Sample records for displacement field due

  1. Time-dependent displacement and stress fields due to shear and tensile faults in a transversely isotropic viscoelastic half-space

    NASA Astrophysics Data System (ADS)

    Molavi Tabrizi, Amirhossein; Pan, Ernian

    2015-07-01

    Viscoelastic behaviour of materials in nature is observed in post-event deformations due to seismic or volcanic activities. In this paper, by adopting the correspondence principle, we propose an inelastic model to predict first the Laplace-domain response of a transversely isotropic viscoelastic half-space due to a shear or tensile fault of polygonal shape. The displacement and stress fields in the time domain are then obtained using an efficient and accurate algorithm for the inverse Laplace transform. Numerical examples are presented to validate the proposed solution and to show the viscoelastic displacement and stress fields due to a strike-slip, dip-slip and tensile fault of rectangular shape. The obtained results indicate that both viscoelasticity and transverse isotropy play significant roles in the viscoelastic response of the half-space due to faults, which could be used as benchmarks for the future numerical analysis of realistic post-seismic or volcanic event.

  2. Crustal displacements due to continental water loading

    USGS Publications Warehouse

    Van Dam, T.; Wahr, J.; Milly, P.C.D.; Shmakin, A.B.; Blewitt, G.; Lavallee, D.; Larson, K.M.

    2001-01-01

    The effects of long-wavelength (> 100 km), seasonal variability in continental water storage on vertical crustal motions are assessed. The modeled vertical displacements (??rM) have root-mean-square (RMS) values for 1994-1998 as large as 8 mm, with ranges up to 30 mm, and are predominantly annual in character. Regional strains are on the order of 20 nanostrain for tilt and 5 nanostrain for horizontal deformation. We compare ??rM with observed Global Positioning System (GPS) heights (??rO) (which include adjustments to remove estimated effects of atmospheric pressure and annual tidal and non-tidal ocean loading) for 147 globally distributed sites. When the ??rO time series are adjusted by ??rM, their variances are reduced, on average, by an amount equal to the variance of the ??rM. Of the ??rO time series exhibiting a strong annual signal, more than half are found to have an annual harmonic that is in phase and of comparable amplitude with the annual harmonic in the ??rM. The ??rM time series exhibit long-period variations that could be mistaken for secular tectonic trends or post-glacial rebound when observed over a time span of a few years.

  3. Relativistic Lagrangian displacement field and tensor perturbations

    E-print Network

    Cornelius Rampf; Alexander Wiegand

    2014-12-14

    We investigate the purely spatial Lagrangian coordinate transformation from the Lagrangian to the basic Eulerian frame. We demonstrate three techniques for extracting the relativistic displacement field from a given solution in the Lagrangian frame. These techniques are (a) from defining a local set of Eulerian coordinates embedded into the Lagrangian frame; (b) from performing a specific gauge transformation; and (c) from a fully non-perturbative approach based on the ADM split. The latter approach shows that this decomposition is not tied to a specific perturbative formulation for the solution of the Einstein equations. Rather, it can be defined at the level of the non-perturbative coordinate change from the Lagrangian to the Eulerian description. Studying such different techniques is useful because it allows us to compare and develop further the various approximation techniques available in the Lagrangian formulation. We find that one has to solve the gravitational wave equation in the relativistic analysis, otherwise the corresponding Newtonian limit will necessarily contain spurious non-propagating tensor artefacts at second order in the Eulerian frame. We also derive the magnetic part of the Weyl tensor in the Lagrangian frame, and find that it is not only excited by gravitational waves but also by tensor perturbations which are induced through the non-linear frame-dragging. We apply our findings to calculate for the first time the relativistic displacement field, up to second order, for a $\\Lambda$CDM Universe in the presence of a local primordial non-Gaussian component. Finally, we also comment on recent claims about whether mass conservation in the Lagrangian frame is violated.

  4. On the displacement of asteroid photocentre due to surface scattering

    NASA Astrophysics Data System (ADS)

    Tungalag, N.; Shevchenko, V. G.; Lupishko, D. F.

    2000-12-01

    The numerical modelling of asteroid brightness distribution for different scattering laws (Lambert, Lommel-Seeliger, Hapke, theoretical and empirical Akimov laws) was carried out for the purpose of determination of asteroid photocentre position. A numerical photometric model of an asteroid which considers the arbitrary i) asteroid shape, ii) albedo distribution on the surface, and iii) scattering law was used. It is shown that the photocentre displacement depends essentially on the asteroid shape, phase angle, and light scattering. The displacement may reach a value of (0.3-0.4)R, where R is asteroid's angular radius. Such displacements exceed the accuracy of space-based astrometric measurements, and they are comparable with the accuracy of ground-based observations. Therefore, the accuracy of asteroid position determinations can be noticeably improved when they are taken into account. Some practical recommendations on the determination of asteroid photocentre displacements are given.

  5. Articular disk displacement of TMJ due to trauma.

    PubMed

    Goddard, G

    1993-07-01

    One hundred and thirty native American Indian patients undergoing orthodontic treatment for malocclusions were screened for temporomandibular joint (TMJ) abnormalities. These patients were followed over the course of orthodontic treatment and six of these patients suffered a traumatic injury to the TMJ. These six patients who had been previously screened and found to be asymptomatic, developed symptoms. Three were diagnosed with articular disk displacement of the TMJ confirmed by magnetic resonance imaging (MRI). PMID:8242786

  6. Characterization of damaged composite laminates by an optical measurement of the displacement field

    NASA Astrophysics Data System (ADS)

    Loukil, M. S.; Varna, J.; Ayadi, Z.

    2012-02-01

    The degradation of the elastic properties of composite laminates with intralaminar cracks is caused by reduced stress in the damaged layer which is mainly due to two parameters: the crack opening displacement (COD) and the crack sliding displacement (CSD). In this paper these parameters are measured experimentally providing laminate stiffness reduction models with valuable information for validation of used assumptions and for defining limits of their application. In particular, the displacement field on the edges of a [0/ +704/ -704]s glass fiber/epoxy laminate specimens with multiple intralaminar cracks is studied and the COD and CSD dependence on the applied mechanical load is measured. The specimen full-field displacement measurement is carried out using ESPI (Electronic Speckle Pattern Interferometry). By studying the displacement discontinuities, the crack face displacements were measured. A comparison between the COD and the CSD (for the same crack) is performed.

  7. Microscopic 3-D displacement field measurements using digital speckle photography

    Microsoft Academic Search

    Linda Larsson; Mikael Sjödahl; Fredrik Thuvander

    2004-01-01

    A technique to measure object shape and 3-D displacement fields in micro-scale is offered by microscopic stereo digital speckle photography. The displacement of the random features that are often present on many engineering surfaces when viewed in a microscope is measured with the system, using image correlation. In this paper the equipment, physical model and calibration routines are described. The

  8. Conditional displacement operator for traveling fields

    NASA Astrophysics Data System (ADS)

    Souza, Simone; Avelar, A. T.; Malbouisson, J. M. C.; Baseia, B.

    2008-05-01

    We show that the conditional displacement operator U=exp[bbˆ(?a-??aˆ)] acting upon arbitrary states of traveling waves can be well approximated by the action of a Kerr-medium placed between two beam splitters whose respective second ports are fed by highly excited coherent states. The scheme is deterministic, since it does not employ any detection event. Applications for generation of nonclassical states and measurement of Wigner function of arbitrary states are also considered.

  9. Tsunami generation by dynamic displacement of sea bed due to dip-slip faulting

    E-print Network

    Paris-Sud XI, Université de

    Tsunami generation by dynamic displacement of sea bed due to dip-slip faulting Denys Dutykh, Fr In classical tsunami-generation techniques, one neglects the dynamic sea bed dis- placement resulting from and the NSWE by a finite-volume scheme. A comparison be- tween static and dynamic tsunami-generation approaches

  10. Optimization of legacy lidar data sets for measuring near-field earthquake displacements

    NASA Astrophysics Data System (ADS)

    Glennie, Craig L.; Hinojosa-Corona, Alejandro; Nissen, Edwin; Kusari, Arpan; Oskin, Michael E.; Arrowsmith, J. Ramon; Borsa, Adrian

    2014-05-01

    Airborne lidar (light detection and ranging) topography, acquired before and after an earthquake, can provide an estimate of the coseismic surface displacement field by differencing the preevent and postevent lidar point clouds. However, estimated displacements can be contaminated by the presence of large systematic errors in either of the point clouds. We present three-dimensional displacements obtained by differencing airborne lidar point clouds collected before and after the El Mayor-Cucapah earthquake, a Mw 7.2 earthquake that occurred in 2010. The original surface displacement estimates contained large, periodic artifacts caused by systematic errors in the preevent lidar data. Reprocessing the preevent data, detailed herein, removed a majority of these systematic errors that were largely due to misalignment between the scanning mirror and the outgoing laser beam. The methodology presented can be applied to other legacy airborne laser scanning data sets in order to improve change estimates from temporally spaced lidar acquisitions.

  11. A semi-empirical model for the estimation of maximum horizontal displacement due to liquefaction-induced lateral spreading

    USGS Publications Warehouse

    Faris, Allison T.; Seed, Raymond B.; Kayen, Robert E.; Wu, Jiaer

    2006-01-01

    During the 1906 San Francisco Earthquake, liquefaction-induced lateral spreading and resultant ground displacements damaged bridges, buried utilities, and lifelines, conventional structures, and other developed works. This paper presents an improved engineering tool for the prediction of maximum displacement due to liquefaction-induced lateral spreading. A semi-empirical approach is employed, combining mechanistic understanding and data from laboratory testing with data and lessons from full-scale earthquake field case histories. The principle of strain potential index, based primary on correlation of cyclic simple shear laboratory testing results with in-situ Standard Penetration Test (SPT) results, is used as an index to characterized the deformation potential of soils after they liquefy. A Bayesian probabilistic approach is adopted for development of the final predictive model, in order to take fullest advantage of the data available and to deal with the inherent uncertainties intrinstiic to the back-analyses of field case histories. A case history from the 1906 San Francisco Earthquake is utilized to demonstrate the ability of the resultant semi-empirical model to estimate maximum horizontal displacement due to liquefaction-induced lateral spreading.

  12. Apparent spatial blurring and displacement of a point optical source due to cloud scattering

    SciTech Connect

    Brower, K.L.

    1997-09-01

    A Monte Carlo algorithm is used to determine the apparent spatial blurring of a terrestrial 1.07 micron optical point source due to cloud scattering as seen from space. The virtual image of a point source over a virtual source plane area 22.4 x 22.4 square kilometers arising from cloud scattering was determined for stratus clouds (NASA cloud number 5) and altostratus clouds optical source arises from photon scattering by cloud water droplets. Displacement of the virtual source is due to the apparent illumination of the cloud top region directly about the actual source which when viewed at a nonzero look angle gives a projected displacement of the apparent source relative to the actual source. These features are quantified by an analysis of the Monte Carlo computational results.

  13. Recorded displacements in a landslide slope due to regional and teleseismic earthquakes

    NASA Astrophysics Data System (ADS)

    Lenti, L.; Martino, S.; Paciello, A.; Prestininzi, A.; Rivellino, S.

    2015-06-01

    Regional and teleseismic earthquakes can induce displacements along joints in a landslide-involved rocky slope in Central Italy. The rarity of these effects is due to specific physical properties of the seismic signals associated with: (i) the energy content, (ii) the distribution of relative energy and peak of ground acceleration related to the ground motion components and (iii) the spectral amplitude distribution in the frequency domain; these properties allow the triggering earthquakes to be distinguished from the others. The observed effects are relevant when compared to the direction of the landslide movement and the dimensions of the involved rock mass volume. The landslide movement is less constrained in the direction parallel to the dip of the slope and the landslide dimensions are associated with characteristic periods that control the landslide deformational response in relation to the spectral content of the ground motion. The earthquake-induced displacements are significant because they have the same order of magnitude as the average annual cumulative displacement based on a decade of strain measurements within the slope.

  14. Local thermal discomfort due to draft and vertical temperature difference in rooms with displacement ventilation

    SciTech Connect

    Melikov, A.K. (Lab. of Heating and Air Conditioning, Technical Univ. of Denmark, Lyngby (DK)); Nielsen, J.B. (Danish Building Research Inst., Indoor Climate Div., Hoersholm (DK))

    1989-01-01

    The paper evaluates the thermal comfort conditions in 18 spaces in practice ventilated by the displacement ventilation principle recently developed in Scandinavia. The risk of local discomfort due to draft and vertical temperature difference is estimated by comprehensive measurement of mean velocity, turbulence intensity, and air temperature. The results indicate a high risk of draft and vertical temperature difference in the occupied zone of some of the spaces. The draft risk and vertical temperature difference varied substantially within the occupied zone. They may create serious complaints in the half of the occupied zone nearest to the outlets. In several cases there was a potential risk of combined discomfort due to draft and vertical temperature difference. This combined discomfort should be studied by subjective experiments.

  15. Displacements due to surface temperature variation on a uniform elastic sphere with its centre of mass stationary

    NASA Astrophysics Data System (ADS)

    Fang, Ming; Dong, Danan; Hager, Bradford H.

    2014-01-01

    We investigate the displacement field induced by temperature variation within a spherical thermal boundary layer under an Earth-like condition of surface heating by deriving analytical solutions on a uniform elastic sphere under the constraint that its centre of mass remains stationary in space. Similar to strain solutions, our displacement solution consists of spectra of two distinctive modes: an exponential mode relating to the thermal body force and a power-law mode relating to the (equivalent) thermal surface loading. The exponential modes of the thermal body force in our solution turn out to be identical to that in a classic half-space solution, while the effect of thermal loading by the power-law modes in our spherical solution is different from the exponential modes of thermal loading in the half-space solution. The thermal surface loading is found, by analytical and numerical analyses, equally important in order of magnitude as the thermal body force in producing the radial displacement at the surface throughout the entire harmonic spectrum. The transverse displacement arises mainly from the power-law modes of thermal surface loading. Numerical simulations, based on NASA's space-borne observation of the global land surface temperature (ocean is masked out), have shown unique patterns in the annual variation of the global displacement field that fits the climatological and geographical settings. The predicted amplitude of the thermally induced surface deformation in global scale is at the millimetre level with the largest ˜2 mm for radial displacement and ˜1 mm for transverse displacement. Comparative analysis shows that the radial displacement field is asymptotically proportional to the surface temperature distribution, which justifies the use of the half-space solution as a good approximation for modelling the global radial displacement. The transverse displacement obtained by patched half-space solution fails to capture the long-range transverse variations on a spherical surface, and thus, is inadequate for modelling and synthesizing the global transverse displacement.

  16. Investigations on the development of a mixed displacement-pressure formulation for an anelastic displacement-field finite element

    NASA Astrophysics Data System (ADS)

    Rusovici, Razvan

    2006-03-01

    Space and weapon delivery systems contain guidance components and payload that need to be protected from the extremely harsh acoustic excitation present during launch operations. The above example represents just one application where high-damping viscoelastic materials are used in the design of shock and vibration isolation components. The shock transients generally encountered are characterized by a broad frequency spectrum. Widely available finite element codes do not offer the proper tools to model the frequency- dependent mechanical properties of viscoelastic materials over the frequency domain of interest. An added difficulty is the large Poissson's ratio exhibited by some of these materials, which indicates that previously developed displacement-based finite element formulations should be complemented with mixed pressure-displacement finite element formulations. A pure displacement-based finite element generally predicts the displacements well, if the mesh used is fine enough, but the same thing may not be said about the values of the predicted stresses. The Anelastic Displacement Fields (ADF) method is employed herein to model frequency-dependence of material properties within a time-domain finite element framework and using a mixed displacement-pressure finite element formulation. Finite elements based on this new formulation are developed.

  17. Displacement field of a screw dislocation in a <011> Cu nanowire: An atomistic study

    NASA Astrophysics Data System (ADS)

    Gailhanou, Marc; Roussel, Jean-Marc

    2013-12-01

    By performing atomistic calculations with a tight-binding potential, we study the displacement field induced by a screw dislocation lying along a free <011> Cu cylindrical nanowire. For this anisotropic orientation that is often encountered experimentally, we show that the displacement field uz along the nanowire can be seen as the superposition of three different fields: the screw dislocation field in an infinite medium, the warping displacement field caused by the so-called Eshelby twist, and an additional image field induced by the free surfaces. A Fourier series analysis of this latter image displacement and stress fields is given. For a circular cross section of the wire, this image field corresponds mainly to an additional warping displacement uz?xy. The dissociation mechanism of the dislocation into partials and the surface stress effects being also captured in our simulations, the present study enables one to quantify the various contributions to the formation of the x-ray diffractograms.

  18. Characterization and Quantification of HITU Fields with a Fiber-optic Displacement Sensor

    NASA Astrophysics Data System (ADS)

    Haller, Julian; Jenderka, Klaus-Vitold; Wilkens, Volker; Koch, Christian

    2011-09-01

    The characterization and quantification of High Intensity Therapeutic Ultrasound (HITU) fields is a difficult challenge, as appropriate sensors need to withstand very high local intensities in small focal regions and to measure them with a high reliability. Due to their high robustness and their small dimensions, fiber-optic probes have proven to be a promising approach for this purpose. In this paper, a fiber-optic displacement sensor and an interferometric optical set-up are presented and the potential as well as the limitations of this set-up are discussed.

  19. Determining horizontal displacement and strains due to subsidence. Rept. of Investigations/1991

    SciTech Connect

    Tandanand, S.; Powell, L.R.

    1991-01-01

    Horizontal displacements and ground strains induced by mine subsidence are significant information needed for calculating damage and developing precautions against subsidence effects on surface structures. To devise a simple method for determining the surface horizontal displacements and strains simultaneously with the subsidence prediction, the U.S. Bureau of Mines examined the significance of the tilt number, which is the proportionality constant in the relationship between the horizontal displacement and the slope of the subsidence profile. The ratio of the tilt number to the critical radius of the subsidence trough is identical to the ratio of the maximum possible horizontal displacement to the full subsidence, which is found to be constant in most European coalfields. If this ratio is known for a particular minesite in the United States, then horizontal displacement and ground strains can be readily obtained from the primary subsidence data.

  20. A stereoscopic digital speckle photography system for 3-D displacement field measurements

    Microsoft Academic Search

    Per Synnergren; Mikael Sjödahl

    1999-01-01

    Stereoscopic digital speckle photography offers a technique to measure object shapes and 3-D displacement fields in experimental mechanics. The system measures the displacement of a random white light speckle pattern, which somehow is present on the object surface, using digital correlation. This paper describes a general physical model for stereo imaging systems. A camera calibration algorithm, which takes the distortion

  1. A reference material for establishing uncertainties in full-field displacement measurements

    NASA Astrophysics Data System (ADS)

    Hack, E.; Lin, X.; Patterson, E. A.; Sebastian, C. M.

    2015-07-01

    A simple reference material for establishing the minimum measurement uncertainty of optical systems for measuring 3D surface displacement fields in deforming objects is described and its use demonstrated by employing 3D digital image correlation as an exemplar technique. The reference material consists of a stepped bar, whose dimensions can be scaled to suit the application, and that can be clamped rigidly at its thick end to create an idealized cantilever. The cantilever was excited at resonance to generate out-of-plane displacements and, in a separate experiment, loaded statically in-plane to provide in-plane displacement fields. The displacements were measured using 3D digital image correlation and compared to the predicted displacement fields derived from tip deflections obtained using a calibrated transducer that provided traceability to the national standard for length. The minimum measurement uncertainties were evaluated by comparing the measured and predicted displacement fields, taking account of the uncertainties in the input parameters for the predictions. It was found that the minimum measurement uncertainties were less than 3% for the Cartesian components of displacement present during static in-plane bending and less than 3?µm for out-of-plane displacements during dynamic loading. It was concluded that this reference material was more straightforward to use, more versatile and yielded comparable results relative to an earlier design.

  2. Measurement of Along-track Displacements due to the M6.0 August 24, 2014 South Napa Earthquake Using X-band Multiple-Aperture SAR Interferometry

    NASA Astrophysics Data System (ADS)

    Jung, H. S.; Jo, M. J.; Yun, S. H.; Jung, H. I.; Koh, Y. C.; Webb, F.

    2014-12-01

    Multiple-aperture SAR interferometry (MAI) has been developed for measuring surface displacements in along-track direction as an alternative method of amplitude offset tracking method. Various studies on geological phenomena have been carried out using MAI technique with C-band and L-band SAR data, but application of MAI to X-band SAR is challenging due to its more severe temporal decorrelation compared to longer wavelength radar. The Italian Space Agency's (ASI) COSMO-SkyMed (CSK) mission consisting of four identical radar satellites has a powerful capability to minimize temporal baselines maintaining high coherence. This offers a good chance for MAI application for precise measurement of along-track displacements. In this study, we demonstrate the MAI performance of X-band SAR for the M6.0, South Napa Earthquake occurred on August 24, 2014. A coseismic CSK pair data (July 26 and August 27, 2014) acquired from descending orbit was used to show the along-track displacements in the fault zone. In order to evaluate the precision for measuring MAI deformation on the Napa Earthquake using CSK data, we produced a coherence map of the interferogram because the MAI precision is a function of interferometric coherence. However, we found that standard deviation of MAI phase does not coincide with the theoretical variation. The measurement uncertainty of along-track displacements was estimated by using the predefined empirical equation which was established through the performance test using multi-path CSK dataset at Kilauea Volcano region. The uncertainty map of the along-track displacements in the South Napa Earthquake region provides a reliable metric to estimate the variance/covariance of the data, useful for 3-D displacement field construction and geophysical modeling.

  3. Field methods to measure surface displacement and strain with the Video Image Correlation method

    NASA Technical Reports Server (NTRS)

    Maddux, Gary A.; Horton, Charles M.; Mcneill, Stephen R.; Lansing, Matthew D.

    1994-01-01

    The objective of this project was to develop methods and application procedures to measure displacement and strain fields during the structural testing of aerospace components using paint speckle in conjunction with the Video Image Correlation (VIC) system.

  4. The displacement field characterization of two interacting parallel edge cracks in a finite body 

    E-print Network

    Keener, Todd Whitney

    1996-01-01

    The goals of this research were to: (1) develop a model to represent the displacement field surrounding two interacting, parallel edge cracks; and (2) use this model to investigate the influence of crack separation and relative crack length...

  5. Mathematical model for regional land subsidence due to pumping: 2. Integrated aquifer subsidence equations for vertical and horizontal displacements

    NASA Astrophysics Data System (ADS)

    Bear, Jacob; Corapcioglu, M. Yavuz

    1981-08-01

    A mathematical model for regional subsidence due to pumping from an aquifer is developed on the basis of Biot's work on coupled three-dimensional consolidation. Following Biot's work on threedimensional consolidation, with coupling between mass conservation and equilibrium equations, a mathematical model for regional subsidence due to pumping from an aquifer is developed by averaging the three-dimensional model over the thickness of the aquifer and assuming conditions of plane stress. Both (vertical) land subsidence and horizontal displacements, as functions of plane coordinates and time, can be estimated by solving the model equations for a given confined or leaky confined aquifer. An analytical solution is presented for the special case of a single well pumping from an infinite homogeneous isotropic aquifer. The solution provides estimates of changes in averaged (over the vertical) values of piezometric head, vertical subsidence, and horizontal displacement. The results indicate that under the conditions of the studied case of radial flow the solution for piezometric head is identical to the one obtained by noncoupled models. Furthermore, half the volume strain is produced by vertical subsidence while the other half by the horizontal displacement. Hence the vertical subsidence is only approximately half the value obtained in noncoupled models which neglect horizontal displacement. A numerical example demonstrates these conclusions.

  6. Maxwell-displacement-current across phospholipid monolayers due to phase transition

    NASA Astrophysics Data System (ADS)

    Iwamoto, Mitsumasa; Kubota, Tohru; Zhong-can, Ou-Yang

    1996-01-01

    With Maxwell-displacement-current-measuring method, the phase transitions of phospholipid monolayers of L-?-dilaurylphosphatidylethanolamine (DLPE) and L-?-dimyristoyl- phosphatidylethanolamine (DMPE) on a water surface were detected. Some fine features, such as the first order phase transition from gaseous to the polar ordering phase and the polar ordering of lipid molecules in the solid phase coexisting with fluid, were revealed for the first time.

  7. Vertical displacement of the storage ring floor due to building distortion in the Photon Factory

    NASA Astrophysics Data System (ADS)

    Katsura, Tomotaro; Fujita, Yutaka

    1991-11-01

    The Light Source Building of the Photon Factory was found to distort so much as to induce the displacement of magnets in the storage ring. This resulted in drifting of the beam orbit. It was considered that the building was distorted by the variations of thermal stress, such as diurnal changes of the solar irradiation and atmospheric temperature. To reduce such thermal stress, the rooftop of the building was insulated with a layer of polyethylene foam. The building distortion was measured in terms of vertical floor displacements along the storage ring by using a hydrostatic level measuring system. Results of the measurement were compared with those of a model simulation based on the finite element method. Comparison between measured and simulated results showed good agreement before the insulation applied to the roof. After the insulation, the measured floor displacements reduced to about one half and were also comparable to the simulated results. A full description of the subject is given in T. Katsura, Ed., KEK Internal 90-32 (in Japanese) Jan. (1991).

  8. Far-field surface displacements resulting from magma-chamber failure and caldera formation

    NASA Astrophysics Data System (ADS)

    Browning, John; Gudmundsson, Agust

    2015-04-01

    On certain rare occasions, the physical processes in a volcano encourage chamber-roof failure and vertical collapse along bounding ring-faults. The conditions which lead to caldera forming collapse are still poorly constrained. As there have only been four, possibly five well documented caldera forming events, the geodetic signals produced from chamber failure and collapse are not well understood. We present results from numerical models designed to simulate the failure and subsidence of a magma chamber roof. Our aim is to present the resultant surface deformation expected from such collapse events. All shallow magma chambers reside in crustal segments which to a first approximation can be considered to behave as a linear elastic material. The crustal response due to deflation and inflation cycles at caldera volcanoes is often considered using a point-pressure (Mogi) source; however, such models are not suitable for constraining magma chamber failure and collapse volumes. We consider roof displacement for a number of magma chamber depths, geometries, and sizes using the numerical Finite Element software, COMSOL. In addition, we investigate the role of crustal heterogeneities and anisotropies, as well as the surface cover (such as an ice sheet) on the results obtained. Initial models indicate significant vertical displacement (> 0.5 m), several tens of kilometres from the collapse area. Results are significantly affected by the mechanical properties of the host rock, the magma chamber geometry, and the collapse volume (the volume of the subsidence). The models can be used to estimate the amount of vertical and horizontal far-field surface displacements that would be expected to be recorded by geodetic monitoring networks for a given caldera subsidence. Such results may be useful for interpreting signals from ice-covered volcanoes, such as Bardarbunga and many other volcanoes in Iceland.

  9. Displacement fields from point cloud data: Application of particle imaging velocimetry to landslide geodesy

    NASA Astrophysics Data System (ADS)

    Aryal, Arjun; Brooks, Benjamin A.; Reid, Mark E.; Bawden, Gerald W.; Pawlak, Geno R.

    2012-03-01

    Acquiring spatially continuous ground-surface displacement fields from Terrestrial Laser Scanners (TLS) will allow better understanding of the physical processes governing landslide motion at detailed spatial and temporal scales. Problems arise, however, when estimating continuous displacement fields from TLS point-clouds because reflecting points from sequential scans of moving ground are not defined uniquely, thus repeat TLS surveys typically do not track individual reflectors. Here, we implemented the cross-correlation-based Particle Image Velocimetry (PIV) method to derive a surface deformation field using TLS point-cloud data. We estimated associated errors using the shape of the cross-correlation function and tested the method's performance with synthetic displacements applied to a TLS point cloud. We applied the method to the toe of the episodically active Cleveland Corral Landslide in northern California using TLS data acquired in June 2005-January 2007 and January-May 2010. Estimated displacements ranged from decimeters to several meters and they agreed well with independent measurements at better than 9% root mean squared (RMS) error. For each of the time periods, the method provided a smooth, nearly continuous displacement field that coincides with independently mapped boundaries of the slide and permits further kinematic and mechanical inference. For the 2010 data set, for instance, the PIV-derived displacement field identified a diffuse zone of displacement that preceded by over a month the development of a new lateral shear zone. Additionally, the upslope and downslope displacement gradients delineated by the dense PIV field elucidated the non-rigid behavior of the slide.

  10. Numerical simulations of saltwater displacement via fault systems due to exploitation of the subsurface

    NASA Astrophysics Data System (ADS)

    Langer, Maria; Tillner, Elena; Kempka, Thomas; Kühn, Michael

    2015-04-01

    Injection of fluids into deep saline aquifers induces an increase in pore pressure in the storage formation, and thus displacement of resident brines. Upward brine migration into shallower aquifers via hydraulically conductive faults may therefore lead to unwanted salinization of potable groundwater resources. In the present study, we investigated different scenarios for a prospective storage site close to the city of Beeskow in the Northeast German Basin by using a representative 3D regional-scale model (100 km x 100 km x 1.34 km) that includes four regional fault zones. The focus was on assessing the impact of fault length and permeability as well as model boundary conditions on the potential salinization of shallow groundwater resources. Moreover, the effects of an overlying secondary brine-bearing reservoir as well as varying initial salt-freshwater boundaries were investigated. We employed numerical simulations of brine injection as a representative fluid based on an example case study discussed by Tillner et al. (2013). Our simulation results demonstrate that pressure build-up within the reservoir determines the fluid rates and duration through the faults, and hence salinization of shallower aquifers. Application of different boundary conditions proved that these have a crucial impact on reservoir fluid displacement. If reservoir boundaries are closed, the fluid displaced via the faults into the shallow aquifer corresponds to the overall injected fluid mass. In that case, fault length and permeability as well as the presence of an overlying secondary reservoir have only temporal effects on brine migration. A fault zone with a hydraulically conductive segment of only two kilometres length causes brine flow into the shallow aquifer of 330 years, which is thus five times longer compared to the case with four faults open over their entire length of 193 km. The presence of an overlying secondary reservoir leads to an additional retardation of brine inflow into the uppermost aquifer up to a factor of three. If the reservoir boundaries are open, salinization is considerably reduced. In the presence of a secondary reservoir, 33 % of equivalent brine mass migrates into the shallow aquifer, if all four faults are completely hydraulically open, whereas the displaced equivalent brine mass is only 13 % if accounting for a single fault of two kilometres length. Without the secondary reservoir, 66 % of the brine mass is displaced in the four fault and about 30 % in the 2 km single fault cases. Taking into account the considered geological boundary conditions, the brine mainly originates from the upper 16 m to 300 m of the investigated faults, and hence the initial salt-freshwater boundary present in the fault is of high relevance for the resulting shallow aquifer salinization. The present study successfully demonstrates that a quantification of brine displacement using numerical simulations is feasible at regional scale. Tillner, E., Kempka, T., Nakaten, B., Kühn, M. Geological CO2 Storage Supports Geothermal Energy Exploitation: 3D Numerical Models Emphasize Feasibility of Synergetic Use (2013) Energy Procedia 37:6604-6616. doi:10.1016/j.egypro.2013.06.593.

  11. Displacement Field Produced by a Surface Source of Vibrations in a Layered Biological Tissue

    NASA Astrophysics Data System (ADS)

    Timanin, E. M.

    2002-01-01

    Theoretical expressions for the components of the displacement vector in a three-layer halfspace with linked and slipping layers are obtained for the case of setting an oscillatory pressure distributed evenly over a circular area at the layer surface. Numerical calculations of the displacement field in the medium are performed for the values of the parameters simulating a skin-fat layer-muscle-liver biological system. The dependences of the oscillatory displacements within tissues on the dimensions and oscillation frequency of the surface source of vibration are studied, and the possibilities of using such a source for the implementation of the sonoelastography method are discussed.

  12. Displacements and stress distribution in D0 Run IIb stave due to CTE mismatches

    SciTech Connect

    Lanfranfo, Giobatta; Fast, James; /Fermilab

    2001-07-01

    A possible D0 Run IIb stave design currently under study is characterized by an outer carbon fiber stiffening shell with the silicon detectors mounted internally and a single central cooling line running between them; in this paper the stave will be analyzed for thermal compatibility since the different coefficient of thermal expansion in the materials may cause unpredictable stresses and strains in the structure. A simplified stave section has been modeled with finite elements for different materials configurations and the vertical and longitudinal displacements induced by the thermal gradient, together with the related stresses, have been computed. Finally, once selected the most suitable material combination, a more realistic model has been created in order to study the influence of the hybrid location along the ladders.

  13. On the derivation of coseismic displacement fields using differential radar interferometry: the Landers earthquake

    Microsoft Academic Search

    A. ZEBKER; PAUL ROsEN

    1961-01-01

    We present a map of the coseismic displacement field resulting from the Landers, CA, June 28, 1992 earthquake derived using data acquired from an orbiting high resolution radar system. We achieve results more accurate than previous space studies and similar in accuracy to those obtained by conventional field survey techniques. Data from the ERS-1 synthetic aperture radar instrument acquired in

  14. Displacement Field Reciprocity, Nonlinearity, and Time Reversal: An Experimental Exploration

    Microsoft Academic Search

    T. Ulrich; R. A. Guyer

    2005-01-01

    The use of the time reversal mirror (TRM) has recently been applied in three dimensional elastic solids, including earth materials. The applications of the TRM in solids is being developed for nondestructive testing as well as gaining information about earthquake sources. A fundamental requirement for using the TRM is the concept of reciprocity, which has been brought into question due

  15. Application of dynamic displacement current for diagnostics of subnanosecond breakdowns in an inhomogeneous electric field

    SciTech Connect

    Shao Tao; Zhang Cheng; Yan Ping [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Power Electronics and Electric Drive, Chinese Academy of Sciences, Beijing 100190 (China); Tarasenko, Victor F.; Burachenko, Alexandr G.; Rybka, Dmitry V.; Kostyrya, Igor' D.; Lomaev, Mikhail I.; Baksht, Evgeni Kh. [Institute of High Current Electronics, Russian Academy of Sciences, Tomsk 634055 (Russian Federation)

    2013-05-15

    The breakdown of different air gaps at high overvoltages in an inhomogeneous electric field was investigated with a time resolution of up to 100 ps. Dynamic displacement current was used for diagnostics of ionization processes between the ionization wave front and a plane anode. It is demonstrated that during the generation of a supershort avalanche electron beam (SAEB) with amplitudes of {approx}10 A and more, conductivity in the air gaps at the breakdown stage is ensured by the ionization wave, whose front propagates from the electrode of small curvature radius, and by the dynamic displacement current between the ionization wave front and the plane electrode. The amplitude of the dynamic displacement current measured by a current shunt is 100 times greater than the SAEB. It is shown that with small gaps and with a large cathode diameter, the amplitude of the dynamic displacement current during a subnanosecond rise time of applied pulse voltage can be higher than 4 kA.

  16. Displacement Field Reciprocity, Nonlinearity, and Time Reversal: An Experimental Exploration

    NASA Astrophysics Data System (ADS)

    Ulrich, T.; Guyer, R. A.

    2005-12-01

    The use of the time reversal mirror (TRM) has recently been applied in three dimensional elastic solids, including earth materials. The applications of the TRM in solids is being developed for nondestructive testing as well as gaining information about earthquake sources. A fundamental requirement for using the TRM is the concept of reciprocity, which has been brought into question due mainly to P ? S mode conversion and nonlinearity. This paper reports on experimental tests of reciprocity in a set of reverberant cavities, including Berea sandstone. A quantitative measure of reciprocity is introduced and used to test the reciprocity of direct signals, A? B and B? A, and the reciprocity of focused time reversed signals, A? BT-1B? A and B? AT-1A? B. The influence of sample preparation, source characteristics and deliberately introduced scatters is examined for direct signals. Focused time reversed signals obey reciprocity in a linear cavity. Departure from reciprocity of focused time reversed signals in a nonlinear cavity (sandstone block) is associated with the production of higher harmonics due to the nonlinearity of the sandstone.

  17. On the derivation of coseismic displacement fields using differential radar interferometry: The Landers earthquake

    NASA Technical Reports Server (NTRS)

    Zebker, Howard A.; Rosen, Paul A.; Goldstein, Richard M.; Gabriel, Andrew; Werner, Charles L.

    1994-01-01

    We present a map of the coseimic displacement field resulting from the Landers, California, June 28, 1992, earthquake derived using data acquired from an orbiting high-resolution radar system. We achieve results more accurate than previous space studies and similar in accuracy to those obtained by conventional field survey techniques. Data from the ERS 1 synthetic aperture radar instrument acquired in April, July, and August 1992 are used to generate a high-resolution, wide area map of the displacements. The data represent the motion in the direction of the radar line of sight to centimeter level precision of each 30-m resolution element in a 113 km by 90 km image. Our coseismic displacement contour map gives a lobed pattern consistent with theoretical models of the displacement field from the earthquake. Fine structure observed as displacement tiling in regions several kilometers from the fault appears to be the result of local surface fracturing. Comparison of these data with Global Positioning System and electronic distance measurement survey data yield a correlation of 0.96; thus the radar measurements are a means to extend the point measurements acquired by traditional techniques to an area map format. The technique we use is (1) more automatic, (2) more precise, and (3) better validated than previous similar applications of differential radar interferometry. Since we require only remotely sensed satellite data with no additioanl requirements for ancillary information. the technique is well suited for global seismic monitoring and analysis.

  18. Full-field dynamic strain prediction on a wind turbine using displacements of optical targets measured by stereophotogrammetry

    NASA Astrophysics Data System (ADS)

    Baqersad, Javad; Niezrecki, Christopher; Avitabile, Peter

    2015-10-01

    Health monitoring of rotating structures (e.g. wind turbines and helicopter blades) has historically been a challenge due to sensing and data transmission problems. Unfortunately mechanical failure in many structures initiates at components on or inside the structure where there is no sensor located to predict the failure. In this paper, a wind turbine was mounted with a semi-built-in configuration and was excited using a mechanical shaker. A series of optical targets was distributed along the blades and the fixture and the displacement of those targets during excitation was measured using a pair of high speed cameras. Measured displacements with three dimensional point tracking were transformed to all finite element degrees of freedom using a modal expansion algorithm. The expanded displacements were applied to the finite element model to predict the full-field dynamic strain on the surface of the structure as well as within the interior points. To validate the methodology of dynamic strain prediction, the predicted strain was compared to measured strain by using six mounted strain-gages. To verify if a simpler model of the turbine can be used for the expansion, the expansion process was performed both by using the modes of the entire turbine and modes of a single cantilever blade. The results indicate that the expansion approach can accurately predict the strain throughout the turbine blades from displacements measured by using stereophotogrammetry.

  19. Vertical crustal displacement due to interseismic deformation along the San Andreas fault

    E-print Network

    Sandwell, David T.

    vertical velocities that are ~10 times smaller than horizontal velocities, caused by along the flexure of the elastic plate caused by bending moments applied at the ends of locked faults. 1 half-space, the far-field postseismic signals could have resulted from viscoelastic flow in the upper

  20. Velocity fields and streamline patterns of miscible displacements in cylindrical tubes

    Microsoft Academic Search

    J. Kuang; P. Petitjeans; T. Maxworthy

    2004-01-01

    Displacements of a viscous fluid by a miscible fluid of a lesser viscosity and density in cylindrical tubes were investigated experimentally. Details of velocity and Stokes streamline fields in vertical tubes were measured using a DPIV (digital particle image velocimetry) technique. In a reference frame moving with the fingertip, the streamline patterns around the fingertip obtained from the present measurements

  1. 3D displacement field measurement with correlation based on the micro-geometrical surface texture

    NASA Astrophysics Data System (ADS)

    Bubaker-Isheil, Halima; Serri, Jérôme; Fontaine, Jean-François

    2011-07-01

    Image correlation methods are widely used in experimental mechanics to obtain displacement field measurements. Currently, these methods are applied using digital images of the initial and deformed surfaces sprayed with black or white paint. Speckle patterns are then captured and the correlation is performed with a high degree of accuracy to an order of 0.01 pixels. In 3D, however, stereo-correlation leads to a lower degree of accuracy. Correlation techniques are based on the search for a sub-image (or pattern) displacement field. The work presented in this paper introduces a new correlation-based approach for 3D displacement field measurement that uses an additional 3D laser scanner and a CMM (Coordinate Measurement Machine). Unlike most existing methods that require the presence of markers on the observed object (such as black speckle, grids or random patterns), this approach relies solely on micro-geometrical surface textures such as waviness, roughness and aperiodic random defects. The latter are assumed to remain sufficiently small thus providing an adequate estimate of the particle displacement. The proposed approach can be used in a wide range of applications such as sheet metal forming with large strains. The method proceeds by first obtaining cloud points using the 3D laser scanner mounted on a CMM. These points are used to create 2D maps that are then correlated. In this respect, various criteria have been investigated for creating maps consisting of patterns, which facilitate the correlation procedure. Once the maps are created, the correlation between both configurations (initial and moved) is carried out using traditional methods developed for field measurements. Measurement validation was conducted using experiments in 2D and 3D with good results for rigid displacements in 2D, 3D and 2D rotations.

  2. Spin decoherence due to fluctuating fields

    NASA Astrophysics Data System (ADS)

    Sza?kowski, Piotr; Trippenbach, M.; Band, Y. B.

    2013-05-01

    The dynamics of a spin in the presence of a deterministic and a fluctuating magnetic field is solved for analytically to obtain the averaged value of the spin as a function of time for various kinds of fluctuations (noise). Specifically, analytic results are obtained for the time dependence of the expectation value of the spin, averaged over fluctuations, for Gaussian white noise, Gaussian colored noise, and non-Gaussian telegraph noise. Fluctuations cause the decay of the average spin vector (decoherence). For noise with a finite temporal correlation time, a deterministic component of the field can suppress the decoherence of the spin component along the field. Hence, decoherence can be manipulated by controlling the deterministic magnetic field. A simple universal physical picture emerges which explains the mechanism for the suppression of decay.

  3. Forces between Dislocations due to Dislocation Core Fields

    SciTech Connect

    Henager, Charles H.; Hoagland, Richard G.

    2001-11-21

    Atomistic dislocation models were used to determine the properties of dislocation core fields in Al using an EAM potential. Equilibrium atom configurations were compared with initial configurations displaced according to the Volterra field to determine core displacement fields for edge, screw, and mixed (60? and 30?) geometries. The core field was approximated by a line force defect field lying parallel to the dislocation line direction. Best-fit parameters for the core fields were obtained in terms of the anisotropic elastic solution for a line force defect, from which the line force strengths and the origin of the line forces were determined. The line force stress fields were then used to compute the forces between dislocations for several dislocation configurations. The Volterra field dominates beyond 50b but core field forces modify the equilibrium angle of edge dislocation dipoles and determine the force between otherwise non-interacting edge and screw dislocations at distances out to 50b compared to the Volterra-only forces.

  4. Sum rules for non-affine displacement fields and elastic properties of amorphous solids

    NASA Astrophysics Data System (ADS)

    Lemaître, Anaël; Maloney, Craig

    2004-03-01

    The elastic response of amorphous bodies involve non-affine displacement fields which contribute significantly to elastic energy, and bring order unity corrections to the sound speed and Lamé constants. We present exact, non-perturbative, expressions for these non-affine displacement fields and for the macroscopic elastic response of amorphous materials. These expressions offer a precise microscopic definition of elastic constants, which hold at any scale, for any sub-sets of molecules, and which can easily be evaluated numerically with a single inversion of a Hessian matrix. The correction to affine elasticity is directly related to a turbulent-like cascade of energy transfers at mesoscale. Simple assumptions for these transfers open the way toward estimates of elastic properties of amorphous materials from microscopic considerations.

  5. Multiparameter double hole contrast detail phantom: Ability to detect image displacement due to off position anode stem

    NASA Astrophysics Data System (ADS)

    Pauzi, Nur Farahana; Majid, Zafri Azran Abdul; Sapuan, Abdul Halim; Azemin, Mohd Zulfaezal Che; Junet, Laila Kalidah

    2015-04-01

    Contrast Detail phantom is a quality control tool to analyze the performance of imaging devices. Currently, its function is solely to evaluate the contrast detail characteristic of imaging system. It consists of drilled hole which gives effect to the penetration of x-ray beam divergence to pass through the base of each hole. This effect will lead to false appearance of image from its original location but it does not being visualized in the radiograph. In this study, a new design of Contrast Detail phantom's hole which consists of double hole construction has been developed. It can detect the image displacement which is due to off position of anode stem from its original location. The double hole differs from previous milled hole, whereby it consists of combination of different hole diameters. Small hole diameter (3 mm) is positioned on top of larger hole diameter (10 mm). The thickness of double hole acrylic blocks is 13 mm. Result revealed` that, Multiparameter Double Hole Contrast Detail phantom can visualize the shifted flaw image quality produced by x-ray machine due to improper position of the anode stem which is attached to rotor and stator. The effective focal spot of x-ray beam also has been shifted from the center of collimator as a result of off-position anode stem. As a conclusion, the new design of double hole Contrast Detail phantom able to measure those parameters in a well manner.

  6. The electric field due to stripline conductors

    Microsoft Academic Search

    James F. Geer

    1976-01-01

    The problem of determining the electromagnetic fields about conductors surrounded by various dielectric materials, such as in the analyses of transmission line configurations, computer circuit boards, or, more recently, electro-optic effects in crystals, is studied. A slab of dielectric material of finite thickness is bounded above and below by a second (different) dielectric material of infinite extent. A finite number

  7. Probabilistic Fault Displacement Hazard Assessment For Pipelines, Mad Dog and Atlantis Field Developments, Deepwater Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Angell, M.; Hanson, K.; Swan, F.; Youngs, R.; Abramson, H.

    2004-12-01

    Seafloor faults having strong geomorphic expression and evidence for late Quaternary activity (i.e. < ~150,000 years) are common geologic features associated with the Sigsbee Escarpment. Waterbottom maps derived from exploration 3D multichannel seismic data provided an early indication that several zones of seafloor faults are in the vicinity of the Mad Dog and Atlantis prospect areas. As part of the site investigation activities for field development BP initiated a study to characterize the potential hazard due to fault displacement. The fault displacement hazard study consists of five components: 1) a site-wide structural geologic characterization of the style and origin of active faulting and fault-related deformation; 2) development of a late Quaternary stratigraphic model to evaluate the history, recency, and rate of fault activity at the site; 3) detailed characterization of faulting within limited study areas designated to capture fault behavior in areas of potential facilities development; 4) a general description of the relationship between Quaternary active faulting and slope failure processes within the field area; and 5) a probabilistic fault displacement hazard analysis (PFDHA) of the potential for fault rupture within the designated study areas that relates annual frequency of recurrence of faulting events to the size of the event. Changes in the style and origin of faulting and deformation of shallow (suprasalt) sediment across the individual field areas primarily is due to differences in the depth, geometry, and movement history of the underlying Sigsbee Salt Nappe. These relationships and the resulting geologic model for structural evolution of the suprasalt section has been used effectively to assess the site-wide geohazards not only for faulting, but also indirectly for slope failure and mass-gravity flows. Hazard from potential seafloor offset at fault crossings is judged to be moderate to low. Fault offsets of the shallowest horizons (less than 15 thousand years old) are typically less than ten meters to several tens of meters. Fault slip rates are on the order of tenths to several tens of meters-per-thousand-years (m/kyr, also millimeters-per-year, or mm/yr), with most values in the range of 2-10 m/kyr. Similarly, the probabilistic annual recurrence of 1-meter events is typically less than 10-3. These studies demonstrate that the presence of potentially active faults does not preclude safe development of seafloor facilities. To evaluate risk associated with potential seafloor faulting, integrated hazard studies can and should be conducted in the early stages of project development, with an underlying intent to understand the causative processes and quantitatively and explicitly evaluate the locations, magnitude and recurrence potential of displacement events.

  8. Landslide subsurface slip geometry inferred from 3-D surface displacement fields

    NASA Astrophysics Data System (ADS)

    Aryal, Arjun; Brooks, Benjamin A.; Reid, Mark E.

    2015-03-01

    The stability of many large landslides is determined in part by deformation along buried, often inaccessible, slip surfaces. Factors such as infiltrating rainfall on the slip surface lead to stability changes. Yet characterizing the depth and shape of this slip surface is challenging. Here we examine the hypothesis that the subsurface slip geometry can be constrained by ground surface displacements in concert with two, mechanically distinct, forward models. We estimate a 3-D ground displacement field for the slow-moving Cleveland Corral landslide in California using repeat terrestrial laser scanner data. We test the efficacy of two models to estimate slip depth and slip magnitude of the slide—a 2-D balanced cross-section method and an elastic dislocation model. The estimated slip surface depth using both methods matches in situ observations from shear rods installed in the slide within the ±0.45 m misfit indicating that these are valuable approaches for investigating landslide geometry and slip behavior.

  9. Cosmological electromagnetic fields due to gravitational wave perturbations Mattias Marklund*

    E-print Network

    Dunsby, Peter

    Cosmological electromagnetic fields due to gravitational wave perturbations Mattias Marklund of Electromagnetics, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden Peter K. S. Dunsby Department; published 9 October 2000 We consider the dynamics of electromagnetic fields in an almost

  10. Determining crack-tip stress-field parameters from mixed-mode displacement fields

    E-print Network

    Matsumoto, Kay Yuri

    1995-01-01

    SOLUTION ALGORITHM FORTRAN LISTING . . 57 59 61 APPENDIX B ISOCHROMATIC FRINGE FORTRAN SUBROUTINE . . 91 APPENDIX C MOIRE FRINGE FORTRAN SUBROUTINES . . 97 VITA 105 LIST OF TABLES TABLE Page I Input load sets used to calculate theoretical... using the ABAQUS code. The geometry and finite element mesh are shown in Fig. 18. The geometry was derived from experimental specimens used in the experiment examples that will be discussed later. Figure 18 illustrates the Mode I u - displacement...

  11. Application of displacement-based design method to assess the level of structural damage due to blast loads

    Microsoft Academic Search

    Ramezan Ali Izadifard; Mahmoud Reza Maheri

    2010-01-01

    In this paper, a displacement-based design (DBD) methodology commonly used for seismic design and evaluation of structures\\u000a is adopted to determine the performance of structures to blast loading. In this method, structural performance is linked to\\u000a measurable quantities such as the displacement ductility. To verify the applicability of the method and the accuracy of the\\u000a results, a simple structural shape,

  12. Development and validation of anelastic-displacement-fields-based dynamic finite elements

    NASA Astrophysics Data System (ADS)

    Rusovici, Razvan; Inman, Daniel J.; Lesieutre, George A.

    2001-07-01

    Sensitive mechanical or electrical components often require protection from the potentially damaging effects of vibration and shock loading. High-damping viscoelastic materials are usually used in the design of impact-absorbent components. Since shock transients are characterized by a broad frequency spectrum, it is imperative to properly model frequency dependence of material parameters over the frequency range of interest. The Anelastic Displacement Fields (ADF) method is used to incorporate frequency-dependence within a finite element formulation. This method considers the effect of material anelasticity on the displacement field, as opposed to directly modeling physical damping mechanisms. ADF-based, plane-stress, and plane-strain finite elements are developed in order to facilitate the modeling of complex viscoelastic structures. The governing equations and assumptions underlying the various finite element developments are presented. In this paper, corresponding finite element models are used to model shock propagation and absorption through viscoelastic beams. The model predictions are validated against wave propagation theory, which shows that ADF-based finite element models are capable of capturing wave propagation phenomena, such as geometric dispersion, and viscoelastic attenuation and dispersion of longitudinal waves in beams. The behavior of mechanical filters in realistic shock conditions is also investigated. ADF three-dimensional finite element models could thus be successfully employed to design mechanical filters, or compare the benefits of using one viscoelastic material over another for a given shock-mitigating task.

  13. Entropy of Dilatonic Black Hole due to Arbitrary Spin Fields

    NASA Astrophysics Data System (ADS)

    Shen, You-Gen; Gao, Chang-Jun

    2001-08-01

    Using the membrane model based on the brick-wall model, we calculate the free energy and entropy of dilatonic black hole due to arbitrary spin fields. The result shows that the entropy of scalar field and the entropy of Fermionic field have similar formulas. There is only a numerical coefficient between them.

  14. Systematic treatment of displacements, strains, and electric fields in density-functional perturbation theory

    NASA Astrophysics Data System (ADS)

    Wu, Xifan; Vanderbilt, David; Hamann, D. R.

    2005-07-01

    The methods of density-functional perturbation theory may be used to calculate various physical response properties of insulating crystals including elastic, dielectric, Born charge, and piezoelectric tensors. These and other important tensors may be defined as second derivatives of an appropriately defined energy functional with respect to atomic-displacement, electric-field, or strain perturbations, or as mixed derivatives with respect to two of these perturbations. The resulting tensor quantities tend to be coupled in complex ways in polar crystals, giving rise to a variety of variant definitions. For example, it is generally necessary to distinguish between elastic tensors defined under different electrostatic boundary conditions, and between dielectric tensors defined under different elastic boundary conditions. Here, we describe an approach for computing all of these various response tensors in a unified and systematic fashion. Applications are presented for two materials, hexagonal ZnO and rhombohedral BaTiO3 , at zero temperature.

  15. Application of GPS technology to measurements of displacements of high-rise structures due to weak winds

    Microsoft Academic Search

    Peter Breuer; Tadeusz Chmielewski; Piotr Górski; Eduard Konopka

    2002-01-01

    Global positioning systems (GPS) have been developed for military purposes like single-point positioning and navigation. The first non-military applications have been made for geodetic purposes with base-line measurements using differential methods. We introduce GPS technology as an alternative measurement method of displacements when high-rise structural systems are monitored. In this paper, two tests to evaluate the accuracy of the measurements

  16. Calculation of the attenuation and phase displacement per unit of length due to rain composed of ellipsoidal drops

    NASA Technical Reports Server (NTRS)

    Maggiori, D.

    1981-01-01

    All of the phenomena which influence the propagation of radiowaves at frequencies above 10 GHz (attenuation, depolarization, scintillation) can by intensified by parameters directly derived from a solution of individual scatter, naturally in addition to be meteorological elements which characterize the physical medium. The diffusion caused by rainy precipitation was studied using Mie's algorithm for rain composed of spherical drops, and Oguchi's algorithm for rain composed of drops in an ellipsoidal form with axes of rotational symmetry arrange along the vertical line of a generic reference point. Specific phase displacement and attenuation along the principal planes, propagation of radiowaves in generic polarization, and propagation with inclined axes are also considered.

  17. Habitat partitioning and competitive displacement in cattails (Typha): experimental field studies

    Microsoft Academic Search

    James B. Grace; Robert G. Wetzel

    1981-01-01

    A conspicuous feature of many plant communities that is often considered evidence of competitive displacement is the segregation of species along a habitat gradient. The extent of competitive displacement is examined in a recently established association of cattails (Typha latifolia L. and T. angustifolia L.). To accomplish this, potential and realized distributions of these two species were compared along a

  18. Displacement measuring technique for satellite-to-satellite laser interferometer to determine Earth's gravity field

    Microsoft Academic Search

    Shigeo Nagano; Taizoh Yoshino; Hiroo Kunimori; Mizuhiko Hosokawa; Seiji Kawamura; Takashi Sato; Masashi Ohkawa

    2004-01-01

    We present a new displacement measuring technique with simplicity, robustness, high sensitivity and wide measurement range. A set of a frequency shifter and a voltage-frequency converter is used to lock a homodyne interferometer on the half-bright fringe by eliminating the Doppler fringe resulting from mirror motion. The mirror displacement is directly retrieved from the feedback signal of a fringe control

  19. IEEE TRANSACTIONS ON MEDICAL IMAGING, VOL. 21, NO. 12, DECEMBER 2002 1461 Edge Displacement Field-Based Classification for

    E-print Network

    Tomasi, Carlo

    and removed. Currently, the only definitive examination of the colon is fiber-optic colonoscopy, which), computer-aided diagnosis, edge displacement fields (EDFs), fiber-optic colonoscopy (FOC). I. INTRODUCTION. We performed a tenfold cross-validation study to assess its performance using sensitivity

  20. Anisotropy in MHD turbulence due to a mean magnetic field

    NASA Technical Reports Server (NTRS)

    Shebalin, J. V.; Matthaeus, W. H.; Montgomery, D.

    1982-01-01

    The development of anisotropy in an initially isotropic spectrum is studied numerically for two-dimensional magnetohydrodynamic turbulence. The anisotropy develops due to the combined effects of an externally imposed dc magnetic field and viscous and resistive dissipation at high wave numbers. The effect is most pronounced at high mechanical and magnetic Reynolds numbers. The anisotropy is greater at the higher wave numbers.

  1. Fluid fields due to many-body hydrodynamic interactions

    Microsoft Academic Search

    I. T. Pie?kowska

    2001-01-01

    We consider the characteristics of the unsteady flows, generated in the incompressible, viscous fluid by the hydrodynamic interactions between a finite number of solid spheres. The non-stationary properties of the velocity fields, due to the local inertia of the fluid, are discussed. To take into account the local acceleration effects, we apply the time-dependent Green's tensor. The four different types

  2. Investigations of viscoelastic structure behavior using a three dimensional anelastic displacement field finite element

    NASA Astrophysics Data System (ADS)

    Rusovici, Razvan; Lesieutre, George A.

    2003-07-01

    Space systems comprise sensitive electronics and delicate mechanical instruments that need to be protected against harsh vibration and shock loads encountered during launch or landing. High damping viscoelastic materials are often used in the design of geometrically complex, shock and vibration isolation components. Since shock transients are characterized by a broad frequency spectrum, and since viscoelastic materials are characterized by frequency-dependent mechanical properties, it is necessary to properly model this behavior over the frequency domain of interest. The Anelastic Displacement Fields (ADF) method is employed herein to model frequency-dependence of material properties within a time-domain finite element framework. A solid, four-node tetrahedron, ADF-based finite element is developed for single and multiple ADF. This particular element is then validated and used for the general purpose of investigating damping in given structures that employ viscoelastic materials. The new three-dimensional finite element may also be used to investigate the potential phase dependence of the Poisson's ratio for such materials. The model predictions are compared against theory.

  3. Calcium displacement caused by electromagnetic fields. Final report, 1 November 1982-31 August 1989

    SciTech Connect

    Bond, J.D.; Jordan, C.A.

    1989-08-31

    This research effort was to determine theoretically a physical basis for the interaction of low-intensity externally applied electromagnetic fields with biological tissue. The primary aim of the investigation was to establish a molecular basis for the class of interactions commonly referred to as nonthermal effects of electromagnetic fields with biological systems. In particular, the biological structure of interest was the plasma membrane since it had been either directly or indirectly implicated in numerous experimental studies. It was demonstrated how a membrane undergoing a phase transition could qualitatively account for the release and/or uptake of divalent calcium ions. A characterization of changes in the structure of the membrane/electrolyte interface due to field induced changes in enzymatic activity was demonstrated. The role of critical phenomena was shown analytically to be able to account for the unique sensitivity of biomembranes to weak external field perturbations, and describe alterations in the passive transport of sodium ions in rabbit erythrocytes.

  4. Needle detection in ultrasound using the spectral properties of the displacement field: a feasibility study

    NASA Astrophysics Data System (ADS)

    Beigi, Parmida; Salcudean, Tim; Rohling, Robert; Lessoway, Victoria A.; Ng, Gary C.

    2015-03-01

    This paper presents a new needle detection technique for ultrasound guided interventions based on the spectral properties of small displacements arising from hand tremour or intentional motion. In a block-based approach, the displacement map is computed for each block of interest versus a reference frame, using an optical flow technique. To compute the flow parameters, the Lucas-Kanade approach is used in a multiresolution and regularized form. A least-squares fit is used to estimate the flow parameters from the overdetermined system of spatial and temporal gradients. Lateral and axial components of the displacement are obtained for each block of interest at consecutive frames. Magnitude-squared spectral coherency is derived between the median displacements of the reference block and each block of interest, to determine the spectral correlation. In vivo images were obtained from the tissue near the abdominal aorta to capture the extreme intrinsic body motion and insertion images were captured from a tissue-mimicking agar phantom. According to the analysis, both the involuntary and intentional movement of the needle produces coherent displacement with respect to a reference window near the insertion site. Intrinsic body motion also produces coherent displacement with respect to a reference window in the tissue; however, the coherency spectra of intrinsic and needle motion are distinguishable spectrally. Blocks with high spectral coherency at high frequencies are selected, estimating a channel for needle trajectory. The needle trajectory is detected from locally thresholded absolute displacement map within the initial estimate. Experimental results show the RMS localization accuracy of 1:0 mm, 0:7 mm, and 0:5 mm for hand tremour, vibrational and rotational needle movements, respectively.

  5. Measuring discontinuous displacement fields in cracked specimens using digital image correlation with mesh adaptation and crack-path optimization

    NASA Astrophysics Data System (ADS)

    Fagerholt, E.; Børvik, T.; Hopperstad, O. S.

    2013-03-01

    This paper evaluates mesh adaptation techniques in two-dimensional digital image correlation (2D-DIC) analyses of specimens with large deformations and a single propagating crack. The "finite element" formulation of DIC is chosen as basis for this study. The focus has been on the challenges caused by high-gradient and discontinuous displacement fields in the region of a propagating crack, and the aim has been to improve both the robustness and the accuracy of the correlation in such regions. Mesh adaptation based on node splitting and a novel overlapping-mesh technique have been implemented in a DIC code and used to capture the discontinuous displacement fields of cracked specimens. In addition, a procedure for optimization of the location of the crack path is presented. Synthetic image series with known displacement fields, generated from finite element simulations, have been analyzed to evaluate the performance of the presented techniques. Additionally, an experimental image series of a modified Arcan test has been analyzed using the proposed mesh adaptation and crack-path optimization. The paper contains a detailed description of the proposed techniques and results from the evaluation. It is found that both the node-splitting and overlapping-mesh techniques can be applied to successfully capture the discontinuous displacement field of a propagating crack. In the latter technique, the crack path is described down to pixel level. The crack-path optimization is capable of locating the crack path with sub-pixel accuracy, reducing correlation residuals and thus increasing the robustness of the DIC analysis. In addition, a certain filtering of pixels based on high correlation residual is found to increase the robustness of the correlation in areas affected by a propagating crack.

  6. Optics for five-dimensional measurement for correction of vertical displacement error due to attitude of floating body in superconducting magnetic levitation system

    SciTech Connect

    Shiota, Fuyuhiko; Morokuma, Tadashi [National Metrology Institute of Japan (NMIJ), AIST, Tsukuba Central 3, 1-1-1 Umezono, Ibaraki 305-8563 (Japan); Tokyo Denki University, 2-2 Kanda-Nishiki-cho, Chiyoda-ku, Tokyo 101-8457 (Japan)

    2006-09-15

    An improved optical system for five-dimensional measurement has been developed for the correction of vertical displacement error due to the attitude change of a superconducting floating body that shows five degrees of freedom besides a vertical displacement of 10 mm. The available solid angle for the optical measurement is extremely limited because of the cryogenic laser interferometer sharing the optical window of a vacuum chamber in addition to the basic structure of the cryogenic vessel for liquid helium. The aim of the design was to develop a more practical as well as better optical system compared with the prototype system. Various artifices were built into this optical system and the result shows a satisfactory performance and easy operation overcoming the extremely severe spatial difficulty in the levitation system. Although the system described here is specifically designed for our magnetic levitation system, the concept and each artifice will be applicable to the optical measurement system for an object in a high-vacuum chamber and/or cryogenic vessel where the available solid angle for an optical path is extremely limited.

  7. Optics for five-dimensional measurement for correction of vertical displacement error due to attitude of floating body in superconducting magnetic levitation system

    NASA Astrophysics Data System (ADS)

    Shiota, Fuyuhiko; Morokuma, Tadashi

    2006-09-01

    An improved optical system for five-dimensional measurement has been developed for the correction of vertical displacement error due to the attitude change of a superconducting floating body that shows five degrees of freedom besides a vertical displacement of 10mm. The available solid angle for the optical measurement is extremely limited because of the cryogenic laser interferometer sharing the optical window of a vacuum chamber in addition to the basic structure of the cryogenic vessel for liquid helium. The aim of the design was to develop a more practical as well as better optical system compared with the prototype system. Various artifices were built into this optical system and the result shows a satisfactory performance and easy operation overcoming the extremely severe spatial difficulty in the levitation system. Although the system described here is specifically designed for our magnetic levitation system, the concept and each artifice will be applicable to the optical measurement system for an object in a high-vacuum chamber and/or cryogenic vessel where the available solid angle for an optical path is extremely limited.

  8. Model study on the kinetics of oil field formation damage due to salt precipitation from injection

    Microsoft Academic Search

    J. Moghadasi; H. Müller-Steinhagen; M. Jamialahmadi; A. Sharif

    2004-01-01

    Due to the extensive use of water injection for oil displacement and pressure maintenance in oilfields, many reservoirs experience the problem of scale deposition when injection water starts to break through. In most cases, the scaled-up wells are caused by the formation of sulfate and carbonate scales of calcium and strontium. Due to their relative hardness and low solubility, there

  9. Interplate coupling beneath NE Japan inferred from three-dimensional displacement field

    Microsoft Academic Search

    Yoko Suwa; Satoshi Miura; Akira Hasegawa; Toshiya Sato; Kenji Tachibana

    2006-01-01

    The northeastern Japan arc is located in a typical subduction zone and is a seismically active region where large interplate earthquakes have occurred repeatedly. The nationwide GPS network has made it possible to investigate the crustal deformation in unprecedented detail; however, vertical displacements are less accurate than the horizontal ones and have not been used to constrain interplate coupling models.

  10. Development and validation of anelastic-displacement-fields-based dynamic finite elements

    Microsoft Academic Search

    Razvan Rusovici; Daniel J. Inman; George A. Lesieutre

    2001-01-01

    Sensitive mechanical or electrical components often require protection from the potentially damaging effects of vibration and shock loading. High-damping viscoelastic materials are usually used in the design of impact-absorbent components. Since shock transients are characterized by a broad frequency spectrum, it is imperative to properly model frequency dependence of material parameters over the frequency range of interest. The Anelastic Displacement

  11. Field data do not support a textbook example of convergent character displacement.

    PubMed Central

    Scott, R J; Foster, S A

    2000-01-01

    Experimental evidence supporting convergent character displacement is rare; only one example exists and it is in the form of orientation and territory competition experiments performed in the laboratory. However, outcomes of laboratory experiments involving behaviour or competition can be artefacts of unnatural conditions and, therefore, the results of the previous experiments supporting convergent character displacement are equivocal. In this study, we re-examine the evolution of melanic nuptial coloration in male three-spined stickleback (Gasterosteus aculeatus) inhabiting the Chehalis River drainage in Washington State. This novel nuptial coloration has been thought to have evolved in response to competition for nesting territories with the co-distributed Olympic mudminnow (Norzumbra hubbsi), which is also melanic and breeds at the same time. I found that melanic stickleback males did not have an advantage over their red counterparts from typical populations when competing for nesting territories with Olympic mudminnows. Additionally competitive interactions between sticklebacks and mudminnows were rare in both cage experiments and naturally breeding sticklebacks. Finally, melanic coloration in the Chehalis populations did not develop until males were parental, well after the hypothesized territory establishment period. These results refute the only experimental support for convergent character displacement and emphasize the importance of conducting behavioural experiments and observations under natural conditions. PMID:10787166

  12. Analysis of the far-field crustal displacements caused by the 2011 Great Tohoku earthquake inferred from continuous GPS observations

    NASA Astrophysics Data System (ADS)

    Shestakov, Nikolay V.; Takahashi, Hiroaki; Ohzono, Mako; Prytkov, Alexander S.; Bykov, Victor G.; Gerasimenko, Mikhail D.; Luneva, Margarita N.; Gerasimov, Grigory N.; Kolomiets, Andrey G.; Bormotov, Vladimir A.; Vasilenko, Nikolay F.; Baek, Jeongho; Park, Pil-Ho; Serov, Mikhail A.

    2012-02-01

    Small coseismic offsets detectable using GPS techniques were found more than 2300 km away from the Great Tohoku 2011 earthquake epicenter. Area of the most intense far-field co- and postseismic deformations with the maximum offset values exceeding 40 and 18 mm, respectively, extends westward from Honshu Island to the Korean Peninsula, northeastern China and southern Far East Russia. Sakhalin Island does not exhibit notable displacements caused by the earthquake, in contrast to the adjacent territories. A rectangular fault model with uniform slip was developed based on the GPS-detected far-field coseismic displacements using the spherically layered Earth assumption. Both far- and near-field coseismic deformations are generally well described by a single-segment rupture of 200 × 96 km2, characterized by thrust slip with minor strike-slip component of about 33 m and by the seismic moment value of 1.9·1022 N·m (Mw = 8.8), which roughly constrains the major slip area. The resultant compact fault geometry revealed that the main portion of the seismic moment had been realized in a relatively small-sized rupture segment. The sensitivity of far-field GPS data to the major slip area might also be used in the development of a seismically generated giant tsunami warning system.

  13. Measurement of beating effects in narrowband multimode Lamb wave displacement fields in aluminum plates by pulsed TV Holography

    NASA Astrophysics Data System (ADS)

    Fernandez, Jose L.; Trillo, Cristina; Doval, Angel F.; Cernadas, Daniel; Lopez, Carlos; Dorrio, Benito V.; Miranda, Marta; Rodriguez, Francisco

    2005-06-01

    Narrowband ultrasonic surface acoustic waves are of the greatest current interest for the nondestructive testing of thin-walled members and shell structures like plates, pipes, bridge girders, cans and many others. The measurement and characterization of ultrasonic displacement fields of Lamb waves by pulsed TV holography (TVH) is presented. Narrowband ultrasound is generated in a few millimeters thick aluminum plate by the prismatic coupling block method using a tone-burst excitation signal in the range of 1MHz. At this frequency, the plate supports only a few Lamb wave modes, mainly the A0 and S0 ones. The simultaneous presence of these modes produces a beating clearly detectable as a spatial amplitude modulation. Our self-developed TVH system performs the optical phase evaluation by the Spatial Fourier Transform Method and renders the instantaneous out-of-plane mechanical displacement field along the whole inspected area. From this field, the wavenumber of each Lamb mode can be obtained and, by combining them with the value of the ultrasound frequency and with the Rayleigh-Lamb theoretical frequency spectrum, information about the elastic constants of the specimen material is obtained.

  14. Habitat partitioning and competitive displacement in cattails (Typha): experimental field studies

    SciTech Connect

    Grace, J.B.; Wetzel, R.G.

    1981-10-01

    A conspicuous feature of many plant communities that is often considered evidence of competitive displacement is the segregation of species along a habitat gradient. The extent of competitive displacement is examined in a recently established association of cattails (Typha latifolia L. and T. angustifolia L.). To accomplish this, potential and realized distributions of these two species were compared along a gradient of water depth in a small pond. These two species together comprised more than 95% of the plant biomass along the gradient and as such constituted a natural two-species association. Comparisons between potential and realized distributions permit a direct estimate of the reductions in abundance of each species by the presence of the other species and the reduction in potential niche overlap along the habitat gradient. In addition, the study of competitive interactions between T. latifolia and T. angustifolia provides us with an opportunity to evaluate the classification of these two species as respectively r-selected and K-selected (McNaughton 1975).

  15. Characterization of a fiber-optic displacement sensor for measurements in high-intensity focused ultrasound fields.

    PubMed

    Haller, Julian; Wilkens, Volker; Jenderka, Klaus-Vitold; Koch, Christian

    2011-06-01

    A fiber-optic sensor is presented that is capable of measuring the particle displacement in high-intensity focused ultrasound (HIFU) fields. For this probe, a secondary calibration was performed, and the resulting complex frequency response is discussed. As a first practical application, the setup was used to measure the pressure in the field of a weakly focusing ultrasound transducer. The result is compared with that of a membrane hydrophone measurement. The feasibility of measurements in HIFU fields is demonstrated by means of measurements of the spatial distribution of the peak particle velocity within the focus of a HIFU transducer and of the dependence of the peak values on the acoustical power level. PMID:21682392

  16. DESIGN NOTE: Real-time measurement of acoustic field displacements using ultrasonic interferometry

    NASA Astrophysics Data System (ADS)

    Kannath, A.; Dewhurst, R. J.

    2004-12-01

    A measurement technique using ultrasonic interferometry is described for non-contact, quantitative measurement of acoustic vibrations. A pair of low-cost ultrasonic transducers was used in a transmit receive mode to direct a 40 kHz carrier wave to the surface of a solid target vibrating acoustically, such as a speaker cone. Demodulation of return signals consisted of a phase sensitive detection circuit to assess interference between the carrier wave and return signal. Recovered signals were enhanced using real-time digital signal processing hardware to improve signal-to-noise ratios for audio vibration measurements. Phase resolution of at least 3.4 mrads has been demonstrated in the audio frequency range. This represented an equivalent displacement of 2.3 µm in air.

  17. Elastostatic fields in an anisotropic substrate due to a buried quantum dot and B. Yang

    E-print Network

    Pan, Ernie

    for the numerical prediction of displacement, stress, strain, and strain energy density fields in an anisotropic that the hydrostatic strain and strain energy density on the surface of anisotropic half-space made of different are in the form of a pyramid. When the infinite domain is anisotropic, Andreev et al.9 and Faux and Pearson6

  18. The displacement field characterization of two interacting parallel edge cracks in a finite body

    E-print Network

    Keener, Todd Whitney

    1996-01-01

    by M/b, as a Function of the Ratio c/ai for the Length Ratio as/at=1. 0. (a) U-field; (b) V-field. Shear Mode Stress Intensity Factor, Scaled by M/b, as a Function of the Ratio c/ai for the Length Ratio ai/a|=1. 25. (a) U-field; (b) V-field. J...

  19. Generation of decoherence-free displaced squeezed states of radiation fields and a squeezed reservoir for atoms in cavity QED

    E-print Network

    T. Werlang; R. Guzman; F. O. Prado; C. J. Villas-Boas

    2008-06-17

    We present a way to engineer an effective anti-Jaynes-Cumming and a Jaynes-Cumming interaction between an atomic system and a single cavity mode and show how to employ it in reservoir engineering processes. To construct the effective Hamiltonian, we analyse considered the interaction of an atomic system in a \\{Lambda} configuration, driven by classical fields, with a single cavity mode. With this interaction, we firstly show how to generate a decoherence-free displaced squeezed state for the cavity field. In our scheme, an atomic beam works as a reservoir for the radiation field trapped inside the cavity, as employed recently by S. Pielawa et al. [Phys. Rev. Lett. 98, 240401 (2007)] to generate an Einstein-Podolsky-Rosen entangled radiation state in high-Q resonators. In our scheme, all the atoms have to be prepared in the ground state and, as in the cited article, neither atomic detection nor precise interaction times between the atoms and the cavity mode are required. From this same interaction, we can also generate an ideal squeezed reservoir for atomic systems. For this purpose we have to assume, besides the engineered atom-field interaction, a strong decay of the cavity field (i.e., the cavity decay must be much stronger than the effective atom-field coupling). With this scheme, some interesting effects in the dynamics of an atom in a squeezed reservoir could be tested.

  20. Magnetic Field Configurations Due to Air Core Coils

    Microsoft Academic Search

    John P. Blewett

    1947-01-01

    The field configurations around a circular loop of wire bearing current are discussed, and a tabulation is presented for the field component parallel to the axis of the loop. Formulae are derived for the current distribution which must obtain in cylindrical and ellipsoidal coils in order that the field inside be uniform. Several special cases are noted. The energy storage

  1. Gold marker displacement due to needle insertion during HDR-brachytherapy for treatment of prostate cancer: A prospective cone beam computed tomography and kilovoltage on-board imaging (kV-OBI) study

    PubMed Central

    2012-01-01

    Purpose To evaluate gold marker displacement due to needle insertion during HDR-brachytherapy for therapy of prostate cancer. Patients and methods 18 patients entered into this prospective evaluation. Three gold markers were implanted into the prostate during the first HDR-brachytherapy procedure after the irradiation was administered. Three days after marker implantation all patients had a CT-scan for planning purpose of the percutaneous irradiation. Marker localization was defined on the digitally-reconstructed-radiographs (DRR) for daily (VMAT technique) or weekly (IMRT) set-up error correction. Percutaneous therapy started one week after first HDR-brachytherapy. After the second HDR-brachytherapy, two weeks after first HDR-brachtherapy, a cone-beam CT-scan was done to evaluate marker displacement due to needle insertion. In case of marker displacement, the actual positions of the gold markers were adjusted on the DRR. Results The value of the gold marker displacement due to the second HDR-brachytherapy was analyzed in all patients and for each gold marker by comparison of the marker positions in the prostate after soft tissue registration of the prostate of the CT-scans prior the first and second HDR-brachytherapy. The maximum deviation was 5 mm, 7 mm and 12 mm for the anterior-posterior, lateral and superior-inferior direction. At least one marker in each patient showed a significant displacement and therefore new marker positions were adjusted on the DRRs for the ongoing percutaneous therapy. Conclusions Needle insertion in the prostate due to HDR-brachytherapy can lead to gold marker displacements. Therefore, it is necessary to verify the actual position of markers after the second HDR-brachytherapy. In case of significant deviations, a new DRR with the adjusted marker positions should be generated for precise positioning during the ongoing percutaneous irradiation. PMID:22348595

  2. Measuring Oscillatory Velocity Fields Due to Swimming Algae

    E-print Network

    Guasto, Jeffrey S; Gollub, J P

    2010-01-01

    In this fluid dynamics video, we present the first time-resolved measurements of the oscillatory velocity field induced by swimming unicellular microorganisms. Confinement of the green alga C. reinhardtii in stabilized thin liquid films allows simultaneous tracking of cells and tracer particles. The measured velocity field reveals complex time-dependent flow structures, and scales inversely with distance. The instantaneous mechanical power generated by the cells is measured from the velocity fields and peaks at 15 fW. The dissipation per cycle is more than four times what steady swimming would require.

  3. Young's Modulus Reconstruction for Radio-Frequency Ablation Electrode-Induced Displacement Fields: A Feasibility Study

    Microsoft Academic Search

    Jingfeng Jiang; Tomy Varghese; Christopher L. Brace; Ernest L. Madsen; Timothy J. Hall; Shyam Bharat; Maritza A. Hobson; James A. Zagzebski; Fred T. Lee Jr.

    2009-01-01

    Radio-frequency (RF) ablation is a minimally invasive treatment for tumors in various abdominal organs. It is effective if good tumor localization and intraprocedural monitoring can be done. In this paper, we investigate the feasibility of using an ultrasound-based Young's modulus reconstruction algorithm to image an ablated region whose stiffness is elevated due to tissue coagulation. To obtain controllable tissue deformations

  4. V-fields due latest monitoring, control technology

    SciTech Connect

    Not Available

    1987-06-29

    Conoco (U.K.) Ltd. this spring begins the installation phase of its V-fields project in the southern basin of the British North Sea. A feature of the $1.25 billion project to develop the Vulcan, North and South Valiant, and Vanguard fields will be one of the most sophisticated control and monitoring systems in the North Sea. The Calcam system (Computer Assisted Logic Control and Monitoring) was designed, developed, and manufactured by Conoco U.K.'s southern offshore operations division. Calcam was first operated successfully on Conoco's Victor and Viking facilities in 1984. The V-fields are about 15 miles west of the Victor and Viking developments. Conoco is installing a central gas gathering complex which will handle the output from two unmanned satellite wellhead drilling platforms on the Vulcan field, two on North Valiant, and one each of Vanguard and South Valiant. The three fields have combined reserves of about 1.4 tcf. Gas will be delivered to Conoco's existing reception terminal on the coast of Lincolnshire at Theddlethorpe which handles gas from the Viking and Victor fields.

  5. Equivalent Magnetic Field due to Matteucci Effect in nickel

    Microsoft Academic Search

    David Jiles; Yuping Shen; John Snyder; Chester Lo; Andrew Ring; Jason Paulson

    2003-01-01

    The Matteucci Effect, i.e. change in magnetization of a rod under the influence of torque due to magnetoelestic coupling, is useful for sensor applications, but its fundamentals are still not well understand. In this study, the Matteucci effect in nickel and permalloy rods were magnetized along the rod long axis and along the circumference. A method of calculating equivalent magnetic

  6. A Laser Speckle Method for Measuring Displacement Field. Application to Resistance Heating Tensile Test on Steel

    E-print Network

    Paris-Sud XI, Université de

    machine named Taboo. The Taboo set-up allows cyclic loadings at very low strain rate (10-3 -10-4 s-1 technique. Thanks to this method we obtain full field measurements. Experimental Set-up Taboo Tensile Test Machine. The "Taboo" machine (Fig. 1) is a thermo-mechanical simulator which has been developed at Cemef

  7. Transport infrastructure monitoring: A ground based optical displacement monitoring system, field tests on a bridge, the Musmeci's bridge in Potenza, Italy.

    NASA Astrophysics Data System (ADS)

    Hagene, J. K.

    2012-04-01

    A gound based optical displacement monitoring system, "NIODIM", is being developed by Norsk Elektro Optikk in the framework of the activities of the European project "Integrated System for Transport Infrastructure surveillance and Monitoring by Electromagnetic Sensing" (ISTIMES), funded in the 7th Framework Programme (FP7/2007-2013). The optical displacement monitoring system has now participated in two real life field campaigns one in Switzerland and one in Italy. The latter, the tests in Potenza, Italy, will be presented in the following. The NIODIM system has undergone some development during the last year to adopt it for use in a somewhat higher frequency domain by changing the camera sensor part. This to make it more useful for monitoring of structures with oscillation frequencies tens of Hz. The original system was intended to a large extent to monitor land slides, quick clay and rock slides and similar phenomena typically having a relatively slow time response. The system has been significantly speeded up from the original 12 Hz. Current tests have been performed at a frame rate of 64 Hz i.e., the camera part and data processing unit have been running on 64Hz. In connection with the tests in Italy the data processing has been upgraded to include sub-pixel resolution i.e., the measurement results are no longer limited by pixel borders or single pixels. The main part of the NIODIM system is a camera capable of operating at a sufficiently high frame rate. This camera will typically be mounted on firm ground and will depict and monitor a reference point, typically a light emitting diode, LED, which will be mounted on the object susceptible to move. A processing unit will acquire the images from the camera part and find the position of the LED in the image and compare that to threshold values and if required raise a warning or an alarm. The NIODIM system can either be a standalone system or be an integrated part of the overall ISTIMES system, the ISTIMES system being a decision support system. Field trials as part of the ISTIMES project took place in Potenza, Italy, for a week in July 2011. The test target was Musmeci's bridge, a bridge with a design where aesthetic values have been just as important as traditional civil engineering aspects. Several technologies and techniques were tested at the same part of the bridge to allow for data correlation between different sensors. The camera and processing parts of the optical displacement monitoring system were mounted on a concrete wall at the one end of the bridge while the LED reference points were mounted on the bridge approximately 40 metres away. The tests at the Musmeci's bridge are successful and verifying some of the findings from the tests in Switzerland. However, we learned a lesson with regards to temporary mounting of the reference points using glossy stainless steel parts. A short period early in the morning, when illuminated by the sun, these stainless steel parts were just as bright as the LED reference point leading to potential noise in the measurements. Due to availability of the raw data this could be fixed later doing post processing on the stored data. One of the findings was that we have relatively large time of day variation that appear to be periodic with a cycle time of about 24 hours, at least with similar weather conditions. These displacements appear to be in the order of 10 mm and is probably due to thermal effects. Several shorter displacements have also been registered with amplitudes of a couple of mm and duration around 10 seconds. These shorter displacement peaks appear to be caused by heavy vehicles passing by on the bridge. The introduction of the processing using sub-pixel resolution looks very promising and appears to give a significant improvement of the actual resolution of the system. Even thought the measurements in the field are successfully completed we have noted larger slowly moving displacements than originally expected. This combined with shorter lasting peaks could lead to measurements above pre-set thres

  8. Passive eye displacement alters auditory spatial receptive fields of cat superior colliculus neurons.

    PubMed

    Zella, J C; Brugge, J F; Schnupp, J W

    2001-12-01

    The superior colliculus (SC) is thought to use a set of superimposed, topographically organized neural maps of visual, auditory, somatosensory and motor space to direct the eyes toward novel stimuli. Auditory spatial response fields (SRFs) of SC neurons may change when an animal moves its eyes, presumably to compensate for the resulting misalignment of visual and auditory sensory spatial reference frames, but the mechanisms responsible for these SRF changes remain unknown. Here we report that passive deviation of the eye in anesthetized, paralyzed animals can profoundly affect the auditory responsiveness of SC neurons, but seems insufficient by itself to provide adaptive shifts of auditory SRFs. PMID:11713474

  9. Cross-Magnetic-Field Diffusion Due To Quasibound State Formation

    NASA Astrophysics Data System (ADS)

    Ahat, Yasin; Ordonez, Carlos

    2006-04-01

    Classical trajectory simulations indicate that quasibound states of hydrogen (or antihydrogen) can form in low density magnetized plasmas [C. E. Correa, J. R. Correa, and C. A. Ordonez, Phys. Rev. E 72 (2005) 046406.]. Such quasibound states form at positive energies, where the energy of the two-particle system is defined to be zero when the electron and proton are at rest with infinite separation. The formation of quasibound states may affect the rate of diffusion of electrons across a magnetic field. Electron diffusion transverse to a magnetic field occurs, in part, because the guiding center position of an electron shifts with each binary interaction between an electron and a proton. The shift associated with a single binary interaction is normally not larger than a typical cyclotron radius. However, simulations indicate that a binary interaction that results in the formation of a quasibound state can cause a shift of the electron guiding center that is much larger than the cyclotron radius before the interaction. An assessment of the effect that the formation of quasibound states may have on electron cross-field diffusion is presented.

  10. Derivation of 3-D coseismic surface displacement fields for the 2011 Mw 9.0 Tohoku-Oki earthquake from InSAR and GPS measurements

    NASA Astrophysics Data System (ADS)

    Hu, J.; Li, Z. W.; Ding, X. L.; Zhu, J. J.; Sun, Q.

    2013-02-01

    Interferometric synthetic aperture radar (InSAR) and global positioning system (GPS) have obvious deficiencies for monitoring surface deformations, for example, 1-D line-of-sight (LOS) measurements for InSAR and spatially very sparse observations for GPS. In this paper, InSAR and GPS measurements are integrated to derive spatially high-resolution 3-D coseismic surface displacement fields of the 2011 Mw 9.0 Tohoku-Oki, Japan earthquake. A unified simultaneous least squares (USLS) approach is developed to minimize the inconsistence between the InSAR results from adjacent paths. 3-D ground displacements are then derived by integrating the InSAR and the GPS measurements with the method of weighted least squares (WLS). Comparisons with independent GPS measurements show that the root mean square errors (RMSEs) of the derived 3-D displacements are 6.30, 4.57 and 1.29 cm for the vertical, east and north components, respectively. The 3-D coseismic displacement map shows that the Honshu Island moved eastwards towards the epicentre and subsided in the eastern part. The maximal displacements in the vertical, east and north directions are -1.5, 5.0 and -2.0 m, respectively. The effects of the density of GPS sites on the InSAR/GPS integration are also investigated. The experimental results reveal that lower to 70 km spatial resolution's GPS observations are adequate to guarantee the accuracies of the 3-D displacements for the Tohoku-Oki earthquake. This demonstrates the applicability of the developed WLS-based InSAR/GPS integration method, as in general the GPS observations are not as dense as those in this study area. Based on the spatially high-resolution 3-D surface displacement fields, we estimate the high-resolution and 3-D strain of the Tohoku-Oki earthquake. The preliminary results show that the Honshu Island suffers from an evident dilatation and shear during the seismic event.

  11. Internal Displacement Monitoring Centre

    NSDL National Science Digital Library

    The Internal Displacement Monitoring Centre (IDMC) was established twelve years ago in the hope that they would "raise awareness of the plight of internally displaced people (IDP), point to gaps in national and international responses and promote solutions reflecting international standards and best practices." The Centre also keeps a database of 50 countries in which people have been displaced within their own country due to conflicts or human rights violations. To get a sense of where displaced persons are and how many countries have IDPs, visitors can click on the small world map on the far right hand side of the homepage. Scrolling over the map will reveal the number of displaced people by continent. Visitors interested in learning about an individual country can click on the continent, then click on one of the countries for an "Internal Displacement Profile", "Country Statistics", and an "Overview". The Resources tab, at the top of any page, includes "IDMC Publications", "Picture Galleries" of internally displaced people in India, Cyprus, and the West Bank, to name a few, and "IDP Maps" which has dozens of maps of from 2001 to 2009.

  12. Displacement Field and Elastic Energy of a Circular Twist Disclination for Large Deformations - an Example how to Treat Nonlinear Boundary Value Problems with Computer Algebra Systems

    Microsoft Academic Search

    Alexander Unzicker; Karl Fabian

    2003-01-01

    A circular twist disclination is a nontrivial example of a defect in an elastic continuum that causes large deformations. The minimal potential energy and the corresponding displacement field is calculated by solving the Euler-Lagrange-equations. The nonlinear incompressibility constraint is rigorously taken into account. By using an appropriate curvilinear coordinate system a finer resolution in the regions of large deformations is

  13. Estimates of historic, present, and future rates of surface displacement due to hydrodynamic autocompaction of Holocene sediments in the Louisiana delta plain

    NASA Astrophysics Data System (ADS)

    Meckel, T. A.; ten Brink, U.; Williams, S.

    2005-05-01

    Subsidence and resulting rapid relative sea level rise and wetland loss in Louisiana have been attributed to natural geologic (isostatic sediment loading, faulting, sediment compaction, dewatering) and human (subsurface fluid withdrawal, salt mining) processes, but we lack quantitative estimates of the relative contributions of each factor, and their role in future subsidence is largely unknown. Such information is critical for ongoing regional-scale wetland restoration plans. We attempt to isolate the component of subsidence attributable to compaction (gravity-driven reduction in porosity and resulting surface displacement) of sediments deposited above the Lower Wisconsin unconformity (<~18 k.y.) in the delta region. One-dimensional, multi-lithology compaction models based on Darcy flow and Terzaghi effective stress principles are solved using a finite difference technique, allowing calculations of cumulative sedimentation and surface displacement, as well as historic, present, and future (in the absence of further loading) rates of vertical surface displacement. Detailed modeling of the USGS/LGS P-1-90 boring (47 m recovered, 13 radiocarbon dates), at the LUMCON facility in Cocodrie, revealed relationships among sediment type, geotechnical parameters, depositional rate, time, and compaction rate. Results indicate that, regardless of variations in depositional history, present rates of surface displacement can be constrained by two end-member stratigraphic models: 100% sand and 100% mud. Shallow (0-200 m) borehole data from the U.S. Army Corps of Engineers have been used to interpolate a regional isopach of Holocene sediments for the Mississippi River alluvial valley and adjacent delta plain and to extend lithologic generalizations (topstratum/substratum) and suitable geotechnical parameters from the USGS boring. Regional-scale analysis allows comprehensive testing of the hypothesis that higher subsidence rates in the alluvial valley can be attributed to compaction of thicker Holocene deposits.

  14. Cobalt activation of Escherichia coli 5'-nucleotidase is due to zinc ion displacement at only one of two metal-ion-binding sites.

    PubMed Central

    McMillen, Lyle; Beacham, Ifor R; Burns, Dennis M

    2003-01-01

    Escherichia coli 5'-nucleotidase activity is stimulated 30- to 50-fold in vitro by the addition of Co(2+). Seven residues from conserved sequence motifs implicated in the catalytic and metal-ion-binding sites of E. coli 5'-nucleotidase (Asp(41), His(43), Asp(84), His(117), Glu(118), His(217) and His(252)) were selected for modification using site-directed mutagenesis of the cloned ushA gene. On the basis of comparative studies between the resultant mutant proteins and the wild-type enzyme, a model is proposed for E. coli 5'-nucleotidase in which a Co(2+) ion may displace the Zn(2+) ion at only one of two metal-ion-binding sites; the other metal-ion-binding site retains the Zn(2+) ion already present. The studies reported herein suggest that displacement occurs at the metal-ion-binding site consisting of residues Asp(84), Asn(116), His(217) and His(252), leading to the observed increase in 5'-nucleotidase activity. PMID:12603203

  15. Aerodynamic sound generation due to vortex-aerofoil interaction. Part 2: Analysis of the acoustic field

    NASA Technical Reports Server (NTRS)

    Parasarathy, R.; Karamcheti, K.

    1972-01-01

    The Lighthill method was the basic procedure used to analyze the sound field associated with a vortex of modified strength interacting with an airfoil. A free vortex interacting with an airfoil in uniform motion was modeled in order to determine the sound field due to all the acoustic sources, not only on the airfoil surfaces (dipoles), but also the ones distributed on the perturbed flow field (quadrupoles) due to the vortex-airfoil interaction. Because inviscid flow is assumed in the study of the interaction, the quadrupoles considered in the perturbed flow field are entirely due to an unsteady flow field. The effects of airfoil thickness on the second radiation are examined by using a symmetric Joukowski airfoil for the vortex-airfoil interaction. Sound radiation in a plane, far field simplification, and computation of the sound field are discussed.

  16. Giant enhancement of electric field between two close metallic grains due to plasmonic resonance

    E-print Network

    Lebedev, Vladimir

    Giant enhancement of electric field between two close metallic grains due to plasmonic resonance V are established and the electric field enhancement is found. Our general arguments are confirmed by analytic of such nanostructures utilized in these applications is a significant field enhance- ment in the dimer's gap

  17. Fracture surface interference in shear—II. Experimental measurements of crack tip displacement field under mode II loading in 7075-T6 Al

    Microsoft Academic Search

    T. S. Gross; Y. Zhang; D. W. Watt

    1995-01-01

    The in-plane and out-of-plane displacement field around the tip of a crack (produced by Mode I fatigue precracking) loaded in pure, remote Mode II was measured as a function of KIIapp by electro-optic holographic interferometry. The effective Mode II stress intensity factor and the induced Mode I stress intensity factor were estimated from a fit to the near-tip expressions for

  18. CMB temperature anisotropy from broken spatial isotropy due to a homogeneous cosmological magnetic field

    SciTech Connect

    Kahniashvili, Tina [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States); Department of Physics, Laurentian University, Ramsey Lake Road, Sudbury, ON P3E 2C6 (Canada); National Abastumani Astrophysical Observatory, 2A Kazbegi Ave, Tbilisi, GE-0160 (Georgia); Lavrelashvili, George [Department of Theoretical Physics, A. Razmadze Mathematical Institute, 1 M. Aleksidze, Tbilisi, GE-0193 (Georgia); Ratra, Bharat [Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, Kansas 66506 (United States)

    2008-09-15

    We derive the cosmic microwave background temperature anisotropy two-point correlation function (including off-diagonal correlations) from broken spatial isotropy due to an arbitrarily oriented homogeneous cosmological magnetic field.

  19. A geometric method to determine the electric field due to a uniformly charged line segment

    NASA Astrophysics Data System (ADS)

    Zuo, Fulin

    2015-06-01

    A geometrical method to calculate the electric field due to a uniformly charged rod is presented. The result is surprisingly simple and elegant. Using only lengths and angles, the direction of the electric field at any point due to this charge configuration can be graphically determined. The method is not new but seems to have been all but forgotten. A full understanding of this result can lead to a deeper appreciation of symmetry in a seemingly un-symmetric system.

  20. The successive displacement process: Oil recovery during blowdown

    SciTech Connect

    Irwin, D.D.; Batychy, J.P.

    1996-12-31

    Much of Western Canada`s conventional crude oil occurs in vertically-continuous reefal carbonate structures. A common strategy has been to support oil production through downward vertical gas displacement. The gravity stable displacement yields excellent conformance and high oil recoveries with typical residual levels of 20% pore volume. Once the oil zone has been depleted leaving only a sandwich loss, the pools enter a blowdown phase to produce the gas cap from the top of structure. During the blowdown phase, if there is an underlying aquifer, the oil sandwich is displaced upwards into the previously gas-displaced oil zone, trapping gas. Due to the presence of the trapped gas saturation and the low connate water saturation (typical of carbonate reefs), the remaining oil saturation in this zone, as it is displaced by the underlying water is reduced to near miscible levels (10 - 15% PV), mobilizing incremental oil equal to 5 - 10% PV. Whether or not there an aquifer is present, bottom water injection can be applied to ensure displacement through the entire gas-displacement oil zone. The Successive Displacement (SDP), as this tertiary waterflood concept has been named, has been confirmed with full-diameter reservoir-condition core tests on carbonate cores in the laboratory. Observation from the initial stages of a full-field SDP application in Imperial Oil`s Bonnie Glen reservoir after about four years of operation provide further encouragement with performance indicating a reduction in the residual of 5-6% PV.

  1. Evidence of high-field radio-frequency hot-spots due to trapped vortices in niobium cavities

    SciTech Connect

    Ciovati, Gianluigi; Gurevich, Alexander

    2008-12-01

    Superconducting radio-frequency (rf) cavities made of high-purity niobium exhibit strong anomalous rf losses starting at peak surface magnetic fields of about 90-100 mT in the gigahertz range. This phenomenon is referred to as "Q-drop". Temperature maps of the cavity surface have revealed the presence of "hot-spots" in the high magnetic field region of the cavities. Several models have been proposed over the years to explain this phenomenon but there is still no experimental evidence on the mechanisms behind such hot-spots. In this work we show that at least some of the hotspots are due to trapped vortices responsible for the anomalous losses. Here we report experiments in which a local thermal gradient was applied to the hot-spot regions of a cavity in order to displace the vortices. Temperature maps measured before and after applying the thermal gradient unambiguously show that the hotspot do move and change their intensities, allowing us to determine changes in

  2. PINEAL MELATONIN LEVEL DISRUPTION IN HUMANS DUE TO ELECTROMAGNETIC FIELDS AND ICNIRP LIMITS

    E-print Network

    Halgamuge, Malka N.

    PINEAL MELATONIN LEVEL DISRUPTION IN HUMANS DUE TO ELECTROMAGNETIC FIELDS AND ICNIRP LIMITS Malka N) classifies electromagnetic fields (EMFs) as `possibly carcinogenic' to humans that might transform normal gland ac- tivity in the brain that regulates the body's sleep­wake cycle. How man-made EMFs may

  3. PARTICLE DISPLACEMENTS ON THE WALL OF A BOREHOLE FROM INCIDENT PLANE WAVES.

    USGS Publications Warehouse

    Lee, M.W.

    1987-01-01

    Particle displacements from incident plane waves at the wall of a fluid-filled borehole are formulated by applying the seismic reciprocity theorem to far-field displacement fields. Such displacement fields are due to point forces acting on a fluid-filled borehole under the assumption of long wavelengths. The displacement fields are analyzed to examine the effect of the borehole on seismic wave propagation, particularly for vertical seismic profiling (VSP) measurements. When the shortest wavelength of interest is approximately 25 times longer than the borehole's diameter, the scattered displacements are proportional to the first power of incident frequency and borehole diameter. When the shortest wavelength of interest is about 40 times longer than the borehole's diameter, borehole effects on VSP measurements using a wall-locking geophone are negligible.

  4. Energy shifts of Rydberg atoms due to patch fields near metal surfaces

    SciTech Connect

    Carter, J. D.; Martin, J. D. D. [Department of Physics and Astronomy and Institute for Quantum Computing, University of Waterloo, Waterloo, Ontario, N2L 3G1 (Canada)

    2011-03-15

    The statistical properties of patch electric fields due to a polycrystalline metal surface are calculated. The fluctuations in the electric field scale like 1/z{sup 2} when z>>w, where z is the distance to the surface and w is the characteristic length scale of the surface patches. For typical thermally evaporated gold surfaces these field fluctuations are comparable to the image field of an elementary charge, and scale in the same way with distance to the surface. Expressions for calculating the statistics of the inhomogeneous broadening of Rydberg-atom energies due to patch electric fields are presented. Spatial variations in the patch fields over the Rydberg orbit are found to be insignificant.

  5. Pull-in control due to Casimir forces using external magnetic fields

    NASA Astrophysics Data System (ADS)

    Esquivel-Sirvent, R.; Palomino-Ovando, M. A.; Cocoletzi, G. H.

    2009-08-01

    We present a theoretical calculation of the pull-in control in capacitive microswitches actuated by Casimir forces using external magnetic fields. The external magnetic fields induce an optical anisotropy due to the excitation of magnetoplasmons that reduces the Casimir force. The calculations are performed in the Voigt configuration and the results show that as the magnetic field increases the system becomes more stable. The detachment length for a cantilever is also calculated for a cantilever, showing that it increases with increasing magnetic field. At the pull-in separation, the stiffness of the system decreases with the increasing magnetic field.

  6. Pull-in control due to Casimir forces using external magnetic fields

    E-print Network

    R. Esquivel-Sirvent; M. A. Palomino-Ovando; G. H. Cocoletzi

    2009-07-13

    We present a theoretical calculation of the pull-in control in capacitive micro switches actuated by Casimir forces, using external magnetic fields. The external magnetic fields induces an optical anisotropy due to the excitation of magneto plasmons, that reduces the Casimir force. The calculations are performed in the Voigt configuration, and the results show that as the magnetic field increases the system becomes more stable. The detachment length for a cantilever is also calculated for a cantilever, showing that it increases with increasing magnetic field. At the pull-in separation, the stiffness of the system decreases with increasing magnetic field.

  7. Measuring vulnerability to disaster displacement

    NASA Astrophysics Data System (ADS)

    Brink, Susan A.; Khazai, Bijan; Power, Christopher; Wenzel, Friedemann

    2015-04-01

    Large scale disasters can cause devastating impacts in terms of population displacement. Between 2008 and 2013, on average 27 million people were displaced annually by disasters (Yonetani 2014). After large events such as hurricane Katrina or the Port-au-Prince earthquake, images of inadequate public shelter and concerns about large scale and often inequitable migration have been broadcast around the world. Population displacement can often be one of the most devastating and visible impacts of a natural disaster. Despite the importance of population displacement in disaster events, measures to understand the socio-economic vulnerability of a community often use broad metrics to estimate the total socio-economic risk of an event rather than focusing on the specific impacts that a community faces in a disaster. Population displacement is complex and multi-causal with the physical impact of a disaster interacting with vulnerability arising from the response, environmental issues (e.g., weather), cultural concerns (e.g., expectations of adequate shelter), and many individual factors (e.g., mobility, risk perception). In addition to the complexity of the causes, population displacement is difficult to measure because of the wide variety of different terms and definitions and its multi-dimensional nature. When we speak of severe population displacement, we may refer to a large number of displaced people, an extended length of displacement or associated difficulties such as poor shelter quality, risk of violence and crime in shelter communities, discrimination in aid, a lack of access to employment or other difficulties that can be associated with large scale population displacement. We have completed a thorough review of the literature on disaster population displacement. Research has been conducted on historic events to understand the types of negative impacts associated with population displacement and also the vulnerability of different groups to these impacts. We aggregate these ideas into a framework of disaster displacement vulnerability that distinguishes between three main aspects of disaster displacement. Disaster displacement can be considered in terms of the number of displaced people and the length of that displacement. However, the literature emphasizes that the severity of disaster displacement can not be measured completely in quantitative terms. Thus, we include a measure representing people who are trapped and unable to leave their homes due to mobility, resources or for other reasons. Finally the third main aspect considers the difficulties that are associated with displacement and reflects the difference between the experiences of those who are displaced into safe and supportive environments as compared to those whose only alternate shelter is dangerous and inadequate for their needs. Finally, we apply the framework to demonstrate a methodology to estimate vulnerability to disaster displacement. Using data from the Global Earthquake Model (GEM) Social and Economic Vulnerability sub-National Database, we generate an index to measure the vulnerability of Japanese prefectures to the dimensions of displacement included in the framework. References Yonitani, M. (2014). Global Estimates 2014: People displaced by disasters. http://www.internal-displacement.org/publications/2014/global-estimates-2014-people-displaced-by-disasters/

  8. Quasi-Static Strain and Stress Fields due to a Moment Tensor in Elastic-Viscoelastic Layered Half-Space

    NASA Astrophysics Data System (ADS)

    Hashima, Akinori; Fukahata, Yukitoshi; Hashimoto, Chihiro; Matsu'ura, Mitsuhiro

    2014-08-01

    We derived explicit expressions in the time domain for 3-D quasi-static strain and stress fields, due to a point moment tensor source in an elastic surface layer overlying viscoelastic half-space under gravity. The expressions of strain in the elastic surface layer were directly obtained from the expressions of displacement in our previous paper. The conversion of strain into stress is easy, because the stress-strain relation of elastic material is linear. In the viscoelastic substratum, the expressions of strain were obtained by applying the correspondence principle of linear viscoelasticity to the associated elastic solution. The strain-stress conversion is not straightforward, as the stress-strain relation of viscoelastic material is usually given in a differential form. To convert strain into stress, we used an integral form of the stress-strain relation instead of the usual differential form. The expressions give the responses of elastic half-space at , and the responses of an elastic plate floating on non-viscous liquid at . The moment tensor is rationally decomposed into the three independent force systems, corresponding to isotropic expansion, shear faulting and crack opening, and so the expressions include the strain and stress fields for these force systems as special cases. As the first numerical example, we computed the temporal changes in strain and stress fields after the sudden opening of an infinitely long vertical crack cutting the elastic surface layer. Here, we observe that the stress changes caused by the sudden crack opening gradually decay with time and vanish at everywhere. After the completion of stress relaxation, a characteristic pattern of shear strain remains in the viscoelastic substratum. Since the strain and stress fields at can be read as the strain- and stress-rate fields caused by steady crack opening, respectively, this numerical example demonstrates the realization of a steady stress state supported by steady viscous flow in the asthenosphere, associated with steady seafloor spreading at mid-ocean ridges. For the second numerical example, we computed the temporal changes in strain and stress fields after the 2011 Tohoku-oki mega-thrust earthquake, which occurred at the North American-Pacific plate interface. In this numerical example, the stress changes caused by coseismic fault slip vanish at in the viscoelastic substratum, but remain in the elastic surface layer. The coseismic stress changes (and also strain changes) in the elastic surface layer diffuse away from the source region with time, due to gradual stress relaxation in the viscoelastic substratum.

  9. The 1999 Hector Mine Earthquake, Southern California: Vector Near-Field Displacements from ERS InSAR

    NASA Technical Reports Server (NTRS)

    Sandwell, David T.; Sichoix, Lydie; Smith, Bridget

    2002-01-01

    Two components of fault slip are uniquely determined from two line-of-sight (LOS) radar interferograms by assuming that the fault-normal component of displacement is zero. We use this approach with ascending and descending interferograms from the ERS satellites to estimate surface slip along the Hector Mine earthquake rupture. The LOS displacement is determined by visually counting fringes to within 1 km of the outboard ruptures. These LOS estimates and uncertainties are then transformed into strike- and dip-slip estimates and uncertainties; the transformation is singular for a N-S oriented fault and optimal for an E-W oriented fault. In contrast to our previous strike-slip estimates, which were based only on a descending interferogram, we now find good agreement with the geological measurements, except at the ends of the rupture. The ascending interferogram reveals significant west-sidedown dip-slip (approximately 1.0 m) which reduces the strike-slip estimates by 1 to 2 m, especially along the northern half of the rupture. A spike in the strike-slip displacement of 6 m is observed in central part of the rupture. This large offset is confirmed by subpixel cross correlation of features in the before and after amplitude images. In addition to strike slip and dip slip, we identify uplift and subsidence along the fault, related to the restraining and releasing bends in the fault trace, respectively. Our main conclusion is that at least two look directions are required for accurate estimates of surface slip even along a pure strike-slip fault. Models and results based only on a single look direction could have major errors. Our new estimates of strike slip and dip slip along the rupture provide a boundary condition for dislocation modeling. A simple model, which has uniform slip to a depth of 12 km, shows good agreement with the observed ascending and descending interferograms.

  10. Calculation of the magnetic field due to a bioelectric current dipole in an ellipsoid

    Microsoft Academic Search

    Andrei Irimia

    2008-01-01

    The bioelectric current dipole model is important both theoretically and computationally in the study of electrical activity\\u000a in the brain and stomach due to the resemblance of the shape of these two organs to an ellipsoid. To calculate the magnetic\\u000a field B due to a dipole in an ellipsoid, one must evaluate truncated series expansions involving ellipsoidal harmonics $$\\u000a\\\\mathbb{E}_n^m

  11. Gyro-electron ghost images due to microchannel plate operation in transverse magnetic fields

    SciTech Connect

    Roquemore, A.L.; Medley, S.S.

    1986-06-01

    A multi-anode microchannel plate (MCP) detector was operated in a transverse magnetic field. When a collimated ion beam of approx.4-mm diameter impinged on one area of the plate, ghost images were observed elsewhere on the plate at anodes up to several centimeters from the beam spot. This effect is due to secondary electrons which are emitted from the interstitial surfaces around the MCP pores and returned to the surface of the plate under the influence of E-tilde X B-tilde fields, where E-tilde is the electric field perpendicular to the plate due to the MCP bias potential and B-tilde is the externally applied transverse magnetic field. A regenerative process is observed in which the secondary electrons traverse the surface of the plate in the E-tilde X B-tilde direction by successive gyro-orbit steps. A method for suppressing the ghost images is discussed.

  12. High-Field Slope in Superconducting Cavities Due to Magnetic Field Enhancement at Grain Boundaries

    Microsoft Academic Search

    J. Knobloch; R. L. Geng; M. Liepe; H. Padamsee

    Quality ( ) degradation of superconducting, field- emission-free cavities at high accelerating gradient ( acc MV\\/m) has been observed at a number of laboratories. This slope presents the main impediment to achieving gradients in excess of 25 MV\\/m needed for future super- conducting high-energy accelerators. Presented here are measurements and numerical simulations with SUPER- LANS and ANSYS that provide insight

  13. A Solution of the Einstein Equation in a Stationary Gravitational Field Due to a Rotating Source

    Microsoft Academic Search

    Osamu Tanimura; Shoichi Hori

    1999-01-01

    The stationary and axially symmetric gravitational field due to a rotating deformed source can be treated by the Ernst equation. We prove analytically the validity of the solution of the Ernst equation that was presented as a possible solution in a previous paper for arbitrary real values of the deformation parameter &delta. By means of analytic continuations of the solution

  14. Acoustic radiation force in tissue-like solids due to modulated sound field

    E-print Network

    Guzina, Bojan

    Acoustic radiation force in tissue-like solids due to modulated sound field Egor V. Dontsov, Bojan April 2012 Available online 23 May 2012 Keywords: Acoustic radiation force Nonlinear acoustics Modulated-called acoustic radiation force) in homogeneous tissue-like solids generated by an elevated-intensity, focused

  15. Fracture surface interference in shear. 2: Experimental measurements of crack tip displacement field under Mode II loading in 7075-T6 Al

    SciTech Connect

    Gross, T.S.; Watt, D.W. [Univ. of New Hampshire, Durham, NH (United States). Dept. of Mechanical Engineering] [Univ. of New Hampshire, Durham, NH (United States). Dept. of Mechanical Engineering; Zhang, Y. [Limco Manufacturing Corp., Glen Cove, NY (United States)] [Limco Manufacturing Corp., Glen Cove, NY (United States)

    1995-03-01

    The in-plane and out-of-plane displacement field around the tip of a crack (produced by Mode I fatigue precracking) loaded in pure, remote Mode II was measured as a function of K{sub IIapp} by electro-optic holographic interferometry. The effective Mode II stress intensity factor and the induced Mode I stress intensity factor were estimated from a fit to the near-tip expressions for the crack face displacement fields. The effective Mode II stress intensity factor was always less than the applied stress intensity factor demonstrating that the fracture surface asperities shield the crack tip. The induced Mode I stress intensity factor was roughly half that of the applied Mode II stress intensity factor, demonstrating that pure Mode II cracks cannot be obtained for cracks with microscopically rough surfaces. Plateaus and jumps in the dependence of the effective Mode II and induced Mode I stress intensity factor on the applied Mode II were correlated further supporting the notion that the fracture surface interference is based on asperity interactions. Analysis of the data shows that force transfer across the crack faces cannot be simply described by a frictional interaction across the asperities. It is suggested that deformation of the asperities must be considered to accurately model the shielding and induced crack face opening under remote Mode II loading.

  16. ANALYSIS OF HIGH FIELD NON-LINEAR LOSSES ON SRF SURFACES DUE TO SPECIFIC TOPOGRAPHIC ROUGHNESS

    SciTech Connect

    Chen Xu,Charles Reece,Michael Kelley

    2012-07-01

    The high-field performance of SRF cavities will eventually be limited by the realization of fundamental material limits, whether it is Hc1 or Hsh, or some derivative thereof, at which the superconductivity is lost. Before reaching this fundamental field limit at the macro level, it must be encountered at localized, perhaps microscopic, sites of field enhancement due to local topography. If such sites are small enough, they may produce thermally stabilized normal-conducting regions which contribute non-linear losses when viewed from the macro resonant field perspective, and thus produce degradation in Q0. We have undertaken a calculation of local surface magnetic field enhancement from specific fine topographic structure by conformal mapping method and numerically. A solution of the resulting normal conducting volume has been derived and the corresponding RF Ohmic loss simulated.

  17. Displacements, Strains, and Tilts at Teleseismic Distances

    Microsoft Academic Search

    1965-01-01

    The dislocation theory representation of faulting of Vvedenskaya, Steketee, Chin- nery, and Maruyama is used to compute the residual displacement, strain, and tilt fields at intermediate and large distances from major earthquakes. It is shown that the distant fields are large enough to be detected by modern instruments. The vertical displacement field from the Alaskan earthquake of March 27, 1964,

  18. The Surface Displacement Field of the November 8, 1997, Mw7.6 Manyi (Tibet) Earthquake Observed with ERS InSAR Data

    NASA Technical Reports Server (NTRS)

    Peltzer, G.; Crampe, F.

    1998-01-01

    ERS2 radar data acquired before and after the Mw7.6, Manyi (Tibet) earthquake of November 8, 1997, provide geodetic information about the surface displacement produced by the earthquake in two ways. (1) The sub-pixel geometric adjustment of the before and after images provides a two dimensional offset field with a resolution of approx, 1m in both the range (radar line of sight) and azimuth (satellite track) directions. Comparison of offsets in azimuth and range indicates that the displacement along the fault is essentially strike-slip and in a left-lateral sense. The offset map reveals a relatively smooth and straight, N78E surface rupture that exceeds 150 km in length, consistent with the EW plane of the Harvard CMT solution. The rupture follows the trace of a quaternary fault visible on satellite imagery (Tapponnier and Molnar, 1978; Wan Der Woerd, pers. comm.). (2) Interferometric processing of the SAR data provides a range displacement map with a precision of a few millimeters. The slip distribution along the rupture reconstructed from the range change map is a bell-shaped curve in the 100-km long central section of the fault with smaller, local maxima near both ends. The curve shows that the fault slip exceeds 2.2 m in range, or 6.2 in strike-slip, along a 30-km long section of the fault and remains above 1 m in range, approx. 3 m strike-slip, along most of its length. Preliminary forward modeling of the central section of the rupture, assuming a uniform slip distribution with depth, indicates that the slip occur-red essentially between 0 and the depth of 10 km, consistent with a relatively shallow event (Velasco et al., 1998).

  19. Dynamical Effects Due to Fringe Field of the Magnets in Circular Accelerators

    SciTech Connect

    Cai, Y.; Nosochkov, Yu.; /SLAC

    2005-05-16

    The leading Lie generators, including the chromatic effects, due to hard-edge fringe field of single multipole and solenoid are derived from the vector potentials within a Hamiltonian system. These nonlinear generators are applied to the interaction region of PEP-II to analyze the linear errors due to the feed-down from the off-centered quadrupoles and solenoid. The nonlinear effects of tune shifts at large amplitude, the synchro-betatron sidebands near half integer and their impacts on the dynamic aperture are studied in the paper.

  20. New Optical Scanning Tomography using a rotating slicing for time-resolved measurements of 3D full field displacements in structures

    NASA Astrophysics Data System (ADS)

    Morandi, P.; Brémand, F.; Doumalin, P.; Germaneau, A.; Dupré, J. C.

    2014-07-01

    In this paper, a new optical tomography process is presented. It has been developed for time-resolved measurement of kinematic fields in the whole volume of structure. This new process is based on the scan of the specimen by a plane laser beam submitted to a motion of rotation. Calibration and reconstruction steps have been established and are described in this document. Acquisition is achieved by illuminating successive slices in the specimen using a rotating plane laser beam and data are recorded with a single CCD camera. The recorded volumes are analyzed by Digital Volume Correlation to measure the three displacement components in the bulk. This new acquisition process is assessed by performing sub-voxel rigid body translations along the three axes. We discuss the quality of a reconstructed volume and also the measurement accuracy in terms of mean error and standard deviation through rigid body displacement tests. Results are compared with those obtained using classical Optical Scanning Tomography (OST) and using X-ray Tomography.

  1. CMB distortion anisotropies due to the decay of primordial magnetic fields

    NASA Astrophysics Data System (ADS)

    Miyamoto, Koichi; Sekiguchi, Toyokazu; Tashiro, Hiroyuki; Yokoyama, Shuichiro

    2014-03-01

    We investigate the power spectrum of the distortion of the cosmic microwave background (CMB) due to the decay of the primordial magnetic fields. It is known that there are two types of the CMB distortions, so-called ? and y types, and we find that the signal of the y-type distortion becomes larger than that of the ?-type one. We also discuss cross power spectra between the CMB distortions and the CMB temperature anisotropy, which are naturally generated due to the existence of the primordial magnetic fields. We find that such cross power spectra have small amplitudes compared with the autopower spectra of the CMB distortions because of the Silk damping effect of the temperature anisotropy. We also investigate the possibility of detecting such a signal in the future CMB experiments, including not only absolutely calibrated experiments such as PIXIE but also relatively calibrated experiments such as LiteBIRD and CMBpol.

  2. Underwater acoustic field and pressure fluctuation on ship hull due to unsteady propeller sheet cavitation

    Microsoft Academic Search

    Young-Zehr Kehr; Jui-Hsiang Kao

    The main objective of this paper is to develop an efficient numerical method which can predict the underwater acoustic field\\u000a and pressure fluctuation on a ship hull due to unsteady propeller sheet cavitation by linear acoustic theory. In addition,\\u000a the noise scattered from the ship hull and reflected from the free surface are included. Concerning the computation of the\\u000a acoustic

  3. A theory for the short-periodic motion due to the tesseral harmonic gravity field

    Microsoft Academic Search

    R. J. Proulx; W. D. McClain; L. W. Early; P. J. Cefola

    1981-01-01

    A model of the short-period motion of a satellite due to tesseral harmonic terms of the central gravity field is developed for inclusion in a semianalytical satellite theory for high-accuracy orbit prediction and determination problems. The generalized method of averaging is applied to the two-phase-angle tesseral harmonic problem to obtain complete first-order expressions for the short-period variations, which are then

  4. FIG. 2: Model results showing vertical and horizontal displacements due to the Hekla 2000 lava (disk, final relaxed response). Tickmarks in c are Lambert coordinates and describe the extend of the modeled area in meters. (a,d) and the Mogi model (b,e). Th

    E-print Network

    Grapenthin, Ronni

    FIG. 2: Model results showing vertical and horizontal displacements due to the Hekla 2000 lava the results of the Mogi model from the final relaxed response due to the Hekla lava. Note that the scale, Chambery, France contact: ronni@gi.alaska.edu AGU ­ V53C-1421 Abstract Modeling a circular lava flow

  5. Additional Enhancement of Electric Field in Surface-Enhanced Raman Scattering due to Fresnel Mechanism

    PubMed Central

    Jayawardhana, Sasani; Rosa, Lorenzo; Juodkazis, Saulius; Stoddart, Paul R.

    2013-01-01

    Surface-enhanced Raman scattering (SERS) is attracting increasing interest for chemical sensing, surface science research and as an intriguing challenge in nanoscale plasmonic engineering. Several studies have shown that SERS intensities are increased when metal island film substrates are excited through a transparent base material, rather than directly through air. However, to our knowledge, the origin of this additional enhancement has never been satisfactorily explained. In this paper, finite difference time domain modeling is presented to show that the electric field intensity at the dielectric interface between metal particles is higher for “far-side” excitation than “near-side”. This is reasonably consistent with the observed enhancement for silver islands on SiO2. The modeling results are supported by a simple analytical model based on Fresnel reflection at the interface, which suggests that the additional SERS signal is caused by near-field enhancement of the electric field due to the phase shift at the dielectric interface. PMID:23903714

  6. Gravity field due to a homogeneous oblate spheroid: Simple solution form and numerical calculations

    NASA Astrophysics Data System (ADS)

    Hvoždara, Milan; Kohút, Igor

    2011-01-01

    We present a simple derivation of the interior and exterior gravitational potentials due to oblate spheroid and also its gravity field components by using the fundamental solution of the Laplace equation in oblate spheroidal coordinates. Application of the method of separation of variables provides an expression for the potential in terms of oblate spheroidal harmonics of degree n = 0, 2. This solution is more concise and suitable for the numerical calculations in comparison with infinite series in spherical harmonics. Also presented are the computations in the form of potential isolines inside and outside the spheroid, as well as for the gravity field components. These reveal some interesting properties of the gravity field of this fundamental geophysical body useful for the applied gravimetry.

  7. Linearly polarized radiation from astrophysical masers due to magnetic fields of intermediate strength

    NASA Technical Reports Server (NTRS)

    Nedoluha, Gerald E.; Watson, William D.

    1990-01-01

    Previous solutions for polarization of astrophysical maser radiation due to closed-shell molecules in a magnetic field have potentially serious limitations. These solutions are mostly based on the approximation that the Zeeman frequency g-Omega is much greater than the rate for stimulated emission R and the rate for decay Gamma of the molecular state. Others are asymptotic solutions obtained for an angular momentum J = 1-0 transition. It has been unclear whether the polarizations due to plausible Zeeman splittings are adequately represented by the solutions obtained for g-Omega/Gamma much greater than 1 and g-Omega/R much greater than 1. Actual masing transitions tend to involve molecular states with angular momenta that are higher than J = 1 and 0. Numerical solutions for the linear polarization are presented here which do not have the foregoing restrictions on the g-Omega and which are not limited to a J = 1-0 transition.

  8. Simultaneous measurement of the microscopic dynamics and the mesoscopic displacement field in soft systems by speckle imaging

    E-print Network

    Luca Cipelletti; Giovanni Brambilla; Simona Maccarrone; Sami Caroff

    2013-06-18

    The constituents of soft matter systems such as colloidal suspensions, emulsions, polymers, and biological tissues undergo microscopic random motion, due to thermal energy. They may also experience drift motion correlated over mesoscopic or macroscopic length scales, \\textit{e.g.} in response to an internal or applied stress or during flow. We present a new method for measuring simultaneously both the microscopic motion and the mesoscopic or macroscopic drift. The method is based on the analysis of spatio-temporal cross-correlation functions of speckle patterns taken in an imaging configuration. The method is tested on a translating Brownian suspension and a sheared colloidal glass.

  9. Numerical evaluation of electromagnetic fields due to dipole antennas in the presence of stratified media

    NASA Technical Reports Server (NTRS)

    Tsang, L.; Brown, R.; Kong, J. A.; Simmons, G.

    1974-01-01

    Two numerical methods are used to evaluate the integrals that express the em fields due to dipole antennas radiating in the presence of a stratified medium. The first method is a direct integration by means of Simpson's rule. The second method is indirect and approximates the kernel of the integral by means of the fast Fourier transform. In contrast to previous analytical methods that applied only to two-layer cases the numerical methods can be used for any arbitrary number of layers with general properties.

  10. Heating rate and spin flip lifetime due to near field noise in layered superconducting atom chips

    E-print Network

    Rachele Fermani; Tobias Mueller; Bo Zhang; Michael J. Lim; Rainer Dumke

    2009-12-11

    We theoretically investigate the heating rate and spin flip lifetimes due to near field noise for atoms trapped close to layered superconducting structures. In particular, we compare the case of a gold layer deposited above a superconductor with the case of a bare superconductor. We study a niobium-based and a YBCO-based chip. For both niobium and YBCO chips at a temperature of 4.2 K, we find that the deposition of the gold layer can have a significant impact on the heating rate and spin flip lifetime, as a result of the increase of the near field noise. At a chip temperature of 77 K, this effect is less pronounced for the YBCO chip.

  11. Saturation of a longitudinal instability due to nonlinearity of the wake field

    SciTech Connect

    Krinsky, S.

    1985-01-01

    Self-sustained synchrotron oscillations are observed in electron storage rings. In general the theoretical description of the saturation of an instability for large oscillation amplitude is a difficult problem, and techniques have not yet been developed which yield analytic approximations to the appropriate nonlinear Vlasov or Fokker-Planck equations. In this paper, a single point bunch interacting with the wake field from a single resonant mode of an rf cavity is considered, and the averaging method of Bogoliubov and Mitropolsky is used to study the saturation of the initial exponential growth of the oscillation amplitude, due to the nonlinearity of the wake field. The determination of the limiting amplitude of oscillation is discussed both in the presence and in the absence of radiation damping.

  12. Critical displacement for unlimited displacement of earthquake-induced landslides

    NASA Astrophysics Data System (ADS)

    Fukuoka, H.; Karnawati, D.; Dok, A.

    2012-04-01

    The 30 September 2009 Padang Earthquake not only affected the buildings and infrastructure of the city, but also induced numerous landslides in the remote hill slopes. (1) A lot of shallow landslides took place along the southern crater rim of the lake Singkarak. Some of them were fluidized and ran as debris flows. (2) In a small town, located south of the lake, several large scale and long run-out landslides took place on hill slopes of pumiceous materials and claimed as many casualties. Those sands were sampled in a landslide deposits and tested by undrained ring shear apparatus by applying cyclic loading with corresponding static normal stress and shear stress. We found that about 5 cm could be the critical shear displacement when the shear resistance get smaller than shear stress due to excess pore pressure generation and thereafter unlimited displacement would appear. The critical displacement may depends on the saturation degree, static stresses acting on the slope, material, density, etc.

  13. A time dependent dielectric breakdown model for field accelerated low-k breakdown due to copper ions

    NASA Astrophysics Data System (ADS)

    Achanta, Ravi S.; Plawsky, Joel L.; Gill, William N.

    2007-12-01

    We have previously shown that the choice of J(t ,L)=0 boundary condition in the model of copper ion drift causes an internal field enhancement at the cathode due to the accumulation of copper ions. The ultimate breakdown of the dielectric occurs due to a combination of the field increase exceeding the intrinsic breakdown strength as well as the intrinsic bond breakage due to thermal and field effects. Here, we show that the field dependence of the intrinsic bond breakage shows an E2 dependence in the presence of copper ions enabling an excellent fit to the failure data on Cu /SiO2/Si devices.

  14. THE DISPLACEMENTS OF ANCHORED DIAPHRAGM WALLS

    Microsoft Academic Search

    ANNA SIEMI?SKA-LEWANDOWSKA

    Due to the influence of the engineering works on buildings in the vicinity of deep excava- tions, two large Warsaw underground stations were constantly monitored. The results of measurements of the displacements of diaphragm walls are presented. Assessment of displacements was carried out on the basis of high-precision land surveying of fixed points positioned on diaphragm walls. The conclu- sions

  15. The use of a displacement device negatively affects the performance of dogs (Canis familiaris) in visible object displacement tasks

    PubMed Central

    Müller, Corsin A.; Riemer, Stefanie; Range, Friederike; Huber, Ludwig

    2014-01-01

    Visible and invisible displacement tasks have been used widely for comparative studies of animals’ understanding of object permanence, with evidence accumulating that some species can solve invisible displacement tasks and thus reach Piagetian stage 6 of object permanence. In contrast, dogs appear to rely on associative cues, such as the location of the displacement device, during invisible displacement tasks. It remains unclear, however, whether dogs, and other species that failed in invisible displacement tasks, do so due to their inability to form a mental representation of the target object, or simply due to the involvement of a more salient but potentially misleading associative cue, the displacement device. Here we show that the use of a displacement device impairs the performance of dogs also in visible displacement tasks: their search accuracy was significantly lower when a visible displacement was performed with a displacement device, and only two of initially 42 dogs passed the sham-baiting control conditions. The negative influence of the displacement device in visible displacement tasks may be explained by strong associative cues overriding explicit information about the target object’s location, reminiscent of an overshadowing effect, and/or object individuation errors as the target object is placed within the displacement device and moves along a spatiotemporally identical trajectory. Our data suggest that a comprehensive appraisal of a species’ performance in object permanence tasks should include visible displacement tasks with the same displacement device used in invisible displacements, which typically has not been done in the past. PMID:24611641

  16. Strategies for displacing oil

    NASA Astrophysics Data System (ADS)

    Rao, Vikram; Gupta, Raghubir

    2015-03-01

    Oil currently holds a monopoly on transportation fuels. Until recently biofuels were seen as the means to break this stranglehold. They will still have a part to play, but the lead role has been handed to natural gas, almost solely due to the increased availability of shale gas. The spread between oil and gas prices, unprecedented in its scale and duration, will cause a secular shift away from oil as a raw material. In the transport fuel sector, natural gas will gain traction first in the displacement of diesel fuel. Substantial innovation is occurring in the methods of producing liquid fuel from shale gas at the well site, in particular in the development of small scale distributed processes. In some cases, the financing of such small-scale plants may require new business models.

  17. GEOPHYSICAL RESEARCH LETTERS, VOL. 26, NO. 9, PAGES 1247-1250, MAY 1, 1999 Mesospheric Electric Field Transients due to

    E-print Network

    Pasko, Victor

    and quantitative two-dimen- sional electromagnetic modeling of mesospheric electric field transients produced Field Transients due to Tropospheric Lightning Discharges Victor P. Pasko, Umran S. Inan, and Timothy F to be produced by large electromagnetic fields capable of initiating breakdown ion- ization at mesospheric

  18. Membrane Permeabilization in Relation to Inactivation Kinetics of Lactobacillus Species due to Pulsed Electric Fields

    PubMed Central

    Wouters, Patrick C.; Bos, Ad P.; Ueckert, Joerg

    2001-01-01

    Membrane permeabilization due to pulsed electric field (PEF) treatment of gram-positive Lactobacillus cells was investigated by using propidium iodide uptake and single-cell analysis with flow cytometry. Electric field strength, energy input, treatment time, and growth phase affected membrane permeabilization of Lactobacillus plantarum during PEF treatment. A correlation between PEF inactivation and membrane permeabilization of L. plantarum cells was demonstrated, whereas no relationship was observed between membrane permeabilization and heat inactivation. The same results were obtained with a Lactobacillus fermentum strain, but the latter organism was more PEF resistant and exhibited less membrane permeabilization, indicating that various bacteria have different responses to PEF treatment. While membrane permeabilization was the main factor involved in the mechanism of inactivation, the growth phase and the acidity of the environment also influenced inactivation. By using flow cytometry it was possible to sort cells in the L. plantarum population based on different cell sizes and shapes, and the results were confirmed by image analysis. An apparent effect of morphology on membrane permeabilization was observed, and larger cells were more easily permeabilized than smaller cells. In conclusion, our results indicate that the ability of PEF treatment to cause membrane permeabilization is an important factor in determining inactivation. This finding should have an effect on the final choice of the processing parameters used so that all microorganisms can be inactivated and, consequently, on the use of PEF treatment as an alternative method for preserving food products. PMID:11425727

  19. An assessment of variation due to laboratory and field conditions in the measurement of radionuclides

    NASA Astrophysics Data System (ADS)

    Parkinson, J. A.; Horrill, A. D.

    1984-06-01

    One of the main problems associated with environmental studies is due to the large amount of variation encountered in field materials. Data obtained during studies into the distribution and movement of radionuclides in terrestrial environments in West Cumbria was found to be suitable for assessments of both spatial and analytical variation. Plutonium measurements on vegetation samples taken from samples of grazed and ungrazed saltmarsh and pasture fields having different management regimes were used in the assessment. Bulk samples of Halimione portulacoides and Pteridium aquilinum were analysed 14 and 11 times respectively and gave coefficients of variation of 9.18% and 7.91%. These were considered to be realistic estimates of analytical variability. Coefficients of variation for results of single plutonium determinations on replicate samples obtained from the pasture sites ranged from 23.4% to 33.1%. The data indicated that for the mean value obtained for a site to fall within 10% of the true mean at 95% probability, the numbers of samples to be taken at these sites ranged from 22 to 44. The grazed and ungrazed saltmarsh sites gave coefficients of variation of 95.70% and 47.2% respectively. These sites, however, would be stratified into vegetation classes, within class coefficients of variation being much lower at 16-24%.

  20. Magnetic field-aligned potential drops due to electrostatic ion cyclotron turbulence

    Microsoft Academic Search

    M. K. Hudson; R. L. Lysak; F. S. Mozer

    1978-01-01

    Measurements of DC and AC electric fields and plasma densities on the S3-3 satellite have shown that electrostatic ion cyclotron (EIC) turbulence is associated with significant DC electric fields parallel to auroral field lines. The EIC mode has been identified in regions of strong DC electric fields and magnetic field aligned currents by AC electric field and density fluctuations with

  1. Improving detection and identification of seismic signals due to landslides: a methodology based on field scale controlled experiments

    NASA Astrophysics Data System (ADS)

    Yfantis, G.; Carvajal, H. E.; Pytharouli, S.; Lunn, R. J.

    2013-12-01

    A number of published studies use seismic sensors to understand the physics involved in slope deformation. In this research we artificially induce failure to two meter scaled slopes in the field and use 12 short period 3D seismometers to monitor the failure. To our knowledge there has been no previous controlled experiments that can allow calibration and validation of the interpreted seismic signals. Inside the body of one of the artificial landslides we embed a pile of glass shards. During movement the pile deforms emitting seismic signals due to friction among the glass shards. Our aim is twofold: First we investigate whether the seismic sensors can record pre-cursory and failure signals. Secondly, we test our hypothesis that the glass shards produce seismic signals with higher amplitudes and a distinct frequency pattern, compared to those emitted by common landslide seismicity and local background noise. Two vertical faces, 2m high, were excavated 3m apart in high porous tropical clay. This highly attenuating material makes the detection of weak seismic signals challenging. Slope failure was induced by increasing the vertical load at the landslide's crown. Special care was taken in the design of all experimental procedures to not add to the area's seismic noise. Measurements took place during 18 hours (during afternoon and night) without any change in soil and weather conditions. The 3D sensors were placed on the ground surface close to the crown, forming a dense microseismic network with 5-to-10m spacing and two nanoseismic arrays, with aperture sizes of 10 and 20 m. This design allowed a direct comparison of the recorded signals emitted by the two landslides. The two faces failed for loading between 70 and 100kN and as a result the pile of glass shards was horizontally deformed allowing differential movement between the shards. After the main failure both landslides were continuing to deform due to soil compaction and horizontal displacement. We apply signal processing techniques to identify and locate the emitted signals related to slope movement, despite high background noise levels and high attenuating geological conditions. Results were groundproofed by visual observations. Our study shows that short period seismic sensors can successfully monitor the brittle behaviour of dry clays for deformations larger than 1 centimetre, as well as weak ground failures. The use of glass, or any other coarse and brittle material, has advantages over soil only, since the friction among the glass shards allows for a more distinct frequency pattern. This makes detection of slope movements easier at heterogeneous environments were signals are emitted following movements of different material types as well as in areas characterised by high background noise levels. Our results provide information on the slope behaviour, a powerful tool for geotechnical engineering applications.

  2. Parametric Study of Preferential Ion Heating Due to Intermittent Magnetic Fields in the Solar Wind

    NASA Astrophysics Data System (ADS)

    Carbajal Gomez, L.; Chapman, S. C.; Dendy, R. O.; Watkins, N. W.

    2014-12-01

    In situ observations and remote measurements of the solar wind show strong preferential heating of ions along the ambient magnetic field. Understanding the mechanism for this heating process is an open problem. The observed broad-band spectrum of Alfven waves permeating the fast solar wind provide a candidate mechanism for this preferential heating through wave-particle interactions on ion kinetic scales. Previous analytical and numerical studies have considered a single pump wave [1, 2] or a turbulent, broad-band spectra of Alfven waves [3, 4, 5] to drive the ion heating. The latter studies investigated the effects on ion heating due to different initial 1/f?power spectral exponents and number of modes and the signals were random phase. However, the observed solar wind fluctuations are intermittent so that the phases of the modes comprising the power spectrum are not random. Non-Gaussian fluctuations are seen both on scales identified with the inertial range of Alfvenic turbulence [6], and on longer scales typified by '1/f' spectra [7]. We present results of the first parametric numerical simulations on the effects of different levels of intermittency of the broad-band spectra of Alfven waves on the preferential heating of ions in the solar wind. We performed hybrid simulations for the local heating of the solar wind, which resolves the full kinetic physics of the ions and treats the electrons as a charge-neutralizing fluid. Our simulations evolve the full vector velocities and electromagnetic fields in one configuration space coordinate and in time.We compare the efficiency of different levels of intermittency of the initial turbulent fields and their effect on the efficiency of the wave-particle interactions which are a mechanism for driving preferential ion heating in the solar wind. [1] J. A. Araneda, E. Marsh, A. F. Viñas, J. Geophys. Res. 112, A04104 (2007). [2] J. A. Araneda, E. Marsh, A. F. Viñas, Phys. Rev. Lett. 100, 125003 (2008) [3] Y. G. Maneva, A. F. Viñas, L. Ofman, J. Geophys. Res. 118, 2842 (2013). [4] L. Ofman, J. Geophys. Res. 115, 1461 (2010). [5] L. Ofman, S. P. Gary, A. Viñas, J. Geophys. Res. 107, 1461 (2002). [6] R. Bruno, V. Carbone, Living Rev. Solar Phys. 10, 2 (2013). [7] R. M. Nicol, S. C. Chapman, R. O. Dendy, The Astrophysical Journal 703, 2138 (2009).

  3. Precision displacement reference system

    DOEpatents

    Bieg, Lothar F. (Albuquerque, NM); Dubois, Robert R. (Albuquerque, NM); Strother, Jerry D. (Edgewood, NM)

    2000-02-22

    A precision displacement reference system is described, which enables real time accountability over the applied displacement feedback system to precision machine tools, positioning mechanisms, motion devices, and related operations. As independent measurements of tool location is taken by a displacement feedback system, a rotating reference disk compares feedback counts with performed motion. These measurements are compared to characterize and analyze real time mechanical and control performance during operation.

  4. A geometric method to determine the direction of electric field due to a uniformly charged line segment

    E-print Network

    Zuo, Fulin

    2014-01-01

    A geometrical approach to calculate the electric field due to a uniformly charged rod is presented. The result is surprisingly simple and elegant. Using pure geometrical quantities like length and angle, the direction of the electric field in this charge configuration can be graphically defined. Understanding and application of this result can lead to a deeper appreciation of symmetry in a seemingly unsymmetric system.

  5. Tsunami generation by horizontal displacement of ocean bottom

    Microsoft Academic Search

    Yuichiro Tanioka; Kenji Satake

    1996-01-01

    Tsunami generation by an earthquake is generally modeled by water surface displacement identical to the vertical deformation of ocean bottom due to faulting. The effect of horizontal deformation is usually neglected. However, when the tsunami source is on a steep slope and the horizontal displacement is large relative to the vertical displacement, the effect becomes significant. We show this for

  6. Probing the mechanical properties of seismically active crust with space geodesy: Study of the coseismic deformation due to the 1992 Mw7.3 Landers (southern California) earthquake

    Microsoft Academic Search

    Yuri Fialko

    2004-01-01

    The coseismic deformation due to the 1992 Mw7.3 Landers earthquake, southern California, is investigated using synthetic aperture radar (SAR) and Global Positioning System (GPS) measurements. The ERS-1 satellite data from the ascending and descending orbits are used to generate contiguous maps of three orthogonal components (east, north, up) of the coseismic surface displacement field. The coseismic displacement field exhibits symmetries

  7. Non-incremental interferometric displacement measurement using a laser Doppler sensor with phase coding

    NASA Astrophysics Data System (ADS)

    Günther, P.; Pfister, T.; Czarske, J.

    2011-09-01

    The inspection of fast rotating objects with rough surfaces is an important task in the emerging field of process control. However, this is challenging since fast and non-contact inspection techniques with a measurement uncertainty in the nanometer range are often required. We present a novel optical sensor allowing non-incremental interferometric displacement measurement of moving solid state objects with rough surfaces. It features three wavelength coded interference fringe systems which are superposed slightly tilted. The displacement is determined by evaluating the phase shift between the resulting scattered light signals. Experimentally, a measurement uncertainty of 660 nm was obtained. This displacement uncertainty is independent of the lateral object velocity in principle. Due to this unique feature, the sensor can be utilized advantageously for precise displacement and vibration measurements of high speed objects as demonstrated by vibration measurements at a turbo pump shaft rotating with 48 000 rpm.

  8. Heating in the MRI environment due to superparamagnetic fluid suspensions in a rotating magnetic field

    E-print Network

    Cantillon-Murphy, Padraig

    In the presence of alternating-sinusoidal or rotating magnetic fields, magnetic nanoparticles will act to realign their magnetic moment with the applied magnetic field. The realignment is characterized by the nanoparticle's ...

  9. Autonomous dynamic displacement estimation from data fusion of acceleration and intermittent displacement measurements

    NASA Astrophysics Data System (ADS)

    Kim, Junhee; Kim, Kiyoung; Sohn, Hoon

    2014-01-01

    Addressing the importance of displacement measurement of structural responses in the field of structural health monitoring, this paper presents an autonomous algorithm for dynamic displacement estimation from acceleration integration fused with displacement data intermittently measured. The presented acceleration integration algorithm of multi-rate Kalman filtering distinguishes itself from the past study in the literature by explicitly considering acceleration measurement bias. Furthermore, the algorithm is formulated by unique state definition of integration errors and error dynamics system modeling. To showcase performance of the algorithm, a series of laboratory dynamic experiments for measuring structural responses of acceleration and displacement are conducted. Improved results are demonstrated through comparison between the proposed and past study.

  10. GEOPHYSICAL RESEARCH LETTERS, VOL. 28, NO. 16, PAGES 3063-3066, AUGUST 15, 2001 The complete (3-D) surface displacement field in the

    E-print Network

    Fialko, Yuri

    . We use Interferometric Synthetic Aperture Radar (InSAR) data to derive continuous maps for three with respect to the fault plane, consistent with predictions of linear elastic mod- els of deformation for a strike-slip fault. Some deviations from symmetry apparent in the surface displacement data may result

  11. Electric field enhancement due to a saw-tooth asperity in a channel and implications on microscale gas breakdown

    NASA Astrophysics Data System (ADS)

    Venkattraman, Ayyaswamy

    2014-10-01

    The electric field enhancement due to an isolated saw-tooth asperity in an infinite channel is considered with the goal of providing some inputs to the choice of field enhancement factors used to describe microscale gas breakdown. The Schwarz–Christoffel transformation is used to map the interior of the channel to the upper half of the transformed plane. The expression for the electric field in the transformed plane is then used to determine the electric field distribution in the channel as well as field enhancement near the asperity. The effective field enhancement factor is determined and its dependence on operating and geometrical parameters is studied. While the effective field enhancement factor depends only weakly on the height of the asperity in comparison to the channel, it is influenced significantly by the base angles of the asperity. Due to the strong dependence of field emission current density on electric field, the effective field enhancement factor (?eff) is shown to vary rapidly with the applied electric field irrespective of the geometrical parameters. This variation is included in the analysis of microscale gas breakdown and compared with results obtained using a constant ?eff as is done traditionally. Even though results for a varying ?eff may be approximately reproduced using an equivalent constant ?eff independent of E-field, it might be important for a range of operating conditions. This is confirmed by extracting ?eff from experimental data for breakdown in argon microgaps with plane-parallel cathodes and comparing its dependence on the E-field. While the use of two-dimensional asperities is shown to be a minor disadvantage of the proposed approach in its current form, it can potentially help in developing predictive capabilities as opposed to treating ?eff as a curve-fitting parameter.

  12. Primary beam steering due to field leakage from superconducting SHMS magnets

    DOE PAGESBeta

    Moore, M H; Waidyawansa, B P; Covrig, S; Carlini, R; Benesch, J

    2014-11-01

    Simulations of the magnetic fields from the Super High Momentum Spectrometer in Hall C at Thomas Jefferson National Accelerator Facility show significant field leakage into the region of the primary beam line between the target and the beam dump. Without mitigation, these remnant fields will steer the unscattered beam enough to limit beam operations at small scattering angles. Presented here are magnetic field simulations of the spectrometer magnets and a solution using optimal placement of a minimal amount of shielding iron around the beam line.

  13. Primary Beam Steering Due to Field Leakage from Superconducting SHMS Magnets

    E-print Network

    Michael H. Moore; Buddhini P. Waidyawansa; Silviu Covrig; Roger Carlini; Jay Benesch

    2014-08-26

    Simulations of the magnetic fields from the Super High Momentum Spectrometer in Hall C at Thomas Jefferson National Accelerator Facility show significant field leakage into the region of the primary beam line between the target and the beam dump. Without mitigation, these remnant fields will steer the unscattered beam enough to limit beam operations at small scattering angles. Presented here are magnetic field simulations of the spectrometer magnets and a solution using optimal placement of a minimal amount of shielding iron around the beam line.

  14. Computation of Transient Electromagnetic Fields Due to Switching in High-Voltage Substations

    Microsoft Academic Search

    Bukar Umar Musa; Wah Hoon Siew; Martin D. Judd

    2010-01-01

    Switching operations of circuit breakers and disconnect switches radiate transient electromagnetic fields within high-voltage substations. The generated fields may interfere and disrupt normal operations of electronic equipment. Hence, the electromagnetic compatibility (EMC) of this electronic equipment has to be considered as early as the design stage of substation planning and operation. Also, microelectronics are being introduced into the substation environment

  15. Cancellation of the ion deflection due to electron-suppression magnetic field in a negative-ion accelerator

    SciTech Connect

    Chitarin, G., E-mail: chitarin@igi.cnr.it [Consorzio RFX, Association EURATOM-ENEA, Corso Stati Uniti 4, 35127 Padova (Italy); Dept. of Management and Engineering, University of Padova, Strad. S. Nicola 3, 36100 Vicenza (Italy); Agostinetti, P.; Aprile, D.; Marconato, N.; Veltri, P. [Consorzio RFX, Association EURATOM-ENEA, Corso Stati Uniti 4, 35127 Padova (Italy)] [Consorzio RFX, Association EURATOM-ENEA, Corso Stati Uniti 4, 35127 Padova (Italy)

    2014-02-15

    A new magnetic configuration is proposed for the suppression of co-extracted electrons in a negative-ion accelerator. This configuration is produced by an arrangement of permanent magnets embedded in one accelerator grid and creates an asymmetric local magnetic field on the upstream and downstream sides of this grid. Thanks to the “concentration” of the magnetic field on the upstream side of the grid, the resulting deflection of the ions due to magnetic field can be “intrinsically” cancelled by calibrating the configuration of permanent magnets. At the same time, the suppression of co-extracted electrons can be improved.

  16. The effect of space charge fields due to finite length electron beams in the free-electron laser

    NASA Technical Reports Server (NTRS)

    Tang, C.-M.; Sprangle, P.; Freund, H.; Colson, W.

    1982-01-01

    The space charge electric field of a finite length electron beam in the free electron laser amplifier with a tapered wiggler is analyzed. In the free drift region between the accelerator and laser, expressions for the increase of energy spread due to the self field are presented. In the FEL interaction region, the general conditions on the importance of the self electric field in the equations of motion is obtained. A numerical example of the FEL experiment at 10.6 microns is given.

  17. Complete Solution of the Ernst Eequation in a Stationary and Axially Symmetric Gravitational Field Due to a Rotating Source

    Microsoft Academic Search

    Osamu Tanimura; Shoichi Hori

    1999-01-01

    We present a systematic and analytic solution of the Ernst equation in stationary and axially symmetric gravitational fields due to a rotating deformed source. This solution is transformed by means of an analytic continuation so as to be valid for any type and magnitude of deformation of the source and for any velocity of the rotation. It is clarified how

  18. Electromagnetic fields due to a horizontal electric dipole antenna laid on the surface of a two-layer medium

    NASA Technical Reports Server (NTRS)

    Tsang, L.; Kong, J. A.

    1974-01-01

    With applications to geophysical subsurface probings, electromagnetic fields due to a horizontal electric dipole laid on the surface of a two-layer medium are solved by a combination of analytic and numerical methods. Interference patterns are calculated for various layer thickness. The results are interpreted in terms of normal modes, and the accuracies of the methods are discussed.

  19. Non-rigid image registration using a median-filtered coarse-to-fine displacement field and a symmetric correlation ratio

    NASA Astrophysics Data System (ADS)

    Lau, Yiu H.; Braun, Michael; Hutton, Brian F.

    2001-04-01

    Conventional approaches to image registration are generally limited to image-wide rigid transformations. However, the body and its internal organs are non-rigid structures that change shape due to changes in the body's posture during image acquisition, and due to normal, pathological and treatment-related variations. Inter-subject matching also constitutes a non-rigid registration problem. In this paper, we present a fully automated non-rigid image registration method that maximizes a local voxel-based similarity metric. Overlapping image blocks are defined on a 3D grid. The transformation vector field representing image deformation is found by translating each block so as to maximize the local similarity measure. The resulting sparsely sampled vector field is median filtered and interpolated by a Gaussian function to ensure a locally smooth transformation. A hierarchical strategy is adopted to progressively establish local registration associated with image structures at diminishing scale. Simulation studies were carried out to evaluate the proposed algorithm and to determine the robustness of various voxel-based cost functions. Mutual information, normalized mutual information, correlation ratio (CR) and a new symmetric version of CR were evaluated and compared. A T1-weighted magnetic resonance (MR) image was used to test intra-modality registration. Proton density and T2-weighted MR images of the same subject were used to evaluate inter-modality registration. The proposed algorithm was tested on the 2D MR images distorted by known deformations and 3D images simulating inter-subject distortions. We studied the robustness of cost functions with respect to image sampling. Results indicate that the symmetric CR gives comparable registration to mutual information in intra- and inter-modality tasks at full sampling and is superior to mutual information in registering sparsely sampled images.

  20. Electromagnetic field generation in the downstream of electrostatic shocks due to electron trapping.

    PubMed

    Stockem, A; Grismayer, T; Fonseca, R A; Silva, L O

    2014-09-01

    A new magnetic field generation mechanism in electrostatic shocks is found, which can produce fields with magnetic energy density as high as 0.01 of the kinetic energy density of the flows on time scales ?10(4)?pe-1. Electron trapping during the shock formation process creates a strong temperature anisotropy in the distribution function, giving rise to the pure Weibel instability. The generated magnetic field is well confined to the downstream region of the electrostatic shock. The shock formation process is not modified, and the features of the shock front responsible for ion acceleration, which are currently probed in laser-plasma laboratory experiments, are maintained. However, such a strong magnetic field determines the particle trajectories downstream and has the potential to modify the signatures of the collisionless shock. PMID:25238365

  1. Kilotesla Magnetic Field due to a Capacitor-Coil Target Driven by High Power Laser

    PubMed Central

    Fujioka, Shinsuke; Zhang, Zhe; Ishihara, Kazuhiro; Shigemori, Keisuke; Hironaka, Youichiro; Johzaki, Tomoyuki; Sunahara, Atsushi; Yamamoto, Naoji; Nakashima, Hideki; Watanabe, Tsuguhiro; Shiraga, Hiroyuki; Nishimura, Hiroaki; Azechi, Hiroshi

    2013-01-01

    Laboratory generation of strong magnetic fields opens new frontiers in plasma and beam physics, astro- and solar-physics, materials science, and atomic and molecular physics. Although kilotesla magnetic fields have already been produced by magnetic flux compression using an imploding metal tube or plasma shell, accessibility at multiple points and better controlled shapes of the field are desirable. Here we have generated kilotesla magnetic fields using a capacitor-coil target, in which two nickel disks are connected by a U-turn coil. A magnetic flux density of 1.5?kT was measured using the Faraday effect 650??m away from the coil, when the capacitor was driven by two beams from the GEKKO-XII laser (at 1?kJ (total), 1.3?ns, 0.53 or 1??m, and 5 × 1016?W/cm2). PMID:23378905

  2. Primary Beam Steering Due To Field Leakage From Superconducting SHMS Magnets

    NASA Astrophysics Data System (ADS)

    Moore, Michael; Covrig, Silviu; Carlini, Roger; Waidyawansa, Buddhini; Benesch, Jay

    2014-03-01

    The Super High Momentum Spectrometer (SHMS) was designed for the 12 GeV/c physics program in Hall C at Thomas Jefferson National Accelerator (JLab). At JLab an electron beam impinges on a fixed target and scattered particles are analyzed with magnetic spectrometers. The SHMS angular acceptance is 5 .5° <= ? <=40° . When positioned at ? = 5 .5° and full field strength the external fields from the magnets are large enough to steer the unscattered primary beam away from the beam dump window located 51.8 m from the target. The effects of these magnetic fields on the primary beam line downstream of the target are studied using Opera 3-D and TOSCA. A solution is presented that uses passive elements to shape these fields and assure that the primary beam is steered onto the beam dump window.

  3. Far-field sheaths due to fast waves incident on material boundaries

    SciTech Connect

    D'Ippolito, D. A. [Lodestar Research Corporation; Myra, J. R. [Lodestar Research Corporation; Jaeger, Erwin Frederick [ORNL; Berry, Lee A [ORNL

    2008-10-01

    The problem of far-field sheath formation is studied with a new quantitative 1D model. These sheaths occur when unabsorbed fast waves (FW) are incident on a conducting surface not aligned with a flux surface. Use of a nonlinear sheath BC gives self-consistent solutions for the wave fields and sheath, and incorporates a sheath plasma wave (SPW) resonance which enhances the sheath potential. The model is applied to edge fields computed by the AORSA-1D full-wave code for a typical D(H) minority heating scenario. This work indicates the conditions under which far-field sheaths can explain some of the 'missing power' (low heating efficiency) and rf-specific impurity generation in ICRF experiments.

  4. Far Field Sheaths Due to Fast Waves Incident on Material Boundaries

    SciTech Connect

    D'Ippolito, D. A.; Myra, J. R. [Lodestar Research Corporation, Boulder, Colorado (United States); Jaeger, E. F.; Berry, L. A. [ORNL, Oak Ridge, Tennessee (United States)

    2007-09-28

    The problem of far-field sheath formation is studied with a new quantitative 1D model. These sheaths occur when unabsorbed fast waves (FW) are incident on a conducting surface not aligned with a flux surface. Use of a nonlinear sheath BC gives self-consistent solutions for the wave fields and sheath, and incorporates a sheath plasma wave (SPW) resonance which enhances the sheath potential. The model is applied to edge fields computed by the AORSA-1D full-wave code for a typical D(H) minority heating scenario. This work indicates the conditions under which far-field sheaths can explain some of the 'missing power' (low heating efficiency) and rf-specific impurity generation in ICRF experiments.

  5. Origin of Magnetic Fields in the Universe Due to Nonminimal Gravitational-Electromagnetic Coupling

    E-print Network

    R. Opher; U. F. Wichoski

    1997-01-28

    Basically the only existing theories for the creation of a magnetic field B in the Universe are the creation of a seed field of order 10^{-20} G in spiral galaxy which is subsequently supposedly amplified up to the observed 10^{-6} - 10^{-5} G by a dynamo process or a seed intergalactic field of magnitude 10^{-12} - 10^{-10} G which is amplified by collapse and differential rotation. No satisfactory dynamo theory, however, exists today. We show that a 10^{-6} - 10^{-5} G magnetic field in spiral galaxies is directly obtained from a nonminimal gravitational-electromagnetic coupling, without the need of significant dynamo amplification.

  6. Observation of Megagauss-Field Topology Changes due to Magnetic Reconnection in Laser-Produced Plasmas

    E-print Network

    - resolved field measurements are a necessity [7,8], and experiments involving strongly coupled, warm dense,10,13­15]. The laser heats the material, forming an expanding, hemispherical plasma bubble with an intense, toroidal B

  7. Computation of induced electric field and temperature elevation in human due to lightning current

    NASA Astrophysics Data System (ADS)

    Nagai, T.; Hirata, A.

    2010-05-01

    The present study investigated induced electric field and temperature elevation in specific tissues/organs of an anatomically based human body model for the lightning current. The threshold amplitude of the current inducing ventricular fibrillation and skin burning are estimated from computed induced electric field and temperature elevation with formulas for electrical stimulation and thermal damage. The computational results obtained herein were reasonably consistent with clinical observation.

  8. Simulations of magnetic field gradients due to micro-magnets on a triple quantum dot circuit

    SciTech Connect

    Poulin-Lamarre, G. [National Research Council of Canada, Ottawa, On., Canada, K1A-0R6 and Département de physique, Université de Sherbrooke, Sherbrooke, Qc. J1K-2R1 (Canada); Bureau-Oxton, C. [Département de physique, Université de Sherbrooke, Sherbrooke, Qc. J1K-2R1 (Canada); Kam, A. [National Research Council of Canada, Ottawa, On. K1A-0R6 (Canada); Zawadzki, P.; Aers, G. [National Research Council of Canada, Ottawa, On. K1A-0R6 (Canada); Studenikin, S. [National Research Council of Canada, Ottawa, On.K1A-0R6 (Canada); Pioro-Ladrière, M. [Département de physique, Université de Sherbrooke, Sherbrooke, Qc. J1K-2R1 (Canada); Sachrajda, A. S. [National Research Council of Canada, Ottawa, On., Canada, K1A-0R6 and Département de physique, Université de Sherbrooke, Sherbrooke, Qc. J1K-2R1 (Canada)

    2013-12-04

    To quantify the effects of local magnetic fields on triple quantum dots, the Heisenberg Hamiltonian has been diagonalized for three electrons coupled via the exchange interaction. In particular, we have investigated different geometries of micro-magnets located on top of the triple dot in order to optimize the field gradient characteristics. In this paper, we focus on two geometries which are candidates for an addressable EDSR triple quantum dot device.

  9. Intense electron emission due to picosecond laser-produced plasmas in high gradient electric fields

    SciTech Connect

    Wang, X.J.; Tsang, T.; Kirk, H.; Srinivasan-Rao, T.; Fischer, J.; Batchelor, K.; Russell, P.; Fernow, R.C. (Brookhaven National Laboratory, Upton, New York 11973 (United States))

    1992-08-01

    Picosecond laser pulses at a wavelength of 266 nm have been focused onto a solid metal cathode in coincidence with high gradient electric fields to produce high brightness electron beams. At power densities exceeding 10{sup 9} W/cm{sup 2}, a solid density plasma is formed and intense bursts of electrons are emitted from the target accompanied by macroscopic surface damage. An inferred {similar to}1 {mu}C of integrated charge with an average current of {similar to}20 A is emitted from a radio-frequency cavity driven at electric field gradients of {similar to}80 MV/m. In another experiment, where a dc extraction field of {similar to}6 MV/m is used, we observed an electron charge of {similar to}0.17 {mu}C. Both results are compared with the Schottky effect and the Fowler--Nordheim field emission. We found that this laser-induced intense electron emission shares many features with the explosive electron emission processes. No selective wavelength dependence is observed in the production of the intense electron emission in the dc extraction field. The integrated electrons give an apparent quantum efficiency of {similar to}1.2%, which is one of the highest reported to date from metal photocathodes at these photon energies.

  10. Casimir effect due to a slowly rotating source in the weak-field approximation

    NASA Astrophysics Data System (ADS)

    Bezerra, V. B.; Mota, H. F.; Muniz, C. R.

    2014-02-01

    We calculate the renormalized vacuum energy density for a massless scalar field confined between two nearby parallel plates formed by ideal uncharged conductors, placed very close to the surface of a rotating spherical gravitational source with mass M, radius R and angular momentum J, at the equatorial region. We consider that the source rotates slowly and that the gravitational field is weak. Corrections to the Casimir energy density induced by the gravitational field generated by this source are calculated up to M/R2 order. The results obtained show us that there is an important modification in the Casimir energy only in this order of approximation, which depends on the surface gravity as well as on the rotation of the source. Thermal corrections to the Casimir energy found are also calculated in all these orders.

  11. Casimir effect due to a slowly rotating source in the weak field approximation

    E-print Network

    Bezerra, V B; Muniz, C R

    2014-01-01

    We calculate the renormalized vacuum energy density for a massless scalar field confined between two nearby parallel plates formed by ideal uncharged conductors, placed very close to the surface of a rotating spherical gravitational source with mass $M$, radius $R$ and momentum angular $J$, at the equatorial region. We consider that the source rotates slowly and that the gravitational field is weak. Corrections to the Casimir energy density induced by the gravitational field generated by this source are calculated up to $M/R^2$ order. The obtained results show us that there is an important modification in the Casimir energy only in this order of approximation, which depends on the surface gravity as well as on the rotation of the source. Thermal corrections to the Casimir energy found also are calculated in all these orders.

  12. Casimir effect due to a slowly rotating source in the weak field approximation

    E-print Network

    V. B. Bezerra; H. F. Mota; C. R. Muniz

    2014-01-09

    We calculate the renormalized vacuum energy density for a massless scalar field confined between two nearby parallel plates formed by ideal uncharged conductors, placed very close to the surface of a rotating spherical gravitational source with mass $M$, radius $R$ and momentum angular $J$, at the equatorial region. We consider that the source rotates slowly and that the gravitational field is weak. Corrections to the Casimir energy density induced by the gravitational field generated by this source are calculated up to $M/R^2$ order. The obtained results show us that there is an important modification in the Casimir energy only in this order of approximation, which depends on the surface gravity as well as on the rotation of the source. Thermal corrections to the Casimir energy found also are calculated in all these orders.

  13. Reducing peripheral nerve stimulation due to gradient switching using an additional uniform field coil.

    PubMed

    Hidalgo-Tobon, Silvia S; Bencsik, Martin; Bowtell, Richard

    2011-11-01

    This study shows that larger rates of change of gradient with time (dG/dt) can be achieved at the threshold for peripheral nerve stimulation by applying a uniform concomitant field varying synchronously with a transverse field gradient and that this increase may be achieved without significant reduction of the spatial extent of the region over which imaging can be carried out. Realization of similar benefits through application of a uniform, z-directed field varying synchronously with an axial gradient is also demonstrated. The design and construction of transverse and axial coil arrangements is described, along with the results of volunteer studies that were carried out on 20 subjects, with the subjects positioned with four different regions (head, heart, hips, and knees) centered in the coils. These experiments were carried out at zero-field on a prototype system in which the coils were not actively shielded. The uniform concomitant field coil was not torque balanced. The increase in the rate of change of gradient at the threshold for peripheral nerve stimulation that could be achieved by the addition of the uniform field depends on body position and was larger for the transverse coils (head = × 1.9 ± 0.6; heart = × 0.9 ± 0.3; hips = × 1.4 ± 0.4; knees = × 1.5 ± 0.4) than for the axial coils (head = × 1.5 ± 0.6; heart = × 0.8 ± 0.3; hips = × 1.3 ± 0.4; knees = × 1.1 ± 0.3). PMID:21604293

  14. Transient particle acceleration in strongly magnetized neutron stars. II - Effects due to a dipole field geometry

    NASA Technical Reports Server (NTRS)

    Fatuzzo, Marco; Melia, Fulvio

    1991-01-01

    Sheared Alfven waves generated by nonradial crustal disturbances above the polar cap of a strongly magnetized neutron star induce an electric field component parallel to B. An attempt is made to determine the manner in which the strong radial dependence of B affects the propagation of these sheared Alfven waves, and whether this MHD process is still an effective particle accelerator. It is found that although the general field equation is quite complicated, a simple wavelike solution can still be obtained under the conditions of interest for which the Alfven phase velocity decouples from the wave equation. The results may be applicable to gamma-ray burst sources.

  15. Poloidal electric field due to ICRH and its effect on neoclassical transport

    SciTech Connect

    Vacca, L. (Plasma Fusion Center, MIT, Cambridge 0123, Massachusetts (United States))

    1994-10-15

    We study the transport of a plasma in which a minority ion species is heated by fast Alfven waves. The strong anisotropy of the minority distribution function gives origin to a poloidal electric field. We calculate the poloidal dependence of the electric potential by numerically integrating the leading order minority distribution function. When the amplitude of this field is such that electrostatic trapping is not negligible in comparison to the magnetic trapping then neoclassical transport can be enhanced as found in previous work. The linearized kinetic equations are solved using a variational method in the banana regime. Approximate analytic expressions for the transport coefficients are given.

  16. Is the Cosmic "Axis of Evil" due to a Large-Scale Magnetic Field

    E-print Network

    Michael J. Longo

    2007-03-29

    I propose a mechanism that would explain the near alignment of the low order multipoles of the cosmic microwave background (CMB). This mechanism supposes a large-scale cosmic magnetic field that tends to align the cyclotron orbit axes of electrons in hot plasmas along the same direction. Inverse Compton scattering of the CMB photons then imprints this pattern on the CMB, thus causing the low- multipoles to be generally aligned. The spins of the majority of spiral galaxies and that of our own Galaxy appear to be aligned along the cosmic magnetic field.

  17. Disturbance to the population due to flight operations at landing fields

    SciTech Connect

    Rohrmann, B.

    1981-02-01

    By means of a social-psychological field study, an explanation for the extent of annoyance and disturbance resulting from flight operations of non-commercial aircraft was found, including moderating, nonphysical factors. Residents near four landing fields between the ages of 19-70 were selected in predetermined clusters. From the sample drawn, 398 interviews were conducted. Informal conversations were also carried out with certain influential persons and acoustical measurements were made at 5 points in Braunschweig. The data was processed and evaluated at the computer center in Hamburg. The study includes an extensive discussion of the results gained from the questionnaire and subjected to statistical analysis.

  18. Ultra-Sensitive Magnetoresistive Displacement Sensing Device

    NASA Technical Reports Server (NTRS)

    Olivas, John D. (Inventor); Lairson, Bruce M. (Inventor); Ramesham, Rajeshuni (Inventor)

    2003-01-01

    An ultrasensitive displacement sensing device for use in accelerometers, pressure gauges, temperature transducers, and the like, comprises a sputter deposited, multilayer, magnetoresistive field sensor with a variable electrical resistance based on an imposed magnetic field. The device detects displacement by sensing changes in the local magnetic field about the magnetoresistive field sensor caused by the displacement of a hard magnetic film on a movable microstructure. The microstructure, which may be a cantilever, membrane, bridge, or other microelement, moves under the influence of an acceleration a known displacement predicted by the configuration and materials selected, and the resulting change in the electrical resistance of the MR sensor can be used to calculate the displacement. Using a micromachining approach, very thin silicon and silicon nitride membranes are fabricated in one preferred embodiment by means of anisotropic etching of silicon wafers. Other approaches include reactive ion etching of silicon on insulator (SOI), or Low Pressure Chemical Vapor Deposition of silicon nitride films over silicon substrates. The device is found to be improved with the use of giant magnetoresistive elements to detect changes in the local magnetic field.

  19. Heat flux due to poloidal electric field in the banana regime

    SciTech Connect

    Taguchi, M. (College of Industrial Technology, Nihon University, 2-11-1 Shinei, Narashino-shi, Chiba-ken 275 (Japan))

    1992-02-01

    The heat flux due to poloidally varying electrostatic potential is calculated in the banana regime. This electrostatic potential determined self-consistently from charge neutrality is shown to increase the electron heat flux by a factor {radical}{ital m}{sub {ital i}}/{ital m}{sub {ital e}} compared with that when this potential is neglected, where {ital m}{sub {ital e}} and {ital m}{sub {ital i}} are the masses of electron and ion, respectively.

  20. Experimental investigations of flow field and heat transfer characteristics due to periodically pulsating impinging air jets

    Microsoft Academic Search

    T. Janetzke; W. Nitsche; J. Täge

    2008-01-01

    The paper concentrates on increasing convective heat transfer due to periodically pulsating impinging air jets. A maximum\\u000a enhancement rate of cooling effectiveness up to 20% could be detected at an excitation Strouhal number of Sr = 0.82 when using a high pulsation magnitude. Reductions up to 5% occured at low Strouhal numbers with coincident high pulsation\\u000a magnitudes as well. The thermal results

  1. Modelling toroidal rotation damping in ITER due to external 3D fields

    NASA Astrophysics Data System (ADS)

    Liu, Yueqiang; Akers, R.; Chapman, I. T.; Gribov, Y.; Hao, G. Z.; Huijsmans, G. T. A.; Kirk, A.; Loarte, A.; Pinches, S. D.; Reinke, M.; Ryan, D.; Sun, Y.; Wang, Z. R.

    2015-06-01

    The linear and quasi-linear plasma response to the n = 3 and n = 4 (n is the toroidal mode number) resonant magnetic perturbation (RMP) fields, produced by the in-vessel edge localized mode control coils, is numerically studied for an ITER 15 MA H-mode baseline scenario. Both single fluid and fluid-kinetic hybrid models are used. The inclusion of drift kinetic effects does not strongly alter the plasma response compared to the fluid approximation for this ITER plasma. The full toroidal drift kinetic model is also used to compute the neoclassical toroidal viscous (NTV) torque, yielding results close to that of an analytic model based on geometric simplifications. The computed NTV torque from low-n RMP fields is generally smaller than the resonant electromagnetic torque for this ITER plasma. The linear response computations show a weak core kink response, contrary to a strong kink response often computed for plasmas from present day tokamak devices. Initial value quasi-linear simulations, including various torque models, show a localized damping of the plasma toroidal flow near the edge, as a result of the applied RMP fields. This localized rotation damping can be weak or strong depending on whether a weakly unstable edge localized peeling mode is present. No qualitative difference is found between the n = 3 and n = 4 RMP field configurations, in both the linear and non-linear response results.

  2. Energy loss due to field fluctuations in a two-stream QCD plasma

    E-print Network

    Mahatsab Mandal; Sreemoyee Sarkar; Pradip Roy; Abhee K. Dutt-Mazumder

    2011-09-06

    We derive the expression for the collisional energy loss in two stream plasma induced by the fluctuating chromoelectric field. It is revealed that the main contribution here comes from the unstable modes which grow exponentially with time. A strong direction dependence of the energy loss has also been demonstrated.

  3. Intense electron emission due to picosecond laser-produced plasmas in high gradient electric fields

    Microsoft Academic Search

    X. J. Wang; T. Tsang; H. Kirk; T. Srinivasan-Rao; J. Fischer; K. Batchelor; P. Russell; R. C. Fernow

    1992-01-01

    Picosecond laser pulses at a wavelength of 266 nm have been focused onto a solid metal cathode in coincidence with high-gradient electric fields to produce high brightness electron beams. At power densities exceeding 10 exp 9 W\\/sq cm, a solid density plasma is formed and intense bursts of electrons are emitted from the target accompanied by macroscopic surface damage. An

  4. Magnetic field changes in the human brain due to swallowing or speaking.

    PubMed

    Birn, R M; Bandettini, P A; Cox, R W; Jesmanowicz, A; Shaker, R

    1998-07-01

    Variations in the magnetic field in the human brain caused by the processes of swallowing or speaking are measured. In both processes, motion of the pharyngeal muscles, especially the tongue and jaw, alter the susceptibility-induced magnetic field distribution at the brain slice being imaged. This leads to image warping, compromising the analysis of a time series of images, such as in functional magnetic resonance imaging (fMRI). These dynamic changes are assessed by acquiring a time series of images using a gradient-echo asymmetric-spin-echo sequence (GREASE), a technique in which two images are acquired for each excitation--one during the gradient echo, and one during the latter part of the spin echo. The NMR phase difference between the two images is a measure of the magnetic field distribution. A series of brain images, acquired with this sequence while the subject either swallows or speaks, indicated negative magnetic field changes of up to 0.087 ppm in the inferior region of the brain for both speaking and swallowing, and in some speech, additional positive changes of up to 0.056 ppm in the frontal region of the brain were indicated. PMID:9660553

  5. Morphology of blazar-induced gamma ray halos due to a helical intergalactic magnetic field

    E-print Network

    Long, Andrew J

    2015-01-01

    We study the characteristic size and shape of idealized blazar-induced cascade halos in the $1-100 \\, {\\rm GeV}$ energy range assuming various non-helical and helical configurations for the intergalactic magnetic field (IGMF). While the magnetic field creates an extended halo, the helicity provides the halo with a twist. Under simplifying assumptions, we assess the parameter regimes for which it is possible to measure the size and shape of the halo from a single source and then to deduce properties of the IGMF. We find that blazar halo measurements with an experiment similar to Fermi-LAT are best suited to probe a helical magnetic field with strength and coherence length today in the ranges $10^{-17} \\lesssim B_{0} / {\\rm Gauss} \\lesssim 10^{-13}$ and $10 \\, {\\rm Mpc} \\lesssim \\lambda \\lesssim 10 \\, {\\rm Gpc}$ where $\\mathcal{H} \\sim B_0^2 / \\lambda$ is the magnetic helicity density. Stronger magnetic fields or smaller coherence scales can still potentially be investigated, but the connection between the halo...

  6. Displacement sensors using soft magnetostrictive alloys

    SciTech Connect

    Hristoforou, E. (NCSR Demokritos Aghia Paraskevi, Athens (Greece). Inst. of Material Science); Reilly, R.E. (King's College London (United Kingdom). Electronic and Electrical Engineering Dept.)

    1994-09-01

    The authors report results on the response of a family of displacement sensors, which are based on the magnetostrictive delay line (MDL) technique, using current conductor orthogonal to the MDL. Such sensing technique is based on the change of the magnetic circuit and the acoustic stress point of origin due to the displacement of a soft magnetic material above it. Integrated arrays of sensors can be obtained due to the acoustic delay line technique and they can be used as tactile arrays, digitizers or devices for medical application (gait analysis etc.), while absence of hysteresis and low cost of manufacturing make them competent in this sector of sensor market.

  7. (14)N Quadrupole Resonance line broadening due to the earth magnetic field, occuring only in the case of an axially symmetric electric field gradient tensor.

    PubMed

    Aissani, Sarra; Guendouz, Laouès; Marande, Pierre-Louis; Canet, Daniel

    2015-01-01

    As demonstrated before, the application of a weak static B0 magnetic field (less than 10G) may produce definite effects on the (14)N Quadrupole Resonance line when the electric field gradient tensor at the nitrogen nucleus level is of axial symmetry. Here, we address more precisely the problem of the relative orientation of the two magnetic fields (the static field and the radio-frequency field of the pure NQR experiment). For a field of 6G, the evolution of the signal intensity, as a function of this relative orientation, is in very good agreement with the theoretical predictions. There is in particular an intensity loss by a factor of three when going from the parallel configuration to the perpendicular configuration. By contrast, when dealing with a very weak magnetic field (as the earth field, around 0.5G), this effect drops to ca. 1.5 in the case Hexamethylenetetramine (HMT).This is explained by the fact that the Zeeman shift (due to the very weak magnetic field) becomes comparable to the natural line-width. The latter can therefore be determined by accounting for this competition. Still in the case of HMT, the estimated natural line-width is half the observed line-width. The extra broadening is thus attributed to earth magnetic field. The latter constitutes therefore the main cause of the difference between the natural transverse relaxation time (T2) and the transverse relaxation time derived from the observed line-width (T2(?)). PMID:25910551

  8. Electric fields in hippocampus due to transcranial focal electrical stimulation via concentric ring electrodes.

    PubMed

    Besio, Walter G; Hadidi, Ruba; Makeyev, Oleksandr; Luna-Munguía, Hiram; Rocha, Luisa

    2011-01-01

    As epilepsy affects approximately one percent of the world population, electrical stimulation of brain has recently shown potential as an additive seizure control therapy. In this study we applied focal transcranial electrical stimulation (TFS) on the surface of the skull of rats via concentric ring electrodes. We recorded electric potentials with a bipolar electrode consisting of two stainless steel wires implanted into the left ventral hippocampus. TFS current was gradually increased by 20% starting at 103 ?A allowing us to assess the relationship between TFS current and both potentials recorded from the bipolar electrode and the resulting electric field. Generally, increases in TFS current resulted in increases in the electric field. This allows us to estimate what extra-cranial TFS current would be sufficient to cause the activation of neurons in the hippocampus. PMID:22255580

  9. Flow and acoustic field due to an inclined plate with a downstream splitter

    NASA Technical Reports Server (NTRS)

    Kim, C. M.; Conlisk, A. T.

    1993-01-01

    In the present work, the high Reynolds number flow past an inclined plate with a splitter plate placed in its wake is considered numerically. A numerical conformal mapping technique is employed to transform the two-plate system into the same number of cylinders: the flow field is assumed to be two-dimensional. The vortex shedding from the inclined plate is modelled using the discrete vortex method. It is shown that the splitter plate has a profound effect on the development of the flow over a range of values of a suitably defined offset parameter and for a range of positions of the leading edge of the splitter plate. The acoustic field is also calculated and the spectrum reflects the flow results.

  10. Spinmotive force due to motion of magnetic bubble arrays driven by magnetic field gradient

    PubMed Central

    Yamane, Yuta; Hemmatiyan, Shayan; Ieda, Jun'ichi; Maekawa, Sadamichi; Sinova, Jairo

    2014-01-01

    Interaction between local magnetization and conduction electrons is responsible for a variety of phenomena in magnetic materials. It has been recently shown that spin current and associated electric voltage can be induced by magnetization that depends on both time and space. This effect, called spinmotive force, provides for a powerful tool for exploring the dynamics and the nature of magnetic textures, as well as a new source for electromotive force. Here we theoretically demonstrate the generation of electric voltages in magnetic bubble array systems subjected to a magnetic field gradient. It is shown by deriving expressions for the electric voltages that the present system offers a direct measure of phenomenological parameter ? that describes non-adiabaticity in the current induced magnetization dynamics. This spinmotive force opens a door for new types of spintronic devices that exploit the field-gradient. PMID:25365971

  11. Antiproton cross-field diffusion in antihydrogen production experiments due to anisotropic binary interactions

    NASA Astrophysics Data System (ADS)

    Ordonez, C. A.; Correa, J. R.

    2007-08-01

    Collisional processes in electrostatic ion storage rings and reflecting-beam-type electrostatic ion traps can be associated with anisotropic binary interactions, because shielding of the Coulomb interactions may not take place in one or more dimensions. Collisional scattering theory has recently been developed for describing the velocity-space scattering processes in such systems [J.R. Correa, Y. Chang, C.A. Ordonez, Phys. Plasmas 12 (2005) 084505]. The theory is extended to enable the effect of a magnetic field to be included. The theory is intended to be applicable, for example, to antiproton scattering within nested Penning traps that are used to produce antihydrogen [M. Amoretti et al., Nature 419 (2002) 456; G. Gabrielse et al., Phys. Rev. Lett. 89 (2002) 213401]. The theory is applied for considering the cross-magnetic-field diffusion of the antiprotons.

  12. Velocity-Space Diffusion Coefficients Due to Full-Wave ICRF Fields in Toroidal Geometry

    SciTech Connect

    Harvey, R.W. [CompX, P.O. Box 2672, Del Mar, CA 92014-5672 (United States); Jaeger, F.; Berry, L.A.; Batchelor, D.B.; D'Azevedo, E.; Carter, M.D. [ORNL, Oak Ridge, TN (United States); Ershov, N.M.; Smirnov, A.P. [Moscow State Univ. (Russian Federation); Bonoli, P.; Wright, J.C. [PSFC, MIT, Boston, MA (United States); Smithe, D.N. [ATK-Mission Research (United States)

    2005-09-26

    Jaeger et al. have calculated bounce-averaged QL diffusion coefficients from AORSA full-wave fields, based on non-Maxwellian distributions from CQL3D Fokker-Planck code. A zero banana-width approximation is employed. Complementing this calculation, a fully numerical calculation of ion velocity diffusion coefficients using the full-wave fields in numerical tokamak equilibria has been implemented to determine the finite orbit width effects. The un-approximated Lorentz equation of motion is integrated to obtain the change in velocity after one complete poloidal transit of the tokamak. Averaging velocity changes over initial starting gyro-phase and toroidal angle gives bounce-averaged diffusion coefficients. The coefficients from the full-wave and Lorentz orbit methods are compared for an ITER DT second harmonic tritium ICRF heating case: the diffusion coefficients are similar in magnitude but reveal substantial finite orbit effects.

  13. Reduced temperature dependence of luminescence from silicon due to field-induced carrier confinement

    Microsoft Academic Search

    Ching-Fuh Lin; Miin-Jang Chen; Eih-Zhe Liang; W. T. Liu; C. W. Liu

    2001-01-01

    Electroluminescence from metal-oxide-semiconductor structures on Si was experimentally found to be much less temperature dependent than photoluminescence of Si. The physical reason is attributed to the field-induced carrier confinement in a small region, which contains much less impurity states, compared to the unconfined region. Thus, electron-hole recombination by radiation emission instead of through highly temperature-dependent impurity states is increased. A

  14. Neuromagnetic field strength outside the human head due to impedance changes from neuronal depolarization.

    PubMed

    Ahadzi, G M; Liston, A D; Bayford, R H; Holder, D S

    2004-02-01

    The holy grail of neuroimaging would be to have an imaging system, which could image neuronal electrical activity over milliseconds. One way to do this would be by imaging the impedance changes associated with ion channels opening in neuronal membranes in the brain during activity. In principle, we could measure this change by using electrical impedance tomography (EIT) but it is close to its threshold of detectability. With the inherent limitation in the use of electrodes, we propose a new scheme based on recording the magnetic field resulting from an injected current with superconducting quantum interference devices (SQUIDs), used in magnetoencephalography (MEG). We have performed a feasibility study using computer simulation. The head was modelled as concentric spheres to mimic the scalp, skull, cerebrospinal fluid and brain using the finite element method. The magnetic field 1 cm away from the scalp was estimated. An impedance change of 1% in a 2 cm radius volume in the brain was modelled as the region of depolarization. A constant current of 100 microA was injected into the head from diametrically opposite electrodes. The model predicts that the standing magnetic field is about 10 pT and changed by about 3 fT (0.03%) on depolarization. The spectral noise density in a typical MEG system in the frequency band 1-100 Hz is about 7 fT, so this places the change at the limit of detectability. This is similar to electrical recording, as in conventional EIT systems, but there may be advantages to MEG in that the magnetic field directly traverses the skull and instrumentation errors from the electrode-skin interface will be obviated. PMID:15005330

  15. VISCOUS EVOLUTION AND PHOTOEVAPORATION OF CIRCUMSTELLAR DISKS DUE TO EXTERNAL FAR ULTRAVIOLET RADIATION FIELDS

    SciTech Connect

    Anderson, Kassandra R.; Adams, Fred C. [Physics Department, University of Michigan, Ann Arbor, MI 48109 (United States); Calvet, Nuria [Astronomy Department, University of Michigan, Ann Arbor, MI 48109 (United States)

    2013-09-01

    This paper explores the effects of FUV radiation fields from external stars on circumstellar disk evolution. Disks residing in young clusters can be exposed to extreme levels of FUV flux from nearby OB stars, and observations show that disks in such environments are being actively photoevaporated. Typical FUV flux levels can be factors of {approx}10{sup 2}-10{sup 4} higher than the interstellar value. These fields are effective in driving mass loss from circumstellar disks because they act at large radial distance from the host star, i.e., where most of the disk mass is located, and where the gravitational potential well is shallow. We combine viscous evolution (an {alpha}-disk model) with an existing FUV photoevaporation model to derive constraints on disk lifetimes, and to determine disk properties as functions of time, including mass-loss rates, disk masses, and radii. We also consider the effects of X-ray photoevaporation from the host star using an existing model, and show that for disks around solar-mass stars, externally generated FUV fields are often the dominant mechanism in depleting disk material. For sufficiently large viscosities, FUV fields can efficiently photoevaporate disks over the entire range of parameter space. Disks with viscosity parameter {alpha} = 10{sup -3} are effectively dispersed within 1-3 Myr; for higher viscosities ({alpha} = 10{sup -2}) disks are dispersed within {approx}0.25-0.5 Myr. Furthermore, disk radii are truncated to less than {approx}100 AU, which can possibly affect the formation of planets. Our model predictions are consistent with the range of observed masses and radii of proplyds in the Orion Nebula Cluster.

  16. Undulation instability in a bilayer lipid membrane due to electric field interaction with lipid dipoles.

    PubMed

    Bingham, Richard J; Olmsted, Peter D; Smye, Stephen W

    2010-05-01

    Bilayer lipid membranes (BLMs) are an essential component of all biological systems, forming a functional barrier for cells and organelles from the surrounding environment. The lipid molecules that form membranes contain both permanent and induced dipoles, and an electric field can induce the formation of pores when the transverse field is sufficiently strong (electroporation). Here, a phenomenological free energy is constructed to model the response of a BLM to a transverse static electric field. The model contains a continuum description of the membrane dipoles and a coupling between the headgroup dipoles and the membrane tilt. The membrane is found to become unstable through buckling modes, which are weakly coupled to thickness fluctuations in the membrane. The thickness fluctuations, along with the increase in interfacial area produced by membrane buckling, increase the probability of localized membrane breakdown, which may lead to pore formation. The instability is found to depend strongly on the strength of the coupling between the dipolar headgroups and the membrane tilt as well as the degree of dipolar ordering in the membrane. PMID:20866263

  17. PDT - PARTICLE DISPLACEMENT TRACKING SOFTWARE

    NASA Technical Reports Server (NTRS)

    Wernet, M. P.

    1994-01-01

    Particle Imaging Velocimetry (PIV) is a quantitative velocity measurement technique for measuring instantaneous planar cross sections of a flow field. The technique offers very high precision (1%) directionally resolved velocity vector estimates, but its use has been limited by high equipment costs and complexity of operation. Particle Displacement Tracking (PDT) is an all-electronic PIV data acquisition and reduction procedure which is simple, fast, and easily implemented. The procedure uses a low power, continuous wave laser and a Charged Coupled Device (CCD) camera to electronically record the particle images. A frame grabber board in a PC is used for data acquisition and reduction processing. PDT eliminates the need for photographic processing, system costs are moderately low, and reduced data are available within seconds of acquisition. The technique results in velocity estimate accuracies on the order of 5%. The software is fully menu-driven from the acquisition to the reduction and analysis of the data. Options are available to acquire a single image or 5- or 25-field series of images separated in time by multiples of 1/60 second. The user may process each image, specifying its boundaries to remove unwanted glare from the periphery and adjusting its background level to clearly resolve the particle images. Data reduction routines determine the particle image centroids and create time history files. PDT then identifies the velocity vectors which describe the particle movement in the flow field. Graphical data analysis routines are included which allow the user to graph the time history files and display the velocity vector maps, interpolated velocity vector grids, iso-velocity vector contours, and flow streamlines. The PDT data processing software is written in FORTRAN 77 and the data acquisition routine is written in C-Language for 80386-based IBM PC compatibles running MS-DOS v3.0 or higher. Machine requirements include 4 MB RAM (3 MB Extended), a single or multiple frequency RGB monitor (EGA or better), a math co-processor, and a pointing device. The printers supported by the graphical analysis routines are the HP Laserjet+, Series II, and Series III with at least 1.5 MB memory. The data acquisition routines require the EPIX 4-MEG video board and optional 12.5MHz oscillator, and associated EPIX software. Data can be acquired from any CCD or RS-170 compatible video camera with pixel resolution of 600hX400v or better. PDT is distributed on one 5.25 inch 360K MS-DOS format diskette. Due to the use of required proprietary software, executable code is not provided on the distribution media. Compiling the source code requires the Microsoft C v5.1 compiler, Microsoft QuickC v2.0, the Microsoft Mouse Library, EPIX Image Processing Libraries, the Microway NDP-Fortran-386 v2.1 compiler, and the Media Cybernetics HALO Professional Graphics Kernal System. Due to the complexities of the machine requirements, COSMIC strongly recommends the purchase and review of the documentation prior to the purchase of the program. The source code, and sample input and output files are provided in PKZIP format; the PKUNZIP utility is included. PDT was developed in 1990. All trade names used are the property of their respective corporate owners.

  18. The vacuum energy excitations due to gravitational field as a possible candidate of dark matter in galaxies

    E-print Network

    V. Majernik

    2004-08-19

    In this Letter we point out to the possibility that the cloud of the vacuum energy excitations in gravitation fields surrounding galaxies forms a component of dark matter. These clouds of the vacuum energy excitations interact gravitationally with the baryonic matter of galaxies changing their dynamical and kinematical properties. In four model galaxies we show that the dynamic changes due to the vacuum energy excitations of these galaxies are comparable with data. This shows that vacuum energy excitations created in the gravitation field of galaxies may be considered as one of the candidates of dark matter.

  19. Acoustic radiation force in tissue-like solids due to modulated sound field

    NASA Astrophysics Data System (ADS)

    Dontsov, Egor V.; Guzina, Bojan B.

    2012-10-01

    The focus of this study is the sustained body force (the so-called acoustic radiation force) in homogeneous tissue-like solids generated by an elevated-intensity, focused ultrasound field (Mach number=O(10-3)) in situations when the latter is modulated by a low-frequency signal. This intermediate-asymptotics problem, which bears relevance to a number of emerging biomedical applications, is characterized by a number of small (but non-vanishing) parameters including the Mach number, the ratio between the modulation and ultrasound frequency, the ratio of the shear to bulk modulus, and the dimensionless attenuation coefficient. On approximating the response of soft tissues as that of a nonlinear viscoelastic solid with heat conduction, the featured second-order problem is tackled via a scaling paradigm wherein the transverse coordinates are scaled by the width of the focal region, while the axial and temporal coordinate are each split into a "fast" and "slow" component with the twin aim of: (i) canceling the linear terms from the field equations governing the propagation of elevated-intensity ultrasound, and (ii) accounting for the effect of ultrasound modulation. In the context of the focused ultrasound analyses, the key feature of the proposed study revolves around the dual-time-scale treatment of the temporal variable, which allows one to parse out the contribution of ultrasound and its modulation in the nonlinear solution. In this way the acoustic radiation force (ARF), giving rise to the mean tissue motion, is exacted by computing the "fast" time average of the germane field equations. A comparison with the existing theory reveals a number of key features that are brought to light by the new formulation, including the contributions to the ARF of ultrasound modulation and thermal expansion, as well as the precise role of constitutive nonlinearities in generating the sustained body force in tissue-like solids by a focused ultrasound beam.

  20. Global Simulation of Proton Precipitation Due to Field Line Curvature During Substorms

    NASA Technical Reports Server (NTRS)

    Gilson, M. L.; Raeder, J.; Donovan, E.; Ge, Y. S.; Kepko, L.

    2012-01-01

    The low latitude boundary of the proton aurora (known as the Isotropy Boundary or IB) marks an important boundary between empty and full downgoing loss cones. There is significant evidence that the IB maps to a region in the magnetosphere where the ion gyroradius becomes comparable to the local field line curvature. However, the location of the IB in the magnetosphere remains in question. In this paper, we show simulated proton precipitation derived from the Field Line Curvature (FLC) model of proton scattering and a global magnetohydrodynamic simulation during two substorms. The simulated proton precipitation drifts equatorward during the growth phase, intensifies at onset and reproduces the azimuthal splitting published in previous studies. In the simulation, the pre-onset IB maps to 7-8 RE for the substorms presented and the azimuthal splitting is caused by the development of the substorm current wedge. The simulation also demonstrates that the central plasma sheet temperature can significantly influence when and where the azimuthal splitting takes place.

  1. SOI detector with drift field due to majority carrier flow - an alternative to biasing in depletion

    SciTech Connect

    Trimpl, M.; Deptuch, G.; Yarema, R.; /Fermilab

    2010-11-01

    This paper reports on a SOI detector with drift field induced by the flow of majority carriers. It is proposed as an alternative method of detector biasing compared to standard depletion. N-drift rings in n-substrate are used at the front side of the detector to provide charge collecting field in depth as well as to improve the lateral charge collection. The concept was verified on a 2.5 x 2.5 mm{sup 2} large detector array with 20 {micro}m and 40 {micro}m pixel pitch fabricated in August 2009 using the OKI semiconductor process. First results, obtained with a radioactive source to demonstrate spatial resolution and spectroscopic performance of the detector for the two different pixel sizes will be shown and compared to results obtained with a standard depletion scheme. Two different diode designs, one using a standard p-implantation and one surrounded by an additional BPW implant will be compared as well.

  2. Observation of displacement momentum in normal and chiral dielectrics.

    PubMed

    Rikken, G L J A; van Tiggelen, B A

    2013-05-10

    We argue that displacement currents in dielectrics are in general accompanied by mechanical momentum through total momentum conservation, quite analogous to the Einstein-de Haas effect. We report the first observation of such displacement momentum, generated by a time varying electric field in a dielectric, and by a time varying magnetic field in a chiral dielectric. PMID:23705708

  3. Elastic and piezoelectric fields in substrates GaAs ,,001... and GaAs ,,111... due to a buried quantum dot

    E-print Network

    Pan, Ernie

    for predicting elastic and piezoelectric fields in the semiconductor GaAs. 2 The magnitude of the QDElastic and piezoelectric fields in substrates GaAs ,,001... and GaAs ,,111... due to a buried present a rigorous study on the elastic and piezoelectric fields in substrates GaAs 001 and GaAs 111 due

  4. Variations of Mars gravitational field and rotation due to seasonal CO2 exchange

    NASA Technical Reports Server (NTRS)

    Chao, B. Fong; Rubincam, David Parry

    1990-01-01

    About a quarter of the Martian atmospheric mass is exchanged between the atmosphere and the polar caps in the course of a Martian year: CO2 condenses to form (or add to) the polar caps in winter and sublimes into the atmosphere in summer. This paper studies the effect of this CO2 mass redistribution on Martian rotation and gravitational field. Two mechanisms are examined: (1) the waxing and waning of solid CO2 in the polar caps and (2) the geographical distribution of gaseous CO2 in the atmosphere. In particular, the net peak-to-peak changes in J2 and J3 over a Martian year are both found to be as much as about 6 x 10 to the -9th. A simulation suggests that these changes may be detected by the upcoming Mars Observer under favorable but realistic conditions.

  5. Material damage due to air pollutants: design of a field monitoring program

    SciTech Connect

    Stankunas, A.R.; McCarthy, E.F.

    1983-01-01

    The recognition of the role of air pollutants in the deterioration of irreplaceable structures and monuments of profound historical importance as well as other commonly used materials exposed outdoors coupled with the recent emphasis on converting to coal from oil has led to a renewed concern of the effects of local increases in SO/sub 2/ emissions and, consequently, potential damage to these structures and materials. The damage to materials by air pollutants is not a single cause and effect process. Many natural environmental factors have a strong influence on the process. Since the natural environment itself causes material damage, it is often difficult or impossible to determine the incremental damage due to air pollutants alone. In addition, pollutants can act synergistically with natural environmental factors or each other which complicates the analysis even more. To quantify the actual damage and provide indication of potential impacts in the future, a materials damage monitoring plan was developed to assess the effects of specific sources. The materials damage monitoring plan recommended here provides a variety of relatively inexpensive techniques not only to adequately identify and assess damage caused by increased SO/sub 2/ emissions but also to determine if significant damage occurs at all. Highly detailed photography, the use of samples of standard building materials, and specially prepared sensitive material samples as short-term preliminary indicators of potential problems provide the necessary information to determine potential effects and allow the performance of mitigative measures before the damage causes irreplaceable losses to our cultural heritage.

  6. Nonlinear imaging techniques for the observation of cell membrane perturbation due to pulsed electric field exposure

    NASA Astrophysics Data System (ADS)

    Moen, Erick K.; Beier, Hope T.; Thompson, Gary L.; Roth, Caleb C.; Ibey, Bennett L.

    2014-03-01

    Nonlinear optical probes, especially those involving second harmonic generation (SHG), have proven useful as sensors for near-instantaneous detection of alterations to orientation or energetics within a substance. This has been exploited to some success for observing conformational changes in proteins. SHG probes, therefore, hold promise for reporting rapid and minute changes in lipid membranes. In this report, one of these probes is employed in this regard, using nanosecond electric pulses (nsEPs) as a vehicle for instigating subtle membrane perturbations. The result provides a useful tool and methodology for the observation of minute membrane perturbation, while also providing meaningful information on the phenomenon of electropermeabilization due to nsEP. The SHG probe Di- 4-ANEPPDHQ is used in conjunction with a tuned optical setup to demonstrate nanoporation preferential to one hemisphere, or pole, of the cell given a single square shaped pulse. The results also confirm a correlation of pulse width to the amount of poration. Furthermore, the polarity of this event and the membrane physics of both hemispheres, the poles facing either electrode, were tested using bipolar pulses consisting of two pulses of opposite polarity. The experiment corroborates findings by other researchers that these types of pulses are less effective in causing repairable damage to the lipid membrane of cells.

  7. Fragmentation and Isomerization Due to Field Heating in Traveling Wave Ion Mobility Spectrometry

    NASA Astrophysics Data System (ADS)

    Morsa, Denis; Gabelica, Valérie; De Pauw, Edwin

    2014-08-01

    During their travel inside a traveling wave ion mobility cell (TW IMS), ions are susceptible to heating because of the presence of high intensity electric fields. Here, we report effective temperatures T eff,vib obtained at the injection and inside the mobility cell of a SYNAPT G2 HDMS spectrometer for different probe ions: benzylpyridinium ions and leucine enkephalin. Using standard parameter sets, we obtained a temperature of ~800 K at injection and 728 ± 2 K into the IMS cell for p-methoxybenzylpyridinium. We found that T eff,vib inside the cell was dependent on the separation parameters and on the nature of the analyte. While the mean energy of the Boltzmann distributions increases with ion size, the corresponding temperature decreases because of increasing numbers of vibrational normal modes. We also investigated conformational rearrangements of 7+ ions of cytochrome c and reveal isomerization of the most compact structure, therefore highlighting the effects of weak heating on the gas-phase structure of biologically relevant ions.

  8. Scavenging of rodent carcasses following simulated mortality due to field applications of anticoagulant rodenticide.

    PubMed

    Montaz, Julie; Jacquot, Marion; Coeurdassier, Michaël

    2014-11-01

    Worldwide, agricultural uses of anticoagulant rodenticides (ARs) cause poisonings of non-target wildlife as observed in France where bromadiolone is used to control water vole outbreaks. Following bromadiolone field application, a part of the vole population may die aboveground of the treated plots and thus, can represent an important risk of secondary poisoning for scavengers. In this study, water voles were trapped in a non-treated area and their carcasses were placed aboveground in plots located in an area where a vole outbreak occurred. Then, the environmental persistence, the diurnal and nocturnal scavenging rates of water vole carcasses were assessed in autumn 2011 and in spring 2012. The diurnal scavenger species were also identified. The environmental persistence of the carcasses to reach at least a scavenging rate of 87.5 % was 0.5-1.5 day. The average rates of diurnal and nocturnal scavenging ranged from 67 to 100 % and 5 to 100 %, respectively. They depended on the composition of the scavenger community present near the monitored plots; diurnal scavenging rates being higher with corvids than with raptors. In autumn, the red kite and the common buzzard were the main scavengers in one of the plots, what suggests a high risk of poisoning for these raptors during post-nuptial migration. So, the collection of vole carcasses after treatments and the limitations of bromadiolone applications when high densities of predators/scavengers are observed could be implemented to mitigate the risks of secondary poisoning. PMID:25147048

  9. Microstructural changes in a cementitious membrane due to the application of a DC electric field.

    PubMed

    Covelo, Alba; Diaz, Belen; Freire, Lorena; Novoa, X Ramon; Perez, M Consuelo

    2008-07-01

    The use of electromigration techniques to accelerate chloride ions motion is commonly employed to characterise the permeability of cementitious samples to chlorides, a relevant parameter in reinforced concrete corrosion. This paper is devoted to the study of microstructure's changes occurring in mortar samples when submitted to natural diffusion and migration experiments. The application of an electric field reduces testing time in about one order of magnitude with respect to natural diffusion experiments. Nevertheless, the final sample's microstructure differs in both tests. Impedance Spectroscopy is employed for real time monitoring of microstructural changes. During migration experiments the global impedance undergoes important increase in shorter period of time compared to natural diffusion tests. So, the forced motion of ions through the concrete membrane induces significant variations in the porous structure, as confirmed by Mercury Intrusion Porosimetry. After migration experiments, an important increase in the capillary pore size (10-100 nm) was detected. Conversely, no relevant variations are found after natural diffusion tests. Results presented in this work cast doubt on the significance of diffusion coefficient values obtained under accelerated conditions. PMID:18569312

  10. Nanofluid flow and heat transfer due to a stretching cylinder in the presence of magnetic field

    NASA Astrophysics Data System (ADS)

    Ashorynejad, H. R.; Sheikholeslami, M.; Pop, I.; Ganji, D. D.

    2013-03-01

    In this paper, flow and heat transfer of a nanofluid over a stretching cylinder in the presence of magnetic field has been investigated. The governing partial differential equations with the corresponding boundary conditions are reduced to a set of ordinary differential equations with the appropriate boundary conditions using similarity transformation, which is then solved numerically by the fourth order Runge-Kutta integration scheme featuring a shooting technique. Different types of nanoparticles as copper (Cu), silver (Ag), alumina (Al2O3) and titanium oxide (TiO2) with water as their base fluid has been considered. The influence of significant parameters such as nanoparticle volume fraction, nanofluids type, magnetic parameter and Reynolds number on the flow and heat transfer characteristics is discussed. It was found that the Nusselt number increases as each of Reynolds number or nanoparticles volume fraction increase, but it decreases as magnetic parameter increase. Also it can be found that choosing copper (for small of magnetic parameter) and alumina (for large values of magnetic parameter) leads to the highest cooling performance for this problem.

  11. Cenozoic evidence of displacements along the Meers Fault, southwestern Oklahoma 

    E-print Network

    Kientop, Gregory Allen

    1988-01-01

    -lateral movement (and possibly as many as four) was established near the Bedrock Pit Site. In addition, small (young) drainages are offset vert1cally due to the later Holocene displacements. Brittle deformation was associated with th1s earlier displacement(s... of the Proposed Study Geologic Setting. . . . . . . Physiographic Setting The Meers Fault Study Area . METHODOLOGY Remote Sensing . Pediment Investigation . Wichita Mountains Study Alluvial Fan Excavation Pointer Site Excavation Bedrock Pit Site . Cave...

  12. SOFTWARE ENABLED VARIABLE DISPLACEMENT PUMPS - EXPERIMENTAL STUDIES

    Microsoft Academic Search

    Michael B. Rannow; Haink C. Tu; Perry Y. Li; Thomas R. Chase

    2006-01-01

    The majority of hydraulic systems are controlled using a me- tering valve or the use of variable displacement pumps. Metering valve control is compact and has a high control bandwidth, but it is energy inefficient due to throttling losses. Variable d isplace- ment pumps are far more efficient as the pump only produces the required flow, but comes with the

  13. Shock formation processes due to interactions of two plasmas in a magnetic field and modified two-stream instabilities

    SciTech Connect

    Toida, Mieko; Uragami, Tatsunori [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)] [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)

    2013-11-15

    The study of interactions of exploding and surrounding plasmas in an external magnetic field [K. Yamauchi and Y. Ohsawa, Phys. Plasmas 14, 053110 (2007)] is verified with two-dimensional (2D) electromagnetic particle simulations, for a case in which the initial velocity of the exploding plasma is perpendicular to the external magnetic field. The 2D simulations show essentially the same shock-formation processes as those in the previous one-dimensional simulation, including penetration of exploding ions into surrounding plasma, formation of a strong magnetic-field pulse due to deceleration of the exploding ions, ion reflection by the pulse, and subsequent splitting of the pulse into two magnetosonic pulses which then develop into forward and reverse shock waves. Furthermore, the 2D structure of electromagnetic fields in the region, where the exploding and surrounding ions overlap, is investigated with particular attention to the linear and nonlinear evolution of modified two-stream instabilities in the magnetic field that is being gradually compressed. The effects of these instabilities on ion reflection and on 2D magnetic fluctuations in the two generated pulses are also discussed.

  14. Attenuation of Scalar Fluxes Measured with Spatially-displaced Sensors

    NASA Astrophysics Data System (ADS)

    Horst, T. W.; Lenschow, D. H.

    2009-02-01

    Observations from the Horizontal Array Turbulence Study (HATS) field program are used to examine the attenuation of measured scalar fluxes caused by spatial separation between the vertical velocity and scalar sensors. The HATS data show that flux attenuation for streamwise, crosswind, and vertical sensor displacements are each a function of a dimensionless, stability-dependent parameter n m multiplied by the ratio of sensor displacement to measurement height. The scalar flux decays more rapidly with crosswind displacements than for streamwise displacements and decays more rapidly for stable stratification than for unstable stratification. The cospectral flux attenuation model of Kristensen et al. agrees well with the HATS data for streamwise sensor displacements, although it is necessary to include a neglected quadrature spectrum term to explain the observation that flux attenuation is often less with the scalar sensor downwind of the anemometer than for the opposite configuration. A simpler exponential decay model provides good estimates for crosswind sensor displacements, as well as for streamwise sensor displacements with stable stratification. A model similar to that of Lee and Black correctly predicts flux attenuation for a combination of streamwise and crosswind displacements, i.e. as a function of wind direction relative to the sensor displacement. The HATS data for vertical sensor displacements extend the near-neutral results of Kristensen et al. to diabatic stratification and confirm their finding that flux attenuation is less with the scalar sensor located below the anemometer than if the scalar sensor is displaced an equal distance either horizontally or above the anemometer.

  15. SUBSIDENCE DUE TO GEOTHERMAL FLUID WITHDRAWAL

    SciTech Connect

    Narasimhan, T.N.; Goyal, K.P.

    1982-10-01

    Single-phase and two-phase geothermal reservoirs are currently being exploited for power production in Italy, Mexico, New Zealand, the U.S. and elsewhere. Vertical ground displacements of upto 4.5 m and horizontal ground displacements of up to 0.5 m have been observed at Wairakei, New Zealand that are clearly attributable to the resource exploitation. Similarly, vertical displacements of about 0.13 m have been recorded at The Geysers, California. No significant ground displacements that are attributable to large-scale fluid production have been observed at Larderello, Italy and Cerro Prieto, Mexico. Observations show that subsidence due to geothermal fluid production is characterized by such features as an offset of the subsidence bowl from the main area of production, time-lag between production and subsidence and nonlinear stress-strain relationships. Several plausible conceptual models, of varying degrees of sophistication, have been proposed to explain the observed features. At present, relatively more is known about the physical mechanisms that govern subsidence than the relevant thermal mechanisms. Although attempts have been made to simulate observed geothermal subsidence, the modeling efforts have been seriously limited by a lack of relevant field data needed to sufficiently characterize the complex field system.

  16. Subsidence due to geothermal fluid withdrawal

    SciTech Connect

    Narasimhan, T.N.; Goyal, K.P.

    1982-10-01

    Single-phase and two-phase geothermal reservoirs are currently being exploited for power production in Italy, Mexico, New Zealand, the U.S. and elsewhere. Vertical ground displacements of upto 4.5 m and horizontal ground displacements of up t o 0.5 m have been observed at Wairakei, New Zealand that are clearly attributable to the resource exploitation. Similarly, vertical displacements of about 0.13 m have been recorded at The Geysers, California. No significant ground displacements that are attributable to large-scale fluid production have been observed at Larderello, Italy and Cerro Prieto, Mexico. Observations show that subsidence due to geothermal fluid production is characterized by such features as an offset of the subsidence bowl from the main area of production, time-lag between production and subsidence and nonlinear stress-strain relationships. Several plausible conceptual models, of varying degrees of sophistication, have been proposed to explain the observed features. At present, relatively more is known about the physical mechanisms that govern subsidence than the relevant therma mechanisms. Although attempts have been made to simulate observed geothermal subsidence, the modeling efforts have been seriously limited by a lack of relevant field data needed to sufficiently characterize the complex field system.

  17. Displacement and Velocity Ratios

    NSDL National Science Digital Library

    Bourassa, James

    This interactive presentation, created by James Bourassa and John Rosz for the Electromechanical Digital Library, discusses displacement and velocity ratios. Bourassa and Rosz begin by providing detailed definitions of both topics and then provide mathematical examples of each. Once this basic explanation is complete, the authors allow students to practice these theories in a set of self-correcting quiz questions. Bourassa and Rosz explain each using helpful interactive flash animations. These are not only useful in explanation, but they allow the student to more fully engage with the topic. Overall, this is a nice introduction to the physical and mathematical concepts of displacement and velocity ratios. This could be a valuable learning resource in everything from a physics to a technical education classroom.

  18. Above Water: Buoyancy & Displacement

    NSDL National Science Digital Library

    New Jersey

    2006-01-01

    In an investigation called "Shape It!" learners craft tiny boats out of clay, set them afloat on water and then add weight loads to them, in order to explore: how objects stay afloat in water; what the relationship is among surface tension, buoyancy, density and displacement; and how shape, size, and type of material affect an object's ability to remain buoyant. The introductory text discusses how heavy steel ships can float on bodies of water like rivers, bays and oceans.

  19. Fragmentation due to centrifugal forces in the photodissociation of H{sub 2}{sup +} in intense laser fields

    SciTech Connect

    Fischer, Michael; Schmidt, Ruediger [Institut fuer Theoretische Physik, Technische Universitaet Dresden, Zellescher Weg 17, D-01069 Dresden (Germany); Lorenz, Ulf [HASYLAB at DESY, Notkestr. 85, D-22607 Hamburg (Germany); Schmidt, Burkhard [Institut fuer Mathematik, Freie Universitaet Berlin, Arnimallee 6, D-14195 Berlin (Germany)

    2011-09-15

    By means of quantum-dynamical and classical trajectory calculations of H{sub 2}{sup +} photodissociation in strong laser fields, it is shown that for certain combinations of pulse durations and intensities the rotational dynamics can lead to fragmentation. In that case, the photofragments exhibit characteristic angular distributions. The classical calculations provide a transparent physical picture of this mechanism which is also very well established in collisions between atomic nuclei or liquid droplets: nonrotating systems are stable, whereas rotating systems fragment due to the decrease of the fragmentation barrier with increasing angular momentum.

  20. A Novel and High-Precision Optical Displacement Sensor

    Microsoft Academic Search

    A. Rostami; M. Noshad; H. Hedayati; A. Ghanbari; F. Janabi-Sharifi

    Summary In this paper, theoretical and experimental investigation of a novel compact and high-precision (0.2 nm) optical displacement sensor is presented. The sensor operation is based on optical intensity modulation due to diffraction. A circular disk, including a central transmitter and circumferential receivers (8 and 12 configurations), is considered as high precision displacement sensor. Effects of the number of receivers

  1. Polaronic effects due to quasi-confined optical phonons in wurtzite nitride nanowire in the presence of an electric field

    NASA Astrophysics Data System (ADS)

    Vardanyan, Karen A.; Asatryan, Anna L.; Vartanian, Arshak L.

    2015-07-01

    Considering the effect of an external electric field in wurtzite nitride cylindrical nanowire (NW), the polaron self-energy and effective mass due to the electron interaction with the quasi-confined optical phonons are studied theoretically by means of Lee-Low-Pines variational approach. The analytical expressions for the quasi-one-dimensional Fröhlich polaron self-energy and effective mass are obtained as functions of the wire radius and the strength of the electric field applied perpendicular to the wire axis. It is found that the main contribution to polaron basic parameters is from higher frequency optical phonon modes. The numerical results on the GaN material show that the polaron self-energy increases with the increase of the electric field and is more sensitive to the field when the wire radius is larger. It is also found that the polaron self-energy in GaN NWs is higher than that in zinc-blende GaAs-based cylindrical NWs.

  2. Gas miscible displacement enhanced oil recovery: Technology status report

    SciTech Connect

    Not Available

    1986-10-01

    Gas miscible displacement enhanced oil recovery research is conducted by the US Department of Energy's Morgantown Energy Technology Center to advance the application of miscible carbon dioxide flooding. This research is an integral part of a multidisciplinary effort to improve the technology for producing additional oil from US resources. This report summarizes the problems of the technology and the 1986 results of the ongoing research that was conducted to solve those problems. Poor reservoir volumetric sweep efficiency is the major problem associated with gas flooding and all miscible displacements. This problem results from the channeling and viscous fingering that occur due to the large differences between viscosity or density of the displacing and displaced fluids (i.e., carbon dioxide and oil, respectively). Simple modeling and core flooding studies indicate that, because of differences in fluid viscosities, breakthrough can occur after only 30% of the total pore volume (PV) of the rock has been injected with gas, while field tests have shown breakthrough occurring much earlier. The differences in fluid densities lead to gravity segregation. The lower density carbon dioxide tends to override the residual fluids in the reservoir. This process would be considerably more efficient if a larger area of the reservoir could be contacted by the gas. Current research has focused on the mobility control, computer simulation, and reservoir heterogeneity studies. Three mobility control methods have been investigated: (1) the use of polymers for direct thickening of high-density carbon dioxide, (2) mobile ''foam-like dispersions'' of carbon dioxide and an aqueous surfactant, and (3) in situ deposition of chemical precipitates. 22 refs., 14 figs., 6 tabs.

  3. Polyimidazoles via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor)

    1991-01-01

    Polyimidazoles (Pl) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl)imidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions are carried out in polar aprotic solvents such as N,N-dimethylacetamide, sulfolane, N-methylpyrroldinone, dimethylsulfoxide, or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperature under nitrogen. The di(hydroxyphenyl)imidazole monomers are prepared by reacting an aromatic aldehyde with a dimethoxybenzil or by reacting an aromatic dialdehyde with a methoxybenzil in the presence of ammonium acetate. The di(methoxyphenyl)imidazole is subsequently treated with aqueous hydrobromic acid to give the di(hydroxyphenyl)imidazole monomer. This synthetic route has provided high molecular weight Pl of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the availability of a large variety of activated aromatic dihalides and dinitro compounds.

  4. Polyimidazoles via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (inventor); Hergenrother, Paul M. (inventor)

    1992-01-01

    Polyimidazoles (PI) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl) imidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions are carried out in polar aprotic solvents such as N,N-dimethyl acetamide, sulfolane, N-methylpyrrolidinone, dimethylsulfoxide, or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. The di(hydroxyphenyl) imidazole monomers are prepared by reacting an aromatic aldehyde with a dimethoxybenzil or by reacting an aromatic dialdehyde with a methoxybenzil in the presence of ammonium acetate. The di(methoxyphenyl) imidazole is subsequently treated with aqueous hydrobromic acid to give the di(hydroxphenyl) imidazole monomer. This synthetic route has provided high molecular weight PI of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the availability of a large variety of activated aromatic dihalides and dinitro compounds.

  5. Wavelet denoising of displacement estimates in elastography.

    PubMed

    Techavipoo, Udomchai; Varghese, Tomy

    2004-04-01

    Wavelet shrinkage denoising of the displacement estimates to reduce noise artefacts, especially at high overlaps in elastography, is presented in this paper. Correlated errors in the displacement estimates increase dramatically with an increase in the overlap between the data segments. These increased correlated errors (due to the increased correlation or similarity between consecutive displacement estimates) generate the so-called "worm" artefact in elastography. However, increases in overlap on the order of 90% or higher are essential to improve axial resolution in elastography. The use of wavelet denoising significantly reduces errors in the displacement estimates, thereby reducing the worm artefacts, without compromising on edge (high-frequency or detail) information in the elastogram. Wavelet denoising is a term used to characterize noise rejection by thresholding the wavelet coefficients. Worm artefacts can also be reduced using a low-pass filter; however, low-pass filtering of the displacement estimates does not preserve local information such as abrupt change in slopes, causing the smoothing of edges in the elastograms. Simulation results using the analytic 2-D model of a single inclusion phantom illustrate that wavelet denoising produces elastograms with the closest correspondence to the ideal mechanical strain image. Wavelet denoising applied to experimental data obtained from an in vitro thermal lesion phantom generated using radiofrequency (RF) ablation also illustrates the improvement in the elastogram noise characteristics. PMID:15121250

  6. Joint estimation of real squeezing and displacement

    E-print Network

    G. Chiribella; G. M. D'Ariano; M. F. Sacchi

    2006-01-18

    We study the problem of joint estimation of real squeezing and amplitude of the radiation field, deriving the measurement that maximizes the probability density of detecting the true value of the unknown parameters. More generally, we provide a solution for the problem of estimating the unknown unitary action of a nonunimodular group in the maximum likelihood approach. Remarkably, in this case the optimal measurements do not coincide with the so called square-root measurements. In the case of squeezing and displacement we analyze in detail the sensitivity of estimation for coherent states and displaced squeezed states, deriving the asymptotic relation between the uncertainties in the joint estimation and the corresponding uncertainties in the optimal separate measurements of squeezing and displacement. A two-mode setup is also analyzed, showing how entanglement between optical modes can be used to approximate perfect estimation.

  7. A note on dynamic displacement measurements using Hall effect sensors

    Microsoft Academic Search

    J. H. Giovanola; T. Kobayashi; R. W. Klopp; T. Gaines; R. Arwood

    1989-01-01

    A transducer suitable for dynamic displacement measurements is described. The transducer uses a commercially available Hall effect sensor and a permanent magnet. Displacements are obtained by measuring the variation in magnetic field strength along the permanent magnet with the Hall effect sensor. To illustrate the capabilities of the transducer, we discuss three application examples. The first example demonstrates the good

  8. Optical fiber digital speckle pattern correlation method for displacement measurement

    Microsoft Academic Search

    Rongxun Liu; Xinwei Liu

    1995-01-01

    This paper briefly reviews present situation on optical fiber-speckle method used for measuring displacements or deformations of an object, and the optical fiber-digital white light speckle patterns correlation method for whole field displacement measurement on a remote surface of a trial object is revealed. The principle of correlation method is demonstrated. A special program for image correlation analysis by computer

  9. Blending vocal music with a given sound field due to the characteristics of the running autocorrelation function of singing voices

    NASA Astrophysics Data System (ADS)

    Kato, Kosuke; Fujii, Kenji; Kawai, Keiji; Ando, Yoichi; Yano, Takashi

    2001-05-01

    This is a study to meet music and the opera house acoustics. It is said that singers adjust their interpretation style according to the acoustical condition of the sound field in a room. However, this mechanism of blending of musical performance with the sound field is unknown. In order to obtain a method of performance blending of opera house acoustics, we attempted to develop evaluation criteria for a singing voice in terms of the minimum value of the effective duration of the running autocorrelation function (r-ACF), (te)min, of sound source signals. This temporal factor has shown to have close correlation with the subjective response of both listeners and performers to sound fields [Y. Ando, Architectural Acoustics (AIP Press/Springer-Verlag, New York, 1998)]. As example for the control of (te)min due to performing style, effects of singing style, kind of vowel, relative pitch, vibrato extent, and intonation on the values of (te)min are demonstrated. In addition, the fine structure of the r-ACF is discussed with regard to the identification of vowels of singing voice. a)Now at 1-10-27 Yamanokami, Kumamoto, Japan.

  10. Acoustic Radiation Force on a Finite-Sized Particle due to an Acoustic Field in a Viscous Compressible Fluid

    NASA Astrophysics Data System (ADS)

    Annamalai, Subramanian; Parmar, Manoj; Balachandar, S.

    2013-11-01

    Particles when subjected to acoustic waves experience a time-averaged second-order force known as the acoustic radiation force, which is of prime importance in the fields of microfluidics and acoustic levitation. Here, the acoustic radiation force on a rigid spherical particle in a viscous compressible medium due to progressive and standing waves is considered. The relevant length scales include: particle radius (a), acoustic wavelength (?) and viscous penetration depth (?). While a / ? and a / ? are arbitrary, ? << ? . A farfield derivation approach has been used in determining the radiated force. Expressing the flow-field as a sum of the incident and scattered fields, an analytical expression for the force is obtained as a summation over infinite series (monopole, dipole and higher sources). These results indicate that the contributions from monopole, dipole and their cross-interaction are sufficient to describe the acoustic radiation force. Subsequently, the monopole and dipole strengths are represented in terms of the particle surface and volume averages of the incoming velocity. This generalization allows one to evaluate the radiation force for an incoming wave of any functional form. However acoustic streaming effects are neglected.

  11. Adapting to variable prismatic displacement

    NASA Technical Reports Server (NTRS)

    Welch, Robert B.; Cohen, Malcolm M.

    1989-01-01

    In each of two studies, subjects were exposed to a continuously changing prismatic displacement with a mean value of 19 prism diopters (variable displacement) and to a fixed 19-diopter displacement (fixed displacement). In Experiment 1, significant adaptation (post-pre shifts in hand-eye coordination) was found for fixed, but not for variable, displacement. Experiment 2 demonstrated that adaptation was obtained for variable displacement, but it was very fragile and is lost if the measures of adaptation are preceded by even a very brief exposure of the hand to normal or near-normal vision. Contrary to the results of some previous studies, an increase in within-S dispersion was not found of target pointing responses as a result of exposure to variable displacement.

  12. Cation disorder and anion displacement in DIIXVI - AIBIIIXVI2 semiconductors

    NASA Astrophysics Data System (ADS)

    Schorr, S.; Wagner, G.; Tovar, M.; Sheptyakov, D.

    2006-09-01

    The composition dependent structural phase transitions (tetragonal-cubic) in (ZnX)2x(CuBX2)1-x alloys (B = Ga, In; X = S, Se, Te) were studied by neutron and X-ray powder diffraction as well as TEM. The transitions are due to the interplay of disorder within the cation substructure and the displacement of the anions. It goes along with a phase separation by cation ordering, i. e. there is a miscibility gap (2-phase field), where tetragonal domains and a cubic matrix coexist. Within a homologous series its extension and the particular composition of end members of this 2-phase field depend on the size of the anion. However, for the same anion its width is determined by the BIII cation. For the tetragonal single phase a non-random Zn distribution on the cation sites of the chalcopyrite-type structure was revealed, indicating the tendency of disorder in the cation substructure.

  13. Observation of depth-dependent atomic displacements related to dislocations in GaN by optical sectioning in the STEM

    NASA Astrophysics Data System (ADS)

    Lozano, J. G.; Guerrero-Lebrero, M. P.; Yasuhara, A.; Okinishi, E.; Zhang, S.; Humphreys, C. J.; Galindo, P. L.; Hirsch, P. B.; Nellist, P. D.

    2014-06-01

    We demonstrate that it is possible to observe depth-dependent atomic displacements in a GaN crystal due to the sufficiently small depth of field achievable in the aberration-corrected scanning transmission electron microscope. The depth-dependent displacements associated with the Eshelby twist of screw dislocations in GaN viewed end on are directly imaged, and makes possible the determination of the sign of the Burgers vector of the dislocation. The experimental results are in good agreement with theoretical images.

  14. Unsteady flow simulations in a three-lobe positive displacement blower

    NASA Astrophysics Data System (ADS)

    Liu, Xiaomin; Lu, Jun

    2014-05-01

    To improve the performance of the positive displacement blower, it is imperative to understand the detailed internal flow characteristics or enable a visualization of flow status. However, the existing two-dimensional unsteady, three-dimensional steady or quasi-unsteady numerical simulation and theoretical analysis cannot provide the detailed flow information, which is unfavorable to improve the performance of positive displacement blower. Therefore, the unsteady flow characteristics in a three-lobe positive displacement blower are numerically investigated by solving the three-dimensional, unsteady, compressible Navier-Stokes equations coupled with RNG k- ? turbulent model. In the numerical simulation, the dynamic mesh technique and overset mesh updating method are adopted. Due to the air being compressed in the process of the rotors rotating, the variation of the temperature field in the positive displacement blower is considered. By comparing the experimental measurements and the numerical results on the variation of flow rate with the outlet pressure, the maximum relative error of the flow rate is less than 2.15% even at the maximum outlet pressure condition, which means that the calculation model and numerical computational method used are effective. The numerical results show that in the intake region, the fluctuations of the inlet flow are greatly affected by the direction of the velocity vectors. In the exhaust region, the temperature changes significantly, which leads to the increase of the airflow pulsation. Through analysis on the velocity, pressure and temperature fields obtained from the numerical simulations, three-dimensional unsteady flow characteristics in the positive displacement blower are revealed. The studied results will provide useful reference for improving the performance and empirical correction in the design of the positive displacement blower.

  15. Mapping the earthquake rupture and displacement field using correlation of ALOS PALSAR amplitude images: Application to the Mw 7.9 Sichuan earthquake, 12 May 2008

    Microsoft Academic Search

    D. Raucoules; M. de Michele; H. Aochi; C. Carnec

    2008-01-01

    This study concerns with the mapping of earthquake rupture in the presence of a high magnitude earthquake using remote sensing techniques. In particular, we focus on the Sichuan 2008 earthquake where large surface deformation field hampers the precise localisation of the earthquake rupture using InSAR techniques, even with L-band radar system. If radar interferometry is able to precisely map the

  16. Displacement Parameter Inversion for a Novel Electromagnetic Underground Displacement Sensor

    PubMed Central

    Shentu, Nanying; Li, Qing; Li, Xiong; Tong, Renyuan; Shentu, Nankai; Jiang, Guoqing; Qiu, Guohua

    2014-01-01

    Underground displacement monitoring is an effective method to explore deep into rock and soil masses for execution of subsurface displacement measurements. It is not only an important means of geological hazards prediction and forecasting, but also a forefront, hot and sophisticated subject in current geological disaster monitoring. In previous research, the authors had designed a novel electromagnetic underground horizontal displacement sensor (called the H-type sensor) by combining basic electromagnetic induction principles with modern sensing techniques and established a mutual voltage measurement theoretical model called the Equation-based Equivalent Loop Approach (EELA). Based on that work, this paper presents an underground displacement inversion approach named “EELA forward modeling-approximate inversion method”. Combining the EELA forward simulation approach with the approximate optimization inversion theory, it can deduce the underground horizontal displacement through parameter inversion of the H-type sensor. Comprehensive and comparative studies have been conducted between the experimentally measured and theoretically inversed values of horizontal displacement under counterpart conditions. The results show when the measured horizontal displacements are in the 0–100 mm range, the horizontal displacement inversion discrepancy is generally tested to be less than 3 mm under varied tilt angles and initial axial distances conditions, which indicates that our proposed parameter inversion method can predict underground horizontal displacement measurements effectively and robustly for the H-type sensor and the technique is applicable for practical geo-engineering applications. PMID:24858960

  17. Displacement parameter inversion for a novel electromagnetic underground displacement sensor.

    PubMed

    Shentu, Nanying; Li, Qing; Li, Xiong; Tong, Renyuan; Shentu, Nankai; Jiang, Guoqing; Qiu, Guohua

    2014-01-01

    Underground displacement monitoring is an effective method to explore deep into rock and soil masses for execution of subsurface displacement measurements. It is not only an important means of geological hazards prediction and forecasting, but also a forefront, hot and sophisticated subject in current geological disaster monitoring. In previous research, the authors had designed a novel electromagnetic underground horizontal displacement sensor (called the H-type sensor) by combining basic electromagnetic induction principles with modern sensing techniques and established a mutual voltage measurement theoretical model called the Equation-based Equivalent Loop Approach (EELA). Based on that work, this paper presents an underground displacement inversion approach named "EELA forward modeling-approximate inversion method". Combining the EELA forward simulation approach with the approximate optimization inversion theory, it can deduce the underground horizontal displacement through parameter inversion of the H-type sensor. Comprehensive and comparative studies have been conducted between the experimentally measured and theoretically inversed values of horizontal displacement under counterpart conditions. The results show when the measured horizontal displacements are in the 0-100 mm range, the horizontal displacement inversion discrepancy is generally tested to be less than 3 mm under varied tilt angles and initial axial distances conditions, which indicates that our proposed parameter inversion method can predict underground horizontal displacement measurements effectively and robustly for the H-type sensor and the technique is applicable for practical geo-engineering applications. PMID:24858960

  18. Fuel Efficient Stoves for Darfur Camps of Internally DisplacedPersons - Report of Field Trip to North and South Darfur, Nov. 16 -Dec.17, 2005

    SciTech Connect

    Galitsky, Christina; Gadgil, Ashok; Jacobs, Mark; Lee, Yoo-Mi

    2006-02-01

    Approximately 2.2 million internally displaced persons (''IDPs'') in Darfur are living in dense camps scattered in arid areas with low fuelwood productivity. Unsustainable harvesting of fuelwood by the IDPs has created ever increasing zones of denudation, that now (in November 2005) have reached several kilometers from the camp boundaries. Leaving the safety of the camps to fetch fuelwood from farther and farther away imposes great risk and hardship on the IDP women. Three different metal fuel efficient stove (''FES'') designs were tested in Darfur IDP camps for their suitability to substantially reduce the fuelwood needs of IDPs. The mud-and-dung ''ITDG'' stoves being promoted under the current FES program were also examined and tested. A modified design of the ITDG mud-and-dung stove, ''Avi'', was developed, built and tested. Systematic informal surveys of IDP households were undertaken in North and South Darfur to understand the household parameters related to family size, food, fuel, cooking habits, cooking pots, expenditure on fuel, and preferences related to alternative ways to spend time/money if fuel could be saved. Surveys found that a significant fraction of families are missing meals for lack of fuel (50% in South Darfur, and 90% in the North Darfur camps visited by the mission). About 60% of women in South Darfur, and about 90% of women in North Darfur camps purchase fuelwood. Selling some of the food rations to purchase fuel to cook meals was significant (40%) in South Darfur and has become common (80%) in North Darfur. The LBNL mission found that two of the metal stoves and the mud-and-dung Avi can significantly reduce fuelwood consumption using the same fuel, pot, cooking methods, and food ingredients used by Darfur IDPs. The most suitable design for Darfur conditions would be a modified ''Tara'' stove. With training of the cooks in tending the fire, this stove can save 50% fuel for the IDPs. The stove costs less than $10 (US) to produce in Darfur, and saves fuelwood worth $160 annually at local market prices. For programmatic and administrative reasons, the LBNL mission do not recommend a mud-and-dung stove, for which control of quality and dimensional accuracy is expensive and cumbersome to administer, particularly in a rapid large rollout effort. A light metal stove, on the other hand, can be rapidly produced in large numbers locally in Darfur, with good quality control exercised on the material and dimensions of the stoves right at the workshop where it is produced. LBNL mission also recommends immediate trials of 50 Tara stoves in a pilot technical rollout, 500 Tara stoves in a pilot social rollout, in parallel with a technical effort to modify the Tara design to make it better suited for Darfur camp conditions. The mission also recommends a program for manufacturing, disseminating the metal stoves, and educating the IDPs in fuel-efficient cooking practices. Monitoring of the stove quality, dissemination effort and training should be an integral part of the program, with systematic summaries planned with 10,000, 50,000 and 100,000 stoves have been disseminated. In the above pilot rollouts as well as in the final implementation, it is important to continue to pay attention to training of the cooks in tending the cooking fire in the stoves, and offer continued social reinforcement to this training (e.g., through periodic competitions to cook normal meals with the least fuelwood use.)

  19. A novel method for solving the displacement and stress fields of an infinite domain with circular holes and\\/or inclusions subject to a screw dislocation

    Microsoft Academic Search

    J. T. Chen; K. H. Chou; Y. T. Lee

    2011-01-01

    In this paper, the degenerate kernel and superposition technique are employed to solve the screw dislocation problems with\\u000a circular holes or inclusions. The problem is decomposed into the screw dislocation problem with several holes and the interior\\u000a Laplace problems for several circular inclusions. Following the success of the null-field integral equation approach, the\\u000a typical boundary value problems can be solved

  20. Displacement of the tyrosyl radical cofactor in ribonucleotide reductase obtained by single-crystal high-field EPR and 1.4-A x-ray data.

    PubMed

    Högbom, Martin; Galander, Marcus; Andersson, Martin; Kolberg, Matthias; Hofbauer, Wulf; Lassmann, Günter; Nordlund, Pär; Lendzian, Friedhelm

    2003-03-18

    The R2 protein of class I ribonucleotide reductase generates and stores a tyrosyl radical essential for ribonucleotide reduction and, thus, DNA synthesis. X-ray structures of the protein have enabled detailed mechanistic suggestions, but no structural information has been available for the active radical-containing state of the protein. Here we report on methods to generate the functional tyrosyl radical in single crystals of R2 from Escherichia coli (Y122(*)). We further report on subsequent high-field EPR experiments on the radical-containing crystals. A full rotational pattern of the spectra was collected and the orientation of the g-tensor axes were determined, which directly reflect the orientation of the radical in the crystal frame. The EPR data are discussed in comparison with a 1.42-A x-ray structure of the met (oxidized) form of the protein, also presented in this paper. Comparison of the orientation of the radical Y122(*) obtained from high-field EPR with that of the reduced tyrosine Y122-OH reveals a significant rotation of the tyrosyl side chain, away from the diiron center, in the active radical state. Implications for the radical transfer connecting the diiron site in R2 with the substrate-binding site in R1 are discussed. In addition, the present study demonstrates that structural and functional information about active radical states can be obtained by combined x-ray and high-field EPR crystallography. PMID:12624184

  1. 600-T Magnetic Fields due to Cold Electron Flow in a simple Cu-Coil irradiated by High Power Laser pulses

    E-print Network

    Zhu, Baojun; Yuan, Dawei; Li, Yanfei; Li, Fang; Liao, Guoqian; Zhao, Jiarui; Zhong, Jiayong; Xue, Feibiao; Wei, Huigang; Zhang, Kai; Han, Bo; Pei, Xiaoxing; Liu, Chang; Zhang, Zhe; Wang, Weimin; Zhu, Jianqiang; Zhao, Gang; Zhang, Jie

    2015-01-01

    A new simple mechanism due to cold electron flow to produce strong magnetic field is proposed. A 600-T strong magnetic field is generated in the free space at the laser intensity of 5.7x10^15 Wcm^-2. Theoretical analysis indicates that the magnetic field strength is proportional to laser intensity. Such a strong magnetic field offers a new experimental test bed to study laser-plasma physics, in particular, fast-ignition laser fusion research and laboratory astrophysics.

  2. Measurement of Object Displacement Using Phase Stepped, Real-Time Holographic Interferometry.

    NASA Astrophysics Data System (ADS)

    Ovryn, Benjie

    Phase stepped holographic interferometry is a noncontact method for measuring displacements over a large field of view with a precision of about 5 nm. The whole -field capabilities and high sensitivity of this method make it potentially unrivaled for measuring spatial inhomogeneities, for example, the proposed spatial variation of the piezoelectric coefficient in cortical bone. This dissertation has advanced the capabilities of this technique for the simultaneous, whole-field measurement of two or more components of displacement (1) by providing a detailed analysis of the effect of random and systematic errors on a displacement or strain measurement; (2) by demonstrating that the Carre algorithm, with phase step angles in multiples of pi/4, provides a least squares solution to an over-determined set of phase stepped intensity measurements, minimizes the affect of random and systematic intensity and phase errors and therefore is the best choice for a phase step algorithm; (3) by offering a new method for compensating for spurious systematic drift; (4) by applying of the former method to allow temporal averaging of repeatedly acquired data sets thereby increasing signal-to-noise while maintaining full spatial resolution; (5) by developing a new test procedure for calibrating the apparatus based on displacement of a poled ceramic due to the converse piezoelectric effect and (6) by introducing a two-camera method for measuring two or more components of displacement and strain simultaneously and verifying the methodology for two dimensional displacements of a piezoelectric ceramic. The evidence indicates that this method, which can employ stereo viewing with either two or three cameras, is a promising approach for the simultaneous measurement of two or more components of displacement. The method was also applied to the measurement of displacement in two old samples of dry bovine tibia, held as cantilever beams and subjected to potentials up to 900 V, however, consistent results were not found. The null results indicate either: (1) the samples were no longer piezoelectrically active; (2) the proposed model, which stipulates that the piezoelectric coefficients vary across the bone, is incorrect and/or (3) the appropriate piezoelectric constant is less than 0.001 pm/V.

  3. Research on Joint Parameter Inversion for an Integrated Underground Displacement 3D Measuring Sensor

    PubMed Central

    Shentu, Nanying; Qiu, Guohua; Li, Qing; Tong, Renyuan; Shentu, Nankai; Wang, Yanjie

    2015-01-01

    Underground displacement monitoring is a key means to monitor and evaluate geological disasters and geotechnical projects. There exist few practical instruments able to monitor subsurface horizontal and vertical displacements simultaneously due to monitoring invisibility and complexity. A novel underground displacement 3D measuring sensor had been proposed in our previous studies, and great efforts have been taken in the basic theoretical research of underground displacement sensing and measuring characteristics by virtue of modeling, simulation and experiments. This paper presents an innovative underground displacement joint inversion method by mixing a specific forward modeling approach with an approximate optimization inversion procedure. It can realize a joint inversion of underground horizontal displacement and vertical displacement for the proposed 3D sensor. Comparative studies have been conducted between the measured and inversed parameters of underground horizontal and vertical displacements under a variety of experimental and inverse conditions. The results showed that when experimentally measured horizontal displacements and vertical displacements are both varied within 0 ~ 30 mm, horizontal displacement and vertical displacement inversion discrepancies are generally less than 3 mm and 1 mm, respectively, under three kinds of simulated underground displacement monitoring circumstances. This implies that our proposed underground displacement joint inversion method is robust and efficient to predict the measuring values of underground horizontal and vertical displacements for the proposed sensor. PMID:25871714

  4. Research on joint parameter inversion for an integrated underground displacement 3D measuring sensor.

    PubMed

    Shentu, Nanying; Qiu, Guohua; Li, Qing; Tong, Renyuan; Shentu, Nankai; Wang, Yanjie

    2015-01-01

    Underground displacement monitoring is a key means to monitor and evaluate geological disasters and geotechnical projects. There exist few practical instruments able to monitor subsurface horizontal and vertical displacements simultaneously due to monitoring invisibility and complexity. A novel underground displacement 3D measuring sensor had been proposed in our previous studies, and great efforts have been taken in the basic theoretical research of underground displacement sensing and measuring characteristics by virtue of modeling, simulation and experiments. This paper presents an innovative underground displacement joint inversion method by mixing a specific forward modeling approach with an approximate optimization inversion procedure. It can realize a joint inversion of underground horizontal displacement and vertical displacement for the proposed 3D sensor. Comparative studies have been conducted between the measured and inversed parameters of underground horizontal and vertical displacements under a variety of experimental and inverse conditions. The results showed that when experimentally measured horizontal displacements and vertical displacements are both varied within 0~30 mm, horizontal displacement and vertical displacement inversion discrepancies are generally less than 3 mm and 1 mm, respectively, under three kinds of simulated underground displacement monitoring circumstances. This implies that our proposed underground displacement joint inversion method is robust and efficient to predict the measuring values of underground horizontal and vertical displacements for the proposed sensor. PMID:25871714

  5. Measles outbreaks in displaced populations: a review of transmission, morbidity and mortality associated factors

    Microsoft Academic Search

    Isidore K Kouadio; Taro Kamigaki; Hitoshi Oshitani

    2010-01-01

    BACKGROUND: Measles is a highly contagious infectious disease with a significant public health impact especially among displaced populations due to their characteristic mass population displacement, high population density in camps and low measles vaccination coverage among children. While the fatality rate in stable populations is generally around 2%, evidence shows that it is usually high among populations displaced by disasters.

  6. Prediction of torque and inductance displacement characteristics of asymmetrically slotted variable-reluctance motors using a simplified model for numerical field solution

    SciTech Connect

    Ertan, H.B.

    1999-09-01

    For prediction of static and dynamic performance of doubly-salient motors, it is essential to know their flux linkage-position-excitation characteristics and also the static torque characteristics. At the design stage determination of these characteristics presents difficulties because of highly nonlinear behavior of the magnetic circuit. It is possible to use numerical field solution of the complete motor to obtain this information. This, however, requires expertise on a professional program and may be expensive if used to search for the best design. This paper shows that a reduced model can be used to obtain the desired information accurately. It is also shown that in fact obtaining field solutions just for a pair of teeth is enough for accurately predicting the flux linkage and torque characteristics of a motor. The approach introduced here makes possible searching for an optimum design (even on a PC) for maximizing average torque or reducing noise and vibration problems, since the effort for producing the model and computation time are greatly reduced.

  7. Measurement of ground displacement from optical satellite image correlation using the free open-source software MicMac

    NASA Astrophysics Data System (ADS)

    Rosu, Ana-Maria; Pierrot-Deseilligny, Marc; Delorme, Arthur; Binet, Renaud; Klinger, Yann

    2015-02-01

    Image correlation is one of the most efficient techniques to determine horizontal ground displacements due to earthquakes, landslides, ice flows or sand dune migrations. Analyzing these deformations allows a better understanding of the causes and mechanisms of the events. By using sub-pixel correlation on before- and after-event ortho-images obtained from high resolution satellite images it is possible to compute the displacement field with high planimetric resolution. In this paper, we focus on measuring the ground displacements due to seismotectonic events. The three sub-pixel correlators used are: COSI-Corr - developed by Caltech, a free, closed-source correlator, dependent on commercial software (ENVI) and widely used by the geoscience community for measuring ground displacement; Medicis - developed by CNES, also a closed-source correlator capable of measuring this type of deformation; and MicMac - developed by IGN, the free open-source correlator we study and tune for measuring fine ground displacements. We measured horizontal ground deformation using these three correlators on SPOT images in three study cases: the 2001 Kokoxili earthquake, the 2005 dyke intrusion in the Afar depression and the 2008 Yutian earthquake.

  8. Effects of Notch Misalignment and Tip Radius on Displacement Field in V-Notch Rail Shear Test as Determined by Photogrammetry

    NASA Technical Reports Server (NTRS)

    Hill, Charles S.; Oliveras, Ovidio M.

    2011-01-01

    Evolution of the 3D strain field during ASTM-D-7078 v-notch rail shear tests on 8-ply quasi-isotropic carbon fiber/epoxy laminates was determined by optical photogrammetry using an ARAMIS system. Specimens having non-optimal geometry and minor discrepancies in dimensional tolerances were shown to display non-symmetry and/or stress concentration in the vicinity of the notch relative to a specimen meeting the requirements of the standard, but resulting shear strength and modulus values remained within acceptable bounds of standard deviation. Based on these results, and reported difficulty machining specimens to the required tolerances using available methods, it is suggested that a parametric study combining analytical methods and experiment may provide rationale to increase the tolerances on some specimen dimensions, reducing machining costs, increasing the proportion of acceptable results, and enabling a wider adoption of the test method.

  9. Regenerative rotary displacer Stirling engine

    Microsoft Academic Search

    Naotsugu Isshiki; Luca Raggi; S. Isshiki; K. Hirata; H. Watanabe

    1996-01-01

    A few rotary displacer Stirling engines whose displacers have one gas pocket space at one side, and rotate in a main enclosed cylinder, which is heated from one side and cooled from the opposite side without any regenerator have been tried and studied for a considerable time by the authors. They then tried to improve this engine by equipping them

  10. Evaluation of the scattered pressure due to infinite rigid cylinders, infinite elastic cylindrical shells, and rigid spheres in the presence of an ambient noise field

    Microsoft Academic Search

    Rebecca L. Honeycutt; Steven J. Johnson

    1993-01-01

    The sound scattering due to an ambient noise field, approximated by a squared cosine function, is considered for infinite rigid and elastic cylinders and rigid spheres. For the cylinders, it is assumed that the acoustic wave front is parallel to the axis of the cylinder (informally incident). For this assumption, a closed form expression for the scattered sound field-to-incident ambient

  11. Field Installation and Real-Time Data Processing of the New Integrated SeismoGeodetic System with Real-Time Acceleration and Displacement Measurements for Earthquake Characterization Based on High-Rate Seismic and GPS Data

    NASA Astrophysics Data System (ADS)

    Zimakov, Leonid; Jackson, Michael; Passmore, Paul; Raczka, Jared; Alvarez, Marcos; Barrientos, Sergio

    2015-04-01

    We will discuss and show the results obtained from an integrated SeismoGeodetic System, model SG160-09, installed in the Chilean National Network. The SG160-09 provides the user high rate GNSS and accelerometer data, full epoch-by-epoch measurement integrity and, using the Trimble Pivot™ SeismoGeodetic App, the ability to create combined GNSS and accelerometer high-rate (200Hz) displacement time series in real-time. The SG160-09 combines seismic recording with GNSS geodetic measurement in a single compact, ruggedized package. The system includes a low-power, 220-channel GNSS receiver powered by the latest Trimble-precise Maxwell™6 technology and supports tracking GPS, GLONASS and Galileo signals. The receiver incorporates on-board GNSS point positioning using Real-Time Precise Point Positioning (PPP) technology with satellite clock and orbit corrections delivered over IP networks. The seismic recording element includes an ANSS Class A, force balance triaxial accelerometer with the latest, low power, 24-bit A/D converter, which produces high-resolution seismic data. The SG160-09 processor acquires and packetizes both seismic and geodetic data and transmits it to the central station using an advanced, error-correction protocol with back fill capability providing data integrity between the field and the processing center. The SG160-09 has been installed in the seismic station close to the area of the Iquique earthquake of April 1, 2014, in northern Chile, a seismically prone area at the current time. The hardware includes the SG160-09 system, external Zephyr Geodetic-2 GNSS antenna, and high-speed Internet communication media. Both acceleration and displacement data was transmitted in real-time to the National Seismological Center in Santiago for real-time data processing using Earthworm / Early Bird software. Command/Control of the field station and real-time GNSS position correction are provided via the Pivot software suite. Data from the SG160-09 system was used for seismic event characterization along with data from traditional stand-alone broadband seismic and geodetic stations installed in the network. Our presentation will focus on the key improvements of the network installation with the SG160-09 system, rapid data transmission, and real-time data processing for strong seismic events and aftershock characterization as well as advanced features of the SG160-09 for Earthquake and Tsunami Early Warning system.

  12. Air displacement plethysmography: cradle to grave.

    PubMed

    Fields, David A; Gunatilake, Ravindu; Kalaitzoglou, Evangelia

    2015-04-01

    Differences in body composition are associated with increased disease risk in various stages of life. Despite numerous available methods in assessing body composition (air displacement plethysmography, dual-energy X-ray absorptiometry, bioelectrical impedance, hydrometry, and magnetic resonance imaging), due to innate technical limitations, the ability for one singular method to track body composition over the life span (ie, infancy to adulthood) is challenging and imperfect. The primary goal of this review is to determine if there are body composition methods that can accurately track body composition from infancy into adulthood. After careful consideration and taking into account the best available scientific evidence, we feel air displacement plethysmography is the best instrument at this time for tracking body composition, starting in infancy and forward into adulthood, partly because it is the only "practical" clinical tool currently available for use during infancy. PMID:25761768

  13. Fitting Strains and Displacements by Minimizing Dislocation Energy

    Microsoft Academic Search

    Carlos A. Felippa; K. C. Park

    We present a procedure for matching a displacement field to a given strain field, or vice- versa, over an arbitrary domain, which can be a finite element. The fitting criterion used is minimization of a dislocation energy functional. The strain field, whether given or fitted, need not be compatible. The method has four immediate applications: (i) finite element stiffness formulation

  14. Correcting capacitive displacement measurements in metrology applications with cylindrical artifacts

    Microsoft Academic Search

    Philip T. Smith; R. Ryan Vallance; Eric R. Marsh

    2005-01-01

    Metrology applications commonly require non-contact, capacitive sensors for displacement measurements due to their nanometer resolution. In some metrology applications, for example, the measurement of roundness and spindle error motion, the displacements of stationary and rotating cylindrical artifacts are measured. Error from using a conventionally calibrated sensor with a non-flat (e.g., cylindrical) target is typically neglected, but these errors cannot be

  15. Superconducting inductive displacement detection of a microcantilever

    E-print Network

    Vinante, Andrea

    2014-01-01

    We demonstrate a superconducting inductive technique to measure the displacement of a micromechanical resonator. In our scheme, a type I superconducting microsphere is attached to the free end of a microcantilever and approached to the loop of a dc Superconducting Quantum Interference Device (SQUID) microsusceptometer. A local magnetic field as low as 100 $\\mu$T, generated by a field coil concentric to the SQUID, enables detection of the cantilever thermomechanical noise at $4.2$ K. The magnetomechanical coupling and the magnetic spring are in good agreement with image method calculations assuming pure Meissner effect. These measurements are relevant to recent proposals of quantum magnetomechanics experiments based on levitating superconducting microparticles.

  16. Superconducting inductive displacement detection of a microcantilever

    E-print Network

    Andrea Vinante

    2014-05-14

    We demonstrate a superconducting inductive technique to measure the displacement of a micromechanical resonator. In our scheme, a type I superconducting microsphere is attached to the free end of a microcantilever and approached to the loop of a dc Superconducting Quantum Interference Device (SQUID) microsusceptometer. A local magnetic field as low as 100 $\\mu$T, generated by a field coil concentric to the SQUID, enables detection of the cantilever thermomechanical noise at $4.2$ K. The magnetomechanical coupling and the magnetic spring are in good agreement with image method calculations assuming pure Meissner effect. These measurements are relevant to recent proposals of quantum magnetomechanics experiments based on levitating superconducting microparticles.

  17. Superconducting inductive displacement detection of a microcantilever

    NASA Astrophysics Data System (ADS)

    Vinante, A.

    2014-07-01

    We demonstrate a superconducting inductive technique to measure the displacement of a micromechanical resonator. In our scheme, a type I superconducting microsphere is attached to the free end of a microcantilever and approached to the loop of a dc Superconducting Quantum Interference Device (SQUID) microsusceptometer. A local magnetic field as low as 100 ?T, generated by a field coil concentric to the SQUID, enables detection of the cantilever thermomechanical noise at 4.2 K. The magnetomechanical coupling and the magnetic spring are in good agreement with image method calculations assuming pure Meissner effect. These measurements are relevant to recent proposals of quantum magnetomechanics experiments based on levitating superconducting microparticles.

  18. Application of PCR-Denaturing-Gradient Gel Electrophoresis (DGGE) Method to Examine Microbial Community Structure in Asparagus Fields with Growth Inhibition due to Continuous Cropping

    PubMed Central

    Urashima, Yasufumi; Sonoda, Takahiro; Fujita, Yuko; Uragami, Atsuko

    2012-01-01

    Growth inhibition due to continuous cropping of asparagus is a major problem; the yield of asparagus in replanted fields is low compared to that in new fields, and missing plants occur among young seedlings. Although soil-borne disease and allelochemicals are considered to be involved in this effect, this is still controversial. We aimed to develop a technique for the biological field diagnosis of growth inhibition due to continuous cropping. Therefore, in this study, fungal community structure and Fusarium community structure in continuously cropped fields of asparagus were analyzed by polymerase chain reaction/denaturing-gradient gel electrophoresis (PCR-DGGE). Soil samples were collected from the Aizu region of Fukushima Prefecture, Japan. Soil samples were taken from both continuously cropped fields of asparagus with growth inhibition and healthy neighboring fields of asparagus. The soil samples were collected from the fields of 5 sets in 2008 and 4 sets in 2009. We were able to distinguish between pathogenic and non-pathogenic Fusarium by using Alfie1 and Alfie2GC as the second PCR primers and PCR-DGGE. Fungal community structure was not greatly involved in the growth inhibition of asparagus due to continuous cropping. By contrast, the band ratios of Fusarium oxysporum f. sp. asparagi in growth-inhibited fields were higher than those in neighboring healthy fields. In addition, there was a positive correlation between the band ratios of Fusarium oxysporum f. sp. asparagi and the ratios of missing asparagus plants. We showed the potential of biological field diagnosis of growth inhibition due to continuous cropping of asparagus using PCR-DGGE. PMID:22200640

  19. Wirelessly Interrogated Position or Displacement Sensors

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E.; Taylor, Bryant D.

    2007-01-01

    Two simple position or displacement sensors based on inductance-capacitance resonant circuits have been conceived. These sensors are both powered and interrogated without use of wires and without making contact with other objects. Instead, excitation and interrogation are accomplished by means of a magnetic-field-response recorder. Both of the present position or displacement sensors consist essentially of variable rectangular parallel-plate capacitors electrically connected in series with fixed inductors. Simple inductance-capacitance circuits of the type used in these sensors are inherently robust; their basic mode of operation does not depend on maintenance of specific environmental conditions. Hence, these sensors can be used under such harsh conditions as cryogenic temperatures, high pressures, and radioactivity.

  20. MAXIMUM SEISMIC DISPLACEMENT ESTIMATION USING ACCELERATION RECORD FOR INEASTIC RESPONSE

    NASA Astrophysics Data System (ADS)

    Abe, Masato; Fujino, Yozo

    Rapid evaluation of damage is essential in seismic hazard mitigation. In application of sensor technology in this subject, reliable and simple indicators for seismic damage are necessary. Although maximum displacement response and ductility factor are direct indicators for seismic damage, their measurement involves displacement measurement which is generally difficult in field. In the current study, estimation method for these seismic damage indicators from readily available acceleration record is developed. The method is an extension previous study of the authors on displacement estimation method of elastic structures based on random vibration theory. Accuracy and reliability of the method are evaluated through results of numerical simulation and shaking table experiment, and its applicability is discussed.

  1. DEM Simulated Results And Seismic Interpretation of the Red River Fault Displacements in Vietnam

    NASA Astrophysics Data System (ADS)

    Bui, H. T.; Yamada, Y.; Matsuoka, T.

    2005-12-01

    The Song Hong basin is the largest Tertiary sedimentary basin in Viet Nam. Its onset is approximately 32 Ma ago since the left-lateral displacement of the Red River Fault commenced. Many researches on structures, formation and tectonic evolution of the Song Hong basin have been carried out for a long time but there are still remained some problems that needed to put into continuous discussion such as: magnitude of the displacements, magnitude of movement along the faults, the time of tectonic inversion and right lateral displacement. Especially the mechanism of the Song Hong basin formation is still in controversy with many different hypotheses due to the activation of the Red River fault. In this paper PFC2D based on the Distinct Element Method (DEM) was used to simulate the development of the Red River fault system that controlled the development of the Song Hong basin from the onshore to the elongated portion offshore area. The numerical results show the different parts of the stress field such as compress field, non-stress field, pull-apart field of the dynamic mechanism along the Red River fault in the onshore area. This propagation to the offshore area is partitioned into two main branch faults that are corresponding to the Song Chay and Song Lo fault systems and said to restrain the east and west flanks of the Song Hong basin. The simulation of the Red River motion also showed well the left lateral displacement since its onset. Though it is the first time the DEM method was applied to study the deformation and geodynamic evolution of the Song Hong basin, the results showed reliably applied into the structural configuration evaluation of the Song Hong basin.

  2. Frequency shift of Raman modes due to an applied electric field and domain inversion in LiNbO3

    NASA Astrophysics Data System (ADS)

    Stone, Greg; Knorr, Brian; Gopalan, Venkatraman; Dierolf, Volkmar

    2011-10-01

    We report changes in the frequency of Raman modes in lithium niobate that are observed under the application of external applied electric fields and after domain inversion. Inspection of the Raman peaks reveals that after domain inversion, the internal field of the crystal is reduced. A comparison of the respective frequency shifts for the different Raman modes indicates that this change in the local internal field is not limited to the ferroelectric axis, but the fields orthogonal to the ferroelectric axis also change. The Raman modes also reveal that the strength of the internal field is dependent on the concentration of intrinsic defects present in the crystal.

  3. 40 CFR 205.153 - Engine displacement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...205.153 Engine displacement. (a) Engine displacement must be calculated using nominal engine values and rounded to the nearest whole...Materials (ASTM) E 29-67. (b) For rotary engines, displacement means the maximum...

  4. 40 CFR 205.153 - Engine displacement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...205.153 Engine displacement. (a) Engine displacement must be calculated using nominal engine values and rounded to the nearest whole...Materials (ASTM) E 29-67. (b) For rotary engines, displacement means the maximum...

  5. 40 CFR 205.153 - Engine displacement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...205.153 Engine displacement. (a) Engine displacement must be calculated using nominal engine values and rounded to the nearest whole...Materials (ASTM) E 29-67. (b) For rotary engines, displacement means the maximum...

  6. Displacement sensing system and method

    DOEpatents

    VunKannon, Jr., Robert S

    2006-08-08

    A displacement sensing system and method addresses demanding requirements for high precision sensing of displacement of a shaft, for use typically in a linear electro-dynamic machine, having low failure rates over multi-year unattended operation in hostile environments. Applications include outer space travel by spacecraft having high-temperature, sealed environments without opportunity for servicing over many years of operation. The displacement sensing system uses a three coil sensor configuration, including a reference and sense coils, to provide a pair of ratio-metric signals, which are inputted into a synchronous comparison circuit, which is synchronously processed for a resultant displacement determination. The pair of ratio-metric signals are similarly affected by environmental conditions so that the comparison circuit is able to subtract or nullify environmental conditions that would otherwise cause changes in accuracy to occur.

  7. Protein-water displacement distributions.

    PubMed

    Doster, Wolfgang; Settles, Marcus

    2005-06-01

    The statistical properties of fast protein-water motions are analyzed by dynamic neutron scattering experiments. Using isotopic exchange, one probes either protein or water hydrogen displacements. A moment analysis of the scattering function in the time domain yields model-independent information such as time-resolved mean square displacements and the Gauss-deviation. From the moments, one can reconstruct the displacement distribution. Hydration water displays two dynamical components, related to librational motions and anomalous diffusion along the protein surface. Rotational transitions of side chains, in particular of methyl groups, persist in the dehydrated and in the solvent-vitrified protein structure. The interaction with water induces further continuous protein motions on a small scale. Water acts as a plasticizer of displacements, which couple to functional processes such as open-closed transitions and ligand exchange. PMID:15893505

  8. Microbial Community Shifts due to Hydrofracking: Observations from Field-Scale Observations and Laboratory-Scale Incubations

    NASA Astrophysics Data System (ADS)

    Mouser, P. J.; Ansari, M.; Hartsock, A.; Lui, S.; Lenhart, J.

    2012-12-01

    The use of fluids containing chemicals and variable water sources during the hydrofracking of unconventional shale is the source of considerable controversy due to perceived risks from altered subsurface biogeochemistry and the potential for contaminating potable water supplies. Rapid shifts in subsurface biogeochemistry are often driven by available macronutrients combined with the abundance and metabolic condition of the subsurface microbiota. While the depth that fracturing occurs in the Marcellus formation is reasonably deep to pose little risk to groundwater supplies, no published studies have systematically characterized the indigenous microbial population and how this community is altered through variable fluid management practices (e.g., chemical composition, source water makeup). In addition, limited information is available on how shallower microbial communities and geochemical conditions might be affected through the accidental release of these fluids to groundwater aquifers. Our measurements indicate field-applied and laboratory-generated fracking fluids contain levels of organic carbon greater than 300 mg/l and nitrogen concentrations greater than 80 mg/l that may differentially stimulate microbial growth in subsurface formations. In contrast to certain inorganic constituents (e.g., chloride) which increase in concentration through the flowback period; dissolved organic carbon levels decrease with time after the fracturing process through multiple attenuation processes (dilution, sorption, microbial utilization). Pyrosequencing data of the 16S rRNA gene indicate a shift from a more diverse source water microbial community to a less diverse community typical of a brine formation as time after fracturing increases. The introduction of varying percentages of a laboratory-generated fracking fluid to microcosm bottles containing groundwater and aquifer media stimulated biogeochemical changes similar to the introduction of landfill leachate, another wastewater containing elevated carbon, nitrogen, and complex organic constituents (e.g., decreased redox conditions, stepwise utilization of available terminal electron acceptors, enriched Fe(II) and sulfide concentrations). These research findings are important for understanding how fluids used during shale energy development may alter in situ microbial communities and provide insight into processes that attenuate the migration of these fluids in shallow aquifers and deep shale formations.

  9. Geometric Deformation-Displacement Maps

    Microsoft Academic Search

    Gershon Elber

    2002-01-01

    Texture mapping, bump mapping, and displacement maps are central instruments in computer graphics aiming to achieve photo-realistic renderings. In all these techniques, the mapping is typically one-to-one and a single surface location is assigned a single texture color, normal, or displacement. Other specialized techniques have also been developed for the rendering of supplementary surface details such as fur hair, or

  10. Origin of Intense Magnetic Fields Near Black Holes Due to Non-Minimal Gravitational-Electromagnetic Coupling

    E-print Network

    Rafael S. de Souza; Reuven Opher

    2011-10-21

    The origin of magnetic fields in astrophysical objects is a challenging problem in astrophysics. Throughout the years, many scientists have suggested that non-minimal gravitational-electromagnetic coupling (NMGEC) could be the origin of the ubiquitous astrophysical magnetic fields. We investigate the possible origin of intense magnetic fields $\\sim 10^{15}-10^{16}$ by NMGEC near rotating neutron stars and black holes, connected with magnetars, quasars, and gamma-ray bursts. Whereas these intense magnetic fields are difficult to explain astrophysically, we find that they are easily explained by NMGEC.

  11. Electric field distributions in CdZnTe due to reduced temperature and x-ray irradiation

    SciTech Connect

    Sellin, P. J.; Prekas, G. [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Franc, J.; Grill, R. [Institute of Physics, Charles University Prague, Prague CZ-121 16 (Czech Republic)

    2010-03-29

    Real-time Pockels imaging is performed on semi-insulating CdZnTe to measure the electric field profile in the material bulk. In steady-state room temperature conditions the measured electric field profile is uniform, consistent with a low space charge concentration. At temperatures <270 K a significant nonuniform electric field profile is observed, which we explain in terms of temperature-induced band bending at the metal-semiconductor interface, causing the formation of positive space charge in the bulk. Similar electric field distortion effects are observed when room temperature CdZnTe is irradiated by x-rays, causing a high rate of photoinduced charge injection.

  12. Comparing Teaching Approaches About Maxwell's Displacement Current

    NASA Astrophysics Data System (ADS)

    Karam, Ricardo; Coimbra, Debora; Pietrocola, Maurício

    2014-08-01

    Due to its fundamental role for the consolidation of Maxwell's equations, the displacement current is one of the most important topics of any introductory course on electromagnetism. Moreover, this episode is widely used by historians and philosophers of science as a case study to investigate several issues (e.g. the theory-experiment relationship). Despite the consensus among physics educators concerning the relevance of the topic, there are many possible ways to interpret and justify the need for the displacement current term. With the goal of understanding the didactical transposition of this topic more deeply, we investigate three of its domains: (1) The historical development of Maxwell's reasoning; (2) Different approaches to justify the term insertion in physics textbooks; and (3) Four lectures devoted to introduce the topic in undergraduate level given by four different professors. By reflecting on the differences between these three domains, significant evidence for the knowledge transformation caused by the didactization of this episode is provided. The main purpose of this comparative analysis is to assist physics educators in developing an epistemological surveillance regarding the teaching and learning of the displacement current.

  13. Development of a Wireless Displacement Measurement System Using Acceleration Responses

    PubMed Central

    Park, Jong-Woong; Sim, Sung-Han; Jung, Hyung-Jo; Spencer, Billie F.

    2013-01-01

    Displacement measurements are useful information for various engineering applications such as structural health monitoring (SHM), earthquake engineering and system identification. Most existing displacement measurement methods are costly, labor-intensive, and have difficulties particularly when applying to full-scale civil structures because the methods require stationary reference points. Indirect estimation methods converting acceleration to displacement can be a good alternative as acceleration transducers are generally cost-effective, easy to install, and have low noise. However, the application of acceleration-based methods to full-scale civil structures such as long span bridges is challenging due to the need to install cables to connect the sensors to a base station. This article proposes a low-cost wireless displacement measurement system using acceleration. Developed with smart sensors that are low-cost, wireless, and capable of on-board computation, the wireless displacement measurement system has significant potential to impact many applications that need displacement information at multiple locations of a structure. The system implements an FIR-filter type displacement estimation algorithm that can remove low frequency drifts typically caused by numerical integration of discrete acceleration signals. To verify the accuracy and feasibility of the proposed system, laboratory tests are carried out using a shaking table and on a three storey shear building model, experimentally confirming the effectiveness of the proposed system. PMID:23881123

  14. Development of a wireless displacement measurement system using acceleration responses.

    PubMed

    Park, Jong-Woong; Sim, Sung-Han; Jung, Hyung-Jo; Spencer, Billie F

    2013-01-01

    Displacement measurements are useful information for various engineering applications such as structural health monitoring (SHM), earthquake engineering and system identification. Most existing displacement measurement methods are costly, labor-intensive, and have difficulties particularly when applying to full-scale civil structures because the methods require stationary reference points. Indirect estimation methods converting acceleration to displacement can be a good alternative as acceleration transducers are generally cost-effective, easy to install, and have low noise. However, the application of acceleration-based methods to full-scale civil structures such as long span bridges is challenging due to the need to install cables to connect the sensors to a base station. This article proposes a low-cost wireless displacement measurement system using acceleration. Developed with smart sensors that are low-cost, wireless, and capable of on-board computation, the wireless displacement measurement system has significant potential to impact many applications that need displacement information at multiple locations of a structure. The system implements an FIR-filter type displacement estimation algorithm that can remove low frequency drifts typically caused by numerical integration of discrete acceleration signals. To verify the accuracy and feasibility of the proposed system, laboratory tests are carried out using a shaking table and on a three storey shear building model, experimentally confirming the effectiveness of the proposed system. PMID:23881123

  15. Quantitative two-dimensional micro-displacement measurement by optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Kurokawa, Kazuhiro; Makita, Shuichi; Hong, Young-Joo; Yasuno, Yoshiaki

    2014-03-01

    There are several applications of quantitative micro-displacement measurement of a biological specimen, including characterization of mechanical property and monitoring a laser-induced photothermal expansion. In this study, we proposed a quantitative micro-displacement measurement method using optical coherence tomography (OCT). Specifically, the axial displacement is measured by Doppler OCT and magnitude of displacement is measured by correlation coefficient. By using this method, we measured the local and microdisplacement of the chicken muscles during laser irradiation. The proposed method successfully visualizes thermal changes of chicken muscle due to the laser irradiation. The measured displacement and deformation are useful information for the further understanding of the thermal changes.

  16. Cosmological birefringence due to CPT-even Chern-Simons-like term with Kalb-Ramond and scalar fields

    E-print Network

    Shih-Hao Ho; W. F. Kao; Kazuharu Bamba; C. Q. Geng

    2010-08-03

    We study the CPT-even dimension-six Chern-Simons-like term by including dynamical Kalb-Ramond and scalar fields to examine the cosmological birefringence. We show that the combined effect of neutrino current and Kalb-Ramond field could induce a sizable rotation polarization angle in the cosmic microwave background radiation polarization.

  17. Species displacements are common to two invasive species of leafminer fly in China, Japan and the United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Under field conditions, species displacements have occurred in different directions between the same invasive species of leafminers (Diptera: Agromyzidae). Liriomyza sativae (Blanchard) was displaced by L. trifolii (Burgess) in the western USA, with evidence suggesting that lower insecticide suscept...

  18. Some comments on particle image displacement velocimetry

    NASA Technical Reports Server (NTRS)

    Lourenco, L. M.

    1988-01-01

    Laser speckle velocimetry (LSV) or particle image displacement velocimetry, is introduced. This technique provides the simultaneous visualization of the two-dimensional streamline pattern in unsteady flows as well as the quantification of the velocity field over an entire plane. The advantage of this technique is that the velocity field can be measured over an entire plane of the flow field simultaneously, with accuracy and spatial resolution. From this the instantaneous vorticity field can be easily obtained. This constitutes a great asset for the study of a variety of flows that evolve stochastically in both space and time. The basic concept of LSV; methods of data acquisition and reduction, examples of its use, and parameters that affect its utilization are described.

  19. Anomalous Hanle effect due to optically created transverse overhauser field in single InAs/GaAs quantum dots.

    PubMed

    Krebs, O; Maletinsky, P; Amand, T; Urbaszek, B; Lemaître, A; Voisin, P; Marie, X; Imamoglu, A

    2010-02-01

    We report on experimental observations of an anomalous Hanle effect in individual self-assembled InAs/GaAs quantum dots. A sizable electron spin polarization photocreated under constant illumination is maintained in transverse magnetic fields as high as approximately 1 T, up to a critical field where it abruptly collapses. These striking anomalies of the Hanle curve point to a novel mechanism of dynamic nuclear spin polarization giving rise to an effective magnetic field generated perpendicular to the optically injected electron spin polarization. This transverse Overhauser field, confirmed by the cancellation of electron Zeeman splitting below the critical field, is likely to be a consequence of the strong inhomogeneous quadrupolar interactions typical for strained quantum dots. PMID:20366781

  20. Forest transition in Vietnam and displacement of deforestation abroad

    PubMed Central

    Meyfroidt, Patrick; Lambin, Eric F.

    2009-01-01

    In some countries across the globe, tropical forest cover is increasing. The national-scale reforestation of Vietnam since 1992 is assumed to contribute to this recovery. It is achieved, however, by the displacement of forest extraction to other countries on the order of 49 (34–70) M m3, or ?39% of the regrowth of Vietnam's forests from 1987 to 2006. Approximately half of wood imports to Vietnam during this period were illegal. Leakage due to policies restricting forest exploitation and displacement due to growing domestic consumption and exports contributed respectively to an estimated 58% and 42% of total displacement. Exports of wood products from Vietnam also grew rapidly, amounting to 84% of the displacement, which is a remarkable feature of the forest transition in Vietnam. Attribution of the displacement and corresponding forest extraction to Vietnam, the source countries or the final consumers is thus debatable. Sixty-one percent of the regrowth in Vietnam was, thus, not associated with displacement abroad. Policies allocating credits to countries for reducing deforestation and forest degradation should monitor illegal timber trade and take into account the policy-induced leakage of wood extraction to other countries. PMID:19805270

  1. Forest transition in Vietnam and displacement of deforestation abroad.

    PubMed

    Meyfroidt, Patrick; Lambin, Eric F

    2009-09-22

    In some countries across the globe, tropical forest cover is increasing. The national-scale reforestation of Vietnam since 1992 is assumed to contribute to this recovery. It is achieved, however, by the displacement of forest extraction to other countries on the order of 49 (34-70) M m(3), or approximately 39% of the regrowth of Vietnam's forests from 1987 to 2006. Approximately half of wood imports to Vietnam during this period were illegal. Leakage due to policies restricting forest exploitation and displacement due to growing domestic consumption and exports contributed respectively to an estimated 58% and 42% of total displacement. Exports of wood products from Vietnam also grew rapidly, amounting to 84% of the displacement, which is a remarkable feature of the forest transition in Vietnam. Attribution of the displacement and corresponding forest extraction to Vietnam, the source countries or the final consumers is thus debatable. Sixty-one percent of the regrowth in Vietnam was, thus, not associated with displacement abroad. Policies allocating credits to countries for reducing deforestation and forest degradation should monitor illegal timber trade and take into account the policy-induced leakage of wood extraction to other countries. PMID:19805270

  2. Photonic bandgap Bragg fiber sensors for bending/displacement detection.

    PubMed

    Qu, Hang; Brastaviceanu, Tiberius; Bergeron, Francois; Olesik, Jonathan; Pavlov, Ivan; Ishigure, Takaaki; Skorobogatiy, Maksim

    2013-09-01

    We demonstrate an amplitude-based bending/displacement sensor that uses a plastic photonic bandgap Bragg fiber with one end coated with a silver layer. The reflection intensity of the Bragg fiber is characterized in response to different displacements (or bending curvatures). We note that the Bragg reflector of the fiber acts as an efficient mode stripper for the wavelengths near the edge of the fiber bandgap, which makes the sensor extremely sensitive to bending or displacements at these wavelengths. Besides, by comparison of the Bragg fiber sensor to a sensor based on a standard multimode fiber with similar outer diameter and length, we find that the Bragg fiber sensor is more sensitive to bending due to the presence of a mode stripper in the form of a multilayer reflector. Experimental results show that the minimum detection limit of the Bragg fiber sensor can be as small as 3 ?m for displacement sensing. PMID:24085096

  3. Thermal field in a water body for solar energy storage and extraction due to a buoyant two-dimensional surface water jet

    Microsoft Academic Search

    Y. Jaluria; B. T. OMara

    1989-01-01

    An experimental study on the thermal field arising in an enclosed water body being employed for energy storage, as sensible heat, due to a horizontally discharged, heated, water jet is carried out. Two-dimensional surface discharges are considered, with an outflow located at the far end of a water body, which is simulated in the laboratory by a tank of rectangular

  4. Induced Currents in a Rat's Brain due a Radio Frequency Fields: Numerical Simulation with a Pixel Model

    NASA Astrophysics Data System (ADS)

    Rojas, R.; Garcia, R. D.; Rodríguez, A. O.

    2008-08-01

    The increasing use of high fields in Magnetic Resonance Systems poses new challenges for their operation within safety limits. At high frequencies, electromagnetic fields induce current densities that may damage the organs to be imaged. These eddy currents are transformed in heat via the Joule's effect causing possible severe damage in tissues and organs. The electric field effects in a rat's brain were studied from numerically computed induced currents using a pixel-based model. Numerical simulations were calculated solving the Maxwell's equations with a Finite Element Method for a circular-shaped coil and the pixel model of a rat's brain. Simulations of the electric field were computed and graphically displayed as bi-dimensional transversal images. Profiles of current density as a function of position for four different frequencies were computed from the simulations. An increment of the induced currents can be appreciates at the surface of the brain, and it vanished towards the centre.

  5. Evidence of high-field radio-frequency hot spots due to trapped vortices in niobium cavities

    Microsoft Academic Search

    Gianluigi Ciovati; Alexander Gurevich

    2008-01-01

    Superconducting radio-frequency (rf) cavities made of high-purity niobium exhibit strong anomalous rf losses starting at peak surface magnetic fields of about 90-100 mT in the gigahertz range. This phenomenon is referred to as ``Q drop.'' Temperature maps of the cavity surface have revealed the presence of ``hot spots'' in the high magnetic field region of the cavities. Several models have

  6. Heterodyne interferometric technique for displacement control at the nanometric scale

    E-print Network

    Boyer, Edmond

    -handed, Cartesian coordinate system Fig. 1 . Electro- magnetic field components of the laser beam EL(z,t) can of the lin- ear, simple harmonic oscillations of the electric-field compo- nents along the s and p axes, 0sHeterodyne interferometric technique for displacement control at the nanometric scale Suat Topcu

  7. Application of magnetoelastic waves for sensors of displacement

    Microsoft Academic Search

    Roberto Germano; Luciano Lanotte

    1997-01-01

    It is shown that the amplitude of resonant magnetoclastic waves is very sensitive to local change of magnetic field. Since a moving object can be related to a variation of the magnetic field produced by its displacement, the last one is detected and its amount evaluated by means of a sensor based on magnetoelastic waves. The prototype of this type

  8. A wireless laser displacement sensor node for structural health monitoring.

    PubMed

    Park, Hyo Seon; Kim, Jong Moon; Choi, Se Woon; Kim, Yousok

    2013-01-01

    This study describes a wireless laser displacement sensor node that measures displacement as a representative damage index for structural health monitoring (SHM). The proposed measurement system consists of a laser displacement sensor (LDS) and a customized wireless sensor node. Wireless communication is enabled by a sensor node that consists of a sensor module, a code division multiple access (CDMA) communication module, a processor, and a power module. An LDS with a long measurement distance is chosen to increase field applicability. For a wireless sensor node driven by a battery, we use a power control module with a low-power processor, which facilitates switching between the sleep and active modes, thus maximizing the power consumption efficiency during non-measurement and non-transfer periods. The CDMA mode is also used to overcome the limitation of communication distance, which is a challenge for wireless sensor networks and wireless communication. To evaluate the reliability and field applicability of the proposed wireless displacement measurement system, the system is tested onsite to obtain the required vertical displacement measurements during the construction of mega-trusses and an edge truss, which are the primary structural members in a large-scale irregular building currently under construction. The measurement values confirm the validity of the proposed wireless displacement measurement system and its potential for use in safety evaluations of structural elements. PMID:24084114

  9. A Wireless Laser Displacement Sensor Node for Structural Health Monitoring

    PubMed Central

    Park, Hyo Seon; Kim, Jong Moon; Choi, Se Woon; Kim, Yousok

    2013-01-01

    This study describes a wireless laser displacement sensor node that measures displacement as a representative damage index for structural health monitoring (SHM). The proposed measurement system consists of a laser displacement sensor (LDS) and a customized wireless sensor node. Wireless communication is enabled by a sensor node that consists of a sensor module, a code division multiple access (CDMA) communication module, a processor, and a power module. An LDS with a long measurement distance is chosen to increase field applicability. For a wireless sensor node driven by a battery, we use a power control module with a low-power processor, which facilitates switching between the sleep and active modes, thus maximizing the power consumption efficiency during non-measurement and non-transfer periods. The CDMA mode is also used to overcome the limitation of communication distance, which is a challenge for wireless sensor networks and wireless communication. To evaluate the reliability and field applicability of the proposed wireless displacement measurement system, the system is tested onsite to obtain the required vertical displacement measurements during the construction of mega-trusses and an edge truss, which are the primary structural members in a large-scale irregular building currently under construction. The measurement values confirm the validity of the proposed wireless displacement measurement system and its potential for use in safety evaluations of structural elements. PMID:24084114

  10. Displacement rank of the Drazin inverse

    NASA Astrophysics Data System (ADS)

    Diao, Huaian; Wei, Yimin; Qiao, Sanzheng

    2004-05-01

    In this paper, we study the displacement rank of the Drazin inverse. Both Sylvester displacement and the generalized displacement are discussed. We present upper bounds for the ranks of the displacements of the Drazin inverse. The general results are applied to the group inverse of a structured matrix such as close-to-Toeplitz, generalized Cauchy, Toeplitz-plus-Hankel, and Bezoutians.

  11. Dual pressure displacement control system

    SciTech Connect

    Louis, J.E.; Klocke, C.C.

    1988-02-02

    This patent describes a dual pressure servo control system for a variable displacement hydraulic unit having displacement setting means positioned by a hydraulic servo mechanism. The hydraulic unit is provided with main loop lines at least one of which is capable of being subjected to high main loop pressure during operation of the hydraulic unit, a control line including a displacement control valve providing a controlled flow of fluid under pressure to the servo mechanism, and a source of fluid under pressure for the control line comprising a low pressure source connected to the control line through a check valve and high pressure source comprising of a high pressure control line connected to the control line downstream of the check valve. The high pressure control line includes a flow restriction limiting flow to the control line means and generating a significant flow induced pressure drop in the high pressure control line once movement in the servo mechanism is initiated.

  12. Neutron star deformation due to poloidal-toroidal magnetic fields of arbitrary multipole order: a new analytic approach

    NASA Astrophysics Data System (ADS)

    Mastrano, A.; Suvorov, A. G.; Melatos, A.

    2015-03-01

    A recipe is presented to construct an analytic, self-consistent model of a non-barotropic neutron star with a poloidal-toroidal field of arbitrary multipole order, whose toroidal component is confined in a torus around the neutral curve inside the star, as in numerical simulations of twisted tori. The recipe takes advantage of magnetic field aligned coordinates to ensure continuity of the mass density at the surface of the torus. The density perturbation and ellipticity of such a star are calculated in general and for the special case of a mixed dipole-quadrupole field as a worked example. The calculation generalizes previous work restricted to dipolar, poloidal-toroidal and multipolar, poloidal-only configurations. The results are applied, as an example, to magnetars whose observations (e.g. spectral features and pulse modulation) indicate that the internal magnetic fields may be at least one order of magnitude stronger than the external fields, as inferred from their spin-downs, and are not purely dipolar.

  13. Particle displacement tracking for PIV

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P.

    1990-01-01

    A new Particle Imaging Velocimetry (PIV) data acquisition and analysis system, which is an order of magnitude faster than any previously proposed system has been constructed and tested. The new Particle Displacement Tracing (PDT) system is an all electronic technique employing a video camera and a large memory buffer frame-grabber board. Using a simple encoding scheme, a time sequence of single exposure images are time coded into a single image and then processed to track particle displacements and determine velocity vectors. Application of the PDT technique to a counter-rotating vortex flow produced over 1100 velocity vectors in 110 seconds when processed on an 80386 PC.

  14. Rotor component displacement measurement system

    DOEpatents

    Mercer, Gary D.; Li, Ming C.; Baum, Charles R.

    2003-05-27

    A measuring system for measuring axial displacement of a tube relative to an axially stationary component in a rotating rotor assembly includes at least one displacement sensor adapted to be located normal to a longitudinal axis of the tube; an insulated cable system adapted for passage through the rotor assembly; a rotatable proximitor module located axially beyond the rotor assembly to which the cables are connected; and a telemetry system operatively connected to the proximitor module for sampling signals from the proximitor module and forwarding data to a ground station.

  15. Local strain and defects in silicon wafers due to nanoindentation revealed by full-field X-ray microdiffraction imaging.

    PubMed

    Li, Z J; Danilewsky, A N; Helfen, L; Mikulik, P; Haenschke, D; Wittge, J; Allen, D; McNally, P; Baumbach, T

    2015-07-01

    Quantitative characterization of local strain in silicon wafers is critical in view of issues such as wafer handling during manufacturing and strain engineering. In this work, full-field X-ray microdiffraction imaging using synchrotron radiation is employed to investigate the long-range distribution of strain fields in silicon wafers induced by indents under different conditions in order to simulate wafer fabrication damage. The technique provides a detailed quantitative mapping of strain and defect characterization at the micrometer spatial resolution and holds some advantages over conventional methods. PMID:26134815

  16. ULF magnetic signatures at the earth surface due to ground water flow - A possible precursor to earthquakes

    NASA Technical Reports Server (NTRS)

    Draganov, A. B.; Inan, U. S.; Taranenko, Iu. N.

    1991-01-01

    Magnetic field fluctuations at the earth's surface at less than 1 Hz are shown to result from motion with a peak velocity of about 4 cm/s of ground water (about 4 S/m) at about 5 km depth. Surface field changes can occur due to either divergence free fluid motion with transverse spatial wavelengths of a few tens of km, and/or homogeneous flow which displaces local inhomogeneities in the earth magnetic field.

  17. High precision measurement of magnetization on a single grain material observed by magnetic ejection due to field gradient force

    NASA Astrophysics Data System (ADS)

    Uyeda, Chiaki; Hisayoshi, Keiji

    The orbits of satellites and the reading of clocks onboard give information about the underyling gravitational field. In this contribution we describe the complete and exact set of satellite orbits and the exact reading of clocks onboard in axially symmetric space-times within General Relativity and within a parametrized Post Newtonian framework. We introduce the set of invariant observables (Perihelion shift, Lense-Thirring effect, the progression of nodes, timing effects like gravitational time delay, deflection angles for flyby orbits, gravitational redshift, gravitomagnetic time effects, etc.) which are all characteristic for the gravitational field. The accuracy of the measurement of such observables is discussed in view of the possibility to make precision orbital and clock tests of General Relativity. With satellite orbits and clocks onboard one also can test the foundations of Local Lorentz Invariance. One model for this is based on the Standard Model Extension where Lorentz symmetry is broken by simply adding nondynamical vector and tensor fields to the equations of motion of matter. Another Lorentz invariance violating model where Lorentz invariance violation is nontrivially linked with gravity is Finsler geometry. Though Finsler geometry fully respects the Universality of Free Fall it is not possible to locally transform away gravity. This model consistently describes possibly different Sun-directed accelerations for planetary orbits and for escape orbits and, thus, has the potential to host the Pioneer anomaly (or dark matter effects). The orbital and clocks effects in a Finslerian model of the gravitational field of the Sun or the Earth are described.

  18. Field Survey of Tsunami Effects in Sri Lanka due to the Sumatra-Andaman Earthquake of December 26, 2004

    NASA Astrophysics Data System (ADS)

    Inoue, Shusaku; Wijeyewickrema, Anil C.; Matsumoto, Hiroyuki; Miura, Hiroyuki; Gunaratna, Priyantha; Madurapperuma, Manoj; Sekiguchi, Toru

    2007-03-01

    The December 26, 2004 Sumatra-Andaman earthquake that registered a moment magnitude (M w ) of 9.1 was one of the largest earthquakes in the world since 1900. The devastating tsunami that resulted from this earthquake caused more casualties than any previously reported tsunami. The number of fatalities and missing persons in the most seriously affected countries were Indonesia - 167,736, Sri Lanka - 35,322, India - 18,045 and Thailand - 8,212. This paper describes two field visits to assess tsunami effects in Sri Lanka by a combined team of Japanese and Sri Lankan researchers. The first field visit from December 30, 2004 January 04, 2005 covered the western and southern coasts of Sri Lanka including the cities of Moratuwa, Beruwala, Bentota, Pereliya, Hikkaduwa, Galle, Talpe, Matara, Tangalla and Hambantota. The objectives of the first field visit were to investigate the damage caused by the tsunami and to obtain eyewitness information about wave arrival times. The second field visit from March 10 18, 2005 covered the eastern and southern coasts of Sri Lanka and included Trincomalee, Batticaloa, Arugam Bay, Yala National Park and Kirinda. The objectives of the second visit were mainly to obtain eyewitness information about wave arrival times and inundation data, and to take relevant measurements using GPS instruments.

  19. Assessing building displacement with GPS

    Microsoft Academic Search

    Andrés Seco; Fermín Tirapu; Francisco Ramírez; Beñat García; Jesús Cabrejas

    2007-01-01

    In the frame of its researches concerning GPS positioning the Universidad Pública de Navarra has carried out in 2003 a study to know the possibilities of this positioning technique for monitoring building's displacements. A 30m concrete building was monitored for several months by observations from a geodetic micronetwork placed around.During the observation period the computed variations in position have standard

  20. DISPLACEMENT BASED SEISMIC DESIGN METHODS.

    SciTech Connect

    HOFMAYER,C.MILLER,C.WANG,Y.COSTELLO,J.

    2003-07-15

    A research effort was undertaken to determine the need for any changes to USNRC's seismic regulatory practice to reflect the move, in the earthquake engineering community, toward using expected displacement rather than force (or stress) as the basis for assessing design adequacy. The research explored the extent to which displacement based seismic design methods, such as given in FEMA 273, could be useful for reviewing nuclear power stations. Two structures common to nuclear power plants were chosen to compare the results of the analysis models used. The first structure is a four-story frame structure with shear walls providing the primary lateral load system, referred herein as the shear wall model. The second structure is the turbine building of the Diablo Canyon nuclear power plant. The models were analyzed using both displacement based (pushover) analysis and nonlinear dynamic analysis. In addition, for the shear wall model an elastic analysis with ductility factors applied was also performed. The objectives of the work were to compare the results between the analyses, and to develop insights regarding the work that would be needed before the displacement based analysis methodology could be considered applicable to facilities licensed by the NRC. A summary of the research results, which were published in NUREGICR-6719 in July 2001, is presented in this paper.

  1. Laboratory displacement with micellar solutions

    Microsoft Academic Search

    1967-01-01

    Slugs of micellar solutions, displaced by thickened water, were evaluated in Berea sandstone cores, previously waterflooded to residual oil saturation. The performance and flow behavior of one of these slugs is described. Flooding performance is remarkable: A 1% pore volume slug recovered 59% of the tertiary oil-in-place, while a 5% pore volume slug recovered 100% of the crude oil from

  2. Approximation for radiation power of electrons due to inverse-Compton process in the black-body photon field

    E-print Network

    O. Petruk

    2009-01-13

    An approximation for the inverse-Compton radiation power of electrons in the isotropic black-body photon field is presented. The approximation allows one to calculate inverse-Compton emissivity as integral over the energies of incident electrons rather than over the field photon energies. Such an approach allows for accurate modeling of IC emission of electrons with energy spectra being different from power-law, in situation where the CPU resources are limited. High accuracy of this approximation allows one to use it in a wide range of conditions, from Thomson to extreme Klein-Nishina limits. The approach adopted results also in some new analytic expressions representing known results in the Thomson limit.

  3. Force Field Analysis Suggests a Lowering of Diffusion Barriers in Atomic Manipulation Due to Presence of STM Tip

    NASA Astrophysics Data System (ADS)

    Emmrich, Matthias; Schneiderbauer, Maximilian; Huber, Ferdinand; Weymouth, Alfred J.; Okabayashi, Norio; Giessibl, Franz J.

    2015-04-01

    We study the physics of atomic manipulation of CO on a Cu(111) surface by combined scanning tunneling microscopy and atomic force microscopy at liquid helium temperatures. In atomic manipulation, an adsorbed atom or molecule is arranged on the surface using the interaction of the adsorbate with substrate and tip. While previous experiments are consistent with a linear superposition model of tip and substrate forces, we find that the force threshold depends on the force field of the tip. Here, we use carbon monoxide front atom identification (COFI) to characterize the tip's force field. Tips that show COFI profiles with an attractive center can manipulate CO in any direction while tips with a repulsive center can only manipulate in certain directions. The force thresholds are independent of bias voltage in a range from 1 to 10 mV and independent of temperature in a range of 4.5 to 7.5 K.

  4. Distillability sudden death in two-qutrit systems with external magnetic field and Dzyaloshinskii-Moriya interaction due to decoherence

    NASA Astrophysics Data System (ADS)

    Guo, You-neng; Fang, Mao-fa; Zhang, Shi-yang; Liu, Xiang

    2014-11-01

    Recently, Mazhar Ali (Phys. Rev. A, 81 (2010) 042303 and J. Phys. B, 43 (2010) 045504) showed the phenomenon of distillability sudden death (DSD) in qutrit-qutrit systems under amplitude damping. In this paper, the phenomenon of distillability sudden death in two-qutrit systems which are in the presence of the external magnetic field and Dzyaloshinskii-Moriya (DM) interaction under decoherence has been investigated. With the help of the realignment criterion, we show that certain initial prepared free entangled states may become bound entangled states in a finite time. Moreover, the effects of the external magnetic field strength and the DM interaction parameter, as well as the intrinsic decoherence parameter on the possibility of DSD in our model have been studied in detail.

  5. Purity loss and degradation of qubit-field correlations and entanglement due to phase noise in nonlinear interaction

    NASA Astrophysics Data System (ADS)

    Hessian, H. A.; Mohamed, A.-B. A.

    2014-09-01

    Numerical simulations and calculation of both the total entropy and the sub-entropies are used to investigate the purity loss in nonlinear interaction of a qubit with coherent field. While, the mutual entropy is used as a measure of the total correlations and the negativity as a measure to the entanglement. We show that the purity and entanglement behave different for standard energy dissipation as compared to an energy preserving phase noise coupling as introduced by Milburn. It is found that a very strong sensitivity of the degradation both total correlation with entanglement to the amount of phase damping and the chosen coupling. In particular for a coherent initial field state the maximum obtainable correlation is strongly reduced even for very weak noise.

  6. Temperature increase in human eyes due to near-field and far-field exposures at 900 MHz, 1.5 GHz, and 1.9 GHz

    Microsoft Academic Search

    Akimasa Hirata

    2005-01-01

    This work investigates the effect of frequency, polarization, and angle of incidence of an electromagnetic (EM) wave on the specific absorption rate (SAR) and maximum temperature increase in the human eye at 900 MHz, 1.5 GHz, and 1.9 GHz. In particular, the temperature increase in the eye is compared for near-field and far-field exposures. The difference of a maximum temperature

  7. Comments on the impedances of the SSC shielded bellows at low frequencies due to the truncation of the wake fields

    SciTech Connect

    Ng, K.Y.

    1986-09-01

    The behavior of the longitudinal impedance of the SSC shielded bellow at low frequencies depends very much on the length of the wake field used in the Fourier transformation. We show analytically and numerically that, regardless of the difference, single-bunch effects are independent of the actual shape of the impedance when the length of the wake used is bigger than the bunch length.

  8. Land subsidence due to groundwater withdrawal detected by InSAR time-series in Tazerbo well field, Libya

    NASA Astrophysics Data System (ADS)

    Tufekci, Nesrin; Schoups, Gerrit; Mahapatra, Pooja; van de Giesen, Nick; Hanssen, Ramon F.

    2014-05-01

    The Tazerbo well field is one of the well fields designed within the Great Man-Made River Project (GMMRP), which aims to deliver water to the eastern coast of Libya through an underground pipe network. It consists of 108 wells in three rows, where the wells are separated 1.3 km in longitude and 10 km in latitude. The planned total groundwater withdrawal from all wells is 1 million m3/day. The water is pumped from the deep sandstone aquifer (Nubian sandstone), which is overlaid by a thick mudstone-siltstone aquitard. Being heavily pumped, the aquifer and fine-grained sediments of the aquitard are expected to compact in time resulting in land subsidence. In order to investigate the surface deformation caused by groundwater pumping in the Tazerbo well field, Interferometric Synthetic Aperture Radar (InSAR) technique was utilized. InSAR is widely used for monitoring land subsidence and can provide sub-cm scale deformation information over large areas. Using the Persistent Scatterer method, SAR time series of 20 Envisat images, spanning from 2004 to 2010, are employed to analyze spatial and temporal distribution of land subsidence induced by groundwater withdrawal. The results are in a good agreement with simulated subsidence. In addition, the spatial distribution of InSAR observations seems to be promising in terms of detecting spatial heterogeneity of aquifer material.

  9. GPS monitoring of the thropospheric water vapor fields due to "Vince" tropical cyclone in October 2005 (South Iberian Peninsula)

    NASA Astrophysics Data System (ADS)

    Seco, A.; Ramirez, F.; Gonzalez, P. J.; García, R.; Yagüe, C.; Miqueleiz, L.; Fernández, J.

    2009-04-01

    We present the GPS estimated water vapor content, distribution and temporal variation due to the "Vince" tropical cyclone on October 11th, 2005 in its track over the Southern part of the Iberian Peninsula. The anomalous event (Vince is the only "historical" tropical cyclone that arrived the Iberian Peninsula) was studied using a sparse array of GPS stations throughout South Portugal and Spain. Analysis of GPS data recorded significant increases of Zenith Tropospheric Delay (ZTD), Zenith Wet Delay (ZTD) and precipitable water (PW). These increments were observed in all the GPS stations along October 11th, corresponding with the West-to-East observed track of Vince. Unusual values of ZTD, ZWD and PW was decreasing gradually from the western stations to the eastern stations. This observation correlates well with the Vince's weakening, due to lack of water vapor inputs (Atlantic ocean) and its intrusion into the continental area (Southern Iberian). Furthermore, good correlation has been observed between PW values and torrential rainfalls registered at rain gauges from the available meteorological networks.

  10. Mineral displacement and -dissolution processes and their relevance to rock porosity and permeability in Rotliegend sandstones of the Altmark natural gas field (central Germany) - results from CO2 laboratory batch experiments

    NASA Astrophysics Data System (ADS)

    Pudlo, Dieter; Enzmann, Frieder; Heister, Katja; Werner, Lars; Ganzer, Leonhard; Reitenbach, Viktor; Henkel, Steven; Albrecht, Daniel; Gaupp, Reinhard

    2014-05-01

    The Rotliegend reservoir sandstones of the Altmark area (central Germany) comprise the second largest natural gas field of Europe. These sandstones were deposited on a playa-like continental platform with braided river systems, ephemeral lakes and aeolian dunes under semi-arid conditions. Some of the pristine, red coloured deposits suffered intensive late diagenetic alteration and are now preserved as bleached, high porous and permeable sandstones. To evaluate the relevance of distinct fluids and their fluid-rock alteration reactions on such bleaching processes we performed laboratory static batch experiments on the Altmark sandstones. These 4-6 week lasting runs were conducted with CO2 saturated synthetic brines under typical Altmark reservoir conditions (p= 20 MPa, T= 125°C). Thereby mineralogical, petrophysical and (hydro- and geo-) chemical rock features were maintained prior and after the experiments. Chemical data proved the dissolution of carbonate and sulphate minerals during the runs, whereas the variation in abundance of further elements was within the detection limit of analytical accuracy. However, FE-SEM investigations on used, evaporated brines reveal the presence of illite and chlorite minerals within a matrix of Ca-, Si-, Fe, Al-, Na- and S components (carbonate, anhydrite, albite and Fe-(hydr-) oxides ?). By porosity and relative permeability measurements an increase in both rock features was observed after the runs, indicating that mineral dissolution and/or (clay) fine migration/detachment occurred during the experiments. Mineral dissolution, especially of pore-filling cements (e.g. carbonate-, sulphate minerals) is also deduced by BET analysis, in determining the specific surface of the sandstones. The size of these reactive surfaces increased after the experiments, suggesting that after the dissolution of pore-filling cements, formerly armoured grain rimming clay cutans were exposed to potential migrating fluids. These findings are also supported by µ-CT investigations. Here, the achieved 3D modelling data indicate an increase in reactive surface areas exposed to the pore space (which is in accord to the BET observations), as well as an enhancement in rock porosity and permeability after the runs. Moreover, these simulations showed that a remarkable mass (mineral) transfer was induced by the experiments, which led to a displacement of the porosity and permeability distribution in the sandstones and therefore a change in the fluid flow characteristics within the rocks - a parameter most important for every fluid-rock process. These observations are quite astonishing because they suggest that not only fluid velocity (e.g. during fluid flow experiments) might detach and transport grain rimming (clay) minerals, but also that physico-chemical reactions may enforce the release of such solids, even during almost static p-/T-/Xfluid conditions, as used in our experiments.

  11. Large displacement formulation of a three-dimensional beam element with cross-sectional warping

    Microsoft Academic Search

    A. Dutta; D. W. White

    1992-01-01

    A displacement-based three-node beam element is formulated for analysis of the large displacement\\/large rotation response of curved structural components of rectangular cross-section, including the effects of cross-sectional warping due to torsion. Master-slave relationships are derived which facilitate the modeling of eccentric stiffeners in plate and shell structures. Efficient and explicit relationships are developed for transformation between relative through-thickness displacement and

  12. Linearly polarized radiation from astrophysical masers due to magnetic fields when the rate for stimulated emission exceeds the Zeeman frequency

    NASA Technical Reports Server (NTRS)

    Deguchi, Shuji; Watson, William D.

    1990-01-01

    The results are presented of reformulating the treatment of polarized maser radiation in the presence of magnetic fields in a way that seems somewhat more convenient for calculations with masing states having angular momenta greater than J = 1 and 0. Calculations are then performed for the case of small Zeeman splitting using idealizations which are equivalant to those made previously in calculations for a J = 1-0 transition. The results provide a complete, general description of the polarization characteristics of astrophysical maser radiation involving states of higher angular momentum of closed-shell molecules.

  13. Free displacer and Ringbom displacer for a Malone refrigerator

    SciTech Connect

    Swift, G.W.; Brown, A.O.

    1994-05-01

    Malone refrigeration uses a liquid near its critical point (instead of the customary gas) as the working fluid in a Stirling, Brayton, or similar regenerative or recuperative cycle. Thus far, we have focused on the Stirling cycle, to avoid the difficult construction of the high-pressure-difference counterflow recuperator required for a Brayton machine. Our first Malone refrigerator used liquid propylene (C{sub 3}H{sub 6}) in a double-acting 4-cylinder Stirling configuration. First measurements with a free displacer used in a liquid working fluid are presented. The displacer was operated both in harmonic mode and in Ringbom mode, in liquid carbon dioxide. The results are in reasonable agreement with expectations.

  14. Full Three-Dimensional Simulation of Ion-Sensitive Field-Effect Transistor Flatband Voltage Shifts Due to DNA Immobilization and Hybridization

    Microsoft Academic Search

    Shigeyasu Uno; Mami Iio; Hiroaki Ozawa; Kazuo Nakazato

    2010-01-01

    A full three-dimensional simulation of the ion-sensitive field-effect transistor flatband voltage shifts due to DNA immobilization and hybridization is presented. Poisson's equation is solved for a domain consisting of an electrolyte, DNA, Stern layer, linker molecular layer, and nitride layer. DNA is modeled as an insulating cylinder with discrete negative charges at the coordinates of phosphate groups. The site binding

  15. Photonic bandgap Bragg fiber sensors for bending/displacement detection

    E-print Network

    Skorobogatiy, Maksim

    diameter and length, we find that the Bragg fiber sensor is more sensitive to bending due to the presencePhotonic bandgap Bragg fiber sensors for bending/displacement detection Hang Qu,1 Tiberius Bragg fiber with one end coated with a silver layer. The reflection intensity of the Bragg fiber

  16. Comparing Teaching Approaches about Maxwell's Displacement Current

    ERIC Educational Resources Information Center

    Karam, Ricardo; Coimbra, Debora; Pietrocola, Maurício

    2014-01-01

    Due to its fundamental role for the consolidation of Maxwell's equations, the displacement current is one of the most important topics of any introductory course on electromagnetism. Moreover, this episode is widely used by historians and philosophers of science as a case study to investigate several issues (e.g. the theory-experiment…

  17. A novel approach to modeling unstable EOR displacements. Final report

    SciTech Connect

    Peters, E.J.

    1994-04-01

    Most enhanced oil recovery schemes involve the displacement of a more dense and more viscous oil by a less dense and less viscous fluid in a heterogeneous porous medium. The interaction of heterogeneity with the several competing forces, namely, viscous, capillary, gravitational, and dispersive forces, can conspire to make the displacements unstable and difficult to model and to predict. The objective of this research was to develop a systematic methodology for modeling unstable fluid displacements in heterogeneous media. Flow visualization experiments were conducted using X-ray computed tomography imaging and a video imaging workstation to gain insights into the dynamics of unstable displacements, acquire detailed quantitative experimental image data for calibrating numerical models of unstable displacements, and image and characterize heterogeneities in laboratory cores geostatistically. High-resolution numerical models modified for use on vector-architecture supercomputers were used to replicate the image data. Geostatistical models of reservoir heterogeneity were incorporated in order to study the interaction of hydrodynamic instability and heterogeneity in reservoir displacements. Finally, a systematic methodology for matching the experimental data with the numerical models and scaling the laboratory results to other systems were developed. The result is a new method for predicting the performance of unstable EOR displacements in the field based on small-scale displacements in the laboratory. The methodology is general and can be applied to forecast the performance of most processes that involve fluid flow and transport in porous media. Therefore, this research should be of interest to those involved in forecasting the performance of enhanced oil recovery processes and the spreading of contaminants in heterogeneous aquifers.

  18. Dynamic displacement measurement of bridges using vision-based system

    NASA Astrophysics Data System (ADS)

    Lee, Jong-Jae; Fukuda, Yoshio; Shinozuka, Masanobu

    2006-03-01

    Measuring the displacement of flexible bridges directly is difficult particularly on monumental suspension bridges. Since these bridges cross over sea channels or large rivers, installation of conventional devices for displacement measurement is technically not easy and costly, if not impossible. In this study, real-time displacement measurement of bridges was carried out by means of digital image processing techniques. This is innovative, highly cost-effective and easy to implement, and yet maintains the advantages of dynamic measurement and high resolution. First, the measurement point is marked on the bridge with a target panel of known geometry. A commercially available digital video camcorder is installed on a fixed point some distance from the bridge (e.g. on the coast) or on a pier (abutment) of the bridge which can be regarded as a fixed point. The camcorder with a telescopic device installed takes a motion picture of the target marked. Meanwhile, the displacement of the target is calculated using an image processing technique, which requires a target recognition algorithm, projection of the captured image, and calculation of the actual displacement using target geometry and the number of pixels moved. To measure the displacement at multiple locations on the bridge, an effective synchronized vision-based system was developed using master/slave system and wireless data communication. For the purpose of verification, the measured displacement by synchronized vision-based system was compared with the data measured by a contact-type sensor, a linear variable differential transformer (LVDT) from laboratory tests. The displacement measured by the proposed method showed a good agreement with the data from the conventional sensors. A field test on a pedestrian suspension bridge was also carried out to check the feasibility of the proposed system.

  19. Full Three-Dimensional Simulation of Ion-Sensitive Field-Effect Transistor Flatband Voltage Shifts Due to DNA Immobilization and Hybridization

    NASA Astrophysics Data System (ADS)

    Uno, Shigeyasu; Iio, Mami; Ozawa, Hiroaki; Nakazato, Kazuo

    2010-01-01

    A full three-dimensional simulation of the ion-sensitive field-effect transistor flatband voltage shifts due to DNA immobilization and hybridization is presented. Poisson's equation is solved for a domain consisting of an electrolyte, DNA, Stern layer, linker molecular layer, and nitride layer. DNA is modeled as an insulating cylinder with discrete negative charges at the coordinates of phosphate groups. The site binding on the nitride surface significantly suppresses the flatband voltage shift due to DNA charge, while switching off the site binding gives results close to experimentally reported values. Increasing DNA density or decreasing salt concentration leads to increasing flatband voltage shifts for both immobilization and hybridization. The flatband voltage shift due to DNA hybridization is proportional to DNA density at a high salt concentration or a low DNA density. At a low salt concentration and a high DNA density, however, the flatband voltage dependence on DNA density deviates from this proportional relationship.

  20. Investigation of instability of displacement front in non-isothermal flow problems

    NASA Astrophysics Data System (ADS)

    Syulyukina, Natalia; Pergament, Anna

    2012-11-01

    In this paper, we investigate the issues of front instability arising in non-isothermal flow displacement processes. The problem of two-phase flow of immiscible fluids, oil and water, is considered, including sources and dependence of viscosity on temperature. Three-dimensional problem with perturbation close to the injection well was considered to find the characteristic scale of the instability. As a result of numerical calculations, theoretical studies on the development of the instability due to the fact that the viscosity of the displacing fluid is less than the viscosity of the displaced have been confirmed. The influence of temperature on the evolution of the instability was considered. For this purpose, the dependence of oil viscosity on temperature has been added to the problem. Numerical calculations were carried out for different values of temperature and it was shown that with increasing of production rate. Thus, it has been demonstrated that the selection of the optimal temperature for injected fluids a possible way for stimulation of oil production also delaying the field water-flooding. This work was supporting by the RFBR grant 12-01-00793-a.

  1. Analog-to-digital conversion as a source of drifts in displacements derived from digital recordings of ground acceleration

    USGS Publications Warehouse

    Boore, D.M.

    2003-01-01

    Displacements obtained from double integration of digitally recorded ground accelerations often show drifts much larger than those expected for the true ground displacements. These drifts might be due to many things, including dynamic elastic ground tilt, inelastic ground deformation, hysteresis in the instruments, and cross feed due to misalignment of nominally orthogonal sensors. This article shows that even if those effects were not present, the analog-to-digital conversion (ADC) process can produce apparent "pulses" and offsets in the acceleration baseline if the ground motion is slowly varying compared with the quantization level of the digitization. Such slowly varying signals can be produced by constant offsets that do not coincide with a quantization level and by near- and intermediate-field terms in the wave field radiated from earthquakes. Double integration of these apparent pulses and offsets leads to drifts in the displacements similar to those found in processing real recordings. These effects decrease in importance as the resolution of the ADC process increases.

  2. Far-field self-focusing and -defocusing radiation behaviors of the electroluminescent light sources due to negative refraction.

    PubMed

    Yin, Yu-Feng; Lin, Yen-Chen; Tsai, Tsung-Han; Shen, Yi-Chun; Huang, Jianjang

    2013-01-15

    In recent years, researchers have demonstrated negative refraction theoretically and experimentally by pumping optical power into photonic crystal (PhC) or waveguide structures. The concept of negative refraction can be used to create a perfect lens that focuses an object smaller than the wavelength. By inserting two-dimensional PhCs into the peripheral of a semiconductor light emitting structure, this study presents an electroluminescent device with negative refraction in the visible wavelength range. This approach produces polarization dependent collimation behavior in far-field radiation patterns. The modal dispersion of negative refraction results in strong group velocity modulation, and self-focusing and -defocusing behaviors are apparent from light extraction. This study further verifies experimental results by using theoretic calculations based on equifrequency contours. PMID:23454956

  3. Transient Phenomena of Current and Field Distortion due to Dynamics of Packet-Like Charges in LDPE Films

    NASA Astrophysics Data System (ADS)

    Yoshioka, Hirokazu; Kadowaki, Kazunori; Kitani, Isamu

    Simultaneous measurements for space charge and external current were carried out using a PEA measurement system with an electrometer on the back of a grounding electrode in order to clarify physical situation of a huge packet of positive space charges in LDPE films. A large number of positive charges from semi-conduction anode were accumulated at the interface between LDPE and Al-cathode under 1.5MV/cm of mean applied field and then they finally disappeared. Results of the simultaneous measurements showed that the external current kept a relatively high value during the charge accumulation and it further increased when the charges disappeared. Both the charge dynamics and the external current were restricted by addition of a low-molecular-weight paraffin wax, indicating that the carrier transport was influenced by micro structure of the polymer. Dynamics of residual charges after short-circuiting is also discussed.

  4. Field measurements and modeling of wave propagation and subsequent weak layer failure in snow due to explosive loading

    NASA Astrophysics Data System (ADS)

    Simioni, Stephan; Sidler, Rolf; Dual, Jürg; Schweizer, Jürg

    2015-04-01

    Avalanche control by explosives is among the key temporary preventive measures. Yet, little is known about the mechanism involved in releasing avalanches by the effect of an explosion. Here, we test the hypothesis that the stress induced by acoustic waves exceeds the strength of weak snow layers. Consequently the snow fails and the onset of rapid crack propagation might finally lead to the release of a snow slab avalanche. We performed experiments with explosive charges over a snowpack. We installed microphones above the snowpack to measure near-surface air pressure and accelerometers within three snow pits. We also recorded pit walls of each pit with high speed cameras to detect weak layer failure. Empirical relationships and a priori information from ice and air were used to characterize a porous layered model from density measurements of snow profiles in the snow pits. This model was used to perform two-dimensional numerical simulations of wave propagation in Biot-type porous material. Locations of snow failure were identified in the simulation by comparing the axial and deviatoric stress field of the simulation to the corresponding snow strength. The identified snow failure locations corresponded well with the observed failure locations in the experiment. The acceleration measured in the snowpack best correlated with the modeled acceleration of the fluid relative to the ice frame. Even though the near field of the explosion is expected to be governed by non-linear effects as for example the observed supersonic wave propagation in the air above the snow surface, the results of the linear poroelastic simulation fit well with the measured air pressure and snowpack accelerations. The results of this comparison are an important step towards quantifying the effectiveness of avalanche control by explosives.

  5. Size effects on electromechanical coupling fields of a bending piezoelectric nanoplate due to surface effects and flexoelectricity

    NASA Astrophysics Data System (ADS)

    Zhang, Zhengrong; Jiang, Liying

    2014-10-01

    Due to large surface to volume ratio and manifest strain gradients typically present in nanostructures, it is essential to incorporate both surface effects and flexoelectricity in studying the size-dependent electromechanical coupling behaviors of piezoelectric materials at the nano-scale. In the current work, a modified Kirchhoff plate model with the consideration of residual surface stress, surface elasticity, surface piezoelectricity, and flexoelectricity is developed to investigate the electroelastic responses and vibrational behaviors of a bending piezoelectric nanoplate (PNP). The governing equations and the corresponding boundary conditions accounting for both the surface effects and the flexoelectricity are derived by the variational principle. Ritz approximate solutions of the static bending and the free vibration indicate that these nano-scale features are more prominent for thinner plates with smaller thickness. The simulation results also reveal that the influence of the flexoelectricity and the surface effects upon the bending behaviors of the PNP depends on the applied electrical loading and the plate dimensions. Moreover, it is also observed that the frequency tuning of PNP-based nanoresonators by adjusting applied electrical load can be modified by both the flexoelectricity and the surface effects. The current work is expected to provide increased understanding on the theoretical basis for the design and applications of PNP-based nanodevices.

  6. Polybenzimidazole via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergenrother, Paul M. (Inventor); Smith, Joseph G. (Inventor)

    1994-01-01

    Di(hydroxyphenyl)benzimidazole monomers were prepared from phenyl-4-hydroxybenzoate and aromatic bis(o-diamine)s. These monomers were used in the synthesis of soluble polybenzimidazoles. The reaction involved the aromatic nucleophilic displacement of various di(hydroxyphenyl)benzimidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds in the presence of an alkali metal base. These polymers exhibited lower glass transition temperatures, improved solubility, and better compression moldability over their commercial counterparts.

  7. Upscaling of Miscible Displacement Processes

    Microsoft Academic Search

    Dengen Zhou; Jairam Kamath; Lou Durlofsky; Erling H. Stenby

    In this paper, we present an approach for upscaling miscible displacement processes using a modified Todd-Longstaff (T-L) formulation. The T-L formulation is modified to include pseudo fractional flow curves. The pseudo fractional flow curves are calculated for each upscaled grid using the upscaling technique proposed by Christie et al.1 The new procedure is applied to a 2-D cross-section model. We

  8. Efficient Current-Induced Domain-Wall Displacement in SrRuO3

    Microsoft Academic Search

    Michael Feigenson; James W. Reiner; Lior Klein

    2007-01-01

    We demonstrate current-induced displacement of ferromagnetic domain walls in submicrometer fabricated patterns of SrRuO3 films. The displacement, monitored by measuring the extraordinary Hall effect, is induced at zero applied magnetic field and its direction is reversed when the current is reversed. We find that current density in the range of 109 1010A\\/m2 is sufficient for domain-wall displacement when the depinning

  9. Reexamination of relaxation of spins due to a magnetic field gradient: Identity of the Redfield and Torrey theories

    SciTech Connect

    Golub, R.; Rohm, Ryan M.; Swank, C. M. [Physics Department, North Carolina State University, Raleigh, North Carolina 27695 (United States); Physics Department, University of North Carolina, Chapel Hill, North Carolina 27599 (United States)

    2011-02-15

    There is an extensive literature on magnetic-gradient-induced spin relaxation. Cates, Schaefer, and Happer, in a seminal publication, have solved the problem in the regime where diffusion theory (the Torrey equation) is applicable using an expansion of the density matrix in diffusion equation eigenfunctions and angular momentum tensors. McGregor has solved the problem in the same regime using a slightly more general formulation using the Redfield theory formulated in terms of the autocorrelation function of the fluctuating field seen by the spins and calculating the correlation functions using the diffusion-theory Green's function. The results of both calculations were shown to agree for a special case. In the present work, we show that the eigenfunction expansion of the Torrey equation yields the expansion of the Green's function for the diffusion equation, thus showing the identity of this approach with that of the Redfield theory. The general solution can also be obtained directly from the Torrey equation for the density matrix. Thus, the physical content of the Redfield and Torrey approaches are identical. We then introduce a more general expression for the position autocorrelation function of particles moving in a closed cell, extending the range of applicability of the theory.

  10. Reexamination of relaxation of spins due to a magnetic field gradient: Identity of the Redfield and Torrey theories

    NASA Astrophysics Data System (ADS)

    Golub, R.; Rohm, Ryan M.; Swank, C. M.

    2011-02-01

    There is an extensive literature on magnetic-gradient-induced spin relaxation. Cates, Schaefer, and Happer, in a seminal publication, have solved the problem in the regime where diffusion theory (the Torrey equation) is applicable using an expansion of the density matrix in diffusion equation eigenfunctions and angular momentum tensors. McGregor has solved the problem in the same regime using a slightly more general formulation using the Redfield theory formulated in terms of the autocorrelation function of the fluctuating field seen by the spins and calculating the correlation functions using the diffusion-theory Green’s function. The results of both calculations were shown to agree for a special case. In the present work, we show that the eigenfunction expansion of the Torrey equation yields the expansion of the Green’s function for the diffusion equation, thus showing the identity of this approach with that of the Redfield theory. The general solution can also be obtained directly from the Torrey equation for the density matrix. Thus, the physical content of the Redfield and Torrey approaches are identical. We then introduce a more general expression for the position autocorrelation function of particles moving in a closed cell, extending the range of applicability of the theory.

  11. Interferometric fiber-optic bending/nano-displacement sensor using plastic dual-core fiber

    E-print Network

    Skorobogatiy, Maksim

    Interferometric fiber-optic bending/nano-displacement sensor using plastic dual-core fiber H. Qu,1); published August 13, 2014 We demonstrate an interferometric fiber-optic bending/nano-displacement sensor accuracy of these sensors is prone to errors due to intensity fluctuations of the light source, as well

  12. Displacement sensing with hetero-core fiber specklegram

    Microsoft Academic Search

    Bo Wang; John Y. Fu; Yuexin Liu; Ruyan Guo; Francis T. S. Yu

    2004-01-01

    In this paper we report the design and implementation of a multimode fiber sensing technique for displacement sensing. To exploit the spatial information contents for sensing, a multimode fiber specklegram sensor with a hetero-core fiber structure is used. The sensor utilizes the inner product of multimode fiber speckle fields, which is highly sensitive on the geometrical shape change of the

  13. Implementation of the constant displacement scheme in random walk

    Microsoft Academic Search

    Xian-Huan Wen; Chen-Shan Kung

    1996-01-01

    The constant displacement (CD) scheme has been shown to be fast, computationally efficient and accurate for dispersion-free particle tracking in highly heterogeneous fields. In this paper, the CD scheme is extended and applied in the random walk method. Also the previously developed Q-BASIC program of particle tracking is extended to be more general for modeling contaminant transport in heterogeneous media,

  14. Optimal optical measurement of small displacements

    Microsoft Academic Search

    Magnus T. L. Hsu; Vincent Delaubert; Ping Koy Lam; Warwick P. Bowen

    2004-01-01

    We derive the quantum noise limit for the optical beam displacement of a TEM00 mode. Using a multimodal analysis, we show that the conventional split detection scheme for measuring beam displacement is non-optimal with ~80% efficiency. We propose a new displacement measurement scheme that is optimal for small beam displacement. This scheme utilizes a homodyne detection set-up that has a

  15. Optimum Small Optical Beam Displacement Measurement

    Microsoft Academic Search

    Magnus T. L. Hsu; Vincent Delaubert; Ping Koy Lam; Warwick Bowen

    2004-01-01

    We derive the quantum noise limit for the optical beam displacement of a\\u000aTEM00 mode. Using a multimodal analysis, we show that the conventional split\\u000adetection scheme for measuring beam displacement is non-optimal with 80%\\u000aefficiency. We propose a new displacement measurement scheme that is optimal\\u000afor small beam displacement. This scheme utilises a homodyne detection setup\\u000athat has a

  16. Optimal optical measurement of small displacements

    Microsoft Academic Search

    Magnus T L Hsu; Vincent Delaubert; Ping Koy Lam; Warwick P Bowen

    2004-01-01

    We derive the quantum noise limit for the optical beam displacement of a TEM00 mode. Using a multimodal analysis, we show that the conventional split detection scheme for measuring beam displacement is non-optimal with ?80% efficiency. We propose a new displacement measurement scheme that is optimal for small beam displacement. This scheme utilizes a homodyne detection set-up that has a

  17. Displacement chromatography of isomers and therapeutic compounds

    Microsoft Academic Search

    Yan Qi; Junxiong Huang

    2002-01-01

    Displacement chromatography was successfully used to separate a binary isomer mixture, epirubicin and doxorubicin, on Kromasil KR100-10 C18 250×4.6 mm I.D. (10 ?m) column. Displacement parameters such as the types and the concentrations of displacer, the composition and the flow rate of the mobile phase were critically examined in this study. The displacer employed was 30 mg\\/ml benzethonium chloride. Loading

  18. Monitoring Changes in Moisture Load Using Elastic Displacements in the Vadose Zone

    NASA Astrophysics Data System (ADS)

    Thrash, C. J.; Murdoch, L. C.; Germanovich, L. N.; Weinberg, A.

    2014-12-01

    Monitoring changes in mass over scales of several meters to hundreds of meters or more has many applications to characterization of the Critical Zone, including assessing changes in soil moisture, erosion or deposition of sediment, and melting or accumulation of snow or ice. A technique has been developed to monitor average changes in mass on those scales using continuous high-resolution measurements of displacement made with a vertical extensometer (called a DELTA extensometer). An increase of mass above the extensometer causes the soil to contract, which causes the extensometer to function similar to a weighing lysimeter. DELTA extensometers have been deployed at field sites near Clemson, South Carolina, and in northern Texas. The extensometers in South Carolina are in saprolite derived from biotite gneiss, whereas the ones in Texas are in clayey silt underlying playas. The instruments are in the vadose zone at depths of 3m to 6m. Signals from co-located extensometers are remarkably similar, demonstrating reproducibility of the technique. The extensometers respond to loading from a person or vehicle, and this load is used to estimate the Young's modulus of soil enveloping the extensometer. Displacement during small to moderate rainfalls is typically linear with the accumulated rain (~0.2 micron/mm of rain, for example). The displacement levels out during large rainfalls, potentially due to the onset of overland flow that would limit the water load during precipitation. This suggests that the onset of overland flow could be evaluated using this technique. Seasonal temperature fluctuations at the soil surface can penetrate to the depths of the extensometers causing displacement from thermal expansion and contraction. Thermal effects account for approximately 100 ?m of displacement over an annual cycle at one instrument. It appears that much of the thermal signal can be removed by data analysis. Pore pressure changes in the vicinity of the extensometer can also affect displacement and we are currently measuring pressures in an effort to identify this component of the signal. At one of the Texas sites, a series of step-like compressions totally 100 microns accompanied several rainfalls as water accumulated and filled the playa.

  19. Water Mist Suppression in Conjunction with Displacement

    E-print Network

    Hickman, Mark

    Water Mist Suppression in Conjunction with Displacement Ventilation By Benjamin Piers Hume-2758 #12;#12;Displacement Water Mist System Masters of Fire Engineering Thesis 2003 i A man of genius makes Water Mist System Masters of Fire Engineering Thesis 2003 ii #12;Displacement Water Mist System Masters

  20. Torsional stress measurement by axial displacement

    Microsoft Academic Search

    J. J. Deer

    1971-01-01

    An apparatus is described for the measurement of torque by converting angular displacement to axial displacement. A stress-responsive pulley is loosely mounted on a drive shaft by a plain bearing and a short screw-threaded section. The pulley is attached to the shaft by means of a torsion spring. In use a retarding effect upon the pulley causes angular displacement within

  1. Dynamic state of water molecular displacement of the brain during the cardiac cycle in idiopathic normal pressure hydrocephalus.

    PubMed

    Kan, Hirohito; Miyati, Tosiaki; Mase, Mitsuhito; Osawa, Tomoshi; Ohno, Naoki; Kasai, Harumasa; Arai, Nobuyuki; Kawano, Makoto; Shibamoto, Yuta

    2015-03-01

    The predictive accuracy of iNPH diagnoses could be increased using a combination of supplemental tests for iNPH. To evaluate the dynamic state of water displacement during the cardiac cycle in idiopathic normal pressure hydrocephalus (iNPH), we determined the change in water displacement using q-space analysis of diffusion magnetic resonance image. ECG-triggered single-shot diffusion echo planar imaging was used. Water displacement was obtained from the displacement probability profile calculated by Fourier transform of the signal decay fitted as a function of the reciprocal spatial vector q. Then maximum minus minimum displacement (delta-displacement), of all cardiac phase images was calculated. We assessed the delta-displacement in white matter in patients with iNPH and atrophic ventricular dilation (atrophic VD), and in healthy volunteers (control group). Delta-displacement in iNPH was significantly higher than those in the atrophic VD and control. This shows that water molecules of the white matter in iNPH are easily fluctuated by volume loading of the cranium during the cardiac cycle, due to the decrease in intracranial compliance. There was no significant correlation between delta-displacement and displacement. The delta-displacement and the displacement do not necessarily yield the same kind of information. Delta-displacement demonstrated to obtain biophysical information about fluctuation. This analysis may be helpful in the understanding physiology and pathological condition in iNPH and the assisting in the diagnosis. PMID:25614094

  2. SMA-based smart damper/displacement transducer

    NASA Astrophysics Data System (ADS)

    Mao, Chen-xi; Li, Hui

    2005-05-01

    An innovative smart shape memory alloy (SMA) -based damper/displacement transducer, which had comprehensive energy dissipation and strain self-sensing abilities (i.e. electric resistance vs. applied strain relationship) simultaneously, was proposed in this paper. This smart SMA-based damper/displacement transducer had three characteristics: 1) SMA wires in the damper/transducer were always elongated during the entire excitation; 2) SMA wires dissipated energy with re-centering ability due to pseudoelasticity; 3) SMA damper/transducer could simultaneously play the role of displacement transducer due to the strain self-sensing property of SMA wires in the damper. Such smart SMA-based damper/displacement transducer, incorporated into a building or a bridge, provided the potential to rapidly assess post-earthquake safety of structures. A large number of tests were conducted firstly, on the hysteresis stress-strain-electric resistance relationship of NiTi SMA wires (diameter 1.2mm). These tests were carried out under sinusoidal excitations with different loading frequencies at room temperature. The experimental results indicated that the pseudoelastic hysteresis loops of the SMA wires were dependent on loading frequency. In addition, the sensitivity coefficient of electric resistance vs. applied strain of the NiTi wires was identified to be 6.466 from the test results, which was independent of the loading frequency. Finally, shake table tests for a scaled 5-story steel frame, with the said smart SMA dampers/displacement transducers at the first story, subjected to various earthquake excitations, were conducted. The results of the shake table tests indicated that not only could the smart SMA damper/displacement transducers suppress structural seismic response effectively, but also it could monitor structural interstory drifts accurately.

  3. An accurate elasto-plastic frictional tangential force displacement model for granular-flow simulations: Displacement-driven formulation

    NASA Astrophysics Data System (ADS)

    Zhang, Xiang; Vu-Quoc, Loc

    2007-07-01

    We present in this paper the displacement-driven version of a tangential force-displacement (TFD) model that accounts for both elastic and plastic deformations together with interfacial friction occurring in collisions of spherical particles. This elasto-plastic frictional TFD model, with its force-driven version presented in [L. Vu-Quoc, L. Lesburg, X. Zhang. An accurate tangential force-displacement model for granular-flow simulations: contacting spheres with plastic deformation, force-driven formulation, Journal of Computational Physics 196(1) (2004) 298-326], is consistent with the elasto-plastic frictional normal force-displacement (NFD) model presented in [L. Vu-Quoc, X. Zhang. An elasto-plastic contact force-displacement model in the normal direction: displacement-driven version, Proceedings of the Royal Society of London, Series A 455 (1991) 4013-4044]. Both the NFD model and the present TFD model are based on the concept of additive decomposition of the radius of contact area into an elastic part and a plastic part. The effect of permanent indentation after impact is represented by a correction to the radius of curvature. The effect of material softening due to plastic flow is represented by a correction to the elastic moduli. The proposed TFD model is accurate, and is validated against nonlinear finite element analyses involving plastic flows in both the loading and unloading conditions. The proposed consistent displacement-driven, elasto-plastic NFD and TFD models are designed for implementation in computer codes using the discrete-element method (DEM) for granular-flow simulations. The model is shown to be accurate and is validated against nonlinear elasto-plastic finite-element analysis.

  4. Optimum Small Optical Beam Displacement Measurement

    E-print Network

    Hsu, M T L; Lam, P K; Bowen, W P; Hsu, Magnus T.L.; Delaubert, Vincent; Lam, Ping Koy; Bowen, Warwick

    2004-01-01

    We derive the quantum noise limit for the optical beam displacement of a TEM00 mode. Using a multimodal analysis, we show that the conventional split detection scheme for measuring beam displacement is non-optimal with 80% efficiency. We propose a new displacement measurement scheme that is optimal for small beam displacement. This scheme utilises a homodyne detection setup that has a TEM10 mode local oscillator. We show that although the quantum noise limit to displacement measurement can be surpassed using squeezed light in appropriate spatial modes for both schemes, the TEM10 homodyning scheme out-performs split detection for all values of squeezing.

  5. Optimum Small Optical Beam Displacement Measurement

    E-print Network

    Magnus T. L. Hsu; Vincent Delaubert; Ping Koy Lam; Warwick Bowen

    2004-07-27

    We derive the quantum noise limit for the optical beam displacement of a TEM00 mode. Using a multimodal analysis, we show that the conventional split detection scheme for measuring beam displacement is non-optimal with 80% efficiency. We propose a new displacement measurement scheme that is optimal for small beam displacement. This scheme utilises a homodyne detection setup that has a TEM10 mode local oscillator. We show that although the quantum noise limit to displacement measurement can be surpassed using squeezed light in appropriate spatial modes for both schemes, the TEM10 homodyning scheme out-performs split detection for all values of squeezing.

  6. Simultaneous detection of translational and angular displacements of micromachined elements

    SciTech Connect

    Hwu, E.-T.; Hung, S.-K.; Yang, C.-W.; Hwang, I.-S.; Huang, K.-Y. [Institute of Physics, Academia Sinica, Nankang, Taipei, Taiwan (China); Department of Mechanical Engineering, National Taiwan University, Taipei, Taiwan (China)

    2007-11-26

    An astigmatic detection system is constructed with a modified digital-versatile-disk optical head. This system, with a detecting spot of {approx}1 {mu}m, can simultaneously measure the vertical displacements and two-dimensional angular tilts of micromachined elements. It can detect thermal vibrations of microfabricated cantilevers with noise levels of 1.3 pm Hz{sup -1/2} for the linear displacement and of 3.2 nrad Hz{sup -1/2} for angular displacements over a frequency range from 1 to 800 kHz. The detecting frequency can even reach beyond 100 MHz if high-speed electronic devices are adopted. Further optimization of the system will broaden its applications in diverse technological fields.

  7. Signal processing for order 10 pm accuracy displacement metrology in real-world scientific applications

    NASA Technical Reports Server (NTRS)

    Halverson, Peter G.; Loya, Frank M.

    2004-01-01

    This paper describes heterodyne displacement metrology gauge signal processing methods that achieve satisfactory robustness against low signal strength and spurious signals, and good long-term stability. We have a proven displacement-measuring approach that is useful not only to space-optical projects at JPL, but also to the wider field of distance measurements.

  8. Reciprocating magnetic refrigerator employing tandem porous matrices within a reciprocating displacer

    NASA Technical Reports Server (NTRS)

    Johnson, D. L. (inventor)

    1985-01-01

    Disclosed is a method and apparatus for a magnetic refrigeration system. A continuously reciprocating displacer houses at least a pair of paramagnetic substances each of which is alternately driven into and out of a magnetic field. Two separate bidirectional pumping systems flow helium gas through the displacer and through both paramagnetic substances to create heat exchange conditions at two separate temperature extremes.

  9. A computer vision-based approach for structural displacement measurement

    NASA Astrophysics Data System (ADS)

    Ji, Yunfeng

    2010-04-01

    Along with the incessant advancement in optics, electronics and computer technologies during the last three decades, commercial digital video cameras have experienced a remarkable evolution, and can now be employed to measure complex motions of objects with sufficient accuracy, which render great assistance to structural displacement measurement in civil engineering. This paper proposes a computer vision-based approach for dynamic measurement of structures. One digital camera is used to capture image sequences of planar targets mounted on vibrating structures. The mathematical relationship between image plane and real space is established based on computer vision theory. Then, the structural dynamic displacement at the target locations can be quantified using point reconstruction rules. Compared with other tradition displacement measurement methods using sensors, such as accelerometers, linear-variable-differential-transducers (LVDTs) and global position system (GPS), the proposed approach gives the main advantages of great flexibility, a non-contact working mode and ease of increasing measurement points. To validate, four tests of sinusoidal motion of a point, free vibration of a cantilever beam, wind tunnel test of a cross-section bridge model, and field test of bridge displacement measurement, are performed. Results show that the proposed approach can attain excellent accuracy compared with the analytical ones or the measurements using conventional transducers, and proves to deliver an innovative and low cost solution to structural displacement measurement.

  10. Finite element modeling tests of the seven moment tensor approximation of ground displacement from tri-axial pressurized ellipsoids.

    NASA Astrophysics Data System (ADS)

    Luongo, Annamaria; Amoruso, Antonella; Crescentini, Luca

    2015-04-01

    Volcanic unrests can be studied through the induced surface deformation; one limiting factor however is the small number of available deformation source models. Till 2011, the only available (approximate or exact) expressions for finite expansion sources referred to spheres, prolate spheroids, and horizontal circular cracks embedded in a homogeneous half-space. Cervelli (2013) derived more general approximate expressions for displacement from a finite spheroid of arbitrary orientation and aspect ratio, embedded in a homogeneous half-space. The only approximate expressions for displacements and stresses from the inflation of a finite pressurized tri-axial ellipsoid in a (possibly heterogeneous) half-space were published by Amoruso and Crescentini (2011). Starting from the equivalence (exact for an infinite elastic medium) between the external displacement field due to a pressurized ellipsoidal cavity and the displacement field given by a uniform distribution of seismic moments, Amoruso and Crescentini (2011) accounted for source finiteness by using an approach similar to the multipole expansion of the gravitational potential outside a mass distribution. The dipole term is null because of symmetry; terms to quadrupole order are kept. The resulting expressions can be evaluated by combining the effects of seven moment tensors (SMT model) and are approximately valid also for a heterogeneous half-space. In case of a layered half-space, the appropriate displacement Green functions can be evaluated analitically and the SMT model has already been used to invert ground deformation data of the Campi Flegrei Caldera, Italy. In case of a heterogeneous medium, the appropriate displacement Green functions can be computed, once and for all, using FEM, so that the SMT model still allows fast forward computations and can be included into inversion codes. Amoruso and Crescentini (2011) could test the goodness of their approach only in case of spherical and prolate spheroidal cavities and horizontal circular cracks (and, later, in case of oblate spheroidal cavities) embedded in a homogenous half-space. We have used Finite Element Modeling (FEM) to extend comparisons to arbitrarily oriented tri-axial ellipsoids embedded in both a homogenous half-space and a heterogeneous one. We show that differences in ground displacement evaluated using FEM and SMT are usually small and, given measurement errors in geodetic data, negligible. Amoruso, A., Crescentini, L., Geophys. Res. Lett., 38 (1), L01303

  11. A new loss mechanism in graphene nanoresonators due to the synthetic electric fields caused by inherent out-of-plane membrane corrugations

    NASA Astrophysics Data System (ADS)

    Firsova, N. E.; Firsov, Yu A.

    2012-10-01

    For the first time the influence of out-of-plane deformations, which always exist in graphene, on the non-stationary processes is considered for the case of a monolayer graphene nanoresonator. A new loss mechanism for this device caused by dissipative intra-valley currents stipulated by synthetic electric fields is studied. These fields are generated by time-dependent gauge fields arising in a graphene membrane due to its intrinsic out-of-plane distortions and the influence of the external periodic electromotive force. The corresponding formula for the quality factor has a quantum mechanical origin and includes quantum mechanical parameters. This loss mechanism accounts for an essential part (about 40%) of losses in a graphene nanoresonator and it is specific just for graphene. The ways of minimization of this kind of dissipation (an increase in the quality factor of the electromechanical system) are discussed. It is explained why one can enhance the quality factor by correctly choosing a combination of strains (by strain engineering). In addition, it is shown that the quality factor can be increased by switching on a magnetic field perpendicular to the graphene membrane.

  12. A Theoretical Model to Predict Both Horizontal Displacement and Vertical Displacement for Electromagnetic Induction-Based Deep Displacement Sensors

    PubMed Central

    Shentu, Nanying; Zhang, Hongjian; Li, Qing; Zhou, Hongliang; Tong, Renyuan; Li, Xiong

    2012-01-01

    Deep displacement observation is one basic means of landslide dynamic study and early warning monitoring and a key part of engineering geological investigation. In our previous work, we proposed a novel electromagnetic induction-based deep displacement sensor (I-type) to predict deep horizontal displacement and a theoretical model called equation-based equivalent loop approach (EELA) to describe its sensing characters. However in many landslide and related geological engineering cases, both horizontal displacement and vertical displacement vary apparently and dynamically so both may require monitoring. In this study, a II-type deep displacement sensor is designed by revising our I-type sensor to simultaneously monitor the deep horizontal displacement and vertical displacement variations at different depths within a sliding mass. Meanwhile, a new theoretical modeling called the numerical integration-based equivalent loop approach (NIELA) has been proposed to quantitatively depict II-type sensors’ mutual inductance properties with respect to predicted horizontal displacements and vertical displacements. After detailed examinations and comparative studies between measured mutual inductance voltage, NIELA-based mutual inductance and EELA-based mutual inductance, NIELA has verified to be an effective and quite accurate analytic model for characterization of II-type sensors. The NIELA model is widely applicable for II-type sensors’ monitoring on all kinds of landslides and other related geohazards with satisfactory estimation accuracy and calculation efficiency. PMID:22368467

  13. Interferometric fiber optic displacement sensor

    DOEpatents

    Farah, J.

    1995-05-30

    A method is presented to produce a change in the optical path length in the gap between two single mode optical fibers proportional to the lateral displacement of either fiber end normal to its axis. This is done with the use of refraction or diffraction at the interface between a guiding and non-guiding media to change the direction of propagation of the light in the gap. A method is also presented for laying a waveguide on a cantilever so that the displacement of the tip of the cantilever produces a proportional path length change in the gap by distancing the waveguide from the neutral axis of the cantilever. The fiber is supported as a cantilever or a waveguide is deposited on a micromachined cantilever and incorporated in an interferometer which is made totally on a silicon substrate with the use of integrated-optic technology. A resonant element in the form of a micro-bridge is incorporated in the ridge waveguide and produces a frequency output which is readily digitizeable and immune to laser frequency noise. Finally, monolithic mechanical means for phase modulation are provided on the same sensor substrate. This is done by vibrating the cantilever or micro-bridge either electrically or optically. 29 figs.

  14. Interferometric fiber optic displacement sensor

    DOEpatents

    Farah, John (M.I.T. P.O. Box 397301, Cambridge, MA 02139)

    1999-01-01

    A method is presented to produce a change in the optical path length in the gap between two single mode optical fibers proportional to the lateral displacement of either fiber end normal to its axis. This is done with the use of refraction or diffraction at the interface between a guiding and non-guiding media to change the direction of propagation of the light in the gap. A method is also presented for laying a waveguide on a cantilever so that the displacement of the tip of the cantilever produces a proportional path length change in the gap by distancing the waveguide from the neutral axis of the cantilever. The fiber is supported as a cantilever or a waveguide is deposited on a micromachined cantilever and incorporated in an interferometer which is made totally on a silicon substrate with the use of integrated-optic technology. A resonant element in the form of a micro-bridge is incorporated in the ridge waveguide and produces a frequency output which is readily digitizeable and immune to laser frequency noise. Finally, monolithic mechanical means for phase modulation are provided on the same sensor substrate. This is done by vibrating the cantilever or micro-bridge either electrically or optically.

  15. Interferometric fiber optic displacement sensor

    DOEpatents

    Farah, J.

    1999-04-06

    A method is presented to produce a change in the optical path length in the gap between two single mode optical fibers proportional to the lateral displacement of either fiber end normal to its axis. This is done with the use of refraction or diffraction at the interface between a guiding and non-guiding media to change the direction of propagation of the light in the gap. A method is also presented for laying a waveguide on a cantilever so that the displacement of the tip of the cantilever produces a proportional path length change in the gap by distancing the waveguide from the neutral axis of the cantilever. The fiber is supported as a cantilever or a waveguide is deposited on a micromachined cantilever and incorporated in an interferometer which is made totally on a silicon substrate with the use of integrated-optic technology. A resonant element in the form of a micro-bridge is incorporated in the ridge waveguide and produces a frequency output which is readily digitizeable and immune to laser frequency noise. Finally, monolithic mechanical means for phase modulation are provided on the same sensor substrate. This is done by vibrating the cantilever or micro-bridge either electrically or optically. 23 figs.

  16. Genetics of bovine abomasal displacement.

    PubMed

    Zerbin, Ina; Lehner, Stefanie; Distl, Ottmar

    2015-04-01

    Displacement of the abomasum (DA) is a common inherited condition in Holstein cows. This article reviews the genetics of DA including risk factors, genetic parameters and molecular genetic results. Breeds other than Holsteins affected by DA include Guernseys, Jerseys, Brown Swiss, Ayrshires and Simmental-Red Holsteins. In most DA cases, left displacements of the abomasum (LDA) are seen. Lactation incidence rates are higher for DA in first lactation Holsteins compared to later lactations. For Holstein cows, heritability estimates for DA are between 0.03 and 0.53. Genetic correlation estimates among DA and milk production traits range from positive to negative. Genome-wide significant genomic regions associated with LDA are located on bovine chromosomes (BTA) 1, 3, 11, 20 and 23. Motilin-associated single nucleotide polymorphisms on BTA23 exhibit a functional relationship with LDA. Pathways for deposition of calcium, insulin-dependent diabetes mellitus and synaptic transmission are significantly related to LDA in Holsteins. Deciphering the DA-associated genomic regions and genes may be an important step in the quest to understand the underlying disease-causing mechanisms and in unravelling mutations with a causal relationship to DA. PMID:25840863

  17. Displacement Based Multilevel Structural Optimization

    NASA Technical Reports Server (NTRS)

    Sobieszezanski-Sobieski, J.; Striz, A. G.

    1996-01-01

    In the complex environment of true multidisciplinary design optimization (MDO), efficiency is one of the most desirable attributes of any approach. In the present research, a new and highly efficient methodology for the MDO subset of structural optimization is proposed and detailed, i.e., for the weight minimization of a given structure under size, strength, and displacement constraints. Specifically, finite element based multilevel optimization of structures is performed. In the system level optimization, the design variables are the coefficients of assumed polynomially based global displacement functions, and the load unbalance resulting from the solution of the global stiffness equations is minimized. In the subsystems level optimizations, the weight of each element is minimized under the action of stress constraints, with the cross sectional dimensions as design variables. The approach is expected to prove very efficient since the design task is broken down into a large number of small and efficient subtasks, each with a small number of variables, which are amenable to parallel computing.

  18. Thermal field in a water body for solar energy storage and extraction due to a buoyant two-dimensional surface water jet

    SciTech Connect

    Jaluria, Y.; O'Mara, B.T. (Rutgers Univ., New Brunswick, NJ (USA))

    1989-01-01

    An experimental study on the thermal field arising in an enclosed water body being employed for energy storage, as sensible heat, due to a horizontally discharged, heated, water jet is carried out. Two-dimensional surface discharges are considered, with an outflow located at the far end of a water body, which is simulated in the laboratory by a tank of rectangular cross section. Energy loss occurs ant the sides and at the top of the water body largely by convective transport and at the bottom by conduction to the ground. The study initially considers the transient behavior of the water body due to the input of thermal energy. A rapid transient, followed by a very gradual variation to an essentially steady-state temperature distribution, is observed. Experimental results are obtained in this steady regime for a water body of large extent, simulated by allowing a gradual outflow far from the inflow. The effects of the inflow conditions, aspect ratio, and the position of the outflow on the resulting thermal stratification are then studied in detail. Several interesting trends are observed and related to the basic mechanisms that arise in such energy storage systems. These flows are of interest in the storage and the extraction of energy, as sensible heat, in systems such as salt-gradient solar ponds. The thermal field is important in the design of such storage systems, particularly with respect to the selection of inlet conditions and the location of the outflow.

  19. Design of the FEM-FIR filter for displacement reconstruction using accelerations and displacements measured at different sampling rates

    NASA Astrophysics Data System (ADS)

    Hong, Yun Hwa; Lee, Se Gun; Lee, Hae Sung

    2013-07-01

    This paper presents a displacement reconstruction scheme using acceleration measured at a high sampling rate and displacement measured at a considerably low sampling rate. The governing equation and the boundary conditions for the reconstruction are derived using the variational statement of an inverse problem to minimize the errors between measured and reconstructed responses. The transfer function of the governing equation is identically 1 over whole frequency domain, and the proposed scheme would not result in any reconstruction error. A finite impulse response filter (FIR filter) is formulated through the finite element discretization of the governing equation. The Hermitian shape function is adopted to interpolate the displacement in a finite element. The transfer functions of the FIR filter are derived, and their characteristics are thoroughly discussed. It is recommended that the displacement sampling rate should be higher than the Nyquist rate of the target frequency, which is the lowest physically meaningful frequency in measured acceleration. In case the displacement sampling rate is lower than the recommended rate, the use of a higher target accuracy, which is the predefined accuracy at the target frequency, is required. The reconstruction of velocity with the proposed scheme is also presented. The validity of the proposed scheme is demonstrated with a numerical simulation study and a field test on a simply-supported railway bridge.

  20. Radiofrequency heating and magnetically induced displacement of dental magnetic attachments during 3.0 T MRI

    PubMed Central

    Miyata, K; Hasegawa, M; Abe, Y; Tabuchi, T; Namiki, T; Ishigami, T

    2012-01-01

    Objective The aim of this study was to estimate the risk of injury from dental magnetic attachments due to their radiofrequency (RF) heating and magnetically induced displacement during 3.0 T MRI. Methods To examine the magnetic attachments, we adopted the American Society for Testing and Materials F2182-02a and F2052-06 standards in two MRI systems (Achieva 3.0 T Nova Dual; Philips, Tokyo, Japan, and Signa HDxt 3.0 T; GE Healthcare, Milwaukee, WI). The temperature change was measured in a cylindrical keeper (GIGAUSS D600; GC, Tokyo, Japan) with coping of the casting alloy and a keeper with a dental implant at the maximum specific absorption rate (SAR) for 20 min. To measure the magnetically induced displacement force, three sizes of keepers (GIGAUSS D400, D600 and D1000) were used in deflection angle tests conducted at the point of the maximum magnetic field strength. Results Temperature elevations of both coping and implant were higher in the Signa system than in the Achieva system. The highest temperature changes in the keeper with implant and keeper with coping were 0.6 °C and 0.8 °C in the Signa system, respectively. The temperature increase did not exceed 1.0 °C at any location. The deflection angle (?) was not measurable because it exceeded 90°. GIGAUSS D400 required an extra 3.0 g load to constrain the deflection angle to less than 45°; GIGAUSS D600 and D1000 required 5.0 and 9.0 g loads, respectively. Conclusions Dental magnetic attachments pose no risk due to RF heating and magnetically induced displacement at 3.0 T MRI. However, it is necessary to confirm that these keepers are securely attached to the prosthesis before imaging. PMID:22499128

  1. Polybenzimidazoles Via Aromatic Nucleophilic Displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Hergerrother, Paul M. (Inventor); Smith, Joseph G., Jr. (Inventor)

    1997-01-01

    Novel molecular weight controlled and endcapped polybenzimidazoles (PBI) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenylbenzimidazole) monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The PBI are endcapped with mono(hydroxyphenyl)benzimidazoles. The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. Mono(hydroxyphenyl)benzimidazoles are synthesized by reacting phenyl-4-hydroxybenzoate with aromatic (o-diamine)s in diphenylsulfone. Molecular weight controlled and endcapped PBI of new chemical structures are prepared that exhibit a favorable combination of physical and mechanical properties.

  2. Displaceable Gear Torque Controlled Driver

    NASA Technical Reports Server (NTRS)

    Cook, Joseph S., Jr. (Inventor)

    1997-01-01

    Methods and apparatus are provided for a torque driver including a displaceable gear to limit torque transfer to a fastener at a precisely controlled torque limit. A biasing assembly biases a first gear into engagement with a second gear for torque transfer between the first and second gear. The biasing assembly includes a pressurized cylinder controlled at a constant pressure that corresponds to a torque limit. A calibrated gage and valve is used to set the desired torque limit. One or more coiled output linkages connect the first gear with the fastener adaptor which may be a socket for a nut. A gear tooth profile provides a separation force that overcomes the bias to limit torque at the desired torque limit. Multiple fasteners may be rotated simultaneously to a desired torque limit if additional output spur gears are provided. The torque limit is adjustable and may be different for fasteners within the same fastener configuration.

  3. Fiber optic multimode displacement sensor

    NASA Astrophysics Data System (ADS)

    Fisher, Karl A.; Jarzynski, Jacek

    1996-04-01

    An underwater Optical Motion Sensor (OMS) based on a design first presented by W. B. Spillman, Schlieren multimode fiber-optic hydrophone, Applied Physics Letters 37(2), 15 July 1980, p. 145-146 is described. The displacement sensor uses the same acoustooptical intensity modulation mechanism as Spillman, however the sensing mechanism is isolated from the ambient fluid environment by a small cylindrical aluminum enclosure (1? OD×3/4?). The enclosure contains an inertial mass and the fiber collimators. The inertial mass is suspended in the center of the enclosure by three small wires rigidly mounted to the walls. The mass and wires act as a cantilever beam system with a mechanical resonance near 100 Hz. The transduction mechanism consists of two opposed optical gratings aligned and positioned between the fiber collimators. One grating is mounted on the inertial mass while the other is mounted on the lower end cap of the enclosure. Relative motion between the gratings causes a modulation of the light transmitted through the gratings. The modulated beam is focused onto a photodetector and converted to electric current. The frequency response is flat from 200 Hz-9 kHz with a minimum detectable displacement of 0.002 A and the dynamic range is 136 dB. The small size and light weight give the sensor an effective density of 1.08 g/cm3 making it almost neutrally buoyant in water. This in conjunction with the performance characteristics make this sensor suitable for use in acoustical sensing applications.

  4. Displacement of crude oil by carbon dioxide 

    E-print Network

    Omole, Olusegun

    1980-01-01

    DISPLACEMENT OF CRUDE OIL BY CARBON DIOXIDE A Thesis by OLUSEGUN OMOLE Submitted to the Graduate College of Texas ASM University in part';al fulfillment of the requirement for the degree of MASTER OF SCIENCE December 1980 Major Subject...: Petroleum Engineering DISPLACEMENT OF CRUDE OIL BY CARBON DIOXIDE A Thesis by OLUSEGUN OMOLE Approved as to style and content by: hairman of Committee / (Member (Member (Member (Hea o Depart ent December 1980 ABSTRACT Displacement of Crude Oil...

  5. Quantum analysis of a linear DC SQUID mechanical displacement detector

    E-print Network

    M. P. Blencowe; E. Buks

    2007-07-19

    We provide a quantum analysis of a DC SQUID mechanical displacement detector within the sub-critical Josephson current regime. A segment of the SQUID loop forms the mechanical resonator and motion of the latter is transduced inductively through changes in the flux threading the loop. Expressions are derived for the detector signal response and noise, which are used to evaluate the position and force detection sensitivity. We also investigate cooling of the mechanical resonator due to back reaction noise from the detector.

  6. Motion of the Esophagus Due to Cardiac Motion

    PubMed Central

    Palmer, Jacob; Yang, Jinzhong; Pan, Tinsu; Court, Laurence E.

    2014-01-01

    When imaging studies (e.g. CT) are used to quantify morphological changes in an anatomical structure, it is necessary to understand the extent and source of motion which can give imaging artifacts (e.g. blurring or local distortion). The objective of this study was to assess the magnitude of esophageal motion due to cardiac motion. We used retrospective electrocardiogram-gated contrast-enhanced computed tomography angiography images for this study. The anatomic region from the carina to the bottom of the heart was taken at deep-inspiration breath hold with the patients' arms raised above their shoulders, in a position similar to that used for radiation therapy. The esophagus was delineated on the diastolic phase of cardiac motion, and deformable registration was used to sequentially deform the images in nearest-neighbor phases among the 10 cardiac phases, starting from the diastolic phase. Using the 10 deformation fields generated from the deformable registration, the magnitude of the extreme displacements was then calculated for each voxel, and the mean and maximum displacement was calculated for each computed tomography slice for each patient. The average maximum esophageal displacement due to cardiac motion for all patients was 5.8 mm (standard deviation: 1.6 mm, maximum: 10.0 mm) in the transverse direction. For 21 of 26 patients, the largest esophageal motion was found in the inferior region of the heart; for the other patients, esophageal motion was approximately independent of superior-inferior position. The esophagus motion was larger at cardiac phases where the electrocardiogram R-wave occurs. In conclusion, the magnitude of esophageal motion near the heart due to cardiac motion is similar to that due to other sources of motion, including respiratory motion and intra-fraction motion. A larger cardiac motion will result into larger esophagus motion in a cardiac cycle. PMID:24586540

  7. Displacement current phenomena in the magnetically insulated transmission lines of the refurbished Z accelerator

    NASA Astrophysics Data System (ADS)

    McBride, R. D.; Jennings, C. A.; Vesey, R. A.; Rochau, G. A.; Savage, M. E.; Stygar, W. A.; Cuneo, M. E.; Sinars, D. B.; Jones, M.; Lechien, K. R.; Lopez, M. R.; Moore, J. K.; Struve, K. W.; Wagoner, T. C.; Waisman, E. M.

    2010-12-01

    Experimental data is presented that illustrates important displacement current phenomena in the magnetically insulated transmission lines (MITLs) of the refurbished Z accelerator [D. V. Rose , Phys. Rev. ST Accel. Beams 13, 010402 (2010)PRABFM1098-440210.1103/PhysRevSTAB.13.010402]. Specifically, we show how displacement current in the MITLs causes significant differences between the accelerator current measured at the vacuum-insulator stack (at a radial position of about 1.6 m from the Z axis of symmetry) and the accelerator current measured at the load (at a radial position of about 6 cm from the Z axis of symmetry). The importance of accounting for these differences was first emphasized by Jennings et al. [C. A. Jennings , IEEE Trans. Plasma Sci. 38, 529 (2010)ITPSBD0093-381310.1109/TPS.2010.2042971], who calculated them using a full transmission-line-equivalent model of the four-level MITL system. However, in the data presented by Jennings et al., many of the interesting displacement current phenomena were obscured by parasitic current losses that occurred between the vacuum-insulator stack and the load (e.g., electron flow across the anode-cathode gap). By contrast, the data presented herein contain very little parasitic current loss, and thus for these low-loss experiments we are able to demonstrate that the differences between the current measured at the stack and the current measured at the load are due primarily to the displacement current that results from the shunt capacitance of the MITLs (about 8.41 nF total). Demonstrating this is important because displacement current is an energy storage mechanism, where energy is stored in the MITL electric fields and can later be used by the system. Thus, even for higher-loss experiments, the differences between the current measured at the stack and the current measured at the load are often largely due to energy storage and subsequent release, as opposed to being due solely to some combination of measurement error and current loss in the MITLs and/or double post-hole convolute. Displacement current also explains why the current measured downstream of the MITLs (i.e., the load current) often exceeds the current measured upstream of the MITLs (i.e., the stack current) at various times in the power pulse (this particular phenomenon was initially thought to be due to timing and/or calibration errors). To facilitate a better understanding of these phenomena, we also introduce and analyze a simple LC circuit model of the MITLs. This model is easily implemented as a simple drive circuit in simulation codes, which has now been done for the LASNEX code [G. B. Zimmerman and W. L. Kruer, Comments Plasma Phys. Controlled Fusion 2, 51 (1975)CPCFBJ0374-2806] at Sandia, as well as for simpler MATLAB®-based codes at Sandia. An example of this LC model used as a drive circuit will also be presented.

  8. Microbial Adhesion in Flow Displacement Systems

    PubMed Central

    Busscher, Henk J.; van der Mei, Henny C.

    2006-01-01

    Flow displacement systems are superior to many other (static) systems for studying microbial adhesion to surfaces because mass transport and prevailing shear conditions can be adequately controlled and notoriously ill-defined slight rinsing steps to remove so-called “loosely adhering organisms” can be avoided. In this review, we present the basic background required to calculate mass transport and shear rates in flow displacement systems, focusing on the parallel plate flow chamber as an example. Critical features in the design of flow displacement systems are discussed, as well as different strategies for data analysis. Finally, selected examples of working with flow displacement systems are given for diverse biomedical applications. PMID:16418527

  9. Fiber-optic displacement sensors on the Hunters Trophy UGT impulse gauge experiments

    SciTech Connect

    Green, R.E.L.; Poutiatine, A.I.

    1995-03-01

    As part of a program to develop gauges for measurement of various mechanical properties in hostile environments, the authors fielded purely optical displacement sensors at the ends of long fiber-optic cables as supplements to the regular displacement sensors of four impulse gauges fielded as part of a materials study on the Hunters Trophy underground effects test at the Nevada Test Site. These fiber-optic sensor systems and their performance on the Hunters Trophy test are described in this report.

  10. Horizontal displacement profiles in N Reactor horizontal control rod channels

    SciTech Connect

    Woodruff, E.M.

    1988-12-01

    One of the potential results from N Reactor graphite moderator distortion is horizontal curvature of the horizontal control rod (HCR) channels. Mockup testing has identified two possible problem scenarios resulting from such curvature: slow scram times and rod abrasion due to rubbing of the rod on the side of the channel and subsequent displacement of T-blocks that form the sides of the channels. As a result of these potential events, surveillance tools (instrumentation) to measure HCR channel horizontal displacement was recently developed. Surveillance of HCR channel 65, performed on December 11, 1987, indicated a six inch rearward displacement near the center of the channel. This approximated the displacement which mockup testing has identified as a concern with regard to T-block movement. Closed Circuit Television (CCTV) observations indicate that T-block movement has not occurred in HCR channel 65, but that there has been some rubbing of the rod on the channel sides. Review of most recent rod hot scram times indicates normal performance for HCR 65. To further evaluate this concern, horizontal deflection and CCTV surveillance was scheduled in six HCR channels surrounding HCR channel 65. Inspection of the HCR rod tip was also performed. 13 refs., 6 figs.

  11. Effects of Fault Displacement on Emplacement Drifts

    SciTech Connect

    F. Duan

    2000-04-25

    The purpose of this analysis is to evaluate potential effects of fault displacement on emplacement drifts, including drip shields and waste packages emplaced in emplacement drifts. The output from this analysis not only provides data for the evaluation of long-term drift stability but also supports the Engineered Barrier System (EBS) process model report (PMR) and Disruptive Events Report currently under development. The primary scope of this analysis includes (1) examining fault displacement effects in terms of induced stresses and displacements in the rock mass surrounding an emplacement drift and (2 ) predicting fault displacement effects on the drip shield and waste package. The magnitude of the fault displacement analyzed in this analysis bounds the mean fault displacement corresponding to an annual frequency of exceedance of 10{sup -5} adopted for the preclosure period of the repository and also supports the postclosure performance assessment. This analysis is performed following the development plan prepared for analyzing effects of fault displacement on emplacement drifts (CRWMS M&O 2000). The analysis will begin with the identification and preparation of requirements, criteria, and inputs. A literature survey on accommodating fault displacements encountered in underground structures such as buried oil and gas pipelines will be conducted. For a given fault displacement, the least favorable scenario in term of the spatial relation of a fault to an emplacement drift is chosen, and the analysis is then performed analytically. Based on the analysis results, conclusions are made regarding the effects and consequences of fault displacement on emplacement drifts. Specifically, the analysis will discuss loads which can be induced by fault displacement on emplacement drifts, drip shield and/or waste packages during the time period of postclosure.

  12. Displacement based multilevel structural optimization

    NASA Technical Reports Server (NTRS)

    Striz, Alfred G.

    1995-01-01

    Multidisciplinary design optimization (MDO) is expected to play a major role in the competitive transportation industries of tomorrow, i.e., in the design of aircraft and spacecraft, of high speed trains, boats, and automobiles. All of these vehicles require maximum performance at minimum weight to keep fuel consumption low and conserve resources. Here, MDO can deliver mathematically based design tools to create systems with optimum performance subject to the constraints of disciplines such as structures, aerodynamics, controls, etc. Although some applications of MDO are beginning to surface, the key to a widespread use of this technology lies in the improvement of its efficiency. This aspect is investigated here for the MDO subset of structural optimization, i.e., for the weight minimization of a given structure under size, strength, and displacement constraints. Specifically, finite element based multilevel optimization of structures (here, statically indeterminate trusses and beams for proof of concept) is performed. In the system level optimization, the design variables are the coefficients of assumed displacement functions, and the load unbalance resulting from the solution of the stiffness equations is minimized. Constraints are placed on the deflection amplitudes and the weight of the structure. In the subsystems level optimizations, the weight of each element is minimized under the action of stress constraints, with the cross sectional dimensions as design variables. This approach is expected to prove very efficient, especially for complex structures, since the design task is broken down into a large number of small and efficiently handled subtasks, each with only a small number of variables. This partitioning will also allow for the use of parallel computing, first, by sending the system and subsystems level computations to two different processors, ultimately, by performing all subsystems level optimizations in a massively parallel manner on separate processors. It is expected that the subsystems level optimizations can be further improved through the use of controlled growth, a method which reduces an optimization to a more efficient analysis with only a slight degradation in accuracy. The efficiency of all proposed techniques is being evaluated relative to the performance of the standard single level optimization approach where the complete structure is weight minimized under the action of all given constraints by one processor and to the performance of simultaneous analysis and design which combines analysis and optimization into a single step. It is expected that the present approach can be expanded to include additional structural constraints (buckling, free and forced vibration, etc.) or other disciplines (passive and active controls, aerodynamics, etc.) for true MDO.

  13. Radiation damage due to electromagnetic showers

    SciTech Connect

    Rakhno, Igor; Mokhov, Nikolai; Striganov, Sergei; /Fermilab

    2008-05-01

    Radiation-induced damage due to atomic displacements is essential to correctly predict the behavior of materials in nuclear reactors and at charged-particle accelerators. Traditionally the damage due to hadrons was of major interest. The recent increased interest in high-energy lepton colliders gave rise to the problem of prediction of radiation damage due to electromagnetic showers in a wide energy range--from a few hundred keV and up to a few hundred GeV. The report describes results of an electron- and positron-induced displacement cross section evaluation. It is based on detailed lepton-nucleus cross sections, realistic nuclear form-factors and a modified Kinchin-Pease damage model. Numerical data on displacement cross sections for various target nuclei is presented.

  14. Antibiotics as low-molecular-mass displacers in ion-exchange displacement chromatography

    Microsoft Academic Search

    Amitava Kundu; Suresh Vunnum; Steven M. Cramer

    1995-01-01

    While the ability to carry out simultaneous concentration and purification in a single displacement step has significant advantages for downstream processing of pharmaceuticals, a major impediment to the implementtion of displacement chromatography has been the lack of suitable displacer compounds. An important recent advance in the state-of-the-art of displacement chromatography has been the discovery that low-molecular-mass dendritic polymers and protected

  15. Tracking of transient displacements of plates with support excitations

    NASA Astrophysics Data System (ADS)

    Krommer, Michael; Nader, Manfred; Irschik, Hans

    2007-04-01

    The present paper is concerned with dynamic shape control of linear elastic plates under the action of transient forces, with prescribed time-dependent boundary conditions, and with given initial conditions. We consider anisotropic linear elastic plates. The following displacement tracking problem is treated: We ask for an additional distribution of actuation stresses such that the resulting displacements of the plates under consideration follow exactly some desired trajectories in every point and at every time instant. We present relations that must be satisfied for the actuation stresses in order that this goal of transient displacement tracking is reached. The actuation stresses we have in mind for enforcing tracking of transient displacements are induced by eigenstrains, such as thermal expansion strains or, more technologically important, piezoelectric parts of strain. Transient vibrations of circular plates in axi-symmetric bending are studied as an exemplary case. The vibrations are excited by support excitations. Actuation stresses are superimposed, which enforce the plate to track prescribed transient deflections. We present analytical solutions for the tracking of prescribed plate deflections with time-dependent support excitation. Coupling between electric and mechanical field is taken into account already at the level of plate theory. The analytical plate solutions are validated by Finite Element computations. Electromechanically coupled three-dimensional piezoelectric elements are used in these numerical calculations. Excellent coincidence between the analytical and the Finite Element computations is observed.

  16. Using a 2D displacement sensor to derive 3D displacement information

    NASA Technical Reports Server (NTRS)

    Soares, Schubert F. (Inventor)

    2002-01-01

    A 2D displacement sensor is used to measure displacement in three dimensions. For example, the sensor can be used in conjunction with a pulse-modulated or frequency-modulated laser beam to measure displacement caused by deformation of an antenna on which the sensor is mounted.

  17. Evaluation of two-phase relative permeability and capillary pressure relations for unstable displacements in a pore network

    SciTech Connect

    Dehoff, Karl J.; Oostrom, Martinus; Zhang, Changyong; Grate, Jay W.

    2012-10-29

    A series of displacement experiments was conducted using five wetting-nonwetting immiscible fluid pairs in a homogenous and uniform pore network. The micromodel was initially saturated with either polyethylene glycol 200 (PEG) or water as a wetting fluid, which was subsequently displaced by a nonwetting fluid (dodecane, hexadecane, or mineral oil) at different flow rates. The experiments were designed to allow determinations of nonwetting fluid relative permeabilities ( ), fluid saturations ( ), and capillary pressure heads ( ). In the displacements, nonwetting fluid saturations increased with increasing flow rates for all five fluid pairs, and viscous fingering, capillary fingering, and stable displacement were observed. Viscous fingering occurred when PEG was displaced by either dodecane or hexadecane. For the water displacements, capillary fingers were observed at low capillary numbers. Due to unstable fingering phenomena, values for the PEG displacements were smaller than for the water displacements. A fitting exercise using the Brooks-Corey (1964) relationship showed that the fitted entry pressure heads are reasonably close to the computed entry pressure head. The fitted pore geometry factor, ?? values for the displacements are considerably lower than what is expected for displacements in homogeneous, highly uniform, porous systems, demonstrating the impact of unstable displacement on the apparent value of ?. It was shown that a continuum-based multiphase model could be used to predict the average behavior for wetting fluid drainage in a pore network as long as independently fitted - and - relations are used. The use of a coupled approach through the Brooks-Corey pore geometry factor underpredicts observed values.

  18. Video Games, Adolescents, and the Displacement Effect

    ERIC Educational Resources Information Center

    Fisher, Carla Christine

    2012-01-01

    The displacement effect (the idea that time spent in one activity displaces time spent in other activities) was examined within the lens of adolescents' video game use and their time spent reading, doing homework, in physically active sports and activities, in creative play, and with parents and friends. Data were drawn from the Panel Study…

  19. Young Children's Understanding of Displaced Aggression.

    ERIC Educational Resources Information Center

    Weiss, Michael G.; Miller, Patricia H.

    1983-01-01

    Examines early phases of understanding of causes of moderately and extremely displaced aggression. Preschool and kindergarten children three to five years of age viewed eight videotaped episodes of displaced aggression. Comprehension was assessed by means of open-ended questions and forced-choice picture selections. (Author/RH)

  20. Displaced Homemakers: Vo-Tech Workshop Guide.

    ERIC Educational Resources Information Center

    Peltier, Wanda Jo

    Written for displaced homemaker programs in vocational-technical schools, this curriculum contains material designed so that instructors can prepare student manuals appropriate to almost any educational support situation for displaced homemakers. An overview provides information on special needs groups, curriculum use, and resources and sample…

  1. Viscoelastic effects on free surface displacement flows: a computational and experimental study

    NASA Astrophysics Data System (ADS)

    Lee, Alex; Shaqfeh, Eric; Khomami, Bamin

    2001-11-01

    A Newton-Raphson pseudo-solid domain mapping technique coupled with DEVSS/ DEVSS-G finite element formulation is applied to study the effects of viscoelasticity on free surface flows. Two distinct flow types are analyzed: the flow induced by a long bubble steadily displacing a polymeric liquid confined by two parallel plates and the slot coating of viscoelastic fluids in the low metering rate limit. The Oldroyd-B, FENE-CR, and FENE-P constitutive equations are used to model the viscoelastic fluid. Our study reveals the formation of an elastic boundary layer in the capillary transition region of the bubble front at moderate Weissenberg numbers while the pressure and stress field in the parallel flow region remains largely unaffected for both flows. The increase in the hydrodynamic coating thickness due to viscoelasticity often reported in planar injection experiments appears to be associated with the onset of these elastic boundary layers.

  2. Lattice Boltzmann simulations of supercritical CO2-water drainage displacement in porous media: CO2 saturation and displacement mechanism.

    PubMed

    Yamabe, Hirotatsu; Tsuji, Takeshi; Liang, Yunfeng; Matsuoka, Toshifumi

    2015-01-01

    CO2 geosequestration in deep aquifers requires the displacement of water (wetting phase) from the porous media by supercritical CO2 (nonwetting phase). However, the interfacial instabilities, such as viscous and capillary fingerings, develop during the drainage displacement. Moreover, the burstlike Haines jump often occurs under conditions of low capillary number. To study these interfacial instabilities, we performed lattice Boltzmann simulations of CO2-water drainage displacement in a 3D synthetic granular rock model at a fixed viscosity ratio and at various capillary numbers. The capillary numbers are varied by changing injection pressure, which induces changes in flow velocity. It was observed that the viscous fingering was dominant at high injection pressures, whereas the crossover of viscous and capillary fingerings was observed, accompanied by Haines jumps, at low injection pressures. The Haines jumps flowing forward caused a significant drop of CO2 saturation, whereas Haines jumps flowing backward caused an increase of CO2 saturation (per injection depth). We demonstrated that the pore-scale Haines jumps remarkably influenced the flow path and therefore equilibrium CO2 saturation in crossover domain, which is in turn related to the storage efficiency in the field-scale geosequestration. The results can improve our understandings of the storage efficiency by the effects of pore-scale displacement phenomena. PMID:25427299

  3. Two-dimensional simulations of displacement accumulation incorporating shear strain

    PubMed Central

    Bayer, Matthew; Hall, Timothy J.; Neves, Lucio P.; Carneiro, A. A. O.

    2015-01-01

    Using ultrasound images to track large tissue deformations usually requires breaking up the deformation into steps and then summing the resulting displacement estimates. The accumulated displacement estimation error therefore depends on the error in each step, but also on the statistical relationships between estimation steps. These relationships have not been thoroughly studied. Building on previous work with one-dimensional simulations, the work reported here measured error variance for single-step and accumulated displacement estimates using two-dimensional numerical simulations of ultrasound echo signals, subjected to both normal and axial shear strain as well as electronic noise. Previous results were confirmed, showing that errors due to electronic noise are negatively correlated between steps and accumulate slowly, while errors due to strain are positively correlated and accumulate quickly. These properties hold for both normal and axial shear strain. A general comparison of tracking performance for tissue under normal and axial shear strain was also performed. Under axial shear strain error variance tends to increase with larger lateral kernel sizes but decrease for larger axial kernel sizes; the opposite relationship holds under normal strain. A combination of these two types of strain limits the practical kernel size in both dimensions. PMID:24275539

  4. Wireless displacement sensing system for bridges using multi-sensor fusion

    NASA Astrophysics Data System (ADS)

    Park, Jong-Woong; Sim, Sung-Han; Jung, Hyung-Jo

    2014-04-01

    Accurate displacement sensing or estimation is an important task for reliably assessing the condition of civil infrastructure such as bridges and buildings, because the structural displacement describes the behavior of a structure and indicates structural safety according to the design limit. However, it is difficult to directly measure the displacement of a bridge structure due to the inaccessibility of a reference point especially when bridges are built over a highway, a river or the sea. As an alternative, an indirect displacement estimation using two different types of measurements such as strain and acceleration (i.e., multimetric data) has been developed. While the approach has been seen as promising, the combination of the traditional sensing system based on wired sensors and the multimetric data-based algorithm is inappropriate or impractical in real-world applications of the approach. This paper proposes a new displacement sensing system by incorporating wireless sensor technology with the multimetric data-based algorithm, which can address the difficulties and issues found in the traditional sensing system to realize a practical means of measuring displacement in full-scale bridges. The proposed wireless displacement sensing system enables (a) time-synchronized acceleration and strain measurement, (b) high-precision strain sensing and (c) improved applicability due to the wireless communication as well as the previous two features. The effectiveness of the proposed system is experimentally verified in laboratory and full-scale experiments.

  5. Medium - long term earthquake prediction by the use of the oscillating electric field (T = 365 days) generated due to Earth's orbit around the Sun and due to its consequent oscillating lithospheric deformation

    E-print Network

    Thanassoulas, C; Tsailas, P; Verveniotis, G; Zymaris, N

    2009-01-01

    We study the Earth's electric field monitored at PYR (Greece) monitoring site, for a period of more than six years (May 23rd, 2003 to September 7th, 2009). It is compared, in particular its oscillating component of T = 365 days, with the Perihelion - Aphelion dates of the Earth's orbit around the Sun, with the same component of the Earth's magnetic field, with the corresponding same period tidal oscillation and with the occurred large EQs of the same period of time. The obtained results suggest that the oscillating electric field component is generated by large scale piezoelectricity triggered by the Earth's shape - lithospheric oscillating deformation. The driving mechanism (yearly tidal variation) precedes the Aphelion - Perihelion dates for a month complying with the corresponding tidal friction behavior of the Earth's shape deformation. The Earth's oscillating electric field peaks coincide with the Perihelion - Aphelion dates while the triggered large EQs are clustered very close to the Perihelion - Aphel...

  6. Is the Long-Term Persistency of Circular Polarisation due to the Constant Helicity of the Magnetic Fields in Rotating Quasar Engines?

    NASA Astrophysics Data System (ADS)

    Enß, T. A.

    2003-03-01

    Many compact radio sources like quasars, blazars, radio galaxies, and micro-quasars emit circular polarisation (CP) with surprising temporal persistent handedness. We propose that the CP is caused by Faraday conversion (FC) of linear polarisation (LP) synchrotron light which propagates along a line-of-sight (LOS) through helical magnetic fields. Jet outflows from radio galaxies should have the required magnetic helicity in the emission region due to the magnetic torque of the accretion disc. Also advection dominated accretion flow (ADAF) should contain magnetic fields with the same helicity. However, a jet region seems to be the more plausible origin of CP. The proposed scenario requires Faraday rotation (FR) to be insignificant in the emission region. The proposed mechanism works in electron-positron (e+/-) as well as electron-proton (e/p) plasma. In the latter case, the emission region should consist of individual flux tubes with independent polarities in order to suppress too strong FR - as it was already proposed for FR based CP generation models. The predominant CP is expected to mostly counter-rotate (rotation is measured here in sky-projection) with respect to the central engine in all cases (jet or ADAF, e+/- or e/p plasma) and therefore allows to measure the sense of rotation of quasar engines. The engine of SgrA* is expected - in this scenario - to rotate clockwise and therefore counter-Galactic, as do the young hot stars in its vicinity, which are thought to feed SgrA* by their winds. Generally, sources with Stokes-V<0 (V>0) are expected to rotate clockwise (counter-clockwise).

  7. Study of microdosimetric energy deposition patterns in tissue-equivalent medium due to low-energy neutron fields using a graphite-walled proportional counter.

    PubMed

    Waker, A J; Aslam

    2011-06-01

    To improve radiation protection dosimetry for low-energy neutron fields encountered in nuclear power reactor environments, there is increasing interest in modeling neutron energy deposition in metrological instruments such as tissue-equivalent proportional counters (TEPCs). Along with these computational developments, there is also a need for experimental data with which to benchmark and test the results obtained from the modeling methods developed. The experimental work described in this paper is a study of the energy deposition in tissue-equivalent (TE) medium using an in-house built graphite-walled proportional counter (GPC) filled with TE gas. The GPC is a simple model of a standard TEPC because the response of the counter at these energies is almost entirely due to the neutron interactions in the sensitive volume of the counter. Energy deposition in tissue spheres of diameter 1, 2, 4 and 8 µm was measured in low-energy neutron fields below 500 keV. We have observed a continuously increasing trend in microdosimetric averages with an increase in neutron energy. The values of these averages decrease as we increase the simulated diameter at a given neutron energy. A similar trend for these microdosimetric averages has been observed for standard TEPCs and the Rossi-type, TE, spherical wall-less counter filled with propane-based TE gas in the same energy range. This implies that at the microdosimetric level, in the neutron energy range we employed in this study, the pattern of average energy deposited by starter and insider proton recoil events in the gas is similar to those generated cumulatively by crosser and stopper events originating from the counter wall plus starter and insider recoil events originating in the sensitive volume of a TEPC. PMID:21476858

  8. Molecular Dynamics Simulations of Displacement Cascades in Single and Polycrystalline Zirconia

    SciTech Connect

    Du Jincheng [Department of Materials Science and Engineering, Center for Advanced Scientific Computing and Modeling, University of North Texas (United States)

    2009-03-10

    Displacement cascades in zirconia have been studied using classical molecular dynamics simulations. Polycrystalline zirconia with nano-meter grains were created using Voronoi polyhedra construction and studied in comparison with single crystalline zirconia. The results show that displacement cascades with similar kinetic energy generated larger number of displaced atoms in polycrystalline than in the single crystal structure. The fraction of atoms with coordination number change was also higher in polycrystalline zirconia that was explained to be due to the diffusion of oxygen and relaxation at grain boundaries.

  9. Voltage-dependent Membrane Displacements Measured by Atomic Force Microscopy

    PubMed Central

    Mosbacher, J.; Langer, M.; Hörber, J.K.H.; Sachs, F.

    1998-01-01

    Cells use polar molecules in the membrane to sense changes in the transmembrane potential. The opening of voltage-gated ion channels and membrane bending due to the inverse flexoelectric effect are two examples of such electromechanical coupling. We have looked for membrane motions in an electric field using atomic (or scanning) force microscopy (AFM) with the intent of studying voltage-dependent conformational changes of ion channels. Voltage-clamped HEK293 cells were either untransfected controls or transfected with Shaker K+ channels. Using a ± 10-mV peak–peak AC carrier stimulus, untransfected cells moved 0.5–15 nm normal to the plane of the membrane. These movements tracked the voltage at frequencies >1 kHz with a phase lead of 60–120°, as expected of a displacement current. The movement was outward with depolarization, but the holding potential only weakly influenced the amplitude of the movement. In contrast, cells transfected with a noninactivating mutant of Shaker K+channels showed similar movements, but these were sensitive to the holding potential; decreasing with depolarization between ?80 and 0 mV. Searching for artifactual origins of these movements, we used open or sealed pipettes and AFM cantilever placements just above the cells. These results were negative, suggesting that the observed movements were produced by the cell membrane rather than by movement of the patch pipette, or by acoustic or electrical interactions of the membrane with the AFM tip. In control cells, the electrical motor may arise from the flexoelectric effect, where changes in potential induce changes in curvature. In transfected cells, it appears that channel-specific movements also occurred. These experiments demonstrate that the AFM may be able to exploit voltage-dependent movements as a source of contrast for imaging membrane components. The electrically induced motility will cause twitching during action potentials, and may have physiological consequences. PMID:9417135

  10. Probing baryogenesis with displaced vertices at the LHC

    NASA Astrophysics Data System (ADS)

    Cui, Yanou; Shuve, Brian

    2015-02-01

    The generation of the asymmetric cosmic baryon abundance requires a departure from thermal equilibrium in the early universe. In a large class of baryogenesis models, the baryon asymmetry results from the out-of-equilibrium decay of a new, massive particle. We highlight that in the interesting scenario where this particle has a weak scale mass, this out-of-equilibrium condition requires a proper decay length larger than O(1) mm. Such new fields are within reach of the LHC, at which they can be pair produced leaving a distinctive, displaced-vertex signature. This scenario is realized in the recently proposed mechanism of baryogenesis where the baryon asymmetry is produced through the freeze-out and subsequent decay of a meta-stable weakly interacting massive particle ("WIMP baryogenesis"). In analogy to missing energy searches for WIMP dark matter, the LHC is an excellent probe of these new long-lived particles responsible for baryogenesis via the low-background displaced vertex channel. In our paper, we estimate the limits on simplified models inspired by WIMP baryogenesis from two of the most sensitive collider searches by CMS and ATLAS with 8 TeV LHC data. We also estimate the LHC reach at 13 TeV using current strategies, and demonstrate that up to a factor of 100 improvement in cross-section limits can be achieved by requiring two displaced vertices while lowering kinematic thresholds. For meta-stable WIMPs produced through electroweak interactions, the high luminosity LHC is sensitive to masses up to 2.5 TeV for lifetimes around 1 cm, while for singlets pair-produced through the off-shell-Higgs portal, the LHC is sensitive to production cross sections of O(10) ab for benchmark masses around 150 GeV. Our analysis and proposals also generally apply to displaced vertex signatures from other new physics such as hidden valley models, twin Higgs models and displaced supersymmetry.

  11. Feasibility study on ultrasonic lateral displacement measurement for structural health monitoring

    NASA Astrophysics Data System (ADS)

    Matsuya, Iwao; Matsumoto, Fumiya; Ihara, Ikuo

    2014-02-01

    In structural health monitoring, measuring the relative lateral displacement of the structure is essential for direct damage detection. Although large numbers of studies have been made on the development of the range finder utilizing an optical sensor, little attention has been given to the measuring method for lateral displacement. We propose a novel measurement method for directly measuring the lateral displacement of the structures by means of the air-coupled ultrasound. The measurement system is composed of two flat-type air-coupled ultrasound transducers and a steel wire as a target. The ultrasound transducers are immobilized on a fixed point, whereas a steel wire is separately arranged on the opposite side. When the steel wire is displaced laterally to the ultrasound detectors, the lateral displacement is calculated by taking advantage of the intensity ratio of the reflected ultrasound waves. The accuracy of the lateral displacement measurement is experimentally assessed by conducting a laboratory test. The estimated displacement value in the far field region of the transducer agrees well with the reference. The result shows that the developed displacement measurement method will be useful for the health diagnosis of structures.

  12. Gage for measuring displacements in rock samples

    DOEpatents

    Holcomb, David J. (Albuquerque, NM); McNamee, Michael J. (Albuquerque, NM)

    1986-01-01

    A gage for measuring diametral displacement within a rock sample for use in a rock mechanics laboratory and in the field, comprises a support ring housing a linear variable differential transformer, a mounting screw, and a leaf spring. The mounting screw is adjustable and defines a first point of contact with the rock sample. The leaf spring has opposite ends fixed to the inner periphery of the mounting ring. An intermediate portion of the leaf spring projecting radially inward from the ring is formed with a dimple defining a second point of contact with the sample. The first and second points of contact are diametrically opposed to each other. The LVDT is mounted in the ring with its axis parallel to the line of measurement and its core rod received in the dimple of the leaf spring. Any change in the length of the line between the first and second support points is directly communicated to the LVDT. The leaf spring is rigid to completely support lateral forces so that the LVDT is free of all load for improved precision.

  13. Gage for measuring displacements in rock samples

    DOEpatents

    Holcomb, D.J.; McNamee, M.J.

    1985-07-18

    A gage for measuring diametral displacement within a rock sample for use in a rock mechanics laboratory and in the field, comprises a support ring housing a linear variable differential transformer (LVDT), a mounting screw, and a leaf spring. The mounting screw is adjustable and defines a first point of contact with the rock sample. The leaf spring has opposite ends fixed to the inner periphery of the mounting ring. An intermediate portion of the leaf spring projecting radially inward from the ring is formed with a dimple defining a second point of contact with the sample. The first and second points of contact are diametrically opposed to each other. The LVDT is mounted in the ring with its axis parallel to the line of measurement and its core rod received in the dimple of the leaf spring. Any change in the length of the line between the first and second support points is directly communicated to the LVDT. The leaf spring is rigid to completely support lateral forces so that the LVDT is free of all load for improved precision.

  14. Transient currents in electrolyte displacement by asymmetric electro-osmosis and determination of surface zeta potentials of composite microchannels

    NASA Astrophysics Data System (ADS)

    Kuo, Ang-Tsung; Chang, Chien-Hsiang; Wei, Hsien-Hung

    2008-06-01

    In this article, we demonstrate the determination of surface zeta potentials of composite microchannels using the electric-field-driven solution displacement method. Nonuniform surface charge creates linear electro-osmotic flow, which leads to asymmetric displacement. Simplified circuit models are derived to determine the surface zeta potentials through examining the behavior of transient currents during the displacement. The effects of dispersion on the measured zeta potentials are discussed in line with the flow characteristics under different surface charge conditions.

  15. Displacement chromatography of isomers and therapeutic compounds.

    PubMed

    Qi, Yan; Huang, Junxiong

    2002-06-14

    Displacement chromatography was successfully used to separate a binary isomer mixture, epirubicin and doxorubicin, on Kromasil KR100-10 C18 250x4.6 mm I.D. (10 microm) column. Displacement parameters such as the types and the concentrations of displacer, the composition and the flow rate of the mobile phase were critically examined in this study. The displacer employed was 30 mg/ml benzethonium chloride. Loading of feed at lower initial organic level of mobile phase coupled with displacement at higher organic level was found to give efficient separation. A 30-mg amount of binary isomer mixture was separated on an analytical column. The purification of epirubicin from the closely related impurities present in raw product solution by displacement chromatography was also investigated. The purity of epirubicin required was greater than 99% with a recovery of 60%. The results have indicated that this process made good use of the high feed load, low solvent costs, and high resolution characteristics of displacement chromatography and offered the chromatographic engineer a powerful tool for the preparative purification of therapeutic compounds. PMID:12141564

  16. Time?dependent displacement of diaphragm wall induced by soil creep

    Microsoft Academic Search

    2002-01-01

    This paper presents the time?dependent performance of an well?instrumented excavation case using the top?down construction method. Studies show that this time?dependent wall displacement is mostly likely due to undrained creep of clayey soils surrounding the excavation. In other words, soil creep may make significant contributions to diaphragm wall displacement and ground settlement in a deep excavation project in soft clay

  17. Impact of caprock permeability on vertical ground surface displacements in geological underground utilisation

    NASA Astrophysics Data System (ADS)

    Kempka, Thomas; Tillner, Elena

    2015-04-01

    Geological underground utilisation inducing pore pressure changes in underground reservoirs is generally accompanied by hydro-mechanical processes. Thereby, pore pressure increase due to fluid injection may trigger ground surface uplift, while a decrease in pore pressure due to reservoir fluid production is known to induce ground subsidence. Different coupled hydro-mechanical simulation studies (e.g. Klimkowski et al., 2015, Kempka et al., 2014, Tillner et al., 2014) indicate that ground surface displacements can achieve a magnitude of several decimetres, if storage or production operations are being carried out at an industrial scale. Consequently, detailed knowledge on the parameters impacting ground surface uplift or subsidence is of major interest for the success of any geological underground utilisation in order to avoid surface infrastructure damage by spatially varying deformations. Furthermore, ground subsidence may result increased groundwater levels as experienced in different underground coal mining districts. In the present study, we carried out coupled hydro-mechanical simulations to account for the impact of caprock permeability on ground surface displacements resulting from geological underground utilisation. Thereto, different simulation scenarios were investigated using a synthetic 3D coupled numerical simulation model with varying caprock permeability and vertical location of the open well section in the target reservoir. Material property ranges were derived from available literature, while a normal faulting stress state was applied in all simulation scenarios. Our simulation results demonstrate that caprock permeability has a significant impact on the pressure development, and thus on vertical displacements at the ground surface as well as at the reservoir top. An increase in caprock permeability from 1 x 10-20 m2 by two orders of magnitude doubles vertical displacements at the ground surface, whereas vertical displacements at the reservoir top are decreased by almost 10 %. Furthermore, if the vertical location of the open well section is directly located below the caprock, vertical displacements at the ground surface are significantly higher compared to a lower open hole position. Consequently, a focus in site characterisation in the scope of geological underground utilisation should be on detailed assessment of caprock permeability. These data may be derived by well logs and hydraulic tests as well as laboratory tests on core samples. Kempka, T., Nielsen, C.M., Frykman, P., Shi, J.-Q., Bacci, G., Dalhoff, F. Coupled Hydro-Mechanical Simulations of CO2 Storage Supported by Pressure Management Demonstrate Synergy Benefits from Simultaneous Formation Fluid Extraction (2014) Oil Gas Sci Technol, doi:10.2516/ogst/2014029. Klimkowski, ?., Nagy, S., Papiernik, B., Orlic, B., Kempka, T. Numerical simulations of enhanced gas recovery at the Za??cze gas field in Poland confirm high storage capacities and mechanical integrity (2015) Oil Gas Sci Technol (accepted). Tillner, E., Shi, J-.Q., Bacci, G., Nielsen, C.M., Frykman, P., Dalhoff, F., Kempka, T. Coupled Dynamic Flow and Geomechanical Simulations for an Integrated Assessment of CO2 Storage Impacts in a Saline Aquifer (2014) Energy Procedia, 63:2879-2893, doi:10.1016/j.egypro.2014.11.311.

  18. Efficient current-induced domain-wall displacement in SrRuO3.

    PubMed

    Feigenson, Michael; Reiner, James W; Klein, Lior

    2007-06-15

    We demonstrate current-induced displacement of ferromagnetic domain walls in submicrometer fabricated patterns of SrRuO3 films. The displacement, monitored by measuring the extraordinary Hall effect, is induced at zero applied magnetic field and its direction is reversed when the current is reversed. We find that current density in the range of 10(9)-10(10) A/m2 is sufficient for domain-wall displacement when the depinning field varies between 50 to 500 Oe. These results indicate relatively high efficiency of the current in displacing domain walls which we believe is related to the narrow width (approximately 3 nm) of domain walls in this compound. PMID:17677989

  19. Viral fitness does not correlate with three genotype displacement events involving infectious hematopoietic necrosis virus

    USGS Publications Warehouse

    Kell, Alison M.; Wargo, Andrew R.; Kurath, Gael

    2014-01-01

    Viral genotype displacement events are characterized by the replacement of a previously dominant virus genotype by a novel genotype of the same virus species in a given geographic region. We examine here the fitness of three pairs of infectious hematopoietic necrosis virus (IHNV) genotypes involved in three major genotype displacement events in Washington state over the last 30 years to determine whether increased virus fitness correlates with displacement. Fitness was assessed using in vivo assays to measure viral replication in single infection, simultaneous co-infection, and sequential superinfection in the natural host, steelhead trout. In addition, virion stability of each genotype was measured in freshwater and seawater environments at various temperatures. By these methods, we found no correlation between increased viral fitness and displacement in the field. These results suggest that other pressures likely exist in the field with important consequences for IHNV evolution.

  20. Viral fitness does not correlate with three genotype displacement events involving infectious hematopoietic necrosis virus.

    PubMed

    Kell, Alison M; Wargo, Andrew R; Kurath, Gael

    2014-09-01

    Viral genotype displacement events are characterized by the replacement of a previously dominant virus genotype by a novel genotype of the same virus species in a given geographic region. We examine here the fitness of three pairs of infectious hematopoietic necrosis virus (IHNV) genotypes involved in three major genotype displacement events in Washington state over the last 30 years to determine whether increased virus fitness correlates with displacement. Fitness was assessed using in vivo assays to measure viral replication in single infection, simultaneous co-infection, and sequential superinfection in the natural host, steelhead trout. In addition, virion stability of each genotype was measured in freshwater and seawater environments at various temperatures. By these methods, we found no correlation between increased viral fitness and displacement in the field. These results suggest that other pressures likely exist in the field with important consequences for IHNV evolution. PMID:25068402

  1. 40 CFR 86.419-78 - Engine displacement, motorcycle classes.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...displacement, motorcycle classes. (a)(1) Engine displacement shall be calculated using nominal engine values and rounded to the nearest whole...accordance with ASTM E 29-67. (2) For rotary engines, displacement means the maximum...

  2. 40 CFR 86.419-2006 - Engine displacement, motorcycle classes.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...displacement, motorcycle classes. (a)(1) Engine displacement shall be calculated using nominal engine values and rounded to the nearest whole...reference in § 86.1). (2) For rotary engines, displacement means the maximum...

  3. 40 CFR 86.419-2006 - Engine displacement, motorcycle classes.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...displacement, motorcycle classes. (a)(1) Engine displacement shall be calculated using nominal engine values and rounded to the nearest whole...reference in § 86.1). (2) For rotary engines, displacement means the maximum...

  4. 40 CFR 86.419-78 - Engine displacement, motorcycle classes.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...displacement, motorcycle classes. (a)(1) Engine displacement shall be calculated using nominal engine values and rounded to the nearest whole...accordance with ASTM E 29-67. (2) For rotary engines, displacement means the maximum...

  5. 40 CFR 86.419-78 - Engine displacement, motorcycle classes.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...displacement, motorcycle classes. (a)(1) Engine displacement shall be calculated using nominal engine values and rounded to the nearest whole...accordance with ASTM E 29-67. (2) For rotary engines, displacement means the maximum...

  6. 40 CFR 86.419-2006 - Engine displacement, motorcycle classes.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...displacement, motorcycle classes. (a)(1) Engine displacement shall be calculated using nominal engine values and rounded to the nearest whole...reference in § 86.1). (2) For rotary engines, displacement means the maximum...

  7. Scale model studies of displacement ventilation

    E-print Network

    Okutan, Galip Mehmet

    1995-01-01

    Displacement ventilation is an air conditioning method that provides conditioned air to indoor environments with the goal to improve air quality while reducing energy consumption. This study investigates the performance ...

  8. Seismic transducer measures small horizontal displacements

    NASA Technical Reports Server (NTRS)

    Greenwood, T. L.

    1965-01-01

    Pendular seismic transducer mounted on base plate measures small horizontal displacements of structures subjected to vibration where no fixed reference point is available. Enclosure of transducer in transparent plastic case prevents air currents from disturbing the pendulum balance.

  9. Interferometer for measuring displacement and distance

    Microsoft Academic Search

    Toshihiro Kubota; Makoto Nara; Toshihiko Yoshino

    1987-01-01

    A simple interferometer for measuring both relative displacement and absolute distance is fabricated that uses a laser diode. The sign of the displacementis detected by means of a lambda\\/8 plate, and the distance is measured by an FM radar technique of modulating the laser-diode frequency. Measurement accuracies of 0.02 micron for displacement and 100 microns for distance are obtained over

  10. Design and Preliminary Results of a Feedback Circuit for Plasma Displacement Control in IR-T1 Tokamak

    NASA Astrophysics Data System (ADS)

    TalebiTaher, A.; Ghoranneviss, M.; Tarkeshian, R.; Khorshid, P.; Salem, M. K.

    2008-04-01

    Since displacement is very important for plasma position control, in IR-T1 tokamak a combination of two cosine coils and two saddle sine coils is used for horizontal displacement measurement. According to the multiple moment theory, the output of these coils linearly depends to radial displacement of plasma column. A new circuit for adding these signals to feedback system designed and unwanted effects of other fields in final output compensated. After compensation and calibration of the system, the output of horizontal displacement circuits applied to feedback control system. By considers the required auxiliary vertical field, a proportional amplifier and driver circuit are constructed to drive power transistors these power transistors switch the feedback bank capacitors. In the experiment, a good linear proportionality between displacement and output observed by applying an appropriate feedback field, the linger confinement time in IR-T1 tokamak obtained, applying this system to discharge increased the plasma duration and realizes repetitive discharges.

  11. Design and Preliminary Results of a Feedback Circuit for Plasma Displacement Control in IR-T1 Tokamak

    SciTech Connect

    TalebiTaher, A.; Ghoranneviss, M.; Tarkeshian, R.; Salem, M. K. [Plasma Physics Research Center, Islamic Azad University, Tehran (Iran, Islamic Republic of); Khorshid, P. [Plasma Physics Research Center, Islamic Azad University, Tehran (Iran, Islamic Republic of); Dep. of Physics, Islamic Azad University, Mashhad (Iran, Islamic Republic of)

    2008-04-07

    Since displacement is very important for plasma position control, in IR-T1 tokamak a combination of two cosine coils and two saddle sine coils is used for horizontal displacement measurement. According to the multiple moment theory, the output of these coils linearly depends to radial displacement of plasma column. A new circuit for adding these signals to feedback system designed and unwanted effects of other fields in final output compensated. After compensation and calibration of the system, the output of horizontal displacement circuits applied to feedback control system. By considers the required auxiliary vertical field, a proportional amplifier and driver circuit are constructed to drive power transistors these power transistors switch the feedback bank capacitors. In the experiment, a good linear proportionality between displacement and output observed by applying an appropriate feedback field, the linger confinement time in IR-T1 tokamak obtained, applying this system to discharge increased the plasma duration and realizes repetitive discharges.

  12. A 3D displacement measurement methodology for anisotropic porous cellular foam materials

    Microsoft Academic Search

    Rémi Guastavino; Peter Göransson

    2007-01-01

    This paper presents a new testing methodology for three dimensional (3D) full-field displacement mapping at the surface of elastic materials under static loading, here with a special focus on macroscopic behaviour of an anisotropic porous cellular foam. Three displacement components on four adjacent surfaces are estimated for cubic samples of the foam using a dual-camera 3D image correlation system. The

  13. Displacement sensor for indoor machine calibrations.

    PubMed

    Mudassar, Asloob Ahmad; Butt, Saira

    2013-05-20

    This paper presents a simple displacement sensor for indoor machine calibrations. The sensor, which is placed in the path of a diverging laser beam, consists of two plane mirror pieces laterally displaced with the line joining their centers initially held perpendicular to the optical axis of the beam during the displacement of the sensor with one of the mirrors always traveling along the optical axis of the laser beam. The optical signals from the two mirrors are combined and a simple detector at the interference plane counts the fringes during the sensor displacement. The sensor could be mounted on the moving head of any mechanical machine, e.g., the lathe machine for displacement calibration. The device has been tested over a range of 10 cm beyond a distance of 150 cm from a diverging laser source giving an accuracy of 1.1015 ?m. Theoretical modeling, simulation, and experimental results are presented which establish that the proposed sensor can be used as a promising displacement measuring device. PMID:23736230

  14. Structural behavior and inter-layer displacements in CFRP plated steel beams – Optical measurements, analysis, and comparative verification

    Microsoft Academic Search

    Christoph Czaderski; Oded Rabinovitch

    2010-01-01

    The linear elastic structural behavior of steel beams strengthened with externally bonded composite materials is experimentally and analytically investigated. The paper focuses on the full-field inter-layer relative displacements between the beam and the FRP layer. Such displacements result from the interaction between the adhesively bonded components and it is the integrated outcome of the interfacial conditions and the deformability of

  15. Estimation of structural static displacements based on vibration data using known mass perturbation

    NASA Astrophysics Data System (ADS)

    Sung, S. H.; Park, J. W.; Moon, Y. J.; Jung, H. J.

    2014-03-01

    This note presents a new method for conveniently estimating static displacements of a structure based on its vibration data. In the proposed method, structural static displacements can be estimated using a normalized modal flexibility matrix assisted by a known mass perturbation method in order to overcome several shortcomings of existing displacement sensors (e.g., linear variable differential transformers, laser Doppler vibrometer, etc) such as limitations on installation due to surrounding environments and inconvenience to the public during static loading tests. For validating the feasibility of the proposed method, experimental validation was carried out on a simply-supported beam model. In the experimental tests, the vibration data under excitation by wind loads was first measured with eight accelerometers. Then the known masses were added on a specific location on the beam and the measurements were carried out under the same settings as the first experiment. The determination of the changes in modal parameters allows estimation of the scaling constants to obtain mass-normalized mode shapes. Finally, the normalized modal flexibility matrix was calculated by using the mass-normalized mode shapes based on the scaling constants and the displacements were estimated by the normalized modal flexibility matrix. These results were compared with real static displacements estimated from the laser-type displacement sensor. It was found that they matched each other well. Therefore, the proposed method can be an effective alternative to conventional static displacement estimation.

  16. Experimental study of miscible displacement fronts in rough self-affine fractures.

    PubMed

    Auradou, H; Hulin, J P; Roux, S

    2001-06-01

    Miscible fluid displacements are studied experimentally in a radial flow between two complementary replica of a self-affine rough granite fracture surface. The displacement front between a dyed fluid and a transparent (but otherwise identical) one is followed optically through one face of the cell. The evolution of its geometry is studied as a function of time, flow-rate, and normal and lateral relative displacements between the two surfaces. For a purely normal displacement, the front is globally smooth, due to the constant local distance between surfaces. For a finite lateral displacement, the front is rough due to spatial variations of this distance; its geometry is fractal and its dimension is directly related to the Hurst exponent H approximately 0.8 of the surface. The fractal regime is observed only above a lower cut-off scale that depends on the normal spacing of the surfaces and an upper one that increases with the injected volume and with the amplitude of the lateral displacement. PMID:11415226

  17. Feedback stabilization of displaced periodic orbits: Application to binary asteroids

    NASA Astrophysics Data System (ADS)

    Simo, Jules; McInnes, Colin R.

    2014-03-01

    This paper investigates displaced periodic orbits at linear order in the circular restricted Earth-Moon system (CRTBP), where the third massless body utilizes a hybrid of solar sail and solar electric propulsion (SEP). A feedback linearization control scheme is implemented to perform stabilization and trajectory tracking for the nonlinear system. Next, attention is directed to binary asteroid systems as an application of the restricted problem. The idea of combining a solar sail with an SEP auxiliary system to obtain a hybrid sail system is important especially due to the challenges of performing complex trajectories.

  18. STUDY ON THE EFFECTIVENESS OF EARTHQUAKE-RESISTANT JOINT AGAINST SEISMIC DISPLACEMENT IN UNDERGROUND STRUCTURE

    NASA Astrophysics Data System (ADS)

    Otsuka, Hisanori; Aibe, Takeaki; Soejima, Sumireko

    In the current seismic design of underground structure, only earthquake shaking is considered and the influence of fault displacement is not considered. However, since linear underground structure such as tunnels have a possibility to be constructed across faults, they have a probability to get severe damage due to the fault displacement. In this study, Soil-underground structure-seismic fault model is analyzed by 3D finite element analysis considering slip and exfoliation between structure and the effect of fault displacement on the underground structure are evaluated. Further more the applicability of the earthquake resistant joints used for underground structure as countermeasure of ground excitations to fault displacements are studied by the numerical analysis, and it is clarified that the more increasing the number of joints and the decreasing of the space of joints introduce the more reducing of cross sectional forces.

  19. SIFT flow for large-displacement object tracking.

    PubMed

    Zhang, Huanlong; Hu, Shiqiang; Zhang, Xiaoyu

    2014-09-20

    Traditional tracking methods place an emphasis on how to cope with the variations in target appearance effectively. However, when the motion displacement of the target between image frames becomes larger, these methods may be unstable. This paper presents a novel (to our knowledge) visual object tracking method. In this method, we first introduce scale-invariant feature transform (SIFT) flow into the tracking problem and develop a real-time motion prediction method to capture large displacement between consecutive image frames. Then we use belief propagation (BP) to convert the problem of finding maximum a posteriori probability (MAP) to globally minimizing an energy function to get the best matching pairs of points for producing good candidate regions of the target. And last, the refined point trajectories are obtained according to the bidirectional flow field consistency estimation and covariance region descriptor matching, which can update model states efficiently so as to achieve enhanced robustness for visual tracking. Compared with the state-of-art tracking methods, the experimental results demonstrate that the proposed algorithm shows favorable performance when the object undergoes large motion displacement between image frames. PMID:25322097

  20. FDTD analysis of human body-core temperature elevation due to RF far-field energy prescribed in the ICNIRP guidelines

    NASA Astrophysics Data System (ADS)

    Hirata, Akimasa; Asano, Takayuki; Fujiwara, Osamu

    2007-08-01

    This study investigated the relationship between the specific absorption rate and temperature elevation in an anatomically-based model named NORMAN for exposure to radio-frequency far fields in the ICNIRP guidelines (1998 Health Phys. 74 494-522). The finite-difference time-domain method is used for analyzing the electromagnetic absorption and temperature elevation in NORMAN. In order to consider the variability of human thermoregulation, parameters for sweating are derived and incorporated into a conventional sweating formula. First, we investigated the effect of blood temperature variation modeling on body-core temperature. The computational results show that the modeling of blood temperature variation was the dominant factor influencing the body-core temperature. This is because the temperature in the inner tissues is elevated via the circulation of blood whose temperature was elevated due to EM absorption. Even at different frequencies, the body-core temperature elevation at an identical whole-body average specific absorption rate (SAR) was almost the same, suggesting the effectiveness of the whole-body average SAR as a measure in the ICNIRP guidelines. Next, we discussed the effect of sweating on the temperature elevation and thermal time constant of blood. The variability of temperature elevation caused by the sweating rate was found to be 30%. The blood temperature elevation at the basic restriction in the ICNIRP guidelines of 0.4 W kg-1 is 0.25 °C even for a low sweating rate. The thermal time constant of blood temperature elevation was 23 min and 52 min for a man with a lower and a higher sweating rate, respectively, which is longer than the average time of the SAR in the ICNIRP guidelines. Thus, the whole-body average SAR required for blood temperature elevation of 1 °C was 4.5 W kg-1 in the model of a human with the lower sweating coefficients for 60 min exposure. From a comparison of this value with the basic restriction in the ICNIRP guidelines of 0.4 W kg-1, the safety factor was 11.

  1. Dislocation and Stacking Fault Core Fields in FCC Metals

    SciTech Connect

    Henager, Charles H.; Hoagland, Richard G.

    2005-12-21

    Atomistic models were used to determine the properties of dislocation core fields and stacking fault fields in Al and Cu using embedded atom method (EAM) potentials. Long-range, linear elastic displacement fields due to nonlinear behavior within dislocation cores, the core field, for relevant combinations of Shockley partial dislocations for edge, screw, and mixed (60? and 30?) geometries were obtained. Displacement fields of stacking faults were obtained separately and used to partition the core field of dissociated dislocations into core fields of partial dislocations and a stacking fault expansion field. Core field stresses were derived from which the total force, including the Volterra field plus core field, between dislocations for several dislocation configurations was determined. The Volterra field dominates when the distance between dislocations exceeds about 50b but forces due to core fields are important for smaller separation distances and were found to affect the equilibrium angle of edge dislocation dipoles and to contribute to the force between otherwise non-interacting edge and screw dislocations. Interactions among the components of a dissociated dislocation modify the equilibrium separation for Shockley partials suggesting that methods that determine stacking fault energies using measurements of separation distances should include core fields.

  2. Landslide displacement measurements from Optical Satellite Images: A Case Study on the North Anatolian Fault Zone

    NASA Astrophysics Data System (ADS)

    Turk, Tarik; Gorum, Tolga; Birdal, Anil Can; Tatar, Orhan

    2015-04-01

    Several geodetic and remote sensing methods are used to monitor the movements due to the tectonic and geomorphic processes and the assessment of associated hazards. Recent advances in image-correlation techniques and high resolution satellite imaging at meter resolution offer the possibility to measure surface displacements with sub-metric accuracy. Moreover, this methods enables an accurate mapping of the surface displacements, and vector visualization of the horizontal movements over a period through establishing correlation among the different dated satellite images belonging to the same area. This study analyzes the displacement pattern of the earth flows using sub-pixel image correlation techniques along the tectonic Kelkit Valley, Central Anatolia, Turkey. In this study, we used Co-Registration of Optically Sensed Images and Correlation (Cosi-Corr) to measure the horizontal surface displacement of landslides from SPOT-5 images. The significance of the horizontal displacement results was verified through fieldwork studies. The landslide displacement vectors obtained from SPOT 5 (2.5 meter resolution) optical satellite images on 11 August 2006 and 21 September 2011 indicate that many of the old landslides reactivated in the study area. It was determined that such reactivation occurred due to the secondary slides developed inside the main body of the old landslides, especially in their accumulation sections. The horizontal displacement values in the accumulation sections of the old landslides vary between 4.9 and -7.7 meters in the North-South direction and between 8.2 and -5 meters in the East-West direction. The maximum displacement values were observed in the eastern hill-slopes. The results show that the Cosi-Corr technique provides important contributions in the determination of the landslide movements especially with very slow, slow to moderate slip velocities and their deformation quantities and patterns. Acknowledgements This research was financially supported by the Scientific and Technological Research Council of Turkey (TUBITAK) Project Numbered 113Y188.

  3. Inefficiency of upward displacement operating theatre ventilation.

    PubMed

    Friberg, B; Friberg, S; Burman, L G; Lundholm, R; Ostensson, R

    1996-08-01

    A new thermally based ventilation system ('Floormaster') with inlet of cool clean air at floor level, and evacuation at the ceiling of the air warmed by activity in the room (upward displacement ventilation, 17 air changes/h) was compared with a standard positive pressure (plenum) ventilation system with air supply through an inclined perforated screen along one wall at the ceiling and evacuation at floor level (conventional turbulent or mixing system, 16 air changes/h). The study was made during rigidly standardized sham operations (N = 20) performed in the same operating room by a six-member team wearing non-woven disposable or cotton clothing. In general the upward displacement system removed dust particles too small to carry bacteria (0.16-<0.3 microm, 0.001displacement system also yielded two to threefold higher air and surface bacterial counts in areas important for surgical asepsis (wound area, instrument table) especially with regard to bacterial sedimentation (0.001displacement system was insufficient elimination of the larger bacteria-carrying particles. The type of clothing worn by the members of the team did not influence the overall results. We conclude that an upward displacement system will lead to increased counts of airborne and sedimenting bacteria and thus increase the risk of postoperative infection in comparison with conventional operating room ventilation systems. PMID:8999051

  4. Measurement of Object Displacement Using Phase Stepped, Real-Time Holographic Interferometry

    Microsoft Academic Search

    Benjie Ovryn

    1992-01-01

    Phase stepped holographic interferometry is a noncontact method for measuring displacements over a large field of view with a precision of about 5 nm. The whole -field capabilities and high sensitivity of this method make it potentially unrivaled for measuring spatial inhomogeneities, for example, the proposed spatial variation of the piezoelectric coefficient in cortical bone. This dissertation has advanced the

  5. Residual Seminal Vesicle Displacement in Marker-Based Image-Guided Radiotherapy for Prostate Cancer and the Impact on Margin Design

    SciTech Connect

    Smitsmans, Monique H.P.; Bois, Josien de; Sonke, Jan-Jakob [Department of Radiation Oncology, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam (Netherlands); Catton, Charles N. [Radiation Medicine Program, Princess Margaret Hospital, Ontario Cancer Institute, Department of Radiation Oncology, Toronto (Canada); Jaffray, David A. [Radiation Medicine Program, Princess Margaret Hospital, Ontario Cancer Institute, Department of Radiation Physics, Toronto (Canada); Lebesque, Joos V. [Department of Radiation Oncology, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam (Netherlands); Herk, Marcel van, E-mail: portal@nki.n [Department of Radiation Oncology, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam (Netherlands)

    2011-06-01

    Purpose: The objectives of this study were to quantify residual interfraction displacement of seminal vesicles (SV) and investigate the efficacy of rotation correction on SV displacement in marker-based prostate image-guided radiotherapy (IGRT). We also determined the effect of marker registration on the measured SV displacement and its impact on margin design. Methods and Materials: SV displacement was determined relative to marker registration by using 296 cone beam computed tomography scans of 13 prostate cancer patients with implanted markers. SV were individually registered in the transverse plane, based on gray-value information. The target registration error (TRE) for the SV due to marker registration inaccuracies was estimated. Correlations between prostate gland rotations and SV displacement and between individual SV displacements were determined. Results: The SV registration success rate was 99%. Displacement amounts of both SVs were comparable. Systematic and random residual SV displacements were 1.6 mm and 2.0 mm in the left-right direction, respectively, and 2.8 mm and 3.1 mm in the anteroposterior (AP) direction, respectively. Rotation correction did not reduce residual SV displacement. Prostate gland rotation around the left-right axis correlated with SV AP displacement (R{sup 2} = 42%); a correlation existed between both SVs for AP displacement (R{sup 2} = 62%); considerable correlation existed between random errors of SV displacement and TRE (R{sup 2} = 34%). Conclusions: Considerable residual SV displacement exists in marker-based IGRT. Rotation correction barely reduced SV displacement, rather, a larger SV displacement was shown relative to the prostate gland that was not captured by the marker position. Marker registration error partly explains SV displacement when correcting for rotations. Correcting for rotations, therefore, is not advisable when SV are part of the target volume. Margin design for SVs should take these uncertainties into account.

  6. Crack opening displacement determination in damaged cross-ply laminate using electronic speckle pattern interferometry (ESPI)

    NASA Astrophysics Data System (ADS)

    Zrida, H.; Loukil, M. S.; Varna, J.; Ayadi, Z.

    2012-02-01

    Composite laminates during service undergo complex combinations of thermal and mechanical loading leading to microdamage accumulation in the plies. The most common damage mode and the one examined in this work is intralaminar cracking in layers. The crack opening displacement (COD) and the crack sliding displacement (CSD) during loading reduce the average stress in the damaged layer, thus reducing the laminate stiffness. These parameters depend on material properties of the damaged layer and surrounding layers, on layer orientation and thickness. Previously these parameters have been calculated using finite element method (FEM) assuming linear elastic material with idealized geometry of cracks. To validate these assumptions experimentally the displacement field on the surface of a [90/0/90] carbon fiber/epoxy laminate specimens with multiple intralaminar cracks in the surface layer is studied and the COD dependence on the applied mechanical load is measured. The specimen full-field displacement measurement is carried out using ESPI (Electronic Speckle Pattern Interferometry). The displacement jumps corresponding to cracks are clearly visible and can be used to determine the opening displacement along the cracks. The effect of crack interaction on the COD at high crack density is also investigated.

  7. Dynamical Field Line Connectivity in Magnetic Turbulence

    NASA Astrophysics Data System (ADS)

    Ruffolo, D.; Matthaeus, W. H.

    2015-06-01

    Point-to-point magnetic connectivity has a stochastic character whenever magnetic fluctuations cause a field line random walk, but this can also change due to dynamical activity. Comparing the instantaneous magnetic connectivity from the same point at two different times, we provide a nonperturbative analytic theory for the ensemble average perpendicular displacement of the magnetic field line, given the power spectrum of magnetic fluctuations. For simplicity, the theory is developed in the context of transverse turbulence, and is numerically evaluated for the noisy reduced MHD model. Our formalism accounts for the dynamical decorrelation of magnetic fluctuations due to wave propagation, local nonlinear distortion, random sweeping, and convection by a bulk wind flow relative to the observer. The diffusion coefficient DX of the time-differenced displacement becomes twice the usual field line diffusion coefficient Dx at large time displacement t or large distance z along the mean field (corresponding to a pair of uncorrelated random walks), though for a low Kubo number (in the quasilinear regime) it can oscillate at intermediate values of t and z. At high Kubo number the dynamical decorrelation decays mainly from the nonlinear term and DX tends monotonically toward 2Dx with increasing t and z. The formalism and results presented here are relevant to a variety of astrophysical processes, such as electron transport and heating patterns in coronal loops and the solar transition region, changing magnetic connection to particle sources near the Sun or at a planetary bow shock, and thickening of coronal hole boundaries.

  8. A theoretical analysis on parameters of fiber optic displacement sensor

    NASA Astrophysics Data System (ADS)

    Xu, Bingshi; Xiao, Wen; Yao, Dong

    2008-10-01

    This paper discusses the characteristic of two-fiber, intensity modulated FODS, a type of high sensitivity displacement sensor, from a theoretical prospective, focusing on the geometrical parameters including fiber aperture (NA), radius of fiber core (r), lateral separation of the transmitting and receiving fibers (s), the angle between the two fibers (2a), and the reflector curvature radius (Rc). A mathematical model is set up to investigate the influence on the performance of FODS introduced by the variation of these parameters, and the simulation results are also presented to conduct farther study in this field.

  9. Rhetorics of Displacement: Constructing Identities in Forced Relocations

    ERIC Educational Resources Information Center

    Powell, Katrina M.

    2012-01-01

    Forced displacement has often involved the use of rhetoric, both by government institutions and by people who struggle not only to survive displacement, but also to resist it. In this article, the author offers first a theoretical framework that informs her thinking about displacement narratives. She briefly examines two published displacement

  10. Traumatic testicular displacement in motorcycle drivers.

    PubMed

    Je?menica, Dragan S; Alempijevi?, Djordje M; Pavleki?, Snežana; Aleksandri?, Branimir V

    2011-03-01

    Testicular displacement is a rare clinical presentation of blunt scrotal injury that may take place in road traffic accidents involving motorcycle occupants. We are presenting two cases of motorcycle occupant fatalities, 21 and 24 years of age, where testicular displacement and other signs of groin trauma have been determined. In both cases, discrete external signs of scrotal trauma were noted on examination, while unilateral and bilateral traumatic testicular displacement, respectively, have been documented at autopsy. For motorcycle occupants involved in collision, it is necessary to perform a thorough analysis of injuries, in particular to look for specific trauma arising from fuel-tank impact to genitalia and/or groin. These injuries are of great medico-legal importance both at postmortem and in clinical cases involving motorcycle occupants involved in collision. PMID:21306375

  11. Displacement of RFID tracers in a steep mountain stream (Rio Cordon, Italy)

    NASA Astrophysics Data System (ADS)

    Rainato, Riccardo; Mao, Luca; Aristide Lenzi, Mario; Picco, Lorenzo

    2015-04-01

    The bedload transport plays a fundamental role in the mountain streams affecting several aspects as morphology and ecological status of the fluvial system, influencing fields as engineering, natural hazard and river management. The monitoring, assessment and quantification of this type of transport is not simple due to impulsive nature that distinguishes it. Moreover, in mountain streams the particle motion is strongly affected by the bed structures as well as by the highly heterogeneous bed material, acting especially through the hiding/exposure, consolidation and embedding effects. Thanks to the assumption that bedload transport may be understood as the result of random individual particle displacements, the sediment tracing method was widely employed in the last years. Such method allow to obtain precious data concerning sediment dynamic in mountain streams, improving the results obtainable by samplers, traps and permanent monitoring stations. In this work, the results obtained by two years of RFID tracers monitoring are presented. This typology of tracers was employed in a steep mountain stream in order to investigate the displacement due to different conditions of hydraulic forcing. The Rio Cordon (northeast Italy) is a typical alpine channel characterized by step-pool and riffle-pool morphology and by a mean slope equal to 13%. The catchment extended 5 km2 exhibits a nivo-pluvial runoff regime. Overall, 250 tracers were seeded in the channel bed, monitoring the travel distance along a study reach 318 m long. For this purpose a mobile antenna in combination with a laser rangefinder were used. The measurement campaign was carried out from 2013 to 2014, performing a survey every 2 months as well as after every flood event occurred. Following such approach 7 tracers monitoring were performed, reaching a mean tracers recovery rate of roughly 65%. During the study period the peak of flood discharges is ranged between 0.85 to 2.10 m3 s-1, therefore allowing to investigate the transport distance due to hydraulic conditions that varied between about a third of bankfull discharge (2.30 m3 s-1) to values very close to it. The results showed negligible displacements (< 1 m) due to the peak discharges lower than 1 m3 s-1 while travel distances abruptly increases as consequence of higher flow magnitude. The mean transport distance reaches values near to 7 m as a result of peak discharges between 1 and 2 m3 s-1 while for the larger floods (> 2 m3 s-1) the mean displacement increase of one order of magnitude, ranging between 63 and 79 m. In this sense, also a different dynamic of transport was observed, with the medium range of peak discharges (1-2 m3 s-1) characterized by size selective transport while an equal mobility condition is shown by the larger floods. This research was funded by the Italian Project of Relevant Interest N.20104ALME4; ITSE: National network for monitoring, modeling and sustainable management of erosion processes in agricultural land and hilly-mountainous area.

  12. Development of A Continuous Process for Displacement Dewatering

    SciTech Connect

    Dave Beck

    2006-10-30

    The subject of this contract was to investigate the viability of a new process for dewatering paper called displacement pressing. The term “displacement pressing” was coined in the 1980s by researchers to describe a paper dewatering process where air is blown through a sheet of paper while it is being pressed. It was shown at that time that the combination of air and low pressing force could dramatically increase both sheet bulk and sheet solids which in theory would translate into huge savings in energy and fiber consumption. But there was a catch. Although the research results were dramatic, no one could figure out a commercially viable process to carry out displacement pressing. All research work had been done with batch processes, and there was no obvious way to convert these processes into a continuous process. By the end of the early1990’s no one was researching in this area because no continuous process existed. Recently we proposed a new method to carry out displacement pressing. Our process uses special pressing fabrics and a special 4 roll press that we call a “Beck Cluster Press” or BCP. The BCP provides a pressurized atmosphere that acts on a moving web of paper and fabrics. The special fabrics designed for this process use this atmosphere to press the sheet and at the same time, these special fabrics force air through the sheet to carry out displacement pressing. 1 Because of the complexity and cost of building the first functioning BCP, a simple simulator was built to confirm and study the process. Although results from this simulator were extremely favorable, financial times were hard in the paper industry. We are grateful for the DOE contract that allowed us to continue research that showed the tremendous benefits of displacement pressing. Specifically, accomplishments from the DOE contract are as follows: 1. A narrow (5” wide sheet) lab Beck Cluster Press (BCP) was started up, and made operational. This press accepts hand sheets and displacement presses them at conditions that duplicate commercial conditions for dwell time, and pressure. 2. The lab BCP machine was used to verify simulator results. Results showed the lab BCP gave paper dryness that exceeded simulator results for dryness. 3. Sheet samples were obtained for several paper grades. These samples were pressed conventionally (shoe and roll presses) and with the lab BCP. Results showed significant gains in bulk (5-48%) compared to commercially pressed sheets while producing similar or higher dryness. These results verified the predictions of the earlier research papers. 4. Sheet bulk exceeded the Agenda 2020 goal a 7% increase. This increase in bulk was reported by Agenda 2020 as being worth about 3 billion dollars per year in fiber savings. Potential energy savings due to dryness savings could be worth $1 billion per year. However energy savings and fiber savings are inter-related so while savings are likely in both energy and fiber at the same time, increasing one will cause the other to decrease. 5. Based on the significant results of small-scale BCP trials, a 1m pilot BCP press stand was built to determine scalability of the process. 6. 1m pilot press stand was started up. This machine was shown to hold design pressure. Drive issues however prevented operation at operating speed and pressure during the contact period. Improvements to the drive system since the end of the DOE contract have allowed us to reach operating pressure and speed. 7. The last DOE objective of passing paper through the 1m BCP was not reached due to drive issues and the desire to study and qualify sealing systems. All other original objectives and the added objective (by contract revision) of this ambitious project have been met. 8. Several paper companies have showed interest in helping us commercialize this process. Interest is so high that these companies appear willing to invest in further development.

  13. Set-up for calorimetric measurements of the AC losses in HTS tapes due to longitudinal magnetic fields and transport currents

    Microsoft Academic Search

    N. Magnusson; S. Borsos; S. Hörnfeldt

    2002-01-01

    For the design of power applications based on high-temperature superconducting (HTS) tapes, knowledge of the AC losses is needed. In most such applications the HTS tape is exposed to a magnetic field oriented perpendicular to the current path. However, in certain applications, the HTS tape is exposed to a field oriented in parallel with the current path; a longitudinal magnetic

  14. Disturbance to the population due to flight operations at landing fields. Questionnaire on community reaction to non-commercial and sporting aviation

    NASA Technical Reports Server (NTRS)

    Rohrmann, B.

    1981-01-01

    A field study was undertaken to determine the Sociopsychological effects of air traffic noise experienced by residents of areas near small sporting aviation fields. A questionaire was prepared which includes questions on flight restriction measures, on attitudes which moderate annoyance and on comparisons with other noise sources, etc.

  15. Frictional behavior of large displacement experimental faults

    USGS Publications Warehouse

    Beeler, N.M.; Tullis, T.E.; Blanpied, M.L.; Weeks, J.D.

    1996-01-01

    The coefficient of friction and velocity dependence of friction of initially bare surfaces and 1-mm-thick simulated fault gouges (400 mm at 25??C and 25 MPa normal stress. Steady state negative friction velocity dependence and a steady state fault zone microstructure are achieved after ???18 mm displacement, and an approximately constant strength is reached after a few tens of millimeters of sliding on initially bare surfaces. Simulated fault gouges show a large but systematic variation of friction, velocity dependence of friction, dilatancy, and degree of localization with displacement. At short displacement (<10 mm), simulated gouge is strong, velocity strengthening and changes in sliding velocity are accompanied by relatively large changes in dilatancy rate. With continued displacement, simulated gouges become progressively weaker and less velocity strengthening, the velocity dependence of dilatancy rate decreases, and deformation becomes localized into a narrow basal shear which at its most localized is observed to be velocity weakening. With subsequent displacement, the fault restrengthens, returns to velocity strengthening, or to velocity neutral, the velocity dependence of dilatancy rate becomes larger, and deformation becomes distributed. Correlation of friction, velocity dependence of friction and of dilatancy rate, and degree of localization at all displacements in simulated gouge suggest that all quantities are interrelated. The observations do not distinguish the independent variables but suggest that the degree of localization is controlled by the fault strength, not by the friction velocity dependence. The friction velocity dependence and velocity dependence of dilatancy rate can be used as qualitative measures of the degree of localization in simulated gouge, in agreement with previous studies. Theory equating the friction velocity dependence of simulated gouge to the sum of the friction velocity dependence of bare surfaces and the velocity dependence of dilatancy rate of simulated gouge fails to quantitatively account for the experimental observations.

  16. Atomistic Simulation of Displacement Cascades in Zircon

    SciTech Connect

    Devanathan, Ram; Weber, William J.; Corrales, Louis R.; BP McGrail and GA Cragnolino

    2002-05-06

    Low energy displacement cascades in zircon (ZrSiO4) initiated by a Zr primary knock-on atom have been investigated by molecular dynamics simulations using a Coulombic model for long-range interactions, Buckingham potential for short-range interactions and Ziegler-Biersack potentials for close pair interactions. Displacements were found to occur mainly in the O sublattice, and O replacements by a ring mechanism were predominant. Clusters containing Si interstitials bridged by O interstitials, vacancy clusters and anti-site defects were found to occur. This Si-O-Si bridging is considerable in quenched liquid ZrSiO4.

  17. Impact of plasma response on plasma displacements in DIII-D during application of external 3D perturbations

    SciTech Connect

    Wingen, Andreas [ORNL; Ferraro, N. M. [General Atomics, San Diego; Shafer, M.W. [Oak Ridge National Laboratory (ORNL); Unterberg, Ezekial A [ORNL; Evans, T. E. [General Atomics, San Diego; Hillis, Donald Lee [ORNL; Snyder, P. B. [General Atomics, San Diego

    2014-01-01

    The effects of applied 3D resonant magnetic perturbations are modelled with and without self-consistent plasma response. The plasma response is calculated using a linear two-fluid model. A synthetic diagnostic is used to simulate soft x-ray (SXR) emission within the steep gradient region of the pedestal, 0.98 > > 0.94. Two methods for simulating the SXR emission given the perturbed fields are considered. In the first method, the emission is assumed to be constant on magnetic field lines, with the emission on each line determined by the penetration depth into the plasma. In the second method, the emission is taken to be a function of the perturbed electron temperature and density calculated by the two-fluid model. It is shown that the latter method is more accurate within the plasma, but is inadequate in the scrape-off layer due to the breakdown of the linearized temperature equation in the two-fluid model. The resulting synthetic emission is compared to measured SXR data, which show helical m = 11 1 displacements around the 11/3 rational surface of sizes up to 5 cm, depending on the poloidal angle. The helical displacements around the 11/3 surface are identified to be directly related to the kink response, caused by amplification of non-resonant components of the magnetic field due to plasma response. The role of different plasma parameters is investigated, but it appears that the electron rotation plays a key role in the formation of screening and resonant amplification, while the kinking appears to be sensitive to the edge current density. It is also hypothesized that the plasma response affects the edge-localized-mode (ELM) stability, i.e. the discharge s operational point relative to the peeling ballooning stability boundary.

  18. Impact of plasma response on plasma displacements in DIII-D during application of external 3D perturbations

    NASA Astrophysics Data System (ADS)

    Wingen, A.; Ferraro, N. M.; Shafer, M. W.; Unterberg, E. A.; Evans, T. E.; Hillis, D. L.; Snyder, P. B.

    2014-06-01

    The effects of applied 3D resonant magnetic perturbations are modelled with and without self-consistent plasma response. The plasma response is calculated using a linear two-fluid model. A synthetic diagnostic is used to simulate soft x-ray (SXR) emission within the steep gradient region of the pedestal, 0.98 > ? > 0.94. Two methods for simulating the SXR emission given the perturbed fields are considered. In the first method, the emission is assumed to be constant on magnetic field lines, with the emission on each line determined by the penetration depth into the plasma. In the second method, the emission is taken to be a function of the perturbed electron temperature and density calculated by the two-fluid model. It is shown that the latter method is more accurate within the plasma, but is inadequate in the scrape-off layer due to the breakdown of the linearized temperature equation in the two-fluid model. The resulting synthetic emission is compared to measured SXR data, which show helical m = 11 ± 1 displacements around the 11/3 rational surface of sizes up to 5 cm, depending on the poloidal angle. The helical displacements around the 11/3 surface are identified to be directly related to the kink response, caused by amplification of non-resonant components of the magnetic field due to plasma response. The role of different plasma parameters is investigated, but it appears that the electron rotation plays a key role in the formation of screening and resonant amplification, while the kinking appears to be sensitive to the edge current density. It is also hypothesized that the plasma response affects the edge-localized-mode (ELM) stability, i.e. the discharge's operational point relative to the peeling-ballooning stability boundary.

  19. 3D displacement time series in the Afar rift zone computed from SAR phase and amplitude information

    NASA Astrophysics Data System (ADS)

    Casu, Francesco; Manconi, Andrea

    2013-04-01

    Large and rapid deformations, such as those caused by earthquakes, eruptions, and landslides cannot be fully measured by using standard DInSAR applications. Indeed, the phase information often degrades and some areas of the interferograms are affected by high fringe rates, leading to difficulties in the phase unwrapping, and/or to complete loss of coherence due to significant misregistration errors. This limitation can be overcome by exploiting the SAR image amplitude information instead of the phase, and by calculating the Pixel-Offset (PO) field SAR image pairs, for both range and azimuth directions. Moreover, it is possible to combine the PO results by following the same rationale of the SBAS technique, to finally retrieve the offset-based deformation time series. Such technique, named PO-SBAS, permits to retrieve the deformation field in areas affected by very large displacements at an accuracy that, for ENVISAT data, correspond to 30 cm and 15 cm for the range and azimuth, respectively [1]. Moreover, the combination of SBAS and PO-SBAS time series can help to better study and model deformation phenomena characterized by spatial and temporal heterogeneities [2]. The Dabbahu rift segment of the Afar depression has been active since 2005 when a 2.5 km3 dyke intrusion and hundreds of earthquakes marked the onset a rifting episode which continues to date. The ENVISAT satellite has repeatedly imaged the Afar depression since 2003, generating a large SAR archive. In this work, we study the Afar rift region deformations by using both the phase and amplitude information of several sets of SAR images acquired from ascending and descending ENVISAT tracks. We combined sets of small baseline interferograms through the SBAS algorithm, and we generate both ground deformation maps and time series along the satellite Line-Of-Sight (LOS). In areas where the deformation gradient causes loss of coherence, we retrieve the displacement field through the amplitude information. Furthermore, we could also retrieve the full 3D deformation field, by considering the North-South displacement component obtained from the azimuth PO information. The combination of SBAS and PO-SBAS information permits to better retrieve and constrain the full deformation field due to repeated intrusions, fault movements, as well as the magma movements from individual magma chambers. [1] Casu, F., A. Manconi, A. Pepe and R. Lanari, 2011. Deformation time-series generation in areas characterized by large displacement dynamics: the SAR amplitude Pixel-Offset SBAS technique, IEEE Transaction on Geosciences and Remote Sensing. [2] Manconi, A. and F. Casu, 2012. Joint analysis of displacement time series retrieved from SAR phase and amplitude: impact on the estimation of volcanic source parameters, Geophysical Research Letters, doi:10.1029/2012GL052202.

  20. On the biophysics and kinetics of toehold-mediated DNA strand displacement

    PubMed Central

    Srinivas, Niranjan; Ouldridge, Thomas E.; Šulc, Petr; Schaeffer, Joseph M.; Yurke, Bernard; Louis, Ard A.; Doye, Jonathan P. K.; Winfree, Erik

    2013-01-01

    Dynamic DNA nanotechnology often uses toehold-mediated strand displacement for controlling reaction kinetics. Although the dependence of strand displacement kinetics on toehold length has been experimentally characterized and phenomenologically modeled, detailed biophysical understanding has remained elusive. Here, we study strand displacement at multiple levels of detail, using an intuitive model of a random walk on a 1D energy landscape, a secondary structure kinetics model with single base-pair steps and a coarse-grained molecular model that incorporates 3D geometric and steric effects. Further, we experimentally investigate the thermodynamics of three-way branch migration. Two factors explain the dependence of strand displacement kinetics on toehold length: (i) the physical process by which a single step of branch migration occurs is significantly slower than the fraying of a single base pair and (ii) initiating branch migration incurs a thermodynamic penalty, not captured by state-of-the-art nearest neighbor models of DNA, due to the additional overhang it engenders at the junction. Our findings are consistent with previously measured or inferred rates for hybridization, fraying and branch migration, and they provide a biophysical explanation of strand displacement kinetics. Our work paves the way for accurate modeling of strand displacement cascades, which would facilitate the simulation and construction of more complex molecular systems. PMID:24019238

  1. How to avoid simulation sickness in virtual environments during user displacement

    NASA Astrophysics Data System (ADS)

    Kemeny, A.; Colombet, F.; Denoual, T.

    2015-03-01

    Driving simulation (DS) and Virtual Reality (VR) share the same technologies for visualization and 3D vision and may use the same technics for head movement tracking. They experience also similar difficulties when rendering the displacements of the observer in virtual environments, especially when these displacements are carried out using driver commands, including steering wheels, joysticks and nomad devices. High values for transport delay, the time lag between the action and the corresponding rendering cues and/or visual-vestibular conflict, due to the discrepancies perceived by the human visual and vestibular systems when driving or displacing using a control device, induces the so-called simulation sickness. While the visual transport delay can be efficiently reduced using high frequency frame rate, the visual-vestibular conflict is inherent to VR, when not using motion platforms. In order to study the impact of displacements on simulation sickness, we have tested various driving scenarios in Renault's 5-sided ultra-high resolution CAVE. First results indicate that low speed displacements with longitudinal and lateral accelerations under a given perception thresholds are well accepted by a large number of users and relatively high values are only accepted by experienced users and induce VR induced symptoms and effects (VRISE) for novice users, with a worst case scenario corresponding to rotational displacements. These results will be used for optimization technics at Arts et Métiers ParisTech for motion sickness reduction in virtual environments for industrial, research, educational or gaming applications.

  2. Three-dimensional elastic stress and displacement analysis of finite geometry solids containing cracks

    NASA Technical Reports Server (NTRS)

    Kring, J.; Gyekenyesi, J.; Mendelson, A.

    1977-01-01

    The line method of analysis is applied to the Navier-Cauchy equations of elastic equilibrium to calculate the displacement fields in finite geometry bars containing central, surface, and double-edge cracks under extensionally applied uniform loading. The application of this method to these equations leads to coupled sets of simultaneous ordinary differential equations whose solutions are obtained along sets of lines in a discretized region. Normal stresses and the stress intensity factor variation along the crack periphery are calculated using the obtained displacement field. The reported results demonstrate the usefulness of this method in calculating stress intensity factors for commonly encountered crack geometries in finite solids.

  3. Modeling elastomer displacements for tactile sensing applications

    SciTech Connect

    Novak, J.L.

    1990-02-01

    Many capacitance-based tactile sensors measure the displacements of an elastic substrate at multiple sites. A large number of sensing applications, however, require knowledge of the surface forces. This report considers the problem of reconstructing these surface forces from the measured displacements. Two models for reconstruction are considered. Contacts in which the area is much smaller than the dimensions of the compliant surface are modelled using a linear elastic half-space. Analyses of the deformations using this model confirm a strong coupling between normal and tangential displacements for normal, tangential or arbitrary loads. Using a spatial frequency formulation, the minimum spatial sampling densities for reconstructing displacements (as a prerequisite to reconstructing forces) are shown to be significantly smaller than those required for reconstructing strains. The second model, the bonded spring, is introduced for surface contacts which extend over the entire sensor surface. A nonlinear stress-strain relationship is included since tactile sensors undergo relatively large deformations. An empirical relationship between elastic pad geometry and the effective modulus of elasticity is also presented. 22 refs., 5 figs., 1 tab.

  4. RECOVERY OF METALS USING ALUMINUM DISPLACEMENT

    EPA Science Inventory

    The removal of typical metals (Cu, Pb, Sn, Ni) from printed circuit and metal finishing waste streams was evaluated using displacement with aluminum. he metal is recovered as non-hazardous metal particles and can be recycled by smelting. n acceptable aluminum metal configuration ...

  5. RECOVERY OF METAL USING ALUMINUM DISPLACEMENT

    EPA Science Inventory

    The removal of typical metals (Cu, Pb, Sn, Ni) from printed circuit and metal finishing waste streams was evaluated using displacement with aluminum. he metal is recovered as non-hazardous metal particles and can be recycled by smelting. n acceptable aluminum metal configuration ...

  6. Dissociation and Displacement: Where Goes the “Ouch?”

    Microsoft Academic Search

    John G. Watkins; Helen H. Watkins

    1990-01-01

    Hypnosis is widely used to relieve pain. Current theory emphasizes its dissociative features. Multiple personality patients can eliminate pain in the primary personality by displacing it into underlying alters. The Hilgards demonstrated that normal hypnotized subjects can similarly dissociate pain into a covert cognitive structural system which they called the “hidden observer.” The Watkins discovered that “hidden observers” appeared to

  7. Coreflood experimental study of steam displacement

    E-print Network

    Cerutti, Andres Enrique

    1997-01-01

    The main objective of this study was to verify experimentally whether or not a Buckley-Leverett shock front exists when steam displaces oil in a porous medium, as assumed in the Aydelotte-Pope steamflood predictive model. Experiments were conducted...

  8. Phase displacement acceleration in the SSC

    SciTech Connect

    Hofmann, A.

    1984-08-01

    The SSC (Superconducting Super Collider) is supposed to operate with bunched beams and the energy radiated by synchrotron radiation is replaced by the rf-system having a synchronous phase angle slightly different from 180/sup 0/. Here the case of operating the SSC with a coasting beam is considered. In particular the possibility of replacing the radiated energy phase displacement acceleration is investigated.

  9. Embedded fiber optic beam displacement sensor

    Microsoft Academic Search

    Roger M. Crane; Eugene C. Fischer

    1991-01-01

    This document discloses a method and apparatus for the two dimensional measurement of displacements of sample materials using a photodetector grid array and optical fiber embedded in the test specimen. The system consists of a light source which is passed into one end of an optical fiber which has embedded a beam specimen, so that when the beam is placed

  10. Acoustic shear wave displacement measurement using ultrasound

    Microsoft Academic Search

    Vinayak Dutt; Randall R. Kinnick; James F. Greenleaf

    1996-01-01

    Echo ultrasound can be used to detect and measure acoustic shear waves. Earlier it has been shown that a phase contrast based magnetic resonance imaging technique can be used for cyclic shear wave displacement measurement. Echo ultrasound presents an alternate method for imaging of such shear waves. The ultrasound based method uses the phase of quadrature echo signals to estimate

  11. Variable-Displacement Hydraulic Drive Unit

    NASA Technical Reports Server (NTRS)

    Lang, D. J.; Linton, D. J.; Markunas, A.

    1986-01-01

    Hydraulic power controlled through multiple feedback loops. In hydraulic drive unit, power closely matched to demand, thereby saving energy. Hydraulic flow to and from motor adjusted by motor-control valve connected to wobbler. Wobbler angle determines motor-control-valve position, which in turn determines motor displacement. Concept applicable to machine tools, aircraft controls, and marine controls.

  12. Extracting gravity line displacement from stabilographic recordings

    Microsoft Academic Search

    Deborah L. King; Vladimir M. Zatsiorsky

    1997-01-01

    Three algorithms for determining gravity line (GL) location from center of pressure (COP) and horizontal force (Fx) recordings are suggested. The algorithms are designed to study upright standing posture and are based on the following premises: (a) the foot(feet) is a solid body and does not move, (b) the axis of rotation of the ankle joint does not displace, and

  13. Retraining Displaced Workers--Barriers and Facilitators.

    ERIC Educational Resources Information Center

    Wolansky, William D.

    Although plant closings and layoffs have been happening for a long time, today's recessions, major changes in the structure of the economy, and a tight job market have combined to make plant closings a more serious problem. Workers are faced with unemployment from both traditional labor-displacing changes, such as the increasing use of robotics;…

  14. Job Displacement and the Rural Worker.

    ERIC Educational Resources Information Center

    Podgursky, Michael

    High rates of unemployment in rural areas poses questions as what education can do with the problem. This report examines the effects of rural American economies as they grow away from agriculture and toward dependence on manufacturing and service industries. Using data from the federal Bureau of Labor Statistics' Displaced Worker Survey, the…

  15. A Personal Appearance Program for Displaced Homemakers.

    ERIC Educational Resources Information Center

    Fiore, Ann Marie; De Long, Marilyn Revell

    1990-01-01

    A career counseling program evaluated the self-esteem of 28 displaced homemakers, then presented 3 sessions on the importance of personal appearance in hiring practices, wardrobe management, nonverbal communication, professional image, and self-concept. Analysis of participant evaluations indicated improved levels of control and confidence and…

  16. Careers for Homemakers (A Displaced Homemakers Program).

    ERIC Educational Resources Information Center

    Hanks, Marlene

    St. Louis Community College's Careers for Homemakers program is a vocational counseling program designed to help displaced homemakers enter the job market for the first time or after a significant absence. The program's goal is to place participants, chosen according to academic or economic disadvantaged eligibility, in jobs consistent with their…

  17. A Mechanical Model of Neural Tissue Displacement During Lorentz Effect Imaging

    PubMed Central

    Roth, Bradley J.; Basser, Peter J.

    2009-01-01

    Song and co-workers recently proposed a method for MRI detection of biocurrents in nerves called “Lorentz Effect Imaging”. When exposed to a magnetic field, neural currents are subjected to a Lorentz force that moves the nerve. If the displacement is large enough, an artifact is predicted in the MR signal. In this paper, the displacement of a nerve of radius a in a surrounding tissue of radius b and shear modulus µ is analyzed. The nerve carries a current density J and lies in a magnetic field B. The solution to the resulting elasticity problem indicates that the nerve moves a distance BJ4?a2ln(ba). Using realistic parameters for a human median nerve in a 4 T field, this calculated displacement is 0.013 µm or less. The distribution of displacement is widespread throughout the tissue, and is not localized near the nerve. This displacement is orders of magnitude too small to be observed by conventional MRI methods. PMID:19097218

  18. Electromechanical displacement of piezoelectric-electrostrictive monolithic bilayer composites

    NASA Astrophysics Data System (ADS)

    Ngernchuklin, P.; Akdo?an, E. K.; Safari, A.; Jadidian, B.

    2009-02-01

    We examine the electromechanical displacement of piezoelectric-electrostrictive monolithic bilayer composites with various piezoelectric volume percentage obtained by cosintering piezoelectric 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 and electrostrictive 0.9Pb(Mg1/3Nb2/.3)O3-0.1PbTiO3 under unipolar and bipolar electric field excitation up to 10 kV/cm experimentally. It is shown that the effective d33 of the composites is limited by the electrostrictive layer, which acts as a capacitor in series to the piezoelectric layer, causing incomplete poling. We show that by controlling the volume content of the piezoelectric layer and constraining it with an electrostrictor, substantial strain amplification (15 ?m for bipolar excitation) can be achieved while inducing asymmetry to the displacement with respect to the polarity of the applied field, which we discuss in the context of symmetry superposition.

  19. Separation of magnetic field effects on the photoreduction of xanthone with p-aminothiophenol into the effects due to the ? and relaxation mechanisms

    NASA Astrophysics Data System (ADS)

    Wakasa, Masanobu; Sakaguchi, Yoshio; Hayashi, Hisaharu

    The inversion observed at 0·1 T for the magnetic field effects (MFEs) on the photoreduction of xanthone with p-aminothiophenol was investigated in the absence and the presence of a paramagnetic Gd3+ ion with the aid of a laser flash photolysis technique. The MFEs owing to the ?g and relaxation mechanisms were experimentally separated by the addition of Gd3+. Thus, we have proved for the present reaction that the MFEs owing to the hyperfine coupling mechanism and relaxation mechanism appear in a low field region (below 0·1 T) and that the MFEs owing to the ?g mechanism gradually appear in a high field region (above 0·1 T).

  20. A relativistic self-consistent model for studying enhancement of space charge limited field emission due to counter-streaming ions

    SciTech Connect

    Lin, M. C., E-mail: mingchiehlin@gmail.com; Lu, P. S. [NanoScience Simulation Laboratory, Fu Jen Catholic University, New Taipei City 24205, Taiwan (China) [NanoScience Simulation Laboratory, Fu Jen Catholic University, New Taipei City 24205, Taiwan (China); Plasma Theory and Simulation Group, Department of Nuclear Engineering, University of California, Berkeley, California 94720 (United States); Chang, P. C. [NanoScience Simulation Laboratory, Fu Jen Catholic University, New Taipei City 24205, Taiwan (China) [NanoScience Simulation Laboratory, Fu Jen Catholic University, New Taipei City 24205, Taiwan (China); Plasma Theory and Simulation Group, Department of Nuclear Engineering, University of California, Berkeley, California 94720 (United States); Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Ragan-Kelley, B. [Plasma Theory and Simulation Group, Department of Nuclear Engineering, University of California, Berkeley, California 94720 (United States) [Plasma Theory and Simulation Group, Department of Nuclear Engineering, University of California, Berkeley, California 94720 (United States); Applied Science and Technology, University of California, Berkeley, California 94720 (United States); Verboncoeur, J. P. [Plasma Theory and Simulation Group, Department of Nuclear Engineering, University of California, Berkeley, California 94720 (United States) [Plasma Theory and Simulation Group, Department of Nuclear Engineering, University of California, Berkeley, California 94720 (United States); Department of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan 48824 (United States)

    2014-02-15

    Recently, field emission has attracted increasing attention despite the practical limitation that field emitters operate below the Child-Langmuir space charge limit. By introducing counter-streaming ion flow to neutralize the electron charge density, the space charge limited field emission (SCLFE) current can be dramatically enhanced. In this work, we have developed a relativistic self-consistent model for studying the enhancement of SCLFE by a counter-streaming ion current. The maximum enhancement is found when the ion effect is saturated, as shown analytically. The solutions in non-relativistic, intermediate, and ultra-relativistic regimes are obtained and verified with 1-D particle-in-cell simulations. This self-consistent model is general and can also serve as a benchmark or comparison for verification of simulation codes, as well as extension to higher dimensions.

  1. Cross-sensor SAR image offsets for deriving coseismic displacements: Application to the 2001 Bhuj (India) earthquake using ERS and Envisat data

    NASA Astrophysics Data System (ADS)

    Wang, T.; Wei, S.; Jonsson, S.; Avouac, J. P.

    2014-12-01

    Synthetic Aperture Radar (SAR) is a powerful imaging technique for measuring ground deformation, either through Interferometric SAR (InSAR) or image offset tracking. However, these methods are only applied to SAR images acquired by the same satellite, which limits the measurement capability for many earthquakes. Here we propose a novel approach that allows for calculating offsets between images acquired from the European ERS and Envisat satellites. To achieve this cross-sensor offset calculation, we first coregister pre-event (ERS) and post-event (Envisat) SAR images separately to generate averaged pre- and post-event SAR amplitude maps. We then compute the orbital offsets between these two maps in order to resample the ERS average map onto the grid of the averaged Envisat image. We finally calculate the cross-sensor image offsets based on cross-correlating selected sub-images distributed throughout the coregistered averaged SAR maps. Application to the 2001 Bhuj earthquake reveals, for the first time, its near-field coseismic displacement field right above the epicenter. We compare our measurements with the surface displacement field predicted from the published source model of Copley et al. [2011]. This model was derived from tele-seismic waveforms and limited far-field geodetic data. The comparison between the two displacement maps shows consistent displacement patterns, yet a systematic shift, which likely is due to the limited near-fault resolution of the data used in the previous model. We then perform a joint inversion using the newly derived SAR image offsets and tele-seismic waveforms. The preferred source model suggests a compact slip pattern at depths of 20-30 km with a peak slip of ~10 meters and a fairly short rise time (<3s). The large slip rate and low attenuation in the crust are likely responsible for the widely felt ground shaking despite of its compact source area. The result demonstrates that it is possible to correlate non-coherent SAR images acquired by different sensors to measure surface displacements. This approach extends further the possibility of mining the archive of SAR images for various types of earth-science studies.

  2. Particle image velocimetry for the surface tension driven convection experiment using a particle displacement tracking technique

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P.; Pline, Alexander D.

    1991-01-01

    The Surface Tension Driven Convection Experiment (STDCE) is a Space Transportation System flight experiment to study both transient and steady thermocapillary fluid flows aboard the USML-1 Spacelab mission planned for 1992. One of the components of data collected during the experiment is a video record of the flow field. This qualitative data is then quantified using an all electronic, two-dimensional particle image velocimetry technique called particle displacement tracking (PDT) which uses a simple space domain particle tracking algorithm. The PDT system is successful in producing velocity vector fields from the raw video data. Application of the PDT technique to a sample data set yielded 1606 vectors in 30 seconds of processing time. A bottom viewing optical arrangement is used to image the illuminated plane, which causes keystone distortion in the final recorded image. A coordinate transformation was incorporated into the system software to correct this viewing angle distortion. PDT processing produced 1.8 percent false identifications, due to random particle locations. A highly successful routine for removing the false identifications was also incorporated, reducing the number of false identifications to 0.2 percent.

  3. Factors associated with the health status of internally displaced persons in northern Uganda

    Microsoft Academic Search

    B Roberts; K Felix Ocaka; J Browne; T Oyok; E Sondorp

    2009-01-01

    Background: Globally, there are over 24 million internally displaced persons (IDPs) who have fled their homes due to violence and insecurity but who remain within their own country. There have been up to 2 million IDPs in northern Uganda alone. The objective of this study was to investigate factors associated with mental and physical health status of IDPs in northern

  4. Weathering the Storm: Persistent Effects and Psychological First Aid with Children Displaced by Hurricane Katrina

    Microsoft Academic Search

    Daphne S. Cain; Carol A. Plummer; Rakinzie M. Fisher; Toni Q. Bankston

    2010-01-01

    There is a growing body of research on mental health outcomes among, and interventions with, children exposed to disaster. A recommended form of postdisaster intervention is psychological first aid (PFA). This research examines the use of a 6-week PFA group intervention among children ages 5 to 15 displaced due to Hurricane Katrina. Within 20 months post-Katrina, children participated in the

  5. Displaced Worker Transition Programs: Leading the Workforce Back to Community Colleges.

    ERIC Educational Resources Information Center

    Walters, Greg; And Others

    In response to the increasing numbers of displaced workers due to corporate downsizing, Pellissippi State Technical Community College, in Tennessee, has initiated the Workplace Innovation (WIN) Project to help adults gain prerequisite academic and personal skills to re-enter the workforce or enter college for eventual placement in higher-paying…

  6. Recording of In-plane Surface Displacement by Double-exposure Speckle Photography

    Microsoft Academic Search

    E. Archbold; J. M. Burch; A. E. Ennos

    1970-01-01

    Local displacements in the plane of an object surface illuminated by coherent light may be measured by recording double-exposure photographs of it. When the surface is illuminated symmetrically by two oblique beams, ‘speckle correlation fringes’ appear in the doubly exposed negative, due to the non-linear nature of the photographic recording. Factors affecting the visibility of these fringes and the range

  7. Unsupervised Adaptation to On-body Sensor Displacement in Acceleration-Based Activity Recognition

    Microsoft Academic Search

    Hamidreza Bayati; Jose del R. Mill´n; Ricardo Chavarriaga

    2011-01-01

    A common assumption in activity recognition is that the system remain unchanged between its design and its posterior operation. However, many factors can affect the data distribution between two different experimental sessions including sensor displacement (e.g. due to replacement or slippage), and lead to changes in the classification performance. We propose an unsupervised adaptive classifier that calibrates itself to be

  8. Lasing from the domain of collision of ionisation waves produced due to electric field concentration at electrodes with a small radius of curvature

    SciTech Connect

    Tarasenko, Viktor F; Tel'minov, A E; Burachenko, A G; Rybka, D V; Baksht, E Kh; Lomaev, Mikhail I; Panchenko, Aleksei N; Vil'tovskii, P O [Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, Tomsk (Russian Federation)

    2011-12-31

    The characteristics of UV lasing in nitrogen and of diffusive discharge produced without an additional ionisation source were experimentally investigated in a nonuniform electric field formed by electrodes with different profiles. High-voltage nanosecond pulses were applied to the blade- and cylinder-shaped electrodes. It was determined that the gap breakdown at elevated pressure was caused by diffusive jets which propagate from the electrodes with a small radius of curvature. The electric field increased in the intersection of counter-propagating jets, with the effect that the threshold of lasing in the C{sup 3}{Pi}{sub u} - B{sup 3}{Pi}{sub g} ({lambda} = 337.1 nm) molecular nitrogen band was attained for low average electric fields (below 60 V cm{sup -1} Torr{sup -1}) and at pressures of 760 Torr and above. With lowering the pressure from 760 to 20 Torr, the voltage of gap breakdown in the nonuniform electric field was observed to increase for a voltage pulse rise time of {approx}300 ps and to decrease for a pulse rise time of {approx}2 ns.

  9. Three-dimensional optimal shape design of magnetic pole in permanent magnet assembly for MRI taking account of eddy currents due to gradient coil field

    Microsoft Academic Search

    Yingying Yao; Chang Seop Koh; Dexin Xie

    2004-01-01

    The ferromagnetic pole pieces of permanent magnet assembly for magnetic resonance imaging is optimally designed taking account of the pulse excited gradient coil field. In the design, the transient design sensitivity analysis is combined with the three-dimensional finite element method to give a search direction. The effects of the eddy currents, induced on the ferromagnetic pole pieces, on the main

  10. Coupled thermo-mechanical simulations of shot impacts: Effects of the temperature on the residual stress field due to shot-peening

    Microsoft Academic Search

    Sébastien Rouquette; Emmanuelle Rouhaud; Manuel François; Arjen Roos; Jean-Louis Chaboche

    2009-01-01

    Shot-peening is an industrial surface treatment used to improve fatigue life of mechanical components. This process generates a compressive residual stress field on the part's surface and offers a protection against crack initiation and propagation, corrosion, etc. Although the consequences of the process on fatigue life are well known, the physical influence of the relevant parameters is not fully understood.

  11. Publication List for Robert L. Lysak Hudson, M. K., F. S. Mozer, and R. L. Lysak, Magnetic field-aligned potential drops due to

    E-print Network

    Lysak, Bob

    ., J. F. Fennell, D. R. Croley, A. L. Vampola, F. S. Mozer, R. B. Torbert, M. Temerin, R. L. Lysak, MPublication List for Robert L. Lysak Hudson, M. K., F. S. Mozer, and R. L. Lysak, Magnetic field. A., R. L. Lysak, R. B. Torbert, and F. S. Mozer, Observations of differences between regions

  12. A reverse updated Lagrangian finite element formulation for determining material properties from measured force and displacement data

    NASA Astrophysics Data System (ADS)

    Tartibi, M.; Steigmann, D. J.; Komvopoulos, K.

    2014-12-01

    The mechanical response of solids exhibiting complex material behavior has traditionally been determined by fitting constitutive models of specified functional form to experimentally derived force-displacement (stress-strain) data. However, characterizing the nonlinear mechanical behavior of complex materials requires a method of quantifying material behavior that is not restricted by a specific constitutive relation. To this end, a new method, termed the reverse updated Lagrangian finite element method (RULFEM), which is based on the three-dimensional displacement field of the deformed solid and the finite element method, is developed for incrementally linear materials. Using the RULEFM, the body is discretized by finite elements and its material properties are determined element-wise, i.e., the properties are assumed to be uniform at the element level and may vary from one element to another. The validity of RULFEM is demonstrated by three noise-free numerical examples and three numerical examples with various input noise levels. Two methods to assess the global and local errors of the results due to error in the measured input data (noisy data) are also discussed.

  13. Seismic Amplifications due to Topographic Effects in the North of Chile Coastal Scarp

    NASA Astrophysics Data System (ADS)

    García, T. C.; Maringue, J.; Hurtado, D.; Yanez, G. A.

    2014-12-01

    The coastal scarp of the North of Chile is an important geomorphological feature, parallel to the oceanic trench. During the Mw 8.2 Pisagua earthquake, site effects were registered in the Alto Hospicio, Huara and Pozo Almonte councils, all locations placed above the high cliff. The observed site effects were not predicted by a previous seismic microzonation of the study area. The topographic effects due to the loss of soil confinement in the west edge of the scarp could be responsible of the seismic amplification registered. In this work, a 2-D implicit Galerkin finite element model was constructed to estimate the effect of the seismic waves on the displacements experienced by the coastal scarp geometry. Our results indicate that vertical amplifications of the seismic waves are observed in the surface and in the scarp slope, with a range of influence from the edge of one hundred meters eastward, approximately. The displacement field found using this model is similar to the measurement made by GPS during coseismic displacement of typical subduction earthquakes. However, changes in the geometry of the finite element have a similar effect in the vertical displacement's magnitude. The model presented is, to the best of our knowledge, the first approximation to resolve the topographic effects in the seismic amplifications due the coastal scarp geometry in the andes?, where many assumptions have been used in order to simplify the results. In order to improve our results, further improvements to the model will be developed in the future, as the inclusion of relevant geological features.

  14. Fast generation of an inward electric field due to ion orbit losses in the tokamak edge plasma during transition from low-to-high confinement

    NASA Astrophysics Data System (ADS)

    Wu, G. J.; Zhang, X. D.; Li, Y. D.; Sun, P. J.; Cao, G. M.

    2014-08-01

    The formation of radial electric field Er in the tokamak edge region is calculated based on the collisionless ion orbit loss. The ion orbit loss generates a negative Er, which in turn affects the ion loss. As a result, Er can saturate at either a low or a high value, depending on the plasma parameters. When the ion temperature in the plasma edge is higher than a threshold, a self-sustaining growth in both ion loss and Er is found, leading to a high saturation value of Er in milliseconds. This mechanism provides a possible explanation for the formation of a strong radial electric field during the transition from the low (L) to the high (H) confinement regime observed in tokamak edge plasmas.

  15. Theoretical Limits on the Threshold for the Response of Long Cells to Weak Extremely Low Frequency Electric Fields Due to Ionic and Molecular Flux Rectification

    Microsoft Academic Search

    James C. Weaver; Timothy E. Vaughan; Robert K. Adair; R. Dean Astumian

    1998-01-01

    Understanding exposure thresholds for the response of biological systems to extremely low frequency (ELF) electric and magnetic fields is a fundamental problem of long-standing interest. We consider a two-state model for voltage-gated channels in the membrane of an isolated elongated cell (Lcell=1mm; rcell=25?m) and use a previously described process of ionic and molecular flux rectification to set lower bounds for

  16. Asymmetric signal intensity in normal collateral ligaments of the distal interphalangeal joint in horses with a low-field MRI system due to the magic angle effect.

    PubMed

    Spriet, Mathieu; Mai, Wilfried; McKnight, Alexia

    2007-01-01

    Increased signal intensity in one of the collateral ligaments of the distal interphalangeal (DIP) joint of sound horses in images acquired using a low-field magnet with vertical orientation of the magnetic field was investigated as a possible manifestation of the magic angle effect. Three isolated equine digits were imaged using the following pulse sequences: (1) spin echo TI, (2) turbo spin echo proton density and T2, and (3) 3D gradient echo T1, in different positions by mildly changing the orientation of the long axis of the digit, in the dorsal plane, relative to the magnetic field. The signal intensity in a ligament was significantly increased when the ligament orientation relative to the magnetic field was 55 +/- 10 degrees. The signal intensity was markedly increased in pulse sequences with short echo time (TE) 5.0, 4.9, and 3.9 times increased, respectively, for 3D gradient echo T1, spin echo T1, and turbo spin echo proton density) and to a lesser extent with pulse sequences with a longer TE (1.8 times increased for turbo spin echo T2). These changes are characteristic of the magic angle effect. Because of the anatomic orientation of the collateral ligaments of the DIP joint, a slight deviation of the long axis of the digit in the dorsal plane, from the ideal horizontal position, will induce an increased signal intensity that can be confused with desmitis. Careful positioning of the foot in magnetic resonance imaging systems where B0 is perpendicular to the long axis of the digit is critical to prevent the occurrence of the magic angle effect. PMID:17385363

  17. Wettability Control on Fluid-Fluid Displacements in Patterned Microfluidics

    NASA Astrophysics Data System (ADS)

    Zhao, B.; Trojer, M.; Cueto-Felgueroso, L.; Juanes, R.

    2014-12-01

    Two-phase flow in porous media is important in many natural and industrial processes like geologic CO2 sequestration, enhanced oil recovery, and water infiltration in soil. While it is well known that the wetting properties of porous media can vary drastically depending on the type of media and the pore fluids, the effect of wettability on fluid displacement continues to challenge our microscopic and macroscopic descriptions. Here we study this problem experimentally, starting with the classic experiment of two-phase flow in a capillary tube. We image the shape of the meniscus and measure the associated capillary pressure for a wide range of capillary numbers. We confirm that wettability exerts a fundamental control on meniscus deformation, and synthesize new observations on the dependence of the dynamic capillary pressure on wetting properties (contact angle) and flow conditions (viscosity contrast and capillary number). We compare our experiments to a macroscopic phase-field model of two-phase flow. We use the insights gained from the capillary tube experiments to explore the viscous fingering instability in the Hele-Shaw geometry in the partial-wetting regime. A key difference between a Hele-Shaw cell and a porous medium is the existence of micro-structures (i.e. pores and pore throats). To investigate how these micro-structrues impact fluid-fluid displacement, we conduct experiments on a planar microfluidic device patterned with vertical posts. We track the evolution of the fluid-fluid interface and elucidate the impact of wetting on the cooperative nature of fluid displacement during pore invasion events. We use the insights gained from the capillary tube and patterned microfluidics experiments to elucidate the effect of wetting properties on viscous fingering and capillary fingering in a Hele-Shaw cell filled with glass beads, where we observe a contact-angle-dependent stabilizing behavior for the emerging flow instabilities, as the system transitions from drainage to imbibition.

  18. Full exploitation of surface displacement time series retrieved from the phase and the amplitude of a SAR dataset: the Galápagos Islands case study

    NASA Astrophysics Data System (ADS)

    Manconi, A.; Casu, F.

    2011-12-01

    In the last years, space-borne Differential SAR Interferometry (DInSAR) played a key role in the analysis of surface displacements over seismogenic and active volcanic areas. DInSAR exploits the phase difference between data pairs acquired over the same area before and after a deformation event, and allows generating spatially dense surface displacement maps. In addition, by means of advanced DInSAR processing techniques it is possible to pass from a static representation of the deformation field to its dynamic characterization via surface displacement time series. In this context, a well-established approach is the Small BAseline Subset (SBAS) algorithm, which relies on an appropriate selection of the SAR image pairs and achieves accuracies in the order of ca. 1 mm/year for mean surface deformation velocities and ca. 5 mm for surface displacement time series. However, in areas characterized by large and/or rapid deformation events, the exploitation of the phase information from SAR images might be prevented due to high fringe rates and/or loss of the signal coherence (mainly due to misregistration errors). In these cases, displacements can be still retrieved by measuring the distortion of the scene as observed in the SAR image amplitude, also known as feature-tracking or pixel-offset (PO) techniques. Recently, a novel algorithm has been presented which, starting from the PO measurements and following the same rationale of the SBAS technique, permits generating surface displacement time series also in areas characterized by large deformation dynamics. The algorithm combining both the PO and the SBAS capabilities is referred to as PO-SBAS, and the estimated accuracies achievable with this method are in the order of 1/30th of a pixel. In addition, PO-SBAS permits also retrieving the displacement time series along the azimuth direction (mostly North-South), thus increasing the information achievable from a single SAR dataset. In this work, we fully exploit the information contained in a dataset of 25 SAR images acquired by ENVISAT satellite over the Galápagos Islands between 2003 and 2007. By applying both the SBAS ad the PO-SBAS techniques, we retrieved spatially and temporally dense surface displacement time series from the phase and the amplitude information. We studied the evolution of the volcanic sources responsible for two large and destructive eruptive events: the first one occurred at Fernandina volcano (May 13, 2005) and the second at Sierra Negra caldera (October 22, 2005). To constrain the volcanic source parameters, we first model separately the displacement time series retrieved from phase and the amplitude information, respectively. Secondly, we jointly invert the SBAS and the PO-SBAS time series in order to understand the impact of using both data on the spatial and temporal characterization of the volcanic source.

  19. A novel wide measuring range FBG displacement sensor with variable measurement precision based on helical bevel gear

    NASA Astrophysics Data System (ADS)

    Jiang, Shan-chao; Wang, Jing; Sui, Qing-mei; Cao, Yu-qiang

    2015-03-01

    A novel fiber Bragg grating (FBG) displacement sensor is proposed, which can achieve wide measuring range displacement detection with variable measurement precision due to its mechanical transfer structure of helical bevel gear. A prototype is designed and fabricated. The maximum detection displacement of this prototype is 1.751 m, and the precision grade changes from 0.2% to 6.7%. Through analyzing the experiment data which is obtained in the calibration experiment, the measuring range of this sensor is from 0 m to 1.532 m, and the wavelength shift errors between experiment data and theory calculation are all less than 5%.

  20. Reliable Estimation of Dense Optical Flow Fields with Large Displacements

    Microsoft Academic Search

    Luis Alvarez; Joachim Weickert; Javier Sánchez

    2000-01-01

    In this paper we show that a classic optical flow technique by Nagel and Enkelmann (1986, IEEE Trans. Pattern Anal. Mach. Intell., Vol. 8, pp. 565–593) can be regarded as an early anisotropic diffusion method with a diffusion tensor. We introduce three improvements into the model formulation that (i) avoid inconsistencies caused by centering the brightness term and the smoothness

  1. Crack border stress and displacement equations revisited

    NASA Technical Reports Server (NTRS)

    Eftis, J.; Subramonian, N.; Liebowitz, H.

    1977-01-01

    It is more or less accepted in fracture mechanics that the elastic stress and displacements very near to the tip of a plane line crack can be approximated with sufficient accuracy, for all geometries and outer boundary loading conditions, by a one-parameter representation, i.e., strictly in terms of the stress intensity factors KI and/or KII. It is shown here that this presumption which appears to be reasonable on face value, quantitatively speaking, is nevertheless unacceptable as a general proposition. The reason lies with the quite arbitrary practice of omitting the second term of the series representation for the stresses, a contribution which is independent of distance from the crack tip. It is not difficult to show by way of specific examples how such omission can lead to error of serious qualitative nature in the prediction of stress and displacement related quantities of interest.

  2. Character displacement of Cercopithecini primate visual signals

    PubMed Central

    Allen, William L.; Stevens, Martin; Higham, James P.

    2014-01-01

    Animal visual signals have the potential to act as an isolating barrier to prevent interbreeding of populations through a role in species recognition. Within communities of competing species, species recognition signals are predicted to undergo character displacement, becoming more visually distinctive from each other, however this pattern has rarely been identified. Using computational face recognition algorithms to model primate face processing, we demonstrate that the face patterns of guenons (tribe: Cercopithecini) have evolved under selection to become more visually distinctive from those of other guenon species with whom they are sympatric. The relationship between the appearances of sympatric species suggests that distinguishing conspecifics from other guenon species has been a major driver of diversification in guenon face appearance. Visual signals that have undergone character displacement may have had an important role in the tribe’s radiation, keeping populations that became geographically separated reproductively isolated on secondary contact. PMID:24967517

  3. Magnetic field effects on the vestibular system: calculation of the pressure on the cupula due to ionic current-induced Lorentz force

    NASA Astrophysics Data System (ADS)

    Antunes, A.; Glover, P. M.; Li, Y.; Mian, O. S.; Day, B. L.

    2012-07-01

    Large static magnetic fields may be employed in magnetic resonance imaging (MRI). At high magnetic field strengths (usually from about 3 T and above) it is possible for humans to perceive a number of effects. One such effect is mild vertigo. Recently, Roberts et al (2011 Current Biology 21 1635-40) proposed a Lorentz-force mechanism resulting from the ionic currents occurring naturally in the endolymph of the vestibular system. In the present work a more detailed calculation of the forces and resulting pressures in the vestibular system is carried out using a numerical model. Firstly, realistic 3D finite element conductivity and fluid maps of the utricle and a single semi-circular canal containing the current sources (dark cells) and sinks (hair cells) of the utricle and ampulla were constructed. Secondly, the electrical current densities in the fluid are calculated. Thirdly, the developed Lorentz force is used directly in the Navier-Stokes equation and the trans-cupular pressure is computed. Since the driving force field is relatively large in comparison with the advective acceleration, we demonstrate that it is possible to perform an approximation in the Navier-Stokes equations that reduces the problem to solving a simpler Poisson equation. This simplification allows rapid and easy calculation for many different directions of applied magnetic field. At 7 T a maximum cupula pressure difference of 1.6 mPa was calculated for the combined ampullar (0.7 µA) and utricular (3.31 µA) distributed current sources, assuming a hair-cell resting current of 100 pA per unit. These pressure values are up to an order of magnitude lower than those proposed by Roberts et al using a simplistic model and calculation, and are in good agreement with the estimated pressure values for nystagmus velocities in caloric experiments. This modeling work supports the hypothesis that the Lorentz force mechanism is a significant contributor to the perception of magnetic field induced vertigo.

  4. FPGA implementation of 3D-displacement measurement based on 2D-DIC and FPP

    NASA Astrophysics Data System (ADS)

    Lei, Zhenkun; Zhang, Fangxu; Li, Xuan

    2014-07-01

    Nondestructive optical techniques have been widely used to satisfy engineering applicat ion. 2D digital image correlation (DIC) method has superiority of convenient manipulation and high accuracy in measuring planar displacement. Moreover, fringe pattern profilometry (FPP) method has become a highly developed technique to measure surface profile. Combined with 2D-DIC method, FPP method can be applied to measure three-dimensional displacements conveniently. As a semi-custom integrated circuit, Field-Programmable Gate Array (FPGA) has been popular for its powerful programming performance on controlling experimental instrument. Furthermore, Labview, an efficient graphical programming language which excels in instrument communication, can be used to program FPGA. In this paper, a corrected dynamic FPP method combined with 2D-DIC method has been presented and achieved by Labview programming to measure dynamic deformation. An experimental system including a projector and a camera is used to project fringe patterns and acquire images alternately at a high speed. By the referred method a series of spatial-discrete displacement data in equal intervals of time are obtained. Then a four-dimensional interpolation is adopted to get full-field and continuous-time displacement data. Thus, the planar and out-plane displacements can be simultaneously measured. Experiments were performed and verified the feasibility of proposed method.

  5. Optoelectronic Displacement Measurement Method for Rotating Disks

    Microsoft Academic Search

    C. E. Bakis; B. J. Haldeman; R. P. Emerson

    Radial displacements on an axial surface of a rotating disk can be measured with optoelectronic sensing devices consisting\\u000a of infrared emitters and phototransistors. The aim of this investigation is to improve the stability and robustness of a previously\\u000a described optoelectronic measurement system. Stability is improved by a computerized algorithm for the control of the emitter\\u000a intensity based on feedback from

  6. Coreflood experimental study of steam displacement 

    E-print Network

    Cerutti, Andres Enrique

    1997-01-01

    COREFLOOD EXPERIMENTAL STUDY OF STEAM DISPI ACEMENT A Thesis by ANDRE S ENRIQUE CERUTTI Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE... December 1997 Major Subject: Petroleum Engineering COREFLOOD EXPERIMENTAL STUDY OF STEAM DISPLACEMENT A Thesis by ANDRES ENRIQUE CERUTTI Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment of the requirements...

  7. Fiber Optic Sensing System Measures Small Displacements

    NASA Technical Reports Server (NTRS)

    Adamovsky, Grigory

    1994-01-01

    Fiber optic sensing system measures small changes in intensity of light propagating through its interferometric sensing head. Quantity determined using this approach is displacement or any other phenomenon that affects intensity of light. Sensing scheme involves imbalanced fiber optic interferometer as sensing head and amplitude modulation and detection at two radio frequencies. One important advantage over prior fiber sensors involving pulse-amplitude modulation is length of imbalance shorter.

  8. Effects of Young's modulus on fault displacement

    Microsoft Academic Search

    Agust Gudmundsson

    2004-01-01

    Elastic crack models predict a linear relationship between displacement (u) and rupture (trace) length (L) during slip in a fault zone. Attempts to find universal-scaling laws for L\\/u, however, have generally failed. Here I propose that these attempts have failed because they do not take into account the changes in the mechanical properties, in particular Young's modulus (stiffness), of the fault

  9. Road displacement model based on structural mechanics

    NASA Astrophysics Data System (ADS)

    Lu, Xiuqin; Guo, Qingsheng; Zhang, Yi

    2006-10-01

    Spatial conflict resolution is an important part of cartographic generalization, and it can deal with the problems of having too much information competing for too little space, while feature displacement is a primary operator of map generalization, which aims at resolving the spatial conflicts between neighbor objects especially road features. Considering the road object, this paper explains an idea of displacement based on structural mechanics. In view of spatial conflict problem after road symbolization, it is the buffer zones that are used to detect conflicts, then we focus on each conflicting region, with the finite element method, taking every triangular element for analysis, listing stiffness matrix, gathering system equations and calculating with iteration strategy, and we give the solution to road symbol conflicts. Being like this until all the conflicts in conflicting regions are solved, then we take the whole map into consideration again, conflicts are detected by reusing the buffer zones and solved by displacement operator, so as to all of them are handled.

  10. Simultaneous muscle force and displacement transducer

    NASA Technical Reports Server (NTRS)

    Feldstein, C.; Lewis, G. W.; Culler, V. H. (inventors)

    1980-01-01

    A myocardial transducer for simultaneously measuring force and displacement within a very small area of myocardium is disclosed. The transducer comprised of an elongated body forked at one end to form an inverted Y shaped beam with each branch of the beam constituting a low compliant tine for penetrating the myocardium to a predetermined depth. Bonded to one of the low compliance tines is a small piezoresistive element for converting a force acting on the beam into an electrical signal. A third high compliant tine of the transducer, which measures displacement of the myocardium in a direction in line with the two low compliant tines, is of a length that just pierces the surface membrane. A small piezoresistive element is bonded to the third tine at its upper end where its bending is greatest. Displacement of the myocardium causes a deformation in curvature of the third tine, and the second small piezoresistive element bonded to the surface of its curved end converts its deformation into an electrical signal.

  11. 46 CFR 153.966 - Discharge by liquid displacement.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 2010-10-01 false Discharge by liquid displacement. 153.966 Section 153...DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS...Procedures § 153.966 Discharge by liquid displacement. The person in...

  12. 46 CFR 153.966 - Discharge by liquid displacement.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 2011-10-01 false Discharge by liquid displacement. 153.966 Section 153...DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS...Procedures § 153.966 Discharge by liquid displacement. The person in...

  13. Calculation of THz radiation due to coherent polar-phonon oscillations in p i n diode structure at high electric field

    NASA Astrophysics Data System (ADS)

    Thao, D. N.; Katayama, S.; Khoa, T. D.; Iida, M.

    2004-04-01

    We present a calculation of terahertz (THz) radiation by coherent optical phonons in GaAs p-i-n diode structure under high electric fields. The ultrafast dynamics of photoexcited carriers is simulated by adopting a self-consistent ensemble Monte Carlo method. It is demonstrated that the coherent phonon oscillations emitting the THz radiation are excited resonantly by synchronization between the proper lattice oscillation and ultrafast transient of electronic polarization originating from a drift overshoot within the initial period of lattice vibration.

  14. Autonomous mobile robot with displacements in a vertical plane and applications in cleaning services

    Microsoft Academic Search

    N. Alexandrescu; T. C. Apostolescu; C. Udrea; D. Duminica?; L. A. Cartal

    2010-01-01

    Robotic systems have lead to important progress in the vast field of automation. Even if industrial robots prevailed initially, service robots intended to perform various activities, including domestic tasks, have brought a substantial contribution in the latest two decades. Autonomous mobile robots used for vertical surface cleaning involve the most complex mechanical structures from the point of view of displacement

  15. Digital PIV Measurements of Acoustic Particle Displacements in a Normal Incidence Impedance Tube

    NASA Technical Reports Server (NTRS)

    Humphreys, William M., Jr.; Bartram, Scott M.; Parrott, Tony L.; Jones, Michael G.

    1998-01-01

    Acoustic particle displacements and velocities inside a normal incidence impedance tube have been successfully measured for a variety of pure tone sound fields using Digital Particle Image Velocimetry (DPIV). The DPIV system utilized two 600-mj Nd:YAG lasers to generate a double-pulsed light sheet synchronized with the sound field and used to illuminate a portion of the oscillatory flow inside the tube. A high resolution (1320 x 1035 pixel), 8-bit camera was used to capture double-exposed images of 2.7-micron hollow silicon dioxide tracer particles inside the tube. Classical spatial autocorrelation analysis techniques were used to ascertain the acoustic particle displacements and associated velocities for various sound field intensities and frequencies. The results show that particle displacements spanning a range of 1-60 microns can be measured for incident sound pressure levels of 100-130 dB and for frequencies spanning 500-1000 Hz. The ability to resolve 1 micron particle displacements at sound pressure levels in the 100 dB range allows the use of DPIV systems for measurement of sound fields at much lower sound pressure levels than had been previously possible. Representative impedance tube data as well as an uncertainty analysis for the measurements are presented.

  16. Lubricant film thickness measurement using fiber-optic Michelson interferometer and fiber-optic displacement sensor

    Microsoft Academic Search

    Yuping Chen; Xiaodong Zhang; Ping Zhang; Chunxiang Liu

    2009-01-01

    How to accurately measure the lubricant film thickness of the hydrodynamic slide bearings has been an important research field in the condition monitor and fault diagnosis of large rotary machinery. This paper focus on a new detection approach using a fiber-optical Michelson Interferometer combined with a fiber-optical displacement sensor for the lubricant film thickness measurement. After introducing the fundamental principle,

  17. Collateral damage: Evolution with displacement of fracture distribution and secondary fault strands in fault

    E-print Network

    Savage, Heather M.

    Collateral damage: Evolution with displacement of fracture distribution and secondary fault strands in fault damage zones Heather M. Savage1,2 and Emily E. Brodsky1 Received 22 April 2010; revised 10 faults is governed by the same process. Based on our own field work combined with data from

  18. Calculation of the Displacement Current Using the Integral Form of Ampere's Law.

    ERIC Educational Resources Information Center

    Dahm, A. J.

    1978-01-01

    Derives the magnetic field as a function of position between two capacitor plates during discharge with the use of the integral form of Ampere's law and real currents only. The displacement current must be included to obtain the same result for arbitrary choices of contours. (Author/GA)

  19. Male-Female Differences in Predicting Displaced Volume: Strategy Usage, Aptitude Relationships, and Experience Influences.

    ERIC Educational Resources Information Center

    Linn, Marcia C.; Pulos, Steven

    1983-01-01

    Gender differences in predicting displaced volume did not reflect gender differences in spatial ability, field-dependence-independence, or Piagetian formal reasoning. In addition, gender differences were not accounted for by science and math course-taking experience. (Author/PN)

  20. Miscible displacement of viscous, non-Newtonian fluids in different geometries. An analytical approach

    Microsoft Academic Search

    R. M. Beirute

    1977-01-01

    Solutions are given for the displacement occurring between parallel plates and in tubes under conditions of constant flow rate. For tubes, a solution is also given for the case when a constant pressure drop is imposed across the flow field. The analytical approach used relied on principles from the hydrodynamic theory of lubrication. The results showed that the process was