Science.gov

Sample records for displacement field due

  1. Magnetic Field Due to a Finite Length Current-Carrying Wire Using the Concept of Displacement Current

    ERIC Educational Resources Information Center

    Buschauer, Robert

    2014-01-01

    In undergraduate E&M courses the magnetic field due to a finite length, current-carrying wire can be calculated using the Biot-Savart law. However, to the author's knowledge, no textbook presents the calculation of this field using the Ampere-Maxwell law: ?B [multiplied by] dl = µ[subscript 0] (I + e[subscript 0] dF/dt) [multiplied by] 1

  2. Crustal displacements due to continental water loading

    USGS Publications Warehouse

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

    2001-01-01

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

  3. Crustal Displacements Due to Continental Water Loading

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    The effects of long-wavelength (> 100 km), seasonal variability in continental water storage on vertical crustal motions are assessed. The modeled vertical displacements (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.

  4. Displacement field measurement in the nanometer range

    NASA Astrophysics Data System (ADS)

    Surrel, Yves; Fournier, Nicolas

    1996-09-01

    The grid method is a classical tool for displacement measurement, which provides field data. This method has benefited very much from the phase-shifting technique in recent years. Two examples of applications of this method in the nanometer range are presented. The first one concerns the materials science: it is shown that microgrids observed by SEM can provide displacement field data with an accuracy of a few nanometers. The second one concerns the measurement of a rigid-body displacement. In this case, displacement data can be averaged over the whole field, drastically increasing the sensitivity. It is shown that a sensitivity of 7 nm can be achieved by using a coarse grid with 8 lines per mm. This sensitivity corresponds to 1/18000 of the grid pitch.

  5. Relativistic Lagrangian displacement field and tensor perturbations

    NASA Astrophysics Data System (ADS)

    Rampf, Cornelius; Wiegand, Alexander

    2014-12-01

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

  6. Feynman's Proof and Non-Elastic Displacement Fields: Relationship Between Magnetic Field and Defects Field

    NASA Astrophysics Data System (ADS)

    Nakamura, Nozomu; Yamasaki, Kazuhito

    2016-12-01

    We consider the relationship between the magnetic field and the non-elastic displacement field including defects, from the viewpoints of non-commutativity of the positions and non-commutativity of the derivatives. The former non-commutativity is related to the magnetic field by Feynman's proof (1948), and the latter is related to the defect fields by the continuum theory of defects. We introduce the concept of differential geometry to the non-elastic displacement field and derive an extended relation that includes basic equations, such as Gauss's law for magnetism and the conservation law for dislocation density. The relation derived in this paper also extends the first Bianchi identity in linear approximation to include the effect of magnetism. These findings suggest that Feynman's approach with a non-elastic displacement field is useful for understanding the relationship between magnetism and non-elastic mechanics.

  7. Mesodermal cell displacements during avian gastrulation are due to both individual cell-autonomous and convective tissue movements.

    PubMed

    Zamir, Evan A; Czirók, András; Cui, Cheng; Little, Charles D; Rongish, Brenda J

    2006-12-26

    Gastrulation is a fundamental process in early development that results in the formation of three primary germ layers. During avian gastrulation, presumptive mesodermal cells in the dorsal epiblast ingress through a furrow called the primitive streak (PS), and subsequently move away from the PS and form adult tissues. The biophysical mechanisms driving mesodermal cell movements during gastrulation in amniotes, notably warm-blooded embryos, are not understood. Until now, a major challenge has been distinguishing local individual cell-autonomous (active) displacements from convective displacements caused by large-scale (bulk) morphogenetic tissue movements. To address this problem, we used multiscale, time-lapse microscopy and a particle image velocimetry method for computing tissue displacement fields. Immunolabeled fibronectin was used as an in situ marker for quantifying tissue displacements. By imaging fluorescently labeled mesodermal cells and surrounding extracellular matrix simultaneously, we were able to separate directly the active and passive components of cell displacement during gastrulation. Our results reveal the following: (i) Convective tissue motion contributes significantly to total cell displacement and must be subtracted to measure true cell-autonomous displacement; (ii) Cell-autonomous displacement decreases gradually after regression from the PS; and (iii) There is an increasing cranial-to-caudal (head-to-tail) cell-autonomous motility gradient, with caudal cells actively moving away from the PS faster than cranial cells. These studies show that, in some regions of the embryo, total mesodermal cell displacements are mostly due to convective tissue movements; thus, the data have profound implications for understanding cell guidance mechanisms and tissue morphogenesis in warm-blooded embryos.

  8. Comment on "No evidence of displacement due to wind turbines in breeding grassland songbirds"

    USGS Publications Warehouse

    Johnson, Douglas H.

    2016-01-01

    A recent article published in The Condor: Ornithological Applications by Hale et al. (2014) is entitled, “No evidence of displacement due to wind turbines in breeding grassland songbirds.” The conclusion stated in that title, unfortunately, is based on inappropriate statistical analysis of data collected by the authors. In fact, their data provide evidence of potential displacement by wind turbines in 2 of the 3 species considered.

  9. Application of miscible displacement for Field MTX low permeability formations

    NASA Astrophysics Data System (ADS)

    Kuntsevich, V.; Slivkin, S.; Belozerov, V.

    2015-02-01

    Miscible displacement is a very effective method of recovery efficiency improvement. It is widely used in the world, but this technology is not widely used in Russia. For this reason, it is necessary to study global experience and physical aspects of this EOR method. The most important factors and limitations of miscible displacement application from the geological point of view (heterogeneity) and from the physical point of view (properties of injected fluids and reservoir fluids) should be determined. The results of this analysis should be tested on the low permeability reservoir of field MTX with analytical, proxy calculation and simulation methods.

  10. Modulating the Near Field Coupling through Resonator Displacement in Planar Terahertz Metamaterials

    NASA Astrophysics Data System (ADS)

    Mohan Rao, S. Jagan; Kumar, Deepak; Kumar, Gagan; Chowdhury, Dibakar Roy

    2017-01-01

    We present the effect of vertical displacements between the resonators inside the unit cell of planar coupled metamaterials on their near field coupling and hence on the terahertz (THz) wave modulation. The metamolecule design consists of two planar split- ring resonators (SRRs) in a unit cell which are coupled through their near fields. The numerically simulated transmission spectrum is found to have split resonances due to the resonance mode hybridization effect. With the increase in displacement between the near field coupled SRRs, this metamaterial system shows a transition from coupled to uncoupled state through merging of the split resonances to the single intrinsic resonance. We have used a semi-analytical model describing the effect of displacements between the resonators and determine that it can predict the numerically simulated results. The outcome could be useful in modulating the terahertz waves employing near field coupled metamaterials, hence, can be useful in the development of terahertz modulators and frequency tunable devices in future.

  11. PREDICTION OF SURFACE SETTLEMENT DUE TO THE DISPLACEMENT OF SOFT ZONES

    SciTech Connect

    Li, W

    2008-03-03

    In areas composed of coastal plain sediments, soft zones subjected to partial overburden may be present in the subsurface. During or after a seismic event, these soft zones may be compressed. The resulting displacement due to the deformation of the soft zones will propagate to the ground surface and cause the surface to settle. This paper presents a method to predict the settlement at the surface due to the propagation of the displacement from the soft zones. This method is performed by discretizing the soft zones into multiple clusters of finite sub-areas or subspaces. Settlement profile at the ground surface due to the displacement of each sub-area or subspace is computed assuming the shape is a normal distribution function. Settlement due to the displacement of the soft zones can then be approximated by adding the settlements computed for all the sub-areas or subspaces. This method provides a simple and useful tool for the prediction of the settlement profile and the results are consistent with those obtained from the finite difference analysis.

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

    USGS Publications Warehouse

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

    2006-01-01

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

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

    SciTech Connect

    Brower, K.L.

    1997-09-01

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

  14. Dense motion field estimation from myocardial boundary displacements.

    PubMed

    Morais, Pedro; Queirós, Sandro; Ferreira, Adriano; Rodrigues, Nuno F; Baptista, Maria J; D'hooge, Jan; Vilaça, João L; Barbosa, Daniel

    2016-09-01

    Minimally invasive cardiovascular interventions guided by multiple imaging modalities are rapidly gaining clinical acceptance for the treatment of several cardiovascular diseases. These images are typically fused with richly detailed pre-operative scans through registration techniques, enhancing the intra-operative clinical data and easing the image-guided procedures. Nonetheless, rigid models have been used to align the different modalities, not taking into account the anatomical variations of the cardiac muscle throughout the cardiac cycle. In the current study, we present a novel strategy to compensate the beat-to-beat physiological adaptation of the myocardium. Hereto, we intend to prove that a complete myocardial motion field can be quickly recovered from the displacement field at the myocardial boundaries, therefore being an efficient strategy to locally deform the cardiac muscle. We address this hypothesis by comparing three different strategies to recover a dense myocardial motion field from a sparse one, namely, a diffusion-based approach, thin-plate splines, and multiquadric radial basis functions. Two experimental setups were used to validate the proposed strategy. First, an in silico validation was carried out on synthetic motion fields obtained from two realistic simulated ultrasound sequences. Then, 45 mid-ventricular 2D sequences of cine magnetic resonance imaging were processed to further evaluate the different approaches. The results showed that accurate boundary tracking combined with dense myocardial recovery via interpolation/diffusion is a potentially viable solution to speed up dense myocardial motion field estimation and, consequently, to deform/compensate the myocardial wall throughout the cardiac cycle. Copyright © 2015 John Wiley & Sons, Ltd.

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

    SciTech Connect

    Tandanand, S.; Powell, L.R.

    1991-01-01

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

  16. Double-shot depth-resolved displacement field measurement using phase-contrast spectral optical coherence tomography.

    PubMed

    De la Torre-Ibarra, Manuel H; Ruiz, Pablo D; Huntley, Jonathan M

    2006-10-16

    We describe a system for measuring sub-surface displacement fields within a scattering medium using a phase contrast version of spectral Optical Coherence Tomography. The system provides displacement maps within a 2-D slice extending into the sample with a sensitivity of order 10 nm. The data for a given deformation state is recorded in a single image, potentially allowing sub-surface displacement and strain mapping of moving targets. The system is based on low cost components and has no moving parts. The theoretical basis for the system is presented along with experimental results from a simple well-controlled geometry consisting of independently-tilting glass sheets. Results are validated using standard two-beam interferometry. A modified system was used to measure through-the-thickness phase changes within a porcine cornea due to displacements produced by an increase in the intraocular pressure.

  17. Retrieving three-dimensional displacement fields of mining areas from a single InSAR pair

    NASA Astrophysics Data System (ADS)

    Li, Zhi Wei; Yang, Ze Fa; Zhu, Jian Jun; Hu, Jun; Wang, Yun Jia; Li, Pei Xian; Chen, Guo Liang

    2015-01-01

    This paper presents a novel method for retrieving three-dimensional (3-D) displacement fields of mining areas from a single interferometric synthetic aperture radar (InSAR) pair. This method fully exploits the mechanism of mining subsidence, specifically the proportional relationship between the horizontal displacement and horizontal gradient of vertical displacements caused by underground mining. This method overcomes the limitations of conventional InSAR techniques that can only measure one-dimensional (1-D) deformation of mining area along the radar line-of-sight direction. The proposed method is first validated with simulated 3-D displacement fields, which are obtained by the FLAC software. The root mean square errors of the 3-D displacements retrieved by the proposed method are 13.7, 27.6 and 3.6 mm for the West-East, North-South, and Up-Down components, respectively. We then apply the proposed method to estimate the 3-D displacements of the Qianyingzi and the Xuzhou coal mines in China, respectively, each along with two Advanced Land Observing Satellite (ALOS) Phased Array Type L-band Synthetic Aperture Radar images. Results show that the estimated 3-D displacement is highly consistent with that of the field surveying. This demonstrates that the proposed method is an effective approach for retrieving 3-D mining displacement fields and will play an important role in mining-related hazard prevention and environment assessment under limited InSAR acquisitions.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  19. Effect of horizontal displacements due to ocean tide loading on the determination of polar motion and UT1

    NASA Astrophysics Data System (ADS)

    Scherneck, Hans-Georg; Haas, Rüdiger

    We show the influence of horizontal displacements due to ocean tide loading on the determination of polar motion and UT1 (PMU) on the daily and subdaily timescale. So called ‘virtual PMU variations’ due to modelling errors of ocean tide loading are predicted for geodetic Very Long Baseline Interferometry (VLBI) networks. This leads to errors of subdaily determination of PMU. The predicted effects are confirmed by the analysis of geodetic VLBI observations.

  20. Buckling analysis of moderately thick rectangular plates using coupled displacement field method

    NASA Astrophysics Data System (ADS)

    Meera Saheb, K.; Aruna, K.

    2015-12-01

    A simple and efficient coupled displacement field method is developed to study the buckling load parameters of the moderately thick rectangular plates. This method has been successfully applied to study the same for the Timoshenko beams. A single term trigonometric admissible displacement field is assumed for one of the variables, say, the total rotations (in both X, Y directions). Making use of the coupling equations, the spatial variation for the remaining lateral displacement field is derived in terms of the total rotations. The coupled displacement field method makes the energy formulation to contains half the number of unknown independent coefficients, in the case of a rectangular plate, contrary to the conventional Rayleigh-Ritz method. The expressions for the non-dimensional buckling load parameters of the moderately thick rectangular plates with all the edges simply supported are derived. The numerical values of these parameters obtained using the coupled displacement field method match very well with open literature demonstrating the effectiveness of the coupled displacement field method.

  1. Displacement Current and the Generation of Parallel Electric Fields

    SciTech Connect

    Song Yan; Lysak, Robert L.

    2006-04-14

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    Injection of fluids into deep saline aquifers induces an increase in pore pressure in the storage formation, and thus displacement of resident brines. Upward brine migration into shallower aquifers via hydraulically conductive faults may therefore lead to unwanted salinization of potable groundwater resources. In the present study, we investigated different scenarios for a prospective storage site close to the city of Beeskow in the Northeast German Basin by using a representative 3D regional-scale model (100 km x 100 km x 1.34 km) that includes four regional fault zones. The focus was on assessing the impact of fault length and permeability as well as model boundary conditions on the potential salinization of shallow groundwater resources. Moreover, the effects of an overlying secondary brine-bearing reservoir as well as varying initial salt-freshwater boundaries were investigated. We employed numerical simulations of brine injection as a representative fluid based on an example case study discussed by Tillner et al. (2013). Our simulation results demonstrate that pressure build-up within the reservoir determines the fluid rates and duration through the faults, and hence salinization of shallower aquifers. Application of different boundary conditions proved that these have a crucial impact on reservoir fluid displacement. If reservoir boundaries are closed, the fluid displaced via the faults into the shallow aquifer corresponds to the overall injected fluid mass. In that case, fault length and permeability as well as the presence of an overlying secondary reservoir have only temporal effects on brine migration. A fault zone with a hydraulically conductive segment of only two kilometres length causes brine flow into the shallow aquifer of 330 years, which is thus five times longer compared to the case with four faults open over their entire length of 193 km. The presence of an overlying secondary reservoir leads to an additional retardation of brine inflow into the

  3. Atomic displacements due to spin-spin repulsion in conjugated alternant hydrocarbons

    NASA Astrophysics Data System (ADS)

    Estrada, Ernesto; Benzi, Michele

    2013-05-01

    We develop a theoretical model to account for the spin-induced atomic displacements in conjugated alternant hydrocarbons. It appears to be responsible for an enlargement of the distance between pairs of atoms separated by two atoms and located at the end of linear polyenes. It also correlates very well with the bond dissociation enthalpies for the cleavage of the C-H bond as well as to the spin density at carbon atoms in both open and closed shell at graphene nanoflakes (GNFs). Finally, we have modified the Schrödinger equation to study the propagation of the spin-induced perturbations through the atoms of GNFs.

  4. Proximal aortic stent-graft displacement with type I endoleak due to Heimlich maneuver.

    PubMed

    Lin, Peter H; Bush, Ruth L; Lumsden, Alan B

    2003-08-01

    The Heimlich maneuver has saved countless lives by relieving foreign body obstruction from the respiratory tract. Complications related to this life-saving technique, particularly involving the abdominal aorta, are extremely rare. We report the case of a patient who underwent successful endovascular abdominal aortic aneurysm (AAA) repair, with AAA reduction at postoperative surveillance. Endograft displacement after performance of the Heimlich maneuver resulted in a proximal type I endoleak. This case underscores both the potential for aortic trauma from the Heimlich maneuver and the risk for clinical failure as a result of abdominal compression after successful endovascular AAA repair.

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

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    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.

  6. Tooth displacement due to occlusal contacts: a three-dimensional finite element study.

    PubMed

    Gomes de Oliveira, S; Seraidarian, P I; Landre, J; Oliveira, D D; Cavalcanti, B N

    2006-12-01

    The use of the Finite Element Method (FE) is an appropriate way to study occlusal forces and tooth movement. The purpose of this study was to evaluate the effects of different occlusal contact patterns on tooth displacement in an adult dentition using a three-dimensional FE model of a human maxilla and mandible. Initially, images of a computerized tomography scan were redrawn in a computer program (CATIA) followed by the FE mesh construction. The MSC/Patran software was used to develop the FE mesh comprising 520,445 elements and 106,633 nodes. The MSC/Nastran program was utilized as pre and post-processor for all mathematical calculations necessary to evaluate dental and mandibular biomechanics. Four occlusal patterns were tested: FEM 1 - standard occlusal contacts; FEM 2 - removal of mesial marginal and mesial tripoidism contacts; FEM 3 - removal of distal marginal and distal tripoidism contacts; FEM 4 - similar to FEM 3 with added contacts between upper and lower incisors. Small changes in the standard distribution of occlusal contacts resulted in an imbalance of occlusal forces and changes in dental positioning. All simulations tested showed mesial displacement of posterior teeth. The most significant changes were registered in the model presenting unstable occlusal contacts when the anterior teeth were in occlusion (FEM 4). These findings may explain mandibular incisors crowding and maxillary incisors flaring as a result of small variations in dental contacts.

  7. Studies of the non-axisymmetric plasma boundary displacement in JET in presence of externally applied magnetic field

    NASA Astrophysics Data System (ADS)

    Yadykin, D.; Frassinetti, L.; Delabie, E.; Chapman, I. T.; Gerasimov, S.; Kempenaars, M.; Rimini, F. G.; Contributors, JET

    2015-10-01

    Non-axisymmetric plasma boundary displacement is caused by the application of the external magnetic field with low toroidal mode number. Such displacement affects edge stability, power load on the first wall and could affect efficiency of the ICRH coupling in ITER. Studies of the displacement are presented for JET tokamak focusing on the interaction between error field correction coils (EFCCs) and shape control system. First results are shown on the direct measurement of the plasma boundary displacement at different toroidal locations. Both qualitative and quantitative studies of the plasma boundary displacement caused by interaction between EFCCs and shape control system are performed for different toroidal phases of the external field. Axisymmetric plasma boundary displacement caused by the EFCC/shape control system interaction is seen for certain phase values of the external field. The value of axisymmetric plasma boundary displacement caused by interaction can be comparable to the non-axisymmetric plasma boundary displacement value produced by EFCCs.

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

    SciTech Connect

    Lanfranfo, Giobatta; Fast, James; /Fermilab

    2001-07-01

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

  9. FIELD TRIALS OF NEWLY DEVELOPED POSITIVE DISPLACEMENT SUBMERSIBLE PUMP

    SciTech Connect

    Rob Beard

    2003-10-01

    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.

  10. Field performance of the Walker Branch throughfall displacement experiment

    SciTech Connect

    Hanson, P.J.; Todd, D.E.; Edwards, N.T.; Huston, M.A.

    1994-10-06

    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.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  12. Moire measurements of the displacement field of a wall under dynamic load

    NASA Astrophysics Data System (ADS)

    Hack, Erwin K.

    1994-03-01

    Attached-grating moire was used to measure the displacement field of a wall that was sheared with both constant and cyclic load and, in a subsequent experiment, was deformed by a perpendicular load. A moire grid of large size (2 X 3 m2) was realized on the object surface. With its aid, the shear component in plane and one component of the out-of-plane displacement field, respectively, were determined by a phase shift algorithm. The results are compared to photogrammetric 3D data that were taken simultaneously. The calibration is discussed. We sketch the influence of phase errors and propose an algorithm to correct for them.

  13. Principal component analysis of dynamic relative displacement fields estimated from MR images.

    PubMed

    Abney, Teresa M; Feng, Yuan; Pless, Robert; Okamoto, Ruth J; Genin, Guy M; Bayly, Philip V

    2011-01-01

    Non-destructive measurement of acceleration-induced displacement fields within a closed object is a fundamental challenge. Inferences of how the brain deforms following skull impact have thus relied largely on indirect estimates and course-resolution cadaver studies. We developed a magnetic resonance technique to quantitatively identify the modes of displacement of an accelerating soft object relative to an object enclosing it, and applied it to study acceleration-induced brain deformation in human volunteers. We show that, contrary to the prevailing hypotheses of the field, the dominant mode of interaction between the brain and skull in mild head acceleration is one of sliding arrested by meninges.

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    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.

  15. On the reach of perturbative descriptions for dark matter displacement fields

    SciTech Connect

    Baldauf, Tobias; Zaldarriaga, Matias; Schaan, Emmanuel E-mail: eschaan@astro.princeton.edu

    2016-03-01

    We study Lagrangian Perturbation Theory (LPT) and its regularization in the Effective Field Theory (EFT) approach. We evaluate the LPT displacement with the same phases as a corresponding N-body simulation, which allows us to compare perturbation theory to the non-linear simulation with significantly reduced cosmic variance, and provides a more stringent test than simply comparing power spectra. We reliably detect a non-vanishing leading order EFT coefficient and a stochastic displacement term, uncorrelated with the LPT terms. This stochastic term is expected in the EFT framework, and, to the best of our understanding, is not an artifact of numerical errors or transients in our simulations. This term constitutes a limit to the accuracy of perturbative descriptions of the displacement field and its phases, corresponding to a 1% error on the non-linear power spectrum at k = 0.2 h{sup −1}Mpc at z = 0. Predicting the displacement power spectrum to higher accuracy or larger wavenumbers thus requires a model for the stochastic displacement.

  16. Displacement field for an edge dislocation in a layered half-space

    USGS Publications Warehouse

    Savage, J.C.

    1998-01-01

    The displacement field for an edge dislocation in an Earth model consisting of a layer welded to a half-space of different material is found in the form of a Fourier integral following the method given by Weeks et al. [1968]. There are four elementary solutions to be considered: the dislocation is either in the half-space or the layer and the Burgers vector is either parallel or perpendicular to the layer. A general two-dimensional solution for a dip-slip faulting or dike injection (arbitrary dip) can be constructed from a superposition of these elementary solutions. Surface deformations have been calculated for an edge dislocation located at the interface with Burgers vector inclined 0??, 30??, 60??, and 90?? to the interface for the case where the rigidity of the layer is half of that of the half-space and the Poisson ratios are the same. Those displacement fields have been compared to the displacement fields generated by similarly situated edge dislocations in a uniform half-space. The surface displacement field produced by the edge dislocation in the layered half-space is very similar to that produced by an edge dislocation at a different depth in a uniform half-space. In general, a low-modulus (high-modulus) layer causes the half-space equivalent dislocation to appear shallower (deeper) than the actual dislocation in the layered half-space.

  17. Modified Savart polariscope with wide field of view and achromatic lateral displacement

    NASA Astrophysics Data System (ADS)

    Quan, Naicheng; Zhang, Chunmin; Mu, Tingkui

    2017-01-01

    A modified Savart polariscope with wide field of view and achromatic lateral displacement is presented. The modified Savart polariscope can be made from two different birefringent crystal materials. The principle of the element is described and the impacts of systematic errors are analyzed. The achievement and performance of the modified Savart polariscope is demonstrated with numerical simulations. The maximum acceptable angle of incidence can be increased by an order of magnitude and the chromatic variations in lateral displacement are inhibited obviously across the specified spectral range 0.4 μm to 0.9 μm.

  18. Electrohydrodynamic Displacement of Polarizable Liquid Interfaces in an Alternating Current Electric Field

    NASA Astrophysics Data System (ADS)

    Gagnon, Zachary

    2015-11-01

    In this work, we investigate Maxwell-Wagner polarization at electrically polarizable liquid interfaces. An AC electric field is applied across a liquid electrical interface created between two co-flowing microfluidic fluid streams with different electrical properties. When potentials as low as 2 volts are applied, we observe a frequency dependent interfacial displacement that is dependent on the relative differences in the electrical conductivity and dielectric constant between the two liquids. At low frequency this deflection is dependent on electrical conductivity, and only depends on dielectric constant at high frequency. At intermediate frequencies, we observe a crossover that is independent of applied voltage, sensitive to both fluid electrical properties, and where no displacement is observed. An analytical polarization model is presented that predicts the liquid interfacial crossover frequency, the dependence of interfacial displacement on liquid electrical conductivity and dielectric constant, and accurately scales the interface displacement measurements. The results show that liquid interfaces are capable of polarizing under AC electric fields and being precisely deflected in a direction and magnitude that is dependent on the applied electric field frequency.

  19. Oxygen Displacement in Cuprates under Ionic Liquid Field-Effect Gating.

    PubMed

    Dubuis, Guy; Yacoby, Yizhak; Zhou, Hua; He, Xi; Bollinger, Anthony T; Pavuna, Davor; Pindak, Ron; Božović, Ivan

    2016-08-31

    We studied structural changes in a 5 unit cell thick La1.96Sr0.04CuO4 film, epitaxially grown on a LaSrAlO4 substrate with a single unit cell buffer layer, when ultra-high electric fields were induced in the film by applying a gate voltage between the film (ground) and an ionic liquid in contact with it. Measuring the diffraction intensity along the substrate-defined Bragg rods and analyzing the results using a phase retrieval method we obtained the three-dimensional electron density in the film, buffer layer, and topmost atomic layers of the substrate under different applied gate voltages. The main structural observations were: (i) there were no structural changes when the voltage was negative, holes were injected into the film making it more metallic and screening the electric field; (ii) when the voltage was positive, the film was depleted of holes becoming more insulating, the electric field extended throughout the film, the partial surface monolayer became disordered, and equatorial oxygen atoms were displaced towards the surface; (iii) the changes in surface disorder and the oxygen displacements were both reversed when a negative voltage was applied; and (iv) the c-axis lattice constant of the film did not change in spite of the displacement of equatorial oxygen atoms.

  20. Oxygen Displacement in Cuprates under IonicLiquid Field-Effect Gating

    SciTech Connect

    Dubuis, Guy; Yacoby, Yizhak; Zhou, Hua; He, Xi; Bollinger, Anthony T.; Pavuna, Davor; Pindak, Ron; Bozovic, Ivan

    2016-08-15

    We studied structural changes in a 5 unit cell thick La1.96Sr0.04CuO4 film, epitaxially grown on a LaSrAlO4 substrate with a single unit cell buffer layer, when ultra-high electric fields were induced in the film by applying a gate voltage between the film and an ionic liquid in contact with it. Measuring the diffraction intensity along the substrate-defined Bragg rods and analyzing the results using a phase retrieval method we obtained the three-dimensional electron density in the film, buffer layer, and topmost atomic layers of the substrate under different applied gate voltages. The main structural observations were: (i) there were no structural changes when the voltage was negative, holes were injected into the film making it more metallic and screening the electric field; (ii) when the voltage was positive, the film was depleted of holes becoming more insulating, the electric field extended throughout the film, the partial surface monolayer became disordered, and planar oxygen atoms were displaced towards the sample surface; (iii) the changes in surface disorder and the oxygen displacements were both reversed when a negative voltage was applied; and (iv) the c-axis lattice constant of the film did not change in spite of the displacement of planar oxygen atoms.

  1. Oxygen Displacement in Cuprates under IonicLiquid Field-Effect Gating

    DOE PAGES

    Dubuis, Guy; Yacoby, Yizhak; Zhou, Hua; ...

    2016-08-15

    We studied structural changes in a 5 unit cell thick La1.96Sr0.04CuO4 film, epitaxially grown on a LaSrAlO4 substrate with a single unit cell buffer layer, when ultra-high electric fields were induced in the film by applying a gate voltage between the film and an ionic liquid in contact with it. Measuring the diffraction intensity along the substrate-defined Bragg rods and analyzing the results using a phase retrieval method we obtained the three-dimensional electron density in the film, buffer layer, and topmost atomic layers of the substrate under different applied gate voltages. The main structural observations were: (i) there were nomore » structural changes when the voltage was negative, holes were injected into the film making it more metallic and screening the electric field; (ii) when the voltage was positive, the film was depleted of holes becoming more insulating, the electric field extended throughout the film, the partial surface monolayer became disordered, and planar oxygen atoms were displaced towards the sample surface; (iii) the changes in surface disorder and the oxygen displacements were both reversed when a negative voltage was applied; and (iv) the c-axis lattice constant of the film did not change in spite of the displacement of planar oxygen atoms.« less

  2. Oxygen Displacement in Cuprates under Ionic Liquid Field-Effect Gating

    NASA Astrophysics Data System (ADS)

    Dubuis, Guy; Yacoby, Yizhak; Zhou, Hua; He, Xi; Bollinger, Anthony T.; Pavuna, Davor; Pindak, Ron; Božović, Ivan

    2016-08-01

    We studied structural changes in a 5 unit cell thick La1.96Sr0.04CuO4 film, epitaxially grown on a LaSrAlO4 substrate with a single unit cell buffer layer, when ultra-high electric fields were induced in the film by applying a gate voltage between the film (ground) and an ionic liquid in contact with it. Measuring the diffraction intensity along the substrate-defined Bragg rods and analyzing the results using a phase retrieval method we obtained the three-dimensional electron density in the film, buffer layer, and topmost atomic layers of the substrate under different applied gate voltages. The main structural observations were: (i) there were no structural changes when the voltage was negative, holes were injected into the film making it more metallic and screening the electric field; (ii) when the voltage was positive, the film was depleted of holes becoming more insulating, the electric field extended throughout the film, the partial surface monolayer became disordered, and equatorial oxygen atoms were displaced towards the surface; (iii) the changes in surface disorder and the oxygen displacements were both reversed when a negative voltage was applied; and (iv) the c-axis lattice constant of the film did not change in spite of the displacement of equatorial oxygen atoms.

  3. Oxygen Displacement in Cuprates under Ionic Liquid Field-Effect Gating

    PubMed Central

    Dubuis, Guy; Yacoby, Yizhak; Zhou, Hua; He, Xi; Bollinger, Anthony T.; Pavuna, Davor; Pindak, Ron; Božović, Ivan

    2016-01-01

    We studied structural changes in a 5 unit cell thick La1.96Sr0.04CuO4 film, epitaxially grown on a LaSrAlO4 substrate with a single unit cell buffer layer, when ultra-high electric fields were induced in the film by applying a gate voltage between the film (ground) and an ionic liquid in contact with it. Measuring the diffraction intensity along the substrate-defined Bragg rods and analyzing the results using a phase retrieval method we obtained the three-dimensional electron density in the film, buffer layer, and topmost atomic layers of the substrate under different applied gate voltages. The main structural observations were: (i) there were no structural changes when the voltage was negative, holes were injected into the film making it more metallic and screening the electric field; (ii) when the voltage was positive, the film was depleted of holes becoming more insulating, the electric field extended throughout the film, the partial surface monolayer became disordered, and equatorial oxygen atoms were displaced towards the surface; (iii) the changes in surface disorder and the oxygen displacements were both reversed when a negative voltage was applied; and (iv) the c-axis lattice constant of the film did not change in spite of the displacement of equatorial oxygen atoms. PMID:27578237

  4. Uncertainty of InSAR velocity fields for measuring long-wavelength displacement

    NASA Astrophysics Data System (ADS)

    Fattahi, H.; Amelung, F.

    2014-12-01

    Long-wavelength artifacts in InSAR data are the main limitation to measure long-wavelength displacement; they are traditionally attributed mainly to the inaccuracy of the satellite orbits (orbital errors). However, most satellites are precisely tracked resulting in uncertainties of orbits of 2-10 cm. Orbits of these satellites are thus precise enough to obtain precise velocity fields with uncertainties better than 1 mm/yr/100 km for older satellites (e.g. Envisat) and better than 0.2 mm/yr/100 km for modern satellites (e.g. TerraSAR-X and Sentinel-1) [Fattahi & Amelung, 2014]. Such accurate velocity fields are achievable if long-wavelength artifacts from sources other than orbital errors are identified and corrected for. We present a modified Small Baseline approach to measure long-wavelength deformation and evaluate the uncertainty of these measurements. We use a redundant network of interferograms for detection and correction of unwrapping errors to ensure the unbiased estimation of phase history. We distinguish between different sources of long-wavelength artifacts and correct those introduced by atmospheric delay, topographic residuals, timing errors, processing approximations and hardware issues. We evaluate the uncertainty of the velocity fields using a covariance matrix with the contributions from orbital errors and residual atmospheric delay. For contributions from the orbital errors we consider the standard deviation of velocity gradients in range and azimuth directions as a function of orbital uncertainty. For contributions from the residual atmospheric delay we use several approaches including the structure functions of InSAR time-series epochs, the predicted delay from numerical weather models and estimated wet delay from optical imagery. We validate this InSAR approach for measuring long-wavelength deformation by comparing InSAR velocity fields over ~500 km long swath across the southern San Andreas fault system with independent GPS velocities and

  5. The displacement field in the vibration analysis of laminated thick plates

    SciTech Connect

    Ohta, Yoshiki; Narita, Yoshihiro

    1995-11-01

    The present paper discusses the assumption of displacement fields used in the vibration analysis of FRP laminated thick plates. For this purpose, the strain and kinetic energies of a FRP cross-ply laminated plate are evaluated analytically based on the three-dimensional theory of elasticity, and the displacements of the rectangular plate, which are simply-supported at all edges, are expanded into the polynomial forms with respect to thickness coordinate. A frequency equation is formulated by using the energy method minimizing the Lagrange function. In the numerical calculations, natural frequencies are obtained for the plates with various stacking sequence and the thickness ratios, and the validity of the assumption of displacement fields and the range of applicability of the various plate theories (e.g. the Classical Plate Theory (CPT), the First-Order Shear Deformation Theory (FSDT) and the Higher-Order Shear Deformation Theory (HSDT)), which are widely used in the vibration analysis of FRP laminated plates, to the laminated thick plates are discussed by comparing the present results with the CPT and the FSDT solutions.

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

    SciTech Connect

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

    2015-04-24

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

  7. Late Cenozoic displacement-field partitioning in the western Great Basin

    SciTech Connect

    Oldow, J.S. . Dept. of Geology and Geophysics)

    1993-04-01

    Late Cenozoic (15 Ma to recent) structures in the western Great Basin record a complex history of extension and transcurrent faulting that reflect displacement-field partitioning and migration of a deformation front outward from the center of the province. The location and morphology of late Cenozoic structures were strongly influenced by the pre-Tertiary crustal architecture of western Nevada and eastern California formed during continental rifting and subsequent active margin tectonism. Late Cenozoic displacements are spatially partitioned components of N55[degree]W regional extension. Within the Great Basin, a central domino of uniform extension (N55[degree]W) is bound on the west by a broad northwest-trending zone of transtension, the Walker Lane Belt (WLB). Central domain extension is accommodated by north-northeast half-grabens that initiated in the mid-Miocene in central Nevada and in the Mio-Pliocene in north west Nevada. Transtension in the WLB is characterized by coeval displacements on oblique-slip faults of various orientations and right-slip on northwest transcurrent faults. As in the central domain, the locus of activity migrated westerly with time in the WLB. The present-day extension axis for oblique-slip faults in the western Great Basin changes stepwise from N55[degree]W, to N75[degree]W, to N75[degree]E as the WLB and Sierra Nevada are approached from the east. The change in extension direction is viewed as the product of displacement field partitioning and not as the result of regional stress variation.

  8. Combining displacement field and grip force information to determine mechanical properties of planar tissue with complicated geometry.

    PubMed

    Nagel, Tina M; Hadi, Mohammad F; Claeson, Amy A; Nuckley, David J; Barocas, Victor H

    2014-11-01

    Performing planar biaxial testing and using nominal stress-strain curves for soft-tissue characterization is most suitable when (1) the test produces homogeneous strain fields, (2) fibers are aligned with the coordinate axes, and (3) strains are measured far from boundaries. Some tissue types [such as lamellae of the annulus fibrosus (AF)] may not allow for these conditions to be met due to their natural geometry and constitution. The objective of this work was to develop and test a method utilizing a surface displacement field, grip force-stretch data, and finite-element (FE) modeling to facilitate analysis of such complex samples. We evaluated the method by regressing a simple structural model to simulated and experimental data. Three different tissues with different characteristics were used: Superficial pectoralis major (SPM) (anisotropic, aligned with axes), facet capsular ligament (FCL) (anisotropic, aligned with axes, bone attached), and a lamella from the AF (anisotropic, aligned off-axis, bone attached). We found that the surface displacement field or the grip force-stretch data information alone is insufficient to determine a unique parameter set. Utilizing both data types provided tight confidence regions (CRs) of the regressed parameters and low parameter sensitivity to initial guess. This combined fitting approach provided robust characterization of tissues with varying fiber orientations and boundaries and is applicable to tissues that are poorly suited to standard biaxial testing. The structural model, a set of C++ finite-element routines, and a Matlab routine to do the fitting based on a set of force/displacement data is provided in the on-line supplementary material.

  9. Possibility of unlimited shear displacement due to sliding-surface-liquefaction of MH gasification and long runout submarine landslides

    NASA Astrophysics Data System (ADS)

    Tsukui, A.; Fukuoka, H.; Yamasaki, S.

    2012-04-01

    : Above-mentioned sliding-surface-liquefaction in the sand - dry ice mixture supports the possibility of similar accelerating and unlimited displacement in the sand-MH mixture or boundaries between MH and sand layer induced by certain strong ground motion under sea floor. To simulate the earthquake-induced submarine landslides due to gasification of MH, authors applied the simple sine-curve cyclic loading to the sand-dry ice sample. After certain number of cyclic loading, sliding surface liquefaction appeared. When the mobilized shear resistance reduced by such excess pore pressure becomes smaller than the shear stress, accelerating behavior and unlimited shear displacement could be expected. Thus, MH still has high possibility to cause gigantic submarine landslides under certain strong earthquake condition.

  10. Magnetostriction of a sphere: stress development during magnetization and residual stresses due to the remanent field

    NASA Astrophysics Data System (ADS)

    Reich, Felix A.; Rickert, Wilhelm; Stahn, Oliver; Müller, Wolfgang H.

    2016-12-01

    Based on the principles of rational continuum mechanics and electrodynamics (see Truesdell and Toupin in Handbuch der Physik, Springer, Berlin, 1960 or Kovetz in Electromagnetic theory, Oxford University Press, Oxford, 2000), we present closed-form solutions for the mechanical displacements and stresses of two different magnets. Both magnets are initially of spherical shape. The first (hard) magnet is uniformly magnetized and deforms due to the field induced by the magnetization. In the second problem of a (soft) linear-magnetic sphere, the deformation is caused by an applied external field, giving rise to magnetization. Both problems can be used for modeling parts of general magnetization processes. We will address the similarities between both settings in context with the solutions for the stresses and displacements. In both problems, the volumetric uc(Lorentz) force density vanishes. However, a uc(Lorentz) surface traction is present. This traction is determined from the magnetic flux density. Since the obtained displacements and stresses are small in magnitude, we may use uc(Hooke's) law with a small-strain approximation, resulting in the uc(Lamé)-uc(Navier) equations of linear elasticity theory. If gravity is neglected and azimuthal symmetry is assumed, these equations can be solved in terms of a series. This has been done by uc(Hiramatsu) and uc(Oka) (Int J Rock Mech Min Sci Geomech Abstr 3(2):89-90, 1966) before. We make use of their series solution for the displacements and the stresses and expand the uc(Lorentz) tractions of the analyzed problems suitably in order to find the expansion coefficients. The resulting algebraic system yields finite numbers of nonvanishing coefficients. Finally, the resulting stresses, displacements, principal strains and the uc(Lorentz) tractions are illustrated and discussed.

  11. Magnetostriction of a sphere: stress development during magnetization and residual stresses due to the remanent field

    NASA Astrophysics Data System (ADS)

    Reich, Felix A.; Rickert, Wilhelm; Stahn, Oliver; Müller, Wolfgang H.

    2017-03-01

    Based on the principles of rational continuum mechanics and electrodynamics (see Truesdell and Toupin in Handbuch der Physik, Springer, Berlin, 1960 or Kovetz in Electromagnetic theory, Oxford University Press, Oxford, 2000), we present closed-form solutions for the mechanical displacements and stresses of two different magnets. Both magnets are initially of spherical shape. The first (hard) magnet is uniformly magnetized and deforms due to the field induced by the magnetization. In the second problem of a (soft) linear-magnetic sphere, the deformation is caused by an applied external field, giving rise to magnetization. Both problems can be used for modeling parts of general magnetization processes. We will address the similarities between both settings in context with the solutions for the stresses and displacements. In both problems, the volumetric Lorentz force density vanishes. However, a Lorentz surface traction is present. This traction is determined from the magnetic flux density. Since the obtained displacements and stresses are small in magnitude, we may use Hooke's law with a small-strain approximation, resulting in the Lamé- Navier equations of linear elasticity theory. If gravity is neglected and azimuthal symmetry is assumed, these equations can be solved in terms of a series. This has been done by Hiramatsu and Oka (Int J Rock Mech Min Sci Geomech Abstr 3(2):89-90, 1966) before. We make use of their series solution for the displacements and the stresses and expand the Lorentz tractions of the analyzed problems suitably in order to find the expansion coefficients. The resulting algebraic system yields finite numbers of nonvanishing coefficients. Finally, the resulting stresses, displacements, principal strains and the Lorentz tractions are illustrated and discussed.

  12. Extension of the Optimized Virtual Fields Method to estimate viscoelastic material parameters from 3D dynamic displacement fields

    PubMed Central

    Connesson, N.; Clayton, E.H.; Bayly, P.V.; Pierron, F.

    2015-01-01

    In-vivo measurement of the mechanical properties of soft tissues is essential to provide necessary data in biomechanics and medicine (early cancer diagnosis, study of traumatic brain injuries, etc.). Imaging techniques such as Magnetic Resonance Elastography (MRE) can provide 3D displacement maps in the bulk and in vivo, from which, using inverse methods, it is then possible to identify some mechanical parameters of the tissues (stiffness, damping etc.). The main difficulties in these inverse identification procedures consist in dealing with the pressure waves contained in the data and with the experimental noise perturbing the spatial derivatives required during the processing. The Optimized Virtual Fields Method (OVFM) [1], designed to be robust to noise, present natural and rigorous solution to deal with these problems. The OVFM has been adapted to identify material parameter maps from Magnetic Resonance Elastography (MRE) data consisting of 3-dimensional displacement fields in harmonically loaded soft materials. In this work, the method has been developed to identify elastic and viscoelastic models. The OVFM sensitivity to spatial resolution and to noise has been studied by analyzing 3D analytically simulated displacement data. This study evaluates and describes the OVFM identification performances: different biases on the identified parameters are induced by the spatial resolution and experimental noise. The well-known identification problems in the case of quasi-incompressible materials also find a natural solution in the OVFM. Moreover, an a posteriori criterion to estimate the local identification quality is proposed. The identification results obtained on actual experiments are briefly presented. PMID:26146416

  13. The magnetic field due to a number of toroidal conductors

    NASA Astrophysics Data System (ADS)

    Caldwell, J.

    1982-03-01

    This is an extension of the work carried out by Gibson and Caldwell on the optimization of the uniformity of the magnetic field produced in the bore of a toroidal conductor of rectangular cross section. In this paper the work is extended to consider the magnetic field due to a number of conductors. The usefulness of the work is assessed by comparing it to the work of Garrett, and numerical results are given for particular coil parameters.

  14. Electric field gradient and mean square displacement of iron sites in cubic iron sulphide

    NASA Astrophysics Data System (ADS)

    Garg, V. K.

    1981-01-01

    Mössbauer absorption of Fe57, for four equivalent but differently oriented sites, in naturally occuring single crystals of FeS2 (pyrite) has been studied as a function of the orientation of the crystal axes with respect to the γ-ray beam from a Co57/Pd source. Polarization effects for our absorbers of ˜0.1 mm thickness were found not to be appreciable. Experimental peak area ratio of ˜1 in the case of powdered absorber and monocrystalline absorbers in (111), (110), and (100) planes has been analyzed to obtain the principal axes of the electric-field-gradient and the mean-square displacement as ‖1,1,1‖, ‖-1,1,1‖, ‖1,1,-1‖, and ‖1,-1,1‖ direction for the Fe sites corresponding to 000, 1/2 1/2 0, 1/2 0 1/2 , and 0 1/2 1/2, respectively. The angular independent recoilless fraction at 298 K has been obtained to be 0.20±0.02 and for the mean-square displacement =< y2>=, and its value at 298 K is 4.34±0.23×10-19 cm2.

  15. Effect of Strain Field on Threshold Displacement Energy of Tungsten Studied by Molecular Dynamics Simulation

    SciTech Connect

    Wang, Dong; Gao, Ning; Setyawan, W.; Kurtz, R. J.; Wang, Zhi-Guang; Gao, Xing; He, Wen-Hao; Pang, Li-Long

    2016-09-01

    The influence of strain field on defect formation energy and threshold displacement energy (Ed) in body-centered cubic (BCC) tungsten (W) has been studied with molecular dynamics simulations. Two different W potentials (Fikar and Juslin) were compared and the results indicate that the connection distance and selected function linking the short-range and long-range portions of the potentials affects the threshold displacement energy and its direction-specific values. The minimum Ed direction calculated with the Fikar-potential is <100> and with the Juslin-potential is <111>. Nevertheless, the most stable self-interstitial configuration is found to be a <111>-crowdion for both potentials. This stable configuration does not change with applied strain. Varying the strain from compression to tension increases the vacancy formation energy but decreases the self-interstitial formation energy. The formation energy of a self-interstitial changes more significantly than a vacancy such that Ed decreases with applied hydrostatic strain from compression to tension.

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

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  17. Detection of Alzheimer’s disease by displacement field and machine learning

    PubMed Central

    Wang, Shuihua

    2015-01-01

    Aim. Alzheimer’s disease (AD) is a chronic neurodegenerative disease. Recently, computer scientists have developed various methods for early detection based on computer vision and machine learning techniques. Method. In this study, we proposed a novel AD detection method by displacement field (DF) estimation between a normal brain and an AD brain. The DF was treated as the AD-related features, reduced by principal component analysis (PCA), and finally fed into three classifiers: support vector machine (SVM), generalized eigenvalue proximal SVM (GEPSVM), and twin SVM (TSVM). The 10-fold cross validation repeated 50 times. Results. The results showed the “DF + PCA + TSVM” achieved the accuracy of 92.75 ± 1.77, sensitivity of 90.56 ± 1.15, specificity of 93.37 ± 2.05, and precision of 79.61 ± 2.21. This result is better than or comparable with not only the other proposed two methods, but also ten state-of-the-art methods. Besides, our method discovers the AD is related to following brain regions disclosed in recent publications: Angular Gyrus, Anterior Cingulate, Cingulate Gyrus, Culmen, Cuneus, Fusiform Gyrus, Inferior Frontal Gyrus, Inferior Occipital Gyrus, Inferior Parietal Lobule, Inferior Semi-Lunar Lobule, Inferior Temporal Gyrus, Insula, Lateral Ventricle, Lingual Gyrus, Medial Frontal Gyrus, Middle Frontal Gyrus, Middle Occipital Gyrus, Middle Temporal Gyrus, Paracentral Lobule, Parahippocampal Gyrus, Postcentral Gyrus, Posterior Cingulate, Precentral Gyrus, Precuneus, Sub-Gyral, Superior Parietal Lobule, Superior Temporal Gyrus, Supramarginal Gyrus, and Uncus. Conclusion. The displacement filed is effective in detection of AD and related brain-regions. PMID:26401461

  18. Flow damping due to stochastization of the magnetic field

    PubMed Central

    Ida, K.; Yoshinuma, M.; Tsuchiya, H.; Kobayashi, T.; Suzuki, C.; Yokoyama, M.; Shimizu, A.; Nagaoka, K.; Inagaki, S.; Itoh, K.; Akiyama, T.; Emoto, M.; Evans, T.; Dinklage, A.; Du, X.; Fujii, K.; Goto, M.; Goto, T.; Hasuo, M.; Hidalgo, C.; Ichiguchi, K.; Ishizawa, A.; Jakubowski, M.; Kamiya, K.; Kasahara, H.; Kawamura, G.; Kato, D.; Kobayashi, M.; Morita, S.; Mukai, K.; Murakami, I.; Murakami, S.; Narushima, Y.; Nunami, M.; Ohdach, S.; Ohno, N.; Osakabe, M.; Pablant, N.; Sakakibara, S.; Seki, T.; Shimozuma, T.; Shoji, M.; Sudo, S.; Tanaka, K.; Tokuzawa, T.; Todo, Y.; Wang, H.; Yamada, H.; Takeiri, Y.; Mutoh, T.; Imagawa, S.; Mito, T.; Nagayama, Y.; Watanabe, K. Y.; Ashikawa, N.; Chikaraishi, H.; Ejiri, A.; Furukawa, M.; Fujita, T.; Hamaguchi, S.; Igami, H.; Isobe, M.; Masuzaki, S.; Morisaki, T.; Motojima, G.; Nagasaki, K.; Nakano, H.; Oya, Y.; Suzuki, Y.; Sakamoto, R.; Sakamoto, M.; Sanpei, A.; Takahashi, H.; Tokitani, M.; Ueda, Y.; Yoshimura, Y.; Yamamoto, S.; Nishimura, K.; Sugama, H.; Yamamoto, T.; Idei, H.; Isayama, A.; Kitajima, S.; Masamune, S.; Shinohara, K.; Bawankar, P. S.; Bernard, E.; von Berkel, M.; Funaba, H.; Huang, X. L.; Ii, T.; Ido, T.; Ikeda, K.; Kamio, S.; Kumazawa, R.; Moon, C.; Muto, S.; Miyazawa, J.; Ming, T.; Nakamura, Y.; Nishimura, S.; Ogawa, K.; Ozaki, T.; Oishi, T.; Ohno, M.; Pandya, S.; Seki, R.; Sano, R.; Saito, K.; Sakaue, H.; Takemura, Y.; Tsumori, K.; Tamura, N.; Tanaka, H.; Toi, K.; Wieland, B.; Yamada, I.; Yasuhara, R.; Zhang, H.; Kaneko, O.; Komori, A.

    2015-01-01

    The driving and damping mechanism of plasma flow is an important issue because flow shear has a significant impact on turbulence in a plasma, which determines the transport in the magnetized plasma. Here we report clear evidence of the flow damping due to stochastization of the magnetic field. Abrupt damping of the toroidal flow associated with a transition from a nested magnetic flux surface to a stochastic magnetic field is observed when the magnetic shear at the rational surface decreases to 0.5 in the large helical device. This flow damping and resulting profile flattening are much stronger than expected from the Rechester–Rosenbluth model. The toroidal flow shear shows a linear decay, while the ion temperature gradient shows an exponential decay. This observation suggests that the flow damping is due to the change in the non-diffusive term of momentum transport. PMID:25569268

  19. Comparison of Reduced Displacement Potentials from Spe Free Field Measurements: SPE-4PRIME Versus Previous Events

    NASA Astrophysics Data System (ADS)

    Patton, H. J.; Rougier, E.

    2015-12-01

    Since 2010, the U. S. Department of Energy has funded a series of chemical tests at the National Nuclear Security Site (NNSS) in Climax Stock granite as part of the Source Physics Experiment (SPE) with the aim of gaining a better understanding of the generation and propagation of seismic energy from underground explosions in hard rock media. To date, four tests have been conducted in the same borehole with yields of 100, 1000, 900 and 100 kg at different depths of burials. The nominal scaled depths of burial are 938, 363, 376 and 1556 m/kt1/3 compared to standard containment practices of ~120 m/kt1/3. A quite dense array of free field accelerometers were installed around the borehole, both on and off shot depth. Acceleration data were corrected for shock-generated baseline-shifts, and free field ground velocity waveforms were obtained. This work concentrates on the qualitative analysis of the reduced displacement potentials and the explosion source spectra for the last shot of the series (SPE-4Prime) and the comparison of the obtained results against the previous events. Finally, the results obtained from the experimental data are compared to the Mueller-Murphy empirical explosion model both using the Heard and Ackerman and Denny and Johnson cavity radius scaling laws.

  20. Tune Variations due to Septum Stray Field F. Pederson &

    SciTech Connect

    Rinolfi, L.

    1986-10-12

    Two types of antiproton instabilities due to trapped ions are harmful in the AA. One is a coherent instability occurring when an ion pocket resonates with a 3-Q mode (hiccups), the other is excitation of 11th and 15th order non-linear resonances due to the non-linear focusing fields from localized ion clouds trapped in uncleared potential well pockets. Accumulation with a good injection yield of antiprotons forces us to locate the tune of the dense core in the general area of the array of 15th order resonances. To avoid harmful blow-up of the dense core the tune is located between the resonances 11Q{sub H} + 4Q{sub V} = 34, 10Q{sub H} + 5Q{sub V} = 34, and 11Q{sub H} = 25, requiring a tune of Q{sub H} = 2.2722 to be maintained with a precision of a few 10{sup -4} (Fig. 4). Different angles of the injection and ejection trajectories require the septum current to be changed from 3860 A during accumulation to 3920 A, during ejection mode. Variations in the septum stray field due to these changes in current cause tune changes in the order of 10{sup -3}. In addition, at a given septum current, a pronounced hysteresis of the stray field causes tune variations of about the same order of magnitude, so also the past history of the septum excitation must be carefully controlled to obtain a reproducible tune.

  1. Biological effects due to weak magnetic field on plants

    NASA Astrophysics Data System (ADS)

    Belyavskaya, N. A.

    2004-01-01

    Throughout the evolution process, Earth's magnetic field (MF, about 50 μT) 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

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

    NASA Technical Reports Server (NTRS)

    Maggiori, D.

    1981-01-01

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

  3. Polymorphism of iron at high pressure: A 3D phase-field model for displacive transitions with finite elastoplastic deformations

    NASA Astrophysics Data System (ADS)

    Vattré, A.; Denoual, C.

    2016-07-01

    A thermodynamically consistent framework for combining nonlinear elastoplasticity and multivariant phase-field theory is formulated at large strains. In accordance with the Clausius-Duhem inequality, the Helmholtz free energy and time-dependent constitutive relations give rise to displacive driving forces for pressure-induced martensitic phase transitions in materials. Inelastic forces are obtained by using a representation of the energy landscape that involves the concept of reaction pathways with respect to the point group symmetry operations of crystal lattices. On the other hand, additional elastic forces are derived for the most general case of large strains and rotations, as well as nonlinear, anisotropic, and different elastic pressure-dependent properties of phases. The phase-field formalism coupled with finite elastoplastic deformations is implemented into a three-dimensional Lagrangian finite element approach and is applied to analyze the iron body-centered cubic (α-Fe) into hexagonal close-packed (ɛ-Fe) phase transitions under high hydrostatic compression. The simulations exhibit the major role played by the plastic deformation in the morphological and microstructure evolution processes. Due to the strong long-range elastic interactions between variants without plasticity, a forward α → ɛ transition is energetically unfavorable and remains incomplete. However, plastic dissipation releases considerably the stored strain energy, leading to the α ↔ ɛ ↔α‧ (forward and reverse) polymorphic phase transformations with an unexpected selection of variants.

  4. On the Vertigo Due to Static Magnetic Fields

    PubMed Central

    Mian, Omar S.; Li, Yan; Antunes, Andre; Glover, Paul M.; Day, Brian L.

    2013-01-01

    Vertigo is sometimes experienced in and around MRI scanners. Mechanisms involving stimulation of the vestibular system by movement in magnetic fields or magnetic field spatial gradients have been proposed. However, it was recently shown that vestibular-dependent ocular nystagmus is evoked when stationary in homogenous static magnetic fields. The proposed mechanism involves Lorentz forces acting on endolymph to deflect semicircular canal (SCC) cupulae. To investigate whether vertigo arises from a similar mechanism we recorded qualitative and quantitative aspects of vertigo and 2D eye movements from supine healthy adults (n = 25) deprived of vision while pushed into the 7T static field of an MRI scanner. Exposures were variable and included up to 135s stationary at 7T. Nystagmus was mainly horizontal, persisted during long-exposures with partial decline, and reversed upon withdrawal. The dominant vertiginous perception with the head facing up was rotation in the horizontal plane (85% incidence) with a consistent direction across participants. With the head turned 90 degrees in yaw the perception did not transform into equivalent vertical plane rotation, indicating a context-dependency of the perception. During long exposures, illusory rotation lasted on average 50 s, including 42 s whilst stationary at 7T. Upon withdrawal, perception re-emerged and reversed, lasting on average 30 s. Onset fields for nystagmus and perception were significantly correlated (p<.05). Although perception did not persist as long as nystagmus, this is a known feature of continuous SSC stimulation. These observations, and others in the paper, are compatible with magnetic-field evoked-vertigo and nystagmus sharing a common mechanism. With this interpretation, response decay and reversal upon withdrawal from the field, are due to adaptation to continuous vestibular input. Although the study does not entirely exclude the possibility of mechanisms involving transient vestibular stimulation

  5. On the vertigo due to static magnetic fields.

    PubMed

    Mian, Omar S; Li, Yan; Antunes, Andre; Glover, Paul M; Day, Brian L

    2013-01-01

    Vertigo is sometimes experienced in and around MRI scanners. Mechanisms involving stimulation of the vestibular system by movement in magnetic fields or magnetic field spatial gradients have been proposed. However, it was recently shown that vestibular-dependent ocular nystagmus is evoked when stationary in homogenous static magnetic fields. The proposed mechanism involves Lorentz forces acting on endolymph to deflect semicircular canal (SCC) cupulae. To investigate whether vertigo arises from a similar mechanism we recorded qualitative and quantitative aspects of vertigo and 2D eye movements from supine healthy adults (n = 25) deprived of vision while pushed into the 7T static field of an MRI scanner. Exposures were variable and included up to 135s stationary at 7T. Nystagmus was mainly horizontal, persisted during long-exposures with partial decline, and reversed upon withdrawal. The dominant vertiginous perception with the head facing up was rotation in the horizontal plane (85% incidence) with a consistent direction across participants. With the head turned 90 degrees in yaw the perception did not transform into equivalent vertical plane rotation, indicating a context-dependency of the perception. During long exposures, illusory rotation lasted on average 50 s, including 42 s whilst stationary at 7T. Upon withdrawal, perception re-emerged and reversed, lasting on average 30 s. Onset fields for nystagmus and perception were significantly correlated (p<.05). Although perception did not persist as long as nystagmus, this is a known feature of continuous SSC stimulation. These observations, and others in the paper, are compatible with magnetic-field evoked-vertigo and nystagmus sharing a common mechanism. With this interpretation, response decay and reversal upon withdrawal from the field, are due to adaptation to continuous vestibular input. Although the study does not entirely exclude the possibility of mechanisms involving transient vestibular stimulation

  6. Applying a Bayesian Approach to Identification of Orthotropic Elastic Constants from Full Field Displacement Measurements

    NASA Astrophysics Data System (ADS)

    Gogu, C.; Yin, W.; Haftka, R.; Ifju, P.; Molimard, J.; Le Riche, R.; Vautrin, A.

    2010-06-01

    A major challenge in the identification of material properties is handling different sources of uncertainty in the experiment and the modelling of the experiment for estimating the resulting uncertainty in the identified properties. Numerous improvements in identification methods have provided increasingly accurate estimates of various material properties. However, characterizing the uncertainty in the identified properties is still relatively crude. Different material properties obtained from a single test are not obtained with the same confidence. Typically the highest uncertainty is associated with respect to properties to which the experiment is the most insensitive. In addition, the uncertainty in different properties can be strongly correlated, so that obtaining only variance estimates may be misleading. A possible approach for handling the different sources of uncertainty and estimating the uncertainty in the identified properties is the Bayesian method. This method was introduced in the late 1970s in the context of identification [1] and has been applied since to different problems, notably identification of elastic constants from plate vibration experiments [2]-[4]. The applications of the method to these classical pointwise tests involved only a small number of measurements (typically ten natural frequencies in the previously cited vibration test) which facilitated the application of the Bayesian approach. For identifying elastic constants, full field strain or displacement measurements provide a high number of measured quantities (one measurement per image pixel) and hence a promise of smaller uncertainties in the properties. However, the high number of measurements represents also a major computational challenge in applying the Bayesian approach to full field measurements. To address this challenge we propose an approach based on the proper orthogonal decomposition (POD) of the full fields in order to drastically reduce their dimensionality. POD is

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

    SciTech Connect

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

    1989-08-31

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

  8. Effect of strain field on displacement cascade in tungsten studied by molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Wang, D.; Gao, N.; Wang, Z. G.; Gao, X.; He, W. H.; Cui, M. H.; Pang, L. L.; Zhu, Y. B.

    2016-10-01

    Using atomistic methods, the coupling effect of strain field and displacement cascade in body-centered cubic (BCC) tungsten is directly simulated by molecular dynamics (MD) simulations at different temperatures. The values of the hydrostatic and uniaxial (parallel or perpendicular to primary knock-on atom (PKA) direction) strains are from -2% to 2% and the temperature is from 100 to 1000 K. Because of the annealing effect, the influence of strain on radiation damage at low temperature has been proved to be more significant than that at high temperature. When the cascade proceeds under the hydrostatic strain, the Frenkel Pair (FP) production, the fraction of defect in cluster and the average size of the defect cluster, all increase at tensile state and decrease at compressive state. When the cascade is under uniaxial strain, the effect of strain parallel to PKA direction is less than the effect of hydrostatic strain, while the effect of strain perpendicular to PKA direction can be negligible. Under the uniaxial strain along <1 1 1> direction, the SIA and SIA cluster is observed to orientate along the strain direction at tensile state and the uniaxial compressive strain with direction perpendicular to <1 1 1> has led to the similar preferred nucleation. All these results indicate that under irradiation, the tensile state should be avoided for materials used in nuclear power plants.

  9. Quantitative Analysis of the Displacement of the Anterior Visual Pathway by Pituitary Lesions and the Associated Visual Field Loss

    PubMed Central

    Boland, Michael V.; Lee, In Ho; Zan, Elcin; Yousem, David M.; Miller, Neil R.

    2016-01-01

    Purpose To evaluate quantitatively the relationship between the displacement of anterior visual pathway structures by pituitary tumors and visual field damage with the goal of improving diagnosis and management. Methods Subjects had pituitary macroadenomas and both magnetic resonance imaging (MRI) and static perimetry. Neuroradiologists measured the displacement of anterior visual pathway structures and right–left tumor asymmetry. To quantify the degree and laterality of visual field loss, we used algorithms from the neurologic hemifield test to analyze each right–left pair of visual fields with respect to temporal asymmetry, the proportion of loss that was temporal, total asymmetry, and total damage. We compared these metrics with the displacement of anterior visual pathway structures and tumor asymmetry. Results Of 114 subjects, 64 (56%) were male and the median age was 57 years (range, 14–88). The summation of vision loss in both eyes and the proportion of temporal loss were statistically significantly related to the maximum displacement of the anterior visual pathway (both P < 0.001 for fit of linear regression). The relationship between the asymmetry of visual field loss in the two eyes and the subjective assignment of tumor asymmetry on MRI did not achieve statistical significance (P = 0.06 by analysis of variance). Conclusions Displacement of the anterior visual pathway by pituitary tumors is associated with both the total amount of visual field loss and the proportion of temporal visual field loss. Although there was right–left asymmetry of vision loss in some subjects, it was not related to the subjective assessment of tumor asymmetry. PMID:27388050

  10. Construction of a high-resolution moiré interferometer for investigating microstructural displacement fields in materials.

    PubMed

    Goldrein, H T; Rae, P J; Palmer, S J P; Field, J E

    2002-05-15

    A high-magnification moiré interferometer has been constructed with a spatial resolution of the order of 1 microm to measure the local in-plane displacement field associated with a material's microstructure. Laser illumination passes through phase-stepping optics and is delivered to the microscope head by polarization-preserving single-mode optical fibres. The head itself is a compact unit consisting of collimating optics, an objective lens and a charge coupled device (CCD) camera. Thin-phase gratings are cast onto the sample surface with a compliant epoxy resin and coated with ca. 5 nm of gold to enhance the fringe contrast and reduce speckle noise. By switching between the laser illumination and white-light illumination, the underlying microstructure is viewed in exact registration with the measured displacement fields. The application of the instrument is illustrated here by visualization of displacement fields in polymer-bonded explosives (PBXs) during deformation to failure. PBXs are highly filled polymers consisting of up to 95% by weight crystalline explosive bound in a variety of polymeric binders. The mechanical properties of PBXs are highly dependent on the microstructure, and moiré interferometry is an ideal tool for investigating the relationship between the 1-100 microm sized crystals and the displacement fields. Methods such as this are required if computer models of inhomogeneous materials are to be accurately validated.

  11. Early warning of freshwater salinization due to upward brine displacement by species transport simulations combined with a hydrochemical genesis model

    NASA Astrophysics Data System (ADS)

    Langer, Maria; Kühn, Michael

    2016-04-01

    Shallow groundwater resources could be possibly affected by intruding brines, which are displaced along hydraulically conductive faults as result of subsurface activities like CO2 injection. To avoid salinization of potable freshwater aquifers an early detection of intruding saline water is necessary, especially in regions where an initial geogenic salinization already exists. Our study is based on work of Tillner et al. [1] and Langer et al. [2] who investigated the influence of permeable fault systems on brine displacement for the prospective storage site Beeskow-Birkholz in the Northeast German Basin. With a 3D regional scale model considering the deep groundwater system, they demonstrated that the existence of hydraulically conductive faults is not necessarily an exclusion criterion for potential injection sites, because salinization of shallower aquifers strongly depends on the effective damage zone volume, the initial salinity distribution and overlying reservoirs [2], while permeability of fault zones does not influence salinization of shallower aquifers significantly [1]. Here we extracted a 2D cross section regarding the upper 220 m of the study area mainly represented by shallow freshwater aquifers, but also considering an initial geogenic salinization [3]. We took flow rates of the intruding brines from the previous studies [2] and implemented species transport simulations with the program code SHEMAT [4]. Results are investigated and interpreted with the hydrochemical genesis model GEBAH [5] which has been already applied as early warning of saltwater intrusions into freshwater aquifers and surface water [6]. GEBAH allows a categorization of groundwater by the ion ratios of the dissolved components and offers a first indicative determination for an existence and the intensity of saline water intrusion in shallow groundwater aquifer, independent of the concentration of the solution. With our model we investigated the migration of saline water through a

  12. Displacement Fields and Self-Energies of Circular and Polygonal Dislocation Loops in Homogeneous and Layered Anisotropic Solids

    SciTech Connect

    Gao, Yanfei; Larson, Ben C.

    2015-06-19

    There are large classes of materials problems that involve the solutions of stress, displacement, and strain energy of dislocation loops in elastically anisotropic solids, including increasingly detailed investigations of the generation and evolution of irradiation induced defect clusters ranging in sizes from the micro- to meso-scopic length scales. Based on a two-dimensional Fourier transform and Stroh formalism that are ideal for homogeneous and layered anisotropic solids, we have developed robust and computationally efficient methods to calculate the displacement fields for circular and polygonal dislocation loops. Using the homogeneous nature of the Green tensor of order -1, we have shown that the displacement and stress fields of dislocation loops can be obtained by numerical quadrature of a line integral. In addition, it is shown that the sextuple integrals associated with the strain energy of loops can be represented by the product of a pre-factor containing elastic anisotropy effects and a universal term that is singular and equal to that for elastic isotropic case. Furthermore, we have found that the self-energy pre-factor of prismatic loops is identical to the effective modulus of normal contact, and the pre-factor of shear loops differs from the effective indentation modulus in shear by only a few percent. These results provide a convenient method for examining dislocation reaction energetic and efficient procedures for numerical computation of local displacements and stresses of dislocation loops, both of which play integral roles in quantitative defect analyses within combined experimental–theoretical investigations.

  13. Biological effects due to weak magnetic fields on plants

    NASA Astrophysics Data System (ADS)

    Belyavskaya, N.

    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

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

    PubMed

    Hamida, Tarek; Babadagli, Tayfun

    2007-09-01

    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.

  15. Full-sensitivity depth-resolved measurements of displacement fields inside weakly scattering materials using wavelength scanning interferometry

    NASA Astrophysics Data System (ADS)

    Ruiz, Pablo D.; Chakraborty, Semanti

    2012-10-01

    This paper extends Digital Speckle Pattern Interferometry into three dimensions. A Wavelength Scanning Interferometry (WSI) system is proposed which provides displacement fields inside the volume of semi-transparent scattering materials with high spatial resolution and three-dimensional displacement sensitivity. The main driver to develop such a system is the need to determine constitutive parameters (mainly elastic constants) of materials such as polymers and biological tissues so that their behavior can be modeled computationally. The sample is illuminated by three non-coplanar collimated beams around the observation direction. Sequences of two-dimensional interferograms are recorded while the frequency of the laser is tuned at a constant rate. Each pixel thus records and intensity signal which temporal frequency encodes the optical path difference between the illumination and reference beams for a particular point on the sample. Fourier transformation along the time axis reconstructs the magnitude and phase of the material's microstructure. Different optical paths along each illumination direction are required in order to separate or multiplex, in the frequency domain, the signals corresponding to each sensitivity vector. In this way, all the information required to reconstruct the location and the 3D displacement vector of scattering points within the volume in the material is recorded simultaneously. A controlled validation experiment is performed, which confirms the ability of the technique to provide three dimensional displacement distributions inside semitransparent scattering materials.

  16. Viscoelastic properties combined with relevant boundary conditions can produce the arctangent shape of the geodetic displacement field

    NASA Astrophysics Data System (ADS)

    Traore, N.; Le Pourhiet, L.; Frelat, J.; Rolandone, F.; Meyer, B.

    2012-04-01

    The screw dislocation model (Weertman & Weertman, 1966) gives the horizontal displacement u as a function of the vertical distance d to the dislocation, the horizontal distance x and the slip s on each side of the dislocation. u = - (s/π) arctan(x/d) Savage and Burford (1973) interpreted this model in terms of horizontal displacement across a strike slip fault which is locked down to depth d, s being the plate velocity. Because of its simplicity and because the arctangent shape well represents the displacement that can be measured around most of the major strike slip faults, this model is commonly used to match geodetic data. We present numerical simulations that have been made with the software CASTEM, a finite element code for structural and mechanical modeling. The models are rectangular boxes that have elastic or viscoelastic properties, and three different kinds of conditions are applied on the boundaries of the domain that may have an impact on the localization of the displacement near the fault plane. The first boundary condition imposes the displacement under the plate, this case has been chosen because of its similarity to the Weertman's screw dislocation model. The second boundary condition imposes the displacement in the front, it corresponds to an extrusion. For the third boundary condition, the displacement is imposed laterally and simulates the general plate motion that drags the domain on both sides. We found that the displacement at the free surface does not fit an arctangent in all cases. If a perfectly elastic, homogeneous domain is used, only the first two types of boundary conditions lead to a displacement field resembling the geodetic data. This is awkward since the third kind of boundary conditions seems to be geologically the more relevant one. We then introduced local rheological modifications to reduce locally the equivalent elastic plate thickness in the vicinity of the fault. This is achieved by introducing a viscoelastic relaxation in

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    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.

  18. Three-dimensional displacement fields measured in a deforming granular-media surface by combined fringe projection and speckle photography

    NASA Astrophysics Data System (ADS)

    Barrientos, B.; Cerca, M.; García-Márquez, J.; Hernández-Bernal, C.

    2008-10-01

    3D displacement fields on a diffuse surface are measured by a combination of two optical methods, fringe projection and speckle photography. The use of a single camera for recording information from the two methods implies that no calibration procedures are necessary, as is the case in stereoscopy-based techniques. Out-of-plane displacements are measured by fringe projection whereas speckle photography yields the 2D in-plane component. By using this technique, we analyze in detail the morphological spatial-temporal evolution of an analogue model of the Earth's crust while subjected to compression forces. We discuss the experimental results and their relevance to the micromechanics of a surface of dry, non-cohesive and dilatant granular media. The results show that the combination of fringe projection and speckle photography is well suited for this type of study and allows the characterization of strain at the grain scale.

  19. Displacement Fields and Self-Energies of Circular and Polygonal Dislocation Loops in Homogeneous and Layered Anisotropic Solids

    DOE PAGES

    Gao, Yanfei; Larson, Ben C.

    2015-06-19

    There are large classes of materials problems that involve the solutions of stress, displacement, and strain energy of dislocation loops in elastically anisotropic solids, including increasingly detailed investigations of the generation and evolution of irradiation induced defect clusters ranging in sizes from the micro- to meso-scopic length scales. Based on a two-dimensional Fourier transform and Stroh formalism that are ideal for homogeneous and layered anisotropic solids, we have developed robust and computationally efficient methods to calculate the displacement fields for circular and polygonal dislocation loops. Using the homogeneous nature of the Green tensor of order -1, we have shown thatmore » the displacement and stress fields of dislocation loops can be obtained by numerical quadrature of a line integral. In addition, it is shown that the sextuple integrals associated with the strain energy of loops can be represented by the product of a pre-factor containing elastic anisotropy effects and a universal term that is singular and equal to that for elastic isotropic case. Furthermore, we have found that the self-energy pre-factor of prismatic loops is identical to the effective modulus of normal contact, and the pre-factor of shear loops differs from the effective indentation modulus in shear by only a few percent. These results provide a convenient method for examining dislocation reaction energetic and efficient procedures for numerical computation of local displacements and stresses of dislocation loops, both of which play integral roles in quantitative defect analyses within combined experimental–theoretical investigations.« less

  20. Mean-square error due to gradiometer field measuring devices.

    PubMed

    Hatsell, C P

    1991-06-01

    Gradiometers use spatial common mode magnetic field rejection to reduce interference from distant sources. They also introduce distortion that can be severe, rendering experimental data difficult to interpret. Attempts to recover the measured magnetic field from the gradiometer output will be plagued by the nonexistence of a spatial function for deconvolution (except for first-order gradiometers), and by the high-pass nature of the spatial transform that emphasizes high spatial frequency noise. Goals of a design for a facility for measuring biomagnetic fields should be an effective shielded room and a field detector employing a first-order gradiometer.

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

    SciTech Connect

    Shiota, Fuyuhiko; Morokuma, Tadashi

    2006-09-15

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

  2. Induced Magnetic Field Due to Reaction Wheel Shielding

    NASA Astrophysics Data System (ADS)

    Pudney, M. A.; Kapfunde, G.; Trougnou, L.

    2016-05-01

    In situ magnetic field measurements are of critical importance to unanswered questions on the inner heliosphere, such as: how the corona and solar wind are accelerated and heated; how the solar magnetic field evolves over a solar cycle; and how this field links into space. However, accurate spacecraft magnetometer measurements require reliable in-flight calibration. The magnetic interference caused by reaction wheels on magnetometer measurements in space is well known, and a common mitigation method is to use magnetic shielding. However, the presence of high-permeability material in-flight has the side-effect of distorting the true ambient field. We present a theoretical analysis of this distortion, and suggest a transfer function that can be used to recover the ambient field from the distorted dataset. Experimental measurements on a shield prototype for the Solar Orbiter mission agree with predictions to within an order of magnitude, demonstrating a distortion of approximately 1 part in 104.

  3. An Optical System to Monitor the Displacement Field of Glass-fibre Posts Subjected to Thermal Loading

    PubMed Central

    Corsalini, Massimo; Pettini, Francesco; Di Venere, Daniela; Ballini, Andrea; Chiatante, Giuseppe; Lamberti, Luciano; Pappalettere, Carmine; Fiorentino, Michele; Uva, Antonio E.; Monno, Giuseppe; Boccaccio, Antonio

    2016-01-01

    Endocanalar posts are necessary to build up and retain coronal restorations but they do not reinforce dental roots. It was observed that the dislodgement of post-retained restorations commonly occurs after several years of function and long-term retention may be influenced by various factors such as temperature changes. Temperature changes, in fact, produce micrometric deformations of post and surrounding tissues/materials that may generate high stress concentrations at the interface thus leading to failure. In this study we present an optical system based on the projection moiré technique that has been utilized to monitor the displacement field of endocanalar glass-fibre posts subjected to temperature changes. Measurements were performed on forty samples and the average displacement values registered at the apical and middle region were determined for six different temperature levels. A total of 480 displacement measurements was hence performed. The values of the standard deviation computed for each of the tested temperatures over the forty samples appear reasonably small which proves the robustness and the reliability of the proposed optical technique. The possible implications for the use of the system in the applicative context were discussed. PMID:27990186

  4. Dynamic optical interferometry applied to analyse out of plane displacement fields for crack propagation in brittle materials

    NASA Astrophysics Data System (ADS)

    Hedan, S.; Pop, O.; Valle, V.; Cottron, M.

    2006-08-01

    We propose in this paper, to analyse, the evolution of out-of-plane displacement fields for a crack propagation in brittle materials. As the crack propagation is a complex process that involves the deformation mechanisms, the out-of-plane displacement measurement gives pertinent information about the 3D effects. For investigation, we use the interferometric method. The optical device includes a laser source, a Michelson interferometer and an ultra high-speed CCD camera. To take into account the crack velocity, we dispose of a maximum frame rate of 1Mfps. The experimental tests have been carried out for a SEN (Single Edge Notch) specimen of PMMA material. The crack propagation is initiated by adding a dynamic energy given by the impact of a cutter on the initial crack. The obtained interferograms are analysed with a new phase extraction method entitled MPC [6]. This analysis, which has been developed specially for dynamic studies, gives the out-of-plane displacement with an accuracy of about 10 nm.

  5. Rapid dissipation of magnetic fields due to the Hall current

    SciTech Connect

    Vainshtein, S. I.; Chitre, S. M.; Olinto, A. V.

    2000-04-01

    We propose a mechanism for the fast dissipation of magnetic fields which is effective in a stratified medium where ion motions can be neglected. In such a medium, the field is frozen into the electrons, and Hall currents prevail. Although Hall currents conserve magnetic energy, in the presence of density gradients they are able to create current sheets which can be sites for efficient dissipation of magnetic fields. We recover the frequency {omega}{sub MH} for Hall oscillations modified by the presence of density gradients. We show that these oscillations can lead to an exchange of energy between different components of the field. We calculate the time evolution, and show that magnetic fields can dissipate on a time scale of order 1/{omega}{sub MH}. This mechanism can play an important role in magnetic dissipation in systems with very steep density gradients, where the ions are static such as those found in the solid crust of neutron stars. (c) 2000 The American Physical Society.

  6. EFFECT OF STRAIN FIELD ON THRESHOLD DISPLACEMENT ENERGY OF TUNGSTEN STUDIED BY MOLECULAR DYNAMICS SIMULATION

    SciTech Connect

    Wang, D.; Gao, Ning; Setyawan, Wahyu; Kurtz, Richard J.; Gao, X.; He, W. H.

    2016-03-31

    The influence of hydrostatic strain on point defect formation energy and threshold displacement energy (Ed) in body-centered cubic (BCC) tungsten was studied with molecular dynamics simulations. Two different tungsten potentials (Fikar and Juslin) were used. The minimum Ed direction calculated with the Fikar-potential was <100>, but with the Juslin-potential it was <111>. The most stable self-interstitial (SIA) configuration was a <111>-crowdion for both potentials. The stable SIA configuration did not change with applied strain. Varying the strain from compression to tension increased the vacancy formation energy but decreased the SIA formation energy. The SIA formation energy changed more significantly than for a vacancy such that Ed decreased with applied strain from compression to tension.

  7. Experimental and numerical in-plane displacement fields for determine the J-integral on a PMMA cracked specimen

    NASA Astrophysics Data System (ADS)

    Hedan, S.; Valle, V.; Cottron, M.

    2010-06-01

    Contrary to J-integral values calculated from the 2D numerical model, calculated J-integrals [1] in the 3D numerical and 3D experimental cases are not very close with J-integral used in the literature. We can note a problem of structure which allows three-dimensional effects surrounding the crack tip to be seen. The aim of this paper is to determine the zone where the Jintegral formulation of the literature is sufficient to estimate the energy release rate (G) for the 3D cracked structure. For that, a numerical model based on the finite element method and an experimental setup are used. A grid method is adapted to experimentally determine the in-plane displacement fields around a crack tip in a Single-Edge-Notch (SEN) tensile polymer (PMMA) specimen. This indirect method composed of experimental in-plane displacement fields and of 2 theoretical formulations, allows the experimental J-integral on the free-surface to be determined and the results obtaining by the 3D numerical simulations to be confirmed.

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

    NASA Astrophysics Data System (ADS)

    Hagene, J. K.

    2012-04-01

    being a decision support system. Field trials as part of the ISTIMES project took place in Potenza, Italy, for a week in July 2011. The test target was Musmeci's bridge, a bridge with a design where aesthetic values have been just as important as traditional civil engineering aspects. Several technologies and techniques were tested at the same part of the bridge to allow for data correlation between different sensors. The camera and processing parts of the optical displacement monitoring system were mounted on a concrete wall at the one end of the bridge while the LED reference points were mounted on the bridge approximately 40 metres away. The tests at the Musmeci's bridge are successful and verifying some of the findings from the tests in Switzerland. However, we learned a lesson with regards to temporary mounting of the reference points using glossy stainless steel parts. A short period early in the morning, when illuminated by the sun, these stainless steel parts were just as bright as the LED reference point leading to potential noise in the measurements. Due to availability of the raw data this could be fixed later doing post processing on the stored data. One of the findings was that we have relatively large time of day variation that appear to be periodic with a cycle time of about 24 hours, at least with similar weather conditions. These displacements appear to be in the order of 10 mm and is probably due to thermal effects. Several shorter displacements have also been registered with amplitudes of a couple of mm and duration around 10 seconds. These shorter displacement peaks appear to be caused by heavy vehicles passing by on the bridge. The introduction of the processing using sub-pixel resolution looks very promising and appears to give a significant improvement of the actual resolution of the system. Even thought the measurements in the field are successfully completed we have noted larger slowly moving displacements than originally expected. This combined

  9. Circulation in the high-latitude thermosphere due to electric fields and Joule heating

    NASA Technical Reports Server (NTRS)

    Heaps, M. G.; Megill, L. R.

    1975-01-01

    Electric fields in the earth's upper atmosphere are capable of setting the neutral atmosphere in motion via ion-neutral collisions as well as pressure gradients from resultant Joule heating. By means of simple models for the high-latitude thermosphere and electric fields a simplified set of coupled equations is solved which show that moderate electric fields, when present for a period of several hours, are capable of displacing the neutral atmosphere of the order of 50 km in the vertical, a few hundred kilometers in the north-south direction and over 1000 km in the east-west direction.

  10. Optical low-cost and portable arrangement for full field 3D displacement measurement using a single camera

    NASA Astrophysics Data System (ADS)

    López-Alba, E.; Felipe-Sesé, L.; Schmeer, S.; Díaz, F. A.

    2016-11-01

    In the current paper, an optical low-cost system for 3D displacement measurement based on a single camera and 3D digital image correlation is presented. The conventional 3D-DIC set-up based on a two-synchronized-cameras system is compared with a proposed pseudo-stereo portable system that employs a mirror system integrated in a device for a straightforward application achieving a novel handle and flexible device for its use in many scenarios. The proposed optical system splits the image by the camera into two stereo images of the object. In order to validate this new approach and quantify its uncertainty compared to traditional 3D-DIC systems, solid rigid in and out-of-plane displacements experiments have been performed and analyzed. The differences between both systems have been studied employing an image decomposition technique which performs a full image comparison. Therefore, results of all field of view are compared with those using a stereoscopy system and 3D-DIC, discussing the accurate results obtained with the proposed device not having influence any distortion or aberration produced by the mirrors. Finally, the adaptability of the proposed system and its accuracy has been tested performing quasi-static and dynamic experiments using a silicon specimen under high deformation. Results have been compared and validated with those obtained from a conventional stereoscopy system showing an excellent level of agreement.

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

    SciTech Connect

    Hanson, P.J.; Todd, D.E.; Huston, M.A.; Joslin, J.D.; Croker, J.L.; Auge, R.M.

    1998-04-01

    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.

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

    PubMed

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

    2014-03-21

    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.

  13. Full-field dynamic displacement and strain measurement using pulsed and high-speed 3D image correlation photogrammetry

    NASA Astrophysics Data System (ADS)

    Schmidt, Timothy; Tyson, John; Galanulis, Konstantin

    2004-02-01

    3D image correlation is a robust method for measuring full-field displacements and strains using a calibrated pair of video cameras. Underlying principles and benefits are reviewed, and the method is compared to both 3D ESPI and 2D image correlation. Several applications combining image correlation photogrammetry with stroboscopic illumination and/or high-speed video cameras are presented. Operational strains in ionic polymeric muscle samples and electro-restrictive actuators are determined. The use of short-duration white light pulses to study automobile tires on road wheels at speeds up to 150 miles per hour is demonstrated. Initial work measuring strains on an 18" flywheel in a spin pit at up to 35,000 rpm is described. A notched rubber dogbone sample is pulled to failure at 125% strain in 38 milliseconds, and hundreds of full-field strain maps are captured. This paper includes discussion of sample preparation methods and special lighting systems, including pulsed arc lamps and pulsed lasers. A matrix of capability using available high speed cameras is included.

  14. Far-field errors due to random noise in cylindrical near-field measurements

    NASA Astrophysics Data System (ADS)

    Romeu, Jordi; Jofre, Luis; Cardama, Angel

    1992-01-01

    A full characterization of the far-field noise obtained from cylindrical near- to far-field transformation, for a white Gaussian, space stationary, near-field noise is derived. A possible source for such noise is the receiver additive noise. The noise characterization is done by obtaining the autocorrelation of the far-field noise, which is shown to be easily computed during the transformation process. Even for this simple case, the far-field noise has complex behavior dependent on the measurement probe. Once the statistical properties of the far-field noise are determined, it is possible to compute upper and lower bounds for the radiation pattern for a given probability. These bounds define a strip within the radiation pattern with the desired probability. This may be used as part of a complete near-field error analysis of a particular cylindrical near-field facility.

  15. A finite element study to determine the occurrence of abfraction and displacement due to various occlusal forces and with different alveolar bone height

    PubMed Central

    Vandana, Kharidhi Laxman; Deepti, Mittal; Shaimaa, Muneer; Naveen, Karnath; Rajendra, Desai

    2016-01-01

    Background: Noncarious cervical lesions (NCCLs) are rarely described in the periodontal literature, perhaps because no direct link between NCCLs and periodontal lesions has been demonstrated. Aim: The aim of this study is to determine the stress and displacement produced in the tooth at different bone levels under different occlusal load using finite element model (FEM) study. Materials and Methods: Four FEMs of maxillary incisor were designed consisting of the tooth, pulp, periodontal ligament, and alveolar bone at the various level of bone height (25%, 50%, and 75%). Different occlusal load (5 kg, 15 kg, 24 kg, and 29 kg) at an angle of 50° to the long axis of the tooth was applied on the palatal surface at the level of middle third of the crown. All the models were assumed to be isotropic, linear and elastic, and the analysis was performed on a Pentium IV processor computer using the ANSYS software. Results: The maximum stress in the tooth was seen in the cervical region and to a greater extent at the apex for all models. The maximum tooth displacement for all the occlusal loads applied in this study was at the incisal edge with the minimum tooth displacement at the cervical third of the root which shifted apically with the reduction of alveolar bone support. Conclusion: The cumulative effect of increased stress and displacement at the cervical region of the tooth would result in abfraction as the age advances along with other wasting diseases. PMID:27041831

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

    NASA Technical Reports Server (NTRS)

    Parasarathy, R.; Karamcheti, K.

    1972-01-01

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

  17. Displacement Current and Surface Flashover

    SciTech Connect

    harris, J R; Caporaso, G J; Blackfield, D; Chen, Y J

    2007-07-17

    High-voltage vacuum insulator failure is generally due to surface flashover rather than insulator bulk breakdown. Vacuum surface flashover is widely believed to be initiated by a secondary electron emission avalanche along the vacuum-insulator interface. This process requires a physical mechanism to cause secondary electrons emitted from the insulator surface to return to that surface. Here, we show that when an insulator is subjected to a fast high-voltage pulse, the magnetic field due to displacement current through the insulator can provide this mechanism. This indicates the importance of the voltage pulse shape, especially the rise time, in the flashover initiation process.

  18. Deformed neutron stars due to strong magnetic field in terms of relativistic mean field theories

    NASA Astrophysics Data System (ADS)

    Yanase, Kota; Yoshinaga, Naotaka

    2014-09-01

    Some observations suggest that magnetic field intensity of neutron stars that have particularly strong magnetic field, magnetars, reaches values up to 1014-15G. It is expected that there exists more strong magnetic field of several orders of magnitude in the interior of such stars. Neutron star matter is so affected by magnetic fields caused by intrinsic magnetic moments and electric charges of baryons that masses of neutron stars calculated by using Tolman-Oppenheimer-Volkoff equation is therefore modified. We calculate equation of state (EOS) in density-dependent magnetic field by using sigma-omega-rho model that can reproduce properties of stable nuclear matter in laboratory Furthermore we calculate modified masses of deformed neutron stars.

  19. Distorted orbit due to field errors and particle trajectories in combined undulator and axial magnetic field

    SciTech Connect

    Papadichev, V.A.

    1995-12-31

    Undulator and solenoid field errors cause electron trajectory deviation from the ideal orbit. Even small errors can result in a large lower frequency excursion from the undulator axis of a distorted orbit and of betatron oscillations performed now around it, especially near resonant conditions. Numerical calculation of a trajectory step by step requires large computing time and treats only particular cases, thus lacking generality. Theoretical treatment is traditionally based on random distribution of field errors, which allows a rather general approach, but is not convenient for practical purposes. In contrast, analytical treatment shows explicitly how distorted orbit and betatron oscillation amplitude depend on field parameters and errors and indicates how to eliminate these distortions. An analytical solution of the equations of motion can be found by expanding field errors and distorted orbit in Fourier series as was done earlier for the simplest case of a plane undulator without axial magnetic field. The same method is applied now to the more general case of combined generlized undulator and axial magnetic fields. The undulator field is a superposition of the fields of two plane undulators with mutually orthogonal fields and an arbitrary axial shift of the second undulator relative to the first. Beam space-charge forces and external linear focusing are taken into account. The particle trajectory is a superposition of ideal and distorted orbits with cyclotron gyration and slow drift gyration in the axial magnetic field caused by a balance of focusing and defocusing forces. The amplitudes of these gyrations depend on transverse coordinate and velocity at injection and can nearly double the total deviation of an electron from the undulator axis even after an adiabatic undulator entry. If the wavenumber of any Fourier harmonic is close to the wavenumbers of cyclotron or drift gyrations, a resonant increase of orbit distortion occurs.

  20. Design and Realization of a Three Degrees of Freedom Displacement Measurement System Composed of Hall Sensors Based on Magnetic Field Fitting by an Elliptic Function.

    PubMed

    Zhao, Bo; Wang, Lei; Tan, Jiu-Bin

    2015-09-08

    This paper presents the design and realization of a three degrees of freedom (DOFs) displacement measurement system composed of Hall sensors, which is built for the XYθz displacement measurement of the short stroke stage of the reticle stage of lithography. The measurement system consists of three pairs of permanent magnets mounted on the same plane on the short stroke stage along the Y, Y, X directions, and three single axis Hall sensors correspondingly mounted on the frame of the reticle stage. The emphasis is placed on the decoupling and magnetic field fitting of the three DOFs measurement system. The model of the measurement system is illustrated, and the XY positions and θZ rotation of the short stroke stage can be obtained by decoupling the sensor outputs. A magnetic field fitting by an elliptic function-based compensation method is proposed. The practical field intensity of a permanent magnet at a certain plane height can be substituted for the output voltage of a Hall sensors, which can be expressed by the elliptic function through experimental data as the crucial issue to calculate the three DOFs displacement. Experimental results of the Hall sensor displacement measurement system are presented to validate the proposed three DOFs measurement system.

  1. Design and Realization of a Three Degrees of Freedom Displacement Measurement System Composed of Hall Sensors Based on Magnetic Field Fitting by an Elliptic Function

    PubMed Central

    Zhao, Bo; Wang, Lei; Tan, Jiu-Bin

    2015-01-01

    This paper presents the design and realization of a three degrees of freedom (DOFs) displacement measurement system composed of Hall sensors, which is built for the XYθz displacement measurement of the short stroke stage of the reticle stage of lithography. The measurement system consists of three pairs of permanent magnets mounted on the same plane on the short stroke stage along the Y, Y, X directions, and three single axis Hall sensors correspondingly mounted on the frame of the reticle stage. The emphasis is placed on the decoupling and magnetic field fitting of the three DOFs measurement system. The model of the measurement system is illustrated, and the XY positions and θZ rotation of the short stroke stage can be obtained by decoupling the sensor outputs. A magnetic field fitting by an elliptic function-based compensation method is proposed. The practical field intensity of a permanent magnet at a certain plane height can be substituted for the output voltage of a Hall sensors, which can be expressed by the elliptic function through experimental data as the crucial issue to calculate the three DOFs displacement. Experimental results of the Hall sensor displacement measurement system are presented to validate the proposed three DOFs measurement system. PMID:26370993

  2. Far-field optical degradation due to near-field transmission through a turbulent heated jet.

    PubMed

    Cicchiello, J M; Jumper, E J

    1997-09-01

    When a laser beam traverses an optically active, turbulent flow field, the laser wave front is aberrated by the flow. Density variations in a heated two-dimensional jet, for example, correspond to index-of-refraction variations, and this modulation of the index in the fluid can imprint an optical phase disturbance, or phase error, onto the laser wave front. Adaptive-optic systems seek to correct the phase error of the wave front, and thus restore the integrity of the far-field irradiance pattern. Given a near-field spatial mapping of a phase disturbance, the far-field irradiance pattern of the affected wave front can be calculated with Fourier-optics techniques. A Fourier-optics computer code was used to study the far-field irradiance patterns arising from actual time-varying measurements of a fluid-induced phase error. The time-averaged Strehl ratio was studied to provide insight into the spatial and temporal design requirements for adaptive-optic systems applied to the time series of near-field spatial phase-error maps.

  3. Electric field due to velocity space particle loss in field-reversed configurations

    SciTech Connect

    Hsiao, M.; Staudenmeier, J.L.; Chiang, P.

    1989-02-01

    Particle confinement criteria for velocity space particle loss are used to calculate the radial and axial electric potential profiles in field-reversed configurations (FRC's). Assuming Vlasov equilibrium distribution functions for both electrons and ions, the density profile and the potential profile are calculated self-consistently. With rest Maxwellian distribution functions for both species and the Hill's vortex magnetic configuration, a radial electric field of about 0--70 V/cm and an axial electric field of about 0--4 V/cm, depending on positions, have been found for a typical set of experimental parameters: electron temperature T/sub e/ = 100 eV, ion temperature T/sub i/ = 200 eV, magnetic field B/sub 0/ = 5500 G, separatrix radius r/sub s/ = 12 cm, and elongation factor k = 5. The corresponding density profile has behavior similar to profiles observed in the experiments. Cases using rigid-rotor distribution functions with different rigid rotating frequencies are also studied.

  4. Collective trauma in the Vanni- a qualitative inquiry into the mental health of the internally displaced due to the civil war in Sri Lanka

    PubMed Central

    2010-01-01

    Background From January to May, 2009, a population of 300,000 in the Vanni, northern Sri Lanka underwent multiple displacements, deaths, injuries, deprivation of water, food, medical care and other basic needs caught between the shelling and bombings of the state forces and the LTTE which forcefully recruited men, women and children to fight on the frontlines and held the rest hostage. This study explores the long term psychosocial and mental health consequences of exposure to massive, existential trauma. Methods This paper is a qualitative inquiry into the psychosocial situation of the Vanni displaced and their ethnography using narratives and observations obtained through participant observation; in depth interviews; key informant, family and extended family interviews; and focus groups using a prescribed, semi structured open ended questionnaire. Results The narratives, drawings, letters and poems as well as data from observations, key informant interviews, extended family and focus group discussions show considerable impact at the family and community. The family and community relationships, networks, processes and structures are destroyed. There develops collective symptoms of despair, passivity, silence, loss of values and ethical mores, amotivation, dependency on external assistance, but also resilience and post-traumatic growth. Conclusions Considering the severity of family and community level adverse effects and implication for resettlement, rehabilitation, and development programmes; interventions for healing of memories, psychosocial regeneration of the family and community structures and processes are essential. PMID:20667090

  5. Synthesis of finite displacements and displacements in continental margins

    NASA Technical Reports Server (NTRS)

    Speed, R. C.; Elison, M. W.; Heck, F. R.; Russo, R. M.

    1988-01-01

    The scope of the project is the analysis of displacement-rate fields in the transitional regions between cratonal and oceanic lithospheres over Phanerozoic time (last 700 ma). Associated goals are an improved understanding of range of widths of major displacement zones; the partition of displacement gradients and rotations with position and depth in such zones; the temporal characteristics of such zones-the steadiness, episodicity, and duration of uniform versus nonunifrom fields; and the mechanisms and controls of the establishment and kinematics of displacement zones. The objective is to provide a context of time-averaged kinematics of displacement zones. The initial phase is divided topically among the methodology of measurement and reduction of displacements in the lithosphere and the preliminary analysis from geologic and other data of actual displacement histories from the Cordillera, Appalachians, and southern North America.

  6. Miscible, porous media displacements with density stratification.

    PubMed

    Riaz, Amir; Meiburg, Eckart

    2004-11-01

    High accuracy, three-dimensional numerical simulations of miscible displacements with gravity override, in both homogeneous and heterogeneous porous media, are discussed for the quarter five-spot configuration. The influence of viscous and gravitational effects on the overall displacement dynamics is described in terms of the vorticity variable. Density differences influence the flow primarily by establishing a narrow gravity layer, in which the effective Peclet number is enhanced due to the higher flow rate. Although this effect plays a dominant role in homogeneous flows, it is suppressed to some extent in heterogeneous displacements. This is a result of coupling between the viscous and permeability vorticity fields. When the viscous wavelength is much larger than the permeability wavelength, gravity override becomes more effective because coupling between the viscous and permeability vorticity fields is less pronounced. Buoyancy forces of a certain magnitude can lead to a pinch-off of the gravity layer, thereby slowing it down.

  7. Internal displacement in Burma.

    PubMed

    Lanjouw, S; Mortimer, G; Bamforth, V

    2000-09-01

    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.

  8. Deformation of a nearly hemispherical conducting drop due to an electric field: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Corson, L. T.; Tsakonas, C.; Duffy, B. R.; Mottram, N. J.; Sage, I. C.; Brown, C. V.; Wilson, S. K.

    2014-12-01

    We consider, both theoretically and experimentally, the deformation due to an electric field of a pinned nearly hemispherical static sessile drop of an ionic fluid with a high conductivity resting on the lower substrate of a parallel-plate capacitor. Using both numerical and asymptotic approaches, we find solutions to the coupled electrostatic and augmented Young-Laplace equations which agree very well with the experimental results. Our asymptotic solution for the drop interface extends previous work in two ways, namely, to drops that have zero-field contact angles that are not exactly π/2 and to higher order in the applied electric field, and provides useful predictive equations for the changes in the height, contact angle, and pressure as functions of the zero-field contact angle, drop radius, surface tension, and applied electric field. The asymptotic solution requires some numerical computations, and so a surprisingly accurate approximate analytical asymptotic solution is also obtained.

  9. Melt Motion Due to Peltier Marking During Bridgman Crystal Growth with an Axial Magnetic Field

    NASA Technical Reports Server (NTRS)

    Sellers, C. C.; Walker, John S.; Szofran, Frank R.; Motakef, Shariar

    2000-01-01

    This paper treats a liquid-metal flow inside an electrically insulating cylinder with electrically conducting solids above and below the liquid region. There is a uniform axial magnetic field, and there is an electric current through the liquid and both solids. Since the lower liquid-solid interface is concave into the solid and since the liquid is a better electrical conductor than the adjacent solid, the electric current is locally concentrated near the centerline. The return to a uniform current distribution involves a radial electric current which interacts with the axial magnetic field to drive an azimuthal flow. The axial variation of the centrifugal force due to the azimuthal velocity drives a meridional circulation with radial and axial velocities. This problem models the effects of Peltier marking during the vertical Bridgman growth of semiconductor crystals with an externally applied magnetic field, where the meridional circulation due to the Peltier Current may produce important mixing in the molten semiconductor.

  10. Surface potential at a ferroelectric grain due to asymmetric screening of depolarization fields

    SciTech Connect

    Genenko, Yuri A. Hirsch, Ofer; Erhart, Paul

    2014-03-14

    Nonlinear screening of electric depolarization fields, generated by a stripe domain structure in a ferroelectric grain of a polycrystalline material, is studied within a semiconductor model of ferroelectrics. It is shown that the maximum strength of local depolarization fields is rather determined by the electronic band gap than by the spontaneous polarization magnitude. Furthermore, field screening due to electronic band bending and due to presence of intrinsic defects leads to asymmetric space charge regions near the grain boundary, which produce an effective dipole layer at the surface of the grain. This results in the formation of a potential difference between the grain surface and its interior of the order of 1 V, which can be of either sign depending on defect transition levels and concentrations. Exemplary acceptor doping of BaTiO{sub 3} is shown to allow tuning of the said surface potential in the region between 0.1 and 1.3 V.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  12. Domain wall interactions due to vacuum Dirac field fluctuations in 2 +1 dimensions

    NASA Astrophysics Data System (ADS)

    Fosco, C. D.; Mazzitelli, F. D.

    2016-07-01

    We evaluate quantum effects due to a two-component Dirac field in 2 +1 spacetime dimensions, coupled to domain-wall-like defects with a smooth shape. We show that these effects induce nontrivial contributions to the (shape-dependent) energy of the domain walls. For a single defect, we study the divergences in the corresponding self-energy, and also consider the role of the massless zero mode—corresponding to the Callan-Harvey mechanism—by coupling the Dirac field to an external gauge field. For two defects, we show that the Dirac field induces a nontrivial, Casimir-like effect between them, and we provide an exact expression for that interaction in the case of two straight-line parallel defects. As is the case for the Casimir interaction energy, the result is finite and unambiguous.

  13. Three-dimensional displacement field of the 2015 Mw8.3 Illapel earthquake (Chile) from across- and along-track Sentinel-1 TOPS interferometry

    NASA Astrophysics Data System (ADS)

    Grandin, R.; Klein, E.; Métois, M.; Vigny, C.

    2016-03-01

    Wide-swath imaging has become a standard acquisition mode for radar missions aiming at applying synthetic aperture radar interferometry (InSAR) at global scale with enhanced revisit frequency. Increased swath width, compared to classical Stripmap imaging mode, is achieved at the expense of azimuthal resolution. This makes along-track displacements, and subsequently north-south displacements, difficult to measure using conventional split-beam (multiple-aperture) InSAR or cross-correlation techniques. Alternatively, we show here that the along-track component of ground motion can be deduced from the double difference between backward and forward looking interferograms within regions of burst overlap. "Burst overlap interferometry" takes advantage of the large squint angle diversity of Sentinel-1 (˜1°) to achieve subdecimetric accuracy on the along-track component of ground motion. We demonstrate the efficiency of this method using Sentinel-1 data covering the 2015 Mw8.3 Illapel earthquake (Chile) for which we retrieve the full 3-D displacement field and validate it against observations from a dense network of GPS sensors.

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

    SciTech Connect

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

    2005-05-16

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

  15. The magnetic field inside a layered anisotropic spherical conductor due to internal sources

    NASA Astrophysics Data System (ADS)

    Nieminen, Jaakko O.; Stenroos, Matti

    2016-01-01

    Recent advances in neuronal current imaging using magnetic resonance imaging and in invasive measurement of neuronal magnetic fields have given a need for methods to compute the magnetic field inside a volume conductor due to source currents that are within the conductor. In this work, we derive, verify, and demonstrate an analytical expression for the magnetic field inside an anisotropic multilayer spherically symmetric conductor due to an internal current dipole. We casted an existing solution for electric field to vector spherical harmonic (VSH) form. Next, we wrote an ansatz for the magnetic field using toroidal-poloidal decomposition that uses the same VSHs. Using properties of toroidal and poloidal components and VSHs and applying magnetic scalar potential, we then formulated a series expression for the magnetic field. The convergence of the solution was accelerated by formulating the solution using an addition-subtraction method. We verified the resulting formula against boundary-element method. The verification showed that the formulas and implementation are correct; 99th percentiles of amplitude and angle differences between the solutions were below 0.5% and 0.5°, respectively. As expected, the addition-subtraction model converged faster than the unaccelerated model; close to the source, 250 terms gave relative error below 1%, and the number of needed terms drops fast, as the distance to the source increases. Depending on model conductivities and source position, field patterns inside a layered sphere may differ considerably from those in a homogeneous sphere. In addition to being a practical modeling tool, the derived solution can be used to verify numerical methods, especially finite-element method, inside layered anisotropic conductors.

  16. Atomic displacements and lattice distortion in the magnetic-field-induced charge-ordered state of SmRu4P12

    NASA Astrophysics Data System (ADS)

    Matsumura, Takeshi; Michimura, Shinji; Inami, Toshiya; Fushiya, Kengo; Matsuda, Tatsuma D.; Higashinaka, Ryuji; Aoki, Yuji; Sugawara, Hitoshi

    2016-11-01

    Structural properties of SmRu4P12 in the anomalous magnetic ordered phase between T*˜14 K and TN=16.5 K in magnetic fields has been studied by x-ray diffraction. Atomic displacements of Ru and P, reflecting the field-induced charge order of the p electrons, have been deduced by analyzing the intensities of the forbidden Bragg peaks, assuming a cubic space group P m 3 ¯ . Also, by utilizing a high-resolution x-ray diffraction experiment, we observed a splitting of fundamental Bragg peaks, clarifying that the unit cell in the magnetic ordered phase is rhombohedral elongated along the [1 1 1 ] axis. The response of the rhombohedral domains to the magnetic field, which reflects the direction of the magnetic moment, is studied in detail.

  17. Field collapse due to band-tail charge in amorphous silicon solar cells

    SciTech Connect

    Wang, Qi; Crandall, R.S.; Schiff, E.A.

    1996-05-01

    It is common for the fill factor to decrease with increasing illumination intensity in hydrogenated amorphous silicon solar cells. This is especially critical for thicker solar cells, because the decrease is more severe than in thinner cells. Usually, the fill factor under uniformly absorbed red light changes much more than under strongly absorbed blue light. The cause of this is usually assumed to arise from space charge trapped in deep defect states. The authors model this behavior of solar cells using the Analysis of Microelectronic and Photonic Structures (AMPS) simulation program. The simulation shows that the decrease in fill factor is caused by photogenerated space charge trapped in the band-tail states rather than in defects. This charge screens the applied field, reducing the internal field. Owing to its lower drift mobility, the space charge due to holes exceeds that due to electrons and is the main cause of the field screening. The space charge in midgap states is small compared with that in the tails and can be ignored under normal solar-cell operating conditions. Experimentally, the authors measured the photocapacitance as a means to probe the collapsed field. They also explored the light intensity dependence of photocapacitance and explain the decrease of FF with the increasing light intensity.

  18. Plasma heating at collisionless shocks due to the kinetic cross-field streaming instability

    NASA Technical Reports Server (NTRS)

    Winske, D.; Quest, K. B.; Tanaka, M.; Wu, C. S.

    1985-01-01

    Heating at collisionless shocks due to the kinetic cross-field streaming instability, which is the finite beta (ratio of plasma to magnetic pressure) extension of the modified two stream instability, is studied. Heating rates are derived from quasi-linear theory and compared with results from particle simulations to show that electron heating relative to ion heating and heating parallel to the magnetic field relative to perpendicular heating for both the electrons and ions increase with beta. The simulations suggest that electron dynamics determine the saturation level of the instability, which is manifested by the formation of a flattop electron distribution parallel to the magnetic field. As a result, both the saturation levels of the fluctuations and the heating rates decrease sharply with beta. Applications of these results to plasma heating in simulations of shocks and the earth's bow shock are described.

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

  20. 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)

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

    2010-12-01

    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

  1. Revealing giant internal magnetic fields due to spin fluctuations in magnetically doped colloidal nanocrystals

    NASA Astrophysics Data System (ADS)

    Rice, William D.; Liu, Wenyong; Baker, Thomas A.; Sinitsyn, Nikolai A.; Klimov, Victor I.; Crooker, Scott A.

    2016-02-01

    Strong quantum confinement in semiconductors can compress the wavefunctions of band electrons and holes to nanometre-scale volumes, significantly enhancing interactions between themselves and individual dopants. In magnetically doped semiconductors, where paramagnetic dopants (such as Mn2+, Co2+ and so on) couple to band carriers via strong sp-d spin exchange, giant magneto-optical effects can therefore be realized in confined geometries using few or even single impurity spins. Importantly, however, thermodynamic spin fluctuations become increasingly relevant in this few-spin limit. In nanoscale volumes, the statistical fluctuations of N spins are expected to generate giant effective magnetic fields Beff, which should dramatically impact carrier spin dynamics, even in the absence of any applied field. Here we directly and unambiguously reveal the large Beff that exist in Mn2+-doped CdSe colloidal nanocrystals using ultrafast optical spectroscopy. At zero applied magnetic field, extremely rapid (300-600 GHz) spin precession of photoinjected electrons is observed, indicating Beff ˜ 15 -30 T for electrons. Precession frequencies exceed 2 THz in applied magnetic fields. These signals arise from electron precession about the random fields due to statistically incomplete cancellation of the embedded Mn2+ moments, thereby revealing the initial coherent dynamics of magnetic polaron formation, and highlighting the importance of magnetization fluctuations on carrier spin dynamics in nanomaterials.

  2. Highly Effective Conductance Modulation in Planar Silicene Field Effect Devices Due to Buckling.

    PubMed

    Al-Dirini, Feras; Hossain, Faruque M; Mohammed, Mahmood A; Nirmalathas, Ampalavanapillai; Skafidas, Efstratios

    2015-10-06

    Silicene is an exciting two-dimensional material that shares many of graphene's electronic properties, but differs in its structural buckling. This buckling allows opening a bandgap in silicene through the application of a perpendicular electric field. Here we show that this buckling also enables highly effective modulation of silicene's conductance by means of an in-plane electric field applied through silicene side gates, which can be realized concurrently within the same silicene monolayer. We illustrate this by using silicene to implement Self-Switching Diodes (SSDs), which are two-dimensional field effect nanorectifiers realized within a single silicene monolayer. Our quantum simulation results show that the atomically-thin silicene SSDs, with sub-10 nm dimensions, achieve a current rectification ratio that exceeds 200, without the need for doping, representing a 30 fold enhancement over graphene SSDs. We attribute this enhancement to a bandgap opening due to the in-plane electric field, as a consequence of silicene's buckling. Our results suggest that silicene is a promising material for the realization of planar field effect devices.

  3. Highly Effective Conductance Modulation in Planar Silicene Field Effect Devices Due to Buckling

    PubMed Central

    Al-Dirini, Feras; Hossain, Faruque M.; Mohammed, Mahmood A.; Nirmalathas, Ampalavanapillai; Skafidas, Efstratios

    2015-01-01

    Silicene is an exciting two-dimensional material that shares many of graphene’s electronic properties, but differs in its structural buckling. This buckling allows opening a bandgap in silicene through the application of a perpendicular electric field. Here we show that this buckling also enables highly effective modulation of silicene’s conductance by means of an in-plane electric field applied through silicene side gates, which can be realized concurrently within the same silicene monolayer. We illustrate this by using silicene to implement Self-Switching Diodes (SSDs), which are two-dimensional field effect nanorectifiers realized within a single silicene monolayer. Our quantum simulation results show that the atomically-thin silicene SSDs, with sub-10 nm dimensions, achieve a current rectification ratio that exceeds 200, without the need for doping, representing a 30 fold enhancement over graphene SSDs. We attribute this enhancement to a bandgap opening due to the in-plane electric field, as a consequence of silicene’s buckling. Our results suggest that silicene is a promising material for the realization of planar field effect devices. PMID:26441200

  4. Revealing giant internal magnetic fields due to spin fluctuations in magnetically doped colloidal nanocrystals

    DOE PAGES

    Rice, William D.; Liu, Wenyong; Baker, Thomas A.; ...

    2015-11-23

    Strong quantum confinement in semiconductors can compress the wavefunctions of band electrons and holes to nanometre-scale volumes, significantly enhancing interactions between themselves and individual dopants. In magnetically doped semiconductors, where paramagnetic dopants (such as Mn2+, Co2+ and so on) couple to band carriers via strong sp–d spin exchange, giant magneto-optical effects can therefore be realized in confined geometries using few or even single impurity spins. Importantly, however, thermodynamic spin fluctuations become increasingly relevant in this few-spin limit. In nanoscale volumes, the statistical √N fluctuations of N spins are expected to generate giant effective magnetic fields Beff, which should dramatically impactmore » carrier spin dynamics, even in the absence of any applied field. In this paper, we directly and unambiguously reveal the large Beff that exist in Mn2+-doped CdSe colloidal nanocrystals using ultrafast optical spectroscopy. At zero applied magnetic field, extremely rapid (300–600 GHz) spin precession of photoinjected electrons is observed, indicating Beff ~ 15-30 T for electrons. Precession frequencies exceed 2 THz in applied magnetic fields. Finally, these signals arise from electron precession about the random fields due to statistically incomplete cancellation of the embedded Mn2+ moments, thereby revealing the initial coherent dynamics of magnetic polaron formation, and highlighting the importance of magnetization fluctuations on carrier spin dynamics in nanomaterials.« less

  5. Revealing giant internal magnetic fields due to spin fluctuations in magnetically doped colloidal nanocrystals

    SciTech Connect

    Rice, William D.; Liu, Wenyong; Baker, Thomas A.; Sinitsyn, Nikolai A.; Klimov, Victor Ivanovich; Crooker, Scott A.

    2015-11-23

    Strong quantum confinement in semiconductors can compress the wavefunctions of band electrons and holes to nanometre-scale volumes, significantly enhancing interactions between themselves and individual dopants. In magnetically doped semiconductors, where paramagnetic dopants (such as Mn2+, Co2+ and so on) couple to band carriers via strong sp–d spin exchange, giant magneto-optical effects can therefore be realized in confined geometries using few or even single impurity spins. Importantly, however, thermodynamic spin fluctuations become increasingly relevant in this few-spin limit. In nanoscale volumes, the statistical √N fluctuations of N spins are expected to generate giant effective magnetic fields Beff, which should dramatically impact carrier spin dynamics, even in the absence of any applied field. In this paper, we directly and unambiguously reveal the large Beff that exist in Mn2+-doped CdSe colloidal nanocrystals using ultrafast optical spectroscopy. At zero applied magnetic field, extremely rapid (300–600 GHz) spin precession of photoinjected electrons is observed, indicating Beff ~ 15-30 T for electrons. Precession frequencies exceed 2 THz in applied magnetic fields. Finally, these signals arise from electron precession about the random fields due to statistically incomplete cancellation of the embedded Mn2+ moments, thereby revealing the initial coherent dynamics of magnetic polaron formation, and highlighting the importance of magnetization fluctuations on carrier spin dynamics in nanomaterials.

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  7. Model based estimation of image depth and displacement

    NASA Technical Reports Server (NTRS)

    Damour, Kevin T.

    1992-01-01

    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

  8. Near-Field Integration of a SiN Nanobeam and a SiO2 Microcavity for Heisenberg-Limited Displacement Sensing

    NASA Astrophysics Data System (ADS)

    Schilling, R.; Schütz, H.; Ghadimi, A. H.; Sudhir, V.; Wilson, D. J.; Kippenberg, T. J.

    2016-05-01

    Placing a nanomechanical object in the evanescent near field of a high-Q optical microcavity gives access to strong gradient forces and quantum-limited displacement readout, offering an attractive platform for both precision sensing technology and basic quantum optics research. Robustly implementing this platform is challenging, however, as it requires integrating optically smooth surfaces separated by ≲λ /10 . Here we describe an exceptionally high-cooperativity, single-chip optonanomechanical transducer based on a high-stress Si3N4 nanobeam monolithically integrated into the evanescent near field of SiO2 microdisk cavity. Employing a vertical integration technique based on planarized sacrificial layers, we realize beam-disk gaps as little as 25 nm while maintaining mechanical Q f >1012 Hz and intrinsic optical Q ˜107. The combination of low loss, small gap, and parallel-plane geometry results in radio-frequency flexural modes with vacuum optomechanical coupling rates of 100 kHz, single-photon cooperativities in excess of unity, and large zero-point frequency (displacement) noise amplitudes of 10 kHz (fm )/√ Hz . In conjunction with the high power-handling capacity of SiO2 and low extraneous substrate noise, the transducer performs particularly well as a sensor, with recent deployment in a 4-K cryostat realizing a displacement imprecision 40 dB below that at the standard quantum limit (SQL) and an imprecision-backaction product <5 ℏ [Wilson et al., Nature (London) 524, 325 (2015)]. In this report, we provide a comprehensive description of device design, fabrication, and characterization, with an emphasis on extending Heisenberg-limited readout to room temperature. Towards this end, we describe a room-temperature experiment in which a displacement imprecision 32 dB below that at the SQL and an imprecision-backaction product <60 ℏ is achieved. Our results extend the outlook for measurement-based quantum control of nanomechanical oscillators and suggest an

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

    NASA Technical Reports Server (NTRS)

    Nedoluha, Gerald E.; Watson, William D.

    1990-01-01

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

  10. Enhancement of threshold electric field for relativistic runaway electrons due to magnetic fluctuation and synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Li, Shucai; Wang, Lu; Chen, Zhongyong; Huang, Duwei; Tong, Ruihai

    2016-10-01

    The dynamics of relativistic electrons are analyzed using the relativistic Fokker-Planck equation including deceleration due to synchrotron radiation (SR) and radial diffusion loss caused by magnetic fluctuation (MF). Threshold electric field for avalanche growth is enhanced, and the growth rate is reduced by the combined effect of MF and SR as compared to the case with only SR. The threshold electric field is determined by the time scales balance between momentum evolution and radial diffusion loss induced by MF, and increased with level of MF. More importantly, the hysteresis behavior of runaway pointed out by does not exist anymore. This is because the ``seed electrons'' cannot be sustained as a result of diffusion loss. This work was supported by NSFC Grant No. 11305071, and the Ministry of Science and technology of China, under Contract Nos. 2013GB112002, 2015GB111002 and 2015GB111001.

  11. Absence of Remote Triggering in Geothermal Fields Due to Human Activity

    NASA Astrophysics Data System (ADS)

    Ge, S.; Zhang, Q.; Lin, G.

    2014-12-01

    Operational geothermal fields typically have high seismicity rates, which could be caused by both tectonic and anthropogenic activities. Due to the high background seismicity and possible interaction between fluid and seismic waves, geothermal areas have been recognized to be susceptible to large remote earthquakes. However, whether human activity (geothermal production) affects remote earthquake triggering by changing the stress state is unclear. Here we choose two geothermal fields, Coso and Salton Sea in southern California, to study the spatiotemporal distributions of the triggered earthquakes following the 1992 Mw 7.3 Landers and 1999 Mw 7.1 Hector Mine earthquakes. These two geothermal fields have been in operation since 1980s with comparable net capacity, and have long-term geothermal fluid loss. By analyzing the regional catalog recorded by the Southern California Seismic Network, we find that these two operational geothermal areas remain unaffected by the remote mainshocks, whereas the surrounding areas show vigorous triggered responses. We interpret this phenomenon as a result of human activity, which presumably has brought the stress state away from failure by reducing pore pressure. To further understand how much the human activity can affect the stress state, we also conduct a systematic study on Long Valley Caldera in northern California as a comparison site. Long Valley Caldera hosts an active geothermal field with net capacity about one sixth of that in Coso or Salton Sea geothermal field, and the extraction volume is not constantly larger than the injection. We will show comparisons of the triggered response in Long Valley with the two geothermal fields in southern California.

  12. Temperature fields due to jet induced mixing in a typical OTV tank

    NASA Technical Reports Server (NTRS)

    Hochstein, J. I.; Ji, Hyun-Chul; Aydelott, J. C.

    1987-01-01

    The Eclipse Code is being developed as a general tool for analysis of cryogenic propellant behavior in spacecraft tankage. The focus of the work being reported is on prediction of temperature fields due to introduction of a cold jet along the centerline of a typical Orbit Transfer Vehicle tank. A brief description of the formulations used for modeling heat transfer and turbulent flow is presented. Code performance is verified through comparison to experimental data for mixing in small scale tanks. An unexpected difficulty in computing long duration flows is reviewed. Preliminary results for a partially filled full scale tank are obtained by approximating the free surface by a spherical solid boundary.

  13. Dispersive FDTD analysis of induced electric field in human models due to electrostatic discharge.

    PubMed

    Hirata, Akimasa; Nagai, Toshihiro; Koyama, Teruyoshi; Hattori, Junya; Chan, Kwok Hung; Kavet, Robert

    2012-07-07

    Contact currents flow from/into a charged human body when touching a grounded conductive object. An electrostatic discharge (ESD) or spark may occur just before contact or upon release. The current may stimulate muscles and peripheral nerves. In order to clarify the difference in the induced electric field between different sized human models, the in-situ electric fields were computed in anatomically based models of adults and a child for a contact current in a human body following ESD. A dispersive finite-difference time-domain method was used, in which biological tissue is assumed to obey a four-pole Debye model. From our computational results, the first peak of the discharge current was almost identical across adult and child models. The decay of the induced current in the child was also faster due mainly to its smaller body capacitance compared to the adult models. The induced electric fields in the forefingers were comparable across different models. However, the electric field induced in the arm of the child model was found to be greater than that in the adult models primarily because of its smaller cross-sectional area. The tendency for greater doses in the child has also been reported for power frequency sinusoidal contact current exposures as reported by other investigators.

  14. Magnetic field shift due to mechanical vibration in functional magnetic resonance imaging.

    PubMed

    Foerster, Bernd U; Tomasi, Dardo; Caparelli, Elisabeth C

    2005-11-01

    Mechanical vibrations of the gradient coil system during readout in echo-planar imaging (EPI) can increase the temperature of the gradient system and alter the magnetic field distribution during functional magnetic resonance imaging (fMRI). This effect is enhanced by resonant modes of vibrations and results in apparent motion along the phase encoding direction in fMRI studies. The magnetic field drift was quantified during EPI by monitoring the resonance frequency interleaved with the EPI acquisition, and a novel method is proposed to correct the apparent motion. The knowledge on the frequency drift over time was used to correct the phase of the k-space EPI dataset. Since the resonance frequency changes very slowly over time, two measurements of the resonance frequency, immediately before and after the EPI acquisition, are sufficient to remove the field drift effects from fMRI time series. The frequency drift correction method was tested "in vivo" and compared to the standard image realignment method. The proposed method efficiently corrects spurious motion due to magnetic field drifts during fMRI.

  15. The successive displacement process: Oil recovery during blowdown

    SciTech Connect

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

    1996-12-31

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

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

    NASA Technical Reports Server (NTRS)

    Peltzer, G.; Crampe, F.

    1998-01-01

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

  17. RTV 21 Displacements

    SciTech Connect

    Kurita, C.H.; /Fermilab

    1987-02-04

    A seal is needed for the cover of the Nitrogen Test Vessel in order to prevent leakage of the N{sub 2} gas. This seal is to be molded out of RTV 21. In this experiment, the Modulus of Elasticity of the RTV was sought after, and the displacements of the RTV due to various stresses were measured to see if they were large enough to provide a tight seal between the vessel and its cover.

  18. Measuring vulnerability to disaster displacement

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    aggregate these ideas into a framework of disaster displacement vulnerability that distinguishes between three main aspects of disaster displacement. Disaster displacement can be considered in terms of the number of displaced people and the length of that displacement. However, the literature emphasizes that the severity of disaster displacement can not be measured completely in quantitative terms. Thus, we include a measure representing people who are trapped and unable to leave their homes due to mobility, resources or for other reasons. Finally the third main aspect considers the difficulties that are associated with displacement and reflects the difference between the experiences of those who are displaced into safe and supportive environments as compared to those whose only alternate shelter is dangerous and inadequate for their needs. Finally, we apply the framework to demonstrate a methodology to estimate vulnerability to disaster displacement. Using data from the Global Earthquake Model (GEM) Social and Economic Vulnerability sub-National Database, we generate an index to measure the vulnerability of Japanese prefectures to the dimensions of displacement included in the framework. References Yonitani, M. (2014). Global Estimates 2014: People displaced by disasters. http://www.internal-displacement.org/publications/2014/global-estimates-2014-people-displaced-by-disasters/

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

    USGS Publications Warehouse

    Lee, M.W.

    1987-01-01

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

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed Central

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

    1999-01-01

    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. PMID:10354428

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

    PubMed Central

    Bigeleisen, Jacob

    1998-01-01

    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. PMID:9560183

  3. Electron spin relaxation due to reorientation of a permanent zero field splitting tensor.

    PubMed

    Schaefle, Nathaniel; Sharp, Robert

    2004-09-15

    Electron spin relaxation of transition metal ions with spin S> or =1 results primarily from thermal modulation of the zero field splitting (zfs) tensor. This occurs both by distortion of the zfs tensor due to intermolecular collisions and, for complexes with less than cubic symmetry, by reorientational modulation of the permanent zfs tensor. The reorientational mechanism is much less well characterized in previous work than the distortional mechanism although it is an important determinant of nuclear magnetic resonance (NMR) paramagnetic relaxation enhancement phenomena (i.e., the enhancement of NMR relaxation rates produced by paramagnetic ions in solution or NMR-PRE). The classical density matrix theory of spin relaxation does not provide an appropriate description of the reorientational mechanism at low Zeeman field strengths because the zero-order spin wave functions are stochastic functions of time. Using spin dynamics simulation techniques, the time correlation functions of the spin operators have been computed and used to determine decay times for the reorientational relaxation mechanism for S=1. In the zfs limit of laboratory field strengths (H(Zeem)field strengths where H(Zeem) approximately H(zfs) (composite function), and in the vicinity of the Zeeman limit. The results demonstrate that the reorientational electron spin relaxation mechanism is often significant when H(zfs) (composite function)> or =H(Zeem), and that its neglect

  4. On the determination of missing boundary data for solids with nonlinear material behaviors, using displacement fields measured on a part of their boundaries

    NASA Astrophysics Data System (ADS)

    Andrieux, Stéphane; Baranger, Thouraya N.

    2016-12-01

    The paper is devoted to the derivation of a numerical method for expanding available mechanical fields (stress vector and displacements) on a part of the boundary of a solid into its interior and up to unreachable parts of its boundary (with possibly internal surfaces). This expansion enables various identification or inverse problems to be solved in mechanics. The method is based on the solution of a nonlinear elliptic Cauchy problem because the mechanical behavior of the solid is considered as nonlinear (hyperelastic or elastoplastic medium). Advantage is taken of the assumption of convexity of the potentials used for modeling the constitutive equation, encompassing previous work by the authors for linear elastic solids, in order to derive an appropriate error functional. Two illustrations are given in order to evaluate the overall efficiency of the proposed method within the framework of small strains and isothermal transformation.

  5. Small scale changes of geochemistry and flow field due to transient heat storage in aquifers

    NASA Astrophysics Data System (ADS)

    Bauer, S.; Boockmeyer, A.; Li, D.; Beyer, C.

    2013-12-01

    Heat exchangers in the subsurface are increasingly installed for transient heat storage due to the need of heating or cooling of buildings as well as the interim storage of heat to compensate for the temporally fluctuating energy production by wind or solar energy. For heat storage to be efficient, high temperatures must be achieved in the subsurface. Significant temporal changes of the soil and groundwater temperatures however effect both the local flow field by temperature dependent fluid parameters as well as reactive mass transport through temperature dependent diffusion coefficients, geochemical reaction rates and mineral equilibria. As the use of heat storage will be concentrated in urban areas, the use of the subsurface for (drinking) water supply and heat storage will typically coincide and a reliable prognosis of the processes occurring is needed. In the present work, the effects of a temporal variation of the groundwater temperature, as induced by a local heat exchanger introduced into a groundwater aquifer, are studied. For this purpose, the coupled non-isothermal groundwater flow, heat transport and reactive mass transport is simulated in the near filed of such a heat exchanger. By explicitly discretizing and incorporating the borehole, the borehole cementation and the heat exchanger tubes, a realistic geometrical and process representation is obtained. The numerical simulation code OpenGeoSys is used in this work, which incorporates the required processes of coupled groundwater flow, heat and mass transport as well as temperature dependent geochemistry. Due to the use of a Finite Element Method, a close representation of the geometric effects can be achieved. Synthetic scenario simulations for typical settings of salt water formations in northern Germany are used to investigate the geochemical effects arising from a high temperature heat storage by quantifying changes in groundwater chemistry and overall reaction rates. This work presents the

  6. Displacement Compensation of Temperature Probe Data

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

    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.

  7. Estimation of Surface Roughness due to Electrode Erosion in Field-Distortion Gas Switch

    NASA Astrophysics Data System (ADS)

    Liu, Xuandong; Wang, Hu; Li, Xiaoang; Zhang, Qiaogen; Wei, Jin; Qiu, Aici

    2013-08-01

    Field distortion gas switch is one of the crucial elements in a Marx generator, fast linear transformer driver and other pulsed power installations. The performance of the gas switch, which is dramatically affected by the surface roughness due to electrode erosion during the discharge process, directly influences the output parameters, stability and reliability of the pulsed power system. In this paper, an electrode surface roughness (ESR) calculation model has been established based on a great deal of experimental data under operating current. The discharge current waveform, the peak height of the burr, the radius and the depth of etch pits in the electrode erosion region were used to predict the ESR. Also, experimental results indicate that this calculation model can effectively estimate the ESR of the test gas switch.

  8. Lateral displacement and rotational displacement sensor

    DOEpatents

    Duden, Thomas

    2014-04-22

    A position measuring sensor formed from opposing sets of capacitor plates measures both rotational displacement and lateral displacement from the changes in capacitances as overlapping areas of capacitors change. Capacitances are measured by a measuring circuit. The measured capacitances are provided to a calculating circuit that performs calculations to obtain angular and lateral displacement from the capacitances measured by the measuring circuit.

  9. Solar Wind Slowdown Due to Dust Pickup during Interplanetary Field Enhancements

    NASA Astrophysics Data System (ADS)

    Lai, Hairong; Russell, Christopher; Wei, Hanying

    2013-04-01

    The interplanetary field enhancements (IFEs) are characterized by their cusp-shaped enhancement in the magnetic field magnitude. They are observed throughout the inner solar system from 0.72AU by Pioneer Venus Orbiter to 5AU by Ulysses. The annual IFE rate is ten at 0.72AU and around eight at 1AU, i.e., decreases as the heliocentric distance increases. Multiple-spacecraft observations show that IFEs are moving radially away from the Sun at nearly the ambient solar wind speed. During the IFE events, case studies show that while there are correlated diamagnetic compensations in pressure there are no significant correlated changes in the solar wind speed. An IFE formation mechanism that explains most of the IFE features is that IFEs result from interactions between solar wind and clouds of picked up nanoscale charged dust, which is released in interplanetary collisions between objects of 10 to 1000m in diameter. The enhanced magnetic field behaves as a magnetic barrier that can transfer momentum to the charged dust from the solar wind. Momentum lifts the dust outward in the solar gravitational well. A prediction of this hypothesis is that solar wind will be slowed down even when the IFEs have reached exactly the solar wind speed. To test this hypothesis, we perform a superposed analysis on the radial velocity of IFEs observed at 1AU. In contrast to the case studies, the statistical results have a significant change in speed. The velocity on the solar wind side of the IFEs is smaller than the ambient velocity. This slowdown increases for larger IFEs with larger estimated mass. In addition, the amount of momentum due to the solar wind slowdown is quantitatively consistent with the momentum expected to be needed to lift the dust out of the Sun's gravitational potential well, which is in strong support of our IFE formation mechanism.

  10. InSAR data as a field guide for mapping minor earthquake surface ruptures: Ground displacements along the Paganica Fault during the 6 April 2009 L'Aquila earthquake

    NASA Astrophysics Data System (ADS)

    Guerrieri, L.; Baer, G.; Hamiel, Y.; Amit, R.; Blumetti, A. M.; Comerci, V.; di Manna, P.; Michetti, A. M.; Salamon, A.; Mushkin, A.; Sileo, G.; Vittori, E.

    2010-12-01

    On 6 April 2009, a moderate earthquake (Mw = 6.3; Ml = 5.8) struck the Abruzzo region in central Italy, causing more than 300 fatalities and heavy damage to L'Aquila and surrounding villages. Coseismic surface effects have been thoroughly documented by timely field surveys as well as by remote sensing analyses of satellite images. The outstanding quality of geological, seismological, geodetic, and interferometric synthetic aperture radar (InSAR) information arguably represents the best ever data set made available immediately after a moderate seismic event. Based on this data set, we aim at testing the capability of coupled geological and InSAR data to map surface faulting patterns associated with moderate earthquakes. Coseismic ground ruptures have been mapped at a scale of 1:500 in the whole epicentral area. Traces of surface ruptures have been inferred from linear phase discontinuities identified in the interferogram. A very good agreement between the two methods resulted in the characterization of the main surface rupture along the Paganica fault. The same approach applied to ground ruptures hypothesized along other capable fault segments provided more questionable results. Thus, the combined field and InSAR approach appeared useful for detecting continuous surface ruptures exceeding 1 km in length and showing displacements greater than a few centimeters. These are the typical faulting parameters for moderate earthquakes (6.0 < Mw < 6.5) in central Apennines. For continuous ground cracks shorter than a few hundred meters and/or that show displacements smaller than 1-2 cm, the described approach may be less helpful, most probably due to the limited resolution of the data.

  11. Lucky interferometry for displacement measurement

    NASA Astrophysics Data System (ADS)

    Ioniţă, Bogdan; Logofătu, Petre Cătălin; Apostol, Dan

    2009-11-01

    We extrapolated the lucky imaging technique, mostly used in astronomy, to the field of interferometry for displacement measurement. From the batch of interferograms generated by a Twyman-Green-type interferometer and acquired by a CCD camera, those with high overall contrast were selected and fitted to a sinusoidal function. The high-contrast interferograms showed a significantly lower dispersion and, consequently, a lower uncertainty of the measured displacement.

  12. Evanescent field enhancement due to plasmonic resonances of a metamaterial slab.

    PubMed

    Chiu, K P; Kao, T S; Tsai, D P

    2008-02-01

    The characteristics of plasmonic resonance in a dielectric-sandwiched metamaterial film at visible wavelengths of 650 and 568 nm have been investigated (for both p- and s-polarized light). Our calculated results demonstrate that each mode of plasmonic resonance has maximum resonance strength at a particular film thickness of the metamaterial. We also demonstrated that the effect of evanescent field enhancement is due to plasmonic resonances of the sandwiched metamaterial system. And the stronger the plasmonic resonance strength the larger the evanescent field is enhanced at the interfaces of the metamaterial film. Also we see that the plasmonic resonances in a sandwiched metamaterial are influenced not only by the materials that constitute the interfaces but also by the thickness of surrounding dielectrics or distance between evanescent light source and metamaterial film. Finally, our results show that there might be an effective light propagation length that will let the coupling efficiency between evanescent light source and SPs resonance become a maximum. These properties of plasmonic resonances to structure parameters of metamaterial film and its surrounding dielectrics provide a useful way to control the optical responses of an optoelectronic device when the wavelength of light source is fixed. That is, by suitably choosing light polarizations, thickness of the metamaterial thin film or the surrounding dielectrics and the position of evanescent light source, it is possible to modulate the plasmonic resonance wavenumber or resonance strength of the system. Therefore, the optical responses of the system can be modulated. Our results will be helpful for the structure design to control the behaviours of coupled plasmonic resonances and consequently the optical properties of the dielectric-sandwiched metamaterial film.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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 μg 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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 μg 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

    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 µg 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 has same significance compared to the ensemble mean.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    A number of published studies use seismic sensors to understand the physics involved in slope deformation. In this research we artificially induce failure to two meter scaled slopes in the field and use 12 short period 3D seismometers to monitor the failure. To our knowledge there has been no previous controlled experiments that can allow calibration and validation of the interpreted seismic signals. Inside the body of one of the artificial landslides we embed a pile of glass shards. During movement the pile deforms emitting seismic signals due to friction among the glass shards. Our aim is twofold: First we investigate whether the seismic sensors can record pre-cursory and failure signals. Secondly, we test our hypothesis that the glass shards produce seismic signals with higher amplitudes and a distinct frequency pattern, compared to those emitted by common landslide seismicity and local background noise. Two vertical faces, 2m high, were excavated 3m apart in high porous tropical clay. This highly attenuating material makes the detection of weak seismic signals challenging. Slope failure was induced by increasing the vertical load at the landslide's crown. Special care was taken in the design of all experimental procedures to not add to the area's seismic noise. Measurements took place during 18 hours (during afternoon and night) without any change in soil and weather conditions. The 3D sensors were placed on the ground surface close to the crown, forming a dense microseismic network with 5-to-10m spacing and two nanoseismic arrays, with aperture sizes of 10 and 20 m. This design allowed a direct comparison of the recorded signals emitted by the two landslides. The two faces failed for loading between 70 and 100kN and as a result the pile of glass shards was horizontally deformed allowing differential movement between the shards. After the main failure both landslides were continuing to deform due to soil compaction and horizontal displacement. We apply signal

  17. Is Maxwell's Displacement Current a Current?

    ERIC Educational Resources Information Center

    French, A. P.

    2000-01-01

    Discusses in detail the claim that certain well-known physics experiments demonstrate the magnetic field produced by Maxwell's displacement current. Addresses the question of whether the displacement current acts as a source of magnetic field in the same way as a current in a wire would. (Contains 12 references.) (WRM)

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  19. Inner Core Anisotropy Due to the Magnetic Field--induced Preferred Orientation of Iron.

    PubMed

    Karato, S

    1993-12-10

    Anisotropy of the inner core of the Earth is proposed to result from the lattice preferred orientation of anisotropic iron crystals during their solidification in the presence of a magnetic field. The resultant seismic anisotropy is related to the geometry of the magnetic field in the core. This hypothesis implies that the observed anisotropy (fast velocity along the rotation axis) indicates a strong toroidal field in the core, which supports a strong field model for the geodynamo if the inner core is made of hexagonal close-packed iron.

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

    DOE PAGES

    Moore, Michael H.; Waidyawansa, Buddhini P.; Covrig, Silviu; ...

    2014-11-05

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

  1. Electromagnetic fields in the human body due to switched transverse gradient coils in MRI.

    PubMed

    While, Peter T; Forbes, Larry K

    2004-07-07

    Magnetic resonance imaging scans impose large gradient magnetic fields on the patient. Modern imaging techniques require this magnetic field to be switched rapidly for good resolution. However, it is believed that this can also lead to the unwanted side effect of peripheral nerve stimulation, which proves to be a limiting factor to the advancement of MRI technology. This paper establishes an analytical model for the fields produced within an MRI scanner by transverse gradient coils of known current density. Expressions are obtained for the magnetic induction vector and the electric field vector, as well as for the surface charge and current densities that are induced on the patient's body. The expressions obtained are general enough to allow the study of any combination of gradient coils whose behaviour can be approximated by Fourier series. For a realistic example coil current density and switching function, it is found that spikes of surface charge density are induced on the patient's body as the gradient field is switched, as well as loops of surface current density that mimic the coil current density. For a 10 mT m(-1) gradient field with a rise time of 100 micros, the magnitude of the radial electric field at the body is found to be 10.3 V m(-1). It is also found that there is a finite limit to radial electric field strength as rise time approaches zero.

  2. Flute stabilization due to ponderomotive force created by an rf field with a variable gradient

    SciTech Connect

    Yasaka, Y.; Itatani, R.

    1986-06-30

    An rf-stabilization experiment was performed in the axisymmetric single-mirror device HIEI by controlling the radial-gradient scale length of the rf field with the aid of an azimuthally phased antenna array. The flute stability depends sensitively on the scale length of the perpendicular rf electric field, which shows that rf stabilization is caused by the ponderomotive force for ions.

  3. Nontrivial excited-state coherence due to two uncorrelated partially coherent fields

    NASA Astrophysics Data System (ADS)

    Sadeq, Z. S.

    2015-04-01

    We analyze a model where a closed V system is excited by two uncorrelated partially coherent fields. We use a collisionally broadened cw laser, which is a good model for an experimentally realizable partially coherent field, and show that it is possible to generate excited-state coherences even if the two fields are uncorrelated. This transient coherence can be increased if splitting between the excited states is reduced relative to the radiation coherence time τd. For small excited-state splitting, one can use this scheme to generate a long-lived coherent response in the system.

  4. Study on magnetic field deviation due to manufacturing errors of the SIS100 superconducting dipole magnet

    NASA Astrophysics Data System (ADS)

    Sugita, Kei; Fischer, Egbert; Mierau, Anna; Roux, Christian; Schnizer, Pierre

    2016-12-01

    An international accelerator project, Facility for Antiproton and Ion Research in Europe (FAIR), is being constructed at Darmstadt, Germany. Central part of the accelerator chain is a superconducting heavy ion synchrotron SIS100, which accelerates injected particles from existing synchrotron SIS18, and provides them to experiment sites and further accelerators. Superconducting magnets in SIS100 are mainly superferric magnet with a Nuclotron cable. After R&D, the First of Series (FoS) main dipole magnet has been manufactured and tested successfully. However, magnetic field quality is unsatisfactory. We report on the investigation of the magnetic field quality by means of magnetic field measurements, geometrical measurements, and electromagnetic simulations.

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    2014-09-05

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

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

    SciTech Connect

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

    2013-12-04

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

  8. Alignment of Iron Nanoparticles in a Magnetic Field Due to Shape Anisotropy

    SciTech Connect

    Radhakrishnan, Balasubramaniam; Nicholson, Don M; Eisenbach, Markus; Ludtka, Gerard Michael; Rios, Orlando; Parish, Chad M

    2015-07-09

    During high magnetic field processing there is evidence for alignment of non-spherical metallic particles above the Curie temperature in alloys with negligible magneto-crystalline anisotropy. The main driving force for alignment is the magnetic shape anisotropy. Current understanding of the phenomenon is not adequate to quantify the effect of particle size, aspect ratio, temperature and the magnetic field on particle alignment. We demonstrate a Monte Carlo approach coupled with size scaling to show the conditions under which alignment is possible.

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

    SciTech Connect

    Long, Andrew J.; Vachaspati, Tanmay E-mail: tvachasp@asu.edu

    2015-09-01

    We study the characteristic size and shape of idealized blazar-induced cascade halos in the 1–100,GeV energy range assuming various non-helical and helical configurations for the intergalactic magnetic field (IGMF). While the magnetic field creates an extended halo, the helicity provides the halo with a twist. Under simplifying assumptions, we assess the parameter regimes for which it is possible to measure the size and shape of the halo from a single source and then to deduce properties of the IGMF. We find that blazar halo measurements with an experiment similar to Fermi-LAT are best suited to probe a helical magnetic field with strength and coherence length today in the ranges 10{sup −17} ∼< B{sub 0} / Gauss ∼< 10{sup −13} and 10 Mpc ∼< λ ∼< 10 Gpc where H ∼ B{sub 0}{sup 2} / λ is the magnetic helicity density. Stronger magnetic fields or smaller coherence scales can still potentially be investigated, but the connection between the halo morphology and the magnetic field properties is more involved. Weaker magnetic fields or longer coherence scales require high photon statistics or superior angular resolution.

  10. A blood-oxygenation-dependent increase in blood viscosity due to a static magnetic field.

    PubMed

    Yamamoto, Toru; Nagayama, Yuki; Tamura, Mamoru

    2004-07-21

    As the magnetic field of widely used MR scanners is one of the strongest magnetic fields to which people are exposed, the biological influence of the static magnetic field of MR scanners is of great concern. One magnetic interaction in biological subjects is the magnetic torque on the magnetic moment induced by biomagnetic substances. The red blood cell is a major biomagnetic substance, and the blood flow may be influenced by the magnetic field. However, the underlying mechanisms have been poorly understood. To examine the mechanisms of the magnetic influence on blood viscosity, we measured the time for blood to fall through a glass capillary inside and outside a 1.5 T MR scanner. Our in vitro results showed that the blood viscosity significantly increased in a 1.5 T MR scanner, and also clarified the mechanism of the interaction between red blood cells and the external magnetic field. Notably, the blood viscosity increased depending on blood oxygenation and the shear rate of the blood flow. Thus, our findings suggest that even a 1.5 T magnetic field may modulate blood flow.

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

    NASA Astrophysics Data System (ADS)

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

    2008-04-01

    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.

  12. Cosmic parity violation due to a flavor-space locked gauge field

    NASA Astrophysics Data System (ADS)

    Caldwell, Robert

    2016-05-01

    A flavor-space locked gauge field is shown to behave like a birefringent medium, imparting a preferred left- or right-circular polarization onto gravitational waves. In a cosmological scenario, such a gauge field can cause a primordial spectrum of gravitational waves to develop a net handedness. The degree of chiral asymmetry depends on the wavelength, the abundance of the gauge field, and the strength of the gauge coupling. An asymmetry in the gravitational wave spectrum would be imprinted on the photon polarization pattern of the cosmic microwave background at last scattering. In this scenario, cosmic parity violation is written on the sky, as we predict nonzero correlation of the curl polarization with the temperature, as well as curl with gradient polarization. We compare this phenomena with parity violation in models of chiral gravity, in which the chiral asymmetry is primordial, and with models of quintessence cosmic birefringence, in which parity-violating correlations are induced along the line of sight.

  13. Formation of electric dipoles in pea stem tissue due to an electric field

    NASA Astrophysics Data System (ADS)

    Ahmadi, Fatemeh; Farahani, Elham

    2016-07-01

    For examining the effect of an electrical field (DC) on pea seed, we exposed the pea seeds to electric fields with intensities 1, 4 and 7 kV/cm for 30, 230, 430 and 630 seconds. The tests were repeated three times, and each iteration had 5 seeds. Then, the seeds were moved to packaged plates. Finally, microscopic observation of the pea stem tissue showed that the application of a DC electrical field caused a deformation in the pea stem tissue. The results led us to examine the deformation of the tissue theoretically and to address that deformation as an electrostatic problem. In this regard, we modeled the pea stem based on the formation of electric dipoles. Then, theoretically, we calculated the force acting on each xylem section by coding, and the results were consistent with the experimental data.

  14. Infrared near-field detection of a narrow resonance due to molecular vibrations in a nanoparticle

    SciTech Connect

    Romanov, Vyacheslav; Walker, G.C.

    2007-02-27

    Di-iron nonacarbonyl particles on a gold surface have been imaged using an apertureless near-field scanning infrared microscopy. First and second harmonic detection, with and without an auto-homodyning option, have been used to collect the near-field spectrum of a single vibrational mode of the bridging carbonyls in di-iron nonacarbonyl nanocrystalline flakes on a gold surface. The experimental results have been compared to two theoretical models, a static image-dipole effective medium and an image dipole modified by a Fresnel coefficient for the appropriate observation angle. The calculations have taken into account the roughness of the gold film. The phase dependence of the near-field contrast has been investigated using broadband and tunable CO2 lasers. Particle size effects on contrast and spatial resolution have been studied to determine the limits of applicability of the half-space approximation.

  15. Neoclassical Drift of Circulating Orbits Due toToroidal Electric Field in Tokamaks

    SciTech Connect

    Hong, Qin; Guan, Xiaoyin; Fisch, Nathaniel J.

    2011-07-19

    In tokamaks, Ware pinch is a well known neoclassical effect for trapped particles in response to a toroidal electric field. It is generally believed that there exists no similar neoclassical effect for circulating particles without collisions. However, this belief is erroneous, and misses an important effect. We show both analytically and numerically that under the influence of a toroidal electric field parallel to the current, the circulating orbits drift outward toward the outer wall with a characteristic velocity O ({var_epsilon}{sup -1}) larger than the E x B velocity, where {var_epsilon} is the inverse aspect-ratio of a tokamak. During a RF overdrive, the toroidal electric field is anti-parallel to the current. As a consequence, all charged particles, including backward runaway electrons, will drift inward towards the inner wall.

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

    NASA Technical Reports Server (NTRS)

    Fatuzzo, Marco; Melia, Fulvio

    1991-01-01

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

  17. Seismic fragility analysis of typical pre-1990 bridges due to near- and far-field ground motions

    NASA Astrophysics Data System (ADS)

    Mosleh, Araliya; Razzaghi, Mehran S.; Jara, José; Varum, Humberto

    2016-03-01

    Bridge damages during the past earthquakes caused several physical and economic impacts to transportation systems. Many of the existing bridges in earthquake prone areas are pre-1990 bridges and were designed with out of date regulation codes. The occurrences of strong motions in different parts of the world show every year the vulnerability of these structures. Nonlinear dynamic time history analyses were conducted to assess the seismic vulnerability of typical pre-1990 bridges. A family of existing concrete bridge representative of the most common bridges in the highway system in Iran is studied. The seismic demand consists in a set of far-field and near-field strong motions to evaluate the likelihood of exceeding the seismic capacity of the mentioned bridges. The peak ground accelerations (PGAs) were scaled and applied incrementally to the 3D models to evaluate the seismic performance of the bridges. The superstructure was assumed to remain elastic and the nonlinear behavior in piers was modeled by assigning plastic hinges in columns. In this study the displacement ductility and the PGA are selected as a seismic performance indicator and intensity measure, respectively. The results show that pre-1990 bridges subjected to near-fault ground motions reach minor and moderate damage states.

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

    PubMed

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

    2012-02-13

    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 blueshifted maximal field enhancements near hybridized plasmonic dimer resonances that are still large but nearly two times smaller than in the usual local-response description. For the same geometry at a fixed frequency, the field enhancement and cross section can also be significantly more enhanced in the nonlocal-response model.

  19. Enhanced excitonic photoconductivity due to built-in internal electric field in TlGaSe{sub 2} layered semiconductor

    SciTech Connect

    Seyidov, MirHasan Yu. Suleymanov, Rauf A.; Şale, Yasin; Balaban, Ertan

    2014-12-07

    The strong enhancement, by several orders of magnitude, of the excitonic peak within the photoconductivity spectrum of TlGaSe{sub 2} semiconductor was observed. The samples were polarized in external dc electric field, which was applied prior to the measurements. Due to the accumulation of charges near the surface, an internal electric field was formed. Electron-hole pairs that were created after the absorption of light are fallen in and then separated by the built-in electric field, which prevents radiative recombination process.

  20. Modelling of 3D fields due to ferritic inserts and test blanket modules in toroidal geometry at ITER

    NASA Astrophysics Data System (ADS)

    Liu, Yueqiang; Äkäslompolo, Simppa; Cavinato, Mario; Koechl, Florian; Kurki-Suonio, Taina; Li, Li; Parail, Vassili; Saibene, Gabriella; Särkimäki, Konsta; Sipilä, Seppo; Varje, Jari

    2016-06-01

    Computations in toroidal geometry are systematically performed for the plasma response to 3D magnetic perturbations produced by ferritic inserts (FIs) and test blanket modules (TBMs) for four ITER plasma scenarios: the 15 MA baseline, the 12.5 MA hybrid, the 9 MA steady state, and the 7.5 MA half-field helium plasma. Due to the broad toroidal spectrum of the FI and TBM fields, the plasma response for all the n  =  1-6 field components are computed and compared. The plasma response is found to be weak for the high-n (n  >  4) components. The response is not globally sensitive to the toroidal plasma flow speed, as long as the latter is not reduced by an order of magnitude. This is essentially due to the strong screening effect occurring at a finite flow, as predicted for ITER plasmas. The ITER error field correction coils (EFCC) are used to compensate the n  =  1 field errors produced by FIs and TBMs for the baseline scenario for the purpose of avoiding mode locking. It is found that the middle row of the EFCC, with a suitable toroidal phase for the coil current, can provide the best correction of these field errors, according to various optimisation criteria. On the other hand, even without correction, it is predicted that these n  =  1 field errors will not cause substantial flow damping for the 15 MA baseline scenario.

  1. Energy conversion of the flare due to direct electric fields from the sheared reconnection

    NASA Astrophysics Data System (ADS)

    Hirayama, T.

    In this paper we present a new mechanism of the main energy conversion of the solar flare. Since a flare inducing prominence (flux tube) rises Vz ⩽ 300 km s-1, the plasmas below it cannot continuously eject with Alfvén speeds of VA = 3000 km s-1 but probably with Vz ≈ ±100 km s-1. Plasma up and downflows with VA will within a short duration be blocked between the chromosphere where reconnected flux tubes are piling up, and the slowly rising flux rope. Hence the Petschek slow shock mechanism is difficult to be realized as a major energy converting mechanism. Adopting a conventional reconnecting morphology, we assume a magnetic component parallel to the photospheric neutral line, i.e. sheared fields of By ≠ 0. Then Gauss’s law leads to non-vanishing electric charges σ; 4πσ = -div(V × B/c) ≈ By∂Vz/c∂x where the horizontal inflow velocity Vx changes to vertical down-flow Vz (e.g. By ≈ Bz = 40G and Δx ≈ 104 km). Then the electric field parallel to the magnetic fields E∥ calculated from Coulomb’s law from this σ is found to be far greater than the Dreicer field, and accelerates electrons and protons. Thus the horizontally inflowing Poynting energy flux in area Sx is immediately converted to the kinetic energy of electron beams along the magnetic field in area Sz; BVxSx/4π=12menVbeam3Sz with Sx/Sz ≈ 4. The particle beam energy flux cannot exceed the Poynting energy flux however large E∥ may be. The total energy can be supplied by 10 keV electrons and nbeam = 2 × 107 cm-3 for Vx = 40 km s-1. This inflow velocity Vx, though restricted by the rising prominence speed, explains the short flare duration consistent to observations. The electron beam flux nbeamVbeam will be simultaneously and co-spatially compensated by the slowly back-flowing bulk electrons, avoiding possible enormous charge pile-up. Instead of the conventional diffusion region, which contains serious difficulties if there is the shear as one should normally expect, we propose

  2. Particle acceleration due to shocks in the interplanetary field: High time resolution data and simulation results

    NASA Technical Reports Server (NTRS)

    Kessel, R. L.; Armstrong, T. P.; Nuber, R.; Bandle, J.

    1985-01-01

    Data were examined from two experiments aboard the Explorer 50 (IMP 8) spacecraft. The Johns Hopkins University/Applied Lab Charged Particle Measurement Experiment (CPME) provides 10.12 second resolution ion and electron count rates as well as 5.5 minute or longer averages of the same, with data sampled in the ecliptic plane. The high time resolution of the data allows for an explicit, point by point, merging of the magnetic field and particle data and thus a close examination of the pre- and post-shock conditions and particle fluxes associated with large angle oblique shocks in the interplanetary field. A computer simulation has been developed wherein sample particle trajectories, taken from observed fluxes, are allowed to interact with a planar shock either forward or backward in time. One event, the 1974 Day 312 shock, is examined in detail.

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

    PubMed Central

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

    2014-01-01

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

  4. Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials

    SciTech Connect

    Roy Chowdhury, Dibakar; Xu, Ningning; Zhang, Weili; Singh, Ranjan

    2015-07-14

    Coulomb's law is one of the most fundamental laws of physics that describes the electrostatic interaction between two like or unlike point charges. Here, we experimentally observe a strong effect of Coulomb interaction in tightly coupled terahertz metamaterials where the split-ring resonator dimers in a unit cell are coupled through their near fields across the capacitive split gaps. Using a simple analytical model, we evaluated the Coulomb parameter that switched its sign from negative to positive values indicating the transition in the nature of Coulomb force from being repulsive to attractive depending upon the near field coupling between the split ring resonators. Apart from showing interesting effects in the strong coupling regime between meta-atoms, Coulomb interaction also allows an additional degree of freedom to achieve frequency tunable dynamic metamaterials.

  5. Field emission current fluctuations due to lithium adsorbed on the W(111) region

    NASA Astrophysics Data System (ADS)

    Biernat, T.; Kleint, Ch.; Mȩclewski, R.

    1991-04-01

    Field emission current fluctuations for lithium adsorbed on the tungsten (111) region were investigated by a probe-hole field emission microscope. The coverage dependence of the noise power as well as spectral density functions W(ƒ) at different temperatures were obtained. The spectral density functions have been analysed in terms of the Timm and van der Ziel concentration fluctuation model. Using Comer's method the surface diffusion energies and prefactors have been determined for submonolayer coverages of lithium. They are strongly coverage dependent. The activation energy varies non-monotonically between 0.41 and 0.53 eV and the prefactor between 2.4 × 10 -4 and 1.3 × 10 -2 cm 2/s in the Li surface concentration interval (0.5-3.7) × 10 14 cm -2. The results are compared with those obtained for the W(111)/K system.

  6. Quasi-static electromagnetic fields due to dipole antennas in bounded conducting media

    NASA Astrophysics Data System (ADS)

    Habashy, T. M.; Kong, J. A.; Tsang, L.

    1985-05-01

    Several techniques are employed to model dipole fields in a two-layer dissipative medium. The upper layer is assumed lossless, the lower lossy. Attention is limited to solutions of integrals over the vertical field by quasi-static approximation (QSA), steepest descent image-source (SDIS), residue and hybrid solution approaches. A comparison of the solutions with experimental data delineates the realms of effectiveness for each computational technique: QSA is good for frequencies below 100 kHz and measurements of less than 1/30 wavelength; SDIS is valid at high frequencies on thick layers; and, normal mode residue is applicable for low frequency thin layers. Finally, intermediate conditions require all three techniques.

  7. False vacuum bubble nucleation due to a nonminimally coupled scalar field

    SciTech Connect

    Lee, Wonwoo; Park, Chanyong; Lee, Bum-Hoon; Lee, Chul H.

    2006-12-15

    We study the possibility of forming the false vacuum bubble nucleated within the true vacuum background via the true-to-false vacuum phase transition in curved spacetime. We consider a semiclassical Euclidean bubble in the Einstein theory of gravity with a nonminimally coupled scalar field. In this paper we present the numerical computations as well as the approximate analytical computations. We mention the evolution of the false vacuum bubble after nucleation.

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

    SciTech Connect

    Anderson, Kassandra R.; Adams, Fred C.; Calvet, Nuria

    2013-09-01

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

  9. SU-E-J-115: Correlation of Displacement Vector Fields Calculated by Deformable Image Registration Algorithms with Motion Parameters of CT Images with Well-Defined Targets and Controlled-Motion

    SciTech Connect

    Jaskowiak, J; Ahmad, S; Ali, I; Alsbou, N

    2015-06-15

    Purpose: To investigate correlation of displacement vector fields (DVF) calculated by deformable image registration algorithms with motion parameters in helical axial and cone-beam CT images with motion artifacts. Methods: A mobile thorax phantom with well-known targets with different sizes that were made from water-equivalent material and inserted in foam to simulate lung lesions. The thorax phantom was imaged with helical, axial and cone-beam CT. The phantom was moved with a cyclic motion with different motion amplitudes and frequencies along the superior-inferior direction. Different deformable image registration algorithms including demons, fast demons, Horn-Shunck and iterative-optical-flow from the DIRART software were used to deform CT images for the phantom with different motion patterns. The CT images of the mobile phantom were deformed to CT images of the stationary phantom. Results: The values of displacement vectors calculated by deformable image registration algorithm correlated strongly with motion amplitude where large displacement vectors were calculated for CT images with large motion amplitudes. For example, the maximal displacement vectors were nearly equal to the motion amplitudes (5mm, 10mm or 20mm) at interfaces between the mobile targets lung tissue, while the minimal displacement vectors were nearly equal to negative the motion amplitudes. The maximal and minimal displacement vectors matched with edges of the blurred targets along the Z-axis (motion-direction), while DVF’s were small in the other directions. This indicates that the blurred edges by phantom motion were shifted largely to match with the actual target edge. These shifts were nearly equal to the motion amplitude. Conclusions: The DVF from deformable-image registration algorithms correlated well with motion amplitude of well-defined mobile targets. This can be used to extract motion parameters such as amplitude. However, as motion amplitudes increased, image artifacts increased

  10. Toroidal response due to strong near-field coupling in planar metamaterials (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Basharin, Alexey A.; Chuguevskiy, Vitaliy; Kafesaki, Maria; Economou, Eleftherios; Ustinov, Alexey V.

    2016-04-01

    The main research efforts in the metamaterials science are focused on achieving negative permittivity and permeability, as well as on effects such as superresolution, subwavelength guiding, enhancement of field localization, nanoantennas etc. At the same time, there is a wide range of interesting problems, beyond the issues of negative refraction. One of them is the problem associated with the excitation of toroidal response in metamaterials and the unusual phenomena associated with such response. In this paper, we demonstrate that, owing to the unique topology of the toroidal dipolar mode, its electric/magnetic field can be spatially confined within sub-wavelength, externally accessible regions of the metamolecules, which makes the toroidal metamaterials a viable platform for sensing, enhancement of light absorption and optical nonlinearities, and, especially, ingredient for qubits and quantum metamaterials. The metamolecules employed in the present study are planar conductive structures consisting of two symmetric split loops. The excited circular currents along the loops lead to a circulating magnetic moment and, as a result, to a toroidal moment. We note that the electric field is strongly localized in the splits of the loops and allows achieving the extremely high Q-factor of such types of resonators.

  11. Inputs of heavy metals due to agrochemical use in tobacco fields in Brazil's Southern Region.

    PubMed

    Zoffoli, Hugo José Oliveira; do Amaral-Sobrinho, Nelson Moura Brasil; Zonta, Everaldo; Luisi, Marcus Vinícius; Marcon, Gracioso; Tolón-Becerra, Alfredo

    2013-03-01

    Only a few studies have assessed the joint incorporation of heavy metals into agricultural systems based on the range of agrochemicals used on a specific agricultural crop. This study was conducted to assess the heavy metals input through application of the main agrochemicals used in Brazilian tobacco fields. A total of 56 samples of different batches of 5 fertilizers, 3 substrates, 8 insecticides, 3 fungicides, 2 herbicides, and 1 growth regulator commonly used in the cultivation of tobacco in Brazil's Southern Region were collected from 3 warehouses located in the States of Rio Grande do Sul, Santa Catarina, and Paraná. The total As, Cd, Co, Cr, Cu, Hg, Fe, Mn, Ni, Pb, and Zn content of the samples was then determined and compared with the regulations of different countries and information found in the available literature. The fertilizers were identified as the primary source of heavy metals among the agrochemicals used. Application of pesticides directly to the shoots of tobacco plants contributed very little to the supply of heavy metals. The agrochemicals used in Brazilian tobacco fields provide lower inputs of the main heavy metals that are nonessential for plants than those registered in the international literature for the majority of crop fields in different regions of the world.

  12. The onset of layer undulations in smectic A liquid crystals due to a strong magnetic field

    NASA Astrophysics Data System (ADS)

    Contreras, A.; Garcia-Azpeitia, C.; García-Cervera, C. J.; Joo, S.

    2016-08-01

    We investigate the effect of a strong magnetic field on a three dimensional smectic A liquid crystal. We identify a critical field above which the uniform layered state loses stability; this is associated to the onset of layer undulations. In a previous work García-Cervera and Joo (2012 Arch. Ration. Mech. Anal. 203 1-43), García-Cervera and Joo considered the two dimensional case and analyzed the transition to the undulated state via a simple bifurcation. In dimension n  =  3 the situation is more delicate because the first eigenvalue of the corresponding linearized problem is not simple. We overcome the difficulties inherent to this higher dimensional setting by identifying the irreducible representations for natural actions on the functional that take into account the invariances of the problem thus allowing for reducing the bifurcation analysis to a subspace with symmetries. We are able to describe at least two bifurcation branches, highlighting the richer landscape of energy critical states in the three dimensional setting. Finally, we analyze a reduced two dimensional problem, assuming the magnetic field is very strong, and are able to relate this to a model in micromagnetics studied in Alouges et al (2002 ESAIM Control Optim. Calc. Var. 8 31-68), from where we deduce the periodicity property of minimizers.

  13. Reordering of the ridge patterns of a stochastic electromagnetic field by diffraction due to an ideal slit

    NASA Astrophysics Data System (ADS)

    Avendaño, J.; de La Peña, L.

    2005-12-01

    We study the behavior of scarlets of a stochastic radiation field of fixed frequency in the presence of a slit pierced on an infinitely thin metallic screen of ideal conductivity. Our methodology involves the exact solution of the Maxwell equations with appropriate boundary conditions, the only approximations being those due to the numerical procedure. Our numerical simulations show that the field is unfolded into two components, a dominant one that is disordered and a weaker one that is ordered. The former still presents scarlets although modified, while the latter exhibits a pattern of perfectly coherent diffraction. Due to the dominant character of the disordered component, the general appearance of the scattered field is stochastic; however, an underlying order exists. Our results confirm, thus, a novel effect suggested previously in the context of stochastic electrodynamics.

  14. Reordering of the ridge patterns of a stochastic electromagnetic field by diffraction due to an ideal slit.

    PubMed

    Avendaño, J; de la Peña, L

    2005-12-01

    We study the behavior of scarlets of a stochastic radiation field of fixed frequency in the presence of a slit pierced on an infinitely thin metallic screen of ideal conductivity. Our methodology involves the exact solution of the Maxwell equations with appropriate boundary conditions, the only approximations being those due to the numerical procedure. Our numerical simulations show that the field is unfolded into two components, a dominant one that is disordered and a weaker one that is ordered. The former still presents scarlets although modified, while the latter exhibits a pattern of perfectly coherent diffraction. Due to the dominant character of the disordered component, the general appearance of the scattered field is stochastic; however, an underlying order exists. Our results confirm, thus, a novel effect suggested previously in the context of stochastic electrodynamics.

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

    PubMed

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Dontsov, Egor V.; Guzina, Bojan B.

    2012-10-01

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

  17. Estimating the change in asymptotic direction due to secular changes in the geomagnetic field

    NASA Technical Reports Server (NTRS)

    Flueckiger, E. O.; Smart, D. F.; Shea, M. A.; Gentile, L. C.; Bathurat, A. A.

    1985-01-01

    The concept of geomagnetic optics, as described by the asymptotic directions of approach, is extremely useful in the analysis of cosmic radiation data. However, when changes in cutoff occur as a result of evolution in the geomagnetic field, there are corresponding changes in the asymptotic cones of acceptance. A method is introduced of estimating the change in the asymptotic direction of approach for vertically incident cosmic ray particles from a reference set of directions at a specific epoch by considering the change in the geomagnetic cutoff.

  18. Suppression of drift wave instability due to sheared field-aligned flow and negative ions

    NASA Astrophysics Data System (ADS)

    Ichiki, Ryuta; Hayashi, Kenichiro; Kaneko, Toshiro; Hatakeyama, Rikizo

    2006-10-01

    Sheared field-aligned plasma flow is a significant topic in space/circumterrestrial plasmas. Taking into account negative ions or dust grains will make the space plasma physics more general and accurate. Using the QT-Upgrade Machine, we have conducted laboratory experiments to examine negative ion effects on shear-modified drift waves. Field-aligned K^+ ion flow and its shear strength are controlled with a concentrically segmented W hot plate. Negative ions SF6^- are produced by introducing SF6 gas in the plasma. The drift wave shows a gradual monotonic decrease in amplitude as the shear strength is increased from zero. However, as the shear strength is decreased from zero to negative values, the amplitude increases up to a certain shear strength and rapidly decreases after the peaking. The negative ion introduction, in general, suppresses this instability while retaining the dependence of the amplitude on the shear. These wave characteristics are interpreted using the theories of current-driven (kinetic) and of D’Angelo (fluid) instabilities.

  19. Excitation of dayside chorus waves due to magnetic field line compression in response to interplanetary shocks

    NASA Astrophysics Data System (ADS)

    Zhou, Chen; Li, Wen; Thorne, Richard M.; Bortnik, Jacob; Ma, Qianli; An, Xin; Zhang, Xiao-jia; Angelopoulos, Vassilis; Ni, Binbin; Gu, Xudong; Fu, Song; Zhao, Zhengyu

    2015-10-01

    The excitation of magnetospheric whistler-mode chorus in response to interplanetary (IP) shocks is investigated using wave data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft. As an example, we show a typical chorus wave excitation following an IP shock event that was observed by THEMIS in the postnoon sector near the magnetopause on 3 August 2010. We then analyze characteristic changes during this event and perform a survey of similar events during the period 2008-2014 using the THEMIS and OMNI data set. Our statistical analysis demonstrates that the chorus wave excitation/intensification in response to IP shocks occurs only at high L shells (L > 8) on the dayside. We analyzed the variations of magnetic curvature following the arrival of the IP shock and found that IP shocks lead to more homogeneous background magnetic field configurations in the near-equatorial dayside magnetosphere; and therefore, the threshold of nonlinear chorus wave growth is likely to be reduced, favoring chorus wave generation. Our results provide the observational evidence to support the concept that the geomagnetic field line configuration plays a key role in the excitation of dayside chorus.

  20. Electron residual energy due to stochastic heating in field-ionized plasma

    SciTech Connect

    Khalilzadeh, Elnaz; Yazdanpanah, Jam Chakhmachi, Amir; Jahanpanah, Jafar; Yazdani, Elnaz

    2015-11-15

    The electron residual energy originated from the stochastic heating in under-dense field-ionized plasma is investigated here. Initially, the optical response of plasma is modeled by using two counter-propagating electromagnetic waves. In this case, the solution of motion equation of a single electron indicates that by including the ionization, the electron with higher residual energy compared with that without ionization could be obtained. In agreement with chaotic nature of the motion, it is found that the electron residual energy will be significantly changed by applying a minor change in the initial conditions. Extensive kinetic 1D-3V particle-in-cell simulations have been performed in order to resolve full plasma reactions. In this way, two different regimes of plasma behavior are observed by varying the pulse length. The results indicate that the amplitude of scattered fields in a proper long pulse length is high enough to act as a second counter-propagating wave and trigger the stochastic electron motion. On the contrary, the analyses of intensity spectrum reveal the fact that the dominant scattering mechanism tends to Thomson rather than Raman scattering by increasing the pulse length. A covariant formalism is used to describe the plasma heating so that it enables us to measure electron temperature inside and outside of the pulse region.

  1. Mobility overestimation due to gated contacts in organic field-effect transistors

    PubMed Central

    Bittle, Emily G.; Basham, James I.; Jackson, Thomas N.; Jurchescu, Oana D.; Gundlach, David J.

    2016-01-01

    Parameters used to describe the electrical properties of organic field-effect transistors, such as mobility and threshold voltage, are commonly extracted from measured current–voltage characteristics and interpreted by using the classical metal oxide–semiconductor field-effect transistor model. However, in recent reports of devices with ultra-high mobility (>40 cm2 V−1 s−1), the device characteristics deviate from this idealized model and show an abrupt turn-on in the drain current when measured as a function of gate voltage. In order to investigate this phenomenon, here we report on single crystal rubrene transistors intentionally fabricated to exhibit an abrupt turn-on. We disentangle the channel properties from the contact resistance by using impedance spectroscopy and show that the current in such devices is governed by a gate bias dependence of the contact resistance. As a result, extracted mobility values from d.c. current–voltage characterization are overestimated by one order of magnitude or more. PMID:26961271

  2. Electron residual energy due to stochastic heating in field-ionized plasma

    NASA Astrophysics Data System (ADS)

    Khalilzadeh, Elnaz; Yazdanpanah, Jam; Jahanpanah, Jafar; Chakhmachi, Amir; Yazdani, Elnaz

    2015-11-01

    The electron residual energy originated from the stochastic heating in under-dense field-ionized plasma is investigated here. Initially, the optical response of plasma is modeled by using two counter-propagating electromagnetic waves. In this case, the solution of motion equation of a single electron indicates that by including the ionization, the electron with higher residual energy compared with that without ionization could be obtained. In agreement with chaotic nature of the motion, it is found that the electron residual energy will be significantly changed by applying a minor change in the initial conditions. Extensive kinetic 1D-3V particle-in-cell simulations have been performed in order to resolve full plasma reactions. In this way, two different regimes of plasma behavior are observed by varying the pulse length. The results indicate that the amplitude of scattered fields in a proper long pulse length is high enough to act as a second counter-propagating wave and trigger the stochastic electron motion. On the contrary, the analyses of intensity spectrum reveal the fact that the dominant scattering mechanism tends to Thomson rather than Raman scattering by increasing the pulse length. A covariant formalism is used to describe the plasma heating so that it enables us to measure electron temperature inside and outside of the pulse region.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  5. Screening of external magnetic perturbation fields due to sheared plasma flow

    NASA Astrophysics Data System (ADS)

    Li, L.; Liu, Y. Q.; Liang, Y.; Wang, N.; Luan, Q.; Zhong, F. C.; Liu, Y.

    2016-09-01

    Within the single fluid resistive magnetohydrodynamic model, systematic toroidal modelling efforts are devoted to investigate the plasma response induced screening of the applied external 3D magnetic field perturbations in the presence of sheared toroidal flow. One particular issue of interest is addressed, when the local flow speed approaches zero at the perturbation rational surface inside the plasma. Subtle screening physics, associated with the favourable averaged toroidal curvature effect (the GGJ effect (Glasser et al 1975 Phys. Fluids 7 875)), is found to play an essential role during slow flow near the rational surface by enhancing the screening at reduced flow. A strong cancellation effect between different terms of Ohm’s law is discovered, leading to different screening physics in the GGJ regime, as compared to that of conventional screening of the typical resistive-inertial regime occurring at faster flow. These modelling results may be applicable to interpret certain mode locking experiments, as well as type-I edge localized mode suppression experiments, with resonant magnetic field perturbations being applied to tokamak plasmas at low input toroidal torque.

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

    SciTech Connect

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

    2010-11-01

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

  7. Overestimation of Crop Root Biomass in Field Experiments Due to Extraneous Organic Matter

    PubMed Central

    Hirte, Juliane; Leifeld, Jens; Abiven, Samuel; Oberholzer, Hans-Rudolf; Hammelehle, Andreas; Mayer, Jochen

    2017-01-01

    Root biomass is one of the most relevant root parameters for studies of plant response to environmental change, soil carbon modeling or estimations of soil carbon sequestration. A major source of error in root biomass quantification of agricultural crops in the field is the presence of extraneous organic matter in soil: dead roots from previous crops, weed roots, incorporated above ground plant residues and organic soil amendments, or remnants of soil fauna. Using the isotopic difference between recent maize root biomass and predominantly C3-derived extraneous organic matter, we determined the proportions of maize root biomass carbon of total carbon in root samples from the Swiss long-term field trial “DOK.” We additionally evaluated the effects of agricultural management (bio-organic and conventional), sampling depth (0–0.25, 0.25–0.5, 0.5–0.75 m) and position (within and between maize rows), and root size class (coarse and fine roots) as defined by sieve mesh size (2 and 0.5 mm) on those proportions, and quantified the success rate of manual exclusion of extraneous organic matter from root samples. Only 60% of the root mass that we retrieved from field soil cores was actual maize root biomass from the current season. While the proportions of maize root biomass carbon were not affected by agricultural management, they increased consistently with soil depth, were higher within than between maize rows, and were higher in coarse (>2 mm) than in fine (≤2 and >0.5) root samples. The success rate of manual exclusion of extraneous organic matter from root samples was related to agricultural management and, at best, about 60%. We assume that the composition of extraneous organic matter is strongly influenced by agricultural management and soil depth and governs the effect size of the investigated factors. Extraneous organic matter may result in severe overestimation of recovered root biomass and has, therefore, large implications for soil carbon modeling and

  8. Overestimation of Crop Root Biomass in Field Experiments Due to Extraneous Organic Matter.

    PubMed

    Hirte, Juliane; Leifeld, Jens; Abiven, Samuel; Oberholzer, Hans-Rudolf; Hammelehle, Andreas; Mayer, Jochen

    2017-01-01

    Root biomass is one of the most relevant root parameters for studies of plant response to environmental change, soil carbon modeling or estimations of soil carbon sequestration. A major source of error in root biomass quantification of agricultural crops in the field is the presence of extraneous organic matter in soil: dead roots from previous crops, weed roots, incorporated above ground plant residues and organic soil amendments, or remnants of soil fauna. Using the isotopic difference between recent maize root biomass and predominantly C3-derived extraneous organic matter, we determined the proportions of maize root biomass carbon of total carbon in root samples from the Swiss long-term field trial "DOK." We additionally evaluated the effects of agricultural management (bio-organic and conventional), sampling depth (0-0.25, 0.25-0.5, 0.5-0.75 m) and position (within and between maize rows), and root size class (coarse and fine roots) as defined by sieve mesh size (2 and 0.5 mm) on those proportions, and quantified the success rate of manual exclusion of extraneous organic matter from root samples. Only 60% of the root mass that we retrieved from field soil cores was actual maize root biomass from the current season. While the proportions of maize root biomass carbon were not affected by agricultural management, they increased consistently with soil depth, were higher within than between maize rows, and were higher in coarse (>2 mm) than in fine (≤2 and >0.5) root samples. The success rate of manual exclusion of extraneous organic matter from root samples was related to agricultural management and, at best, about 60%. We assume that the composition of extraneous organic matter is strongly influenced by agricultural management and soil depth and governs the effect size of the investigated factors. Extraneous organic matter may result in severe overestimation of recovered root biomass and has, therefore, large implications for soil carbon modeling and estimations

  9. Experimental observation of increased threshold electric field for runaway generation due to synchrotron radiation losses in the FTU tokamak

    SciTech Connect

    Martin-Solis, Jose Ramon; Sanchez, Raul; Esposito, Basilio

    2010-01-01

    The threshold electric field for runaway generation has been investigated during runaway suppression experiments by means of electron-cyclotron-resonance heating in the flattop phase of FTU discharges. Runaway suppression has been experimentally found to occur at electric fields substantially larger than those predicted by the relativistic collisional theory of runaway generation, E{sub R} = n{sub e}e{sup 3}ln{Lambda}/4{pi}{var_epsilon}{sub 0}{sup 2}m{sub e}c{sup 2}. These experimental results are consistent with an increase of the critical electric field due to the electron synchrotron radiation losses. No runaway electrons are found in FTU experiments below the radiation threshold. These results support evidence for a new threshold electric field for runaway generation that accounts for the effect of the synchrotron losses, and which should be considered when making predictions on runaway generation and mitigation in devices such as ITER.

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

    NASA Astrophysics Data System (ADS)

    Sengupta, K.; Sen, Diptiman

    2009-09-01

    We compute concurrence and negativity as measures of two-spin entanglement generated by a power-law quench (characterized by a rate τ-1 and an exponent α ) 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, τc-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 τ , the concurrence (negativity) scales as α/τ (α/τ) , and we relate this scaling behavior to defect production by the quench through a QCP.

  11. Gyrokinetic Simulations of Electrostatic Turbulence Reduction due to Radial Electric Field Shear in DIII-D

    NASA Astrophysics Data System (ADS)

    Taimourzadeh, Sam; Holod, Ihor; Lin, Zhihong; Nazikian, Raffi

    2015-11-01

    It has been demonstrated that edge localized modes (ELMs) can be fully suppressed in DIII-D H-mode plasmas with the application of resonant magnetic perturbations (RMPs), and that there is a corresponding reduction of pedestal gradients, changes in rotation, and changes in the radial electric field (Er) profile. However, with the application of RMPs there is also an increase in short wavelength, electrostatic turbulence on top of the pedestal, as observed with BES, DBS, and other fluctuation diagnostics. The effects of Er shear on this turbulence, is investigated using gyrokinetic simulations via the gyrokinetic toroidal code (GTC) for in DIII-D shot 158103, at times 3750 ms (RMP on, ELM active) and 3050 ms (RMP on, ELM suppressed).

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

    NASA Astrophysics Data System (ADS)

    Trupp, Andreas

    2002-11-01

    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.

  13. 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)

    Glover, P. M.; Bowtell, R.

    2008-01-01

    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.

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

    PubMed

    Glover, P M; Bowtell, R

    2008-01-21

    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.

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

    PubMed Central

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

    2014-01-01

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

  16. Precision displacement reference system

    DOEpatents

    Bieg, Lothar F.; Dubois, Robert R.; Strother, Jerry D.

    2000-02-22

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

  17. Microbial contamination of indoor air due to leakages from crawl space: a field study.

    PubMed

    Airaksinen, M; Pasanen, P; Kurnitski, J; Seppänen, O

    2004-02-01

    Mechanical exhaust ventilation system is typical in apartment buildings in Finland. In most buildings the base floor between the first floor apartments and crawl space is not air tight. As the apartments have lower pressure than the crawl space due to ventilation, contaminated air may flow from the crawl space to the apartments. The object of this study was to find out whether a potential air flow from crawl space has an influence on the indoor air quality. The results show that in most cases the concentration of fungal spores was clearly higher in the crawl space than inside the building. The size distribution of fungal spores depended on the fungal species. Correlation between the fungal spores in the crawl space and indoors varied with microbial species. Some species have sources inside the building, which confounds the possible relation between crawl pace and indoor concentrations. Some species, such as Acremonium, do not normally have a source indoors, but its concentration in the crawl space was elevated; our measurements showed also elevated concentrations of Acremonium in the air of the apartments. This consistent finding shows a clear linkage between fungal spores in the indoor air and crawl space. We conclude that a building with a crawl space and pressure difference over the base floor could be a potential risk for indoor air quality in the first floor apartments.

  18. Enhanced O2+ loss at Mars due to an ambipolar electric field from electron heating

    NASA Astrophysics Data System (ADS)

    Ergun, R. E.; Andersson, L. A.; Fowler, C. M.; Woodson, A. K.; Weber, T. D.; Delory, G. T.; Andrews, D. J.; Eriksson, A. I.; McEnulty, T.; Morooka, M. W.; Stewart, A. I. F.; Mahaffy, P. R.; Jakosky, B. M.

    2016-05-01

    Recent results from the MAVEN Langmuir Probe and Waves instrument suggest higher than predicted electron temperatures (Te) in Mars' dayside ionosphere above ~180 km in altitude. Correspondingly, measurements from Neutral Gas and Ion Mass Spectrometer indicate significant abundances of O2+ up to ~500 km in altitude, suggesting that O2+ may be a principal ion loss mechanism of oxygen. In this article, we investigate the effects of the higher Te (which results from electron heating) and ion heating on ion outflow and loss. Numerical solutions show that plasma processes including ion heating and higher Te may greatly increase O2+ loss at Mars. In particular, enhanced Te in Mars' ionosphere just above the exobase creates a substantial ambipolar electric field with a potential (eΦ) of several kBTe, which draws ions out of the region allowing for enhanced escape. With active solar wind, electron, and ion heating, direct O2+ loss could match or exceed loss via dissociative recombination of O2+. These results suggest that direct loss of O2+ may have played a significant role in the loss of oxygen at Mars over time.

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

    PubMed

    Montaz, Julie; Jacquot, Marion; Coeurdassier, Michaël

    2014-11-01

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

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

    PubMed

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

    2008-07-01

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

  1. A comprehensive study of charge trapping in organic field-effect devices with promising semiconductors and different contact metals by displacement current measurements

    NASA Astrophysics Data System (ADS)

    Bisoyi, Sibani; Rödel, Reinhold; Zschieschang, Ute; Kang, Myeong Jin; Takimiya, Kazuo; Klauk, Hagen; Tiwari, Shree Prakash

    2016-02-01

    A systematic and comprehensive study on the charge-carrier injection and trapping behavior was performed using displacement current measurements in long-channel capacitors based on four promising small-molecule organic semiconductors (pentacene, DNTT, C10-DNTT and DPh-DNTT). In thin-film transistors, these semiconductors showed charge-carrier mobilities ranging from 1.0 to 7.8 cm2 V-1 s-1. The number of charges injected into and extracted from the semiconductor and the density of charges trapped in the device during each measurement were calculated from the displacement current characteristics and it was found that the density of trapped charges is very similar in all devices and of the order 1012 cm-2, despite the fact that the four semiconductors show significantly different charge-carrier mobilities. The choice of the contact metal (Au, Ag, Cu, Pd) was also found to have no significant effect on the trapping behavior.

  2. Superior bit error rate and jitter due to improved switching field distribution in exchange spring magnetic recording media

    PubMed Central

    Suess, D.; Fuger, M.; Abert, C.; Bruckner, F.; Vogler, C.

    2016-01-01

    We report two effects that lead to a significant reduction of the switching field distribution in exchange spring media. The first effect relies on a subtle mechanism of the interplay between exchange coupling between soft and hard layers and anisotropy that allows significant reduction of the switching field distribution in exchange spring media. This effect reduces the switching field distribution by about 30% compared to single-phase media. A second effect is that due to the improved thermal stability of exchange spring media over single-phase media, the jitter due to thermal fluctuation is significantly smaller for exchange spring media than for single-phase media. The influence of this overall improved switching field distribution on the transition jitter in granular recording and the bit error rate in bit-patterned magnetic recording is discussed. The transition jitter in granular recording for a distribution of Khard values of 3% in the hard layer, taking into account thermal fluctuations during recording, is estimated to be a = 0.78 nm, which is similar to the best reported calculated jitter in optimized heat-assisted recording media. PMID:27245287

  3. Superior bit error rate and jitter due to improved switching field distribution in exchange spring magnetic recording media.

    PubMed

    Suess, D; Fuger, M; Abert, C; Bruckner, F; Vogler, C

    2016-06-01

    We report two effects that lead to a significant reduction of the switching field distribution in exchange spring media. The first effect relies on a subtle mechanism of the interplay between exchange coupling between soft and hard layers and anisotropy that allows significant reduction of the switching field distribution in exchange spring media. This effect reduces the switching field distribution by about 30% compared to single-phase media. A second effect is that due to the improved thermal stability of exchange spring media over single-phase media, the jitter due to thermal fluctuation is significantly smaller for exchange spring media than for single-phase media. The influence of this overall improved switching field distribution on the transition jitter in granular recording and the bit error rate in bit-patterned magnetic recording is discussed. The transition jitter in granular recording for a distribution of Khard values of 3% in the hard layer, taking into account thermal fluctuations during recording, is estimated to be a = 0.78 nm, which is similar to the best reported calculated jitter in optimized heat-assisted recording media.

  4. Efficient magnetic-field amplification due to the Kelvin-Helmholtz instability in binary neutron star mergers

    NASA Astrophysics Data System (ADS)

    Kiuchi, Kenta; Cerdá-Durán, Pablo; Kyutoku, Koutarou; Sekiguchi, Yuichiro; Shibata, Masaru

    2015-12-01

    We explore magnetic-field amplification due to the Kelvin-Helmholtz instability during binary neutron star mergers. By performing high-resolution general relativistic magnetohydrodynamics simulations with a resolution of 17.5 m for 4-5 ms after the onset of the merger on the Japanese supercomputer "K", we find that an initial magnetic field of moderate maximum strength 1013 G is amplified at least by a factor of ≈103. We also explore the saturation of the magnetic-field energy and our result shows that it is likely to be ≳4 ×1050 erg , which is ≳0.1 % of the bulk kinetic energy of the merging binary neutron stars.

  5. Tactile suppression of displacement.

    PubMed

    Ziat, Mounia; Hayward, Vincent; Chapman, C Elaine; Ernst, Marc O; Lenay, Charles

    2010-10-01

    In vision, the discovery of the phenomenon of saccadic suppression of displacement has made important contributions to the understanding of the stable world problem. Here, we report a similar phenomenon in the tactile modality. When scanning a single Braille dot with two fingers of the same hand, participants were asked to decide whether the dot was stationary or whether it was displaced from one location to another. The stimulus was produced by refreshable Braille devices that have dots that can be swiftly raised and recessed. In some conditions, the dot was stationary. In others, a displacement was created by monitoring the participant's finger position and by switching the dot activation when it was not touched by either finger. The dot displacement was of either 2.5 mm or 5 mm. We found that in certain cases, displaced dots were felt to be stationary. If the displacement was orthogonal to the finger movements, tactile suppression occurred effectively when it was of 2.5 mm, but when the displacement was of 5 mm, the participants easily detected it. If the displacement was medial-lateral, the suppression effect occurred as well, but less often when the apparent movement of the dot opposed the movement of the finger. In such cases, the stimulus appeared sooner than when the brain could predict it from finger movement, supporting a predictive rather than a postdictive differential processing hypothesis.

  6. Displacement data assimilation

    NASA Astrophysics Data System (ADS)

    Rosenthal, W. Steven; Venkataramani, Shankar; Mariano, Arthur J.; Restrepo, Juan M.

    2017-02-01

    We show that modifying a Bayesian data assimilation scheme by incorporating kinematically-consistent displacement corrections produces a scheme that is demonstrably better at estimating partially observed state vectors in a setting where feature information is important. While the displacement transformation is generic, here we implement it within an ensemble Kalman Filter framework and demonstrate its effectiveness in tracking stochastically perturbed vortices.

  7. Internal displacement in Colombia

    PubMed Central

    Shultz, James M; Ceballos, Ángela Milena Gómez; Espinel, Zelde; Oliveros, Sofia Rios; Fonseca, Maria Fernanda; Florez, Luis Jorge Hernandez

    2014-01-01

    This commentary aims to delineate the distinguishing features of conflict-induced internal displacement in the nation of Colombia, South America. Even as Colombia is currently implementing a spectrum of legal, social, economic, and health programs for “victims of armed conflict,” with particular focus on internally displaced persons (IDPs), the dynamics of forced migration on a mass scale within this country are little known beyond national borders.   The authors of this commentary are embarking on a global mental health research program in Bogota, Colombia to define best practices for reaching the displaced population and implementing sustainable, evidence-based screening and intervention for common mental disorders. Presenting the defining characteristics of internal displacement in Colombia provides the context for our work and, more importantly, conveys the compelling and complex nature of this humanitarian crisis. We attempt to demonstrate Colombia’s unique position within the global patterning of internal displacement. PMID:28228997

  8. Laser optical displacement system

    NASA Astrophysics Data System (ADS)

    Starritt, Larry W.; Matthews, Larryl K.

    1995-04-01

    The current quality of our nations bridges is on a decline. There are roughly half a million highway bridges in the United States and out of the half a million more than 200,000 are deficient. With catastrophic failure of bridges causing the loss of life and property, the need for bridge inspection and maintenance is evident. When the Silver Bridge that crossed the Ohio River collapsed in December 1967, 46 people were killed. The failure to prevent the disaster was attributed to the poor inspection techniques used by the bridge inspectors. Current inspection techniques depend on humans being able to recognize structural imperfections without the aid of instrumentation. The Federal-Aid Highway Act of 1968 mandated both national bridge inspection standards and training for bridge inspectors. This act has encouraged the development of instruments that would allow inspectors to perform more complete inspections of bridges. To improve the quality of inspection and data, there is a great need for proven methods and instruments used to acquire data. The Laser Optical Displacement System (L.O.D.S.) developed at New Mexico State University by the Optical and Materials Science Lab is such a device. The L.O.D.S. has been tested and proven in both laboratory situations and in the field. This paper describes some of the methods that are now being used to measure deflections in bridges. Then, a description of the development and application of the L.O.D.S. unit is given.

  9. The effect of thermotropic oil-displacing compound thickened Ninka on reservoir microflora and the composition of oil in Usinskoe oil field

    NASA Astrophysics Data System (ADS)

    Ovsyannikova, V. S.; Shcherbakova, A. G.; Guseva, Y. Z.; Altunina, L. K.; Chuykina, D. I.

    2016-11-01

    The work presents results of the study of the impact of thermotropic sol-forming compound thickened NINKA on enhanced oil recovery, stimulation of oil production, on the composition of crude oil, and on oil reservoir microflora sampled from reservoir fluids in the testing and reference areas of Usinskoe field. In vitro, the compound in the concentrations of 0.1-0.5% has a stimulating effect on the microflora, which is more pronounced in a low-mineralized environment. In reservoir conditions, after the injection of the compound, along with the appearance of nitrogen-containing components of the compound and products of its hydrolysis in the wellstream, some wells showed a significant increase in the number of heterotrophic and denitrifying microflora, which is indicative of a stimulating effect of the compound. The change in the composition of oil from these producing wells is due to the desorption of polar and high-molecular components and, to a lesser extent, to the redistribution of filtration flows.

  10. Simulation of permafrost changes due to technogenic influences of different ingeneering constructions used in nothern oil and gas fields

    NASA Astrophysics Data System (ADS)

    Filimonov, M. Yu; Vaganova, N. A.

    2016-10-01

    Significant amount of oil and gas is producted in Russian Federation on the territories with permafrost soils. Ice-saturated rocks thawing due to global warming or effects of various human activity will be accompanied by termocarst and others dangerous geological processes in permafrost. Design and construction of well pads in permafrost zones have some special features. The main objective is to minimize the influence of different heat sources (engineering objects) inserted into permafrost and accounting long-term forecast of development of permafrost degradation due to different factors in particular generated by human activity. In this work on the basis a mathematical model and numerical algorithms approved on 11 northern oil and gas fields some effects obtained by carrying out numerical simulations for various engineering systems are discussed.

  11. Prediction of electron concentration reductions in re-entry flow fields due to electrophilic liquid and water injection.

    NASA Technical Reports Server (NTRS)

    Pergament, H. S.; Mikatarian, R. R.; Kurzius, S. C.

    1972-01-01

    Discussion of an analytical model which leads to predictions of reductions in electron concentrations in reentry flow fields due to the injection of electrophilic liquids and water. The processes incorporated into the model are: penetration and breakup of the liquid jet, droplet acceleration and vaporization, expansion of the liquid spray due to droplet vaporization, electrophilic vapor diffusion, heterogeneous and homogeneous charged species recombination kinetics and homogeneous electron attachment kinetics. Spray boundary calculations are shown to be in good agreement with photographic observations of water and Freon E-3 sprays in wind tunnel tests of a scale model RAM C-III flight vehicle. Fixed-bias electrostatic probe data taken during the RAM C-III flight are interpreted in terms of effective jet penetration distances - which are shown to be consistent with calculations using the present model.

  12. Displacement of molecules near a metal surface as seen by an SPR-SPFS biosensor.

    PubMed

    Ekgasit, Sanong; Yu, Fang; Knoll, Wolfgang

    2005-04-26

    Movement of a fluorophore-labeled antibody on the surface of a self-assembled monolayer (SAM) was observed by surface plasmon resonance and surface-plasmon field-enhanced fluorescence spectroscopy (SPFS). At an extremely low surface coverage, the antibody lies close to the biotin-functionalized SAM surface. As additional nonlabeled antibodies were bound, the fluorophore-labeled antibody was displaced away from the SAM surface (and thus the gold surface) due to the constraint imposed by the neighboring nonlabeled antibody. A greater SPFS fluorescence signal was observed due to the weaker fluorescence quenching at large distances from the gold surface. The magnitude of the displacement is proportional to the available biotin binding sites on the sensor surface. The displacement is theoretically explained on the basis of the relationship between the fluorescence intensity and the evanescent field amplitude within the dielectric medium.

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

    SciTech Connect

    Fischer, Michael; Schmidt, Ruediger; Lorenz, Ulf; Schmidt, Burkhard

    2011-09-15

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

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

    SciTech Connect

    J. Dai, K. Zhao, G.V. Eremeev, R.L. Geng, A.D. Palczewski; Dai, J.; Palczewski, A. D.; Eremeev, G. V.; Geng, R. L.; Zhao, K.

    2011-07-01

    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.

  15. First in situ evidence of electron pitch angle scattering due to magnetic field line curvature in the Ion diffusion region

    NASA Astrophysics Data System (ADS)

    Zhang, Y. C.; Shen, C.; Marchaudon, A.; Rong, Z. J.; Lavraud, B.; Fazakerley, A.; Yao, Z.; Mihaljcic, B.; Ji, Y.; Ma, Y. H.; Liu, Z. X.

    2016-05-01

    Theory predicts that the first adiabatic invariant of a charged particle may be violated in a region of highly curved field lines, leading to significant pitch angle scattering for particles whose gyroradius are comparable to the radius of the magnetic field line curvature. This scattering generates more isotropic particle distribution functions, with important impacts on the presence or absence of plasma instabilities. Using magnetic curvature analysis based on multipoint Cluster spacecraft observations, we present the first investigation of magnetic curvature in the vicinity of an ion diffusion region where reconnected field lines are highly curved. Electrons at energies > 8 keV show a clear pitch angle ordering between bidirectional and trapped distribution in surrounding regions, while we show that in the more central part of the ion diffusion region electrons above such energies become isotropic. By contrast, colder electrons (~1 keV) retain their bidirectional character throughout the diffusion regions. The calculated adiabatic parameter K2 for these electrons is in agreement with theory. This study provides the first observational evidence for particle pitch angle scattering due to magnetic field lines with well characterized curvature in a space plasma.

  16. 24 CFR 583.310 - Displacement, relocation, and acquisition.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... persons. A displaced person (defined in paragraph (f) of this section) must be provided relocation... “displaced person,” or the amount of relocation assistance for which the person is eligible, may file a... to the HUD field office. (f) Definition of displaced person. (1) For purposes of this section,...

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

    NASA Astrophysics Data System (ADS)

    Kim, Junhee; Kim, Kiyoung; Sohn, Hoon

    2014-01-01

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

  18. Advanced Triangulation Displacement Sensors

    NASA Technical Reports Server (NTRS)

    Poteet, Wade M.; Cauthen, Harold K.

    1996-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Brodsky, Lisa; Punjabi, Alkesh; Ali, Halima

    2008-11-01

    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 have the advantage that natural canonical coordinates can be inverted to calculate real space coordinates (R,Z,φ), and there is no problem in crossing the separatrix. This is not possible for magnetic coordinates. This map is applied to calculate stochastic broadening due to magnetic noise and field errors in the DIII-D. Mode numbers for noise + field errors are (m,n)=(3,1), (4,1), (6,2), (7,2), (8,2), (9,3), (10,3), (11,3), (12,3). The common amplitude δ is varied from 0.8X10-5 to 2.0X10-5. Preliminary results suggest that the width of stochastic layer from noise and field errors in the DIII-D varies from about 7 to 16 cm near X-point, and about 0.6 to 3% of poloidal flux is lost from inside ideal separatrix. This work is supported by US Department of Energy grants DE-FG02-07ER54937, DE-FG02-01ER54624 and DE-FG02-04ER54793.

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

    NASA Technical Reports Server (NTRS)

    Miura, T.; Chao, C. C.

    1980-01-01

    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.

  1. Non-Maxwellian electron distribution functions due to self-generated turbulence in collisionless guide-field reconnection

    NASA Astrophysics Data System (ADS)

    Muñoz, P. A.; Büchner, J.

    2016-10-01

    Non-Maxwellian electron velocity space distribution functions (EVDFs) are useful signatures of plasma conditions and non-local consequences of collisionless magnetic reconnection. In the past, EVDFs were obtained mainly for antiparallel reconnection and under the influence of weak guide-fields in the direction perpendicular to the reconnection plane. EVDFs are, however, not well known, yet, for oblique (or component-) reconnection in case and in dependence on stronger guide-magnetic fields and for the exhaust (outflow) region of reconnection away from the diffusion region. In view of the multi-spacecraft Magnetospheric Multiscale Mission (MMS), we derived the non-Maxwellian EVDFs of collisionless magnetic reconnection in dependence on the guide-field strength bg from small ( b g ≈ 0 ) to very strong (bg = 8) guide-fields, taking into account the feedback of the self-generated turbulence. For this sake, we carried out 2.5D fully kinetic Particle-in-Cell simulations using the ACRONYM code. We obtained anisotropic EVDFs and electron beams propagating along the separatrices as well as in the exhaust region of reconnection. The beams are anisotropic with a higher temperature in the direction perpendicular rather than parallel to the local magnetic field. The beams propagate in the direction opposite to the background electrons and cause instabilities. We also obtained the guide-field dependence of the relative electron-beam drift speed, threshold, and properties of the resulting streaming instabilities including the strongly non-linear saturation of the self-generated plasma turbulence. This turbulence and its non-linear feedback cause non-adiabatic parallel electron acceleration. We further obtained the resulting EVDFs due to the non-linear feedback of the saturated self-generated turbulence near the separatrices and in the exhaust region of reconnection in dependence on the guide field strength. We found that the influence of the self-generated plasma turbulence

  2. Quantum corrections to the gravitational potentials of a point source due to conformal fields in de Sitter

    SciTech Connect

    Fröb, Markus B.; Verdaguer, Enric E-mail: enric.verdaguer@ub.edu

    2016-03-01

    We derive the leading quantum corrections to the gravitational potentials in a de Sitter background, due to the vacuum polarization from loops of conformal fields. Our results are valid for arbitrary conformal theories, even strongly interacting ones, and are expressed using the coefficients b and b' appearing in the trace anomaly. Apart from the de Sitter generalization of the known flat-space results, we find two additional contributions: one which depends on the finite coefficients of terms quadratic in the curvature appearing in the renormalized effective action, and one which grows logarithmically with physical distance. While the first contribution corresponds to a rescaling of the effective mass, the second contribution leads to a faster fall-off of the Newton potential at large distances, and is potentially measurable.

  3. Ultra-Sensitive Magnetoresistive Displacement Sensing Device

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  4. Water displacement mercury pump

    DOEpatents

    Nielsen, M.G.

    1984-04-20

    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.

  5. Water displacement mercury pump

    DOEpatents

    Nielsen, Marshall G.

    1985-01-01

    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.

  6. Optical displacement sensor

    DOEpatents

    Carr, Dustin W.

    2008-04-08

    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.

  7. Electrostatic Fields Near the Active Site of Human Aldose Reductase: 2. New Inhibitors and Complications due to Hydrogen Bonds†

    PubMed Central

    Xu, Lin; Cohen, Aina E.; Boxer, Steven G.

    2011-01-01

    Vibrational Stark effect spectroscopy was used to measure electrostatic fields in the hydrophobic region of the active site of human aldose reductase (hALR2). A new nitrile-containing inhibitor was designed and synthesized, and the x-ray structure of its complex, along with cofactor NADP+, with wild-type hALR2 was determined at 1.3 Å resolution. The nitrile is found to be in close proximity to T113, consistent with a hydrogen bond interaction. Two vibrational absorption peaks were observed at room temperature in the nitrile region when the inhibitor binds to wild-type hALR2, indicating that the nitrile probe experiences two different microenvironments, and these could be empirically separated into a hydrogen bonded and non-hydrogen bonded population by comparison with the mutant T113A, where a hydrogen bond to the nitrile is not present. Classical molecular dynamics simulations based on the structure predict a double-peaked distribution in protein electric fields projected along the nitrile probe. The interpretation of these two peaks as a hydrogen bond formation-dissociation process between the probe nitrile group and a nearby amino acid side chain is used to explain the observation of two IR bands, and the simulations were used to investigate the molecular details of this conformational change. Hydrogen bonding complicates the simplest analysis of vibrational frequency shifts as being due solely to electrostatic interactions through the vibrational Stark effect, and the consequences of this complication are discussed. PMID:21859105

  8. Accelerated soil mineralization, nitrification, and revegetation of abandoned fields due to the removal of crop-soil phytotoxicity.

    PubMed

    Lodhi, M A

    1981-07-01

    In an abandoned corn field, clear-cutting of crop vegetation increased the productivity, species richness, and nonannuals in the following years after abandonment, as compared to the control plots from which crop vegetation was not removed. The increase in plant growth was apparently due to the elimination of allelopathic chemicals from the soil, which normally are released from the standing crop. Removal of vegetation also increased the soil mineralization of Ca(2+), Mg(2+), K(+), NH4 (+) and NO3 (-)-N. This situation encouraged species having higher mineral requirements to rapidly invade the fields in the successive years. Clear-cutting also increased the nitrification process by removing the inhibitors of nitrification. The number ofNitrosomonas was always significantly higher in the harvested plots as compared to unharvested plots. Phenolic phytotoxins were isolated from the crop residue and soil. Further, these phytotoxins were significantly higher in the unharvested crops as compared to clear-cut plots, in most samples. Whatever the direct or indirect additional explanation for increased biomass, nonannuals and richness in successive years, it is clear that the removal of standing crop has a definite influence.

  9. Enhanced Valley Zeeman Splitting in MoS2 /EuS due to interfacial exchange field

    NASA Astrophysics Data System (ADS)

    Zhao, Chuan; Scrace, Thomas; Taheri, Payam; Zhang, Peiyao; Norden, Tenzin; Blizzard, Brett; Petrou, Athos; Zeng, Hao; Zhao, Puqin; Kioseoglou, George

    A monolayer transition metal dichalcogenides such as MoS2 with broken inversion symmetry possesses two degenerate yet inequivalent valleys that can be selectively excited by circularly polarized light. The ability to manipulate valley degrees of freedom with light or external magnetic field makes them attractive for optoelectronic and spintronic applications. On the other hand, it has been demonstrated recently that a magnetic insulator such as EuS can induce magnetic exchange field (MEF) on graphene through proximity effect. Thus, construction of a magnetic insulator/TMDC heterostructure may induce large MEF on TMDC, which may lead to giant valley Zeeman splitting. In this work, we report the observation of valley Zeeman splitting in monolayer MoS2 and other TMDCs due to the MEF from EuS substrates. Using magneto-reflectivity, we measured a Zeeman splitting of valley exciton of 2 meV at 7 tesla and 4 K, for monolayer MoS2 on a SiO2 substrate. This is consistent with values reported in monolayer WSe2. However, when EuS is used as the substrate, we observed an increase of valley splitting from 2 to 10 meV. We attribute this enhanced valley splitting to the MEF from the EuS substrate. Utilizing MEF of a magnetic insulator can induce magnetic ordering and giant Zeeman splitting in 2D TMDCs, which might enable novel spintronics applications.

  10. Numerical modelling of thermal effects in rats due to high-field magnetic resonance imaging (0.5 1 GHz)

    NASA Astrophysics Data System (ADS)

    Trakic, Adnan; Crozier, Stuart; Liu, Feng

    2004-12-01

    A finite-difference time-domain (FDTD) thermal model has been developed to compute the temperature elevation in the Sprague Dawley rat due to electromagnetic energy deposition in high-field magnetic resonance imaging (MRI). The field strengths examined ranged from 11.75-23.5 T (corresponding to 1H resonances of 0.5-1 GHz) and an N-stub birdcage resonator was used to both transmit radio-frequency energy and receive the MRI signals. With an in-plane resolution of 1.95 mm, the inhomogeneous rat phantom forms a segmented model of 12 different tissue types, each having its electrical and thermal parameters assigned. The steady-state temperature distribution was calculated using a Pennes 'bioheat' approach. The numerical algorithm used to calculate the induced temperature distribution has been successfully validated against analytical solutions in the form of simplified spherical models with electrical and thermal properties of rat muscle. As well as assisting with the design of MRI experiments and apparatus, the numerical procedures developed in this study could help in future research and design of tumour-treating hyperthermia applicators to be used on rats in vivo.

  11. Numerical modelling of thermal effects in rats due to high-field magnetic resonance imaging (0.5-1 GHZ).

    PubMed

    Trakic, Adnan; Crozier, Stuart; Liu, Feng

    2004-12-21

    A finite-difference time-domain (FDTD) thermal model has been developed to compute the temperature elevation in the Sprague Dawley rat due to electromagnetic energy deposition in high-field magnetic resonance imaging (MRI). The field strengths examined ranged from 11.75-23.5 T (corresponding to 1H resonances of 0.5-1 GHz) and an N-stub birdcage resonator was used to both transmit radio-frequency energy and receive the MRI signals. With an in-plane resolution of 1.95 mm, the inhomogeneous rat phantom forms a segmented model of 12 different tissue types, each having its electrical and thermal parameters assigned. The steady-state temperature distribution was calculated using a Pennes 'bioheat' approach. The numerical algorithm used to calculate the induced temperature distribution has been successfully validated against analytical solutions in the form of simplified spherical models with electrical and thermal properties of rat muscle. As well as assisting with the design of MRI experiments and apparatus, the numerical procedures developed in this study could help in future research and design of tumour-treating hyperthermia applicators to be used on rats in vivo.

  12. Hybrid excitations due to crystal field, spin-orbit coupling, and spin waves in LiFePO4

    NASA Astrophysics Data System (ADS)

    Yiu, Yuen; Le, Manh Duc; Toft-Peterson, Rasmus; Ehlers, Georg; McQueeney, Robert J.; Vaknin, David

    2017-03-01

    We report on the spin waves and crystal field excitations in single crystal LiFePO4 by inelastic neutron scattering over a wide range of temperatures, below and above the antiferromagnetic transition of this system. In particular, we find extra excitations below TN=50 K that are nearly dispersionless and are most intense around magnetic zone centers. We show that these excitations correspond to transitions between thermally occupied excited states of Fe2 + due to splitting of the S =2 levels that arise from the crystal field and spin-orbit interactions. These excitations are further amplified by the highly distorted nature of the oxygen octahedron surrounding the iron atoms. Above TN, magnetic fluctuations are observed up to at least 720 K, with an additional inelastic excitation around 4 meV, which we attribute to single-ion effects, as its intensity weakens slightly at 720 K compared to 100 K, which is consistent with the calculated cross sections using a single-ion model. Our theoretical analysis, using the MF-RPA model, provides both detailed spectra of the Fe d shell and estimates of the average ordered magnetic moment and TN. By applying the MF-RPA model to a number of existing spin-wave results from other Li M PO4 (M =Mn , Co, and Ni), we are able to obtain reasonable predictions for the moment sizes and transition temperatures.

  13. PDT - PARTICLE DISPLACEMENT TRACKING SOFTWARE

    NASA Technical Reports Server (NTRS)

    Wernet, M. P.

    1994-01-01

    Particle Imaging Velocimetry (PIV) is a quantitative velocity measurement technique for measuring instantaneous planar cross sections of a flow field. The technique offers very high precision (1%) directionally resolved velocity vector estimates, but its use has been limited by high equipment costs and complexity of operation. Particle Displacement Tracking (PDT) is an all-electronic PIV data acquisition and reduction procedure which is simple, fast, and easily implemented. The procedure uses a low power, continuous wave laser and a Charged Coupled Device (CCD) camera to electronically record the particle images. A frame grabber board in a PC is used for data acquisition and reduction processing. PDT eliminates the need for photographic processing, system costs are moderately low, and reduced data are available within seconds of acquisition. The technique results in velocity estimate accuracies on the order of 5%. The software is fully menu-driven from the acquisition to the reduction and analysis of the data. Options are available to acquire a single image or 5- or 25-field series of images separated in time by multiples of 1/60 second. The user may process each image, specifying its boundaries to remove unwanted glare from the periphery and adjusting its background level to clearly resolve the particle images. Data reduction routines determine the particle image centroids and create time history files. PDT then identifies the velocity vectors which describe the particle movement in the flow field. Graphical data analysis routines are included which allow the user to graph the time history files and display the velocity vector maps, interpolated velocity vector grids, iso-velocity vector contours, and flow streamlines. The PDT data processing software is written in FORTRAN 77 and the data acquisition routine is written in C-Language for 80386-based IBM PC compatibles running MS-DOS v3.0 or higher. Machine requirements include 4 MB RAM (3 MB Extended), a single or

  14. Displaced Homemakers: Unresolved Issues.

    ERIC Educational Resources Information Center

    Zawada, Mary Ann

    1980-01-01

    Problems of today's displaced homemakers overlap with those of women in the 1960s. Problems of women seeking employment are similar to those of minority groups, older workers and welfare recipients. Recent legislation has expanded to fulfill some of the needs of women returning to the labor force. (Author/BEF)

  15. FDTD analysis of temperature elevation in the lens of human and rabbit models due to near-field and far-field exposures at 2.45 GHz.

    PubMed

    Oizumi, Takuya; Laakso, Ilkka; Hirata, Akimasa; Fujiwara, Osamu; Watanabe, Soichi; Taki, Masao; Kojima, Masami; Sasaki, Hiroshi; Sasaki, Kazuyuki

    2013-07-01

    The eye is said to be one of the most sensitive organs to microwave heating. According to previous studies, the possibility of microwave-induced cataract formation has been experimentally investigated in rabbit and monkey eyes, but not for the human eye due to ethical reasons. In the present study, the temperature elevation in the lens, the skin around the eye and the core temperature of numerical human and rabbit models for far-field and near-field exposures at 2.45 GHz are investigated. The temperature elevations in the human and rabbit models were compared with the threshold temperatures for inducing cataracts, thermal pain in the skin and reversible health effects such as heat exhaustion or heat stroke. For plane-wave exposure, the core temperature elevation is shown to be essential both in the human and in the rabbit models as suggested in the international guidelines and standards. For localised exposure of the human eye, the temperature elevation of the skin was essential, and the lens temperature did not reach its threshold for thermal pain. On the other hand, the lens temperature elevation was found to be dominant for the rabbit eye.

  16. Displacement sensors using soft magnetostrictive alloys

    NASA Astrophysics Data System (ADS)

    Hristoforou, E.; Reilly, R. E.

    1994-09-01

    We report results on the response of a family of displacement sensors, which are based on the magentostrictive delay line (MDL) technique, using current conductors orthogonal to the MDL. Such sensing technique is based on the change of the magnetic circuit at 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 applications (gait analysis etc.), while absence of hysteresis and low cost of manufacturing make them competent in this sector of sensor market.

  17. Computing Displacements And Strains From Video Images

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

    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.

  18. Reduced spatial focality of electrical field in tDCS with ring electrodes due to tissue anisotropy.

    PubMed

    Suh, Hyun Sang; Lee, Won Hee; Cho, Young Sun; Kim, Ji-Hwan; Kim, Tae-Seong

    2010-01-01

    For effective stimulation with tDCS, spatial focality of induced electrical field (EF) is one of the important factors to be considered. Recently, there have been some studies to improve the spatial focality via different types of electrodes and their new configurations: some improvements using ring electrodes were reported over the conventional pad electrodes. However, most of these studies assumed isotropic conductivities in the head. In this work, we have investigated the effect of tissue anisotropy on the spatial focality of tDCS with the 4+1 ring electrode configuration via a 3-D high-resolution finite element (FE) head model with anisotropic conductivities in the skull and white matter. By examining the profiles of the induced EF from the head models with isotropic and anisotropic conductivities respectively, we found that the spatial focality of the induced EF significantly drops and get diffused due to tissue anisotropy. Our analysis suggests that it is critical to incorporate tissue anisotropy in the stimulation of the brain via tDCS.

  19. 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)

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

    2007-11-01

    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.

  20. Temperature insensitive measurements of displacement using fiber Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Yang, Shuang; Li, Jun; Xu, Shengming; Sun, Miao; Tang, Yuquan; Gao, Gang; Dong, Fengzhong

    2016-11-01

    Optical fiber Bragg grating (FBG) displacement sensors play an important role in various areas due to the high sensitivity to displacement. However, it becomes a serious problem of FBG cross-sensitivity of temperature and displacement in applications with FBG displacement sensing. This paper presents a method of temperature insensitive measurement of displacement via using an appropriate layout of the sensor. A displacement sensor is constructed with two FBGs mounted on the opposite surface of a cantilever beam. The wavelengths of the FBGs shift with a horizontal direction displacement acting on the cantilever beam. Displacement measurement can be achieved by demodulating the wavelengths difference of the two FBGs. In this case, the difference of the two FBGs' wavelengths can be taken in order to compensate for the temperature effects. Four cantilever beams with different shapes are designed and the FBG strain distribution is quite different from each other. The deformation and strain distribution of cantilever beams are simulated by using finite element analysis, which is used to optimize the layout of the FBG displacement sensor. Experimental results show that an obvious increase in the sensitivity of this change on the displacement is obtained while temperature dependence greatly reduced. A change in the wavelength can be found with the increase of displacement from 0 to 10mm for a cantilever beam. The physical size of the FBG displacement sensor head can be adjusted to meet the need of different applications, such as structure health monitoring, smart material sensing, aerospace, etc.

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

    SciTech Connect

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

    2006-02-01

    Approximately 2.2 million internally displaced persons (''IDPs'') in Darfur are living in dense camps scattered in arid areas with low fuelwood productivity. Unsustainable harvesting of fuelwood by the IDPs has created ever increasing zones of denudation, that now (in November 2005) have reached several kilometers from the camp boundaries. Leaving the safety of the camps to fetch fuelwood from farther and farther away imposes great risk and hardship on the IDP women. Three different metal fuel efficient stove (''FES'') designs were tested in Darfur IDP camps for their suitability to substantially reduce the fuelwood needs of IDPs. The mud-and-dung ''ITDG'' stoves being promoted under the current FES program were also examined and tested. A modified design of the ITDG mud-and-dung stove, ''Avi'', was developed, built and tested. Systematic informal surveys of IDP households were undertaken in North and South Darfur to understand the household parameters related to family size, food, fuel, cooking habits, cooking pots, expenditure on fuel, and preferences related to alternative ways to spend time/money if fuel could be saved. Surveys found that a significant fraction of families are missing meals for lack of fuel (50% in South Darfur, and 90% in the North Darfur camps visited by the mission). About 60% of women in South Darfur, and about 90% of women in North Darfur camps purchase fuelwood. Selling some of the food rations to purchase fuel to cook meals was significant (40%) in South Darfur and has become common (80%) in North Darfur. The LBNL mission found that two of the metal stoves and the mud-and-dung Avi can significantly reduce fuelwood consumption using the same fuel, pot, cooking methods, and food ingredients used by Darfur IDPs. The most suitable design for Darfur conditions would be a modified ''Tara'' stove. With training of the cooks in tending the fire, this stove can save 50% fuel for the IDPs. The stove costs less than $10 (US) to produce in Darfur

  2. A field trial on the effect of propylene glycol on displaced abomasum, removal from herd, and reproduction in fresh cows diagnosed with subclinical ketosis.

    PubMed

    McArt, J A A; Nydam, D V; Oetzel, G R

    2012-05-01

    The purpose was to determine the effect of oral propylene glycol (PG) administration in fresh cows diagnosed with subclinical ketosis (SCK). Measured outcomes were development of displaced abomasum (DA) and removal from herd in the first 30 d in milk (DIM), conception to first service, and time to conception within 150 DIM. Cows from 4 freestall dairy herds (2 in New York and 2 in Wisconsin) were each tested 6 times for SCK from 3 to 16 DIM on Mondays, Wednesdays, and Fridays using the Precision Xtra meter (Abbott Laboratories, Abbott Park, IL). Subclinical ketosis was defined as a blood β-hydroxybutyrate concentration of 1.2 to 2.9 mmol/L. Cows with SCK were randomized to treatment group (oral PG) or untreated control group (no PG); treatment cows were orally drenched with 300 mL of PG once daily from the day they tested 1.2 to 2.9 mmol/L until the day they tested <1.2 mmol/L. Mixed effects multivariable Poisson regression was used to assess the effect of PG on DA, removal from herd, and conception to first service; a semiparametric proportional hazards model was used to evaluate the days-to-conception outcome. A total of 741 of 1,717 (43.2%) eligible enrolled cows had at least 1 β-hydroxybutyrate test of 1.2 to 2.9 mmol/L. Of these, 372 were assigned to the PG treatment group and 369 to the control group. Thirty-nine cows (5.3%) developed a DA after testing positive for SCK and 30 cows (4.0%) died or were sold within the first 30 DIM. Based on risk ratios, control cows were 1.6 times more likely [95% confidence interval (CI)=1.3 to 2.0] to develop a DA and 2.1 times more likely (95% CI=1.2 to 3.6) to die or be sold than cows treated with PG. In addition, PG-treated cows were 1.3 times more likely (risk ratio 95% CI=1.1 to 1.5) to conceive at first insemination than control cows in 3 of the herds. No difference was observed in days to conception within 150 DIM between treatment groups (hazard ratio for PG cows=1.1, 95% CI=0.8 to 1.4), with a median time to

  3. Study of Surface Displacements on Tunnelling under Buildings Using 3DEC Numerical Modelling

    PubMed Central

    Rebello, Nalini; Sastry, V. R.

    2014-01-01

    Underground structures at shallow depths are often constructed for metro lines, either in loose or dense layered soils. Tunnelling in urban areas is predominantly under surface structures and on tunnelling, innumerable changes in the form of distortion take place in strata surrounding the tunnel. Extent of displacement/damage to buildings or the tunnel-soil structure interaction depends on the type of building and nature of strata. Effect on displacements has been less studied in granular soils compared to other types of soils like clays. In this paper, parametric studies are conducted to find the displacements at surface, in granular soil conditions, due to varying building storeys and building eccentricities from the tunnel centre line. Effect of presence of geosynthetic layer under footings is further studied. Prior to the parametric studies, validity of the model used is checked with field data available for a stretch of tunnel in South India. Results of simulation studies reveal that inclusion of building reduces displacements at the surface in the dense strata. In very dense strata, the displacements increase as compared to the case without a building. As the centre of the building moves away from the tunnel centre line, settlement above the tunnel matches displacements in the case without building. Applicability of 3DEC software is checked with respect to the present study. PMID:27437472

  4. Study of Surface Displacements on Tunnelling under Buildings Using 3DEC Numerical Modelling.

    PubMed

    Rebello, Nalini; Sastry, V R; Shivashankar, R

    2014-01-01

    Underground structures at shallow depths are often constructed for metro lines, either in loose or dense layered soils. Tunnelling in urban areas is predominantly under surface structures and on tunnelling, innumerable changes in the form of distortion take place in strata surrounding the tunnel. Extent of displacement/damage to buildings or the tunnel-soil structure interaction depends on the type of building and nature of strata. Effect on displacements has been less studied in granular soils compared to other types of soils like clays. In this paper, parametric studies are conducted to find the displacements at surface, in granular soil conditions, due to varying building storeys and building eccentricities from the tunnel centre line. Effect of presence of geosynthetic layer under footings is further studied. Prior to the parametric studies, validity of the model used is checked with field data available for a stretch of tunnel in South India. Results of simulation studies reveal that inclusion of building reduces displacements at the surface in the dense strata. In very dense strata, the displacements increase as compared to the case without a building. As the centre of the building moves away from the tunnel centre line, settlement above the tunnel matches displacements in the case without building. Applicability of 3DEC software is checked with respect to the present study.

  5. Liquid CO2 Displacement of Water in a Dual-Permeability Pore Network Micromodel

    SciTech Connect

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

    2011-09-01

    Permeability contrasts exist in multilayer geological formations under consideration for carbon sequestration. To improve our understanding of heterogeneous pore-scale displacements, liquid CO2 (LCO2) - 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 two orders of magnitude. LCO2 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, LCO2 displaced water in the low permeability zone with capillary fingering as the dominant mechanism. LCO2 saturation (SLCO2) as a function of injection rate was quantified using fluorescent microscopy. In all experiments, more than 50% of LCO2 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 SLCO2 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 SLCO2.

  6. The photoelectric displacement converter

    NASA Astrophysics Data System (ADS)

    Dragoner, Valeriu V.

    2005-02-01

    In the article are examined questions of constructing photoelectric displacement converter satisfying demands that are stated above. Converter has channels of approximate and precise readings. The approximate reading may be accomplished either by the method of reading from a code mask or by the method of the consecutive calculation of optical scale gaps number. Phase interpolator of mouar strips" gaps is determined as a precise measuring. It is shown mathematical model of converter that allow evaluating errors and operating speed of conversion.

  7. Tunable beam displacer

    SciTech Connect

    Salazar-Serrano, Luis José; Valencia, Alejandra; Torres, Juan P.

    2015-03-15

    We report the implementation of a tunable beam displacer, composed of a polarizing beam splitter (PBS) and two mirrors, that divides an initially polarized beam into two parallel beams whose separation can be continuously tuned. The two output beams are linearly polarized with either vertical or horizontal polarization and no optical path difference is introduced between them. The wavelength dependence of the device as well as the maximum separation between the beams achievable is limited mainly by the PBS characteristics.

  8. Variable displacement vane pump

    SciTech Connect

    Tschantz, J.S.; Bisson, B.J.

    1997-12-31

    What has been developed under this program is a pumping system which can vary the amount of fuel delivered according to engine needs, thereby reducing the temperature rise of the fuel to very low levels. This permits the elimination of the air/oil coolers and conserves the vital airflow through the fan. The variable displacement vane pump (VDVP) also permits a substantial simplification of the control system with the elimination of complex metering valves, offering a significant reduction in fuel system cost. This program was initiated to develop a technology that embodied the ruggedness of the gear pump with the efficiency and metering versatility of the variable displacement vane pump. Thick metal vanes emulate the teeth on pumping gears while the simple, elegant swing cam feature provides the variable displacement capability without the unwieldy multiple cam segments found in other concepts. The result is a pumping architecture which is rugged, light in weight and extremely versatile, having demonstrated superb heat management and controllability in extensive bench and engine testing. This paper will report the results that the pumps have achieved to date both in terms of durability and efficiency.

  9. Subsidence due to geothermal fluid withdrawal

    SciTech Connect

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

    1984-12-01

    Single-phase and two-phase geothermal reservoirs are currently being exploited for power production in Italy, Mexico, New Zealand, the United States, and elsewhere. Vertical ground displacements of up to 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. In this paper, 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. Finally, 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.

  10. Subsidence due to geothermal fluid withdrawal

    SciTech Connect

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

    1982-10-01

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

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

    SciTech Connect

    Ertan, H.B.

    1999-09-01

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

  12. Wireless Measurement of Rotation and Displacement Rate

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E.; Taylor, Bryant D.

    2007-01-01

    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.

  13. 24 CFR 582.335 - Displacement, relocation, and real property acquisition.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... for displaced persons. A displaced person (defined in paragraph (f) of this section) must be provided... “displaced person,” or the amount of relocation assistance for which the person is eligible, may file a... to the HUD field office. (f) Definition of displaced person. (1) For purposes of this section,...

  14. Field observations of seismic velocity changes caused by shaking-induced damage and healing due to mesoscopic nonlinearity

    NASA Astrophysics Data System (ADS)

    Gassenmeier, M.; Sens-Schönfelder, C.; Eulenfeld, T.; Bartsch, M.; Victor, P.; Tilmann, F.; Korn, M.

    2016-03-01

    To investigate temporal seismic velocity changes due to earthquake related processes and environmental forcing in Northern Chile, we analyse 8 yr of ambient seismic noise recorded by the Integrated Plate Boundary Observatory Chile (IPOC). By autocorrelating the ambient seismic noise field measured on the vertical components, approximations of the Green's functions are retrieved and velocity changes are measured with Coda Wave Interferometry. At station PATCX, we observe seasonal changes in seismic velocity caused by thermal stress as well as transient velocity reductions in the frequency range of 4-6 Hz. Sudden velocity drops occur at the time of mostly earthquake-induced ground shaking and recover over a variable period of time. We present an empirical model that describes the seismic velocity variations based on continuous observations of the local ground acceleration. The model assumes that not only the shaking of large earthquakes causes velocity drops, but any small vibrations continuously induce minor velocity variations that are immediately compensated by healing in the steady state. We show that the shaking effect is accumulated over time and best described by the integrated envelope of the ground acceleration over the discretization interval of the velocity measurements, which is one day. In our model, the amplitude of the velocity reduction as well as the recovery time are proportional to the size of the excitation. This model with two free scaling parameters fits the data of the shaking induced velocity variation in remarkable detail. Additionally, a linear trend is observed that might be related to a recovery process from one or more earthquakes before our measurement period. A clear relationship between ground shaking and induced velocity reductions is not visible at other stations. We attribute the outstanding sensitivity of PATCX to ground shaking and thermal stress to the special geological setting of the station, where the subsurface material

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Hill, Charles S.; Oliveras, Ovidio M.

    2011-01-01

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

  17. Quantification of the vocal folds’ dynamic displacements

    NASA Astrophysics Data System (ADS)

    del Socorro Hernández-Montes, María; Muñoz, Silvino; De La Torre, Manuel; Flores, Mauricio; Pérez, Carlos; Mendoza-Santoyo, Fernando

    2016-05-01

    Fast dynamic data acquisition techniques are required to investigate the motional behavior of the vocal folds (VFs) when they are subjected to a steady air-flow through the trachea. High-speed digital holographic interferometry (DHI) is a non-invasive full-field-of-view technique that has proved its usefulness to study rapid and non-repetitive object movements. Hence it is an ideal technique used here to measure VF displacements and vibration patterns at 2000 fps. Analyses from a set of 200 displacement images showed that VFs’ vibration cycles are established along their width (y) and length (x). Furthermore, the maximum deformation for the right and left VFs’ area may be quantified from these images, which in itself represents an important result in the characterization of this structure. At a controlled air pressure, VF displacements fall within the range ~100-1740 nm, with a calculated precision and accuracy that yields a variation coefficient of 1.91%. High-speed acquisition of full-field images of VFs and their displacement quantification are on their own significant data in the study of their functional and physiological behavior since voice quality and production depend on how they vibrate, i.e. their displacement amplitude and frequency. Additionally, the use of high speed DHI avoids prolonged examinations and represents a significant scientific and technological alternative contribution in advancing the knowledge and working mechanisms of these tissues.

  18. Enhancement of electron-positron pair creation due to transient excitation of field-induced bound states

    NASA Astrophysics Data System (ADS)

    Jiang, M.; Lv, Q. Z.; Sheng, Z. M.; Grobe, R.; Su, Q.

    2013-04-01

    We study the creation of electron-positron pairs induced by two spatially separated electric fields that vary periodically in time. The results are based on large-scale computer simulations of the time-dependent Dirac equation in reduced spatial dimensions. When the separation of the fields is very large, the pair creation is caused by multiphoton transitions and mainly determined by the frequency of the fields. However, for small spatial separations a coherence effect can be observed that can enhance or reduce the particle yield compared to the case of two infinitely separated fields. If the travel time for a created electron or positron between both field locations becomes comparable to the period of the oscillating fields, we observe peaks in the energy spectrum which can be explained in terms of field-induced transient bound states.

  19. Timing of Landform Displacements along the Mojave Section of the San Andreas Fault: A Comparison of Field-based and Remote Reconstructions at Two Sites

    NASA Astrophysics Data System (ADS)

    Barr, M. A.; Cowgill, E.

    2013-12-01

    Determining the Holocene slip rate of the Mojave section of the San Andreas Fault (MSAF) is key for assessing the earthquake hazard that this ~150-km-long section of fault poses to the Los Angeles metropolitan area, which is located ~45 km to the southwest. Possible temporal variations in slip rate along the MSAF are suggested by an apparent discrepancy between geologically and geodetically determined slip rates, with rates from geologic observations reported to be up to twice as fast as those reported from geodetic data. This apparent variability could be the result of changes in slip rate over time, which is known as secular variation in slip. To test the hypothesis that the MSAF exhibits variability in slip rate over time requires establishing not just a Holocene-average slip rate, but a Holocene slip history. Previous work along the MSAF using remote, virtual-reality based analysis of B4 LiDAR topographic data and pilot field observations identified ~60 potential slip-rate sites with landform offsets between 30 and 300 m, 10 of which are particularly promising. We are currently conducting detailed, field-based studies at two of these 10 sites (Oakdale and Shoemaker Canyon), with an emphasis on collecting age and offset data to determine both Holocene-average slip rates and constrain slip-history analysis. Initial offset estimates were made by remote analysis using 3D visualization software with 1-meter resolution LiDAR (Light Detection and Ranging) data. We plan to excavate exploratory, fault-parallel trenches both northwest and southeast of the fault to constrain the ages of offset landforms, correlate depositional events across the fault, and test the offset estimates that were determined remotely. Upon establishing the stratigraphic relationships of lithologic units within the trenches and correlating this stratigraphy across the fault, we plan to employ geochronologic techniques to quantify the age of depositional events. The nature of the deposits will

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

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

  1. An electromechanical displacement transducer

    NASA Astrophysics Data System (ADS)

    Villiers, Marius; Mahboob, Imran; Nishiguchi, Katsuhiko; Hatanaka, Daiki; Fujiwara, Akira; Yamaguchi, Hiroshi

    2016-08-01

    Two modes of an electromechanical resonator are coupled through the strain inside the structure with a cooperativity as high as 107, a state-of-the-art value for purely mechanical systems, which enables the observation of normal-mode splitting. This coupling is exploited to transduce the resonator’s fundamental mode into the bandwidth of the second flexural mode, which is 1.4 MHz higher in frequency. Thus, an all-mechanical heterodyne detection scheme is implemented that can be developed into a high-precision displacement sensor.

  2. Water displacement during sparging under perched water-table conditions

    SciTech Connect

    DiGiulio, D.C.

    1995-12-31

    The feasibility of using sparging to purposefully displace perched water in silt loam soils was evaluated at a field site in northwestern Oklahoma. Soils and groundwater are contaminated with petroleum hydrocarbons, trichloroethene (TCE), and vinyl chloride. During sparging, a transient response in water level measurements was observed in observation wells which is attributed to water displacement. Evidence of water displacement was manifested by water-table collapse upon the cessation of sparging.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  4. Polyimidazoles via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  5. Polyimidazoles via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  6. Monitoring Changes in Soil Water Content Using Subsurface Displacement

    NASA Astrophysics Data System (ADS)

    Thrash, C. J.; Miller, S.; Murdoch, L. C.; Germanovich, L. N.; Gates, J. B.; Volkmer, A.; Weinburg, A.

    2013-12-01

    Closing the water balance is important in many research and water resource applications, but it can be difficult to accomplish due to a variety of factors. A new technique that measures vertical displacement of soil in order to estimate the change in mass of water stored in overlying material is being developed. The measurement technique uses an extensometer that functions as a lysimeter, and we refer to the technique as Displacement Extensometry for Lysimetric Terrain Analysis (DELTA). DELTA extensometers are 2-m-long devices deployed by creating a friction fit with intact soil below a cased borehole. The instrument measures small displacements (better than 10 nm resolution) in response to changes of mass in the overlying soil, or other factors. The instrument averages over a region that scales with the depth of installation (the radius of influence is approximately 2x the depth). The spatial averaging of this instrument extends over regions representative of agricultural fields, hydrologic model grid blocks, and small watersheds. Five DELTA extensometers have been deployed at a field site near Clemson, SC at depths of 3, 6, and 9 m within saprolite derived from biotite gneiss. Barometric pressure, precipitation, and soil moisture are being measured along with displacement. Signals from the co-located extensometers are remarkably similar, demonstrating reproducibility of the technique. Rainfall causes soil compression, and at 6 m depth there is approximately 200 nm of compression per 1 mm of rainfall. There is gradual expansion, which ranges from 0.15 to 1.75 μm/day, following rainfall. The gradual unloading of the soil is interpreted as water loss due to evapotranspiration. Superimposed on the signal are diurnal fluctuations of 0.5 to 1 μm, which correlate to changes in barometric pressure. Four DELTA extensometers were recently deployed in hard, clayey sediments at two field locations south of Amarillo, TX. The instruments will compliment current research on

  7. Angular displacement measuring device

    NASA Technical Reports Server (NTRS)

    Seegmiller, H. Lee B. (Inventor)

    1992-01-01

    A system for measuring the angular displacement of a point of interest on a structure, such as aircraft model within a wind tunnel, includes a source of polarized light located at the point of interest. A remote detector arrangement detects the orientation of the plane of the polarized light received from the source and compares this orientation with the initial orientation to determine the amount or rate of angular displacement of the point of interest. The detector arrangement comprises a rotating polarizing filter and a dual filter and light detector unit. The latter unit comprises an inner aligned filter and photodetector assembly which is disposed relative to the periphery of the polarizer so as to receive polarized light passing the polarizing filter and an outer aligned filter and photodetector assembly which receives the polarized light directly, i.e., without passing through the polarizing filter. The purpose of the unit is to compensate for the effects of dust, fog and the like. A polarization preserving optical fiber conducts polarized light from a remote laser source to the point of interest.

  8. Angular displacement measuring device

    NASA Astrophysics Data System (ADS)

    Seegmiller, H. Lee B.

    1992-08-01

    A system for measuring the angular displacement of a point of interest on a structure, such as aircraft model within a wind tunnel, includes a source of polarized light located at the point of interest. A remote detector arrangement detects the orientation of the plane of the polarized light received from the source and compares this orientation with the initial orientation to determine the amount or rate of angular displacement of the point of interest. The detector arrangement comprises a rotating polarizing filter and a dual filter and light detector unit. The latter unit comprises an inner aligned filter and photodetector assembly which is disposed relative to the periphery of the polarizer so as to receive polarized light passing the polarizing filter and an outer aligned filter and photodetector assembly which receives the polarized light directly, i.e., without passing through the polarizing filter. The purpose of the unit is to compensate for the effects of dust, fog and the like. A polarization preserving optical fiber conducts polarized light from a remote laser source to the point of interest.

  9. 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

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

    2012-01-01

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

  10. Monitoring pipe line stress due to ground displacement

    SciTech Connect

    Greenwood, J.H. Jr.

    1986-04-01

    Northwest Pipeline Corp. has a large-diameter natural gas pipe line system from Ignacio, Colo., to Sumas, Wash. At Douglas Pass in Colorado, large landslides required several sections of the line to be relocated outside the slide areas: 4,400 ft of new line in April 1962 and 3,200 ft in March 1963. No serious disruptions occurred for the next 16 years. Then in July 1979, some 1,200 ft had to be relocated. From 1980 to date, many landslides in the Douglas Pass area have caused new deformations, with the springs of 1983 and 1984 being the worst years. In 1980, Northwest Pipeline began engineering and geotechnical studies of the landslide problems. These led to instrumentation and pipe monitoring which indicated that pipe failure can be predicted and prevented if important slope deformations or increases in pipe stresses are detected early enough to implement some mitigating measures. Excavation of the pipe to relieve the stresses was used in most cases. The method was so successful that no pipe failure occurred in 1984 within instrumented sections, in spite of the exceptionally bad climatic conditions experienced.

  11. Simple and sensitive strain gauge displacement transducer

    NASA Astrophysics Data System (ADS)

    Ramana, Y. V.; Sarma, L. P.

    1981-09-01

    We describe a simple and sensitive strain gauge displacement transducer. It is based on the linear movement of a shaft (with two cantilevers and four strain gauges) in a tapered chamber, resulting in a change in resistance proportional to the cantilever deformation. The transducer with its Wheatstone full bridge configuration is calibrated against a mechanical dial indicator of 0.002 mm accuracy for both ac and dc voltage excitations. Its output is linear for measurements of full range displacement up to 25 mm. It has a sensitivity of ±0.0082 mm for ac excitation with a strain indicator whose resolution is ±1 μɛ. It has a dc full range sensitivity of 1.5 mV/V for excitation levels up to 5 V. It can have varied field and laboratory applications wherever displacements are precisely read, recorded, or monitored.

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

    SciTech Connect

    Not Available

    1986-10-01

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

  13. Strong and large area field enhancement outside a microcavity due to propagating surface plasmons and standing wave effect

    NASA Astrophysics Data System (ADS)

    Wang, Meng; Wang, Bin; Sun, Xin; Li, Haoyu; Wang, Feng; Zhang, Yunxia; Huang, Senpeng; Xu, Xiaoxuan; Wang, Yufang; Zhang, Cunzhou

    2016-10-01

    We investigated the optical property of periodic inverted pyramidal microcavities and observed large area field enhancement outside a cavity when the incident wavelength and structure parameters match certain relations. The mechanism of this phenomenon has been studied. Propagating surface plasmons and the standing wave effect both contribute to the field enhancement outside the cavity. The relations between the incident wavelength and structure parameters have been clarified. Based on the relations, one can control the field enhancement outside the cavity for a specific laser wavelength.

  14. External magnetic field dependent shift of superparamagnetic blocking temperature due to core/surface disordered spin interactions.

    PubMed

    Lee, Kwan; Jang, Jung-Tak; Nakano, Hiroshi; Nakagawa, Shigeki; Paek, Sun Ha; Bae, Seongtae

    2017-02-17

    Although the blocking temperature of superparamagnetic nanoparticles (SPNPs) is crucial for various spintronics and biomedical applications, the precise determination of the blocking temperature is still not clear. Here, we present 'intrinsic' and 'extrinsic' characteristics of the blocking temperature in SPNP systems. In zero-field-cooled/field-cooled (ZFC-FC) curves, there was no shift of 'intrinsic blocking temperature' at different applied external (excitation) magnetic fields. However, 'extrinsic blocking temperature' shift is clearly dependent on the external (excitation) magnetic field. According to our newly proposed physical model, the 'intermediate spin layer' located between the core and surface disordered spin layers is primarily responsible for the physical nature of the shift of extrinsic blocking temperature. Our new findings offer possibilities for characterizing the thermally induced physical properties of SPNPs. Furthermore, these findings provide a new empirical approach to indirectly estimate the qualitative degree of the disordered surface spin status in SPNPs.

  15. External magnetic field dependent shift of superparamagnetic blocking temperature due to core/surface disordered spin interactions

    NASA Astrophysics Data System (ADS)

    Lee, Kwan; Jang, Jung-tak; Nakano, Hiroshi; Nakagawa, Shigeki; Paek, Sun Ha; Bae, Seongtae

    2017-02-01

    Although the blocking temperature of superparamagnetic nanoparticles (SPNPs) is crucial for various spintronics and biomedical applications, the precise determination of the blocking temperature is still not clear. Here, we present ‘intrinsic’ and ‘extrinsic’ characteristics of the blocking temperature in SPNP systems. In zero-field-cooled/field-cooled (ZFC-FC) curves, there was no shift of ‘intrinsic blocking temperature’ at different applied external (excitation) magnetic fields. However, ‘extrinsic blocking temperature’ shift is clearly dependent on the external (excitation) magnetic field. According to our newly proposed physical model, the ‘intermediate spin layer’ located between the core and surface disordered spin layers is primarily responsible for the physical nature of the shift of extrinsic blocking temperature. Our new findings offer possibilities for characterizing the thermally induced physical properties of SPNPs. Furthermore, these findings provide a new empirical approach to indirectly estimate the qualitative degree of the disordered surface spin status in SPNPs.

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

    PubMed

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

    2010-10-11

    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.

  17. Helium vs. Proton Induced Displacement Damage in Electronic Materials

    NASA Technical Reports Server (NTRS)

    Ringo, Sawnese; Barghouty, A. F.

    2010-01-01

    In this project, the specific effects of displacement damage due to the passage of protons and helium nuclei on some typical electronic materials will be evaluated and contrasted. As the electronic material absorbs the energetic proton and helium momentum, degradation of performance occurs, eventually leading to overall failure. Helium nuclei traveling at the same speed as protons are expected to impart more to the material displacement damage; due to the larger mass, and thus momentum, of helium nuclei compared to protons. Damage due to displacement of atoms in their crystalline structure can change the physical properties and hence performance of the electronic materials.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  19. Variable displacement blower

    DOEpatents

    Bookout, Charles C.; Stotts, Robert E.; Waring, Douglass R.; Folsom, Lawrence R.

    1986-01-01

    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.

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

    PubMed

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

    2014-05-22

    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.

  1. Multiple crossovers between positive and negative magnetoresistance versus field due to fragile spin structure in metallic GdPd3

    PubMed Central

    Pandey, Abhishek; Mazumdar, Chandan; Ranganathan, R.; Johnston, D. C.

    2017-01-01

    Studies on the phenomenon of magnetoresistance (MR) have produced intriguing and application-oriented outcomes for decades–colossal MR, giant MR and recently discovered extremely large MR of millions of percents in semimetals can be taken as examples. We report here the discovery of novel multiple sign changes versus applied magnetic field of the MR in the cubic intermetallic compound GdPd3. Our study shows that a very strong correlation between magnetic, electrical and magnetotransport properties is present in this compound. The magnetic structure in GdPd3 is highly fragile since applied magnetic fields of moderate strength significantly alter the spin arrangement within the system–a behavior that manifests itself in the oscillating MR. Intriguing magnetotransport characteristics of GdPd3 are appealing for field-sensitive device applications, especially if the MR oscillation could materialize at higher temperature by manipulating the magnetic interaction through perturbations caused by chemical substitutions. PMID:28211520

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    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).

  3. Multiple crossovers between positive and negative magnetoresistance versus field due to fragile spin structure in metallic GdPd3

    NASA Astrophysics Data System (ADS)

    Pandey, Abhishek; Mazumdar, Chandan; Ranganathan, R.; Johnston, D. C.

    2017-02-01

    Studies on the phenomenon of magnetoresistance (MR) have produced intriguing and application-oriented outcomes for decades–colossal MR, giant MR and recently discovered extremely large MR of millions of percents in semimetals can be taken as examples. We report here the discovery of novel multiple sign changes versus applied magnetic field of the MR in the cubic intermetallic compound GdPd3. Our study shows that a very strong correlation between magnetic, electrical and magnetotransport properties is present in this compound. The magnetic structure in GdPd3 is highly fragile since applied magnetic fields of moderate strength significantly alter the spin arrangement within the system–a behavior that manifests itself in the oscillating MR. Intriguing magnetotransport characteristics of GdPd3 are appealing for field-sensitive device applications, especially if the MR oscillation could materialize at higher temperature by manipulating the magnetic interaction through perturbations caused by chemical substitutions.

  4. 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)

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

    1992-01-01

    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.

  5. Loading effects in GPS vertical displacement time series

    NASA Astrophysics Data System (ADS)

    Memin, A.; Boy, J. P.; Santamaría-Gómez, A.; Watson, C.; Gravelle, M.; Tregoning, P.

    2015-12-01

    Surface deformations due to loading, with yet no comprehensive representation, account for a significant part of the variability in geodetic time series. We assess effects of loading in GPS vertical displacement time series at several frequency bands. We compare displacement derived from up-to-date loading models to two global sets of positioning time series, and investigate how they are reduced looking at interannual periods (> 2 months), intermediate periods (> 7 days) and the whole spectrum (> 1day). We assess the impact of interannual loading on estimating velocities. We compute atmospheric loading effects using surface pressure fields from the ECMWF. We use the inverted barometer (IB) hypothesis valid for periods exceeding a week to describe the ocean response to the pressure forcing. We used general circulation ocean model (ECCO and GLORYS) to account for wind, heat and fresh water flux. We separately use the Toulouse Unstructured Grid Ocean model (TUGO-m), forced by air pressure and winds, to represent the dynamics of the ocean response at high frequencies. The continental water storage is described using GLDAS/Noah and MERRA-land models. Non-hydrology loading reduces the variability of the observed vertical displacement differently according to the frequency band. The hydrology loading leads to a further reduction mostly at annual periods. ECMWF+TUGO-m better agrees with vertical surface motion than the ECMWF+IB model at all frequencies. The interannual deformation is time-correlated at most of the locations. It is adequately described by a power-law process of spectral index varying from -1.5 to -0.2. Depending on the power-law parameters, the predicted non-linear deformation due to mass loading variations leads to vertical velocity biases up to 0.7 mm/yr when estimated from 5 years of continuous observations. The maximum velocity bias can reach up to 1 mm/yr in regions around the southern Tropical band.

  6. Variation of Magnetic Fluctuation due to Gas Puffing in Edge Region of Reversed-Field Pinch Plasma

    NASA Astrophysics Data System (ADS)

    Yambe, Kiyoyuki; Hirano, Yoichi; Sakakita, Hajime; Koguchi, Haruhisa

    2016-09-01

    We measured the variation of magnetic and electrostatic fluctuations observed during the gas puffing in the edge region of the toroidal pinch experiment-reversed experiment (TPE-RX) reversed-field pinch plasma. In the short period in which the electron density increased slowly just after the gas puffing, the confinement of fast electrons in the core region was maintained by the decrease in the fast radial magnetic fluctuation with the deepening of the reversal of the toroidal field. During the following period in which the electron density increased rapidly, the radial gradient of electron density decreased, and the loss of fast electrons from the core region increased owing to the increase in the toroidal and radial magnetic fluctuations in the high-frequency band, although the poloidal magnetic fluctuation decreased. Therefore, the confinement of fast electrons would be maintained by keeping the radial gradient of plasma thermal pressure with a moderate neutral particle supply of small quantity in a short time.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  8. Force field analysis suggests a lowering of diffusion barriers in atomic manipulation due to presence of STM tip.

    PubMed

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

    2015-04-10

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

  9. Dc to ac field conversion due to leaky-wave excitation in a plasma slab behind an ionization front

    NASA Astrophysics Data System (ADS)

    Kostin, V. A.; Vvedenskii, N. V.

    2015-03-01

    We present a way for generating coherent tunable electromagnetic radiation through dc to ac field conversion by an ionization front. The conversion is caused by the excitation of leaky waves behind the transversely limited ionization front propagating in a uniform electrostatic field. This differs significantly from the well-known dc-to-ac-radiation-converter models which consider Doppler-like frequency conversion by a transversely unlimited ionization front propagating in a spatially periodic electric field. We explore the dispersion properties and excitation of these leaky waves radiated through the transverse plasma boundary at the Cherenkov angle to the direction of propagation of a superluminal ionization front as dependent on the parameters of the plasma produced and on the speed of the ionization front. It is shown that not only the center frequency but also the duration and waveform of the generated pulse may significantly depend on the speed of the ionization front. The results indicate the possibility of using such converters based on planar photoconductive antennas to create sources of microwave and terahertz radiation with controllable waveforms that are transformed from video to radio pulse when the angle of incident ionizing radiation is tuned.

  10. Helical modulation of the electrostatic plasma potential due to edge magnetic islands induced by resonant magnetic perturbation fields at TEXTOR

    SciTech Connect

    Ciaccio, G. Spizzo, G.; Schmitz, O. Frerichs, H.; Abdullaev, S. S.; Evans, T. E.; White, R. B.

    2015-10-15

    The electrostatic response of the edge plasma to a magnetic island induced by resonant magnetic perturbations to the plasma edge of the circular limiter tokamak TEXTOR is analyzed. Measurements of plasma potential are interpreted by simulations with the Hamiltonian guiding center code ORBIT. We find a strong correlation between the magnetic field topology and the poloidal modulation of the measured plasma potential. The ion and electron drifts yield a predominantly electron driven radial diffusion when approaching the island X-point while ion diffusivities are generally an order of magnitude smaller. This causes a strong radial electric field structure pointing outward from the island O-point. The good agreement found between measured and modeled plasma potential connected to the enhanced radial particle diffusivities supports that a magnetic island in the edge of a tokamak plasma can act as convective cell. We show in detail that the particular, non-ambipolar drifts of electrons and ions in a 3D magnetic topology account for these effects. An analytical model for the plasma potential is implemented in the code ORBIT, and analyses of ion and electron radial diffusion show that both ion- and electron-dominated transport regimes can exist, which are known as ion and electron root solutions in stellarators. This finding and comparison with reversed field pinch studies and stellarator literature suggest that the role of magnetic islands as convective cells and hence as major radial particle transport drivers could be a generic mechanism in 3D plasma boundary layers.

  11. Isothermal Multiple Displacement Amplification

    PubMed Central

    Luthra, Rajyalakshmi; Medeiros, L. Jeffrey

    2004-01-01

    Isothermal multiple strand displacement amplification (IMDA) of the whole human genome is a promising method for procuring abundant DNA from valuable and often limited clinical specimens. However, whether DNA generated by this method is of high quality and a faithful replication of the DNA in the original specimen, allowing for subsequent molecular diagnostic testing, requires verification. In this study, we evaluated the suitability of IMDA-generated DNA (IMDA-DNA) for detecting antigen receptor gene rearrangements, chromosomal translocations, and gene mutations using Southern blot analysis, polymerase chain reaction (PCR) methods, or sequencing methods in 28 lymphoma and leukemia clinical specimens. Molecular testing before and after whole genome amplification of these specimens using the IMDA technique showed concordance in 27 of 28 (96%) specimens. Analysis of IMDA-DNA by Southern blot analysis detected restriction fragments >12 kilobases long. No amplification bias was observed at all loci tested demonstrating that this method can be useful in generating large amounts of unbiased, high molecular weight DNA from limited clinical specimens. PMID:15269301

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

    NASA Astrophysics Data System (ADS)

    Honeycutt, Rebecca L.; Johnson, Steven J.

    1993-04-01

    The sound scattering due to an ambient noise field, approximated by a squared cosine function, is considered for infinite rigid and elastic cylinders and rigid spheres. For the cylinders, it is assumed that the acoustic wave front is parallel to the axis of the cylinder (informally incident). For this assumption, a closed form expression for the scattered sound field-to-incident ambient noise field (signal-to-noise) ratio is obtained not only for the cosine squared directivity, but for any arbitrary directivity which can be expressed in terms of a Fourier series. For the sphere, it is assumed that the noise is circumferentially symmetric which leads to a closed form expression for the signal-to-noise ratio due to a cosine squared directivity.

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Deguchi, Shuji; Watson, William D.

    1990-01-01

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

  15. In field damage of high and low cyanogenic cassava due to a generalist insect herbivore Cyrtomenus bergi (Hemiptera: Cydnidae).

    PubMed

    Riis, Lisbeth; Bellotti, Anthony Charles; Castaño, Oscar

    2003-12-01

    The hypothesis that cyanogenic potential in cassava roots deters polyphagous insects in the field is relevant to current efforts to reduce or eliminate the cyanogenic potential in cassava. To test this hypothesis, experiments were conducted in the field under natural selection pressure of the polyphagous root feeder Cyrtomenus bergi Froeschner (Hemiptera: Cydnidae). A number of cassava varieties (33) as well as 13 cassava siblings and their parental clone, each representing a determined level of cyanogenic potential (CNP), were scored for damage caused by C. bergi and related to CNP and nonglycosidic cyanogens, measured as hydrogen cyanide. Additionally, 161 low-CNP varieties (< 50 ppm hydrogen cyanide, fresh weight) from the cassava germplasm core collection at Centro Internacional de Agricultura Tropical (CIAT) were screened for resistance/tolerance to C. bergi. Low root damage scores were registered at all levels of CNP. Nevertheless, CNP and yield (or root size) partly explained the damage in cassava siblings (r2 = 0.82) and different cassava varieties (r2 = 0.42), but only when mean values of damage scores were used. This relation was only significant in one of two crop cycles. A logistic model describes the underlying negative relation between CNP and damage. An exponential model describes the underlying negative relation between root size and damage. Damage, caused by C. bergi feeding, released nonglycosidic cyanogens, and an exponential model fits the underlying positive relation. Fifteen low-CNP clones were selected for potential resistance/tolerance against C. bergi.

  16. Displacement, Substitution, Sublimation: A Bibliography.

    ERIC Educational Resources Information Center

    Pedrini, D. T.; Pedrini, Bonnie C.

    Sigmund Freund worked with the mechanisms of displacement, substitution, and sublimation. These mechanisms have many similarities and have been studied diagnostically and therapeutically. Displacement and substitution seem to fit in well with phobias, hysterias, somatiyations, prejudices, and scapegoating. Phobias, prejudices, and scapegoating…

  17. Miscible porous media displacements driven by non-vertical injection wells

    NASA Astrophysics Data System (ADS)

    Upchurch, E.; Meiburg, E.

    High-resolution simulations are employed to identify and analyse the mechanisms dominating miscible porous media displacements generated by inclined injection wells. Compared to vertical injection wells, significant differences are observed that strongly influence breakthrough times and recovery rates. Constant density and viscosity displacements, for which the velocity field is potential in nature, demonstrate the existence of pronounced flow non-uniformities, due to the interaction of the inclined well with the reservoir boundaries. These non-uniformities deform the fronts during the initial displacement stages.In the presence of a viscosity difference, the non-uniformities of the potential flow field result in a focusing of the fingering instability. If the fluids also have different densities, a gravity tongue will reinforce the dominant finger along one front, while a gravitational instability leads to the disintegration of the dominant finger along the other front. Hence, the two fronts emerging from the inclined injection well usually evolve very differently from each other for variable density and viscosity displacements.For inclined injection wells and sufficiently large mobility ratios, gravity tongues are seen to evolve dendritically for an intermediate range of density contrasts. While mild gravitational forces are necessary to create the gravity tongue in the first place, large density differences will suppress the growth of the dendritic side branches. Since the dendritic branches appear along the side of the gravity tongue that should be stable according to traditional stability criteria, it can be concluded that the tip region plays a crucial role in their formation.

  18. Watching the wind: seismic data contamination at long-periods due to atmospheric pressure-field-induced tilting

    NASA Astrophysics Data System (ADS)

    de Angelis, S.; Bodin, P.; Hagel, K.; Fletcher, D.

    2010-12-01

    Long-period noise generated by the elastic response of the Earth to atmospheric pressure fluctuations has long been recognized as a limiting factor for seismic investigations. The quality of seismic data recorded by sensitive, near-surface broadband seismometers can be severely corrupted by this effect. During the recent installation of a new broadband site on the Olympic Peninsula in Washington, the Pacific Northwest Seismic Network recorded and investigated elevated daytime noise levels at periods exceeding 30 seconds. Substantial power spectral density variations of the background noise field, 15-20 dB, were observed in the horizontal component seismograms. The pattern of the long-period noise exhibited striking correlations with local fluctuations of the air temperature and wind speed as measured nearby the seismic station by the National Weather Service Forecast Office, Seattle, Washington, and the National Oceanic and Atmospheric Administration. Several past studies have demonstrated that local wind systems may lead to variations of the atmospheric pressure field that deform the ground and perturb seismograms. The rotational component of this motion is detected by horizontal-component seismometers because at periods longer than the sensor’s low corner frequency the sensor is acting essentially as a tiltmeter. We obtained a transfer function that describes the response of the broadband seismometer to a tilt step change and estimated the amplitude of tilt noise to be on the order of 10-9 - 10-8 radians. Within the seismic pass-band of the sensor, it is not possible to remove the tilt signal from the observed seismograms because the details of the tilting depend on the pressure field variations, the compliance of the near surface to pressure variations, and the design and construction of the seismometer vault itself. At longer periods, using the seismic data to recover tilts of tectonic origin is made challenging because of the needed instrument correction

  19. Permeability enhancement due to cold water injection: A Case Study at the Los Azufres Geothermal Field, Mexico

    SciTech Connect

    Benson, S.M.; Daggett, J.; Ortiz, J.; Iglesias, E.; Comision Federal de Electricidad, Morelia; Instituto de Investigaciones Electricas, Cuernavaca )

    1989-04-01

    Pressure transient buildup and falloff data from 3 wells at the Los Azufres geothermal field have been evaluated to determine the extent to which cold water infection increases the permeability of the near-bore reservoir formation. Simultaneous analysis of the buildup and falloff data provides estimates of the permeability-thickness of the reservoir, the skin factor of the well, and the degree of permeability enhancement in the region behind the thermal front. Estimates of permeability enhancement range from a factor of 4 to 9, for a temperature change of about 150{degree}C. The permeability enhancement is attributed to thermally induced contraction and stress-cracking of the formation. 9 refs., 18 figs.

  20. Density profile steepening due to self-generated magnetic fields in plasmas produced by laser irradiation of spherical targets

    SciTech Connect

    Vyas, P.; Srivastava, M.P.

    1995-07-01

    The density variation of plasmas produced by irradiation with laser beams on spherical targets has been studied in the steady state. This study used an adiabatic plasma model with self-generated magnetic fields included in a phenomenological manner. The density variation with a radial coordinate is found to have a steep rise through the critical density, which reaches a plateau in the overdense region, then a density minimum and finally, a rise. This variation has been compared with experimentally observed values in earlier works and is found to be in fairly good agreement. The variation of plateau density with the intensity of the laser is also compared with the experimentally observed variation. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

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

    PubMed

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

    2005-10-01

    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.

  2. Systematic errors in two-dimensional digital image correlation due to lens distortion

    NASA Astrophysics Data System (ADS)

    Pan, Bing; Yu, Liping; Wu, Dafang; Tang, Liqun

    2013-02-01

    Lens distortion practically presents in a real optical imaging system causing non-uniform geometric distortion in the recorded images, and gives rise to additional errors in the displacement and strain results measured by two-dimensional digital image correlation (2D-DIC). In this work, the systematic errors in the displacement and strain results measured by 2D-DIC due to lens distortion are investigated theoretically using the radial lens distortion model and experimentally through easy-to-implement rigid body, in-plane translation tests. Theoretical analysis shows that the displacement and strain errors at an interrogated image point are not only in linear proportion to the distortion coefficient of the camera lens used, but also depend on its distance relative to distortion center and its magnitude of displacement. To eliminate the systematic errors caused by lens distortion, a simple linear least-squares algorithm is proposed to estimate the distortion coefficient from the distorted displacement results of rigid body, in-plane translation tests, which can be used to correct the distorted displacement fields to obtain unbiased displacement and strain fields. Experimental results verify the correctness of the theoretical derivation and the effectiveness of the proposed lens distortion correction method.

  3. Annoyance and self-reported sleep disturbance due to night-time railway noise examined in the field.

    PubMed

    Pennig, Sibylle; Quehl, Julia; Mueller, Uwe; Rolny, Vinzent; Maass, Hartmut; Basner, Mathias; Elmenhorst, Eva-Maria

    2012-11-01

    Railway noise interferes with daytime activities and disturbs sleep leading to annoyance of exposed residents. The main objective of this paper was to establish exposure-response relationships between nocturnal railway noise exposure and annoyance and to examine self-reported sleep disturbances as short-term reactions to noise. In a field study 33 residents living close to railway tracks in the Cologne/Bonn area (Germany) were investigated. Railway noise was measured indoors during nine consecutive nights at each site. Questionnaires referring to annoyance and non-acoustical factors were performed. Annoyance ratings increased significantly with the total number of trains and freight trains per night, and non-significantly with rising number of passenger trains and energy equivalent sound pressure level (L(Aeq)), when adjusting the model for non-acoustical variables. The total number of trains and the number of freight trains also significantly affected self-reported awakening frequency, but no other aspects of subjective sleep disturbances. The responses of this subject sample referring to railway noise in the previous night point to rather low impairments of exposed residents.

  4. Variation of bulk Lorentz factor in AGN jets due to Compton rocket in a complex photon field

    NASA Astrophysics Data System (ADS)

    Vuillaume, T.; Henri, G.; Petrucci, P.-O.

    2015-09-01

    Radio-loud active galactic nuclei are among the most powerful objects in the universe. In these objects, most of the emission comes from relativistic jets getting their power from the accretion of matter ontosupermassive black holes. However, despite the number of studies, a jet's acceleration to relativistic speeds is still poorly understood. It is widely known that jets contain relativistic particles that emit radiation through several physical processes, one of them being the inverse Compton scattering of photons coming from external sources. In the case of a plasma composed of electrons and positrons continuously heated by the turbulence, inverse Compton scattering can lead to relativistic bulk motions through the Compton rocket effect. We investigate this process and compute the resulting bulk Lorentz factor in the complex photon field of an AGN composed of several external photon sources. We consider various sources:the accretion disk, the dusty torus, and the broad line region. We take their geometry and anisotropy carefully into account in order to numerically compute the bulk Lorentz factor of the jet at every altitude. The study, made for a broad range of parameters, shows interesting and unexpected behaviors of the bulk Lorentz factor, exhibiting acceleration and deceleration zones in the jet. We investigate the patterns of the bulk Lorentz factor along the jet depending on the source sizes and on the observation angle and we finally show that these patterns can induce variability in the AGN emission with timescales going from hours to months.

  5. Regenerative rotary displacer Stirling engine

    SciTech Connect

    Isshiki, Naotsugu; Watanabe, Hiroichi; Raggi, L.; Isshiki, Seita; Hirata, Koichi

    1996-12-31

    A few rotary displacer Stirling engines in which the displacer has one gas pocket space at one side and rotates in a main enclosed cylinder, which is heated from one side and cooled from opposite side without any regenerator, have been studied for some time by the authors. The authors tried to improve this engine by equipping it with a regenerator, because without a regenerator, pressure oscillation and efficiency are too small. Here, several types of regenerative rotary displacer piston Stirling engines are proposed. One is the contra-rotating tandem two disc type displacer engine using axial heat conduction through side walls or by heat pipes and another is a single disc type with circulating fluid regenerator or heat pipes. Stirling engines of this new rotary displacer type are thought to attain high speed. Here, experimental results of the original rotary displacer Stirling engine without a regenerator, and one contra-rotating tandem displacer engine with side wall regenerator by axial heat conduction are reported accompanied with a discussion of the results.

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

    PubMed Central

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

    2015-01-01

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

  7. Measuring fast stochastic displacements of bio-membranes with dynamic optical displacement spectroscopy.

    PubMed

    Monzel, C; Schmidt, D; Kleusch, C; Kirchenbüchler, D; Seifert, U; Smith, A-S; Sengupta, K; Merkel, R

    2015-10-06

    Stochastic displacements or fluctuations of biological membranes are increasingly recognized as an important aspect of many physiological processes, but hitherto their precise quantification in living cells was limited due to a lack of tools to accurately record them. Here we introduce a novel technique--dynamic optical displacement spectroscopy (DODS), to measure stochastic displacements of membranes with unprecedented combined spatiotemporal resolution of 20 nm and 10 μs. The technique was validated by measuring bending fluctuations of model membranes. DODS was then used to explore the fluctuations in human red blood cells, which showed an ATP-induced enhancement of non-Gaussian behaviour. Plasma membrane fluctuations of human macrophages were quantified to this accuracy for the first time. Stimulation with a cytokine enhanced non-Gaussian contributions to these fluctuations. Simplicity of implementation, and high accuracy make DODS a promising tool for comprehensive understanding of stochastic membrane processes.

  8. Measuring fast stochastic displacements of bio-membranes with dynamic optical displacement spectroscopy

    NASA Astrophysics Data System (ADS)

    Monzel, C.; Schmidt, D.; Kleusch, C.; Kirchenbüchler, D.; Seifert, U.; Smith, A.-S.; Sengupta, K.; Merkel, R.

    2015-10-01

    Stochastic displacements or fluctuations of biological membranes are increasingly recognized as an important aspect of many physiological processes, but hitherto their precise quantification in living cells was limited due to a lack of tools to accurately record them. Here we introduce a novel technique--dynamic optical displacement spectroscopy (DODS), to measure stochastic displacements of membranes with unprecedented combined spatiotemporal resolution of 20 nm and 10 μs. The technique was validated by measuring bending fluctuations of model membranes. DODS was then used to explore the fluctuations in human red blood cells, which showed an ATP-induced enhancement of non-Gaussian behaviour. Plasma membrane fluctuations of human macrophages were quantified to this accuracy for the first time. Stimulation with a cytokine enhanced non-Gaussian contributions to these fluctuations. Simplicity of implementation, and high accuracy make DODS a promising tool for comprehensive understanding of stochastic membrane processes.

  9. Apes Communicate about Absent and Displaced Objects: Methodology Matters

    PubMed Central

    Lyn, Heidi; Russell, Jamie L.; Leavens, David A.; Bard, Kim A.; Boysen, Sarah T.; Schaeffer, Jennifer A.; Hopkins, William D.

    2013-01-01

    Displaced reference is the ability to refer to an item that has been moved (displaced) in space and/or time, and has been called one of the true hallmarks of referential communication. Several studies suggest that nonhuman primates have this capability, but a recent experiment concluded that in a specific situation (absent entities) human infants display displaced reference but chimpanzees do not. Here we show that chimpanzees and bonobos of diverse rearing histories are capable of displaced reference to absent and displaced objects. It is likely that some of the conflicting findings from animal cognition studies are due to relatively minor methodological differences, but are compounded by interpretation errors. Comparative studies are of great importance in elucidating the evolution of human cognition, however, greater care must be taken with methodology and interpretation for these studies to accurately reflect species differences. PMID:23681052

  10. Displacement Energies for Nanorods

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Arnold, James O. (Technical Monitor)

    1996-01-01

    The geometries have been optimized and harmonic frequencies computed for three small hydrocarbon rods. The two lowest unique frequencies correspond to a torsion and a bend of the rods. The energy to bend or twist the rods has been computed by adding a fraction of the normal coordinate corresponding to these two modes to the equilibrium geometry. The density functional theory (using B3LYP) and self-consistent field (SCF) results are very similar for all properties considered.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  12. Effects of rippled fields due to ferritic inserts and ELM mitigation coils on energetic ion losses in a 15 MA inductive scenario in ITER

    NASA Astrophysics Data System (ADS)

    Shinohara, K.; Tani, K.; Oikawa, T.; Putvinski, S.; Schaffer, M.; Loarte, A.

    2012-09-01

    The energetic ion loss has been assessed using the F3D-OFMC code for a 15 MA inductive scenario with Q = 10 and the latest information on the first wall geometry, the implementation of ferritic inserts (FI) and the ELM mitigation/control coils. Alpha particles and NB ions generated by the neutral beam injectors with the injection energy of 1 MeV are well confined and the heat load on the first wall is negligibly small and allowable for the magnetic background by the toroidal field coils and FI. However, an increase in the loss of these energetic ions is observed when the magnetic field by the ELM coils is applied. The increase in the loss fraction is larger for NB ions than for alpha particles under the ELM coil field. The origin of the expelled NB ions is dominantly trapped ions generated in the peripheral region due to a high-density plasma of the 15 MA scenario.

  13. Rapid Sunspot Displacement Associated with Solar Eruptions

    NASA Astrophysics Data System (ADS)

    Liu, Chang; Deng, N.; Wang, H.

    2010-05-01

    Many observational and modeling studies of solar eruptions merely treat photosphere as the lower boundary and assume no significant changes of magnetic fields anchoring there to occur during flares/CMEs. With increasing evidence of photospheric magnetic fields variations resulting from energy release in the upper atmosphere, Hudson, Fisher and Welsch (2008, ASP, 383, 221) proposed that the photosphere and even solar interior would respond in a back-reaction process to the coronal magnetic field restructuring. Inspired by this concept, we analyzed white-light images obtained with TRACE and report here rapid and permanent perturbation in the position of delta spot umbrae associated with five X-class flares. Our main results are the following: (1) The centroids of umbrae with opposite magnetic polarities undergo relative as well as overall displacement on the order of 1E3 km after flares/CMEs. (2) The estimated total kinetic energy associated with these motions (Ek) is on the order of 1E29 ergs and appears to correlate with the 6 mHZ seismic energy (Es) derived by the Monash group. (3) There appears correlation between both the Ek and Es corresponding to the velocity of CMEs. We suggest that: (1) sunspot displacement provides a direct observational evidence of the photospheric back-reaction and could potentially serve as an alternative excitation mechanism of seismic waves; (2) These could provide rational support to the back-reaction mechanism in the sense that its magnitude might be related to how violent the coronal magnetic field is disrupted. For selected events with good multiwavelength coverage, we also analyze in detail spatial as well as temporal relationship among the sunspot displacement, magnetic field changes, seismic sources, hard X-ray emissions, and overall flaring condition. This work is supported by NSF grants ATM 08-19662 and ATM 07-45744, and NASA grants NNX 08AQ90G, NNX 07AH78G, and NNX 08AQ32G.

  14. Displacement sensing system and method

    DOEpatents

    VunKannon, Jr., Robert S

    2006-08-08

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

  15. Wirelessly Interrogated Position or Displacement Sensors

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E.; Taylor, Bryant D.

    2007-01-01

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

  16. The role of environmental degradation in population displacement.

    PubMed

    Lonergan, S

    1998-01-01

    This article answers a series of questions about the role of environmental degradation in population displacement, refugee movement, and migration. The environment tends not to be included in the reasons for migration. Roger's indicators of migration potential include population growth, economic restructuring, increased economic disparities, and increased refugee flows. Myers (1993) estimated that international displacement and internal displacement may amount to about 25 million and may rise to 150 million by 2050. The role of the environment in displacement must be examined in the broader political and cultural context. Definitions of environmental refugees are ambiguous and inconsistent, and research has not answered why people continue to move to Mexico City and Chongqing, China, which both have very high levels of pollution. El-Hinnawi (1985) defined 3 groups of environmental refugees: those displaced due to natural disasters; those displaced due to permanent habitat changes; and those displaced who migrated from areas that cannot support their basic needs and who desire an improved quality of life. Lonergan (1994) identified environmental stresses as natural disasters, cumulative or slow-onset changes, accidental disruptions or industrial accidents, development projects, and conflict and warfare. These 5 causes must be treated separately and not lumped together as environmental degradation. Shoreline erosion, coastal flooding, and agricultural disruption associated with climate change may increase migration. Global measures must address world poverty and promote sustainable development.

  17. A Vision-Based Sensor for Noncontact Structural Displacement Measurement.

    PubMed

    Feng, Dongming; Feng, Maria Q; Ozer, Ekin; Fukuda, Yoshio

    2015-07-09

    Conventional displacement sensors have limitations in practical applications. This paper develops a vision sensor system for remote measurement of structural displacements. An advanced template matching algorithm, referred to as the upsampled cross correlation, is adopted and further developed into a software package for real-time displacement extraction from video images. By simply adjusting the upsampling factor, better subpixel resolution can be easily achieved to improve the measurement accuracy. The performance of the vision sensor is first evaluated through a laboratory shaking table test of a frame structure, in which the displacements at all the floors are measured by using one camera to track either high-contrast artificial targets or low-contrast natural targets on the structural surface such as bolts and nuts. Satisfactory agreements are observed between the displacements measured by the single camera and those measured by high-performance laser displacement sensors. Then field tests are carried out on a railway bridge and a pedestrian bridge, through which the accuracy of the vision sensor in both time and frequency domains is further confirmed in realistic field environments. Significant advantages of the noncontact vision sensor include its low cost, ease of operation, and flexibility to extract structural displacement at any point from a single measurement.

  18. A Vision-Based Sensor for Noncontact Structural Displacement Measurement

    PubMed Central

    Feng, Dongming; Feng, Maria Q.; Ozer, Ekin; Fukuda, Yoshio

    2015-01-01

    Conventional displacement sensors have limitations in practical applications. This paper develops a vision sensor system for remote measurement of structural displacements. An advanced template matching algorithm, referred to as the upsampled cross correlation, is adopted and further developed into a software package for real-time displacement extraction from video images. By simply adjusting the upsampling factor, better subpixel resolution can be easily achieved to improve the measurement accuracy. The performance of the vision sensor is first evaluated through a laboratory shaking table test of a frame structure, in which the displacements at all the floors are measured by using one camera to track either high-contrast artificial targets or low-contrast natural targets on the structural surface such as bolts and nuts. Satisfactory agreements are observed between the displacements measured by the single camera and those measured by high-performance laser displacement sensors. Then field tests are carried out on a railway bridge and a pedestrian bridge, through which the accuracy of the vision sensor in both time and frequency domains is further confirmed in realistic field environments. Significant advantages of the noncontact vision sensor include its low cost, ease of operation, and flexibility to extract structural displacement at any point from a single measurement. PMID:26184197

  19. Variations in proton scanned beam dose delivery due to uncertainties in magnetic beam steering.

    PubMed

    Peterson, Stephen; Polf, Jerimy; Ciangaru, George; Frank, Steven J; Bues, Martin; Smith, Al

    2009-08-01

    The purpose of this work was to develop a method to calculate and study the impact of fluctuations in the magnetic field strengths within the steering magnets in a proton scanning beam treatment nozzle on the dose delivered to the patient during a proton therapy treatment. First, an analytical relationship between magnetic field uncertainties in the steering magnets and the resulting lateral displacements in the position of the delivered scanned beam "dose spot" was established. Next, using a simple 3D dose calculation code and data from a validated Monte Carlo model of the proton scanning beam treatment nozzle, the uniform dose delivery to a 3D treatment volume was calculated. The dose distribution was then recalculated using the calculated lateral displacements due to magnetic field fluctuations to the proton pencil beam position. Using these two calculated dose distributions, the clinical effects of the magnetic field fluctuations were determined. A deliberate displacement of four adjacent spots either toward or away from each other was used to determine the "maximum" dose impact, while a random displacement of all spots was used to establish a more realistic clinical dose impact. Changes in the dose volume histogram (DVH) and the presence of hot and cold spots in the treatment volume were used to quantify the impact of dose-spot displacement. A general analytical relationship between magnetic field uncertainty and final dose-spot position is presented. This analytical relationship was developed such that it can be applied to study magnetic beam steering for any scanned beam nozzle design. Using this relationship the authors found for the example beam steering nozzle used in this study that deliberate lateral displacements of 0.5 mm or random lateral displacements of up to 1.0 mm produced a noticeable dose impact (5% hot spot) in the treatment volume. A noticeable impact (3% decrease in treatment volume coverage) on the DVH was observed for random displacements

  20. Utilisation of the magnetic sensor in a smartphone for facile magnetostatics experiment: magnetic field due to electrical current in straight and loop wires

    NASA Astrophysics Data System (ADS)

    Septianto, R. D.; Suhendra, D.; Iskandar, F.

    2017-01-01

    This paper reports on the result of a research into the utilisation of a smartphone for the study of magnetostatics on the basis of experiments. The use of such a device gives great measurement result and thus it can replace magnetic sensor tools that are relatively expensive. For the best experimental result, firstly the position of the magnetic sensor in the smartphone has to be considered by way of value mapping of a magnetic field due to permanent magnet. The magnetostatics experiment investigated in this research was the measurement of magnetic field due to electrical currents in two shapes of wire, straight and looped. The current flow, the distance between the observation point and the wire, and the diameter of the loop were the variable parameters investigated to test the smartphone’s capabilities as a measurement tool. To evaluate the experimental results, the measured data were compared with theoretical values that were calculated by using both an analytical and a numerical approach. According to the experiment results, the measured data had good agreement with the results from the analytical and the numerical approach. This means that the use of the magnetic sensor in a smartphone in physics experiments is viable, especially for magnetic field measurement.

  1. Comparing Teaching Approaches About Maxwell's Displacement Current

    NASA Astrophysics Data System (ADS)

    Karam, Ricardo; Coimbra, Debora; Pietrocola, Maurício

    2014-08-01

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

  2. Contactless sub-millimeter displacement measurements

    NASA Astrophysics Data System (ADS)

    Sliepen, Guus; Jägers, Aswin P. L.; Bettonvil, Felix C. M.; Hammerschlag, Robert H.

    2008-07-01

    Weather effects on foldable domes, as used at the DOT and GREGOR, are investigated, in particular the correlation between the wind field and the stresses caused to both metal framework and tent clothing. Camera systems measure contactless the displacement of several dome points. The stresses follow from the measured deformation pattern. The cameras placed near the dome floor do not disturb telescope operations. In the set-ups of DOT and GREGOR, these cameras are up to 8 meters away from the measured points and must be able to detect displacements of less than 0.1 mm. The cameras have a FireWire (IEEE1394) interface to eliminate the need for frame grabbers. Each camera captures 15 images of 640 × 480 pixels per second. All data is processed on-site in real-time. In order to get the best estimate for the displacement within the constraints of available processing power, all image processing is done in Fourier-space, with all convolution operations being pre-computed once. A sub-pixel estimate of the peak of the correlation function is made. This enables to process the images of four cameras using only one commodity PC with a dual-core processor, and achieve an effective sensitivity of up to 0.01 mm. The deformation measurements are well correlated to the simultaneous wind measurements. The results are of high interest to upscaling the dome design (ELTs and solar telescopes).

  3. Impacts of plasma-induced damage due to UV light irradiation during etching on Ge fin fabrication and device performance of Ge fin field-effect transistors

    NASA Astrophysics Data System (ADS)

    Mizubayashi, Wataru; Noda, Shuichi; Ishikawa, Yuki; Nishi, Takashi; Kikuchi, Akio; Ota, Hiroyuki; Su, Ping-Hsun; Li, Yiming; Samukawa, Seiji; Endo, Kazuhiko

    2017-02-01

    We investigated the impacts of plasma-induced damage due to UV light irradiation during etching on Ge fin fabrication and the device performance of Ge fin field-effect transistors (Ge FinFETs). UV light irradiation during etching affected the shape of the Ge fin and the surface roughness of the Ge fin sidewall. A vertical and smooth Ge fin could be fabricated by neutral beam etching without UV light irradiation. The performances of Ge FinFETs fabricated by neutral beam etching were markedly improved as compared to those of Ge FinFETs fabricated by inductively coupled plasma etching, in which the UV light has an impact.

  4. Combined MRI-PET scanner: A Monte Carlo evaluation of the improvements in PET resolution due to the effects of a static homogeneous magnetic field

    SciTech Connect

    Raylman, R.R.; Hammer, B.E.; Christensen, N.L.

    1996-08-01

    Positron emission tomography (PET) relies upon the detection of photons resulting from the annihilation of positrons emitted by a radiopharmaceutical. The combination of images obtained with PET and magnetic resonance imaging (MRI) have begun to greatly enhance the study of many physiological processes. A combined MRI-PET scanner could alleviate much of the spatial and temporal coregistration difficulties currently encountered in utilizing images from these complementary imaging modalities. In addition, the resolution of the PET scanner could be improved by the effects of the magnetic field. In this computer study, the utilization of a strong static homogeneous magnetic field to increase PET resolution by reducing the effects of positron range and photon noncollinearity was investigated. The results reveal that significant enhancement of resolution can be attained. For example, an approximately 27% increase in resolution is predicted for a PET scanner incorporating a 10-Tesla magnetic field. Most of this gain in resolution is due to magnetic confinement of the emitted positrons. Although the magnetic field does mix some positronium states resulting in slightly less photon noncollinearity, this reduction does not significantly affect resolution. Photon noncollinearity remains as the fundamental limiting factor of large PET scanner resolution.

  5. Job Displacement Among Single Mothers:

    PubMed Central

    Brand, Jennie E.; Thomas, Juli Simon

    2015-01-01

    Given the recent era of economic upheaval, studying the effects of job displacement has seldom been so timely and consequential. Despite a large literature associating displacement with worker well-being, relatively few studies focus on the effects of parental displacement on child well-being, and fewer still focus on implications for children of single parent households. Moreover, notwithstanding a large literature on the relationship between single motherhood and children’s outcomes, research on intergenerational effects of involuntary employment separations among single mothers is limited. Using 30 years of nationally representative panel data and propensity score matching methods, we find significant negative effects of job displacement among single mothers on children’s educational attainment and social-psychological well-being in young adulthood. Effects are concentrated among older children and children whose mothers had a low likelihood of displacement, suggesting an important role for social stigma and relative deprivation in the effects of socioeconomic shocks on child well-being. PMID:25032267

  6. Perceived displacement explains wolfpack effect

    PubMed Central

    Šimkovic, Matúš; Träuble, Birgit

    2014-01-01

    We investigate the influence of perceived displacement of moving agent-like stimuli on the performance in dynamic interactive tasks. In order to reliably measure perceived displacement we utilize multiple tasks with different task demands. The perceived center of an agent's body is displaced in the direction in which the agent is facing and this perceived displacement is larger than the theoretical position of the center of mass would predict. Furthermore, the displacement in the explicit judgment is dissociated from the displacement obtained by the implicit measures. By manipulating the location of the pivot point, we show that it is not necessary to postulate orientation as an additional cue utilized by perception, as has been suggested by earlier studies. These studies showed that the agent's orientation influences the detection of chasing motion and the detection-related performance in interactive tasks. This influence has been labeled wolfpack effect. In one of the demonstrations of the wolfpack effect participants control a green circle on a display with a computer mouse. It has been shown that participants avoid display areas with agents pointing toward the green circle. Participants do so in favor of areas where the agents point in the direction perpendicular to the circle. We show that this avoidance behavior arises because the agent's pivot point selected by the earlier studies is different from where people locate the center of agent's body. As a consequence, the nominal rotation confounds rotation and translation. We show that the avoidance behavior disappears once the pivot point is set to the center of agent's body. PMID:25566114

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

    PubMed Central

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

    2013-01-01

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

  8. Particle displacement tracking for PIV

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P.

    1990-01-01

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

  9. Rotor component displacement measurement system

    DOEpatents

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

    2003-05-27

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

  10. Equatorial E region electric fields at the dip equator: 2. Seasonal variabilities and effects over Brazil due to the secular variation of the magnetic equator

    NASA Astrophysics Data System (ADS)

    Moro, J.; Denardini, C. M.; Resende, L. C. A.; Chen, S. S.; Schuch, N. J.

    2016-10-01

    In this work, the seasonal dependency of the E region electric field (EEF) at the dip equator is examined. The eastward zonal (Ey) and the daytime vertical (Ez) electric fields are responsible for the overall phenomenology of the equatorial and low-latitude ionosphere, including the equatorial electrojet (EEJ) and its plasma instability. The electric field components are studied based on long-term backscatter radars soundings (348 days for both systems) collected during geomagnetic quiet days (Kp ≤ 3+), from 2001 to 2010, at the São Luís Space Observatory (SLZ), Brazil (2.33°S, 44.20°W), and at the Jicamarca Radio Observatory (JRO), Peru (11.95°S, 76.87°W). Among the results, we observe, for the first time, a seasonal difference between the EEF in these two sectors in South America based on coherent radar measurements. The EEF is more intense in summer at SLZ, in equinox at JRO, and has been highly variable with season in the Brazilian sector compared to the Peruvian sector. In addition, the secular variation on the geomagnetic field and its effect on the EEJ over Brazil resulted that as much farther away is the magnetic equator from SLZ, later more the EEJ is observed (10 h LT) and sooner it ends (16 h LT). Moreover, the time interval of type II occurrence decreased significantly after the year 2004, which is a clear indication that SLZ is no longer an equatorial station due to the secular variation of the geomagnetic field.

  11. Monte Carlo simulations of patient dose perturbations in rotational-type radiotherapy due to a transverse magnetic field: A tomotherapy investigation

    SciTech Connect

    Yang, Y. M.; Geurts, M.; Smilowitz, J. B.; Bednarz, B. P.; Sterpin, E.

    2015-02-15

    Purpose: Several groups are exploring the integration of magnetic resonance (MR) image guidance with radiotherapy to reduce tumor position uncertainty during photon radiotherapy. The therapeutic gain from reducing tumor position uncertainty using intrafraction MR imaging during radiotherapy could be partially offset if the negative effects of magnetic field-induced dose perturbations are not appreciated or accounted for. The authors hypothesize that a more rotationally symmetric modality such as helical tomotherapy will permit a systematic mediation of these dose perturbations. This investigation offers a unique look at the dose perturbations due to homogeneous transverse magnetic field during the delivery of Tomotherapy{sup ®} Treatment System plans under varying degrees of rotational beamlet symmetry. Methods: The authors accurately reproduced treatment plan beamlet and patient configurations using the Monte Carlo code GEANT4. This code has a thoroughly benchmarked electromagnetic particle transport physics package well-suited for the radiotherapy energy regime. The three approved clinical treatment plans for this study were for a prostate, head and neck, and lung treatment. The dose heterogeneity index metric was used to quantify the effect of the dose perturbations to the target volumes. Results: The authors demonstrate the ability to reproduce the clinical dose–volume histograms (DVH) to within 4% dose agreement at each DVH point for the target volumes and most planning structures, and therefore, are able to confidently examine the effects of transverse magnetic fields on the plans. The authors investigated field strengths of 0.35, 0.7, 1, 1.5, and 3 T. Changes to the dose heterogeneity index of 0.1% were seen in the prostate and head and neck case, reflecting negligible dose perturbations to the target volumes, a change from 5.5% to 20.1% was observed with the lung case. Conclusions: This study demonstrated that the effect of external magnetic fields can

  12. Phase-sensitive lateral motion estimator for measurement of artery-wall displacement--phantom study.

    PubMed

    Hasegawa, Hideyuki; Kanai, Hiroshi

    2009-11-01

    Artery-wall motion due to the pulsation of the heart is often measured to evaluate mechanical properties of the arterial wall. Such motion is thought to occur only in the arterial radial direction because the main source of the motion is an increase of blood pressure. However, it has recently been reported that the artery also moves in the longitudinal direction. Therefore, a 2-D motion estimator is required even when the artery is scanned in the longitudinal direction because the arterial wall moves both in the radial (axial) and longitudinal (lateral) directions. Methods based on 2-D correlation of RF echoes are often used to estimate the lateral displacement together with axial displacement. However, these methods require much interpolation of the RF echo or correlation function to achieve a sufficient resolution in the estimation of displacement. To overcome this problem, Jensen et al. modulated the ultrasonic field in the lateral direction at a designed spatial frequency to use the lateral phase for the estimation of lateral motion. This method, namely, the lateral modulation method, generates complex signals whose phases change depending on the lateral motion. Therefore, the lateral displacement can be estimated with a good resolution without interpolation, although special beamformers are required. The present paper describes a method that can be applied to ultrasonic echoes obtained by a conventional beamformer to estimate lateral displacements using the phases of lateral fluctuations of ultrasonic echoes. In the proposed method, complex signals were generated by the Hilbert transform, and the phase shift was estimated by correlation-based estimators. The proposed method was validated using a cylindrical phantom mimicking an artery. The error in the lateral displacement estimated by the proposed method was 13.5% of the true displacement of 0.5 mm with a kernel size used for calculating the correlation function of 0.6 mm in the lateral direction, which was

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  14. Forest transition in Vietnam and displacement of deforestation abroad

    PubMed Central

    Meyfroidt, Patrick; Lambin, Eric F.

    2009-01-01

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

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

    PubMed

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

    2013-09-30

    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.

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

    PubMed Central

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

    2013-01-01

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

  17. Pattern of dynamic displacements in a strike-slip earthquake

    NASA Astrophysics Data System (ADS)

    Saltogianni, V.; Gianniou, M.; Moschas, F.; Stiros, S.

    2016-07-01

    High-rate (1 Hz) records from GPS stations uniformly distributed along the fault ruptures of the 2014 Samothraki-Gökçeada Mw6.9 earthquake in the North Aegean Trough, at the extension of the North Anatolian Fault Zone, were analyzed using the Precise Point Positioning (PPP) technique. Computed dynamic displacements shed light to the pattern of dynamic displacements during shallow strike-slip earthquakes. The area of near-field static seismic displacements bounds ramp-type, long-period dynamic displacements (fling steps) in the sense of static displacements. Along-fault and normal to fault components of dynamic displacement follow typical attenuation laws, but attenuation is higher in the fault-parallel component hence confined to the area of static dislocations. Forward directivity and local, especially topography-controlled amplification effects, consistent with accelerometer evidence, were also observed. The overall pattern seems to characterize shallow strike-slip earthquakes and is expected to prove useful to explain or even predict the near-field damaging potential of strike-slip earthquakes.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    The Rotliegend reservoir sandstones of the Altmark area (central Germany) comprise the second largest natural gas field of Europe. These sandstones were deposited on a playa-like continental platform with braided river systems, ephemeral lakes and aeolian dunes under semi-arid conditions. Some of the pristine, red coloured deposits suffered intensive late diagenetic alteration and are now preserved as bleached, high porous and permeable sandstones. To evaluate the relevance of distinct fluids and their fluid-rock alteration reactions on such bleaching processes we performed laboratory static batch experiments on the Altmark sandstones. These 4-6 week lasting runs were conducted with CO2 saturated synthetic brines under typical Altmark reservoir conditions (p= 20 MPa, T= 125°C). Thereby mineralogical, petrophysical and (hydro- and geo-) chemical rock features were maintained prior and after the experiments. Chemical data proved the dissolution of carbonate and sulphate minerals during the runs, whereas the variation in abundance of further elements was within the detection limit of analytical accuracy. However, FE-SEM investigations on used, evaporated brines reveal the presence of illite and chlorite minerals within a matrix of Ca-, Si-, Fe, Al-, Na- and S components (carbonate, anhydrite, albite and Fe-(hydr-) oxides ?). By porosity and relative permeability measurements an increase in both rock features was observed after the runs, indicating that mineral dissolution and/or (clay) fine migration/detachment occurred during the experiments. Mineral dissolution, especially of pore-filling cements (e.g. carbonate-, sulphate minerals) is also deduced by BET analysis, in determining the specific surface of the sandstones. The size of these reactive surfaces increased after the experiments, suggesting that after the dissolution of pore-filling cements, formerly armoured grain rimming clay cutans were exposed to potential migrating fluids. These findings are also

  19. Polybenzimidazoles Via Aromatic Nucleophilic Displacement

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    Soluble polybenzimidazoles (PBI's) synthesized by nucleophilic displacement reaction of di(hydroxyphenyl)-benzimidazole monomers with activated aromatic difluoride compounds in presence of anhydrous potassium carbonate. These polymers exhibit good thermal, thermo-oxidative, and chemical stability, and high mechanical properties. Using benzimidazole monomers, more economical, and new PBI's processed more easily than commercial PBI, without loss of desirable physical properties.

  20. Retraining Displaced Workers. Policy Brief

    ERIC Educational Resources Information Center

    LaLonde, Robert; Sullivan, Daniel

    2010-01-01

    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…

  1. Free displacer and Ringbom displacer for a Malone refrigerator

    SciTech Connect

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

    1994-05-01

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

  2. Interplay between interstitial displacement and displacive lattice transformations

    NASA Astrophysics Data System (ADS)

    Zhang, Xie; Hickel, Tilmann; Rogal, Jutta; Neugebauer, Jörg

    2016-09-01

    Diffusionless displacive lattice rearrangements, which include martensitic transformations, are in real materials often accompanied by a displacive drag of interstitials. The interplay of both processes leads to a particular atomistic arrangement of the interstitials in the product phase, which is decisive for its performance. An archetype example is the martensitic transformation in Fe-C alloys. One of the puzzles for this system is that the deviation from the cubic symmetry (i.e., the tetragonality) in the martensite resulting from this interplay is lower than what thermodynamics dictates. In our ab initio approach, the relative motion of C in the transforming lattice is studied with the nudged elastic band method. We prove that an atomic shearlike shuffle mechanism of adjacent (11 2 ¯) Fe layers along the ±[111] bcc directions is essential to achieve a redistribution of C atoms during the fcc → bcc transition, which fully explains the abnormal behavior. Furthermore, the good agreement with experiment validates our method to treat a diffusionless redistribution of interstitials and a displacive rearrangement of the host lattice simultaneously.

  3. Superconducting inductive displacement detection of a microcantilever

    SciTech Connect

    Vinante, A.

    2014-07-21

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

  4. Atomic displacements in quantum crystals

    NASA Astrophysics Data System (ADS)

    Dusseault, Marisa; Boninsegni, Massimo

    2017-03-01

    Displacements of atoms and molecules away from lattice sites in helium and parahydrogen solids at low temperature have been studied by means of quantum Monte Carlo simulations. In the bcc phases of 3He and 4He, atomic displacements are largely quantum-mechanical in character, even at melting. The computed Lindemann ratio at melting is found to be in good agreement with experimental results for 4He. Unlike the case of helium, in solid parahydrogen there exists near melting a significant thermal contribution to molecular vibrations, accounting for roughly half of the total effect. Although the Lindemann ratio at melting is in quantitative agreement with experiment, computed molecular mean square fluctuations feature a clear temperature dependence, in disagreement with recent experimental observations.

  5. Polybenzimidazole via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  6. Polyphenylquinoxalines via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    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.

  7. Polyphenylquinoxalines via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    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.

  8. Single-mode displacement sensor

    NASA Astrophysics Data System (ADS)

    Duivenvoorden, Kasper; Terhal, Barbara M.; Weigand, Daniel

    2017-01-01

    We show that one can determine both parameters of a displacement acting on an oscillator with an accuracy which scales inversely with the square root of the number of photons in the oscillator. Our results are obtained by using a grid state as a sensor state for detecting small translations in phase space (displacements). Grid states were first proposed [D. Gottesman et al., Phys. Rev. A 64, 012310 (2001), 10.1103/PhysRevA.64.012310] for encoding a qubit into an oscillator: an efficient preparation protocol of such states, using a coupling to a qubit, was later developed [B. M. Terhal and D. Weigand, Phys. Rev. A 93, 012315 (2016), 10.1103/PhysRevA.93.012315]. We compare the performance of the grid state with the quantum compass or cat code state and place our results in the context of the two-parameter quantum Cramér-Rao lower bound on the variances of the displacement parameters. We show that the accessible information about the displacement for a grid state increases with the number of photons in the state when we measure and prepare the state using a phase estimation protocol. This is in contrast with the accessible information in the quantum compass state which we show is always upper bounded by a constant, independent of the number of photons. We present numerical simulations of a phase estimation based preparation protocol of a grid state in the presence of photon loss, nonlinearities, and qubit measurement, using no post-selection, showing how the two effective squeezing parameters which characterize the grid state change during the preparation. The idea behind the phase estimation protocol is a simple maximal-information gain strategy.

  9. Deformable image registration for tissues with large displacements.

    PubMed

    Huang, Xishi; Ren, Jing; Abdalbari, Anwar; Green, Mark

    2017-01-01

    Image registration for internal organs and soft tissues is considered extremely challenging due to organ shifts and tissue deformation caused by patients' movements such as respiration and repositioning. In our previous work, we proposed a fast registration method for deformable tissues with small rotations. We extend our method to deformable registration of soft tissues with large displacements. We analyzed the deformation field of the liver by decomposing the deformation into shift, rotation, and pure deformation components and concluded that in many clinical cases, the liver deformation contains large rotations and small deformations. This analysis justified the use of linear elastic theory in our image registration method. We also proposed a region-based neuro-fuzzy transformation model to seamlessly stitch together local affine and local rigid models in different regions. We have performed the experiments on a liver MRI image set and showed the effectiveness of the proposed registration method. We have also compared the performance of the proposed method with the previous method on tissues with large rotations and showed that the proposed method outperformed the previous method when dealing with the combination of pure deformation and large rotations. Validation results show that we can achieve a target registration error of [Formula: see text] and an average centerline distance error of [Formula: see text]. The proposed technique has the potential to significantly improve registration capabilities and the quality of intraoperative image guidance. To the best of our knowledge, this is the first time that the complex displacement of the liver is explicitly separated into local pure deformation and rigid motion.

  10. Technique for Determining Bridge Displacement Response Using MEMS Accelerometers

    PubMed Central

    Sekiya, Hidehiko; Kimura, Kentaro; Miki, Chitoshi

    2016-01-01

    In bridge maintenance, particularly with regard to fatigue damage in steel bridges, it is important to determine the displacement response of the entire bridge under a live load as well as that of each member. Knowing the displacement response enables the identification of dynamic deformations that can cause stresses and ultimately lead to damage and thus also allows the undertaking of appropriate countermeasures. In theory, the displacement response can be calculated from the double integration of the measured acceleration. However, data measured by an accelerometer include measurement errors caused by the limitations of the analog-to-digital conversion process and sensor noise. These errors distort the double integration results. Furthermore, as bridges in service are constantly vibrating because of passing vehicles, estimating the boundary conditions for the numerical integration is difficult. To address these problems, this paper proposes a method for determining the displacement of a bridge in service from its acceleration based on its free vibration. To verify the effectiveness of the proposed method, field measurements were conducted using nine different accelerometers. Based on the results of these measurements, the proposed method was found to be highly accurate in comparison with the reference displacement obtained using a contact displacement gauge. PMID:26907287

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

    SciTech Connect

    Peters, E.J.

    1994-04-01

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

  12. Estimating Hydrologic Processes from Subsurface Soil Displacements

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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

  13. Are seismic velocity time-lapse changes due to fluid substitution or matrix dissolution? A CO2 sequestration study at Pohokura Field, New Zealand

    NASA Astrophysics Data System (ADS)

    Adam, L.; Sim, C. Y.; Macfarlane, J.; van Wijk, K.; Shragge, J. C.; Higgs, K.

    2015-12-01

    Time-lapse seismic signatures can be used to quantify fluid saturation and pressure changes in a reservoir undergoing CO2 sequestration. However, the injection of CO2 acidifies the water, which may dissolve and/or precipitate minerals. Understanding the impact on the rock frame from field seismic time-lapse changes remains an outstanding challenge. Here, we study the effects of carbonate-CO2-water reactions on the physical and elastic properties of rock samples with variable volumes of carbonate cementation. The effects of fluid substitution alone (brine to CO2) and those due to the combination of fluid substitution and mineral dissolution on time-lapse seismic signatures are studied by combining laboratory data, geophysical well-log data and 1-D seismic modeling. Nine rocks from Pohokura Field (New Zealand) are reacted with carbonic acid. The elastic properties are measured using a high-density laser-ultrasonic setup. We observe that P-wave velocity changes up to -19% and correlate with sandstone grain size. Coarse-grained sandstones show greater changes in elastic wave velocities due to dissolution than fine-grained sandstones. To put this in perspective, this velocity change is comparable to the effect of fluid substitution from brine to CO2. This can potentially create an ambiguity in the interpretation of the physical processes responsible for time-lapse signatures in a CO2injection scenario. The laboratory information is applied onto well-log data to model changes in elastic properties of sandstones at the well-log scale. Well-logs and core petrographic analyses are used to find an elastic model that best describes the observed elastic waves velocities in the cemented reservoir sandstones. The Constant-cement rock physics model is found to predict the elastic behaviour of the cemented sandstones. A possible late-time sequestration scenario is that both mineral dissolution and fluid substitution occur in the reservoir. 1-D synthetic seismograms show that

  14. Study of microdosimetric energy deposition patterns in tissue-equivalent medium due to low-energy neutron fields using a graphite-walled proportional counter.

    PubMed

    Waker, A J; Aslam

    2011-06-01

    To improve radiation protection dosimetry for low-energy neutron fields encountered in nuclear power reactor environments, there is increasing interest in modeling neutron energy deposition in metrological instruments such as tissue-equivalent proportional counters (TEPCs). Along with these computational developments, there is also a need for experimental data with which to benchmark and test the results obtained from the modeling methods developed. The experimental work described in this paper is a study of the energy deposition in tissue-equivalent (TE) medium using an in-house built graphite-walled proportional counter (GPC) filled with TE gas. The GPC is a simple model of a standard TEPC because the response of the counter at these energies is almost entirely due to the neutron interactions in the sensitive volume of the counter. Energy deposition in tissue spheres of diameter 1, 2, 4 and 8 µm was measured in low-energy neutron fields below 500 keV. We have observed a continuously increasing trend in microdosimetric averages with an increase in neutron energy. The values of these averages decrease as we increase the simulated diameter at a given neutron energy. A similar trend for these microdosimetric averages has been observed for standard TEPCs and the Rossi-type, TE, spherical wall-less counter filled with propane-based TE gas in the same energy range. This implies that at the microdosimetric level, in the neutron energy range we employed in this study, the pattern of average energy deposited by starter and insider proton recoil events in the gas is similar to those generated cumulatively by crosser and stopper events originating from the counter wall plus starter and insider recoil events originating in the sensitive volume of a TEPC.

  15. Fiber-Optic Differential Displacement Sensor

    NASA Technical Reports Server (NTRS)

    Tcheng, Ping

    1996-01-01

    Dual fiber-optic sensor measures small relative displacements of two proximate objects along common surface. Dual sensor comprises two fiber-optic sensors in differential configuration increasing sensitivity to displacement while decreasing sensitivity to thermal expansion and contraction.

  16. Comparing Teaching Approaches about Maxwell's Displacement Current

    ERIC Educational Resources Information Center

    Karam, Ricardo; Coimbra, Debora; Pietrocola, Maurício

    2014-01-01

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

  17. Intrinsic parameterization of a computational optical system for long-distance displacement structural monitoring

    NASA Astrophysics Data System (ADS)

    Martins, Luís F. Lages; Rebordão, José Manuel N. V.; Ribeiro, Álvaro Silva

    2015-01-01

    We aim at the intrinsic parameterization of a computational optical system applied in long-distance displacement measurement of large-scale structures. In this structural-monitoring scenario, the observation distance established between the digital camera and reference targets, which is composed of the computational optical system, can range from 100 up to 1000 m, requiring the use of long-focal length lenses in order to obtain a suitable sensitivity for the three-dimensional displacement measurement of the observed structure which can be of reduced magnitude. Intrinsic parameterization of long-focal length cameras is an emergent issue since conventional approaches applied for reduced focal length cameras are not suitable mainly due to ill-conditioned matrices in least squares estimation procedures. We describe the intrinsic parameterization of a long-focal length camera (600 mm) by the diffractive optical element method and present the obtained estimates and measurement uncertainties, discussing their contribution for the system's validation by calibration field test and displacement measurement campaigns in a long-span suspension bridge.

  18. Multicomponent seismic monitoring of stress arching in the overburden due to hydraulic fracturing in the Montney Shale at Pouce Coupe Field, Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Vinal, Irene

    Recent studies have shown convincing evidence that time-lapse changes in seismic data occur not only within the reservoir interval but also in the overburden. Observations that production at the reservoir level and subsequent decrease in pore pressure lead to modifications in the stress field and variations in the overburden have been documented (Hatchell et al., 2003; Hudson et al., 2005). The study of the opposite case, that is, the analysis of the effect in the overburden of an increase in pore pressure in the reservoir has not been so well documented yet and is the focus of this work; the possibility that the hydraulic fracturing process causes seismically detectable changes in the overburden in a time-lapse sense is studied at Pouce Coupe Field, Alberta, and the results are shown. The analysis is performed using multicomponent data from three seismic surveys acquired to evaluate the hydraulic stimulations of two horizontal wells in the Montney Shale. The time-lapse time shifts between the data of the two monitor surveys and the baseline have been calculated and constitute the main tool to study the injection-induced changes above the reservoir interval. The hypothesis is that the increase in the reservoir pressure due to the hydraulic well treatment might produce upward overburden compaction, leading to an increase in stresses that would be translated into an increase in the seismic velocities and therefore, into positive time shifts (considering monitor data subtracted from baseline data) if a time window for the overburden is analyzed. The study shows strong differences in the magnitude of the PS response to the stimulations compared to that of the PP data. The fact that mode-converted (PS) waves are more sensitive to azimuthal anisotropy than compressional waves explains the stronger character of the response observed in PS data, allowing for a more detailed interpretation of the stress-arching distribution. The time-lapse time shifts in the overburden

  19. The case for character displacement in plants

    PubMed Central

    Beans, Carolyn M

    2014-01-01

    The evidence for character displacement as a widespread response to competition is now building. This progress is largely the result of the establishment of rigorous criteria for demonstrating character displacement in the animal literature. There are, however, relatively few well-supported examples of character displacement in plants. This review explores the potential for character displacement in plants by addressing the following questions: (1) Why aren't examples of character displacement in plants more common? (2) What are the requirements for character displacement to occur and how do plant populations meet those requirements? (3) What are the criteria for testing the pattern and process of character displacement and what methods can and have been used to address these criteria in the plant literature? (4) What are some additional approaches for studying character displacement in plants? While more research is needed, the few plant systems in which character displacement hypotheses have been rigorously tested suggest that character displacement may play a role in shaping plant communities. Plants are especially amenable to character displacement studies because of the experimental ease with which they can be used in common gardens, selection analyses, and breeding designs. A deeper investigation of character displacement in plants is critical for a more complete understanding of the ecological and evolutionary processes that permit the coexistence of plant species. PMID:24683467

  20. The case for character displacement in plants.

    PubMed

    Beans, Carolyn M

    2014-03-01

    The evidence for character displacement as a widespread response to competition is now building. This progress is largely the result of the establishment of rigorous criteria for demonstrating character displacement in the animal literature. There are, however, relatively few well-supported examples of character displacement in plants. This review explores the potential for character displacement in plants by addressing the following questions: (1) Why aren't examples of character displacement in plants more common? (2) What are the requirements for character displacement to occur and how do plant populations meet those requirements? (3) What are the criteria for testing the pattern and process of character displacement and what methods can and have been used to address these criteria in the plant literature? (4) What are some additional approaches for studying character displacement in plants? While more research is needed, the few plant systems in which character displacement hypotheses have been rigorously tested suggest that character displacement may play a role in shaping plant communities. Plants are especially amenable to character displacement studies because of the experimental ease with which they can be used in common gardens, selection analyses, and breeding designs. A deeper investigation of character displacement in plants is critical for a more complete understanding of the ecological and evolutionary processes that permit the coexistence of plant species.

  1. 40 CFR 205.153 - Engine displacement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Engine displacement. 205.153 Section... TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycles § 205.153 Engine displacement. (a) Engine displacement must be calculated using nominal engine values and rounded to the nearest whole cubic...

  2. 40 CFR 205.153 - Engine displacement.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Engine displacement. 205.153 Section... TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycles § 205.153 Engine displacement. (a) Engine displacement must be calculated using nominal engine values and rounded to the nearest whole cubic...

  3. 25 CFR 700.59 - Displaced person.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 25 Indians 2 2010-04-01 2010-04-01 false Displaced person. 700.59 Section 700.59 Indians THE OFFICE OF NAVAJO AND HOPI INDIAN RELOCATION COMMISSION OPERATIONS AND RELOCATION PROCEDURES General Policies and Instructions Definitions § 700.59 Displaced person. Displaced person means a member of...

  4. Polyphenylquinoxalines via Aromatic Nucleophilic Displacement

    NASA Technical Reports Server (NTRS)

    Hergenrother, Paul M.; Connell, John W.

    1988-01-01

    Polyphenylquinoxalines are produced by an aromatic nucleophilic displacement reaction involving an activated aromatic dihalide with an appropriate quinoxaline monomer. Polyphenylquinoxalines are high temperature thermoplastics used as adhesives, coatings, films and composite matrices. The novelty of this invention is threefold: (1) some of the quinoxaline monomers are new compositions of matter; (2) the phenylquinoxaline polymers which are the end products of the invention are new compositions of matter; and (3) the method of forming the polymers is novel, replacing a more costly prior art process, which is also limited in the kinds of products prepared therefrom.

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

    SciTech Connect

    Podoshvedov, S. A.

    2011-04-15

    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.

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

    USGS Publications Warehouse

    Boore, D.M.

    2003-01-01

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

  7. Current Density and Plasma Displacement Near Perturbed Rational Surface

    SciTech Connect

    A.H. Boozer and N. Pomphrey

    2010-10-10

    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.

  8. In-plane and out-of-plane tissue micro-displacement measurement by correlation coefficients of optical coherence tomography.

    PubMed

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

    2015-05-01

    We propose a method to measure the in-plane and out-of-plane displacements of tissue using the correlation coefficients of optical coherence tomography (OCT) signals. The displacements are determined by the local correlation coefficients between digitally shifted reference OCT images and a target image. The method achieves sub-micron displacement measurement with an accuracy better than 0.32 μm and repeatability better than 0.36 μm. The feasibility of the method was examined by measuring the displacement field of a laser irradiated porcine retina. This method successfully visualized the dynamic change of the displacement field during laser irradiation.

  9. Interferometric fiber optic displacement sensor

    DOEpatents

    Farah, John

    1999-01-01

    A method is presented to produce a change in the optical path length in the gap between two single mode optical fibers proportional to the lateral displacement of either fiber end normal to its axis. This is done with the use of refraction or diffraction at the interface between a guiding and non-guiding media to change the direction of propagation of the light in the gap. A method is also presented for laying a waveguide on a cantilever so that the displacement of the tip of the cantilever produces a proportional path length change in the gap by distancing the waveguide from the neutral axis of the cantilever. The fiber is supported as a cantilever or a waveguide is deposited on a micromachined cantilever and incorporated in an interferometer which is made totally on a silicon substrate with the use of integrated-optic technology. A resonant element in the form of a micro-bridge is incorporated in the ridge waveguide and produces a frequency output which is readily digitizeable and immune to laser frequency noise. Finally, monolithic mechanical means for phase modulation are provided on the same sensor substrate. This is done by vibrating the cantilever or micro-bridge either electrically or optically.

  10. Interferometric fiber optic displacement sensor

    DOEpatents

    Farah, J.

    1999-04-06

    A method is presented to produce a change in the optical path length in the gap between two single mode optical fibers proportional to the lateral displacement of either fiber end normal to its axis. This is done with the use of refraction or diffraction at the interface between a guiding and non-guiding media to change the direction of propagation of the light in the gap. A method is also presented for laying a waveguide on a cantilever so that the displacement of the tip of the cantilever produces a proportional path length change in the gap by distancing the waveguide from the neutral axis of the cantilever. The fiber is supported as a cantilever or a waveguide is deposited on a micromachined cantilever and incorporated in an interferometer which is made totally on a silicon substrate with the use of integrated-optic technology. A resonant element in the form of a micro-bridge is incorporated in the ridge waveguide and produces a frequency output which is readily digitizeable and immune to laser frequency noise. Finally, monolithic mechanical means for phase modulation are provided on the same sensor substrate. This is done by vibrating the cantilever or micro-bridge either electrically or optically. 23 figs.

  11. Interferometric fiber optic displacement sensor

    DOEpatents

    Farah, John

    1995-01-01

    A method is presented to produce a change in the optical path length in the gap between two single mode optical fibers proportional to the lateral displacement of either fiber end normal to its axis. This is done with the use of refraction or diffraction at the interface between a guiding and non-guiding media to change the direction of propagation of the light in the gap. A method is also presented for laying a waveguide on a cantilever so that the displacement of the tip of the cantilever produces a proportional path length change in the gap by distancing the waveguide from the neutral axis of the cantilever. The fiber is supported as a cantilever or a waveguide is deposited on a micromachined cantilever and incorporated in an interferometer which is made totally on a silicon substrate with the use of integrated-optic technology. A resonant element in the form of a micro-bridge is incorporated in the ridge waveguide and produces a frequency output which is readily digitizeable and immune to laser frequency noise. Finally, monolithic mechanical means for phase modulation are provided on the same sensor substrate. This is done by vibrating the cantilever or micro-bridge either electrically or optically.

  12. Interferometric fiber optic displacement sensor

    DOEpatents

    Farah, J.

    1995-05-30

    A method is presented to produce a change in the optical path length in the gap between two single mode optical fibers proportional to the lateral displacement of either fiber end normal to its axis. This is done with the use of refraction or diffraction at the interface between a guiding and non-guiding media to change the direction of propagation of the light in the gap. A method is also presented for laying a waveguide on a cantilever so that the displacement of the tip of the cantilever produces a proportional path length change in the gap by distancing the waveguide from the neutral axis of the cantilever. The fiber is supported as a cantilever or a waveguide is deposited on a micromachined cantilever and incorporated in an interferometer which is made totally on a silicon substrate with the use of integrated-optic technology. A resonant element in the form of a micro-bridge is incorporated in the ridge waveguide and produces a frequency output which is readily digitizeable and immune to laser frequency noise. Finally, monolithic mechanical means for phase modulation are provided on the same sensor substrate. This is done by vibrating the cantilever or micro-bridge either electrically or optically. 29 figs.

  13. Displacement damage effects in silicon MEMS at high proton doses

    NASA Astrophysics Data System (ADS)

    Gomes, João; Shea, Herbert R.

    2011-02-01

    We report on a study of the sensitivity of silicon MEMS to proton radiation and mitigation strategies. MEMS can degrade due to ionizing radiation (electron-hole pair creation) and non-ionizing radiation (displacement damage), such as electrons, trapped and solar protons, or cosmic rays, typically found in a space environment. Over the past few years there has been several reports on the effects of ionizing radiation in silicon MEMS, with failure generally linked to trapped charge in dielectrics. However there is near complete lack of studies on displacement damage effects in silicon- MEMS: how does silicon change mechanically due to proton irradiation? We report on an investigation on the susceptibility of 50 μm thick SOI-based MEMS resonators to displacement damages due to proton beams, with energies from 1 to 60 MeV, and annealing of this damage. We measure ppm changes on the Young's modulus and Poisson ratio by means of accurately monitoring the resonant frequency of devices in vacuum using a Laser Doppler Vibrometer. We observed for the first time an increase (up to 0.05%) of the Young's modulus of single-crystal silicon electromagnetically-actuated micromirrors after exposure to low energy protons (1-4 MeV) at high absorbed doses ~ 100 Mrad (Si). This investigation will contribute to a better understanding of the susceptibility of silicon-based MEMS to displacement damages frequently encountered in a space radiation environment, and allow appropriated design margin and shielding to be implemented.

  14. Multiple crossovers between positive and negative magnetoresistance versus field due to fragile spin structure in metallic GdPd3 [Oscillating magnetoresistance due to fragile spin structure in metallic GdPd3

    DOE PAGES

    Pandey, Abhishek; Mazumdar, Chandan; Ranganathan, R.; ...

    2017-02-17

    Here, studies on the phenomenon of magnetoresistance (MR) have produced intriguing and application-oriented outcomes for decades–colossal MR, giant MR and recently discovered extremely large MR of millions of percents in semimetals can be taken as examples. We report here the discovery of novel multiple sign changes versus applied magnetic field of the MR in the cubic intermetallic compound GdPd3. Our study shows that a very strong correlation between magnetic, electrical and magnetotransport properties is present in this compound. The magnetic structure in GdPd3 is highly fragile since applied magnetic fields of moderate strength significantly alter the spin arrangement within themore » system–a behavior that manifests itself in the oscillating MR. Intriguing magnetotransport characteristics of GdPd3 are appealing for field-sensitive device applications, especially if the MR oscillation could materialize at higher temperature by manipulating the magnetic interaction through perturbations caused by chemical substitutions.« less

  15. Displacement of squeezed propagating microwave states

    NASA Astrophysics Data System (ADS)

    Fedorov, Kirill G.; Zhong, Ling; Pogorzalek, Stefan; Eder, Peter; Fischer, Michael; Goetz, Jan; Wulschner, Friedrich; Xie, Edwar; Menzel, Edwin; Deppe, Frank; Marx, Achim; Gross, Rudolf

    Displacement of propagating squeezed states is a fundamental operation for quantum communications. It can be applied to fundamental studies of macroscopic quantum coherence and has an important role in quantum teleportation protocols with propagating microwaves. We generate propagating squeezed states using a Josephson parametric amplifier and implement displacement using a cryogenic directional coupler. We study single- and two-mode displacement regimes. For the single-mode displacement we find that the squeezing level of the displaced squeezed state does not depend on the displacement amplitude. Also, we observe that quantum entanglement between two spatially separated channels stays constant across 4 orders of displacement power. We acknowledge support by the German Research Foundation through SFB 631 and FE 1564/1-1, the EU project PROMISCE, and Elite Network of Bavaria through the program ExQM.

  16. Transport of runaway and thermal electrons due to magnetic microturbulence

    SciTech Connect

    Mynick, H.E.; Strachan, J.D.

    1981-04-01

    The ratio of the runaway electron confinement to thermal electron energy confinement is derived for tokamaks where both processes are determined by free streaming along stochastic magnetic field lines. The runaway electron confinement is enhanced at high runaway electron energies due to phase averaging over the magnetic perturbations when the runaway electron drift surfaces are displaced from the magnetic surfaces. Comparison with experimental data from LT-3, Ormak, PLT, ST, and TM-3 indicates that magnetic stochasticity may explain the relative transport rates of runaways and thermal electron energy.

  17. A theoretical model to predict both horizontal displacement and vertical displacement for electromagnetic induction-based deep displacement sensors.

    PubMed

    Shentu, Nanying; Zhang, Hongjian; Li, Qing; Zhou, Hongliang; Tong, Renyuan; Li, Xiong

    2012-01-01

    Deep displacement observation is one basic means of landslide dynamic study and early warning monitoring and a key part of engineering geological investigation. In our previous work, we proposed a novel electromagnetic induction-based deep displacement sensor (I-type) to predict deep horizontal displacement and a theoretical model called equation-based equivalent loop approach (EELA) to describe its sensing characters. However in many landslide and related geological engineering cases, both horizontal displacement and vertical displacement vary apparently and dynamically so both may require monitoring. In this study, a II-type deep displacement sensor is designed by revising our I-type sensor to simultaneously monitor the deep horizontal displacement and vertical displacement variations at different depths within a sliding mass. Meanwhile, a new theoretical modeling called the numerical integration-based equivalent loop approach (NIELA) has been proposed to quantitatively depict II-type sensors' mutual inductance properties with respect to predicted horizontal displacements and vertical displacements. After detailed examinations and comparative studies between measured mutual inductance voltage, NIELA-based mutual inductance and EELA-based mutual inductance, NIELA has verified to be an effective and quite accurate analytic model for characterization of II-type sensors. The NIELA model is widely applicable for II-type sensors' monitoring on all kinds of landslides and other related geohazards with satisfactory estimation accuracy and calculation efficiency.

  18. A Theoretical Model to Predict Both Horizontal Displacement and Vertical Displacement for Electromagnetic Induction-Based Deep Displacement Sensors

    PubMed Central

    Shentu, Nanying; Zhang, Hongjian; Li, Qing; Zhou, Hongliang; Tong, Renyuan; Li, Xiong

    2012-01-01

    Deep displacement observation is one basic means of landslide dynamic study and early warning monitoring and a key part of engineering geological investigation. In our previous work, we proposed a novel electromagnetic induction-based deep displacement sensor (I-type) to predict deep horizontal displacement and a theoretical model called equation-based equivalent loop approach (EELA) to describe its sensing characters. However in many landslide and related geological engineering cases, both horizontal displacement and vertical displacement vary apparently and dynamically so both may require monitoring. In this study, a II-type deep displacement sensor is designed by revising our I-type sensor to simultaneously monitor the deep horizontal displacement and vertical displacement variations at different depths within a sliding mass. Meanwhile, a new theoretical modeling called the numerical integration-based equivalent loop approach (NIELA) has been proposed to quantitatively depict II-type sensors’ mutual inductance properties with respect to predicted horizontal displacements and vertical displacements. After detailed examinations and comparative studies between measured mutual inductance voltage, NIELA-based mutual inductance and EELA-based mutual inductance, NIELA has verified to be an effective and quite accurate analytic model for characterization of II-type sensors. The NIELA model is widely applicable for II-type sensors’ monitoring on all kinds of landslides and other related geohazards with satisfactory estimation accuracy and calculation efficiency. PMID:22368467

  19. Constrained potential field modeling of the crustal architecture of the Musgrave Province in central Australia: Evidence for lithospheric strengthening due to crust-mantle boundary uplift

    NASA Astrophysics Data System (ADS)

    Aitken, Alan R. A.; Betts, Peter G.; Weinberg, Roberto F.; Gray, Daniel

    2009-12-01

    We image the crustal architecture of the Musgrave Province with petrophysically constrained forward models of new potential field data. These models image divergent shallow-dipping crustal scale thrusts that, at depth, link with an axial zone defined by steeper, lithospheric scale transpressional shear zones. They also show that to permit a near-surface density distribution that is consistent with petrophysical and geological observations, approximately 15-20 km of crust-mantle boundary uplift is necessary beneath the axial zone. The long-term preservation of this crust-mantle boundary offset implies a change from relatively weak lithosphere to relatively strong lithosphere during the intraplate Petermann Orogeny. To explain this, we propose a model in which uplift of the axial zone of the orogen leads to local lithospheric strengthening as a result of the uplift of mantle rocks into the lower crust, coupled with long-term lithospheric cooling due to the erosion of a radioactive upper crust. Brace-Goetze lithospheric strength models suggest that these processes may have increased the integrated strength of the lithosphere by a factor of 1.4-2.8. Because of this strengthening, this system is self-limiting, and activity will cease when lithospheric strength is sufficient to resist external forces and support isostatic imbalances. A simple force-balance model demonstrates that the force required to uplift the axial zone is tectonically reasonable and that the system can subsequently withstand significant tensional forces. This example shows that crust-mantle boundary uplift coupled with reduced crustal heat production can profoundly affect the long-term strength of the continental lithosphere and may be a critical process in the tectonic stabilization of intraplate regions.

  20. SU-F-BRB-14: Dosimetric Effects at Air- Tissue Boundary Due to Magnetic Field in MR-Guided IMRT/VMAT Delivery for Head and Neck Cancer

    SciTech Connect

    Prior, P; Chen, X; Schultz, C; Li, X

    2015-06-15

    Purpose: The advent of the MR-Linac enables real-time and high soft tissue contrast image guidance in radiation therapy (RT) delivery. Potential hot-spots at air-tissue interfaces, such as the sphenoid sinus, in RT for head and neck cancer (HNC), could potentially occur due to the electron return effect (ERE). In this study, we investigate the dosimetric effects of ERE on the dose distribution at air-tissues interfaces in HNC IMRT treatment planning. Methods: IMRT plans were generated based on planning CT’s acquired for HNC cases (nasopharynx, base of skull and paranasal sinus) using a research planning system (Monaco, v5.09.06, Elekta) employing Monte Carlo dose calculations with or without the presence of a transverse magnetic field (TMF). The dose in the air cavity was calculated in a 1 & 2 mm thick tissue layer, while the dose to the skin was calculated in a 1, 3 and 5 mm thick tissue layer. The maximum dose received in 1 cc volume, D1cc, were collected at different TMF strengths. Plan qualities generated with or without TMF or with increasing TMF were compared in terms of commonly-used dose-volume parameters (DVPs). Results: Variations in DVPs between plans with and without a TMF present were found to be within 5% of the planning CT. The presence of a TMF results in <5% changes in sinus air tissue interface. The largest skin dose differences with and without TMF were found within 1 mm of the skin surface Conclusion: The presence of a TMF results in practically insignificant changes in HNC IMRT plan quality, except for skin dose. Planning optimization with skin DV constraints could reduce the skin doses. This research was partially supported by Elekta Inc. (Crowley, U.K.)

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    ERIC Educational Resources Information Center

    Levitan, Sar A.; Mangum, Stephen L.

    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…

  3. An accurate elasto-plastic frictional tangential force displacement model for granular-flow simulations: Displacement-driven formulation

    NASA Astrophysics Data System (ADS)

    Zhang, Xiang; Vu-Quoc, Loc

    2007-07-01

    We present in this paper the displacement-driven version of a tangential force-displacement (TFD) model that accounts for both elastic and plastic deformations together with interfacial friction occurring in collisions of spherical particles. This elasto-plastic frictional TFD model, with its force-driven version presented in [L. Vu-Quoc, L. Lesburg, X. Zhang. An accurate tangential force-displacement model for granular-flow simulations: contacting spheres with plastic deformation, force-driven formulation, Journal of Computational Physics 196(1) (2004) 298-326], is consistent with the elasto-plastic frictional normal force-displacement (NFD) model presented in [L. Vu-Quoc, X. Zhang. An elasto-plastic contact force-displacement model in the normal direction: displacement-driven version, Proceedings of the Royal Society of London, Series A 455 (1991) 4013-4044]. Both the NFD model and the present TFD model are based on the concept of additive decomposition of the radius of contact area into an elastic part and a plastic part. The effect of permanent indentation after impact is represented by a correction to the radius of curvature. The effect of material softening due to plastic flow is represented by a correction to the elastic moduli. The proposed TFD model is accurate, and is validated against nonlinear finite element analyses involving plastic flows in both the loading and unloading conditions. The proposed consistent displacement-driven, elasto-plastic NFD and TFD models are designed for implementation in computer codes using the discrete-element method (DEM) for granular-flow simulations. The model is shown to be accurate and is validated against nonlinear elasto-plastic finite-element analysis.

  4. Signal processing for order 10 pm accuracy displacement metrology in real-world scientific applications

    NASA Technical Reports Server (NTRS)

    Halverson, Peter G.; Loya, Frank M.

    2004-01-01

    This paper describes heterodyne displacement metrology gauge signal processing methods that achieve satisfactory robustness against low signal strength and spurious signals, and good long-term stability. We have a proven displacement-measuring approach that is useful not only to space-optical projects at JPL, but also to the wider field of distance measurements.

  5. Polybenzimidazoles via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    Novel molecular weight controlled and endcapped polybenzimidazoles (PBI) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl benzimidazole) monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The PBI are endcapped with mono(hydroxyphenyl) benzimidazoles. The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. Mono(hydroxyphenyl) benzimidazoles are synthesizedby reacting phenyl-4-hydroxybenzoate with aromatic (o-diamine)s in diphenylsulfone. Molecular weight controlled and endcapped PBI of new chemical structures are prepared that exhibit a favorable combination of physical and mechanical properties.

  6. Polybenzimidazoles Via Aromatic Nucleophilic Displacement

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

    Novel molecular weight controlled and endcapped polybenzimidazoles (PBI) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenylbenzimidazole) monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The PBI are endcapped with mono(hydroxyphenyl)benzimidazoles. The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. Mono(hydroxyphenyl)benzimidazoles are synthesized by reacting phenyl-4-hydroxybenzoate with aromatic (o-diamine)s in diphenylsulfone. Molecular weight controlled and endcapped PBI of new chemical structures are prepared that exhibit a favorable combination of physical and mechanical properties.

  7. Variable delivery, fixed displacement pump

    SciTech Connect

    Sommars, Mark F.

    2001-01-01

    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.

  8. Limb displacement and brightness seismology

    NASA Astrophysics Data System (ADS)

    Emilio, Marcelo; Cunnyngham, Ian; Kuhn, Jeff; Mehret, Leandro; Bush, Rock; Scholl, Isabelle

    2015-08-01

    The Helioseismic and Magnetic Imager (HMI) abord the Solar Dynamics Observatory (SDO) has been used to obtain the most sensitive spectrally resolved observation of individual p-modes at the extreme solar limb. Such oscillation observations of the limb displacement and brightness for some spatial and temporal regimes are even competitive in signal-to-noise to full-disk doppler measurements of the p-mode spectrum. Limb measurements of 5-min p-modes, while having many similarities to full-disk doppler observations, have significantly different sensitivities to the solar rotation and the 5-min mode solar atmospheric structure. These may provide information about the solar structure which is complementary to full-disk measurements. In this work we present results from Individual spherical harmonic p-modes that were detected around solar limb with amplitudes at the micro-arcsecond level.

  9. Displaced electrode process for welding

    DOEpatents

    Heichel, L.J.

    1975-08-26

    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)

  10. Displaceable Gear Torque Controlled Driver

    NASA Technical Reports Server (NTRS)

    Cook, Joseph S., Jr. (Inventor)

    1997-01-01

    Methods and apparatus are provided for a torque driver including a displaceable gear to limit torque transfer to a fastener at a precisely controlled torque limit. A biasing assembly biases a first gear into engagement with a second gear for torque transfer between the first and second gear. The biasing assembly includes a pressurized cylinder controlled at a constant pressure that corresponds to a torque limit. A calibrated gage and valve is used to set the desired torque limit. One or more coiled output linkages connect the first gear with the fastener adaptor which may be a socket for a nut. A gear tooth profile provides a separation force that overcomes the bias to limit torque at the desired torque limit. Multiple fasteners may be rotated simultaneously to a desired torque limit if additional output spur gears are provided. The torque limit is adjustable and may be different for fasteners within the same fastener configuration.

  11. DISPLACEMENT BASED SEISMIC DESIGN CRITERIA

    SciTech Connect

    HOFMAYER,C.H.

    1999-03-29

    The USNRC has initiated a project to determine if any of the likely revisions to traditional earthquake engineering practice are relevant to seismic design of the specialized structures, systems and components of nuclear power plants and of such significance to suggest that a change in design practice might be warranted. As part of the initial phase of this study, a literature survey was conducted on the recent changes in seismic design codes/standards, on-going activities of code-writing organizations/communities, and published documents on displacement-based design methods. This paper provides a summary of recent changes in building codes and on-going activities for future codes. It also discusses some technical issues for further consideration.

  12. Fiber optic multimode displacement sensor

    NASA Astrophysics Data System (ADS)

    Fisher, Karl A.; Jarzynski, Jacek

    1996-04-01

    An underwater Optical Motion Sensor (OMS) based on a design first presented by W. B. Spillman, Schlieren multimode fiber-optic hydrophone, Applied Physics Letters 37(2), 15 July 1980, p. 145-146 is described. The displacement sensor uses the same acoustooptical intensity modulation mechanism as Spillman, however the sensing mechanism is isolated from the ambient fluid environment by a small cylindrical aluminum enclosure (1″ OD×3/4″). The enclosure contains an inertial mass and the fiber collimators. The inertial mass is suspended in the center of the enclosure by three small wires rigidly mounted to the walls. The mass and wires act as a cantilever beam system with a mechanical resonance near 100 Hz. The transduction mechanism consists of two opposed optical gratings aligned and positioned between the fiber collimators. One grating is mounted on the inertial mass while the other is mounted on the lower end cap of the enclosure. Relative motion between the gratings causes a modulation of the light transmitted through the gratings. The modulated beam is focused onto a photodetector and converted to electric current. The frequency response is flat from 200 Hz-9 kHz with a minimum detectable displacement of 0.002 A and the dynamic range is 136 dB. The small size and light weight give the sensor an effective density of 1.08 g/cm3 making it almost neutrally buoyant in water. This in conjunction with the performance characteristics make this sensor suitable for use in acoustical sensing applications.

  13. Derivation of the Biot-Savart Law from Ampere's Law Using the Displacement Current

    NASA Astrophysics Data System (ADS)

    Buschauer, Robert

    2013-12-01

    The equation describing the magnetic field due to a single, nonrelativistic charged particle moving at constant velocity is often referred to as the "Biot-Savart law for a point charge." Introductory calculus-based physics books usually state this law without proof.2 Advanced texts often present it either without proof or as a special case of a complicated mathematical formalism.3 Either way, little or no physical insight is provided to the student regarding the underlying physics. This paper presents a novel, basic, and transparent derivation of the Biot-Savart law for a point charge based only on Maxwell's displacement current term in Ampere's law. This derivation can serve many pedagogical purposes. For example, it can be used as lecture material at any academic level to obtain the Biot-Savart law for a point charge from simple principles. It can also serve as a practical example of the important fact that a changing electric flux produces a magnetic field.

  14. Detection of quasi-static displacement components of LP seismic sources near the volcanic summit

    NASA Astrophysics Data System (ADS)

    Thun, Johannes; Bean, Christopher J.; Lokmer, Ivan

    2014-05-01

    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

  15. FDTD analysis of human body-core temperature elevation due to RF far-field energy prescribed in the ICNIRP guidelines.

    PubMed

    Hirata, Akimasa; Asano, Takayuki; Fujiwara, Osamu

    2007-08-21

    This study investigated the relationship between the specific absorption rate and temperature elevation in an anatomically-based model named NORMAN for exposure to radio-frequency far fields in the ICNIRP guidelines (1998 Health Phys. 74 494-522). The finite-difference time-domain method is used for analyzing the electromagnetic absorption and temperature elevation in NORMAN. In order to consider the variability of human thermoregulation, parameters for sweating are derived and incorporated into a conventional sweating formula. First, we investigated the effect of blood temperature variation modeling on body-core temperature. The computational results show that the modeling of blood temperature variation was the dominant factor influencing the body-core temperature. This is because the temperature in the inner tissues is elevated via the circulation of blood whose temperature was elevated due to EM absorption. Even at different frequencies, the body-core temperature elevation at an identical whole-body average specific absorption rate (SAR) was almost the same, suggesting the effectiveness of the whole-body average SAR as a measure in the ICNIRP guidelines. Next, we discussed the effect of sweating on the temperature elevation and thermal time constant of blood. The variability of temperature elevation caused by the sweating rate was found to be 30%. The blood temperature elevation at the basic restriction in the ICNIRP guidelines of 0.4 W kg(-1) is 0.25 degrees C even for a low sweating rate. The thermal time constant of blood temperature elevation was 23 min and 52 min for a man with a lower and a higher sweating rate, respectively, which is longer than the average time of the SAR in the ICNIRP guidelines. Thus, the whole-body average SAR required for blood temperature elevation of 1 degrees C was 4.5 W kg(-1) in the model of a human with the lower sweating coefficients for 60 min exposure. From a comparison of this value with the basic restriction in the ICNIRP

  16. Nonaffine displacements in crystalline solids in the harmonic limit.

    PubMed

    Ganguly, Saswati; Sengupta, Surajit; Sollich, Peter; Rao, Madan

    2013-04-01

    A systematic coarse graining of microscopic atomic displacements generates a local elastic deformation tensor D as well as a positive definite scalar χ measuring nonaffinity, i.e., the extent to which the displacements are not representable as affine deformations of a reference crystal. We perform an exact calculation of the statistics of χ and D and their spatial correlations for solids at low temperatures, within a harmonic approximation and in one and two dimensions. We obtain the joint distribution P(χ,D) and the two-point spatial correlation functions for χ and D. We show that nonaffine and affine deformations are coupled even in a harmonic solid, with a strength that depends on the size of the coarse-graining volume Ω and dimensionality. As a corollary to our work, we identify the field h(χ) conjugate to χ and show that this field may be tuned to produce a transition to a state where the ensemble average <χ> and the correlation length of χ diverge. Our work should be useful as a template for understanding nonaffine displacements in realistic systems with or without disorder and as a means for developing computational tools for studying the effects of nonaffine displacements in melting, plastic flow, and the glass transition.

  17. Quantum Phonon Optics: Squeezing Quantum Noise in the Atomic Displacements.

    NASA Astrophysics Data System (ADS)

    Hu, X.; Nori, F.

    1996-03-01

    We have investigated(X. Hu and F. Nori, Physical Review B, in press; preprints.) coherent and squeezed quantum states of phonons. Squeezed states are interesting because they allow the possibility of modulating the quantum fluctuations of atomic displacements below the zero-point quantum noise level of phonon vacuum states. We have studiedfootnotemark[1] the possibility of squeezing quantum noise in the atomic displacement using a polariton-based approach and also a method based on the three-phonon anharmonic interaction. Our focus here is on the first approach. We have diagonalized the polariton Hamiltonian and calculated the corresponding expectation values and fluctuations of both the atomic displacement and the lattice amplitude operators (the later is the phonon analog of the electric field operator for photons). Our results shows that squeezing of quantum fluctuations in the atomic displacements can be achieved with appropriate initial states of both photon and phonon fields. The degree of squeezing is directly related to the crystal susceptibility, which is indicative of the interaction strength between the incident light and the crystal.

  18. Modelling Toehold-Mediated RNA Strand Displacement

    PubMed Central

    Šulc, Petr; Ouldridge, Thomas E.; Romano, Flavio; Doye, Jonathan P.K.; Louis, Ard A.

    2015-01-01

    We study the thermodynamics and kinetics of an RNA toehold-mediated strand displacement reaction with a recently developed coarse-grained model of RNA. Strand displacement, during which a single strand displaces a different strand previously bound to a complementary substrate strand, is an essential mechanism in active nucleic acid nanotechnology and has also been hypothesized to occur in vivo. We study the rate of displacement reactions as a function of the length of the toehold and temperature and make two experimentally testable predictions: that the displacement is faster if the toehold is placed at the 5′ end of the substrate; and that the displacement slows down with increasing temperature for longer toeholds. PMID:25762335

  19. Modelling toehold-mediated RNA strand displacement.

    PubMed

    Šulc, Petr; Ouldridge, Thomas E; Romano, Flavio; Doye, Jonathan P K; Louis, Ard A

    2015-03-10

    We study the thermodynamics and kinetics of an RNA toehold-mediated strand displacement reaction with a recently developed coarse-grained model of RNA. Strand displacement, during which a single strand displaces a different strand previously bound to a complementary substrate strand, is an essential mechanism in active nucleic acid nanotechnology and has also been hypothesized to occur in vivo. We study the rate of displacement reactions as a function of the length of the toehold and temperature and make two experimentally testable predictions: that the displacement is faster if the toehold is placed at the 5' end of the substrate; and that the displacement slows down with increasing temperature for longer toeholds.

  20. Precise displacement measurement for a local surface.

    PubMed

    Yeh, Sheng Lih; Lin, Shyh Tsong; Chang, Yu Hsin

    2009-11-01

    An optical measurement method to get the in-plane and out-of-plane displacements of a local surface using a laser is proposed. The proposed method simultaneously derives the in-plane and out-of-plane displacements by measuring the shift of interference fringes formed by scattered beams. The average errors of the in-plane and out-of-plane displacement measurements are significantly smaller than 10 nm. Moreover, the proposed method uses only low-cost optical elements.

  1. Displacement speeds in turbulent premixed flame simulations

    SciTech Connect

    Day, Marcus S.; Shepherd, Ian G.; Bell, J.; Grcar, Joseph F.; Lijewski, Michael J.

    2007-07-01

    The theory of turbulent premixed flames is based on acharacterization of the flame as a discontinuous surface propagatingthrough the fluid. The displacement speed, defined as the local speed ofthe flame front normal to itself, relative to the unburned fluid,provides one characterization of the burning velocity. In this paper, weintroduce a geometric approach to computing displacement speed anddiscuss the efficacy of the displacement speed for characterizing aturbulent flame.

  2. Disturbance to the population due to flight operations at landing fields. Questionnaire on community reaction to non-commercial and sporting aviation

    NASA Technical Reports Server (NTRS)

    Rohrmann, B.

    1981-01-01

    A field study was undertaken to determine the Sociopsychological effects of air traffic noise experienced by residents of areas near small sporting aviation fields. A questionaire was prepared which includes questions on flight restriction measures, on attitudes which moderate annoyance and on comparisons with other noise sources, etc.

  3. Experimental investigation on the effect of surface electric field in the growth of tungsten nano-tendril morphology due to low energy helium irradiation

    NASA Astrophysics Data System (ADS)

    Woller, K. B.; Whyte, D. G.; Wright, G. M.; Brunner, D.

    2016-12-01

    The mechanisms responsible for and controlling the growth of tungsten nano-tendrils (or "fuzz") under low-energy helium plasma exposure remain unclear. For the first time in nano-tendril experiments, the plasma sheath-produced electric field and the helium (He) ion energy have been decoupled, showing that the sheath electric field has little impact on nano-tendril growth, eliminating a possible cause for tendril growth. The well-established necessary growth conditions for W fuzz were maintained with He ion flux density ΓHe > 1021 He m-2 s-1, surface temperature Ts = 1273 K, He ion energy EHe = 64 eV, and He ion fluence ΦHe > 1024 He m-2. A grid is situated between the tungsten sample and plasma, with the grid and sample potentials independently controlled in order to control the electric field at the surface of the sample while maintaining the same incident He ion energy to the surface. A calculation of the potential profile in the drift space between the grid and sample was used to account for space charge and calculate the electric field at the surface of the sample. Tungsten fuzz formed at all electric fields tested, even near zero electric field. Also, the depth of the resulting W fuzz layer was unaltered by the electric field when compared to the calculated depth determined from an empirical growth model. The conclusion is that the sheath electric field is not necessary to cause the changes in surface morphology.

  4. Cervicitis associated with lateral cervical displacement.

    PubMed

    Gjoni, Indira; Muneyyirci-Delale, Ozgul

    2012-01-01

    Lateral cervical displacement has been recognized as a sign of endometriosis; however, other causes of the finding have not been explored. In our experience, patients without endometriosis are presenting with lateral cervical displacement, mainly towards the left of midline. The common finding in these cases is the presence of cervicitis leading us to hypothesize the role of cervicitis in causing lateral displacement of the cervix. Future research into this area will provide us with a stronger understanding of the role that lateral cervical displacement plays in the development of pelvic pathology and the development of cervical cancer.

  5. Displacement of Propagating Squeezed Microwave States

    NASA Astrophysics Data System (ADS)

    Fedorov, Kirill G.; Zhong, L.; Pogorzalek, S.; Eder, P.; Fischer, M.; Goetz, J.; Xie, E.; Wulschner, F.; Inomata, K.; Yamamoto, T.; Nakamura, Y.; Di Candia, R.; Las Heras, U.; Sanz, M.; Solano, E.; Menzel, E. P.; Deppe, F.; Marx, A.; Gross, R.

    2016-07-01

    Displacement of propagating quantum states of light is a fundamental operation for quantum communication. It enables fundamental studies on macroscopic quantum coherence and plays an important role in quantum teleportation protocols with continuous variables. In our experiments, we have successfully implemented this operation for propagating squeezed microwave states. We demonstrate that, even for strong displacement amplitudes, there is no degradation of the squeezing level in the reconstructed quantum states. Furthermore, we confirm that path entanglement generated by using displaced squeezed states remains constant over a wide range of the displacement power.

  6. Internal displacement and health among the Palestinian minority in Israel.

    PubMed

    Daoud, Nihaya; Shankardass, Ketan; O'Campo, Patricia; Anderson, Kim; Agbaria, Ayman K

    2012-04-01

    Long term health impacts of internal displacement (ID) resulting from political violence are not well documented or understood. One such case is the ID of 300,000-420,000 Palestinian citizens of Israel and their descendants during the Nakba of 1948 (Palestinian Catastrophe). We aim to document the long term health impacts of this ID. We draw on data collected in 2005 from a nationwide random sample of 902 individuals aged 30-70. Research participants were interviewed in person after being selected through a multistage sampling procedure. About 24% of participants reported that either they or their families had been internally displaced. Palestinian internally displaced persons (IDPs), that is, those who were forcibly displaced and dispossessed from their homes and lands during the Nakba and its aftermath, as well as their families and descendants, and who reside within the current borders of Israel, had an odds ratio of 1.45 (95% CI = 1.02-2.07) for poor self-rated health (SRH) compared to non-IDPs after controlling for demographic, socioeconomic and psychosocial factors. No difference was found between IDPs and non-IDPs in limiting longstanding illness following control for confounders. Low socioeconomic position and chronic stress were significantly related to ID and to SRH. Our findings suggest adverse long term health impacts of the Nakba on the IDPs when compared to non-IDPs. We propose that these disparities might stem from IDPs' unhealed post-traumatic scars from the Nakba, or from becoming a marginalized minority within their own society due to their displacement and loss of collective identity. Given these long term health consequences, we conclude that displacement should be addressed with health and social policies for IDPs.

  7. Influence of lateral displacement on the levitation performance of a magnetized bulk high-Tc superconductor magnet

    NASA Astrophysics Data System (ADS)

    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

    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.

  8. Radiofrequency heating and magnetically induced displacement of dental magnetic attachments during 3.0 T MRI

    PubMed Central

    Miyata, K; Hasegawa, M; Abe, Y; Tabuchi, T; Namiki, T; Ishigami, T

    2012-01-01

    Objective The aim of this study was to estimate the risk of injury from dental magnetic attachments due to their radiofrequency (RF) heating and magnetically induced displacement during 3.0 T MRI. Methods To examine the magnetic attachments, we adopted the American Society for Testing and Materials F2182-02a and F2052-06 standards in two MRI systems (Achieva 3.0 T Nova Dual; Philips, Tokyo, Japan, and Signa HDxt 3.0 T; GE Healthcare, Milwaukee, WI). The temperature change was measured in a cylindrical keeper (GIGAUSS D600; GC, Tokyo, Japan) with coping of the casting alloy and a keeper with a dental implant at the maximum specific absorption rate (SAR) for 20 min. To measure the magnetically induced displacement force, three sizes of keepers (GIGAUSS D400, D600 and D1000) were used in deflection angle tests conducted at the point of the maximum magnetic field strength. Results Temperature elevations of both coping and implant were higher in the Signa system than in the Achieva system. The highest temperature changes in the keeper with implant and keeper with coping were 0.6 °C and 0.8 °C in the Signa system, respectively. The temperature increase did not exceed 1.0 °C at any location. The deflection angle (α) was not measurable because it exceeded 90°. GIGAUSS D400 required an extra 3.0 g load to constrain the deflection angle to less than 45°; GIGAUSS D600 and D1000 required 5.0 and 9.0 g loads, respectively. Conclusions Dental magnetic attachments pose no risk due to RF heating and magnetically induced displacement at 3.0 T MRI. However, it is necessary to confirm that these keepers are securely attached to the prosthesis before imaging. PMID:22499128

  9. High speed displacement analysis using digital speckle correlation

    NASA Astrophysics Data System (ADS)

    Siebert, T.; Splitthof, K.; Becker, T.; Krupka, R.

    2006-06-01

    Digital speckle correlation techniques have already been successfully proven for accurate displacement analysis. With the use of two cameras, three dimensional measurements of contours and displacements can be carried out. The principle of this technique is pretty easy to understood and realized, opening a nearly unlimited range of applications. Rapid new developments in the field of digital imaging and computer technology, especially for very much dynamic applications, opens further applications for these measurement method up to high speed deformation and strain analysis, e.g. in the fields of, material testing, fracture mechanics, high speed testing, advanced materials and component testing. The dynamic range is combined with the capability to measure very large strains (up to more than 100%). The resolution of the deformation in space and time opens a wide range of applications for vibration analysis of objects. Since the system determines the absolute position and displacements of the object in space it is capable of measuring high amplitudes and even objects with rigid body movements, which is a big advantage against full field ESPI systems. The absolute resolution depends on the field of view and is scalable. Calibration of the optical setup is a crucial point which will be discussed in detail. Examples of the analysis of high speed harmonic vibration and transient events out of material research and industrial applications are presented. Results of measurement performed on a vibrating membrane and a tensile test sample are show typical features of the system.

  10. Testing fault displacement-length scaling relations through analogue modeling in an extensional setting

    NASA Astrophysics Data System (ADS)

    Bonini, L.; Basili, R.; Burrato, P.; Kastelic, V.; Toscani, G.; Seno, S.; Valensise, G.

    2013-12-01

    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

  11. Comparison of second cancer risk due to out-of-field doses from 6-MV IMRT and proton therapy based on 6 pediatric patient treatment plans

    PubMed Central

    Athar, Basit S.; Paganetti, Harald

    2010-01-01

    Background and Purpose This study compared 6-MV IMRT and proton therapy in terms of organ specific second cancer lifetime attributable risks (LARs) caused by scattered and secondary out-of-field radiation. Material and Methods Based on simulated organ doses, excess relative and excess absolute risk models were applied to assess organ-specific LARs. Two treatment sites (cranium and central spine) were considered involving 6 treatment volumes and 6 patient ages (9-month, 4-year, 8-year, 11-year, 14-year, and adult). Results The LARs for thyroid cancer from a 6 cm diameter field treating a brain lesion in a 4-year old patient were estimated to be 1.1% and 0.3% in passive proton therapy and IMRT, respectively. However, estimated LARs for bladder cancer, more than 25 cm from the field edge for the same patient and treatment field, were estimated to be 0.2% and 0.02% from IMRT and proton therapy, respectively. Risks for proton beam scanning was found to be an order of magnitude smaller compared to passive proton therapy. Conclusion In terms of out-of-field risks, IMRT offers advantage close to the primary field and an increasing advantage for passive proton therapy is noticed with increasing distance to the field. Scanning proton beam therapy shows the lowest risks. PMID:21159398

  12. Polybenzoxazole via aromatic nucleophilic displacement

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    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.

  13. [Dynamics of biomacromolecules in coherent electromagnetic radiation field].

    PubMed

    Leshcheniuk, N S; Apanasevich, E E; Tereshenkov, V I

    2014-01-01

    It is shown that induced oscillations and periodic displacements of the equilibrium positions occur in biomacromolecules in the absence of electromagnetic radiation absorption, due to modulation of interaction potential between atoms and groups of atoms forming the non-valence bonds in macromolecules by the external electromagnetic field. Such "hyperoscillation" state causes inevitably the changes in biochemical properties of macromolecules and conformational transformation times.

  14. Formation of the residual stress field under local thermal actions

    NASA Astrophysics Data System (ADS)

    Burenin, A. A.; Dats, E. P.; Murashkin, E. V.

    2014-03-01

    The one-dimensional process of material deformation due to local heating and subsequent cooling is analyzed in the framework of the classical theory of elastoplastic deformations. The problem of formation of residual stresses in a thin plate made of an elastoplastic material under a given thermal action is solved. The graphs of fields of residual stresses and displacements are constructed.

  15. Effects of Fault Displacement on Emplacement Drifts

    SciTech Connect

    F. Duan

    2000-04-25

    The purpose of this analysis is to evaluate potential effects of fault displacement on emplacement drifts, including drip shields and waste packages emplaced in emplacement drifts. The output from this analysis not only provides data for the evaluation of long-term drift stability but also supports the Engineered Barrier System (EBS) process model report (PMR) and Disruptive Events Report currently under development. The primary scope of this analysis includes (1) examining fault displacement effects in terms of induced stresses and displacements in the rock mass surrounding an emplacement drift and (2 ) predicting fault displacement effects on the drip shield and waste package. The magnitude of the fault displacement analyzed in this analysis bounds the mean fault displacement corresponding to an annual frequency of exceedance of 10{sup -5} adopted for the preclosure period of the repository and also supports the postclosure performance assessment. This analysis is performed following the development plan prepared for analyzing effects of fault displacement on emplacement drifts (CRWMS M&O 2000). The analysis will begin with the identification and preparation of requirements, criteria, and inputs. A literature survey on accommodating fault displacements encountered in underground structures such as buried oil and gas pipelines will be conducted. For a given fault displacement, the least favorable scenario in term of the spatial relation of a fault to an emplacement drift is chosen, and the analysis is then performed analytically. Based on the analysis results, conclusions are made regarding the effects and consequences of fault displacement on emplacement drifts. Specifically, the analysis will discuss loads which can be induced by fault displacement on emplacement drifts, drip shield and/or waste packages during the time period of postclosure.

  16. Three-dimensional particle-in-cell simulations of rapid start-up in strapped oven magnetrons due to variation in the insulating magnetic field

    NASA Astrophysics Data System (ADS)

    Luginsland, J. W.; Lau, Y. Y.; Neculaes, V. B.; Gilgenbach, R. M.; Jones, M. C.; Frese, M. H.; Watrous, J. J.

    2004-06-01

    A three-dimensional parallel particle-in-cell code, ICEPIC, is used to simulate the geometry and the magnetic field profiles of the recent low-noise, fast startup magnetron experiments at the University of Michigan. The fast startup, the power levels, and the starting currents that have been observed in these experiments are quantitatively reproduced in the simulations. The tendency for low noise operation has also been reproduced with the use of an azimuthally varying magnetic field.

  17. Resistance to the Bacillus thuringiensis bioinsecticide in a field population of Plutella xylostella is due to a change in a midgut membrane receptor.

    PubMed

    Ferré, J; Real, M D; Van Rie, J; Jansens, S; Peferoen, M

    1991-06-15

    The biochemical mechanism for resistance to Bacillus thuringiensis crystal proteins was studied in a field population of diamondback moths (Plutella xylostella) with a reduced susceptibility to the bioinsecticidal spray. The toxicity and binding characteristics of three crystal proteins [CryIA(b), CryIB, and CryIC] were compared between the field population and a laboratory strain. The field population proved resistant (greater than 200-fold compared with the laboratory strain) to CryIA(b), one of the crystal proteins in the insecticidal formulation. Binding studies showed that the two strains differ in a membrane receptor that recognizes CryIA(b). This crystal protein did not bind to the brush-border membrane of the midgut epithelial cells of the field population, either because of strongly reduced binding affinity or because of the complete absence of the receptor molecule. Both strains proved fully susceptible to the CryIB and CryIC crystal proteins, which were not present in the B. thuringiensis formulation used in the field. Characteristics of CryIB and CryIC binding to brush-border membranes of midgut epithelial cells were virtually identical in the laboratory and the field population.

  18. Radiation damage due to electromagnetic showers

    SciTech Connect

    Rakhno, Igor; Mokhov, Nikolai; Striganov, Sergei; /Fermilab

    2008-05-01

    Radiation-induced damage due to atomic displacements is essential to correctly predict the behavior of materials in nuclear reactors and at charged-particle accelerators. Traditionally the damage due to hadrons was of major interest. The recent increased interest in high-energy lepton colliders gave rise to the problem of prediction of radiation damage due to electromagnetic showers in a wide energy range--from a few hundred keV and up to a few hundred GeV. The report describes results of an electron- and positron-induced displacement cross section evaluation. It is based on detailed lepton-nucleus cross sections, realistic nuclear form-factors and a modified Kinchin-Pease damage model. Numerical data on displacement cross sections for various target nuclei is presented.

  19. Drift due to viscous vortex rings

    NASA Astrophysics Data System (ADS)

    Morrell, Thomas; Spagnolie, Saverio; Thiffeault, Jean-Luc

    2016-11-01

    Biomixing is the study of fluid mixing due to swimming organisms. While large organisms typically produce turbulent flows in their wake, small organisms produce less turbulent wakes; the main mechanism of mixing is the induced net particle displacement (drift). Several experiments have examined this drift for small jellyfish, which produce vortex rings that trap and transport a fair amount of fluid. Inviscid theory implies infinite particle displacements for the trapped fluid, so the effect of viscosity must be included to understand the damping of real vortex motion. We use a model viscous vortex ring to compute particle displacements and other relevant quantities, such as the integrated moments of the displacement. Fluid entrainment at the tail end of a growing vortex 'envelope' is found to play an important role in the total fluid transport and drift. Partially supported by NSF Grant DMS-1109315.

  20. Fiber-optic displacement sensors on the Hunters Trophy UGT impulse gauge experiments

    SciTech Connect

    Green, R.E.L.; Poutiatine, A.I.

    1995-03-01

    As part of a program to develop gauges for measurement of various mechanical properties in hostile environments, the authors fielded purely optical displacement sensors at the ends of long fiber-optic cables as supplements to the regular displacement sensors of four impulse gauges fielded as part of a materials study on the Hunters Trophy underground effects test at the Nevada Test Site. These fiber-optic sensor systems and their performance on the Hunters Trophy test are described in this report.

  1. Stress intensity and crack displacement for small edge cracks

    NASA Technical Reports Server (NTRS)

    Orange, Thomas W.

    1988-01-01

    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.

  2. Does migratory distance affect fuelling in a medium-distance passerine migrant?: results from direct and step-wise simulated magnetic displacements

    PubMed Central

    Ilieva, Mihaela; Bianco, Giuseppe; Åkesson, Susanne

    2016-01-01

    ABSTRACT In birds, fat accumulation before and during migration has been shown to be endogenously controlled and tuned by, among other factors, the Earth's magnetic field. However, our knowledge about the influence of the geomagnetic field on the fuelling in migrating birds is still limited to just a few nocturnally migrating passerine species. In order to study if variations of the magnetic field can also influence the fuelling of both day- and night-migrating passerines, we caught first-year dunnocks (Prunella modularis) and subjected them to three magnetic field conditions simulated by a system of magnetic coils: (1) local geomagnetic field of southern Sweden, (2) magnetic field corresponding to the centre of the expected wintering area, and (3) magnetic field met at the northern limit of the species' breeding distribution. We did not find a difference in mass increase between the birds kept in a local magnetic field and a field resembling their wintering area, irrespectively of the mode of magnetic displacement, i.e. direct or step-wise. However, the dunnocks magnetically displaced north showed a lower rate of fuelling in comparison to the control group, probably due to elevated activity. Compared with previous studies, our results suggest that the fuelling response to magnetic displacements during the migration period is specific to the eco-physiological situation. Future studies need to address if there is an effect of magnetic field manipulation on the level of migratory activity in dunnocks and how widespread the influence of local geomagnetic field parameters is on fuelling decisions in different bird species, which have different migratory strategies, distances and migration history. PMID:26883627

  3. 40 CFR 205.153 - Engine displacement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Engine displacement. 205.153 Section 205.153 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycles § 205.153 Engine displacement. (a)...

  4. 40 CFR 205.153 - Engine displacement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Engine displacement. 205.153 Section 205.153 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycles § 205.153 Engine displacement. (a)...

  5. 40 CFR 205.153 - Engine displacement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Engine displacement. 205.153 Section 205.153 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) NOISE ABATEMENT PROGRAMS TRANSPORTATION EQUIPMENT NOISE EMISSION CONTROLS Motorcycles § 205.153 Engine displacement. (a)...

  6. Worker Displacement in a Strong Labor Market.

    ERIC Educational Resources Information Center

    Helwig, Ryan T.

    2001-01-01

    As economic growth continued in 1997 and 1998, job losses declined and the displacement rate was the lowest of the 1990s. Many displaced workers were able to find new jobs with little or no change in weekly earnings. (Author/JOW)

  7. Video Games, Adolescents, and the Displacement Effect

    ERIC Educational Resources Information Center

    Fisher, Carla Christine

    2012-01-01

    The displacement effect (the idea that time spent in one activity displaces time spent in other activities) was examined within the lens of adolescents' video game use and their time spent reading, doing homework, in physically active sports and activities, in creative play, and with parents and friends. Data were drawn from the Panel Study…

  8. Displaced Homemakers: Vo-Tech Workshop Guide.

    ERIC Educational Resources Information Center

    Peltier, Wanda Jo

    Written for displaced homemaker programs in vocational-technical schools, this curriculum contains material designed so that instructors can prepare student manuals appropriate to almost any educational support situation for displaced homemakers. An overview provides information on special needs groups, curriculum use, and resources and sample…

  9. O the Spatial Structure of the Acoustic Signal Field Near the Deep Ocean Bottom due to a Near-Surface CW Source.

    NASA Astrophysics Data System (ADS)

    Grant, David Edward

    The spatial structure of the acoustic signal field near the ocean bottom was investigated experimentally. A source near the ocean surface projected a cw tone as it moved along a radial path from a range of 40 km to within 2 km of a near-bottom vertical array of receiving hydrophones in a 2643 m deep ocean. The signal level at each hydrophone and the signal phase difference between consecutive pairs of phones were measured as a function of source-receiver range. A technique for modelling the signal field spatial structure was developed that demonstrated those physical mechanisms that influence the signal field. It was found that, for short ranges, signal phase difference was dominated by a few eigenrays and that coherent interference among these rays was an important factor in describing certain aspects of the signal field. An application to receiving array beamforming was made in which it was shown that inhomogeneities in the spatial structure of the signal field led to degradation of array signal gain when standard delay-and-sum beamforming was done.

  10. Internal displacement in Colombia: Fifteen distinguishing features.

    PubMed

    Shultz, James M; Ceballos, Ángela Milena Gómez; Espinel, Zelde; Oliveros, Sofia Rios; Fonseca, Maria Fernanda; Florez, Luis Jorge Hernandez

    2014-01-01

    This commentary aims to delineate the distinguishing features of conflict-induced internal displacement in the nation of Colombia, South America. Even as Colombia is currently implementing a spectrum of legal, social, economic, and health programs for "victims of armed conflict," with particular focus on internally displaced persons (IDPs), the dynamics of forced migration on a mass scale within this country are little known beyond national borders.   The authors of this commentary are embarking on a global mental health research program in Bogota, Colombia to define best practices for reaching the displaced population and implementing sustainable, evidence-based screening and intervention for common mental disorders. Presenting the defining characteristics of internal displacement in Colombia provides the context for our work and, more importantly, conveys the compelling and complex nature of this humanitarian crisis. We attempt to demonstrate Colombia's unique position within the global patterning of internal displacement.

  11. Sentinel-1 TOPS interferometry for along-track displacement measurement

    NASA Astrophysics Data System (ADS)

    Jiang, H. J.; Pei, Y. Y.; Li, J.

    2017-02-01

    The European Space Agency’s Sentinel-1 mission, a constellation of two C-band synthetic aperture radar (SAR) satellites, utilizes terrain observation by progressive scan (TOPS) antenna beam steering as its default operation mode to achieve wide-swath coverage and short revisit time. The beam steering during the TOPS acquisition provides a means to measure azimuth motion by using the phase difference between forward and backward looking interferograms within regions of burst overlap. Hence, there are two spectral diversity techniques for along-track displacement measurement, including multi-aperture interferometry (MAI) and “burst overlap interferometry”. This paper analyses the measurement accuracies of MAI and burst overlap interferometry. Due to large spectral separation in the overlap region, burst overlap interferometry is a more sensitive measurement. We present a TOPS interferometry approach for along-track displacement measurement. The phase bias caused by azimuth miscoregistration is first estimated by burst overlap interferometry over stationary regions. After correcting the coregistration error, the MAI phase and the interferometric phase difference between burst overlaps are recalculated to obtain along-track displacements. We test the approach with Sentinel-1 TOPS interferometric data over the 2015 Mw 7.8 Nepal earthquake fault. The results prove the feasibility of our approach and show the potential of joint estimation of along-track displacement with burst overlap interferometry and MAI.

  12. Multi-interferometric displacement measurement system with variable measurement mirrors.

    PubMed

    Chang, Chung-Ping; Tung, Pi-Cheng; Shyu, Lih-Horng; Wang, Yung-Cheng; Manske, Eberhard

    2013-06-10

    Laser interferometers have been widely implemented for the displacement sensing and positioning calibration of the precision mechanical industry, due to their excellent measuring features and direct traceability to the dimensional definition. Currently some kinds of modified Fabry-Perot interferometers with a planar mirror or a corner cube prism as the measurement mirror have been proposed. Each optical structure of both models has the individual particularity and performance for measuring applications. In this investigation, a multi-interferometric displacement system has been proposed whose measurement mirror can be quickly and conveniently altered with a planar mirror or a corner cube reflector depending on the measuring demand. Some experimental results and analyses about the interpolation error and displacement measurements with both reflectors have been demonstrated. According to the results, suggestions about the choice of a measuring reflector and interpolation model have been presented. With the measuring verifications, the developed system with a maximum standard deviation less than 0.2081 μm in measuring range of 300 mm would be a compact and robust tool for sensing or calibrating the linear displacement of mechanical equipment.

  13. A thermal modelling of displacement cascades in uranium dioxide

    NASA Astrophysics Data System (ADS)

    Martin, G.; Garcia, P.; Sabathier, C.; Devynck, F.; Krack, M.; Maillard, S.

    2014-05-01

    The space and time dependent temperature distribution was studied in uranium dioxide during displacement cascades simulated by classical molecular dynamics (MD). The energy for each simulated radiation event ranged between 0.2 keV and 20 keV in cells at initial temperatures of 700 K or 1400 K. Spheres into which atomic velocities were rescaled (thermal spikes) have also been simulated by MD to simulate the thermal excitation induced by displacement cascades. Equipartition of energy was shown to occur in displacement cascades, half of the kinetic energy of the primary knock-on atom being converted after a few tenths of picoseconds into potential energy. The kinetic and potential parts of the system energy are however subjected to little variations during dedicated thermal spike simulations. This is probably due to the velocity rescaling process, which impacts a large number of atoms in this case and would drive the system away from a dynamical equilibrium. This result makes questionable MD simulations of thermal spikes carried out up to now (early 2014). The thermal history of cascades was compared to the heat equation solution of a punctual thermal excitation in UO2. The maximum volume brought to a temperature above the melting temperature during the simulated cascade events is well reproduced by this simple model. This volume eventually constitutes a relevant estimate of the volume affected by a displacement cascade in UO2. This definition of the cascade volume could also make sense in other materials, like iron.

  14. A relativistic self-consistent model for studying enhancement of space charge limited field emission due to counter-streaming ions

    NASA Astrophysics Data System (ADS)

    Lin, M. C.; Lu, P. S.; Chang, P. C.; Ragan-Kelley, B.; Verboncoeur, J. P.

    2014-02-01

    Recently, field emission has attracted increasing attention despite the practical limitation that field emitters operate below the Child-Langmuir space charge limit. By introducing counter-streaming ion flow to neutralize the electron charge density, the space charge limited field emission (SCLFE) current can be dramatically enhanced. In this work, we have developed a relativistic self-consistent model for studying the enhancement of SCLFE by a counter-streaming ion current. The maximum enhancement is found when the ion effect is saturated, as shown analytically. The solutions in non-relativistic, intermediate, and ultra-relativistic regimes are obtained and verified with 1-D particle-in-cell simulations. This self-consistent model is general and can also serve as a benchmark or comparison for verification of simulation codes, as well as extension to higher dimensions.

  15. A relativistic self-consistent model for studying enhancement of space charge limited field emission due to counter-streaming ions

    SciTech Connect

    Lin, M. C. Lu, P. S.; Chang, P. C.; Ragan-Kelley, B.; Verboncoeur, J. P.

    2014-02-15

    Recently, field emission has attracted increasing attention despite the practical limitation that field emitters operate below the Child-Langmuir space charge limit. By introducing counter-streaming ion flow to neutralize the electron charge density, the space charge limited field emission (SCLFE) current can be dramatically enhanced. In this work, we have developed a relativistic self-consistent model for studying the enhancement of SCLFE by a counter-streaming ion current. The maximum enhancement is found when the ion effect is saturated, as shown analytically. The solutions in non-relativistic, intermediate, and ultra-relativistic regimes are obtained and verified with 1-D particle-in-cell simulations. This self-consistent model is general and can also serve as a benchmark or comparison for verification of simulation codes, as well as extension to higher dimensions.

  16. Gage for measuring displacements in rock samples

    DOEpatents

    Holcomb, D.J.; McNamee, M.J.

    1985-07-18

    A gage for measuring diametral displacement within a rock sample for use in a rock mechanics laboratory and in the field, comprises a support ring housing a linear variable differential transformer (LVDT), a mounting screw, and a leaf spring. The mounting screw is adjustable and defines a first point of contact with the rock sample. The leaf spring has opposite ends fixed to the inner periphery of the mounting ring. An intermediate portion of the leaf spring projecting radially inward from the ring is formed with a dimple defining a second point of contact with the sample. The first and second points of contact are diametrically opposed to each other. The LVDT is mounted in the ring with its axis parallel to the line of measurement and its core rod received in the dimple of the leaf spring. Any change in the length of the line between the first and second support points is directly communicated to the LVDT. The leaf spring is rigid to completely support lateral forces so that the LVDT is free of all load for improved precision.

  17. Gage for measuring displacements in rock samples

    DOEpatents

    Holcomb, David J.; McNamee, Michael J.

    1986-01-01

    A gage for measuring diametral displacement within a rock sample for use in a rock mechanics laboratory and in the field, comprises a support ring housing a linear variable differential transformer, a mounting screw, and a leaf spring. The mounting screw is adjustable and defines a first point of contact with the rock sample. The leaf spring has opposite ends fixed to the inner periphery of the mounting ring. An intermediate portion of the leaf spring projecting radially inward from the ring is formed with a dimple defining a second point of contact with the sample. The first and second points of contact are diametrically opposed to each other. The LVDT is mounted in the ring with its axis parallel to the line of measurement and its core rod received in the dimple of the leaf spring. Any change in the length of the line between the first and second support points is directly communicated to the LVDT. The leaf spring is rigid to completely support lateral forces so that the LVDT is free of all load for improved precision.

  18. Paddy-field contamination with 134Cs and 137Cs due to Fukushima Dai-ichi Nuclear Power Plant accident and soil-to-rice transfer coefficients.

    PubMed

    Endo, Satoru; Kajimoto, Tsuyoshi; Shizuma, Kiyoshi

    2013-02-01

    The transfer coefficient (TF) from soil to rice plants of (134)Cs and (137)Cs in the form of radioactive deposition from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in March 2011 was investigated in three rice paddy fields in Minami-Soma City. Rice crops were planted in the following May and harvested at the end of September. Soil cores of 30-cm depth were sampled from rice-planted paddy fields to measure (134)Cs and (137)Cs radioactivity at 5-cm intervals. (134)Cs and (137)Cs radioactivity was also measured in rice ears (rice with chaff), straws and roots. The rice ears were subdivided into chaff, brown rice, polished rice and rice bran, and the (134)Cs and (137)Cs radioactivity concentration of each plant part was measured to calculate the respective TF from the soil. The TF of roots was highest at 0.48 ± 0.10 in the field where the (40)K concentration in the soil core was relatively low, in comparison with TF values of 0.31 and 0.38 in other fields. Similar trends could be found for the TF of whole rice plants, excluding roots. The TF of rice ears was relatively low at 0.019-0.026. The TF of chaff, rice bran, brown rice and polished rice was estimated to be 0.049, 0.10-0.16, 0.013-0.017 and 0.005-0.013, respectively.

  19. Lattice Boltzmann simulations of supercritical CO2-water drainage displacement in porous media: CO2 saturation and displacement mechanism.

    PubMed

    Yamabe, Hirotatsu; Tsuji, Takeshi; Liang, Yunfeng; Matsuoka, Toshifumi

    2015-01-06

    CO2 geosequestration in deep aquifers requires the displacement of water (wetting phase) from the porous media by supercritical CO2 (nonwetting phase). However, the interfacial instabilities, such as viscous and capillary fingerings, develop during the drainage displacement. Moreover, the burstlike Haines jump often occurs under conditions of low capillary number. To study these interfacial instabilities, we performed lattice Boltzmann simulations of CO2-water drainage displacement in a 3D synthetic granular rock model at a fixed viscosity ratio and at various capillary numbers. The capillary numbers are varied by changing injection pressure, which induces changes in flow velocity. It was observed that the viscous fingering was dominant at high injection pressures, whereas the crossover of viscous and capillary fingerings was observed, accompanied by Haines jumps, at low injection pressures. The Haines jumps flowing forward caused a significant drop of CO2 saturation, whereas Haines jumps flowing backward caused an increase of CO2 saturation (per injection depth). We demonstrated that the pore-scale Haines jumps remarkably influenced the flow path and therefore equilibrium CO2 saturation in crossover domain, which is in turn related to the storage efficiency in the field-scale geosequestration. The results can improve our understandings of the storage efficiency by the effects of pore-scale displacement phenomena.

  20. Transport infrastructure monitoring: Testing of the NIODIM optical displacement monitoring system at the Sihlhochstrasse bridge in Zürich, Switzerland.

    NASA Astrophysics Data System (ADS)

    Hagene, J. K.

    2012-04-01

    A gound based optical displacement monitoring system, "NIODIM", is being developed by Norsk Elektro Optikk in the framework of the activities of the European project "Integrated System for Transport Infrastructure surveillance and Monitoring by Electromagnetic Sensing" (ISTIMES), funded in the 7th Framework Programme (FP7/2007-2013). The optical displacement monitoring system has now participated in two real life field campaigns one in Switzerland and one in Italy. The test campaign in Switzerland during a week in May 2011 will be presented below. The NIODIM system is based on a camera part mounted on firm ground and this camera is imaging a reference point, normally a light emitting diode (LED) which is supposed to be mounted on an object susceptible to move or oscillate. A microprocessor based unit is processing the acquired images and is calculating the displacement. The Sihlhochstrasse bridge is placed on concrete pillars in the river Sihl in Zürich and the motorway is one of the entrance routes to the city. A site visit had been performed in advance and it had been decided to mount the camera part as well as the processing unit at the lower part of the pillar above the relatively dry riverbed. The reference point in form of a light emitting diode was to be mounted below the bridge deck. However, due to practical access limitations it was not possible to place the reference LED in the middle between pillar pairs, but the LED had to be placed closer to next pair of the pillars downstream the river thus increasing the distance and possibly reducing the potential displacement. A lower signal due to reduced sensitivity (length) and due to lower deflection (better support from the pillar) had to be expected. The system would be powered by a generator placed on the riverbed. Arriving at the river front the fist day of the field trials was a surprise to most the campaign members. Due to heavy rain the week before, and in particular up in the mountains, the water

  1. Displacement of location in illusory line motion.

    PubMed

    Hubbard, Timothy L; Ruppel, Susan E

    2013-05-01

    Six experiments examined displacement in memory for the location of the line in illusory line motion (ILM; appearance or disappearance of a stationary cue is followed by appearance of a stationary line that is presented all at once, but the stationary line is perceived to "unfold" or "be drawn" from the end closest to the cue to the end most distant from the cue). If ILM was induced by having a single cue appear, then memory for the location of the line was displaced toward the cue, and displacement was larger if the line was closer to the cue. If ILM was induced by having one of two previously visible cues vanish, then memory for the location of the line was displaced away from the cue that vanished. In general, the magnitude of displacement increased and then decreased as retention interval increased from 50 to 250 ms and from 250 to 450 ms, respectively. Displacement of the line (a) is consistent with a combination of a spatial averaging of the locations of the cue and the line with a relatively weaker dynamic in the direction of illusory motion, (b) might be implemented in a spreading activation network similar to networks previously suggested to implement displacement resulting from implied or apparent motion, and (c) provides constraints and challenges for theories of ILM.

  2. Effects of rotation and magnetic field on the onset of convective instability in a liquid layer due to buoyancy and surface tension

    NASA Technical Reports Server (NTRS)

    Sarma, G. S. R.

    1982-01-01

    Thermocapillary stability characteristics of a horizontal liquid layer heated from below rotating about a vertical axis and subjected to a uniform vertical magnetic field are analyzed under a variety of thermal and electromagnetic boundary conditions. Results based on analytical solutions to the pertinent eigenvalue problems are discussed in the light of earlier work on special cases of the more general problem considered here to show in particular the effects of the heat transfer, nonzero curvature and gravity waves at the two-fluid interface. Although the expected stabilizing action of the Coriolis and Lorentz force fields in this configuration are in evidence the optimal choice of an appropriate range for the relevant parameters is shown to be critically dependent on the interfacial effects mentioned above.

  3. Micro-pixel Displacement Estimation for the Heterogeneous and Asymmetric PSFs of STEP

    NASA Astrophysics Data System (ADS)

    Zhou, Jianfeng

    2015-08-01

    Search for Terrestrial Exo-Planest (STEP) is a Chinese space mission aims at the detection of nearby earth-alike planets, comprehensive research on the planetary system with 1uas astrometry precision in the space, which will be the highest precision detection mission in the world. Micro-pixel accuracy centroid displacement estimation and the relevant detector calibration are the key techniques in this mission. Due to the instability of the spacecraft, there will be a rotation displacement between two epochs of observations. In such situation, the heterogeneous and asymmetric Point Spread Functions (PSF) of the STEP will greatly reduce the accuracy of the centroid displacement estimation. To solve this problem, we present a new algorithm in which both displacement and rotation are considered, therefore micro-pixel accuracy displacement estimation is maintained.

  4. Displacement of a maxillary third molar into the infratemporal fossa: case report.

    PubMed

    Dimitrakopoulos, Ioannis; Papadaki, Maria

    2007-01-01

    The case of a maxillary third molar displaced into the infratemporal fossa, with difficulty in localization due to the synchronous creation of oroantral communication, is described in this article. The patient was referred to the oral and maxillofacial department and underwent successful surgical treatment through an intraoral access. The causes of tooth displacement into the infratemporal fossa, the aid of a computerized tomography (CT) scan in tooth localization, and the difficulty in treating this complication, particularly when the tooth migrates toward the base of the skull, are emphasized. Prevention of maxillary third molar displacement into the infratemporal fossa predominates over removal and is achieved by adequate flap design, correct extraction technique, and a distal retractor during surgical extraction. In the case of displacement, no effort to retrieve the tooth is recommended because of the risk of hemorrhage, neurologic injury, and further displacement of the tooth. The patient should be treated with antibiotics and referred to an oral and maxillofacial department.

  5. Local interpolation of coseismic displacements measured by InSAR

    NASA Astrophysics Data System (ADS)

    Yaseen, M.; Hamm, N. A. S.; Woldai, T.; Tolpekin, V. A.; Stein, A.

    2013-08-01

    Coseismic displacements play a significant role in characterizing earthquake causative faults and understanding earthquake dynamics. They are typically measured from InSAR using pre- and post-earthquake images. The displacement map produced by InSAR may contain missing coseismic values due to the decorrelation of ASAR images. This study focused on interpolating missing values in the coseismic displacement map of the 2003 Bam earthquake using geostatistics with the aim of running a slip distribution model. The gaps were grouped into 23 patches. Variograms of the patches showed that the displacement data were spatially correlated. The variogram prepared for ordinary kriging (OK) indicated the presence of a trend and thus justified the use of universal kriging (UK). Accuracy assessment was performed in 3 ways. First, 11 patches of equal size and with an equal number of missing values generated artificially, were kriged and validated. Second, the four selected patches results were validated after shifting them to new locations without missing values and comparing them with the observed values. Finally, cross validation was performed for both types of patch at the original and shifted locations. UK results were better than OK in terms of kriging variance, mean error (ME) and root mean square error (RMSE). For both OK and UK, only 4 out of 23 patches (1, 5, 11 and 21) showed ME and RMSE values that were substantially larger than for the other patches. The accuracy assessment results were found to be satisfactory with ME and RMSE values close to zero. InSAR data inversion demonstrated the usefulness of interpolation of the missing coseismic values by improving a slip distribution model. It is therefore concluded that kriging serves as an effective tool for interpolating the missing values on a coseismic displacement map.

  6. Three-Dimensional Continuous Displacement Measurement with Temporal Speckle Pattern Interferometry

    PubMed Central

    Qin, Jie; Gao, Zhan; Wang, Xu; Yang, Shanwei

    2016-01-01

    A speckle interferometer which can measure whole field three-dimensional displacements continuously and dynamically has been built. Three different wavelength lasers are used to produce the speckle interferograms of the two in-plane displacements (displacements in the x- and y-direction) and one out-of-plane displacement (displacement in the z-direction), respectively. One color CCD camera is employed to collect these mixed speckle interferograms simultaneously. The mixed interferograms are separated by the Red, Green and Blue channels of the color CCD camera, and then are processed by the wavelet transform technique to extract the phase information of the measured object. The preliminary experiment is carried out to demonstrate the performance of this new device. PMID:27916858

  7. Magnetic field effects on the vestibular system: calculation of the pressure on the cupula due to ionic current-induced Lorentz force

    NASA Astrophysics Data System (ADS)

    Antunes, A.; Glover, P. M.; Li, Y.; Mian, O. S.; Day, B. L.

    2012-07-01

    Large static magnetic fields may be employed in magnetic resonance imaging (MRI). At high magnetic field strengths (usually from about 3 T and above) it is possible for humans to perceive a number of effects. One such effect is mild vertigo. Recently, Roberts et al (2011 Current Biology 21 1635-40) proposed a Lorentz-force mechanism resulting from the ionic currents occurring naturally in the endolymph of the vestibular system. In the present work a more detailed calculation of the forces and resulting pressures in the vestibular system is carried out using a numerical model. Firstly, realistic 3D finite element conductivity and fluid maps of the utricle and a single semi-circular canal containing the current sources (dark cells) and sinks (hair cells) of the utricle and ampulla were constructed. Secondly, the electrical current densities in the fluid are calculated. Thirdly, the developed Lorentz force is used directly in the Navier-Stokes equation and the trans-cupular pressure is computed. Since the driving force field is relatively large in comparison with the advective acceleration, we demonstrate that it is possible to perform an approximation in the Navier-Stokes equations that reduces the problem to solving a simpler Poisson equation. This simplification allows rapid and easy calculation for many different directions of applied magnetic field. At 7 T a maximum cupula pressure difference of 1.6 mPa was calculated for the combined ampullar (0.7 µA) and utricular (3.31 µA) distributed current sources, assuming a hair-cell resting current of 100 pA per unit. These pressure values are up to an order of magnitude lower than those proposed by Roberts et al using a simplistic model and calculation, and are in good agreement with the estimated pressure values for nystagmus velocities in caloric experiments. This modeling work supports the hypothesis that the Lorentz force mechanism is a significant contributor to the perception of magnetic field induced vertigo.

  8. Variable displacement alpha-type Stirling engine

    NASA Astrophysics Data System (ADS)

    Homutescu, V. M.; Bălănescu, D. T.; Panaite, C. E.; Atanasiu, M. V.

    2016-08-01

    The basic design and construction of an alpha-type Stirling engine with on load variable displacement is presented. The variable displacement is obtained through a planar quadrilateral linkage with one on load movable ground link. The physico-mathematical model used for analyzing the variable displacement alpha-type Stirling engine behavior is an isothermal model that takes into account the real movement of the pistons. Performances and power adjustment capabilities of such alpha-type Stirling engine are calculated and analyzed. An exemplification through the use of the numerical simulation was performed in this regard.

  9. Displacement sensor based on plasmonic slot metamaterials

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Ren, Mengxin; Pi, Biao; Cai, Wei; Xu, Jingjun

    2016-02-01

    In this paper, we demonstrate a plasmonic type displacement sensor based on slot metamaterials. The sensors are formed by arranging metamaterial arrays with different dimension parameters adjacently. Hence, the measured spectra would be modified as a result of moving the sensors across the detecting area of the spectrometer. From the spectral changes, the displacement amount could be retrieved. The sensor is demonstrated to be capable of recognizing a displacement of 200 nm, which is equal to the period of the metamaterial lattice, and the sensitivity is largely dependent on the shape and size of the acquisition area of the spectrometer used for spectra analysis.

  10. The self-consistent parallel electric field due to electrostatic ion-cyclotron turbulence in downward auroral-current regions of the Earth's magnetosphere. IV

    SciTech Connect

    Jasperse, John R.; Basu, Bamandas; Lund, Eric J.; Grossbard, Neil

    2010-06-15

    The physical processes that determine the self-consistent electric field (E{sub ||}) parallel to the magnetic field have been an unresolved problem in magnetospheric physics for over 40 years. Recently, a new multimoment fluid theory was developed for inhomogeneous, nonuniformly magnetized plasma in the guiding-center and gyrotropic approximation that includes the effect of electrostatic, turbulent, wave-particle interactions (see Jasperse et al. [Phys. Plasmas 13, 072903 (2006); ibid.13, 112902 (2006)]). In the present paper and its companion paper [Jasperse et al., Phys. Plasmas 17, 062903 (2010)], which are intended as sequels to the earlier work, a fundamental model for downward, magnetic field-aligned (Birkeland) currents for quasisteady conditions is presented. The model includes the production of electrostatic ion-cyclotron turbulence in the long-range potential region by an electron, bump-on-tail-driven ion-cyclotron instability. Anomalous momentum transfer (anomalous resistivity) by itself is found to produce a very small contribution to E{sub ||}; however, the presence of electrostatic, ion-cyclotron turbulence has a very large effect on the altitude dependence of the entire quasisteady solution. Anomalous energy transfer (anomalous heating and cooling) modifies the density, drift, and temperature altitude profiles and hence the generalized parallel-pressure gradients and mirror forces in the electron and ion momentum-balance equations. As a result, |E{sub ||}| is enhanced by nearly a factor of 40 compared to its value when turbulence is absent. The space-averaged potential increase associated with the strong double layer at the bottom of the downward-current sheet is estimated using the FAST satellite data and the multimoment fluid theory.

  11. Topographic amplification of tectonic displacement: Implications for geodetic measurement of strain changes

    SciTech Connect

    McTigue, D.F.; Stein, R.S.

    1984-02-10

    Correlations of level changes with topography demand an assessment of the effect of an irregular free boundary on surface deformation. This is examined through a plane strain elastic model with topography of small slope, subjected to a change in the far-field horizontal stress. To leading order, vertical surface displacements due to the topographic perturbation are proportional to the local relief. Elevation-dependent uplift results from a compressional change, and downdrop results from a tensional change. The model further predicts that the ratio of elevation change to elevation is proportional to and of the same order of magnitude as the regional strain. Horizontal strains are locally perturbed by topography as well, with the magnitude scaling with the local slope.. The predicted localization of level changes is very small in aseismic regions and cannot contribute significantly to measured correlations. A test case in southern California bears this out, with strains of order 10/sup -6/ accompanied by elevation change to elevation ratios of order 10/sup -4/. Releveling following the Nankaido-Tonankai earthquakes, which induced large coseismic and postseismic strains, reveals scattered examples of elevation-dependent level changes. However, when compared to modeled strains, the correlations are again at least an order of magnitude larger than the localization effect predicted by the elastic model. Although the topographic perturbation of vertical displacements appears to be unmeasurably small, local variations in horizontal strain or borehole dilatation across steep relief may be discernible with current technology.

  12. Accurate Feeding of Nanoantenna by Singular Optics for Nanoscale Translational and Rotational Displacement Sensing

    NASA Astrophysics Data System (ADS)

    Xi, Zheng; Wei, Lei; Adam, A. J. L.; Urbach, H. P.; Du, Luping

    2016-09-01

    Identifying subwavelength objects and displacements is of crucial importance in optical nanometrology. We show in this Letter that nanoantennas with subwavelength structures can be excited precisely by incident beams with singularity. This accurate feeding beyond the diffraction limit can lead to dynamic control of the unidirectional scattering in the far field. The combination of the field discontinuity of the incoming singular beam with the rapid phase variation near the antenna leads to remarkable sensitivity of the far-field scattering to the displacement at a scale much smaller than the wavelength. This Letter introduces a far-field deep subwavelength position detection method based on the interaction of singular optics with nanoantennas.

  13. Numerical Study of Pressure Field in Laterally Closed Industrial Buildings with Curved Metallic Roofs due to the Wind Effect by FEM and European Rule Comparison

    NASA Astrophysics Data System (ADS)

    Nieto, P. J. García; del Coz Díaz, J. J.; Vilán, J. A. Vilán; Placer, C. Casqueiro

    2009-08-01

    In this paper, an evaluation of distribution of the air pressure is determined throughout the laterally closed industrial buildings with curved metallic roofs due to the wind effect by the finite element method (FEM). The non-linearity is due to Reynolds-averaged Navier-Stokes (RANS) equations that govern the turbulent flow. The Navier-Stokes equations are non-linear partial differential equations and this non-linearity makes most problems difficult to solve and is part of the cause of turbulence. The RANS equations are time-averaged equations of motion for fluid flow. They are primarily used while dealing with turbulent flows. Turbulence is a highly complex physical phenomenon that is pervasive in flow problems of scientific and engineering concern like this one. In order to solve the RANS equations a two-equation model is used: the standard k-ɛ model. The calculation has been carried out keeping in mind the following assumptions: turbulent flow, an exponential-like wind speed profile with a maximum velocity of 40 m/s at 10 m reference height, and different heights of the building ranging from 6 to 10 meters. Finally, the forces and moments are determined on the cover, as well as the distribution of pressures on the same one, comparing the numerical results obtained with the Spanish CTE DB SE-AE, Spanish NBE AE-88 and European standard rules, giving place to the conclusions that are exposed in the study.

  14. Numerical analysis of pressure field on curved self-weighted metallic roofs due to the wind effect by the finite element method

    NASA Astrophysics Data System (ADS)

    Del Coz Diaz, J. J.; Garcia Nieto, P. J.; Suarez Dominguez, F. J.

    2006-07-01

    In this paper, an evaluation of distribution of the air pressure is determined throughout the curved and open self-weighted metallic roof due to the wind effect by the finite element method (FEM) [K. Bathe, Finite Element Procedures, Prentice-Hall, Englewood Cliffs, New York, 1996]. Data from experimental tests carried out in a wind tunnel involving a reduced scale model of a roof was used for comparison. The nonlinearity is due to time-averaged Navier-Stokes equations [C.A.J. Fletcher, Computational Techniques for Fluid Dynamics, Springer, Berlin, 1991] that govern the turbulent flow. The calculation has been carried out keeping in mind the possibility of turbulent flow in the vicinities of the walls, and speeds of wind have been analyzed between 30 and 40 m/s. Finally, the forces and moments are determined on the cover, as well as the distribution of pressures on the same one, comparing the results obtained with the Spanish and European Standards rules, giving place to the conclusions that are exposed in the study.

  15. The first clinical case due to AP92 like strain of Crimean-Congo Hemorrhagic Fever virus and a field survey

    PubMed Central

    2009-01-01

    Background Crimean-Congo Hemorrhagic Fever (CCHF) is a fatal infection, but no clinical case due to AP92 strain was reported. We described the first clinical case due to AP92 like CCHFV. Methods A case infected by a AP92 like CCHFV was detected in Balkanian part of Turkey. Diagnosis was confirmed by RT-PCR and sequencing. A human serologic and tick survey studies were performed in the region, where the case detected. Results Thirty eight individuals out of 741 were found to be anti CCHFV IgM positive. The attack rate for overall CCHFV was calculated as 5.2%. In univariate analyses, CCHFV IgM positivity was found to be associated with the age (p < 0.001), male gender (p = 0.001), agricultural activity (p = 0.036), and history of tick bite (p = 0.014). In multivariate analysis, older age (OR: 1.03, CI:1.01–1.05, p < 0.001), male gender were found to be the risk factors (OR: 2.5, CI:1.15–5.63, p = 0.020) for CCHFV infection. Conclusion This is the first human case with AP92 like CCHFV infection. Furthermore, this is the first report of AP92 like strain in Turkey. In the region, elderly males carry the highest risk for CCHFV infection. PMID:19515251

  16. Beam Dynamics Enhancement due to Accelerating Field Symmetrization in the BNL/SLAC/UCLA 1.6 cell S-Band Photocathode RF Gun

    NASA Astrophysics Data System (ADS)

    Palmer, D. T.; Wang, X. J.; Ben-Zvi, I.; Miller, R. H.

    1997-05-01

    A 1.6 cell photocathode S-Band gun developed by the BNL/SLAC/UCLA collaboration is now in operation at the Brookhaven Accelerator Test Facility (ATF). One of the main features of this RF gun is the symmetrization of the RF coupling iris with a identical vacuum pumping port located in the full cell. The effects of the asymmetry caused by the RF coupling iris were experimentally investigated by positioning a metallic plunger at the back wall of the vacuum port iris. The higher order modes produced were studied using electron beamlets with n-fold symmetry. The n-fold beamlets were produced by masking the laser beam. These experimental results indicate that the integrated electrical center and the geometrical center of the gun are within 175 μm. Which is within the laser alignment tolerance of 250 μm. Comparing these results to previous generations of BNL type RF guns, there has been an order of magnitude decrease in the dipole field components of the longitudinal accelerating field E_z. Low power RF cold tests measurements of the guns full cell are consistent with the experimental beam dynamics transport studies.

  17. THREE-DIMENSIONAL FEATURES OF THE OUTER HELIOSPHERE DUE TO COUPLING BETWEEN THE INTERSTELLAR AND INTERPLANETARY MAGNETIC FIELDS. III. THE EFFECTS OF SOLAR ROTATION AND ACTIVITY CYCLE

    SciTech Connect

    Pogorelov, Nikolai V.; Borovikov, Sergey N.; Zank, Gary P.; Ogino, Tatsuki E-mail: snb0003@uah.edu E-mail: ogino@stelab.nagoya-u.ac.jp

    2009-05-10

    We investigate the effects of the 11 year solar cycle and 25 day rotation period of the Sun on the interaction of the solar wind (SW) with the local interstellar medium (LISM). Our models take into account the partially ionized character of the LISM and include momentum and energy transfer between the ionized and neutral components. We assume that the interstellar magnetic field vector belongs to the hydrogen deflection plane as discovered in the SOHO SWAN experiment. This plane is inclined at an angle of about 60 deg. toward the ecliptic plane of the Sun, as suggested in recent publications relating the local interstellar cloud properties to the radio emission observed by Voyager 1. It is assumed that the latitudinal extent of the boundary between the slow and fast SW regions, as well as the angle between the Sun's rotation and magnetic-dipole axes, are periodic functions of time, while the polarity of the interstellar magnetic field changes sign every 11 years at the solar maximum. The global variation of the SW-LISM interaction pattern, the excursions of the termination shock and the heliopause, and parameter distributions in certain directions are investigated. The analysis of the behavior of the wavy heliospheric current sheet in the supersonic SW region shows the importance of neutral atoms on its dynamics.

  18. Stepping Aside: Correlates of Displacement in Pedestrians.

    ERIC Educational Resources Information Center

    Willis, Frank N., Jr.; And Others

    1979-01-01

    Examines the effects of gender, age, race, group size, and other characteristics on spatial displacement in the general population. Considers the relative contributions of power, gallantry, and status in the determining of who yields to whom. (JMF)

  19. Bucky gel actuator displacement: experiment and model

    NASA Astrophysics Data System (ADS)

    Ghamsari, A. K.; Jin, Y.; Zegeye, E.; Woldesenbet, E.

    2013-02-01

    Bucky gel actuator (BGA) is a dry electroactive nanocomposite which is driven with a few volts. BGA’s remarkable features make this tri-layered actuator a potential candidate for morphing applications. However, most of these applications would require a better understanding of the effective parameters that influence the BGA displacement. In this study, various sets of experiments were designed to investigate the effect of several parameters on the maximum lateral displacement of BGA. Two input parameters, voltage and frequency, and three material/design parameters, carbon nanotube type, thickness, and weight fraction of constituents were selected. A new thickness ratio term was also introduced to study the role of individual layers on BGA displacement. A model was established to predict BGA maximum displacement based on the effect of these parameters. This model showed good agreement with reported results from the literature. In addition, an important factor in the design of BGA-based devices, lifetime, was investigated.

  20. Buoyant miscible displacement flows in vertical pipe

    NASA Astrophysics Data System (ADS)

    Amiri, A.; Larachi, F.; Taghavi, S. M.

    2016-10-01

    The displacement flow of two miscible Newtonian fluids is investigated experimentally in a vertical pipe of long aspect ratio (δ-1 ≈ 210). The fluids have a small density difference and they have the same viscosity. The heavy displacing fluid is initially placed above the light displaced fluid. The displacement flow is downwards. The experiments cover a wide range of the two dimensionless parameters that largely describe the flow: the modified Reynolds number (0 ≤ Ret⪅800) and the densimetric Froude number (0 ≤ Fr ≤ 24). We report on the stabilizing effect of the imposed flow and uncover the existence of two main flow regimes at long times: a stable displacement flow and an unstable displacement flow. The transition between the two regimes occurs at a critical modified Reynolds number " separators=" R et | Critical , as a function of Fr. We study in depth the stable flow regime: First, a lubrication model combined with a simple initial acceleration formulation delivers a reasonable prediction to the time-dependent penetrating displacing front velocity. Second, we find two sub-regimes for stable displacements, namely, sustained-back-flows and no-sustained-back-flows. The transition between the two sub-regimes is a marginal stationary interface flow state, which is also well predicted by the lubrication model. The unstable regime is associated to instabilities and diffusive features of the flow. In addition, particular patterns such as front detachment phenomenon appear in the unstable flow regime, for which we quantify the regions of existence versus the dimensionless groups.

  1. Monolithically integrated interferometer for optical displacement measurement

    NASA Astrophysics Data System (ADS)

    Hofstetter, Daniel; Zappe, Hans P.

    1996-01-01

    We discuss the fabrication of a monolithically integrated optical displacement sensors using III-V semiconductor technology. The device is configured as a Michelson interferometer and consists of a distributed Bragg reflector laser, a photodetector and waveguides forming a directional coupler. Using this interferometer, displacements in the 100 nm range could be measured at distances of up to 45 cm. We present fabrication, device results and characterization of the completed interferometer, problems, limitations and future applications will also be discussed.

  2. Displacement sensor for indoor machine calibrations.

    PubMed

    Mudassar, Asloob Ahmad; Butt, Saira

    2013-05-20

    This paper presents a simple displacement sensor for indoor machine calibrations. The sensor, which is placed in the path of a diverging laser beam, consists of two plane mirror pieces laterally displaced with the line joining their centers initially held perpendicular to the optical axis of the beam during the displacement of the sensor with one of the mirrors always traveling along the optical axis of the laser beam. The optical signals from the two mirrors are combined and a simple detector at the interference plane counts the fringes during the sensor displacement. The sensor could be mounted on the moving head of any mechanical machine, e.g., the lathe machine for displacement calibration. The device has been tested over a range of 10 cm beyond a distance of 150 cm from a diverging laser source giving an accuracy of 1.1015 μm. Theoretical modeling, simulation, and experimental results are presented which establish that the proposed sensor can be used as a promising displacement measuring device.

  3. Development and evolution of character displacement.

    PubMed

    Pfennig, David W; Pfennig, Karin S

    2012-05-01

    Character displacement occurs when competition for either resources or successful reproduction imposes divergent selection on interacting species, causing divergence in traits associated with resource use or reproduction. Here, we describe how character displacement can be mediated either by genetically canalized changes (i.e., changes that reflect allelic or genotype frequency changes) or by phenotypic plasticity. We also discuss how these two mechanisms influence the tempo of character displacement. Specifically, we suggest that, under some conditions, character displacement mediated by phenotypic plasticity might occur more rapidly than that mediated by genetically canalized changes. Finally, we describe how these two mechanisms may act together and determine character displacement's mode, such that it proceeds through an initial phase in which trait divergence is environmentally induced to a later phase in which divergence becomes genetically canalized. This plasticity-first hypothesis predicts that character displacement should be generally mediated by ancestral plasticity and that it will arise similarly in multiple, independently evolving populations. We conclude by highlighting future directions for research that would test these predictions.

  4. Displacement of the anterior leaflet of the tricuspid valve: Rare variant of Ebstein's anomaly.

    PubMed

    Tsujii, Nobuyuki; Kurosaki, Kenichi; Yasuda, Kenji; Mizuno, Masanori; Sakaguchi, Heima; Hoashi, Takaya; Ichikawa, Hajime; Shiraishi, Isao

    2016-08-01

    In Ebstein's anomaly, the points of attachment, or hinges, of the septal and mural leaflets in the right ventricle are displaced away from the atrioventricular junction. In contrast, the junctional hinge of the anterior leaflet usually retains a normal position. Here, we report a case of giant right atrial aneurysm due to isolated displacement of the anterior leaflet of the tricuspid valve in an infant, a rare variant of Ebstein's anomaly. Enlargement of the right atrium, which was initially diagnosed during the fetal period, progressively and markedly dilated after birth and was successfully treated with surgical resection. Isolated displacement of the anterior leaflet should be recognized as a variant of Ebstein's anomaly.

  5. Molecular Dynamics Simulations of Displacement Cascades in Single and Polycrystalline Zirconia

    SciTech Connect

    Du Jincheng

    2009-03-10

    Displacement cascades in zirconia have been studied using classical molecular dynamics simulations. Polycrystalline zirconia with nano-meter grains were created using Voronoi polyhedra construction and studied in comparison with single crystalline zirconia. The results show that displacement cascades with similar kinetic energy generated larger number of displaced atoms in polycrystalline than in the single crystal structure. The fraction of atoms with coordination number change was also higher in polycrystalline zirconia that was explained to be due to the diffusion of oxygen and relaxation at grain boundaries.

  6. An Analysis of Displacement Measurements for Lisbon, Portugal Using Combined InSAR and GNSS Data

    NASA Astrophysics Data System (ADS)

    Roque, D.; Simonetto, E.; Falcao, A. P.; Perissin, D.; Durand, F.; Morel, L.; Fonseca, A. M.; Polidori, L.

    2016-08-01

    Atmospheric effects are still a limitation to the application of InSAR techniques for displacement measurement. In this study, zenith total delay (ZTD) values derived from global navigation satellite system (GNSS) are used to correct interferograms from tropospheric effects. Displacement measurements are obtained from the corrected interferograms through a persistent scatterer interferometry approach. The influence of different interpolation methods on the construction of ZTD maps is tested through two different algorithms: cubic spline and ordinary kriging. Differences are observed between the cumulative displacement maps obtained with both interpolators, but atmospheric effects are still present, possibly due to the small number of available GNSS stations.

  7. Direct observation of depth-dependent atomic displacements associated with dislocations in gallium nitride.

    PubMed

    Lozano, J G; Yang, H; Guerrero-Lebrero, M P; D'Alfonso, A J; Yasuhara, A; Okunishi, E; Zhang, S; Humphreys, C J; Allen, L J; Galindo, P L; Hirsch, P B; Nellist, P D

    2014-09-26

    We demonstrate that the aberration-corrected scanning transmission electron microscope has a sufficiently small depth of field to observe depth-dependent atomic displacements in a crystal. The depth-dependent displacements associated with the Eshelby twist of dislocations in GaN normal to the foil with a screw component of the Burgers vector are directly imaged. We show that these displacements are observed as a rotation of the lattice between images taken in a focal series. From the sense of the rotation, the sign of the screw component can be determined.

  8. Viral fitness does not correlate with three genotype displacement events involving infectious hematopoietic necrosis virus

    USGS Publications Warehouse

    Kell, Alison M.; Wargo, Andrew R.; Kurath, Gael

    2014-01-01

    Viral genotype displacement events are characterized by the replacement of a previously dominant virus genotype by a novel genotype of the same virus species in a given geographic region. We examine here the fitness of three pairs of infectious hematopoietic necrosis virus (IHNV) genotypes involved in three major genotype displacement events in Washington state over the last 30 years to determine whether increased virus fitness correlates with displacement. Fitness was assessed using in vivo assays to measure viral replication in single infection, simultaneous co-infection, and sequential superinfection in the natural host, steelhead trout. In addition, virion stability of each genotype was measured in freshwater and seawater environments at various temperatures. By these methods, we found no correlation between increased viral fitness and displacement in the field. These results suggest that other pressures likely exist in the field with important consequences for IHNV evolution.

  9. Viral fitness does not correlate with three genotype displacement events involving infectious hematopoietic necrosis virus.

    PubMed

    Kell, Alison M; Wargo, Andrew R; Kurath, Gael

    2014-09-01

    Viral genotype displacement events are characterized by the replacement of a previously dominant virus genotype by a novel genotype of the same virus species in a given geographic region. We examine here the fitness of three pairs of infectious hematopoietic necrosis virus (IHNV) genotypes involved in three major genotype displacement events in Washington state over the last 30 years to determine whether increased virus fitness correlates with displacement. Fitness was assessed using in vivo assays to measure viral replication in single infection, simultaneous co-infection, and sequential superinfection in the natural host, steelhead trout. In addition, virion stability of each genotype was measured in freshwater and seawater environments at various temperatures. By these methods, we found no correlation between increased viral fitness and displacement in the field. These results suggest that other pressures likely exist in the field with important consequences for IHNV evolution.

  10. Simulation of foam displacement in porous media

    SciTech Connect

    Kovscek, A.R.; Patzek, T.W.; Radke, C.J.

    1993-08-01

    Foam is an excellent fluid for achieving mobility control of gas in porous media. Practical application of foams for EOR processes, however requires a predictive model of foam displacement. Further, quantitative information on foam-flow behavior at reservoir flow rates and pressures is required as input to any field-scale modeling. An experimental and mechanistic-modeling study is reported for the transient flow of foam through 1.3 {mu}m{sup 2} (1.3 D) Boise sandstone at backpressures in excess of 5 MPa (700 psi) over a quality range from 0.80 to 0.99. Total superficial velocities range from as little as 0.42 to 2.20 m/day (1.4 ft/day to 7 ft/day). Sequential pressure taps and gamma-ray densitometry measure flow resistance and in-situ liquid saturations, respectively. We garner experimental pressure and saturation profiles in both the transient and steady states. Adoption of a mean-size foam-bubble conservation equation along with the traditional reservoir simulation equations allows mechanistic foam simulation. Since foam mobility depends heavily upon its texture, the bubble population balance is both useful and necessary as the role of foam texture must be incorporated into any model which seeks accurate prediction of flow properties. Our model employs capillary-pressure-dependent kinetic expressions for lamellae generation and coalescence and also a term for trapping of lamellae. Additionally, the effects of surfactant chemical transport are included. We find quantitative agreement between experimental and theoretical saturation and pressure profiles in both the transient and steady states.

  11. Soil carbon sequestration due to post-Soviet cropland abandonment: estimates from a large-scale soil organic carbon field inventory.

    PubMed

    Wertebach, Tim-Martin; Hölzel, Norbert; Kämpf, Immo; Yurtaev, Andrey; Tupitsin, Sergey; Kiehl, Kathrin; Kamp, Johannes; Kleinebecker, Till

    2017-02-04

    The break-up of the Soviet Union in 1991 triggered cropland abandonment on a continental scale, which in turn led to carbon accumulation on abandoned land across Eurasia. Previous studies have estimated carbon accumulation rates across Russia based on large-scale modelling. Studies that assess carbon sequestration on abandoned land based on robust field sampling are rare. We investigated soil organic carbon (SOC) stocks using a randomized sampling design along a climatic gradient from forest steppe to Sub-Taiga in Western Siberia (Tyumen Province). In total, SOC contents were sampled on 470 plots across different soil and land-use types. The effect of land use on changes in SOC stock was evaluated, and carbon sequestration rates were calculated for different age stages of abandoned cropland. While land-use type had an effect on carbon accumulation in the topsoil (0-5 cm), no independent land-use effects were found for deeper SOC stocks. Topsoil carbon stocks of grasslands and forests were significantly higher than those of soils managed for crops and under abandoned cropland. SOC increased significantly with time since abandonment. The average carbon sequestration rate for soils of abandoned cropland was 0.66 Mg C ha(-1)  yr(-1) (1-20 years old, 0-5 cm soil depth), which is at the lower end of published estimates for Russia and Siberia. There was a tendency towards SOC saturation on abandoned land as sequestration rates were much higher for recently abandoned (1-10 years old, 1.04 Mg C ha(-1)  yr(-1) ) compared to earlier abandoned crop fields (11-20 years old, 0.26 Mg C ha(-1)  yr(-1) ). Our study confirms the global significance of abandoned cropland in Russia for carbon sequestration. Our findings also suggest that robust regional surveys based on a large number of samples advance model-based continent-wide SOC prediction.

  12. Use of pulsed-field gel electrophoresis typing to study an outbreak of infection due to Serratia marcescens in a neonatal intensive care unit.

    PubMed Central

    Miranda, G; Kelly, C; Solorzano, F; Leanos, B; Coria, R; Patterson, J E

    1996-01-01

    Serratia marcescens is a well-known cause of nosocomial infections and outbreaks, particularly in critically ill neonates and immunocompromised patients. Numerous methods have been proposed for typing. We used pulsed-field gel electrophoresis (PFGE) typing to analyze an outbreak in a neonatal intensive care unit (NICU). We included 23 patient isolates from an outbreak (March to July 1995), and 10 patient isolates from different wards during the same time period. PFGE of whole-cell DNA digested by SpeI was used as a marker of strain identity. The most common presentation of the infection was sepsis in 18 of 23 (78%) neonates. Only four different biotypes were identified; biotype A8d accounted for 84% of the strains. PFGE typing revealed two clones responsible for two different clonal strain dissemination outbreaks from March to July, with 24 patient isolates being pattern A and 4 patient isolates being pattern E. PFGE typing suggests cross transmission between patients in the NICU and other wards. The isolates from 5 other patients showed distinct PFGE patterns. Extensive investigation and cultures failed to identify any environmental or staff reservoir of S. marcescens. This is one of the first reports applying PFGE to the study of S. marcescens, and this method was a useful marker of strain identity. PFGE typing distinguished strains which appeared to be the same by biotyping. PMID:8940460

  13. Impact of caprock permeability on vertical ground surface displacements in geological underground utilisation

    NASA Astrophysics Data System (ADS)

    Kempka, Thomas; Tillner, Elena

    2015-04-01

    Geological underground utilisation inducing pore pressure changes in underground reservoirs is generally accompanied by hydro-mechanical processes. Thereby, pore pressure increase due to fluid injection may trigger ground surface uplift, while a decrease in pore pressure due to reservoir fluid production is known to induce ground subsidence. Different coupled hydro-mechanical simulation studies (e.g. Klimkowski et al., 2015, Kempka et al., 2014, Tillner et al., 2014) indicate that ground surface displacements can achieve a magnitude of several decimetres, if storage or production operations are being carried out at an industrial scale. Consequently, detailed knowledge on the parameters impacting ground surface uplift or subsidence is of major interest for the success of any geological underground utilisation in order to avoid surface infrastructure damage by spatially varying deformations. Furthermore, ground subsidence may result increased groundwater levels as experienced in different underground coal mining districts. In the present study, we carried out coupled hydro-mechanical simulations to account for the impact of caprock permeability on ground surface displacements resulting from geological underground utilisation. Thereto, different simulation scenarios were investigated using a synthetic 3D coupled numerical simulation model with varying caprock permeability and vertical location of the open well section in the target reservoir. Material property ranges were derived from available literature, while a normal faulting stress state was applied in all simulation scenarios. Our simulation results demonstrate that caprock permeability has a significant impact on the pressure development, and thus on vertical displacements at the ground surface as well as at the reservoir top. An increase in caprock permeability from 1 x 10-20 m2 by two orders of magnitude doubles vertical displacements at the ground surface, whereas vertical displacements at the reservoir top

  14. Surface displacements in the 1906 San Francisco and 1989 Loma Prieta Earthquakes

    SciTech Connect

    Segall, P. Geological Survey, Menlo Park, CA ); Lisowski, M. )

    1990-11-30

    The horizontal displacements accompanying the 1906 San Francisco earthquake and the 1989 Loma Prieta earthquake are computed from geodetic survey measurements. The 1906 earthquake displacement field is entirely consistent with right-lateral strike slip on the San Andreas fault. In contrast, the 1989 Loma Prieta earthquake exhibited subequal components of strike slip and reverse faulting. This result, together with other seismic and geologic data, may indicate that the two earthquakes occurred on two different fault planes.

  15. Surface displacements in the 1906 San Francisco and 1989 Loma Prieta earthquakes

    USGS Publications Warehouse

    Segall, P.; Lisowski, M.

    1990-01-01

    The horizontal displacements accompanying the 1906 San Francisco earthquake and the 1989 Loma Prieta earthquake are computed from geodetic survey measurements. The 1906 earthquake displacement field is entirely consistent with right-lateral strike slip on the San Andreas fault. In contrast, the 1989 Loma Prieta earthquake exhibited subequal components of strike slip and reverse faulting. This result, together with other seismic and geologic data, may indicate that the two earthquakes occurred on two different fault planes.

  16. Surface displacements in the 1906 san francisco and 1989 loma prieta earthquakes.

    PubMed

    Segall, P; Lisowski, M

    1990-11-30

    The horizontal displacements accompanying the 1906 San Francisco earthquake and the 1989 Loma Prieta earthquake are computed from geodetic survey measurements. The 1906 earthquake displacement field is entirely consistent with right-lateral strike slip on the San Andreas fault. In contrast, the 1989 Loma Prieta earthquake exhibited subequal components of strike slip and reverse faulting. This result, together with other seismic and geologic data, may indicate that the two earthquakes occurred on two different fault planes.

  17. MHD dissipative flow and heat transfer of Casson fluids due to metachronal wave propulsion of beating cilia with thermal and velocity slip effects under an oblique magnetic field

    NASA Astrophysics Data System (ADS)

    Akbar, Noreen Sher; Tripathi, D.; Bég, O. Anwar; Khan, Z. H.

    2016-11-01

    A theoretical investigation of magnetohydrodynamic (MHD) flow and heat transfer of electrically-conducting viscoplastic fluids through a channel is conducted. The robust Casson model is implemented to simulate viscoplastic behavior of fluids. The external magnetic field is oblique to the fluid flow direction. Viscous dissipation effects are included. The flow is controlled by the metachronal wave propagation generated by cilia beating on the inner walls of the channel. The mathematical formulation is based on deformation in longitudinal and transverse velocity components induced by the ciliary beating phenomenon with cilia assumed to follow elliptic trajectories. The model also features velocity and thermal slip boundary conditions. Closed-form solutions to the non-dimensional boundary value problem are obtained under physiological limitations of low Reynolds number and large wavelength. The influence of key hydrodynamic and thermo-physical parameters i.e. Hartmann (magnetic) number, Casson (viscoplastic) fluid parameter, thermal slip parameter and velocity slip parameter on flow characteristics are investigated. A comparative study is also made with Newtonian fluids (corresponding to massive values of plastic viscosity). Stream lines are plotted to visualize trapping phenomenon. The computations reveal that velocity increases with increasing the magnitude of Hartmann number near the channel walls whereas in the core flow region (center of the channel) significant deceleration is observed. Temperature is elevated with greater Casson parameter, Hartmann number, velocity slip, eccentricity parameter, thermal slip and also Brinkmann (dissipation) number. Furthermore greater Casson parameter is found to elevate the quantity and size of the trapped bolus. In the pumping region, the pressure rise is reduced with greater Hartmann number, velocity slip, and wave number whereas it is enhanced with greater cilia length.

  18. Changes in polyphenol profiles and color composition of freshly fermented model wine due to pulsed electric field, enzymes and thermovinification pretreatments.

    PubMed

    El Darra, Nada; Turk, Mohammad F; Ducasse, Marie-Agnès; Grimi, Nabil; Maroun, Richard G; Louka, Nicolas; Vorobiev, Eugène

    2016-03-01

    This work compares the effects of three pretreatments techniques: pulsed electric fields (PEFs), enzymes treatment (ET) and thermovinification (TV) on the improving of extraction of main phenolic compounds, color characteristics (L(∗)a(∗)b(∗)), and composition (copigmentation, non-discolored pigments) of freshly fermented model wine from Cabernet Sauvignon variety. The pretreatments produced differences in the wines, with the color of the freshly fermented model wine obtained from PEF and TV pretreated musts being the most different with an increase of 56% and 62%, respectively, compared to the control, while the color only increased by 22% for ET. At the end of the alcoholic fermentation, the contents of anthocyanins for all the pretreatments were not statistically different. However, for the content of total phenolics and total flavonols, PEF and TV were statistically different, but ET was not statistically different. The contents of flavonols in musts pretreated by PEF and TV were significantly higher comparing to the control. An increase of 48% and 97% was noted respectively, and only 4% for ET. A similar result was observed for the total phenolics with an increase by 18% and 32% respectively for PEF and TV, and only 3% for ET comparing to the control. The results suggest that the higher intensity and the difference of color composition between the control and pretreated freshly fermented model wines were not related only to a higher content of residual native polyphenols in these freshly fermented model wines. Other phenomena such as copigmentation and formation of derived pigments may be favored by these pretreatments.

  19. Public self-consciousness moderates the link between displacement behaviour and experience of stress in women.

    PubMed

    Mohiyeddini, Changiz; Bauer, Stephanie; Semple, Stuart

    2013-07-01

    When stressed, people typically show elevated rates of displacement behaviour--activities such as scratching and face touching that seem irrelevant to the ongoing situation. Growing evidence indicates that displacement behaviour may play a role in regulating stress levels, and thus may represent an important component of the coping response. Recently, we found evidence that this stress-regulating effect of displacement behaviour is found in men but not in women. This sex difference may result from women's higher levels of public self-consciousness, which could inhibit expression of displacement behaviour due to the fear of projecting an inappropriate image. Here, we explored the link between public self-consciousness, displacement behaviour and stress among 62 healthy women (mean age = 26.59 years; SD = 3.61). We first assessed participants' public self-consciousness, and then quantified displacement behaviour, heart rate and cognitive performance during a Trier Social Stress Test (TSST) and used self-report questionnaires to assess the experience of stress afterwards. Public self-consciousness was negatively correlated with rate of displacement behaviour, and positively correlated with both the subjective experience of stress post-TSST and the number of mistakes in the cognitive task. Moderation analyses revealed that for women high in public self-consciousness, high levels of displacement behaviour were associated with higher reported levels of stress and poorer cognitive performance. For women low in public self-consciousness, stress levels and cognitive performance were unrelated to displacement behaviour. Our findings indicate that public self-consciousness is associated with both the expression of displacement behaviour and how such behaviour mediates responses to social stress.

  20. Determining Fault Geometries From Surface Displacements

    NASA Astrophysics Data System (ADS)

    Volkov, D.; Voisin, C.; Ionescu, I. R.

    2017-02-01

    We introduce a new algorithm for determining the geometry of active parts of faults. This algorithm uses surface measurements of displacement fields and local modeling of the Earth's crust as a half-space elastic medium. The numerical method relies on iterations alternating non-linear steps for recovering the geometry and linear steps for reconstructing slip fields. Our algorithm greatly improves upon past attempts at reconstructing fault profiles. We argue that these past attempts suffered from either the restrictive assumption that the geometry of faults can be derived using only uniformly constant slips or that they relied on arbitrary assumptions on the statistics of the reconstruction error. We test this algorithm on the 2006 Guerrero, Mexico, slow slip event (SSE) and on the 2009 SSE for the same region. These events occurred on a relatively well-known subduction zone, whose geometry was derived from seismicity and gravimetric techniques, see Kostoglodov et al. (Geophys Res Lett 23(23):3385-3388, 1996), Pardo and Suarez (J Geophys Res 100(B7):357-373, 1995), Singh and Pardo (Geophys Res Lett 20(14):1483-1486, 1993), so our results can be compared to known benchmarks. Our derived geometry is found to be consistent with these benchmarks regarding dip and strike angles and the positioning of the North American Trench. In addition, our derived slip distribution is also consistent with previous studies (all done with an assumed fixed geometry), see Larson et al. (Geophys Res Lett 34(13), 2007), Bekaert et al. (J Geophys Res: Solid Earth 120(2):1357-1375, 2015), Radiguet et al. (Geophys J Int 184(2):816-828, 2011, J Geophys Res 2012), Rivet et al. (Geophys Res Lett 38(8), 2011), Vergnolle et al. (J Geophys Res: Solid Earth 115(B8), 2010), Walpersdorf et al. Geophys Res Lett 38(15), 2011), to name a few. We believe that the new computational inverse method introduced in this paper holds great promise for applications to blind inversion cases, where both geometry and