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1

Role of plasma response in displacements of the tokamak edge due to applied non-axisymmetric fields  

SciTech Connect

Linear, two-fluid, resistive modelling of the plasma response to applied non-axisymmetric fields shows significant displacement of edge temperature and density profiles. The calculated displacements, often of 2 cm or more in H-mode pedestals with parameters appropriate to DIII-D, are due to the helical distortions resulting from stable edge modes being driven to finite amplitude by the applied fields. In many cases, these displacements are greater in magnitude, and different in phase, than the distortions of the separatrix manifolds predicted from vacuum modelling. Comparison of these results with experimental measurements from Thomson scattering and soft x-ray imaging finds good quantitative agreement. In these experiments, the phase of the applied non-axisymmetric magnetic field was flipped or rotated in order to probe the non-axisymmetric features of the response. The poloidal structures measured by x-ray imaging show clear indications of a helical response, as opposed to simply a change in the axisymmetric transport. Inclusion of two-fluid effects and rotation are found to be important in obtaining quantitative agreement with Thomson scattering data. Modelling shows screening of islands in the H-mode pedestal, but island penetration near the top of the pedestal where the electron rotation vanishes in plasmas with co-current rotation. Enhanced transport due to these islands may provide a mechanism for maintaining the pedestal width below the stability threshold of edge-localized modes. For typical DIII-D parameters, it is shown that the linear approximation is often near or beyond the limit of validity in the H-mode edge; however, the general agreement with experimental measurements indicates that these linear results nevertheless maintain good predictive value for profile displacements.

Evans, T. E. [General Atomics, San Diego; Ferraro, N. M. [General Atomics, San Diego; Orlov, D. M. [University of California, San Diego & La Jolla; Wade, M. [General Atomics, San Diego; Lao, L. L. [General Atomics, San Diego; Moyer, R. A. [University of California, San Diego; Wingen, A. [University of Dusseldorf, Germany; Nazikian, R. [Princeton Plasma Physics Laboratory (PPPL); Unterberg, Ezekial A [ORNL; Shafer, Morgan W [ORNL

2013-01-01

2

Crustal Displacements Due to Continental Water Loading  

NASA Technical Reports Server (NTRS)

The effects of long-wavelength (> 100 km), seasonal variability in continental water storage on vertical crustal motions are assessed. The modeled vertical displacements (delta-r(sub M)) 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 delta-r(sub M) with observed Global Positioning System (GPS) heights (delta-r(sub O)) (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 delta-r(sub O) time series are adjusted by delta-r(sub M), their variances are reduced, on average, by an amount equal to the variance of the delta-r(sub M). Of the delta-r(sub O) 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 delta-r(sub M). The delta-r(sub M) 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.

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

2001-01-01

3

Displacement-sensitive organic field effect transistor  

Microsoft Academic Search

Thin films of organic semiconductor copper phthalocynanine (CuPc) and Al were deposited in sequence by vacuum evaporation on a glass substrate with Ag source and drain electrodes. The effect of displacement on the properties of the fabricated field effect transistor with metal (aluminium)–semiconductor (copper phthalocyanine) Schottky junction was investigated. It was observed that the drain–source resistance of this organic field

Kh. S. Karimov; M. Saleem; M. Mahroof-Tahir; T. A. Qasuria; Adam Khan; T. A. Khan

2011-01-01

4

Displacement-sensitive organic field effect transistor  

Microsoft Academic Search

Thin films of organic semiconductor copper phthalocynanine (CuPc) and Al were deposited in sequence by vacuum evaporation on a glass substrate with Ag source and drain electrodes. The effect of displacement on the properties of the fabricated field effect transistor with metal (aluminium)–semiconductor (copper phthalocyanine) Schottky junction was investigated. It was observed that the drain–source resistance of this organic field

Kh. S. Karimov; M. Saleem; M. Mahroof-Tahir; T. A. Qasuria; Adam Khan; T. A. Khan

2012-01-01

5

Mass Spectrometer Image Displacements due to Second-Order Aberrations  

Microsoft Academic Search

Second-order aberrations in mass spectrometers give rise to image broadening which is generally unsymmetrical about the optic axis, resulting in a net displacement of the image center from the optic axis. The net displacement depends on the properties of the mass resolving system and on the velocity and angular distribution in the ion beam. In the event different ionic species

Charles F. Robinson

1958-01-01

6

Mass Spectrometer Image Displacements due to Second-Order Aberrations  

Microsoft Academic Search

Second-order aberrations in mass spectrometers give rise to image ; broadening which is generally unsymmetrical about the optic axis, resulting in a ; net displacement of the image center from the optic axis. The net displacement ; depends on the properties of the mass resolving system and on the velocity and ; angular distribution in the ion beam. In the

Charles F. Robinson

1958-01-01

7

BLOCK DISPLACEMENT METHOD FIELD DEMONSTRATION AND SPECIFICATIONS  

EPA Science Inventory

The Block Displacement technique has been developed as a remedial action method for isolating large tracks of ground contaminated by hazardous waste. The technique places a low permeability barrier around and under a large block of contaminated earth. The Block Displacement proce...

8

A regularized finite-element digital image correlation for irregular displacement field  

NASA Astrophysics Data System (ADS)

A nonlinear Tikhonov regularization scheme is developed to tackle the ill-posed finite-element digital image correlation, which aims to measure the displacement field from consequent digital images before and after deformation. The goal of this algorithm is to resolve the displacement field with fine and irregular structure without deteriorated by the measuring errors due to its ill-posedness. A Newton-type method is employed to linearize the nonlinear problem iteratively, then the Tikhonov regularization is applied to the linearized problem, with the regularization parameter adaptively chosen by the L-curve method. The proposed algorithm is verified by computer simulated input images with a priori displacement field. The result shows that it is capable of resolving displacement field with very fine structure in a reasonable accuracy.

Yang, Reng-cai

2014-05-01

9

Mechanoreceptors for near-field water displacements in crayfish.  

PubMed

1. Mechanosensory hairs on the surface of the crayfish telson are dually innervated, one sensory cell responding to headward, the other to tailward deflection of the hair. The average conduction velocity of headward elements was 0.8 m/s (variance 0.08) and of tailward elements 1.2 m/s (variance 0.19). In a frequency range from 0.05 to 200 Hz, thresholds were lowest near 20 Hz: 0.08 mum (pp) for headward-sensitive and 0.1 mum (pp) for tailward-sensitive cells. 2. The receptors are displacement sensitive since thresholds are of the same order of magnitude over the frequency range 1-70 Hz when the hair is moved by a vibrating wire loop. With natural stimuli (surface waves), the velocity component of the particle movement (and consequently force) becomes influential. The coding of a broad range of stimulus intensities is aided by variations in mechanical properties of the hair. 3. Marked directionality (better than 4:1), in addition to the dual innervation, enhances vector detection. At least part of this characteristic stems from the hingelike articulation of the hair on the body surface: the hair can be moved easily 40 degrees tailward and 20 degrees headward, but must be forced in the orthogonal direction. Morphological studies indicate the presence of a double pivoted hinge, with rigid guides for movement of the hair shaft. Preliminary results of electron microscope examination show a clearly polarized arrangement of densely packed microtubules in the two dendrites; they appear interconnected in groups of two and three along a line parallel to the sensitivity plane of the receptor. 4. The 50-fold threshold difference between the results of behavioral experiments in lobsters (24) and the data for the individual receptors reported here may be due to improvement in signal-to-noise ratio by central nervous averaging of the input from an estimated 2 X 10(3) receptors (Procambarus), and/or to the kind of threshold criteria applied to individual receptor thresholds. As would be expected (35), the sensory cells of each directional class synapse with separate interneurons: in this way, the organism might employ differential microphones to reduce background noise. 5. The receptors are analogous to those of the lateral-line system in lower vertebrates in having receptors with sensitivities polarized by 180 degrees. These similarities suggest that in both cases monitoring of near field water displacements has proved in essential way of orienting in opaque waters. PMID:966040

Wiese, K

1976-07-01

10

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

11

Determination of displacements at the boundary of a body due to discontinuities in the medium  

SciTech Connect

The problem of determining the displacements at the boundary of a body due to instantaneous disturbance of the continuity of the medium inside the body, i.e. discontinuities over a certain finite surface S, is of particular interest in connection with the inspection of structural elements, prediction of the probable effects of earthquakes, and the study of other processes. Three-dimensional problems - which more adequately reflect the actual physical processes that take place - are especially interesting in this regard. Here, we use an elastic half-space as an example to study the dependence of the displacements at its boundary on the instantaneous formation of discontinuities inside the half-space over a certain finite plane surface S. To solve this problem with allowance for its three-dimensional nature, we will examine a half-space weakened by plane slits whose opposing surfaces are displaced relative to one another over the period of time t in accordance with a certain law. Conditionally assuming that this law is known, we determine the displacements that these displacements cause at the boundary of the body. The boundary is assumed to be free of external forces.

Stankevich, V.Z.; Khai, M.V. [Institute of Applied Problems of Mechanics and Mathematics, Lvov (Ukraine)

1995-06-01

12

Electromechanical measurements of electric field-induced displacements of fibers.  

PubMed

In this paper we report on a development of a new method for measurements of electric field-induced displacements in a cylindrical geometry (optical fiber with the deposited piezoelectric film). The measurement setup is based on a commercially available Fotonic Sensor MTI 2000 (MTI Inc.). Major disadvantages of measurement by standard techniques (e.g., interferometry) such as low reflectivity, high roughness of the coating resulting in poor fringe quality, and big displacement range are successfully avoided using a special configuration of an optical probe and a sample. The method allows performing investigations of electromechanically induced vibrations in a broad frequency range (from 0 up to 150 kHz) and various combinations of ac and dc voltages. The capabilities of the proposed method are validated by strain measurements of an optical fiber cantilever beam covered by Pb(Zr,Ti)O(3) thick film. PMID:18248066

Vyshatko, Nikolai P; Vilarinho, Paula M; Kholkin, Andrei L

2008-01-01

13

Electromechanical measurements of electric field-induced displacements of fibers  

NASA Astrophysics Data System (ADS)

In this paper we report on a development of a new method for measurements of electric field-induced displacements in a cylindrical geometry (optical fiber with the deposited piezoelectric film). The measurement setup is based on a commercially available Fotonic Sensor MTI 2000 (MTI Inc.). Major disadvantages of measurement by standard techniques (e.g., interferometry) such as low reflectivity, high roughness of the coating resulting in poor fringe quality, and big displacement range are successfully avoided using a special configuration of an optical probe and a sample. The method allows performing investigations of electromechanically induced vibrations in a broad frequency range (from 0 up to 150 kHz) and various combinations of ac and dc voltages. The capabilities of the proposed method are validated by strain measurements of an optical fiber cantilever beam covered by Pb(Zr,Ti)O3 thick film.

Vyshatko, Nikolai P.; Vilarinho, Paula M.; Kholkin, Andrei L.

2008-01-01

14

Tsunami simulation using submarine displacement calculated from simulation of ground motion due to seismic source model  

NASA Astrophysics Data System (ADS)

Since fault fracturing due to an earthquake can simultaneously cause ground motion and tsunami, it is appropriate to evaluate the ground motion and the tsunami by single fault model. However, several source models are used independently in the ground motion simulation or the tsunami simulation, because of difficulty in evaluating both phenomena simultaneously. Many source models for the 2011 off the Pacific coast of Tohoku Earthquake are proposed from the inversion analyses of seismic observations or from those of tsunami observations. Most of these models show the similar features, which large amount of slip is located at the shallower part of fault area near the Japan Trench. This indicates that the ground motion and the tsunami can be evaluated by the single source model. Therefore, we examine the possibility of the tsunami prediction, using the fault model estimated from seismic observation records. In this study, we try to carry out the tsunami simulation using the displacement field of oceanic crustal movements, which is calculated from the ground motion simulation of the 2011 off the Pacific coast of Tohoku Earthquake. We use two fault models by Yoshida et al. (2011), which are based on both the teleseismic body wave and on the strong ground motion records. Although there is the common feature in those fault models, the amount of slip near the Japan trench is lager in the fault model from the strong ground motion records than in that from the teleseismic body wave. First, the large-scale ground motion simulations applying those fault models used by the voxel type finite element method are performed for the whole eastern Japan. The synthetic waveforms computed from the simulations are generally consistent with the observation records of K-NET (Kinoshita (1998)) and KiK-net stations (Aoi et al. (2000)), deployed by the National Research Institute for Earth Science and Disaster Prevention (NIED). Next, the tsunami simulations are performed by the finite difference calculation based on the shallow water theory. The initial wave height for tsunami generation is estimated from the vertical displacement of ocean bottom due to the crustal movements, which is obtained from the ground motion simulation mentioned above. The results of tsunami simulations are compared with the observations of the GPS wave gauges to evaluate the validity for the tsunami prediction using the fault model based on the seismic observation records.

Akiyama, S.; Kawaji, K.; Fujihara, S.

2013-12-01

15

The deformation field around a point displacement in a gel  

NASA Astrophysics Data System (ADS)

We study the deformation field around a point displacement in a fractal colloidal gel. The samples are formed by diffusion-limited cluster aggregation (DLCA) of latex spheres with a small number of paramagnetic latex spheres. An external magnetic field is applied and the motions of the latex spheres are probed with an optical microscope. Using IDL particle tracking software, we obtain the particle positions. The deformation field is compared to the local structure in order to investigate the local elasticity. We also measure each particle's localization length, which is the root mean square deviation from the particle's time-averaged position. It has been found that disordered solids share a common distribution of normalized localization lengths; we investigate whether this distribution is the same under conditions of applied stress. The results of our measurements will be helpful to test statistical mechanical predictions of universal properties of disordered solids. We acknowledge support from the donors of the American Chemical Society Petroleum Research Fund.

Kang, Wenfeng; Dinsmore, A. D.

2004-03-01

16

Remagnetization effects due to lateral displacement above a PMG on bulk HTS magnet  

NASA Astrophysics Data System (ADS)

For a high-Tc superconducting (HTS) maglev system with large force requirements, the use of magnetized bulk high-Tc superconductor magnets (MBSCMs) is a good candidate because of its strong flux pinning ability and corresponding high trapped flux. Different from the rare-earth permanent magnet (PM), the trapped flux of a MBSCM is sustained by the supercurrent produced by a magnetizing process, so the trapped flux is sensitive to variations of the supercurrent. The lateral displacement of a MBSCM above a PM guideway (PMG) will provide disturbance of the applied field and then alter the supercurrent as a process of remagnetization. Different magnetization histories will bring different remagnetization characteristics and consequently diverse levitation performances for a MBSCM during the lateral displacements. When the MBSCMs are applied into the HTS maglev system, the influence of lateral displacements on levitation performance should be taken into consideration. This article investigates the remagnetization characteristics of a MBSCM when it is subject to the lateral displacements above a PMG with different trapped magnetic flux and opposite magnetization polarities. Relevant analyses about the internal supercurrent configuration based on the critical state model are also included to better understand the remagnetization characteristic of a MBSCM.

Liu, W.; Wang, J. S.; Ma, G. T.; Zheng, J.; Ren, J. F.; Li, L. L.; Yang, X. F.; Ye, C. Q.; Wang, S. Y.

2012-12-01

17

Multiscale displacement field measurements of compressed mineral-wool samples by digital image correlation  

Microsoft Academic Search

We propose a multiscale approach to determine the displacement field by digital image correlation. The displacement field is first estimated on a coarse resolution image and progressively finer details are introduced in the analysis as the displacement is more and more securely and accurately determined. Such a scheme has been developed to increase the robustness, accuracy, and reliability of the

Francois Hild; Bumedijen Raka; Maud Baudequin; Stephane Roux; Florence Cantelaube

2002-01-01

18

Diagonal parameter shifts due to nearest-neighbor displacements in empirical tight-binding theory  

NASA Astrophysics Data System (ADS)

Nanoscale heterostructures are generally characterized by local strain variations. Because the atoms in such systems can be irregularly positioned, theroretical models and parameterizations that are restricted to hydrostatic and uniaxial strain are generally not applicable. To address this shortcoming, a method that enables the incorporation of general distortions into the empirical tight binding model is presented. The method shifts the diagonal Hamiltonian matrix elements due to displacements of neighboring atoms from their ideal bulk positions. The new, efficient, and flexible method is developed for zincblende semiconductors and employed to calculate gaps for GaAs and InAs under hydrostatic and uniaxial strain. Where experimental and theoretical data are available our new method compares favorably with other methods, yet it is not restricted to the cases of uniaxial or hydrostatic strain. Because our method handles arbitrary nearest-neighbor displacements it permits the incorporation of diagonal parameter shifts in general, three-dimensional nanoscale electronic structure simulations, such as the nanoelectronic modeling tool (NEMO 3D).

Boykin, Timothy B.; Klimeck, Gerhard; Bowen, R. Chris; Oyafuso, Fabiano

2002-09-01

19

Vertical crustal displacement due to interseismic deformation along the San Andreas fault: Constraints from tide gauges  

NASA Astrophysics Data System (ADS)

motion along complex strike-slip fault systems such as the San Andreas Fault System (SAFS) can produce vertical velocities that are ~10 times smaller than horizontal velocities, caused by along-strike variations in fault orientation and locking depth. Tide gauge stations provide a long (50-100 year) recording history of sea level change due to several oceanographic and geologic processes, including vertical earthquake cycle deformation. Here we compare relative sea level displacements with predictions from a 3-D elastic/viscoelastic earthquake cycle model of the SAFS. We find that models with lithospheric structure reflecting a thick elastic plate (>50 km) and moderate viscosities produce vertical motions in surprisingly good agreement with the relative tide gauge uplift rates. These results suggest that sea level variations along the California coastline contain a small but identifiable tectonic signal reflecting the flexure of the elastic plate caused by bending moments applied at the ends of locked faults.

Smith-Konter, Bridget R.; Thornton, Garrett M.; Sandwell, David T.

2014-06-01

20

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

NASA Astrophysics Data System (ADS)

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.

Gailhanou, Marc; Roussel, Jean-Marc

2013-12-01

21

Two-dimensional Co-Seismic Surface Displacements Field of the Chi-Chi Earthquake Inferred from SAR Image Matching  

PubMed Central

The Mw=7.6 Chi-Chi earthquake in Taiwan occurred in 1999 over the Chelungpu fault and caused a great surface rupture and severe damage. Differential Synthetic Aperture Radar Interferometry (DInSAR) has been applied previously to study the co-seismic ground displacements. There have however been significant limitations in the studies. First, only one-dimensional displacements along the Line-of-Sight (LOS) direction have been measured. The large horizontal displacements along the Chelungpu fault are largely missing from the measurements as the fault is nearly perpendicular to the LOS direction. Second, due to severe signal decorrelation on the hangling wall of the fault, the displacements in that area are un-measurable by differential InSAR method. We estimate the co-seismic displacements in both the azimuth and range directions with the method of SAR amplitude image matching. GPS observations at the 10 GPS stations are used to correct for the orbital ramp in the amplitude matching and to create the two-dimensional (2D) co-seismic surface displacements field using the descending ERS-2 SAR image pair. The results show that the co-seismic displacements range from about -2.0 m to 0.7 m in the azimuth direction (with the positive direction pointing to the flight direction), with the footwall side of the fault moving mainly southwards and the hanging wall side northwards. The displacements in the LOS direction range from about -0.5 m to 1.0 m, with the largest displacement occuring in the northeastern part of the hanging wall (the positive direction points to the satellite from ground). Comparing the results from amplitude matching with those from DInSAR, we can see that while only a very small fraction of the LOS displacement has been recovered by the DInSAR mehtod, the azimuth displacements cannot be well detected with the DInSAR measurements as they are almost perpendicular to the LOS. Therefore, the amplitude matching method is obviously more advantageous than the DInSAR in studying the Chi-Chi earthquake. Another advantage of the method is that the displacement in the hanging wall of the fault that is un-measurable with DInSAR due to severe signal decorrelation can almost completely retrieved in this research. This makes the whole co-seismic displacements field clearly visible and the location of the rupture identifiable. Using displacements measured at 15 independent GPS stations for validation, we found that the RMS values of the differences between the two types of results were 6.9 cm and 5.7 cm respectively in the azimuth and the range directions.

Hu, Jun; Li, Zhi-Wei; Ding, Xiao-Li; Zhu, Jian-Jun

2008-01-01

22

Displacement fields U and V by interferometry of three beams  

SciTech Connect

The simultaneous measurement of the two in-plane displacement components by electronic speckle pattern interferometry with three objects beams and without in-line reference beam is presented. Three interference fringes patterns corresponding to three different sensitivity vectors are recorded in a single interferogram and separated by means of the Fourier transform method. Two interference fringes patterns are selected to obtain the in-plane displacement components.

Martinez, Amalia; Rayas, J. A.; Anguiano-Morales, Marcelino; Mendoza, Fernando [Centro de Investigaciones en Optica, A. C., Leon, Gto. (Mexico); Meneses-Fabian, Cruz [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias Fisico-Matematicas, Puebla (Mexico)

2008-04-15

23

Digital image correlation for whole field out-of-plane displacement measurement using a single camera  

Microsoft Academic Search

Digital image correlation (DIC) using a single camera has been widely used for in-plane displacement and strain measurement. However, in order to obtain out-of-plane displacement, one should employ stereo vision systems which enable multiple directions detection. In this paper, we develop a simple method for whole field out-of-plane displacement measurement using only one camera. The proposed method employs digital image

C. J. Tay; C. Quan; Y. H. Huang; Y. Fu

2005-01-01

24

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

Microsoft Academic Search

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

Per Synnergren; Mikael Sjödahl

1999-01-01

25

Displacement Damage Effects Due to Neutron and Proton Irradiations on CMOS Image Sensors Manufactured in Deep Submicron Technology  

Microsoft Academic Search

Displacement damage effects due to proton and neutron irradiations of CMOS image sensors dedicated to imaging are presented through the analysis of the dark current behavior in pixel arrays and isolated photodiodes. The mean dark current increase and the dark current nonuniformity are investigated. Dark current histogram observations are compared to damage energy distributions based on GEANT 4 calculations. We

Cedric Virmontois; Vincent Goiffon; Pierre Magnan; Sylvain Girard; Christophe Inguimbert; Sophie Petit; Guy Rolland; Olivier Saint-Pé

2010-01-01

26

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

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

27

The probability density function of the multiplication factor due to small, random displacements of fissile spheres  

Microsoft Academic Search

An analytical expression is obtained for the probability density function of the multiplication factor of an array of spheres when each sphere is displaced in a random fashion from its initial position. Two cases are considered: (1) spheres in an infinite background medium in which the total cross section in spheres and medium is the same, and (2) spheres in

M. M. R. Williams

2003-01-01

28

TRANSVERSE EFFECTS DUE TO RANDOM DISPLACEMENT OF RESISTIVE WALL SEGMENTS AND FOCUSING ELEMENTS  

SciTech Connect

In this paper, we study the single bunch transverse beam dynamics in the presence of random displacements of resistive wall segments and focusing elements. Analytical formulas are obtained for long-range resistive wall wake, together with numerical results for short-range resistive wall wake. The results are applied to the LCLS project and some other proposed accelerators.

Jean Delayen; Juhao Wu

2007-06-18

29

Linear displacement sensor with high magnetic field gradient  

Microsoft Academic Search

This paper presents designs of permanent magnet structures providing a high magnetic field gradient in an air gap for microdisplacement sensor application. A geometric optimization of the structure is fulfilled with magnetic induction analytic calculation in the air gap. The magnetic field gradient value is obtained by finite element analysis. A discussion about the different structures is presented, with regard

C. Blache; G. Lemarquand

1992-01-01

30

Coseismic Displacement Field of the June 23, 2001 Peru Earthquake  

NASA Astrophysics Data System (ADS)

On June 23 2001, a Mw 8.3 earthquake followed by a tsunami with waves up to 7.8m affected the southern coastal region of Peru. The epicenter was located at 16.22 \\deg S, 76.60 \\deg W and caused significant damage in towns located along the shoreline between Atico and Ilo as well in the inland cities of Arequipa and Moquegua. We present coseismic displacement estimates from GPS data at 14 geodetic monuments having a spatial coverage of about 760 km x 340 km. Maximum horizontal coseismic offset of 1.02m and maximum vertical offset of 0.80m were observed at the coastal stations of JHAI and TANA respectively. To the east of the epicenter, two continuous stations: AREQ and MIST measured average horizontal coseismic offset of 0.47m. During the observation phase a Mw 7.6 aftershock occurred in the neighborhood of POCO. We will present results of elastic dislocation models based on available GPS and seismic data.

Norabuena, E. O.; Norabuena, E. O.; Dixon, T.; Sacks, I.; Stein, S.

2001-12-01

31

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

NASA Astrophysics Data System (ADS)

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.

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

2012-03-01

32

Displacement current and the generation of parallel electric fields.  

PubMed

We show for the first time the dynamical relationship between the generation of magnetic field-aligned electric field (E||) and the temporal changes and spatial gradients of magnetic and velocity shears, and the plasma density in Earth's magnetosphere. We predict that the signatures of reconnection and auroral particle acceleration should have a correlation with low plasma density, and a localized voltage drop (V||) should often be associated with a localized magnetic stress concentration. Previous interpretations of the E|| generation are mostly based on the generalized Ohm's law, causing serious confusion in understanding the nature of reconnection and auroral acceleration. PMID:16712084

Song, Yan; Lysak, Robert L

2006-04-14

33

Displacement Current and the Generation of Parallel Electric Fields  

SciTech Connect

We show for the first time the dynamical relationship between the generation of magnetic field-aligned electric field (E{sub parallel}) and the temporal changes and spatial gradients of magnetic and velocity shears, and the plasma density in Earth's magnetosphere. We predict that the signatures of reconnection and auroral particle acceleration should have a correlation with low plasma density, and a localized voltage drop (V{sub parallel}) should often be associated with a localized magnetic stress concentration. Previous interpretations of the E{sub parallel} generation are mostly based on the generalized Ohm's law, causing serious confusion in understanding the nature of reconnection and auroral acceleration.

Song Yan; Lysak, Robert L. [School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

2006-04-14

34

A parametric method to model 3D displacements around faults with volumetric vector fields  

NASA Astrophysics Data System (ADS)

This paper presents a 3D parametric fault representation for modeling the displacement field associated with faults in accordance with their geometry. The displacements are modeled in a canonical fault space where the near-field displacement is defined by a small set of parameters consisting of the maximum displacement amplitude and the profiles of attenuation in the surrounding space. The particular geometry and the orientation of the slip of each fault are then taken into account by mapping the actual fault onto its canonical representation. This mapping is obtained with the help of a curvilinear frame aligned both on the fault surface and slip direction. This formulation helps us to include more geological concepts in quantitative subsurface models during 3D structural modeling tasks. Its applicability is demonstrated in the framework of forward modeling and stochastic sequential fault simulations, and the results of our model are compared to observations of natural objects described in the literature.

Laurent, Gautier; Caumon, Guillaume; Bouziat, Antoine; Jessell, Mark

2013-04-01

35

A Novel “Subset Splitting” Procedure for Digital Image Correlation on Discontinuous Displacement Fields  

Microsoft Academic Search

Digital Image Correlation (DIC) is an easy to use yet powerful approach to measure displacement and strain fields. While the\\u000a method is robust and accurate for a variety of applications, standard DIC returns large error and poor correlation quality\\u000a near displacement discontinuities such as cracks or shear bands. This occurs because the subsets used for correlation can\\u000a only capture continuous

J. Poissant; F. Barthelat

2010-01-01

36

Displacements of the earth's surface due to atmospheric loading - Effects of gravity and baseline measurements  

NASA Technical Reports Server (NTRS)

Atmospheric mass loads and deforms the earth's crust. By performing a convolution sum between daily, global barometric pressure data and mass loading Green's functions, the time dependent effects of atmospheric loading, including those associated with short-term synoptic storms, on surface point positioning measurements and surface gravity observations are estimated. The response for both an oceanless earth and an earth with an inverted barometer ocean is calculated. Load responses for near-coastal stations are significantly affected by the inclusion of an inverted barometer ocean. Peak-to-peak vertical displacements are frequently 15-20 mm with accompanying gravity perturbations of 3-6 micro Gal. Baseline changes can be as large as 20 mm or more. The perturbations are largest at higher latitudes and during winter months. These amplitudes are consistent with the results of Rabbel and Zschau (1985), who modeled synoptic pressure disturbances as Gaussian functions of radius around a central point. Deformation can be adequately computed using real pressure data from points within about 1000 km of the station. Knowledge of local pressure, alone, is not sufficient. Rabbel and Zschau's hypothesized corrections for these displacements, which use local pressure and the regionally averaged pressure, prove accurate at points well inland but are, in general, inadequate within a few hundred kilometers of the coast.

Van Dam, T. M.; Wahr, J. M.

1987-01-01

37

Irreducible dislocation of the thumb interphalangeal joint due to displaced flexor pollicis longus tendon: case report and new reduction technique.  

PubMed

Dislocation of the thumb interphalangeal (IP) joint is uncommon because of the inherent stability of the joint. Cases in which reduction was blocked by the volar plate, the flexor pollicis longus (FPL) tendon, the sesamoid bone, and an osteochondral fragment have been described in the literature. This article reports a case of closed thumb IP joint dislocation caused by the displacement of the FPL tendon. A new percutaneous reduction technique for this injury will also be presented. A 63-year-old woman presented to the emergency room with an obvious thumb deformity. Radiographs confirmed dorsal dislocation of the thumb IP joint without associated fracture. Closed reduction was not successful. Percutaneous reduction was performed under locoregional anesthesia, because the dislocation was due to an FPL tendon that had displaced dorsally and radially to the proximal phalanx. After reduction, Kirschner wire fixation was not needed, but IP joint immobilization with a splint was required for 3 weeks. Postoperatively, there were no complications in soft tissues and the operative scar was almost unrecognizable. This technique enables a mini-invasive reduction by operating percutaneously on the FPL. In addition, unlike with a volar zigzag approach, it is possible to suppress the occurrence of postoperative adhesion of the flexor tendon. This new minimally invasive reduction technique is useful for irreducible dislocation of the thumb IP joint due to a displaced FPL tendon. PMID:24902518

Naito, Kiyohito; Sugiyama, Yoichi; Igeta, Yuka; Kaneko, Kazuo; Obayashi, Osamu

2014-08-01

38

NONLINEAR SIMULATION OF TURBULENT FIELD LINES AND COMPARISON OF THEIR MEAN CROSS-FIELD DISPLACEMENT WITH THEORETICAL PREDICTION  

SciTech Connect

A new method for the full nonlinear computation of turbulent field lines is presented that extends the Sums of Random Numbers Distribution method previously applied to the computation of generalized quasilinear (GQL) field lines. A study of the mean cross-field displacement confirms the theoretical prediction of a nonlinear diffusion regime, on the large scales where the mean cross-field displacement exceeds twice the perpendicular correlation length. The simulation results duplicate at all length scales the variations of the mean cross-field displacement predicted by the theoretical calculations, including the transitions from GQL supradiffusion to nonlinear diffusion. Both GQL and full nonlinear computations also reproduce, accurately, the predicted variations with turbulence level of the large-scale GQL and nonlinear diffusion coefficients, respectively.

Ragot, B. R. [Air Force Research Laboratory, RVBXS, 29 Randolph Rd., Hanscom AFB, MA 01731-3010 (United States)

2010-06-01

39

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

NASA Astrophysics Data System (ADS)

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 ~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.

Shao, Tao; Tarasenko, Victor F.; Zhang, Cheng; Burachenko, Alexandr G.; Rybka, Dmitry V.; Kostyrya, Igor'D.; Lomaev, Mikhail I.; Baksht, Evgeni Kh.; Yan, Ping

2013-05-01

40

Accurate full-field optical displacement measurement technique using a digital camera and repeated patterns.  

PubMed

In this study, a novel, fast, and accurate in-plane displacement distribution measurement method is proposed that uses a digital camera and arbitrary repeated patterns based on the moiré methodology. The key aspect of this method is the use of phase information of both the fundamental frequency and the high-order frequency components of the moiré fringe before and after deformations. Compared with conventional displacement methods and sensors, the main advantages of the method developed herein are its high resolution, accuracy, speed, low cost, and easy implementation. The effectiveness is confirmed by a simple in-plane displacement measurement experiment, and the experimental results indicate that an accuracy of 1/1000 of the pitch can be achieved for various repeated patterns. This method is useful for various applications ranging from the study of displacement and strain distributions in materials science, the biomimetics field, and mechanical material testing, to secure the integrity of infrastructures. PMID:24787855

Ri, Shien; Hayashi, Satoshi; Ogihara, Shinji; Tsuda, Hiroshi

2014-04-21

41

FIELD TRIALS OF NEWLY DEVELOPED POSITIVE DISPLACEMENT SUBMERSIBLE PUMP  

SciTech Connect

The purpose of this grant was to evaluate under real world conditions the performance of a new type of downhole pump, the hydraulically driven submersible diaphragm pump. This pump is supplied by Pumping Solutions Incorporated, Albuquerque NM. The original scope of the project was to install 10 submersible pumps, and compare that to 10 similar installations of rod pumps. As an operator, the system as tested was not ready for prime time, but has shown the ability to reduce costs, and increase production, if run times can be improved. The PSI group did improve the product and offered excellent service. The latest design appears to be much better, but more test data is needed to show short run life is not a problem. PSI and Beard Oil intend to continue testing the pump with non-government funding. The testing to date did not uncover any fundamental problems that would preclude the widespread use of this pump, and as an operator, I believe that with further improvement and testing, the pump can have a significant impact on stripper well costs. On the positive side, the pump was easy to run, was more power efficient then a rod pump, and is the only submersible that could handle the large quantities of solids typical of the production environment found at the Weber field and in CMB production. The product shows much promise for the future, and with continued design and testing, this type of submersible pump has the potential to become the standard of the industry.

Rob Beard

2003-10-01

42

Field performance of the Walker Branch throughfall displacement experiment  

SciTech Connect

The authors are conducting a large-scale manipulative field experiments in an upland oak forest on the Walker Branch Watershed in eastern Tennessee USA to identify important ecosystem responses that might result from future precipitation changes. The manipulation of soil moisture is being implemented by a gravity-driven transfer of throughfall precipitation from one treatment plot to another. Throughfall is intercepted in {approx} 2,000 subcanopy troughs (0.3 x 5 m) suspended above the forest floor of the dry plots ({approx} 33% of the ground area is covered) and transferred by gravity flow across an ambient plot for subsequent distribution onto the wet treatment plot. Percent soil water is being monitored with time domain reflectometers at 310 sampling locations across the site. The experimental system is able to produce statistically significant differences in soil water content in years having both extremely dry and extremely wet conditions. Furthermore, comparisons of pre- and post-installation soil temperature measurements have documented the ability of the experimental design to produce these changes without changing the microclimate of the forest understory.

Hanson, P.J.; Todd, D.E.; Edwards, N.T.; Huston, M.A. [Oak Ridge National Lab., TN (United States). Environmental Sciences Div.

1994-10-06

43

Displacement sensor containing magnetic field sensing element between a pair of biased magnets movable as a unit  

NASA Technical Reports Server (NTRS)

A displacement sensor for providing an indication of the position of a first body relative to a second body, the first body being displaceable relative to the second body in a displacement direction. The sensor is composed of: two magnets that are spaced from one another in the displacement direction to define therebetween a region containing a magnetic field; a magnetic field sensing element mounted in the region; and components for coupling at least one of the magnets to one of the bodies and the magnetic field sensing element to the other of the bodies to produce a relative displacement between the at least one magnet and the magnetic field sensing element in the displacement direction in response to displacement of the first body relative to the second body.

Bahr, Joseph K. (Inventor); Johnson, Mont A. (Inventor)

2003-01-01

44

Digital image correlation using iterative least squares and pointwise least squares for displacement field and strain field measurements  

Microsoft Academic Search

Digital image correlation (DIC) method using iterative least squares algorithm (ILS) for displacement field measurement and pointwise least squares algorithm (PLS) for strain field measurement is proposed in this paper. A more general and practical intensity change model is employed with consideration of the linear intensity change of the deformed image, followed by an iterative least squares algorithm for calculating

Bing Pan; Anand Asundi; Huimin Xie; Jianxin Gao

2009-01-01

45

Measurement of displacement field around a crack tip using fractal correlation method  

NASA Astrophysics Data System (ADS)

The key problem to enhance the precision of displacements measurement with image correlation is to make the most of correlation behavior of speckle images. In fact, the artificial random speckles or natural texture, especially the microcosmic texture, on the object's surface have fractal characteristics, and the digital images of these patterns are also fractals. It is found that there is correlation between the fractal characteristics in un-deformed and deformed states of the images. Based on this fact a method called fractal correlation method, can be used to measure displacements. In this paper, the fractal correlation method was used to measure the displacement field on a crack tip of a metal specimen. The microcosmic natural texture on specimen's surface was taken as images, and the area was 1.397×1.397mm. By correlation operation with the fractal correlation method, curves of displacement around the tip can be obtained. The position of crack tip can be clearly distinguished from the displacement curves. The relationship of COD and distance behind the tip is linear. This agrees with the theory of fracture mechanics. The results also show that the plastic field does not distribute in uniform.

Hou, Zhende; Qin, Yuwen; Xiu, Lianyun

2003-04-01

46

Detection of in-plane displacements of acoustic wave fields using extrinsic Fizeau fiber interferometric sensors  

NASA Technical Reports Server (NTRS)

Quantitative measurements of the in-plane particle displacement components of ultrasonic surface acoustic wave fields using extrinsic Fizeau fiber interferometric (EFFI) sensors are reported. Wave propagation in materials and the fiber sensor elements are briefly discussed. Calibrated experimental results obtained for simulated acoustic emission events on homogeneous metal test specimens are reported and compared to previous results obtained using piezoelectric transducers.

Dhawan, R.; Gunther, M. F.; Claus, R. O.

1991-01-01

47

The use of displacement sensitive organic field effect transistor for telemetry system applications  

Microsoft Academic Search

The thin films of the organic semiconductor material Copper Phthalocyanine (CuPc) and metal Aluminum (Al) were deposited in a sequence by vacuum thermal evaporation technique on glass substrate with Silver (Ag) as source and drain electrodes. The effect of displacement on properties of the fabricated Organic Field Effect Transistor (OFET) was investigated. It was observed that the drain–source resistance of

Kh. S. Karimov; T. A. Qasuria

48

Strain field due to self-interstitial impurity in Ni  

NASA Astrophysics Data System (ADS)

The embedded-atom method have been applied to study the strain field produced by the self-interstitial impurity at the octahedral site in Ni. The calculation have been carried out consistently on the basis of discrete lattice theory, using Kanzaki method. The atomic force constants are evaluated using Wills and Harrison interatomic potential. The dynamical matrix and external force are evaluated considering the interaction up to first nearest neighbors. The atomic displacements are tabulated up to 20NN's. These displacements are of oscillatory nature and of decreasing magnitude with NN's distance. The physical properties such as self-interstitial formation energy and volume change calculated using atomic displacements are in accordance with the earlier studies.

Sharma, Hitesh; Prakash, S.

2003-01-01

49

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

NASA Astrophysics Data System (ADS)

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.

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

2011-07-01

50

Ionospheric effects due to electrostatic thundercloud fields  

Microsoft Academic Search

Electrostatic thundercloud fields are shown to heat lower ionospheric electrons significantly under night time conditions. The effect is maximized under conditions of higher altitudes of thundercloud charges, larger magnitudes of these charges, and larger scale heights of ambient conductivity profiles. The lower ionospheric conductivity can be modified as a result of the heating by up to one order of magnitude

V. P. Pasko; T. F. Bell

1998-01-01

51

Reconstruction of myocardial tissue motion and strain fields from displacement-encoded MR imaging  

PubMed Central

A quantitative analysis of myocardial mechanics is fundamental to understanding cardiac function, diagnosis of heart disease, and assessment of therapeutic intervention. Displacement encoding with stimulated-echo (DENSE) magnetic resonance imaging (MRI) technique was developed to track the three-dimensional (3D) displacement vector of discrete material grid points in the myocardial tissue. Despite the wealth of information gained from DENSE images, the current software only provides two-dimensional in-plane deformation. The objective of this study is to introduce a postprocessing method to reconstruct and visualize continuous dynamic 3D displacement and strain fields in the ventricular wall from DENSE data. An anatomically accurate hexagonal finite-element model of the left ventricle (LV) is reconstructed by fitting a prolate spheroidal primitive to contour points of the epi- and endocardial surfaces. The continuous displacement field in the model is described mathematically based on the discrete DENSE vectors using a minimization method with smoothness regularization. Based on the displacement, heart motion and myocardial stretch (or strain) are analyzed. Illustratory computations were conducted with DENSE data of three infarcted and one normal sheep ventricles. The full 3D results show stronger overall axial shortening, wall thickening, and twisting of the normal LV compared with the infarcted hearts. Local myocardial stretches show a dyskinetic LV in the apical region, dilation of apex in systole, and a compensatory increase in strain in the healthy basal region as a compensatory mechanism. We conclude that the proposed postprocessing method significantly extends the utility of DENSE MRI, which may provide a patient-specific 3D model of cardiac mechanics.

Liu, Yi; Wen, Han; Gorman, Robert C.; Pilla, James J.; Gorman, Joseph H.; Buckberg, Gerald; Teague, Shawn D.; Kassab, Ghassan S.

2009-01-01

52

Strain field due to transition metal impurities in Ni and Pd  

NASA Astrophysics Data System (ADS)

The strain field due to body centered substitutional transition metal impurities in Ni and Pd metals are investigated. The calculations are carried out in the discrete lattice model of the metal using Kanzaki lattice static method. The effective ion-ion interaction potential due to Wills and Harrison is used to evaluate dynamical matrix and the impurity-induced forces. The results for atomic displacements due to 3d, 4d and 5d impurities (Fe, Co, Cu, Nb, Mo, Pd, Pt and Au) in Ni and (Fe, Co, Cu, Ni, Nb, Mo, Pt and Au) impurities in Pd are given up to 25 NN's of impurity and these are compared with the available experimental data. The maximum displacements of 4.6% and 3.8% of 1NN distance are found for NiNb and PdNb alloys respectively, while the minimum displacements of 0.63% and 0.23% of 1NN distance are found for NiFe and PdFe alloys respectively. Except for Cu, the atomic displacements are found to be proportional to the core radii and d state radius. The relaxation energies for 3d impurities are found less than those for 4d and 5d impurities in Ni and Pd metals. Therefore, 3d impurities may easily be solvable in these metals.

Sharma, Hitesh; Prakash, S.

2003-01-01

53

Contribution of nuclear displacements to the static polarizability of molecules in an external electric field: Application to fluorinated fullerenes C{sub 60}F{sub n}  

SciTech Connect

In molecules with ionic contributions to the binding, the contribution of nuclear displacements (due to the external field) to the static polarizability can be decisive. Using the finite field method, we optimized the structure with and without a finite external electric field by a total energy minimization and we calculated the polarizability from the induced dipole moment. In C{sub 60}F{sub n}, fluorination mostly increases the polarizability. Only for n=2 and 18, where the molecule without an external field has a very large dipole moment, does fluorination decrease it. For large n (n=20, 36, and 48), the polarizability per added F atom due to nuclear displacements is increased by a factor of about 2. The validity of the additivity model has been discussed.

Zagorodniy, K.; Taut, M.; Hermann, H. [Leibniz Institute for Solid State and Materials Research, IFW Dresden, P.O. Box 270016, 01171 Dresden (Germany)

2006-05-15

54

Cascadia Slow Earthquakes: Strategies for Time Independent Inversion of Displacement Fields  

NASA Astrophysics Data System (ADS)

Continuous observations using Global Positioning System geodesy (CGPS) have revealed periodic slow or silent earthquakes along the Cascadia subduction zone with a spectrum of timing and periodicity. These creep events perturb time series of GPS observations and yield coherent displacement fields that relate to the extent and magnitude of fault displacement. In this study, time independent inversions of the surface displacement fields that accompany eight slow earthquakes characterize slip distributions along the plate interface for each event. The inversions employed in this study utilize Okada's elastic dislocation model and a non- negative least squares approach. Methodologies for optimizing the slip distribution smoothing parameter for a particular station distribution have also been investigated, significantly reducing the number of possible slip distributions and the range of estimates for total moment release for each event. The discretized slip distribution calculated for multiple creep events identifies areas of the Cascadia plate interface where slip persistently recurs. The current hypothesis, that slow earthquakes are modulated by forced fluid flow, leads to the possibility that some regions of the Cascadia plate interface may display fault patches preferentially exploited by fluid flow. Thus, the identification of regions of the plate interface that repeatedly slip during slow events may yield important information regarding the identification of these fluid pathways.

Szeliga, W. M.; Melbourne, T. I.; Miller, M. M.; Santillan, V. M.

2004-12-01

55

Painful rib hump: a new clinical sign for detecting intraspinal rib displacement in scoliosis due to neurofibromatosis  

PubMed Central

Background Spinal cord compression and associate neurological impairment is rare in patients with scoliosis and neurofibromatosis. Common reasons are vertebral subluxation, dislocation, angulation and tumorous lesions around the spinal canal. Only twelve cases of intraspinal rib dislocation have been reported in the literature. The aim of this report is to present a case of rib penetration through neural foramen at the apex of a scoliotic curve in neurofibromatosis and to introduce a new clinical sign for its detection. Methods A 13-year-old girl was evaluated for progressive left thoracic kyphoscoliotic curve due to a type I neurofibromatosis. Clinical examination revealed multiple large thoracic and abdominal "cafe-au-lait" spots, neurological impairment of the lower limbs and the presence of a thoracic gibbous that was painful to pressure at the level of the left eighth rib (Painful Rib Hump). CT-scan showed detachment and translocation of the cephalic end of the left eighth rib into the adjacent enlarged neural foramen. The M.R.I. examination of the spine showed neither cord abnormality nor neurogenic tumor. Results The patient underwent resection of the intraspinal mobile eighth rib head and posterior spinal instrumentation and was neurologically fully recovered six months postoperatively. Conclusion Spine surgeons should be aware of intraspinal rib displacement in scoliotic curves in neurofibromatosis. Painful rib hump is a valuable diagnostic tool for this rare clinical entity.

Gkiokas, Andreas; Hadzimichalis, Socratis; Vasiliadis, Elias; Katsalouli, Marina; Kannas, Georgios

2006-01-01

56

Monitoring Landslide Displacement Fields at Different Temporal Scale by using GB-INSAR  

NASA Astrophysics Data System (ADS)

The application of SAR Interferometry technique (InSAR) for landslide monitoring, in order to resolve the problems connected to the implementation from the satellite platform, such as spatial resolution, incidence angles, temporal coverages, etc., can benefit from the use of ground-based instrumentation. This work concerns the application of ground-based SAR interferometry (GB-InSAR) to the monitoring of landslides characterized by different kinematics and diverse materials. This implementation has been realized by using the LISA (Linear Synthetic Radar) system developed at the JRC. The test sites, chosen to demonstrate the capabilities of such a technique in operational conditions, are the Ruinon rock slide in Valtellina, the Tessina earth slide in the Italian Dolomites and the Firenzuola rockslide in the Northern Appennines. The presence of independent monitoring systems within these landslides has allowed the radar measures to be validated. The LISA is a SAR system with interferometric capabilities specifically design for field applications. It is composed by a 2.8 m linear rail along which a motorised sled with two antennas is moved in order to obtain the synthetic aperture. The system can operate in the frequency band Ku (l = 1.8 cm) or C (l = 5.6 cm). Coherent SAR processing transforms raw data, acquired by the system, into a SAR images containing for each pixel information regarding the signal phase which depends on the target-sensor distance. Acquiring the data exactly from the same position (zero baseline condition), it is possible to directly relate the phase variations obtained by the interferometric analysis of consecutive couple of images to ground displacements along the line of sight of the radar instrumentations. Otherwise, by acquiring two radar datasets from slightly different positions it is possible to relate the phase variations obtained from the interferometric analysis to the topography of the observed area, providing an accurate DEM of the scene. While the first application allows to continuously follow the short term temporal evolution of the mass movements, the second one permits, by the comparison between interferometric DEM obtained in different periods, to observe the landslide evolution on a longer temporal scale. The application of these approaches to the selected test sites have demonstrated, by means of the comparison with traditionals instrumentations, the excellent precision and accuracy of the new technique. The use of such a technique, providing deformations maps of the studied area, facilitates the interpretation of the movement mechanism. Due to its non-invasive character, the good versatility in terms of suitable mass movement and the very high definition, the technique is well suited to mass movements, especially for those affecting urban area and cultural heritage.

Tarchi, D.; Casagli, N.; Catani, F.; Farina, P.; Leva, D.; Nico, G.

2002-12-01

57

Landslide sub-surface characteristics inferred from Terrestrial Laser Scanning surface displacement fields  

NASA Astrophysics Data System (ADS)

Increasingly available Terrestrial Laser Scanner (TLS) data permit the construction of complete ground-surface displacement fields for slow-moving landslides, particularly with the adoption of techniques such as particle-imaging velocimetry (PIV). An important next step, following well-developed analytical methodologies from the earthquake geodesy field, is to use the high-resolution surficial data to infer sub-surface characteristics such as slip-surface orientation and slip magnitude. Here, we first extend the PIV method to estimate a fully three-dimensional surface displacement field. Then, we test the efficacy of using two different sub-surface inference techniques and compare with in situ measurements from the episodically active part of the Cleveland Corral landslide in northern California. A 2-d balanced cross-section (area-balancing) method assuming incompressible material behavior uniquely constrains slip magnitude and depth whereas an elastic dislocation model requires solving a multidimensional non-linear inverse problem. We address this by placing strong prior constraints (e.g. length of the slip patch is about the length of the landslide) on orientation parameters that render the elastic dislocation problem computationally tractable via a direct search of parameter space. This reduction of free parameters is likely to be applicable to most surveyed landslides. The estimated landslide slip depth using both methods is consistent with previous seismic refraction surveys and contemporaneously installed shear rods. Importantly, slip magnitude determined by the balanced cross-section method is nearly twice that estimated using the elastic dislocation model (~ 1m). This two-fold difference is not surprising given the end-member model material properties but it highlights the need for further development of discriminatory criteria. Finally, our demonstration of this general sub-surface inference methodology should stimulate the development and application of more computationally efficient, though rheologically realistic, landslide models for use with inverse methods.

Aryal, A.; Brooks, B. A.; Reid, M. E.

2012-12-01

58

Diamagnetic magnetocaloric effect due to a transversal oscillating magnetic field  

NASA Astrophysics Data System (ADS)

The present Letter describes the magnetocaloric effect of a diamagnetic material with a magnetic field B? along the z axis and a transversal and oscillating field B?(?B?) parallel to the x-y plane. We show that the magnetocaloric potentials due to a change in B? are the same as those due to a change in the frequency of B?. These results raise the possibility of building magnetocaloric devices without moving parts, since changing frequency is a simple electronic issue, while changing the field from permanent magnets depends on mechanical aspects.

Reis, M. S.

2014-05-01

59

Surface displacement due to banda-aceh earthquake and its effect on geo-informatic work in Thailand  

Microsoft Academic Search

On the morning of December 26 th 2004, a major earthquake which was the fourth in instrumental seismology history happened 30 km below sea level off the coast of northern Sumatra, Indonesia. Using Okada's elastic formulae, the displacement caused by the earthquake on a number of GPS sites in Indonesia, Malaysia, Singapore, Myanmar and Thailand can be computed. The model

Chalermchon Satirapod; C. Wicheancharoen; I. Trisirisatayawong; C. Vigny; W. Simons

2005-01-01

60

General expressions for internal deformation fields due to a dislocation source in a multilayered elastic half-space  

Microsoft Academic Search

We have obtained general expressions for internal displacement and stress fields due to a point dislocation source in a multilayered elastic half-space under gravity. Most previous expressions for the internal deformation fields were obtained by applying one of two different types of Thomson-Haskell propagator matrix, namely the up-going propagator matrix proposed by Singh (1970) and the down-going propagator matrix proposed

Yukitoshi Fukahata; Mitsuhiro Matsu'ura

2005-01-01

61

Spark Voltage Dependence of Magnetic Fields Due to Electrostatic Discharge  

NASA Astrophysics Data System (ADS)

The electrostatic discharge (ESD) of charged metal objects produces electromagnetic (EM) fields having broad-band frequency spectra over the microwave region, which often gives serious EM interference (EMI) to electronic equipment. For the EMI of this kind, it has widely been accepted that the lower spark voltage ESD causes the stronger EMI to high-tech information equipment, whereas its mechanism still remains unknown. On the other hand, we previously proposed a new FDTD algorithm based on gap excitation with the time-variant conductivity and electric field of a spark channel, which enables one to predict the ESD fields due to charged metals having arbitrary shapes. In this study, the spark voltage dependence of the magnetic field due to a spark between cylindrical metals was investigated from our proposed FDTD computation and a spark experiment. As a result, it was found that the lower spark voltage produces the higher magnetic field level, while a certain spark voltage causes the highest magnetic field. This finding implies the presence of an ESD specific condition due to charged metals that gives the highest EM fields.

Seko, Hideaki; Fujiwara, Osamu; Yamanaka, Yukio

62

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

Microsoft Academic Search

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

Peter Breuer; Tadeusz Chmielewski; Piotr Górski; Eduard Konopka

2002-01-01

63

Anisotropy in MHD turbulence due to a mean magnetic field  

Microsoft Academic Search

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

John V. Shebalin; W. H. Matthaeus; David Montgomery

1983-01-01

64

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

NASA Technical Reports Server (NTRS)

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.

Maggiori, D.

1981-01-01

65

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.  

NASA Astrophysics Data System (ADS)

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 seismic deformation on a wide area, near the rupture where the surface spatial displacement gradient becomes too steep, InSAR technique fails due to loss of signal coherence. To complement the deformation mapping in the close neighbourhood of the surface rupture, we propose to compute the line/column pixel offsets on radar images using sub-pixel correlation techniques along with a novel approach . The Sichuan 2008 earthquake surface displacements is expected to be of several metres. Therefore, sub- pixel correlation of 5-10m pixel sized radar images (such as ALOS/ASAR data)is therefore relevant to study the phenomenon. Two shortcomings could hamper the result: 1 - The offsets in the range direction contains a topographic component particularily in the high relief area of the Sichuan province. 2 - The offsets in the azimuth direction could be affected by ionospheric perturbancies, particularily the L - band radar imagery (such as ALOS/PALSAR data) In this paper, firstly we propose a novel approach based on PCA processing to separate surface deformation from image offset due high relief. Secondly , we show that the ionospheric perturbancies do not sistematically mask all the information in the images offset in the azimuth direction, allowing us to help mapping in certain cases the surface rupture as well as the near field azimuth displacement field. The results provide us with a good localization of the surface rupture as well as an estimate of the surface displacement along the seismogenic fault.

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

2008-12-01

66

Stress and displacement fields in the outer wedge induced by megathrust earthquakes  

NASA Astrophysics Data System (ADS)

model plate boundary slip at the outer (oceanward) segment of the megathrust wedge as slip at the base of a two-dimensional elastic wedge, subject to gravity force, with a sloping seafloor at the top, and drag at the bottom from a rigid plate in frictional contact. The stress and displacement fields in the wedge are given analytically as functions of basal frictional coefficient ?e. Unlike either conventional dislocation models (constant slip) or crack models (constant stress drop), our wedge model (constant ?e drop) does not show a stress singularity at the updip toe of the plate boundary. The slip increases, but the stress drop decreases updip along the fault toward the trench axis. There is a minimum stress difference state in the wedge when ?e is varied. By referring to this state (?e = ?ec), the stress state is separated into a horizontally tensile regime (?e < ?ec) and a horizontally compressional regime (?e > ?ec). Slip associated with a ?e drop in the range ?e ? ?ec occurs toward increasing horizontal tension and shear energy. Such earthquakes include tsunami earthquakes occurring in the outer segment and the 2011 great Tohoku-Oki earthquake, which involved both the outer and inner segments, with much larger slip in the outer segment. These earthquakes are characterized by an almost complete drop of basal stress, which brings the wedge into the maximum tensile state, leading to the rare occurrence of thrust aftershocks at the base of the wedge and frequent occurrence of normal fault aftershocks within the wedge.

Fukao, Yoshio; Hori, Takane; Kodaira, Shuichi

2014-05-01

67

Assessment of thermal environment using a thermal manikin in a field environment chamber served by displacement ventilation system  

Microsoft Academic Search

This paper presents a thermal comfort study using a thermal manikin in a field environment chamber served by the Displacement Ventilation (DV) system. The manikin has a female body with 26 individually heated and controlled body segments. The manikin together with subjects was exposed to 3 levels of vertical air temperature gradients, nominally 1, 3 & 5K\\/m, between 0.1 and

K. W. D. Cheong; W. J. Yu; R. Kosonen; K. W. Tham; S. C. Sekhar

2006-01-01

68

Biological effects due to weak magnetic field on plants  

NASA Astrophysics Data System (ADS)

Throughout the evolution process, Earth's magnetic field (MF, about 50 ?T) was a natural component of the environment for living organisms. Biological objects, flying on planned long-term interplanetary missions, would experience much weaker magnetic fields, since galactic MF is known to be 0.1-1 nT. However, the role of weak magnetic fields and their influence on functioning of biological organisms are still insufficiently understood, and is actively studied. Numerous experiments with seedlings of different plant species placed in weak magnetic field have shown that the growth of their primary roots is inhibited during early germination stages in comparison with control. The proliferative activity and cell reproduction in meristem of plant roots are reduced in weak magnetic field. Cell reproductive cycle slows down due to the expansion of G 1 phase in many plant species (and of G 2 phase in flax and lentil roots), while other phases of cell cycle remain relatively stabile. In plant cells exposed to weak magnetic field, the functional activity of genome at early pre-replicate period is shown to decrease. Weak magnetic field causes intensification of protein synthesis and disintegration in plant roots. At ultrastructural level, changes in distribution of condensed chromatin and nucleolus compactization in nuclei, noticeable accumulation of lipid bodies, development of a lytic compartment (vacuoles, cytosegresomes and paramural bodies), and reduction of phytoferritin in plastids in meristem cells were observed in pea roots exposed to weak magnetic field. Mitochondria were found to be very sensitive to weak magnetic field: their size and relative volume in cells increase, matrix becomes electron-transparent, and cristae reduce. Cytochemical studies indicate that cells of plant roots exposed to weak magnetic field show Ca 2+ over-saturation in all organelles and in cytoplasm unlike the control ones. The data presented suggest that prolonged exposures of plants to weak magnetic field may cause different biological effects at the cellular, tissue and organ levels. They may be functionally related to systems that regulate plant metabolism including the intracellular Ca 2+ homeostasis. However, our understanding of very complex fundamental mechanisms and sites of interactions between weak magnetic fields and biological systems is still incomplete and still deserve strong research efforts.

Belyavskaya, N. A.

2004-01-01

69

Field enhancement due to anomalous skin effect inside a target  

SciTech Connect

A new method based on Fourier transformation to study the skin effects is presented. Using this method, the field amplitude in plasma is represented in terms of electric conductivity, and the normal and anomalous skin effects are described through one formula by omitting the plasma dispersion or not. The results are in agreement with other publications [e.g., J. P. Matte and K. Aguenaou, Phys. Rev. A {bold 45}, 2558 (1992)] for equivalent parameters. But for deeper positions inside a target, which have not been studied by others, it is found that the field amplitude is considerably enhanced due to an anomalous skin effect, even for constant collision frequency. In addition, the skin absorptions and some calculations on an anomalous skin effect for different collision frequencies are also presented. {copyright} {ital 1996 American Institute of Physics.}

Ma, G. [Shanghai Institute of Optics and Fine Mechanics, Academia Sinica, P.O. Box 800-211, Shanghai 201800 (People`s Republic of China)] [Shanghai Institute of Optics and Fine Mechanics, Academia Sinica, P.O. Box 800-211, Shanghai 201800 (People`s Republic of China); Tan, W. [Department of Physics, Shanghai University, Shanghai 201800 (People`s Republic of China)] [Department of Physics, Shanghai University, Shanghai 201800 (People`s Republic of China)

1996-01-01

70

Near field 3D displacement of El Mayor-Cupapah Earthquake: A hybrid approach. (Invited)  

NASA Astrophysics Data System (ADS)

The surface rupture produced on April 4th of 2010 by the M 7.2 El Mayor-Cucapah Earthquake is an ideal target to be analyzed by remote sensing techniques. It produced over 100 km of scarps, with vertical and horizontal slip on the order of 2 to 3 m in scarcely vegetated, rugged terrain underlain by mostly igneous rocks. A 3D displacement field (DF) was calculated by matching pre- to post-event airborne LiDAR point clouds through the Iterative Closest Point (ICP) algorithm, which first segments the point clouds into discrete windows, and for each, iteratively converges on a rigid body transformation comprising a translation and a rotation that best aligns the pre- to post-event point clouds. After testing different window sizes, we used a square window 100m a side. The El Mayor-Cucapah LiDAR data sets present special challenges for the ICP technique. The point clouds differ considerably in point density, by ~1:700. This, and the lower precision of the pre-earthquake data, limit the accuracy of the DF results. Despite these issues, the vertical and East-West (E-W) components of the DF from ICP very clearly delineate the trace of the surface rupture, showing east-side down dextral-normal motion in agreement with field measurements and the focal mechanism reported for this event. A systematic error in the LiDAR instrument used for the pre-event survey caused severe distortion of the North-South (N-S) component of the LiDAR returns. After reprocessing the source pre-event point cloud in various ways to correct for the systematic error, a more plausible pattern for the N-S component was obtained for the DF. To have another perspective for the horizontal DF, a subpixel correlation analysis of optical satellite images (SPOT 2.5 m panchromatic images) before and after the earthquake, was performed using the COSI-Corr software. We combined the N-S component from this analysis with the E-W and vertical components of the ICP results, and present the analysis of the resulting DF. We also compare the results from ICP and COSI-Corr individually for each of the horizontal components. Both methods delineate very clearly the rupture, and agree in direction with small discrepancies in magnitude for the horizontal DF. Results from far field deformation measurements obtained from different remote sensing techniques, such as GPS and InSAR, could be fused with the near-field LiDAR and COSI-Corr results to provide a synoptic view of the strain induced by earthquakes such as the El Mayor-Cucapah event.

Hinojosa-Corona, A.; Limon, F. J.; Nissen, E.; Glennie, C. L.; Krishnan, A.; Oskin, M. E.; Arrowsmith, R.; Leprince, S.; Saripalli, S.; Arregui, S. M.; Borsa, A. A.; Kreylos, O.; Banesh, D.; Fletcher, J. M.

2013-12-01

71

Predicting ground electric field due to geomagnetic disturbances  

NASA Astrophysics Data System (ADS)

Electric field induced in the ground by geomagnetic disturbances drives currents in the power transmission grids, telecommunication lines or buried pipelines. These currents, known as Geomagnetically Induced Currents (GIC) are known to cause service disruptions. This effect is maximal at high latitudes due to the presence of strong polar electrojet currents. However both observations and models show that GIC caused by ring current intensifications also pose a risk at low- and mid-latitude locations, where majority of systems vulnerable to GIC are installed. A technique to model geoelectric field induced by the magnetospheric currents in a 3D conductivity model of the Earth is presented by Püthe & Kuvshinov (2013). We extend this work by predicting the induced geoelectric field solely based on Disturbance storm time index (Dst), a measure of ring current activity. Two major components of this effort are 1) Pre-computed 3D electromagnetic response of the ground to a unit magnetopsheric (P01) source and 2) Forecasted Dst data (Temerin & Li, 2002; 2006) from Advanced Composition Explorer (ACE) satellite at the L1 Lagrange point. Depending on the solar wind speed, the Dst forecasts are available approximately 1 hour in advance. The pre-computed response function for a site is multiplied by the Dst data in frequency domain to obtain predicted electric field for that location. Validating our approach, the predicted geoelectric field compares favorably with observed data from an ocean bottom electromagnetic array in the Pacific Ocean during the geomagnetic storm of April 2000. We also compare data from USArray magnetotelluric stations operational during the geomagnetic storm of October 2011. In this case, the results are site specific, with varying degrees of model fit. This indicates the influence of local surface conductivity inhomogeneities on the observed geoelectric data. Averaging data from adjacent stations seems to improve the fit with the prediction.

Nair, M. C.; Püthe, C.; Kuvshinov, A. V.

2013-12-01

72

Decrease of Charge Collection Due to Displacement Damage by Gamma Rays in a 6H-SiC Diode  

Microsoft Academic Search

Charge collection efficiency (CCE) of 6H-SiC diodes was evaluated before and after gamma irradiation using a Co-60 source. After gamma irradiation of 96 Mrad(SiC), CCE at a bias of 150 V decreased from 95% to 70%. The degradation of diffusion length of minority carriers was evaluated from the change in the applied bias dependence of CCE due to gamma irradiation.

Shinobu Onoda; Takeshi Ohshima; Toshio Hirao; Kenta Mishima; Shigeomi Hishiki; Naoya Iwamoto; Kazuhisa Kojima; Katsuyasu Kawano

2007-01-01

73

Immiscible displacement of oil by water in consolidated porous media due to capillary imbibition under ultrasonic waves.  

PubMed

Numerous studies done in the last four decades have demonstrated that acoustic stimulation may enhance recovery in oil reservoirs. This technology is not only technically feasible, but also serves as an economical, environmentally friendly alternative to currently accepted enhanced oil recovery (EOR) method. It requires low capital expenditure, and yields almost immediate improvement without any additional EOR agents. Despite a vast body of empirical and theoretical support, this method lacks sufficient understanding to make meaningful and consistent engineering predictions. This is in part due to the complex nature of the physical processes involved, as well as due to a shortage of fundamental/experimental research. Much of what the authors believe is happening within acoustically stimulated porous media is speculative and theoretical. This paper focuses on the effects of ultrasound on the interfacial forces between immiscible fluids. Capillary (spontaneous) imbibition of an aqueous phase into oil (or air)-saturated Berea sandstone and Indiana limestone samples experiments were conducted. Solutions of water, brine (15,000 and 150,000 ppm NaCl), anionic surfactant (sodium dodecyl diphenyloxide disulfonate), nonionic surfactant (alcohol ethoxylate) and polymer (xanthan gum) were prepared as the aqueous phase. Both counter-current and co-current geometries were tested. Due to the intrinsically unforced, gentle nature of the process, and their strong dependence on wettability, interfacial tension, viscosity and density, such experiments provide valuable insight into some of the governing mechanisms behind ultrasonic stimulation. PMID:17927413

Hamida, Tarek; Babadagli, Tayfun

2007-09-01

74

Local thermal sensation and comfort study in a field environment chamber served by displacement ventilation system in the tropics  

Microsoft Academic Search

This paper presents a study of local thermal sensation (LTS) and comfort in a field environmental chamber (FEC) served by displacement ventilation (DV) system. The FEC, 11.12m (L)×7.53m (W)×2.60m (H), simulates a typical office layout. A total of 60 tropically acclimatized subjects, 30 male and 30 female, were engaged in sedentary office work for 3h. Subjects were exposed to three

K. W. D. Cheong; W. J. Yu; S. C. Sekhar; K. W. Tham; R. Kosonen

2007-01-01

75

[Electromagnetic fields: damage to health due to the nocebo effect].  

PubMed

Environmental exposure to man-made electromagnetic fields has been steadily increasing as the growing demand for electricity and advancing technology have created many artificial sources. Over the course of the past decade, numerous sources of electromagnetic fields have become the focus of health scares, most recently mobile phones and their base stations. The predictable reaction to these health scares has been 'more research'. This comment argues that studies of the possible hazards of low-level electromagnetic fields waste scarce financial resources. Many studies have convincingly excluded detectable tangible health hazards. Bayesian logic predicts that the likelihood of false-positive results will be great in studies lacking a prior hypothesis and using non-specific health states as outcomes. The health hazards due to the maintenance of environmental scares by false-positive studies have been neglected. The nocebo hypothesis states that expectations of sickness cause sickness in the expectant individual. Maintaining anxiety by fostering doubts in gullible populations about the quality ofthe environment they live in may cause serious mental illness. Anxiety caused by health scares is an increasing public health problem, which should be addressed in its own right. PMID:17520846

Bonneux, L

2007-04-28

76

Evaluation of the Compressive Response of Notched Composite Panels using a Full-Field Displacement Measurement System  

NASA Technical Reports Server (NTRS)

An experimental and analytical evaluation of the compressive response of two composite, notched stiffened panels representative of primary composite wing structure is presented. A three-dimensional full-field image correlation technique is used to measure all three displacement components over global and local areas of the test panels. Point-wise and full-field results obtained using the image correlation technique are presented and compared to experimental results and analytical results obtained using nonlinear finite element analysis. Both global and global-local image correlation results are presented and discussed. Results of a simple calibration test of this image correlation technique are also presented.

McGowan, David M.; Ambur, Damodar R.; Hanna, T. Glen; McNeill, Stephen R.

1999-01-01

77

Study of Eastern Canadian Coastal Site Displacement due to Ocean Tide Loading Using a GPS Network in Atlantic Canada  

NASA Astrophysics Data System (ADS)

The continuously operating GPS stations of The Princess of Acadia project, especially the Coast Guard station in Saint John, New Brunswick and the station Digby in Halifax, Nova Scotia, both of which lie in the proximity of highly turbulent waters of Bay of Fundy, are subjected to perpetual movements due to temporally oceanic water mass surface loading of the lithosphere by the ocean tides. If the affects of ocean tide loading are not taken into consideration they can affect high- accuracy positioning especially in the final solutions for height. It is proposed under this project that ocean tidal loading studies be carried out in the area using atleast 1 year of GPS data with varying data processing sessions. Time series would then be extracted from discrete 24-hour solutions for ocean tide loading studies. Data collection in this regard is already in progress and 3 hr and 24 hr solutions are being extracted, cleaned and processed using DIPOP 3.1 software. The role of the tropospheric delay and its effect on height estimates when ocean tide loading effects, whether modeled or ignored, would also be investigated.

Rafiq, M.; Santos, M. C.

2004-05-01

78

Biological effects due to weak magnetic fields on plants  

NASA Astrophysics Data System (ADS)

In the evolution process, living organisms have experienced the action of the Earth's magnetic field (MF) that is a natural component of our environment. It is known that a galactic MF induction does not exceed 0.1 nT, since investigations of weak magnetic field (WMF) effects on biological systems have attracted attention of biologists due to planning long-term space flights to other planets where the magnetizing force is near 10-5 Oe. However, the role of WMF and its influence on organisms' functioning are still insufficiently investigated. A large number of experiments with seedlings of different plant species placed in WMF has found that the growth of their primary roots is inhibited during the early terms of germination in comparison with control. The proliferation activity and cell reproduction are reduced in meristem of plant roots under WMF application. The prolongation of total cell reproductive cycle is registered due to the expansion of G phase in1 different plant species as well as of G phase in flax and lentil roots along with2 relative stability of time parameters of other phases of cell cycle. In plant cells exposed to WMF, the decrease in functional activity of genome at early prereplicate period is shown. WMF causes the intensification in the processes of proteins' synthesis and break-up in plant roots. Qualitative and quantitative changes in protein spectrum in growing and differentiated cells of plant roots exposed to WMF are revealed. At ultrastructural level, there are observed such ultrastructural peculiarities as changes in distribution of condensed chromatin and nucleolus compactization in nuclei, noticeable accumulation of lipid bodies, development of a lytic compartment (vacuoles, cytosegresomes and paramural bodies), and reduction of phytoferritin in plastids in meristem cells of pea roots exposed to WMF. Mitochondria are the most sensitive organelle to WMF application: their size and relative volume in cells increase, matrix is electron-transparent, and cristae reduce. Cytochemical studies indicate that cells of plant roots exposed to WMF show the Ca2 + oversaturation both in all organelles and in a hyaloplasm of the cells unlike the control ones. The data presented suggest that prolonged plant exposures to WMF may cause different biological effects at the cellular, tissue and organ level. They may be functionally related to systems that regulate plant metabolism including the intracellular Ca 2 + homeostasis. The understanding of the fundamental mechanisms and sites of interactions between WMF and biological systems are complex and still deserve strong efforts, particular addressed to basic principles of coupling between field energy and biomolecules.

Belyavskaya, N.

79

Full-field displacement and strain measurement of small complex bony structures with digital speckle pattern interferometry and shearography  

NASA Astrophysics Data System (ADS)

We have developed a simple digital speckle pattern interferometry (DSPI) and shearography setup to measure the displacement and the corresponding strains of small complex bony structures. We choose both optical techniques because we want to obtain very small deformations (+/- 20 ?m) of small objects (+/- 1cm). Furthermore full field and in situ measurements are preferred. We first use a Michelson DSPI arrangement with phase shifting. In this way we can obtain the out-of-plane displacements precisely. Second, shearography is introduced to measure the derivative of the out-ofplane displacement. In this way some intrinsic disadvantages of DSPI can be overcome. We have developed these setups to measure the out-of-plane deformations of (small) bird beaks when realistic external forces are applied. In this way, we have a full field validation measurement to which we can compare the outcome of realistic finite element models. The aim is to determine whether the shape, and not only the size, of the bird beaks are optimized to deal with the biting forces that a species encounters. This quantitative analysis will help biologists to investigate if beak morphology is adapted to feeding habits. Applying the method to the famous evolution model of the Darwin's finches will provide scientific proof of functional evolution. In this paper we will present both the DSPI and shearography setup, a comparison of the performance of both techniques on a simple deflection of a cantilever beam and the first results obtained on loaded bird beaks.

Soons, Joris; Dirckx, Joris J. J.

2010-09-01

80

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

NASA Astrophysics Data System (ADS)

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.

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

81

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

SciTech Connect

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).

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

1981-10-01

82

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

PubMed

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

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

2011-06-01

83

Field Equations due to a Constant Modification in General Relativity  

NASA Astrophysics Data System (ADS)

In this article, by adding a constant to Einstein-Hilbert action, we derive field equations for a non-vacuum space. Also we derive a general solution for these field equations, considering a de Sitter like initial geometric constraint. It is shown that how this additional constant can affect usual gravitational field equations, which are derived from general relativity.

Payandeh, Farrin; Fathi, Mohsen

2013-03-01

84

Suppression of pair creation due to a steady magnetic field  

NASA Astrophysics Data System (ADS)

We investigate the electron-positron pair creation process in a supercritical static electric field in the presence of a static magnetic field that is perpendicular. If both fields vary spatially in one direction the dynamics can be reduced to a set of one-dimensional systems. Using a generalized computational quantum field theoretical procedure, we calculate the time dependence of the spatial density for the created electrons. In the presence of the magnetic field, a significant amount of suppression of pair creation is observed in the simulations and confirmed by an analytical analysis for the limits of short-range fields and long interaction times. This suppression might be interpreted in terms of Pauli blocking by the electron during its return to the creation region as it performs a cyclotronlike motion in the magnetic field.

Su, W.; Jiang, M.; Lv, Z. Q.; Li, Y. J.; Sheng, Z. M.; Grobe, R.; Su, Q.

2012-07-01

85

Microscopic 57 Fe electric-field-gradient and anisotropic mean-squared-displacement tensors: ferrous chloride tetrahydrate  

NASA Astrophysics Data System (ADS)

This paper reports the determination of the electric-field-gradient and mean-squared-displacement tensors in 57Fe symmetry-related sites of bar {1} Laue class in monoclinic FeCl2.4H2O at room temperature by single-crystal Mössbauer spectroscopy. Contrary to all previous work, the mean-squared-displacement matrix (tensor), , is not constrained to be isotropic resulting in the determination of physically meaningful estimates of microscopic (local) electric-field gradient (efg) and tensors. As a consequence of anisotropy in the tensor the absorber recoilless fractions are also anisotropic. As expected of a low-symmetry site, Laue class bar{1} in this case, no two principal axes of the efg and tensors are coaxial, within the combined errors in the two. Further, no principal direction of the efg tensor seems related to bond directions in the unit cell. Within error, and in agreement with an earlier study of sodium nitroprusside, it appears that the tensor principal directions lie close to the crystallographic axes suggesting that they are determined by long wavelength (phonon) vibrations in the crystal rather than by approximate local symmetry about the 57Fe nucleus. Concurrent with the Mössbauer measurements, we determined as part of a new X-ray structural determination, precise atomic displacement parameters (ADPs) leading to an alternative determination of the matrix (tensor). The average of the eigenvalues of the Mössbauer-determined exceeds that of the average of the X-ray-determined eigenvalues by a factor of around 2.2. Assuming isotropic absorber recoilless fractions leads to substantially the same (macroscopic) efg tensor as had been determined in earlier work. Taking 1/3× the trace of the anisotropic absorber recoilless fractions leads to an isotropic value of 0.304 in good agreement with earlier single crystal studies where isotropy was assumed.

Bull, James N.; Fitchett, Christopher M.; Tennant, W. Craighead

2010-06-01

86

Small displacement normal faults as barriers to fluid flow in the complexly faulted anticline of the Wilmington Field  

SciTech Connect

Fault controlled barriers can significantly affect basin flow dynamics. Fault barriers cause compartmentalization of fluid systems, isolating areas of differing fluid pressure, diagenetic processes, and fluid characteristics. Understanding the effects of relatively difficult to detect, small displacement faults on fluid flow is essential when analyzing basin hydrodynamics. The Wilmington structure is a SE plunging asymmetric anticline cut by a series of N-S oriented normal faults in the west and NW-SE oriented normal faults in the east. Fault displacement varies within the field from no displacement at fault tips, to the maxima for each fault, which varies from 10m to 135m. Faults are truncated at a mid Pliocene unconformity above which sediments are neither folded nor faulted. Over 2000 deviated wells penetrate the structure in a sixteen square mile area, often crossing the high angle normal faults. We are first performing a detailed analysis of fault geometry and degree of offset from well logs and a 3D seismic survey. A core recovered through the Temple Avenue fault shows slip over a ten meter zone without a dominant slip plane. Well logs also indicate a zone of deformation associated with the fault. A barrier was present, prior to development, across the fault where offset is less than the thickness of the offset reservoir unit, indicating fault zone properties are responsible for formation of the barrier. Fault barriers are established from offset oil-water contacts, pressure, and production surveys. Preliminary analysis of pressure data shows variability across the field and a lack of fluid communication over short distances.

Teas, P.A.; Thornburg, J. (Univ. of Southern California, Santa Cruz, CA (United States))

1996-01-01

87

Electric field-directed cell shape changes, displacement, and cytoskeletal reorganization are calcium dependent  

Microsoft Academic Search

C3H\\/10T1\\/2 mouse embryo fibroblasts were stimulated by a steady electric field ranging up to 10 V\\/cm. Some cells elongated and aligned perpendic- ular to the field direction. A preferential positional shift toward the cathode was observed which was in- hibited by the calcium channel blocker D-600 and the calmodulin antagonist trifluoperazine. Rhodamine- phalloidin labeling of actin filaments revealed a field-

Edward K. Onuma; Sek-Wen Hui

1988-01-01

88

Simultaneous mapping of the unsteady flow fields by Particle Displacement Velocimetry (PDV)  

NASA Technical Reports Server (NTRS)

Current experimental and computational techniques must be improved in order to advance the prediction capability of the longitudinal vortical flows shed by underwater vehicles. The generation, development, and breakdown mechanisms of the shed vortices at high Reynolds numbers are not fully understood. The ability to measure hull separated vortices associated with vehicle maneuvering does not exist at present. The existing point-by-point measurement techniques can only capture approximately the large 'mean' eddies but fail to meet the dynamics of small vortices during the initial stage of generation. A new technique, which offers a previously unavailable capability to measure the unsteady cross-flow distribution in the plane of the laser light sheet, is called Particle Displacement Velocimetry (PDV). PDV consists of illuminating a thin section of the flowfield with a pulsed laser. The water is seeded with microscopic, neutrally buoyant particles containing imbedded fluorescing dye which responds with intense spontaneous fluorescence with the illuminated section. The seeded particles in the vortical flow structure shed by the underwater vehicle are illuminated by the pulse laser and the corresponding particle traces are recorded in a single photographic frame. Two distinct approaches were utilized for determining the velocity distribution from the particle traces. The first method is based on matching the traces of the same particle and measuring the distance between them. The direction of the flow can be identified by keeping one of the pulses longer than the other. The second method is based on selecting a small window within the image and finding the mean shift of all the particles within that region. The computation of the auto-correlation of the intensity distribution within the selected sample window is used to determine the mean displacement of particles. The direction of the flow is identified by varying the intensity of the laser light between pulses. Considerable computational resources are required to compute the auto-correction of the intensity distribution. Parallel processing will be employed to speed up the data reduction. A few examples of measured unsteady vortical flow structures shed by the underwater vehicles will be presented.

Huang, Thomas T.; Fry, David J.; Liu, Han-Lieh; Katz, Joseph; Fu, Thomas C.

1992-01-01

89

Reorientation of global coronal magnetic fields due to differential rotation  

Microsoft Academic Search

It is discussed how differential rotation may serve as the driving force to produce large scale reorientations of magnetic fields in the solar atmosphere, drastically altering the three-dimensional global structure of the corona and the distribution of filaments. No changes in magnetic flux from the photosphere are required, only a reconnection of existing coronal field lines. A process is suggested

S. F. Hansen; R. T. Hansen

1977-01-01

90

MGS magnetic fields and electron reflectometer investigation: discovery of paleomagnetic fields due to crustal remanence  

NASA Astrophysics Data System (ADS)

The MGS MAG/ER investigation provides vector measurements of the magnetic field and the ionospheric electron density near periapsis. The instrumentation consists of twin triaxial fluxgate magnetometers and a ``top hat'' electrostatic analyzer of electrons in the energy range of 1 eV to 20 keV. Results include extensive mapping of the detached bow shock wave in the solar wind, the nature and structure of the ionopause and magnetic pile-up boundaries. The most surprising result is the discovery of localized magnetic fields of planetary origin, presumably due to remanent crustal magnetization. Maximum fields measured while below the ionosphere exceed 300 nT. We present an initial study of one of these very localized fields and extrapolations to the Martian surface in the Acidalia planitia.

Ness, N. F.; Acuña, M. H.; Connerney, J.; Wasilewski, P.; Mazelle, C.; Sauvaud, J.; Vignes, D.; D'Uston, C.; Reme, H.; Lin, R.; Mitchell, D. L.; McFadden, J.; Curtis, D.; Cloutier, P.; Bauer, S. J.

1999-01-01

91

V-fields due latest monitoring, control technology  

SciTech Connect

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.

Not Available

1987-06-29

92

Modeling surface deformation due to CO2 injection at an enhanced oil recovery field in Texas  

NASA Astrophysics Data System (ADS)

The Geodesy Laboratory at the University of South Florida has operated 3 C-GPS stations at an enhanced oil recovery field in Texas since October 2011. Our GPS sites recorded vertical uplift during the injection phase when the reservoir was initially pressurized, and localized subsidence in phase with reservoir pressure after oil extraction started. In this study, we use analytical and numerical models to better understand the small-scale surface deformation observed by GPS due to CO2 injection. First, we use an analytical model of a pressurized horizontal circular crack in an elastic half-space to fit the surface deformation data. Then, constrained by the analytical modeling results, we develop a poroelastic Finite Element Model (FEM) to investigate the influence of reservoir geometry and overlying stratigraphy on surface displacement. A sensitivity study is carried out to understand the effects of realistic geometry and material properties on surface deformation. Our preliminary results show that a poroelastic FEM can explain the location-dependant time delay between the injection and surface response.

Yang, Q.; Abdollahzadeh, M.; Dixon, T. H.; Malservisi, R.; Hosseini, S.

2013-12-01

93

Examination of Au, Cu, and Al contacts in organic field-effect transistors via displacement current measurements  

NASA Astrophysics Data System (ADS)

Displacement current measurements (DCM) on long-channel capacitors (LCCs) were used to examine carrier injection and extraction processes in organic field-effect transistors (OFETs). An LCC can be seen as an OFET with one channel contact removed and the conducting channel elongated to millimeter range. While carrier injection and extraction processes occur simultaneously in OFETs during traditional DC measurements, these two processes can be examined separately with LCCs and DCMs. In addition, the numbers of injected, extracted, and trapped carriers can be determined by integrating the displacement current with respect to time. Pentacene LCCs with Au, Cu, and Al contacts were fabricated. Surprisingly, it was found that more carriers were trapped in the Au devices than in the Cu devices even though the pentacene film and dielectric layers were essentially identical. We propose that carrier trapping in the long channel of the Au devices is indirectly caused by the deep trap states at the pentacene-dielectric interface in the contact region generated by Au penetration. In addition, ambipolar injection and transport were observed in an LCC with an Al contact and a PMMA buffer layer between pentacene and SiO2.

Liang, Yan; Chang, Hsiu-Chuang; Paul Ruden, P.; Daniel Frisbie, C.

2011-09-01

94

Field-free molecular orientation control due to ramped pulses  

NASA Astrophysics Data System (ADS)

We study theoretically nonadiabatic rotational excitation dynamics and field-free orientation of a polar molecule in a ramped laser field by using time-dependent quantum mechanics. By adjusting the time of rising and falling edge of the ramped pulse, the population of the specific rotational states can be controlled. We describe the effect of the different shaped pulses (ramp, Gaussian, square pulses) in controlling the molecular dynamics. Further, it is also shown that enhancement or suppression of molecular orientation can be coherently manipulated by controlling various laser parameters like intensity, time delay, and rotational temperature, etc.

Arya, Urvashi; Prasad, Vinod

2013-03-01

95

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

Microsoft Academic Search

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

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

96

Reorientation of global coronal magnetic fields due to differential rotation  

Microsoft Academic Search

Because of the progressive decrease in rotation rate of the solar plasma at increasing latitudes, the photospheric foot-points of large-scale closed magnetic structures in the corona, which are originally widely separated in longitude, may ultimately be brought into proximity. Magnetic mergers and reconnections between magnetic fields of opposite polarity are presumed to occur, producing major structural changes in the corona

Shirley F. Hansen; Richard T. Hansen

1977-01-01

97

Spin Hall effect in graphene due to random Rashba field  

NASA Astrophysics Data System (ADS)

Spin Hall effect due to random Rashba spin-orbit coupling in the two-dimensional honeycomb lattice of carbon atoms (graphene) is considered theoretically. Using the Green function method and diagrammatic technique we show that fluctuations of the Rashba interaction around zero average value give rise to nonzero spin Hall conductivity. Generally, the conductivity is not universal, but depends on the ratio of the total momentum and spin-flip relaxation rates.

Dyrda?, A.; Barna?, J.

2012-10-01

98

Estimation of limit angle using laminated displacement discontinuity analysis in the Soma coal field, Western Turkey  

Microsoft Academic Search

Determination of the limit angle at the Manisa-Soma-Eynez coal field, a major coal production area in Turkey, is difficult because of the presence of a landslide caused by the waste from a neighboring open-pit site being dumped over the underground mine at the Soma-Eynez basin. In fact, it is not possible to determine the effect of extraction on the surface

C. O. Aksoy; H. Kose; T. Onargan; Y. Koca; K. Heasley

2004-01-01

99

Broadband electrostatic noise due to field-aligned currents  

NASA Technical Reports Server (NTRS)

There are observations of broadband electrostatic noise in the plasma-sheet boundary layer that are associated with field-aligned currents (electron beams), which often have an upper cutoff frequency above the electron plasma frequency. In this paper linear theory and numerical simulations are used to study instabilities caused by an electron beam in a thermally mixed plasma. It is shown that two instabilities, the electron acoustic and electron-ion instabilities, can combine to form a broadband wave spectrum that rapidly destroys the electron beam.

Schriver, David; Ashour-Abdalla, Maha

1989-01-01

100

Electromagnetic fields due to dipole antennas over stratified anisotropic media.  

NASA Technical Reports Server (NTRS)

Solutions to the problem of radiation of dipole antennas in the presence of a stratified anisotropic media are facilitated by decomposing a general wave field into transverse magnetic (TM) and transverse electric (TE) modes. Employing the propagation matrices, wave amplitudes in any region are related to those in any other regions. The reflection coefficients, which embed all the information about the geometrical configuration and the physical constituents of the medium, are obtained in closed form. In view of the general formulation, various special cases are discussed.

Kong, J. A.

1972-01-01

101

Characterization of guided acoustic waves in an arbitrary direction with full-field instantaneous maps of the acoustic displacement  

NASA Astrophysics Data System (ADS)

The full-field optical measurement of guided acoustic waves presents important advantages derived from the capability to map the acoustic field in a two dimensional region, so that acoustic information over a large area can be retrieved with each measurement. In this work, we introduce an extension of the well-established two dimensional spatio-temporal Fourier transform method to calculate the frequency spectrum of guided acoustic waves. For this, we take advantage of the unique capability of a self-developed double-pulsed television holography system to acquire the acoustic displacement field in two spatial dimensions and time. Then, the spatio-temporal Fourier transform method is expanded to three dimensions according to the nature of the experimental data, so that the frequency spectrum of the waves propagating in an arbitrary direction can be calculated. The method is tested experimentally by generating narrowband Lamb waves in an aluminium plate with a piezoelectric transducer. The good agreement between the theoretical and experimental spectra in a broad zone anticipates the applicability of the method to characterize guided acoustic waves as a function of the propagation direction in materials or structures presenting anisotropic propagation behaviour.

Luís Deán-Ben, X.; Trillo, Cristina; Doval, Ángel F.; Fernández, José L.

2012-08-01

102

Highly localized strain fields due to planar defects in epitaxial SrBi2Nb2O9 thin films  

NASA Astrophysics Data System (ADS)

Thin films of (00l) oriented SrBi2Nb2O9 epitaxially grown on SrTiO3 by sol-gel spin coating have been studied by means of high-resolution x-ray diffraction reciprocal space mapping. It is shown that these materials contain highly localized heterogeneous strain fields due to imperfect stacking faults (i.e., faults that do not propagate throughout the crystallites building up the film). In the film plane, the strain fields are confined to 11 nm wide regions and characterized by a vertical displacement of 0.18c (where c is the cell parameter) showing that the stacking faults are mainly composed of one additional (or missing) perovskite layer. Prolonged thermal annealing at 700 °C strongly reduces the density of stacking faults and yields a more uniform strain distribution within the film volume without inducing significant grain growth.

Boulle, A.; Guinebretière, R.; Dauger, A.

2005-04-01

103

Description and field performance of the Walker Branch throughfall displacement experiment: 1993--1996  

SciTech Connect

The authors are conducting a large-scale manipulative field experiment in an upland oak forest on the Walker Branch Watershed in eastern Tennessee to identify important ecosystem responses that might result from future precipitation changes. The manipulation of soil water content is being implemented by a gravity-driven transfer of throughfall from one 6400-m{sup 2} treatment plot to another. Throughfall is intercepted in {approx}1850 subcanopy troughs suspended above the forest floor of the dry plot and transferred by gravity flow across an ambient plot for subsequent distribution onto the wet treatment plot. Soil water content is being monitored at two depths with time domain reflectometers at 310 sampling locations across the site. The experimental system is able to produce statistically significant differences in soil water content in years having both dry and wet conditions. Maximum soil water content differentials between wet and dry plots in the 0- to 0.35-m horizon were 8 to 10% during summers with abundant precipitation and 3 to 5% during drought periods. Treatment impacts on soil water potential were restricted to the surface soil layer. Comparisons of pre- and post-installation soil and litter temperature measurements showed the ability of the experimental design to produce changes in soil water content and water potential without creating large artifacts in the forest understory environment.

Hanson, P.J.; Todd, D.E.; Huston, M.A. [Oak Ridge National lab., TN (United States). Environmental Sciences Div.; Joslin, J.D. [Tennessee Valley Authority, Norris, TN (United States); Croker, J.L.; Auge, R.M. [Univ. of Tennessee, Knoxville, TN (United States). Inst. of Agriculture

1998-04-01

104

Application of the digital volume correlation technique for the measurement of displacement and strain fields in bone: a literature review.  

PubMed

Digital volume correlation (DVC) provides experimental measurements of displacements and strains throughout the interior of porous materials such as trabecular bone. It can provide full-field continuum- and tissue-level measurements, desirable for validation of finite element models, by comparing image volumes from subsequent µCT scans of a sample in unloaded and loaded states. Since the first application of DVC for measurement of strain in bone tissue, subsequent reports of its application to trabecular bone cores up to whole bones have appeared within the literature. An "optimal" set of procedures capable of precise and accurate measurements of strain, however, still remains unclear, and a systematic review focussing explicitly on the increasing number of DVC algorithms applied to bone or structurally similar materials is currently unavailable. This review investigates the effects of individual parameters reported within individual studies, allowing to make recommendations for suggesting algorithms capable of achieving high accuracy and precision in displacement and strain measurements. These recommendations suggest use of subsets that are sufficiently large to encompass unique datasets (e.g. subsets of 500 µm edge length when applied to human trabecular bone cores, such as cores 10mm in height and 5mm in diameter, scanned at 15 µm voxel size), a shape function that uses full affine transformations (translation, rotation, normal strain and shear strain), the robust normalized cross-correlation coefficient objective function, and high-order interpolation schemes. As these employ computationally burdensome algorithms, researchers need to determine whether they have the necessary computational resources or time to adopt such strategies. As each algorithm is suitable for parallel programming however, the adoption of high precision techniques may become more prevalent in the future. PMID:24529357

Roberts, Bryant C; Perilli, Egon; Reynolds, Karen J

2014-03-21

105

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)

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.

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

2013-02-01

106

Crack embrittlement displacement fields  

NASA Astrophysics Data System (ADS)

When using precracked fracture toughness specimens to study liquid metal embrittlement is has been necessary to estimate the crack length and applied load as a function of time. These parameters are sometimes difficult to obtain and accuracy is often questionable. Further, these data provide the basis for calculating crack growth rate (d a/d t) as a function of applied stress intensity factor KI. This paper presents an approach based on use of moiré interferometry in conjunction with fracture toughness specimens and acoustic emission techniques to study liquid mercury amalgam embrittlement of 6061-T 6 aluminum. Moiré interferometry provides a unique method for obtaining KI, at the crack tip, without requiring knowledge of crack length and load. This paper describes the approach and provides an evaluation based on test results.

Epstein, J. S.; Reuter, W. G.; Keiser, D. D.

107

Near-Field High-Resolution Seismic, Strain and Displacement Measurements for Earthquake Source Studies in Deep Mines in South Africa  

Microsoft Academic Search

Unique access to information on the physics of the earthquake source (earthquake nucleation, fault rupture, heat generation, stress state, seismic wave propagation, fault displacement, material properties and particularly changes in some of these parameters prior to rupture) exists in the near-field of mining-induced earthquakes in deep gold mines in South Africa. The new NSF funded Natural Earthquake Laboratory in South

M. J. Johnston; Z. Reches; G. van Aswegan; A. McGarr; D. Lockner; E. Sellers; Y. Ben Zion; C. Williams

2004-01-01

108

An algorithm and a computer program for the three-term asymptotic expansion of elastic-plastic crack tip stress and displacement fields  

Microsoft Academic Search

Study of stress and displacement fields in the microstructurally significant region near the tip of a crack in an elastic-plastic body is important for establishing multi-parameter fracture criteria. A mathematical tool for such study is a multi-term asymptotic expansion of crack tip fields. This paper presents a methodology and a FORTRAN program for the determination of three-term asymptotic stress and

G. P. Nikishkov

1995-01-01

109

A distance to dose difference tool for estimating the required spatial accuracy of a displacement vector field  

PubMed Central

Purpose: To introduce a tool, termed distance to dose difference (DTD), which estimates the required spatial accuracy of displacement vector fields (DVFs) used for mapping four dimensional dose values. Methods: Dose mapping maps dose values from an irradiated geometry to a reference geometry. DVF errors result in dose being mapped from the wrong spatial location in the irradiated geometry, with a dose error equal to the dose difference between the error-free and sampled spatial locations. The DTD, defined as the distance to observe a given dose difference in the irradiated geometry, quantifies the permitted DVF error to ensure a prespecified desired dose mapping accuracy is achieved. To demonstrate the DTD, a treatment plan is generated with a 5 mm internal target volume-to-planning target volume margin for an intensity modulated radiation therapy lung patient. The DTD is evaluated for mapping dose from the end of inhale image with a dose error tolerance of 3.30 Gy, which equals 5% of the 66 Gy prescription dose. The DTD is loaded into the treatment planning system to visualize positional dependencies of permissible DVF errors overlaid on the patient’s anatomy and DTD-volume-histograms are generated. Results: DTD values vary with location in the patient anatomy. For the test case, DTD analysis indicates that accurate DVFs (?1 mm) are required in high dose gradient regions while large DVF errors (>20 mm) are acceptable in low dose gradient regions. Within the clinical target volume (CTV), tolerated DVF uncertainties range from 1 to 12 mm, depending on location. Ninety percent of the CTV volume had DTD values less than 4 mm. Conclusions: The DVF spatial accuracy required to meet a dose mapping accuracy tolerance depends on the spatial location within the dose distribution. For dose mapping, DVFs accuracy must be highest in dose gradient regions, while less accurate DVFs can be tolerated in uniform dose regions. The DTD tool provides a useful first estimate of DVF required spatial accuracy.

Saleh-Sayah, Nahla K.; Weiss, Elisabeth; Salguero, Francisco J.; Siebers, Jeffrey V.

2011-01-01

110

Electrostatic Ion Cyclotron Instability due to a Nonuniform Electric Field Perpendicular to the External Magnetic Field.  

National Technical Information Service (NTIS)

We suggest a new mechanism that can destabilize the kinetic ion cyclotron waves in the presence of a nonuniform electric field perpendicular to the uniform ambient magnetic field. In the absence of the electric field the mode energy is positive while in t...

G. Ganguli Y. C. Lee P. Palmadesso

1985-01-01

111

Displacement measurements of highway bridges using digital image correlation methods  

NASA Astrophysics Data System (ADS)

Digital image correlation methods (DICMs) are important tools in experimental solid mechanics. DICM is becoming very versatile and cost effective due to the dramatic improvement over the digital cameras. Current study applies DICMs to displacement measurements of full-scale concrete beams. Computer programs are implemented and tested against the contact measurements using a linear variable differential transformer (LVDT). The calculated displacements agree with the LVDT measurements that the difference is mostly within 3%. The DICM programs produce similar displacement fields to those obtained using two computer codes written by other researchers. The DICM programs compute a singlepoint in merely seconds while completing the displacement calculation for a whole-field region of one mega pixels in one hour. Additional tests on the vertical displacement of a highway bridge also achieve a reasonable result which can be extended to health monitoring of bridges.

Chiang, Chih-Hung; Shih, Ming-Hsiang; Chen, Welltin; Yu, Chih-Peng

2011-08-01

112

Thermal effect of temperature gradient in a field environment chamber served by displacement ventilation system in the tropics  

Microsoft Academic Search

The effect of vertical air temperature gradient on overall and local thermal comfort at different overall thermal sensations and room air temperatures (at 0.6m height) was investigated in a room served by displacement ventilation system. Sixty tropically acclimatized subjects performed sedentary office work for a period of 3h during each session of the experiment. Nominal vertical air temperature gradients between

W. J. Yu; K. W. D. Cheong; K. W. Tham; S. C. Sekhar; R. Kosonen

2007-01-01

113

Solution for the stress and displacement fields in the vicinity of a V-notch of negative wedge angle in plane problems of elasticity  

Microsoft Academic Search

The method is presented of modeling displacement, strain and stress fields in the two-dimensional problems of elasticity considering the presence of V-shaped notches with any positive or negative angle. The analytical expressions for stress and strain states at the tip of a V-notch were obtained for two cases of deformation: opening (mode I) and sliding (mode II). This was achieved

Andrzej Seweryn; Janislaw Zwolinski

1993-01-01

114

A study of perceived air quality and sick building syndrome in a field environment chamber served by displacement ventilation system in the tropics  

Microsoft Academic Search

This paper presents a study of Perceived Air Quality (PAQ) and Sick Building Syndrome (SBS) using tropically acclimatized subjects in a Field Environmental Chamber (FEC) served by Displacement Ventilation (DV) system. The FEC, 11.12m (L)×7.53m (W)×2.60m (H), simulates a typical office layout. A total of 60 subjects, 30 males and 30 females, were engaged in sedentary office work for 3h.

K. W. D. Cheong; W. J. Yu; K. W. Tham; S. C. Sekhar; R. Kosonen

2006-01-01

115

Internal displacement in Burma.  

PubMed

The internal displacement of populations in Burma is not a new phenomenon. Displacement is caused by numerous factors. Not all of it is due to outright violence, but much is a consequence of misguided social and economic development initiatives. Efforts to consolidate the state by assimilating populations in government-controlled areas by military authorities on the one hand, while brokering cease-fires with non-state actors on the other, has uprooted civilian populations throughout the country. Very few areas in which internally displaced persons (IDPs) are found are not facing social turmoil within a climate of impunity. Humanitarian access to IDP populations remains extremely problematic. While relatively little information has been collected, assistance has been focused on targeting accessible groups. International concern within Burma has couched the problems of displacement within general development modalities, while international attention along its borders has sought to contain displacement. With the exception of several recent initiatives, few approaches have gone beyond assistance and engaged in the prevention or protection of the displaced. PMID:11026156

Lanjouw, S; Mortimer, G; Bamforth, V

2000-09-01

116

Displaced Supersymmetry  

NASA Astrophysics Data System (ADS)

The apparent absence of light superpartners at the LHC strongly constrains the viability of the MSSM as a solution to the hierarchy problem. These constraints can be significantly alleviated by R-parity violation (RPV). Bilinear R-parity violation, with the single operator LH u , does not require any special flavor structure and can be naturally embedded in a GUT while avoiding constraints from proton decay (unlike baryon-number-violating RPV). The LSP in this scenario can be naturally long-lived, giving rise to displaced vertices. Many collider searches, particularly those selecting b-jets or leptons, are insensitive to events with such detector-scale displaced decays owing to cuts on track quality and impact parameter. We demonstrate that for decay lengths in the window ˜1-103 mm, constraints on superpartner masses can be as low as ˜450 GeV for squarks and ˜40 GeV for LSPs. In some parts of parameter space light LSPs can dominate the Higgs decay width, hiding the Higgs from existing searches. This framework motivates collider searches for detector-scale displaced vertices. LHCb may be ideally suited to trigger on such events, while ATLAS and CMS may need to trigger on missing energy or multijet signatures.

Graham, Peter W.; Kaplan, David E.; Rajendran, Surjeet; Saraswat, Prashant

2012-07-01

117

Modeling in-plane and out-of-plane displacement fields in pull-off tests on FRP strips  

Microsoft Academic Search

The present paper deals with modeling FRP strips bonded to concrete blocks and tested in pull-off. The investigation starts from the experimental observations obtained by means of an optical image-correlation measurement system which is able to monitor the 3D displacement components of a fine mesh of points on the surface of both the FRP strip and concrete block. Thus, refined

Enzo Martinelli; Christoph Czaderski; Masoud Motavalli

2011-01-01

118

Novel Theoretical and Numerical Methods for the Computation of Electromagnetic Fields due to Current Sources  

NASA Astrophysics Data System (ADS)

In this dissertation, series expansions are developed for the Incomplete Lipschitz-Hankel integrals (ILHIs) Je_0(a,z) and Ye_0(a,z). These expansions are obtained using the Laplace transform technique together with the theory of contour integration. These special functions are encountered in the solutions for numerous problems in electromagnetics. For example, ILHIs are used in this dissertation to obtain exact, closed-form field expressions for a semi-infinite traveling wave current filament in homogeneous space. They are also used together with the steepest descent technique to obtain expressions for the electromagnetic fields due to a semi-infinite traveling wave current filament above a half space. Superposition of these fields are used to obtain the fields due to a finite length wire carrying a traveling wave current. In addition, the ILHIs are also encountered when Prony's method is used to obtain field expressions for a vertical electric dipole source over earth.

Mechaik, Mehdi Mohamad

119

MGS magnetic fields and electron reflectometer investigation: Discovery of paleomagnetic fields due to crustal remanence  

Microsoft Academic Search

The MGS MAG\\/ER investigation provides vector measurements of the magnetic field and the ionospheric electron density near periapsis. The instrumentation consists of twin triaxial fluxgate magnetometers and a “top hat” electrostatic analyzer of electrons in the energy range of 1 eV to 20 keV. Results include extensive mapping of the detached bow shock wave in the solar wind, the nature

N. F. Ness; M. H. Acuña; J. Connerney; P. Wasilewski; C. Mazelle; J. Sauvaud; D. Vignes; C. d'Uston; H. Reme; R. Lin; D. L. Mitchell; J. McFadden; D. Curtis; P. Cloutier; S. J. Bauer

1999-01-01

120

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

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

121

Lattice-dynamical evaluation of atomic displacement parameters for coesite from an empirical force field with implications on thermodynamic properties  

Microsoft Academic Search

Using empirical potentials derived from fitting the vibrational frequencies of a group of silicates and oxides (not including\\u000a the mineral under study), a Born-von Karman rigid-ion lattice-dynamical model has been applied to the whole Brillouin zone\\u000a in coesite. The atomic anisotropic displacement parameters (A.D.P.s) derived from accurate crystal-structure refinement at\\u000a room temperature and at 15 K agree very well with

T. Pilati; F. Demartin; C. M. Gramaccioli

1998-01-01

122

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

SciTech Connect

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.

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

1986-06-01

123

Low-field large magnetostriction in DyCo2 due to field-induced rearrangement of tetragonal variants  

NASA Astrophysics Data System (ADS)

The synchrotron high-energy x-ray diffraction was used to trace directly the structural evolution of polycrystalline DyCo2, one of RT2 (R = rare earth, T = Co, Fe) compounds with Laves phase, as a function of temperature and magnetic field. When the DyCo2 compound was zero-field cooled down below TC, the high temperature cubic lattice was distorted into tetragonal structure, associated with an expansion of unit cell volume. It was further found that the large magnetostriction at low magnetic field was due to the preferential rearrangement of tetragonal variants in the low-temperature ferrimagnetic phase. Our finding of the field-driven preferential selection of tetragonal variants in the polycrystalline materials provides important clues for exploring the advanced ferromagnetic alloys with a large magnetostriction at low field.

Nie, Zhihua; Yang, Sen; Wang, Yandong; Wang, Zilong; Liu, Dongmei; Ren, Yang

2013-09-01

124

Young displacements on the Atacama Fault System, northern Chile from field observations and cosmogenic 21Ne concentrations  

NASA Astrophysics Data System (ADS)

We present the first numerical age constraint for young deformation of the Atacama Fault System (AFS) in northern Chile. The young activity of the AFS is expressed by several fault scarps which affects alluvial fan sediments of the eastern side of the Coastal Cordillera (23°30'-23°42'S). Detailed mapping of alluvial fans reveals a complex relationship between fault motion, erosion and alluvial fan development. An older group of alluvial fans became inactive prior to the scarp formation. Younger alluvial fans, arising directly from feeder channels and entrenched in the fault scarps, posts date the scarp formation. The youngest slip on the AFS is recorded by headward eroding channels entrenched across the scarp which are in turn displaced vertically 0.3-0.5 m by the fault. Quartz fragments in four sites on the older inactive fan group were analyzed for cosmogenic 21Ne concentrations yielding an average age of 424 ± 151 ka, the upper limit for the recent activity of the fault. Combined with the height of fault scarp, we calculate a 0.01 mm/yr minimum vertical fault slip rate. Thus young displacement on the AFS is Quaternary in age and confined to the late Pleistocene.

GonzáLez L., Gabriel; Dunai, Tibor; Carrizo, Daniel; Allmendinger, Richard

2006-06-01

125

Changes in the natural frequency of a ferromagnetic rod in a magnetic field due to magnetoelastic interaction  

Microsoft Academic Search

Based on the magnetoelastic generalized variational principle and Hamilton’s principle, a dynamic theoretical model characterizing\\u000a the magnetoelastic interaction of a soft ferromagnetic medium in an applied magnetic field is developed in this paper. From\\u000a the variational manipulation of magnetic scale potential and elastic displacement, all the fundamental equations for the magnetic\\u000a field and mechanical deformation, as well as the magnetic

Xing-zhe Wang

2008-01-01

126

Shot noise of low energy electron field emission due to Klein tunneling  

NASA Astrophysics Data System (ADS)

This paper investigates the property of shot noise for low energy electron field emission from a single-layer vertically aligned graphene sheet assuming the emission process is due to Klein tunneling. In our model, we use two different methods (relativistic WKB and transfer matrix) to calculate the transmission coefficient and thus obtain the Fano factor (? or suppression of shot noise) as a function of temperature T, Fermi energy Ef, and local electric field F. It is found that a universal maximum value of about ? = 1/3 can be reached at low temperature limit within a certain range of local electric field.

Sun, S.; Ang, L. K.

2012-07-01

127

Compensatory saccades made to remembered targets following orbital displacement by electrically stimulating the dorsomedial frontal cortex or frontal eye fields of primates.  

PubMed

If the eye-position signal during visually-evoked saccades is dependent on the dorsomedial frontal cortex (DMFC), one would expect that saccades generated to briefly presented visual targets would be disrupted after displacement of the eyes via electrical stimulation of this cortical area. Compared are compensatory saccades evoked to brief targets following stimulation of the DMFC and frontal eye fields (FEF). Compensatory saccades produced to brief targets following perturbation via the DMFC were not affected. Accordingly, electrical stimulation of the DMFC does not disrupt the eye-position signal during the execution of visually-evoked saccades. PMID:8842402

Tehovnik, E J; Sommer, M A

1996-07-15

128

Field-induced optical nonlinearity due to virtual transitions in semiconductor quantum-well structures  

Microsoft Academic Search

A new concept of optical nonlinearity due to virtual transitions in quantum-well structures in an electric field, named virtual charge-induced optical nonlinearity, is proposed, and some examples of theoretical results on the nonlinearity are given. The switching time of the nonlinearity is expected to be extremely short, 100 fs. The nonlinearity seems to be observable and quite useful for the

Masamichi Yamanishi

1987-01-01

129

Model based estimation of image depth and displacement  

NASA Technical Reports Server (NTRS)

Passive depth and displacement map determinations have become an important part of computer vision processing. Applications that make use of this type of information include autonomous navigation, robotic assembly, image sequence compression, structure identification, and 3-D motion estimation. With the reliance of such systems on visual image characteristics, a need to overcome image degradations, such as random image-capture noise, motion, and quantization effects, is clearly necessary. Many depth and displacement estimation algorithms also introduce additional distortions due to the gradient operations performed on the noisy intensity images. These degradations can limit the accuracy and reliability of the displacement or depth information extracted from such sequences. Recognizing the previously stated conditions, a new method to model and estimate a restored depth or displacement field is presented. Once a model has been established, the field can be filtered using currently established multidimensional algorithms. In particular, the reduced order model Kalman filter (ROMKF), which has been shown to be an effective tool in the reduction of image intensity distortions, was applied to the computed displacement fields. Results of the application of this model show significant improvements on the restored field. Previous attempts at restoring the depth or displacement fields assumed homogeneous characteristics which resulted in the smoothing of discontinuities. In these situations, edges were lost. An adaptive model parameter selection method is provided that maintains sharp edge boundaries in the restored field. This has been successfully applied to images representative of robotic scenarios. In order to accommodate image sequences, the standard 2-D ROMKF model is extended into 3-D by the incorporation of a deterministic component based on previously restored fields. The inclusion of past depth and displacement fields allows a means of incorporating the temporal information into the restoration process. A summary on the conditions that indicate which type of filtering should be applied to a field is provided.

Damour, Kevin T.

1992-01-01

130

Analytic models of the displacements and stresses in a long basin due to varying hydrological loading, with application to hydrogeological geodesy  

NASA Astrophysics Data System (ADS)

A seasonally sinusoidal signal often dominates geodetic data, and it has been shown that, globally, ~40% of this signal is due to periodic mass redistributions (Dong et al., 2002). One particular component of these mass redistributions is the effect of groundwater loading. This source of deformation is commonly modeled using the surface loading Greens function, e.g., by assuming that deformation is imposed by a normal traction boundary condition applied at the surface of the earth (Malvern, 1967; Farrell, 1972). We present an alternate strategy which assumes that there are seasonal fluctuations in pore fluid pressure that are uniformly distributed throughout the hydrologically active elastic upper crust. While this model is probably more close to the physical truth, it is not necessarily apparent a priori that the difference between these two models is significant. We present a collection of new analytic models that attempt to model seasonal groundwater induced deformation for several commonly occurring cases. The models consist of an infinitely long (e.g., under plane strain) poroelastic solid that is polygonal in cross section, such as a fault bounded basin. To solve the relevant two dimensional mixed boundary value problem, we use the complex variable method in concert with conformal mapping and analytic continuation (England, 2003). This approach benefits from being quite general, naturally suited for the mixed boundary value problem, and not requiring a strong prior hypothesis concerning the form of the solution. Results are confirmed using a numerical boundary element software. As an exemplary case study, we use PS-InSAR data from the Bay Area, CA, to observe seasonal surface deformation. Subsurface structure in this area, known from seismic studies (Wentworth et al., 2010), provides a uniquely suited natural laboratory for discerning between the models discussed. As the Bay Area is a region of notable tectonic activity, the benefits of studying seasonal deformation are manifold: 1. Better constraints on groundwater flow and the structure of aquifers may be gained, 2. Seasonally modulated error terms in the GPS signal may be better understood, 3. A more robust physical model of deformation due to seasonal mass effects will permit a more accurate study of other physical phenomena, such as fault kinematics, dynamics and seasonal seismic modulation.

Lipovsky, B.; Funning, G. J.; Richards-Dinger, K. B.; Ferretti, A.

2010-12-01

131

Magnetic-field generation and turbulence suppression due to cross-helicity effects  

NASA Astrophysics Data System (ADS)

The regeneration mechanism of magnetic fields in turbulent motion is studied using a turbulent dynamo model, in which effects of global plasma rotation are incorporated through the turbulent cross helicity (velocity/magnetic-field correlation). The turbulent model consists of the mean-field equations and the transport equations for turbulent quantities such as the turbulent energy, its dissipation rate, and the turbulent cross helicity. Prominent properties of the cross-helicity effect, such as the direct linkage to the mean vortical motion, the alignment of the mean electric current and the mean vorticity, etc., are discussed in comparison with the helicity or ? effect. This model is applied to simple plasma flows, such as a cylindrical pipe and an accretion disk. The numerical results show that the turbulence suppression and magnetic-field generation due to the cross-helicity effects occur in the presence of mean vortical motion. The possible cross-helicity production mechanisms are also discussed.

Yokoi, Nobumitsu

1999-08-01

132

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

SciTech Connect

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.

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

2005-05-16

133

Magma displacements under insular volcanic fields, applications to eruption forecasting: El Hierro, Canary Islands, 2011-2013  

NASA Astrophysics Data System (ADS)

Significant deformations, followed by increased seismicity detected since 2011 July at El Hierro, Canary Islands, Spain, prompted the deployment of additional monitoring equipment. The climax of this unrest was a submarine eruption first detected on 2011 October 10, and located at about 2 km SW of La Restinga, southernmost village of El Hierro Island. The eruption ceased on 2012 March 5, after the volcanic tremor signals persistently weakened through 2012 February. However, the seismic activity did not end with the eruption, as several other seismic crises followed. The seismic episodes presented a characteristic pattern: over a few days the number and magnitude of seismic event increased persistently, culminating in seismic events severe enough to be felt all over the island. Those crises occurred in 2011 November, 2012 June and September, 2012 December to 2013 January and in 2013 March-April. In all cases the seismic unrest was preceded by significant deformations measured on the island's surface that continued during the whole episode. Analysis of the available GPS and seismic data suggests that several magma displacement processes occurred at depth from the beginning of the unrest. The first main magma movement or `injection' culminated with the 2011 October submarine eruption. A model combining the geometry of the magma injection process and the variations in seismic energy release has allowed successful forecasting of the new-vent opening.

García, A.; Fernández-Ros, A.; Berrocoso, M.; Marrero, J. M.; Prates, G.; De la Cruz-Reyna, S.; Ortiz, R.

2014-01-01

134

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

USGS Publications Warehouse

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.

Lee, M. W.

1987-01-01

135

Main Features of Quasi-Electrostatic Fields in Atmospheric Regions due to Lightning Discharge  

NASA Astrophysics Data System (ADS)

The most important features of the strong quasi-electrostatic fields, generated in the region ionosphereground after a single lightning discharge, due to succeeding redistribution of capacitive spatial charges, are studied in this work. The investigation of these fields is of great importance, particularly since they are considered to be responsible for generation of red sprites in the mesosphere and lower ionosphere over thunderstorms. As experimental measurements show, these quasi-electrostatic fields can cause, more often than sprites, electron heating and conductivity modifications in the mesosphere and ionosphere as well. The temporal behavior and relaxation time of the quasi-electrostatic fields, as well as their spatial extent and orientation are studied. For this purpose an analytical model based on the Maxwell equations under conditions of curl-free electric field is proposed. Such conditions are fulfilled short (less than a millisecond) after beginning of a lightning discharge and last until another discharge. Isotropic conductivity in the region of interest is assumed. Computations are made for the time-course of the quasi-electrostatic fields up to the lower ionosphere. The dynamics of spatial charges in this region, responsible for the quasi-electrostatic fields, is analyzed also. The quasi-electrostatic fields at an altitude observed reach their maximum at a time close to the local relaxation time. Up to the ionosphere this maximum is of an order of V/m per 1 Coulomb of a charge transported by lightning. The field decreases immediately after reaching its maximum in the mesosphere; however, at stratospheric and tropospheric altitudes its maximum forms a plateau, which becomes wider at lower heights. The relaxation of the quasi-electrostatic field at altitudes above 40 km is essentially slower than the local relaxation time of an electrical charge.

Tonev, P. T.

2006-03-01

136

Displacement Compensation of Temperature Probe Data  

NASA Technical Reports Server (NTRS)

Analysis of temperature data from a probe in a vertical Bridgman furnace growing germanium crystals revealed a displacement of the temperature profile due to conduction error. A theoretical analysis shows that the displacement compensation is independent of local temperature gradient. A displacement compensation value should become a standard characteristic of temperature probes used for temperature profile measurements.

Welch, Christopher S.; Hubert, James A.; Barber, Patrick G.

1996-01-01

137

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

PubMed Central

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.

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

2013-01-01

138

Alignment transition in a nematic liquid crystal due to field-induced breaking of anchoring  

NASA Astrophysics Data System (ADS)

We report on the alignment transition of a nematic liquid crystal from initially homeotropic to quasi-planar due to field-induced anchoring breaking. The initial homeotropic alignment is achieved by Langmuir-Blodgett monolayers. In this geometry the anchoring strength can be evaluated by the Frederiks transition technique. Applying an electric field above a certain threshold provokes turbulent states denoted DSM1 and DSM2. While DSM1 does not affect the anchoring, DSM2 breaks the coupling between the surface and the liquid crystal: switching off the field from a DSM2 state does not immediately restore the homeotropic alignment. Instead, we obtain a quasi-planar metastable alignment. The cell thickness dependence for the transition is related to the cell thickness dependence of the anchoring strength.

Fazio, V. S. U.; Komitov, L.

1999-04-01

139

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

140

Displacement in Revitalizing Neighborhoods: A Review and Research Strategy. (RE-ANNOUNCEMENT of PB85-126829-see notes field for explanation).  

National Technical Information Service (NTIS)

This paper first provides an analytical framework for viewing the displacement of poor families within the larger context of neighborhood revitalization and then reviews existing evidence to assess what is known about displacement's magnitude and extent; ...

H. J. Sumka

1979-01-01

141

3D displacement measurements using a single camera  

NASA Astrophysics Data System (ADS)

Measuring 3D displacements usually requires at least two cameras or 3D images. However, in some especially constrained experimental circumstances, it is only possible to use a single camera. The present paper develops a methodology, based on digital image correlation that is able to measure the homogeneous 3D displacement of a plane surface using a single camera. Based on Descartes' theory, a model is elaborated that accounts not only for the magnification change due to the out-of-plane displacement but also for the unfocusing of the object. Several examples are provided that show the ability of the technique to track 3D displacements with various optical setups with different depths of field.

Réthoré, Julien; Morestin, Fabrice; Lafarge, Lionel; Valverde, Paul

2014-06-01

142

Gain depression due to undulator field errors in the UCSB FEL  

NASA Astrophysics Data System (ADS)

The linearly polarized undulator for the single stage free electron laser (FEL) experiment at UCSB is made of cobalt-samarium permanent magnets. It can provide a maximum field of 850 G on axis with ±2% uniformity. Numerical simulation of the electron beam transport through the undulator shows strong focusing betatron oscillations in the vertical direction. In the horizontal plane, typical beam trajectories have fluctuating amplitudes comparable to the laser beam radius. As a result of this, the laser gain is reduced by 30%. Numerical analysis of the bandwidth broadening of the spontaneous emission is discussed. Field imperfection in the undulator reduces electron beam recovery, which also reduces laser gain. With a maximum recovery rate of 97%, the gain is reduced by 1% due to electron beam energy shift. It can be reduced more with less recovery rate.

Hu, Ren-Chau James; Elias, Luis R.

1986-09-01

143

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

SciTech Connect

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.

Krinsky, S.

1985-01-01

144

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

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

145

Porous silicon/Ni composites of high coercivity due to magnetic field-assisted etching  

PubMed Central

Ferromagnetic nanostructures have been electrodeposited within the pores of porous silicon templates with average pore diameters between 25 and 60?nm. In this diameter regime, the pore formation in general is accompanied by dendritic growth resulting in rough pore walls, which involves metal deposits also offering a branched structure. These side branches influence the magnetic properties of the composite system not only due to modified and peculiar stray fields but also because of a reduced interpore spacing by the approaching of adjacent side pores. To improve the morphology of the porous silicon structures, a magnetic field up to 8?T has been applied during the formation process. The magnetic field etching results in smaller pore diameters with less dendritic side pores. Deposition of a ferromagnetic metal within these templates leads to less branched nanostructures and, thus, to an enhancement of the coercivity of the system and also to a significantly increased magnetic anisotropy. So magnetic field-assisted etching is an appropriate tool to improve the structure of the template concerning the decrease of the dendritic pore growth and to advance the magnetic properties of the composite material.

2012-01-01

146

Porous silicon/Ni composites of high coercivity due to magnetic field-assisted etching  

NASA Astrophysics Data System (ADS)

Ferromagnetic nanostructures have been electrodeposited within the pores of porous silicon templates with average pore diameters between 25 and 60 nm. In this diameter regime, the pore formation in general is accompanied by dendritic growth resulting in rough pore walls, which involves metal deposits also offering a branched structure. These side branches influence the magnetic properties of the composite system not only due to modified and peculiar stray fields but also because of a reduced interpore spacing by the approaching of adjacent side pores. To improve the morphology of the porous silicon structures, a magnetic field up to 8 T has been applied during the formation process. The magnetic field etching results in smaller pore diameters with less dendritic side pores. Deposition of a ferromagnetic metal within these templates leads to less branched nanostructures and, thus, to an enhancement of the coercivity of the system and also to a significantly increased magnetic anisotropy. So magnetic field-assisted etching is an appropriate tool to improve the structure of the template concerning the decrease of the dendritic pore growth and to advance the magnetic properties of the composite material.

Granitzer, Petra; Rumpf, Klemens; Ohta, Toshiyuki; Koshida, Nobuyoshi; Poelt, Peter; Reissner, Michael

2012-07-01

147

Transient hydromagnetic flow in a rotating channel permeated by an inclined magnetic field with magnetic induction and Maxwell displacement current effects  

NASA Astrophysics Data System (ADS)

Closed-form solutions are presented for the transient hydromagnetic flow in a rotating channel with inclined applied magnetic field under the influence of a forced oscillation. Magnetic Reynolds number is large enough to permit the inclusion of magnetic induction effects. The Maxwell displacement current effect is also included and simulated via a dielectric strength parameter. The governing momentum and magnetic induction conservation equations are normalized with appropriate transformations and the resulting quartet of partial differential equations are solved exactly. A parametric study is performed of the influence of oscillation frequency parameter ( ?), time ( T), inverse Ekman number, i.e. rotation parameter ( K 2), square of the Hartmann magnetohydrodynamic (MHD) parameter ( M 2), and magnetic field inclination ( ?) on the primary and secondary induced magnetic field components ( b x , b y ) and velocity components ( u, v) across the channel. Network solutions are also obtained to validate the exact solutions and shown to be in excellent agreement. Applications of the study arise in planetary plasma physics and rotating MHD induction power generators and also astronautical flows.

Ghosh, S. K.; Bég, O. A.; Zueco, J.; Prasad, V. R.

2010-02-01

148

Characterization of transducer arrays by laser interferometry: influence of acousto-optic interactions on displacement measurements in water  

Microsoft Academic Search

This paper deals with the influence of acoustooptic interactions on displacement measurements over transducer array with laser interferometer. Changes on the popular x-t and ?-k diagram of displacement due to interactions between acoustic and laser beams are discussed. A theoretical analysis of acousto-optic phenomenon, based on the plane wave decomposition of radiated field by the array is developed. Theoretical and

D. Certon; O. B. Matar; J. Guyonvarch; N. Felix; F. Patat

2001-01-01

149

Instability of Alfvénic Structures due to Inhomogeneous Parallel Current and Transverse Electric Field  

NASA Astrophysics Data System (ADS)

Previous studies of the instability of Alfvénic structures are expanded to include the effect of a sheared E x B flow. Alfvén waves with transverse scale near the electron inertial length c/? p can be unstable due to the parallel current carried primarily by the electrons. In an equilibrium with inhomogeneous parallel current and no parallel or transverse flow, the modes are purely growing. With the addition of a sheared flow due to a structured transverse electric field, the character of the unstable modes are substantially changed. In particular, sheared flow can significantly increase the growth rate of the current driven interchange mode. Linear stability analysis and numerical eigenvalue calculations are shown. We will also present the results of three-dimensonal nonlinear simulations which show that the instability of Alfvénic structures can lead to current filaments and coherent short scale electric field structures. The instabilities presented here are possible mechanisms for producing the broadband extremely low-frequency (BBELF) waves often associated with Alfvénic structures and transverse ion acceleration.

Wu, K.; Seyler, C. E.

2001-05-01

150

Biological effects due to weak electric and magnetic fields: the temperature variation threshold.  

PubMed Central

A large number of epidemiological and experimental studies suggest that prolonged (>100 s) weak 50-60-Hz electric and magnetic field (EMF) exposures may cause biological effects(NIEHS Working Group, NIH, 1998; Bersani, 1999). We show, however, that for typical temperature sensitivities of biochemical processes, realistic temperature variations during long exposures raise the threshold exposure by two to three orders of magnitude over a fundamental value, independent of the biophysical coupling mechanism. Temperature variations have been omitted in previous theoretical analyses of possible weak field effects, particularly stochastic resonance (Bezrukov and Vodyanoy 1997a. Nature. 385:319-321; Astumian et al., 1997 Nature. 338:632-633; Bezrukov and Vodyanoy, 1997b. Nature. 338:663; Dykman and McClintock, 1998. Nature. 391:344; McClintock, 1998;. Gammaitoni et al., 1998. Rev. Mod. Phys. 70:223-287). Although sensory systems usually respond to much shorter (approximately 1 s) exposures and can approach fundamental limits (Bialek, 1987 Annu. Rev. Biophys. Biophys. Chem. 16:455-468; Adair et al, 1998. Chaos. 8:576-587), our results significantly decrease the plausibility of effects for nonsensory biological systems due to prolonged, weak-field exposures.

Weaver, J C; Vaughan, T E; Martin, G T

1999-01-01

151

Second-order correction to the Bigeleisen-Mayer equation due to the nuclear field shift  

PubMed Central

The nuclear field shift affects the electronic, rotational, and vibrational energies of polyatomic molecules. The theory of the shifts in molecular spectra has been studied by Schlembach and Tiemann [Schlembach, J. & Tiemann, E. (1982) Chem. Phys. 68, 21]; measurements of the electronic and rotational shifts of the diatomic halides of Pb and Tl have been made by Tiemann et al. [Tiemann, E., Knöckel, H. & Schlembach, J. (1982) Ber. Bunsenges. Phys. Chem. 86, 821]. These authors have estimated the relative shifts in the harmonic frequencies of these compounds due to the nuclear field shift to be of the order of 10?6. I have used this estimate of the relative shift in vibrational frequency to calculate the correction to the harmonic oscillator approximation to the isotopic reduced partition-function ratio 208Pb32S/207Pb32S. The correction is 0.3% of the harmonic oscillator value at 300 K. In the absence of compelling evidence to the contrary, it suffices to calculate the nuclear field effect on the total isotopic partition-function ratio from its shift of the electronic zero point energy and the unperturbed molecular vibration.

Bigeleisen, Jacob

1998-01-01

152

Reduction of the friction force in electron cooling systems due to magnetic field errors  

NASA Astrophysics Data System (ADS)

Magnetic field errors can limit the dynamical friction force on co-propagating ions and, hence, increase the cooling time. We present theoretical and numerical results for reduction of the friction force due to bounded transverse magnetic field errors, as a function of wavelength. VORPAL [1] simulations using a binary collision algorithm [2] show that small-wavelength field errors affect the friction logarithmically, via the Coulomb log, while long-wavelength errors reduce the friction by effectively increasing the transverse electron temperature. A complete understanding of finite-time effects and the role of small impact parameter collisions is required to correctly interpret the simulation results. We show that the distribution of electron-ion impact parameters is similar to a Pareto distribution, for which the central limit theorem does not apply. A new code has been developed to calculate the cumulative distribution function of electron-ion impact parameters and thus correctly estimate the expectation value and uncertainty of the friction force. [1] C. Nieter and J. Cary, J. Comp. Phys. 196 (2004), p. 448. [2] G. Bell et al., J. Comp. Phys. 227 (2008), p. 8714.

Sobol, Andrey; Bell, George; Bruhwiler, David; Fedotov, Alexei; Litvinenko, Vladimir

2009-05-01

153

Pineal melatonin level disruption in humans due to electromagnetic fields and ICNIRP limits.  

PubMed

The International Agency for Research on Cancer (IARC) classifies electromagnetic fields (EMFs) as 'possibly carcinogenic' to humans that might transform normal cells into cancer cells. Owing to high utilisation of electricity in day-to-day life, exposure to power-frequency (50 or 60 Hz) EMFs is unavoidable. Melatonin is a natural hormone produced by pineal gland activity in the brain that regulates the body's sleep-wake cycle. How man-made EMFs may influence the pineal gland is still unsolved. The pineal gland is likely to sense EMFs as light but, as a consequence, may decrease the melatonin production. In this study, more than one hundred experimental data of human and animal studies of changes in melatonin levels due to power-frequency electric and magnetic fields exposure were analysed. Then, the results of this study were compared with the International Committee of Non-Ionizing Radiation Protection (ICNIRP) limit and also with the existing experimental results in the literature for the biological effect of magnetic fields, in order to quantify the effects. The results show that this comparison does not seem to be consistent despite the fact that it offers an advantage of drawing attention to the importance of the exposure limits to weak EMFs. In addition to those inconsistent results, the following were also observedfrom this work: (i) the ICNIRP recommendations are meant for the well-known acute effects, because effects of the exposure duration cannot be considered and (ii) the significance of not replicating the existing experimental studies is another limitation in the power-frequency EMFs. Regardless of these issues, the above observation agrees with our earlier study in which it was confirmed that it is not a reliable method to characterise biological effects by observing only the ratio of AC magnetic field strength to frequency. This is because exposure duration does not include the ICNIRP limit. Furthermore, the results show the significance of disruption of melatonin due to exposure to weak EMFs, which may possibly lead to long-term health effects in humans. PMID:23051584

Halgamuge, Malka N

2013-05-01

154

Membrane permeabilization in relation to inactivation kinetics of Lactobacillus species due to pulsed electric fields.  

PubMed

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

Wouters, P C; Bos, A P; Ueckert, J

2001-07-01

155

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

PubMed Central

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.

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

2001-01-01

156

Displacement currents in geoelectromagnetic problems  

NASA Astrophysics Data System (ADS)

The influence of displacement currents in conventional geoelectromagnetic (GEM) methods using unimodal transversal electric (TE) or multimodal TE and TM (transversal magnetic) fields is only significant at very high frequencies in the frequency domain or at extremely early times in the time domain. The transient process in the latter includes three stages: the propagation through air, the propagation through earth and the diffusion within the earth. The influence of displacement currents is significant mainly during the former two stages, normally up to several tens to a few hundreds of nanoseconds. The behavior is essentially different in novel GEM methods using a vertical electric dipole (VED) or circular electric dipole (CED) sources of unimodal TM-fields. Under certain geoelectric conditions, the influence of displacement currents in these methods might be crucial at late times as well. This happens, if the model consists of insulating layers. In the absence of displacement currents, such layers would totally mask underlying structures. However, TM-fields including displacement currents depend on geoelectric parameters below insulating layers at late times.

Mogilatov, Vladimir; Goldman, Mark; Persova, Marina; Soloveichik, Yury

2014-06-01

157

FARADAY ROTATION MEASURE DUE TO THE INTERGALACTIC MAGNETIC FIELD. II. THE COSMOLOGICAL CONTRIBUTION  

SciTech Connect

We investigate the Faraday rotation measure (RM) due to the intergalactic magnetic field (IGMF) through the cosmic web up to cosmological distances, using a model IGMF based on turbulence dynamo in the large-scale structure of the universe. By stacking the IGMF and gas density data up to redshift z = 5 and taking account of the redshift distribution of polarized background radio sources against which the RM is measured, we simulate the sky map of the RM. The contribution from galaxy clusters is subtracted from the map, based on several different criteria of X-ray brightness and temperature. Our findings are as follows. The distribution of RM for radio sources of different redshifts shows that the rms value increases with redshift and saturates for z {approx}> 1. The saturated value is RM{sub rms} {approx} several rad m{sup -2}. The probability distribution function of |RM| follows the lognormal distribution. The power spectrum has a broad plateau over the angular scale of {approx}1{sup 0}-0.{sup 0}1 with a peak around {approx}0.{sup 0}15. The second-order structure function has a flat profile in the angular separation of {approx}> 0.{sup 0}2. Our results could provide useful insights for surveys to explore the IGMF with the Square Kilometer Array (SKA) and upcoming SKA pathfinders.

Akahori, Takuya [Research Institute of Basic Science, Chungnam National University, Daejeon (Korea, Republic of); Ryu, Dongsu, E-mail: akataku@canopus.cnu.ac.kr, E-mail: ryu@canopus.cnu.ac.kr [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of)

2011-09-10

158

Uncertainties in SOA simulations due to meteorological uncertainties in Mexico City during MILAGRO-2006 field campaign  

NASA Astrophysics Data System (ADS)

The purpose of the present study is to investigate the uncertainties in simulating secondary organic aerosol (SOA) in Mexico City metropolitan area (MCMA) due to meteorological initial uncertainties using the WRF-CHEM model through ensemble simulations. The simulated periods (24 and 29 March 2006) represent two typical meteorological episodes ("Convection-South" and "Convection-North", respectively) in the Mexico City basin during the MILAGRO-2006 field campaign. The organic aerosols are simulated using a non-traditional SOA model including the volatility basis-set modeling method and the contributions from glyoxal and methylglyoxal. Model results demonstrate that uncertainties in meteorological initial conditions have significant impacts on SOA simulations, including the peak time concentrations, the horizontal distributions, and the temporal variations. The ensemble spread of the simulated peak SOA at T0 can reach up to 4.0 ?g m-3 during the daytime, which is around 35% of the ensemble mean. Both the basin wide wind speed and the convergence area affect the magnitude and the location of the simulated SOA concentrations inside the Mexico City basin. The wind speed, especially during the previous midnight and the following early morning, influences the magnitude of the peak SOA concentration through ventilation. The surface horizontal convergence zone generally determines the area with high SOA concentrations. The magnitude of the ensemble spreads may vary with different meteorological episodes but the ratio of the ensemble spread to mean does not change significantly.

Bei, N.; Li, G.; Molina, L. T.

2013-05-01

159

Rapid decay of storm time ring current due to pitch angle scattering in curved field line  

NASA Astrophysics Data System (ADS)

The storm time ring current sometimes exhibits rapid decay, as suggested from the Dst index, but the underlying mechanism is unknown. By means of a simulation with pitch angle scattering due to the field line curvature (FLC), together with the charge exchange and adiabatic loss cone loss, we investigated rapid decay of the storm time ring current for the large magnetic storm that occurred on 12 August 2000. When all three loss processes were included, the Dst (SYM-H) index showed rapid recovery with an e-folding time of ˜6 h. However, without FLC scattering, the simulated Dst (SYM-H) index showed a slower recovery with an e-folding time of ˜12 h. Overall flux of energetic neutral hydrogen with energy ? 39 keV was significantly reduced by the FLC scattering and is consistent with data from the high energy neutral analyzer (HENA) on board the IMAGE satellite. Power of precipitating protons showed a fairly good agreement with data from the far ultraviolet (FUV) imager on board IMAGE. These fairly good agreements with observations lead to the possible conclusion that the FLC scattering is a significant loss mechanism for the ring current ions, and the main oval of the proton aurora is likely a manifestation of the precipitating loss of the protons for this particular storm.

Ebihara, Y.; Fok, M.-C.; Immel, T. J.; Brandt, P. C.

2011-03-01

160

In situ evidence of enhanced transformation kinetics in a medium carbon steel due to a high magnetic field  

Microsoft Academic Search

A medium carbon steel was cooled from 850 °C at various rates with and without a 30-T magnetic field. Due to the magnetic field, the onset of thermal recalescence associated with the release of latent heat showed 70–90 °C increase, indicating acceleration in austenite decomposition. The relative shift was cooling rate dependent. Microstructural examination revealed increased ferrite content and corroborated

G. M. Ludtka; R. A. Jaramillo; R. A. Kisner; D. M. Nicholson; J. B. Wilgen; G. Mackiewicz-Ludtka; P. N. Kalu

2004-01-01

161

Analytical Calculation of the Magnetic Field in Electrical Machines due to the Current Density in an Airgap Winding  

Microsoft Academic Search

An electrical machine was designed for an energy storage flywheel in a load-levelling system for a city bus. This machine has a slotless stator, and was designed by the use of analytical field calculations. The calculation of the field due to the current distribution in the airgap forms the main contribu- tion of this paper. The results of the analytical

S. R. Holm; H. Polinder; J. A. Ferreira; M. J. Hoeijmakers; P. van Gelder; R. Dill

162

Rotation of a levitated YBa 2Cu 3O 7- x superconductor due to a low frequency magnetic field  

NASA Astrophysics Data System (ADS)

Rotation of a levitated YBa 2Cu 3O 7- x superconductor due to both rotational and linear alternating magnetic fields was observed. Rotational field intensity-induced rotation is strongly frequency dependent. This dependence demonstrates oscillating-like behaviour. The rotational frequency of the superconductor is less than the field frequency and practically independent of it. The relationship between viscous motion of the vortices and rotation of the superconductor is discussed.

Terentiev, A. N.; Kuznetsov, A. A.

1990-07-01

163

Displacement of large-scale open solar magnetic fields from the zone of active longitudes and the heliospheric storm of November 3-10, 2004: 1. The field dynamics and solar activity  

NASA Astrophysics Data System (ADS)

The dynamics of the large-scale open field and solar activity at the second stage of the MHD process, including the origination and disappearance of the four-sector structure during the decline phase of cycle 23 (the stage when the blocking field is displaced from the main zone of active longitudes), has been considered. Extremely fast changes in the scales of one of new sectors (from an extremely small sector (“singularity”) to a usual sector that originated after the uniform expansion (“explosion”) of singularity with a “kick” into the zone of active longitudes, westward motion of the MHD disturbance front in the direction of solar rotation, and formation of an active quasi-rigidly corotating sector boundary responsible for the heliospheric storm of November 2004) have been detected in the field dynamics. It has been indicated that a very powerful group of sunspots AR 10656 (which disappeared after the explosion) with an area of up to 1540 ppmh (part per million hemisphere), a considerable deficit of the external energy release, and zero geoeffectiveness in spite of the closeness to the Earth helioprojection existed within singularity. It has been assumed that the energy escaped from this group with effort owing to the interaction between coronal ejections and narrow sector walls (singularity), and a considerable part of the energy was released in the outer layers of the convective zone, as a result of which singularity exploded and this explosion was accompanied by the above effects in the large-scale field and solar activity.

Ivanov, K. G.

2010-06-01

164

A Methodology to Validate the InSAR Derived Displacement Field of the September 7th, 1999 Athens Earthquake Using Terrestrial Surveying. Improvement of the Assessed Deformation Field by Interferometric Stacking  

PubMed Central

The primary objective of this paper is the evaluation of the InSAR derived displacement field caused by the 07/09/1999 Athens earthquake, using as reference an external data source provided by terrestrial surveying along the Mornos river open aqueduct. To accomplish this, a processing chain to render comparable the leveling measurements and the interferometric derived measurements has been developed. The distinct steps proposed include a solution for reducing the orbital and atmospheric interferometric fringes and an innovative method to compute the actual InSAR estimated vertical ground subsidence, for direct comparison with the leveling data. Results indicate that the modeled deformation derived from a series of stacked interferograms, falls entirely within the confidence interval assessed for the terrestrial surveying data.

Kotsis, Ioannis; Kontoes, Charalabos; Paradissis, Dimitrios; Karamitsos, Spyros; Elias, Panagiotis; Papoutsis, Ioannis

2008-01-01

165

Residual magnetic stray field in ITER building and field perturbation on the plasma due to ferromagnetic iron components outside the vessel  

Microsoft Academic Search

The present work evaluates, using 3D finite element (FE) electromagnetic (EM) analyses, the poloidal field coil (PFC) stray field reduction inside and outside the main ITER building due to the presence of ferromagnetic content in the concrete and other iron components outside the vessel (mainly the huge iron boxes of the NBI – neutral beam injector – and the iron

M. Roccella; A. Marin; F. Lucca; A. Pizzuto; G. Ramogida

2009-01-01

166

Hysteretic control of organic conductance due to remanent magnetic fringe fields  

NASA Astrophysics Data System (ADS)

Manipulation of the remanent (zero external magnetic field) magnetization state of a single ferromagnetic film is shown to control the room-temperature conductance of an organic semiconductor thin film deposited on top. For the organic semiconductor Alq3, the magnetic fringe fields from a multidomain remanent magnetization state of the film enhance the device conductance by several percent relative to its value for the magnetically saturated ferromagnetic film. The effect of fringe fields is insensitive to ferromagnetic film's thickness (which varies the fringe field magnitude proportionately) but sensitive to the magnetic domain's correlation length.

Macià, F.; Wang, F.; Harmon, N. J.; Wohlgenannt, M.; Kent, A. D.; Flatté, M. E.

2013-01-01

167

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

PubMed Central

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 time constant, ?. As the magnetic field frequency is increased, the nanoparticle’s magnetic moment lags the applied magnetic field at a constant angle for a given frequency, ?, in rad/s. Associated with this misalignment is a power dissipation that increases the bulk magnetic fluid’s temperature which has been utilized as a method of magnetic nanoparticle hyperthermia, particularly suited for cancer in low-perfusion tissue (e.g., breast) where temperature increases of between 4°C and 7°C above the ambient in vivo temperature cause tumor hyperthermia. This work examines the rise in the magnetic fluid’s temperature in the MRI environment which is characterized by a large DC field, B0. Theoretical analysis and simulation is used to predict the effect of both alternating-sinusoidal and rotating magnetic fields transverse to B0. Results are presented for the expected temperature increase in small tumors (~1 cm radius) over an appropriate range of magnetic fluid concentrations (0.002 to 0.01 solid volume fraction) and nanoparticle radii (1 to 10 nm). The results indicate that significant heating can take place, even in low-field MRI systems where magnetic fluid saturation is not significant, with careful selection of the rotating or sinusoidal field parameters (field frequency and amplitude). The work indicates that it may be feasible to combine low-field MRI with a magnetic hyperthermia system using superparamagnetic iron oxide nanoparticles.

Wald, L.L.; Adalsteinsson, E.; Zahn, M.

2009-01-01

168

Precision displacement reference system  

DOEpatents

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.

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

2000-02-22

169

XY displacement device  

Microsoft Academic Search

An XY-displacement device (1) with a four-fold symmetry comprises a reference frame (10); an object mount (20) for holding an object (22) to be displaced; an X-manipulator (100) coupled between the reference frame (10) and the object mount (20), which provides a rigid coupling between the object mount (20) and a piezoelectric X-actuator (140), allows a Y-displacement of the object

W. C. Heerens; C. D. Laham; A. E. Holman

1997-01-01

170

Distortion of magnetic field and magnetic force of a brushless dc motor due to deformed rubber magnet  

NASA Astrophysics Data System (ADS)

This paper investigates the distortion of magnetic field of a brushless dc (BLDC) motor due to deformed rubber magnet. Global or local deformation of rubber magnet in the BLDC motor is mathematically modeled by using the Fourier series. Distorted magnetic field is calculated by using the finite element method, and unbalanced magnetic force is calculated by using the Maxwell stress tensor. When the rubber magnet is globally or locally deformed, the unbalanced magnetic force has the frequencies with the first harmonic and the harmonics of slot number +/-1. However, the harmonic deformation with multiple of common divisor of pole and slot does not generate unbalanced magnetic force due to the rotational symmetry.

Lee, C. J.; Jang, G. H.

2008-04-01

171

Fusion of D-InSAR and sub-pixel image correlation measurements for coseismic displacement field estimation: Application to the Kashmir earthquake (2005)  

Microsoft Academic Search

In geophysics, the uncertainty associated with model parameters or displacement measurements plays a crucial role in the understanding of geophysical phenomenon. An emerging way to reduce the geodetic parameter uncertainty is to combine a large number of data provided by SAR images. However, the measurements by radar imagery are subject to both random and epistemic uncertainties. Probability theory is known

Yajing Yan; Emmanuel Trouvé; Virginie Pinel; Gilles Mauris; Erwan Pathier; Sylvie Galichet

2012-01-01

172

Fusion of D-InSAR and sub-pixel image correlation measurements for coseismic displacement field estimation: Application to the Kashmir earthquake (2005)  

Microsoft Academic Search

In geophysics, the uncertainty associated with model parameters or displacement measurements plays a crucial role in the understanding of geophysical phenomenon. An emerging way to reduce the geodetic parameter uncertainty is to combine a large number of data provided by SAR images. However, the measurements by radar imagery are subject to both random and epistemic uncertainties. Probability theory is known

Yajing Yan; Emmanuel Trouvé; Virginie Pinel; Gilles Mauris; Erwan Pathier; Sylvie Galichet

2011-01-01

173

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

Microsoft Academic Search

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

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

2006-01-01

174

Analysis of payload bay magnetic fields due to dc power multipoint and single point ground configurations  

NASA Technical Reports Server (NTRS)

An analysis of magnetic fields in the Orbiter Payload Bay resulting from the present grounding configuration (structure return) was presented and the amount of improvement that would result from installing wire returns for the three dc power buses was determined. Ac and dc magnetic fields at five points in a cross-section of the bay are calculated for both grounding configurations. Y and Z components of the field at each point are derived in terms of a constant coefficient and the current amplitude of each bus. The dc loads assumed are 100 Amperes for each bus. The ac noise current used is a spectrum 6 db higher than the Orbiter equipment limit for narrowband conducted emissions. It was concluded that installing return wiring to provide a single point ground for the dc Buses in the Payload Bay would reduce the ac and dc magnetic field intensity by approximately 30 db.

Lawton, R. M.

1976-01-01

175

Blindness Due to Sellar Region Tumor Caused Apoplexy; Visual Field Investigation Helps the Diagnosis.  

National Technical Information Service (NTIS)

Chiasmal region tumor caused apoplexy is not uncommon. As its clinical picture varies and is complicated, early diagnosis is usually difficult. 7 cases are reported with marked visual loss, the presenting symptom. Visual fields all revealed definite chias...

L. Yuanxiu

1980-01-01

176

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

PubMed Central

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).

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

177

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

NASA Astrophysics Data System (ADS)

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).

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

178

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

NASA Astrophysics Data System (ADS)

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.

Nagai, T.; Hirata, A.

2010-05-01

179

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

NASA Astrophysics Data System (ADS)

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.

Poulin-Lamarre, G.; Bureau-Oxton, C.; Kam, A.; Zawadzki, P.; Studenikin, S.; Aers, G.; Pioro-Ladrière, M.; Sachrajda, A. S.

2013-12-01

180

Can Baryogenesis Survive in the Standard Model Due To Strong Hypermagnetic Field?  

Microsoft Academic Search

The electroweak phase transition in a constant hypermagnetic field=A0 is studied in the Standard Model. The symmetry behaviour is investigated within the consistent effective potential of the scalar and magnetic fields at finite temperature. It includes the one-loop and ring diagram contributions. All fundamental fermions and bosons are taken into consideration with their actual masses. The only free parameter is

Vladimir Skalozub; Vadim Demchik

1999-01-01

181

Phase shifts in precision atom interferometry due to the localization of atoms and optical fields  

SciTech Connect

We discuss details of momentum transfer in the interaction between localized atoms and localized optical fields which are relevant to precision atom interferometry. Specifically, we consider a {lambda}-type atom coherently driven between its ground states by a bichromatic optical field. We assume that the excited state can be eliminated adiabatically from the time evolution. It is shown that the average recoil momentum is given by the phase gradient of the two-photon field at the 'position' of the atom, provided that the optical field can be described by a function which is separable in position and time and that the atomic wave function is symmetric and well localized within the optical field envelope. The result does not require the optical fields to have a Gaussian spatial dependence. Our discussion provides the basis for the analysis of systematic errors in precision atom interferometry arising from optical wave-front curvature, wave-front distortion, and the Gouy phase shift of Gaussian beams. We apply our result to the atom interferometer experiment of Chu and co-workers which measures the fine-structure constant.

Wicht, A.; Sarajlic, E.; Hensley, J.M.; Chu, S. [Institute for Experimental Physics, Heinrich-Heine-Universitaet Duesseldorf, Universitaetsstr. 1, D-40225 Duesseldorf (Germany); Physics Department, Stanford University, Stanford, California 94305 (United States)

2005-08-15

182

Quadrupolar spin relaxation due to electric field gradients induced by vibrations and collisions  

NASA Astrophysics Data System (ADS)

The spin relaxation of quadrupolar nuclei in highly symmetric electronic environments via vibrationally-induced electric field gradients is considered. A model is presented for tetrahedral molecules which yields a nuclear quadrupole coupling constant for 189Os in an excited vibrational state of OsO4 which is in reasonable agreement with experimentally observed values. The nuclear quadrupole coupling constants for the central nucleus in excited E and F2 vibrational states of GeCl4, GeBr4, RuO4, OsO4 molecules as well as the MOn-4 ions (M = V, Cr, Mn, Mo, Tc, Re) are calculated using this model. These coupling constants lead to quadrupolar relaxation rates which are orders of magnitude too small compared to experiment. Alternate mechanisms, collisional-deformation by long-range van der Waals interactions and fields induced by octopole moments, are proposed. A binary collision model is used in which the fluctuating electric fields associated with London dispersion forces during a collision create electric field gradients at the quadrupolar nucleus. Parallel development of vibrational and intermolecular effects on nuclear shielding with vibrational and collisional-deformation-induced electric field gradients is shown. The latter mechanism and the octopole-induced fields are capable of giving relaxation rates of the right order of magnitude.

Osten, H. Jörg; Jameson, Cynthia J.

183

Transient electric field at high altitudes due to lightning: Possible role of induction field in the formation of elves  

Microsoft Academic Search

Space and time behaviors of electric field perturbation vector at high altitudes driven by lightning return stroke are examined in terms of its three individual components (i.e., electrostatic, induction, and radiation) with transmission line model, by specifying the current form in a return stroke channel, which is presumed to be vertically oriented. The result shows that at 90 km altitude,

Gaopeng Lu

2006-01-01

184

Cancellation of the ion deflection due to electron-suppression magnetic field in a negative-ion acceleratora)  

NASA Astrophysics Data System (ADS)

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.

Chitarin, G.; Agostinetti, P.; Aprile, D.; Marconato, N.; Veltri, P.

2014-02-01

185

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

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

186

Compressed Facade Displacement Maps  

Microsoft Academic Search

We describe an approach to render massive urban models. To prevent a memory transfer bottleneck, we propose to render the models from a compressed representation directly. Our solution is based on rendering crude building outlines as polygons and generating details by ray-tracing displacement maps in the fragment shader. We demonstrate how to compress a displacement map so that a decompression

Saif Ali; Jieping Ye; Anshuman Razdan; Peter Wonka

2009-01-01

187

On the gravitational potential and field anomalies due to thin mass layers  

NASA Technical Reports Server (NTRS)

The gravitational potential and field anomalies for thin mass layers are derived using the technique of matched asymptotic expansions. An inner solution is obtained using an expansion in powers of the thickness and it is shown that the outer solution is given by a surface distribution of mass sources and dipoles. Coefficients are evaluated by matching the inner expansion of the outer solution with the outer expansion of the inner solution. The leading term in the inner expansion for the normal gravitational field gives the Bouguer formula. The leading term in the expansion for the gravitational potential gives an expression for the perturbation to the geoid. The predictions given by this term are compared with measurements by satellite altimetry. The second-order terms in the expansion for the gravitational field are required to predict the gravity anomaly at a continental margin. The results are compared with observations.

Ockendon, J. R.; Turcotte, D. L.

1977-01-01

188

Distortion of the virtual photon cloud due to a static electric field  

NASA Astrophysics Data System (ADS)

The structure of the virtual transverse-photon cloud surrounding a ground-state hydrogen atom is considered in the presence of a uniform static electric field, which is capable of polarizing the atom. It is shown that this virtual cloud is distorted with respect to the spherically symmetric shape which is obtained when no static electric field is present. The distortion is carried by new components of the cloud, arising from the contributions of magnetic-dipole and electric-quadrupole virtual photons. These new contributions are shown to possess an overall cylindrical symmetry around the direction of the static field, and to be present also at large distances from the atom. The possibility of detecting these contributions experimentally is briefly discussed.

Compagno, G.; Palma, M. G.

1988-04-01

189

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

SciTech Connect

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.

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

1994-10-15

190

Decrease of Visual Fields Due to Re-growth of a Big Aneurysm after Coiling  

PubMed Central

Summary We report the case of a 50-year-old man with the chief complaint of narrowing of the visual fields and blurring in his right eye. He had undergone coiling for bilateral aneurysms of the ophthalmic segment of the internal carotid arteries 15 months previously. Angiography showed re-growth of the left ophthalmic aneurysm. The patient underwent clipping and resection the coiled aneurysm. Following surgery his visual fields improved. Therefore, re-growth of aneurysms following coiling sometimes requires resection for decompression.

Harsan, H.; Eka, JW.; Julius, J.

2008-01-01

191

Calculating the electromagnetic field on the earth due to an electrodynamic tethered system in the ionosphere  

NASA Technical Reports Server (NTRS)

A method is presented for calculating the electromagnetic wave field on the earth's surface associated with the operation of an electrodynamic tethered satellite system of constant or slowly varying current in the upper ionosphere. The wave field at the ionospheric boundary and on the earth's surface is obtained by numerical integration. The results suggest that the ionospheric waves do not propagate into the atmosphere and that the image of the Alfven wings from a steady-current tether should be greatly broadened on the earth's surface.

Estes, Robert D.

1989-01-01

192

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

NASA Technical Reports Server (NTRS)

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.

Fatuzzo, Marco; Melia, Fulvio

1991-01-01

193

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

NASA Technical Reports Server (NTRS)

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.

Tsang, L.; Kong, J. A.

1974-01-01

194

Study of Optical Effects Due to an Induced Polarization Third Order in the Electric Field Strength  

Microsoft Academic Search

This paper presents the results of a series of experiments in which a giant pulsed ruby laser is used to study several different nonlinear optical effects arising from an induced optical polarization third order in the electric field strength. The various phenomena studied are special cases of either frequency mixing or intensity-dependent changes in the complex refractive index, including Raman

P. D. Maker; R. W. Terhune

1965-01-01

195

Heating, ionization and upward discharges in the mesosphere, due to intense quasi-electrostatic thundercloud fields  

Microsoft Academic Search

Quasi-electrostatic (QE) fields that temporarily exist at high altitudes following the sudden removal (e.g., by a lightning discharge) of thundercloud charge at low altitudes are found to significantly heat mesospheric electrons and produce ionization and light. The intensity, spatial extent, duration and spectra of optical emissions produced are consistent with the observed features of the Red Sprite type of upward

Victor P. Pasko; Umran S. Inan; Yuri N. Taranenko; Timothy F. Bell

1995-01-01

196

Heating, ionization and upward discharges in the mesosphere due to intense quasi-electrostatic thundercloud fields  

Microsoft Academic Search

Quasi-electrostatic (QE) fields that temporarily exist at high altitudes following the sudden removal (e.g., by a lightning discharge) of thundercloud charge at low altitudes are found to significantly heat mesospheric electrons and produce ionization and light. The intensity, spatial extent, duration and spectra of optical emissions produced are consistent with the observed features of the Red Sprite type of upward

Victor P. Pasko; Umran S. Inan; Yuri N. Taranenko; Timothy F. Bell

1995-01-01

197

The field transmitted into a PBG crystal due to an electric line source  

Microsoft Academic Search

The analytic solution for the field transmitted from an electric line source into a photonic bandgap (PBG) crystal half-space is presented. This solution demonstrates the extension of the effective functional description of PBG crystals of Kyriazidou, Contopanoagos, Merrill and Alexopoulos (see IEEE Trans. Ant. Prop. 1998) to a description of a PBG crystal excited by a non-plane wave source. The

W. M. Merrill; C. A. Kyriazidou; Harry F. Contopanagos; N. G. Alexopoulos

1999-01-01

198

Frequency shifts and modulation effects due to solenoidal magnetic field inhomogeneities in ion cyclotron mass spectrometry  

NASA Astrophysics Data System (ADS)

Solenoidal (i.e. axially symmetric) magnetic field inhomogeneities, which in addition have symmetry under the operation z --> -z are the most important to Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometry since they introduce frequency shifts at first-order in perturbation theory. Frequency shifts for all three fundamental modes are derived for the leading second-order and fourth-order solenoidal inhomogeneities without any restrictions on the initial conditions. The analytical frequency shifts agree very well with frequency shifts obtained from numerical trajectory calculations using the exact classical equations of motion. The effect of the inhomogeneity on the ion trajectory is solved analytically. For a strong magnetic bottle field, the cyclotron motion is frequency modulated at twice the z-oscillation frequency resulting in sidebands. However, the amplitude of these sidebands is negligibly small for typical inhomogeneity strengths. The effect of a magnetized ICR trap on the homogeneity of the magnetic field is studied by analytical methods. We find that the leading magnetic bottle field decreases as d-3, where d is the cylindrical ion trap diameter.

Mitchell, Dale W.; Rockwood, Alan L.; Smith, Richard D.

1995-02-01

199

Modified field enhancement and extinction by plasmonic nanowire dimers due to nonlocal response  

NASA Astrophysics Data System (ADS)

We study the effect of nonlocal optical response on the optical properties of metallic nanowires, by numerically implementing the hydrodynamical Drude model for arbitrary nanowire geometries. We first demonstrate the accuracy of our frequency-domain finite-element implementation by benchmarking it in a wide frequency range against analytical results for the extinction cross section of a cylindrical plasmonic nanowire. Our main results concern more complex geometries, namely cylindrical and bow-tie nanowire dimers that can strongly enhance optical fields. For both types of dimers we find that nonlocal response can strongly affect both the field enhancement in between the dimers and their respective extinction cross sections. In particular, we give examples of maximal field enhancements near hybridized plasmonic dimer resonances that are still large but nearly two times smaller than in the usual local-response description. At the same time, for a fixed frequency the field enhancement and cross section can also be significantly more enhanced in the nonlocal-response model.

Toscano, Giuseppe; Raza, Søren; Jauho, Antti-Pekka; Mortensen, N. Asger; Wubs, Martijn

2012-02-01

200

Assessment of the magnetic field exposure due to the battery current of digital mobile phones.  

PubMed

Hand-held digital mobile phones generate pulsed magnetic fields associated with the battery current. The peak value and the waveform of the battery current were measured for seven different models of digital mobile phones, and the results were applied to compute approximately the magnetic flux density and induced currents in the phone-user's head. A simple circular loop model was used for the magnetic field source and a homogeneous sphere consisting of average brain tissue equivalent material simulated the head. The broadband magnetic flux density and the maximal induced current density were compared with the guidelines of ICNIRP using two various approaches. In the first approach the relative exposure was determined separately at each frequency and the exposure ratios were summed to obtain the total exposure (multiple-frequency rule). In the second approach the waveform was weighted in the time domain with a simple low-pass RC filter and the peak value was divided by a peak limit, both derived from the guidelines (weighted peak approach). With the maximum transmitting power (2 W) the measured peak current varied from 1 to 2.7 A. The ICNIRP exposure ratio based on the current density varied from 0.04 to 0.14 for the weighted peak approach and from 0.08 to 0.27 for the multiple-frequency rule. The latter values are considerably greater than the corresponding exposure ratios 0.005 (min) to 0.013 (max) obtained by applying the evaluation based on frequency components presented by the new IEEE standard. Hence, the exposure does not seem to exceed the guidelines. The computed peak magnetic flux density exceeded substantially the derived peak reference level of ICNIRP, but it should be noted that in a near-field exposure the external field strengths are not valid indicators of exposure. Currently, no biological data exist to give a reason for concern about the health effects of magnetic field pulses from mobile phones. PMID:14695008

Jokela, Kari; Puranen, Lauri; Sihvonen, Ari-Pekka

2004-01-01

201

Heat flux due to poloidal electric field in the banana regime  

SciTech Connect

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.

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

1992-02-01

202

Effect of the Plate Thickness on the Out-of-Plane Displacement Field of a Cracked Elastic Plate Loaded in Mode I  

Microsoft Academic Search

The paper presents analytical results on the out-of-plane displacement of the lateral surface of a plate in the vicinity of\\u000a a through-the-thickness crack at different ratios of the crack length to the plate thickness. The theoretical approach is\\u000a based on a recently developed three-dimensional elastic solution for an edge dislocation in a plate of arbitrary thickness\\u000a and the standard distributed

Andrei Kotousov; Peng Jing Tan

2004-01-01

203

Giant Spin-Orbit Interaction Due to Rotating Magnetic Fields in Graphene Nanoribbons  

NASA Astrophysics Data System (ADS)

We study graphene nanoribbons theoretically in the presence of spatially varying magnetic fields produced, e.g., by nanomagnets. We show, both analytically and numerically, that an exceptionally large Rashba spin-orbit interaction of the order of 10 meV can be produced by a nonuniform magnetic field. As a consequence, helical modes exist in armchair nanoribbons that exhibit nearly perfect spin polarization and are robust against boundary defects. This result paves the way for realizing spin-filter devices in graphene nanoribbons in the temperature regime of a few kelvins. If a nanoribbon in the helical regime is in proximity contact to an s-wave superconductor, the nanoribbon can be tuned into a topological phase that sustains Majorana fermions.

Klinovaja, Jelena; Loss, Daniel

2013-01-01

204

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

SciTech Connect

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.

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

205

Asymmetric switching behavior in perpendicularly magnetized spin-valve nanopillars due to the polarizer dipole field  

NASA Astrophysics Data System (ADS)

We report the free layer switching field distributions of spin-valve nanopillars with perpendicular magnetization. While the distributions are consistent with a thermal activation model, they show a strong asymmetry between the parallel to antiparallel and the reverse transition, with energy barriers more than 50% higher for the parallel to antiparallel transitions. The inhomogeneous dipolar field from the polarizer is demonstrated to be at the origin of this symmetry breaking. Interestingly, the symmetry is restored for devices with a lithographically defined notch pair removed from the midpoint of the pillar cross-section along the ellipse long axis. These results have important implications for the thermal stability of perpendicular magnetized magnetic random access memory bit cells.

Gopman, D. B.; Bedau, D.; Mangin, S.; Lambert, C. H.; Fullerton, E. E.; Katine, J. A.; Kent, A. D.

2012-02-01

206

Reduction of crossed-field diode transmitted current due to anode secondary emission  

NASA Astrophysics Data System (ADS)

The limiting current theory for planar crossed-field diodes has long been studied extensively for various emission energies and temperatures. However, experimental measurements of transmitted current have shown significant departure from theory. This paper attempts to explain the reduction in transmitted current from that expected in theory in terms of secondary electron emission created by electrons hitting the anode. It is proposed that the presence of the secondary electrons increases the charge density in the gap, thereby reducing the amount of current transmitted. A detailed secondary emission model is implemented in a particle-in-cell code to study current reduction. The effect of secondary electrons on charge density, and on the resultant electric field and potential is also presented.

Gopinath, V. P.; Vanderberg, B. H.

1998-01-01

207

Ultrasonic propagation velocity in magnetic and magnetorheological fluids due to an external magnetic field.  

PubMed

Ultrasonic propagation velocity in a magnetic fluid (MF) and magnetorheological fluid (MRF) changes with the application of an external magnetic field. The formation of clustering structures inside the MF and MRF clearly has an influence on the ultrasonic propagation velocity. Therefore, we propose a qualitative analysis of these structures by measuring properties of ultrasonic propagation. Since MF and MRF are opaque, non-contact inspection using the ultrasonic technique can be very useful for analyzing the inner structures of MF and MRF. In this study, we measured ultrasonic propagation velocity in a hydrocarbon-based MF and MRF precisely. Based on these results, the clustering structures of these fluids are analyzed experimentally in terms of elapsed time dependence and the effect of external magnetic field strength. The results reveal hysteresis and anisotropy in the ultrasonic propagation velocity. We also discuss differences of ultrasonic propagation velocity between MF and MRF. PMID:21386478

Bramantya, M A; Motozawa, M; Sawada, T

2010-08-18

208

Electromagnetic force analysis of HTS bulk in DC-magnetic fields due to electromagnet  

Microsoft Academic Search

A new type linear synchronous motor which is based on an idea considering pinning force of high temperature superconducting (HTS) bulk as synchronizing force in using current-carrying-armature winding is proposed. However, HTS bulk could not produce lift force enough to levitate the HTS bulk ship for basic experiments. To research larger lift force, DC-magnet which generates higher magnetic fields has

K. Yoshida; H. Matsumoto

2002-01-01

209

Electromagnetic field in the sea due to an omnidirectional VLF antenna  

NASA Astrophysics Data System (ADS)

The physical and electrical properties of typical VLF transmitters are described, and new formulas are given for the electromagnetic field they generate on the surface of and at any depth in the sea. These apply to the spherical earth at frequencies in the range 14 ? ƒ ? 30 kHz. They are useful for distances up to 10,000 km. Special application is made to communication with submerged submarines equipped with horizontal antennas.

King, Ronold W. P.; Harrison, Charles W., Jr.; Houdzoumis, Vassilios A.

1997-01-01

210

Long Time Range Breakdown Due to Field Distortion in PET Film Subjected to Step Voltage  

Microsoft Academic Search

When a relatively low step voltage was applied to a PET film, the breakdown time lags were normally distributed in the minute range. The mean time lag at a field strength of 4.5 MV\\/cm, as an example, was 451 seconds at 25°C, 185 seconds at 40°C and 79 seconds at 60°C, respectively. The periodic reversal of the polarity of the

Isamu Kitani; Kiyomitsu Arii

1986-01-01

211

Novel Theoretical and Numerical Methods for the Computation of Electromagnetic Fields due to Current Sources  

Microsoft Academic Search

In this dissertation, series expansions are developed for the Incomplete Lipschitz-Hankel integrals (ILHIs) Je_0(a,z) and Ye_0(a,z). These expansions are obtained using the Laplace transform technique together with the theory of contour integration. These special functions are encountered in the solutions for numerous problems in electromagnetics. For example, ILHIs are used in this dissertation to obtain exact, closed-form field expressions for

Mehdi Mohamad Mechaik

1994-01-01

212

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

SciTech Connect

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.

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

213

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

NASA Astrophysics Data System (ADS)

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.

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

2010-05-01

214

A model free real space reconstruction of the magnetic field due to the vortex lattice  

NASA Astrophysics Data System (ADS)

Typically small angle neutron scattering (SANS) experiments on the vortex lattice of type II superconductors measures only the first order Bragg reflections. If higher order Bragg reflections are measured they are simply ignored. In our study, the measured higher order Bragg reflections allow us to perform a more comprehensive data analysis with minimum theoretical input. We have performed SANS experiments on the non-magnetic members, YNi 2B2C and LuNi2B2C and the magnetic member, TmNi2B2C of the rare-earth nickel borocarbide family of superconductors. With an unprecedented number of reflections observed, we are able to analysis the vortex lattice form factors in a model free fashion to calculate the magnetic field modulation. LuNi2B2C displayed highest number of observed Bragg reflections where up to the (32) reflection was measured. With our model free analysis of the magnetic field modulation, we compare our results with numerical calculation based on the quasiclassical Eilenberger theory performed by Ichioka et al. Our results are most consistent with an anisotropic superconducting gap, either d-wave or anisotropic s-wave. The magnetic field reconstruction in all three materials studied are consistent and robust. While the absolute values of the field does change with variation of the form factors, the overall features do not change. The radius of the vortex core, defined as the maximum in the superconducting screening current, was calculated and agreed reasonably with coherence length measurements. The current around the vortex displayed a four-fold anisotropy which is typical of the borocarbides. The vortex lattice was measured in both square and rhombic unit cell symmetries. A symmetrization of the rhombic unit cell to square unit cell shows no appreciable change in the magnetic field reconstruction. With measurements done on both magnetic and non-magnetic borocarbides, we are able to estimate the interaction between magnetism and superconductivity on the measured vortex lattice form factors in TmNi2B2C.

Densmore, John Michael

215

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

NASA Astrophysics Data System (ADS)

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.

Dontsov, Egor V.; Guzina, Bojan B.

2012-10-01

216

Internal electric fields due to piezoelectric and spontaneous polarizations in CdZnO/MgZnO quantum well with various applied electric field effects  

NASA Astrophysics Data System (ADS)

The strain-induced piezoelectric polarization and the spontaneous polarization can be reduced effectively using the applied electric field in the CdZnO/ZnMgO quantum well (QW) structure with high Cd composition. That is, optical properties as a function of internal and external fields in the CdZnO/ZnMgO QW with various applied electric field result in the increased optical gain due to the fact that the QW potential profile is flattened as a result of the compensation of the internal field by the reverse field as confirmed. These results demonstrate that a high-performance optical device operation can be realized in CdZnO/MgZnO QW structures by reducing the droop phenomenon.

Jeon, H. C.; Lee, S. J.; Kang, T. W.; Park, S. H.

2012-05-01

217

Materials damage due to acid deposition - A field study in southern California  

SciTech Connect

The Kapiloff Acid Deposition Act of 1982 requires the California Air Resources Board (CARB) to assess the economic impact of acid deposition upon materials as part of a comprehensive research program to determine the nature, extent and potential effects of acid deposition in California. Prior to assessing the economic impact, major uncertainties must be resolved concerning the specific roles of acid deposition constituents in materials damage. Field exposure and laboratory chamber experiments to quantify these specific roles are being conducted in a joint project between Environmental Monitoring and Services, Inc. (EMSI), Rockwell International Science Center (RISC), and University of Southern California (USC).

Vijayakumar, R.; Hillestad, R.; Jeanjaquet, S.L.; Mansfeld, F.

1987-01-01

218

Self-assembly of amorphous silicon island systems due to field-induced selectivity  

NASA Astrophysics Data System (ADS)

The structure and morphology characteristics of the surface of amorphous silicon (a-Si) condensates have been studied by the method of scanning electron microscopy (SEM). The SEM data revealed self-organization processes that lead to the formation of a-Si islands with similar shapes and sizes. A mathematical model is developed that partly explains the observed self-organization of island systems under the conditions of ultimately low supersaturations in the presence of an electric field at the growth surface and the deposition of ionized substance.

Kosminska, Yu. A.; Mokrenko, A. A.; Perekrestov, V. I.

2011-06-01

219

Effects of Magnetic Field on Entropy Generation in Flow and Heat Transfer due to a Radially Stretching Surface  

NASA Astrophysics Data System (ADS)

We investigate the effects of magnetic field on the entropy generation during fluid flow and heat transfer due to the radially stretching surface. The partial differential equations governing the flow and heat transfer phenomenon are transformed into nonlinear ordinary differential equations by using suitable similarity transformations. These equations are then solved by the homotopy analysis method and the shooting technique. The effects of the magnetic field parameter M and the Prandtl number Pr on velocity and the temperature profiles are presented. Moreover, influence of the magnetic field parameter M and the group parameter Br/? on the local entropy generation number Ns as well as the Bejan number Be are inspected. It is observed that the magnetic field is a strong source of entropy production in the considered problem.

Adnan Saeed, Butt; Asif, Ali

2013-02-01

220

Multicomponent seismic monitoring of strain due to carbon dioxide injection at Delhi Field, Louisiana  

NASA Astrophysics Data System (ADS)

Time-lapse, multicomponent seismic data are used in this thesis to monitor geomechanical changes within the reservoir and in the overburden layers at Delhi Field, Louisiana. Multicomponent seismic data are important for monitoring gas saturation and pressure changes associated with CO2 flooding. A seismic survey acquired before CO2 injection operations began serves as a baseline survey and a pair of multicomponent monitor surveys acquired during first two years of injection allow time-lapse analysis of amplitude differences and time-shifts between seismic surveys. Time-lapse seismic data are used for mapping fluid and pressure changes within the reservoir interval. Reservoir pressure increases at Delhi Field cause overburden compaction and time-shifts between seismic monitor surveys. Vertical strain in the overburden is calculated from compressional and converted wave time-shifts and provide quantitative insight into how injection operations affect overburden layers. Strain estimated from converted wave seismic data shows both a different pattern and magnitude than strain estimated from compressional seismic data. Monitoring these geomechanical changes enables the calibration of geomechanical models to understand the influence of reservoir dynamics on the overburden and the underburden.

Bishop, John E., Jr.

221

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

SciTech Connect

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.

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

2010-11-01

222

Excessive magnetic field flux density distribution from overhead isolated powerline conductors due to neutral line current.  

PubMed

Overhead isolated powerline conductors (hereinafter: "OIPLC") are the most compact form for distributing low voltage currents. From the known physics of magnetic field emission from 3-phase power lines, it is expected that excellent symmetry of the 120° shifted phase currents and where compact configuration of the 3-phase+neutral line exist, the phase current vectorial summation of the magnetic field flux density (MFFD) is expected to be extremely low. However, despite this estimation, an unexpectedly very high MFFD was found in at least three towns in Israel. This paper explains the reasons leading to high MFFD emissions from compact OIPLC and the proper technique to fix it. Analysis and measurement results had led to the failure hypothsis of neutral line poor connection design and poor grounding design of the HV-LV utility transformers. The paper elaborates on the low MFFD exposure level setup by the Israeli Environmental Protection Office which adopted a rather conservative precaution principal exposure level (2 mG averaged over 24 h). PMID:23675630

Netzer, Moshe

2013-06-01

223

Topographic change in ERP due to discrimination of geometric figures in the peripheral visual field.  

PubMed

The present study examined the neurophysiological aspects of discrimination of geometric figures with different eccentricities. In the behavioral experiment, a circle and 3 geometric polygons (square, hexagon, or octagon) were presented for 300 ms at quadrant locations. The eccentricity was changed from 2 degrees to 16 degrees at 2 degrees intervals. The participants (10 adults) were instructed to fixate the center of the CRT and find the circle among the polygons. In the neurophysiological experiment, 4 identical stimuli (squares, hexagons, octagons, or circles) were presented at an eccentricity of 4 degrees, 8 degrees, or 12 degrees. Discrimination performance in the periphery declined when the angularity of the polygons increased. ERP components at 80 ms (P1 with posterior positivity) and 140 ms (N1 with posterior negativity) were observed regardless of the eccentricity or shape of the stimuli. N1 lasted longer as eccentricity increased. P2 with posterior positivity at 200 ms became blurred in the periphery, except for squares. The topography of N1 and P2 changed, depending on the retinal stimulus location; it was influenced by the angularity of the geometric figures in the peripheral visual field. Cerebral processing concerned with N1 and P2 might play an important role in the perception and recognition of visual objects in the peripheral visual field. PMID:16650494

Shoji, Hiroaki; Ozaki, Hisaki

2006-10-01

224

Global simulation of proton precipitation due to field line curvature during substorms  

NASA Astrophysics Data System (ADS)

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.

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

2012-05-01

225

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

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

226

Vibroacoustic Response of Residential Housing due to Sonic Boom Exposure: A Summary of two Field Tests  

NASA Technical Reports Server (NTRS)

Two experiments have been performed to measure the vibroacoustic response of houses exposed to sonic booms. In 2006, an old home in the base housing area of Edwards Air Force Base, built around 1960 and demolished in 2007, was instrumented with 288 transducers. During a 2007 follow-on test, a newer home in the base housing area, built in 1997, was instrumented with 112 transducers. For each experiment, accelerometers were placed on walls, windows and ceilings in bedrooms of the house to measure the vibration response of the structure. Microphones were placed outside and inside the house to measure the excitation field and resulting interior sound field. The vibroacoustic response of each house was measured for sonic boom amplitudes spanning from 2.4 to 96 Pa (0.05 to 2 lbf/sq ft). The boom amplitudes were systematically varied using a unique dive maneuver of an F/A-18 airplane. In total, the database for both houses contains vibroacoustic response data for 154 sonic booms. In addition, several tests were performed with mechanical shaker excitation of the structure to characterize the forced response of the houses. The purpose of this paper is to summarize all the data from these experiments that are available to the research community, and to compare and contrast the vibroacoustic behavior of these two dissimilar houses.

Klos, Jacob; Buehrle, Ralph; Sullivan, Brenda; Gavin, Joseph; Salamone, Joseph; Haering, Edward A., jr.; Miller, Denise M.

2008-01-01

227

Stability of Miscible Displacements Across Stratified Porous Media  

SciTech Connect

This report studied macro-scale heterogeneity effects. Reflecting on their importance, current simulation practices of flow and displacement in porous media were invariably based on heterogeneous permeability fields. Here, it was focused on a specific aspect of such problems, namely the stability of miscible displacements in stratified porous media, where the displacement is perpendicular to the direction of stratification.

Shariati, Maryam; Yortsos, Yanis C.

2000-09-11

228

Estimation of Displacement Location for Enhanced Strain Imaging  

Microsoft Academic Search

Ultrasonic strain imaging usually begins with displacement estimates computed using finite-length sections of RF ultrasound signals. Amplitude variations in the ultrasound are known to perturb the location at which the displacement estimate is valid. If this goes uncorrected, it is a significant source of estimation noise, which is amplified when displacement fields are converted into strain images. We present a

Joel E. Lindop; Graham M. Treece; Andrew H. Gee; Richard W. Prager

2007-01-01

229

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

NASA Astrophysics Data System (ADS)

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.

Kim, Junhee; Kim, Kiyoung; Sohn, Hoon

2014-01-01

230

Residential Displacement: An Update.  

National Technical Information Service (NTIS)

The report provides an assessment of the displacement phenomenon, based mainly on the results of HUD-sponsored research and technical assistance projects. A summary of these projects' results addresses the neighborhood revitalization process and displacem...

M. S. Davis G. Ferguson

1981-01-01

231

Entanglement production due to quench dynamics of an anisotropic XY chain in a transverse field  

NASA Astrophysics Data System (ADS)

We compute concurrence and negativity as measures of two-spin entanglement generated by a power-law quench (characterized by a rate ?-1 and an exponent ? ) which takes an anisotropic XY chain in a transverse field through a quantum critical point (QCP). We show that only spins separated by an even number of lattice spacings get entangled in such a process. Moreover, there is a critical rate of quench, ?c-1 , above which no two-spin entanglement is generated; the entire entanglement is multipartite. The ratio of the entanglements between consecutive even neighbors can be tuned by changing the quench rate. We also show that for large ? , the concurrence (negativity) scales as ?/? (?/?) , and we relate this scaling behavior to defect production by the quench through a QCP.

Sengupta, K.; Sen, Diptiman

2009-09-01

232

Electromagnetic wake-field due to surface roughness in an optical structure  

NASA Astrophysics Data System (ADS)

In this study we investigate the properties of the electromagnetic wake-field generated by an electron bunch moving in the vicinity of an optical structure of finite roughness. The model employed consists of a metallic cylindrical waveguide to which grooves of random width, height, and location are attached. Based on this model analytic expressions have been developed for the average energy emitted per groove and for its standard deviation. As expected, both quantities are virtually independent of the momentum in a highly relativistic regime and the average energy emitted per groove is proportional to the roughness parameter. Moreover, it has been found that the standard deviation of the energy emitted per groove is proportional to the standard deviation of the roughness parameter to the power of 1/4. The cumulative effect of surface roughness was studied resorting to both periodic and quasiperiodic structures-significant differences in the spectrum have been observed only for low frequencies.

Banna, S.; Schieber, D.; Schächter, L.

2004-04-01

233

Second Law Violations by Means of a Stratification of Temperature Due to Force Fields  

NASA Astrophysics Data System (ADS)

In 1868 J.C. Maxwell proved that a perpetual motion machine of the second kind would become possible, if the equilibrium temperature in a vertical column of gas subject to gravity were a function of height. However, Maxwell had claimed that the temperature had to be the same at all points of the column. So did Boltzmann. Their opponent was Loschmidt. He claimed that the equilibrium temperature declined with height, and that a perpetual motion machine of the second kind operating by means of such column was compatible with the second law of thermodynamics. Extending the general idea behind Loschmidt's concept to other force fields, gravity can be replaced by molecular forces acting on molecules that try to escape from the surface of a liquid into the vapor space. Experiments proving the difference of temperature between the liquid and the vapor phase were conducted in the 19th century already.

Trupp, Andreas

2002-11-01

234

Advanced Triangulation Displacement Sensors  

NASA Technical Reports Server (NTRS)

Advanced optoelectronic triangulation displacement sensors undergoing development. Highly miniaturized, more stable, more accurate, and relatively easy to use. Incorporate wideband electronic circuits suitable for real-time monitoring and control of displacements. Measurements expected to be accurate to within nanometers. In principle, sensors mass-produced at relatively low unit cost. Potential applications numerous. Possible industrial application in measuring runout of rotating shaft or other moving part during fabrication in "zero-defect" manufacturing system, in which measured runout automatically corrected.

Poteet, Wade M.; Cauthen, Harold K.

1996-01-01

235

Measurement of electric fields induced in a human subject due to natural movements in static magnetic fields or exposure to alternating magnetic field gradients  

NASA Astrophysics Data System (ADS)

A dual dipole electric field probe has been used to measure surface electric fields in vivo on a human subject over a frequency range of 0.1-800 Hz. The low-frequency electric fields were induced by natural body movements such as walking and turning in the fringe magnetic fields of a 3 T magnetic resonance whole-body scanner. The rate-of-change of magnetic field (dB/dt) was also recorded simultaneously by using three orthogonal search coils positioned near to the location of the electric field probe. Rates-of-change of magnetic field for natural body rotations were found to exceed 1 T s-1 near the end of the magnet bore. Typical electric fields measured on the upper abdomen, head and across the tongue for 1 T s-1 rate of change of magnetic field were 0.15 ± 0.02, 0.077 ± 0.003 and 0.015 ± 0.002 V m-1 respectively. Electric fields on the abdomen and chest were measured during an echo-planar sequence with the subject positioned within the scanner. With the scanner rate-of-change of gradient set to 10 T m-1 s-1 the measured rate-of-change of magnetic field was 2.2 ± 0.1 T s-1 and the peak electric field was 0.30 ± 0.01 V m-1 on the chest. The values of induced electric field can be related to dB/dt by a 'geometry factor' for a given subject and sensor position. Typical values of this factor for the abdomen or chest (for measured surface electric fields) lie in the range of 0.10-0.18 m. The measured values of electric field are consistent with currently available numerical modelling results for movement in static magnetic fields and exposure to switched magnetic field gradients.

Glover, P. M.; Bowtell, R.

2008-01-01

236

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

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

237

Piezophotonic Switching Due to Local Field Effects in a Coherently Prepared Medium of Three-Level Atoms  

NASA Astrophysics Data System (ADS)

We study the effect of near dipole-dipole interactions on the electric susceptibility of a coherently prepared three-level ? system. We discuss the influence of atomic nonlinearities on the recently predicted enhancement of the absorptionless index of refraction and inversionless gain due to local field effects [J.P. Dowling and C.M. Bowden,

Phys. Rev. Lett. 70 1421 1993
] and predict a density dependent, or piezophotonic, switching between absorption and amplification.

Manka, Aaron S.; Dowling, Jonathan P.; Bowden, Charles M.; Fleischhauer, Michael

1994-09-01

238

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

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

239

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

240

Fragmentation and isomerization due to field heating in traveling wave ion mobility spectrometry.  

PubMed

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. PMID:24845353

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

2014-08-01

241

The nature and origin of off-fault damage surrounding strike-slip fault zones with a wide range of displacements: A field study from the Atacama fault system, northern Chile  

NASA Astrophysics Data System (ADS)

Damage surrounding the core of faults is represented by deformation on a range of scales from microfracturing of the rock matrix to macroscopic fracture networks. The spatial distribution and geometric characterization of damage at various scales can help to predict fault growth processes, subsequent mechanics, bulk hydraulic and seismological properties of a fault zone. Within the excellently exposed Atacama fault system, northern Chile, micro- and macroscale fracture densities and orientation surrounding strike-slip faults with well-constrained displacements ranging over nearly 5 orders of magnitude (˜0.12 m-5000 m) have been analyzed. Faults have been studied that cut granodiorite and have been passively exhumed from 6 to 10 km depth. This allows direct comparison of the damage surrounding faults of different displacements. The faults consist of a fault core and associated damage zone. Macrofractures in the damage zone are predominantly shear fractures orientated at high angles to the faults studied. They have a reasonably well-defined exponential decrease with distance from the fault core. Microfractures are a combination of open, healed, partially healed and fluid inclusion planes (FIPs). FIPs are the earliest set of fractures and show an exponential decrease in fracture density with perpendicular distance from the fault core. Later microfractures do not show a clear relationship of microfracture density with perpendicular distance from the fault core. Damage zone widths defined by the density of FIPs scale with fault displacement but appear to reach a maximum at a few km displacement. One fault, where damage was characterized on both sides of the fault core shows no damage asymmetry. All faults appear to have a critical microfracture density at the fault core/damage zone boundary that is independent of displacement. An empirical relationship for microfracture density distribution with displacement is presented. Preferred FIP orientations have a high angle to the fault close to the fault core and become more diffuse with distance. Models that predict off-fault damage such as a migrating process zone during fault formation, wear from geometrical irregularities and dynamic rupture are all consistent with our data. We conclude it is very difficult to distinguish between them on the basis of field data alone, at least within the limits of this study.

Mitchell, T. M.; Faulkner, D. R.

2009-08-01

242

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

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

Yuri Fialko

2004-01-01

243

The generalized uncertainty principle and the quantum entropy due to spin fields on the Reissner-Nordström black hole background  

NASA Astrophysics Data System (ADS)

By using the null tetrad and the 't Hooft brick-wall model, the quantum entropies of a Reissner-Nordström black hole due to the Weyl neutrino, electromagnetic, massless Rarita-Schwinger and gravitational fields for the source-free case are investigated from a generalized uncertainty principle. The divergence structure for the entropy is demonstrated. In addition to the usual linearly and logarithmically divergent terms, additional quadratic, cubic, biquadratic and other higher order divergences exist near the event horizon in the entropy, which not only depend on the black hole characteristics but also on the spin fields and the gravitational interactions. The terms describe the contribution of the quantum fields to the entropy and the effects of the generalized uncertainty principle on it. If the smallest length scale is taken into account, the contribution of the gravitational interactions to the entropy is found to be a part of the dominant term and very important, and therefore it can not be neglected.

Li, Guqiang

2014-06-01

244

Field Observation and Numerical Simulation on Sediment Yield Due to Freeze and Thaw Action  

NASA Astrophysics Data System (ADS)

Because most parts of the Japanese islands are located within temperate to subarctic climatic zones, freeze and thaw action during winter can be observed frequently in most mountainous areas. The freeze-thaw action usually causes bedrock weathering and produces sediment. Erosion induced by freeze-thaw action appears to be a major source of sediment from mountainous areas to streams. However, these processes are little understood. In this research, a detailed field observation was conducted to elucidate mechanisms of freeze-thaw action and the sediment yield on a bare slope in southern Shiga Prefecture, Japan. The bedrock of the observed bare slope consists of granite and is highly weathered. Two small plots (plots 1 and 2) were established by partitioning these areas with plastic borders. For each plot, surface and subsurface temperatures at depths of 0, 10, 25 and 50 cm, as well as air temperature were continuously measured every 10 min during the observation period from December 2004 to April 2005. The sediment produced from weathered bedrock was collected and weighed once in a week from the plot 1. In plot 2, the sediment was not disturbed and remained on the bedrock until the end of observation period. From the observation results, it was shown that the freeze-thaw action occurred repeatedly, and the freezing front where the bedrock temperature is 0 degree C, reached a depth of 10 cm. Sediment was actively produced when freeze-thaw action was observed; when freeze-thaw action stopped in April 2005, sediment yield decreased markedly. Sediment yields from plots 1 and 2 were 108 and 44 kg/m2/year, respectively. This difference indicates that the sediment cover on the bedrock surface mitigated the effect of freeze-thaw action on sediment yield from the bedrock. These observed results were simulated by a simplified thermal conductivity analysis. Comparison between the observed and simulated results suggests that multiple episodes of freeze-thaw activity are necessary for the bedrock to be converted into sediment.

Tsutsumi, D.; Fujita, M.; Sawada, T.

2007-05-01

245

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

SciTech Connect

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.

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

246

Ultra-Sensitive Magnetoresistive Displacement Sensing Device  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

247

Water displacement mercury pump  

DOEpatents

A water displacement mercury pump has a fluid inlet conduit and diffuser, a valve, a pressure cannister, and a fluid outlet conduit. The valve has a valve head which seats in an opening in the cannister. The entire assembly is readily insertable into a process vessel which produces mercury as a product. As the mercury settles, it flows into the opening in the cannister displacing lighter material. When the valve is in a closed position, the pressure cannister is sealed except for the fluid inlet conduit and the fluid outlet conduit. Introduction of a lighter fluid into the cannister will act to displace a heavier fluid from the cannister via the fluid outlet conduit. The entire pump assembly penetrates only a top wall of the process vessel, and not the sides or the bottom wall of the process vessel. This insures a leak-proof environment and is especially suitable for processing of hazardous materials.

Nielsen, Marshall G. (Woodside, CA)

1985-01-01

248

Water displacement mercury pump  

DOEpatents

A water displacement mercury pump has a fluid inlet conduit and diffuser, a valve, a pressure cannister, and a fluid outlet conduit. The valve has a valve head which seats in an opening in the cannister. The entire assembly is readily insertable into a process vessel which produces mercury as a product. As the mercury settles, it flows into the opening in the cannister displacing lighter material. When the valve is in a closed position, the pressure cannister is sealed except for the fluid inlet conduit and the fluid outlet conduit. Introduction of a lighter fluid into the cannister will act to displace a heavier fluid from the cannister via the fluid outlet conduit. The entire pump assembly penetrates only a top wall of the process vessel, and not the sides or the bottom wall of the process vessel. This insures a leak-proof environment and is especially suitable for processing of hazardous materials.

Nielsen, M.G.

1984-04-20

249

Bragg optical displacement sensor  

NASA Astrophysics Data System (ADS)

A novel optical displacement sensor based on Bragg effect is described. A green light bema was used to excite a Rh6G dye solution in Shank type geometry. The beam was split up by a dielectric mirror and the two equal intensity vertically polarized light beams were folded by two mirrors to interfere in the dye cell. The lasing wavelength was found to be a precise function of the half angle between the beams. The vibrating body was attached to one of the folding mirror. In normal operation the lasing line wavelength was unchanged but during mirror vibration corresponding to this 1 degree was 87 micrometers . The sensor resolution was about 1.3 angstrom/micrometers . This ultrashell displacement sensor can be used to determine the frequency of vibration or simple displacements in ultraprecise applications.

Khan, Nasrullah

1999-11-01

250

Optical displacement sensor  

DOEpatents

An optical displacement sensor is disclosed which uses a vertical-cavity surface-emitting laser (VCSEL) coupled to an optical cavity formed by a moveable membrane and an output mirror of the VCSEL. This arrangement renders the lasing characteristics of the VCSEL sensitive to any movement of the membrane produced by sound, vibrations, pressure changes, acceleration, etc. Some embodiments of the optical displacement sensor can further include a light-reflective diffractive lens located on the membrane or adjacent to the VCSEL to control the amount of lasing light coupled back into the VCSEL. A photodetector detects a portion of the lasing light from the VCSEL to provide an electrical output signal for the optical displacement sensor which varies with the movement of the membrane.

Carr, Dustin W. (Albuquerque, NM)

2008-04-08

251

Internally displaced persons.  

PubMed

There were estimated to be over 20 million internally displaced persons (IDPs) at the end of 1999, a number that surpasses global estimates of refugees. Displacement exposes IDPs to new hazards and accrued vulnerability. These dynamics result in greater risk for the development of illness and death. Often, access of IDPs to health care and humanitarian assistance is excluded deliberately by conflicting parties. Furthermore, the arrival of IDPs into another community or region strains local health systems, and the host population ends up sharing the sufferings of the internally displaced. Health outcomes are dismaying. From a health perspective, the best option is to avoid human displacement. WHO contributes to the prevention of displacement by working for sustainable development. Placing health high on the political agenda helps maintain stability, and thereby, reduce the likelihood for displacement. Primary responsibility for assisting IDPs, irrespective of the cause, rests with the national government. However, where the government is unwilling or unable to provide the necessary aid, the international humanitarian community must step in, with WHO playing a major role in the health sector. There is consensus among the partners of the World Health Organization (WHO) that, in emergencies, the WHO must: 1) take the lead in rapid health assessment, epidemiological and nutritional surveillance, epidemic preparedness, essential drugs management, control of communicable diseases, and physical and psychosocial rehabilitation; and 2) provide guidelines and advice on nutritional requirements and rehabilitation, immunisation, medical relief items, and reproductive health. If the vital health needs of IDPs--security, food, water, shelter, sanitation and household items--are not satisfied, the provision of health services alone cannot save lives. Community participation is essential, and community participation implies bolstering the assets and capacities of the beneficiaries. PMID:11875794

Leus, X; Wallace, J; Loretti, A

2001-01-01

252

PDT - PARTICLE DISPLACEMENT TRACKING SOFTWARE  

NASA Technical Reports Server (NTRS)

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.

Wernet, M. P.

1994-01-01

253

Magnetic field energy dissipation due to particle trapping in a force-free configuration of collisionless pair plasmas.  

PubMed

It is shown by using a two-dimensional, fully relativistic, electromagnetic particle-in-cell simulation code that a force-free magnetic configuration in collisionless, electron-positron (pair) plasmas becomes unstable against current-driven Buneman instability and subsequently there occurs a strong magnetic field energy dissipation associated with collisionless magnetic reconnection, which can be driven by particle trapping due to two-dimensional electric potentials remaining in the nonlinear stage of the initial current-driven Buneman instability. About 43% of the initial magnetic field energy dissipates and is transformed to plasma heating as well as high-energy particle production. The energy spectrum in the high-energy region is given by an exponential type with two temperatures. We also show the simulation results for the electron-ion plasma to compare the effect of the mass ratio of the electron and proton. PMID:11308957

Sakai, J I; Sugiyama, D; Haruki, T; Bobrova, N; Bulanov, S

2001-04-01

254

Some closed-form solutions of the temperature field due to bending magnet and undulator heating in APS  

SciTech Connect

Several temperature field solutions due to bending magnet and undulator x-ray heating are developed and presented in this paper. The Gaussian power distribution is simulated as the bending magnet whereas a Guassian-parabolic type of power distribution is used for the undulator/wiggler heating. The heating on a two-dimensional plane, three-dimensional block, thin disk, infinite wedge plane, infinite wedge block, and beryllium-copper composite are analyzed. Parametric studies are also included to determine the optimized temperature.

Sheng, I.C.; Nian, T.

1993-07-01

255

Exploration of Quench Initiation Due to Intentional Geometrical Defects in a High Magnetic Field Region of an SRF Cavity  

SciTech Connect

A computer program which was used to simulate and analyze the thermal behaviors of SRF cavities has been developed at Jefferson Lab using C++ code. This code was also used to verify the quench initiation due to geometrical defects in high magnetic field region of SRF cavities. We built a CEBAF single cell cavity with 4 artificial defects near equator, and this cavity has been tested with T-mapping. The preheating behavior and quench initiation analysis of this cavity will be presented here using the computer program.

J. Dai, K. Zhao, G.V. Eremeev, R.L. Geng, A.D. Palczewski; Dai, J. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Palczewski, A. D. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Eremeev, G. V. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Geng, R. L. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Zhao, K. [Institute of Heavy Ion Physics, Peking University, Beijing (China)

2011-07-01

256

Needs of Displaced Homemakers.  

ERIC Educational Resources Information Center

As part of its five-year state plan for vocational education, the California State Department of Education and the Chancellor's Office of the California Community Colleges commissioned a study of the needs of displaced homemakers. (These women's needs were relevant to the state's plans for vocational education because the Education Amendments of…

Arnold, Carolyn; Marzone, Jean

257

Displacement sensors using soft magnetostrictive alloys  

SciTech Connect

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.

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

258

Using time-lapse seismic amplitude data to detect variations of pore pressure and fluid saturation due to oil displacement by water: a numerical study based on one-dimensional prestack inversion  

Microsoft Academic Search

We describe a numerical study performed to appraise the ability of seismic amplitude data to infer the time evolution of pore pressure and fluid saturation due to hydrocarbon production. To this end, we construct a synthetic, spatially heterogeneous hydrocarbon reservoir model that is subject to numerical simulation of multiphase fluid flow. Hydrocarbon production is assumed in the form of one

Omar J Varela; Carlos Torres-Verdín; Mrinal K Sen; Indrajit G Roy

2006-01-01

259

Computing Displacements And Strains From Video Images  

NASA Technical Reports Server (NTRS)

Subpixel digital video image correlation (SDVIC) technique for measuring in-plane displacements on surfaces of objects under loads, without contact. Used for analyses of experimental research specimens or actual service structures of virtually any size or material. Only minimal preparation of test objects needed, and no need to isolate test objects from minor vibrations or fluctuating temperatures. Technique implemented by SDVIC software, producing color-graduated, full-field representations of in-plane displacements and partial derivatives with respect to position along both principal directions in each image plane. From representations, linear strains, shear strains, and rotation fields determined. Written in C language.

Russell, Samuel S.; Mcneill, Stephen R.; Lansing, Matthew D.

1996-01-01

260

Electrostatic oscillations due to filamentary structures in the magnetic-field-aligned flow: The ion-acoustic branch  

NASA Astrophysics Data System (ADS)

Recent space missions such as FAST and Freja report highly structured plasma flows along the magnetic field. Electrostatic fluctuations that can be supported by such inhomogeneous parallel flows are investigated. It is found that even a small transverse gradient in parallel flow can significantly reduce the critical value of the relative ion-electron field-aligned drift for the current-driven electrostatic ion acoustic modes. It is also shown that the shear-modified ion acoustic mode can be excited without any relative field-aligned drift provided that the flow gradient is sufficiently strong. The instability mechanism can be described in a local limit. The new shear-modified ion-acoustic modes considered in this paper are shown to be different from both the nonresonant mode due to a velocity shear in the parallel flow [D'Angelo, 1965] and the resonant classical current-driven ion-acoustic mode [Fried and Gould, 1961]. The new modes discussed in this paper can be excited for typical ionospheric conditions and a wide range of ion-electron temperature ratios. The reported results may explain ionospheric observations of low-frequency ion-acoustic-like waves, especially for ion-electron temperature ratios of the order of unity and larger when the critical current for the homogeneous current-driven ion acoustic mode is significantly above the observed values. Other possible applications of our results to space plasmas are also discussed.

Gavrishchaka, Valeriy V.; Ganguli, Supriya B.; Ganguli, Gurudas I.

1999-06-01

261

Transmitted sound field due to an impulsive line acoustic source bounded by a plate followed by a vortex sheet  

NASA Technical Reports Server (NTRS)

The propagation of sound due to a line acoustic source in the moving stream across a semiinfinite vortex sheet which trails from a rigid plate is examined in a linear theory for the subsonic case. A solution for the transmitted sound field is obtained with the aid of multiple integral transforms and the Wiener-Hopf technique for both the steady state (time harmonic) and initial value (impulsive source) situations. The contour of inverse transform and hence the decomposition of the functions are determined through causality and radiation conditions. The solution obtained satisfies causality and the full Kutta conditions. The transmitted sound field is composed of two waves in both the stady state and initial value problems. One is the wave scattered from the edge of the plate which is associated with the bow wave and the instability wave. These waves exist in the downstream sectors. The other is the wave transmitted through the vortex sheet which is also associated with the instability wave. Regional divisions of the transmitted sound field are identified.

Miura, T.; Chao, C. C.

1980-01-01

262

Visuomotor Adaptation to Displacing Prisms by Adult and Baby Barn Owls  

Microsoft Academic Search

The capacity of barn owls to adapt visuomotor behavior in response to prism-induced displacement of the,visual field was tested in babies and adults. Matched, binocular Fresnel prisms, which displaced the visual field 1 lo, 23\\

Eric I. Knudsen; Phyllis F. Knudsen

263

Displacement and Velocity Ratios  

NSDL National Science Digital Library

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.

Bourassa, James; Rosz, John

2011-04-05

264

Liquid CO2 displacement of water in a dual-permeability pore network micromodel.  

PubMed

Permeability contrasts exist in multilayer geological formations under consideration for carbon sequestration. To improve our understanding of heterogeneous pore-scale displacements, liquid CO(2) (LCO(2))-water displacement was evaluated in a pore network micromodel with two distinct permeability zones. Due to the low viscosity ratio (logM = -1.1), unstable displacement occurred at all injection rates over 2 orders of magnitude. LCO(2) displaced water only in the high permeability zone at low injection rates with the mechanism shifting from capillary fingering to viscous fingering with increasing flow rate. At high injection rates, LCO(2) displaced water in the low permeability zone with capillary fingering as the dominant mechanism. LCO(2) saturation (S(LCO2)) as a function of injection rate was quantified using fluorescent microscopy. In all experiments, more than 50% of LCO(2) resided in the active flowpaths, and this fraction increased as displacement transitioned from capillary to viscous fingering. A continuum-scale two-phase flow model with independently determined fluid and hydraulic parameters was used to predict S(LCO2) in the dual-permeability field. Agreement with the micromodel experiments was obtained for low injection rates. However, the numerical model does not account for the unstable viscous fingering processes observed experimentally at higher rates and hence overestimated S(LCO2). PMID:21774502

Zhang, Changyong; Oostrom, Mart; Grate, Jay W; Wietsma, Thomas W; Warner, Marvin G

2011-09-01

265

Optical displacement measuring device  

Microsoft Academic Search

Theoretical considerations of a lightweight, frictionless, optical displacement measuring device (ODMD) are discussed. Experimental results show its resolution and accuracy to be better than 2.5 x 10 to the -8th m with a linear range of 7.5 x 10 to the -5th m, and less than 0.2% change of voltage signal in 600 hours; it has high cycling ability, no

G. F. Weissmann; H. L. Carter Jr.; R. R. Hart

1979-01-01

266

The 3D lithospheric structure and plate tectonics of the on-going Taiwan arc-continent collision and delamination: a context for understanding patterns of geomorphic uplift and contemporary stress and geodetic displacement fields.  

NASA Astrophysics Data System (ADS)

3D mapping of local and global tomographic data have considerably clarified the underlying architecture and long-term kinematics of ongoing arc-continent collision and subduction reversal in Taiwan, including the role of delamination of the continental mantle lithosphere and lowermost crust as an integral part of the ongoing collision. This subduction by continental delamination produces a new delamination Moho in northernmost Taiwan and is accompanied by extensional deformation and oroclinal bending of the overlying crust and now dead compressional mountain belt in northernmost Taiwan, even though subduction of Eurasian lithosphere continues at depth, with the Eurasian slab extending vertically to the mantle transtion zone. This subducting Eurasian continental lithosphere is continuous as a single intact slab across the Eurasian ocean-continent boundary, with the South China Sea Eurasian lithosphere to the south undergoing classic oceanic subduction. In this presentation we show that a 3D understanding of the geometry and long-term plate kinematics of this arc-continent collision informs and illuminates our understanding of [1] patterns of geomorphic uplift on a 100Ka timescale, [2] contemporary horizontal geodetic displacement fields, and [3] contemporary stress fields in the upper 100km determined from focal-mechanism inversions and borehole breakouts. Patterns of uplift and magmatism are closely linked to the locus of current delamination at depth. The contemporary horizontal displacement field shows on-going oroclinal bending. The very large changes in stress orientation are immediately clarified by their locations relative to fundamental structures, including the delamination Moho and the deep slabs of the Eurasian and Philippine Sea plates.

Suppe, J.; Kanda, R. V.; Carena, S.; Wu, Y.

2012-12-01

267

Estimating mortality displacement during and after heat waves.  

PubMed

The proportion of excess deaths occurring as a result of hot weather that are brought forward by only a short time ("displaced") is important but not easy to estimate. A recent proposal by Saha et al. (Am J Epidemiol. 2014;179(4):467-474) was to estimate this using a "displacement ratio" equal to the sum of deficits of daily deaths below an expected baseline divided by the sum of excesses over all days during and up to 15 days after a heat wave. Unfortunately, this method results in important artifacts due to natural Poisson variation in deaths by which deficits, and hence displacement ratios above zero, will occur even when there is no real short-term displacement. Simulations confirm this and further show spurious patterns, such as the displacement ratio diminishing with more severe waves. This displacement ratio cannot be relied upon for interpretation. Quantifying mortality displacement remains an incompletely resolved problem. PMID:24812157

Armstrong, Ben; Gasparrini, Antonio; Hajat, Shakoor

2014-06-15

268

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

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

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

2008-01-01

269

Experimental investigation of local displacement speeds of wrinkled unsteady flames  

NASA Astrophysics Data System (ADS)

Local flame displacement speeds were measured along the flame front of laminar unsteady premixed flames wrinkled by laminar toroidal vortices. The displacement speed is argued to be the most important and sensitive parameter that must be simulated correctly in numerical simulation of turbulent flames. An axisymetric flame wrinkle is created in order to measure all components of the normal velocity vector and stretch; particle image velocimetry (PIV) and high-speed shadowgraph cinematography yield the difference between the interface velocity and the reactant gas velocity---the displacement speed. This repeatable flame-vortex interaction problem provides a useful test data to assess direct numerical simulation models and flame stretch theory. Lean and rich methane-air, and lean propane-air flames were investigated to assess stable and unstable preferential diffusion effects on local displacement speeds. The strength of the laminar toroidal vortices was varied from 1.4 to 10 times the unstretched laminar flame burning velocities, S L. Results showed that the local displacement speeds follow the trends predicted by the laminar steady-state theory, but not the magnitudes. Large variations in local displacement speed measurements were found, ranging from --6 to 10 times SL. The negative values occur at the two locations that the steady-state theory predicts low values. Planar laser induced fluorescence of the OH radical was used successfully to locate the flame front boundary in the velocity fields obtained from the PIV images. Microgravity studies at NASA Lewis 2.2 second drop tower showed that when the stabilizing influence of buoyancy is removed, the wrinkling amplitude of the premixed flames caused by toroidal vortices increases by as much as a factor of three. The degree of wrinkling for preferential diffusion unstable flames is larger than those showed by stable ones. Vorticity fields obtained from the PIV images (at one-g) indicate that baroclinic torques due to buoyancy create "flame-generated vorticity" which induces a velocity that suppresses flame wrinkles. Scaling concepts indicate that the ratio of Baroclinic torques to the Rayleigh-Taylor stabilizing force scales inversely with Froude number. In the present experiment, the velocity induced by Baroclinic torques is equal to that induced by the Rayleigh-Taylor forces. Thus, baroclinic torques in this experiment are important but not dominant.

Sinibaldi, Jose Oscar

270

A non-hypersingular boundary integral formulation for displacement gradients in linear elasticity  

Microsoft Academic Search

Summary Based on boundary displacement and traction, a non-hypersingular boundary integral formulation is developed for the displacement gradient. At an arbitrary boundary point where the displacement field at least satisfies a Hölder condition (uk?C1, ? with ?>0), the displacement gradient can be calculated by the Cauchy Principal Value (CPV) integration. The hypersingularity involved in conventional formulation is circumvented by applying

Y. F. Dong; H. C. Gea

1998-01-01

271

Wireless Measurement of Rotation and Displacement Rate  

NASA Technical Reports Server (NTRS)

A magnetic field response sensor is designed to measure displacement or rotation rate without a physical connection to a power source, microprocessor, data acquisition equipment, or electrical circuitry. The sensor works with the magnetic field response recorder, which was described in Magnetic-Field-Response Measurement-Acquisition System, NASA Tech Briefs, Vol. 30, No. 6 (June 2006), page 28. These sensors are wirelessly powered and interrogated, and the measurement acquisition system and sensors are extremely lightweight.The response recorder uses oscillating magnetic fields to power the sensors. Once powered, the sensors respond with their own magnetic field. For displacement/ rotation measurements, the response recorder uses the sensor s response amplitude, which is dependent on the distance from the antenna. The recorder s antenna orientation and position are kept fixed, and the sampling period is constant.

Woodard, Stanley E.; Taylor, Bryant D.

2007-01-01

272

Effects of local toroidal field ripples due to test blanket modules for ITER on radial transport of thermal ions  

NASA Astrophysics Data System (ADS)

The effects of local toroidal field (TF) ripples due to ferromagnetic steels used in test blanket modules (TBMs) in ITER on the radial transport of thermal ions located near the top of the pedestal are investigated using a fully three-dimensional magnetic field orbit following Monte Carlo (F3D-OFMC) code. In the simulation, the three-dimensional motion of 20?000 test particles, distributed near the top of the pedestal (?N = 0.91) with the same Maxwellian velocity distribution as the thermal ions at this location, is traced for 1.9 s. In comparison with the number of lost particles in the case without a TBM, the additional loss with three TBM ports expected in ITER is evaluated to be less than 1% of the test particles. The additional losses increase linearly with the number of TBM ports and with the square of the amplitude of the local TF ripple. The poloidal structure of the TF ripple without ferritic inserts and a case with 18 TBM ports are also compared. It is found that cases having the same ripple amplitude at a certain point can have substantially different additional loss rates if the poloidal ripple structure is not the same. The ripple amplitude near the banana tip seems to be the most important factor in determining the radial diffusion of thermal ions.

Oyama, N.; Urano, H.; Shinohara, K.; Honda, M.; Takizuka, T.; Hayashi, N.; Kamada, Y.; the JT-60 Team

2012-11-01

273

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

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.)

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

2006-02-01

274

Scaling of fault damage zones with displacement and the implications for fault growth processes  

NASA Astrophysics Data System (ADS)

Knowledge of the spatial extent of damage surrounding fault zones is important for understanding crustal fluid flow and also for understanding the physical processes and mechanics by which fault zones develop with slip. There are few data available on the scaling of the fault damage zone with fault displacement, and of those that exist, deriving scaling relationships is hampered by comparing faults that run through different lithologies, have formed at different crustal depths or tectonic regimes (e.g., normal versus strike-slip movement). We describe new data on the microfracture damage zone width from small displacement fault zones within the Atacama fault zone in northern Chile that formed at ˜6 km depth within a dioritic protolith. The microfracture damage zone is shown by an alteration halo surrounding the faults in which the density of the microfractures is much greater than background levels in the undeformed protolith. The data show that damage zone width increases with fault displacement and there appears to be a zero intercept to this relationship, meaning that at zero displacement, there is no microfracture damage zone. This is supported by field observations at fault tips that show a tapering out of fault damage zones. These data, combined with data from the literature, indicate that this same relationship might hold for much larger displacement faults. There is also a distinct asymmetry to the fracture damage. Several processes for the development of the observed scaling are discussed. The widely accepted theory of a process zone predicts that fault damage zone width increases with fault length and thus should always be largest at a propagating fault tip where displacement is lowest. This prediction is opposite to that seen in the current data set, leading to suggestion that other processes, such as damage zone growth with increasing displacement due to geometric irregularities or coseismic damage formation might better explain the spatial extent of damage surrounding even low-displacement faults.

Faulkner, D. R.; Mitchell, T. M.; Jensen, E.; Cembrano, J.

2011-05-01

275

Penn Grade Micellar Displacement Project. Final report  

Microsoft Academic Search

Results of the five year study are presented in this report. The Penn Grade Micellar Displacement Project was a test of a Microemulsion Flooding process on typical post-waterflood Bradford Third Sand Reservoir. The project was located on Pennzoil's Lawry Lease in the heart of the Bradford Field in Northern Pennsylvania. The tertiary oil recovery system was Marathon Oil Company's Maraflood

P. S. Ondrusek; W. T. Paynter

1982-01-01

276

Gage for Measuring Displacements in Rock Samples.  

National Technical Information Service (NTIS)

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...

D. J. Holcomb M. J. McNamee

1985-01-01

277

Displacement Gage for the Rock Mechanics Laboratory.  

National Technical Information Service (NTIS)

A gage for measuring displacements has been developed for use in the rock mechanics laboratory and in the field. The gage consists of a support ring that holds an LVDT (liner variable differential transformer), a mounting screw, and a leaf spring. The gag...

D. J. Holcomb M. J. McNamee

1984-01-01

278

SOFTWARE ENABLED VARIABLE DISPLACEMENT PUMPS  

Microsoft Academic Search

Direct pump control of hydraulic systems is more energy efficient than throttle valve based methods to control hydra ulic systems. This requires variable displacement pumps that are responsive and capable of electronic control. Such Electronic Displacement Controlled (EDC) pumps tend to be significantl y larger, heavier and more expensive than fixed displacement c oun- terparts. In addition, achievable control bandwidths

Perry Y. Li; Cassie Y. Li; Thomas R. Chase

279

DISPLACEMENT SPECTRA FOR SEISMIC DESIGN  

Microsoft Academic Search

Displacement-based seismic design and assessment of structures require the reliable definition of displacement spectra for a wide range of periods and damping levels. The displacement spectra derived from acceleration spectra in existing seismic codes do not provide a suitable answer and there are no existing frequency-dependent attenuation relationships derived specifically for this purpose. Using a carefully processed dataset of European

JULIAN J. BOMMER; AMR S. ELNASHAI

1999-01-01

280

Displacement Data Assimilation  

NASA Astrophysics Data System (ADS)

Geometric corrections are blended with nonlinear/non-Gaussian estimation methods to produced improved data assimilation outcomes on problems where features are critical. Problems of this sort are the estimation of hurricane tracks, tracking jet meandering, front propagation, among many others. The geometric correction is made possible by a data preserving map. It makes corrections on phase, primarily, as well as in the amplitude. The displacement assimilation is embedded in the analysis stage of a nonlinear/non-Gaussian Bayesian data assimilation scheme, such as the path integral method. In addition to showing how the method improves upon the results, as compared to more standard methodologies.

Restrepo, J. M.; Rosenthal, S.; Venkataramani, S.

2013-05-01

281

Subsidence due to geothermal fluid withdrawal  

SciTech Connect

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.

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

1982-10-01

282

SUBSIDENCE DUE TO GEOTHERMAL FLUID WITHDRAWAL  

SciTech Connect

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.

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

1982-10-01

283

An ion displacement membrame model.  

PubMed

The usual assumption in treating the diffusion of ions in an electric field has been that the movement of each ion is independent of the movement of the others. The resulting equation for diffusion by a succession of spontaneous jumps has been well stated by Parlin and Eyring. This paper will consider one simple case in which a different assumption is reasonable. Diffusion of monovalent positive ions is considered as a series of jumps from one fixed negative site to another. The sites are assumed to be full (electrical neutrality). Interaction occurs by the displacement of one ion by another. An ion leaves a site if and only if another ion, not necessarily of the same species, attempts to occupy the same site. Flux ratios and net fluxes are given as functions of the electrical potential, concentration ratios, and number of sites encountered in crossing the membrane. Quantitative comparisons with observations of Hodgkin and Keynes are presented. PMID:6048876

Hladky, S B; Harris, J D

1967-09-01

284

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)

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.

Hill, Charles S.; Oliveras, Ovidio M.

2011-01-01

285

Adapting to variable prismatic displacement  

NASA Technical Reports Server (NTRS)

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.

Welch, Robert B.; Cohen, Malcolm M.

1989-01-01

286

Gas miscible displacement enhanced oil recovery: Technology status report  

SciTech Connect

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.

Not Available

1986-10-01

287

Displacement measurement of a shaker in an accelerometer calibration system  

Microsoft Academic Search

The vibration displacement of a shaker in an accelerometer calibration system is detected by a Michelson type of a phase quadrature laser interferometer. The interferometric signals are stored in a digital storage scope and transferred to a computer for displacement calculation. Due to the high resolution, fast acquisition speed, and large memory capacity of the scope, this system demonstrates a

Gwo-Sheng Peng; Chien-Ming Wu; Yeu-Jong Huang

1996-01-01

288

Experimental design rules for implementing biconically tapered single mode optical fibre displacement sensors  

NASA Astrophysics Data System (ADS)

Tapered optical fibers are used to design couplers, wavelength division multiplexers, near field scanning optical microscopy, just to mention a few. Moreover, and due to its strong transmission dependence to external medium the tapered fiber may also be used to sense distinct parameters such as temperature, humidity, PH, etc. In this work bending effects in tapers are exploited to achieved displacement sensors and to present design rules for implementing these sensors according to the desired both range and sensitivity.

Arregui, Francisco J.; Matias, Ignacio R.; Bariain, C.; Lopez-Amo, Manuel

1998-06-01

289

Dust mobilization due to density currents in the Atlas region: Observations from the Saharan Mineral Dust Experiment 2006 field campaign  

NASA Astrophysics Data System (ADS)

Evaporation of precipitation is a ubiquitous feature of dry and hot desert environments. The resulting cooling often generates density currents with strong turbulent winds along their leading edges, which can mobilize large amounts of dust. Mountains support this process by triggering convection, by downslope acceleration of the cool air, and by fostering the accumulation of fine-grained sediments along their foothills through the action of water. For the Sahara, the world's largest dust source, this mechanism has been little studied because of the lack of sufficiently high resolution observational data. The present study demonstrates the frequent occurrence of density currents along the Sahara side of the Atlas Mountain chain in southern Morocco using the unique data set collected during the Saharan Mineral Dust Experiment (SAMUM) field campaign in May/June 2006. The density currents are related to convection over the mountains in the afternoon hours and have lifetimes on the order of 10 h. The passage of the sharp leading edge that sometimes reaches several hundred kilometers in length is usually associated with a marked increase in dew point and wind speed, a change in wind direction, and a decrease in temperature and visibility due to suspended dust. It is conceivable that this mechanism is relevant for other mountainous regions in northern Africa during the warm season. This would imply that simulations of the dust cycle with numerical models need a reliable representation of moist convective processes in order to generate realistic dust emissions from the Sahara.

Knippertz, P.; Deutscher, C.; Kandler, K.; Müller, T.; Schulz, O.; Schütz, L.

2007-11-01

290

Impaired reading not due to visual field loss in a patient with a right-hemipsheric lesion.  

PubMed

We describe a right-handed patient (M.B.), who developed left hemianopsia and a severe reading impairment after right occipital-parietal hemorrhage. The pattern of his reading deficit was very similar to that of pure alexia (alexia-without-agraphia): extremely slow reading times with frequent grapheme substitutions and omissions. A test of letter reading while controlling for saccadic eye movements and hemifield of presentation ruled out hemianoptic alexia. Although there have already been reports of reading impairments in right handers following right- hemispheric lesions, ours is, to the best of our knowledge, the first where visual field loss can be definitely excluded as the main cause. Based on a standard neuropsychological assessment and on additional behavioral tests, we argue that M.B.'s difficulties are unlikely to be due to right-hemisphere dominance for language. After considering several candidate explanations, we suggest that M.B.'s symptoms may be related to an impairment in attentional processes related to reading. PMID:23984952

Basagni, Benedetta; Patané, Ivan; Ferrari, Vera; Bruno, Nicola

2014-10-01

291

Spatially dispersive displacement sensor utilizing a semiconductor gain chip.  

PubMed

We demonstrate the development of a simply equipped displacement sensor utilizing spatially dispersive confocal technology. It feeds the amplified spontaneous emission (ASE) of a laser diode to a wavelength-selective feedback structure that corresponds to the position of a measured surface. The displacement sensor has a detecting range of 4 microm and precision of less than 2 nm, as proven by the analysis of the spectral shifts of the multipassed amplified output ASE. As compared with traditional sensors, the displacement sensor presented in our study requires fewer components and has as high precision as complex systems and a higher measurement rate due to the simpler strategy of displacement determination. PMID:17279154

Horng, Ji-Bin; Chou, Wei-Yang; Tsau, Seth; Liao, Jay; Hsu, Shih-Ming; Chen, Chih-Li; Chang, Kun-Chieh; Su, Yan-Kuin

2007-02-10

292

Variable displacement blower  

DOEpatents

A blower having a stationary casing for rotatably supporting a rotor assembly having a series of open ended chambers arranged to close against the surrounding walls of the casing. Pistons are slidably mounted within each chamber with the center of rotation of the pistons being offset in regard to the center of rotation of the rotor assembly whereby the pistons reciprocate in the chambers as the rotor assembly turns. As inlet port communicates with the rotor assembly to deliver a working substance into the chamber as the pistons approach a top dead center position in the chamber while an outlet port also communicates with the rotor to exhaust the working substance as the pistons approach a bottom dead center position. The displacement of the blower is varied by adjusting the amount of eccentricity between the center of rotation of the pistons and the center of rotation of the rotor assembly.

Bookout, Charles C. (Niskayuna, NY) [Niskayuna, NY; Stotts, Robert E. (Clifton Park, NY) [Clifton Park, NY; Waring, Douglass R. (Ballston Spa, NY) [Ballston Spa, NY; Folsom, Lawrence R. (Ohain, BE) [Ohain, BE

1986-01-01

293

Displacement parameter inversion for a novel electromagnetic underground displacement sensor.  

PubMed

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

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

2014-01-01

294

Displacement Parameter Inversion for a Novel Electromagnetic Underground Displacement Sensor  

PubMed Central

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.

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

2014-01-01

295

Mean force on a finite-sized spherical particle due to an acoustic field in a viscous compressible medium  

NASA Astrophysics Data System (ADS)

An analytical expression to evaluate the second-order mean force (acoustic radiation force) on a finite-sized, rigid, spherical particle due to an acoustic wave is presented. The medium in which the particle is situated is taken to be both viscous and compressible. A far-field derivation approach has been used in determining the force, which is a function of the particle size, acoustic wavelength, and viscous boundary-layer thickness. It is assumed that the viscous length scale is negligibly small compared to the acoustic wavelength. The force expression presented here (i) reduces to the correct inviscid behavior (for both small- and finite-sized particles) and (ii) is identical to recent viscous results [M. Settnes and H. Bruus, Phys. Rev. E 85, 016327 (2012), 10.1103/PhysRevE.85.016327] for small-sized particles. Further, the computed force qualitatively matches the computational fluid dynamics (finite-element) results [D. Foresti, M. Nabavi, and D. Poulikakos, J. Fluid Mech. 709, 581 (2012), 10.1017/jfm.2012.350] for finite-sized particles. Additionally, the mean force is interpreted in terms of a multipole expansion. Subsequently, considering the fact that the force expansion is an infinite series, the number of terms that are required or adequate to capture the force to a specified accuracy is also provided as a function of the particle size to acoustic wavelength ratio. The dependence of the force on particle density, kinematic viscosity, and bulk viscosity of the fluid is also investigated. Here, both traveling and standing waves are considered.

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

2014-05-01

296

Gas Miscible Displacement Enhanced Oil Recovery. Technology Status Report.  

National Technical Information Service (NTIS)

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 densit...

1985-01-01

297

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

298

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

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.

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

2012-01-01

299

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

SciTech Connect

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.

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

300

Regenerative rotary displacer Stirling engine  

Microsoft Academic Search

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

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

1996-01-01

301

Feature-based Displacement Mapping  

Microsoft Academic Search

Displacement mapping was originally created as a rendering tool to provide small-scale modulation of an underlying smooth surface. However, it has now emerged as a sculpting tool, to the extent that complex geometry can effectively be added to a scene at rendering time. The attendant complexity of displacement maps is placing increased demands on rendering systems, from quality, perfor- mance,

Xiaohuan Corina Wang; Jérôme Maillot; Eugene Fiume; Victor Ng-thow-hing; Andrew Woo; Sanjay Bakshi

2000-01-01

302

Energy loss in YBCO-123 coated conductor due to AC\\/DC transport current and AC external perpendicular magnetic field  

Microsoft Academic Search

In the paper we present experimental results of power losses measurements in a YBCO-123 coated conductor carrying a DC (or AC) transport current when subjected simultaneously to an external AC magnetic field. Two kinds of measurements were carried out; the first was AC transport current losses as a function of the current amplitude and the AC external magnetic field (“AC–AC”

M. Ciszek; O. Tsukamoto; J. Ogawa; M. Shiokawa

2003-01-01

303

Riesgo laboral y residencial por exposición a campos electromagnéticos Labour and residential risk due to electromagnetic fields exposition  

Microsoft Academic Search

In the recent years, there has been an increment of ex- position to electromagnetic fields (EMF), specially residen- tial and labour exposure. Some scientist allege that exposure to electric and mag- netic fields generated mainly by electric power delivery sys- tems is responsible for health problems as reproductive dys- function, birth defects, neurological disorders and cancer. This article provides a

M. Física; Pastor Vega

304

Transverse angular momentum and transverse barycenter shift of a focused light field due to nonuniform input angular momentum.  

PubMed

We calculate the spin, intrinsic and extrinsic orbital angular momenta, as well as the barycenter of the focal field after a high-NA lens and find that, when the input beam is with nonuniform angular momentum (AM), the focal field carries both longitudinal and transverse parts of AM and the barycenter of the field has a transverse shift owing to the spin and orbital Hall effect of light. When one half of the input beam possesses spin and orbital AM, ? and l, and the other half with -? and -l, a pure transverse AM is generated in the focal field, accompanying a shift of the field barycenter in the transverse plane that depends on ? and l. PMID:24690781

Zhu, Wenguo; She, Weilong

2014-03-15

305

Is fibular fracture displacement consistent with tibiotalar displacement?  

PubMed

We believed open reduction with internal fixation is required for supination-external rotation ankle fractures located at the level of the distal tibiofibular syndesmosis (Lauge-Hanssen SER II and Weber B) with 2 mm or more fibular fracture displacement. The rationale for surgery for these ankle fractures is based on the notion of elevated intraarticular contact pressures with lateral displacement. To diagnose these injuries, we presumed that in patients with a fibular fracture with at least 2 mm fracture displacement, the lateral malleolus and talus have moved at least 2 mm in a lateral direction without medial displacement of the proximal fibula. We reviewed 55 adult patients treated operatively for a supination-external rotation II ankle fracture (2 mm or more fibular fracture displacement) between 1990 and 1998. On standard radiographs, distance from the tibia to the proximal fibula, distance from the tibia to the distal fibula, and displacement at the level of the fibular fracture were measured. These distances were compared preoperatively and postoperatively. We concluded tibiotalar displacement cannot be reliably assessed at the level of the fracture. Based on this and other studies, we believe there is little evidence to perform open reduction and internal fixation of supination-external rotation II ankle fractures. Level of Evidence: Level IV, case series. See Guidelines for Authors for a complete description of levels of evidence. PMID:19582527

van den Bekerom, Michel P J; van Dijk, C Niek

2010-04-01

306

Far field intensity distributions due to spatial self phase modulation of a Gaussian beam by a thin nonlocal nonlinear media.  

PubMed

In this work we present a simple model that can be used to calculate the far field intensity distributions when a Gaussian beam cross a thin sample of nonlinear media but the response can be nonlocal. PMID:20941108

Ramirez, E V Garcia; Carrasco, M L Arroyo; Otero, M M Mendez; Cerda, S Chavez; Castillo, M D Iturbe

2010-10-11

307

Electromagnetic Fields and Relative Heating Patterns Due to a Rectangular Aperture Source in Direct Contact with Bilayered Biological Tissue  

Microsoft Academic Search

Expressions are derived and evaluated for the electro-magnetic fields and associated relative heating patterns in two-Iayered biological tissue media exposed to a direct-contact rectangular aperture source. The source consists of a linearly polarized electric field distribution specified in the plane of the aperture. The results may be used for many biomedical applications ranging from the design of diathermy applicators to

A. W. Guy

1968-01-01

308

Evaluation of preprocessing steps to compensate for magnetic field distortions due to body movements in BOLD fMRI  

Microsoft Academic Search

Blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is currently the dominant technique for non-invasive investigation of brain functions. One of the challenges with BOLD fMRI, particularly at high fields, is compensation for the effects of spatiotemporally varying magnetic field inhomogeneities (?B0) caused by normal subject respiration and, in some studies, movement of the subject during the scan to

Robert L. Barry; Joy M. Williams; L. Martyn Klassen; Jason P. Gallivan; Jody C. Culham; Ravi S. Menon

2010-01-01

309

Calculation of stochastic broadening in real space due to noise and field errors in the DIII-D tokamak  

Microsoft Academic Search

The equilibrium EFIT data for the DIII-D shot 115467 at 3000 ms is used to construct the equilibrium generating function for magnetic field line trajectories in the DIII-D tokamak in natural canonical coordinates. A canonical transformation is used to construct an area-preserving map for field line trajectories in the natural canonical coordinates in the DIII-D. Maps in natural canonical coordinates

Lisa Brodsky; Alkesh Punjabi; Halima Ali

2008-01-01

310

Development and Displacement in India: Reforming the Economy towards Sustainability  

NASA Astrophysics Data System (ADS)

Displacement of human populations from the natural habitats results in a host of socio-economic impacts. This study will focus on mainly farmers and tribal communities in India and how the modernisation process has affected these communities especially since the adoption of neoliberal economic reforms. For the rural people the displacement is a traumatic both in terms livelihoods and cultural point of view. The paper will analyse the issues of displacement of the villages that have been relatively isolated from the outside world. The development induced displacement becomes important due to its impact on the rural communities through land alienation in the form of protests by the affected communities. I find that not even a single study shows the socio-economic and environmental effects of these policies on the rural poor. Analysis of the reasons for these changes point in many directions. Displacement, the loss of traditional livelihoods of the rural communities and environmental destruction are the most prominent among them.

Siddiqui, Kalim

2012-05-01

311

Borehole optical lateral displacement sensor  

DOEpatents

There is provided by this invention an optical displacement sensor that utilizes a reflective target connected to a surface to be monitored to reflect light from a light source such that the reflected light is received by a photoelectric transducer. The electric signal from the photoelectric transducer is then imputed into electronic circuitry to generate an electronic image of the target. The target`s image is monitored to determine the quantity and direction of any lateral displacement in the target`s image which represents lateral displacement in the surface being monitored. 4 figs.

Lewis, R.E.

1998-10-20

312

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

Microsoft Academic Search

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.

Isidore K Kouadio; Taro Kamigaki; Hitoshi Oshitani

2010-01-01

313

The Displaced vs. the Disadvantaged: A Necessary Dichotomy? Occasional Paper 1994-2.  

ERIC Educational Resources Information Center

The current displaced worker initiative towers over the 30-year effort to bring the economically disadvantaged into the mainstream of the labor market. The Congressional Budget Office defines displacement as all workers 18 years of age and older who lose full-time employment due to slack work, job abolition, or plant closure. Major displaced

Levitan, Sar A.; Mangum, Stephen L.

314

Eddy-Current Displacement Transducer With Extended Linear Range and Automatic Tuning  

Microsoft Academic Search

Design details and measurement results of the eddy-current displacement transducer with extended linear range and automatic tuning are presented. The transducer is based on a resonant impedance inversion method of transfer curve linearization where the displacement probe circuit is kept in resonance by the resonance control loop. The transducer exhibits an extended linear range due to the compensation of displacement

Darko Vyroubal

2009-01-01

315

Measuring frequency changes due to microwave power variations as a function of C-field setting in a rubidium frequency standard  

NASA Technical Reports Server (NTRS)

It has been shown in previous studies that in some cesium frequency standards there exist certain C-field settings that minimize frequency changes that are due to variations in the microwave power. In order to determine whether similar results could be obtained with rubidium (Rb) frequency standards (clocks), we performed a similar study, using a completely automated measurement system, on a commercial Rb standard. From our measurements we found that changing the microwave power to the filter cell resulted in significant changes in frequency, and that the magnitude of these frequency changes at low C-field levels went to zero and decreased as the C-field was increased.

Sarosy, E. B.; Johnson, Walter A.; Karuza, Sarunas K.; Voit, Frank J.

1992-01-01

316

Magnetic field response of NaCl:Eu crystal plasticity due to spin-dependent Eu2+ aggregation  

NASA Astrophysics Data System (ADS)

Magnetic field impulse (7 T amplitude 10 ms duration) was found to affect microhardness of NaCl:Eu crystals at room temperature. Dimers (pairs of Eu2+ paramagnetic ions) were shown to be responsible for the crystal softening induced by magnetic field. Theoretical treatment of the magnetoplastic effect based on the spin dependence of processes resulting in transformation of the dimers in crystals is developed and applied to the description of the long-term magnetic memory. Activation energies of the dimer formation, E1=0.23±0.04eV and decomposition, E2=0.33±0.06eV were extracted from thermoactivation analysis of magnetic field controlled Eu2+ aggregation in 77-473 K temperature range.

Morgunov, R. B.; Buchachenko, A. L.

2010-07-01

317

Testing the Validity of the Neoclassical Toroidal Viscosity Model of Torque due to 3D Non-Resonant Magnetic Fields  

NASA Astrophysics Data System (ADS)

Understanding the torque applied by resonant and non-resonant magnetic perturbations and its effect on rotation is essential to predict confinement and stability in burning plasmas. Non-axisymmetric 3D fields produced in the DIII-D tokamak apply a torque to the plasma, which can be evaluated through its effect on the plasma rotation. One explanation for this torque is Neoclassical Toroidal Viscosity (NTV) acting through non-resonant field components [1]. We have developed a software framework in which magnetic perturbations calculated by the state of the art two fluid MHD code M3D-C1 can be used in NTV calculations. For discharges with applied external magnetic fields in DIII-D, the experimentally determined torques will be analyzed and compared with NTV models.[4pt] [1] J.D. Callen, Nucl. Fusion 51, 094026 (2011).

McCubbin, A. J.; Smith, S. P.; Ferraro, N. M.; Callen, J. D.; Meneghini, O.

2012-10-01

318

Asymmetric photoelectron momentum distributions due to quantum interference in strong-field ionization by a few-cycle pulse  

NASA Astrophysics Data System (ADS)

We calculate the left-right asymmetry of the photoelectron momentum distributions generated in a hydrogen atom exposed to an intense few-cycle laser pulse as a function of both the carrier-envelope phase and the laser intensity. We present results of the numerical solution of the three-dimensional time-dependent Schrödinger equation, semiclassical simulations accounting for both laser and Coulomb fields, and the strong-field approximation. We predict pronounced oscillations of the asymmetry parameter as a function of the intensity for a particular range of the carrier-envelope phase. In order to reveal the mechanism underlying these oscillations, we investigate in detail the electron momentum distributions in the one-dimensional case. We show that quantum interference among a large set of both bound and continuum field-free states is responsible for the oscillatory behavior of the left-right asymmetry.

Shvetsov-Shilovski, N. I.; Räsänen, E.; Paulus, G. G.; Madsen, L. B.

2014-04-01

319

Heat and mass transfer in gases due to pressure and temperature gradients in a laser radiation field  

NASA Astrophysics Data System (ADS)

Heat and mass transfer in a one-component gas through a capillary in the field of resonant laser radiation in the presence of pressure and temperature gradients are considered. On the basis of the Boltzmann type kinetic equations in the linear approximation the expression for entropy production is obtained. Kinetic coefficients satisfy the Onsager reciprocity relations at all Knudsen numbers and for any nature of the interaction of gas atoms with the surface of the capillary. The pressure and temperature gradients established in the insulated system in a laser field are defined in a nearly free molecular regime.

Chermyaninov, I. V.; Chernyak, V. G.

2012-11-01

320

Experimental Validation of Displacement Underestimation in ARFI Ultrasound  

PubMed Central

Acoustic radiation force impulse (ARFI) imaging is an elastography technique that uses ultrasonic pulses to both displace and track tissue motion. Previous modeling studies have shown that ARFI displacements are susceptible to underestimation due to lateral and elevational shearing that occurs within the tracking resolution cell. In this study, optical tracking was utilized to experimentally measure the displacement underestimation achieved by acoustic tracking using a clinical ultrasound system. Three optically translucent phantoms of varying stiffness were created, embedded with sub-wavelength diameter microspheres, and ARFI excitation pulses with F/1.5 or F/3 lateral focal configurations were transmitted from a standard linear array to induce phantom motion. Displacements were tracked using confocal optical and acoustic methods. As predicted by earlier FEM studies, significant acoustic displacement underestimation was observed for both excitation focal configurations; the maximum underestimation error was 35% of the optically measured displacement for the F/1.5 excitation pulse in the softest phantom. Using higher F/#, less tightly focused beams in the lateral dimension improved accuracy of displacements by approximately 10 percentage points. This work experimentally demonstrates limitations of ARFI implemented on a clinical scanner using a standard linear array and sets up a framework for future displacement tracking validation studies.

Czernuszewicz, Tomasz J.; Streeter, Jason E.; Dayton, Paul A.; Gallippi, Caterina M.

2014-01-01

321

The Dispersion of the Geomagnetic Field Due to Secular Variation and Its Determination for Remote Times from Paleomagnetic Data  

Microsoft Academic Search

In studies of the paleosecular variation the situation often arises that, although a number of spot readings of the palcogeomagnetic field have been deduced from the fossil magnetization of a rock formation, their stratigraphic sequence is unknown. Hence, in this paper, methods are discussed of deducing the amount of dispersion produced by the palcosecu- lar variation in the magnetization of

K. M. Creer

1962-01-01

322

Enhanced dynamo contribution to the resistivity of a reversed field pinch due to non-uniform effective charge profiles  

Microsoft Academic Search

The effect of a non-uniform effective ion charge distribution on the dynamo contribution to the plasma resisitivity of a reversed field pinch is studied, based on a stationary energy or helicity balance. The radial distribution of the impurity is obtained from the ETA-BETA II line emission profiles. It is found that the main impurity ions are concentrated in the outer

L. Gabellieri; M. Giubbilei; S. Martini; S. Ortolani; M. E. Puiatti; P. Scarin

1987-01-01

323

Height and latitude structure of electric fields and currents due to local east-west winds in the equatorial electrojet  

Microsoft Academic Search

Using the equivalent electrical circuit method for the theoretical treatment of the local wind effects on the equatorial electrojet, the height structures of electric fields and currents that are generated by heightvarying east-west winds in the electrojet region have been calculated for theoretical model wind sturctures and for a variety of experimentally observed wind structures. The results bring out clearly

C. A. Reddy; C. V. Devasia

1981-01-01

324

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

NASA Astrophysics Data System (ADS)

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.

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

2007-03-01

325

Stochastic Electron Dynamics due to Drift Waves in a Sheared Magnetic Field and Other Drift Motion Problems  

Microsoft Academic Search

Electron motion in a single electrostatic wave in a sheared magnetic field is shown to become stochastic in the presence of a second wave at an amplitude well below that obtained from the overlapping pendulum resonance approximation. The enhanced stochasticity occurs for low parallel velocity electrons for which the parallel trapping motion from eE(,(PARLL))\\/m interacts strongly with the E x

James Alexander Robertson

1986-01-01

326

Coexistence of single- and multi-photon processes due to longitudinal couplings between superconducting flux qubits and external fields  

NASA Astrophysics Data System (ADS)

In contrast to natural atoms, the potential energies for superconducting flux qubit (SFQ) circuits can be artificially controlled. When the inversion symmetry of the potential energy is broken, we find that multi-photon processes can coexist in multi-level SFQ circuits. Moreover, there are not only transverse but also longitudinal couplings between the external magnetic fields and the SFQs when the inversion symmetry of potential energy is broken. Longitudinal coupling would induce some new phenomena in the SFQs. Here we will show how longitudinal coupling can result in the coexistence of multi-photon processes in a two-level system formed by an SFQ circuit. We also show that the SFQs can become transparent to the transverse coupling fields when the longitudinal coupling fields satisfy certain conditions. We further show that the quantum Zeno effect can also be induced by longitudinal coupling in the SFQs. Finally, we clarify why longitudinal coupling can induce the coexistence and disappearance of single- and two-photon processes for a driven SFQ, which is coupled to a single-mode quantized field.

Liu, Yu-xi; Yang, Cheng-Xi; Sun, Hui-Chen; Wang, Xiang-Bin

2014-01-01

327

Using CIDS with Displaced Workers.  

ERIC Educational Resources Information Center

Discusses the use of the Virginia Vital Information for Education and Work program at J. Sargeant Reynolds Community College, with particular emphasis on career planning and placement services and outreach efforts. Highlights special displaced workers programs with industry. (DMM)

Amburgey, Lillian; Sanborn, Carleton H.

1987-01-01

328

Polyimidazoles Via Aromatic Nucleophilic Displacement  

NASA Technical Reports Server (NTRS)

Experiments show variety of polyimidazoles prepared by aromatic nucleophilic displacement, from reactions of bisphenol imidazoles with activated difluoro compounds. Polyimidazoles have good mechanical properties making them suitable for use as films, moldings, and adhesives.

Connell, John W.; Hergenrother, Paul M.

1990-01-01

329

Wirelessly Interrogated Position or Displacement Sensors  

NASA Technical Reports Server (NTRS)

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.

Woodard, Stanley E.; Taylor, Bryant D.

2007-01-01

330

A 3D electrokinetic flow structure of solution displacement in microchannels for on-chip sample preparation applications  

NASA Astrophysics Data System (ADS)

Electroosmotic flow with solution displacement in microchannels is often encountered in many lab-on-a-chip devices where washing procedures are designed using one solution to displace another different solution. In order to investigate the detailed flow structures for a displacement process between two different electrolyte solutions, a three-dimensional numerical model is developed in this paper. KCl solution and LaCl3 solution are used as sample solutions. A 2 mm long straight microchannel with a rectangular cross-sectional area (height 100 µm and width 200 µm) was employed in this study. The governing equations of the applied electrical field, flow field and concentration field are numerically solved based on a finite-control-volume scheme. The fluid flow coupled equations are solved using the semi-implicit method for pressure-linked equation (SIMPLE) algorithm. The observed electrokinetic flow structures include back flow in the center of the channel and distortion of the plug-like electroosmotic velocity profile, which are investigated in detail. It is found that distortion in the flow field is due to the induced pressure gradient, which results from the nonuniformity of electroosmotic mobilities and electrical conductivities of the two solutions. Finally, the displacement between a pair of different solutions, distilled ultra-filtered (DIUF) water and LaCl3 solution, is briefly studied.

Shao, Zhanjie; Ren, Carolyn L.; Schneider, Gerry E.

2006-03-01

331

Clavicle fracture with intrathoracic displacement.  

PubMed

Clavicle fractures are common, and most are isolated injuries. Injury to the nearby subclavian vessels and brachial plexus have classically been described as potential complications of clavicle fractures. However, in the setting of a substantially displaced clavicle fracture, concomitant thoracic trauma is relatively frequent. Injury to the thorax can be difficult to identify on physical examination, and advanced imaging modalities may be required for diagnosis. The evaluation, workup, and management of a patient with intrathoracic displacement of a clavicle fracture are described. Despite the significant fracture displacement and associated pneumothorax, the injury severity was not clinically obvious. Imaging, including a screening chest radiograph and subsequent axial computed tomography, played an important role in diagnosis and management. The patient underwent successful open reduction and plate fixation. A thoracostomy tube was not required at any point during the hospitalization. The patient recovered uneventfully and returned to full work duty by 3 months postoperatively. Including the current report, only 3 cases of intrathoracic displacement of the clavicle have been published in the English literature. All involved fractures of the middle third of the clavicle. The severity of displacement was not obvious in any patient, and diagnosis was dependent on additional imaging. Given the frequency of associated chest trauma and limitations of physical examination, chest radiography should be considered in the evaluation of patients with substantially displaced clavicle fractures. PMID:23937761

Lohse, Grant R; Lee, Donald H

2013-08-01

332

Magnetic phase diagram of CeAu2Ge2: High magnetic anisotropy due to crystal electric field  

NASA Astrophysics Data System (ADS)

CeAu2Ge2 single crystals (with tetragonal ThCr2Si2 structure) have been grown in Au-Ge flux (AGF) as well as in Sn flux (SF). X-ray powder diffraction and EDX measurements indicate that in the latter case, Sn atoms from the flux are incorporated in the samples, leading to a decrease of the lattice constants by ?0.3% compared to AGF samples. For both types of samples, a strong anisotropy of the magnetization M for the magnetic field B parallel and perpendicular to the c direction is observed with M||/M??6--7 in low fields just above 10 K. This anisotropy is preserved to high fields and temperatures and can be quantitatively explained by crystal electric field effects. Antiferromagnetic ordering sets in around 10 K as previously found for polycrystalline samples. From the magnetization data of our single crystals we obtain the phase diagrams for the AGF and SF samples. The magnetic properties depend strongly on the flux employed. While the AGF samples exhibit a complex behavior indicative of several magnetic transitions, the SF samples adopt a simpler antiferromagnetic structure with a single spin-flop transition. This effect of a more ordered state induced by disorder in form of Sn impurities is qualitatively explained within the anisotropic next-nearest neighbor Ising (ANNNI) model, which assumes ferromagnetic and antiferromagnetic interactions in agreement with the magnetic structure previously inferred from neutron-scattering experiments on polycrystalline CeAu2Ge2 by Loidl [Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.46.9341 46, 9341 (1992)].

Fritsch, V.; Pfundstein, P.; Schweiss, P.; Kampert, E.; Pilawa, B.; v. Löhneysen, H.

2011-09-01

333

Verifying the Field of View Afforded to the Pilot due to Cockpit Design, Stature, and Aerodrome Design Parameters  

Microsoft Academic Search

\\u000a This paper examined the contribution of various design parameters towards the pilot’s forward field of view (FFOV). This study\\u000a was based upon the SQ006 crash at Chiang Kai Shek Airport, Taipei, Taiwan on 31 Oct 2000. A 3-dimensional scale model was\\u000a created to simulate certain design features experienced on the night of the accident. A simulation of the Boeing 747-400

Eugene Aik Min Khoo; Kee Yong Lim

2004-01-01

334

Urban exposure to ELF magnetic field due to high-, medium- and low-voltage electricity supply networks.  

PubMed

The regional environment protection agency (ARPA) of the Aosta Valley region in north Italy performed a survey of magnetic field triggered by the power supply network in high, medium and low voltages on the entire area of Aosta town. The electrical distribution system for houses was not however taken into account. The aim of the survey was to evaluate the global population exposure and not simply the assessment of the legal exposure limit compliance. PMID:19843546

Bottura, V; Cappio Borlino, M; Carta, N; Cerise, L; Imperial, E

2009-12-01

335

Propagation Effects Due to Finitely Conducting Ground on Lightning-Generated Magnetic Fields Evaluated Using Sommerfeld's Integrals  

Microsoft Academic Search

The effects of finitely conducting ground on the signature of lightning-generated magnetic fields at ground level were evaluated by numerical solution of Sommerfeld's integrals. Results are presented for distances between 10 m to 1 km from the lightning channel and for ground conductivities in the range of 0.01 and 0.0001 S\\/m. The results obtained from the exact theory are compared

Vernon Cooray

2009-01-01

336

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

337

MAXIMUM SEISMIC DISPLACEMENT ESTIMATION USING ACCELERATION RECORD FOR INEASTIC RESPONSE  

NASA Astrophysics Data System (ADS)

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.

Abe, Masato; Fujino, Yozo

338

Ion heating by kinetic cross-field streaming instability due to reflected ions at a quasiperpendicular shock  

NASA Technical Reports Server (NTRS)

The present paper shows that the reflected ion at a supercritical quasi-perpendicular shock wave can excite a purely growing mode propagating parallel to the ambient magnetic field. To discuss the ion heating by such an unstable mode, the self-consistent quasi-linear kinetic equation is solved with the assumption that the present purely growing mode is the dominant unstable mode in the system. In the quasi-linear analysis of the instability, two particular cases are considered: the case of low initial ion beta and that of a high initial ion beta.

Yoon, Peter H.; Wu, C. S.; Mandt, M. E.

1992-01-01

339

Comparing Teaching Approaches About Maxwell's Displacement Current  

NASA Astrophysics Data System (ADS)

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.

Karam, Ricardo; Coimbra, Debora; Pietrocola, Maurício

2013-07-01

340

Closed form solutions for thermal stress field due to non-equilibrium heating during laser short-pulse irradiation  

NASA Astrophysics Data System (ADS)

Non-equilibrium heating in the lattice sub-system results in high temperature gradients in the surface region. This in turn causes thermal stress waves propagating into the substrate material. In the present study, a closed form solution for thermal stress developed in the substrate material due to volumetric pulse heating is presented. The stress free and stress continuity boundary conditions at the surface are incorporated in the closed form solutions. It is found that thermal stress wave is tensile in the surface region and it becomes compressive at some depth below the surface for stress free condition at the surface; however, it remains compressive for the condition of stress continuity at the surface.

Yilbas, B. S.; Al-Dweik, A. Y.

2012-06-01

341

Three dimensional temperature field in a conducting sphere due to an arbitrarily located split ring heating source  

NASA Astrophysics Data System (ADS)

Thermal control of spacecrafts plays an important role in space missions. In the design stage the preliminary thermal analysis of the spacecraft requires an estimate of the conductive thermal resistance between the various spacecraft components. With this in mind, the fully three dimensional problem of determining the thermal field in a conducting sphere with an asymmetric split ring current carrying heating source is resolved in an analytical or almost analytical form, implying either a closed form solution or utmost expressions involving a simple numerical integration. This has immediate application for evaluation of thermal resistance in spacecrafts. Green's function integral techniques are used. Comparisons are made with series solutions and also with purely numerical solutions to contrast the simplicity and highlight the elegance of the present method. Parametric studies reveal expected behavior.

Venkataraman, Nellore S.; Vélez García, Ana M.; Venkataraman, Vikram; Diestra-Cruz, Heberth

2014-02-01

342

Asymmetric toroidal flux generation due to phase locking of internally resonant tearing modes in the RELAX reversed-field pinch  

NASA Astrophysics Data System (ADS)

Self-generation and sustainment of toroidal flux via a dynamo is one of the unique characteristics of the reversed-field pinch (RFP) configuration. In a small aspect ratio RFP machine RELAX, it has been observed that a sudden dynamo usually occurs at a localized toroidal location. This localized dynamo evolves in time, causing a toroidally asymmetric flux distribution. The degree of asymmetry depends on the location and propagation of the localized dynamo. It has been observed that the position where the localized dynamo occurs coincides with the position where the phases of the internally resonant tearing modes align. The phase alignment plays an important role in triggering a localized dynamo activity and in the formation of asymmetric toroidal flux distribution especially in deep-reversal plasmas in RELAX.

Ikezoe, R.; Masamune, S.; Oki, K.; Sanpei, A.; Himura, H.; Onchi, T.; Hirose, A.

2013-01-01

343

Integrating a MRI scanner with a 6 MV radiotherapy accelerator: impact of the surface orientation on the entrance and exit dose due to the transverse magnetic field.  

PubMed

At the UMC Utrecht, in collaboration with Elekta and Philips Research Hamburg, we are developing a radiotherapy accelerator with integrated MRI functionality. The radiation dose will be delivered in the presence of a lateral 1.5 T field. Although the photon beam is not affected by the magnetic field, the actual dose deposition is done by a cascade of secondary electrons and these electrons are affected by the Lorentz force. The magnetic field causes a reduced build-up distance: because the trajectory of the electrons between collisions is curved, the entrance depth in tissue decreases. Also, at tissue-air interfaces an increased dose occurs due to the so-called electron return effect (ERE): electrons leaving tissue will describe a circular path in air and re-enter the tissue yielding a local dose increase. In this paper the impact of a 1.5 T magnetic field on both the build-up distance and the dose increase due to the ERE will be investigated as a function of the angle between the surface and the incident beam. Monte Carlo simulations demonstrate that in the presence of a 1.5 T magnetic field, the surface dose, the build-up distance and the exit dose depend more heavily on the surface orientation than in the case without magnetic field. This is caused by the asymmetrical pointspread kernel in the presence of 1.5 T and the directional behaviour of the re-entering electrons. Simulations on geometrical phantoms show that ERE dose increase at air cavities can be avoided using opposing beams, also when the air-tissue boundary is not perpendicular to the beam. For the more general case in patient anatomies, more problems may arise. Future work will address the possibilities and limitations of opposing beams in combination with IMRT in a magnetic field. PMID:17264362

Raaijmakers, A J E; Raaymakers, B W; van der Meer, S; Lagendijk, J J W

2007-02-21

344

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)

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.

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

2014-05-01

345

Dual pressure displacement control system  

SciTech Connect

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.

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

1988-02-02

346

Control of clinical coccidiosis of calves due to Eimeria bovis and Eimeria zuernii with toltrazuril under field conditions.  

PubMed

The efficacy of metaphylactic treatment with toltrazuril (Baycox 5% suspension) against natural infections with Eimeria bovis and/or Eimeria zuernii in calves was investigated. The study was conducted with 208 calves on five calf-rearing farms in Germany and the Czech Republic. All participating farms had a notable incidence of coccidiosis. Animals were treated 14 days after stabling in the respective facility. One group was treated with 15 mg toltrazuril/kg body weight, and a second group served as the sham-treated control. Assessment of efficacy was based on faecal consistency and oocyst excretion of E. bovis and E. zuernii, both investigated throughout the study. Duration and rate of oocyst excretion as well as number of scour days with E. bovis or E. zuernii oocyst shedding and the severity of diarrhoea were significantly lower in the toltrazuril-treated groups. It is concluded that a single metaphylactic treatment with toltrazuril controls coccidiosis of housed calves under various field conditions. PMID:16228270

Mundt, H-C; Bangoura, B; Mengel, H; Keidel, J; Daugschies, A

2005-10-01

347

Characterization of carbonate reservoir property changes due to dissolution for far-field conditions of CO2 storage  

NASA Astrophysics Data System (ADS)

Geological storage of CO2 in reservoir pore fluid (e.g. deep saline aquifers), is one of the diverse technologies being explored for deacreasing atmospheric CO2 concentration. After injecting the CO2 as a supercritical fluid at depth, it will slowly dissolve into the pore water producing low pH fluids with a high capacity for dissolving carbonates and consequently changing irreversibly the hydrodynamical properties of the reservoir. Characterizing these changes is essential for modelling flow and CO2 transport during and after the CO2 injection. Here we report experimental results from the injection of the CO2-saturated brine into two distinct limestone cores (a bioclastic carbonate and an oolitic carbonate) of 9 mm diameter, 18 mm length. 3D high-resolution X-ray microtomography (XRMT) of the rock sample have been performed before and after the experiments. The experiments were performed using in-situ sequestration conditions (P = 12MPa and T = 100°C), and notably, under chemical conditions given at the position far away from the well injection site (i.e area where the volume of dissolved CO2 into the brine is low, due to CO2 consumption by the dissolution processes occured during its transport from the well injection site). Permeability k is calculated from the pressure drop across the sample and porosity ? is deduced from chemical concentration of the outlet fluid. The change of the pore structure is analysed in terms of connectivity, tortuosity and fluid-rock interface from processing the XRMT images. These experiments show that far from the well injection site, dissolution processes are characterized by slow mass tranfer including, in the case of carbonate rock, transport of fine particles, which locally clog the porous space. Then, that leads to the damage of the carbonate reservoir both in terms of connectivity of the porous space and CO2 hydrodynamical storage capacity. In fact, the results of the two experiments show that the porosity decreased locally into the carbonate rock sample, particularly at the bottom of the sample, caused by the deposit of fine particles into the pore spaces. On the other hand, the volume ratio of voids on the top of the samples (e.g. area where the CO2 enriched fluid is more reactive) increased by dissolution of the solid and microporous phase. Indeed, the pronounced dissolution processes at the top of the samples were associated with the extraction of fine solid particles from the solid phase and especially from the microporous phase. The particles were transported in the flow direction suspended in the CO2 rich fluid away from the extraction site and were deposited somewhere else. Subsequently they formed particle aggregates through the porous space. The compartmentalization of the porous network (eg. decrease of the pore connectivity) led, for the two experiments, to the decrease of the permeability due the dissolution processes occuring during CO2 enriched fluid percolation.

Mangane, P. O.; Gouze, P.; Luquot, L.

2012-12-01

348

Particle displacement tracking for PIV  

NASA Technical Reports Server (NTRS)

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.

Wernet, Mark P.

1990-01-01

349

Generation of displaced squeezed superpositions of coherent states  

SciTech Connect

We study the method of generation of states that approximate superpositions of large-amplitude coherent states (SCSs) with high fidelity in free-traveling fields. Our approach is based on the representation of an arbitrary single-mode pure state, and SCSs in particular, in terms of displaced number states with an arbitrary displacement amplitude. The proposed optical scheme is based on alternation of photon additions and displacement operators (in the general case, N photon additions and N - 1 displacements are required) with a seed coherent state to generate both even and odd displaced squeezed SCSs regardless of the parity of the used photon additions. It is shown that the optical scheme studied is sensitive to the seed coherent state if the other parameters are unchanged. Output states can approximate either even squeezed SCS or odd SCS shifted relative to each other by some value. This allows constructing a local rotation operator, in particular, the Hadamard gate, which is a mainframe element for quantum computation with coherent states. We also show that three-photon additions with two intermediate displacement operators are sufficient to generate even displaced squeezed SCS with the amplitude 1.7 and fidelity more than 0.99. The effects deteriorating the quality of output states are considered.

Podoshvedov, S. A., E-mail: sapo66@mail.ru [South Ural State University, Department of General and Theoretical Physics (Russian Federation)

2012-03-15

350

Formation of calcite thin films by cooperation of polyacrylic acid and self-generating electric field due to aligned dipoles of polarized substrates.  

PubMed

We demonstrated the formation of calcite thin films on positively and negatively charged surfaces of a hydroxyapatite (HAp) electret coexisting with polyacrylic acid (PAA) and self-generating surface electric fields due to HAp electrets with electrically aligned dipoles. The cooperation of PAA and the self-generating surface electric field due to the electrets favored the formation of calcite thin films and acted remarkably on the negatively charged surface. Calcite thin films, 4-10 microm thick, with a shell-like microstructure were produced on the negatively charged surfaces with a small amount of PAA. In contrast, under other reaction conditions, calcite thin films with a fan-like structure in the cross section formed on the polarized substrates, and their thickness ranged from 2 to 7 microm. The films were composed of hemispheric- or flat island-shaped aggregates that were made of the calcite crystals that elongated along the c-axis. The morphology of the PAA-Ca(2+) complex assembly, which adsorbed onto the polarized HAp substrates, was controlled by the balance of the spatial charge distribution in its structure and the properties of the self-generating surface electric field, which led to the different morphologies of the calcite thin films. We proposed that the formation mechanism of the films formed coexisting with PAA and the self-generating electric fields. PMID:19062036

Wada, Norio; Nakamura, Miho; Tanaka, Yumi; Kanamura, Kiyoshi; Yamashita, Kimihiro

2009-02-15

351

de Haas-van Alphen effect in the mixed state of LuNi2B2C : Anisotropy and field dependence of the damping due to superconductivity  

NASA Astrophysics Data System (ADS)

We report observation of the de Haas-van Alphen oscillations in the mixed state as well as in the normal state of LuNi2B2C . Two oscillations ? and ? are observed in the mixed state. In particular, the ? oscillation can be studied not only deep in the mixed state as a function of magnetic field but also as a function of field direction. The damping rate of the oscillations due to superconductivity is found to be very anisotropic. For fields far below Hc2 , the damping behavior is anomalous and cannot be explained only in terms of the superconducting gap. We argue that both the anisotropy of the gap and a disorder of the flux line lattice are responsible for the anisotropic and anomalous behavior of the damping in the mixed state.

Isshiki, T.; Kimura, N.; Aoki, H.; Terashima, T.; Uji, S.; Yamauchi, K.; Harima, H.; Jaiswal-Nagar, D.; Ramakrishnan, S.; Grover, A. K.

2008-10-01

352

Forest transition in Vietnam and displacement of deforestation abroad  

PubMed Central

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.

Meyfroidt, Patrick; Lambin, Eric F.

2009-01-01

353

Uncertainties in Eddy Covariance fluxes due to post-field data processing: a multi-site, full factorial analysis  

NASA Astrophysics Data System (ADS)

Eddy Covariance (EC) is the only technologically available direct method to measure carbon and energy fluxes between ecosystems and atmosphere. However, uncertainties related to this method have not been exhaustively assessed yet, including those deriving from post-field data processing. The latter arise because there is no exact processing sequence established for any given situation, and the sequence itself is long and complex, with many processing steps and options available. However, the consistency and inter-comparability of flux estimates may be largely affected by the adoption of different processing sequences. The goal of our work is to quantify the uncertainty introduced in each processing step by the fact that different options are available, and to study how the overall uncertainty propagates throughout the processing sequence. We propose an easy-to-use methodology to assign a confidence level to the calculated fluxes of energy and mass, based on the adopted processing sequence, and on available information such as the EC system type (e.g. open vs. closed path), the climate and the ecosystem type. The proposed methodology synthesizes the results of a massive full-factorial experiment. We use one year of raw data from 15 European flux stations and process them so as to cover all possible combinations of the available options across a selection of the most relevant processing steps. The 15 sites have been selected to be representative of different ecosystems (forests, croplands and grasslands), climates (mediterranean, nordic, arid and humid) and instrumental setup (e.g. open vs. closed path). The software used for this analysis is EddyPro™ 3.0 (www.licor.com/eddypro). The critical processing steps, selected on the basis of the different options commonly used in the FLUXNET community, are: angle of attack correction; coordinate rotation; trend removal; time lag compensation; low- and high- frequency spectral correction; correction for air density fluctuations; and length of the flux averaging interval. We illustrate the results of the full-factorial combination relative to a subset of the selected sites with particular emphasis on the total uncertainty at different time scales and aggregations, as well as a preliminary analysis of the most critical steps for their contribution to the total uncertainties and their potential relation with site set-up characteristics and ecosystem type.

Sabbatini, S.; Fratini, G.; Arriga, N.; Papale, D.

2012-04-01

354

Photonic bandgap Bragg fiber sensors for bending/displacement detection.  

PubMed

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

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

2013-09-01

355

A wireless laser displacement sensor node for structural health monitoring.  

PubMed

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

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

2013-01-01

356

A Wireless Laser Displacement Sensor Node for Structural Health Monitoring  

PubMed Central

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.

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

2013-01-01

357

Retraining Displaced Workers. Policy Brief  

ERIC Educational Resources Information Center

Robert LaLonde of the University of Chicago and Daniel Sullivan of the Federal Reserve Bank of Chicago suggest that retraining through our nation's community colleges is a way to reduce the skills gaps of at least some of these displaced workers and increase their reemployment earnings. Although workers may still experience significant earnings…

LaLonde, Robert; Sullivan, Daniel

2010-01-01

358

DISPLACEMENT BASED SEISMIC DESIGN METHODS.  

SciTech Connect

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.

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

2003-07-15

359

Free displacer and Ringbom displacer for a Malone refrigerator  

SciTech Connect

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.

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

1994-05-01

360

High-accuracy displacement interferometry in air  

NASA Astrophysics Data System (ADS)

The absolute accuracy of laser interferometers employed in displacement metrology is limited by two dominant factors: uncertainties in the source vacuum wavelength and the refractive index of the ambient air. In this paper we describe an interferometer system designed to minimize these uncertainties. Based on a commercial interferometer, the new system features direct measurement of the vacuum wavelength by frequency comparison with a portable iodine-stabilized He-Ne laser. The refractive index of air is computed from accurately measured values of pressure, temperature, and relative humidity. Combined with a desktop computer, the interferometer system permits the automated field measurement of displacement errors (such as those associated with precision machine tools) with an absolute accuracy of 8.5 parts in 10^8. Performance of the interferometer in field metrology is illustrated by the results of recent validation testing of the large optics diamond turning machine (LODTM) at Lawrence Livermore National Laboratory. These results highlight the need for new measurements of the absolute refractive index of standard air in order to reduce a limiting uncertainty on such measurements of +-5 parts in 10^8.

Estler, W. Tyler

1985-03-01

361

Fossil magnetic fields due to Titan's plasma interaction revisited:The role of the electric conductivities in the ionosphere and in Titan's interior  

NASA Astrophysics Data System (ADS)

The concept of fossil magnetic fields has been introduced into the physics of Titan’s plasma interaction a few years ago ( Neubauer et al.,J.geophys.Res.,2006) and has first been applied to Titan magnetic field data by Bertucci et al.(Science, 2008) .The concept is based on the idea that because of very low plasma velocities near Titan, magnetic flux tubes entering Titan’s near plasma environment through an upstream fiducial plane at approximately XTIIS= - 3 RTitan (say) can spend up to a few hours in Titan’s environment as intact structures until they reach their lowest altitude. Eventually they are flushed out of the system. We discuss an extension of this idea by allowing the flux tubes to enter the lower ionosphere, where the frozen-in -fields concept starts to break down and diffusion of magnetic fields becomes dominant due to the increasing resistivity. However, the age of a field line can still be defined by considering a discontinuity (e.g. magnetopause related) to enter Titan’s environment through the fiducial plane referred to above. The age is shown to reach a relative maximum of several hours inside the ionosphere. Even larger ages of ~ ten days can be reached if a conducting ocean exists below Titan’s subsurface and yet larger ones if a conducting core exists. We show that observations at low altitudes and/or in a corridor in the wake of Titan are needed for observations of these fields, which are within the reach of the Cassini flyby trajectories. However, the required special inflow conditions occur relatively rarely.

Neubauer, F. M.; Hoerdt, A.; Wennmacher, A.; Simon, S.; Bertucci, C.; Dougherty, M. K.

2010-12-01

362

Differences of the Plasma Drift and Upper Thermospheric Wind Behaviour in the Northern and Southern Polar Regions due to the Geomagnetic Field Asymmetry  

NASA Astrophysics Data System (ADS)

The non-dipolar portions of Earth's main magnetic field constitute substantial differences between the geomagnetic field configurations of both hemispheres. They cause in particular different magnetic field flux densities in the opposite polar regions and different offsets of the invariant poles with respect to the rotation axis of the Earth. The offset is presently considerable larger (factor ~2) in the Southern Hemisphere compared to the Northern, which has substantial implications for the coupled magnetosphere-ionosphere-thermosphere system under the influence of external drivers. Recent observations have shown that the ionospheric/thermospheric response to solar wind and IMF dependent processes in the magnetosphere can be very dissimilar in the Northern and Southern Hemisphere. We present statistical studies of both the high-latitude ionospheric convection and the upper thermospheric circulation patterns obtained from almost a decade of measurements starting in 2001 of the electron drift instrument (EDI) on board the Cluster satellites and an accelerometer on board the CHAMP spacecraft, respectively. Using the Coupled Magnetosphere-Ionosphere-Thermosphere (CMIT) model, on the other hand, we simulated a 20-day spring equinox interval of low solar activity with both symmetric dipole and realistic (IGRF) geomagnetic field configurations to prove the importance of the hemispheric differences for the plasma and neutral wind dynamics. The survey of both the numerical simulation and the statistical observation results show some prominent asymmetries between the two hemispheres, which are likely due to the different geographic-geomagnetic offset, or even due to different patterns of geomagnetic flux densities. Plasma drift differences can partly be attributed to differing ionospheric conductivities. The forthcoming Swarm satellite mission will provide valuable observations for further detailed analyses of the North-South asymmetries of plasma convection and neutral wind dynamics.

Foerster, M.; Cnossen, I.; Haaland, S.

2013-12-01

363

Polyphenylquinoxalines via aromatic nucleophilic displacement  

NASA Technical Reports Server (NTRS)

Polyphenylquinoxalines are prepared by the nucleophilic displacement reaction of di(hydroxyphenyl)quinoxaline monomers with activated aromatic dihalides or dinitro compounds. The reactions are carried out in polar aprotic solvents during alkali metal bases at elevated temperatures under nitrogen. The di(hydroxyphenyl)quinoxaline monomers are prepared either by reacting stoichiometric quantities of aromatic bis(o-diamines) with a hydroxybenzil or by reacting o-phenylenediamine with a dihydroxybenzil or bis(hydroxyphenylglyoxylyl)benzene.

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

1991-01-01

364

Polyphenylquinoxalines via aromatic nucleophilic displacement  

NASA Technical Reports Server (NTRS)

Polyphenylquinoxalines are prepared by the nucleophilic displacement reaction of di(hydroxyphenyl)quinoxaline monomers with activated aromatic dihalides or dinitro compounds. The reactions are carried out in polar aprotic solvents using alkali metal bases at elevated temperatures under nitrogen. The di(hydroxyphenyl)quinoxaline monomers are prepared either by reacting stoichiometric quantities of aromatic bis(o-diamines) with a hydroxybenzil or by reacting o-phenylenediamine with a dihydroxybenzil or bis(hydroxyphenylglyoxylyl)benzene.

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

1990-01-01

365

Polybenzimidazole via aromatic nucleophilic displacement  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

366

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

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

367

Ultrasonic tracking of acoustic radiation force-induced displacements in homogeneous media.  

PubMed

The use of ultrasonic methods to track the tissue deformation generated by acoustic radiation force is subject to jitter and displacement underestimation errors, with displacement underestimation being primarily caused by lateral and elevation shearing within the point spread function (PSF) of the ultrasonic beam. Models have been developed using finite element methods and Field II, a linear acoustic field simulation package, to study the impact of focal configuration, tracking frequency, and material properties on the accuracy of ultrasonically tracking the tissue deformation generated by acoustic radiation force excitations. These models demonstrate that lateral and elevation shearing underneath the PSF of the tracking beam leads to displacement underestimation in the focal zone. Displacement underestimation can be reduced by using tracking beams that are narrower than the spatial extent of the displacement fields. Displacement underestimation and jitter decrease with time after excitation as shear wave propagation away from the region of excitation reduces shearing in the lateral and elevation dimensions. The use of higher tracking frequencies in broadband transducers, along with 2D focusing in the elevation dimension, will reduce jitter and improve displacement tracking accuracy. Relative displacement underestimation remains constant as a function of applied force, whereas jitter increases with applied force. Underdeveloped speckle (SNR < 1.91) leads to greater levels of jitter and peak displacement underestimation. Axial shearing is minimal over the tracking kernel lengths used in acoustic radiation force impulse imaging and thus does not impact displacement tracking. PMID:16889337

Palmeri, Mark L; McAleavey, Stephen A; Trahey, Gregg E; Nightingale, Kathryn R

2006-07-01

368

Dynamic displacement measurement of bridges using vision-based system  

NASA Astrophysics Data System (ADS)

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.

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

2006-04-01

369

Estimating Hydrologic Processes from Subsurface Soil Displacements  

NASA Astrophysics Data System (ADS)

Soil moisture and the processes that control it are important components of the hydrologic cycle, but measuring these processes remains challenging. We have developed a new measurement method that offers flexibility compared to existing technology. The approach is to measure small vertical displacements in the soil which responds proportionally to distributed surface load changes such as variation in the near-surface water content. The instrument may be installed at a depth of several meters to hundreds of meters below the surface. Because the measurement averaging region scales with the depth of the displacement measurements, this approach provides the means for estimating the soil moisture time series over tens of square meters to tens of thousands of square meters. The instrument developed for this application is called a Sand-X, which is short for Sand Extensometer. It is designed for applications in unconsolidated material, ranging from clay to sand. The instrument is simple and relatively inexpensive, and it can be installed in a boring made with a hand auger or with a small drill rig. Studies at the field scale are ongoing at a field site near Clemson, SC. The site is underlain by saprolite weathered primarily from biotite gneiss. Several Sand-X devices are installed at a field site that is instrumented for validating soil moisture, precipitation, and evapotranspiration estimates. These instruments are emplaced at a depth of 6 m and respond to the weight of a vehicle out to 18 m from the well. Calibration is performed by comparing precipitation measurements to the soil displacement response. For example, the coefficient for one installation is roughly 185 nm soil displacement/mm water content change. The resolution of the instrument is approximately 10 nm, so the Sand-X is capable of detecting changes of soil moisture on the order of tenths of one mm in compliant soils like saprolite. A typical soil displacement time series shows alternating periods of abrupt compression and gradual extension of the soil corresponding to periods of rainfall and evaporation respectively. ET estimates based on local, historic, pan evaporation data range from about 1 to 4 mm/da, and estimates of ET based on the Sand-X data track within 25% of these averages for the first half of 2012. Daily ET averages reveal periods of ET at double the monthly average during the rainy season consistent with the increased availability of soil water for evaporation. In addition to ET, the Sand-X is sensitive to changes in barometric pressure and infiltration of soil water. For example, diurnal barometric variations create a signal that is more than 10 times greater than the sensor resolution. We have developed a poroelastic model to characterize the effect of barometric loading. This analysis is used to remove the effect of barometric fluctuations and improve the resolution of hydrologic processes. Other applications for the instrument include characterizing the accumulation or removal of sediments, snow, ice, biomass, etc.

Freeman, C. E.; Murdoch, L. C.; Germanovich, L.; MIller, S.

2012-12-01

370

Effect of Job Displacement on Couple's Fertility Decisions  

Microsoft Academic Search

This paper uses Finnish longitudinal employee-employer data (FLEED) matched to birth records to estimate the effects of job displacement on fertility. We distinguish between male and female job losses. We focus on couple's where one spouse lost his\\/her job due to a plant closure in 1991 and follow them several years before and after the job loss. As a comparison

Kristiina Huttunen; Jenni Kellokumpu

2010-01-01

371

A real time fiber optic micro displacement level sensor  

Microsoft Academic Search

Detection of micro change in liquid level using PMMA fiber in real time is demonstrated in this article. This sensor operates on light intensity modulation and such modulation results due to displacement of a floating reflector. The sensor system consists of light source, encapsulated PMMA fiber, floating reflector, photo detector, transimpedence amplifier, multimeter and a data acquisition system for the

D. Sengupta; M. Sai Shankar; P. Saidi Reddy; R. L. N SaiPrasad; K. S. Narayana; P. Kishore

2011-01-01

372

40 CFR 205.153 - Engine displacement.  

Code of Federal Regulations, 2013 CFR

...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycles § 205.153 Engine displacement. (a) Engine displacement must be calculated using nominal engine values and...

2013-07-01

373

Fixture for Linearly Variable Displacement Transducers  

NASA Technical Reports Server (NTRS)

Original point of interest on shear panel tracked throughout loading. Technique and fixture measure out-of-plane displacements on shear panel using linearly variable displacement transducers (LVDT's) while tracking original panel location. Technique adaptable to any size shear panel.

Farley, G. L.; Baker, D. J.

1985-01-01

374

STRAIGHTENING THE DENSITY-DISPLACEMENT RELATION WITH A LOGARITHMIC TRANSFORM  

SciTech Connect

We investigate the use of a logarithmic density variable in estimating the Lagrangian displacement field motivated by the success of a logarithmic transformation in restoring information to the matter power spectrum. The logarithmic relation is an extension of the linear relation, motivated by the continuity equation, in which the density field is assumed to be proportional to the divergence of the displacement field; we compare the linear and logarithmic relations by measuring both of these fields directly in a cosmological N-body simulation. The relative success of the logarithmic and linear relations depends on the scale at which the density field is smoothed. Thus we explore several ways of measuring the density field, including Cloud-In-Cell smoothing, adaptive smoothing, and the (scale-independent) Delaunay tessellation, and we use both a Fourier-space and a geometrical tessellation approach to measuring the divergence. We find that the relation between the divergence of the displacement field and the density is significantly tighter and straighter with a logarithmic density variable, especially at low redshifts and for very small ({approx}2 h{sup -1} Mpc) smoothing scales. We find that the grid-based methods are more reliable than the tessellation-based method of calculating both the density and the divergence fields, though in both cases the logarithmic relation works better in the appropriate regime, which corresponds to nonlinear scales for the grid-based methods and low densities for the tessellation-based method.

Falck, Bridget L.; Neyrinck, Mark C.; Aragon-Calvo, Miguel A.; Lavaux, Guilhem; Szalay, Alexander S. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles St., Baltimore, MD 21218 (United States)

2012-01-20

375

[Contribution to the treatment of displacement of the ascendant colon in the spleen-kidney area].  

PubMed

Objective to this field study was to find an alternative to rolling a colic patient with left dorsal displacement under general anesthesia. For that purpose a total of 49 horses with a complete nephrosplenic entrapment out of 542 colic patients presented at the Tierklinik Kerken in 1996 were retrospectively evaluated. Having performed a preliminary colic examination and initial treatment if needed, horses which did not undergo surgery immediately where left loose in a small sized arena to move and roll themselves under observation. According to the results of further exams, horses were left in the arena until the displacement was corrected and were only treated if needed or underwent surgery. In 42 (85.7%) out of the 49 horses that were sent in for left dorsal displacement, the entrapment resolved itself within a period of 30 minutes to 48 hours (phi 12.1 +/- 10.4 hours) through walking and rolling themselves. Seven horses (14.3%) needed surgery (midline laparotomy) due to worsening of the general condition, repeated overload of the stomach or more dramatic colic symptoms. Two horses (4.1%) developed a gastroduodenojejunitis or thyphlocolitis postoperatively and were euthanized. The results showed that individual rolling of colic patients versus rolling under general anesthesia as a means of therapy in cases of nephrosplenic entrapment has higher success rates and also reduces the risk for the horses as no general anesthesia is necessary. PMID:9587974

Hofmeister, S; Becker, M; Böckenhoff, G

1998-04-01

376

Wireless Power Transfer during Displacement Using Electromagnetic Coupling in Resonance  

Microsoft Academic Search

This paper proposes a novel way for achieving wireless power transfer from a transmitting antenna to a receiving antenna. This technique is suitable for charging electric vehicles (EVs) because the proposed antennas can transfer power wirelessly with high efficiencies when the antennas are displaced and have large air gaps. This technique utilizes near-field antennas at resonance; however, this technique is

Takehiro Imura; Hiroyuki Okabe; Toshiyuki Uchida; Yoichi Hori

2010-01-01

377

Internal displacement and strain imaging using ultrasonic speckle tracking  

Microsoft Academic Search

Previous ultrasound speckle tracking methods have been extended, permitting measurement of internal displacement and strain fields over a wide dynamic range of tissue motion. The markedly increased dynamic range of this approach should lead to enhanced contrast resolution in strain and elasticity images. Results of experiments on gelatin-based, tissue equivalent phantoms show the capabilities of the method

M. O'Donnell; A. R. Skovoroda; B. M. Shapo; S. Y. Emelianov

1994-01-01

378

Teacher Education Center--A Displaced Campus School?  

ERIC Educational Resources Information Center

The similarities and differences between teacher education centers and campus schools are examined to clarify the objectives of the trend towards field-based teacher education. The central question of the issue is whether or not teacher centers are in fact displaced campus schools and whether this fact will render the campus school obsolete.…

Driscoll, Robert L.; Wheeler, Daniel

379

Upper Limit to Stapes Displacement: Implications for Hearing Loss.  

National Technical Information Service (NTIS)

Based on calculations from existing data, the human middle ear appears to have a displacement limit of about 30 micrometers peak to peak and becomes nonlinear at about 10 micrometers peak to peak. This nonlinearity begins at free-field SPLs of 110 to 120 ...

G. R. Price

1974-01-01

380

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

USGS Publications Warehouse

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.

Boore, D. M.

2003-01-01

381

Syndrome of transtentorial herniation: is vertical displacement necessary?  

PubMed Central

MRI from a comatose patient with a massive acute subdural haematoma showed most of the features of transtentorial herniation described in the classic pathology literature. In addition to encroachment on the perimesencephalic cisterns, infarction in the anterior and posterior cerebral artery territories, ischaemic change in the lower diencephalon, and ventricular enlargement were visualised. Despite the clinical syndrome and these secondary changes due to compression, there was only approximately 2 mm of downward displacement of the upper brainstem compared with 13 mm horizontal displacement. Although tissue shifts adjacent to the tentorial aperture cause brainstem and vascular compression, these changes may occur with minimal downward herniation. Images

Ropper, A H

1993-01-01

382

Engineering of Schroedinger cat states by a sequence of displacements and photon additions or subtractions  

SciTech Connect

A method to generate Schroedinger cat states in free propagating optical fields based on the use of displaced states (or displacement operators) is developed. Some optical schemes with photon-added coherent states are studied. The schemes are modifications of the general method based on a sequence of displacements and photon additions or subtractions adjusted to generate Schroedinger cat states of a larger size. The effects of detection inefficiency are taken into account.

Podoshvedov, S. A., E-mail: podoshvedov@mail.ru [Seoul National University, Center for Subwavelength Optics and Department of Physics and Astronomy (Korea, Republic of)

2011-04-15

383

Incorporation of the effect of the composite electric fields of molecular ions as a simulation tool for biological damage due to heavy ion irradiation II  

SciTech Connect

This paper presents a theoretical study of the DNA damage due to the effect of the composite electric fields of H{sub 2}O{sup +} ions produced from the irradiation of a heavy ion onto a cell. It is found that a much larger number of electrons, which are produced from electron impact ionization, is trapped near the track of an incident ion in the case of C{sup 6+} ion irradiation with the energy of 3 MeV/u than that of proton irradiation. Therefore, the irradiation of carbon ions may produce a larger number of cluster DNA damage than that in the irradiation of protons. This may lead to the understanding of relative biological effectiveness (RBE).

Moribayashi, Kengo [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 8-1-7, Umemidai, Kizugawa-city, 619-0215 (Japan) and Faculty of Life and Medical Sciences, Doshisha University, 1-3 Tatara Miyakodani, Kyotanabe City, 610-0394 (Japan)

2012-07-11

384

Measuring displacement derivatives by electronic speckle pattern shearing interferometry (ESPSI)  

NASA Astrophysics Data System (ADS)

Electronic speckle pattern shearing interferometry (ESPSI), also known as shearography, is a whole-field optical technique used to measure approximately the fields of displacement derivatives. The accurate measurements of these derivatives have two problems: first, although ESPSI results are approximately equal to the derivatives, they are equal to the derivatives only if the shear distance tends to zero, hence, if experimental data rendered by ESPSI are taken directly as equal to the derivatives, the measurements may carry an important shearing error; second, ESPSI yields values relative to a reference value at a specific location of the field that can be very difficult to determine accurately. In this paper, we propose a general procedure to compensate the shearing error and to introduce the reference by adding two quantities to the values rendered by ESPSI. As an example, we measured a displacement derivative field induced on a metallic sheet specimen by applying tensile load.

Labbe, Fernando; Cordero, Raúl R.; Martínez, Amalia; Rodríguez-Vera, Ramón

2005-08-01

385

Spectral properties of displacement models  

NASA Astrophysics Data System (ADS)

The recent study of Schrodinger operators with random potentials has provided significant insight into our understanding of the electronic properties of disordered media. This work presents new results concerning the spectrum of a class of random operators called displacement models. Such models may be used to model solids in which the positions of the individual atoms are randomly perturbed from an ideal periodic lattice. In particular, we will provide a characterization of the almost sure spectral minimum of the random displacement model, bounds on the integrated density of states, and a rigourous proof of the lack of classical Lifshitz tails under suitable assumptions on the random parameters. The fundamental tool used throughout the work is a quite general phenomenon in the spectral theory of Neumann problems, which we dub "bubbles tend to the boundary." How should a given compactly supported potential be placed into a bounded domain so as to minimize or maximize the first Neumann eigenvalue of the Schrdinger operator on this domain? For square or rectangular domains and reflection symmetric potentials, we show that the first Neumann eigenvalue is minimized when the potential sits in one of the corners of the domain and is maximized when it sits in the center of the domain. With different methods we also show a corresponding result for smooth strictly convex domains.

Baker, Steven

386

Interferometric fiber optic displacement sensor  

DOEpatents

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.

Farah, J.

1999-04-06

387

Interferometric fiber optic displacement sensor  

SciTech Connect

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.

Farah, J.

1995-05-30

388

Interferometric fiber optic displacement sensor  

DOEpatents

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.

Farah, John (M.I.T. P.O. Box 397301, Cambridge, MA 02139)

1999-01-01

389

Interferometric fiber optic displacement sensor  

DOEpatents

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.

Farah, John (M.I.T. Branch P.O. Box 301, Cambridge, MA 02139)

1995-01-01

390

Thermal field of an oil bed in a nonstationary pressure field  

Microsoft Academic Search

We carried out a numerical investigation of the temperature field arising in an oil bed due to the Joule-Thomson effect and\\u000a the heat of deaeration of the liquid in the nonstationary pressure field in displacement of oil by water. The formation of\\u000a the temperature field depends substantially on the initial flooding of the bed and the approach of the front

A. R. Sabitov; R. F. Sharafutdinov

1999-01-01

391

Computational Treatment of MHD Transient Natural Convection Flow in a Vertical Channel Due to Symmetric Heating in Presence of Induced Magnetic Field  

NASA Astrophysics Data System (ADS)

This paper considers the effect of induced magnetic field on transient hydromagnetic natural convection flow of an incompressible viscous electrically conducting fluid in the presence of transverse magnetic field in a vertical channel formed by electrically non-conducting infinite vertical parallel plates due to symmetric heating of vertical parallel plates. The problem is solved using Laplace transform technique and the inversion of the Laplace domain to the time domain is obtained by Riemann-sum approximation method. In order to verify the accuracy of Riemann-sum approximation method, analytical solution for steady state mathematical model is obtained in closed form. The governing equations are also solved using an implicit finite difference method to confirm the method used in the present problem. During the course of numerical computation an excellent agreement was found between steady state solution obtained exactly and transient solution obtained by implicit finite difference method or Riemann sum approximation method at large values of time. The dimensionless parameters in the flow are extensively discussed with the help of graphs.

Jha, Basant K.; Isa, Sani

2013-08-01

392

NMR spectra of oligosaccharides at ultra-high field (900 MHz) have better resolution than expected due to favourable molecular tumbling  

PubMed Central

Nuclear magnetic resonance (NMR) remains the most promising technique for acquiring atomic-resolution information in complex carbohydrates. Significant obstacles to the acquisition of such data are the poor chemical-shift dispersion and artifacts resultant from their degenerate chemical structures. The recent development of ultra-high-field NMR (at 900 MHz and beyond) gives new potential to overcome these problems, as we demonstrate on a hexasaccharide of the highly repetitive glycosaminoglycan hyaluronan. At 900 MHz, the expected increase in spectral dispersion due to higher resonance frequencies and reduction in strong coupling-associated distortions are observed. In addition, the fortuitous molecular tumbling rate of oligosaccharides results in longer T2-values that further significantly enhances resolution, an effect not available to proteins. Combined, the resolution enhancement can be as much as twofold relative to 600 MHz, allowing all 1H-resonances in the hexasaccharide to be unambiguously assigned using standard natural-abundance experiments. The use of ultra-high-field spectrometers is clearly advantageous and promises a new and exciting era in carbohydrate structural biology.

Blundell, Charles D.; Reed, Michelle A.C.; Overduin, Michael; Almond, Andrew

2006-01-01

393

Investigation of wing upper surface flow-field disturbance due to NASA DC-8-72 in-flight inboard thrust-reverser deployment  

NASA Technical Reports Server (NTRS)

An investigation of the wing upper surface flow-field disturbance due to in-flight inboard thrust reverser deployment on the NASA DC-8-72, which was conducted cooperatively by NASA Ames, the Federal Aviation Administration (FAA), McDonnell Douglas, and the Aerospace Industry Association (AIA), is outlined and discussed in detail. The purpose of this flight test was to obtain tufted flow visualization data which demonstrates the effect of thrust reverser deployment on the wing upper surface flow field to determine if the disturbed flow regions could be modeled by computational methods. A total of six symmetric thrust reversals of the two inboard engines were performed to monitor tuft and flow cone patterns as well as the character of their movement at the nominal Mach numbers of 0.55, 0.70, and 0.85. The tufts and flow cones were photographed and video-taped to determine the type of flow field that occurs with and without the thrust reversers deployed. In addition, the normal NASA DC-8 onboard Data Acquisition Distribution System (DADS) was used to synchronize the cameras. Results of this flight test will be presented in two parts. First, three distinct flow patterns associated with the above Mach numbers were sketched from the motion videos and discussed in detail. Second, other relevant aircraft parameters, such as aircraft's angular orientation, altitude, Mach number, and vertical descent, are discussed. The flight test participants' comments were recorded on the videos and the interested reader is referred to the video supplement section of this report for that information.

Hamid, Hedayat U.; Margason, Richard J.; Hardy, Gordon

1995-01-01

394

Current density and plasma displacement near perturbed rational surfaces  

SciTech Connect

The current density in the vicinity of a rational surface of a force-free magnetic field subjected to an ideal perturbation is shown to be the sum of both a smooth and a delta-function distribution, which give comparable currents. The maximum perturbation to the smooth current density is comparable to a typical equilibrium current density and the width of the layer in which the current flows is shown to be proportional to the perturbation amplitude. In the standard linearized theory, the plasma displacement has an unphysical jump across the rational surface, but the full theory gives a continuous displacement. A resolution of the paradox of a jump in the displacement is required for interpreting perturbed tokamak equilibria.

Boozer, Allen H. [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States); Pomphrey, Neil [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2010-11-15

395

Analysis of displacement of excavation based on inclinometer measurements  

NASA Astrophysics Data System (ADS)

The article presents back analysis to estimate geotechnical parameters of fill layer. The agreement between field measurements and theoretical calculations was examined. Displacements of a cantilever CFA bored pile wall were monitored. The inclinometric measurements were taken directly after pile construction and according to excavation process. Over 200 calculation series were performed, with changing fill parameters. The calculations employed the actual geometric and material parameters of the pile wall, as well as geotechnical parameters of layered soil. The parameters estimated through back analysis were the angle of internal friction and Young's modulus of fill layer. In the case discussed, pile wall cap displacement was the response of the system, and soil medium parameters were the input data. The agreement between theoretical calculations and inclinometer measurements was assessed in accordance with two functions. The measured horizontal displacements of excavation support structure assumed different values at the two inclinometer sites analysed. Back analysis results for these sites are approximately convergent for a final excavation depth.

Gorska, Karolina; Wyjad?owski, Marek

2012-10-01

396

THE EFFECTS OF GRAIN BOUNDARIES ON RADIATION DAMAGE PRODUCTION BY DISPLACEMENT CASCADES IN αFe  

Microsoft Academic Search

It is well known that grain boundaries in metals can be sinks for migrating defects such as mobile interstitial atoms, but less is known about the effects of grain boundaries on defect production and defect-grain boundary interactions due to displacement cascades in the vicinity of grain boundaries. Molecular dynamics simulations were performed for displacement cascades in the vicinity of both

Howard L. Heinisch; Richard J. Kurtz; Fei Gao

2011-01-01

397

Competitive displacement of trees in response to environmental change or introduction of exotics.  

PubMed

Various global change factors such as natural and anthropogenic climate change, tropospheric ozone, CO2, SO2, and nitrogen deposition affect forest growth, but in species-specific ways. Since even small differences in growth rates between competing species can lead to eventual competitive exclusion, it is important to know the rate at which displacement might occur. Similarly, invasive species may displace native species and cause their extinction. A simulation study of displacement velocity was conducted. Competitive displacement between pairs of similar tree species in which one species has a growth advantage produced trajectories that fit an exponential decay model, leading to the use of the half-life as a useful summary statistic. At any given level of growth differential, the half-life for shade-tolerant species was found to be much longer than for shade-intolerant species due to the ability of shade-tolerant species to survive even when their growth is very slow. Trees with longer life-spans also persisted longer, but this effect was weaker than the shade-tolerance effect. Disturbances speeded up displacement by increasing tumover. For short-lived, intolerant species with a 20% disturbance rate and 20% growth suppression, the estimate of an approximately 100-year half-life could be considered a precipitous rate of decline, with a risk of extinction at about 500 years. In the absence of disturbance, and with a 20% growth reduction or differential between competing species, half-lives for species replacement ranged from 100+ to nearly 800 years. With lesser growth differentials, half-lives are much longer. Such gradual competitive displacement processes will be very difficult to detect in the field over periods of even decades. Results of this study have implications for exotic species invasions. It is predicted that intact forest is not truly resistant to invasion, but that invasion of shade-tolerant tree species should be very slow. Invasion of shade-intolerant species is predicted to be accelerated by disturbance, as has been frequently observed. Results of the simulations were supported by data compiled from several parts of the world. PMID:14703916

Loehle, Craig

2003-07-01

398

A computer vision-based approach for structural displacement measurement  

NASA Astrophysics Data System (ADS)

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.

Ji, Yunfeng

2010-03-01

399

Variable delivery, fixed displacement pump  

DOEpatents

A variable delivery, fixed displacement pump comprises a plurality of pistons reciprocated within corresponding cylinders in a cylinder block. The pistons are reciprocated by rotation of a fixed angle swash plate connected to the pistons. The pistons and cylinders cooperate to define a plurality of fluid compression chambers each have a delivery outlet. A vent port is provided from each fluid compression chamber to vent fluid therefrom during at least a portion of the reciprocal stroke of the piston. Each piston and cylinder combination cooperates to close the associated vent port during another portion of the reciprocal stroke so that fluid is then pumped through the associated delivery outlet. The delivery rate of the pump is varied by adjusting the axial position of the swash plate relative to the cylinder block, which varies the duration of the piston stroke during which the vent port is closed.

Sommars, Mark F. (Sparland, IL)

2001-01-01

400

Displaced electrode process for welding  

SciTech Connect

A method is described for the butt-welding of a relatively heavy mass to a relatively small mass such as a thin-wall tube. In butt-welding heat is normally applied at the joint between the two pieces which are butt-welded together. The application of heat at the joint results in overheating the tube which causes thinning of the tube walls and porosity in the tube material. This is eliminated by displacing the welding electrode away from the seam toward the heavier mass so that heat is applied to the heavy mass and not at the butt seam. Examples of the parameters used in welding fuel rods are given. The cladding and end plugs were made of Zircalloy. The electrode used was of 2 percent thoriated tungsten. (auth)

Heichel, L.J.

1975-08-26

401

A combined optical technique for 360-degree measurement of 3D shape and deformation field of discontinuous surface  

Microsoft Academic Search

Many applications in industry require non-contact, fast and accurate measurement of both surface profile and deformation field for manufactu ring quality control and structural testing purposes. The fringe projection technique has been widely used due to its high accuracy and spatial resolution in measuring shape and out-of-pl ane displacement fields, but it cannot identify in-plane displacements reliably for surfac es

T. Nam Nguyen

402

Reciprocating magnetic refrigerator employing tandem porous matrices within a reciprocating displacer  

NASA Technical Reports Server (NTRS)

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.

Johnson, D. L. (inventor)

1985-01-01

403

A formal interpretation of the displacement current and the instantaneous formulation of Maxwell's equations  

Microsoft Academic Search

Maxwell's displacement current has been the subject of controversy for more than a century. Questions on whether the displacement current represents a true current like the conduction current and whether it produces a magnetic field have recently been discussed in the literature. Similar interpretations for the Faraday induction current have also been controversial. These basic questions are answered by considering

José A. Heras

2011-01-01

404

Displaced Women in Northern GhanaIndigenous Knowledge About Ethnic Conflict  

Microsoft Academic Search

This article presents the findings of field research in Ghana in 2002 about internal displacement stemming from multiethnic violence in northern Ghana in 1994, known as the “Guinea Fowl War.” Indigenous, gender-specific knowledge from displaced Ghanaian women is presented in the context of feminist perspectives on the consequences of regional wars on non-combatants. The research generated indigenous material for social

Brenda Faye McGadney-Douglass; William K. Ahadzie

2008-01-01

405

An overview and a contribution to the optical measurement of linear displacement  

Microsoft Academic Search

The present work is a contribution to the field of linear displacement measurements by optical means. For that purpose, a brief overview of some existing solutions is presented and two systems for axial linear displacement measurement based on light intensity detection are introduced. The systems have redundancy and were designed with the purpose of achieving identification and automatic correction of

P. M. B. S. Girao; Octavian A. Postolache; José A. Brandão Faria; José M. C. Dias Pereira

2001-01-01

406

Detection of quasi-static displacement components of LP seismic sources near the volcanic summit  

NASA Astrophysics Data System (ADS)

Seismic long-period (LP) events are still not completely understood, but widely accepted source models involve fluids and fluid-driven resonance processes. Due to the difficulties related to installing seismometers in summit regions of volcanoes, the observations of volcanic seismicity are usually performed at distances not closer than 1-2 km from the hypocentre of a seismic event. Observations from high-density network experiments on different volcanoes lead to a new model proposed by Bean et al. (Nature Geoscience, January 2014). Therein LP events are explained as a consequence of a brittle-ductile failure occurring under the low-stress conditions in the shallow volcanic edifice, rather than fluid-driven resonance. One consequence of this model is a static displacement associated with these LP events. Unfortunately, the expected amplitude of the static shift is only several micrometres, i.e. not detectable by typical deformation measurements. Therefore, we try to develop methods for using seismometers as static shift detecting sensors. Our current inability to recover the full spectrum of recorded displacement results in a band-limited representation of the true process derived from moment-tensor inversions. If the actual source process is of a broadband character, our narrow-band results can be quite misleading. In this study we are focusing on quasi-static displacements we observed on seismometer data from Turrialba Volcano (Costa Rica) and Mt Etna (Italy). These appear as ramp-like signals on displacement traces of LP events, most commonly on all three seismometer components, and have a magnitude of a few micrometres. Laboratory tests confirm that the seismometers used in our field experiments can indeed measure step-like signals, but they also show that long period noise can be a problem when trying to interpret these. Normal high pass filters suitable to remove this noise cannot be applied without losing the signal we are interested in. Therefore special attention has to be paid to the processing steps preceding the interpretation of data. In order to constrain the data and test the applied methods, we compare field data and laboratory data with numerical simulations. Considering the full broadband spectrum of the recorded displacements may shed new light on the long period part of the source process.

Thun, Johannes; Bean, Christopher J.; Lokmer, Ivan

2014-05-01

407

COMPETITIVE DISPLACEMENT AMONG INSECTS AND ARACHNIDS  

Microsoft Academic Search

? Abstract Competitive displacement,is the most severe outcome,of interspecific competition. For the purposes of this review, we define this type of displacement as the removal,of a formerly established species from a habitat as a result of direct or indirect competitive,interactions with another species. We reviewed,the literature for recent putative cases of competitive displacement,among,insects and arachnids and assessed the evidence,for the

Stuart R. Reitz; John T. Trumble

2001-01-01

408

An improved displacement damage monitor LED  

Microsoft Academic Search

A frequency-domain technique for measuring carrier lifetime in GaAs light-emitting-diode (LED) displacement damage monitors capable of high sensitivity and repeatability is developed. Applications of this technique that take advantage of the high sensitivity of this method, including the measurement of the threshold energy for lattice displacement in GaAs, are described. The measured minimum electron energy for displacement damage was 270±15

A. L. Barry; R. Maxseiner; R. Wojcik; M. A. Briere; D. Braeunig

1990-01-01

409

Transverse sacral fractures with anterior displacement  

Microsoft Academic Search

Transverse fractures of the sacrum with anterior displacement are the rarest type of transverse sacral fractures. They usually\\u000a occur at the S1–S2 region in suicide jumpers. A clinical study was performed to evaluate the diagnosis, treatment and outcome\\u000a of transverse sacral fractures with anterior displacement. We present six patients with a transverse fracture of the sacrum\\u000a with anterior displacement. All

George S. Sapkas; Andreas F. Mavrogenis; Panayiotis J. Papagelopoulos

2008-01-01

410

Lateral displacement estimation using tissue incompressibility  

Microsoft Academic Search

Using the incompressibility property of soft tissue, lateral displacements can be reconstructed from axial strain measurements. Results of simulations and experiments on gelatin-based tissue equivalent phantoms are compared with theoretical displacements, as well as estimates derived from traditional speckle tracking. Incompressibility processing greatly improves the accuracy and signal-to-noise ratio (SNR) of lateral displacement measurements compared with more traditional speckle tracking

Mark A. Lubinski; Stanislav Y. Emelianov; K. R. Raghavan; Andrew E. Yagle; Andrei R. Skovoroda; Matthew O'Donnell

1996-01-01

411

Displacement based multilevel structural optimization  

NASA Technical Reports Server (NTRS)

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.

Striz, Alfred G.

1995-01-01

412

Microbial Adhesion in Flow Displacement Systems  

PubMed Central

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.

Busscher, Henk J.; van der Mei, Henny C.

2006-01-01

413

Influence of lateral displacement on the levitation performance of a magnetized bulk high-Tc superconductor magnet  

NASA Astrophysics Data System (ADS)

Compared with the permanent magnet, the magnetized bulk high-Tc superconductor magnet (MBSCM) can trap higher magnetic field due to its strong flux pinning ability, so it is a good candidate to improve the levitation performance of high-Tc superconductive (HTS) maglev system. The trapped magnetic flux of a MBSCM is sustained by the inductive superconducting current produced by the magnetizing process and is susceptible to the current intensity as well as configuration. In the HTS maglev system, the lateral displacement is an important process to change the superconducting current within a MBSCM and then affects its levitation performance, which is essential for the traffic ability in curve-way, the loading capacity of lateral impact and so on. The research about influence of lateral displacement on the levitation performance of MBSCM is necessary when MBSCM is applied on the HTS maglev vehicle. The experimental investigations about the influence of lateral displacement on the levitation performance of a MBSCM with different trapped fluxes and applied fields are processed in this article. The analyses and conclusions of this article are useful for the practical application of MBSCM in HTS maglev system.

Liu, W.; Wang, J. S.; Ma, G. T.; Zheng, J.; Tuo, X. G.; Li, L. L.; Ye, C. Q.; Liao, X. L.; Wang, S. Y.

2012-03-01

414

Testing fault displacement-length scaling relations through analogue modeling in an extensional setting  

NASA Astrophysics Data System (ADS)

The scaling relation between displacement and length of faults plays a crucial role in understanding the growth history of individual faults and their possible linkage and reactivation in future ruptures. Displacement-length relations are commonly based on empirical data. The measurement of fault geometric properties, however, is generally affected by large scattering due not only to intrinsic difficulties of making observations in natural cases (outcrop availability, seismic profiles), but also to the variety of geological factors that may affect the rupture patterns. These can be the interaction between the present-day tectonic regime and an inherited structural fabric, or that between a master fault at depth and shallow structural features. As an alternative to field observations, analogue modeling provides an opportunity to investigate the faulting processes in a controlled environment. During the last decade, the ability of scaled models to properly reproduce such geological processes has greatly improved thanks to the introduction of new materials (e.g. wet kaolin) suitable for reproducing brittle deformation in the upper crust and hi-tech monitoring systems (e.g. laser scanner, particle image velocimetry) with the ability of capturing structural details and performing accurate measurements. We use a dedicated apparatus with such properties to gain insights on the evolution of extensional faults through a suite of experiments which includes (a) setups in homogeneous material to test our ability in meeting general criteria related with fault displacement-length parameters; and (b) increasing complexities attained by inserting various pre-existing fault patterns to analyze how shallow mechanical discontinuities affect our ability to characterize a major fault at depth. Our results show that pre-existing faults can either halt or favor fault development and growth depending on their location/orientation with respect to the applied stress field and suggest the reappraisal of natural case studies under a different perspective.

Bonini, L.; Basili, R.; Burrato, P.; Kastelic, V.; Toscani, G.; Seno, S.; Valensise, G.

2013-12-01

415

Polybenzoxazole via aromatic nucleophilic displacement  

NASA Technical Reports Server (NTRS)

Polybenzoxazoles (PBO) are heterocyclic macromolecules which were first synthesized in a two-step process by the initial formation of aromatic diacid chlorides with bis(o-aminophenol)s through solution condensation of aromatic diacid chlorides with bis(o-aminophenol)s followed by thermal cyclodehydration. Since then several methods were utilized in their synthesis. The most common synthetic method for PBO involves a polycondensation of bis(o-aminophenol)s with aromatic diacid diphenyl esters. Another preparative route involves the solution polycondensation of the hydrochloride salts of bis(o-amino phenol)s with aromatic diacids in polyphosphoric acid. Another synthetic method involves the initial formation of poly(o-hydroxy amide)s from silylated bis(o-aminophenol)s with aromatic diacid chlorides followed by thermal cyclodehydration to PBO. A recent preparative route involves the reaction of aromatic bisphenols with bis(fluorophenyl) benzoxazoles by the displacement reaction to form PBO. The novelty of the present invention is that high molecular weight PBO of new chemical structures are prepared that exhibit a favorable combination of physical and mechanical properties.

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

1993-01-01

416

Erosion due to cultivation of calcareous clay soils on hillsides in south-west France. II. Effect of ploughing down the steepest slope  

Microsoft Academic Search

The erosion of calcareous clay soils from Terrefort in south west France is not exclusively due to run-off water. An experiment was carried out in situ to quantify the effect of ploughing on the displacement of soil down the slope. In a field experiment, a trench 0.4 m × 0.4 m × 20 m was dug parallel to the contours

M. Guiresse; J. C. Revel

1995-01-01

417

Effects of Fault Displacement on Emplacement Drifts  

SciTech Connect

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.

F. Duan

2000-04-25

418

Reciprocating Magnetic Refrigerator Employing Tandem Porous Matrices within a Reciprocating Displacer.  

National Technical Information Service (NTIS)

A method and apparatus for a magnetic refrigeration system are described. 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 bidirecti...

D. L. Johnson

1984-01-01

419

Stress intensity and crack displacement for small edge cracks  

NASA Technical Reports Server (NTRS)

The weight function method was used to derive stress intensity factors and crack mouth displacement coefficients for small edge cracks (less than 20 percent of the specimen width) in common fracture specimen configurations. Contact stresses due to point application of loads were found to be small but significant for three-point bending and insignificant for four-point bending. The results are compared with available equations and numerical solutions from the literature and with unpublished boundary collocation results.

Orange, Thomas W.

1988-01-01

420

Investigation of operating parameters in high-performance displacement chromatography.  

PubMed

The effect of operational parameters of displacement chromatography was examined in the separation of various mixtures such as that of the main hydrolysis products of methylfurylbutyrolactone, a potential anticancer drug, the diastereoisomers benzoyl-D- and benzoyl-L-phenylalanyl-L-alanyl-L-proline, as well as polyethylene glycol homologues containing 1-10 ethylene oxide units. The chromatograph was assembled from modules generally used in analytical high-performance liquid chromatography (HPLC) and the column effluent was analyzed by an on-line HPLC unit at 30-sec intervals. Octadecyl-silica was used throughout as the stationary phase. Derivatives of ethylene glycol and propylene glycol as well as tetrabutylammonium bromide and n-butanol were used as displacers. The throughput was used as the measure of efficiency. In the absence of axial dispersion, for a given separation various displacers are expected to yield the same efficiency if the slope of the operating line is kept the same by appropriate adjustment of displacer concentrations. In practice, however, the optimum slope of the operating line has to be determined experimentally as most available chromatographic systems depart from ideal behavior. The dependence of the throughput on the flow-rate and feed load also indicated the presence of non-equilibrium phenomena and the optimum value of these parameters was established experimentally. In most cases water was used as the carrier solvent but the separation of poorly soluble peptides required the use of hydro-organic carriers. Results obtained with octadecyl-silicas of different origin and a given displacer were found to vary significantly suggesting that even for stationary phases of the same type the selection of displacer requires special consideration. Most experiments were carried out with columns having dimensions customary in analytical HPLC. Increasing the inner diameter of the column did not result in the expected increase in throughout probably due to poor distribution of the sample at the column entrance. Therefore scaling-up the process requires careful engineering of inlet conditions. Throughput can be increased by connecting a small inner diameter column to the outlet of a large diameter preparative column. As theoretical predictions for ideal displacement chromatography do not hold in practice when axial dispersion is significant, optimization of the process requires experimental support. The results obtained in the separation of a variety of mixtures shed light on the most important operational aspects of displacement chromatography and suggest approaches to find optimum conditions.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:4044730

Frenz, J; van der Schrieck, P; Horváth, C

1985-08-01

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