decuplet are calculated in quenched QCD on a 20{sup 3}x40 lattice with a lattice spacing of 0.128 fm using the fat-link irrelevant clover fermion action with quark masses providing a pion mass as low as 300 MeV. Magnetic moments and charge radii are extracted from the electric and magnetic form factors for each individual quark sector. From these, the corresponding baryon properties are constructed. We present results for the higher-order moments of the spin-3/2 baryons, including the electric-quadrupole moment E2 and the magnetic-octupole moment M3. The world's first determination of a nonzero M3 form factor for the {delta} baryon is presented. With these results we provide a conclusive analysis which shows that decuplet baryons are deformed. We compare the decuplet-baryon results from a similar lattice calculation of the octet baryons. We establish that the environment sensitivity is far less pronounced for the decuplet baryons compared to the octet baryons. A surprising result is that the charge radii of the decuplet baryons are generally smaller than those of the octet baryons. The magnetic moment of the {delta}{sup +} reveals a turnover in the low quark-mass region, making it smaller than the proton magnetic moment. These results are consistent with the expectations of quenched chiral perturbation theory. A similar turnover is also noticed in the magnetic moment of the {sigma}*{sup 0}, but not for {xi}* where only kaon loops can appear in quenched QCD. The electric-quadrupole moment of the {omega}{sup -} baryon is positive when the negative charge factor is included, and is equal to 0.86{+-}0.12x10{sup -2} fm{sup 2}, indicating an oblate shape.

  8. PHYSICAL FOUNDATIONS OF QUANTUM ELECTRONICS: Multiple reflection method for electromagnetic waves in layered dielectric structures

    NASA Astrophysics Data System (ADS)

    Morozov, G. V.; Maev, R. G.; Drake, G. W. F.

    2001-09-01

    Reflection and transmission of a plane electromagnetic wave propagating in a layered dielectric structure with an arbitrary number of layers of various thicknesses are investigated. For the general case of oblique incidence of the wave on this structure, the reflection and transmission coefficients are calculated for both TE and TM waves using a multiple reflection method. An algorithm to apply the obtained formulas for numerical and analytical calculations is suggested.

  9. Structure characteristics in industrially centrifugally cast 25Cr20Ni stainless steel tubes solidified under different electromagnetic field intensity

    SciTech Connect

    Wu, X.Q.; Yang, Y.S.; Zhang, J.S.; Jia, G.L.; Hu, Z.Q.

    1999-10-01

    The influences of different electromagnetic field intensities on the solidification structures of industrially centrifugally cast 25Cr20Ni stainless steel tubes have been investigated in detail. The results reveal that the electromagnetic field exerted during the centrifugal solidification causes a marked variation in the structures of the cast tubes. With an increase of the electromagnetic field intensity, the area fraction of the equiaxed structures in transverse sections of the cast tubes increases, and the macrostructures are gradually refined. The distribution of the eutectic carbides changes from the dendrite boundaries to the grain boundaries. However, an excessive electromagnetic field intensity gives rise to many intergranular cast defects formed along the inner walls of the centrifugally cast tubes. The effects of fluid flow induced by the electromagnetic field on the solidification process of the centrifugally cast tubes are the primary reason for the previously mentioned structure variations.

  10. Study of filamentary damage in synthesized silica induced by chirped femtosecond laser pulses

    SciTech Connect

    Onda, Satoshi; Watanabe, Wataru; Yamada, Kazuhiro; Itoh, Kazuyoshi; Nishii, Junji

    2005-11-01

    Different filamentary tracks in synthesized silica were induced by varying both the pulse duration and the incident energy of chirped laser pulses under slow-focusing conditions. Short-duration pulses induced filamentary refractive-index change, whereas longer pulses produced scattering damage in filamentary tracks. We report a systematic study on the morphology and birefringence of filamentary refractive-index change and scattering damage.

  11. Influence analysis of structural parameters on electromagnetic properties of HTS linear induction motor

    NASA Astrophysics Data System (ADS)

    Zhao, J.; Zheng, T. Q.; Zhang, W.; Fang, J.; Liu, Y. M.

    2011-11-01

    A new type high temperature superconductor linear induction motor is designed and analyzed as a prototype to ensure applicability aimed at industrial motors. Made of Bi-2223/Ag, primary windings are distributed with the double-layer concentrated structure. The motor is analyzed by 2D electromagnetic Finite Element Method to get magnetic field distribution, thrust force, vertical force and so on. The critical current of motor and the electromagnetic force are mostly decided by the leakage flux density of primary slot and by the main magnetic flux and eddy current respectively. The structural parameters of motor have a great influence on the distribution of magnetic field. Under constant currents, the properties of motor are analyzed with different slot widths, slot heights and winding turns. The properties of motor, such as the maximum slot leakage flux density, motor thrust and motor vertical force, are analyzed with different structural parameters.

  12. Effect of shear stress on electromagnetic behaviors in superconductor-ferromagnetic bilayer structure

    NASA Astrophysics Data System (ADS)

    Yong, Huadong; Zhao, Meng; Jing, Ze; Zhou, Youhe

    2014-09-01

    In this paper, the electromagnetic response and shielding behaviour of superconductor-ferromagnetic bilayer structure are studied. The magnetomechanical coupling in ferromagnetic materials is also considered. Based on the linear piezomagnetic coupling model and anti-plane shear deformation, the current density and magnetic field in superconducting strip are obtained firstly. The effect of shear stress on the magnetization of strip is discussed. Then, we consider the magnetic cloak for superconductor-ferromagnetic bilayer structure. The magnetic permeability of ferromagnetic material is obtained for perfect cloaking in uniform magnetic field with magnetomechanical coupling in ferromagnet. The simulation results show that the electromagnetic response in superconductors will change by applying the stress only to the ferromagnetic material. In addition, the performance of invisibility of structure for non-uniform field will be affected by mechanical stress. It may provide a method to achieve tunability of superconducting properties with mechanical loadings.

  13. Semi-analytic approach for electromagnetic problems of large arrays structures

    NASA Astrophysics Data System (ADS)

    Rostami-Angas, Masoud

    helps us in finding the microscopic charactristics of the structure. Building on the theory that the molecules can be modeled by electric dipoles; a semi-analytic and semi-classical approach is developed to solve the electromagnetic problem of large array of dipoles and simulate the optical response of molecular aggregates. In chapter 3, a double negative (DNG) metamaterial structure is designed by unit cells of multilayer (concentric) spheres. The dispersion diagram is analyzed to find the frequency band with negative group velocity and the losses in DNG region. Basically, the combination of a positive permittivity dielectric and a negative permittivity plasmonic material can control the resonances of unit cells and therefore the effective permittivity of the 3-D structure. It is also discussed how a novel design of multilayer sphere unit cells leads to the DNG performance at the desired frequency band. In chapter 4, analytical solution to the problem of electromagnetic wave scattering by an arbitrary array of non-concentric spheres is derived. A full wave multipole expansion method is applied to express the electromagnetic fields in terms of the electric and magnetic dipole modes and the higher order moments. Vector spherical wave functions are used as the basis functions of the multipole expansions and the translation addition theorem is implemented to expand fields in desired coordinate systems. The accuracy and computational performance of the model are investigated and some interesting applications are discussed.

  14. The structure of the nucleon: Elastic electromagnetic form factors

    SciTech Connect

    Punjabi, V.; Perdrisat, C. F.; Jones, M. K.; Brash, E. J.; Carlson, C. E.

    2015-07-10

    Precise proton and neutron form factor measurements at Jefferson Lab, using spin observables, have recently made a significant contribution to the unraveling of the internal structure of the nucleon. Accurate experimental measurements of the nucleon form factors are a test-bed for understanding how the nucleon's static properties and dynamical behavior emerge from QCD, the theory of the strong interactions between quarks. There has been enormous theoretical progress, since the publication of the Jefferson Lab proton form factor ratio data, aiming at reevaluating the picture of the nucleon. We will review the experimental and theoretical developments in this field and discuss the outlook for the future.

  15. Nonasymptotic homogenization of periodic electromagnetic structures: Uncertainty principles

    NASA Astrophysics Data System (ADS)

    Tsukerman, Igor; Markel, Vadim A.

    2016-01-01

    We show that artificial magnetism of periodic dielectric or metal/dielectric structures has limitations and is subject to at least two "uncertainty principles." First, the stronger the magnetic response (the deviation of the effective permeability tensor from identity), the less accurate ("certain") the predictions of any homogeneous model. Second, if the magnetic response is strong, then homogenization cannot accurately reproduce the transmission and reflection parameters and, simultaneously, power dissipation in the material. These principles are general and not confined to any particular method of homogenization. Our theoretical analysis is supplemented with a numerical example: a hexahedral lattice of cylindrical air holes in a dielectric host. Even though this case is highly isotropic, which might be thought of as conducive to homogenization, the uncertainty principles remain valid.

  16. The structure of the nucleon: Elastic electromagnetic form factors

    DOE PAGESBeta

    Punjabi, V.; Perdrisat, C. F.; Jones, M. K.; Brash, E. J.; Carlson, C. E.

    2015-07-10

    Precise proton and neutron form factor measurements at Jefferson Lab, using spin observables, have recently made a significant contribution to the unraveling of the internal structure of the nucleon. Accurate experimental measurements of the nucleon form factors are a test-bed for understanding how the nucleon's static properties and dynamical behavior emerge from QCD, the theory of the strong interactions between quarks. There has been enormous theoretical progress, since the publication of the Jefferson Lab proton form factor ratio data, aiming at reevaluating the picture of the nucleon. We will review the experimental and theoretical developments in this field and discussmore » the outlook for the future.« less

  17. Electromagnetic modeling of large subwavelength-patterned highly resonant structures.

    PubMed

    Chaumet, P C; Demésy, G; Gauthier-Lafaye, O; Sentenac, A; Popov, E; Fehrembach, A-L

    2016-05-15

    The rigorous modeling of large (hundreds of wavelengths) optical resonant components patterned at a subwavelength scale remains a major issue, especially when long range interactions cannot be neglected. In this Letter, we compare the performances of the discrete dipole approximation approach to that of the Fourier modal, the finite element and the finite difference time domain methods, for simulating the spectral behavior of a cavity resonator integrated grating filter (CRIGF). When the component is invariant along one axis (two-dimensional configuration), the four techniques yield similar results, despite the modeling difficulty of such a structure. We also demonstrate, for the first time to the best of our knowledge, the rigorous modeling of a three-dimensional CRIGF. PMID:27177002

  18. Instability-driven electromagnetic fields in coronal plasmasa)

    NASA Astrophysics Data System (ADS)

    Manuel, M. J.-E.; Li, C. K.; Séguin, F. H.; Sinenian, N.; Frenje, J. A.; Casey, D. T.; Petrasso, R. D.; Hager, J. D.; Betti, R.; Hu, S. X.; Delettrez, J.; Meyerhofer, D. D.

    2013-05-01

    Filamentary electromagnetic fields previously observed in the coronae of laser-driven spherical targets [F. H. Séguin et al., Phys. Plasma. 19, 012701 (2012)] have been further investigated in laser-irradiated plastic foils. Face-on proton-radiography provides an axial view of these filaments and shows coherent cellular structure regardless of initial foil-surface conditions. The observed cellular fields are shown to have an approximately constant scale size of ˜210 μm throughout the plasma evolution. A discussion of possible field-generation mechanisms is provided and it is demonstrated that the likely source of the cellular field structure is the magnetothermal instability. Using predicted temperature and density profiles, the fastest growing modes of this instability were found to be slowly varying in time and consistent with the observed cellular size.

  19. Instability-driven electromagnetic fields in coronal plasmas

    DOE PAGESBeta

    Manuel, M. J.-E.; Li, C. K.; Seguin, F. H.; Sinenian, N.; Frenje, J. A.; Casey, D. T.; Petrasso, R. D.; Hager, J. D.; Betti, R.; Hu, S. X.; et al

    2013-04-15

    Filamentary electromagnetic fields previously observed in the coronae of laser-driven spherical targets [F. H. S eguin et al., Phys. Plasma. 19, 012701 (2012)] have been further investigated in laser irradiated plastic foils. Face-on proton-radiography provides an axial view of these filaments and shows coherent cellular structure regardless of initial foil-surface conditions. The observed cellular fields are shown to have an approximately constant scale size of 210 lm throughout the plasma evolution. A discussion of possible field-generation mechanisms is provided and it is demonstrated that the likely source of the cellular field structure is the magnetothermal instability. Using predicted temperature andmore » density profiles, the fastest growing modes of this instability were found to be slowly varying in time and consistent with the observed cellular size.« less

  20. Instability-driven electromagnetic fields in coronal plasmas

    SciTech Connect

    Manuel, M. J.-E.; Li, C. K.; Seguin, F. H.; Sinenian, N.; Frenje, J. A.; Casey, D. T.; Petrasso, R. D.; Hager, J. D.; Betti, R.; Hu, S. X.; Delettrez, J.; Meyerhofer, D. D.

    2013-04-15

    Filamentary electromagnetic fields previously observed in the coronae of laser-driven spherical targets [F. H. S eguin et al., Phys. Plasma. 19, 012701 (2012)] have been further investigated in laser irradiated plastic foils. Face-on proton-radiography provides an axial view of these filaments and shows coherent cellular structure regardless of initial foil-surface conditions. The observed cellular fields are shown to have an approximately constant scale size of 210 lm throughout the plasma evolution. A discussion of possible field-generation mechanisms is provided and it is demonstrated that the likely source of the cellular field structure is the magnetothermal instability. Using predicted temperature and density profiles, the fastest growing modes of this instability were found to be slowly varying in time and consistent with the observed cellular size.

  1. Instability-driven electromagnetic fields in coronal plasmas

    SciTech Connect

    Manuel, M. J.-E.; Li, C. K.; Séguin, F. H.; Sinenian, N.; Frenje, J. A.; Casey, D. T.; Petrasso, R. D.; Hager, J. D.; Betti, R.; Hu, S. X.; Delettrez, J.; Meyerhofer, D. D.

    2013-05-15

    Filamentary electromagnetic fields previously observed in the coronae of laser-driven spherical targets [F. H. Séguin et al., Phys. Plasma. 19, 012701 (2012)] have been further investigated in laser-irradiated plastic foils. Face-on proton-radiography provides an axial view of these filaments and shows coherent cellular structure regardless of initial foil-surface conditions. The observed cellular fields are shown to have an approximately constant scale size of ∼210 μm throughout the plasma evolution. A discussion of possible field-generation mechanisms is provided and it is demonstrated that the likely source of the cellular field structure is the magnetothermal instability. Using predicted temperature and density profiles, the fastest growing modes of this instability were found to be slowly varying in time and consistent with the observed cellular size.

  2. All-thin-film multilayered multiferroic structures with a slot-line for spin-electromagnetic wave devices

    SciTech Connect

    Nikitin, Andrey A.; Ustinov, Alexey B.; Semenov, Alexander A.; Kalinikos, Boris A.; Lähderanta, E.

    2014-03-03

    Spin-electromagnetic waves propagating in thin-film multilayered multiferroic structures containing a slot transmission line have been investigated both experimentally and theoretically. The thin-film structure was composed of a ferrite film, a ferroelectric film, and a slot-line. It was shown that the spectrum of the spin-electromagnetic wave was formed as a result of hybridization of the spin wave in the ferrite film with the electromagnetic wave in the slot-line and was electrically and magnetically tunable. For the experimental investigations, a microwave phase shifter based on the multiferroic structure has been fabricated. Performance characteristics are presented.

  3. Application of space analysis of electromagnetic fields to investigation of the geoelectrical structure of the Earth

    NASA Astrophysics Data System (ADS)

    Zhdanov, M. S.

    1987-03-01

    Lateral composition inhomogeneities of the Earth's deep geoelectric structure require special consideration for any conductivity evaluation of a region. This paper presents a review of some theoretical techniques for determining both the vertical and horizontal conductivity profiles of a region using a spatial distribution of observed electromagnetic fields at the Earth's surface. Effects of shallow positioned anomalies upon a deep conductivity determination are also considered. An application of the procedure is illustrated by a conductivity study in the Soviet Carpathians.

  4. LSP Simulation and Analytical Results on Electromagnetic Wave Scattering on Coherent Density Structures

    NASA Astrophysics Data System (ADS)

    Sotnikov, V.; Kim, T.; Lundberg, J.; Paraschiv, I.; Mehlhorn, T.

    2014-09-01

    The presence of plasma turbulence can strongly influence propagation properties of electromagnetic signals used for surveillance and communication. In particular, we are interested in the generation of low frequency plasma density irregularities in the form of coherent vortex structures. Interchange or flute type density irregularities in magnetized plasma are associated with Rayleigh-Taylor type instability. These types of density irregularities play important role in refraction and scattering of high frequency electromagnetic signals propagating in the earth ionosphere, in high energy density physics (HEDP) and in many other applications. We will discuss scattering of high frequency electromagnetic waves on low frequency density irregularities due to the presence of vortex density structures associated with interchange instability. We will also present PIC simulation results on EM scattering on vortex type density structures using the LSP code and compare them with analytical results. Acknowledgement: This work was supported by the Air Force Research laboratory, the Air Force Office of Scientific Research, the Naval Research Laboratory and NNSA/DOE grant no. DE-FC52-06NA27616 at the University of Nevada at Reno.

  5. Analysis of electromagnetic scattering by nearly periodic structures: an LDRD report.

    SciTech Connect

    Johnson, William Arthur; Warne, Larry Kevin; Jorgenson, Roy Eberhardt; Wilton, Donald R. (University of Houston, Houston, TX); Basilio, Lorena I.; Peters, David William; Capolino, F.

    2006-10-01

    In this LDRD we examine techniques to analyze the electromagnetic scattering from structures that are nearly periodic. Nearly periodic could mean that one of the structure's unit cells is different from all the others--a defect. It could also mean that the structure is truncated, or butted up against another periodic structure to form a seam. Straightforward electromagnetic analysis of these nearly periodic structures requires us to grid the entire structure, which would overwhelm today's computers and the computers in the foreseeable future. In this report we will examine various approximations that allow us to continue to exploit some aspects of the structure's periodicity and thereby reduce the number of unknowns required for analysis. We will use the Green's Function Interpolation with a Fast Fourier Transform (GIFFT) to examine isolated defects both in the form of a source dipole over a meta-material slab and as a rotated dipole in a finite array of dipoles. We will look at the numerically exact solution of a one-dimensional seam. In order to solve a two-dimensional seam, we formulate an efficient way to calculate the Green's function of a 1d array of point sources. We next formulate ways of calculating the far-field due to a seam and due to array truncation based on both array theory and high-frequency asymptotic methods. We compare the high-frequency and GIFFT results. Finally, we use GIFFT to solve a simple, two-dimensional seam problem.

  6. Full-wave finite-difference time-domain simulation of electromagnetic cloaking structures.

    PubMed

    Zhao, Yan; Argyropoulos, Christos; Hao, Yang

    2008-04-28

    This paper proposes a radial dependent dispersive finite-difference time-domain method for the modeling of electromagnetic cloaking structures. The permittivity and permeability of the cloak are mapped to the Drude dispersion model and taken into account in dispersive FDTD simulations. Numerical simulations demonstrate that under ideal conditions, objects placed inside the cloak are 'invisible' to external electromagnetic fields. However for the simplified cloak based on linear transformations, the back scattering has a similar level to the case of a PEC cylinder without any cloak, rendering the object still being 'visible'. It is also demonstrated numerically that the simplified cloak based on high-order transformations can indeed improve the cloaking performance. PMID:18545374

  7. The Dense Filamentary Giant Molecular Cloud G23.0-0.4: Birthplace of Ongoing Massive Star Formation

    NASA Astrophysics Data System (ADS)

    Su, Yang; Zhang, Shaobo; Shao, Xiangjun; Yang, Ji

    2015-10-01

    We present observations of 1.5 square degree maps of the 12CO, 13CO, and C18O (J = 1 - 0) emission toward the complex region of the supernova remnant (SNR) W41 and SNR G22.7-0.2. A massive (˜ 5× {10}5 {M}⊙ ), large (˜84 × 15 pc), and dense (˜103 cm-3) giant molecular cloud (GMC), G23.0-0.4 with {V}{LSR} ˜ 77 km s-1, is found to be adjacent to the two SNRs. The GMC displays a filamentary structure approximately along the Galactic plane. The filamentary structure of the dense molecular gas, traced by C18O (J = 1 - 0) emission, is also coincident well with the distribution of the dust-continuum emission in the direction. Two dense massive MC clumps, two 6.7 GHz methanol masers, and one H ii/SNR complex, associated with the 77 km s-1 GMC G23.0-0.4, are aligned along the filamentary structure, indicating the star-forming activity within the GMC. These sources have periodic projected spacing of 0.°18-0.°26 along the giant filament, which is consistent with the theoretical predictions of 0.°22. This indicates that the turbulence seems to dominate the fragmentation process of the dense gaseous filament on a large scale. The established 4.4 kpc distance of the GMC and the long dense filament traced by C18O emission, together with the rich massive star-formation groups in the nearby region, suggest that G23.0-0.4 is probably located at the near side of the Scutum-Centaurus arm in the first quadrant. Considering the large scale and the elongation structure along the Galactic plane, we speculate that the dense filamentary GMC is related to the spiral density wave of the Milky Way.

  8. Variable features on Mars. VII - Dark filamentary markings on Mars

    NASA Technical Reports Server (NTRS)

    Veverka, J.

    1976-01-01

    The paper discusses the location, variability, and possible nature of well-developed patterns of dark filamentary markings in the Mariner 9 photographic records. Although not common on Mars, the markings are concentrated in at least two areas: Depressio Hellespontica and Cerberus/Trivium Charontis. In certain localities, strong winds are required to bring these markings into prominence. The dark filamentary markings seem to be true albedo features controlled by local topography, it being unlikely that they are free linear dunes. The distinctive criss-cross pattern seen in many of the pictures suggests that jointing provides the controlling topographic grid. At this stage it cannot be inferred whether the markings are erosional or depositional in character.

  9. Time-dependent response of filamentary composite spherical pressure vessels

    NASA Technical Reports Server (NTRS)

    Dozier, J. D.

    1983-01-01

    A filamentary composite spherical pressure vessel is modeled as a pseudoisotropic (or transversely isotropic) composite shell, with the effects of the liner and fill tubes omitted. Equations of elasticity, macromechanical and micromechanical formulations, and laminate properties are derived for the application of an internally pressured spherical composite vessel. Viscoelastic properties for the composite matrix are used to characterize time-dependent behavior. Using the maximum strain theory of failure, burst pressure and critical strain equations are formulated, solved in the Laplace domain with an associated elastic solution, and inverted back into the time domain using the method of collocation. Viscoelastic properties of HBFR-55 resin are experimentally determined and a Kevlar/HBFR-55 system is evaluated with a FORTRAN program. The computed reduction in burst pressure with respect to time indicates that the analysis employed may be used to predict the time-dependent response of a filamentary composite spherical pressure vessel.

  10. Scattering of electromagnetic waves by vortex density structures associated with interchange instability: Analytical and large scale plasma simulation results

    NASA Astrophysics Data System (ADS)

    Sotnikov, V.; Kim, T.; Lundberg, J.; Paraschiv, I.; Mehlhorn, T. A.

    2014-05-01

    The presence of plasma turbulence can strongly influence propagation properties of electromagnetic signals used for surveillance and communication. In particular, we are interested in the generation of low frequency plasma density irregularities in the form of coherent vortex structures. Interchange or flute type density irregularities in magnetized plasma are associated with Rayleigh-Taylor type instability. These types of density irregularities play an important role in refraction and scattering of high frequency electromagnetic signals propagating in the earth ionosphere, in high energy density physics, and in many other applications. We will discuss scattering of high frequency electromagnetic waves on low frequency density irregularities due to the presence of vortex density structures associated with interchange instability. We will also present particle-in-cell simulation results of electromagnetic scattering on vortex type density structures using the large scale plasma code LSP and compare them with analytical results.

  11. Scattering of electromagnetic waves by vortex density structures associated with interchange instability: Analytical and large scale plasma simulation results

    SciTech Connect

    Sotnikov, V.; Kim, T.; Lundberg, J.; Paraschiv, I.; Mehlhorn, T. A.

    2014-05-15

    The presence of plasma turbulence can strongly influence propagation properties of electromagnetic signals used for surveillance and communication. In particular, we are interested in the generation of low frequency plasma density irregularities in the form of coherent vortex structures. Interchange or flute type density irregularities in magnetized plasma are associated with Rayleigh-Taylor type instability. These types of density irregularities play an important role in refraction and scattering of high frequency electromagnetic signals propagating in the earth ionosphere, in high energy density physics, and in many other applications. We will discuss scattering of high frequency electromagnetic waves on low frequency density irregularities due to the presence of vortex density structures associated with interchange instability. We will also present particle-in-cell simulation results of electromagnetic scattering on vortex type density structures using the large scale plasma code LSP and compare them with analytical results.

  12. Electromagnetic-field effects on structure and dynamics of amyloidogenic peptides.

    PubMed

    Todorova, Nevena; Bentvelzen, Alan; English, Niall J; Yarovsky, Irene

    2016-02-28

    Electromagnetic fields (EMFs) are ever-present, and so is the need to better understand their influence on human health and biological matter in general. The interaction between a molecular system and external EMF can alter the structure, and dynamical behaviour, and, hence, biological function of proteins with uncertain health consequences. This urges a detailed investigation of EMF-induced effects on basic protein biophysics. Here, we used all-atom non-equilibrium molecular dynamics simulations to understand and quantify the response mechanisms of the amyloidogenic apoC-II(60-70) peptides to non-ionising radiation by modelling their behaviour under external electromagnetic and electric fields of different strengths. Our simulations show high strength fields (>0.04 V/nm) cause structural changes in apoC-II(60-70) due to the peptide dipole alignment along the applied field direction, which disrupts the inherent β-hairpin conformation known to be the intermediate state for fibril formation. The intermediate field-strength range (0.04-0.004 V/nm) causes a significant acceleration in peptide dynamics, which leads to the increased population of structures with fibril-inhibiting characteristics, such as the separated N- and C-termini and colocation of the aromatic residues at the same peptide face. In contrast, lower field strengths (<0.004 V/nm) promote the formation of the amyloid-prone hairpin structures relative to the ambient conditions. These findings suggest that intermediate-strength electromagnetic fields could be considered for designing alternative treatments of amyloid diseases, while the very high and low field strengths could be employed for engineering well-ordered fibrillar aggregates for non-medicinal applications. PMID:26931725

  13. A New Method for Design of Geometrically Shaped Structures for Prescribed Electromagnetic Field Distribution

    NASA Astrophysics Data System (ADS)

    Pereira, Carlos Manuel

    The contribution of this research work to the body of existing knowledge is a novel design (inverse) method to compute the distribution of fields when electromagnetic waves interact with surfaces. If given a desired distribution of electromagnetic fields (radiation pattern), the design (inverse) method developed will rapidly allow a designer to determine a unique geometric solution which will provide the desired radiation pattern, which is an inverse problem. The method developed can also be used as an analysis tool to analyze radiating or receiving structures with simple and complex non-linear geometric features. In the extensive literature search provided in this work, others have used analytical methods for computing the distribution of electromagnetic fields when waves propagate and interact with structures. This requires a mathematical framework to be developed using time-harmonic and magnetic fields to solve boundary value problems using closed-form mathematical relationships that only have closed-form solutions for a few simple geometrical shapes. When the geometrical features of a structure contain arbitrary shapes with irregular geometries, finite element methods can also be used as analysis tools to handle any type of geometrical features, however, both of these methods are used to perform analysis of these types of problems and are very time consuming and not suited as design tools to rapidly provide design information on the geometry features that provide a desired electric field distribution. This revolutionary methodology provides a design tool which currently does not exist in the reviewed published literature. It overcomes deficiencies presented by current analysis tools, such as theoretical, analytical and numerical methods which are capable of analyzing wave propagation and interaction problems, but are not suited to rapidly design geometrical features of radiating or receiving structures.

  14. Electromagnetic-field effects on structure and dynamics of amyloidogenic peptides

    NASA Astrophysics Data System (ADS)

    Todorova, Nevena; Bentvelzen, Alan; English, Niall J.; Yarovsky, Irene

    2016-02-01

    Electromagnetic fields (EMFs) are ever-present, and so is the need to better understand their influence on human health and biological matter in general. The interaction between a molecular system and external EMF can alter the structure, and dynamical behaviour, and, hence, biological function of proteins with uncertain health consequences. This urges a detailed investigation of EMF-induced effects on basic protein biophysics. Here, we used all-atom non-equilibrium molecular dynamics simulations to understand and quantify the response mechanisms of the amyloidogenic apoC-II(60-70) peptides to non-ionising radiation by modelling their behaviour under external electromagnetic and electric fields of different strengths. Our simulations show high strength fields (>0.04 V/nm) cause structural changes in apoC-II(60-70) due to the peptide dipole alignment along the applied field direction, which disrupts the inherent β-hairpin conformation known to be the intermediate state for fibril formation. The intermediate field-strength range (0.04-0.004 V/nm) causes a significant acceleration in peptide dynamics, which leads to the increased population of structures with fibril-inhibiting characteristics, such as the separated N- and C-termini and colocation of the aromatic residues at the same peptide face. In contrast, lower field strengths (<0.004 V/nm) promote the formation of the amyloid-prone hairpin structures relative to the ambient conditions. These findings suggest that intermediate-strength electromagnetic fields could be considered for designing alternative treatments of amyloid diseases, while the very high and low field strengths could be employed for engineering well-ordered fibrillar aggregates for non-medicinal applications.

  15. BMFO-PVDF electrospun fiber based tunable metamaterial structures for electromagnetic interference shielding in microwave frequency region

    NASA Astrophysics Data System (ADS)

    Revathi, Venkatachalam; Dinesh Kumar, Sakthivel; Subramanian, Venkatachalam; Chellamuthu, Muthamizhchelvan

    2015-11-01

    Metamaterial structures are artificial structures that are useful in controlling the flow of electromagnetic radiation. In this paper, composite fibers of sub-micron thickness of barium substituted magnesium ferrite (Ba0.2Mg0.8Fe2O4) - polyvinylidene fluoride obtained by electrospinning is used as a substrate to design electromagnetic interference shielding structures. While electrospinning improves the ferroelectric properties of the polyvinylidene fluoride, the presence of barium magnesium ferrite modifies the magnetic property of the composite fiber. The dielectric and magnetic properties at microwave frequency measured using microwave cavity perturbation technique are used to design the reflection as well as absorption based tunable metamaterial structures for electromagnetic interference shielding in microwave frequency region. For one of the structures, the simulation indicates that single negative metamaterial structure becomes a double negative metamaterial under the external magnetic field.

  16. Novel Compact Mushroom-Type EBG Structure for Electromagnetic Coupling Reduction of Microstrip Antenna array

    NASA Astrophysics Data System (ADS)

    Hu, Lizhong; Wang, Guangming; Liang, Jiangang; Zhang, Chenxin

    2015-03-01

    A novel compact electromagnetic bandgap (EBG) structure consisting of two turns complementary spiral resonator (CSR) and conventional mushroom EBG (CM-EBG) structure is introduced to suppress the mutual coupling in antenna arrays for multiple-input and multiple-output (MIMO) applications. Eigenmode calculation is used to investigate the proposed CSR-loaded mushroom-type EBG (MT-EBG), which proved to exhibit bandgap property and a miniaturization of 48.9% is realized compared with the CM-EBG. By inserting the proposed EBG structure between two E-plane coupled microstrip antennas, a mutual coupling reduction of 8.13 dB has been achieved numerically and experimentally. Moreover, the EBG-loaded antenna has better far-field radiation patterns compared with the reference antenna. Thus, this novel EBG structure with advantages of compactness and high decoupling efficiency opens an avenue to new types of antennas with super performances.

  17. Self-organized electromagnetic field structures in laser-produced counter-streaming plasmas

    NASA Astrophysics Data System (ADS)

    Kugland, N. L.; Ryutov, D. D.; Chang, P.-Y.; Drake, R. P.; Fiksel, G.; Froula, D. H.; Glenzer, S. H.; Gregori, G.; Grosskopf, M.; Koenig, M.; Kuramitsu, Y.; Kuranz, C.; Levy, M. C.; Liang, E.; Meinecke, J.; Miniati, F.; Morita, T.; Pelka, A.; Plechaty, C.; Presura, R.; Ravasio, A.; Remington, B. A.; Reville, B.; Ross, J. S.; Sakawa, Y.; Spitkovsky, A.; Takabe, H.; Park, H.-S.

    2012-11-01

    Self-organization occurs in plasmas when energy progressively transfers from smaller to larger scales in an inverse cascade. Global structures that emerge from turbulent plasmas can be found in the laboratory and in astrophysical settings; for example, the cosmic magnetic field, collisionless shocks in supernova remnants and the internal structures of newly formed stars known as Herbig-Haro objects. Here we show that large, stable electromagnetic field structures can also arise within counter-streaming supersonic plasmas in the laboratory. These surprising structures, formed by a yet unexplained mechanism, are predominantly oriented transverse to the primary flow direction, extend for much larger distances than the intrinsic plasma spatial scales and persist for much longer than the plasma kinetic timescales. Our results challenge existing models of counter-streaming plasmas and can be used to better understand large-scale and long-time plasma self-organization.

  18. Characterizing filamentary switching in resistive memories (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Busby, Yan; Pireaux, Jean-Jacques

    2015-09-01

    Characterizing filamentary switching in resistive memories For many organic, inorganic and hybrid memory devices the resistive switching mechanism is well known to rely on filament formation [1]. This implies that localized conductive paths are established between the two terminal electrodes during the forming step. This filaments sustain the current flow when the memory is in the low conductive state and they can be ruptured and possibly re-formed for more than hundreds of I-V cycles. The nature and morphology of filaments has been long time debated especially for organic memories. The filament size, density and formation mechanism have been very challenging to be characterized, and need appropriate experimental techniques. However, filaments in organic memories have been recently identified and characterized by cross-section transmission electron microscopy (TEM), conductive-AFM, AFM-tomography and through depth profile analysis combining Time-of-flight secondary ions mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS). In particular, 3D spectroscopic images obtained with ToF-SIMS give access for the first time to filament formation process and rupture mechanism. From these results, a clear picture of the filament(s) dynamics during memory operation can be drawn. In this contribution, recent results showing filaments in memories based on different structures and architectures will be discussed. The memories are based on insulating polymers (polystyrene [2] and poly methyl methacrylate [3]), conductive polymers/nanocomposites (polyera N1400 with metal NPs [4]), and small semiconducting molecules (Tris(8-hydroxyquinolinato)aluminium - Alq3 [5]). The results show that resistive switching clearly involves the inhomogeneous metal diffusion in the organic layer taking place during the top electrode deposition and during memory operation. This may be of great relevance in many other organic electronics applications. REFERENCES [1] S. Nau, S. Sax, E

  19. Application study of filamentary composites in a commercial jet aircraft fuselage

    NASA Technical Reports Server (NTRS)

    Johnson, R. W.; June, R. R.

    1972-01-01

    A study of applications of filamentary composite materials to aircraft fuselage structure was performed. General design criteria were established and material studies conducted using the 727-200 forebody as the primary structural component. Three design approaches to the use of composites were investigated: uniaxial reinforcement of metal structure, uniaxial and biaxial reinforcement of metal structure, and an all-composite design. Materials application studies for all three concepts were conducted on fuselage shell panels, keel beam, floor beams, floor panels, body frames, fail-safe straps, and window frames. Cost benefit studies were conducted and developmental program costs estimated. On the basis of weight savings, cost effectiveness, developmental program costs, and potential for early application on commercial aircraft, the unaxial design is recommended for a 5-year flight service evaluation program.

  20. Broadband impedance-matched electromagnetic structured ferrite composite in the megahertz range

    SciTech Connect

    Parke, L.; Hibbins, A. P.; Sambles, J. R.; Youngs, I. J.

    2014-06-02

    A high refractive-index structured ferrite composite is designed to experimentally demonstrate broadband impedance matching to free-space. It consists of an array of ferrite cubes that are anisotropically spaced, thereby allowing for independent control of the effective complex permeability and permittivity. Despite having a refractive index of 9.5, the array gives less than 1% reflection and over 90% transmission of normally incident radiation up to 70 MHz for one of the orthogonal linear polarisations lying in a symmetry plane of the array. This result presents a route to the design of MHz-frequency ferrite composites with bespoke electromagnetic parameters for antenna miniaturisation.

  1. Investigation of the electromagnetic structure of η and η' mesons by two-photon interactions

    NASA Astrophysics Data System (ADS)

    Aihara, H.; Alston-Garnjost, M.; Avery, R. E.; Barbaro-Galtieri, A.; Barker, A. R.; Barnett, B. A.; Bauer, D. A.; Bay, A.; Bobbink, G. J.; Buchanan, C. D.; Buijs, A.; Caldwell, D. O.; Chao, H.-Y.; Chun, S.-B.; Clark, A. R.; Cowan, G. D.; Crane, D. A.; Dahl, O. I.; Daoudi, M.; Derby, K. A.; Eastman, J. J.; Eberhard, P. H.; Edberg, T. K.; Eisner, A. M.; Erné, F. C.; Fairfield, K. H.; Hauptman, J. M.; Hofmann, W.; Hylen, J.; Kamae, T.; Kaye, H. S.; Kenney, R. W.; Khacheryan, S.; Kofler, R. R.; Langeveld, W. G.; Layter, J. G.; Lin, W. T.; Linde, F. L.; Loken, S. C.; Lu, A.; Lynch, G. R.; Madaras, R. J.; Magnuson, B. D.; Masek, G. E.; Mathis, L. G.; Matthews, J. A.; Maxfield, S. J.; Miller, E. S.; Moses, W.; Nygren, D. R.; Oddone, P. J.; Paar, H. P.; Park, S. K.; Pellett, D. E.; Pripstein, M.; Ronan, M. T.; Ross, R. R.; Rouse, F. R.; Schwitkis, K. A.; Sens, J. C.; Shapiro, G.; Shen, B. C.; Smith, J. R.; Steinman, J. S.; Stephens, R. W.; Stevenson, M. L.; Stork, D. H.; Strauss, M. G.; Sullivan, M. K.; Takahashi, T.; Toutounchi, S.; van Tyen, R.; Vernon, W.; Wagner, W.; Wang, E. M.; Wang, Y.-X.; Wenzel, W. A.; Wolf, Z. R.; Yamamoto, H.; Yellin, S. J.; Zeitlin, C.; TPC/Two-Gamma Collaboration

    1990-01-01

    The TPC/Two-Gamma facility at the SLAC e+e- storage ring PEP was used to study the reactions γγ*-->η and γγ*-->η'. The ηγ*γ and η'γ*γ transition form factors were measured as functions of Q2, the negative of the invariant mass squared of the tagged photon, in the range 0.1electromagnetic structure of the η and η' mesons are consistent with both vector-meson dominance and QCD. They also provide new measurements of the pseudoscalar mixing angle and decay constants.

  2. Electromagnetic and muonic structure of showers initiated by gamma-rays and by hadrons

    NASA Technical Reports Server (NTRS)

    Hillas, A. M.

    1985-01-01

    If photon cascades develop by the usual mechanisms, there should indeed be notable differences between the structure of showers due to photon and hadron primaries, as regards muon densities and lateral distributions of some detector signals. The muon content of showers from Cygnus X-3, observed at Kiel, cannot be understood in this way. One remedy is to postulate arbitrarily a strong hadronic interaction of photons in the TeV region. This would utterly change the nature of electromagnetic cascades, but surprisingly does not at first sight seem to be in conflict with air shower observations.

  3. Vibration and shape control of hinged light structures using electromagnetic forces

    NASA Astrophysics Data System (ADS)

    Matsuzaki, Yuji; Miyachi, Shigenobu; Sasaki, Toshiyuki

    2003-08-01

    This paper describes a new electromagnetic device for vibration control of a light-weighted deployable/retractable structure which consists of many small units connected with mechanical hinges. A typical example of such a structure is a solar cell paddle of an artificial satellite which is composed of many thin flexible blankets connected in series. Vibration and shape control of the paddle is not easy, because control force and energy do not transmit well between the blankets which are discretely connected by hinges with each other. The new device consists of a permanent magnet glued along an edge of a blanket and an electric current-conducting coil glued along an adjoining edge of another adjacent blanket. Conduction of the electric current in a magnetic field from the magnet generates an electromagnetic force on the coil. By changing the current in the coil, therefore, we may control the vibration and shape of the blankets. To confirm the effectiveness of the new device, constructing a simple paddle model consisting eight hinge- panels, we have carried out a model experiment of vibration and shape control of the paddle. In addition, a numerical simulation of vibration control of the hinge structure is performed to compare with measured data.

  4. Electromagnetic interference (EMI) transparent shielding of reduced graphene oxide (RGO) interleaved structure fabricated by electrophoretic deposition.

    PubMed

    Kim, Sanghoon; Oh, Joon-Suk; Kim, Myeong-Gi; Jang, Woojin; Wang, Mei; Kim, Youngjun; Seo, Hee Won; Kim, Ye Chan; Lee, Jun-Ho; Lee, Youngkwan; Nam, Jae-Do

    2014-10-22

    Here we introduce the electromagnetic shielding effectiveness (SE) of reduced graphene oxide (RGO) sheets interleaved between polyetherimide (PEI) films fabricated by electrophoretic deposition (EPD). Incorporating only 0.66 vol % of RGO, the developed PEI/RGO composite films exhibited an electromagnetic interference shielding effectiveness (EMI SE) at 6.37 dB corresponding to ∼50% shielding of incident waves. Excellent flexibility and optical transparency up to 62% of visible light was demonstrated. It was achieved by placing the RGO sheets in the localized area as a thin film (ca. 20 nm in thickness) between the PEI films (ca. 2 μm) to be an interleaved and alternating structure. This unique interleaved structure without any delamination areas was fabricated by a successive application of cathodic and anodic EPD of both RGO and PEI layers. The EPD fabrication process was ensured by an alternating deposition of the quarternized-PEI drops and RGO, each taking positive and negative charges, respectively, in the water medium. We believe that the developed facile fabrication method of RGO interleaved structure with such low volume fraction has great potential to be used as a transparent EMI shielding material. PMID:25238628

  5. Spirulina-Templated Metal Microcoils with Controlled Helical Structures for THz Electromagnetic Responses

    PubMed Central

    Kamata, Kaori; Piao, Zhenzi; Suzuki, Soichiro; Fujimori, Takahiro; Tajiri, Wataru; Nagai, Keiji; Iyoda, Tomokazu; Yamada, Atsushi; Hayakawa, Toshiaki; Ishiwara, Mitsuteru; Horaguchi, Satoshi; Belay, Amha; Tanaka, Takuo; Takano, Keisuke; Hangyo, Masanori

    2014-01-01

    Microstructures in nature are ultrafine and ordered in biological roles, which have attracted material scientists. Spirulina forms three-dimensional helical microstructure, one of remarkable features in nature beyond our current processing technology such as lithography in terms of mass-productivity and structural multiplicity. Spirulina varies its diameter, helical pitch, and/or length against growing environment. This unique helix is suggestive of a tiny electromagnetic coil, if composed of electro-conductive metal, which brought us main concept of this work. Here, we describe the biotemplating process onto Spirulina surface to fabricate metal microcoils. Structural parameters of the microcoil can be controlled by the cultivation conditions of Spirulina template and also purely one-handed microcoil can be fabricated. A microcoil dispersion sheet exhibited optically active response attributed to structural resonance in terahertz-wave region. PMID:24815190

  6. Spirulina-Templated Metal Microcoils with Controlled Helical Structures for THz Electromagnetic Responses

    NASA Astrophysics Data System (ADS)

    Kamata, Kaori; Piao, Zhenzi; Suzuki, Soichiro; Fujimori, Takahiro; Tajiri, Wataru; Nagai, Keiji; Iyoda, Tomokazu; Yamada, Atsushi; Hayakawa, Toshiaki; Ishiwara, Mitsuteru; Horaguchi, Satoshi; Belay, Amha; Tanaka, Takuo; Takano, Keisuke; Hangyo, Masanori

    2014-05-01

    Microstructures in nature are ultrafine and ordered in biological roles, which have attracted material scientists. Spirulina forms three-dimensional helical microstructure, one of remarkable features in nature beyond our current processing technology such as lithography in terms of mass-productivity and structural multiplicity. Spirulina varies its diameter, helical pitch, and/or length against growing environment. This unique helix is suggestive of a tiny electromagnetic coil, if composed of electro-conductive metal, which brought us main concept of this work. Here, we describe the biotemplating process onto Spirulina surface to fabricate metal microcoils. Structural parameters of the microcoil can be controlled by the cultivation conditions of Spirulina template and also purely one-handed microcoil can be fabricated. A microcoil dispersion sheet exhibited optically active response attributed to structural resonance in terahertz-wave region.

  7. Kinetic structure of slow shocks - Effects of the electromagnetic ion/ion cyclotron instability

    NASA Technical Reports Server (NTRS)

    Omidi, N.; Winske, D.

    1992-01-01

    The structure of slow magnetosonic shocks in the low beta regime is analyzed with attention given to ion heating and the effects of waves upstream of the electromagnetic ion/ion cyclotron (EMIIC) instability. Shock formation is assessed by means of three methods - a relaxation method and two based on dynamic flow interactions - to determine the effects of initialization and boundary conditions on the formation. Good solutions are found with the piston method and the similar flow-flow method in which the plasma is injected from two boundaries to form two slow shocks. Plasma parameters and shock normal angle are found to be the key variables dictating the structure of the magnetosonic shocks. Four unique classes of resultant shock structures are described in which classical, steady, or nonsteady behavior is found. The analysis also yields insight into the relationship between EMIIC instability and ion dissipation.

  8. Tailor-Made Distribution of Nanoparticles in Blend Structure toward Outstanding Electromagnetic Interference Shielding.

    PubMed

    Biswas, Sourav; Kar, Goutam Prasanna; Bose, Suryasarathi

    2015-11-18

    Engineering blend structure with tailor-made distribution of nanoparticles is the prime requisite to obtain materials with extraordinary properties. Herein, a unique strategy of distributing nanoparticles in different phases of a blend structure has resulted in >99% blocking of incoming electromagnetic (EM) radiation. This is accomplished by designing a ternary polymer blend structure using polycarbonate (PC), poly(vinylidene fluoride) (PVDF), and poly(methyl methacrylate) (PMMA) to simultaneously improve the structural, electrical, and electromagnetic interference shielding (EMI). The blend structure was made conducting by preferentially localizing the multi-wall nanotubes (MWNTs) in the PVDF phase. By taking advantage of "π-π stacking" MWNTs was noncovalently modified with an imidazolium based ionic liquid (IL). Interestingly, the enhanced dispersion of IL-MWNTs in PVDF improved the electrical conductivity of the blends significantly. While one key requisite to attenuate EM radiation (i.e., electrical conductivity) was achieved using MWNTs, the magnetic properties of the blend structure was tuned by introducing barium ferrite (BaFe) nanoparticles, which can interact with the incoming EM radiation. By suitably modifying the surface of BaFe nanoparticles, we can tailor their localization under the macroscopic processing condition. The precise localization of BaFe nanoparticles in the PC phase, due to nucleophilic substitution reaction, and the MWNTs in the PVDF phase not only improved the conductivity but also facilitated in absorption of the incoming microwave radiation due to synergetic effect from MWNT and BaFe. The shielding effectiveness (SE) was measured in X and Ku band, and an enhanced SE of -37 dB was noted at 18 GHz frequency. PMMA, which acted as an interfacial modifier in PC/PVDF blends further, resulting in a significant enhancement in the mechanical properties besides retaining high SE. This study opens a new avenue in designing mechanically strong

  9. Influence analysis of structural parameters and operating parameters on electromagnetic properties of HTS linear induction motor

    NASA Astrophysics Data System (ADS)

    Fang, J.; Sheng, L.; Li, D.; Zhao, J.; Li, Sh.; Qin, W.; Fan, Y.; Zheng, Q. L.; Zhang, W.

    A novel High Temperature Superconductor Linear Induction Motor (HTS LIM) is researched in this paper. Since the critical current and the electromagnetic force of the motor are determined mainly by the primary slot leakage flux, the main magnetic flux and eddy current respectively, in order to research the influence of structural parameters and operating parameters on electromagnetic properties of HTS LIM, the motor was analyzed by 2D transient Finite Element Method (FEM). The properties of the motor, such as the maximum slot leakage flux density, motor thrust, motor vertical force and critical current are analyzed with different structural parameters and operating parameters. In addition, an experimental investigation was carried out on prototype HTS motor. Electrical parameters were deduced from these tests and also compared with the analysis results from FEM. AC losses of one HTS coil in the motor were measured and AC losses of all HTS coils in HTS LIM were estimated. The results in this paper could provide reference for the design and research on the HTS LIM.

  10. Coherent scattering of electromagnetic waves by self-organized dust structures: Degree of coherence

    SciTech Connect

    Tsytovich, Vadim; Gusein-zade, Namik; Ignatov, Alexander

    2015-02-15

    It is demonstrated explicitly that the scattering of electromagnetic waves by dust structures can be strongly enhanced as compared to incoherent scattering by random electrons. If the size of the dust structure is much less than the wavelength of the incident radiation, the scattering is coherent. In this case, the scattering is proportional to the square of the total number of electrons in the structure. In the opposite limit, the scattering is incoherent being proportional to the total number of electrons in the structure. The factor describing the degree of coherency is calculated numerically for several models of self-organized structures. It is demonstrated in general way that for sudden heating of electrons, the factor of coherency in scattering by structures can decrease by several orders of magnitude with subsequent increase after the heating is switched off. In laboratory dusty plasmas, the coherent scattering is proposed for diagnostics of universal structuring instability and as a probe for determining the properties typical for self-organized nature of structures that are observed in recent experiments.

  11. Coherent scattering of electromagnetic waves by self-organized dust structures: Degree of coherence

    NASA Astrophysics Data System (ADS)

    Tsytovich, Vadim; Gusein-zade, Namik; Ignatov, Alexander

    2015-02-01

    It is demonstrated explicitly that the scattering of electromagnetic waves by dust structures can be strongly enhanced as compared to incoherent scattering by random electrons. If the size of the dust structure is much less than the wavelength of the incident radiation, the scattering is coherent. In this case, the scattering is proportional to the square of the total number of electrons in the structure. In the opposite limit, the scattering is incoherent being proportional to the total number of electrons in the structure. The factor describing the degree of coherency is calculated numerically for several models of self-organized structures. It is demonstrated in general way that for sudden heating of electrons, the factor of coherency in scattering by structures can decrease by several orders of magnitude with subsequent increase after the heating is switched off. In laboratory dusty plasmas, the coherent scattering is proposed for diagnostics of universal structuring instability and as a probe for determining the properties typical for self-organized nature of structures that are observed in recent experiments.

  12. Strong ion energization by electromagnetic fluctuations in plasmoid-like magnetic structures.

    NASA Astrophysics Data System (ADS)

    Grigorenko, Elena

    2016-04-01

    Numerous studies based on data from many magnetospheric missions reported the observations of energetic ions with energies of hundreds of keV in the Earth magnetotail. The acceleration of charged particles to energies exceeding the potential drop across the tail can be produced by strong inductive electric fields generated in the course of transient processes related to changes of the magnetic field topology: e.g., magnetic reconnection, dipolarization, magnetic turbulence, and so on. The observations of energetic ion flows by Cluster/RAPID instruments in the near-Earth tail show the increase of H+, He+, and O+ fluxes in the energy range ≥130 keV during the periods of the tailward flows. The hardening of ion spectra is observed inside the plasmoid-like magnetic structures propagating tailward through the Cluster spacecraft. Simultaneously, the low-frequency electromagnetic fluctuations were observed in such structures. The analysis of 37 events demonstrated that the following factors are favorable for the ion energization: (1) the spatial scale of a plasmoid should exceed the thermal gyroradius of a given ion component in the plasmoid neutral plane; (2) the Power Spectral Density (PSD) of the magnetic fluctuations near the gyrofrequency of a particular ion component should exceed ~ 50.0 nT2/Hz for oxygen ions; while the energization of He+ and H+ takes place for much lower values of the PSD. The kinetic analysis of ion dynamics in the plasmoid-like magnetic configurations with the superimposed electromagnetic fluctuations similar to the observed ones confirms the importance of ion resonant interactions with the low-frequency electromagnetic fluctuations for ion energization inside plasmoids. The analysis also show that to be strongly accelerated ions do not need to pass a large distance in the duskward direction and the effective energization can be reached even at the localized source. Thus, ion acceleration by the electromagnetic fluctuations may smear the dawn

  13. Generation of Non-Propagating Electromagnetic-Plasma Structures and Formation of Quasi-Static and Alfvenic Discrete Auroras

    NASA Astrophysics Data System (ADS)

    Song, Y.; Lysak, R. L.

    2013-12-01

    The nonlinear interaction of incident and reflected Alfven wave packets in auroral acceleration regions can create non-propagating electromagnetic-plasma structures, such as transverse Alfvenic double layers and charge holes. These dynamical structures are often characterized by localized strong electrostatic electric fields, localized density cavities and enhanced magnetic or mechanical stresses, and are responsible for auroral particle acceleration and the formation of both Alfvenic and quasi-static inverted-V discrete auroras. Similar electromagnetic-plasma structures should also be generated in other cosmic plasmas, and would constitute effective high energy accelerators of charged particles in cosmic plasmas.

  14. Electromagnetic scattering from a structured slab comprised of periodically placed resistive cards

    NASA Astrophysics Data System (ADS)

    Jorgenson, Roy E.; Mittra, Raj

    1989-05-01

    The structured slab, which is constructed by arranging cells composed of thin, lossy, dielectric cards on a one- or two-dimensional lattice, is an important material in the aerospace industry because of its high strength-to-weight ratio. Recently, the structured slab has also been used to reduce the radar cross section of various aircraft. It is important, therefore, to characterize how an electromagnetic wave scatters from this slab. The structured slabs discussed herein are constructed by repeating lossy strips periodically in one dimension or lossy plates in two dimensions. An electric field integral equation is formulated which has as its unknown the electric current flowing in a single unit cell of the structure. The periodicity of the structure is accounted for by using an efficiently calculated periodic Green's function. The loss is modeled by resistive boundary condition. The integral equation is solved by the method of moments using subdomain basis functions. The generalized scattering matrix is calculated and the propagating reflection coefficients are plotted as a function of frequency for various structures. The oblique scattering from one-dimensional arrays of strips is examined for various configurations of unit cells and various resistances. A depolarizing effect of the structure is found to be a function of incident angle and symmetry in the unit cell. The reflection from two-dimensional arrays of plates connected to form slabs of zigzag plates and honeycomb is also examined.

  15. Further investigations of underground resistivity structures in coastal areas using grounded-source airborne electromagnetics

    NASA Astrophysics Data System (ADS)

    Ito, Hisatoshi; Mogi, Toru; Jomori, Akira; Yuuki, Youichi; Kiho, Kenzo; Kaieda, Hideshi; Suzuki, Koichi; Tsukuda, Kazuhiro; Allah, Sabry Abd

    2011-08-01

    Understanding geological and hydrogeological characteristics in coastal areas is an issue of paramount importance considering its socio-economic relevance, whereas, to date, limited information has been acquired due to the lack of suitable survey methods. We have conducted an airborne electromagnetic survey in an alluvial coastal plain, Kujukuri, in southeast Japan, to examine the effectiveness of elucidating the subsurface electric-resistivity structure both on land and offshore. Our approach was to use a grounded electrical dipole source and a helicopter-towed magnetic field receiver. Repeated surveys both at high and low tides revealed that a reliable resistivity structure is available to a depth of 300-350 m in coastal areas where shallow (˜5 m deep) water prevails.

  16. The formation of filamentary sublimate residues (FSR) from mineral grains

    NASA Technical Reports Server (NTRS)

    Storrs, A. D.; Fanale, F. P.; Saunders, R. S.; Stephens, J. B.

    1988-01-01

    The significant interparticle forces observed between solar system dust grains upon desorption or sublimation of excess volatiles in simulated Martian or cometary environments are presently investigated, in order to more precisely define these mechanisms and to simulate the types of deposits thereby formed. Some classes of phyllosilicate mineral grains are noted to bond together to form a highly porous filamentary sublimate residue (FSR) exhibiting an exceptionally high tensile strength for its density; this may be important in its control of erosion and sublimation in Martian and cometary environments. It is concluded that FSR formation from clean mineral grains in water ice may be important in the formation of the Martian polar layered terrain.

  17. The Electrical Characteristics of a Filamentary Dielectric Barrier Discharge

    SciTech Connect

    Tay, W. H.; Yap, S. L.; Wong, C. S.

    2010-07-07

    The electrical characteristics of a filamentary dielectric barrier discharge using parallel-plate electrodes geometry were statistically studied. The DBD's system was powered by a 50 Hz power supply and operated at atmospheric pressure. The influence of the air gap and position of dielectric on the discharge had been investigated. It was found that the air gap distance and position of dielectric had significant influence on the discharge current pulse. The results showed that discharge with large distance between the high voltage electrode and the dielectric would generate higher current pulses during the positive cycle. The discharge energy of single pulse was also determined.

  18. A spiral passive electromagnetic sensor (SPES) for wireless and wired structural health monitoring

    NASA Astrophysics Data System (ADS)

    Iervolino, Onorio; Meo, Michele

    2016-04-01

    A major goal of structural health monitoring (SHM) in the past decade has been to improve crack detection and monitoring while reducing maintenance and installation costs. This would normally require placing many sensors over a large area, powering and interrogating them. On the other hand, operational aspects such as the temperature effects, battery life, and weight penalties have fundamental roles in the sensor design. In addition, small dimension of the sensors, low cost, and non-contact measurement system for data retrieval are very often required. We present a non-destructive evaluation/structural health monitoring (NDE/SHM) sensor that can be remotely interrogated without any wiring for data transmission or power supply. A spiral passive electromagnetic sensor (SPES) was designed and fabricated. The sensor is a planar 2D inductor circuit of scalable size that resonates at a characteristic frequency when exposed to an electromagnetic field. The specific frequency is dependent on the inductance of the inductor, its parasitic capacitance and resistance, and the electrical properties of the surrounding area. A change in a material’s permittivity or permeability due to damage can be sensed through the SPES device. The sensor was tested by using a passive wireless resonant telemetry scheme and a wired interrogation method. Both conductive (i.e. carbon fiber) and non-conductive (i.e. fiber glass) structures were monitored showing very promising capabilities and accuracy in detecting defects/damage in composite structures. The use of the proposed sensor eliminates the need for on-board power and exposed interconnects, reduces the instrumentation mass and volume, increases the reliability due to the continuous operation even in case of a damaged sensor, and increases the life of the device.

  19. Advanced 3D electromagnetic and particle-in-cell modeling on structured/unstructured hybrid grids

    SciTech Connect

    Seidel, D.B.; Pasik, M.F.; Kiefer, M.L.; Riley, D.J.; Turner, C.D.

    1998-01-01

    New techniques have been recently developed that allow unstructured, free meshes to be embedded into standard 3-dimensional, rectilinear, finite-difference time-domain grids. The resulting hybrid-grid modeling capability allows the higher resolution and fidelity of modeling afforded by free meshes to be combined with the simplicity and efficiency of rectilinear techniques. Integration of these new methods into the full-featured, general-purpose QUICKSILVER electromagnetic, Particle-In-Cell (PIC) code provides new modeling capability for a wide variety of electromagnetic and plasma physics problems. To completely exploit the integration of this technology into QUICKSILVER for applications requiring the self-consistent treatment of charged particles, this project has extended existing PIC methods for operation on these hybrid unstructured/rectilinear meshes. Several technical issues had to be addressed in order to accomplish this goal, including the location of particles on the unstructured mesh, adequate conservation of charge, and the proper handling of particles in the transition region between structured and unstructured portions of the hybrid grid.

  20. Structural and ultrastructural study of rat liver influenced by electromagnetic radiation.

    PubMed

    Holovská, K; Almášiová, V; Cigánková, V; Beňová, K; Račeková, E; Martončíková, M

    2015-01-01

    Mobile communication systems are undoubtedly an environmental source of electromagnetic radiation (EMR). There is an increasing concern regarding the interactions of EMR with the humans. The aim of this study was to examine the effects of EMR on Wistar rat liver. Mature rats were exposed to electromagnetic field of frequency 2.45 GHz and mean power density of 2.8 mW/cm2 for 3 h/d for 3 wk. Samples of the liver were obtained 3 h after the last irradiation and processed histologically for light and transmission electron microscopy. Data demonstrated the presence of moderate hyperemia, dilatation of liver sinusoids, and small inflammatory foci in the center of liver lobules. Structure of hepatocytes was not altered and all described changes were classified as moderate. Electron microscopy of hepatocytes revealed vesicles of different sizes and shapes, lipid droplets, and proliferation of smooth endoplasmic reticulum. Occasionally necrotizing hepatocytes were observed. Our observations demonstrate that EMR exposure produced adverse effects on rat liver. PMID:25734762

  1. Towards 3D and Multilayer Electromagnetic Metamaterials Structures in the THz Range

    NASA Astrophysics Data System (ADS)

    Casse, B. D. F.; Moser, H. O.; Lee, J. W.; Inglis, S.; Bahou, M.; Jian, L. K.

    2007-03-01

    V. G. Veselago predicted that left-handed materials would exhibit a plethora of unusual effects such as a negative index of refraction as used in Snell's law, a reverse Doppler and Cerenkov effect. This novel class of materials, following Pendry's recipes, can potentially restore evanescent waves to focus subwavelength details in an image. Micron-size electromagnetic metamaterials (EM^3) structures which exist so far were produced and characterized as single layer structures. Furthermore the structures were produced with a low yield. In the first part of the talk, we will present techniques for producing copious amount of EM^3 chips via the LIGA process using Synchrotron radiation and demonstrate assembly of the first multilayer THz EM^3 structures. The planar micro- or nanoEM^3 produced so far are also highly anisotropic. Recently, we proposed schemes to produce more isotropic structures, within the same matrix, via tilted X-ray exposures that were introduced in the LIGA process years ago. In the second part of the talk, we will show the results of microfabrication of nearly 3D EM^3 structures for the THz range.

  2. Investigations of the structure and electromagnetic interactions of few-body systems

    SciTech Connect

    Lehman, D.R.; Haberzettl, H.; Maximon, L.C.; Parke, W.C.

    1992-07-01

    In order to make it easy for the reader to see the specific research carried out and the progress made, the following report of progress is done by topic. Each item has a format layout of Topic, Investigators, Objective, Significance, and Description of Progress, followed at the end by the relevant references. As is clear from the topics listed, the emphasis of the George Washington University (GWU) theory group has been on the structure and electromagnetic interactions of few-body nuclei. Both low- and intermediate-energy electromagnetic disintegration of these nuclei is considered. When the excitation energy of the target nucleus is low, the aim has been to handle the continuum part of the theoretical work numerically with no approximations, that is, by means of full three- or four-body dynamics. When structure questions axe the issue, numerically accurate calculations axe always carried through, limited only by the underlying two-body or three-body interactions used as input. Implicit in our work is the question of how far one can go within the traditional nuclear physics framework, i.e., nucleons and mesons in a nonrelativistic setting. Our central goal is to carry through state-of-the-art fewbody calculations that wig serve as a means of determining at what point standard nuclear physics requires quark degrees of freedom in order to understand the phenomena in question. So far, in the problems considered, there has been no evidence of the necessity to go beyond the traditional approach, though we always keep in mind that possibility. As our work is involved with questions in the intermediate-energy realm, moving from a nonrelativistic framework to a relativistic one is always a consideration. Currently, for the problems that have been pursued in this domain of energy, the issues concern far more the mechanisms of the reactions and structural questions than the need to move to relativistic dynamics.

  3. Electromagnetic and thermal properties of three-dimensional printed multilayered nano-carbon/poly(lactic) acid structures

    NASA Astrophysics Data System (ADS)

    Paddubskaya, A.; Valynets, N.; Kuzhir, P.; Batrakov, K.; Maksimenko, S.; Kotsilkova, R.; Velichkova, H.; Petrova, I.; Biró, I.; Kertész, K.; Márk, G. I.; Horváth, Z. E.; Biró, L. P.

    2016-04-01

    A new type of light-weight material produced by 3D printing consisting of nano-carbon doped polymer layer followed by a dielectric polymer layer is proposed. We performed temperature dependent characterization and measured the electromagnetic (EM) response of the samples in the GHz and THz range. The temperature dependent structural characteristics, crystallization, and melting were observed to be strongly affected by the presence and the number of nano-carbon doped layers in the sandwich structure. The electromagnetic measurements show a great potential of such a type of periodic material for electromagnetic compatibility applications in microwave frequency range. Sandwich structures containing only two nano-carbon layers already become not transparent to the microwaves, giving an electromagnetic interference shielding efficiency at the level of 8-15 dB. A sandwich consisting of one nano-carbon doped and one polymer layer is opaque for THz radiation, because of 80% of absorption. These studies serve as a basis for design and realization of specific optimal geometries of meta-surface type with the 3D printing technique, in order to reach a high level of electromagnetic interference shielding performance for real world EM cloaking and EM ecology applications.

  4. Particle simulation of filamentary formation in dielectric barrier discharge.

    NASA Astrophysics Data System (ADS)

    Fan, Weili; Dong, Lifang

    2015-11-01

    Dielectric barrier discharge (DBD) is well known for its extensive industrial applications. Recently, new attention has been paid to DBD as a system of rich nonlinear dynamics to study the self-organized filamentary patterns. Though a number of experimental studies have been implemented, the involved physics is still not completely clear, partially due to the limitation of the available space and time-resolved diagnostics. Computer simulation has proven to be an effective tool to give insights into the discharge mechanism. So far, most simulations presented are based on fluid models. However, since the plasma is non-equilibrium in DBD where the particle velocities may deviate from the Maxwellian distribution, self-consistent kinetic simulations are required. In this paper, two successive filamentary discharges in DBD have been studied by use of two-dimensional particle-in-cell simulation with Monte Carlo collisions included (PIC-MCC). The formation of multiple filaments and the involved electric fields, electric potentials, plasma densities, and particle temperatures are presented. Results show that both of the surface charges and space charges play significant roles in the discharges. The total electric field in the gas gap has been completely reversed before the ac voltage hit zero, due to the accumulation of the surface charges, which triggers the next discharge. The space charges always exist between two successive discharges, which provides the `seed charges' for reignition of the filaments. This modeling has revealed significant details of the discharge behaviors, which greatly improved our understanding of DBD mechanisms.

  5. Self-organization of ULF electromagnetic wave structures in the shear flow driven dissipative ionosphere

    NASA Astrophysics Data System (ADS)

    Aburjania, G.; Chargazia, K.; Kharshiladze, O.; Zimbardo, G.

    2014-08-01

    This work is devoted to investigation of nonlinear dynamics of planetary electromagnetic (EM) ultra-low-frequency wave (ULFW) structures in the rotating dissipative ionosphere in the presence of inhomogeneous zonal wind (shear flow). Planetary EM ULFW appears as a result of interaction of the ionospheric medium with the spatially inhomogeneous geomagnetic field. The shear flow driven wave perturbations effectively extract energy of the shear flow increasing own amplitude and energy. These perturbations undergo self organization in the form of the nonlinear solitary vortex structures due to nonlinear twisting of the perturbation's front. Depending on the features of the velocity profiles of the shear flows the nonlinear vortex structures can be either monopole vortices, or dipole vortex, or vortex streets and vortex chains. From analytical calculation and plots we note that the formation of stationary nonlinear vortex structure requires some threshold value of translation velocity for both non-dissipation and dissipation complex ionospheric plasma. The space and time attenuation specification of the vortices is studied. The characteristic time of vortex longevity in dissipative ionosphere is estimated. The long-lived vortices transfer the trapped medium particles, energy and heat. Thus they represent structural elements of turbulence in the ionosphere.

  6. Improved Electromagnetic Interference Shielding Properties of MWCNT–PMMA Composites Using Layered Structures

    PubMed Central

    2009-01-01

    Electromagnetic interference (EMI) shielding effectiveness (SE) of multi-walled carbon nanotubes–polymethyl methacrylate (MWCNT–PMMA) composites prepared by two different techniques was measured. EMI SE up to 40 dB in the frequency range 8.2–12.4 GHz (X-band) was achieved by stacking seven layers of 0.3-mm thick MWCNT–PMMA composite films compared with 30 dB achieved by stacking two layers of 1.1-mm thick MWCNT–PMMA bulk composite. The characteristic EMI SE graphs of the composites and the mechanism of shielding have been discussed. SE in this frequency range is found to be dominated by absorption. The mechanical properties (tensile, flexural strength and modulus) of the composites were found to be comparable or better than the pure polymer. The studies therefore show that the composite can be used as structurally strong EMI shielding material. PMID:20596500

  7. Investigation of the electromagnetic structure of. eta. and. eta. prime mesons by two-photon interactions

    SciTech Connect

    Aihara, H.; Alston-Garnjost, M.; Avery, R.E.; Barbaro-Galtieri, A.; Barker, A.R.; Barnett, B.A.; Bauer, D.A.; Bay, A.; Bobbink, G.J.; Buchanan, C.D.; Buijs, A.; Caldwell, D.O.; Chao, H.; Chun, S.; Clark, A.R.; Cowan, G.D.; Crane, D.A.; Dahl, O.I.; Daoudi, M.; Derby, K.A.; Eastman, J.J.; Eberhard, P.H.; Edberg, T.K.; Eisner, A.M.; Erne, F.C.; Fairfield, K.H.; Hauptman, J.M.; Hofmann, W.; Hylen, J.; Kamae, T.; Kaye, H.S.; Kenney, R.W.; Khacheryan, S.; Kofler, R.R.; Langeveld, W.G.J.; Layter, J.G.; Lin, W.T.; Linde, F.L.; Loken, S.C.; Lu, A.; Lynch, G.R.; Madaras, R.J.; Magnuson, B.D.; Masek, G.E.; Mathis, L.G.; Matthews, J.A.J.; Maxfield, S.J.; Miller, E.S.; Moses, W.; Nygren, D.R.; Oddone, P.J.; Paar, H.P.; Park, S.K.; Pellett, D.E.; Pripstein, M.; Ronan, M.T.; Ross, R.R.; Rouse, F.R.; Schwitkis, K.A.; Sens, J.C.; Shapiro, G.; Shen, B.C.; Smith, J.R.; Steinman, J.S.; Stephens, R.W.; Stevenson, M.L.; Stork, D.H.; Strauss, M.G.; Sullivan, M.K.; Takahashi, T.; Toutounchi, S.; van Tyen, R.; TPC /Two-Gamma Collaboration

    1990-01-08

    The TPC/Two-Gamma facility at the SLAC {ital e}{sup +}{ital e}{sup {minus}} storage ring PEP was used to study the reactions {gamma}{gamma}{sup *}{r arrow}{eta} and {gamma}{gamma}{sup *}{r arrow}{eta}{prime}. The {eta}{gamma}{sup *}{gamma} and {eta}{prime}{gamma}{sup *}{gamma} transition form factors were measured as functions of {ital Q}{sup 2}, the negative of the invariant mass squared of the tagged photon, in the range 0.1{lt}{ital Q}{sup 2}{lt}7 GeV{sup 2}. These determinations of the electromagnetic structure of the {eta} and {eta}{prime} mesons are consistent with both vector-meson dominance and QCD. They also provide new measurements of the pseudoscalar mixing angle and decay constants.

  8. Finite element modeling of magnetic compression using coupled electromagnetic-structural codes

    SciTech Connect

    Hainsworth, G.; Leonard, P.J.; Rodger, D.; Leyden, C.

    1996-05-01

    A link between the electromagnetic code, MEGA, and the structural code, DYNA3D has been developed. Although the primary use of this is for modelling of Railgun components, it has recently been applied to a small experimental Coilgun at Bath. The performance of Coilguns is very dependent on projectile material conductivity, and so high purity aluminium was investigated. However, due to its low strength, it is crushed significantly by magnetic compression in the gun. Although impractical as a real projectile material, this provides useful benchmark experimental data on high strain rate plastic deformation caused by magnetic forces. This setup is equivalent to a large scale version of the classic jumping ring experiment, where the ring jumps with an acceleration of 40 kG.

  9. Making structured metals transparency for broadband and wide-incidence-angle electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Fan, Renhao; Peng, Ruwen; Huang, Xianrong; Wang, Mu

    2014-03-01

    Very recently, we have demonstrated that one-dimensional metallic gratings can become transparent and completely antireflective for extremely broadband electromagnetic (EM) waves under oblique incidence. However, the oblique-incidence geometry, is inconvenient for the technological applications. To overcome this drawback, here we instead use oblique metal gratings with optimal tilt angles to achieve normal-incidence broadband transparence for EM waves. Further we use two-dimensional periodic metallic cuboids to achieve broadband and broad-angle high transmission and antireflection. By introducing such metallic cuboids arrays into silicon solar cells, we find that high performance of light trapping in the cells can be obtained with a significant enhancement of the ultimate quantum efficiency. The structured metals, which achieve broadband and broad-angle high transmission for EM waves, may have many other potential applications, such as transparent conducting panels, white-beam polarizers, and stealth objects.

  10. Improved Electromagnetic Interference Shielding Properties of MWCNT-PMMA Composites Using Layered Structures.

    PubMed

    Pande, Shailaja; Singh, Bp; Mathur, Rb; Dhami, Tl; Saini, P; Dhawan, Sk

    2009-01-01

    Electromagnetic interference (EMI) shielding effectiveness (SE) of multi-walled carbon nanotubes-polymethyl methacrylate (MWCNT-PMMA) composites prepared by two different techniques was measured. EMI SE up to 40 dB in the frequency range 8.2-12.4 GHz (X-band) was achieved by stacking seven layers of 0.3-mm thick MWCNT-PMMA composite films compared with 30 dB achieved by stacking two layers of 1.1-mm thick MWCNT-PMMA bulk composite. The characteristic EMI SE graphs of the composites and the mechanism of shielding have been discussed. SE in this frequency range is found to be dominated by absorption. The mechanical properties (tensile, flexural strength and modulus) of the composites were found to be comparable or better than the pure polymer. The studies therefore show that the composite can be used as structurally strong EMI shielding material. PMID:20596500

  11. Electromagnetic metamaterial-inspired band gap and perfect transmission in semiconductor and graphene-based electronic and photonic structures

    NASA Astrophysics Data System (ADS)

    Mahdy, M. R. C.; Al Sayem, Ayed; Shahriar, Arif; Shawon, Jubayer; Al-Quaderi, Golam Dastegir; Jahangir, Ifat; Matin, M. A.

    2016-04-01

    In this article, at first we propose a unified and compact classification of single negative electromagnetic metamaterial-based perfect transmission unit cells. The classes are named as: type-A, -B and -C unit cells. Then based on the classification, we have extended these ideas in semiconductor and graphene regimes. For type-A: Based on the idea of electromagnetic Spatial Average Single Negative bandgap, novel bandgap structures have been proposed for electron transmission in semiconductor heterostructures. For type-B: with dielectric-graphene-dielectric structure, almost all angle transparency is achieved for both polarizations of electromagnetic wave in the terahertz frequency range instead of the conventional transparency in the microwave frequency range. Finally the application of the gated dielectric-graphene-dielectric has been demonstrated for the modulation and switching purpose.

  12. In-plane transport anisotropy in BSCCO-Ag multi-filamentary tapes

    NASA Astrophysics Data System (ADS)

    Borroto, A.; García-Gordillo, A. S.; Del Río, L.; Arronte, M.; Altshuler, E.

    2015-07-01

    Composite structures such as high-Tc multi-filamentary tapes display a complex anisotropy arising from the combination of the ‘intrinsic’ anisotropy of the Bi-2223 grains, and that associated to the superconducting phase distribution in the superconductor-metal composite, as well as cracks and other defects. In this paper we characterize the ‘in-plane’ anisotropy of BSCCO-Ag tapes, i.e., the difference between the transport properties along the longitudinal axis and those along the transverse direction also lying on the wide face of the tape. In particular, we demonstrate that the dissipation associated to transport along the transverse direction approaches that of the longitudinal direction as the temperature or the current increases, which may be relevant to transport applications in situations where the superconducting properties have significantly degraded.

  13. The effect of particles and electromagnetic waves on vortex structures in the atmosphere and the ionosphere

    NASA Astrophysics Data System (ADS)

    Izhovkina, N. I.

    2015-05-01

    The formation of vortex structures in an inhomogeneous gyrotropic atmosphere was stochastically determined. Atmospheric gyrotropy is induced by the Coriolis force acting as the Earth rotates and the motion of charged particles in the geomagnetic field. Vortices of a plasma nature are observed in the atmosphere. The electric field of such plasma vortices originates within the fields of pressure gradients of a mosaic cell topology upon the ionization of particles. It is shown that waves in a neutral atmosphere, electric fields, and electromagnetic waves affect the stability of vortex structures. Wave signals from anthropogenic sources and smog may stimulate local precipitation upon the passage of a cloud front and weaken or strengthen vortex structures. The plasma vortex may capture charged particles of different masses. The charge separation in plasma vortex structures is driven by the polarization drift at the decay of electric fields. The self-focusing of plasma vortices upon the condensation of moisture in the atmospheric cloud cover leads to an increase in the energy of vortices.

  14. Filamentary Structure of the Orion A Molecular Cloud

    NASA Astrophysics Data System (ADS)

    Suri, S.; Schilke, P.; Sánchez-Monge, Á.

    2016-05-01

    Interstellar filaments pervade molecular clouds on all scales providing a bridge between the gas with relatively low densities and the dense clumps. In this work, we characterize various physical properties of filaments in the Orion A molecular cloud using preliminary datasets from the CARMA Orion project. We use an automated filament finding algorithm, DisPerSE, on 3D datacubes, and custom characterization algorithms.

  15. Electromagnetic structure of the proton within the CP-violation hypothesis

    SciTech Connect

    Krutov, A. F. Kudinov, M. Yu.

    2013-11-15

    The so-called non-Rosenbluth behavior of the proton electromagnetic form factors can be explained within the hypothesis of CP violation in electromagnetic processes involving composite systems of strongly interacting particles. It is shown that this hypothesis leads to the appearance of an additional, anapole, form factor of the proton. The proton electromagnetic form factors, including the anapole form factor, are estimated on the basis of experimental data on elastic electron-proton scattering.

  16. Nonlinear Planetary Electromagnetic Vortex Structures in the Ionospheric F-Layer

    SciTech Connect

    Aburjaniya, G. D.; Khantadze, A. G.; Kharshiladze, O. A.

    2002-07-15

    A study is made of the dynamics of planetary-scale electromagnetic waves in the F-layer of the ionosphere. It is shown that, in this layer, a new branch of large-scale magneto-ionospheric wave perturbations is generated under the action of the latitudinal variations of the geomagnetic field, which are a constant property of the ionosphere. The waves propagate along the parallels with phase velocities of tens to hundreds of km/s. The pulsations of the geomagnetic field in the waves can be as strong as several tens of nT. A possible self-localization effect is revealed: these waves may form nonlinear localized solitary vortices moving either westward or eastward along the parallels with velocities much higher than the phase velocities of the linear waves. The characteristic dimension of a vortex is about 10{sup 4} km or even larger. The magnetic fields generated by vortex structures are one order of magnitude stronger than those in linear waves. The vortices are long-lived formations and may be regarded as elements of strong structural turbulence in the ionosphere. The properties of the wave structures under investigation are very similar to those of ultralow-frequency perturbations observed experimentally in the ionosphere at middle latitudes.

  17. Rayleigh-Taylor-Induced Electromagnetic Fields in Laser-Produced Plasmas

    NASA Astrophysics Data System (ADS)

    Manuel, Mario J.-E.

    Spontaneous electromagnetic fields can be important to the dynamic evolution of a plasma by directing heat flow as well as providing additional pressures on the conducting fluids through the Lorentz force. Electromagnetic fields are predicted to affect fluid behavior during the core-collapse of supernovae through generation of fields due to hydrodynamic instabilities. In the coronae of stars, self-generated magnetic fields lead to filamentary structure in the hot plasma. Recent experiments by Gregori et al. investigated sources of protogalactic magnetic fields generated by laser-produced shock waves. In inertial confinement fusion experiments, self-generated electromagnetic fields can also play a role and have recently become of great interest to the community. Present day laser facilities provide a unique opportunity to study spontaneous field-generation in these extreme environments under controlled conditions. Instability-induced electromagnetic fields were investigated using a novel monoenergetic-proton radiography system. Fusion protons generated by an 'exploding-pusher' implosion were used to probe laser-irradiated plastic foils with various preimposed surface perturbations. Imaging protons are sensitive to electromagnetic fields and density modulations in the plasma through the Lorentz force and Coulomb collisions, respectively. Corresponding x-ray radiographs of these targets provided mass density distributions and Coulomb effects on protons were assessed using a Monte Carlo code written using the Geant4 framework. Proton fluence distributions were recorded on CR-39 detectors and Fourier analyzed to infer path-integrated field strengths. Rayleigh-Taylor (RT) growth of preimposed surface perturbations generated magnetic fields by the RT-induced Biermann battery and were measured for the first time. Good data were obtained during linear growth and when compared to ideal calculations, demonstrated that field diffusion near the source played an important role

  18. Kinetic description of the 3D electromagnetic structures formation in flows of expanding plasma coronas. Part 1: General

    NASA Astrophysics Data System (ADS)

    Gubchenko, V. M.

    2015-12-01

    In part I of the work, the physical effects responsible for the formation of low-speed flows in plasma coronas, coupled with formation of coronas magnetosphere-like structures, are described qualitatively. Coronal domain structures form if we neglect scales of spatial plasma dispersion: high-speed flows are accumulated in magnetic tubes of the open domains, while magnetic structures and low-speed flows are concentrated within boundaries of domains. The inductive electromagnetic process occurring in flows of the hot collisionless plasma is shown to underlie the formation of magnetosphere-like structures. Depending on the form of the velocity distribution function of particles (PDF), a hot flow differently reveals its electromagnetic properties, which are expressed by the induction of resistive and diamagnetic scales of spatial dispersion. These determine the magnetic structure scales and structure reconstruction. The inductive electromagnetic process located in lines of the plasma nontransparency and absorption, in which the structures of excited fields are spatially aperiodic and skinned to the magnetic field sources. The toroidal and dipole magnetic sources of different configurations are considered for describing the corona structures during the solar maximum and solar minimum.

  19. Filamentary Environment and Mass Measurements of Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Noh, Yookyung

    2013-01-01

    Galaxy clusters reside at the nodes of cosmic web and are fed matter along the filaments. This filamentary environment is important to understand the formation and the evolution of galaxy clusters, and is also inevitably included when we observe them. This latter effect generates projection effects on cluster observables. Reducing errors in measuring cluster masses is of interest since a cluster's mass is a crucial property for many areas of astrophysics and cosmology. We study the filamentary environment surrounding galaxy clusters and its effect on the cluster mass measurements by constructing a filament catalogue in a high-resolution N-body simulation. We consider the statistical properties of filaments around galaxy clusters. Not only filaments but also the majority of mass in halos and number of galaxies in the local environment of clusters tends to lie on planes which are mostly aligned with each other and with the cluster's major axis. We show that this local planar environment can be one source of projection effects that bias cluster mass measurements. Sources of mass measurement scatters are shared between different mass measurement methods, generating correlations in their respective scatters. This correlated scatter mitigates the complementary information of cluster mass measurements in multi-wavelength observations. We study the scatter by calculating correlations/covariances between them and performing Principal Component Analysis (PCA). As expected, the scatter from different techniques tends to be correlated. We find that the combination of scatters which dominates the variance of all the measurements is common for the majority of clusters. Its dominance tends to be enhanced when observing along the cluster's major axis. We also find shared trends among cluster mass scatter, intrinsic and environmental properties of clusters using PCA.

  20. Electromagnetic fields as structure-function zeitgebers in biological systems: environmental orchestrations of morphogenesis and consciousness

    PubMed Central

    Rouleau, Nicolas; Dotta, Blake T.

    2014-01-01

    Within a cell system structure dictates function. Any interaction between cells, or a cell and its environment, has the potential to have long term implications on the function of a given cell and emerging cell aggregates. The structure and function of cells are continuously subjected to modification by electrical and chemical stimuli. However, biological systems are also subjected to an ever-present influence: the electromagnetic (EM) environment. Biological systems have the potential to be influenced by subtle energies which are exchanged at atomic and subatomic scales as EM phenomena. These energy exchanges have the potential to manifest at higher orders of discourse and affect the output (behavior) of a biological system. Here we describe theoretical and experimental evidence of EM influence on cells and the integration of whole systems. Even weak interactions between EM energies and biological systems display the potential to affect a developing system. We suggest the growing literature of EM effects on biological systems has significant implications to the cell and its functional aggregates. PMID:25426035

  1. Experimental Investigation on Electromagnetic Attenuation by Low Pressure Radio-Frequency Plasma for Cavity Structure

    NASA Astrophysics Data System (ADS)

    He, Xiang; Zhang, Yachun; Chen, Jianping; Chen, Yudong; Zeng, Xiaojun; Yao, Hong; Tang, Chunmei

    2016-01-01

    This paper reports on an experiment designed to test electromagnetic (EM) attenuation by radio-frequency (RF) plasma for cavity structures. A plasma reactor, in the shape of a hollow cylinder, filled with argon gas at low pressure, driven by a RF power source, was produced by wave-transmitting material. The detailed attenuations of EM waves were investigated under different conditions: the incident frequency is 1-4 GHz, the RF power supply is 13.56 MHz and 1.6-3 kW, and the argon pressure is 75-200 Pa. The experimental results indicate that 5-15 dB return loss can be obtained. From a first estimation, the electron density in the experiment is approximately (1.5-2.2) × 1016 m-3 and the collision frequency is about 11-30 GHz. The return loss of EM waves was calculated using a finite-difference time-domain (FDTD) method and it was found that it has a similar development with measurement. It can be confirmed that RF plasma is useful in the stealth of cavity structures such as jet-engine inlet. supported by National Natural Science Foundation of China (No. 51107033) and the Fundamental Research Funds for the Central Universities of China (No. 2013B33614)

  2. Design of UWB monopole antenna with dual notched bands using one modified electromagnetic-bandgap structure.

    PubMed

    Liu, Hao; Xu, Ziqiang

    2013-01-01

    A modified electromagnetic-bandgap (M-EBG) structure and its application to planar monopole ultra-wideband (UWB) antenna are presented. The proposed M-EBG which comprises two strip patch and an edge-located via can perform dual notched bands. By properly designing and placing strip patch near the feedline, the proposed M-EBG not only possesses a simple structure and compact size but also exhibits good band rejection. Moreover, it is easy to tune the dual notched bands by altering the dimensions of the M-EBG. A demonstration antenna with dual band-notched characteristics is designed and fabricated to validate the proposed method. The results show that the proposed antenna can satisfy the requirements of VSWR < 2 over UWB 3.1-10.6 GHz, except for the rejected bands of the world interoperability for microwave access (WiMAX) and the wireless local area network (WLAN) at 3.5 GHz and 5.5 GHz, respectively. PMID:24170984

  3. Design of UWB Monopole Antenna with Dual Notched Bands Using One Modified Electromagnetic-Bandgap Structure

    PubMed Central

    Xu, Ziqiang

    2013-01-01

    A modified electromagnetic-bandgap (M-EBG) structure and its application to planar monopole ultra-wideband (UWB) antenna are presented. The proposed M-EBG which comprises two strip patch and an edge-located via can perform dual notched bands. By properly designing and placing strip patch near the feedline, the proposed M-EBG not only possesses a simple structure and compact size but also exhibits good band rejection. Moreover, it is easy to tune the dual notched bands by altering the dimensions of the M-EBG. A demonstration antenna with dual band-notched characteristics is designed and fabricated to validate the proposed method. The results show that the proposed antenna can satisfy the requirements of VSWR < 2 over UWB 3.1–10.6 GHz, except for the rejected bands of the world interoperability for microwave access (WiMAX) and the wireless local area network (WLAN) at 3.5 GHz and 5.5 GHz, respectively. PMID:24170984

  4. Framing the structural role of mathematics in physics lectures: A case study on electromagnetism

    NASA Astrophysics Data System (ADS)

    Karam, Ricardo

    2014-06-01

    Physics education research has shown that students tend to struggle when trying to use mathematics in a meaningful way in physics (e.g., mathematizing a physical situation or making sense of equations). Concerning the possible reasons for these difficulties, little attention has been paid to the way mathematics is treated in physics instruction. Starting from an overall distinction between a technical approach, which involves an instrumental (tool-like) use of mathematics, and a structural one, focused on reasoning about the physical world mathematically, the goal of this study is to characterize the development of the latter in didactic contexts. For this purpose, a case study was conducted on the electromagnetism course given by a distinguished physics professor. The analysis of selected teaching episodes with the software Videograph led to the identification of a set of categories that describe different strategies used by the professor to emphasize the structural role of mathematics in his lectures. As a consequence of this research, an analytic tool to enable future comparative studies between didactic approaches regarding the way mathematics is treated in physics teaching is provided.

  5. Spiral Passive Electromagnetic Sensor (SPES) for composite structural changes in aircraft structures

    NASA Astrophysics Data System (ADS)

    Iervolino, Onorio; Meo, Michele

    2016-04-01

    A major goal of structural health monitoring (SHM) is to provide accurate and responsive detection and monitoring of flaws. This research work reports an investigation of SPES sensors for damage detection, investigating different sensor sizes and how they affect the sensor's signal. A sensor able to monitor structural change that can be remotely interrogated and does not need a power supply is presented in this work. The SPES-sensor presents the great advantage of monitoring conductive and non-conductive structures such as fiberglass-reinforced composites (FRC) and carbon fiber-reinforced polymers (CFRP). Any phenomena that affect the magnetic field of the SPES can be detected and monitored. A study was conducted to investigate the capability of sensor to give information on structural changes, simulated by the presence of an external mass placed in the proximity of sensor. Effect of different positions of the SPES within the sample, and how to extend the area of inspection using multiple sensors was investigated. The sensor was tested embedded in the samples, simulating the structural change on both sides of the sample. In both configurations the sensor described herein demonstrated a great potential to monitor structural changes.

  6. Computational modeling of the electromagnetic characteristics of carbon fiber-reinforced polymer composites with different weave structures

    NASA Astrophysics Data System (ADS)

    Hassan, A. M.; Douglas, J. F.; Garboczi, E. J.

    2014-02-01

    Carbon fiber reinforced polymer composites (CFRPC) are of great interest in the aerospace and automotive industries due to their exceptional mechanical properties. Carbon fibers are typically woven and inter-laced perpendicularly in warps and wefts to form a carbon fabric that can be embedded in a binding matrix. The warps and wefts can be interlaced in different patterns called weaving structures. The primary weaving structures are the plain, twill, and satin weaves, which give different mechanical composite properties. The goal of this work is to computationally investigate the dependence of CFRPC microwave and terahertz electromagnetic characteristics on weave structure. These bands are good candidates for the Nondestructive Evaluation (NDE) of CFRPC since their wavelengths are comparable to the main weave features. 3D full wave electromagnetic simulations of several different weave models have been performed using a finite element (FEM) simulator, which is able to accurately model the complex weave structure. The computational experiments demonstrate that the reflection of electromagnetic waves from CFRPC depend sensitively on weave structure. The reflection spectra calculated in this work can be used to identify the optimal frequencies for the NDE of each weave structure.

  7. Integrated design method of MR damper and electromagnetic induction system for structural control

    NASA Astrophysics Data System (ADS)

    Lee, Heon-Jae; Moon, Seok-Jun; Jung, Hyung-Jo; Huh, Young-Cheol; Jang, Dong-Doo

    2008-03-01

    Magnetorheological (MR) dampers are one of the most advantageous control devices for civil engineering applications to natural hazard mitigation due to many good features such as small power requirement, reliability, and low price to manufacture. To reduce the responses of a structural system by using MR dampers, a control system including a power supply, control algorithm, and sensors is needed. The control system becomes complex, however, when a lot of MR dampers are applied to large-scale civil structures, such as cable-stayed bridges and high-rise buildings. Thus, it is difficult to install and/or maintain the MR damper-based control system. To overcome the above difficulties, a smart passive system was proposed, which is based on an MR damper system. The smart passive system consists of an MR damper and an electromagnetic induction (EMI) system that uses a permanent magnet and a coil. According to the Faraday law of induction, the EMI system that is attached to the MR damper can produce electric energy and the produced energy is applied to the MR damper to vary the damping characteristics of the damper. Thus, the smart passive system does not require any power at all. Besides the output of electric energy is proportional to input loads such as earthquakes, which means the smart passive system has adaptability by itself without any controller or sensors. In this paper, the integrated design method of a large-scale MR damper and Electromagnetic Induction (EMI) system is presented. Since the force of an MR damper is controllable by altering the input current generated from an EMI part, it is necessary to design an MR damper and an EMI part simultaneously. To do this, design parameters of an EMI part consisting of permanent magnet and coil as well as those of an MR damper consisting of a hydraulic-type cylinder and a magnetic circuit that controls the magnetic flux density in a fluid-flow path are considered in the integrated design procedure. As an example, a

  8. Scattering and Diffraction of Electromagnetic Radiation: An Effective Probe to Material Structure

    NASA Technical Reports Server (NTRS)

    Xu, Yu-Lin

    2016-01-01

    Scattered electromagnetic waves from material bodies of different forms contain, in an intricate way, precise information on the intrinsic, geometrical and physical properties of the objects. Scattering theories, ever deepening, aim to provide dependable interpretation and prediction to the complicated interaction of electromagnetic radiation with matter. There are well-established multiple-scattering formulations based on classical electromagnetic theories. An example is the Generalized Multi-particle Mie-solution (GMM), which has recently been extended to a special version ? the GMM-PA approach, applicable to finite periodic arrays consisting of a huge number (e.g., >>106) of identical scattering centers [1]. The framework of the GMM-PA is nearly complete. When the size of the constituent unit scatterers becomes considerably small in comparison with incident wavelength, an appropriate array of such small element volumes may well be a satisfactory representation of a material entity having an arbitrary structure. X-ray diffraction is a powerful characterization tool used in a variety of scientific and technical fields, including material science. A diffraction pattern is nothing more than the spatial distribution of scattered intensity, determined by the distribution of scattering matter by way of its Fourier transform [1]. Since all linear dimensions entered into Maxwell's equations are normalized by wavelength, an analogy exists between optical and X-ray diffraction patterns. A large set of optical diffraction patterns experimentally obtained can be found in the literature [e.g., 2,3]. Theoretical results from the GMM-PA have been scrutinized using a large collection of publically accessible, experimentally obtained Fraunhofer diffraction patterns. As far as characteristic structures of the patterns are concerned, theoretical and experimental results are in uniform agreement; no exception has been found so far. Closely connected with the spatial distribution of

  9. Acceleration of solar wind ions to 1 MeV by electromagnetic structures upstream of the Earth's bow shock

    NASA Astrophysics Data System (ADS)

    Stasiewicz, K.; Markidis, S.; Eliasson, B.; Strumik, M.; Yamauchi, M.

    2013-05-01

    We present measurements from the ESA/NASA Cluster mission that show in situ acceleration of ions to energies of 1 MeV outside the bow shock. The observed heating can be associated with the presence of electromagnetic structures with strong spatial gradients of the electric field that lead to ion gyro-phase breaking and to the onset of chaos in ion trajectories. It results in rapid, stochastic acceleration of ions in the direction perpendicular to the ambient magnetic field. The electric potential of the structures can be compared to a field of moguls on a ski slope, capable of accelerating and ejecting the fast running skiers out of piste. This mechanism may represent the universal mechanism for perpendicular acceleration and heating of ions in the magnetosphere, the solar corona and in astrophysical plasmas. This is also a basic mechanism that can limit steepening of nonlinear electromagnetic structures at shocks and foreshocks in collisionless plasmas.

  10. Effect of aluminum substitution on structural and electromagnetic properties of nanocrystalline MgCuMn ferrites

    SciTech Connect

    Ramesh, T. E-mail: ramanasarabu@gmail.com; Kumar, S. Senthil; Shinde, R. S.; Murthy, S. R.

    2015-06-24

    The effect of substitution of nonmagnetic Al{sup 3+} ions on the structural and electromagnetic properties were studied in nanocrystalline ferrite series of Mg{sub 0.8}Cu{sub 0.2}Al{sub x}Fe{sub 1.95-x}Mn{sub 0.05}O{sub 4} where x varies 0-0.4 in steps of 0.1. This series was synthesized by using microwave hydrothermal method. The nanocrystalline ferrite phase was observed at temperature 150°C/40 min. Synthesized powders were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The synthesized powders were densified using microwave sintering method at 950°C/40 min. The sintered samples were characterized using XRD. Surface morphology was observed by using field effective scanning electron microscopy (FESEM). The electrical and magnetic properties were measured at room temperature. These results led us to interfere that the values of d.c resistivity increases and dielectric constant, initial permeability, saturation magnetization and Curie temperature were observed to be decreased with the substitution of Al{sup 3+} ions with those of Fe{sup 3+}. The low dielectric and magnetic losses and low magnetization exhibited by aluminum substituted MgCuMn ferrites makes them find applications in microwave devices.

  11. Impact of Electromagnetic Stirring on Grain Structure of Electroslag Remelting Ingot

    NASA Astrophysics Data System (ADS)

    Wang, Qiang; Yan, Hongguang; Wang, Fang; Li, Baokuan

    2015-08-01

    A transient, two-dimensional axisymmetric model was developed to understand the effect of the electromagnetic stirring (EMS) on the grain morphology of the electroslag remelting ingot. The cellular automaton-finite element technique was employed to describe the nucleation and growth of the grain. The Joule heating and Lorentz force created by the current of the furnace, as well as the Lorentz force induced by the EMS device, are included. The effect of the EMS current on the grain structure was investigated using the model. A reasonable agreement between the experiment and simulation was obtained. The growth direction of the upper grain without the EMS is approximately 45° with respect to the vertical axis, while changes to the radial were caused by EMS. The grain was considerably refined by the EMS, and the average area of the grain decreased from 9.381 × 10-7 m2 to 6.781 × 10-7 m2 with the current of the EMS ranging from 0 A to 500 A. Both the local solidification time and second dendrite arm spacing decreased with the increasing stirring intensity. The metal pool depth, however, increased with the EMS, which definitely contributed to the macrosegregation formation. The upper ingot with EMS was darker than that without EMS in the experiment. The EMS technique should be used with caution.

  12. Electromagnetic emissions and fine structures observed near main ionospheric trough during geomagnetic storms and their interactions

    NASA Astrophysics Data System (ADS)

    Przepiórka, Dorota; Marek, Michał; Matyjasiak, Barbara; Rothkaehl, Hanna

    2016-04-01

    Geomagnetic conditions triggered by the solar activity affect the ionosphere, its fine and global structures. Very intense magnetic storms substantially change the plasma density, concentration and circulation. Especially sensitive region is located near auroral oval, where most energy is deposited during geomagnetic storms. In this region and just below it, where the main ionospheric trough is located, we observe enhanced electromagnetic emissions in different frequency ranges. In particular the AKR-like (Auroral Kilometric Radiation) emissions are seen at frequencies of the order of hundreds of kHz in the ionosphere, just below the auroral oval. Analyzing spectrograms from DEMETER mission and comparing them with electron density measurements from DEMETER, we found that AKR-like emissions are seen near poleward wall of the main ionospheric trough, during geomagnetic storms. Main ionospheric trough is known as a turbulent region which properties change as the geomagnetic storm evolves. This work is an attempt to determine how the presence of the different emissions affect main ionospheric trough parameters such as location, width and depth. Data used in this study come from DEMETER and RELEC missions. This work was partly supported by NCN grant Rezonans 2012/07/B/ST9/04414.

  13. Design and Strength Evaluation of Structural Joint Made by Electro-Magnetic Forming(EMF)

    NASA Astrophysics Data System (ADS)

    Park, Young-Bae; Kim, Heon-Young; Oh, Soo-Ik

    2004-06-01

    Recently, weight reduction of vehicles has been of great interest, and consequently, the use of low-density materials in the automotive industry is increasing every year. Materials should not be substituted such a way that material of component parts is simply changed because there is a problem in achieving stiffness and strength. To achieve these requirements, the automobile should be redesigned totally. Aluminum spaceframe is rapidly being adopted as a body structure for accommodating lightness, stiffness and strength requirement. In aluminum spaceframe manufacturing, it is often required to join aluminum tube. But there are few suitable methods for joining aluminum tube, so that much interest has been focused on testing suitable joining methods. Joining by electromagnetic forming(EMF) can be useful method in joining aluminum tube, which offers some advantages compared with the conventional joining method. In this paper, joining by EMF was investigated as a pre-study for applying an automotive spaceframe. Finite element simulations and strength tests were performed to analyze the influence of geometric parameters on joint strength. Based on these results, configurations of axial joint and torque joint were suggested and guidelines for designing EMF joint were established.

  14. Final report of LDRD project: Electromagnetic impulse radar for detection of underground structures

    SciTech Connect

    Loubriel, G.; Aurand, J.; Buttram, M.; Zutavern, F.; Brown, D.; Helgeson, W.

    1998-03-01

    This report provides a summary of the LDRD project titled: Electromagnetic impulse radar for the detection of underground structures. The project met all its milestones even with a tight two year schedule and total funding of $400 k. The goal of the LDRD was to develop and demonstrate a ground penetrating radar (GPR) that is based on high peak power, high repetition rate, and low center frequency impulses. The idea of this LDRD is that a high peak power, high average power radar based on the transmission of short impulses can be utilized effect can be utilized for ground penetrating radar. This direct time-domain system the authors are building seeks to increase penetration depth over conventional systems by using: (1) high peak power, high repetition rate operation that gives high average power, (2) low center frequencies that better penetrate the ground, and (3) short duration impulses that allow for the use of downward looking, low flying platforms that increase the power on target relative to a high flying platform. Specifically, chirped pulses that are a microsecond in duration require (because it is difficult to receive during transmit) platforms above 150 m (and typically 1 km) while this system, theoretically could be at 10 m above the ground. The power on target decays with distance squared so the ability to use low flying platforms is crucial to high penetration. Clutter is minimized by time gating the surface clutter return. Short impulses also allow gating (out) the coupling of the transmit and receive antennas.

  15. Electromagnetic potential in pre-metric electrodynamics: Causal structure, propagators and quantization

    NASA Astrophysics Data System (ADS)

    Pfeifer, Christian; Siemssen, Daniel

    2016-05-01

    An axiomatic approach to electrodynamics reveals that Maxwell electrodynamics is just one instance of a variety of theories for which the name electrodynamics is justified. They all have in common that their fundamental input are Maxwell's equations d F =0 (or F =d A ) and d H =J and a constitutive law H =#F which relates the field strength two-form F and the excitation two-form H . A local and linear constitutive law defines what is called local and linear pre-metric electrodynamics whose best known application is the effective description of electrodynamics inside media including, e.g., birefringence. We analyze the classical theory of the electromagnetic potential A before we use methods familiar from mathematical quantum field theory in curved spacetimes to quantize it in a locally covariant way. Our analysis of the classical theory contains the derivation of retarded and advanced propagators, the analysis of the causal structure on the basis of the constitutive law (instead of a metric) and a discussion of the classical phase space. This classical analysis sets the stage for the construction of the quantum field algebra and quantum states. Here one sees, among other things, that a microlocal spectrum condition can be formulated in this more general setting.

  16. Controlling electromagnetic fields using periodic structures: Gratings, metamaterials, and photonic crystals

    NASA Astrophysics Data System (ADS)

    Memarian, Mohammad

    This thesis presents novel devices and techniques that enable new methods for enhancement, concentration, refraction, shaping, collimation, and directive beaming of electromagnetic fields. These unprecedented methods to control electromagnetic fields are achieved by exploring and harnessing the unique wave-interactions in periodic gratings, metamaterials, and photonic crystals, with emphasis on Epsilon-Near-Zero (ENZ) metamaterials and zero-index media. The presented solutions impact a wide variety of applications ranging from microwave to optical frequencies. A discovery of dramatic radiation enhancement of an invisible array of sources next to a sub-wavelength periodic metal strip grating is reported, both theoretically and experimentally. The phenomenon is first systematically theorized by introducing the 'spectral impulse response' approach for the aperiodic excitation problem, followed by the 'spectral array factor' approach for designing the near-field of array of sources. Such radiation enhancement has applications in sensing, detection, and accurate measurement of distance. The shaping and collimation of radiation of a simple dipole source near or buried inside a general anisotropic ENZ half-space is then systematically studied using the Lorentz reciprocity method. Various elliptic and hyperbolic anisotropic ENZ media are considered, showing how the air-side radiation can be enhanced and shaped using certain ENZs. A novel device and technique is proposed for collecting, refracting and concentrating incident waves into an area of high power concentration, at extremely short distances. This flat low-profile light-concentrator comprises a hetero-junction of anisotropic ENZ metamaterials (hyperbolic or elliptic), and is realized with plasmonic layered media at optical frequencies. By harnessing an extremely oblique refraction process in ENZs, the light-concentrator significantly outperforms the size requirements of existing thick high curvature lenses, useful

  17. [Electromagnetic studies of nuclear structure and reactions]. [Nuclear Physics Group, Univ. of New Hampshire

    SciTech Connect

    Not Available

    1992-01-01

    The experimental goals are focused on developing an understanding of strong interactions and the structure of hadronic systems by determination of the electromagnetic response; these goals will be accomplished through coincidence detection of final states. Nuclear modeling objectives are to organize and interpret the data through a consistent description of a broad spectrum of reaction observables; calculations are performed in a nonrelativistic diagrammatic framework as well as a relativistic QHD approach. Work is described according to the following arrangement: direct knockout reactions (completion of [sup 16]O(e,e[prime]p), [sup 12]C(e,e[prime]pp) progress, large acceptance detector physics simulations), giant resonance studies (intermediate-energy experiments with solid-state detectors, the third response function in [sup 12]C(e,e[prime]p[sub 0]) and [sup 16]O(e,e[prime]p[sub 0]), comparison of the [sup 12]C(e, e[prime]p[sub 0]) and [sup 16]O(e,e[prime]p[sub 3]) reactions, quadrupole strength in the [sup 16]O(e,e[prime][alpha][sub 0]) reaction, quadrupole strength in the [sup 12]C(e,e[prime][alpha]) reaction, analysis of the [sup 12]C(e,e[prime]p[sub 1]) and [sup 16]O(e,e[prime]p[sub 3]) angular distributions, analysis of the [sup 40]Ca(e,e[prime]x) reaction at low q, analysis of the higher-q [sup 12]C(e,e[prime]x) data from Bates), models of nuclear structure (experimental work, Hartree-Fock calculations, phonon excitations in spherical nuclei, shell model calculations, variational methods for relativistic fields), and instrumentation development efforts (developments at CEBAF, CLAS contracts, BLAST developments).

  18. Feedback Structure-Borne Sound Control of a Flexible Plate with AN Electromagnetic Actuator: the Phase Lag Problem

    NASA Astrophysics Data System (ADS)

    Ren, M. Z.; Seto, K.; Doi, F.

    1997-08-01

    In this paper an experimental study is presented on active control of a clamped plate at audio frequencies by using feedback controller and electromagnetic actuator. The controller is designed with modern control theory on a lumped parameter model of the plate, and is then implemented in experiments to control the real structure. In practice, the optimal control force cannot be generated exactly as desired due to the non-ideal characteristics of the control system. Several factors such as A/D and D/A convertors, velocity estimation through approximate differentiation, and the electromagnetic actuator are examined in respect to their frequency features. An analytical model is developed to predict the phase lag of the actual control force to the designed control force. It is shown that if the phase lag is over 90 degrees, the control system will become unstable. Two techniques are discussed for improving the system performance that is mainly affected by the electromagnetic actuator when the high speed sampling and processing device is used as the controller. The simple and practical method is to employ a phase-lead compensation network in the control circuit. Another one that is more fundamental is to incorporate the characteristics of the actuator into the system by feeding back the current passing through the actuator into the controller. Various experiments are carried out to verify the analysis and the proposed methods, and the potentials of the electromagnetic actuator in controlling the high frequency vibration and noise are therefore demonstrated.

  19. The structure of electromagnetic wave-induced 557.7-nm emission associated with a sporadic- E event over arecibo

    PubMed

    Kagan; Kelley; Garcia; Bernhardt; Djuth; Sulzer; Tepley

    2000-07-01

    We report observations of electromagnetic wave-induced 557.7-nm emission in correspondence with a sporadic low-altitude plasma layer (the sporadic- E layer, E(s)). We show that the structure of 557. 7-nm emission seen for some events results from a transformation of transmitted energy by ionization clouds, compiling the patchy type E(s), and presents a projection of the sporadic- E layer structure on the emission altitude. This allows us to propose the first method for visualizing a horizontal structure of sporadic- E layers. PMID:10991198

  20. Interaction of High Frequency Electromagnetic Waves with Vortex Density Structures: Comparison of Analytical and LSP Simulation Results

    NASA Astrophysics Data System (ADS)

    Sotnikov, V.; Kim, T.; Lundberg, J.; Paraschiv, I.; Mehlhorn, T. A.

    2014-10-01

    Interchange or flute type density irregularities in magnetized plasma are associated with Rayleigh-Taylor type instability. In particular, we are interested in the generation of low frequency plasma density irregularities in the form of flute type vortex density structures and interaction of high frequency electromagnetic waves used for surveillance and communication with such structures. These types of density irregularities play an important role in refraction and scattering of high frequency electromagnetic signals propagating in the earth ionosphere, in high energy density physics (HEDP), and in many other applications. We will present PIC simulation results of EM scattering on vortex type density structures using the LSP code and compare them with analytical results. Two cases will be analyzed. In the first case electromagnetic wave scattering will take place in the ionospheric plasma. In the second case laser probing in a high-beta Z-pinch plasma will be presented. This work was supported by the Air Force Research laboratory, the Air Force Office of Scientific Research, the Naval Research Laboratory and NNSA/DOE Grant No. DE-FC52-06NA27616 at the University of Nevada at Reno.

  1. Laser Thomson Scattering Diagnostics of Pulsed Filamentary Discharge Plasmas

    NASA Astrophysics Data System (ADS)

    Bolouki, Nima

    2012-10-01

    Laser Thomson scattering (LTS) has been applied to measure spatiotemporal evolution of electron density and electron temperature in a pulsed filamentary discharge. The light source of LTS is the second harmonics Nd:YAG laser with a energy of 8 mJ. Also a triple grating spectrometer (TGS) having high rejection rate for stray light is used to measure LTS spectra. In our experimental conditions, non-thermal and non-equilibrium micro-plasmas are generated at round atmospheric pressure. Moreover, the electrode set in this experiment is consisted of a needle electrode and a hemispherical electrode with an inter-electrode gap of 0.5 mm. The total electric charge that flows through the discharge channel vary from 20 nC to 850 nC by changing capacitance in electrical circuit. We could show that the total charge variation leads to increase in electron density from 10^22 m-3 to 10^23 m-3. However, the electron temperature remains almost constant at the main discharge. In order to investigate the streamer phase, we changed the gap up to 16mm, and then performed the LTS method to measure the electron density and electron temperature.

  2. FILAMENTARY ACCRETION FLOWS IN THE EMBEDDED SERPENS SOUTH PROTOCLUSTER

    SciTech Connect

    Kirk, Helen; Myers, Philip C.; Bourke, Tyler L.; Gutermuth, Robert A.; Wilson, Grant W.; Hedden, Abigail

    2013-04-01

    One puzzle in understanding how stars form in clusters is the source of mass-is all of the mass in place before the first stars are born, or is there an extended period when the cluster accretes material which can continuously fuel the star formation process? We use a multi-line spectral survey of the southern filament associated with the Serpens South embedded cluster-forming region in order to determine if mass is accreting from the filament onto the cluster, and whether the accretion rate is significant. Our analysis suggests that material is flowing along the filament's long axis at a rate of {approx}30 M{sub Sun} Myr{sup -1} (inferred from the N{sub 2}H{sup +} velocity gradient along the filament), and radially contracting onto the filament at {approx}130 M{sub Sun} Myr{sup -1} (inferred from HNC self-absorption). These accretion rates are sufficient to supply mass to the central cluster at a similar rate to the current star formation rate in the cluster. Filamentary accretion flows may therefore be very important in the ongoing evolution of this cluster.

  3. Crustal and uppermost mantle structures of Atlas Mountains of Morocco inferred from electromagnetic imaging

    NASA Astrophysics Data System (ADS)

    Kiyan, D.; Jones, A. G.; Fullea, J.; Ledo, J.; Siniscalchi, A.; Romano, G.

    2012-12-01

    The second phase of the PICASSO (Program to Investigate Convective Alboran Sea System Overturn) project and the concomitant TopoMed (Plate re-organization in the western Mediterranean: Lithospheric causes and topographic consequences - an ESF EUROCORES TOPO-EUROPE Collaborative Research Project) is designed to determine the internal structure of the crust and lithosphere of the Atlas Mountains of Morocco. A multi-institutional magnetotelluric (MT) experiment across the Atlas Mountains region comprises the acquisition of broadband and long period MT data along two profiles: a N-S oriented profile through Middle Atlas to the east and a NE-SW profile through Marrakech to the west. The preliminary results of interpretation of the MT data collected over the first profile were presented in the paper by Ledo et al. (2011). In this study, we present the results from 3D MT inversion using the codes WSINV3DMT (Siripunvaraporn et al., 2005) and Modular system for Electromagnetic Inversion (ModEM; Egbert and Kelbert, 2012). There is a general good agreement between the main features obtained from the 2D models and the new results of the 3D modelling. Models inverting for only off-diagonal tensor components showed a distinct conductivity contrast between Middle-High Atlas and Anti Atlas correlates with the South Atlas Front fault, the depth extent of which appears to be limited to uppermost mantle (approximately 55 km). The resistivity of the lithosphere is gradually increasing towards Anti Atlas. Beside this, a prominent conducting anomaly at the lower crust/uppermost mantle is imaged west of the profile in the junction between the High and Middle Atlas (Moulouya plain). The conductive body, which extends from the southern boundary of Middle Atlas to the northern boundary of High Atlas, is interpreted as due to the presence of partial melt and/or migrated fluids.

  4. Internal structure of Mount Merapi, Indonesia, derived from long-offset transient electromagnetic data

    NASA Astrophysics Data System (ADS)

    Müller, M.; HöRdt, A.; Neubauer, F. M.

    2002-09-01

    A long-offset transient electromagnetic (LOTEM) survey was carried out on Merapi volcano, Indonesia, in 1998. LOTEM data have been recorded at 41 receiver locations which cover a 10 km W-E and a 15 km S-N profile. The signals were transmitted at four locations on the south, west, and north sides of Merapi. The data were interpreted with one-dimensional (1-D) inversions. In addition, two particular features were investigated with 3-D modeling. On the south flank the magnetic field data show strong 3-D distortions consistently over the profile which can only be explained by a conductive near-surface structure, like a fracture filled with conductive fluids. The simulation of topographic effects shows that the interpretation is not significantly affected. On both profiles the most striking feature is a conductive layer of 20 Ω m at depths of 500-1000 m below the surface and a thickness of 1-2 km. The cause of the increased conductivity may be different for the summit area, the intermediate zone, and at the flanks: Below the summit, in vicinity of the conduit, the decrease in resistivity is produced either by hydrothermal fluids, by partial melts or rocks altered by the hydrothermal system, or by a combination. In the intermediate zone between the conduit and the flanks, either alteration or hydrothermal fluids may be the source of the conductivity increase. Fluids seem to be the most likely cause for the conductive layer at the flanks and the west-east striking anomaly. From the resistivity of the conductive layer and the typical porosity of volcanic rock we estimate fluid resistivities of 0.2-1 Ω m.

  5. Electromagnetic structure of the Delta baryon within the covariant spectator theory

    SciTech Connect

    M. T. Pena, G. Ramalho, Franz Gross

    2010-12-01

    We calculated all the electromagnetic observables for the nucleon and its lowest-lying Delta(1232) excitation within a constituent quark model for those two baryons based on the covariant spectator theory. Once the reactions gamma N \\to N and gamma N \\to Delta were described, we predicted without further adjusting of parameters the four electromagnetic Delta form factors: the electric charge G_{E0}, the magnetic dpole G_{M1}, the electric quadrupole G_{E2} and the magnetic octupole G_{M3}. The results are compatible with the available experimental data and recent lattice QCD data.

  6. From Fragmented Knowledge to a Knowledge Structure: Linking the Domains of Mechanics and Electromagnetism.

    ERIC Educational Resources Information Center

    Bagno, Esther; Eylon, Bat-Sheva; Ganiel, Uri

    2000-01-01

    Describes the MAOF physics education program which is designed to relate large parts of mechanics and electromagnetism to each other via the key concepts of field and potential, while at the same time treat students' conceptual difficulties. Finds that students who studied with the MAOF program significantly improved their physics knowledge…

  7. Coupled Structural, Thermal, Phase-Change and Electromagnetic Analysis for Superconductors. Volume 1

    NASA Technical Reports Server (NTRS)

    Felippa, C. A.; Farhat, C.; Park, K. C.; Militello, C.; Schuler, J. J.

    1996-01-01

    Described are the theoretical development and computer implementation of reliable and efficient methods for the analysis of coupled mechanical problems that involve the interaction of mechanical, thermal, phase-change and electromagnetic subproblems. The focus application has been the modeling of superconductivity and associated quantum-state phase-change phenomena. In support of this objective the work has addressed the following issues: (1) development of variational principles for finite elements, (2) finite element modeling of the electromagnetic problem, (3) coupling of thermal and mechanical effects, and (4) computer implementation and solution of the superconductivity transition problem. The main accomplishments have been: (1) the development of the theory of parametrized and gauged variational principles, (2) the application of those principled to the construction of electromagnetic, thermal and mechanical finite elements, and (3) the coupling of electromagnetic finite elements with thermal and superconducting effects, and (4) the first detailed finite element simulations of bulk superconductors, in particular the Meissner effect and the nature of the normal conducting boundary layer. The theoretical development is described in two volumes. This volume, Volume 1, describes mostly formulations for specific problems. Volume 2 describes generalization of those formulations.

  8. Coupled structural, thermal, phase-change and electromagnetic analysis for superconductors, volume 1

    NASA Technical Reports Server (NTRS)

    Felippa, Carlos A.; Farhat, Charbel; Park, K. C.; Militello, Carmelo; Schuler, James J.

    1993-01-01

    This research program has dealt with the theoretical development and computer implementation of reliable and efficient methods for the analysis of coupled mechanical problems that involve the interaction of mechanical, thermal, phase-change and electromagnetic subproblems. The focus application has been the modeling of superconductivity and associated quantum-state phase-change phenomena. In support of this objective the work has addressed the following issues: (1) development of variational principles for finite elements; (2) finite element modeling of the electromagnetic problem; (3) coupling of thermal and mechanical effects; and (4) computer implementation and solution of the superconductivity transition problem. The research was carried out over the period September 1988 through March 1993. The main accomplishments have been: (1) the development of the theory of parametrized and gauged variational principles; (2) the application of those principled to the construction of electromagnetic, thermal and mechanical finite elements; and (3) the coupling of electromagnetic finite elements with thermal and superconducting effects; and (4) the first detailed finite element simulations of bulk superconductors, in particular the Meissner effect and the nature of the normal conducting boundary layer. The grant has fully supported the thesis work of one doctoral student (James Schuler, who started on January 1989 and completed on January 1993), and partly supported another thesis (Carmelo Militello, who started graduate work on January 1988 completing on August 1991). Twenty-three publications have acknowledged full or part support from this grant, with 16 having appeared in archival journals and 3 in edited books or proceedings.

  9. Gravitational fragmentation caught in the act: the filamentary Musca molecular cloud

    NASA Astrophysics Data System (ADS)

    Kainulainen, J.; Hacar, A.; Alves, J.; Beuther, H.; Bouy, H.; Tafalla, M.

    2016-02-01

    Context. Filamentary structures are common in molecular clouds. Explaining how they fragment to dense cores is a missing step in understanding their role in star formation. Aims: We perform a case study of whether low-mass filaments are close to hydrostatic prior to their fragmentation, and whether their fragmentation agrees with gravitational fragmentation models. To accomplish this, we study the ~6.5 pc long Musca molecular cloud, which is an ideal candidate for a filament at an early stage of fragmentation. Methods: We employ dust extinction mapping, in conjunction with near-infrared JHKS-band data from the CTIO/NEWFIRM instrument, and 870 μm dust continuum emission data from the APEX/LABOCA instrument to estimate column densities in Musca. We use the data to identify fragments from the cloud and to determine the radial density distribution of its filamentary part. We compare the cloud's morphology with 13CO and C18O line emission observed with the APEX/SHeFI instrument. Results: The Musca cloud is pronouncedly fragmented at its ends, but harbors a remarkably well-defined, ~1.6 pc long filament in its center region. The line mass of the filament is 21-31 M⊙ pc-1 and the full width at half maximum (FWHM) 0.07 pc. The radial profile of the filament can be fitted with a Plummer profile, which has the power-index of 2.6 ± 11% and is flatter than that of an infinite hydrostatic filament. The profile can also be fitted with a hydrostatic cylinder truncated by external pressure. These models imply a central density of ~5-10 × 104 cm-3. The fragments in the cloud have a mean separation of ~0.4 pc, in agreement with gravitational fragmentation. These properties, together with the subsonic and velocity-coherent nature of the cloud, suggest a scenario in which an initially hydrostatic cloud is currently gravitationally fragmenting. The fragmentation started a few tenths of a Myr ago from the ends of the cloud, leaving its center still relatively nonfragmented

  10. Nonlinear current-voltage behavior of the isolated resistive switching filamentary channels in CuC nanolayer

    SciTech Connect

    Kim, Doo-In; Yoon, Jaesik; Kim, Young Moon; Kwon, Se Hun; Kim, Kwang Ho; Park, Ju-Bong; Hwang, Hyunsang

    2011-04-11

    Copper-doped amorphous carbon film was prepared by radio frequency reactive magnetron sputtering and their resistive switching behaviors were studied under a conductive atomic force microscope (cAFM). The repetitive scanning over the same area using cAFM with various bias voltages revealed that most of the isolated conductive paths were involved in resistive switching with asymmetric nonlinear I-V characteristics. The observed I-V behavior of nanoscale filamentary channels indicates that electron transfer mechanism of resistive switching filamentary channel in Pt/CuC/Pt is a tunneling between Cu filamentary channel and electrode through the solid electrolyte rather than conduction through fully connected Cu filamentary channel.

  11. Assessment of the Effect of Microstructure on the Magnetic Behavior of Structural Carbon Steels Using an Electromagnetic Sensor

    NASA Astrophysics Data System (ADS)

    Rumiche, F.; Indacochea, J. E.; Wang, M. L.

    2008-08-01

    The magnetic properties of four carbon steels were evaluated using an electromagnetic sensor and correlated with their microstructures. Their composition, microstructure features (such as ferrite volume fraction, grain size, inclusions, etc), and hardness were compared with their saturated magnetic flux density, retentivity, and coercivity. The four steel rods used in this study were hot-rolled AISI 1010, AISI 1018, AISI 1045, and AISI 1045-high manganese/“stress proof.” The results show that microstructures have a notable effect on the magnetic properties of the steels. In addition, the effect of variations in cross-section area of the steel rods on the magnetic response was investigated. The steel rods diameters were systematically reduced by machining and then magnetically evaluated. Consistent relationships between metallurgical characteristics of the structural carbon steels and their magnetic properties measured with the electromagnetic sensor were obtained. In addition, the sensor was found to be able to detect changes in magnetic properties due to variations in cross-section area. These results reveal that the electromagnetic sensor has the potential to be used as a reliable nondestructive tool to detect and monitor microstructural and morphological changes occurring during the different stages of steel manufacturing or alterations caused by a degradation mechanism.

  12. Properties of Filamentary Sublimation Residues from Dispersions of Clay in Ice

    NASA Technical Reports Server (NTRS)

    Stephens, J. B.; Parker, T. J.; Saunders, R. S.; Laue, E. G.; Fanale, F. P.

    1985-01-01

    The properties of sublimate residues are of considerable interest in studies of the thermal modeling of Martian and cometary ice surfaces. The study of the formation of sand grains from this mantle on Martian polar ice is also supported by these experiments. To understand these properties, a series of low temperature vacuum experiments were run during which dirty ices that might be expected to be found in Martian polar caps and in comet nuclei were made and then freeze dried. In addition to using particulate material of appropriate grain size and minerology, particle nucleated ices were simulated by dispersing the particulates in the ice so that they did not contact one another. This noncontact dispersion was the most difficult requirement to achieve but the most rewarding in that it produced a new filamentary sublimate residue that was not a relic of the frozen dispersion. If the siliceous particles are allowed to touch one another in the ice the structure of the contacting particles in the ice will remain as a relic after the ice is sublimed away.

  13. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Modeling and Computing Example for Effective Electromagnetic Parameters of Multiphase Composite Media

    NASA Astrophysics Data System (ADS)

    Song, Wei-Li; Yuan, Jie; Hou, Zhi-Ling; Cao, Mao-Sheng

    2009-05-01

    A method using strong fluctuation theory (SFT) to compute the effective electromagnetic parameters of multiphase composite media, and common materials used to design radar-absorbing materials, is demonstrated. The effective electromagnetic parameters of ultrafine carbonyl-iron (DT-50) and fiber fabric, which are both multiphase composite media and represent coated and structured radar absorbing materials, respectively, are investigated, and the corresponding equations of electromagnetic parameters by using the SFT are attained. Moreover, we design a program to simplify the solutions, and the results are discussed.

  14. Electromagnetic turbulent structures: A ubiquitous feature of the edge region of toroidal plasma configurations

    SciTech Connect

    Spolaore, M. Vianello, N.; Agostini, M.; Cavazzana, R.; De Masi, G.; Martines, E.; Momo, B.; Scaggion, A.; Scarin, P.; Spagnolo, S.; Spizzo, G.; Zuin, M.; Furno, I.; Avino, F.; Fasoli, A.; Theiler, C.; Carralero, D.; Alonso, J. A.; Hidalgo, C.

    2015-01-15

    Electromagnetic features of turbulent filaments, emerging from a turbulent plasma background, have been studied in four different magnetic configurations: the stellarator TJ-II, the Reversed Field Pinch RFX-mod, a device that can be operated also as a ohmic tokamak, and the Simple Magnetized Torus, TORPEX. By applying an analogous diagnostic concept in all cases, direct measurements of both field-aligned current density and vorticity were performed inside the filament. The inter-machine comparison reveals a clear dependence of the filament vorticity upon the local time-averaged E × B flow shear. Furthermore, a wide range of local beta was explored allowing concluding that this parameter plays a fundamental role in the appearance of filament electromagnetic features.

  15. Electromagnetic turbulent structures: A ubiquitous feature of the edge region of toroidal plasma configurations

    NASA Astrophysics Data System (ADS)

    Spolaore, M.; Vianello, N.; Furno, I.; Carralero, D.; Agostini, M.; Alonso, J. A.; Avino, F.; Cavazzana, R.; De Masi, G.; Fasoli, A.; Hidalgo, C.; Martines, E.; Momo, B.; Scaggion, A.; Scarin, P.; Spagnolo, S.; Spizzo, G.; Theiler, C.; Zuin, M.

    2015-01-01

    Electromagnetic features of turbulent filaments, emerging from a turbulent plasma background, have been studied in four different magnetic configurations: the stellarator TJ-II, the Reversed Field Pinch RFX-mod, a device that can be operated also as a ohmic tokamak, and the Simple Magnetized Torus, TORPEX. By applying an analogous diagnostic concept in all cases, direct measurements of both field-aligned current density and vorticity were performed inside the filament. The inter-machine comparison reveals a clear dependence of the filament vorticity upon the local time-averaged E × B flow shear. Furthermore, a wide range of local beta was explored allowing concluding that this parameter plays a fundamental role in the appearance of filament electromagnetic features.

  16. Metal/PET Composite Knitted Fabrics and Composites: Structural Design and Electromagnetic Shielding Effectiveness

    NASA Astrophysics Data System (ADS)

    Huang, Chen-Hung; Lin, Jia-Horng; Yang, Ruey-Bin; Lin, Ching-Wen; Lou, Ching-Wen

    2012-08-01

    Following rapid technological advances, electronic products are being used more frequently than ever, resulting in a massive amount of interference from electromagnetic waves. In this research, stainless-steel (SS) wires, copper wires, and polyester (PET) filaments were made into SS/PET, copper/PET, and SS/copper/PET composite ply yarns. These ply yarns were then knitted into electromagnetic shielding fabrics with various knitting-needle densities. In the frequency range of 1.1 GHz to 1.4 GHz, the electromagnetic shielding effectiveness (EMSE) of the SS/PET fabric was 3.8 dB greater than that of the copper/PET composite knitted fabric, demonstrating better permeability. However, in the frequency range of 0.36 GHz to 1.1 GHz, the EMSE of the copper/PET fabric was 10 dB greater than that of the SS/PET fabric, demonstrating better conductivity. The SS/copper/PET fabrics exhibited an EMSE 10 dB greater than that of the SS/PET or copper/PET fabrics.

  17. Coupled Structural, Thermal, Phase-change and Electromagnetic Analysis for Superconductors, Volume 2

    NASA Technical Reports Server (NTRS)

    Felippa, C. A.; Farhat, C.; Park, K. C.; Militello, C.; Schuler, J. J.

    1996-01-01

    Described are the theoretical development and computer implementation of reliable and efficient methods for the analysis of coupled mechanical problems that involve the interaction of mechanical, thermal, phase-change and electromag subproblems. The focus application has been the modeling of superconductivity and associated quantum-state phase change phenomena. In support of this objective the work has addressed the following issues: (1) development of variational principles for finite elements, (2) finite element modeling of the electromagnetic problem, (3) coupling of thermel and mechanical effects, and (4) computer implementation and solution of the superconductivity transition problem. The main accomplishments have been: (1) the development of the theory of parametrized and gauged variational principles, (2) the application of those principled to the construction of electromagnetic, thermal and mechanical finite elements, and (3) the coupling of electromagnetic finite elements with thermal and superconducting effects, and (4) the first detailed finite element simulations of bulk superconductors, in particular the Meissner effect and the nature of the normal conducting boundary layer. The theoretical development is described in two volumes. Volume 1 describes mostly formulation specific problems. Volume 2 describes generalization of those formulations.

  18. A Dry Powder Process for Preparing Uni-Tape Prepreg from Polymer Powder Coated Filamentary Towpregs

    NASA Technical Reports Server (NTRS)

    Wilkinson, Steven P. (Inventor); Johnston, Norman J. (Inventor); Marchello, Joseph M. (Inventor)

    1995-01-01

    A process for preparing uni-tape prepreg from polymer powder coated filamentary towpregs is provided. A plurality of polymer powder coated filamentary towpregs are provided. The towpregs are collimated so that each towpreg is parallel. The sandwich is heated to a temperature wherein the polymer flows and intimately contacts the filaments and pressure is repeatedly applied perpendicularly to the sandwich with a longitudinal oscillating action wherein the filaments move apart and the polymer wets the filaments forming a uni-tape prepreg. The uni-tape prepreg is subsequently cooled.

  19. Dry powder process for preparing uni-tape prepreg from polymer powder coated filamentary towpregs

    NASA Technical Reports Server (NTRS)

    Wilkinson, Steven P. (Inventor); Johnston, Norman J. (Inventor); Marchello, Joseph M. (Inventor)

    1997-01-01

    A process for preparing uni-tape prepreg from polymer powder coated filamentary towpregs is provided. A plurality of polymer powder coated filamentary towpregs are provided. The towpregs are collimated so that each towpreg is parallel. A material is applied to each side of the towpreg to form a sandwich. The sandwich is heated to a temperature wherein the polymer flows and intimately contacts the filaments and pressure is repeatedly applied perpendicularly to the sandwich with a longitudinal oscillating action wherein the filaments move apart and the polymer wets the filaments forming a uni-tape prepreg. The uni-tape prepreg is subsequently cooled.

  20. Tailoring electromagnetically induced transparency for terahertz metamaterials: From diatomic to triatomic structural molecules

    NASA Astrophysics Data System (ADS)

    Yin, Xiaogang; Feng, Tianhua; Yip, SenPo; Liang, Zixian; Hui, Alvin; Ho, Johnny C.; Li, Jensen

    2013-07-01

    The coupling effects in electromagnetically induced transparency (EIT) for triatomic metamaterials are investigated at terahertz (THz) frequencies both experimentally and theoretically. We observed enhancement and cancellation of EIT with single transparency window, and also two additional ways to achieve double EIT transparency windows. One is from the hybridization between two dark atoms in a bright-dark-dark configuration. Another is from an averaged effect between absorption of the additional bright atom and the EIT from the original diatomic molecule in a bright-bright-dark configuration. It allows us to control EIT and the associated slow-light effect for THz metamaterials with high accuracy.

  1. Enhancement of Optical Nonlinearities in Composite Media and Structures via Local Fields and Electromagnetic Coupling Effects

    NASA Technical Reports Server (NTRS)

    Smith, David D.

    2002-01-01

    This talk will review the linear and nonlinear optical properties of metal nanoparticles and dielectric microparticles, with an emphasis on local field effects, and whispering gallery modes (WGMs), as well as the conjunction of these two effects for enhanced Raman. In particular, enhanced optical properties that result from electromagnetic coupling effects will be discussed in the context of Mie scattering from concentric spheres and bispheres. Predictions of mode splitting and photonic bandgaps in micro-spheres will be presented and will be shown to be analogous to effects that occur in coupled resonator optical waveguides (CROW). Slow and fast light in SCISSOR / CROW configurations will also be discussed.

  2. Minimum uncertainty states in angular momentum and angle variables for charged particles in structured electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Rodríguez-Méndez, D.; Hacyan, S.; Jáuregui, R.

    2013-10-01

    We study the phase-space properties of a charged particle in a static electromagnetic field exhibiting vortex pairs with complementary topological charges and in a pure gauge field. A stationary solution of the Schrödinger equation that minimizes the uncertainty relations for angular momentum and trigonometric functions of the phase is obtained. It does not exhibit vortices and the angular momentum is due to the gauge field only. Increasing the topological charge of the vortices increases the regions where the Wigner function in the angle-angular momentum plane takes negative values, and thus enhances the quantum character of the dynamics.

  3. Electrical resistivity structure of the Valu Fa Ridge, Lau Basin, from marine controlled-source electromagnetic sounding

    NASA Astrophysics Data System (ADS)

    MacGregor, Lucy; Sinha, Martin; Constable, Steven

    2001-07-01

    In December 1995 we carried out a comprehensive controlled-source electromagnetic survey of the Valu Fa Ridge at 22°25'S in the Lau Basin. The Valu Fa Ridge is a back-arc spreading centre of intermediate spreading rate and is a site of extensive hydrothermal activity. Seismic studies have imaged a melt lens at an average depth of 3.2km below the seafloor, surrounded by a zone of lowered seismic velocity, interpreted as a region of partial melt in the crust. The electromagnetic experiment was part of a multidisciplinary study which included wide-angle and reflection seismics, bathymetry and potential field measurements. Electromagnetic signals at frequencies between 0.25 and 40Hz were transmitted from a horizontal electric dipole towed close to the seafloor and were recorded by an array of 11 sea-bottom receivers at ranges of up to 20km from the source. Over 80 hr of data, consisting of the magnitude of the horizontal electric field at the seafloor, were collected. These data have extremely low scatter compared to similar data from previous surveys. The data were interpreted using a combination of 1- and 2-D forward modelling and inversion. The vertical resistivity gradient in the upper crust at the Valu Fa Ridge is abnormally low, with resistivities of less than 10Ω m observed throughout layer 2 of the crust to a depth of 3km. This is significantly more conductive at depth than the axis of the slow-spreading Reykjanes Ridge at 57°45'N, and the fast-spreading East Pacific Rise at 13°N, where similar data sets have been collected in the past. Although the structure of layer 2 is well constrained by the electromagnetic data, its extremely low resistivity causes rapid attenuation of electromagnetic signals diffusing through it, and hence the data are not sensitive to the structure in layer 3, in particular the structure of the melt lens or surrounding low-velocity zone. The seismic velocity structure of the Valu Fa Ridge, determined from the coincident wide

  4. DOD-SBIR Structured Multi-Resolution PIC Code for Electromagnetic Plasma Simulations, Final Report

    SciTech Connect

    Vay, J L; Grote, D P; Friedman, A

    2010-04-22

    A novel electromagnetic solver with mesh refinement capability was implemented in Warp. The solver allows for calculations in 2-1/2 and 3 dimensions, includes the standard Yee stencil, and the Cole-Karkkainen stencil for lower numerical dispersion along the principal axes. Warp implementation of the Cole-Karkkainen stencil includes an extension to perfectly matched layers (PML) for absorption of waves, and is preserving the conservation property of charge conserving current deposition schemes, like the Buneman-Villanesor and Esirkepov methods. Warp's mesh refinement framework (originally developed for electrostatic calculations) was augmented to allow for electromagnetic capability, following the methodology presented in [1] extended to an arbitrary number of refinement levels. Other developments include a generalized particle injection method, internal conductors using stair-cased approximation, and subcycling of particle pushing. The solver runs in parallel using MPI message passing, with a choice at runtime of 1D, 2D and 3D domain decomposition, and is shown to scale linearly on a test problem up-to 32,768 CPUs. The novel solver was tested on the modeling of filamentation instability, fast ignition, ion beam induced plasma wake, and laser plasma acceleration.

  5. Structural optimization of a large-displacement electromagnetic Lorentz force microactuator for optical switching applications

    NASA Astrophysics Data System (ADS)

    Han, Jeong Sam; Ko, Jong Soo; Korvink, Jan G.

    2004-11-01

    This paper discusses optimization of an electromagnetic microactuator for large-displacement optical switching. The microactuator used in this research is a laterally driven electromagnetic one that provides parallel actuation to the silicon substrate surface (in-plane motion) using the Lorentz force. When the microactuator is driven by the distributed Lorentz force induced along the arch-shaped leaf springs, a buckling phenomenon in two leaf springs enables a large displacement with a relatively small actuation load. An important design objective of a microactuator is to achieve a large displacement with a low actuating force. In this research, two optimization formulations have been performed to improve the displacement capabilities of the microactuator. In the first, the actuation load to obtain a specific displacement is minimized, subject to constraints on the first natural frequency and maximum allowable stress. In the second, the actuation displacement for a given actuation load is maximized, subject to the same constraints as in the first formulation. These optimizations have generated considerably improved designs, making the actuators capable of large-displacement actuations with small actuating loads.

  6. Human motion energy harvesting: numerical analysis of electromagnetic swing-excited structures

    NASA Astrophysics Data System (ADS)

    Ylli, K.; Hoffmann, D.; Willmann, A.; Folkmer, B.; Manoli, Y.

    2016-09-01

    Energy harvesting from human motion has constantly attracted scientific interest over recent years. A location where a harvesting device can easily and unobtrusively be integrated is the shoe sole, which also protects the device from exterior influences. In this work a numerical system model is developed, which can be used to simulate different inductive harvester geometries and predict their power output. Real world acceleration data is used as a model input. The model is implemented in Matlab/Simulink and subdivided into a mechanical and an electromagnetic model. The key features including the motion model and the calculation of the electromagnetic coupling coefficient are explained in detail and the model is briefly evaluated experimentally. A total of six inductive architectures, i.e. different cylindrical and rectangular magnet-coil arrangements, are then investigated in detail. The geometrical parameters are optimized for each architecture to find the best geometry within the size of 71 mm × 37.5 mm × 12.5 mm, which can be integrated into the sole. With the best overall design an average power output of 42.7 mW is simulated across an ohmic load of 41 Ohms. In addition to the respective best designs, the (dis-)advantages of each architecture are explained.

  7. Synthesis, structure and electromagnetic properties of Mn-Zn ferrite by sol-gel combustion technique

    NASA Astrophysics Data System (ADS)

    Wang, Wenjie; Zang, Chongguang; Jiao, Qingjie

    2014-01-01

    The electromagnetic absorbing behaviors of a thin coating fabricated by mixing Mn-Zn ferrite with epoxy resin (EP) were studied. The spinel ferrites Mn1-xZnxFe2O4 (x=0.2, 0.5 and 0.8) were synthesized with citrate acid as complex agent by sol-gel combustion method. The microstructure and surface morphology of Mn-Zn ferrite powders were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The complex permittivity and complex permeability of the fabricated ferrite/EP composites were investigated in terms of their contributions to the absorbing properties in the low frequency (10 MHz to 1 GHz). The microwave absorption of the prepared ferrite/EP composites could be tailored by matching the dielectric loss and magnetic loss and by controlling the doped metal ratio. The composites with the ferrite composition x=0.2 are found to show higher reflection loss compared with the composites with other compositions. It is proposed that the prepared composites can potentially be applied in electromagnetic microwave absorbing field.

  8. Theory of hysteresis during electron heating of electromagnetic wave scattering by self-organized dust structures in complex plasmas

    SciTech Connect

    Tsytovich, Vadim; Gusein-zade, Namik; Ignatov, Alexander

    2015-07-15

    Dust structuring is a natural and universal process in complex plasmas. The scattering of electromagnetic waves by dust structures is governed by the factor of coherency, i.e., the total number of coherent electrons in a single structure. In the present paper, we consider how the factor of coherency changes due to additional pulse electron heating and show that it obeys a hysteresis. After the end of the pulse heating, the scattering intensity differs substantially from that before heating. There are three necessary conditions for scattering hysteresis: first, the radiation wavelength should be larger than the pattern (structure) size; second, the total number of coherent electrons confined by the structure should be large; and third, the heating pulse duration should be shorter than the characteristic time of dust structure formation. We present the results of numerical calculations using existing models of self-consistent dust structures with either positively or negatively charged dust grains. It is shown that, depending on the grain charge and the ionization rate, two types of hysteresis are possible: one with a final increase of the scattering and the other with a final decrease of the scattering. It is suggested that the hysteresis of coherent scattering can be used as a tool in laboratory experiments and that it can be a basic mechanism explaining the observed hysteresis in radar scattering by noctilucent clouds during active experiments on electron heating in mesosphere.

  9. Propagation of electromagnetic waves through a multilayered structure containing diamond-like carbon, porous silicon, and left-handed material

    NASA Astrophysics Data System (ADS)

    Shabat, Mohammed M.; Ubeid, Muin F.; Altanany, Sameh M.

    2016-05-01

    In this work, reflection and transmission of electromagnetic wave through a multilayered structure containing diamond-like carbon, porous silicon, and left-handed material (LHM) are investigated theoretically and numerically. The mentioned materials are described, and their main parameters are given in detail. After the construction of the problem, the reflection and transmission coefficients are derived in a closed form by a transfer matrix method. The reflected and transmitted powers of the structure are calculated using these coefficients. In the numerical results, the mentioned powers are computed and illustrated as a function of frequency, angle of incidence, and slabs thickness, when the damping coefficient of the LHM changes. The results obtained may be useful to the researchers and designer working in the area solar cells.

  10. Summary of the Working Group 3: Electron beams from electromagnetic structures, including dielectric and laser-driven

    NASA Astrophysics Data System (ADS)

    Rosenzweig, J.; Conde, M.; leaders, WG

    2014-03-01

    In this working group advances in electromagnetic accelerating structures have been addressed, as they progress from radiofrequency towards new frontiers at short wavelengths and higher field, in excess of a GV/m. The discussion focused on schemes powered by advanced RF sources, as well as new sources of EM power such as Cerenkov wakefields, and intense lasers at wavelengths ranging from the visible to the mid-IR. Advanced and exotic structures using novel materials and photonic designs have been also examined. In this context one needed to place special emphasis on extreme high brightness electron beam sources that are demanded in optical-to-mm-scale accelerators, and on beam dynamics issues specific to the optical scale, and to use of ultra-high amplitude fields.

  11. Electromagnetic microactuators

    NASA Astrophysics Data System (ADS)

    Büttgenbach, S.; Al-Halhouli, A. T.; Feldmann, M.; Seidemann, V.; Waldschik, A.

    2013-05-01

    High precision microactuators have become key elements for many applications of MEMS, for example for positioning and handling systems as well as for microfluidic devices. Electromagnetic microactuators exhibit considerable benefits such as high forces, large deflections, low input impedances and thus, the involvement of only low voltages. Most of the magnetic microactuators developed so far are based on the variable reluctance principle and use soft magnetic materials. Since the driving force of such actuators is proportional to their volume, they require structures with rather great heights and aspect ratios. Therefore, the development of new photo resists, which allow UV exposure of thick layers of resist, has been essential for the advancement of variable reluctance microactuators. On the other hand, hard magnetic materials have the potential for larger forces and larger deflections. Accordingly, polymer magnets, in which micro particles of hard magnetic material are suspended in a polymer matrix, have been used to fabricate permanent magnet microactuators. In this paper we give an overview of sophisticated electromagnetic microactuators which have been developed in our laboratory in the framework of the Collaborative Research Center "Design and Manufacturing of Active Microsystems". In particular, concept, fabrication and test of variable reluctance micro stepper motors, of permanent magnet synchronous micromotors and of microactuators based on the Lorentz force principle will be described. Special emphasis will be given to applications in lab-on-chip systems.

  12. Potential of glassy carbon and silicon carbide photonic structures as electromagnetic radiation shields for atmospheric re-entry.

    PubMed

    Komarevskiy, Nikolay; Shklover, Valery; Braginsky, Leonid; Hafner, Christian; Lawson, John

    2012-06-18

    During high-velocity atmospheric entries, space vehicles can be exposed to strong electromagnetic radiation from ionized gas in the shock layer. Glassy carbon (GC) and silicon carbide (SiC) are candidate thermal protection materials due to their high melting point and also their good thermal and mechanical properties. Based on data from shock tube experiments, a significant fraction of radiation at hypersonic entry conditions is in the frequency range from 215 to 415 THz. We propose and analyze SiC and GC photonic structures to increase the reflection of radiation in that range. For this purpose, we performed numerical optimizations of various structures using an evolutionary strategy. Among the considered structures are layered, porous, woodpile, inverse opal and guided-mode resonance structures. In order to estimate the impact of fabrication inaccuracies, the sensitivity of the reflectivity to structural imperfections is analyzed. We estimate that the reflectivity of GC photonic structures is limited to 38% in the aforementioned range, due to material absorption. However, GC material can be effective for photonic reflection of individual, strong spectral line. SiC on the other hand can be used to design a good reflector for the entire frequency range. PMID:22714482

  13. Potential of Glassy Carbon and Silicon Carbide Photonic Structures as Electromagnetic Radiation Shields for Atmospheric Re-entry

    NASA Technical Reports Server (NTRS)

    Komarevskiy,Nikolay; Shklover, Valery; Braginsky, Leonid; Hafner, Christian; Lawson, John W.

    2012-01-01

    During high-velocity atmospheric entries, space vehicles can be exposed to strong electromagnetic radiation from ionized gas in the shock layer. Glassy carbon (GC) and silicon carbide (SiC) are candidate thermal protection materials due to their high melting point and also their good thermal and mechanical properties. Based on data from shock tube experiments, a significant fraction of radiation at hypersonic entry conditions is in the frequency range from 215 to 415 THz. We propose and analyze SiC and GC photonic structures to increase the reflection of radiation in that range. For this purpose, we performed numerical optimizations of various structures using an evolutionary strategy. Among the considered structures are layered, porous, woodpile, inverse opal and guided-mode resonance structures. In order to estimate the impact of fabrication inaccuracies, the sensitivity of the reflectivity to structural imperfections is analyzed. We estimate that the reflectivity of GC photonic structures is limited to 38% in the aforementioned range, due to material absorption. However, GC material can be effective for photonic reflection of individual, strong spectral line. SiC on the other hand can be used to design a good reflector for the entire frequency range.

  14. MAPPING LARGE-SCALE CO DEPLETION IN A FILAMENTARY INFRARED DARK CLOUD

    SciTech Connect

    Hernandez, Audra K.; Butler, Michael J.; Barnes, Peter; Tan, Jonathan C.; Caselli, Paola; Jimenez-Serra, Izaskun; Fontani, Francesco E-mail: butler85@astro.ufl.edu E-mail: jt@astro.ufl.edu E-mail: ijimenez-serra@cfa.harvard.edu

    2011-09-01

    Infrared Dark Clouds (IRDCs) are cold, high mass surface density and high density structures, likely to be representative of the initial conditions for massive star and star cluster formation. CO emission from IRDCs has the potential to be useful for tracing their dynamics, but may be affected by depleted gas phase abundances due to freeze out onto dust grains. Here we analyze C{sup 18}O J = 1 {yields} 0 and J = 2 {yields} 1 emission line data, taken with the Instituto de Radioastronomia Milimetrica 30 m telescope, of the highly filamentary IRDC G035.39.-0033. We derive the excitation temperature as a function of position and velocity, with typical values of {approx}7 K, and thus derive total mass surface densities, {Sigma}{sub C18O}, assuming standard gas phase abundances and accounting for optical depth in the line, which can reach values of {approx}1. The mass surface densities reach values of {approx}0.07 g cm{sup -2}. We compare these results to the mass surface densities derived from mid-infrared extinction mapping, {Sigma}{sub SMF}, by Butler and Tan, which are expected to be insensitive to the dust temperatures in the cloud. With a significance of {approx}> 10{sigma}, we find {Sigma}{sub C18O}/{Sigma}{sub SMF} decreases by about a factor of five as {Sigma} increases from {approx}0.02 to {approx}0.2 g cm{sup -2}, which we interpret as evidence for CO depletion. Several hundred solar masses are being affected, making this one of the most massive clouds in which CO depletion has been observed directly. We present a map of the depletion factor in the filament and discuss implications for the formation of the IRDC.

  15. Selective reinforcement of wing structure for flutter prevention.

    NASA Technical Reports Server (NTRS)

    Cooper, P. A.; Stroud, W. J.

    1972-01-01

    The results of an analytical study are presented on the use of boron polyimide filamentary composite material for the purpose of increasing the flutter speed of a simple titanium full depth sandwich wing structure designed for strength. The results clearly demonstrate that selective reinforcement of wing surfaces, using judiciously placed filamentary composites, promises sizable mass savings in the design of advanced aircraft structures.

  16. Seismic electromagnetic study in China

    NASA Astrophysics Data System (ADS)

    Huang, Qinghua

    2016-04-01

    Seismo-electromagnetism is becoming a hot interdisciplinary study in both geosciences and electromagnetism. Numerous electromagnetic changes at a broad range of frequencies associated with earthquakes have been reported independently. There are some attempts of applying such electromagnetic data to short-term earthquake prediction. Although due to the complexity of seismogenic process and underground structure, the seismic electromagnetic phenomena cannot be fully understood, the seismic electromagnetic study plays a key role in the mitigation of seismic hazard. China is one of the countries which have the earliest reports on seismo-electromagnetic phenomena. The seismic electromagnetic study in China started in late 1960's. There are almost 50 years continuous observation data up to now, which provides a unique database for seismo-electromagnetic study not only in China, but also in the world. Therefore, seismo-electromagnetic study in China is interested broadly by international communities of geosciences and electromagnetism. I present here a brief review on seismic electromagnetic study in China, especially focusing on geo-electromagnetic observation and empirical prediction based on the observation data. After summarizing various electromagnetic observations such as apparent resistivity, geoelectric potential, geomagnetic field, electromagnetic disturbance, and so on, I show the cases of the empirical prediction based on the observed electromagnetic data associated with some earthquakes in China. Finally, based on the above review, I propose an integrated research scheme of earthquake-related electromagnetic phenomena, which includes the interaction between appropriate observations, robust methodology of data processing, and theoretical model analysis. This study is supported partially by the National Natural Science Foundation of China (41274075) and the National Basic Research Program of China (2014CB845903).

  17. Photonic bands in two-dimensional microplasma arrays. I. Theoretical derivation of band structures of electromagnetic waves

    SciTech Connect

    Sakai, Osamu; Sakaguchi, Takui; Tachibana, Kunihide

    2007-04-01

    Two theoretical approaches appropriate for two-dimensional plasma photonic crystals reveal dispersions of propagating waves including photonic (electromagnetic) band gaps and multiflatbands. A modified plane-wave expansion method yields dispersions of collisional periodical plasmas, and the complex-value solution of a wave equation by a finite difference method enables us to obtain dispersions with structure effects in an individual microplasma. Periodical plasma arrays form band gaps as well as normal photonic crystals, and multiflatbands are present below the electron plasma frequency in the transverse electric field mode. Electron elastic collisions lower the top frequency of the multiflatbands but have little effect on band gap properties. The spatial gradient of the local dielectric constant resulting from an electron density profile widens the frequency region of the multiflatbands, as demonstrated by the change of surface wave distributions. Propagation properties described in dispersions including band gaps and flatbands agree with experimental observations of microplasma arrays.

  18. C/NOFS observations of electromagnetic coupling between magnetically conjugate MSTID structures

    NASA Astrophysics Data System (ADS)

    Burke, W. J.; Martinis, C. R.; Lai, P. C.; Gentile, L. C.; Sullivan, C.; Pfaff, R. F.

    2016-03-01

    This report demonstrates empirically that couplings between magnetically conjugate medium-scale traveling ionospheric disturbances (MSTIDs) are electromagnetic in nature. This is accomplished by comparing plasma density, electric, and magnetic perturbations sampled simultaneously by sensors on the Communication/Navigation Outage Forecasting System (C/NOFS) satellite. During the period of interest on 17 February 2010, C/NOFS made three consecutive orbits while magnetically conjugate to the field of view of an all-sky imager located at El Leoncito, Argentina (31.8°S, 69.3°W). Imaged 630.0 nm airglow was characterized by alternating bands of relatively bright and dark emissions that were aligned from northeast to southwest and propagated toward the northwest, characteristic of MSTIDs in the southern hemisphere. Measurable Poynting fluxes flow along the Earth's magnetic field (S||) from "generator" to "load" hemispheres. While S|| was predominantly away from the ionosphere above El Leoncito, interhemispheric energy flows were not one-way streets. Measured Poynting flux intensities diminished with time over the three C/NOFS passes, suggesting that source mechanisms of MSTIDs were absent or that initial impedance mismatches between the two hemispheres approached an equilibrium status.

  19. Electromagnetic Structure of A=2 and 3 Nuclei and the Nuclear Current Operator

    SciTech Connect

    Rocco Schiavilla

    2005-02-01

    Different models for conserved two- and three-body electromagnetic currents are constructed from two- and three-nucleon interactions, using either meson-exchange mechanisms or minimal substitution in the momentum dependence of these interactions. The connection between these two different schemes is elucidated. A number of low-energy electronuclear observables, including (i) np radiative capture at thermal neutron energies and deuteron photodisintegration at low energies, (ii) nd and pd radiative capture reactions, and (iii) isoscalar and isovector magnetic form factors of {sup 3}H and {sup 3}He, are calculated in order to make a comparative study of these models for the current operator. The realistic Argonne v{sub 18} two-nucleon and Urbana IX or Tucson-Melbourne three-nucleon interactions are taken as a case study. For A=3 processes, the bound and continuum wave functions, both below and above deuteron breakup threshold, are obtained with the correlated hyperspherical-harmonics method. Three-body currents give small but significant contributions to some of the polarization observables in the {sup 2}H(p,{gamma}){sup 3}He process and the {sup 2}H(n,{gamma}){sup 3}H cross section at thermal neutron energies. It is shown that the use of a current which did not exactly satisfy current conservation with the two- and three-nucleon interactions in the Hamiltonian was responsible for some of the discrepancies reported in previous studies between the experimental and theoretical polarization observables in pd radiative capture.

  20. Structure of the neutral pion and its electromagnetic transition form factor

    NASA Astrophysics Data System (ADS)

    Raya, Khépani; Chang, Lei; Bashir, Adnan; Cobos-Martinez, J. Javier; Gutiérrez-Guerrero, L. Xiomara; Roberts, Craig D.; Tandy, Peter C.

    2016-04-01

    The γ*γ →π0 transition form factor, G (Q2), is computed on the entire domain of spacelike momenta using a continuum approach to the two valence body bound-state problem in relativistic quantum field theory: the result agrees with data obtained by the CELLO, CLEO, and Belle Collaborations. The analysis unifies this prediction with that of the pion's valence-quark parton distribution amplitude (PDA) and elastic electromagnetic form factor and demonstrates, too, that a fully self-consistent treatment can readily connect a pion PDA that is a broad, concave function at the hadronic scale with the perturbative QCD prediction for the transition form factor in the hard photon limit. The normalization of that limit is set by the scale of dynamical chiral symmetry breaking, which is a crucial feature of the Standard Model. Understanding of the latter will thus remain incomplete until definitive transition form factor data are available on Q2>10 GeV2 .

  1. ELECTROMAGNETIC PUMP

    DOEpatents

    Pulley, O.O.

    1954-08-17

    This patent reiates to electromagnetic pumps for electricity-conducting fluids and, in particular, describes several modifications for a linear conduction type electromagnetic interaction pump. The invention resides in passing the return conductor for the current traversing the fiuid in the duct back through the gap in the iron circuit of the pump. Both the maximum allowable pressure and the efficiency of a linear conduction electromagnetic pump are increased by incorporation of the present invention.

  2. Electromagnetic responses of curved fishnet structures: near-zero refractive index with lower loss

    NASA Astrophysics Data System (ADS)

    Soemphol, Chaiyong; Kitchin, Steven F.; Fiddy, Michael A.; Wongkasem, Nantakan

    2016-02-01

    Fishnet structure metamaterials are modified by introducing some curvature at the corners of the slabs and the neck lines in order to tailor a uniform current distribution as well as field concentration in the microwave regime. The results obtained show that these modified fishnet structures can generate 20% broader low loss near-zero index bandwidth as compared to that of the original fishnet structures. The majority of the near-zero bands of the modified fishnet structures produce lower loss than those of the original fishnet structures at the same frequency.

  3. Cone structure and focusing of VLF and LF electromagnetic waves at high altitudes in the ionosphere

    NASA Technical Reports Server (NTRS)

    Alpert, Ya. L.; Green, J. L.

    1994-01-01

    The frequency and angle dependencies of the electric field radiated by an electric dipole E = E(sub 0) cos omega(t) are studied through numerical calculations of absolute value of E in the VLF and LF frequency bands where F is less than or equal 0.02 to 0.05 f(sub b) in a model ionosphere over an altitude region of 800-6000 km where the wave frequency and electron gyrofrequency varies between F approximately 4-500 kHz and f(sub b) is approximately equal (1.1 to 0.2) MHz respectively. It is found that the amplitudes of the electric field have large maxima in four regions: close to the direction of the Earth magnetic field line B(sub 0) (it is called the axis field E(sub 0), in the Storey E(sub St), reversed Storey E(sub RevSt), and resonance E(sub Res) cones. The maximal values of E(sub 0), E(sub Res), and E(sub RevSt) are the most pronounced close to the lower hybrid frequency, F approximately F(sub L). The flux of the electric field is concentrated in very narrow regions, with the apex angles of the cones Delta-B is approximately (0.1-1) deg. The enhancement and focusing of the electric field increases with altitude starting at Z greater than 800 km. At Z greater than or equal to 1000 up to 6000 km, the relative value of absolute value of E, in comparison with its value at Z = 800 km is about (10(exp 2) to 10(exp 4)) times larger. Thus the flux of VLF and LF electromagnetic waves generated at high altitudes in the Earth's ionosphere are trapped into very narrow conical beams similar to laser beams.

  4. Electromagnetic penetration through narrow slots in conducting surfaces and coupling to structures on the shadow side

    SciTech Connect

    Reed, E.K.; Butler, C.M. . Dept. of Electrical and Computer Engineering)

    1990-07-01

    Electromagnetic field penetration through a curved narrow slot in a planar conducting surface and coupling to a curved, loaded thin wire on the shadow side are determined in the time domain (TD) and the frequency domain (FD) by integral equation methods. Coupled integral equations are derived and solved numerically for the equivalent magnetic current in the slot and the electric current on the wire, from which the field that penetrates the slotted surface is determined. One employs a piecewise linear approximation of the unknown currents and performs equation enforcement by pulse testing. The resulting TD equations are solved by a scheme incorporating a finite-difference approximation for a second partial time derivative which allows one to solve for the unknown currents at a discrete time instant t + 1 in terms of the known excitation and currents calculated at a discrete time instant t and earlier. The FD equations are solved by the method of moments. A hybrid time-domain integral equation -- finite-difference time-domain solution technique is described whereby one solves for the field which penetrates a slotted cavity-backed surface. One models the fields in the exterior region and in the slot with integral operators and models the fields inside the cavity with a discretized form of Maxwell's equations. Narrow slots following various contours were chemically etched in thin bass sheets and an apparatus was fabricated to measure shadow-side fields, electric current on a thin wire on the shadow side, and, separately, fields inside a rectangular cavity which backed the slotted brass sheet. The experimentation was conducted at the Lawrence Livermore National Laboratory on a frequency-domain test range employing a monocone source over a large ground plane. One observes very good agreement among the experimental and theoretical results.

  5. Controlled-source electromagnetic and seismic delineation of subseafloor fluid flow structures in a gas hydrate province, offshore Norway

    NASA Astrophysics Data System (ADS)

    Attias, Eric; Weitemeyer, Karen; Minshull, Tim A.; Best, Angus I.; Sinha, Martin; Jegen-Kulcsar, Marion; Hölz, Sebastian; Berndt, Christian

    2016-08-01

    Deep sea pockmarks underlain by chimney-like or pipe structures that contain methane hydrate are abundant along the Norwegian continental margin. In such hydrate provinces the interaction between hydrate formation and fluid flow has significance for benthic ecosystems and possibly climate change. The Nyegga region, situated on the western Norwegian continental slope, is characterized by an extensive pockmark field known to accommodate substantial methane gas hydrate deposits. The aim of this study is to detect and delineate both the gas hydrate and free gas reservoirs at one of Nyegga's pockmarks. In 2012, a marine controlled-source electromagnetic (CSEM) survey was performed at a pockmark in this region, where high-resolution 3-D seismic data were previously collected in 2006. 2-D CSEM inversions were computed using the data acquired by ocean bottom electrical field receivers. Our results, derived from unconstrained and seismically constrained CSEM inversions, suggest the presence of two distinctive resistivity anomalies beneath the pockmark: a shallow vertical anomaly at the underlying pipe structure, likely due to gas hydrate accumulation, and a laterally extensive anomaly attributed to a free gas zone below the base of the gas hydrate stability zone. This work contributes to a robust characterization of gas hydrate deposits within subseafloor fluid flow pipe structures.

  6. Analysis of Wave Propagation in Stratified Structures Using Circuit Analogues, with Application to Electromagnetic Absorbers

    ERIC Educational Resources Information Center

    Sjoberg, Daniel

    2008-01-01

    This paper presents an overview of how circuit models can be used for analysing wave propagation in stratified structures. Relatively complex structures can be analysed using models which are accessible to undergraduate students. Homogeneous slabs are modelled as transmission lines, and thin sheets between the slabs are modelled as lumped…

  7. Electromagnetic Attraction.

    ERIC Educational Resources Information Center

    Milson, James L.

    1990-01-01

    Three activities involving electromagnetism are presented. Discussed are investigations involving the construction of an electromagnet, the effect of the number of turns of wire in the magnet, and the effect of the number of batteries in the circuit. Extension activities are suggested. (CW)

  8. Investigation of the structure of the electromagnetic field and related phenomena, generated by the active satellite

    NASA Technical Reports Server (NTRS)

    Alpert, Yakov L.

    1992-01-01

    A short review is given for the general frequency and angle distribution of the electric field radiated by an electric dipole E = E(sub 0)cos(omega)t, in a magnetoplasma. Detailed results of numerical calculations of (E) were made in the Very Low Frequency (VLF) and the Low Frequency (LF) bands 0.02f(sub b) is less than or equal to F is less than or equal to 0.5f(sub b) (F is approximately (4-500) kHz) in the ionosphere and magnetosphere in the altitude region Z = (800-6000) km; f(sub b) is the electron gyro-frequency of the plasmas in the discussed region f(sub b) is approximately equal to (1.1 to 0.2) MHz. The amplitudes of the electric field have large maxima in four regions: close to the direction of the Earth's magnetic field line (B(sub 0)), it is the so called Axis field (E(sub 0)) and in the Storey (E(sub St)), Reversed Storey (E(sub RevSt)), and Resonance (E(sub Res)) Cones. The maximal values of E(sub 0), E(sub Res), and E(sub RevSt) are very pronounced close to the low hybrid frequency, F approximately F(sub L). The flux of the electric field is concentrated in very narrow regions, the apex angles of the cones delta(beta) is approximately equal to (0.1 - 1) degree. The enhancement and focusing of the electric field is growing up, especially quickly at Z greater than 800 km. At Z is greater than 1000 up to 6000 km, the relative value of (E), in comparison with its value at Z = 800 km is about (10(exp 2) to 10(exp 4)) times larger. Thus, the flux of VLF and LF electromagnetic waves in the Earth magnetoplasma produces and is guided by very narrow pencil beams, similar, let us say, to laser beams.

  9. The theory of electro-magnetic radiation of electron transiting through the resonance-tunnel structure

    SciTech Connect

    Tkach, M.; Seti, Ju.; Voitsekhivska, O.; Fartushynsky, R.

    2009-12-14

    The quasi-stationary electron states are studied in the three-barrier resonance-tunnel structure which is the basic element of coherent quantum cascade lasers. In the models of rectangular and delta-barrier potentials there is established theory of evolution and collapse of double resonance complexes in a symmetric resonance-tunnel structure. The induced conductivity of nano-system is calculated within the both models. It is shown that the negative induced conductivity of three-barrier resonance-tunnel structure in delta-barrier model is dozens times smaller than more realistic magnitudes obtained within the rectangular potentials model.

  10. Critical current studies on fine filamentary NbTi accelerator wires

    SciTech Connect

    Garber, M.; Suenaga, M.; Sampson, W.B.; Sabatini, R.L.

    1985-01-01

    The magnets for the Superconductig Super Collider, a high energy proton colliding beam accelerator, require a superconductor with very high current density (>2400 A/mm/sup 2/ at 5 T) and very small filaments (approx. 2..mu..m in diameter). Previous work has shown that by controlling the formation of Cu/sub 4/Ti compound particles on the filament surfaces it is possible to make fine filamentary NbTi wire with high critical current density. The performance of multi-filamentary wire is characterized by the current density and the quantity ''n'' which describes the superconducting-normal transition. Micrographs of wires having high J/sub c/ and high n show smooth, uniform filaments. Recently wires of very high critical current and high n have been produced in experimental quantities by commercial manufactures.

  11. DBD plasma source operated in single-filamentary mode for therapeutic use in dermatology

    NASA Astrophysics Data System (ADS)

    Rajasekaran, Priyadarshini; Mertmann, Philipp; Bibinov, Nikita; Wandke, Dirk; Viöl, Wolfgang; Awakowicz, Peter

    2009-11-01

    Our dielectric barrier discharge (DBD) plasma source for bio-medical application comprises a copper electrode covered with ceramic. Objects of high capacitance such as the human body can be used as the opposite electrode. In this study, the DBD source is operated in single-filamentary mode using an aluminium spike as the opposite electrode, to imitate the conditions when the discharge is ignited on a raised point, such as hair, during therapeutic use on the human body. The single-filamentary discharge thus obtained is characterized using optical emission spectroscopy, numerical simulation, voltage-current measurements and microphotography. For characterization of the discharge, averaged plasma parameters such as electron distribution function and electron density are determined. Fluxes of nitric oxide (NO), ozone (O3) and photons reaching the treated surface are simulated. The calculated fluxes are finally compared with corresponding fluxes used in different bio-medical applications.

  12. High-Temperature Superconductors as Electromagnetic Deployment and Support Structures in Spacecraft. [NASA NIAC Phase I

    NASA Technical Reports Server (NTRS)

    Getliffe, Gwendolyn V.; Inamdar, Niraj K.; Masterson, Rebecca; Miller, David W.

    2012-01-01

    This report, concluding a one-year NIAC Phase I study, describes a new structural and mechanical technique aimed at reducing the mass and increasing the deployed-to-stowed length and volume ratios of spacecraft systems. This technique uses the magnetic fields generated by electrical current passing through coils of high-temperature superconductors (HTSs) to support spacecraft structures and deploy them to operational configurations from their stowed positions inside a launch vehicle fairing.

  13. CO gas kinematics and excitation in a filamentary IRDC: Filament-filament interaction and accretion processes.

    NASA Astrophysics Data System (ADS)

    Jimenez-Serra, Izaskun; Caselli, Paola; Fontani, Francesco; Tan, Jonathan C.; Henshaw, Jonathan D.; Kainulainen, Jouni; Hernandez, Audra K.

    2013-07-01

    Some theories of molecular cloud formation propose that molecular clouds form in highly dynamical environments characterized by the interaction of converging gas flows or cloud-cloud collisions. The determination of the dynamics and physical conditions of the molecular gas in clouds at the early stages of their evolution is thus essential to establish the dynamical imprints of such collisions, and to infer the physical processes involved in their formation. We present large-scale (~1.7pc x 3.4 pc) multi-transition 13CO and C18O on-the-fly maps carried out with the IRAM 30m and JCMT telescopes toward the Infrared-Dark Cloud G035.39-00.33. This cloud shows a very filamentary structure and relatively little star formation activity, suggestive of its youth, and where evidence for a flow-flow collision has recently been reported. Consistent with previous studies, the 13CO and C18O line maps toward G035.39-00.33 reveal that the molecular gas in this cloud is distributed in three different filaments separated in velocity space by ~3 kms-1 (Filaments 1, 2 and 3). The massive dense cores in this IRDC are preferentially found at the intersecting regions between Filaments 1 and 3, where most of the CO gas is accumulated. The analysis of the 13CO and C18O lines show that the three filaments have a similar kinematic structure with relatively smooth velocity gradients (of ~0.4-0.8 kms-1pc-1) that seem to converge onto core H6, the most massive core in the region located in the center of the IRDC. Several possible scenarios are proposed to explain this velocity gradient, including rotation, global gas accretion along the filaments and large-scale turbulence motions with a steep turbulent power spetrum. The 13CO and C18O gas motions are supersonic across G035.39-00.33 with the line emission showing broader linewidths toward the edges of the IRDC. This may indicate energy dissipation at the densest regions in the IRDC as a consequence of the filament-filament interaction. The

  14. Gas Kinematics and Star Formation in the Filamentary IRDC G34.43+0.24

    NASA Astrophysics Data System (ADS)

    Xu, Jin-Long; Li, Di; Zhang, Chuan-Peng; Liu, Xiao-Lan; Wang, Jun-Jie; Ning, Chang-Chun; Ju, Bing-Gang

    2016-03-01

    We performed a multiwavelength study toward the infrared dark cloud (IRDC) G34.43+0.24. New maps of 13CO J = 1-0 and C18O J = 1-0 were obtained from the Purple Mountain Observatory (PMO) 13.7 m radio telescope. At 8 μm (Spitzer-IRAC), IRDC G34.43+0.24 appears to be a dark filament extended by 18‧ along the north-south direction. Based on the association with the 870 μm and C18O J = 1-0 emission, we suggest that IRDC G34.43+0.24 should not be 18‧ in length, but extend to 34‧. IRDC G34.43+0.24 contains some massive protostars, UC H ii regions, and infrared bubbles. The spatial extend of IRDC G34.43+0.24 is about 37 pc, assuming a distance of 3.7 kpc. IRDC G34.43+0.24 has a linear mass density of ˜1.6 × 103 M⊙ pc-1, which is roughly consistent with its critical mass to length ratio. The turbulent motion may help stabilize the filament against the radial collapse. Both infrared bubbles N61 and N62 show a ringlike structure at 8 μm. In particular, N61 has a double-shell structure that has expanded into IRDC G34.43+0.24. The outer shell is traced by 8 μm and 13CO J = 1-0 emission, while the inner shell is traced by 24 μm and 20 cm emission. We suggest that the outer shell (9.9 × 105 years) is created by the expansion of H ii region G34.172+0.175, while the inner shell (4.1 ˜ 6.3 × 105 years) may be produced by the energetic stellar wind of its central massive star. From the GLIMPSE I catalog, we selected some Class I sources with an age of ˜105 years. These Class I sources are clustered along the filamentary molecular cloud.

  15. Structural mapping in basin-and-range-like geology by electromagnetic methods: A powerful aid to seismic

    SciTech Connect

    Galibert, P.Y.; Andrieux, P.; Guerin, R.

    1996-11-01

    A case history is presented where electromagnetic (EM) methods were applied as a complement to seismic, for structural mapping in basin-and-range-like geology: 366 five-component magnetotelluric (MT) soundings were carried out together with 331 transient soundings (TDEM) along seismic lines. Due to high structural complexity, seismic shows a number of limitations. For the same reasons, MT is highly perturbed and three specific interpretation techniques were comprehensively applied: (1) a classical correction of static effect using TDEM sounding, to determine the high-frequency nondistorted apparent resistivities and thus the corrected tensor; (2) a so-called regional correction based upon the same concept as the static effect, to transform distorted resistivity curves due to the horst/graben situation into plausible 1D curves, through the use of nomograms built for 2D H-polarization situations; and (3) a stripping technique which made it possible to map areas where a deep conductive Mesozoic shale was present below carbonates, at a depth of 3 km. After the best MT interpretation was obtained along each line, it was integrated with seismic and with the results from two boreholes. A crude empirical law relating resistivity and acoustic velocity was established and the MT horizons were plotted on the two-way traveltime seismic sections. The final integrated cross-sections obtained are undoubtedly of greater use to the explorationist than the initial seismic sections alone and two wells were accurately predicted.

  16. Accurate modeling and reconstruction of three-dimensional percolating filamentary microstructures from two-dimensional micrographs via dilation-erosion method

    SciTech Connect

    Guo, En-Yu; Chawla, Nikhilesh; Jing, Tao; Torquato, Salvatore; Jiao, Yang

    2014-03-01

    Heterogeneous materials are ubiquitous in nature and synthetic situations and have a wide range of important engineering applications. Accurate modeling and reconstructing three-dimensional (3D) microstructure of topologically complex materials from limited morphological information such as a two-dimensional (2D) micrograph is crucial to the assessment and prediction of effective material properties and performance under extreme conditions. Here, we extend a recently developed dilation–erosion method and employ the Yeong–Torquato stochastic reconstruction procedure to model and generate 3D austenitic–ferritic cast duplex stainless steel microstructure containing percolating filamentary ferrite phase from 2D optical micrographs of the material sample. Specifically, the ferrite phase is dilated to produce a modified target 2D microstructure and the resulting 3D reconstruction is eroded to recover the percolating ferrite filaments. The dilation–erosion reconstruction is compared with the actual 3D microstructure, obtained from serial sectioning (polishing), as well as the standard stochastic reconstructions incorporating topological connectedness information. The fact that the former can achieve the same level of accuracy as the latter suggests that the dilation–erosion procedure is tantamount to incorporating appreciably more topological and geometrical information into the reconstruction while being much more computationally efficient. - Highlights: • Spatial correlation functions used to characterize filamentary ferrite phase • Clustering information assessed from 3D experimental structure via serial sectioning • Stochastic reconstruction used to generate 3D virtual structure 2D micrograph • Dilation–erosion method to improve accuracy of 3D reconstruction.

  17. Optical characteristics of the filamentary and diffuse modes in surface dielectric barrier discharge.

    PubMed

    Zhang, Ying; Li, Jie; Jiang, Nan; Shang, Ke-Feng; Lu, Na; Wu, Yan

    2016-11-01

    Surface dielectric barrier discharge (DBD) plasmas generally exhibits filamentary and diffuse discharges at atmospheric air. The focus of this investigation is on the different optical characteristics and quantitative research about morphological features of two discharge modes. The temporally and spatially resolved characteristics of discharge phenomenon together with the gas temperature are presented with microsecond time scale. Discharge area is estimated by the sum of pixels that equal to "1" in MATLAB software. The formation of diffuse plasma mainly depends on an increase of the ionization coefficient and a creation of sufficient seed electrons by the Penning effect at low electric fields. Accordingly, experimental measurements show that diffuse discharge during the negative half cycle has good uniformity and stability compared with filamentary discharge during the positive half cycle. The rotational temperatures of plasma are determined by comparing the experimental spectra with the simulated spectra that have been investigated. The plasma gas temperature keeps almost constant in the filamentary discharge phase and subsequently increased by about 115K during the diffuse discharge. In addition, it is shown to be nearly identical in the axial direction. Non-uniform temperature distribution can be observed in the radial direction with large fluctuations. The plasma length is demonstrated almost the same between two discharge modes. PMID:27294552

  18. Simultaneous Joint Inversion of Seismic AVO and Controlled Source Electromagnetic Data by Direct Estimation of Common Parameter Structure

    NASA Astrophysics Data System (ADS)

    Lien, M.

    2012-12-01

    We are concerned with the inverse problem of identifying changes in saturation for monitoring of underground reservoirs with application to CO2 sequestration and oil production monitoring. The inverse problem is at the outset ill-posed, where non-uniqueness and instability issues can lead to large uncertainties in the resulting parameter estimates. Constraining the inversion with a higher degree of information by combining information from different data sets will be important to improve the quality of the model calibration and thereby the reliability of the resulting reservoir predictions. For this, the simultaneous joint inversion of seismic AVO and controlled source electromagnetic (CSEM) data is considered. With simultaneous joint inversion, one secures that the final result from the inversion honors all available data. AVO and CSEM represent different sources of information. The seismic signals provide information about the elastic properties of the reservoir with relatively high spatial resolution, whereas CSEM data probe the electric properties of the subsediments at the extreme low frequency limit. Hence, the coupling of the two data types is not trivial. An increasingly popular approach for simultaneous joint inversion of disparate data sets is structure-coupled joint inversion. Here the coupling of the data sets is obtained by imposing structural dependency between the different geophysical model parameters (i.e. the elastic and electric properties of the reservoir). The idea is that some of the main property changes in the different model parameters are likely to occur over the same interfaces/structures representing e.g. changes in lithology or fluid saturation. We propose a novel approach for structure-coupled joint inversion, where the coupling of the different data sets is obtained by facilitating for estimation of parameter structure directly. The approach is based on a generic method for parameter representation providing a joint relation to a

  19. Electromagnetic fasteners

    DOEpatents

    Crane, Randolph W.; Marts, Donna J.

    1994-11-01

    An electromagnetic fastener for manipulating objects in space uses the matic attraction of various metals. An end effector is attached to a robotic manipulating system having an electromagnet such that when current is supplied to the electromagnet, the object is drawn and affixed to the end effector, and when the current is withheld, the object is released. The object to be manipulated includes a multiplicity of ferromagnetic patches at various locations to provide multiple areas for the effector on the manipulator to become affixed to the object. The ferromagnetic patches are sized relative to the object's geometry and mass.

  20. Electromagnetic fasteners

    SciTech Connect

    Crane, Randolph W.; Marts, Donna J.

    1994-01-01

    An electromagnetic fastener for manipulating objects in space uses the matic attraction of various metals. An end effector is attached to a robotic manipulating system having an electromagnet such that when current is supplied to the electromagnet, the object is drawn and affixed to the end effector, and when the current is withheld, the object is released. The object to be manipulated includes a multiplicity of ferromagnetic patches at various locations to provide multiple areas for the effector on the manipulator to become affixed to the object. The ferromagnetic patches are sized relative to the object's geometry and mass.

  1. Protostar L1455 IRS1: A Rotating Disk Connecting to a Filamentary Network

    NASA Astrophysics Data System (ADS)

    Chou, Hsuan-Gu; Yen, Hsi-Wei; Koch, Patrick M.; Guilloteau, Stéphane

    2016-06-01

    We conducted IRAM-30 m C18O (2–1) and SMA 1.3 mm continuum 12CO (2–1) and C18O (2–1) observations toward the Class 0/I protostar L1455 IRS1 in Perseus. The IRAM-30 m C18O results show IRS1 in a dense 0.05 pc core with a mass of 0.54 M ⊙, connecting to a filamentary structure. Inside the dense core, compact components of 350 au and 1500 au are detected in the SMA 1.3 mm continuum and C18O, with a velocity gradient in the latter one perpendicular to a bipolar outflow in 12CO, likely tracing a rotational motion. We measure a rotational velocity profile \\propto {r}-0.75 that becomes shallower at a turning radius of ˜200 au, which is approximately the radius of the 1.3 mm continuum component. These results hint at the presence of a Keplerian disk with a radius <200 au around L1455 IRS1 with a protostellar mass of about 0.28 M ⊙. We derive a core rotation that is about one order of magnitude faster than expected. A significant velocity gradient along a filament toward IRS1 indicates that this filament is dynamically important, providing a gas reservoir and possibly responsible for the faster-than-average core rotation. Previous polarimetric observations show a magnetic field aligned with the outflow axis and perpendicular to the associated filament on a 0.1 pc scale, while on the inner 1000 au scale, the field becomes perpendicular to the outflow axis. This change in magnetic field orientations is consistent with our estimated increase in rotational energy from large to small scales that overcomes the magnetic field energy, wrapping the field lines and aligning them with the disk velocity gradient. These results are discussed in the context of the interplay between filament, magnetic field, and gas kinematics from large to small scales. Possible emerging trends are explored with a sample of 8 Class 0/I protostars.

  2. Summary Report of Working Group 7: Electromagnetic-Structure Based Accelerators

    SciTech Connect

    Colby, E.; Musumeci, P.; /INFN, Rome

    2007-04-02

    We detail the most pressing physics and technical issues confronting short-wavelength acceleration. We review new acceleration concepts that are proposed and under development, and recent progress on technical issues such as structure fabrication and material damage. We outline key areas where work is still needed before a reliable assessment of the value of working at wavelengths below 1 cm can be made. Possible ways to enhance collaboration and progress in this important area are also discussed.

  3. Can electromagnetic fields influence the structure and enzymatic digest of proteins? A critical evaluation of microwave-assisted proteomics protocols

    PubMed Central

    Damm, Markus; Nusshold, Christoph; Cantillo, David; Rechberger, Gerald N.; Gruber, Karl; Sattler, Wolfgang; Kappe, C. Oliver

    2012-01-01

    This study reevaluates the putative advantages of microwave-assisted tryptic digests compared to conventionally heated protocols performed at the same temperature. An initial investigation of enzyme stability in a temperature range of 37–80 °C demonstrated that trypsin activity declines sharply at temperatures above 60 °C, regardless if microwave dielectric heating or conventional heating is employed. Tryptic digests of three proteins of different size (bovine serum albumin, cytochrome c and β-casein) were thus performed at 37 °C and 50 °C using both microwave and conventional heating applying accurate internal fiber-optic probe reaction temperature measurements. The impact of the heating method on protein degradation and peptide fragment generation was analyzed by SDS-PAGE and MALDI-TOF-MS. Time-dependent tryptic digestion of the three proteins and subsequent analysis of the corresponding cleavage products by MALDI-TOF provided virtually identical results for both microwave and conventional heating. In addition, the impact of electromagnetic field strength on the tertiary structure of trypsin and BSA was evaluated by molecular mechanics calculations. These simulations revealed that the applied field in a typical laboratory microwave reactor is 3–4 orders of magnitude too low to induce conformational changes in proteins or enzymes. PMID:22889711

  4. Structural and electromagnetic characterization of Cr-substituted Ni-Zn ferrites synthesized via Egg-white route

    NASA Astrophysics Data System (ADS)

    Gabal, M. A.; Bayoumy, W. A.; Saeed, A.; Al Angari, Y. M.

    2015-10-01

    Nano-crystalline ferrites with formula Ni0.8Zn0.2CrxFe2-xO4 (x = 0.0-1.0) was synthesized using Egg-white auto-combustion method. An appropriate mechanism for complexation and ferrite formation was suggested. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and a.c. electrical conductivity measurements were utilized to study the effect of Cr-substitution and its impact on particle size and electro-magnetic properties of the investigated ferrite. X-ray diffraction revealed single-phase cubic structure. The decrease in lattice parameter with increasing chromium was discussed in the view of ionic radii. TEM exhibited cubic agglomerated crystals with sizes between 10 and 20 nm. The decrease in the saturation magnetization and coercivity estimated through VSM measurements with increasing Cr-content indicated the preferential occupation of Cr3+ ions in the octahedral sites. Ac-conductivity measurements revealed semiconducting behavior of the entire investigated samples at high temperature and revealed a magnetic transition from ferromagnetic to paramagnetic for the samples with Cr-content up to 0.2. The conductivity values as well as the conduction activation energies indicated that the Cr3+ ions do not participate in the conduction and thus limit the Fe2+-Fe3+ conduction by blocking up Fe2+-Fe3+ transformation.

  5. Flexible transparent PES/silver nanowires/PET sandwich-structured film for high-efficiency electromagnetic interference shielding.

    PubMed

    Hu, Mingjun; Gao, Jiefeng; Dong, Yucheng; Li, Kai; Shan, Guangcun; Yang, Shiliu; Li, Robert Kwok-Yiu

    2012-05-01

    We have developed a kind of high-yield synthesis strategy for silver nanowires by a two-step injection polyol method. Silver nanowires and polyethylene oxide (PEO) (M(w) = 900,000) were prepared in a homogeneous-coating ink. Wet composite films with different thicknesses were fabricated on a PET substrate by drawn-down rod-coating technology. Silver nanowires on PET substrates present a homogeneous distribution under the assistance of PEO. Then PEO was thermally removed in situ at a relatively low temperature attributed to its special thermal behavior under atmospheric conditions. As-prepared metallic nanowire films on PET substrates show excellent stability and a good combination of conductivity and light transmission. A layer of transparent poly(ethersulfones) (PESs) was further coated on silver nanowire networks by the same coating method to prevent the shedding and corrosion of silver nanowires. Sandwich-structured flexible transparent films were obtained and displayed excellent electromagnetic interference (EMI) shielding effectiveness. PMID:22533864

  6. Electromagnetic Fields

    MedlinePlus

    ... cancer. Some people worry that wireless and cellular phones cause cancer. They give off radio-frequency energy (RF), a form of electromagnetic radiation. Scientists need to do more research on this ...

  7. Design of electromagnetic energy harvesters for large-scale structural vibration applications

    NASA Astrophysics Data System (ADS)

    Cassidy, Ian L.; Scruggs, Jeffrey T.; Behrens, Sam

    2011-03-01

    This paper reports on the design and experimental validation of transducers for energy harvesting from largescale civil structures, for which the power levels can be above 100W, and disturbance frequencies below 1Hz. The transducer consists of a back-driven ballscrew, coupled to a permanent-magnet synchronous machine, and power harvesting is regulated via control of a four-quadrant power electronic drive. Design tradeoffs between the various subsystems (including the controller, electronics, machine, mechanical conversion, and structural system) are illustrated, and an approach to device optimization is presented. Additionally, it is shown that nonlinear dissipative behavior of the electromechanical system must be properly characterized in order to assess the viability of the technology, and also to correctly design the matched impedance to maximize harvested power. An analytical expression for the average power generated across a resistive load is presented, which takes the nonlinear dissipative behavior of the device into account. From this expression the optimal resistance is determined to maximize power for an example in which the transducer is coupled to base excited tuned mass damper (TMD). Finally, the results from the analytical model are compared to an experimental system that uses hybrid testing to simulated the dynamics of the TMD.

  8. Quasimodal expansion of electromagnetic fields in open two-dimensional structures

    NASA Astrophysics Data System (ADS)

    Vial, Benjamin; Zolla, Frédéric; Nicolet, André; Commandré, Mireille

    2014-02-01

    A quasimodal expansion method (QMEM) is developed to model and understand the scattering properties of arbitrary shaped two-dimensional open structures. In contrast with the bounded case which has only a discrete spectrum (real in the lossless media case), open resonators show a continuous spectrum composed of radiation modes and may also be characterized by resonances associated to complex eigenvalues (quasimodes). The use of a complex change of coordinates to build perfectly matched layers allows the numerical computation of those quasimodes and of approximate radiation modes. Unfortunately, the transformed operator at stake is no longer self-adjoint, and classical modal expansion fails. To cope with this issue, we consider an adjoint eigenvalue problem whose eigenvectors are biorthogonal to the eigenvectors of the initial problem. The scattered field is expanded on this complete set of modes leading to a reduced order model of the initial problem. The different contributions of the eigenmodes to the scattered field unambiguously appears through the modal coefficients, allowing us to analyze how a given mode is excited when changing incidence parameters. This gives physical insights to the spectral properties of different open structures such as nanoparticles and diffraction gratings. Moreover, the QMEM proves to be extremely efficient for the computation of local density of states.

  9. Three-dimensional electromagnetic modeling in complex geoelectrical structures with multiple inhomogeneous domains

    NASA Astrophysics Data System (ADS)

    Endo, M.; Cuma, M.; Zhdanov, M. S.

    2009-12-01

    In geophysical applications, it is difficult to describe an earth structure using a horizontally layered background conductivity model, which is required for efficient implementation of the conventional integral equation (IE) approach. As a result, a large domain of interest with anomalous conductivity distribution needs to be discretized, which complicates the computations. Contrary to conventional IE, finite-difference (FD), or finite-element (FE) techniques, the new multiple-domain (MD) IE method allows us to consider multiple inhomogeneous domains, where the conductivity distribution is different from that of the background, and to use independent discretizations for different domains. This reduces dramatically the computational resources required for large-scale modeling. In addition, using this method, we can analyze the response of each domain separately without an inappropriate use of the superposition principle for EM field calculations. The numerical modeling results demonstrate that the MD IE method can be effectively used not only for studying the EM fields in complex geoelectrical models with multiple inhomogeneous domains, but also for evaluating the ability of an EM survey to detect complex geoelectrical targets.

  10. Investigations of the structure and electromagnetic interactions of few-body systems. Progress report, 1 July 1992--30 June 1993

    SciTech Connect

    Lehman, D.R.; Haberzettl, H.; Maximon, L.C.; Parke, W.C.; Bennhold, C.; Ito, Hiroshi; Pratt, R.K.; Najmeddine, M.; Rakei, A.

    1993-07-01

    The emphasis of the nuclear theory group has been on the structure and electromagnetic interactions of few-body nuclei. Both low- and intermediate-energy electromagnetic disintegration of these nuclei is considered, including coherent photoproduction of {pi} mesons. When the excitation energy of the target nucleus is low, the aim is to handle the continuum part of the theoretical work numerically with no approximations, that is, by means of full three- or four-body dynamics. When structure questions are the issue, numerically accurate calculations are always carried through, limited only by the underlying two-body or three-body interactions used as input. A central goal is to carry through state-of-the-art few-body calculations that will serve as a means of determining at what point standard nuclear physics requires introduction of relativity and/or quark degrees of freedom in order to understand the phenomena in question.

  11. Gravitational scattering of electromagnetic radiation

    NASA Technical Reports Server (NTRS)

    Brooker, J. T.; Janis, A. I.

    1980-01-01

    The scattering of electromagnetic radiation by linearized gravitational fields is studied to second order in a perturbation expansion. The incoming electromagnetic radiation can be of arbitrary multipole structure, and the gravitational fields are also taken to be advanced fields of arbitrary multipole structure. All electromagnetic multipole radiation is found to be scattered by gravitational monopole and time-varying dipole fields. No case has been found, however, in which any electromagnetic multipole radiation is scattered by gravitational fields of quadrupole or higher-order multipole structure. This lack of scattering is established for infinite classes of special cases, and is conjectured to hold in general. The results of the scattering analysis are applied to the case of electromagnetic radiation scattered by a moving mass. It is shown how the mass and velocity may be determined by a knowledge of the incident and scattered radiation.

  12. Current transfer length in multi-filamentary superconducting NbTi and Nb3Sn strands; experiments and models

    NASA Astrophysics Data System (ADS)

    Zhou, C.; Dhallé, M.; ten Kate, H. H. J.; Nijhuis, A.

    2014-09-01

    The current transfer length of multi-filamentary superconducting NbTi and Nb3Sn strands was measured and analyzed. The aim is to understand and quantify the current distribution process between matrix and superconducting filaments occurring at current injection joints or shunting localized interruptions like originated by transverse cracks or high strain, temperature, or magnetic field in filaments. The current transfer length was investigated on two different multi-filamentary Nb3Sn wires and one NbTi wire. Opposite to earlier clarifications, it was found that the current transfer length cannot be simply represented by a single parameter but depends on the ratio of transport current and critical current and the distance from the current injection point or local interruption of the superconducting path in the filamentary zone. With the aid of our numerical 3D multi-filamentary strand model, simulations were performed showing excellent agreement with the experimental data. For broader use, analytical formulae are proposed to determine the current transfer length for multi-filamentary superconductors with complex cross-sectional layout. The increasing current transfer length with the higher injected current and/or along with the distance away from the current injection point is explained by a progressive current penetration, which is caused by the high resistive matrix layers and complex layout. For the experimental results obtained here, the analytical and numerical simulation results show good agreement against the experimentally measured data from the potential-tips along the strand length.

  13. Local inhomogeneity and filamentary superconductivity in Pr-doped CaFe2As2.

    PubMed

    Gofryk, Krzysztof; Pan, Minghu; Cantoni, Claudia; Saparov, Bayrammurad; Mitchell, Jonathan E; Sefat, Athena S

    2014-01-31

    We use multiscale techniques to determine the extent of local inhomogeneity and superconductivity in Ca0.86Pr0.14Fe2As2 single crystal. The inhomogeneity is manifested as a spatial variation of the praseodymium concentration, local density of states, and superconducting order parameter. We show that the high-Tc superconductivity emerges from cloverlike defects associated with Pr dopants. The highest Tc is observed in both the tetragonal and collapsed tetragonal phases, and its filamentary nature is a consequence of nonuniform Pr distribution that develops localized, isolated superconducting regions within the crystals. PMID:24580484

  14. Analytical estimations for thermal crosstalk, retention, and scaling limits in filamentary resistive memory

    NASA Astrophysics Data System (ADS)

    Lohn, Andrew J.; Mickel, Patrick R.; Marinella, Matthew J.

    2014-06-01

    We discuss the thermal effects on scaling, retention, and error rate in filamentary resistive memories from a theoretical perspective using an analytical approach. Starting from the heat equation, we derive the temperature profile surrounding a resistive memory device and calculate its effect on neighboring devices. We outline the engineering tradeoffs that are expected with continued scaling, such as retention and power use per device. Based on our calculations, we expect scaling to continue well below 10 nm, but that the effect of heating from neighboring devices needs to be considered for some applications even at current manufacturing capabilities. We discuss possible designs to alleviate some of these effects while further increasing device density.

  15. Local Inhomogeneity and Filamentary Superconductivity in Pr-Doped CaFe2As2

    NASA Astrophysics Data System (ADS)

    Gofryk, Krzysztof; Pan, Minghu; Cantoni, Claudia; Saparov, Bayrammurad; Mitchell, Jonathan E.; Sefat, Athena S.

    2014-01-01

    We use multiscale techniques to determine the extent of local inhomogeneity and superconductivity in Ca0.86Pr0.14Fe2As2 single crystal. The inhomogeneity is manifested as a spatial variation of the praseodymium concentration, local density of states, and superconducting order parameter. We show that the high-Tc superconductivity emerges from cloverlike defects associated with Pr dopants. The highest Tc is observed in both the tetragonal and collapsed tetragonal phases, and its filamentary nature is a consequence of nonuniform Pr distribution that develops localized, isolated superconducting regions within the crystals.

  16. Electromagnetic Propulsion

    NASA Technical Reports Server (NTRS)

    Schafer, Charles

    2000-01-01

    The design and development of an Electromagnetic Propulsion is discussed. Specific Electromagnetic Propulsion Topics discussed include: (1) Technology for Pulse Inductive Thruster (PIT), to design, develop, and test of a multirepetition rate pulsed inductive thruster, Solid-State Switch Technology, and Pulse Driver Network and Architecture; (2) Flight Weight Magnet Survey, to determine/develop light weight high performance magnetic materials for potential application Advanced Space Flight Systems as these systems develop; and (3) Magnetic Flux Compression, to enable rapid/robust/reliable omni-planetary space transportation within realistic development and operational costs constraints.

  17. Self-organization of large-scale ULF electromagnetic wave structures in their interaction with nonuniform zonal winds in the ionospheric E region

    SciTech Connect

    Aburjania, G. D.; Chargazia, Kh. Z.

    2011-02-15

    A study is made of the generation and subsequent linear and nonlinear evolution of ultralow-frequency planetary electromagnetic waves in the E region of a dissipative ionosphere in the presence of a nonuniform zonal wind (a sheared flow). Hall currents flowing in the E region and such permanent global factors as the spatial nonuniformity of the geomagnetic field and of the normal component of the Earth's angular velocity give rise to fast and slow planetary-scale electromagnetic waves. The efficiency of the linear amplification of planetary electromagnetic waves in their interaction with a nonuniform zonal wind is analyzed. When there are sheared flows, the operators of linear problems are non-self-conjugate and the corresponding eigenfunctions are nonorthogonal, so the canonical modal approach is poorly suited for studying such motions and it is necessary to utilize the so-called nonmodal mathematical analysis. It is shown that, in the linear evolutionary stage, planetary electromagnetic waves efficiently extract energy from the sheared flow, thereby substantially increasing their amplitude and, accordingly, energy. The criterion for instability of a sheared flow in an ionospheric medium is derived. As the shear instability develops and the perturbation amplitude grows, a nonlinear self-localization mechanism comes into play and the process ends with the self-organization of nonlinear, highly localized, solitary vortex structures. The system thus acquires a new degree of freedom, thereby providing a new way for the perturbation to evolve in a medium with a sheared flow. Depending on the shape of the sheared flow velocity profile, nonlinear structures can be either purely monopole vortices or vortex streets against the background of the zonal wind. The accumulation of such vortices can lead to a strongly turbulent state in an ionospheric medium.

  18. Signatures of filamentary superconductivity in antiferromagnetic BaFe2As2 single crystals

    NASA Astrophysics Data System (ADS)

    Moseley, D.; Yates, K. A.; Branford, W. R.; Sefat, A. S.; Mandrus, D.; Stuard, S. J.; Salem-Sugui, S.; Ghivelder, L.; Cohen, L. F.

    2015-08-01

    In this paper, we present ac susceptibility and magnetotransport measurements on aged single crystals of the ferropnictide parent compound, BaFe2As2 with a paramagnetic-to-antiferromagnetic transition temperature of 134 K. The ac susceptibility shows the clear onset of a partial diamagnetic response with an onset temperature, commensurate with a subtle downturn in resistivity at approximately 20 K. Below 20 K the magnetotransport shows in-plane anisotropy, magnetic-field history dependence and a hysteretic signature. Above 20 K the crystals show the widely reported high-field linear magnetoresistance. An enhanced noise signature in ac susceptibility is observed above 20 K, which varies in character with amplitude and frequency of the ac signal. The hysteresis in magnetoresistance and the observed sensitivity of the superconducting phase to the amplitude of the ac signal are indicative characteristics of granular or weakly linked filamentary superconductivity. These features taken together with the observed noise signature above T{c} suggests a link between the formation of the superconducting filamentary phase and the freezing of antiphase domain walls, known to exist in these materials.

  19. Neuromorphic crossbar circuit with nanoscale filamentary-switching binary memristors for speech recognition

    PubMed Central

    2014-01-01

    In this paper, a neuromorphic crossbar circuit with binary memristors is proposed for speech recognition. The binary memristors which are based on filamentary-switching mechanism can be found more popularly and are easy to be fabricated than analog memristors that are rare in materials and need a more complicated fabrication process. Thus, we develop a neuromorphic crossbar circuit using filamentary-switching binary memristors not using interface-switching analog memristors. The proposed binary memristor crossbar can recognize five vowels with 4-bit 64 input channels. The proposed crossbar is tested by 2,500 speech samples and verified to be able to recognize 89.2% of the tested samples. From the statistical simulation, the recognition rate of the binary memristor crossbar is estimated to be degraded very little from 89.2% to 80%, though the percentage variation in memristance is increased very much from 0% to 15%. In contrast, the analog memristor crossbar loses its recognition rate significantly from 96% to 9% for the same percentage variation in memristance. PMID:25489283

  20. Neuromorphic crossbar circuit with nanoscale filamentary-switching binary memristors for speech recognition

    NASA Astrophysics Data System (ADS)

    Truong, Son Ngoc; Ham, Seok-Jin; Min, Kyeong-Sik

    2014-11-01

    In this paper, a neuromorphic crossbar circuit with binary memristors is proposed for speech recognition. The binary memristors which are based on filamentary-switching mechanism can be found more popularly and are easy to be fabricated than analog memristors that are rare in materials and need a more complicated fabrication process. Thus, we develop a neuromorphic crossbar circuit using filamentary-switching binary memristors not using interface-switching analog memristors. The proposed binary memristor crossbar can recognize five vowels with 4-bit 64 input channels. The proposed crossbar is tested by 2,500 speech samples and verified to be able to recognize 89.2% of the tested samples. From the statistical simulation, the recognition rate of the binary memristor crossbar is estimated to be degraded very little from 89.2% to 80%, though the percentage variation in memristance is increased very much from 0% to 15%. In contrast, the analog memristor crossbar loses its recognition rate significantly from 96% to 9% for the same percentage variation in memristance.

  1. Electromagnetic Reciprocity.

    SciTech Connect

    Aldridge, David F.

    2014-11-01

    A reciprocity theorem is an explicit mathematical relationship between two different wavefields that can exist within the same space - time configuration. Reciprocity theorems provi de the theoretical underpinning for mod ern full waveform inversion solutions, and also suggest practical strategies for speed ing up large - scale numerical modeling of geophysical datasets . In the present work, several previously - developed electromagnetic r eciprocity theorems are generalized to accommodate a broader range of medi um, source , and receiver types. Reciprocity relations enabling the interchange of various types of point sources and point receivers within a three - dimensional electromagnetic model are derived. Two numerical modeling algorithms in current use are successfully tested for adherence to reciprocity. Finally, the reciprocity theorem forms the point of departure for a lengthy derivation of electromagnetic Frechet derivatives. These mathe matical objects quantify the sensitivity of geophysical electromagnetic data to variatio ns in medium parameters, and thus constitute indispensable tools for solution of the full waveform inverse problem. ACKNOWLEDGEMENTS Sandia National Labor atories is a multi - program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE - AC04 - 94AL85000. Signif icant portions of the work reported herein were conducted under a Cooperative Research and Development Agreement (CRADA) between Sandia National Laboratories (SNL) and CARBO Ceramics Incorporated. The author acknowledges Mr. Chad Cannan and Mr. Terry Pa lisch of CARBO Ceramics, and Ms. Amy Halloran, manager of SNL's Geophysics and Atmospheric Sciences Department, for their interest in and encouragement of this work. Special thanks are due to Dr . Lewis C. Bartel ( recently retired from Sandia National Labo ratories and now a

  2. Fabrication and characterization of direct-written 3D TiO2 woodpile electromagnetic bandgap structures

    NASA Astrophysics Data System (ADS)

    Li, Ji-Jiao; Li, Bo; Peng, Qin-Mei; Zhou, Ji; Li, Long-Tu

    2014-09-01

    Three groups of three-dimensional (3D) TiO2 woodpile electromagnetic gap materials with tailed rheological properties were developed for direct-written fabrication. Appropriate amount of polyethyleneimine (PEI) dispersants allow the preparation of TiO2 inks with a high solid content of 42 vol.%, which enables them to flow through the nozzles easily. The inks exhibit pseudoplastic behavior. The measured microwave characteristics of the results agree well with simulations based on plane wave expansion (PWE).

  3. Morphology-Control Synthesis of a Core-Shell Structured NiCu Alloy with Tunable Electromagnetic-Wave Absorption Capabilities.

    PubMed

    Zhao, Biao; Zhao, Wanyu; Shao, Gang; Fan, Bingbing; Zhang, Rui

    2015-06-17

    In this work, dendritelike and rodlike NiCu alloys were prepared by a one-pot hydrothermal process at various reaction temperatures (120, 140, and 160 °C). The structure and morphology were analyzed by scanning electron microscopy, energy-dispersive spectrometry, X-ray diffraction, and transmission electron microscopy, which that demonstrate NiCu alloys have core-shell heterostructures with Ni as the shell and Cu as the core. The formation mechanism of the core-shell structures was also discussed. The uniform and perfect dendritelike NiCu alloy obtained at 140 °C shows outstanding electromagnetic-wave absorption properties. The lowest reflection loss (RL) of -31.13 dB was observed at 14.3 GHz, and the effective absorption (below -10 dB, 90% attenuation) bandwidth can be adjusted between 4.4 and 18 GHz with a thin absorber thickness in the range of 1.2-4.0 mm. The outstanding electromagnetic-wave-absorbing properties are ascribed to space-charge polarization arising from the heterogeneous structure of the NiCu alloy, interfacial polarization between the alloy and paraffin, and continuous micronetworks and vibrating microcurrent dissipation originating from the uniform and perfect dendritelike shape of NiCu prepared at 140 °C. PMID:26018739

  4. Intra-cellular traffic: bio-molecular motors on filamentary tracks

    NASA Astrophysics Data System (ADS)

    Chowdhury, D.; Basu, A.; Garai, A.; Greulich, P.; Nishinari, K.; Schadschneider, A.; Tripathi, T.

    2008-08-01

    Molecular motors are macromolecular complexes which use some form of input energy to perform mechanical work. The filamentary tracks, on which these motors move, are made of either proteins (e.g., microtubules) or nucleic acids (DNA or RNA). Often, many such motors move simultaneously on the same track and their collective properties have superficial similarities with vehicular traffic on highways. The models we have developed provide "unified" description: in the low-density limit, a model captures the transport properties of a single motor while, at higher densities the same model accounts for the collective spatio-temporal organization of interacting motors. By drawing analogy with vehicular traffic, we have introduced novel quantities for characterizing the nature of the spatio-temporal organization of molecular motors on their tracks. We show how the traffic-like intracellular collective phenomena depend on the mechano-chemistry of the corresponding individual motors.

  5. Investigation of the clinical features in filamentary keratitis in Hangzhou, east of China

    PubMed Central

    Chen, Siming; Ruan, Yimeng; Jin, Xiuming

    2016-01-01

    Abstract Filamentary keratitis (FK) is a chronic and recurrent disorder of the cornea. FK is reportedly associated with various kinds of ocular surface diseases or conditions. Until now, there have been lacks of studies based on quantitative sample analysis concerning FK incidence regularity and inducement characteristics at different ages. This was a retrospective study of 147 patients (162 eyes) with FK who had been continuously and completely recorded from August 2012 to August 2015 at the Second Affiliated Hospital of Zhejiang University in Hangzhou, east of China. Our results suggest that the causative factors of FK varied at different ages and the distribution of filaments on the corneal surface was also diverse with different inducements. By exploring the frequency and clinical features of FK, we believe that the findings from our research will be clinically significant and aid in the early prevention and treatment guidance of the disease. PMID:27583881

  6. Rectifying filamentary resistive switching in ion-exfoliated LiNbO3 thin films

    NASA Astrophysics Data System (ADS)

    Pan, Xinqiang; Shuai, Yao; Wu, Chuangui; Luo, Wenbo; Sun, Xiangyu; Zeng, Huizhong; Zhou, Shengqiang; Böttger, Roman; Ou, Xin; Mikolajick, Thomas; Zhang, Wanli; Schmidt, Heidemarie

    2016-01-01

    In this letter, we report the resistive switching properties of ion-exfoliated LiNbO3 thin films. After annealing in Ar or in vacuum, electro-forming has been observed on the thin films, and the oxygen gas bubbles can be eliminated by tuning the annealing conditions in order to prevent the destruction of top electrodes. The thin films show rectifying filamentary resistive switching after forming, which is interpreted by a simplified model that the local filament does not penetrate throughout the LiNbO3 thin film, resulting in asymmetric contact barriers at the two interfaces. The well controlled electro-forming step and the highly reproducible switching properties are attributed to the more homogeneous distribution of defects in single crystalline materials and the specific geometry of filament.

  7. Filamentary resistive switching in amorphous and polycrystalline Nb2O5 thin films

    NASA Astrophysics Data System (ADS)

    Mähne, H.; Berger, L.; Martin, D.; Klemm, V.; Slesazeck, S.; Jakschik, S.; Rafaja, D.; Mikolajick, T.

    2012-06-01

    In this paper, the correlation between the crystallinity of reactively sputtered Nb2O5 layers on Pt bottom electrode and their resistive switching behavior was investigated. It was found that the amorphous phase can transformed to an orthorhombic phase by annealing in argon at 650 °C. Smooth surfaces of the crystalline samples with RMS roughness of 1 nm were produced. By using the stack Al/Nb2O5/Pt a Schottky diode was produced and a barrier height of 1.0 eV for the argon annealed sample was found. For the amorphous sample, a Frenkel-Poole emission mechanism was found with the activation energy of 0.21 eV. After an electric forming process a filamentary resistive switching was observed for both types of samples.

  8. Investigation of the clinical features in filamentary keratitis in Hangzhou, east of China.

    PubMed

    Chen, Siming; Ruan, Yimeng; Jin, Xiuming

    2016-08-01

    Filamentary keratitis (FK) is a chronic and recurrent disorder of the cornea. FK is reportedly associated with various kinds of ocular surface diseases or conditions. Until now, there have been lacks of studies based on quantitative sample analysis concerning FK incidence regularity and inducement characteristics at different ages. This was a retrospective study of 147 patients (162 eyes) with FK who had been continuously and completely recorded from August 2012 to August 2015 at the Second Affiliated Hospital of Zhejiang University in Hangzhou, east of China. Our results suggest that the causative factors of FK varied at different ages and the distribution of filaments on the corneal surface was also diverse with different inducements.By exploring the frequency and clinical features of FK, we believe that the findings from our research will be clinically significant and aid in the early prevention and treatment guidance of the disease. PMID:27583881

  9. Electromagnetic Hammer for Metalworking

    NASA Technical Reports Server (NTRS)

    Anderson, S. A.; Brunet, F.; Dowd, A.; Durham, R.; Ezell, J.; Gorr, G.; Hartley, D.; Jackson, F.; Marchand, J.; Macfarlane, W.; Nameth, P.; Okelly, K.; Phillips, H.; Rollo, J.; Rupert, E.; Sykes, H.; Vitrano, E.; Woods, M.

    1986-01-01

    High eddy currents apply pressure for cold-forming. Coil housing constructed for mechanical strength to hold coil against magnetic force, to maintain electrical contact with coil ends, and to maintain insulation between coil turns. Drilled holes placed to facilitate release of bubbles during potting. In contrast with mechanical hammers, electromagnetic hammer requires no dynamic material contact with workpiece; consequently, produces almost no change in metal grain structure.

  10. Radiation and scattering by thin-wire structures in the complex frequency domain. [electromagnetic theory for thin-wire antennas

    NASA Technical Reports Server (NTRS)

    Richmond, J. H.

    1974-01-01

    Piecewise-sinusoidal expansion functions and Galerkin's method are employed to formulate a solution for an arbitrary thin-wire configuration in a homogeneous conducting medium. The analysis is performed in the real or complex frequency domain. In antenna problems, the solution determines the current distribution, impedance, radiation efficiency, gain and far-field patterns. In scattering problems, the solution determines the absorption cross section, scattering cross section and the polarization scattering matrix. The electromagnetic theory is presented for thin wires and the forward-scattering theorem is developed for an arbitrary target in a homogeneous conducting medium.

  11. Earth's Electromagnetic Environment

    NASA Astrophysics Data System (ADS)

    Constable, Catherine

    2016-01-01

    The natural spectrum of electromagnetic variations surrounding Earth extends across an enormous frequency range and is controlled by diverse physical processes. Electromagnetic (EM) induction studies make use of external field variations with frequencies ranging from the solar cycle which has been used for geomagnetic depth sounding through the 10^{-4}-10^4 Hz frequency band widely used for magnetotelluric and audio-magnetotelluric studies. Above 10^4 Hz, the EM spectrum is dominated by man-made signals. This review emphasizes electromagnetic sources at ˜1 Hz and higher, describing major differences in physical origin and structure of short- and long-period signals. The essential role of Earth's internal magnetic field in defining the magnetosphere through its interactions with the solar wind and interplanetary magnetic field is briefly outlined. At its lower boundary, the magnetosphere is engaged in two-way interactions with the underlying ionosphere and neutral atmosphere. Extremely low-frequency (3 Hz-3 kHz) electromagnetic signals are generated in the form of sferics, lightning, and whistlers which can extend to frequencies as high as the VLF range (3-30 kHz).The roughly spherical dielectric cavity bounded by the ground and the ionosphere produces the Schumann resonance at around 8 Hz and its harmonics. A transverse resonance also occurs at 1.7-2.0 kHz arising from reflection off the variable height lower boundary of the ionosphere and exhibiting line splitting due to three-dimensional structure. Ground and satellite observations are discussed in the light of their contributions to understanding the global electric circuit and for EM induction studies.

  12. 3-D imaging of large scale buried structure by 1-D inversion of very early time electromagnetic (VETEM) data

    USGS Publications Warehouse

    Aydmer, A.A.; Chew, W.C.; Cui, T.J.; Wright, D.L.; Smith, D.V.; Abraham, J.D.

    2001-01-01

    A simple and efficient method for large scale three-dimensional (3-D) subsurface imaging of inhomogeneous background is presented. One-dimensional (1-D) multifrequency distorted Born iterative method (DBIM) is employed in the inversion. Simulation results utilizing synthetic scattering data are given. Calibration of the very early time electromagnetic (VETEM) experimental waveforms is detailed along with major problems encountered in practice and their solutions. This discussion is followed by the results of a large scale application of the method to the experimental data provided by the VETEM system of the U.S. Geological Survey. The method is shown to have a computational complexity that is promising for on-site inversion.

  13. Three-dimensional imaging of subsurface structural patterns using quantitative large-scale multiconfiguration electromagnetic induction data

    NASA Astrophysics Data System (ADS)

    von Hebel, Christian; Rudolph, Sebastian; Mester, Achim; Huisman, Johan A.; Kumbhar, Pramod; Vereecken, Harry; van der Kruk, Jan

    2014-03-01

    Electromagnetic induction (EMI) systems measure the soil apparent electrical conductivity (ECa), which is related to the soil water content, texture, and salinity changes. Large-scale EMI measurements often show relevant areal ECa patterns, but only few researchers have attempted to resolve vertical changes in electrical conductivity that in principle can be obtained using multiconfiguration EMI devices. In this work, we show that EMI measurements can be used to determine the lateral and vertical distribution of the electrical conductivity at the field scale and beyond. Processed ECa data for six coil configurations measured at the Selhausen (Germany) test site were calibrated using inverted electrical resistivity tomography (ERT) data from a short transect with a high ECa range, and regridded using a nearest neighbor interpolation. The quantitative ECa data at each grid node were inverted using a novel three-layer inversion that uses the shuffled complex evolution (SCE) optimization and a Maxwell-based electromagnetic forward model. The obtained 1-D results were stitched together to form a 3-D subsurface electrical conductivity model that showed smoothly varying electrical conductivities and layer thicknesses, indicating the stability of the inversion. The obtained electrical conductivity distributions were validated with low-resolution grain size distribution maps and two 120 m long ERT transects that confirmed the obtained lateral and vertical large-scale electrical conductivity patterns. Observed differences in the EMI and ERT inversion results were attributed to differences in soil water content between acquisition days. These findings indicate that EMI inversions can be used to infer hydrologically active layers.

  14. Investigations of the structure and electromagnetic interactions of few-body systems. Progress report, 1 August 1991--31 July 1992

    SciTech Connect

    Lehman, D.R.; Haberzettl, H.; Maximon, L.C.; Parke, W.C.

    1992-07-01

    In order to make it easy for the reader to see the specific research carried out and the progress made, the following report of progress is done by topic. Each item has a format layout of Topic, Investigators, Objective, Significance, and Description of Progress, followed at the end by the relevant references. As is clear from the topics listed, the emphasis of the George Washington University (GWU) theory group has been on the structure and electromagnetic interactions of few-body nuclei. Both low- and intermediate-energy electromagnetic disintegration of these nuclei is considered. When the excitation energy of the target nucleus is low, the aim has been to handle the continuum part of the theoretical work numerically with no approximations, that is, by means of full three- or four-body dynamics. When structure questions axe the issue, numerically accurate calculations axe always carried through, limited only by the underlying two-body or three-body interactions used as input. Implicit in our work is the question of how far one can go within the traditional nuclear physics framework, i.e., nucleons and mesons in a nonrelativistic setting. Our central goal is to carry through state-of-the-art fewbody calculations that wig serve as a means of determining at what point standard nuclear physics requires quark degrees of freedom in order to understand the phenomena in question. So far, in the problems considered, there has been no evidence of the necessity to go beyond the traditional approach, though we always keep in mind that possibility. As our work is involved with questions in the intermediate-energy realm, moving from a nonrelativistic framework to a relativistic one is always a consideration. Currently, for the problems that have been pursued in this domain of energy, the issues concern far more the mechanisms of the reactions and structural questions than the need to move to relativistic dynamics.

  15. Electromagnetic and acoustic waves in metamaterials and structures (Scientific session of the Physical Sciences Division of the Russian Academy of Sciences, 24 February 2011)

    NASA Astrophysics Data System (ADS)

    2011-11-01

    The scientific session, titled "Electromagnetic and acoustic waves in metamaterials and structures", of the Physical Sciences Division of the Russian Academy of Sciences (RAS) was held on February 24, 2011 in the conference hall of the Lebedev Physical Institute, RAS. The agenda of the session announced on the website www.gpad.ac.ru of the RAS Physical Sciences Division featured presentation of the following reports: (1) Veselago V G (A M Prokhorov General Physics Institute, RAS, Moscow, and Moscow Institute of Physics and Technology, Dolgoprudnyi, Moscow region) "Waves in metamaterials: their role in modern physics"; (2) Burov V A, Voloshinov V B, Dmitriev K V, Polikarpova N V (Lomonosov Moscow State University, Moscow) "Acoustic waves in metamaterials, anisotropic crystals and anomalously refracting structures"; (3) Shvartsburg A B (Joint Institute for High Temperatures, RAS, Moscow), Erokhin N S (Space Research Institute, RAS, Moscow) "Resonant tunneling of ultrashort electromagnetic pulses in gradient metamaterials: paradoxes and prospects"; (4) Petnikov V G (A M Prokhorov General Physics Institute, RAS, Moscow), Stromkov A A (Institute of Applied Physics, RAS, Nizhny Novgorod) "Focusing of low-frequency sound fields on the ocean shelf"; (5) Luchinin A G, Khil'ko A I (Institute of Applied Physics, RAS, Nizhny Novgorod) "Low-mode acoustics of shallow water waveguides"; (6) Esipov I B (RAS Research Council on Acoustics, Moscow) "Basic results for 2010 in the field of acoustics as presented at a RAS Council session". Papers written on the basis of these oral presentations are published below. • Waves in metamaterials: their role in modern physics, V G Veselago Physics-Uspekhi, 2011, Volume 54, Number 11, Pages 1161-1165 • Acoustic waves in metamaterials, crystals, and anomalously refracting structures, V A Burov, V B Voloshinov, K V Dmitriev, N V Polikarpova Physics-Uspekhi, 2011, Volume 54, Number 11, Pages 1165-1170 • Resonant tunneling of ultrashort

  16. Filamentary structures in dense plasma focus: Current filaments or vortex filaments?

    SciTech Connect

    Soto, Leopoldo Pavez, Cristian; Moreno, José; Castillo, Fermin; Veloso, Felipe; Auluck, S. K. H.

    2014-07-15

    Recent observations of an azimuthally distributed array of sub-millimeter size sources of fusion protons and correlation between extreme ultraviolet (XUV) images of filaments with neutron yield in PF-1000 plasma focus have re-kindled interest in their significance. These filaments have been described variously in literature as current filaments and vortex filaments, with very little experimental evidence in support of either nomenclature. This paper provides, for the first time, experimental observations of filaments on a table-top plasma focus device using three techniques: framing photography of visible self-luminosity from the plasma, schlieren photography, and interferometry. Quantitative evaluation of density profile of filaments from interferometry reveals that their radius closely agrees with the collision-less ion skin depth. This is a signature of relaxed state of a Hall fluid, which has significant mass flow with equipartition between kinetic and magnetic energy, supporting the “vortex filament” description. This interpretation is consistent with empirical evidence of an efficient energy concentration mechanism inferred from nuclear reaction yields.

  17. An Ad-hoc Satellite Network to Measure Filamentary Current Structures in the Auroral Zone

    NASA Astrophysics Data System (ADS)

    Nabong, C.; Fritz, T. A.; Semeter, J. L.

    2014-12-01

    An ad-hoc cubesat-based satellite network project known as ANDESITE is under development at Boston University. It aims to develop a dense constellation of easy-to-use, rapidly-deployable low-cost wireless sensor nodes in space. The objectives of the project are threefold: 1) Demonstrate viability of satellite based sensor networks by deploying an 8-node miniature sensor network to study the filamentation of the field aligned currents in the auroral zones of the Earth's magnetosphere. 2) Test the scalability of proposed protocols, including localization techniques, tracking, data aggregation, and routing, for a 3 dimensional wireless sensor network using a "flock" of nodes. 3) Construct a 6U Cube-sat running the Android OS as an integrated constellation manager, data mule and sensor node deplorer. This small network of sensor nodes will resolve current densities at different spatial resolutions in the near-Earth magnetosphere using measurements from magnetometers with 1-nT sensitivities and 0.2 nT/√Hz self-noise. Mapping of these currents will provide new constraints for models of auroral particle acceleration, wave-particle interactions, ionospheric destabilization, and other kinetic processes operating in the low-beta plasma of the near Earth magnetosphere.

  18. Investigations of temporal reshaping during filamentary propagation with application to impulsive raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Odhner, Johanan

    Femtosecond laser filamentation in gaseous media is a new source of broadband, ultrashort radiation that has the potential for application to many fields of research. In this dissertation filamentation is studied with a view to understanding the underlying physics governing the formation and propagation dynamics of filamentation, as well as to developing a method for vibrational spectroscopy based on the filament-induced impulsive vibrational excitation of molecules in the filamentation region. In pursuit of a better understanding of the underlying physical processes driving filamentation, the development of a new method for characterizing high intensity ultrashort laser pulses is presented, wherein two laser beams generate a transient grating in a noble gas, causing the pulse undergoing filamentation to diffract from the grating. Measuring the spectrum as a function of time delay between the filament and probe beams generates a spectrogram that can be inverted to recover the spectral and temporal phase and amplitude of the filamentary pulse. This technique enables measurement of the filamentary pulse in its native environment, offering a window into the pulse dynamics as a function of propagation distance. The intrinsic pulse shortening observed during filamentation leads to the impulsive excitation of molecular vibrations, which can be used to understand the dynamics of filamentation as well. Combined measurements of the longitudinally-resolved filament Raman spectrum, power spectrum, and fluorescence intensity confirm the propagation dynamics inferred from pulse measurements and show that filamentation provides a viable route to impulsive vibrational spectroscopy at remote distances from the laser source. The technique is applied to thermometry in air and in flames, and an analytical expression is derived to describe the short-time dynamics of the rovibrational wave-packet dispersion experienced by diatomic molecules in the wave of the filament. It is found that

  19. Regularities of Filamentary Channels Formation During Formation of Nanostructured Non-Metallic Inorganic Coatings in Microplasma Galvanostatic Mode in Solutions

    NASA Astrophysics Data System (ADS)

    Mamaev, A. I.; Mamaeva, V. A.; Kolenchin, N. F.; Chubenko, A. K.; Kovalskaya, Ya. B.; Konstantinova, T. A.; Dolgova, Yu. N.; Beletskaya, E. Yu.

    2016-04-01

    This paper presents the theoretical models describing the growth of filamentary channels of nanostructured non-metallic coatings formed by anodizing and microplasma oxidation. The authors identified dependences of the number of pores on the coating thickness. The paper presents graphic dependences of the number of filamentary channels on the process time and the coating thickness. These dependences allow calculating through and surface porosity, and in cases, when the pores are filled with functional material, they allow calculating the concentration distribution of this functional material throughout the coating thickness. The theoretical models enhance our understanding of the nature of anode processes and can be used to describe and forecast the growth and filling of porous coatings, so they can also be used to create functional and bioactive materials.

  20. Electromagnetic topology: Characterization of internal electromagnetic coupling

    NASA Technical Reports Server (NTRS)

    Parmantier, J. P.; Aparicio, J. P.; Faure, F.

    1991-01-01

    The main principles are presented of a method dealing with the resolution of electromagnetic internal problems: Electromagnetic Topology. A very interesting way is to generalize the multiconductor transmission line network theory to the basic equation of the Electromagnetic Topology: the BLT equation. This generalization is illustrated by the treatment of an aperture as a four port junction. Analytical and experimental derivations of the scattering parameters are presented. These concepts are used to study the electromagnetic coupling in a scale model of an aircraft, and can be seen as a convenient means to test internal electromagnetic interference.

  1. Electromagnetic topology - Characterization of internal electromagnetic coupling

    NASA Astrophysics Data System (ADS)

    Parmantier, J. P.; Aparicio, J. P.; Faure, F.

    This paper presents the main principles of a method dealing with the resolution of electromagnetic internal problems: electromagnetic topology. A very interesting way is to generalize the multiconductor transmission line network theory to the basic equation of electromagnetic topology. This generalization is illustrated by the treatment of an aperture as a four port junction. Analytical and experimental derivations of the scattering parameters are presented. These concepts are used to study the electromagnetic coupling in a scale model of an aircraft, and can be seen as a convenient means to test internal electromagnetic interference.

  2. Electromagnetic topology: Characterization of internal electromagnetic coupling

    NASA Astrophysics Data System (ADS)

    Parmantier, J. P.; Aparicio, J. P.; Faure, F.

    1991-08-01

    The main principles are presented of a method dealing with the resolution of electromagnetic internal problems: Electromagnetic Topology. A very interesting way is to generalize the multiconductor transmission line network theory to the basic equation of the Electromagnetic Topology: the BLT equation. This generalization is illustrated by the treatment of an aperture as a four port junction. Analytical and experimental derivations of the scattering parameters are presented. These concepts are used to study the electromagnetic coupling in a scale model of an aircraft, and can be seen as a convenient means to test internal electromagnetic interference.

  3. A comparison of polypropylene-surface treatment by filamentary, homogeneous and glow discharges in helium at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Massines, F.; Gouda, G.

    1998-12-01

    Three different dielectric barrier-controlled discharge regimes in helium at atmospheric pressure under sinusoidal excitation have been obtained by varying the excitation frequency or the gas chemical composition: the filamentary discharge, which is the discharge that is usually obtained; the glow discharge, which is controlled by cathode secondary emission; and the homogeneous discharge, which is of a nature in between those of the filamentary and the glow discharges. All the characteristics that have been studied, such as the discharge current, the emission spectrum, the wettability and the chemical transformations of a polypropylene film, are related to the discharge-regime variation. The glow discharge is clearly more efficient than the others as a means of increasing the polypropylene-surface energy. Values as high as 62 mJ 0022-3727/31/24/003/img1 are obtained with this discharge whereas the maximum value after interaction with the filamentary one is 45 mJ 0022-3727/31/24/003/img1. This improvement in wettability is due to there being more O atoms implanted at the surface as well as to the addition of N atoms. The differences among in surface transformations have been correlated to the characteristics of these different discharges and more specifically to the localization of the electrical energy transfer into the gas and to the nature of the ions created during the discharge.

  4. Investigations of the structure and electromagnetic interactions of few-body systems. Progress report, 1 July 1991--30 June 1994

    SciTech Connect

    Lehman, D.R.; Haberzettl, H.; Maximon, L.C.; Parke, W.C.; Bennhold, C.; Ito, Hiroshi; Pratt, R.K.; Najmeddine, M.; Rakei, A.

    1994-07-01

    In order to make it easy for the reader to see the specific research carried out and the progress made, the following report of progress is done by topic. Each item has a format layout of Topic, Investigators, Objective, Significance, and Description of Progress, followed at the end by the relevant references. As is clear from the topics listed, the emphasis of the GW nuclear theory group has been on the structure and electromagnetic interactions of few-body nuclei. Both low- and intermediate-energy electromagnetic disintegration of these nuclei is considered, including coherent photoproduction of {pi} mesons. When the excitation energy of the target nucleus is low, the aim has been to handle the continuum part of the theoretical work numerically with no approximations, that is, by means of full three- or four-body dynamics. When structure questions are the issue, numerically accurate calculations are always carried through, limited only by the underlying two-body or three-body interactions used as input. Implicit in our work is the question of how far one can go within the traditional nuclear physics framework i.e., nucleons and mesons in a nonrelativistic setting. Our central goal is to carry through state-of-the-art few-body calculations that will serve as a means of determining at what point standard nuclear physics requires introduction of relativity and/or quark degrees of freedom in order to understand the phenomena in question. So far, the problems considered were mostly concerned with low- to medium-energy regimes where little evidence was found that requires going beyond the traditional approach.

  5. Magnetoresistivity and filamentary superconductivity in nickel-doped BaFe2As2

    NASA Astrophysics Data System (ADS)

    Wei, Zhang; Yao-Min, Dai; Bing, Xu; Run, Yang; Jin-Yun, Liu; Qiang-Tao, Sui; Hui-Qian, Luo; Rui, Zhang; Xing-Ye, Lu; Hao, Yang; Xiang-Gang, Qiu

    2016-04-01

    We present magnetotransport studies on a series of BaFe2‑x Ni x As2 (0.03 ≤ x ≤ 0.10) single crystals. In the underdoped (x = 0.03) non-superconducting sample, the temperature-dependent resistivity exhibits a peak at 22 K, which is associated with the onset of filamentary superconductivity (FLSC). FLSC is suppressed by an external magnetic field in a manner similar to the suppression of bulk superconductivity in an optimally-doped (x = 0.10) compound, suggesting the same possible origin as the bulk superconductivity. Our magnetoresistivity measurements reveal that FLSC persists up to the optimal doping and disappears in the overdoped regime where the long-range antiferromagnetic order is completely suppressed, pointing to a close relation between FLSC and the magnetic order. Project supported by the National Basic Research Program of China (Grant Nos. 2012CB821400, 2012CB921302, and 2015CB921303) and the National Natural Science Foundation of China (Grant Nos. 11274237, 91121004, 51228201, 11004238, and 11374011).

  6. Understanding the Star Formation Process in the Filamentary Dark Cloud GF 9: Near-Infrared Observations

    NASA Technical Reports Server (NTRS)

    Ciardi, David R.; Woodward, Charles E.; Clemens, Dan P.; Harker, David E.; Rudy, Richard J.

    1998-01-01

    We have performed a near-infrared JHK survey of a dense core and a diffuse filament region within the filamentary dark cloud GF 9 (LDN 1082). The core region is associated with the IRAS point source PSC 20503+6006 and is suspected of being a site of star formation. The diffuse filament region has no associated IRAS point sources and is likely quiescent. We find that neither the core nor the filament region appears to contain a Class I or Class II young stellar object. As traced by the dust extinction, the core and filament regions contain 26 and 22 solar mass, respectively, with an average H2 volume density for both regions of approximately 2500/cu cm. The core region contains a centrally condensed extinction maximum with a peak extinction of A(sub v) greater than or approximately equal to 10 mag that appears to be associated with the IRAS point source. The average H2 volume density of the extinction core is approximately 8000/cu cm. The dust within the filament, however, shows no sign of a central condensation and is consistent with a uniform-density cylindrical distribution.

  7. Imaging the Three-Dimensional Conductive Channel in Filamentary-Based Oxide Resistive Switching Memory.

    PubMed

    Celano, Umberto; Goux, Ludovic; Degraeve, Robin; Fantini, Andrea; Richard, Olivier; Bender, Hugo; Jurczak, Malgorzata; Vandervorst, Wilfried

    2015-12-01

    Filamentary-based oxide resistive memory is considered as a disruptive technology for nonvolatile data storage and reconfigurable logic. Currently accepted models explain the resistive switching in these devices through the presence/absence of a conductive filament (CF) that is described as a reversible nanosized valence-change in an oxide material. During device operation, the CF cycles billion of times at subnanosecond speed, using few tens of microamperes as operating current and thus determines the whole device's performance. Despite its importance, the CF observation is hampered by the small filament size and its minimal compositional difference with the surrounding material. Here we show an experimental solution to this problem and provide the three-dimensional (3D) characterization of the CF in a scaled device. For this purpose we have recently developed a tomography technique which combines the high spatial resolution of scanning probe microscopy with subnanometer precision in material removal, leading to a true 3D-probing metrology concept. We locate and characterize in three-dimensions the nanometric volume of the conductive filament in state-of-the-art bipolar oxide-based devices. Our measurements demonstrate that the switching occurs through the formation of a single conductive filament. The filaments exhibit sizes below 10 nm and present a constriction near the oxygen-inert electrode. Finally, different atomic-size contacts are observed as a function of the programming current, providing evidence for the filament's nature as a defects modulated quantum contact. PMID:26523952

  8. Filamentary pulse self-compression: The impact of the cell windows

    SciTech Connect

    Bree, Carsten; Demircan, Ayhan; Bethge, Jens; Nibbering, Erik T. J.; Skupin, Stefan; Berge, Luc; Steinmeyer, Guenter

    2011-04-15

    Self-compression of multi-millijoule laser pulses during filamentary propagation is usually explained by the interplay of self-focusing and defocusing effects, causing a substantial concentration of energy on the axis of the propagating optical pulse. Recently, it has been argued that cell windows may play a decisive role in the self-compression mechanism. As such windows have to be used for media other than air their presence is often unavoidable, yet they present a sudden nonadiabatic change in dispersion and nonlinearity that should lead to a destruction of the temporal and spatial integrity of the light bullets generated in the self-compression mechanism. We now experimentally prove that there is, in fact, a self-healing mechanism that helps to overcome the potentially destructive consequences of the cell windows. We show in two carefully conducted experiments that the cell window position decisively influences activation or inhibition of the self-healing mechanism. A comparison with a windowless cell shows that the presence of this mechanism is an important prerequisite for the exploitation of self-compression effects in windowed cells filled with inert gases.

  9. Investigation and optimization of intraband electromagnetically induced transparency in strained InAs quantum dot/wetting layer structures

    NASA Astrophysics Data System (ADS)

    Parvizi, R.; Rezaei, G.

    2016-01-01

    In this work, effects of the shape and size on the optical properties and optimization of the intersubband electromagnetically induced transparency in the Infra-red region of three-dimensional strained truncated pyramid-shaped InAs/GaAs quantum dot (QD) were investigated in detail. More precisely, within the density matrix approach, the probe absorption and group velocity along with the refractive index of the medium were studied with respect to their dependence on the dephasing rates and the Rabi frequencies of the probe and coupling fields for different QD heights and wetting layer (WL) thicknesses. It is found that the slow-down factors, group index, and absorption coefficient are inversely proportional to the width of the transparency window and proportional to the depth of the transparency window. The optimized transparency window can be achieved by varying the dot height and the WL thickness such that the tall dots with thin WL thickness induce significant enhancements at a fixed resonant peak position of Rabi frequency of the coupling field. The physical reasons behind these interesting phenomena were also explained based on the polarized features of intersubband transitions.

  10. Electromagnetic perturbations in new brane world scenarios

    NASA Astrophysics Data System (ADS)

    Molina, C.; Pavan, A. B.; Medina Torrejón, T. E.

    2016-06-01

    In this work, we consider electromagnetic dynamics in Randall-Sundrum branes. It is derived from a family of four-dimensional spacetimes compatible with Randall-Sundrum brane worlds, focusing on asymptotic flat backgrounds. Maximal extensions of the solutions are constructed, and their causal structures are discussed. These spacetimes include singular, nonsingular, and extreme black holes. Maxwell's electromagnetic field is introduced, and its evolution is studied in an extensive numerical survey. Electromagnetic quasinormal mode spectra are derived and analyzed with time-dependent and high-order WKB methods. Our results indicate that the black holes in the brane are electromagnetically stable.

  11. Detection of electromagnetic waves using MEMS antennas

    SciTech Connect

    Lavrik, Nickolay V; Tobin,; Bowland, Landon T

    2011-01-01

    We describe the design, fabrication and characterization of simple micromechanical structures that are capable of sensing static electric time varying electromagnetic fields. Time varying electric field sensing is usually achieved using an electromagnetic antenna and a receiver. However, these antenna-based approaches do not exhibit high sensitivity over a broad frequency (or wavelength) range. An important aspect of the present work is that, in contrast to traditional antennas, the dimensions of these micromechanical oscillators can be much smaller than the wavelength of the electromagnetic wave. We characterized the fabricated micromechanical oscillators by measuring their responses to time varying electric and electromagnetic fields.

  12. Broadband electromagnetic cloaking of long cylindrical objects.

    PubMed

    Tretyakov, Sergei; Alitalo, Pekka; Luukkonen, Olli; Simovski, Constantin

    2009-09-01

    Electromagnetic cloaks are devices that make objects undetectable for probing with electromagnetic waves. The known realizations of transformational-optics cloaks require materials with exotic electromagnetic properties and offer only limited performance in narrow frequency bands. Here, we demonstrate a wideband and low-loss cloak whose operation is not based on the use of exotic electromagnetic materials, which are inevitably dispersive and lossy. Instead, we use a simple structure made of metal layers. In this Letter, we present an experimental demonstration of cloaking for microwaves and simulation results for cloaking in the visible range. PMID:19792314

  13. Co-electrospinning fabrication and study of structural and electromagnetic interference-shielding effectiveness of TiO2/SiO2 core-shell nanofibers

    NASA Astrophysics Data System (ADS)

    Nakhaei, Omolfajr; Shahtahmassebi, Nasser; Rezaee Roknabadi, Mahmood; Behdani, Mohammad

    2016-05-01

    The present paper reports novel outcome comprising experimental results on electromagnetic interference (EMI) shielding and radar signal absorption characteristics of one-dimensional (1D) TiO2/SiO2 core-shell nanofibers. 1D TiO2/SiO2 core-shell nanofibers with various concentrations of nanoparticles (NPs) were fabricated using a single-nozzle co-electrospinning method. The core-shell structure of polyvinylpyrrolidone/polyacrylonitrile nanofibers with NPs have been electrospun from the homogeneous solution of polyvinylpyrrolidone (PVP and TiO2 NPs, as core) and polyacrylonitrile (PAN and SiO2 NPs, as shell). The morphologies and structures of TiO2/SiO2 core-shell nanofibers were characterized by XRD, FTIR, EDS, and SEM images. Microwave absorption properties of the synthesized nanofibers were studied using a vector network analyzer between 2 and 20 GHz at room temperature. The maximum EMI-shielding effectiveness of 150 dB is obtained with the dominant shielding mechanism of absorption of EM radiation. The excellent microwave absorption properties of the composites nanofibers are attributed to the special 1D fibrous structure and the effective dielectric loss.

  14. Controlled-source electromagnetic and seismic delineation of sub-seafloor fluid flow structures in a gas hydrate province, offshore Norway

    NASA Astrophysics Data System (ADS)

    Attias, Eric; Weitemeyer, Karen; Minshull, Tim A.; Best, Angus I.; Sinha, Martin; Jegen-Kulcsar, Marion; Hölz, Sebastian; Berndt, Christian

    2016-05-01

    Deep sea pockmarks underlain by chimney-like or pipe structures that contain methane hydrate are abundant along the Norwegian continental margin. In such hydrate provinces the interaction between hydrate formation and fluid flow has significance for benthic ecosystems and possibly climate change. The Nyegga region, situated on the western Norwegian continental slope, is characterized by an extensive pockmark field known to accommodate substantial methane gas hydrate deposits. The aim of this study is to detect and delineate both the gas hydrate and free gas reservoirs at one of Nyegga's pockmarks. In 2012, a marine controlled-source electromagnetic (CSEM) survey was performed at a pockmark in this region, where high-resolution three-dimensional seismic data were previously collected in 2006. Two-dimensional CSEM inversions were computed using the data acquired by ocean bottom electrical field receivers. Our results, derived from unconstrained and seismically constrained CSEM inversions, suggest the presence of two distinctive resistivity anomalies beneath the pockmark: a shallow vertical anomaly at the underlying pipe structure, likely due to gas hydrate accumulation, and a laterally extensive anomaly attributed to a free gas zone below the base of the gas hydrate stability zone. This work contributes to a robust characterization of gas hydrate deposits within sub-seafloor fluid flow pipe structures.

  15. New results on the resistivity structure of Merapi Volcano(Indonesia), derived from 3D restricted inversion of long-offsettransient electromagnetic data

    SciTech Connect

    Commer, Michael; Helwig, Stefan, L.; Hordt, Andreas; Scholl,Carsten; Tezkan, Bulent

    2006-06-14

    Three long-offset transient electromagnetic (LOTEM) surveyswerecarried out at the active volcano Merapi in Central Java (Indonesia)during the years 1998, 2000, and 2001. The measurements focused on thegeneral resistivity structure of the volcanic edifice at depths of 0.5-2km and the further investigation of a southside anomaly. The measurementswere insufficient for a full 3D inversion scheme, which could enable theimaging of finely discretized resistivity distributions. Therefore, astable, damped least-squares joint-inversion approach is used to optimize3D models with a limited number of parameters. The mode ls feature therealistic simulation of topography, a layered background structure, andadditional coarse 3D blocks representing conductivity anomalies.Twenty-eight LOTEM transients, comprising both horizontal and verticalcomponents of the magnetic induction time derivative, were analyzed. Inview of the few unknowns, we were able to achieve reasonable data fits.The inversion results indicate an upwelling conductor below the summit,suggesting hydrothermal activity in the central volcanic complex. Ashallow conductor due to a magma-filled chamber, at depths down to 1 kmbelow the summit, suggested by earlier seismic studies, is not indicatedby the inversion results. In conjunction with an anomalous-density model,derived from arecent gravity study, our inversion results provideinformation about the southern geological structure resulting from amajor sector collapse during the Middle Merapi period. The density modelallows to assess a porosity range andthus an estimated vertical salinityprofile to explain the high conductivities on a larger scale, extendingbeyond the foothills of Merapi.

  16. Electromagnetic Characterization Of Metallic Sensory Alloy

    NASA Technical Reports Server (NTRS)

    Wincheski, Russell A.; Simpson, John; Wallace, Terryl A.; Newman, John A.; Leser, Paul; Lahue, Rob

    2012-01-01

    Ferromagnetic shape-memory alloy (FSMA) particles undergo changes in both electromagnetic properties and crystallographic structure when strained. When embedded in a structural material, these attributes can provide sensory output of the strain state of the structure. In this work, a detailed characterization of the electromagnetic properties of a FSMA under development for sensory applications is performed. In addition, a new eddy current probe is used to interrogate the electromagnetic properties of individual FSMA particles embedded in the sensory alloy during controlled fatigue tests on the multifunctional material.

  17. Electromagnetic characterization of metallic sensory alloy

    NASA Astrophysics Data System (ADS)

    Wincheski, Buzz; Simpson, John; Wallace, Terryl; Newman, Andy; Leser, Paul; Lahue, Rob

    2013-01-01

    Ferromagnetic shape-memory alloy (FSMA) particles undergo changes in both electromagnetic properties and crystallographic structure when strained. When embedded in a structural material, these attributes can provide sensory output of the strain state of the structure. In this work, a detailed characterization of the electromagnetic properties of a FSMA under development for sensory applications is performed. In addition, a new eddy current probe is used to interrogate the electromagnetic properties of individual FSMA particles embedded in the sensory alloy during controlled fatigue tests on the multifunctional material.

  18. The carbon inventory in a quiescent, filamentary molecular cloud in G328

    SciTech Connect

    Burton, Michael G.; Ashley, Michael C. B.; Braiding, Catherine; Storey, John W. V.; Kulesa, Craig; Hollenbach, David J.; Wolfire, Mark; Glück, Christian; Rowell, Gavin

    2014-02-20

    We present spectral line images of [C I] 809 GHz, CO J = 1-0 115 GHz and H I 1.4 GHz line emission, and calculate the corresponding C, CO and H column densities, for a sinuous, quiescent giant molecular cloud about 5 kpc distant along the l = 328° sightline (hereafter G328) in our Galaxy. The [C I] data comes from the High Elevation Antarctic Terahertz telescope, a new facility on the summit of the Antarctic plateau where the precipitable water vapor falls to the lowest values found on the surface of the Earth. The CO and H I data sets come from the Mopra and Parkes/ATCA telescopes, respectively. We identify a filamentary molecular cloud, ∼75 × 5 pc long with mass ∼4 × 10{sup 4} M {sub ☉} and a narrow velocity emission range of just 4 km s{sup –1}. The morphology and kinematics of this filament are similar in CO, [C I], and H I, though in the latter appears as self-absorption. We calculate line fluxes and column densities for the three emitting species, which are broadly consistent with a photodissociation region model for a GMC exposed to the average interstellar radiation field. The [C/CO] abundance ratio averaged through the filament is found to be approximately unity. The G328 filament is constrained to be cold (T {sub Dust} < 20 K) by the lack of far-IR emission, to show no clear signs of star formation, and to only be mildly turbulent from the narrow line width. We suggest that it may represent a GMC shortly after formation, or perhaps still in the process of formation.

  19. Strong Magnetic Field Fluctuations within Filamentary Auroral Density Cavities Interpreted as VLF Saucer Sources

    NASA Technical Reports Server (NTRS)

    Knudsen, D. L.; Kabirzadeh, R.; Burchill, J. K.; Pfaff, Robert F.; Wallis, D. D.; Bounds, S. R.; Clemmons, J. H.; Pincon, J.-L.

    2012-01-01

    The Geoelectrodynamics and Electro-Optical Detection of Electron and SuprathermalIon Currents (GEODESIC) sounding rocket encountered more than 100 filamentary densitycavities associated with enhanced plasma waves at ELF (3 kHz) and VLF (310 kHz)frequencies and at altitudes of 800990 km during an auroral substorm. These cavities weresimilar in size (20 m diameter in most cases) to so-called lower-hybrid cavities (LHCs)observed by previous sounding rockets and satellites; however, in contrast, many of theGEODESIC cavities exhibited up to tenfold enhancements in magnetic wave powerthroughout the VLF band. GEODESIC also observed enhancements of ELF and VLFelectric fields both parallel and perpendicular to the geomagnetic field B0 within cavities,though the VLF E field increases were often not as large proportionally as seen in themagnetic fields. This behavior is opposite to that predicted by previously published theoriesof LHCs based on passive scattering of externally incident auroral hiss. We argue thatthe GEODESIC cavities are active wave generation sites capable of radiating VLF wavesinto the surrounding plasma and producing VLF saucers, with energy supplied by cold,upward flowing electron beams composing the auroral return current. This interpretation issupported by the observation that the most intense waves, both inside and outside cavities,occurred in regions where energetic electron precipitation was largely inhibited orabsent altogether. We suggest that the wave-enhanced cavities encountered by GEODESICwere qualitatively different from those observed by earlier spacecraft because of thefortuitous timing of the GEODESIC launch, which placed the payload at apogee within asubstorm-related return current during its most intense phase, lasting only a few minutes.

  20. Pondermotive versus mirror force in creation of the filamentary cavities in auroral plasma

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra

    1994-01-01

    Recently rocket observations on spikelets of lower-hybrid waves along with strong density cavities and transversely heated ions were reported. The observed thin filamentary cavities oriented along the magnetic field in the auroral plasma have density depletions up to several tens of percent. These observations have been interpreted in terms of a theory for lower-hybrid wave condensation and collapse. The modulational instability leading to the wave consensation of the lower-hybrid waves yields only weak density perturbations, which cannot explain the above strong density depletions. The wave collapse theory is based on the nonlinear pondermotive force in a homogeneous ambient plasma and the density depletion is determined by the balance between the wave pressure (pondermotive force) and the plasma pressure. In the auroral plasma, the balance is achieved in a time tau(sub wc) equal to or less than 1 ms. It is shown here that the mirror force, acting on the transversely heated ions at a relatively long time scale, is an effective mechanism for creating the strong plasma cavities. We suggest that the process of wave condensation, through the pondermotive force causing generation of short wavelength waves from relatively long wavelength waves, is a dominant process until the former waves evolve and become effective in the transverse heating of ions. As soon as this happens, mirror force on ions becomes an important factor in the creation of the density cavities, which may further trap and enhance the waves. Results from a model of cavity formation by transverse ion heating show that the observed depletions in the density cavities can be produced by the heating rates determined by the observed wave amplitudes near the lower-hybrid frequency. It is found that the creation of a strong density cavity takes a few minutes.

  1. Strong magnetic field fluctuations within filamentary auroral density cavities interpreted as VLF saucer sources

    NASA Astrophysics Data System (ADS)

    Knudsen, D. J.; Kabirzadeh, R.; Burchill, J. K.; Pfaff, R. F.; Wallis, D. D.; Bounds, S. R.; Clemmons, J. H.; Pinçon, J.-L.

    2012-02-01

    The Geoelectrodynamics and Electro-Optical Detection of Electron and Suprathermal Ion Currents (GEODESIC) sounding rocket encountered more than 100 filamentary density cavities associated with enhanced plasma waves at ELF (<3 kHz) and VLF (3-10 kHz) frequencies and at altitudes of 800-990 km during an auroral substorm. These cavities were similar in size (˜20 m diameter in most cases) to so-called lower-hybrid cavities (LHCs) observed by previous sounding rockets and satellites; however, in contrast, many of the GEODESIC cavities exhibited up to tenfold enhancements in magnetic wave power throughout the VLF band. GEODESIC also observed enhancements of ELF and VLF electric fields both parallel and perpendicular to the geomagnetic field B0 within cavities, though the VLF E field increases were often not as large proportionally as seen in the magnetic fields. This behavior is opposite to that predicted by previously published theories of LHCs based on passive scattering of externally incident auroral hiss. We argue that the GEODESIC cavities are active wave generation sites capable of radiating VLF waves into the surrounding plasma and producing VLF saucers, with energy supplied by cold, upward flowing electron beams composing the auroral return current. This interpretation is supported by the observation that the most intense waves, both inside and outside cavities, occurred in regions where energetic electron precipitation was largely inhibited or absent altogether. We suggest that the wave-enhanced cavities encountered by GEODESIC were qualitatively different from those observed by earlier spacecraft because of the fortuitous timing of the GEODESIC launch, which placed the payload at apogee within a substorm-related return current during its most intense phase, lasting only a few minutes.

  2. Microstructures and critical currents of single- and multi-filamentary MgB2 superconducting wires fabricated by an internal Mg diffusion process

    NASA Astrophysics Data System (ADS)

    Togano, K.; Hur, J.; Matsumoto, A.; Kumakura, H.

    2010-08-01

    A single-filament wire and 7- and 19-filament wires of MgB2 superconductor were fabricated by an internal Mg diffusion (IMD) process. The wire is sheathed by a Cu-Ni alloy and each filament is composed of an outermost Ta, an intermediate B + SiC powder layer and an Mg core at the center. Despite the large total area reduction, the cross sections of all wires show uniform deformation of the composite. During the subsequent heat treatment, a reacted layer with a dense composite structure composed of a MgB2 matrix and fine particles is formed by Mg liquid infiltration and the reaction with the B + SiC powder. For all wires, the highest transport Ic was obtained at furnace temperatures of 640-645 °C, which is just below the melting point of Mg. In the single-filament wire, a fairly large amount of B + SiC remains outside the reacted layer, while the residual B + SiC is much reduced in the multi-filamentary wires, resulting in higher Ic, than that of the single-filament wire. However, the Jc, estimated for the reacted layer is not so different between the wires. When the heat treatment temperature exceeds 650 °C, the Ic value rapidly decreases, although the volume fraction of the MgB2 detected continues to increase. It is observed that the thickness of the reacted layer formed at higher temperatures becomes significantly inhomogeneous, which is thought to be responsible for the deterioration of transport Ic values. The highest Jc(layer) estimated for the reacted layer is as high as 9.9 × 104 A cm - 2 at 4.2 K and 10 T and 3.3 × 105 A cm - 2 at 20 K and 1 T achieved for the multi-filamentary wires. The Jc(core) estimated for the area including the hole and remnant B is about 1/3 of the Jc(layer). From good workability of the composite and excellent Jc values, it is expected that the IMD process can compete in terms of practical wire fabrication with the conventional powder-in-tube (PIT) process.

  3. Determination of near-surface, crustal and lithospheric structures in the Canadian Precambrian Shield using time-domain electromagnetic and magnetotelluric methods

    NASA Astrophysics Data System (ADS)

    Wu, Xianghong

    Two electromagnetic methods were used to analyse the geoelectric structure of the subsurface of regions of the Precambrian Shield in Canada: the magnetotelluric (MT) and time-domain electromagnetic (TEM) methods. Magnetotelluric soundings were made at 60 sites in the southwestern Northwest Territories, Canada, along the LITHOPROBE SNORCLE Transect Corridor 1 and 1A, in the summer of 1996. The sites are located in southwestern Northwest Territories, Canada, between latitudes 60°--65°N and longitudes 110°--125°W, and cross the Archean Slave Province, the Proterozoic Buffalo Head, Great Bear Magmatic Arc, Hottah, Fort Simpson and Nahanni terranes, and the Great Slave Lake Shear Zone. Phanerozoic sedimentary rocks overlie the Proterozoic terranes. The main object of this project is to map the fracture zones and fresh/saline water interface in Precambrian granitic rocks using the surface TEM method. The TEM surveys were completed at Sites B, D, URL and A. A GEONICS PROTEM47 system with a 100 m transmitter loop was used. The data were collected for receiver offsets ranging from 0--280 m on four sides of transmitter loop. Analysis of the TEM and borehole log data indicates a basic three-layer structure: a thin conductive surface layer, a thick resistive second layer with an embedded conductive layer at some stations, and a conductive bottom layer. The results of this study show the TEM method can be used to investigate the fracture zones and groundwater salinity distribution in the Precambrian granitic rocks and contribute to site investigations for nuclear waste deposit. The TEM study in the Lac du Bonnet Batholith was successful in demonstrating the potential of the TEM methods in mapping groundwater salinity in granitic batholith. The PROTEM47 instrument, in combination with a 100 m transmitter loop, provides a suitable TEM system for mapping the resistivity structure of the Lac du Bonnet batholith down to a depth of 300--400 m. For deeper penetration and more

  4. Detection of electromagnetic radiation using nonlinear materials

    DOEpatents

    Hwang, Harold Y.; Liu, Mengkun; Averitt, Richard D.; Nelson, Keith A.; Sternbach, Aaron; Fan, Kebin

    2016-06-14

    An apparatus for detecting electromagnetic radiation within a target frequency range is provided. The apparatus includes a substrate and one or more resonator structures disposed on the substrate. The substrate can be a dielectric or semiconductor material. Each of the one or more resonator structures has at least one dimension that is less than the wavelength of target electromagnetic radiation within the target frequency range, and each of the resonator structures includes at least two conductive structures separated by a spacing. Charge carriers are induced in the substrate near the spacing when the resonator structures are exposed to the target electromagnetic radiation. A measure of the change in conductivity of the substrate due to the induced charge carriers provides an indication of the presence of the target electromagnetic radiation.

  5. Diamagnetic composite material structure for reducing undesired electromagnetic interference and eddy currents in dielectric wall accelerators and other devices

    DOEpatents

    Caporaso, George J.; Poole, Brian R.; Hawkins, Steven A.

    2015-06-30

    The devices, systems and techniques disclosed here can be used to reduce undesired effects by magnetic field induced eddy currents based on a diamagnetic composite material structure including diamagnetic composite sheets that are separated from one another to provide a high impedance composite material structure. In some implementations, each diamagnetic composite sheet includes patterned conductor layers are separated by a dielectric material and each patterned conductor layer includes voids and conductor areas. The voids in the patterned conductor layers of each diamagnetic composite sheet are arranged to be displaced in position from one patterned conductor layer to an adjacent patterned conductor layer while conductor areas of the patterned conductor layers collectively form a contiguous conductor structure in each diamagnetic composite sheet to prevent penetration by a magnetic field.

  6. Numerical evidence of undriven, fast reconnection in the solar-wind interaction with earth's magnetosphere: formation of electromagnetic coherent structures.

    PubMed

    Faganello, M; Califano, F; Pegoraro, F

    2008-09-01

    We give evidence for the first time of the onset of undriven fast, collisionless magnetic reconnection during the evolution of an initially homogeneous magnetic field advected in a sheared velocity field. We consider the interaction of the solar wind with the magnetospheric plasma at low latitude and show that reconnection takes place in the layer between adjacent vortices generated by the Kelvin-Helmholtz instability. This process generates coherent magnetic structures with a size comparable to the ion inertial scale, much smaller than the system dimensions but much larger than the electron inertial scale. These magnetic structures are further advected in the plasma in a complex pattern but remain stable over a time interval much longer than their formation time. These results can be crucial for the interpretation of satellite data showing coherent magnetic structures in the Earth's magnetosheath or the magnetotail. PMID:18851219

  7. Estimation of Prestress Force Distribution in Multi-Strand System of Prestressed Concrete Structures Using Field Data Measured by Electromagnetic Sensor.

    PubMed

    Cho, Keunhee; Cho, Jeong-Rae; Kim, Sung Tae; Park, Sung Yong; Kim, Young-Jin; Park, Young-Hwan

    2016-01-01

    The recently developed smart strand can be used to measure the prestress force in the prestressed concrete (PSC) structure from the construction stage to the in-service stage. The higher cost of the smart strand compared to the conventional strand renders it unaffordable to replace all the strands by smart strands, and results in the application of only a limited number of smart strands in the PSC structure. However, the prestress forces developed in the strands of the multi-strand system frequently adopted in PSC structures differ from each other, which means that the prestress force in the multi-strand system cannot be obtained by simple proportional scaling using the measurement of the smart strand. Therefore, this study examines the prestress force distribution in the multi-strand system to find the correlation between the prestress force measured by the smart strand and the prestress force distribution in the multi-strand system. To that goal, the prestress force distribution was measured using electromagnetic sensors for various factors of the multi-strand system adopted on site in the fabrication of actual PSC girders. The results verified the possibility to assume normal distribution for the prestress force distribution per anchor head, and a method computing the mean and standard deviation defining the normal distribution is proposed. This paper presents a meaningful finding by proposing an estimation method of the prestress force based upon field-measured data of the prestress force distribution in the multi-strand system of actual PSC structures. PMID:27548172

  8. Spatial structure of the electromagnetic field inside the ionospheric Alfvén resonator excited by atmospheric lightning activity

    NASA Astrophysics Data System (ADS)

    Plyasov, A. A.; Surkov, V. V.; Pilipenko, V. A.; Fedorov, E. N.; Ignatov, V. N.

    2012-09-01

    We have theoretically estimated ULF spectra on the ground and at ionospheric altitudes in the frequency range of the ionospheric Alfvén resonator (IAR). The IAR has been considered to be excited either by a separate lightning stroke or stochastic global thunderstorm activity. The spectra of both horizontal magnetic and electric components are shown to reveal the spectral resonant structure in the upper ionosphere. The IAR excitation for different ionospheric conditions has been compared. The IAR eigenfrequencies latitudinal inhomogeneity results in the smoothing and shift of the spectral resonance structure. The feasibility of the IAR signature detection by low-orbiting satellites with magnetic or electric sensors is discussed.

  9. Electromagnetic induction methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electromagnetic induction geophysical methods are finding greater and greater use for agricultural purposes. Electromagnetic induction methods measure the electrical conductivity (or resistivity) for a bulk volume of soil directly beneath the surface. An instrument called a ground conductivity meter...

  10. The electromagnetic spike solutions

    NASA Astrophysics Data System (ADS)

    Nungesser, Ernesto; Lim, Woei Chet

    2013-12-01

    The aim of this paper is to use the existing relation between polarized electromagnetic Gowdy spacetimes and vacuum Gowdy spacetimes to find explicit solutions for electromagnetic spikes by a procedure which has been developed by one of the authors for gravitational spikes. We present new inhomogeneous solutions which we call the EME and MEM electromagnetic spike solutions.

  11. Research Investigation Directed Toward Extending the Useful Range of the Electromagnetic Spectrum. [atomic spectra and electronic structure of alkali metals

    NASA Technical Reports Server (NTRS)

    Hartmann, S. R.; Happer, W.

    1974-01-01

    The report discusses completed and proposed research in atomic and molecular physics conducted at the Columbia Radiation Laboratory from July 1972 to June 1973. Central topics described include the atomic spectra and electronic structure of alkali metals and helium, molecular microwave spectroscopy, the resonance physics of photon echoes in some solid state systems (including Raman echoes, superradiance, and two photon absorption), and liquid helium superfluidity.

  12. Core/shell-structured nickel/nitrogen-doped onion-like carbon nanocapsules with improved electromagnetic wave absorption properties

    NASA Astrophysics Data System (ADS)

    Wu, Niandu; Liu, Xianguo; Or, Siu Wing

    2016-05-01

    Core/shell-structured nickel/nitrogen-doped onion-like carbon (Ni/(C, N)) nanocapsules are synthesized by a modified arc-discharge method using N2 gas as the source of N atoms. Core/shell-structured Ni/C nanocapsules are also prepared for comparison. The Ni/(C, N) nanocapsules with diameters of 10-80 nm exhibit a clear core/shell structure. The doping of N atoms introduces more lattice defects into the (C, N) shells and creates more disorderly C in the (C, N) shells. This leads to a slight shift in the dielectric resonance peak to the lower frequency side and an increase in the dielectric loss tangent for the Ni/(C, N) nanocapsules in comparison with the Ni/C nanocapsules. The magnetic permeability of both types of nanocapsules remains almost unaltered since the N atoms exist only in the (C, N) shells. The reflection loss (RL) of the Ni/(C, N) nanocapsules not only reaches a high value of -35 dB at 13.6 GHz, but also is generally improved in the low-frequency S and C microwave bands covering 2-8 GHz as a result of the N-doping-induced additional dipolar polarization and dielectric loss from the (C, N) shells.

  13. The BaBar electromagnetic calorimeter

    SciTech Connect

    Stahl, A.

    1997-07-01

    The progress on the design and construction of the BaBar electromagnetic calorimeter including its mechanical structure, the readout system, the mechanical and optical properties of the crystals, and the schedule for the final assembly and testing is summarized.

  14. Metamaterials beyond electromagnetism

    NASA Astrophysics Data System (ADS)

    Kadic, Muamer; Bückmann, Tiemo; Schittny, Robert; Wegener, Martin

    2013-12-01

    Metamaterials are rationally designed man-made structures composed of functional building blocks that are densely packed into an effective (crystalline) material. While metamaterials are mostly associated with negative refractive indices and invisibility cloaking in electromagnetism or optics, the deceptively simple metamaterial concept also applies to rather different areas such as thermodynamics, classical mechanics (including elastostatics, acoustics, fluid dynamics and elastodynamics), and, in principle, also to quantum mechanics. We review the basic concepts, analogies and differences to electromagnetism, and give an overview on the current state of the art regarding theory and experiment—all from the viewpoint of an experimentalist. This review includes homogeneous metamaterials as well as intentionally inhomogeneous metamaterial architectures designed by coordinate-transformation-based approaches analogous to transformation optics. Examples are laminates, transient thermal cloaks, thermal concentrators and inverters, ‘space-coiling’ metamaterials, anisotropic acoustic metamaterials, acoustic free-space and carpet cloaks, cloaks for gravitational surface waves, auxetic mechanical metamaterials, pentamode metamaterials (‘meta-liquids’), mechanical metamaterials with negative dynamic mass density, negative dynamic bulk modulus, or negative phase velocity, seismic metamaterials, cloaks for flexural waves in thin plates and three-dimensional elastostatic cloaks.

  15. Metamaterials beyond electromagnetism.

    PubMed

    Kadic, Muamer; Bückmann, Tiemo; Schittny, Robert; Wegener, Martin

    2013-12-01

    Metamaterials are rationally designed man-made structures composed of functional building blocks that are densely packed into an effective (crystalline) material. While metamaterials are mostly associated with negative refractive indices and invisibility cloaking in electromagnetism or optics, the deceptively simple metamaterial concept also applies to rather different areas such as thermodynamics, classical mechanics (including elastostatics, acoustics, fluid dynamics and elastodynamics), and, in principle, also to quantum mechanics. We review the basic concepts, analogies and differences to electromagnetism, and give an overview on the current state of the art regarding theory and experiment-all from the viewpoint of an experimentalist. This review includes homogeneous metamaterials as well as intentionally inhomogeneous metamaterial architectures designed by coordinate-transformation-based approaches analogous to transformation optics. Examples are laminates, transient thermal cloaks, thermal concentrators and inverters, 'space-coiling' metamaterials, anisotropic acoustic metamaterials, acoustic free-space and carpet cloaks, cloaks for gravitational surface waves, auxetic mechanical metamaterials, pentamode metamaterials ('meta-liquids'), mechanical metamaterials with negative dynamic mass density, negative dynamic bulk modulus, or negative phase velocity, seismic metamaterials, cloaks for flexural waves in thin plates and three-dimensional elastostatic cloaks. PMID:24190877

  16. Lanthanum and Neodymium Doped Barium Ferrite-TiO₂/MCNTs/poly(3-methyl thiophene) Composites with Nest Structures: Preparation, Characterization and Electromagnetic Microwave Absorption Properties.

    PubMed

    Zhao, Jie; Yu, Jian; Xie, Yu; Le, Zhanggao; Hong, Xiaowei; Ci, Suqin; Chen, Junhong; Qing, Xiaoyan; Xie, Weijie; Wen, Zhenhai

    2016-01-01

    We report herein the synthesis of a novel nest structured electromagnetic composite through in-situ chemical polymerization of 3-methyl thiophene (3MT) in the presence of the BaFe11.92(LaNd)0.04O19-TiO2 (BFTO) nanoparticles and MCNTs. As an absorbing material, the BFTO/MCNTs/P3MT/wax composites were prepared at various loadings of BFTO/MCNTs/P3MT (0.2:0.10:1.0 ~ 0.2:0.30:1.0), and they exhibited strong microwave absorption properties in the range of 1.0-18 GHz. When the loading of BFTO/MCNTs/P3MT is 0.2:0.30:1.0, the composite has a strongest absorbing peak at 11.04 GHz, and achieves a maximum absorbing value of -21.56 dB. The absorbing peak position moves to higher frequencies with the increase of MCNTs content. The mechanism for microwave absorption of these composites has been explained in detail. PMID:26857939

  17. Lanthanum and Neodymium Doped Barium Ferrite-TiO2/MCNTs/poly(3-methyl thiophene) Composites with Nest Structures: Preparation, Characterization and Electromagnetic Microwave Absorption Properties

    NASA Astrophysics Data System (ADS)

    Zhao, Jie; Yu, Jian; Xie, Yu; Le, Zhanggao; Hong, Xiaowei; Ci, Suqin; Chen, Junhong; Qing, Xiaoyan; Xie, Weijie; Wen, Zhenhai

    2016-02-01

    We report herein the synthesis of a novel nest structured electromagnetic composite through in-situ chemical polymerization of 3-methyl thiophene (3MT) in the presence of the BaFe11.92(LaNd)0.04O19-TiO2 (BFTO) nanoparticles and MCNTs. As an absorbing material, the BFTO/MCNTs/P3MT/wax composites were prepared at various loadings of BFTO/MCNTs/P3MT (0.2:0.10:1.0 ~ 0.2:0.30:1.0), and they exhibited strong microwave absorption properties in the range of 1.0-18 GHz. When the loading of BFTO/MCNTs/P3MT is 0.2:0.30:1.0, the composite has a strongest absorbing peak at 11.04 GHz, and achieves a maximum absorbing value of -21.56 dB. The absorbing peak position moves to higher frequencies with the increase of MCNTs content. The mechanism for microwave absorption of these composites has been explained in detail.

  18. The influence of oscillating electromagnetic fields on membrane structure and function: Synthetic liposome and natural membrane bilayer systems with direct application to the controlled delivery of chemical agents

    SciTech Connect

    Liburdy, R.P.; de Manincor, D.; Fingado, B.

    1989-09-01

    Investigations have been conducted to determine if an imposed electromagnetic field can influence membrane transport, and ion and drug permeability in both synthetic and natural cell membrane systems. Microwave fields enhance accumulation of sodium in the lymphocyte and induce protein shedding at Tc. Microwaves also trigger membrane permeability of liposome systems under specific field exposure conditions. Sensitivity varies in a defined way in bilayers displaying a membrane structural phase transition temperature, Tc; maximal release was observed at or near Tc. Significantly, liposome systems without a membrane phase transition were also found to experience permeability increases but, in contrast, this response was temperature independent. The above results indicate that field-enhanced drug release occurs in liposome vesicles that possess a Tc as well as non-Tc liposomes. Additional studies extend non-Tc liposome responses to the in vivo case in which microwaves trigger Gentamicin release from a liposome depot'' placed subcutaneously in the rat hind leg. In addition, evidence is provided that cell surface sequestered liposomes can be triggered by microwave fields to release drugs directly into target cells. 24 refs., 6 figs.

  19. Lanthanum and Neodymium Doped Barium Ferrite-TiO2/MCNTs/poly(3-methyl thiophene) Composites with Nest Structures: Preparation, Characterization and Electromagnetic Microwave Absorption Properties

    PubMed Central

    Zhao, Jie; Yu, Jian; Xie, Yu; Le, Zhanggao; Hong, Xiaowei; Ci, Suqin; Chen, Junhong; Qing, Xiaoyan; Xie, Weijie; Wen, Zhenhai

    2016-01-01

    We report herein the synthesis of a novel nest structured electromagnetic composite through in-situ chemical polymerization of 3-methyl thiophene (3MT) in the presence of the BaFe11.92(LaNd)0.04O19-TiO2 (BFTO) nanoparticles and MCNTs. As an absorbing material, the BFTO/MCNTs/P3MT/wax composites were prepared at various loadings of BFTO/MCNTs/P3MT (0.2:0.10:1.0 ~ 0.2:0.30:1.0), and they exhibited strong microwave absorption properties in the range of 1.0–18 GHz. When the loading of BFTO/MCNTs/P3MT is 0.2:0.30:1.0, the composite has a strongest absorbing peak at 11.04 GHz, and achieves a maximum absorbing value of −21.56 dB. The absorbing peak position moves to higher frequencies with the increase of MCNTs content. The mechanism for microwave absorption of these composites has been explained in detail. PMID:26857939

  20. Growth and Filling Regularities of Filamentary Channels in Non-Metallic Inorganic Coatings Under Anodic Oxidation of Valve Metals. Mathematical Modeling

    NASA Astrophysics Data System (ADS)

    Mamaev, A. I.; Mamaeva, V. A.; Kolenchin, N. F.; Chubenko, A. K.; Kovalskaya, Ya. B.; Dolgova, Yu. N.; Beletskaya, E. Yu.

    2015-12-01

    Theoretical models are developed for growth and filling processes in filamentary channels of nanostructured non-metallic coatings produced by anodizing and microplasma oxidation. Graphical concentration distributions are obtained for channel-reacting anions, cations, and sparingly soluble reaction products depending on the time of electric current transmission and the length of the filamentary channel. Graphical distributions of the front moving velocity for the sparingly soluble compound are presented. The resulting model representation increases the understanding of the anodic process nature and can be used for a description and prediction of porous anodic film growth and filling. It is shown that the character of the filamentary channel growth and filling causes a variety of processes determining the textured metal - nonmetallic inorganic coating phase boundary formation.

  1. Structural response in FeCl2 (iron chloride) to pressure-induced electro-magnetic transitions

    SciTech Connect

    Taylor, R D; Rozenberg, G Kh; Pasternak, M P; Gorodetsky, P; Xu, W M; Dubrovinsky, L S; Le Bihan, T L

    2009-01-01

    High pressure (HP) synchrotron x-ray diffraction studies were carried out in FeCl{sub 2} together with resistivity (R) studies, at various temperatures and pressures to 65 GPa using diamond anvil cells. This work follows a previous HP {sup 57}Fe Mossbauer study in which two pressure-induced (PI) electronic transitions were found interpreted as: (i) quenching of the orbital-term contribution to the hyperfine field concurring with a tilting of the magnetic moment by 55 degrees and (ii) collapse of the magnetism concurring with a sharp decrease of the isomer shift (IS). The R(P,T) studies affirm that the cause the collapse of the magnetism is a PI p-d correlation breakdown, leading to an insulator-metal transition at {approx}45 GPa and is not due to a spi-Ir,crossover (S=2 {yields} S=0). The structure response to the pressure evolution of the two electronic phase transitions starting at low pressures (LP), through an intermediate phase (IP) 30-57 GPa, and culminating in a high-pressure phase (HP), P >32 GPa, can clearly be quantified. The IP-HP phases coexist through the 32-57 GPa range in which the HP abundance increases monotonically at the expense of the IP phase. At the LP-IP interface no volume change is detected, yet the c-axis increases and the a-axis shrinks by 0.21 Angstroms and 0.13 Angstroms, respectively. The fit of the equation of state of the combined LP-IP phases yields a bulk modulus K{sub 0} = 35.3(1.8) GPa. The intralayer CI-CI distances increases, but no change is observed in Fe-CI bond-length nor are there substantial changes in the interlayer spacing. The pressure-induced electronic IP-HP transition leads to a first-order structural phase transition characterized by a decrease in Fe-CI bond length and an abrupt drop in V(P) by {approx}3.5% accompanying the correlation breakdown. In this transition no symmetry change is detected,and the XRD data could be satisfactorily fitted with the CdI{sub 2} structure. The bulk modulus of the HP phase is

  2. Hypercube-Computer Analysis Of Electromagnetic Scattering

    NASA Technical Reports Server (NTRS)

    Patterson, J. E.; Liewer, P. C.; Calalo, R. H.; Manshadi, F.

    1990-01-01

    Capabilities of hypercube and parallel processing demonstrated. Report describes use of Mark III Hypercube computer to analyze scattering of electromagnetic waves. Purpose of study to assess utility of parallel computing in such computation-intensive problems as large-scale electromagnetic scattering. Two electromagnetic codes based on different algorithms converted to run on Mark III Hypercube. First code implements finite-difference, time-domain solution of Maxwell's curl equations. Second code is Numerical Electromagnetics Code (NEC-2) which embodies frequency-domain method and developed to analyze electromagnetic responses of antennas and other metallic structures. On Mark III Hypercube with 32 active nodes, largest lattice contains about 2,048,000 unit cells.

  3. Transformation of the Spatial Structure of an Optical Echo-Hologram Response by External Non-Resonant Pulses of Electromagnetic Standing Waves

    NASA Astrophysics Data System (ADS)

    Sakhbieva, A. R.; Nefed‧ev, L. A.; Garnaeva, G. I.

    2015-11-01

    It was shown that non-resonant electromagnetic standing wave pulses between exciting laser pulses during formation of a stimulated echo hologram transformed the wave front of the stimulated echo-hologram response.

  4. Effects of Three-Dimensional Electromagnetic Structures on Resistive-Wall-Mode Stability of Reversed Field Pinches

    SciTech Connect

    Villone, F.

    2008-06-27

    In this Letter, the linear stability of the resistive wall modes (RWMs) in toroidal geometry for a reversed field pinch (RFP) plasma is studied. Three computational models are used: the cylindrical code ETAW, the toroidal MHD code MARS-F, and the CarMa code, able to take fully into account the effects of a three-dimensional conducting structure which mimics the real shell geometry of a reversed field pinch experimental device. The computed mode growth rates generally agree with experimental data. The toroidal effects and the three-dimensional features of the shell, like gaps, allow a novel interpretation of the RWM spectrum in RFP's and remove its degeneracy. This shows the importance of making accurate modeling of conductors for the RWM predictions also in future devices such as ITER.

  5. Comparison of surface modification of polypropylene film by filamentary DBD at atmospheric pressure and homogeneous DBD at medium pressure in air

    NASA Astrophysics Data System (ADS)

    Fang, Z.; Xie, X.; Li, J.; Yang, H.; Qiu, Y.; Kuffel, E.

    2009-04-01

    Non-equilibrium plasmas generated by a dielectric barrier discharge (DBD) are of great interest in material surface processing because of their convenience, effectiveness and low cost. In this paper, polypropylene (PP) films are modified using a non-equilibrium plasma generated by a DBD in air in homogeneous mode and in filamentary mode. The filamentary DBD is generated in ambient air, and the homogeneous DBD is generated at medium pressure with an operating pressure value of 3 kPa. The characteristics of homogeneous DBD are studied and compared with those of filamentary DBD by measuring their electrical discharge parameters and observing their light emission phenomena, and the surface properties of the PP films before and after the treatments are studied using contact angle and surface energy measurement, x-ray photoelectron spectroscopy and scanning electron microscopy. It is found that the homogeneous DBD is even and stable in the whole gas gap, which differs from the commonly filamentary DBD. The plasma treatments modify the PP surface in both morphology and composition. The PP films modified in both treatments show a remarkable decrease in the water contact angle and a remarkable increase in surface energy due to the introduction of oxygen-containing groups on the surface and the etching of the surface. The homogeneous DBD is more effective in PP surface modification than the filamentary DBD as it can make the contact angle decrease to a lower level by introducing more oxygen-containing groups. This effect could be explained by the evenly distributed plasma at a homogeneous DBD than at a filamentary DBD, and by the more efficient introduction of atomic oxygen to the PP surface in the case of homogeneous DBD.

  6. Identification of the formation phases of filamentary damage induced by nanosecond laser pulses in bulk fused silica

    SciTech Connect

    Shen, Chao; Xu, Zhongjie; Chambonneau, Maxime E-mail: jiangtian198611@163.com; Cheng, Xiang'ai; Jiang, Tian E-mail: jiangtian198611@163.com

    2015-09-14

    Employing a pump-probe polarization-based two-frame shadowgraphy setup, the formation of filamentary damage induced in bulk fused silica by a nanosecond pulse at 1064 nm is investigated with a picosecond probe. Three different phases are exhibited in the damage experiments. The first phase is the formation of a micrometric plasma channel along the laser direction during the beginning of the pulse likely caused by multi-photon ionization. This channel exhibits growth during ∼400 ps, and the newly grown plasma is discrete. Then, during the end of the pulse, this channel evolves into a tadpole-like morphology showing an elliptical head upstream the laser flux followed by a thin tail. This observed asymmetry is attributed to shielding effects caused by both the plasma and hot modified silica. Once the damage shows its almost final morphology, a last phase consists in the launch of a pressure wave enlarging it after the laser pulse. The physical mechanisms that might be involved in the formation of plasma channels are discussed. The experimental data are first confronted to the moving breakdown model which overestimates the filamentary damage length. Finally, taking into account the temporal shape of the laser pulses, the coupling between Kerr-induced self-focusing and stimulated Brillouin scattering is discussed to interpret the observations.

  7. Identification of the formation phases of filamentary damage induced by nanosecond laser pulses in bulk fused silica

    NASA Astrophysics Data System (ADS)

    Shen, Chao; Chambonneau, Maxime; Cheng, Xiang'ai; Xu, Zhongjie; Jiang, Tian

    2015-09-01

    Employing a pump-probe polarization-based two-frame shadowgraphy setup, the formation of filamentary damage induced in bulk fused silica by a nanosecond pulse at 1064 nm is investigated with a picosecond probe. Three different phases are exhibited in the damage experiments. The first phase is the formation of a micrometric plasma channel along the laser direction during the beginning of the pulse likely caused by multi-photon ionization. This channel exhibits growth during ˜400 ps, and the newly grown plasma is discrete. Then, during the end of the pulse, this channel evolves into a tadpole-like morphology showing an elliptical head upstream the laser flux followed by a thin tail. This observed asymmetry is attributed to shielding effects caused by both the plasma and hot modified silica. Once the damage shows its almost final morphology, a last phase consists in the launch of a pressure wave enlarging it after the laser pulse. The physical mechanisms that might be involved in the formation of plasma channels are discussed. The experimental data are first confronted to the moving breakdown model which overestimates the filamentary damage length. Finally, taking into account the temporal shape of the laser pulses, the coupling between Kerr-induced self-focusing and stimulated Brillouin scattering is discussed to interpret the observations.

  8. Electromagnetic eigenstates and the field of an oscillating point electric dipole in a flat-slab composite structure

    NASA Astrophysics Data System (ADS)

    Farhi, Asaf; Bergman, David J.

    2016-06-01

    An exact calculation of the local electric field E (r ) is described for the case of a time-dependent point electric dipole p e-i ω t in the top layer of an ɛ2, ɛ1, ɛ2 three parallel slabs composite structure, where the ɛ1 layer has a finite thickness 2 d but the ɛ2 layers are infinitely thick. For this purpose we first calculate all the eigenstates of the full Maxwell equations for the case where μ =1 everywhere in the system. The eigenvalues appear as special, nonphysical values of ɛ1 when ɛ2 is given. These eigenstates are then used to develop an exact expansion for the physical values of E (r ) in the system characterized by physical values of ɛ1(ω ) and ɛ2(ω ) . Results are compared with those of a previous calculation of the local field of a time-dependent point charge in the quasistatic regime. Numerical results are shown for the local electric field in practically important configurations where attaining an optical image with subwavelength resolution has practical significance.

  9. Electromagnetic and Mechanical Analysis of the Coil Structure for the CLAS12 Torus for 12 GeV Upgrade

    SciTech Connect

    Ghoshal, P. K.; Pastor, O.; Kashy, D.; Schneider, W.; Wiseman, M.; Zarecky, M.; Young, G.; Rode, C.; Elouadrhiri, L.; Burkert, V.

    2014-12-18

    The torus magnet for the CLAS12 spectrometer is a 3.6 T superconducting magnet being designed and built as part of the Jefferson Lab 12 GeV Upgrade. The magnet consists of six coil case assemblies mounted to a cold central hub. The coil case assembly consists of an aluminum case and cover enclosing an epoxy vacuum impregnated coil pack. The coil pack consists of a 117 turn double-pancake winding wrapped with 2 layers of 0.635 mm thick copper cooling sheets. The coil case assembly is cooled by supercritical helium at 4.6 K. This report details the structural analysis of the coil case assembly and the assessment of the coil pack stresses. For the normal operation of the torus magnet, the coil case assembly was analyzed for cool down to 4.6 K and the Lorentz forces at normal operating current. In addition to the normal operating configuration, the coil case assembly was analyzed for Lorentz forces arising from coil misalignment and current imbalances. The allowable stress criteria for the magnet followed the approach of the ASME codes. Primary stresses were limited to the lesser of 2/3 times the yield strength or 1/3 times the ultimate tensile strength. Primary plus secondary stresses were limited to 3 times the primary stress allowable. The analysis was performed using ANSYS Maxwell to calculate the magneto-static loads and ANSYS Mechanical to calculate the stresses.

  10. Electromagnetic and Mechanical Analysis of the Coil Structure for the CLAS12 Torus for 12 GeV Upgrade

    DOE PAGESBeta

    Ghoshal, P. K.; Pastor, O.; Kashy, D.; Schneider, W.; Wiseman, M.; Zarecky, M.; Young, G.; Rode, C.; Elouadrhiri, L.; Burkert, V.

    2014-12-18

    The torus magnet for the CLAS12 spectrometer is a 3.6 T superconducting magnet being designed and built as part of the Jefferson Lab 12 GeV Upgrade. The magnet consists of six coil case assemblies mounted to a cold central hub. The coil case assembly consists of an aluminum case and cover enclosing an epoxy vacuum impregnated coil pack. The coil pack consists of a 117 turn double-pancake winding wrapped with 2 layers of 0.635 mm thick copper cooling sheets. The coil case assembly is cooled by supercritical helium at 4.6 K. This report details the structural analysis of the coilmore » case assembly and the assessment of the coil pack stresses. For the normal operation of the torus magnet, the coil case assembly was analyzed for cool down to 4.6 K and the Lorentz forces at normal operating current. In addition to the normal operating configuration, the coil case assembly was analyzed for Lorentz forces arising from coil misalignment and current imbalances. The allowable stress criteria for the magnet followed the approach of the ASME codes. Primary stresses were limited to the lesser of 2/3 times the yield strength or 1/3 times the ultimate tensile strength. Primary plus secondary stresses were limited to 3 times the primary stress allowable. The analysis was performed using ANSYS Maxwell to calculate the magneto-static loads and ANSYS Mechanical to calculate the stresses.« less

  11. Pulsed electromagnetic gas acceleration

    NASA Technical Reports Server (NTRS)

    Jahn, R. G.; Vonjaskowsky, W. F.; Clark, K. E.

    1971-01-01

    Experimental data were combined with one-dimensional conservation relations to yield information on the energy deposition ratio in a parallel-plate accelerator, where the downstream flow was confined to a constant area channel. Approximately 70% of the total input power was detected in the exhaust flow, of which only about 20% appeared as directed kinetic energy, thus implying that a downstream expansion to convert chamber enthalpy into kinetic energy must be an important aspect of conventional high power MPD arcs. Spectroscopic experiments on a quasi-steady MPD argon accelerator verified the presence of A(III) and the absence of A(I), and indicated an azimuthal structure in the jet related to the mass injection locations. Measurements of pressure in the arc chamber and impact pressure in the exhaust jet using a piezocrystal backed by a Plexiglas rod were in good agreement with the electromagnetic thrust model.

  12. Electromagnetically Clean Solar Arrays

    NASA Technical Reports Server (NTRS)

    Stem, Theodore G.; Kenniston, Anthony E.

    2008-01-01

    The term 'electromagnetically clean solar array' ('EMCSA') refers to a panel that contains a planar array of solar photovoltaic cells and that, in comparison with a functionally equivalent solar-array panel of a type heretofore used on spacecraft, (1) exhibits less electromagnetic interferences to and from other nearby electrical and electronic equipment and (2) can be manufactured at lower cost. The reduction of electromagnetic interferences is effected through a combination of (1) electrically conductive, electrically grounded shielding and (2) reduction of areas of current loops (in order to reduce magnetic moments). The reduction of cost is effected by designing the array to be fabricated as a more nearly unitary structure, using fewer components and fewer process steps. Although EMCSAs were conceived primarily for use on spacecraft they are also potentially advantageous for terrestrial applications in which there are requirements to limit electromagnetic interference. In a conventional solar panel of the type meant to be supplanted by an EMCSA panel, the wiring is normally located on the back side, separated from the cells, thereby giving rise to current loops having significant areas and, consequently, significant magnetic moments. Current-loop geometries are chosen in an effort to balance opposing magnetic moments to limit far-0field magnetic interactions, but the relatively large distances separating current loops makes full cancellation of magnetic fields problematic. The panel is assembled from bare photovoltaic cells by means of multiple sensitive process steps that contribute significantly to cost, especially if electomagnetic cleanliness is desired. The steps include applying a cover glass and electrical-interconnect-cell (CIC) sub-assemble, connecting the CIC subassemblies into strings of series-connected cells, laying down and adhesively bonding the strings onto a panel structure that has been made in a separate multi-step process, and mounting the

  13. Comment on: Polar Plumes and Fine-scale Coronal Structures - On the Interpretation of Coronal Radio Sounding Data by Patzold and Bird

    NASA Technical Reports Server (NTRS)

    Woo, R.; Habbal, S. R.

    1998-01-01

    Radio occultation measurements, which probe electron density over a wide dynamic range with high sensitivity and high spatial and temporal resolution reveal a solar corona permeated by a hierarchy of filamentary structures.

  14. THE NATURE OF FILAMENTARY COLD GAS IN THE CORE OF THE VIRGO CLUSTER

    SciTech Connect

    Werner, N.; Canning, R. E. A.; Allen, S. W.; Simionescu, A.; Von der Linden, A.; Oonk, J. B. R.; Kos, J.; Van Weeren, R. J.; Nulsen, P. E. J.; Edge, A. C.; Fabian, A. C.; Reynolds, C. S.; Ruszkowski, M.

    2013-04-20

    We present a multi-wavelength study of the emission-line nebulae located {approx}38'' (3 kpc in projection) southeast of the nucleus of M87, the central dominant galaxy of the Virgo Cluster. We report the detection of far-infrared (FIR) [C II] line emission at 158 {mu}m from the nebulae using observations made with the Herschel Photodetector Array Camera and Spectrometer (PACS). The infrared line emission is extended and co-spatial with optical H{alpha}+ [N II], far-ultraviolet C IV lines, and soft X-ray emission. The filamentary nebulae evidently contain multi-phase material spanning a temperature range of at least five orders of magnitude, from {approx}100 K to {approx}10{sup 7} K. This material has most likely been uplifted by the active galactic nucleus from the center of M87. The thermal pressure of the 10{sup 4} K phase appears to be significantly lower than that of the surrounding hot intracluster medium (ICM), indicating the presence of additional turbulent and magnetic pressure in the filaments. If the turbulence in the filaments is subsonic then the magnetic field strength required to balance the pressure of the surrounding ICM is B {approx} 30-70 {mu}G. The spectral properties of the soft X-ray emission from the filaments indicate that it is due to thermal plasma with kT {approx} 0.5-1 keV, which is cooling by mixing with the cold gas and/or radiatively. Charge exchange can be ruled out as a significant source of soft X-rays. Both cooling and mixing scenarios predict gas with a range of temperatures. This is at first glance inconsistent with the apparent lack of X-ray emitting gas with kT < 0.5 keV. However, we show that the missing very soft X-ray emission could be absorbed by the cold gas in the filaments with an integrated hydrogen column density of N{sub H} {approx} 1.6 Multiplication-Sign 10{sup 21} cm{sup -2}, providing a natural explanation for the apparent temperature floor to the X-ray emission at kT {approx} 0.5 keV. The FIR through ultraviolet

  15. Objects of Maximum Electromagnetic Chirality

    NASA Astrophysics Data System (ADS)

    Fernandez-Corbaton, Ivan; Fruhnert, Martin; Rockstuhl, Carsten

    2016-07-01

    We introduce a definition of the electromagnetic chirality of an object and show that it has an upper bound. Reciprocal objects attain the upper bound if and only if they are transparent for all the fields of one polarization handedness (helicity). Additionally, electromagnetic duality symmetry, i.e., helicity preservation upon interaction, turns out to be a necessary condition for reciprocal objects to attain the upper bound. We use these results to provide requirements for the design of such extremal objects. The requirements can be formulated as constraints on the polarizability tensors for dipolar objects or on the material constitutive relations for continuous media. We also outline two applications for objects of maximum electromagnetic chirality: a twofold resonantly enhanced and background-free circular dichroism measurement setup, and angle-independent helicity filtering glasses. Finally, we use the theoretically obtained requirements to guide the design of a specific structure, which we then analyze numerically and discuss its performance with respect to maximal electromagnetic chirality.

  16. Intergalactic Medium Emission Observations with the Cosmic Web Imager. I. The Circum-QSO Medium of QSO 1549+19, and Evidence for a Filamentary Gas Inflow

    NASA Astrophysics Data System (ADS)

    Martin, D. Christopher; Chang, Daphne; Matuszewski, Matt; Morrissey, Patrick; Rahman, Shahin; Moore, Anna; Steidel, Charles C.

    2014-05-01

    The Palomar Cosmic Web Imager (PCWI), an integral field spectrograph designed to detect and map low surface brightness emission, has obtained imaging spectroscopic maps of Lyα from the circum-QSO medium (CQM) of QSO HS1549+19 at redshift z = 2.843. Extensive extended emission is detected from the CQM, consistent with fluorescent and pumped Lyα produced by the ionizing and Lyα continuum of the QSO. Many features present in PCWI spectral images match those detected in narrow-band images. Filamentary structures with narrow line profiles are detected in several cases as long as 250-400 kpc. One of these is centered at a velocity redshifted with respect to the systemic velocity, and displays a spatially collimated and kinematically cold line profile increasing in velocity width approaching the QSO. This suggests that the filament gas is infalling onto the QSO, perhaps in a cold accretion flow. Because of the strong ionizing flux, the neutral column density is low, typically N(H\\,\\scriptsize{I}) \\sim 10^{12}{--} 10^{15}\\, cm^{ - 2}, and the line center optical depth is also low (typically τ0 < 10), insufficient to display well separated double peak emission characteristic of higher line optical depths. With a simple ionization and cloud model we can very roughly estimate the total gas mass (log M gas = 12.5 ± 0.5) and the total (log M tot = 13.3 ± 0.5). We can also calculate a kinematic mass from the total line profile (2 × 1013 M ⊙), which agrees with the mass estimated from the gas emission. The intensity-binned spectrum of the CQM shows a progression in kinematic properties consistent with heirarchical structure formation.

  17. Intergalactic medium emission observations with the cosmic web imager. I. The circum-QSO medium of QSO 1549+19, and evidence for a filamentary gas inflow

    SciTech Connect

    Martin, D. Christopher; Chang, Daphne; Matuszewski, Matt; Morrissey, Patrick; Rahman, Shahin; Moore, Anna; Steidel, Charles C.

    2014-05-10

    The Palomar Cosmic Web Imager (PCWI), an integral field spectrograph designed to detect and map low surface brightness emission, has obtained imaging spectroscopic maps of Lyα from the circum-QSO medium (CQM) of QSO HS1549+19 at redshift z = 2.843. Extensive extended emission is detected from the CQM, consistent with fluorescent and pumped Lyα produced by the ionizing and Lyα continuum of the QSO. Many features present in PCWI spectral images match those detected in narrow-band images. Filamentary structures with narrow line profiles are detected in several cases as long as 250-400 kpc. One of these is centered at a velocity redshifted with respect to the systemic velocity, and displays a spatially collimated and kinematically cold line profile increasing in velocity width approaching the QSO. This suggests that the filament gas is infalling onto the QSO, perhaps in a cold accretion flow. Because of the strong ionizing flux, the neutral column density is low, typically N(H I)∼10{sup 12}--10{sup 15} cm{sup −2}, and the line center optical depth is also low (typically τ{sub 0} < 10), insufficient to display well separated double peak emission characteristic of higher line optical depths. With a simple ionization and cloud model we can very roughly estimate the total gas mass (log M {sub gas} = 12.5 ± 0.5) and the total (log M {sub tot} = 13.3 ± 0.5). We can also calculate a kinematic mass from the total line profile (2 × 10{sup 13} M {sub ☉}), which agrees with the mass estimated from the gas emission. The intensity-binned spectrum of the CQM shows a progression in kinematic properties consistent with heirarchical structure formation.

  18. Nucleon Electromagnetic Form Factors

    SciTech Connect

    Kees de Jager

    2004-08-01

    Although nucleons account for nearly all the visible mass in the universe, they have a complicated structure that is still incompletely understood. The first indication that nucleons have an internal structure, was the measurement of the proton magnetic moment by Frisch and Stern (1933) which revealed a large deviation from the value expected for a point-like Dirac particle. The investigation of the spatial structure of the nucleon, resulting in the first quantitative measurement of the proton charge radius, was initiated by the HEPL (Stanford) experiments in the 1950s, for which Hofstadter was awarded the 1961 Nobel prize. The first indication of a non-zero neutron charge distribution was obtained by scattering thermal neutrons off atomic electrons. The recent revival of its experimental study through the operational implementation of novel instrumentation has instigated a strong theoretical interest. Nucleon electro-magnetic form factors (EMFFs) are optimally studied through the exchange of a virtual photon, in elastic electron-nucleon scattering. The momentum transferred to the nucleon by the virtual photon can be selected to probe different scales of the nucleon, from integral properties such as the charge radius to scaling properties of its internal constituents. Polarization instrumentation, polarized beams and targets, and the measurement of the polarization of the recoiling nucleon have been essential in the accurate separation of the charge and magnetic form factors and in studies of the elusive neutron charge form factor.

  19. Electromagnetic Structure of the Deuteron

    SciTech Connect

    Franz Gross

    2002-06-01

    Recent high energy measurements of elastic ed scattering support the use of a relativistic theory based on an accurate description of the NN channel, but theory needed for an understanding of the high energy deuteron photodisintegration cross sections and polarized observables is not yet mature.

  20. Deep electromagnetic investigation to study the geological and structural setting of the epicentral area of the April 6, 2009 Abruzzo earthquake

    NASA Astrophysics Data System (ADS)

    Balasco, Marianna; Giocoli, Alessandro; Gueguen, Erwan; Lapenna, Vincenzo; Perrone, Angela; Piscitelli, Sabatino; Rizzo, Enzo; Romano, Gerardo; Siniscalchi, Agata; Votta, Mario

    2010-05-01

    Deep electromagnetic investigation, using magnetotelluric (MT) and Deep Electrical Resistivity Tomography (DERT) methods, has been carried out across the Aterno Valley, in the epicentral area of April 6, 2009 (Mw=6.3) Abruzzo earthquake, with the aim to study the geological and structural setting of the subsurface. The L'Aquila Basin is a 60 Km long intermountain depression of the Central Apennines, with a NW-SE-trending, bounded to SW by Monti Sirente-Monte Ocre and by Gran Sasso to NE. This depression is filled in Quaternary continental sediments of the Aterno River while the bedrock is composed by Mesocenozoic calcareous of platform. In the middle part of the basin, from Bagno (SW) to Paganica village (NE), along a profile about 9 km long were carried out 10 MT soundings with site separations of about of 1 km. The acquisition of MT data were obtained with MT24-LF systems (Schlumberger/EMI). The frequency of data recording was set to 6.25 Hz for at least 24 hours and during night-time we launched high frequency sampling acquisition events (500 Hz) for at least 2 hour. Time series data were analyzed using the processing based on Egbert's robust code (Egbert, 1997) to compute estimates of the MT transfer function in the period range 0.00931-238.313 s. Applying an inversion 2D model we have obtained the distribution resistivity of subsoil, as function of depth. The apparent resistivity and phase for TE and TM mode (in all investigated period range) were inverted by using an algorithm developed by Rodi & Mackie, 2001. Almost coincident with MT profile, a DERT with "dipole-dipole" array configuration has been carried out along a profile of 8Km, using 21 stations with an electrode spacing of 400 m and a maximum distance between current and potential probes 7-8 times the basic spacing. In this way, the electrode array geometry allows us to obtain a an exploration depth of about 900 m. The acquisition system consists of a transmitting stations which injects the current

  1. Structural and dynamic electromagnetic properties of Ni0.27 Cu0.10 Zn0.63 Alx Fe2-x O4

    NASA Astrophysics Data System (ADS)

    Hossen, M. Belal; Hossain, A. K. M. Akther

    2015-08-01

    The influence of Al substitution on the structural and electromagnetic properties of Ni0.27Cu0.10Zn0.63AlxFe2 - xO4; (where x = 0.0 to x = 0.16 with step = 0.02) prepared by the combustion technique, has been investigated. X-ray diffraction analysis confirms the presence of single phase cubic spinel structure without any secondary phase. The lattice constant, theoretical density, bulk density and average grain size decreases with increasing Al content. B-H loops have been traced for all the compositions and the various hysteresis parameters like saturation induction, coercivity, remanance, remanance ratio and power loss have been studied as a function of Al content. The saturation induction and the initial permeability increases with sintering temperature up to 1150 °C where the maximum bulk density is obtained, while for higher sintering temperature they decrease. The variation of complex initial permeability for Al substituted NiCuZn ferrites can be presented as a form of semicircle so called the Cole-Cole plot and the relaxation phenomena were explained with various shapes of the plots. The analysis of complex impedance spectra by an equivalent circuit model were used to separate the grain and grain boundary resistance of various Ni0.27 Cu0.10 Zn0.63 Alx Fe2 - x O4 . The impedance plot showed the first semicircle at high frequency which corresponds to grain effect and the second semicircle at lower frequency which corresponds to grain boundary (conduction phenomenon). Both grain and grain boundary resistance increases with increasing Al content and the relative increase of grain resistance is larger than the grain boundary resistance. The frequency dependent conductivity results support the double (Jonscher's modified) power law,σT (ω) = σ (o) +A1 ω n1 +A2 ω n2 , and the results showed evidence of three types of conduction process at room temperature: (i) low frequency conductivity is due to long-range ordering (frequency independent or its tendency

  2. Electromagnetic shielding effectiveness of composite material

    NASA Astrophysics Data System (ADS)

    Serna, Patrick J.; Liechty, Gary H.

    1999-01-01

    The purpose of this paper is to present an engineering study of the electromagnetic shielding effectiveness of composite materials used in space applications. The objective of the study is to identify and quantify the important electrical characteristics of composite materials proposed as substitutes for conventional metal-based structural elements of spacecraft. Current design practices utilized by various developers of spacecraft, particularly those with survivability and endurability requirements, employ variations of design constraints which rely on quantifiable and testable control of electromagnetic topology. These design practices are based on extensive knowledge and experience gained through analyses and tests of configurations on metallic structures and metal-enclosed electronics boxes. The purpose of this study is to determine, analytically and experimentally, the relevant electromagnetic characteristics of selected classes of composite material being recommended for inclusion in designs of new spacecraft systems. This study surveyed existing electromagnetic databases to determine known electrical characteristics of various advanced composite materials proposed as substitutes for spacecraft metal-based structures and enclosure materials. Particular attention was focused on determining the utility of this data in quantifying the electromagnetic shielding effectiveness through nominal bulk properties such as resistivity/conductivity and electrical connectivity through bonds/joints. For a select set of composite material, an experimental approach to evaluate the important electromagnetic characteristics of sample configurations was used. Primary material focus of this study is on carbon/epoxy, graphite/epoxy, and carbon/cyanate ester materials.

  3. CAFM investigations of filamentary conduction in Cu2O ReRAM devices fabricated using stencil lithography technique.

    PubMed

    Singh, Bharti; Mehta, B R; Varandani, Deepak; Savu, Andreea Veronica; Brugger, Juergen

    2012-12-14

    With the objective of understanding the role of size and current level of filamentary regions on the resistive switching parameters, detailed conductive atomic force microscope investigations of resistive memory cells having different dimensions have been carried out in this study. Cu-Cu(2)O-Ti memory cells having dimensions of 150, 50 and 25 μm have been fabricated on the same substrate using a stencil lithography technique. The dependence of resistive switching parameters on the device dimensions can be directly related to the average size, current level of the filaments and difference in these parameters between the low resistance state (LRS) and high resistance state (HRS). It is observed that the large increase in the ratio of current in the two states in cells having lower dimensions is mainly due to the smaller number of conducting regions in the HRS, indicating efficient switching from the LRS to the HRS at lower dimensions. PMID:23149566

  4. Tunability enhanced electromagnetic wiggler

    DOEpatents

    Schlueter, R.D.; Deis, G.A.

    1992-03-24

    The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles. 14 figs.

  5. Tunability enhanced electromagnetic wiggler

    DOEpatents

    Schlueter, Ross D.; Deis, Gary A.

    1992-01-01

    The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles.

  6. Electromagnetic mass revisited

    NASA Astrophysics Data System (ADS)

    Schwinger, Julian

    1983-03-01

    Examples of uniformly moving charge distributions that possess conserved electromagnetic stress tensors are exhibited. These constitute stable systems with covariantly characterized electromagnetic mass. This note, on a topic to which Paul Dirac made a significant contribution in 1938, is dedicated to him for his 80th birthday.

  7. Electromagnetically Operated Counter

    DOEpatents

    Goldberg, H D; Goldberg, M I

    1951-12-18

    An electromagnetically operated counter wherein signals to be counted are applied to cause stepwise rotation of a rotatable element which is connected to a suitable register. The mechanism involved consists of a rotatable armature having three spaced cores of magnetic material and a pair of diametrically opposed electromagnets with a suitable pulsing circuit to actuate the magnets.

  8. Introducing Electromagnetic Field Momentum

    ERIC Educational Resources Information Center

    Hu, Ben Yu-Kuang

    2012-01-01

    I describe an elementary way of introducing electromagnetic field momentum. By considering a system of a long solenoid and line charge, the dependence of the field momentum on the electric and magnetic fields can be deduced. I obtain the electromagnetic angular momentum for a point charge and magnetic monopole pair partially through dimensional…

  9. Mapping hydrogeophysical structures with time--domain electromagnetic methods: Resolving small-scale details with large loops and three--component measurements

    NASA Astrophysics Data System (ADS)

    Weiss, C. J.; Li, Y.; Nabighian, M.

    2004-12-01

    One of the outstanding problems in managing water resources in geologically complex aquifers is to develop improved techniques for mapping compartmentalization due to faulting. And although the role of faults in aquifer dynamics can vary considerably, knowledge of their location is key to understanding aquifer recharge and developing a sensible model for predicting aquifer response due to anthropogenic loads. We have explored the application of time--domain electromagnetic methods for mapping shallow aquifer faults on the western flanks of the Estancia Basin, central New Mexico. The field site is underlain by massive Pennsylvanian limestones (Madera Group) subsequently faulted by Laramide tectonics of the Ancestral Rockies and Neogene extension of the Rio Grande Rift. Two experimental configurations were deployed: a large 50 × 40 m transmitter loop with receiver stations located on a 5 m grid over the loop's interior; and an azimuthal survey consisting of a smaller fixed transmitter with receiver stations at ˜2 m intervals along a 30 m radius circle centered on the transmitter. Three--component transients of magnetic field due to a fast linear ramp--off in the transmitter were recorded at each station. As a rapid reconnaisance tool, the azimuthal experiment is well--suited for identification of subsurface fault planes since symmetry constraints require a vanishing azimuthal ̂ φ component of magnetic field when the electrical strike, or fault plane, lies in the ̂ φ direction. However, each of the experimental configurations revealed that the site's electrical structure is far more three--dimensional than previously believed and is not dominated by the response of a previously identified fault plane. Instead, we have observed spatially coherent transient signals which may indicate compartmentalization over length scales as small as a few tens of meters. Sections of this work were performed at Sandia National Laboratories. Sandia is a multi--program laboratory

  10. Low Frequency Electromagnetic Background Radiation From Electron Acceleration Above Thunderclouds

    NASA Astrophysics Data System (ADS)

    Fullekrug, Martin; Mezentsev, Andrew; Soula, Serge; van der Velde, Oscar; Farges, Thomas

    2013-04-01

    It was recently proposed that the acceleration of electrons during the growth and branching of streamers above thunderclouds initiated by intense lightning discharges could result in detectable low frequency electromagnetic radiation from several tens of kHz up to several hundreds of kHz (Qin et al., GRL, 2012). The intensity of the predicted radiation scales with the streamer density which is particularly large during spectacular sprite occurrences such as jellyfish sprites and/or dancing sprites. Dancing sprites are up to one second long sequences of consecutive sprites or sprite groups which are typically separated by some hundreds of milliseconds and which tend to follow the spatial development of large scale intracloud lightning discharges. A particularly spectacular series of 10 dancing sprite events over a Mediterranean mesoscale convective system was recorded with a low light video camera in south-eastern France during the early morning hours of August 31, 2012. Each dancing sprite event was composed of ~3-4 consecutive sprites or groups of sprites. All of these sprite occurrences were associated with a sudden enhancement ~2 uV/m/Hz-1/2 of the low frequency electromagnetic background radiation as measured with a radio receiver in south-west England. It is estimated that ~1000 streamers at a height of ~40 km are necessary to epxlain the observed electric field strengths. These sudden enhancements are superimposed on a more continuous low frequency electromagnetic background radiation which accompanies each dancing sprite event. It is speculated that this low frequency 'radio glow' results from filamentary streamers near the cloud top as a result of the large scale electrostatic charging of the thundercloud and that it may be used as an indicator for sprite occurrences in future studies.

  11. High frequency electromagnetic tomography

    SciTech Connect

    Daily, W.; Ramirez, A.; Ueng, T.; Latorre, R.

    1989-09-01

    An experiment was conducted in G Tunnel at the Nevada Test Site to evaluate high frequency electromagnetic tomography as a candidate for in situ monitoring of hydrology in the near field of a heater placed in densely welded tuff. Tomographs of 200 MHz electromagnetic permittivity were made for several planes between boreholes. Data were taken before the heater was turned on, during heating and during cooldown of the rockmass. This data is interpreted to yield maps of changes in water content of the rockmass as a function of time. This interpretation is based on laboratory measurement of electromagnetic permittivity as a function of water content for densely welded tuff. 8 refs., 6 figs.

  12. Electromagnetic spatial coherence wavelets.

    PubMed

    Castaneda, Roman; Garcia-Sucerquia, Jorge

    2006-01-01

    The recently introduced concept of spatial coherence wavelets is generalized to describe the propagation of electromagnetic fields in the free space. For this aim, the spatial coherence wavelet tensor is introduced as an elementary amount, in terms of which the formerly known quantities for this domain can be expressed. It allows for the analysis of the relationship between the spatial coherence properties and the polarization state of the electromagnetic wave. This approach is completely consistent with the recently introduced unified theory of coherence and polarization for random electromagnetic beams, but it provides further insight about the causal relationship between the polarization states at different planes along the propagation path. PMID:16478063

  13. Pulsed electromagnetic gas acceleration

    NASA Technical Reports Server (NTRS)

    Jahn, R. G.; Vonjaskowsky, W. F.; Clark, K. E.

    1974-01-01

    Detailed measurements of the axial velocity profile and electromagnetic structure of a high power, quasi-steady MPD discharge are used to formulate a gasdynamic model of the acceleration process. Conceptually dividing the accelerated plasma into an inner flow and an outer flow, it is found that more than two-thirds of the total power in the plasma is deposited in the inner flow, accelerating it to an exhaust velocity of 12.5 km/sec. The outer flow, which is accelerated to a velocity of only 6.2 km/sec, appears to provide a current conduction path between the inner flow and the anode. Related cathode studies have shown that the critical current for the onset of terminal voltage fluctuations, which was recently shown to be a function of the cathode area, appears to reach an asymptote for cathodes of very large surface area. Detailed floating potential measurements show that the fluctuations are confined to the vicinity of the cathode and hence reflect a cathode emission process rather than a fundamental limit on MPD performance.

  14. Electromagnetism in the Movies.

    ERIC Educational Resources Information Center

    Everitt, Lori R.; Patterson, Evelyn T.

    1999-01-01

    Describes how the authors used portions of popular movies to help students review concepts related to electromagnetism. Movies used and concepts covered in the review are listed, and a sample activity is described. (WRM)

  15. An opening electromagnetic transducer

    NASA Astrophysics Data System (ADS)

    Sun, Yanhua; Kang, Yihua

    2013-12-01

    Tubular solenoids have been widely used without any change since an electrical wire was discovered to create magnetic fields by Hans Christian Oersted in 1820 and thereby the wire was first coiled as a helix into a solenoid coil by William Sturgeon in 1823 and was improved by Joseph Henry in 1829 [see http://www.myetymology.com/encyclopedia/History_of_the_electricity.html; J. M. D. Coey, Magnetism and Magnetic Materials (Cambridge University Press, New York, 2010); and F. Winterberg, Plasma Phys. 8, 541553 (1996)]. A magnetic control method of C-shaped carrying-current wire is proposed, and thereby a new opening electromagnetic transducer evidently differing from the traditional tubular solenoid is created, capable of directly encircling and centering the acted objects in it, bringing about convenient and innovative electromagnetic energy conversion for electromagnetic heating, electromagnetic excitation, physical information capture, and electro-mechanical motion used in science research, industry, and even biomedical activities.

  16. Electromagnetic rotational actuation.

    SciTech Connect

    Hogan, Alexander Lee

    2010-08-01

    There are many applications that need a meso-scale rotational actuator. These applications have been left by the wayside because of the lack of actuation at this scale. Sandia National Laboratories has many unique fabrication technologies that could be used to create an electromagnetic actuator at this scale. There are also many designs to be explored. In this internship exploration of the designs and fabrications technologies to find an inexpensive design that can be used for prototyping the electromagnetic rotational actuator.

  17. Performance analysis of superconducting generator electromagnetic shielding

    NASA Astrophysics Data System (ADS)

    Xia, D.; Xia, Z.

    2015-12-01

    In this paper, the shielding performance of electromagnetic shielding systems is analyzed using the finite element method. Considering the non-iron-core rotor structure of superconducting generators, it is proposed that the stator alternating magnetic field generated under different operating conditions could decompose into oscillating and rotating magnetic field, so that complex issues could be greatly simplified. A 1200KW superconducting generator was analyzed. The distribution of the oscillating magnetic field and the rotating magnetic field in rotor area, which are generated by stator winding currents, and the distribution of the eddy currents in electromagnetic shielding tube, which are induced by these stator winding magnetic fields, are calculated without electromagnetic shielding system and with three different structures of electromagnetic shielding system respectively. On the basis of the results of FEM, the shielding factor of the electromagnetic shielding systems is calculated and the shielding effect of the three different structures on the oscillating magnetic field and the rotating magnetic field is compared. The method and the results in this paper can provide reference for optimal design and loss calculation of superconducting generators.

  18. Device and method for redirecting electromagnetic signals

    DOEpatents

    Garcia, Ernest J.

    1999-01-01

    A device fabricated to redirect electromagnetic signals, the device including a primary driver adapted to provide a predetermined force, a linkage system coupled to the primary driver, a pusher rod rotationally coupled to the linkage system, a flexible rod element attached to the pusher rod and adapted to buckle upon the application of the predetermined force, and a mirror structure attached to the flexible rod element at one end and to the substrate at another end. When the predetermined force buckles the flexible rod element, the mirror structure and the flexible rod element both move to thereby allow a remotely-located electromagnetic signal directed towards the device to be redirected.

  19. Efficient transformer for electromagnetic waves

    DOEpatents

    Miller, R.B.

    A transformer structure for efficient transfer of electromagnetic energy from a transmission line to an unmatched load provides voltage multiplication and current division by a predetermined constant. Impedance levels are transformed by the square of that constant. The structure includes a wave splitter, connected to an input transmission device and to a plurality of output transmission devices. The output transmission devices are effectively connected in parallel to the input transmission device. The output transmission devices are effectively series connected to provide energy to a load. The transformer structure is particularly effective in increasing efficiency of energy transfer through an inverting convolute structure by capturing and transferring energy losses from the inverter to the load.

  20. Diffuse barrier discharges in nitrogen with small admixtures of oxygen: discharge mechanism and transition to the filamentary regime

    NASA Astrophysics Data System (ADS)

    Brandenburg, R.; Maiorov, V. A.; Golubovskii, Yu B.; Wagner, H.-E.; Behnke, J.; Behnke, J. F.

    2005-07-01

    Diffuse barrier discharges (BDs) are characterized by the periodicity of their discharge current and by the uniform coverage of the entire electrode surface by the plasma. Up to now the discharge development, their appearance and dynamics cannot be adequately explained by elementary processes. Different processes are discussed in the literature controversially, in particular the importance of volume and surface processes on the pre-ionization (Penning-ionization, secondary (γ-) processes, role of surface charges). Diffuse BDs in nitrogen with small admixtures of oxygen are investigated by plasma diagnostics (current/voltage-oscillography, optical emission spectroscopy) and numerical modelling. Special attention is paid to the transition to the usual filamentary mode, characterized by the presence of micro-discharges and caused by the admixture of oxygen in the range of 0-1200 ppm (parts-per-million). This transition starts at low values of O2 (about 450 ppm) and is introduced by an oscillative multi-peak mode. At higher admixtures (about 1000 ppm) the micro-discharges are generated. According to the results of numerical modelling, secondary electron emission by N2(A 3Σu) metastable states plays a major role in discharge maintenance. Due to the much more effective quenching of these states by O2 and NO than by N2 the subsequent delivery of electrons will be decreased when the oxygen amount is increased.

  1. Behaviour of filamentary MgB2 wires subjected to tensile stress at 4.2 K

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Kopera, L.; Melišek, T.; Rindfleisch, M.; Haessler, W.; Hušek, I.

    2013-10-01

    Different filamentary MgB2 wires have been subjected to tensile stress at 4.2 K. Stress-strain and critical current versus stress and strain characteristics of wires differing by filament architecture, sheath materials, deformation and heat treatment were measured and compared. It was found that the linear increase of critical current due to the pre-compression effect (ranging from 5% up to ≈20%) is affected by thermal expansion and the strength of used metallic sheaths. The values of irreversible strain ɛirr and stress σirr depend dominantly on the applied outer sheath and its final heat treatment conditions. Consequently, the strain-tolerance of MgB2 wires is influenced by several parameters and it is difficult to see a clear relation between Ic(ɛ) and σ(ɛ) characteristics. The lowest ɛirr was measured for Monel sheathed wires (0.3-0.6%), medium for GlidCop® sheath (0.48-0.6%), and the highest ɛirr = 0.6-0.9% were obtained for MgB2 wires reinforced by the stainless steel 316L annealed at temperature between 600 and 800 ° C. The highest ɛirr = 0.9% and σirr = 900 MPa were measured for the work-hardened steel, which is not considerably softened by the heat treatment at 600 ° C/2.5 h.

  2. Evidence of Filamentary Switching in Oxide-based Memory Devices via Weak Programming and Retention Failure Analysis

    NASA Astrophysics Data System (ADS)

    Younis, Adnan; Chu, Dewei; Li, Sean

    2015-09-01

    Further progress in high-performance microelectronic devices relies on the development of novel materials and device architectures. However, the components and designs that are currently in use have reached their physical limits. Intensive research efforts, ranging from device fabrication to performance evaluation, are required to surmount these limitations. In this paper, we demonstrate that the superior bipolar resistive switching characteristics of a CeO2:Gd-based memory device can be manipulated by means of UV radiation, serving as a new degree of freedom. Furthermore, the metal oxide-based (CeO2:Gd) memory device was found to possess electrical and neuromorphic multifunctionalities. To investigate the underlying switching mechanism of the device, its plasticity behaviour was studied by imposing weak programming conditions. In addition, a short-term to long-term memory transition analogous to the forgetting process in the human brain, which is regarded as a key biological synaptic function for information processing and data storage, was realized. Based on a careful examination of the device’s retention behaviour at elevated temperatures, the filamentary nature of switching in such devices can be understood from a new perspective.

  3. Properties of filamentary sublimation residues from dispersions of clay in ice. [on Martian poles, comet nuclei, and icy satellites

    NASA Technical Reports Server (NTRS)

    Saunders, R. S.; Parker, T. J.; Stephens, J. B.; Fanale, F. P.; Sutton, S.

    1986-01-01

    Results are reported from experimental studies of the formation of ice mixed with mineral particles in an effort to simulate similar processes on natural surfaces such as at the Martian poles, on comet nuclei and on icy satellites. The study consisted of low-pressure, low-temperature sublimations of water ice from dilutions of water-clay (montmorillonite and Cabosil) dispersions of various component ratios. Liquid dispersions were sprayed into liquid nitrogen to form droplets at about -50 C. Both clay-water dispersions left a filamentary residue on the bottom of the Dewar after the water ice had sublimated off. The residue was studied with optical and SEM microscopy, the latter method revealing a high electrical conductivity in the residue. The results suggest that the sublimation of the water ice can leave a surface crust, which may be analogous to processes at the Martian poles and on comet nuclei. The process could proceed by the attachment of water molecules to salt crystals during the hottest part of the Martian year. The residue remaining was found to remain stable up to 370 C, be porous, and remain resilient, which could allow it to insulate ice bodies such as comets in space.

  4. MMS observations of electron-scale filamentary currents in the reconnection exhaust and near the X line

    NASA Astrophysics Data System (ADS)

    Phan, T. D.; Eastwood, J. P.; Cassak, P. A.; Øieroset, M.; Gosling, J. T.; Gershman, D. J.; Mozer, F. S.; Shay, M. A.; Fujimoto, M.; Daughton, W.; Drake, J. F.; Burch, J. L.; Torbert, R. B.; Ergun, R. E.; Chen, L. J.; Wang, S.; Pollock, C.; Dorelli, J. C.; Lavraud, B.; Giles, B. L.; Moore, T. E.; Saito, Y.; Avanov, L. A.; Paterson, W.; Strangeway, R. J.; Russell, C. T.; Khotyaintsev, Y.; Lindqvist, P. A.; Oka, M.; Wilder, F. D.

    2016-06-01

    We report Magnetospheric Multiscale observations of macroscopic and electron-scale current layers in asymmetric reconnection. By intercomparing plasma, magnetic, and electric field data at multiple crossings of a reconnecting magnetopause on 22 October 2015, when the average interspacecraft separation was ~10 km, we demonstrate that the ion and electron moments are sufficiently accurate to provide reliable current density measurements at 30 ms cadence. These measurements, which resolve current layers narrower than the interspacecraft separation, reveal electron-scale filamentary Hall currents and electron vorticity within the reconnection exhaust far downstream of the X line and even in the magnetosheath. Slightly downstream of the X line, intense (up to 3 μA/m2) electron currents, a super-Alfvénic outflowing electron jet, and nongyrotropic crescent shape electron distributions were observed deep inside the ion-scale magnetopause current sheet and embedded in the ion diffusion region. These characteristics are similar to those attributed to the electron dissipation/diffusion region around the X line.

  5. Time-resolved characterization of a filamentary argon discharge at atmospheric pressure in a capillary using emission and absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Schröter, Sandra; Pothiraja, Ramasamy; Awakowicz, Peter; Bibinov, Nikita; Böke, Marc; Niermann, Benedikt; Winter, Jörg

    2013-11-01

    An argon/nitrogen (0.999/0.001) filamentary pulsed discharge operated at atmospheric pressure in a quartz tube is characterized using voltage-current measurements, microphotography, optical emission spectroscopy (OES) and absorption spectroscopy. Nitrogen is applied as a sensor gas for the purpose of OES diagnostic. The density of argon metastable atoms Ar(3P2) is determined using tunable diode laser absorption spectroscopy (TDLAS). Using a plasma chemical model the measured OES data are applied for the characterization of the plasma conditions. Between intense positive pulses the discharge current oscillates with a damped amplitude. It is established that an electric current flows in this discharge not only through a thin plasma filament that is observed in the discharge image but also through the whole cross section of the quartz tube. A diffuse plasma fills the quartz tube during a time between intense current pulses. Ionization waves are propagating in this plasma between the spike and the grounded area of the tube producing thin plasma channels. The diameter of these channels increases during the pause between the propagation of ionization waves probably because of thermal expansion and diffusion. Inside the channels electron densities of ˜2 × 1013 cm-3, argon metastable densities ˜1014 cm-3 and a reduced electric field about 10 Td are determined.

  6. Evidence of Filamentary Switching in Oxide-based Memory Devices via Weak Programming and Retention Failure Analysis

    PubMed Central

    Younis, Adnan; Chu, Dewei; Li, Sean

    2015-01-01

    Further progress in high-performance microelectronic devices relies on the development of novel materials and device architectures. However, the components and designs that are currently in use have reached their physical limits. Intensive research efforts, ranging from device fabrication to performance evaluation, are required to surmount these limitations. In this paper, we demonstrate that the superior bipolar resistive switching characteristics of a CeO2:Gd-based memory device can be manipulated by means of UV radiation, serving as a new degree of freedom. Furthermore, the metal oxide-based (CeO2:Gd) memory device was found to possess electrical and neuromorphic multifunctionalities. To investigate the underlying switching mechanism of the device, its plasticity behaviour was studied by imposing weak programming conditions. In addition, a short-term to long-term memory transition analogous to the forgetting process in the human brain, which is regarded as a key biological synaptic function for information processing and data storage, was realized. Based on a careful examination of the device’s retention behaviour at elevated temperatures, the filamentary nature of switching in such devices can be understood from a new perspective. PMID:26324073

  7. Electromagnetic attachment mechanism

    NASA Technical Reports Server (NTRS)

    Monford, Leo G., Jr. (Inventor)

    1992-01-01

    An electromagnetic attachment mechanism is disclosed for use as an end effector of a remote manipulator system. A pair of electromagnets, each with a U-shaped magnetic core with a pull-in coil and two holding coils, are mounted by a spring suspension system on a base plate of the mechanism housing with end pole pieces adapted to move through openings in the base plate when the attractive force of the electromagnets is exerted on a strike plate of a grapple fixture affixed to a target object. The pole pieces are spaced by an air gap from the strike plate when the mechanism first contacts the grapple fixture. An individual control circuit and power source is provided for the pull-in coil and one holding coil of each electromagnet. A back-up control circuit connected to the two power sources and a third power source is provided for the remaining holding coils. When energized, the pull-in coils overcome the suspension system and air gap and are automatically de-energized when the pole pieces move to grapple and impose a preload force across the grapple interface. A battery backup is a redundant power source for each electromagnet in each individual control circuit and is automatically connected upon failure of the primary source. A centerline mounted camera and video monitor are used in cooperation with a target pattern on the reflective surface of the strike plate to effect targeting and alignment.

  8. Multiple-scattering theory for electromagnetic waves

    SciTech Connect

    Wang, X. ); Zhang, X. ); Yu, Q.; Harmon, B.N. )

    1993-02-15

    In this paper, a multiple-scattering formalism for electromagnetic waves is presented. Its application to the three-dimensional periodic dielectric structures is given in a form similar to the usual Korringa-Kohn-Rostoker form of scalar waves. Using this approach, the band-structure results of touching spheres of diamond structure in a dielectric medium with dielectric constant 12.96 are calculated. The application to disordered systems under the coherent-potential approximation is discussed.

  9. Aircraft electromagnetic compatibility

    NASA Technical Reports Server (NTRS)

    Clarke, Clifton A.; Larsen, William E.

    1987-01-01

    Illustrated are aircraft architecture, electromagnetic interference environments, electromagnetic compatibility protection techniques, program specifications, tasks, and verification and validation procedures. The environment of 400 Hz power, electrical transients, and radio frequency fields are portrayed and related to thresholds of avionics electronics. Five layers of protection for avionics are defined. Recognition is given to some present day electromagnetic compatibility weaknesses and issues which serve to reemphasize the importance of EMC verification of equipment and parts, and their ultimate EMC validation on the aircraft. Proven standards of grounding, bonding, shielding, wiring, and packaging are laid out to help provide a foundation for a comprehensive approach to successful future aircraft design and an understanding of cost effective EMC in an aircraft setting.

  10. Electromagnetic particle simulation codes

    NASA Technical Reports Server (NTRS)

    Pritchett, P. L.

    1985-01-01

    Electromagnetic particle simulations solve the full set of Maxwell's equations. They thus include the effects of self-consistent electric and magnetic fields, magnetic induction, and electromagnetic radiation. The algorithms for an electromagnetic code which works directly with the electric and magnetic fields are described. The fields and current are separated into transverse and longitudinal components. The transverse E and B fields are integrated in time using a leapfrog scheme applied to the Fourier components. The particle pushing is performed via the relativistic Lorentz force equation for the particle momentum. As an example, simulation results are presented for the electron cyclotron maser instability which illustrate the importance of relativistic effects on the wave-particle resonance condition and on wave dispersion.

  11. Electromagnetic energy sink

    NASA Astrophysics Data System (ADS)

    Valagiannopoulos, C. A.; Vehmas, J.; Simovski, C. R.; Tretyakov, S. A.; Maslovski, S. I.

    2015-12-01

    The ideal black body fully absorbs all incident rays, that is, all propagating waves created by arbitrary sources. A known idealized realization of the black body is the perfectly matched layer (PML), widely used in numerical electromagnetics. However, ideal black bodies and PMLs do not interact with evanescent fields that exists near any finite-size source, and the energy stored in these fields cannot be harvested. Here, we introduce the concept of the ideal conjugate matched layer (CML), which fully absorbs the energy of both propagating and evanescent fields of sources acting as an ideal sink for electromagnetic energy. Conjugate matched absorbers have exciting application potentials, as resonant attractors of electromagnetic energy into the absorber volume. We derive the conditions on the constitutive parameters of media which can serve as CML materials, numerically study the performance of planar and cylindrical CML and discuss possible realizations of such materials as metal-dielectric composites.

  12. Aircraft electromagnetic compatibility

    NASA Astrophysics Data System (ADS)

    Clarke, Clifton A.; Larsen, William E.

    1987-06-01

    Illustrated are aircraft architecture, electromagnetic interference environments, electromagnetic compatibility protection techniques, program specifications, tasks, and verification and validation procedures. The environment of 400 Hz power, electrical transients, and radio frequency fields are portrayed and related to thresholds of avionics electronics. Five layers of protection for avionics are defined. Recognition is given to some present day electromagnetic compatibility weaknesses and issues which serve to reemphasize the importance of EMC verification of equipment and parts, and their ultimate EMC validation on the aircraft. Proven standards of grounding, bonding, shielding, wiring, and packaging are laid out to help provide a foundation for a comprehensive approach to successful future aircraft design and an understanding of cost effective EMC in an aircraft setting.

  13. Metamaterial electromagnetic wave absorbers.

    PubMed

    Watts, Claire M; Liu, Xianliang; Padilla, Willie J

    2012-06-19

    The advent of negative index materials has spawned extensive research into metamaterials over the past decade. Metamaterials are attractive not only for their exotic electromagnetic properties, but also their promise for applications. A particular branch-the metamaterial perfect absorber (MPA)-has garnered interest due to the fact that it can achieve unity absorptivity of electromagnetic waves. Since its first experimental demonstration in 2008, the MPA has progressed significantly with designs shown across the electromagnetic spectrum, from microwave to optical. In this Progress Report we give an overview of the field and discuss a selection of examples and related applications. The ability of the MPA to exhibit extreme performance flexibility will be discussed and the theory underlying their operation and limitations will be established. Insight is given into what we can expect from this rapidly expanding field and future challenges will be addressed. PMID:22627995

  14. EMACK electromagnetic launcher commissioning

    NASA Astrophysics Data System (ADS)

    Deis, D. W.; Scherbarth, D. W.; Ferrentino, G. L.

    1984-03-01

    The Laboratory Demonstration Electromagnetic Launcher Program (EMACK) was initiated in April 1979, with the objective to design, construct, and demonstrate a complete electromagnetic launcher (EML) system capable of accelerating projectiles of substantial mass to velocities significantly greater than those achievable with conventional chemical systems. The last hardware was installed in late 1981. During February 1982, a series of five test shots was made to evaluate the system's performance. Particular attention is given to the parameters of the final, as-built hardware, and the results of the commissioning tests. The results of these tests have demonstrated the viability of the components required for large scale electromagnetic launchers. It has been shown that large projectiles with velocities significantly greater than those achievable by chemical systems can be accelerated intact.

  15. Electromagnetic properties of baryons

    SciTech Connect

    Ledwig, T.; Pascalutsa, V.; Vanderhaeghen, M.; Martin-Camalich, J.

    2011-10-21

    We discuss the chiral behavior of the nucleon and {Delta}(1232) electromagnetic properties within the framework of a SU(2) covariant baryon chiral perturbation theory. Our one-loop calculation is complete to the order p{sup 3} and p{sup 4}/{Delta} with {Delta} as the {Delta}(1232)-nucleon energy gap. We show that the magnetic moment of a resonance can be defined by the linear energy shift only when an additional relation between the involved masses and the applied magnetic field strength is fulfilled. Singularities and cusps in the pion mass dependence of the {Delta}(1232) electromagnetic moments reflect a non-fulfillment. We show results for the pion mass dependence of the nucleon iso-vector electromagnetic quantities and present preliminary results for finite volume effects on the iso-vector anomalous magnetic moment.

  16. Radial Electromagnetic Press for IGNITOR

    NASA Astrophysics Data System (ADS)

    Cucchiaro, A.; Anzidei, L.; Capriccioli, A.; Celentano, G.; Crescenzi, C.; Gasparotto, M.; Guerrieri, A.; Pizzuto, A.; Palmieri, A.; Rita, C.; Roccella, M.; Coppi, B.

    1998-11-01

    The structural performance of the IGNITOR machine relies upon a combination of both bucking between Toroidal Field Coils (TFCs), Central Solenoid (CS) and the Central Post (CP), and wedging in a well-defined area of the TFCs and of the magnet mechanical structure (called C-Clamps). This requires a pre-loading system to enhance the load bearing capability. Several solutions have been assessed and compared with each other within the operational scenarios and eventually a radial electromagnetic press has been selected as reference(Pizzuto A. et al., ENEA Report IGN/MAC/001/96). The loading system is made up by active coils and passive restraining rings. The radial active press consists of two pairs of coils (200x200mm each), symmetrically located relative to the machine equatorial plane and seating onto the passive rings. The permanent pre--load of the rings is applied through a wedging system with a load of about 120 MN. A radial electromagnetic press has the purpose of modulating the axial pressure on the TFC inner legs during the pulse. Design aspects including stress analysis, manufacturing, assembly and operational scenarios of the selected solution are presented in this paper.

  17. Volcano-electromagnetic effects

    USGS Publications Warehouse

    Johnston, Malcolm J. S.

    2007-01-01

    Volcano-electromagnetic effects—electromagnetic (EM) signals generated by volcanic activity—derive from a variety of physical processes. These include piezomagnetic effects, electrokinetic effects, fluid vaporization, thermal demagnetization/remagnetization, resistivity changes, thermochemical effects, magnetohydrodynamic effects, and blast-excited traveling ionospheric disturbances (TIDs). Identification of different physical processes and their interdependence is often possible with multiparameter monitoring, now common on volcanoes, since many of these processes occur with different timescales and some are simultaneously identified in other geophysical data (deformation, seismic, gas, ionospheric disturbances, etc.). EM monitoring plays an important part in understanding these processes.

  18. Introducing electromagnetic field momentum

    NASA Astrophysics Data System (ADS)

    Yu-Kuang Hu, Ben

    2012-07-01

    I describe an elementary way of introducing electromagnetic field momentum. By considering a system of a long solenoid and line charge, the dependence of the field momentum on the electric and magnetic fields can be deduced. I obtain the electromagnetic angular momentum for a point charge and magnetic monopole pair partially through dimensional analysis and without using vector calculus identities or the need to evaluate integrals. I use this result to show that linear and angular momenta are conserved for a charge in the presence of a magnetic dipole when the dipole strength is changed.

  19. Electromagnetic propulsion test facility

    NASA Technical Reports Server (NTRS)

    Gooder, S. T.

    1984-01-01

    A test facility for the exploration of electromagnetic propulsion concept is described. The facility is designed to accommodate electromagnetic rail accelerators of various lengths (1 to 10 meters) and to provide accelerating energies of up to 240 kiloJoules. This accelerating energy is supplied as a current pulse of hundreds of kiloAmps lasting as long as 1 millisecond. The design, installation, and operating characteristics of the pulsed energy system are discussed. The test chamber and its operation at pressures down to 1300 Pascals (10 mm of mercury) are described. Some aspects of safety (interlocking, personnel protection, and operating procedures) are included.

  20. Superconducting dipole electromagnet

    DOEpatents

    Purcell, John R.

    1977-07-26

    A dipole electromagnet of especial use for bending beams in particle accelerators is wound to have high uniformity of magnetic field across a cross section and to decrease evenly to zero as the ends of the electromagnet are approached by disposing the superconducting filaments of the coil in the crescent-shaped nonoverlapping portions of two intersecting circles. Uniform decrease at the ends is achieved by causing the circles to overlap increasingly in the direction of the ends of the coil until the overlap is complete and the coil is terminated.

  1. Improved Electromagnetic Brake

    NASA Technical Reports Server (NTRS)

    Martin, Toby B.

    2004-01-01

    A proposed design for an electromagnetic brake would increase the reliability while reducing the number of parts and the weight, relative to a prior commercially available electromagnetic brake. The reductions of weight and the number of parts could also lead to a reduction of cost. A description of the commercial brake is prerequisite to a description of the proposed electromagnetic brake. The commercial brake (see upper part of figure) includes (1) a permanent magnet and an electromagnet coil on a stator and (2) a rotor that includes a steel contact plate mounted, with tension spring loading, on an aluminum hub. The stator is mounted securely on a stationary object, which would ordinarily be the housing of a gear drive or a motor. The rotor is mounted on the shaft of the gear drive or motor. The commercial brake nominally operates in a fail-safe (in the sense of normally braking) mode: In the absence of current in the electromagnet coil, the permanent magnet pulls the contact plate, against the spring tension, into contact with the stator. To release the brake, one excites the electromagnet with a current of the magnitude and polarity chosen to cancel the magnetic flux of the permanent magnet, thereby enabling the spring tension to pull the contact plate out of contact with the stator. The fail-safe operation of the commercial brake depends on careful mounting of the rotor in relation to the stator. The rotor/stator gap must be set with a tolerance between 10 and 15 mils (between about 0.25 and about 0.38 mm). If the gap or the contact pad is thicker than the maximum allowable value, then the permanent magnetic field will not be strong enough to pull the steel plate across the gap. (For this reason, any contact pad between the contact plate and the stator must also be correspondingly thin.) If the gap exceeds the maximum allowable value because of shaft end play, it becomes impossible to set the brake by turning off the electromagnet current. Although it may

  2. Elastic metamaterials for tuning circular polarization of electromagnetic waves

    PubMed Central

    Zárate, Yair; Babaee, Sahab; Kang, Sung H.; Neshev, Dragomir N.; Shadrivov, Ilya V.; Bertoldi, Katia; Powell, David A.

    2016-01-01

    Electromagnetic resonators are integrated with advanced elastic material to develop a new type of tunable metamaterial. An electromagnetic-elastic metamaterial able to switch on and off its electromagnetic chiral response is experimentally demonstrated. Such tunability is attained by harnessing the unique buckling properties of auxetic elastic materials (buckliballs) with embedded electromagnetic resonators. In these structures, simple uniaxial compression results in a complex but controlled pattern of deformation, resulting in a shift of its electromagnetic resonance, and in the structure transforming to a chiral state. The concept can be extended to the tuning of three-dimensional materials constructed from the meta-molecules, since all the components twist and deform into the same chiral configuration when compressed. PMID:27320212

  3. Elastic metamaterials for tuning circular polarization of electromagnetic waves.

    PubMed

    Zárate, Yair; Babaee, Sahab; Kang, Sung H; Neshev, Dragomir N; Shadrivov, Ilya V; Bertoldi, Katia; Powell, David A

    2016-01-01

    Electromagnetic resonators are integrated with advanced elastic material to develop a new type of tunable metamaterial. An electromagnetic-elastic metamaterial able to switch on and off its electromagnetic chiral response is experimentally demonstrated. Such tunability is attained by harnessing the unique buckling properties of auxetic elastic materials (buckliballs) with embedded electromagnetic resonators. In these structures, simple uniaxial compression results in a complex but controlled pattern of deformation, resulting in a shift of its electromagnetic resonance, and in the structure transforming to a chiral state. The concept can be extended to the tuning of three-dimensional materials constructed from the meta-molecules, since all the components twist and deform into the same chiral configuration when compressed. PMID:27320212

  4. Elastic metamaterials for tuning circular polarization of electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Zárate, Yair; Babaee, Sahab; Kang, Sung H.; Neshev, Dragomir N.; Shadrivov, Ilya V.; Bertoldi, Katia; Powell, David A.

    2016-06-01

    Electromagnetic resonators are integrated with advanced elastic material to develop a new type of tunable metamaterial. An electromagnetic-elastic metamaterial able to switch on and off its electromagnetic chiral response is experimentally demonstrated. Such tunability is attained by harnessing the unique buckling properties of auxetic elastic materials (buckliballs) with embedded electromagnetic resonators. In these structures, simple uniaxial compression results in a complex but controlled pattern of deformation, resulting in a shift of its electromagnetic resonance, and in the structure transforming to a chiral state. The concept can be extended to the tuning of three-dimensional materials constructed from the meta-molecules, since all the components twist and deform into the same chiral configuration when compressed.

  5. Synergy between different electromagnetic-protection systems

    NASA Astrophysics Data System (ADS)

    Boudenot, J. C.

    1990-04-01

    A new approach to electromagnetic-protection (EP) design is presented. The EP problem for large structures has been shown to be strongly dependent on the various types of electromagnetic constraints (NEMP, lightning, EMC, TEMPEST). Even though the types of protection systems that can be applied are limited, the characteristics of these systems show a potential for synergism in the treatment of the EP. It is shown that, in order to take advantange of this potential synergism and to achieve the best cost-effective design, an early analysis of the protection scenario is required.

  6. Intercode comparison of gyrokinetic global electromagnetic modes

    NASA Astrophysics Data System (ADS)

    Görler, T.; Tronko, N.; Hornsby, W. A.; Bottino, A.; Kleiber, R.; Norscini, C.; Grandgirard, V.; Jenko, F.; Sonnendrücker, E.

    2016-07-01

    Aiming to fill a corresponding lack of sophisticated test cases for global electromagnetic gyrokinetic codes, a new hierarchical benchmark is proposed. Starting from established test sets with adiabatic electrons, fully gyrokinetic electrons, and electrostatic fluctuations are taken into account before finally studying the global electromagnetic micro-instabilities. Results from up to five codes involving representatives from different numerical approaches as particle-in-cell methods, Eulerian and Semi-Lagrangian are shown. By means of spectrally resolved growth rates and frequencies and mode structure comparisons, agreement can be confirmed on ion-gyro-radius scales, thus providing confidence in the correct implementation of the underlying equations.

  7. Multi-scale quantum point contact model for filamentary conduction in resistive random access memories devices

    SciTech Connect

    Lian, Xiaojuan Cartoixà, Xavier; Miranda, Enrique; Suñé, Jordi; Perniola, Luca; Rurali, Riccardo; Long, Shibing; Liu, Ming

    2014-06-28

    We depart from first-principle simulations of electron transport along paths of oxygen vacancies in HfO{sub 2} to reformulate the Quantum Point Contact (QPC) model in terms of a bundle of such vacancy paths. By doing this, the number of model parameters is reduced and a much clearer link between the microscopic structure of the conductive filament (CF) and its electrical properties can be provided. The new multi-scale QPC model is applied to two different HfO{sub 2}-based devices operated in the unipolar and bipolar resistive switching (RS) modes. Extraction of the QPC model parameters from a statistically significant number of CFs allows revealing significant structural differences in the CF of these two types of devices and RS modes.

  8. Broadband electromagnetic cloaking with smart metamaterials.

    PubMed

    Shin, Dongheok; Urzhumov, Yaroslav; Jung, Youngjean; Kang, Gumin; Baek, Seunghwa; Choi, Minjung; Park, Haesung; Kim, Kyoungsik; Smith, David R

    2012-01-01

    The ability to render objects invisible with a cloak that fits all objects and sizes is a long-standing goal for optical devices. Invisibility devices demonstrated so far typically comprise a rigid structure wrapped around an object to which it is fitted. Here we demonstrate smart metamaterial cloaking, wherein the metamaterial device not only transforms electromagnetic fields to make an object invisible, but also acquires its properties automatically from its own elastic deformation. The demonstrated device is a ground-plane microwave cloak composed of an elastic metamaterial with a broad operational band (10-12 GHz) and nearly lossless electromagnetic properties. The metamaterial is uniform, or perfectly periodic, in its undeformed state and acquires the necessary gradient-index profile, mimicking a quasi-conformal transformation, naturally from a boundary load. This easy-to-fabricate hybrid elasto-electromagnetic metamaterial opens the door to implementations of a variety of transformation optics devices based on quasi-conformal maps. PMID:23169054

  9. Electromagnetic processes in the atmosphere of pulsars

    NASA Technical Reports Server (NTRS)

    Yukhimuk, A. K.

    1974-01-01

    The work consists of two parts. The first deals with the fine structure of radio pulses. Based on kinetic theory, processes occurring in the plasma shell of a pulsar when external electromagnetic radiation is present are investigated. It is shown that electromagnetic waves cause electrons to drift relative to ions, and initiate longitudinal oscillations. A dispersion equation describing the longitudinal oscillations in magnetized plasma is derived. Conditions for excitation of oscillations are found. Correlation functions of electron density are calculated, along with the coefficients of electromagnetic wave scattering. It is shown that variations in the amplitude of pulsar pulses are associated with scintillations caused by fluctuations in the plasma electron density. The second part of the study presents a mechanism for the radio emission of pulsars. The model of a rotating and a pulsating star, a neutron star with dipolar or more complex magnetic field, is examined.

  10. Electromagnetic braking for Mars spacecraft

    NASA Technical Reports Server (NTRS)

    Holt, A. C.

    1986-01-01

    Aerobraking concepts are being studied to improve performance and cost effectiveness of propulsion systems for Mars landers and Mars interplanetary spacecraft. Access to megawatt power levels (nuclear power coupled to high-storage inductive or capacitive devices) on a manned Mars interplanetary spacecraft may make feasible electromagnetic braking and lift modulation techniques which were previously impractical. Using pulsed microwave and magnetic field technology, potential plasmadynamic braking and hydromagnetic lift modulation techniques have been identified. Entry corridor modulation to reduce loads and heating, to reduce vertical descent rates, and to expand horizontal and lateral landing ranges are possible benefits. In-depth studies are needed to identify specific design concepts for feasibility assessments. Standing wave/plasma sheath interaction techniques appear to be promising. The techniques may require some tailoring of spacecraft external structures and materials. In addition, rapid response guidance and control systems may require the use of structurally embedded sensors coupled to expert systems or to artificial intelligence systems.

  11. The CMS Electromagnetic Calorimeter

    SciTech Connect

    Paramatti, Riccardo

    2005-10-12

    The electromagnetic calorimeter of the CMS experiment at LHC will consist of about 76000 Lead Tungstate crystals. Its main purpose is the very precise energy measurement of electrons and photons produced at 14 TeV centre-of-mass energy. A review of its performances and its construction status is given. Then the calibration strategy is described in details.

  12. Equivalence principles and electromagnetism

    NASA Technical Reports Server (NTRS)

    Ni, W.-T.

    1977-01-01

    The implications of the weak equivalence principles are investigated in detail for electromagnetic systems in a general framework. In particular, it is shown that the universality of free-fall trajectories (Galileo weak equivalence principle) does not imply the validity of the Einstein equivalence principle. However, the Galileo principle plus the universality of free-fall rotation states does imply the Einstein principle.

  13. Electromagnetic radiation detector

    DOEpatents

    Benson, Jay L.; Hansen, Gordon J.

    1976-01-01

    An electromagnetic radiation detector including a collimating window, a cathode member having a photoelectric emissive material surface angularly disposed to said window whereby radiation is impinged thereon at acute angles, an anode, separated from the cathode member by an evacuated space, for collecting photoelectrons emitted from the emissive cathode surface, and a negatively biased, high transmissive grid disposed between the cathode member and anode.

  14. Superconductive electromagnet apparatus

    SciTech Connect

    Mine, S.

    1982-12-14

    Disclosed is a superconductive electromagnet apparatus having a coil with a coiled conductor with a channel between adjacently disposed the paths of the coil conductor of which width is selected in accordance with amounts of heat produced at the corresponding portions of the coil section as viewed in cross section.

  15. Noncontact Electromagnetic Vibration Source

    NASA Technical Reports Server (NTRS)

    Namkung, Min; Fulton, James P.; Wincheski, Buzz A.

    1994-01-01

    Metal aircraft skins scanned rapidly in vibration tests. Relatively simple combination of permanent magnets and electromagnet serves as noncontact vibration source for nondestructive testing of metal aircraft skins. In test, source excites vibrations, and vibration waveforms measured, then analyzed for changes in resonances signifying cracks and other flaws.

  16. Simple Superconducting "Permanent" Electromagnet

    NASA Technical Reports Server (NTRS)

    Israelson, Ulf E.; Strayer, Donald M.

    1992-01-01

    Proposed short tube of high-temperature-superconducting material like YBa2Cu3O7 acts as strong electromagnet that flows as long as magnetic field remains below critical value and temperature of cylinder maintained sufficiently below superconducting-transition temperature. Design exploits maximally anisotropy of high-temperature-superconducting material.

  17. "Hearing" Electromagnetic Waves

    ERIC Educational Resources Information Center

    Rojo, Marta; Munoz, Juan

    2014-01-01

    In this work, an educational experience is described in which a microwave communication link is used to make students aware that all electromagnetic waves have the same physical nature and properties. Experimental demonstrations are linked to theoretical concepts to increase comprehension of the physical principles underlying electromagnetic…

  18. Microscale Electromagnetic Heating in Heterogeneous Energetic Materials Based on X-ray Computed Tomography

    NASA Astrophysics Data System (ADS)

    Kort-Kamp, W. J. M.; Cordes, N. L.; Ionita, A.; Glover, B. B.; Duque, A. L. Higginbotham; Perry, W. L.; Patterson, B. M.; Dalvit, D. A. R.; Moore, D. S.

    2016-04-01

    Electromagnetic stimulation of energetic materials provides a noninvasive and nondestructive tool for detecting and identifying explosives. We combine structural information based on x-ray computed tomography, experimental dielectric data, and electromagnetic full-wave simulations to study microscale electromagnetic heating of realistic three-dimensional heterogeneous explosives. We analyze the formation of electromagnetic hot spots and thermal gradients in the explosive-binder mesostructures and compare the heating rate for various binder systems.

  19. Microscale electromagnetic heating in heterogeneous energetic materials based on x-ray computed tomography

    DOE PAGESBeta

    Kort-Kamp, W. J. M.; Cordes, N. L.; Ionita, A.; Glover, B. B.; Duque, A. L. Higginbotham; Perry, W. L.; Patterson, B. M.; Dalvit, D. A. R.; Moore, D. S.

    2016-04-01

    Electromagnetic stimulation of energetic materials provides a noninvasive and nondestructive tool for detecting and identifying explosives. We combine structural information based on x-ray computed tomography, experimental dielectric data, and electromagnetic full-wave simulations to study microscale electromagnetic heating of realistic three-dimensional heterogeneous explosives. In conclusion, we analyze the formation of electromagnetic hot spots and thermal gradients in the explosive-binder mesostructures and compare the heating rate for various binder systems.

  20. How do the barrier thickness and dielectric material influence the filamentary mode and CO2 conversion in a flowing DBD?

    NASA Astrophysics Data System (ADS)

    Ozkan, A.; Dufour, T.; Bogaerts, A.; Reniers, F.

    2016-08-01

    Dielectric barrier discharges (DBDs) are commonly used to generate cold plasmas at atmospheric pressure. Whatever their configuration (tubular or planar), the presence of a dielectric barrier is mandatory to prevent too much charge build up in the plasma and the formation of a thermal arc. In this article, the role of the barrier thickness (2.0, 2.4 and 2.8 mm) and of the kind of dielectric material (alumina, mullite, pyrex, quartz) is investigated on the filamentary behavior in the plasma and on the CO2 conversion in a tubular flowing DBD, by means of mass spectrometry measurements correlated with electrical characterization and IR imaging. Increasing the barrier thickness decreases the capacitance, while preserving the electrical charge. As a result, the voltage over the dielectric increases and a larger number of microdischarges is generated, which enhances the CO2 conversion. Furthermore, changing the dielectric material of the barrier, while keeping the same geometry and dimensions, also affects the CO2 conversion. The highest CO2 conversion and energy efficiency are obtained for quartz and alumina, thus not following the trend of the relative permittivity. From the electrical characterization, we clearly demonstrate that the most important parameters are the somewhat higher effective plasma voltage (yielding a somewhat higher electric field and electron energy in the plasma) for quartz, as well as the higher plasma current (and thus larger electron density) and the larger number of microdischarge filaments (mainly for alumina, but also for quartz). The latter could be correlated to the higher surface roughness for alumina and to the higher voltage over the dielectric for quartz.

  1. Computational Electronics and Electromagnetics

    SciTech Connect

    DeFord, J.F.

    1993-03-01

    The Computational Electronics and Electromagnetics thrust area is a focal point for computer modeling activities in electronics and electromagnetics in the Electronics Engineering Department of Lawrence Livermore National Laboratory (LLNL). Traditionally, they have focused their efforts in technical areas of importance to existing and developing LLNL programs, and this continues to form the basis for much of their research. A relatively new and increasingly important emphasis for the thrust area is the formation of partnerships with industry and the application of their simulation technology and expertise to the solution of problems faced by industry. The activities of the thrust area fall into three broad categories: (1) the development of theoretical and computational models of electronic and electromagnetic phenomena, (2) the development of useful and robust software tools based on these models, and (3) the application of these tools to programmatic and industrial problems. In FY-92, they worked on projects in all of the areas outlined above. The object of their work on numerical electromagnetic algorithms continues to be the improvement of time-domain algorithms for electromagnetic simulation on unstructured conforming grids. The thrust area is also investigating various technologies for conforming-grid mesh generation to simplify the application of their advanced field solvers to design problems involving complicated geometries. They are developing a major code suite based on the three-dimensional (3-D), conforming-grid, time-domain code DSI3D. They continue to maintain and distribute the 3-D, finite-difference time-domain (FDTD) code TSAR, which is installed at several dozen university, government, and industry sites.

  2. Evaluation of a metal shear web selectively reinforced with filamentary composites for space shuttle application

    NASA Technical Reports Server (NTRS)

    Laakso, J. H.; Straayer, J. W.

    1974-01-01

    A final program summary is reported for test and evaluation activities that were conducted for space shuttle web selection. Large scale advanced composite shear web components were tested and analyzed to evaluate application of advanced composite shear web construction to a space shuttle orbiter thrust structure. The shear web design concept consisted of a titanium-clad + or - 45 deg boron/epoxy web laminate stiffened with vertical boron-epoxy reinforced aluminum stiffeners and logitudinal aluminum stiffening. The design concept was evaluated to be efficient and practical for the application that was studied. Because of the effects of buckling deflections, a requirement is identified for shear buckling resistant design to maximize the efficiency of highly-loaded advanced composite shear webs.

  3. Gas kinematics and excitation in the filamentary IRDC G035.39-00.33

    NASA Astrophysics Data System (ADS)

    Jiménez-Serra, I.; Caselli, P.; Fontani, F.; Tan, J. C.; Henshaw, J. D.; Kainulainen, J.; Hernandez, A. K.

    2014-04-01

    Some theories of dense molecular cloud formation involve dynamical environments driven by converging atomic flows or collisions between preexisting molecular clouds. The determination of the dynamics and physical conditions of the gas in clouds at the early stages of their evolution is essential to establish the dynamical imprints of such collisions, and to infer the processes involved in their formation. We present multitransition 13CO and C18O maps towards the IRDC G035.39-00.33, believed to be at the earliest stages of evolution. The 13CO and C18O gas is distributed in three filaments (Filaments 1, 2 and 3), where the most massive cores are preferentially found at the intersecting regions between them. The filaments have a similar kinematic structure with smooth velocity gradients of ˜0.4-0.8 km s-1 pc-1. Several scenarios are proposed to explain these gradients, including cloud rotation, gas accretion along the filaments, global gravitational collapse and unresolved sub-filament structures. These results are complemented by HCO+, HNC, H13CO+ and HN13C single-pointing data to search for gas infall signatures. The 13CO and C18O gas motions are supersonic across G035.39-00.33, with the emission showing broader linewidths towards the edges of the infrared dark cloud (IRDC). This could be due to energy dissipation at the densest regions in the cloud. The average H2 densities are ˜5000-7000 cm-3, with Filaments 2 and 3 being denser and more massive than Filament 1. The C18O data unveil three regions with high CO depletion factors (fD ˜ 5-12), similar to those found in massive starless cores.

  4. Electromagnetic properties of ice coated surfaces

    NASA Technical Reports Server (NTRS)

    Dominek, A.; Walton, E.; Wang, N.; Beard, L.

    1989-01-01

    The electromagnetic scattering from ice coated structures is examined. The influence of ice is shown from a measurement standpoint and related to a simple analytical model. A hardware system for the realistic measurement of ice coated structures is also being developed to use in an existing NASA Lewis icing tunnel. Presently, initial measurements have been performed with a simulated tunnel to aid in the development.

  5. Weakly relativistic electromagnetic solitons in warm plasmas

    NASA Astrophysics Data System (ADS)

    Sundar, Sita

    2016-06-01

    For slowly propagating electromagnetic solitons, validity of the cold plasma model is addressed using a more realistic model involving effects arising due to temperature as well as ion dynamics. Small amplitude single peak structures which are quasineutral are studied, and different regions of existence of bright and dark classes of solitons are delineated. Influence of temperature on spectral characteristics of the solitary structures is presented.

  6. Electromagnetic induction in the Earth

    NASA Astrophysics Data System (ADS)

    Fergurson, Ian; Slater, Lee; Queralt, Pilar; Ledo, Juanjo

    Measurements of electrical properties of the Earth using electromagnetic induction (EM) can elucidate geological structures and processes ranging from meter to mantle scale. The 18th International Workshop on Electromagnetic Induction in the Earth (EMIW) highlighted how recent theoretical and instrumental advances are being applied in high-quality EM induction studies from around the world, at lithospheric, crustal, and near-surface scales.Important aspects of the lithospheric and crustal studies presented included the demonstration of the increased resolution provided by dense two-dimensional magnetotelluric (MT) profiles and three-dimensional grids, the common use of the improved impedance tensor decomposition method to correct regional MT responses, widespread consideration of implicitly anisotropic materials within multidimensional MT models, and, in the numerical modeling field, the increased use of unstructured meshes. Review papers provided an overview of the large-scale EM surveys and spatial variations in the European lithosphere and addressed the role of EM in monitoring seismic and volcanic crustal processes.

  7. Electromagnetic wave energy conversion research

    NASA Technical Reports Server (NTRS)

    Bailey, R. L.; Callahan, P. S.

    1975-01-01

    Known electromagnetic wave absorbing structures found in nature were first studied for clues of how one might later design large area man-made radiant-electric converters. This led to the study of the electro-optics of insect dielectric antennae. Insights were achieved into how these antennae probably operate in the infrared 7-14um range. EWEC theoretical models and relevant cases were concisely formulated and justified for metal and dielectric absorber materials. Finding the electromagnetic field solutions to these models is a problem not yet solved. A rough estimate of losses in metal, solid dielectric, and hollow dielectric waveguides indicates future radiant-electric EWEC research should aim toward dielectric materials for maximum conversion efficiency. It was also found that the absorber bandwidth is a theoretical limitation on radiant-electric conversion efficiency. Ideally, the absorbers' wavelength would be centered on the irradiating spectrum and have the same bandwith as the irradiating wave. The EWEC concept appears to have a valid scientific basis, but considerable more research is needed before it is thoroughly understood, especially for the complex randomly polarized, wide band, phase incoherent spectrum of the sun. Specific recommended research areas are identified.

  8. SOFIA/FORCAST Observations of the Arched Filamentary Region in the Galactic Center

    NASA Astrophysics Data System (ADS)

    Hankins, Matthew; Lau, Ryan M.; Morris, Mark; Herter, Terry L.

    2016-06-01

    Abstract: We present 19.7, 25.2, 31.5, and 37.1 μm maps of the Thermal Arched Filament region in the Galactic Center taken with the Faint Object Infrared Camera for the SOFIA Telescope (FORCAST) with an angular resolution of 3.2-3.8". We calculate the integrated infrared luminosity of the Arched Filaments and show that they are consistent with being heated by the nearby Arches cluster. Additionally, using our observations, we infer dust temperatures (75 – 90 K) across the Arched Filaments which are remarkably consistent over large spatial scales (∼ 25 pc). We discuss the possible geometric effects needed to recreate this temperature structure. Additionally, we compare the observed morphology of the Arches in the FORCAST maps with the Paschen-α emission in the region to study what fraction of the infrared emission may be coming from dust in the HII region versus the PDR beneath it. Finally, we use Spitzer/IRAC 8 μm data to look for spatial variations in PAH abundance in the rich UV environment of the young (~2-4 Myr) and massive Arches cluster.

  9. Electromagnetic Environment of Grounding Systems

    NASA Astrophysics Data System (ADS)

    Lefouili, M.; Hafsaoui, I.; Kerroum, K.; Drissi, K. El Khamlichi

    Electromagnetic compatibility (EMC) and lightning protection studies in large installations require knowledge of spatial and temporal distribution of electromagnetic fields in case of lightning and power system faults. A new hybrid method for modeling electromagnetic environment of grounding systems is developed in this work. The electromagnetic fields in the surrounding soil are determined from the previously calculated current distribution using dipoles theory with analytical formulas. The model can be used to predict the EM environment of grounding systems because it can calculate electromagnetic fields in any points of interest.

  10. Measurement of Electromagnetic Properties of Lightning with 10 Nanosecond Resolution

    NASA Technical Reports Server (NTRS)

    Baum, C. E.; Breen, E. L.; Oneill, J. P.; Moore, C. B.; Hall, D. L.

    1980-01-01

    Electromagnetic data recorded from lightning strikes are presented. The data analysis reveals general characteristics of fast electromagnetic fields measured at the ground including rise times, amplitudes, and time patterns. A look at the electromagnetic structure of lightning shows that the shortest rise times in the vicinity of 30 ns are associated with leader leader streamers. Lightning location is based on electromagnetic field characteristics and is compared to a nearby sky camera. The fields from both leaders and return strokes were measured and are discussed. The data were obtained during 1978 and 1979 from lightning strikes occuring within 5 kilometers of an underground metal instrumentation room located on South Baldy peak near Langmuir Laboratory, New Mexico. The computer controlled instrumentation consisted of sensors previously used for measuring the nuclear electromagnetic pulse (EMP) and analog-digital recorders with 10 ns sampling, 256 levels of resolution, and 2 kilobytes of internal memory.

  11. High temperature electromagnetic characterization of thermal protection system tile materials

    NASA Technical Reports Server (NTRS)

    Heil, Garrett G.

    1993-01-01

    This study investigated the impact of elevated temperatures on the electromagnetic performance of the LI-2200 thermal protection system. A 15-kilowatt CO2 laser was used to heat an LI-2200 specimen to 3000 F while electromagnetic measurements were performed over the frequency range of l9 to 21 GHz. The electromagnetic measurement system consisted of two Dual-Lens Spot-Focusing (DLSF) antennas, a sample support structure, and an HP-8510B vector network analyzer. Calibration of the electromagnetic system was accomplished with a Transmission-Reflection-Line (TRL) procedure and was verified with measurements on a two-layer specimen of known properties. The results of testing indicated that the LI-2200 system's electromagnetic performance is slightly temperature dependent at temperatures up to 3000 F.

  12. Electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L. (Inventor)

    1973-01-01

    Electromagnetic wave energy is converted into electric power with an array of mutually insulated electromagnetic wave absorber elements each responsive to an electric field component of the wave as it impinges thereon. Each element includes a portion tapered in the direction of wave propagation to provide a relatively wideband response spectrum. Each element includes an output for deriving a voltage replica of the electric field variations intercepted by it. Adjacent elements are positioned relative to each other so that an electric field subsists between adjacent elements in response to the impinging wave. The electric field results in a voltage difference between adjacent elements that is fed to a rectifier to derive dc output power.

  13. DIRECT CURRENT ELECTROMAGNETIC PUMP

    DOEpatents

    Barnes, A.H.

    1957-11-01

    An improved d-c electromagnetic pump is presented in which the poles, and consequently the magetic gap at the poles, are tapered to be wider at the upstream end. In addition, the cross section of the tube carryiQ the liquid metal is tapered so that the velocity of the pumped liquid increases in the downstream direction at a rate such that the counter-induced voltage in the liquid metal remains constant as it traverses the region between the poles. This configuration compensates for the distortion of the magnetic field caused by the induced voltage that would otherwise result in the lowering of the pumping capacity. This improved electromagnetic pump as practical application in the pumping of liquid metal coolants for nuclear reactors where conventional positive displacement pumps have proved unsatisfactory due to the high temperatures and the corrosive properties of the liquid metals involved.

  14. Computational electronics and electromagnetics

    SciTech Connect

    Shang, C C

    1998-01-01

    The Computational Electronics and Electromagnetics thrust area serves as the focal point for Engineering R and D activities for developing computer-based design and analysis tools. Representative applications include design of particle accelerator cells and beamline components; design of transmission line components; engineering analysis and design of high-power (optical and microwave) components; photonics and optoelectronics circuit design; electromagnetic susceptibility analysis; and antenna synthesis. The FY-97 effort focuses on development and validation of (1) accelerator design codes; (2) 3-D massively parallel, time-dependent EM codes; (3) material models; (4) coupling and application of engineering tools for analysis and design of high-power components; and (5) development of beam control algorithms coupled to beam transport physics codes. These efforts are in association with technology development in the power conversion, nondestructive evaluation, and microtechnology areas. The efforts complement technology development in Lawrence Livermore National programs.

  15. Electromagnetic targeting of guns

    SciTech Connect

    Pogue, E.W.; Boat, R.M.; Holden, D.N.; Lopez, J.R.

    1996-10-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Electromagnetic pulse (EMP) signals produced from explosives being fired have been reported in the literature for fifty years. When a gun is fired it produces an EMP muzzle blast signal. The strength and nature of these signals was first analyzed in the early 1970s, while the results were interesting, no follow-up studies were conducted. With modern detection and signal processing technology, we believe that these signals could be used to instantaneously locate guns of virtually all calibers as they fire. The objective of our one-year project was to establish the basic nature of these signals and their utility in the concept of electromagnetic targeting of guns.

  16. ELECTROMAGNETIC RELEASE MECHANISM

    DOEpatents

    Michelson, C.

    1960-09-13

    An electromagnetic release mechanism is offered that may be used, for example, for supporting a safety rod for a nuclear reactor. The release mechanism is designed to have a large excess holding force and a rapid, uniform, and dependable release. The fast release is accomplished by providing the electromagnet with slotttd polts separated by an insulating potting resin, and by constructing the poles with a ferro-nickel alloy. The combination of these two features materially reduces the eddy current power density whenever the magnetic field changes during a release operation. In addition to these features, the design of the armature is such as to provide ready entrance of fluid into any void that might tend to form during release of the armature. This also improves the release time for the mechanism. The large holding force for the mechanism is accomplished by providing a small, selected, uniform air gap between the inner pole piece and the armature.

  17. Banded electromagnetic stator core

    DOEpatents

    Fanning, A.W.; Gonzales, A.A.; Patel, M.R.; Olich, E.E.

    1996-06-11

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups. 5 figs.

  18. Banded electromagnetic stator core

    DOEpatents

    Fanning, A.W.; Gonzales, A.A.; Patel, M.R.; Olich, E.E.

    1994-04-05

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups. 5 figures.

  19. Electromagnetically coupled microstrip dipoles

    NASA Astrophysics Data System (ADS)

    Oltman, H. G.; Huebner, D. A.

    1981-01-01

    A new class of printed circuit radiator consisting of a microstrip dipole electromagnetically coupled to a microstrip feed line is described. Several configurations which differ in bandwidth, efficiency, and construction simplicity are presented. A geometry which has been found to be optimum for many applications is noted. Radiation characteristics of both isolated elements and arrays of elements are examined. Experimental and theoretical results are presented.

  20. Proca and electromagnetic fields

    SciTech Connect

    Hillion, P.; Quinnerz, S.

    1986-07-01

    In the framework of the proper orthochronous Lorentz group, the old connection is revived between the electromagnetic field characterized by a self-dual tensor and a traceless second-rank spinor obeying the Proca equation. The relationship between this spinor and the Hertz potential also considered as a self-dual tensor is emphasized. The extension of this formalism to meet the covariance under the full Lorentz group is also discussed.

  1. Banded electromagnetic stator core

    DOEpatents

    Fanning, Alan W.; Gonzales, Aaron A.; Patel, Mahadeo R.; Olich, Eugene E.

    1994-01-01

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups.

  2. Banded electromagnetic stator core

    DOEpatents

    Fanning, Alan W.; Gonzales, Aaron A.; Patel, Mahadeo R.; Olich, Eugene E.

    1996-01-01

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups.

  3. Electromagnetic tornadoes in space

    SciTech Connect

    Chang, T.; Crew, G.B.; Retterer, J.M.

    1988-01-01

    The exotic phenomenon of energetic-ion conic formation by plasma waves in the magnetosphere is considered. Two particular transverse heating mechanisms are reviewed in detail; lower-hybrid energization of ions in the boundary layer of the plasma sheet and electromagnetic ion cyclotron resonance heating in the central region of the plasma sheet. Mean particle calculations, plasma simulations and analytical treatments of the heating processes are described.

  4. CMS electromagnetic calorimeter readout

    SciTech Connect

    Denes, P.; Wixted, R.

    1997-12-31

    The CMS Electromagnetic Calorimeter will consist of 109,008 crystals of Lead Tungstate (PbWO{sub 4}) arranged in a barrel (92880 crystals) and 2 endcaps (8064 crystals each). The crystals will be 25 radiation lengths long and cut in tapered shapes to make a hermetic calorimeter. The scintillation light from the crystals is captured by a photodetector, amplified and digitized. The properties of PbWO4, which is a new crystal still very much under development.

  5. Electromagnetically Activated Hypersonic Ducts

    NASA Astrophysics Data System (ADS)

    MacLeod, C.

    This paper explores the use of Electromagnetic Radiation as an alternative to combustion in Scramjet-like hypersonic engines. The radiation is absorbed by the flow, heating it and thereby providing an alternative to the heat derived from combustion in the Scramjet. The advantages and disadvantages of this system are explored and theoretical results are presented illustrating typical radiation pathlengths at different frequencies. Suggestions for further theoretical and practical work are also made.

  6. Electromagnetically induced angular Talbot effect

    NASA Astrophysics Data System (ADS)

    Qiu, Tianhui; Yang, Guojian

    2015-12-01

    The discrete angular spectrum (angular Talbot effect) of a periodic grating illuminated by a suitable spherical wave front has been observed recently (Azaña and Chatellus 2104 Phys. Rev. Lett. 112 213902). In this paper we study the possibility of such a phenomenon being realized with a medium that has no macroperiodic structure itself. Tunable electromagnetically induced grating (EIG) could be such a kind of medium. We obtain an EIG based on the periodically modulated strong susceptibility due to the third-order nonlinear effect generated in a double Λ-type four-level atomic system, and show the angular Talbot effect of an amplitude EIG, as well as a hybrid EIG, as the condition of the discrete phase-modulation shift of the illumination light front is satisfied. EIG parameters are tunable and the EIG-based angular Talbot effect may have the same potential applications as its periodic grating counterpart has.

  7. Coherent hybrid electromagnetic field imaging

    DOEpatents

    Cooke, Bradly J.; Guenther, David C.

    2008-08-26

    An apparatus and corresponding method for coherent hybrid electromagnetic field imaging of a target, where an energy source is used to generate a propagating electromagnetic beam, an electromagnetic beam splitting means to split the beam into two or more coherently matched beams of about equal amplitude, and where the spatial and temporal self-coherence between each two or more coherently matched beams is preserved. Two or more differential modulation means are employed to modulate each two or more coherently matched beams with a time-varying polarization, frequency, phase, and amplitude signal. An electromagnetic beam combining means is used to coherently combine said two or more coherently matched beams into a coherent electromagnetic beam. One or more electromagnetic beam controlling means are used for collimating, guiding, or focusing the coherent electromagnetic beam. One or more apertures are used for transmitting and receiving the coherent electromagnetic beam to and from the target. A receiver is used that is capable of square-law detection of the coherent electromagnetic beam. A waveform generator is used that is capable of generation and control of time-varying polarization, frequency, phase, or amplitude modulation waveforms and sequences. A means of synchronizing time varying waveform is used between the energy source and the receiver. Finally, a means of displaying the images created by the interaction of the coherent electromagnetic beam with target is employed.

  8. Facile aqueous synthesis and electromagnetic properties of novel 3D urchin-like glass/Ni-Ni(3)P/Co(2)P(2)O(7) core/shell/shell composite hollow structures.

    PubMed

    An, Zhenguo; Zhang, Jingjie; Pan, Shunlong

    2010-04-14

    Novel 3D urchin-like glass/Ni-Ni(3)P/Co(2)P(2)O(7) core/shell/shell composite hollow structures are fabricated for the first time by controlled stepwise assembly of granular Ni-Ni(3)P alloy and ribbon-like Co(2)P(2)O(7) nanocrystals on hollow glass spheres in aqueous solutions at mild conditions. It is found that the shell structure and the overall morphology of the products can be tailored by properly tuning the annealing temperature. The as-obtained composite core/shell/shell products possess low density (ca. 1.18 g cm(-3)) and shape-dependent magnetic and microwave absorbing properties, and thus may have some promising applications in the fields of low-density magnetic materials, microwave absorbers, etc. Based on a series of contrast experiments, the probable formation mechanism of the core/shell/shell hierarchical structures is proposed. This work provides an additional strategy to prepare core/shell composite spheres with tailored shell morphology and electromagnetic properties. PMID:20379530

  9. Composite structural materials. [aircraft structures

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1980-01-01

    The use of filamentary composite materials in the design and construction of primary aircraft structures is considered with emphasis on efforts to develop advanced technology in the areas of physical properties, structural concepts and analysis, manufacturing, and reliability and life prediction. The redesign of a main spar/rib region on the Boeing 727 elevator near its actuator attachment point is discussed. A composite fabrication and test facility is described as well as the use of minicomputers for computer aided design. Other topics covered include (1) advanced structural analysis methids for composites; (2) ultrasonic nondestructive testing of composite structures; (3) optimum combination of hardeners in the cure of epoxy; (4) fatigue in composite materials; (5) resin matrix characterization and properties; (6) postbuckling analysis of curved laminate composite panels; and (7) acoustic emission testing of composite tensile specimens.

  10. Complementary Electromagnetic Non-Destructive Evaluation

    NASA Astrophysics Data System (ADS)

    Tian, Gui Yun; Wilson, John; Morozov, Maxim

    2011-06-01

    The use of non-destructive evaluation (NDE) for defect detection and failure prediction in structures and specimens is widespread in energy industries, aimed at ageing power plants and pipelines, material degradation, fatigue and radiation damage, etc. At present there are no suitable electromagnetic NDE methods for the measurement and characterization of material degradation, in irradiated samples in particular, which is very important and timely for the nuclear power industry in the UK. This paper reports recent developments in the field of electromagnetic (EM) NDE at Newcastle University, including pulsed eddy current (PEC), pulsed magnetic flux leakage (PMFL), magnetic Barkhausen emission (MBE) and magneto-acoustic emission (MAE). As different EM methods have different strengths, an integrative EM framework is introduced. Case studies through the second round robin tests organized by the Universal Network for Magnetic Non-Destructive Evaluation (UNMNDE), representing eighteen leading research groups worldwide in the area of electromagnetic NDE, are reported. Twelve samples with different ageing times and rolling reduction ratios were tested using different magnetic methods among the UNMNDE members. Based on the studies, the complementary characteristics of electromagnetic techniques for NDE are discussed.

  11. Resonant response of electromagnetic scattering from ellipsoid

    NASA Astrophysics Data System (ADS)

    Gavriloaia, Mihai-Bogdan; Vizireanu, Constantin-Radu; Neamtu, Catalin; Preda, Radu; Achimescu, Emanuel; Halunga, Simona

    2015-02-01

    Modern radars must provide in a very short time: existence, mobility and shape of objects evolving in airspace. Evaluation of the object shapes through active research by using synthetic aperture radar is limited in time, resolution, and cost. A new way of processing non-stationary signals is presented in this article. Signals are obtained from the reflection of the electromagnetic field by objects with complex shape when they are irradiated with linear frequency modulated signals. The amplitude of reflected signal is variable on the radio-impulse duration depending on object shape, causing a certain electromagnetic signature. This phenomenon is caused by specific electromagnetic resonance. The reflected signal has maximum amplitude when the frequency of the incident wave is the same with the resonant frequency of the investigated object. The structure of an radar target can be decomposed into simple geometric shapes such as spheres, ellipsoids, prisms, and so on. Using resonant effect that ensures pattern recognition is exemplified by an object with an aerodynamic profile accepted in many component elements of the aircraft, namely - an ellipsoid. It is a geometric shape used extensively in aviation, because it has a very low aerodynamic resistance. The resonant response of ellipsoid is evaluated in a decade frequency band, but the pattern recognition of this shape is enough for an octave band. The resonant response is assessed for cross polarization of incident electromagnetic field, as well. As a result, the radio-impulse shape can be used in a data base for pattern recognition.

  12. Study on the mode-transition of nanosecond-pulsed dielectric barrier discharge between uniform and filamentary by controlling pressures and pulse repetition frequencies

    NASA Astrophysics Data System (ADS)

    Yu, S.; Pei, X.; Hasnain, Q.; Nie, L.; Lu, X.

    2016-02-01

    In this paper, we investigate the temporally resolved evolution of the nanosecond pulsed dielectric barrier discharge (DBD) in a moderate 6 mm discharge gap under various pressures and pulse repetition frequencies (PRFs) by intensified charge-coupled device (ICCD) images, using dry air and its components oxygen and nitrogen. It is found that the pressures are very different when the mode transits between uniform and filamentary in air, oxygen, and nitrogen. The PRFs can also obviously affect the mode-transition. The transition mechanism in the pulsed DBD is not Townsend-to-Streamer, which is dominant in the traditional alternating-voltage DBD. The pulsed DBD in a uniform mode develops in the form of plane ionization wave due to overlap of primary avalanches, while the increase in pressure disturbs the overlap and discharge develops in streamer, corresponding to the filamentary mode. Increasing the initial electron density by pre-ionization may contribute to discharge uniformity at higher pressures. We also found that the dependence of homogeneity upon PRF is a non-monotonic one.

  13. Electromagnetic Theory 3 Volume Set

    NASA Astrophysics Data System (ADS)

    Heaviside, Oliver

    2011-09-01

    Volume 1: Preface; 1. Introduction; 2. Outline of the electromagnetic connections; 3. The elements of vectorial algebra and analysis; 4. Theory of plane electromagnetic waves; Appendix. Volume 2: Preface; 5. Mathematics and the age of the earth; 6. Pure diffusion of electric displacement; 7. Electromagnetic waves and generalised differentiation; 8. Generalised differentiation and divergent series; Appendix. Volume 3: 9. Waves from moving sources; 10. Waves in the ether.

  14. Electromagnetic Meissner-Effect Launcher

    NASA Technical Reports Server (NTRS)

    Robertson, Glen A.

    1990-01-01

    Proposed electromagnetic Meissner-effect launching apparatus differs from previous electromagnetic launchers; no need for electromagnet coil on projectile. Result, no need for brush contacts and high-voltage commutation equipment to supply current directly to projectile coil, or for pulse circuitry to induce current in projectile coil if brush contacts not used. Compresses magnetic field surrounding rear surface of projectile, creating gradient of magnetic pressure pushing projectile forward.

  15. On electromagnetic and quantum invisibility

    NASA Astrophysics Data System (ADS)

    Mundru, Pattabhiraju Chowdary

    The principle objective of this dissertation is to investigate the fundamental properties of electromagnetic wave interactions with artificially fabricated materials i.e., metamaterials for application in advanced stealth technology called electromagnetic cloaking. The main goal is to theoretically design a metamaterial shell around an object that completely eliminates the dipolar and higher order multipolar scattering, thus making the object invisible. In this context, we developed a quasi-effective medium theory that determines the optical properties of multi-layered-composites beyond the quasi-static limit. The proposed theory exactly reproduces the far-field scattering/extinction cross sections through an iterative process in which mode-dependent quasi-effective impedances of the composite system are introduced. In the large wavelength limit, our theory is consistent with Maxwell-Garnett formalism. Possible applications in determining the hybridization particle resonances of multi-shell structures and electromagnetic cloaking are identified. This dissertation proposes a multi-shell generic cloaking system. A transparency condition independent of the object's optical and geometrical properties is proposed in the quasi-static regime of operation. The suppression of dipolar scattering is demonstrated in both cylindrically and spherically symmetric systems. A realistic tunable low-loss shell design is proposed based on the composite metal-dielectric shell. The effects due to dissipation and dispersion on the overall scattering cross-section are thoroughly evaluated. It is shown that a strong reduction of scattering by a factor of up to 103 can be achieved across the entire optical spectrum. Full wave numerical simulations for complex shaped particle are performed to validate the analytical theory. The proposed design does not require optical magnetism and is generic in the sense that it is independent of the object's material and geometrical properties. A generic

  16. Electromagnetic Meissner effect launcher

    NASA Technical Reports Server (NTRS)

    Robertson, Glen A. (Inventor)

    1991-01-01

    An electromagnetic projectile launcher provides acceleration of a superconducting projectile through the diamagnetic repulsion of the superconducting projectile. A superconducting layer is provided aft of the projectile, either directly on the projectile or on a platform upon which the projectile is carried, and a traveling magnetic field is caused to propagate along a magnetic field drive coil in which the projectile is disposed. The resulting diamagnetic repulsion between the superconducting projectile and the traveling magnetic field causes the projectile to be propelled along the coil. In one embodiment, a segmented drive coil is used to generate the traveling magnetic field.

  17. Electromagnetic transitions in hypernuclei

    SciTech Connect

    Chrien, R.E.

    1986-01-01

    The object of this review is to survey observations of electromagnetic transitions in hypernuclei and to point out contributions of these observations to an understanding of the effective two-body hyperon-nucleon forces in the nucleus. The discussion concentrates on lambda-hyperon nucleon potentials. Future plans for high resolution hypernuclear spectroscopy using Ge diode detectors is discussed, especially regarding the window of utility of such devices. Expected improvements in beam facilities are also reviewed. 9 refs., 4 figs., 1 tab. (DWL)

  18. Electromagnetic pump stator coil

    DOEpatents

    Fanning, Alan W.; Dahl, Leslie R.

    1996-01-01

    An electrical stator coil for an electromagnetic pump includes a continuous conductor strip having first and second terminals at opposite ends thereof and an intermediate section disposed therebetween. The strip is configured in first and second coil halves, with the first coil half including a plurality of windings extending from the first terminal to the intermediate section, and the second coil half including a plurality of windings extending from the second terminal to the intermediate section. The first and second coil halves are disposed coaxially, and the first and second terminals are disposed radially inwardly therefrom with the intermediate section being disposed radially outwardly therefrom.

  19. Electromagnetic pump stator coil

    DOEpatents

    Fanning, A.W.; Dahl, L.R.

    1996-06-25

    An electrical stator coil for an electromagnetic pump includes a continuous conductor strip having first and second terminals at opposite ends thereof and an intermediate section disposed therebetween. The strip is configured in first and second coil halves, with the first coil half including a plurality of windings extending from the first terminal to the intermediate section, and the second coil half including a plurality of windings extending from the second terminal to the intermediate section. The first and second coil halves are disposed coaxially, and the first and second terminals are disposed radially inwardly therefrom with the intermediate section being disposed radially outwardly therefrom. 9 figs.

  20. The ALICE Electromagnetic Calorimeter

    SciTech Connect

    Awes, Terry C; ALICE, Collaboration

    2010-05-01

    ALICE is the general purpose experiment at the LHC dedicated to the study of heavy-ion collisions. The electromagnetic calorimeter (EMCal) is a late addition to the ALICE suite of detectors with first modules installed in ALICE this year. The EMCal is designed to trigger on high energy gamma-rays and jets, and to enhance the capabilities of ALICE for these measurements. The EMCal is a Pb/scintillator sampling shish-kebab type calorimeter. The EMCal construction, readout, and performance in beam tests at the CERN SPS and PS are described.

  1. The ALICE Electromagnetic Calorimeter

    SciTech Connect

    Awes, Terry C; ALICE, Collaboration

    2010-01-01

    ALICE is the general purpose experiment at the LHC dedicated to the study of heavy-ion collisions. The electromagnetic calorimeter (EMCal) is a late addition to the ALICE suite of detectors with first modules installed in ALICE this year. The EMCal is designed to trigger on high energy gamma-rays and jets, and to enhance the capabilities of ALICE for these measurements. The EMCal is a Pb/scintillator sampling shish-kebab type calorimeter. The EMCal construction, readout, and performance in beam tests at the CERN SPS and PS are described.

  2. Phase characteristics of electromagnetic stirring

    SciTech Connect

    Fujisaki, Keisuke; Ueyama, Takatsugu; Takahashi, Keiichi; Satoh, Shouji

    1997-09-01

    Electromagnetic stirring is used at billet molds as well as at slab mold, to get high quality steel at continuous casting in steel making plant. In order to get the same electromagnetic force in each billet mold and thus the same quality, phase characteristics of electromagnetic stirring is investigated. From the calculation result, it is found that the relative phase at which the difference of the electromagnetic torque in each mold becomes the smallest is 0 or 240 deg. To apply the phase characteristics of the EMS to the quality control, the authors propose the dynamic phase control system by two inverters to get the high quality in the surface crack.

  3. Medium effect on the characteristics of the coupled seismic and electromagnetic signals

    PubMed Central

    HUANG, Qinghua; REN, Hengxin; ZHANG, Dan; CHEN, Y. John

    2015-01-01

    Recently developed numerical simulation technique can simulate the coupled seismic and electromagnetic signals for a double couple point source or a finite fault planar source. Besides the source effect, the simulation results showed that both medium structure and medium property could affect the coupled seismic and electromagnetic signals. The waveform of coupled signals for a layered structure is more complicated than that for a simple uniform structure. Different from the seismic signals, the electromagnetic signals are sensitive to the medium properties such as fluid salinity and fluid viscosity. Therefore, the co-seismic electromagnetic signals may be more informative than seismic signals. PMID:25743062

  4. Electro-magnetic compatibility

    NASA Astrophysics Data System (ADS)

    Maidment, H.

    1980-05-01

    The historical background to the growth in problems of electromagnetic compatibility (EMC) in UK Military aircraft is reviewed and the present approach for minimizing these problems during development is discussed. The importance of using representative aircraft for final EMC assessments is stressed, and the methods of approach in planning and executing such tests are also outlined. The present equipment qualification procedures are based on assumptions regarding the electromagnetic fields present within the airframe, and the nature of the coupling mechanisms. These cannot be measured with any certainty in representative aircraft. Thus EMC assessments rely on practical tests. Avionics systems critical to flight safety, and systems vital to mission effectiveness require test methods that provide a measure of the safety and performance margins available to account for variations that occur in production and service use. Some proven methods are available, notably for detonator circuits, but in most other areas further work is required. Encouraging process has been made in the use of current probes for the measurement of interfering signals on critical signal lines, in conjunction with complementary test house procedures, as a means for obtaining the safety margins required in flight and engine control systems. Performance margins for mission systems using digital techniques are difficult to determine, and there is a need for improved test techniques. The present EMC qualification tests for equipment in the laboratory do not guarantee freedom from interference when installed, and the results are limited in value for correlating with aircraft tests.

  5. Interactions between electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Schwan, H. P.

    1985-02-01

    We applied for this grant to support a workshop at Erice, Italy. This workshop has been commonly called Erice School and the main subject of this workshop is the interaction of electromagnetic fields with biological cells and molecules. The grant from ONR enabled us to invite American scientists to participants in this workshop and deliver scientific papers. The duration of the Erice School was ten days. Therefore, we had sufficient time to discuss the problems of electromagnetic radiations. Vigorous discussions took place during official sessions and during private conversations. The participants of this workshop are mostly those who have been active in the research on bioelectromagnetics, but there are some numbers of speakers who discussed the basic electrical and magnetic properties of polyelectrolytes, biological membranes and tissue. The workshop was unique in that there were participants with a variety of training backgrounds. This enabled us to exchange the information between applied scientists and basic scientists. Also, active exchanges of opinions took place between biological scientists and physical scientists.

  6. Electromagnetic propulsion for spacecraft

    NASA Astrophysics Data System (ADS)

    Myers, Roger M.

    1993-09-01

    Three electromagnetic propulsion technologies, solid propellant pulsed plasma thrusters (PPT), magnetoplasmadynamic (MPD) thrusters, and pulsed inductive thrusters (PIT), were developed for application to auxiliary and primary spacecraft propulsion. Both the PPT and MPD thrusters were flown in space, though only PPT's were used on operational satellites. The performance of operational PPT's is quite poor, providing only approximately 8 percent efficiency at approximately 1000 s specific impulse. However, laboratory PPT's yielding 34 percent efficiency at 2000 s specific impulse were extensively tested, and peak performance levels of 53 percent efficiency at 5170 s specific impulse were demonstrated. MPD thrusters were flown as experiments on the Japanese MS-T4 spacecraft and the Space Shuttle and were qualified for a flight in 1994. The flight MPD thrusters were pulsed, with a peak performance of 22 percent efficiency at 2500 s specific impulse using ammonia propellant. Laboratory MPD thrusters were demonstrated with up to 70 percent efficiency and 700 s specific impulse using lithium propellant. While the PIT thruster has never been flown, recent performance measurements using ammonia and hydrazine propellants are extremely encouraging, reaching 50 percent efficiency for specific impulses between 4000 to 8000 s. The fundamental operating principles, performance measurements, and system level design for the three types of electromagnetic thrusters are reviewed, and available data on flight tests are discussed for the PPT and MPD thrusters.

  7. Electromagnetically Induced Entanglement

    NASA Astrophysics Data System (ADS)

    Yang, Xihua; Xiao, Min

    2015-08-01

    Quantum entanglement provides an essential resource for quantum computation, quantum communication, and quantum network. How to conveniently and efficiently produce entanglement between bright light beams presents a challenging task to build realistic quantum information processing networks. Here, we present an efficient and convenient way to realize a novel quantum phenomenon, named electromagnetically induced entanglement, in the conventional Λ-type three-level atomic system driven by a strong pump field and a relatively weak probe field. Nearly perfect entanglement between the two fields can be achieved with a low coherence decay rate between the two lower levels, high pump-field intensity, and large optical depth of the atomic ensemble. The physical origin is quantum coherence between the lower doublet produced by the pump and probe fields, similar to the well-known electromagnetically induced transparency. This method would greatly facilitate the generation of nondegenerate narrow-band continuous-variable entanglement between bright light beams by using only coherent laser fields, and may find potential and broad applications in realistic quantum information processing.

  8. Electromagnetic propulsion for spacecraft

    NASA Technical Reports Server (NTRS)

    Myers, Roger M.

    1993-01-01

    Three electromagnetic propulsion technologies, solid propellant pulsed plasma thrusters (PPT), magnetoplasmadynamic (MPD) thrusters, and pulsed inductive thrusters (PIT), were developed for application to auxiliary and primary spacecraft propulsion. Both the PPT and MPD thrusters were flown in space, though only PPT's were used on operational satellites. The performance of operational PPT's is quite poor, providing only approximately 8 percent efficiency at approximately 1000 s specific impulse. However, laboratory PPT's yielding 34 percent efficiency at 2000 s specific impulse were extensively tested, and peak performance levels of 53 percent efficiency at 5170 s specific impulse were demonstrated. MPD thrusters were flown as experiments on the Japanese MS-T4 spacecraft and the Space Shuttle and were qualified for a flight in 1994. The flight MPD thrusters were pulsed, with a peak performance of 22 percent efficiency at 2500 s specific impulse using ammonia propellant. Laboratory MPD thrusters were demonstrated with up to 70 percent efficiency and 700 s specific impulse using lithium propellant. While the PIT thruster has never been flown, recent performance measurements using ammonia and hydrazine propellants are extremely encouraging, reaching 50 percent efficiency for specific impulses between 4000 to 8000 s. The fundamental operating principles, performance measurements, and system level design for the three types of electromagnetic thrusters are reviewed, and available data on flight tests are discussed for the PPT and MPD thrusters.

  9. Electromagnetically Induced Entanglement.

    PubMed

    Yang, Xihua; Xiao, Min

    2015-01-01

    Quantum entanglement provides an essential resource for quantum computation, quantum communication, and quantum network. How to conveniently and efficiently produce entanglement between bright light beams presents a challenging task to build realistic quantum information processing networks. Here, we present an efficient and convenient way to realize a novel quantum phenomenon, named electromagnetically induced entanglement, in the conventional Λ-type three-level atomic system driven by a strong pump field and a relatively weak probe field. Nearly perfect entanglement between the two fields can be achieved with a low coherence decay rate between the two lower levels, high pump-field intensity, and large optical depth of the atomic ensemble. The physical origin is quantum coherence between the lower doublet produced by the pump and probe fields, similar to the well-known electromagnetically induced transparency. This method would greatly facilitate the generation of nondegenerate narrow-band continuous-variable entanglement between bright light beams by using only coherent laser fields, and may find potential and broad applications in realistic quantum information processing. PMID:26314514

  10. Electromagnetic Field Penetration Studies

    NASA Technical Reports Server (NTRS)

    Deshpande, M.D.

    2000-01-01

    A numerical method is presented to determine electromagnetic shielding effectiveness of rectangular enclosure with apertures on its wall used for input and output connections, control panels, visual-access windows, ventilation panels, etc. Expressing EM fields in terms of cavity Green's function inside the enclosure and the free space Green's function outside the enclosure, integral equations with aperture tangential electric fields as unknown variables are obtained by enforcing the continuity of tangential electric and magnetic fields across the apertures. Using the Method of Moments, the integral equations are solved for unknown aperture fields. From these aperture fields, the EM field inside a rectangular enclosure due to external electromagnetic sources are determined. Numerical results on electric field shielding of a rectangular cavity with a thin rectangular slot obtained using the present method are compared with the results obtained using simple transmission line technique for code validation. The present technique is applied to determine field penetration inside a Boeing-757 by approximating its passenger cabin as a rectangular cavity filled with a homogeneous medium and its passenger windows by rectangular apertures. Preliminary results for, two windows, one on each side of fuselage were considered. Numerical results for Boeing-757 at frequencies 26 MHz, 171-175 MHz, and 428-432 MHz are presented.

  11. Interpreting marine controlled source electromagnetic field behaviour with streamlines

    NASA Astrophysics Data System (ADS)

    Pethick, A. M.; Harris, B. D.

    2013-10-01

    Streamlines represent particle motion within a vector field as a single line structure and have been used in many areas of geophysics. We extend the concept of streamlines to interactive three dimensional representations of the coupled vector fields generated during marine controlled source electromagnetic surveys. These vector fields have measurable amplitudes throughout many hundreds of cubic kilometres. Electromagnetic streamline representation makes electromagnetic interactions within complex geo-electrical setting comprehensible. We develop an interface to rapidly compute and interactively visualise the electric and magnetic fields as streamlines for 3D marine controlled source electromagnetic surveys. Several examples highlighting how interactive use has value in marine controlled source electromagnetic survey design, interpretation and teaching are provided. The first videos of electric, magnetic and Poynting vector field streamlines are provided along with the first published example of the airwave represented as streamlines. We demonstrate that the electric field airwave is a circulating vortex moving down and out from the air-water interface towards the ocean floor. The use of interactive streamlines is not limited to marine controlled source electromagnetic methods. Streamlines provides a high level visualisation tool for interpreting the electric and magnetic field behaviour generated by a wide range of electromagnetic survey configurations for complex 3D geo-electrical settings.

  12. The compact electromagnetic device optimization modeling of seismo-electromagnetic processes for the Earth

    NASA Astrophysics Data System (ADS)

    Sengor, T.

    2009-04-01

    The electromagnetically equivalent device model [1]-[2] is extended as considering the whole Earth like a complete system in this paper. The crustal structures are considered as a complex network of distributed circuits involving slot antenna arrays, open waveguides, cavities, transmission strip lines, attenuators, frequency converters, dividers, couplings in the electromagnetically equivalent device model of the complete system of Earth (EEDMCSE). The variations at the geo-data taken at any port of the EEDMCSE give some functional relationships on the electromagnetic characteristics of the distributed complex network explained above. The mappings said here are based on the transformations among both the temporal and the spatial variations of both geo-data and the electromagnetic characteristics of the distributed complex network [2]. The Finite Difference Time Domain Method is used at the evaluations. The temporal variations at the mappings of EEDMCSE at specific locations extract the mechanisms explaining the relationships among the characteristics of the distributed complex network and seismic phenomena of Earth in the future. A mapping is established between the parameter space of the geo-data and the characteristics of the electromagnetically equivalent device model. The temporal variations of the geo-data are correlated to the self-optimizing the specific characteristics of the electromagnetically equivalent device. The relationships said here give a possibility of predicting the geo-data. Using the inverses of the mappings generates the evaluations giving the predictability conditions involving restrictions. The inversion of the mapping exploits a fine model at predicting the natural iterations of the geo-data at future on both the region connected the port and some locations non-related to the port either geologically or seismically or phenomenologically relating to the earth [1] - [5]. 2 References [1] T. Sengor,"The electromagnetic device optimization

  13. Electromagnetic direct implicit PIC simulation

    SciTech Connect

    Langdon, A.B.

    1983-03-29

    Interesting modelling of intense electron flow has been done with implicit particle-in-cell simulation codes. In this report, the direct implicit PIC simulation approach is applied to simulations that include full electromagnetic fields. The resulting algorithm offers advantages relative to moment implicit electromagnetic algorithms and may help in our quest for robust and simpler implicit codes.

  14. Transmitting Electromagnetic Energy into Liquids

    NASA Technical Reports Server (NTRS)

    Johnston, E. J.

    1984-01-01

    Rough liquid surface enhances coupling. Agitating surface of liquid nitrogen bath with periodic or aperiodic excitation enhances electromagnetic coupling between microwave horn and blackbody temperature standard immersed in liquid. Useful in interfaces between electromagnetic radiation and liquids. Biomedical, radar, and meteorological applications.

  15. Exploration of the Electromagnetic Environment

    ERIC Educational Resources Information Center

    Fullekrug, M.

    2009-01-01

    The electromagnetic environment is composed of electric and magnetic fields which result from man-made and natural sources. An elementary experiment is described to explore the electromagnetic environment by measuring electric fields in the frequency range from approximately equal to 10 to 24 000 Hz. The equipment required to conduct the…

  16. Electromagnetic scattering theory

    NASA Technical Reports Server (NTRS)

    Bird, J. F.; Farrell, R. A.

    1986-01-01

    Electromagnetic scattering theory is discussed with emphasis on the general stochastic variational principle (SVP) and its applications. The stochastic version of the Schwinger-type variational principle is presented, and explicit expressions for its integrals are considered. Results are summarized for scalar wave scattering from a classic rough-surface model and for vector wave scattering from a random dielectric-body model. Also considered are the selection of trial functions and the variational improvement of the Kirchhoff short-wave approximation appropriate to large size-parameters. Other applications of vector field theory discussed include a general vision theory and the analysis of hydromagnetism induced by ocean motion across the geomagnetic field. Levitational force-torque in the magnetic suspension of the disturbance compensation system (DISCOS), now deployed in NOVA satellites, is also analyzed using the developed theory.

  17. Electromagnetic propulsion for spacecraft

    NASA Technical Reports Server (NTRS)

    Myers, Roger M.

    1993-01-01

    Three electromagnetic propulsion technologies, solid propellant pulsed plasma thrusters (PPT), magnetoplasmadynamic (MPD) thrusters, and pulsed inductive thrusters (PIT) have been developed for application to auxiliary and primary spacecraft propulsion. Both the PPT and MPD thrusters have been flown in space, though only PPTs have been used on operational satellites. The performance of operational PPTs is quite poor, providing only about 8 percent efficiency at about 1000 sec specific impulse. Laboratory PPTs yielding 34 percent efficiency at 5170 sec specific impulse have been demonstrated. Laboratory MPD thrusters have been demonstrated with up to 70 percent efficiency and 7000 sec specific impulse. Recent PIT performance measurements using ammonia and hydrazine propellants are extremely encouraging, reaching 50 percent efficiency for specific impulses between 4000 and 8000 sec.

  18. Causal electromagnetic interaction equations

    SciTech Connect

    Zinoviev, Yury M.

    2011-02-15

    For the electromagnetic interaction of two particles the relativistic causal quantum mechanics equations are proposed. These equations are solved for the case when the second particle moves freely. The initial wave functions are supposed to be smooth and rapidly decreasing at the infinity. This condition is important for the convergence of the integrals similar to the integrals of quantum electrodynamics. We also consider the singular initial wave functions in the particular case when the second particle mass is equal to zero. The discrete energy spectrum of the first particle wave function is defined by the initial wave function of the free-moving second particle. Choosing the initial wave functions of the free-moving second particle it is possible to obtain a practically arbitrary discrete energy spectrum.

  19. Computational electronics and electromagnetics

    SciTech Connect

    Shang, C. C.

    1997-02-01

    The Computational Electronics and Electromagnetics thrust area at Lawrence Livermore National Laboratory serves as the focal point for engineering R&D activities for developing computer-based design, analysis, and tools for theory. Key representative applications include design of particle accelerator cells and beamline components; engineering analysis and design of high-power components, photonics, and optoelectronics circuit design; EMI susceptibility analysis; and antenna synthesis. The FY-96 technology-base effort focused code development on (1) accelerator design codes; (2) 3-D massively parallel, object-oriented time-domain EM codes; (3) material models; (4) coupling and application of engineering tools for analysis and design of high-power components; (5) 3-D spectral-domain CEM tools; and (6) enhancement of laser drilling codes. Joint efforts with the Power Conversion Technologies thrust area include development of antenna systems for compact, high-performance radar, in addition to novel, compact Marx generators. 18 refs., 25 figs., 1 tab.

  20. Electromagnetic nucleon form factors

    SciTech Connect

    Bender, A.; Roberts, C.D.; Frank, M.R.

    1995-08-01

    The Dyson-Schwinger equation framework is employed to obtain expressions for the electromagnetic nucleon form factor. In generalized impulse approximation the form factor depends on the dressed quark propagator, the dressed quark-photon vertex, which is crucial to ensuring current conservation, and the nucleon Faddeev amplitude. The approach manifestly incorporates the large space-like-q{sup 2} renormalization group properties of QCD and allows a realistic extrapolation to small space-like-q{sup 2}. This extrapolation allows one to relate experimental data to the form of the quark-quark interaction at small space-like-q{sup 2}, which is presently unknown. The approach provides a means of unifying, within a single framework, the treatment of the perturbative and nonperturbative regimes of QCD. The wealth of experimental nucleon form factor data, over a large range of q{sup 2}, ensures that this application will provide an excellent environment to test, improve and extend our approach.