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1

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

NASA Astrophysics Data System (ADS)

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

Buschauer, Robert

2014-10-01

2

Displacement-sensitive organic field effect transistor  

Microsoft Academic Search

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

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

2012-01-01

3

Displacement-sensitive organic field effect transistor  

Microsoft Academic Search

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

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

2011-01-01

4

Fast Image Upsampling via the Displacement Field.  

PubMed

In this paper, we present a fast image upsampling method within a two-scale framework to ensure the sharp construction of upsampled image for both large-scale edges and small-scale structures. In our approach, the low-frequency image is recovered via a novel sharpness preserving interpolation technique based on a well-constructed displacement field, which is estimated by a cross-resolution sharpness preserving model. Within this model, the distances of pixels on edges are preserved, which enables the recovery of sharp edges in the high-resolution result. Likewise, local high-frequency structures are reconstructed via a sharpness preserving reconstruction algorithm. Extensive experiments show that our method outperforms current state-of-the-art approaches, based on quantitative and qualitative evaluations, as well as perceptual evaluation by a user study. Moreover, our approach is very fast so as to be practical for real applications. PMID:25265631

Wang, Lingfeng; Wu, Huaiyu; Pan, Chunhong

2014-12-01

5

BLOCK DISPLACEMENT METHOD FIELD DEMONSTRATION AND SPECIFICATIONS  

EPA Science Inventory

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

6

Articular disk displacement of TMJ due to trauma.  

PubMed

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

Goddard, G

1993-07-01

7

Viscoelastic displacement and gravity changes due to point magmatic intrusions in a gravitational layered solid earth  

NASA Astrophysics Data System (ADS)

We present a method for the computation of time-dependent geodetic and geophysical signatures (deformation, potential and gravity changes) due to magmatic intrusions in a layered viscoelastic-gravitational medium. This work is an extension of a deformation model previously developed to compute effects due to volcanic loading in an elastic gravitational layered media. The model assumes a planar earth geometry, useful for near field problems, and consists of welded elastic and viscoelastic layers overlying a viscoelastic half-space. Every layer can either be considered elastic or viscoelastic. The intrusion (treated as a point source) can be located at any depth, in any of the layers or in the half-space. Several examples of theoretical computations for different media are also presented. We have found that, in line with previous results obtained by other authors, introducing viscoelastic properties in all or part of the medium can extend the effects (displacements, gravity changes, etc.) considerably and therefore lower pressure increases are required to model given observed effects. The viscoelastic effects seem to depend mainly on the rheological properties of the layer (zone) where the intrusion is located, rather than on the rheology of the whole medium. We apply our model to the 1982-1984 uplift episode at Campi Flegrei, modelling simultaneously the observed vertical displacement and gravity changes. The results clearly show that for a correct interpretation of observed effects it is necessary to include the gravitational field in the anelastic theoretical models. This factor can change the value and pattern of time-dependent deformation as well as the gravity changes, explaining cases of displacement without noticeable gravity changes or vice versa, cases with uplift and incremental gravity values, and other cases. The combination of displacement and gravity changes is found to be especially effective in constraining the possible characteristics of the magmatic intrusion as well as the rheology of the medium surrounding it.

Fernández, José; Tiampo, Kristy F.; Rundle, John B.

2001-07-01

8

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

9

Strong-field physics: Displaced creation  

NASA Astrophysics Data System (ADS)

The ionization of atoms and molecules by strong laser fields has become a core technique in modern laser physics. Now, the electrons emerging from ionized molecules are shown to exhibit a memory of the ionization process, resulting in a spatial phase that may influence the interpretation of imaging data.

Küpper, Jochen

2014-08-01

10

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

NASA Astrophysics Data System (ADS)

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

Yang, Reng-cai

2014-05-01

11

Near-field beam displacement at surface plasmon resonance  

NASA Astrophysics Data System (ADS)

A finite-size beam exciting a surface plasmon polariton (SPP) in a prism coupling configuration experiences an in-plane displacement that can be used for the characterization of plasmonic components by means of near-field optical microscopy. We first demonstrate experimentally the existence of this displacement by taking near-field images of finite-width metal strips. Next, the properties of this shift are analyzed in detail. We investigate the dynamic of the near-field shift for an incident Gaussian beam as a function of illumination conditions. For beams with a narrow spectrum, we propose a straightforward derivation showing that the displacement depends on the average angle of incidence according to a Lorentzian law characteristic of the SPP resonance. For smaller beams with typical sizes of an order or smaller than the plasmon damping distance, we give a heuristic expression relating the beam displacement to the amount of incident energy that can couple to the SPP mode. By using an analogy with tunneling experiments through a dielectric barrier, we demonstrate a direct-space analog of the Hartman effect. Finally we show that the beam displacement is a convenient parameter that can be used to optimize SPP mode excitation in plasmonic waveguiding geometries.

Weeber, J.-C.; Colas-Des-Francs, G.; Bouhelier, A.; Dereux, A.

2011-03-01

12

Force-free magnetic fields - Generating functions and footpoint displacements  

NASA Technical Reports Server (NTRS)

This paper presents analytic and numerical calculations that explore equilibrium sequences of bipolar force-free magnetic fields in relation to displacments of their magnetic footpoints. It is shown that the appearance of magnetic islands - sometimes interpreted as marking the loss of equilibrium in models of the solar atmosphere - is likely associated only with physically unrealistic footpoint displacements such as infinite separation or 'tearing' of the model photosphere. The work suggests that the loss of equilibrium in bipolar configurations, sometimes proposed as a mechanism for eruptive solar events, probably requires either fully three-dimensional field configurations or nonzero plasma pressure. The results apply only to fields that are strictly bipolar, and do not rule out equilibrium loss in more complex structures such as quadrupolar fields.

Wolfson, Richard; Verma, Ritu

1991-01-01

13

Displacement and stress fields around rock fractures opened by irregular overpressure variations  

NASA Astrophysics Data System (ADS)

Many rock fractures are entirely driven open by fluids such as ground water, geothermal water, gas, oil, and magma. These are a subset of extension fractures (mode I cracks; e.g., dikes, mineral veins and joints) referred to as hydrofractures. Field measurements show that many hydrofractures have great variations in aperture. However, most analytical solutions for fracture displacement and stress fields assume the loading to be either constant or with a linear variation. While these solutions have been widely used, it is clear that a fracture hosted by heterogeneous and anisotropic rock is normally subject to loading that is neither constant nor with a linear variation. Here we present new general solutions for the displacement and stress fields around hydrofractures, modelled as two-dimensional elastic cracks, opened by irregular overpressure variations given by the Fourier cosine series. Each solution has two terms. The first term gives the displacement and stress fields due to the average overpressure acting inside the crack; it is given by the initial term of the Fourier coefficients expressing the overpressure variation. The second term gives the displacement and stress fields caused by the overpressure variation; it is given by general terms of the Fourier coefficients and solved through numerical integration. Our numerical examples show that the crack aperture variation closely reflects the overpressure variation. Also, that the general displacement and stress fields close to the crack follow the overpressure variation but tend to be more uniform far from the crack. The present solutions can be used to estimate the displacement and stress fields around any fluid-driven crack, that is, any hydrofracture, as well as its aperture, provided the variation in overpressure can be described by Fourier series. The solutions add to our understanding of local stresses, displacements, and fluid transport associated with hydrofractures in the crust.

Kusumoto, Shigekazu; Gudmundsson, Agust

2014-05-01

14

Mechanisms of In Situ Rock Displacement During Hypervelocity Impact: Field and Microscopic Observations  

NASA Astrophysics Data System (ADS)

The nature of rock deformation due to hypervelocity impact is discussed, especially with regard to the larger terrestrial structures (e.g., Sudbury, Vredefort, Manicouagan). Based on field observations and thin section microscopy, evidence is presented for two end-members of rock response to extreme strain rates: (1) bulk deformation, due to pervasive fracture generation and ensuing micro-displacement with melting; (2) localized large-displacement faulting, accompanied by friction melt generation (pseudotachylytes). There is no evidence for bulk "fluidization" at the thin section scale, except where bulk melting has occurred during impact melt sheet generation, wherein truly fluid (igneous) rocks are formed.

Spray, J. G.

2003-02-01

15

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

16

PREDICTION OF SURFACE SETTLEMENT DUE TO THE DISPLACEMENT OF SOFT ZONES  

SciTech Connect

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.

Li, W

2008-03-03

17

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

18

First-principles modeling of ferroelectric capacitors via constrained displacement field calculations  

Microsoft Academic Search

First-principles modeling of ferroelectric capacitors presents several technical challenges due to the coexistence of metallic electrodes, long-range electrostatic forces, and short-range interface chemistry. Here we show how these aspects can be efficiently and accurately rationalized by using a finite-field density-functional theory formalism in which the fundamental electrical variable is the displacement field D . By performing calculations on model Pt\\/BaTiO3\\/Pt

Massimiliano Stengel; David Vanderbilt; Nicola A. Spaldin

2009-01-01

19

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

USGS Publications Warehouse

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.

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

2006-01-01

20

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

SciTech Connect

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.

Brower, K.L.

1997-09-01

21

Short-time distribution of particle displacements due to swimming microorganisms  

E-print Network

The experiments of Leptos et al. [Phys. Rev. Lett. 103,198103 (2009)] show that the displacements of small particles affected by swimming microorganisms achieve a non-Gaussian distribution, which nevertheless scales diffusively. We use a simple model where the particles undergo repeated 'kicks' due to the swimmers to explain the shape of the distribution as a function of the volume fraction of swimmers. The net displacement is determined by the self-convolution of the drift function caused by one swimmer, and by a Poisson distribution for the frequency of interactions. The only adjustable parameter is the strength of the stresslet term in our spherical squirmer model. The effective diffusivity predicted by the model is consistent with the experiments, with no further parameter adjustments. The diffusive scaling appears to be due to the particular form of the drift function, and is not statistical in origin. The model also suggests that the scaling disappears for longer times, when the swimmers undergo signifi...

Thiffeault, Jean-Luc

2014-01-01

22

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

23

Processing discontinuous displacement fields by a spatio-temporal derivative technique  

NASA Astrophysics Data System (ADS)

In this paper, a digital image correlation (DIC) method coupling cross-correlation with spatio-temporal differential techniques was proposed for assessing discontinuous displacement fields. The accuracy and robustness of the algorithm was assessed on a set of numerical tests by processing computer generated speckled-pattern images. Fracture mechanical tests in mode I were considered, in which both in-plane and out-of-plane rigid-body movements were taken into account. The ability for recovering the analytical asymptotic displacement field in mode I was analysed, and stress intensity factor, crack opening displacement and crack tip location were used as quantitative parameters for validation purposes. Throughout these tests, the results obtained with the proposed method were systematically compared to the ones from Aramis DIC-2D commercial code. Globally, the results computed from both methods are in good agreement with reference values. However, due to the high spatial resolution (point-wise characteristic), a better matching of the displacements in the neighbour of discontinuities could be obtained by the proposed method.

Sousa, A. M. R.; Xavier, J.; Morais, J. J. L.; Filipe, V. M. J.; Vaz, M.

2011-12-01

24

Short-time distribution of particle displacements due to swimming microorganisms  

E-print Network

The experiments of Leptos et al. [Phys. Rev. Lett. 103,198103 (2009)] show that the displacements of small particles affected by swimming microorganisms achieve a non-Gaussian distribution, which nevertheless scales diffusively. We use a simple model where the particles undergo repeated 'kicks' due to the swimmers to explain the shape of the distribution as a function of the volume fraction of swimmers. The net displacement is determined by the self-convolution of the drift function caused by one swimmer, and by a Poisson distribution for the frequency of interactions. The only adjustable parameter is the strength of the stresslet term in our spherical squirmer model. The effective diffusivity predicted by the model is consistent with the experiments, with no further parameter adjustments. The diffusive scaling appears to be due to the particular form of the drift function, and is not statistical in origin. The model also suggests that the scaling disappears for longer times, when the swimmers undergo significant reorientation.

Jean-Luc Thiffeault

2014-08-20

25

Removing the image-doubling in shearography by reconstruction of the displacement field  

Microsoft Academic Search

In shearography a doubled speckle pattern is used to measure an approximation to the displacement derivative of a deformed object. In this paper a method is presented that reconstructs the original displacement field from a shearographic recording. The phase value representing the displacement of a point is calculated by adding the phase values of certain points in the shearogram. Applying

Stephan Waldner

1996-01-01

26

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

PubMed Central

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

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

2008-01-01

27

A Demographic Profile of Displaced Farmers Due to Economically Depressed Times.  

ERIC Educational Resources Information Center

The socioeconomic characteristics of a generalizable sample of recently displaced farm households in North Dakota were compared with characteristics of a random sample of farmers who were still operating their enterprises in 1985. Data were collected in 1986 by phone and mail surveys from 162 displaced and 752 active farmers. The farm…

Rathge, Richard W.; And Others

28

Field management of displaced ankle fractures: techniques for successful reduction.  

PubMed

Ankle fracture/dislocations are generally low-energy injuries most commonly seen in older adults. Prompt reduction is indicated when evacuation to definitive care would be prolonged or neurovascular compromise to the foot is suspected. Reduction restores neurovascular integrity, realigns joint contact surfaces, reduces pain, and decreases soft-tissue edema. The hematoma block is a safe, easy, and effective method of obtaining adequate anesthesia to allow manipulation of displaced fractures. Although most commonly used for distal radius fractures, the hematoma block has been demonstrated to be as effective as conscious sedation for ankle reduction analgesia. Use of hematoma block is ideal for the wilderness setting because it requires few supplies, is easy to perform, and is effective. Quigley's traction consists of suspending the injured leg in a tubular fabric sling to allow gradual relaxation of deforming muscle forces and eventual reduction of a displaced ankle. For those displaced ankle fractures that are not amenable to reduction by direct manipulation, Quigley's traction applied after hematoma block may allow successful reduction. Improvised Quigley's traction can be built in a wilderness setting using available clothing. After successful reduction, fractured ankles should be adequately stabilized and the affected extremity should be kept nonweight bearing. The hematoma block and improvised Quigley's traction are valuable skills for the wilderness medical provider and may facilitate a successful and relatively pain-free reduction of dislocated ankle fractures in a wilderness setting. PMID:19364168

Dean, D Brian

2009-01-01

29

Two wavelength simultaneous DSPI and DSP for 3D displacement field measurements  

Microsoft Academic Search

A novel optical system is proposed that implements digital speckle pattern interferometry (DSPI) and digital speckle photography (DSP) simultaneously using two wavelength illumination of an object for simultaneous measurement of all three components of the displacement vector field. A collimated red light illuminates both the object and a reference surface in a DSPI configuration which is sensitive to out-of-plane displacement

Basanta Bhaduri; C. J. Tay; C. Quan; H. Niu; Mikael Sjödahl

2011-01-01

30

A Quantitative Approach for Estimating Coseismic Displacements in the Near Field from Strong-Motion Accelerographs  

E-print Network

records. Introduction The determination of coseismic displacements from strong-motion accelerographs A Quantitative Approach for Estimating Coseismic Displacements in the Near Field from Strong-Motion accelerations recorded by strong-motion seismometers are often contaminated by baseline offsets that prevent

Cerveny, Vlastislav

31

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

32

On the Derivation of Coseismic Displacement Fields Using Differential Radar Interferometry: The Landers Eartquake  

NASA Technical Reports Server (NTRS)

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

Zebker, H.; Rosen, P.

1994-01-01

33

Responses of three invasive aquatic macrophytes to nutrient enrichment do not explain their observed field displacements  

Microsoft Academic Search

In some eutrophic inland waters the invasive aquatic macrophyte Elodea canadensis has been displaced by the morphologically similar species Elodea nuttallii and subsequently E. nuttallii by Lagarosiphon major. We investigated whether differences in the responses of these species and their associated epiphytic floras to five nutrient loadings in the range 30–480?gL?1P and 0.21–3.36mgL?1N could explain their observed field displacements. The

Cassandra S. James; John W. Eaton; Keith Hardwick

2006-01-01

34

Rapid displacement of a monoecious plant lineage is due to pollen swamping by a dioecious relative.  

PubMed

Interspecific hybridization is recognized as a potentially destructive process that represents a major threat to biodiversity. The rate of population displacement by hybridization can be rapid, but underlying mechanisms are often obscure. One hypothesis is that a species may be driven to extinction by interspecific gene flow, or pollen swamping, when hybrids are inviable or sterile. Here, we document the rapid movement of two zones of contact between monoecious hexaploid and dioecious diploid populations of the wind-pollinated plant Mercurialis annua (Euphorbiaceae) in northeastern and northwestern Spain, where diploids have displaced hexaploids by about 80 and 200 km, respectively, over a period of four decades. By using experimental mating arrays, we show that hybridization is highly asymmetrical in favor of the diploids, mainly because they disperse substantially more pollen, as expected in a comparison between an obligate outcrosser and a facultative selfer. Self-fertilization, which is expected to reduce the proportion of sterile hybrids produced in mixed ploidy populations, allowed the hexaploids to avoid the effects of pollen swamping only slightly, and in a density-dependent manner. Our results thus provide a mechanistic explanation for the rapid movement of both contact zones of M. annua in Spain. PMID:16713956

Buggs, Richard J A; Pannell, John R

2006-05-23

35

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

Microsoft Academic Search

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

A. ZEBKER; PAUL ROsEN

1961-01-01

36

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

PubMed

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

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

2014-04-21

37

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

SciTech Connect

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

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

2013-05-15

38

Displacement field analysis based on the combination digital speckle correlation method with radial basis function interpolation.  

PubMed

The digital speckle correlation method (DSCM) has been widely used to resolve displacement and deformation gradient fields. The computational time and the computational accuracy are still two challenging problems faced in this area. In this paper, we introduce the radial basis function (RBF) interpolation method to DSCM and propose a method for displacement field analysis based on the combination of DSCM with RBF interpolation. We test the proposed method on two computer-simulated and two experimentally obtained deformation measurements and compare it with the widely used Newton-Raphson iteration (NR method). The experimental results demonstrate that our method performs better than the NR method in terms of both quantitative evaluation and visual quality. In addition, the total computational time of our method is considerably shorter than that of the NR method. Our method is particularly suitable for displacement field analysis of large regions. PMID:20733625

Tang, Chen; Wang, Linlin; Yan, Si; Wu, Jian; Cheng, Liyan; Li, Cancan

2010-08-20

39

Field performance of the Walker Branch throughfall displacement experiment  

SciTech Connect

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

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

1994-10-06

40

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

41

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

NASA Astrophysics Data System (ADS)

We propose a multiscale approach to determine the displacement field by digital image correlation. The displacement field is first estimated on a coarse resolution image and progressively finer details are introduced in the analysis as the displacement is more and more securely and accurately determined. Such a scheme has been developed to increase the robustness, accuracy, and reliability of the image-matching algorithm. The procedure is used on two different types of examples. The first one deals with a representative image that is deformed precisely and purposefully to assess the intrinsic performances. In particular, the maximum measurable strain is determined. The second case deals with a series of pictures taken during compression experiments on mineral-wool samples. The different steps of the procedure are analyzed and their respective role is assessed. Both reflection and transmission images are tested.

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

2002-11-01

42

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

PubMed

We propose a multiscale approach to determine the displacement field by digital image correlation. The displacement field is first estimated on a coarse resolution image and progressively finer details are introduced in the analysis as the displacement is more and more securely and accurately determined. Such a scheme has been developed to increase the robustness, accuracy, and reliability of the image-matching algorithm. The procedure is used on two different types of examples. The first one deals with a representative image that is deformed precisely and purposefully to assess the intrinsic performances. In particular, the maximum measurable strain is determined. The second case deals with a series of pictures taken during compression experiments on mineral-wool samples. The different steps ofthe procedure are analyzed and their respective role is assessed. Both reflection and transmission images are tested. PMID:12440536

Hild, François; Raka, Bumedijen; Baudequin, Maud; Roux, Stéphane; Cantelaube, Florence

2002-11-10

43

Measuring near field coseismic displacements from SAR images: Application to the Landers earthquake  

Microsoft Academic Search

We describe a procedure to compute SAR interferograms based on the compensation of the images' misregistrations due to the ground deformation and on a specific adaptive filtering to improve the SNR in the measurement where displacement gradients are large. Applied to the Landers earthquake case, the registration reduces the phase noise by 20° (rms) near the fault and the interferogram

Rémi Michel; Jean-Philippe Avouac; Jean Taboury

1999-01-01

44

Measuring displacement fields by cross-correlation and a differential technique: experimental validation  

NASA Astrophysics Data System (ADS)

A digital image correlation (DIC) algorithm for displacement measurements combining cross-correlation and a differential technique was validated through a set of experimental tests. These tests consisted of in-plane rigid-body translation and rotation tests, a tensile mechanical test, and a mode I fracture test. The fracture mechanical test, in particular, was intended to assess the accuracy of the method when dealing with discontinuous displacement fields, for which subset-based image correlation methods usually give unreliable results. The proposed algorithm was systematically compared with the Aramis® DIC-2D commercial code by processing the same set of images. When processing images from rigid-body and tensile tests (associated with continuous displacement fields), the two methods provided equivalent results. When processing images from the fracture mechanical test, however, the proposed method obtained a better qualitative description of the discontinuous displacements. Moreover, the proposed method gave a more reliable estimation of both crack length and crack opening displacement of the fractured specimen.©

Xavier, José; Sousa, António M. R.; Morais, José J. L.; Filipe, Vitor M. J.; Vaz, Mario

2012-04-01

45

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

PubMed

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. PMID:12804287

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

2002-05-15

46

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

USGS Publications Warehouse

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.

Savage, J. C.

1998-01-01

47

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

Microsoft Academic Search

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

Kh. S. Karimov; T. A. Qasuria

48

Nature and extent of population displacement due to climate change-triggered disasters in the south-western coastal region of Bangladesh  

Microsoft Academic Search

Purpose – Climate change impacts people's life directly or indirectly in several ways and displacement is one such indirect effect. This paper aims to bring this fact to light as Bangladesh is going to face severe problems due to displacement of population predicted by researchers. Design\\/methodology\\/approach – This paper is an outcome of a thorough study of Bogi village in

2011-01-01

49

Surface displacement due to degree-1 loading in reference frames realized by imperfect geodetic networks  

NASA Astrophysics Data System (ADS)

Load-induced geocenter motion has become a crucial factor for maintaining a terrestrial reference frame (TRF) at submillimeter level in near real-time, and for estimates of the variation of the degree-1 gravity field. Realization of the commonly adopted center of figure (CF) frame requires an infinite number of observation sites uniformly distributed over the Earth’s surface. In reality, we can only approximate the idealized CF frame by using a finite number of irregularly distributed sites. We call this approximation the center of network (CN) frame. Irregularities in site distribution alias the response of the spherical Earth to degree-1 surface loading. We develop a new theory to cope with this situation. We show that load-induced geocenter motions in a general CN frame formally split the degenerate degree-1 load Love numbers into harmonic-order dependent, (m = -1, 0, 1). To eliminate the unknown variables contained in their formal expressions, we extend the split-load Love numbers into degree-1 Love matrices, H1, L1, and K1. Useful split-load Love numbers can be defined in what we call the principal frame of loading, analogous to the principal frame of stress. The artificial aliasing caused by irregular site distributions is quantified and clearly visualized in those well-defined split load Love numbers in the principle CN frame. In a detailed case study, we consider a realistic CN frame and its partial decompositions, CNh and CNl, maintained by 99 IGS reference sites. The two partials are found much less aliased then the complete CN frame. Based on synthetic true geocenter motion generated from MIT’s OGCM and the GLDAS hydrology model, a simulated GPS inversion is performed under the scheme of purposely misusing the CN frame as an idealized center of figure frame. Significant biases, by a factor ~2, are produced in the direction, confirming the conjecture that the exceptionally large components obtained from previous inversions of real data are indeed spurious.

Fang, M.; Hager, B. H.

2009-12-01

50

The Contribution of Coseismic Displacements due to Splay Faults Into the Local Wavefield of the 1964 Alaska Tsunami  

NASA Astrophysics Data System (ADS)

The Alaska Earthquake Information Center conducts tsunami inundation mapping for coastal communities in Alaska. For many locations in the Gulf of Alaska, the 1964 tsunami generated by the Mw9.2 Great Alaska earthquake may be the worst-case tsunami scenario. We use the 1964 tsunami observations to verify our numerical model of tsunami propagation and runup, therefore it is essential to use an adequate source function of the 1964 earthquake to reduce the level of uncertainty in the modeling results. It was shown that the 1964 co-seismic slip occurred both on the megathrust and crustal splay faults (Plafker, 1969). Plafker (2006) suggested that crustal faults were a major contributor to vertical displacements that generated local tsunami waves. Using eyewitness arrival times of the highest observed waves, he suggested that the initial tsunami wave was higher and closer to the shore, than if it was generated by slip on the megathrust. We conduct a numerical study of two different source functions of the 1964 tsunami to test whether the crustal splay faults had significant effects on local tsunami runup heights and arrival times. The first source function was developed by Johnson et al. (1996) through joint inversion of the far-field tsunami waveforms and geodetic data. The authors did not include crustal faults in the inversion, because the contribution of these faults to the far-field tsunami was negligible. The second is the new coseismic displacement model developed by Suito and Freymueller (2008, submitted). This model extends the Montague Island fault farther along the Kenai Peninsula coast and thus reduces slip on the megathrust in that region. We also use an improved geometry of the Patton Bay fault based on the deep crustal seismic reflection and earthquake data. We propagate tsunami waves generated by both source models across the Pacific Ocean and record wave amplitudes at the locations of the tide gages that recorded the 1964 tsunami. As expected, the two sources produce very similar waveforms in the far field that are also in good agreement with the tide gage records. In order to study the near-field tsunami effects, we will construct embedded telescoping bathymetry grids around tsunami generation area to calculate tsunami arrival times and sea surface heights for both source models of the 1964 earthquake, and use available observation data to verify the model results.

Suleimani, E.; Ruppert, N.; Fisher, M.; West, D.; Hansen, R.

2008-12-01

51

The tidal displacement field at Earth's surface determined using global GPS observations  

NASA Astrophysics Data System (ADS)

We investigate the 3-D tidal displacement field on Earth's surface recorded globally by 456 continuous global positioning system (GPS) stations of IGS spanning 1996-2011, for eight principal diurnal and semidiurnal tidal constituents. In-phase and quadrature amplitudes of the residual tidal displacements, after removal of an a priori body tide model, are estimated using the precise point positioning (PPP) technique on the daily GPS data; the resultant daily estimates are combined to derive final estimates for each tide at each station. The results are compared with the predictions of eight recent global ocean tide models, separately for coastal (307) and inland (149) stations. We show that GPS can provide tidal displacement estimates accurate to the level of 0.12 mm (horizontal) and 0.24 mm (vertical) for the lunar-only constituents (M2, N2, O1, and Q1) and less favorably for solar-related tidal constituents (S2, K2, K1, and P1), although improved by ambiguity resolution. Most recent ocean tide models fit the GPS estimates equally well on the global scale but do not agree well between them in certain coastal areas, especially for the vertical displacements, suggesting the existence of model uncertainties near shallow seas. The tidal residuals for the inland stations after removing both body tides and ocean tidal loading (OTL) furthermore show clear continental-scale spatial coherence, implying deficiencies of the a priori body tide modeling in catching lateral heterogeneity in elastic as well as inelastic properties in the Earth's deep interior. We assert that the GPS tidal displacement estimates now achieve sufficient accuracy to potentially provide constraints on the Earth's structure.

Yuan, Linguo; Chao, Benjamin Fong; Ding, Xiaoli; Zhong, Ping

2013-05-01

52

The displacement field in the vibration analysis of laminated thick plates  

SciTech Connect

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.

Ohta, Yoshiki; Narita, Yoshihiro [Hokkaido Inst. of Tech., Hokkaido (Japan). Dept. of Mechanical Engineering

1995-11-01

53

Late Cenozoic displacement-field partitioning in the western Great Basin  

SciTech Connect

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.

Oldow, J.S. (Rice Univ., Houston, TX (United States). Dept. of Geology and Geophysics)

1993-04-01

54

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

NASA Astrophysics Data System (ADS)

Recent studies on the mechanism of occurrence of large scale submarine landslides focuses mostly on the generation of excess pore pressure due to rapid sedimentation rate in certain environment, rather than gasification of methane hydrates (MH), although MH gasification could contribute to the landslides in the transgresssion period. However, at the 1896 Meiji Sanriku-oki Earthquake which caused serious tsunami disaster in the Tohoku region of Japan, there are witnesses of large-scale flame which were of possibly ejected dissolved methane hydrates (MH) from sea floor. We employed the stress-controlled undrained ring shear apparatuses have been developed at Disaster Prevention Research Institute, Kyoto University to reproduce shear behavior of the dry sand-dry ice mixture under constant normal stress and shear speed control tests using the latest ring shear apparatus. Tested sample was mixture of silica sands and dry-ice pellets (frozen carbon-dioxide). Those mixtures are often used for studying the mechanism of the methane hydrates in laboratories because no explosion protection facility is required. Through three series of tests, we obtained following results. (1) Rate Effect: The samples were tested under stepped shear speed ranging from 0.02 cm/s to 10 cm/s. The obtained excess pore-pressure ratio relationship, which is defined as the ratio of excess pore air pressure to initial effective stress, These results clearly shows positive speed dependency, especially for 1 cm/s and 10 cm/s. This phenomenon could be explained by the "sliding surface liquefaction." (2) Difference between internal and external friction: Based on the published observation of the sliding surface and the BSR, the sliding surface can be generated in the boundary of the MH layer. Tests to compare the internal friction and external friction between sand layers reveals that the behaviour of the both conditions have no significant difference. (3) Shear behaviour under cyclic loading condition: 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.

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

2012-04-01

55

Influence of the free-layer domain structure on domain-wall displacing type field sensors  

NASA Astrophysics Data System (ADS)

We propose a giant magnetoresistive sensor which utilizes the shifting of oscillatory domain walls to detect the external field along the easy axis. For this type of sensor the domains in the soft magnetic free layer play an import role and the sensor output is mainly determined by the domain-wall displacement. Domain structures in various micro-fabricated soft magnetic patterns have been investigated and two typical free-layer materials were selected to fabricate the sensor devices. The domain-wall displacing (DWD) type sensor with a 10 nm Ni80Fe20 free layer shows a higher field sensitivity than that with CoFeB, however the sensor output becomes saturated when the external field (Hex) > 0.4 Oe. For the sensor which has a 10 nm (Co90Fe10)92B8 free layer, the sensor output is linear even as Hex increases to 2.6 Oe. In addition, the sensors were operated under the magnetization rotation mode to compare the sensor outputs with the DWD mode. When the sensors were operated under the DWD mode a field sensitivity of at least two times higher was achieved.

Wang, G. A.; Masuda, Y.; Kato, T.; Iwata, S.

2011-04-01

56

A case of facial deformity due to bilateral developmental maxillary cheek teeth displacement in an adult horse  

PubMed Central

A 7-year-old mare presented with facial deformities associated with oral discomfort and weight loss was found to have bilateral, palatal, developmental displacements of the maxillary 08s, with secondary diastema. Following repulsion of both displaced teeth, the horse regained weight and resumed training. Bony deformities remained visible 9 mo after discharge. PMID:21197210

Robert, Mickael P.; Gangl, Monika C.; Lepage, Olivier M.

2010-01-01

57

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

PubMed Central

Background Spinal cord compression and associate neurological impairment is rare in patients with scoliosis and neurofibromatosis. Common reasons are vertebral subluxation, dislocation, angulation and tumorous lesions around the spinal canal. Only twelve cases of intraspinal rib dislocation have been reported in the literature. The aim of this report is to present a case of rib penetration through neural foramen at the apex of a scoliotic curve in neurofibromatosis and to introduce a new clinical sign for its detection. Methods A 13-year-old girl was evaluated for progressive left thoracic kyphoscoliotic curve due to a type I neurofibromatosis. Clinical examination revealed multiple large thoracic and abdominal "cafe-au-lait" spots, neurological impairment of the lower limbs and the presence of a thoracic gibbous that was painful to pressure at the level of the left eighth rib (Painful Rib Hump). CT-scan showed detachment and translocation of the cephalic end of the left eighth rib into the adjacent enlarged neural foramen. The M.R.I. examination of the spine showed neither cord abnormality nor neurogenic tumor. Results The patient underwent resection of the intraspinal mobile eighth rib head and posterior spinal instrumentation and was neurologically fully recovered six months postoperatively. Conclusion Spine surgeons should be aware of intraspinal rib displacement in scoliotic curves in neurofibromatosis. Painful rib hump is a valuable diagnostic tool for this rare clinical entity. PMID:16774682

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

2006-01-01

58

Reconstruction of temperature and displacement fields in satellite sandwich panels based on integrated fiber optic sensors  

NASA Astrophysics Data System (ADS)

Large satellites are equipped with hundreds of sensors for temperature measurement. The large amount of sensors is expensive in terms of integration effort and mass in the case conventional sensors are used. In this article an integrated fiber optic temperature sensor network for the hot spot detection on satellite sandwich panels is introduced. The developed sensor system is integrated with only negligible mechanical impact. It is electro-magnetic immune and decoupled from mechanical loads. In addition to monitoring hotspots, the number and aerial density allows a reliable reconstruction of temperature and displacement fields.

Rapp, Stephan; Baier, Horst

2009-03-01

59

Displacement effect in strong-field atomic ionization by an XUV pulse  

NASA Astrophysics Data System (ADS)

We study strong-field atomic ionization driven by an XUV pulse with a nonzero displacement, the quantity defined as the time integral of the pulse vector potential taken over the pulse duration. The use of such pulses may lead to an extreme sensitivity of the ionization process to subtle changes of a driving XUV pulse, in particular, the ramp-on and off profile and the carrier envelope phase. We illustrate this sensitivity for atomic hydrogen and lithium driven by few-femtosecond XUV pulses with intensity in the 1014W/cm2 range. The observed effect is general and should modify strong-field ionization of any atom or molecule, provided the ionization rate is sufficiently high.

Ivanov, Igor A.; Kheifets, Anatoli S.; Bartschat, Klaus; Emmons, John; Buczek, Sean M.; Gryzlova, Elena V.; Grum-Grzhimailo, Alexei N.

2014-10-01

60

Cosmological electromagnetic fields due to gravitational wave perturbations Mattias Marklund*  

E-print Network

Cosmological electromagnetic fields due to gravitational wave perturbations Mattias Marklund that the coupling between gravitational waves and a weak magnetic test field can generate electromagnetic waves. We show that this coupling leads to an initial pulse of electromagnetic waves whose width and amplitude

Dunsby, Peter

61

Dynamic model of micropolar elastic thin plates with independent fields of displacements and rotations  

NASA Astrophysics Data System (ADS)

A general model of dynamic bending of isotropic micropolar elastic thin plates with independent fields of displacements and rotations is presented. The model has been justified asymptotically based on the solutions for special cases subject to simplifying assumptions. The model incorporates transverse shear deformations. Neglecting transverse shear, a model of the dynamics of micropolar elastic thin plates is also constructed. Then, we study free and forced oscillations and derive the natural frequencies, the amplitudes of the forced oscillations and the resonance conditions for micropolar elastic hinge-supported rectangular and circular plates. Finally, the basic characteristic features of micropolar plates are numerically analysed for different values of various elastic and inertial constants of the micropolar material.

Sargsyan, A. H.; Sargsyan, S. H.

2014-09-01

62

Full-field displacement measurement by double symmetrical illumination through reflection holograms  

NASA Astrophysics Data System (ADS)

Compact and stable phase stepping interferometer for shape and full field displacement measurement in static and in "real time" operation mode is presented. Double symmetrical illumination of the object in two orthogonal planes with diode lasers, emitting in NIR (790 nm and 830 nm), through a four-exposure reflective holographic optical element (Denisiyk's volume reflection holograms of a reference plane) is applied. Phase stepping is introduced simply by precise increments of the diode lasers current. The proposed system is very stable against external noise, produced by vibrations, temperature changes, air flows, as well as against the influence of object's "rigid body" motion, as the compact and low weight interferometer can be stably fixed directly onto the measured construction.

Sainov, V.; Baldjiev, A.; Stoykova, E.

2013-06-01

63

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

Microsoft Academic Search

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

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

2005-01-01

64

Determination of vertical displacements over the coastal area of Korea due to the ocean tide loading using GPS observations  

Microsoft Academic Search

This paper describes the GPS applicability for detecting the vertical displacements of ground stations caused by ocean tide loading effects. An experiment was carried out using 12 permanent GPS stations located in the coastal area of Korea using data in the period 1 July until 26 August 2003. The relative height differences were calculated from hourly DGPS data processing based

Hong-Sic Yun; Dong-Ha Lee; Dong-Seob Song

2007-01-01

65

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

E-print Network

mixed-mode data 38 8 Stress-field parameters calculated from theoretical Mode I data with a 0. 0005 inch translation in the z direction 40 9 Stress-field parameters calculated from experimental Mode I data 54 vn LIST OF FIGURES FIGURE Page 1... ? (1 + v)(n + 2) sin 0 sin(n ? 2)0 ] "n+2 CO T m+1 + P Bm [2cos(m+ 1)0 ? (1+ v)(m+ 1) sin 0sinm0] m+1 r +z 1 Evt: g A& y [2 sin(n + &)0 ? (1 + v)(n + &) sin 0 cos(n ? &)0] "n+2' OQ T m+1 + P Bm [(1 ? v) sin(m+ 1)0 ? (1+ v)(m+ 1)sin0cosn8] tn+ 1...

Matsumoto, Kay Yuri

2012-06-07

66

Monte Carlo Analysis of Correlation of Displacement Damage Due to Neutrons, Protons, Electrons and Gamma Ray in Microelectronic Devices  

NASA Astrophysics Data System (ADS)

In this paper, the correlation of displacement damage produced by neutrons, protons, electrons and gamma ray in microelectronic devices is studied quantitatively by Monte Carlo method on basis of NIEL concept. The physical model and processes of NIEL caused by different particles with different energies are discussed and the computer programs have been set up to calculate the NIEL of neutrons, protons, electrons and gamma ray in silicon. The calculated results agree well with the typical values reported in literatures.

Xing, Huang Liu; Bin, Chen Shi; Sheng, Chen Yu

67

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

Microsoft Academic Search

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

Peter Breuer; Tadeusz Chmielewski; Piotr Górski; Eduard Konopka

2002-01-01

68

Some thoughts on error-contributions to reconstruct 3D coseismic displacement field using the model of combining multiple independent InSAR  

NASA Astrophysics Data System (ADS)

Interferometric Synthetic Aperture Radar (InSAR) has proved an immensely powerful tool in studying earthquakes with millimetre-scale accuracy at a high spatial resolution. However, each interferogram records only the component of displacement in the direction of the satellite line of sight (LOS). Thus previous InSAR studies of displacement due to earthquakes were generally limited to one or two components of the surface displacement field. Three- dimensional (3D) surface displacement maps can provide a more comprehensive understanding of source geometry associated with earthquake. By combining interferograms from multiple look angles, it is possible to constrain the three-dimensional components of displacement [Jung et al., 2011; Wright, et al., 2004; Hong et al., 2010]. In this work, we take 2008 Gaize Ms6.9 earthquake (Tibet) for example, derive LOS surface displacement from several paths of ENVISAT ASAR images (Image mode: Track 348, descending pass; Track 341, 427, and 155, ascending pass. ScanSAR mode: Track 341, 112, 155, and 384, ascending pass), and reconstruct the 3D coseismic displacement field with the model named multiple independent InSAR with different viewing angles. Because it is difficult to distinguish tectonic signal from phase noise (eg. orbital errors, atmospheric errors, and unwrapping errors), these error-contributions may be propagated to the 3D coseismic components (vertical, north, east). In addition, for ENVISAT ASAR, it is worth notice that the radar antenna is fixed with respect to the current satellite, which may lead to different LOS observations with nearly identical viewing angles in parallel passes. Thus, when inverting 3D components with least square solution, InSAR observation errors may be magnified by the ill-conditioned system of equations in the solution. Although the ill-conditioned system of equations may result in bad solution, some InSAR observation errors can be detected by the system. In our study, we will introduce the condition number (cond) of coefficient matrix to evaluate the condition of equation set. Our purposes are: 1) to find above which condition number (critical value) we can detect the observation errors from the equation set; 2) to comprehensive understand how the accuracies of 3D components are affected by ill-conditioned system. According to the answers of these two questions, some optimized algorithm may be proposed to improve the accuracies of reconstructing 3D coseismic displacement field.

Liu, Bin; Zhang, Jingfa; Luo, Yi

2012-07-01

69

Anisotropy in MHD turbulence due to a mean magnetic field  

Microsoft Academic Search

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

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

1983-01-01

70

Anisotropy in MHD turbulence due to a mean magnetic field  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

71

Axial separation of orthogonally polarized focal field components due to a radially polarized beam.  

PubMed

In this paper, we investigate the field distribution in the focal volume of an aberrated radially polarized beam. Using two different forms of the vectorial diffraction theory, we show that the presence of defocus in the beam displaces both the axially and the radially polarized fields parallel to the optical axis of the focusing lens, while the presence of spherical aberration primarily shifts the longitudinally polarized field only. This facilitates axial separation of the two orthogonally polarized field components, resulting in a significant boost to the ratio of the peak longitudinally polarized field to the peak laterally polarized field in the focal plane. We further show that with an appropriate combination of oppositely signed defocus and spherical aberration, the energy density in the focal volume due to the longitudinally polarized field can be caused to peak at the focal plane. The results obtained are expected to be beneficial to the applications requiring a stronger longitudinally polarized focal field relative to the laterally polarized focal field component. PMID:22751392

Boruah, Bosanta R

2012-07-01

72

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

NASA Technical Reports Server (NTRS)

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

Maggiori, D.

1981-01-01

73

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

Microsoft Academic Search

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

James B. Grace; Robert G. Wetzel

1981-01-01

74

Coseismic displacement field of the Wenchuan Ms 8.0 earthquake in 2008 derived using differential radar interferometry  

NASA Astrophysics Data System (ADS)

We used the radar data from satellite ALOS/PALSAR of Japan and D-InSAR technology to derive the coseismic displacement produced by the Wenchuan, China Ms 8.0 earthquake on 12 May 2008. The result shows that the coseismic displacement primarily concentrated in a near-field range about 100km width on both sides of the Yingxiu-Beichuan fault. The incoherent zone about 250km long and 15~35km wide nearby the fault suffered the largest deformation with surface ruptures. The secondary deformed areas are 70km wide on each side of the incoherent zone, where the displacements exhibit a sunk northern wall with maximum -110~120cm and an uplifted southern wall with maximum 120~130cm, respectively. In the far-field range of the fault, displacements are less than 10cm. Using the offset tracking, we found clear rupture traces and coseismic displacement of 3m along the faults. With a model of four fault sections, we retrieved slip distribution on the faults. The inversion result reveals two slips of 10m at depths 5~20km beneath the Yingxiu-Beichuan fault and one slip of 2.3m at depth 5~20km below the Guanxian-Jiangyou fault, respectively. Thrust faulting dominates the southwestern Yingxiu-Beichuan fault and the entire Guanxian-Jiangyou fault, while right-slip is the primary component along the northeastern Yingxiu-Beichuan fault.

Qu, Chunyan; Shan, Xinjian; Zhang, Guohong; Song, Xiaogang; Zhang, Guifang

2010-03-01

75

Prediction of displacement and stress fields of a notched panel with geometric nonlinearity by reduced order modeling  

NASA Astrophysics Data System (ADS)

The focus of this investigation is on a first assessment of the predictive capabilities of nonlinear geometric reduced order models for the prediction of the large displacement and stress fields of panels with localized geometric defects, the case of a notch serving to exemplify the analysis. It is first demonstrated that the reduced order model of the notched panel does indeed provide a close match of the displacement and stress fields obtained from full finite element analyses for moderately large static and dynamic responses (peak displacement of 2 and 4 thicknesses). As might be expected, the reduced order model of the virgin panel would also yield a close approximation of the displacement field but not of the stress one. These observations then lead to two “enrichment” techniques seeking to superpose the notch effects on the virgin panel stress field so that a reduced order model of the latter can be used. A very good prediction of the full finite element stresses, for both static and dynamic analyses, is achieved with both enrichments.

Perez, Ricardo; Wang, X. Q.; Mignolet, Marc P.

2014-12-01

76

Closed full-field solutions for stresses and displacements in the Brazilian disk under distributed radial load  

Microsoft Academic Search

The Brazilian disk test, namely the diametric compression of a circular disk by radial loads that are uniformly distributed along two symmetric arcs of its periphery, is studied using the method of complex potentials introduced by Kolosov and Muskhelishvili. The rock is assumed to be linear elastic. Closed form full-field solutions are obtained for both the stress and the displacement

Ch. F. Markides; D. N. Pazis; S. K. Kourkoulis

2010-01-01

77

Biological effects due to weak magnetic field on plants  

NASA Astrophysics Data System (ADS)

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

Belyavskaya, N. A.

2004-01-01

78

Measurement of two-dimensional velocity fields in porous media by particle image displacement velocimetry  

Microsoft Academic Search

Local measurements of the phase function and of two components of the velocity can be performed in transparent porous media by means of particle image displacement velocimetry (P.I.D.V.). Some preliminary results are presented and discussed.

S. Saleh; J. F. Thovert; P. M. Adler

1992-01-01

79

Predicting ground electric field due to geomagnetic disturbances  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

80

Displacement field estimation for a two-dimensional structure using fiber Bragg grating sensors  

Microsoft Academic Search

The structure shape itself is of great interest for many aerospace applications. For example, the stability of the surface shape of large, high precision or space reflectors is essential for the communication performance. The knowledge of static and dynamic displacements of these structures would provide the possibility to enhance their performance by appropriate countermeasures. During operation, however, the direct measurement

Stephan Rapp; Lae-Hyong Kang; Jae-Hung Han; Uwe C. Mueller; Horst Baier

2009-01-01

81

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

Microsoft Academic Search

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

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

2004-01-01

82

Biological effects due to weak magnetic fields on plants  

NASA Astrophysics Data System (ADS)

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

Belyavskaya, N.

83

Improved Newton-Raphson digital image correlation method for full-field displacement and strain calculation.  

PubMed

The two-dimensional in-plane displacement and strain calculation problem through digital image processing methods has been studied extensively in the past three decades. Out of the various algorithms developed, the Newton-Raphson partial differential correction method performs the best quality wise and is the most widely used in practical applications despite its higher computational cost. The work presented in this paper improves the original algorithm by including adaptive spatial regularization in the minimization process used to obtain the motion data. Results indicate improvements in the strain accuracy for both small and large strains. The improvements become even more significant when employing small displacement and strain window sizes, making the new method highly suitable for situations where the underlying strain data presents both slow and fast spatial variations or contains highly localized discontinuities. PMID:21102673

Cofaru, Corneliu; Philips, Wilfried; Van Paepegem, Wim

2010-11-20

84

The Walker Branch throughfall displacement experiment: An overview, field performance data, and initial growth responses  

Microsoft Academic Search

At Walker Branch Watershed a group of interdisciplinary scientists are conducting the Throughfall Displacement Experiment, a stand-level manipulation experiment that provides the appropriate environment for mechanistic studies of ecosystem and plant-level responses to changing precipitation inputs to an upland oak forest. Soil water is being manipulated by a gravity-driven transfer of one third of the throughfall precipitation from a {open_quotes}dry{close_quotes}

P. J. Hanson; D. E. Todd; K. M. Harter

1995-01-01

85

Fiber-optic based method for the measurements of electric-field induced displacements in ferroelectric materials  

NASA Astrophysics Data System (ADS)

A novel technique for the measurements of electric field-induced displacements in ferroelectric materials is presented. The method relies on a high sensitivity of the fiber-optic probe (Fotonic Sensor™, MTI Inc.) that measures the displacement of a specially designed cantilever beam having both electrical and mechanical contact with deforming sample. In this way, the major disadvantages of the standard Fotonic Sensor technique can be avoided. The method provides relatively high sensitivity (down to ˜4Å), high stability (7% over 8h), and sufficiently broad frequency range. The capabilities of the proposed measurement setup are validated by the strain measurements in bulk Pb(Zr ,Ti)O3(PZT) ceramics and thin films.

Vyshatko, Nikolai P.; Brioso, Paulo M.; de la Cruz, Javier Pérez; Vilarinho, Paula M.; Kholkin, Andrei L.

2005-08-01

86

FARADAY ROTATION MEASURE DUE TO THE INTERGALACTIC MAGNETIC FIELD  

SciTech Connect

Studying the nature and origin of the intergalactic magnetic field (IGMF) is an outstanding problem of cosmology. Measuring Faraday rotation would be a promising method to explore the IGMF in the large-scale structure (LSS) of the universe. We investigated the Faraday rotation measure (RM) due to the IGMF in filaments of galaxies using simulations for cosmological structure formation. We employed a model IGMF based on turbulence dynamo in the LSS of the universe, it has an average strength of (B) {approx} 10 nG and a coherence length of several x 100 h {sup -1} kpc in filaments. With the coherence length smaller than the path length, the inducement of RM would be a random walk process, and we found that the density peak along the line of sight dominantly contributes to the resultant RM. The root mean square of RM through filaments at the present universe was predicted to be {approx}1 rad m{sup -2}. In addition, we predicted that the probability distribution function of |RM| through filaments follows the lognormal distribution, and the power spectrum of RM in the local universe peaks at a scale of {approx}1 h {sup -1} Mpc. Our prediction of RM could be tested with future instruments.

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

2010-11-01

87

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

88

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

PubMed Central

Radiofrequency (RF) ablation is a minimally invasive treatment for tumors in various abdominal organs. It is effective if good tumor localization and intra-procedural monitoring can be done. In this paper, we investigate the feasibility of using an ultrasound-based Young’s modulus reconstruction algorithm to image an ablated region whose stiffness is elevated due to tissue coagulation. To obtain controllable tissue deformations for abdominal organs during and/or intermediately after the RF ablation, the proposed modulus imaging method is specifically designed for using tissue deformation fields induced by the RF electrode. We have developed a new scheme under which the reconstruction problem is simplified to a two-dimensional problem. Based on this scheme, an iterative Young’s modulus reconstruction technique with edge-preserving regularization was developed to estimate the Young’s modulus distribution. The method was tested in experiments using a tissue-mimicking phantom and on ex vivo bovine liver tissues. Our preliminary results suggest that high contrast modulus images can be successfully reconstructed. In both experiments, the geometries of the reconstructed modulus images of thermal ablation zones match well with the phantom design and the gross pathology image, respectively. PMID:19258195

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

2009-01-01

89

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

NASA Astrophysics Data System (ADS)

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

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

2005-06-01

90

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

PubMed

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

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

2011-06-01

91

Dose uncertainty due to aperture effects in dynamic fields  

Microsoft Academic Search

Dosimetry of intensity modulated radiation therapy requires accurate modeling of the beamlets that comprise each treatment segment. Planning systems such as Varian Eclipse and Philips Pinnacle recommend measuring dose distributions and output factors for fields as small as possible, generally down to at least 2x2 cm². Conventionally, we perform these measurements for regular fields, defined by the secondary collimators. In

P. D. Higgins; P. Alaei

2006-01-01

92

Students drop out of STEM fields due to poor grades  

NASA Astrophysics Data System (ADS)

College students planning to major in science, technology, engineering, and mathematics (STEM) fields often drop out of those fields because of poorer than expected grades, according to a recent study. Conducted by Ralph Stinebrickner of Berea College in Kentucky and Todd Stinebrickner of the University of Western Ontario, the study is a National Bureau of Economic Research working paper published in June 2013.

Balcerak, Ernie

2013-09-01

93

Measuring Oscillatory Velocity Fields Due to Swimming Algae  

E-print Network

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

Guasto, Jeffrey S; Gollub, J P

2010-01-01

94

Mean Cross-Field Displacement of Magnetic Field Lines in Slow Solar Wind: A Confirmation of the Supradiffusion Predicted by the Generalized Quasilinear Theory  

NASA Astrophysics Data System (ADS)

A quantitative comparison of the magnetic field-line mean cross-field displacements predicted by the generalized quasilinear theory and of those deduced from Helios 2 in situ measurements is presented for the quiet slow solar wind (SW) at 0.3 and 1 AU. While the supradiffusivity of the magnetic field lines, X2~(?z)? with 2>=?>1, is confirmed on all field-aligned scales ?z<0.1 AU, the precise amplitude of the mean cross-field displacement X may not be obtained without some correction of the in situ measured spectra at frequencies <10-4 Hz. The SW cross flow and resulting transverse decorrelation and spectral flattening would cause the global amplitude of X to be underestimated by up to a factor 2. The value of the transport exponent ? below 0.01 AU is little affected by the uncertainty at very low frequencies; it is very close to the value determined by the spectrum around (?z)-1. By plotting segments of wandering magnetic field lines computed from Helios 2 data as perturbations to Parker spiral fields, a lower limit of the order of 20° is also established for the median angular deviation of the wandering field lines. The cumulative angular deviation of a magnetic field line wandering from the source region of impulsive solar energetic particles (SEPs) out to 1 AU may, in some instances, be a few times larger. It occurs in longitude and latitude and could explain the relatively low magnetic connectivity of impulsive SEPs. The variability of the slow SW turbulence is also demonstrated.

Ragot, B. R.

2006-08-01

95

Full field displacement measurement by double symmetrical illumination with diode lasers through a pair of double exposure reflectionholograms  

NASA Astrophysics Data System (ADS)

Compact and stable phase stepping interferometer for shape and full field displacement measurement in static and in "real time" operation mode is presented. Double symmetrical illumination of the object in two orthogonal planes with diode lasers, emitting in NIR (790 nm and 830 nm), through a four-exposure reflective holographic optical element (Denisiyk's volume reflection holograms of a reference plane) is applied. The proposed four channels one-beam interferometer is very compact, as the diode lasers without collimators and spatial filters are used directly for reconstruction of the reference planes from a pair of double exposure reflection holograms and for object's illumination through the same holographic optical element. Phase stepping is introduced simply by precise increments of the diode lasers current. By introduction of removable sinusoidal phase gratings and removal of the holographic optical element, the system operates as a single-shot fringe projection profilometer for shape measurement that is essential for precise estimation of displacement vector's components. The proposed system is very stable against external noise, produced by vibrations, temperature changes, air flows, as well as against the influence of object's "rigid body" motion, as the compact and low weight interferometer can be stably fixed directly onto the measured construction.

Sainov, V.; Baldjiev, A.; Stoykova, E.

2013-06-01

96

Approximations by gravitational fields due to restricted unit point masses  

E-print Network

) December 1973 ABSTRACT Approximations by Gravitational Pields Due to Restricted Unit Point Masses. (December 1973) Carolyn Flowers Shull, B. S. , Stephen P. Austin State University Directed by: Dr. Charles K. Chui The objective of this thesis.... ACKNOWLEDGENENTS I wish to sincerely thank Dr. Charles K. Chui for his suggestions and guidance concerning this thesis. I also am grateful to my husband, William H. Shull, for helping to type this thesis. TABLE OF CONTENTS CHAPTER INTRODUCTION. I. Uniform...

Shull, Carolyn Sue Flowers

2012-06-07

97

Optical wavefront distortion due to supersonic flow fields  

Microsoft Academic Search

The optical wavefront distortion caused by a supersonic flow field around a half model of blunt nose cone was studied in a\\u000a wind tunnel. A Shack-Hartmann wavefront sensor was used to measure the distorted optical wavefront. Interesting optical parameters\\u000a including the peak variation (PV), root of mean square (RMS) and Strehl ratio were obtained under different test conditions\\u000a during the

ZhiQiang Chen; Song Fu

2009-01-01

98

Nanofiber near-field light-matter interactions for enhanced detection of molecular level displacements and dynamics.  

PubMed

We experimentally demonstrate that plasmonic nanoparticles embedded in the evanescent field of subwavelength optical waveguides (WGs) are highly sensitive to distances normal to the propagation of light, showing an ~10× increase in spatial resolution compared to the optical field decay of the WG. The scattering cross-section of the Au nanoparticle is increased by the plasmon-dielectric coupling interaction when the nanoparticle is placed near the dielectric surface of the WG, and the decay of the scattering signal is enhanced, showing angstrom level distance sensitivity within 10 nm from the WG. Numerical studies with the finite-difference time-domain (FDTD) method correlate well with the experimental results. To demonstrate real-time monitoring of a single molecule stretching in the evanescent field, we linked individual single-stranded DNA molecules between the WG and plasmonic nanoparticles and pushed on the nanoparticles with fluidic forces. The simple design and ease of obtaining optical feedback on molecular displacements makes our approach ideal for new in situ force sensing devices, imaging technologies, and high-throughput molecular analysis. PMID:23517010

Yoon, Ilsun; Baker, Sarah E; Kim, Kanguk; Fischer, Nicholas O; Heineck, Daniel; Wang, Yinmin; Esener, Sadik C; Sirbuly, Donald J

2013-04-10

99

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

SciTech Connect

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

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

1998-04-01

100

Thickness measurement of full field soap bubble film in real time based on large lateral shearing displacement interferometry  

NASA Astrophysics Data System (ADS)

Soap bubble has a profile nearly the same as a perfect sphere. Many researches focus on the measurement of the film thickness of the soap bubble over time in order to calculate the film drainage rate. Its thickness variation in gravitation field can be respectively approximated with many models, considering the cost and precision in different applications. In this research, fringe patterns of a soap bubble were captured continuously using the large lateral shearing displacement interferometry during the process from its formation to burst. From the analysis of three typical frames, it can be seen that the film thickness distribution along the gravity orientation shows a very good agreement with an exponential model. The ratio of its maximum error to the laser wavelength is 3/8, existing at the sphere's center. Moreover, it can be seen that the absolute value of the parameter k in the exponential model keeps increasing over time, while the parameter b keeps decreasing over time. Based on the parameter k from the exponential model, the maximum limit in the thickness measurement of the soap bubble film can be calculated from the function of the fringe pattern's resolution and its field coordinates. The result shows that there is a special point above the sphere's center, being the right place where the gradient of phase order changes its sign. The region near this point presents very high limitation in the film thickness measurement.

Lv, Wei; Zhou, Huai-chun; Zhu, Jin-rong

2012-03-01

101

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

E-print Network

Using time-lapse seismic amplitude data to detect variations of pore pressure and fluid saturation due to oil displacement by water: a numerical study based on one-dimensional prestack inversion. Geophys. Eng. 3 (2006) 177­193 doi:10.1088/1742-2132/3/2/009 Using time-lapse seismic amplitude data

Torres-Verdín, Carlos

102

Crack embrittlement displacement fields  

NASA Astrophysics Data System (ADS)

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

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

103

CHARACTERISTICS OF FAR FIELD AND ENERGY FLOW DUE TO A MOVING RADIATING SOURCE IN VARIOUS MEDIA  

E-print Network

CHARACTERISTICS OF FAR FIELD AND ENERGY FLOW DUE TO A MOVING RADIATING SOURCE IN VARIOUS MEDIA FIELD AND ENERGV FLOW DUE TO A MOVING RADIATING SOURCE IN VARIOUS MEDIA CONTENTS Acknowledgement. Abst.1 Definit.ion and physical meaning 3.2 Examples of DWS's 3.2.1 vacuum 3.2.2 isot.ropic non-dispersive media

Ng, Chung-Sang

104

Suppression of side lobes in a spectrum of fibre Bragg gratings due to the transverse displacement of phase mask with respect to the optical fibre  

SciTech Connect

The possibility of apodisation of fibre Bragg gratings (FBGs) recorded in the interference region of two Gaussian beams in the phase-mask scheme is considered. The FBG reflection spectra are numerically simulated for different values of recordingbeam parameters and the distance between the axes of interfering beams diffracted into different orders, which is varied by transverse displacement of the phase mask with respect to the optical fibre. Suppression of side lobes and smoothing out of the FBG spectrum with an increase in the transverse displacement of the phase mask is experimentally demonstrated. It is shown that this effect is caused by the equalisation of the mean induced refractive index in the FBG region. (optical fibres, lasers and amplifiers. properties and applications)

Abdullina, S R; Nemov, I N; Babin, Sergei A [Institute of Automation and Electrometry, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

2012-09-30

105

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

NASA Astrophysics Data System (ADS)

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

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

2005-05-01

106

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

NASA Technical Reports Server (NTRS)

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.

Parasarathy, R.; Karamcheti, K.

1972-01-01

107

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

Microsoft Academic Search

The high-field performance of SRF cavities will eventually be limited by the realization of fundamental material limits, whether it is Hc1 or Hsh, or some derivative thereof, at which the superconductivity is lost. Before reaching this fundamental field limit at the macro level, it must be encountered at localized, perhaps microscopic, sites of field enhancement due to local topography. If

Chen Xu; Charles Reece; Michael Kelley

2012-01-01

108

Synthesis of finite displacements and displacements in continental margins  

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

109

X-ray diffraction study of the displacement filed normal to grain boundaries  

Microsoft Academic Search

The diffuse X-ray scattering intensity in the vicinity of Bragg reflections was studied in order to obtain quantitative information on the displacement field due to twist boundaries. The present investigation focused on the behavior of the displacement field normal to the boundary plane. The experiments were performed using thin film bicrystals containing (001) twist boundaries. Results are presented and discussed

E. Burkel; M. Fitzsimmons; S. L. Sass

2008-01-01

110

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

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

2010-01-01

111

Superdiffusion of 2D Yukawa liquids due to a perpendicular magnetic field  

E-print Network

Stochastic transport of a two-dimensional (2D) dusty plasma liquid with a perpendicular magnetic field is studied. Superdiffusion, which is a type of non-Fickian transport, is found to occur especially at higher magnetic fields with $\\beta$ of order unity. Here, $\\beta = \\omega_c / \\omega_{pd}$ is the ratio of the cyclotron and plasma frequencies for dust particles. The mean-square displacement ${\\rm {MSD}} = 4 D_\\alpha t^\\alpha$ is found to have an exponent $\\alpha > 1$, indicating superdiffusion, with $\\alpha$ increasing monotonically to $1.1$ as $\\beta$ increases to unity. The 2D Langevin molecular dynamics simulation used here also reveals that another indicator of random particle motion, the velocity autocorrelation function (VACF), has a dominant peak frequency $\\omega_{peak}$ that empirically obeys $\\omega_{peak}^2 = \\omega_c^2+ \\omega_{pd}^2/4$.

Yan Feng; J. Goree; Bin Liu; T. P. Intrator; M. S. Murillo

2013-11-27

112

Superdiffusion of two-dimensional Yukawa liquids due to a perpendicular magnetic field.  

PubMed

Stochastic transport of a two-dimensional (2D) dusty plasma liquid with a perpendicular magnetic field is studied. Superdiffusion is found to occur especially at higher magnetic fields with ? of order unity. Here, ? = ?(c)/?(pd) is the ratio of the cyclotron and plasma frequencies for dust particles. The mean-square displacement MSD = 4D(?)t(?) is found to have an exponent ? > 1, indicating superdiffusion, with ? increasing monotonically to 1.1 as ? increases to unity. The 2D Langevin molecular dynamics simulation used here also reveals that another indicator of random particle motion, the velocity autocorrelation function, has a dominant peak frequency ?(peak) that empirically obeys ?(peak)(2) = ?(c)(2) + ?(pd)(2)/4. PMID:25122399

Feng, Yan; Goree, J; Liu, Bin; Intrator, T P; Murillo, M S

2014-07-01

113

Displacement measurements of highway bridges using digital image correlation methods  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

114

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

Microsoft Academic Search

Closed-form solutions are presented for the transient hydromagnetic flow in a rotating channel with inclined applied magnetic\\u000a field under the influence of a forced oscillation. Magnetic Reynolds number is large enough to permit the inclusion of magnetic\\u000a induction effects. The Maxwell displacement current effect is also included and simulated via a dielectric strength parameter.\\u000a The governing momentum and magnetic induction

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

2010-01-01

115

On the crystal field line broadening due to spin fluctuations in cuprates  

NASA Astrophysics Data System (ADS)

The crystal field excitation linewidth GCF(T) in the Tm-YBCO system is calculated due to s-f interaction. By using a two-level approximation for crystal-field excitations, it is shown that antiferromagnetic spin fluctuations in the CuO2 planes are important to explain the temperature dependence of GCF.>

Plakida, N. M.; Kovacevic, Z.; Kova?evi?, Ž.

1994-12-01

116

The dissociation-induced displacement of chemisorbed O2 by mobile O atoms and the autocatalytic recombination of O due to chain fragmentation on Ag(110)  

NASA Astrophysics Data System (ADS)

The interplay between thermal desorption of chemisorbed dioxygen and its dissociation was studied with temperature programmed methods. Analysis of the kinetics of molecular desorption and the fraction of adsorbed molecules which dissociate is consistent with a model in which oxygen atoms released by the dissociation event induce desorption of the molecular species. These unequilibrated atoms exhibit a mean free path relative to the chemisorbed dioxygen of 1.8 nm prior to thermalization with the surface, displacing chemisorbed dioxygen within their reach. Each dissociation event leads to desorption of two oxygen molecules if the space between chemisorbed molecules approaches the minimum of 0.58 nm. This condition can be achieved experimentally by saturating the population of chemisorbed dioxygen (0.33 ML O2) at 90-100 K. Oxygen adatoms recombine near 580 K from the reconstructed (n × 1)-O adlayer with kinetics dictated by progressive fragmentation of the O(AgO)m rows. This behavior gives rise to autocatalytic recombination kinetics of oxygen adatoms which produces both an acceleration of rate at constant temperature and unusual recombination kinetics in temperature programmed desorption.

Eric Klobas, J.; Schmid, Martin; Friend, Cynthia M.; Madix, Robert J.

2014-12-01

117

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

NASA Astrophysics Data System (ADS)

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

Mechaik, Mehdi Mohamad

118

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

Microsoft Academic Search

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

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

119

The switch between electromagnetically induced transparency and absorption due to the power broadening of probing field  

NASA Astrophysics Data System (ADS)

In this paper we present a theoretical study of the nonlinear effect in the quasi-lambda type four-level system. The system consists of an excited state level and three ground state hyperfine levels. Probing and coupling field are coupled to between the excited state and two higher ground states, and the microwave field drives the two lower ground states which are associated with probing field. By solving the precision solutions of the equations of motion of density matrix, the absorption properties as a function of Rabi frequencies of the probing field and microwave field are given. As a result, the switch from double EIT to single EIA is found due to the power broadening of probing field. However, the splitting frequency of double EIT has some connection with the Rabi frequency of microwave field.

Li, Xiaoli; He, Chao; Zhang, Jianfei

2010-11-01

120

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

121

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

NASA Astrophysics Data System (ADS)

We derived explicit expressions in the time domain for 3-D quasi-static strain and stress fields, due to a point moment tensor source in an elastic surface layer overlying viscoelastic half-space under gravity. The expressions of strain in the elastic surface layer were directly obtained from the expressions of displacement in our previous paper. The conversion of strain into stress is easy, because the stress-strain relation of elastic material is linear. In the viscoelastic substratum, the expressions of strain were obtained by applying the correspondence principle of linear viscoelasticity to the associated elastic solution. The strain-stress conversion is not straightforward, as the stress-strain relation of viscoelastic material is usually given in a differential form. To convert strain into stress, we used an integral form of the stress-strain relation instead of the usual differential form. The expressions give the responses of elastic half-space at t = 0 , and the responses of an elastic plate floating on non-viscous liquid at t = ? . The moment tensor is rationally decomposed into the three independent force systems, corresponding to isotropic expansion, shear faulting and crack opening, and so the expressions include the strain and stress fields for these force systems as special cases. As the first numerical example, we computed the temporal changes in strain and stress fields after the sudden opening of an infinitely long vertical crack cutting the elastic surface layer. Here, we observe that the stress changes caused by the sudden crack opening gradually decay with time and vanish at t = ? everywhere. After the completion of stress relaxation, a characteristic pattern of shear strain remains in the viscoelastic substratum. Since the strain and stress fields at t = ? can be read as the strain- and stress-rate fields caused by steady crack opening, respectively, this numerical example demonstrates the realization of a steady stress state supported by steady viscous flow in the asthenosphere, associated with steady seafloor spreading at mid-ocean ridges. For the second numerical example, we computed the temporal changes in strain and stress fields after the 2011 Tohoku-oki mega-thrust earthquake, which occurred at the North American-Pacific plate interface. In this numerical example, the stress changes caused by coseismic fault slip vanish at t = ? in the viscoelastic substratum, but remain in the elastic surface layer. The coseismic stress changes (and also strain changes) in the elastic surface layer diffuse away from the source region with time, due to gradual stress relaxation in the viscoelastic substratum.

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

2014-03-01

122

Displacement of Torymus beneficus (Hymenoptera: Torymidae) by T. sinensis, an indigenous and introduced parasitoid of the chestnut gall wasp, Dryocosmus kuriphilus (Hymenoptera: Cynipidae), in Japanese chestnut fields: Possible involvement in hybridization  

Microsoft Academic Search

Although there is empirical knowledge to suggest the displacement of Torymus beneficus (Hymenoptera: Torymidae) by Torymus sinensis, an indigenous and introduced parasitoid of the chestnut gall wasp Dryocosmus kuriphilus (Hymenoptera: Cynipidae), respectively, in Japanese chestnut fields, the underlying mechanisms are unclear. In this study, the displacement of the early-spring strain of T. beneficus by T. sinensis was surveyed in a

Kaori Yara; Terunori Sasawaki; Yasuhisa Kunimi

2007-01-01

123

The distortion of a uniform flow field due to a finite flat plate  

E-print Network

THE DISTORTION OI' A UNIFORM FLON FIELD DUE TO A FINITE FLAT PLATE A Thesis Lawrence Michael Zull Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE May... 1970 Major Subject: Mechanical F~nin~eerin THE DISTORTION OF A UNIFORM FLOV FIELD DUE TO A FINITE FLAT PLATE A Thesis by Lawrence Michael Zull Approved as to style and content by: (Ch (Head of De artment) (Member) (Member) ~Ma 19 70 AB...

Zull, Lawrence Michael

2012-06-07

124

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

125

Electromagnetic field generated by a finite fault due to electrokinetic effect  

NASA Astrophysics Data System (ADS)

This work investigates surface electromagnetic wavefields generated by a finite fault due to electrokinetic effect with Pride's theory as the governing equations. A finite fault is discretized into a series of small subfaults, each of which is taken as a point source with different initiation time. The wavefields generated by the whole fault are then synthesized by stacking those generated by all the subfaults. Numerical simulations of a vertical strike-slip fault with a constant rupturing velocity are then conducted on the basis of the derived formalism. Simulation results show that the rupturing fault generates observable permanent ground motions and electromagnetic field disturbances. Two types of electric field characters are observed in simulations: the coseismic oscillatory variation and the postseismic decaying variation. When the fault rupturing stops and the seismic waves pass far away, the magnetic field vanishes while the electric field remains, decaying slowly and lasting for hundreds of seconds. Adjacent to the free surface the vertical electric field is about 100 times larger than the horizontal one. When the receiving depth increases, the amplitudes of the horizontal electric fields in both the oscillatory and decaying components increase while those of the vertical electric fields decrease. It is also shown that there is no horizontal electric field remnant right at the free surface after the seismic perturbations decay away. The near-fault electric fields simulated in this paper hold similar features to some field observations in literature.

Hu, Hengshan; Gao, Yongxin

2011-08-01

126

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

E-print Network

Acoustic radiation force in tissue-like solids due to modulated sound field Egor V. Dontsov, Bojan wherein the transverse coordinates are scaled by the width of the focal region, while the axial plate, the radiation force of sound is a phenomenon that has been intensely studied for over a century

Guzina, Bojan

127

Comparison of methods for calculating the sound field due to a rotating monopole.  

PubMed

A spherical harmonic expansion for the sound field due to a rotating oscillating point source has recently been derived. This paper provides further confirmation of the expansion results by comparing it with two known numerical approaches to determining the sound field. In the advanced time approach-applicable for Mach numbers below 1-the sound at transmission time determines the field at an observation point from the distance from source to observation point at the transmission time. In the retarded time approach the field at the observation point at the observation time is determined by solving for the retarded transmission times. The results from all three approaches are shown to be in good agreement. Expressions for the far-field instantaneous frequency are also derived and shown to agree with previous work. PMID:21682378

Poletti, M A; Teal, P D

2011-06-01

128

Model based estimation of image depth and displacement  

NASA Technical Reports Server (NTRS)

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

Damour, Kevin T.

1992-01-01

129

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

SciTech Connect

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

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

2005-05-16

130

RTV 21 Displacements  

SciTech Connect

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.

Kurita, C.H.; /Fermilab

1987-02-04

131

Electric field enhancement between two parallel cylinders due to plasmonic resonance  

SciTech Connect

We theoretically examine the electric field enhancement in the narrow gap between two parallel cylinders due to the plasmonic resonance. The resonance condition and the field enhancement factor are found explicitly. It is shown that the resonance occurs at frequencies lower than the plasma frequency. This effect results from the special geometry: the gap width between parallel cylinders is much smaller than their radii. It is also shown that the enhancement coefficient is much larger than the one for a single cylinder and is determined together with the resonance frequency by the system geometry.

Vorobev, P. E., E-mail: petro999@list.r [Landau Institute for Theoretical Physics Russian Academy of Sciences (Russian Federation)

2010-02-15

132

Eddy current fields and overheating problems due to heavy current carrying conductors  

Microsoft Academic Search

Large complex problems, eddy current fields and local overheating due to heavy current carrying conductors (HCCC) including leads and connecting bus bars in a 360 MVA\\/500 kV power transformer, are analyzed by the boundary element method. To improve numerical accuracy, this paper chooses triangle polar coordinate mapping and addition-substraction techniques to evaluate singular integrals. The distributions of magnetic flux and

Junyou Yang; Renyuan Tang; Yan Li; Yongbin Chen

1994-01-01

133

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

USGS Publications Warehouse

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

Lee, M.W.

1987-01-01

134

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

SciTech Connect

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.

Wang, Qi; Crandall, R.S. [National Renewable Energy Lab., Golden, CO (United States)] [National Renewable Energy Lab., Golden, CO (United States); Schiff, E.A. [Syracuse Univ., NY (United States)] [Syracuse Univ., NY (United States)

1996-05-01

135

Enhancement of the thermoelectric figure of merit in a quantum dot due to external ac field  

NASA Astrophysics Data System (ADS)

We investigate the figure of merit of a quantum dot (QD) system irradiated with an external microwave filed by nonequilibrium Green's function (NGF) technique. Results show that the frequency of microwave field influence the figure of merit ZT significantly. At low temperature, a sharp peak can be observed in the figure of merit ZT as the frequency of ac field increases. As the frequency varies, several zero points and resonant peaks emerge in the figure of merit ZT. By adjusting the frequency of the microwave field, we can obtain high ZT. The figure of merit ZT increases with the decreasing of linewidth function ?. In addition, Wiedemann-Franz law does not hold, particularly in the low frequency region due to multi-photon emission and absorption. Some novel thermoelectric properties are also found in two-level QD system.

Chen, Qiao; Wang, Zhi-yong; Xie, Zhong-Xiang

2013-08-01

136

Additional enhancement of electric field in surface-enhanced Raman Scattering due to Fresnel mechanism.  

PubMed

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

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

2013-01-01

137

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

138

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

PubMed Central

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

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

2013-01-01

139

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

NASA Technical Reports Server (NTRS)

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).

Peltzer, G.; Crampe, F.

1998-01-01

140

Displacement Compensation of Temperature Probe Data  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

141

Neural Control of Visual Search by Frontal Eye Field: Effects of Unexpected Target Displacement on Visual Selection and Saccade Preparation  

PubMed Central

The dynamics of visual selection and saccade preparation by the frontal eye field was investigated in macaque monkeys performing a search-step task combining the classic double-step saccade task with visual search. Reward was earned for producing a saccade to a color singleton. On random trials the target and one distractor swapped locations before the saccade and monkeys were rewarded for shifting gaze to the new singleton location. A race model accounts for the probabilities and latencies of saccades to the initial and final singleton locations and provides a measure of the duration of a covert compensation process—target-step reaction time. When the target stepped out of a movement field, noncompensated saccades to the original location were produced when movement-related activity grew rapidly to a threshold. Compensated saccades to the final location were produced when the growth of the original movement-related activity was interrupted within target-step reaction time and was replaced by activation of other neurons producing the compensated saccade. When the target stepped into a receptive field, visual neurons selected the new target location regardless of the monkeys’ response. When the target stepped out of a receptive field most visual neurons maintained the representation of the original target location, but a minority of visual neurons showed reduced activity. Chronometric analyses of the neural responses to the target step revealed that the modulation of visually responsive neurons and movement-related neurons occurred early enough to shift attention and saccade preparation from the old to the new target location. These findings indicate that visual activity in the frontal eye field signals the location of targets for orienting, whereas movement-related activity instantiates saccade preparation. PMID:19261711

Murthy, Aditya; Ray, Supriya; Shorter, Stephanie M.; Schall, Jeffrey D.; Thompson, Kirk G.

2009-01-01

142

Neural control of visual search by frontal eye field: effects of unexpected target displacement on visual selection and saccade preparation.  

PubMed

The dynamics of visual selection and saccade preparation by the frontal eye field was investigated in macaque monkeys performing a search-step task combining the classic double-step saccade task with visual search. Reward was earned for producing a saccade to a color singleton. On random trials the target and one distractor swapped locations before the saccade and monkeys were rewarded for shifting gaze to the new singleton location. A race model accounts for the probabilities and latencies of saccades to the initial and final singleton locations and provides a measure of the duration of a covert compensation process-target-step reaction time. When the target stepped out of a movement field, noncompensated saccades to the original location were produced when movement-related activity grew rapidly to a threshold. Compensated saccades to the final location were produced when the growth of the original movement-related activity was interrupted within target-step reaction time and was replaced by activation of other neurons producing the compensated saccade. When the target stepped into a receptive field, visual neurons selected the new target location regardless of the monkeys' response. When the target stepped out of a receptive field most visual neurons maintained the representation of the original target location, but a minority of visual neurons showed reduced activity. Chronometric analyses of the neural responses to the target step revealed that the modulation of visually responsive neurons and movement-related neurons occurred early enough to shift attention and saccade preparation from the old to the new target location. These findings indicate that visual activity in the frontal eye field signals the location of targets for orienting, whereas movement-related activity instantiates saccade preparation. PMID:19261711

Murthy, Aditya; Ray, Supriya; Shorter, Stephanie M; Schall, Jeffrey D; Thompson, Kirk G

2009-05-01

143

Spin and valley polarization of plasmons in silicene due to external fields  

NASA Astrophysics Data System (ADS)

The electronic properties of the two-dimensional material silicene are strongly influenced by the application of a perpendicular electric field Ez and of an exchange field M due to adatoms positioned on the surface or a ferromagnetic substrate. Within the random phase approximation, we investigate how electron-electron interactions are affected by these fields and present analytical and numerical results for the dispersion of plasmons, their lifetime, and their oscillator strength. We find that the combination of the fields Ez and M brings a spin and valley texture to the particle-hole excitation spectrum and allows the formation of spin- and valley-polarized plasmons. When the Fermi level lies in the gap of one spin in one valley, the intraband region of the corresponding spectrum disappears. For zero Ez and finite M the spin symmetry is broken and spin polarization is possible. The lifetime and oscillator strength of the plasmons are shown to depend strongly on the number of spin and valley type electrons that form the electron-hole pairs.

Van Duppen, B.; Vasilopoulos, P.; Peeters, F. M.

2014-07-01

144

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

PubMed

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. PMID:22713253

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

2012-07-01

145

hal-00252040,version1-12Feb2008 Near-field induction heating of metallic nanoparticles due to infrared magnetic  

E-print Network

hal-00252040,version1-12Feb2008 Near-field induction heating of metallic nanoparticles due mechanism is near-field induction heating, due to Joule dissipation of eddy currents in the particle.ecp.fr We revisit the electromagnetic heat transfer between a metallic nanoparticle and a metallic semi

Paris-Sud XI, Université de

146

Modelling the electric and magnetic fields at the Earths surface due to an auroral electrojet  

NASA Astrophysics Data System (ADS)

A calculation of the electric and magnetic fields at the Earths surface due to an ionospheric electrojet system is required for the estimation of geomagnetically induced currents (GIC) in a technological network, which are a manifestation of space weather effects on the ground. Two models of the auroral electrojet for calculating the geoelectromagnetic field are compared in this paper: an infinitely long line current and a more realistic system consisting of an electrojet of a finite length and of vertical (field-aligned) currents at its ends. The Earth is described by a two-layer half-space, and a small and a large period of oscillation in time are considered. In the case of an infinite line current the field at the Earths surface is independent of the space coordinate parallel to the electrojet, and in the case of the finite electrojet two profiles perpendicular to the electrojet and located at the centre of the electrojet and near the edge of the electrojet are considered. The most significant shortcoming of the infinite model is the neglect of the horizontal electric component perpendicular to the electrojet as well as the horizontal magnetic component parallel to the electrojet. It is shown in this paper that these components may in reality get values in the order of 0.1-1 Vkm and 100-200 nT, respectively. The parallel electric component and the perpendicular horizontal magnetic component are overestimated by the infinite model by about 10-50% at their maxima achieved beneath the electrojet. At large distances the infinite model leads to an incorrect sign of these components. The vertical magnetic component is accurately obtained by the infinite model.

Pirjola, R. J.

1998-07-01

147

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

NASA Astrophysics Data System (ADS)

A model of the short-period motion of a satellite due to tesseral harmonic terms of the central gravity field is developed for inclusion in a semianalytical satellite theory for high-accuracy orbit prediction and determination problems. The generalized method of averaging is applied to the two-phase-angle tesseral harmonic problem to obtain complete first-order expressions for the short-period variations, which are then cast in the form of a double Fourier series in the mean mean-longitude and the Greenwich Sidereal Time, with coefficients that are slowly varying functions of time. The resulting model is general with respect to the geopotential coefficients and valid for fields of arbitrary degree and order. The Fourier coefficients are only evaluated with the theory a few times a day, with values at other times determined by interpolation. Results of numerical experiments with the model implemented as part of a semianalytical orbit generator are presented and compared with Cowell orbit determination results in order to verify model results for a range of satellite altitudes and eccentricities.

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

1981-08-01

148

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

NASA Astrophysics Data System (ADS)

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

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

1984-06-01

149

Is Maxwell's Displacement Current a Current?  

ERIC Educational Resources Information Center

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)

French, A. P.

2000-01-01

150

Cloud-Radiation Field Changes due to the Direct Effect of Smoke Aerosols in Southeast Mexico  

NASA Astrophysics Data System (ADS)

In general, aerosols affect climate mainly by directly absorbing and scattering input solar radiation and indirectly through their rule as cloud condensation nuclei. Smoke aerosols from biomass burning are considered to be the second most important source of anthropogenic particles (sulfate aerosols being the first) that are influencing the climate. Numerical simulations are carried on MM5 (using the CCM2 radiative scheme) by introducing the smoke aerosol spectral optical properties in the southeastern Mexican region. The neighborhood of this region is the most important source of biomass burning aerosols in Central America during the dry season (February-June). The particles are considered to be homogeneous in composition and the optical properties are calculated using Mie theory and the Remer et al. (1998) smoke model. Simulations are performed for March 17-20 and April 18-20, 2003. These two periods resulted to be a relative maximum in the number of fires detected in the studied region according to different algorithms based on satellite imagery. GDAS data are used to initialize the MM5 model. The goal is to study the changes in the cloud-radiation field due to the aerosol direct effect varying the smoke aerosol optical properties, especially the optical depth. Preliminary results support the argument that not only the aerosol effect is important but also the cloud changes due to the radiative differences caused by the aerosol direct effect itself. These cloud effects followed very different ways sometimes depending on atmospheric conditions of course, but also on other characteristics such as orography or land surface features. The simulations indicate a wide range on the surface radiative forcing varying from -40 W/m2 for smoke particles with an optical depth of 0.2 (at 670 nm), to -140 W/m2 for particles with an optical depth of 0.8.

Montero-Martinez, M. J.

2003-12-01

151

Electroporation in cells and tissues: A biophysical phenomenon due to electromagnetic fields  

NASA Astrophysics Data System (ADS)

The effect of "strong" electromagnetic fields on cells and tissue can be dramatic but not necessarily harmful. The essentially universal biophysical phenomenon of "electroporation" occurs if an applied field causes the cell transmembrane voltage to reach about 0.5-1 V in a time of microseconds to milliseconds. Ordinarily the cell membrane is a formidable barrier to the transport of ions and charged molecules. However, electroporation results in a large increase in transmembrane conductance, which is believed to be caused by ion transport through temporary membrane openings ("pores"). This high-conductance state limits the transmembrane voltage and thereby protects the membrane. A large increase in molecular transport generally occurs for the same conditions and allows polar molecules to be introduced into cells. Similar enhanced molecular transport can be caused in living tissues. Not only cell membranes, but also cell layers or even the stratum corneum of human skin can be temporarily altered by the electrical creation of aqueous pathways. The mechanism of electroporation is partially understood, in that the electrical and mechanical behavior of artificial planar bilayer membranes can be described quantitatively by a theoretical model based on transient aqueous pores. More complex behavior in cell membranes may be due to both the complicated shapes of cell membranes and the additional participation of metastable pores and interactions with cell structures. In the case of tissues the situation is even more complex and has only recently begun to be studied but has the prospect of providing a new approach to transporting polar molecules across tissue barriers.

Weaver, James C.

1995-01-01

152

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

SciTech Connect

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

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

2011-09-10

153

Observed Changes in the Gravity Field of Mars Due to Seasonal Atmospheric Processes  

NASA Technical Reports Server (NTRS)

The atmosphere of Mars deposits approximately 30% of its mass at the winter pole as part of its seasonal cycle of CO2 exchange and sublimes it back to the atmosphere in the spring, thus creating an annual hemispheric cycle of mass re-distribution. Using X-band tracking data of the Mars Global Surveyor (MGS) spacecraft, we have detected the signature of changes in the low degree gravity field from March 1999 through August 2000, corresponding to about three-quarters of a Martian year. The observed variations show a general resemblance to predicted variations from general circulation models. Also observed are irregular changes that appear to be due to transient phenomena in the Martian atmosphere such as large dust storms that provide significant heat into the lower atmosphere, even in the polar regions. In addition, we have identified a change in the rate of rotation of Mars over this same period that appears somewhat smaller than anticipated, but in general agreement with general circulation models.

Smith, David E.; Zuber, M. T.; Dunn, P. J.; Torrence, M. H.; Fricke, S. K.

2000-01-01

154

Anomalies due to the crystal field in the paramagnetic susceptibility of salts of the rare earth metals  

Microsoft Academic Search

We report here a study of the anomalies due to the crystal field in the paramagnetic susceptibility and the relationship between these anomalies and the microscopic characteristics of the system. By \\

S. I. Lebedeva; G. A. Romanova; A. A. Kazakov

1969-01-01

155

Finite element formulation using magnetic vector potential approach: effects of displacement current in magneto-electro-elastic cylindrical shells  

NASA Astrophysics Data System (ADS)

Displacement current is associated with the generation of magnetic fields due to time-varying electric fields. The harmonic response of a magneto-electro-elastic axisymmetric cylinder accounting for displacement current is carried out using the semi-analytical finite element method. The non-conservative electric field is represented using a magnetic vector potential. Studies are carried out for the first circumferential harmonics of the shell structure with the clamped-free boundary condition. The contribution made to the magnetic flux density by the electric displacement current is very small at lower frequencies but it becomes significant at higher frequencies.

Biju, B.; Ganesan, N.; Shankar, K.

2010-01-01

156

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

157

Emergence of magnetic field due to spin-polarized baryon matter in neutron stars  

E-print Network

A model of the ferromagnetic origin of magnetic fields of neutron stars is considered. In this model, the magnetic phase transition occurs inside the core of neutron stars soon after formation. However, owing to the high electrical conductivity the core magnetic field is initially fully screened. We study how this magnetic field emerges for an outside observer. After some time, the induced field that screens the ferromagnetic field decays enough to uncover a detectable fraction of the ferromagnetic field. We conjecture that weak fields of millisecond pulsars of 10^8-10^9 G could be identified with ferromagnetic fields of unshielded fraction f=10^-4 resulting from the decay of screening fields by a factor 1-f in 10^8 yr since their birth.

M. Kutschera

1999-07-28

158

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

E-print Network

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

Cantillon-Murphy, Padraig

159

2D Continuous Wavelet Transform of potential fields due to extended source distributions  

Microsoft Academic Search

We analyse the real Continuous Wavelet Transform 2D (CWT2D) of potential fields for the investigation of potential field singularities. We focus our attention to extended geological sources, in order to verify the reliability of this method with realistic fields. 3D space-scale representation (3D Scalogram) related to synthetic models were generated, showing the Wavelet Transform Modulus Maxima (WTMM) at each scale.

M. Fedi; F. Cella; T. Quarta; A. V. Villani

2010-01-01

160

ANALYSIS OF CATASTROPHIC FIELD FAILURES DUE TO CONDUCTIVE ANODIC FILAMENT (CAF) FORMATION  

E-print Network

and / or water soluble flux constituents. In this work, two catastrophic field failures were analyzed. Both chromatography (IC) was used to identify residue extracted from a failed board. The failure phenomena known a separated fiber / epoxy interface [1-5]. This paper will review two different field failures that were

Bennett, Gisele

161

Abrikosov-vortex-energy change due to an electric-field effect  

SciTech Connect

The influence of the electric-field effect on the Abrikosov vortex energy in high-temperature superconductors is analyzed. The dependencies of the change of the dc critical current on the electric-field magnitude and the film thickness are calculated.

Ghinovker, M. [Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel)] [Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel); Sandomirsky, V.B. [Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel)] [Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel); [Research Institute, College of Judea and Samaria, Ariel 44820 (Israel); Shapiro, B.Y. [Jack and Pearl Resnick Institute of Advanced Technology, Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel)] [Jack and Pearl Resnick Institute of Advanced Technology, Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel)

1995-04-01

162

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

PubMed Central

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

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

2014-01-01

163

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

SciTech Connect

The problem of 'far-field' sheath formation is studied with a new quantitative one-dimensional model. These radio-frequency (rf) sheaths occur when unabsorbed fast waves in the ion cyclotron range of frequencies are incident on a conducting surface not aligned with a flux surface. Use of a nonlinear sheath boundary condition gives self-consistent solutions for the wave fields and sheath characteristics, and it introduces a sheath-plasma-wave resonance which can enhance the sheath potential. The model is used to compute the parametric dependence of the far-field sheath potential. Its application to post-process the rf fields computed by a full-wave code for a typical D(H) minority heating scenario is also discussed. This work shows that two-dimensional effects (included heuristically) are essential in determining whether far-field sheath potentials are strong enough to cause significant edge interactions, such as impurity generation and reduced heating efficiency.

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

2008-10-01

164

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

NASA Astrophysics Data System (ADS)

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

Venkattraman, Ayyaswamy

2014-10-01

165

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

E-print Network

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

166

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

SciTech Connect

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

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

2008-10-01

167

Far Field Sheaths Due to Fast Waves Incident on Material Boundaries  

SciTech Connect

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

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

2007-09-28

168

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

PubMed

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

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

2014-09-01

169

Electromagnetic Field Generation in the Downstream of Electrostatic Shocks Due to Electron Trapping  

NASA Astrophysics Data System (ADS)

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 ˜104?pe-1. Electron trapping during the shock formation process creates a strong temperature anisotropy in the distribution function, giving rise to the pure Weibel instability. The generated magnetic field is well confined to the downstream region of the electrostatic shock. The shock formation process is not modified, and the features of the shock front responsible for ion acceleration, which are currently probed in laser-plasma laboratory experiments, are maintained. However, such a strong magnetic field determines the particle trajectories downstream and has the potential to modify the signatures of the collisionless shock.

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

2014-09-01

170

Helmholtz decomposition of the Lagrangian displacement  

NASA Astrophysics Data System (ADS)

Lagrangian displacement field ? is the central object in Lagrangian perturbation theory (LPT). LPT is very successful at high redshifts, but it performs poorly at low redshifts due to severe shell crossing. To understand and quantify the effects of shell crossing, we extract ? from N-body simulation and decompose it into scalar and vector parts. We find that at late time the power spectrum of the scalar part agrees with 1-loop results from LPT at large scales, while the power in small scales is much suppressed due to shell crossing. At z =0, the power spectrum of ? is 10% lower than the 1-loop results at k =0.1 Mpc-1h. Shell crossing also generates the vector contribution in ?, although its effect is subdominant in comparison with the power suppression in the scalar part. At z =0, the vector part contributes 10% to the total power spectrum of ? at k =1 Mpc-1h, while only 1% is expected from the vector contribution in LPT. We also examine the standard LPT recipes and some of its variants. In one of the variants, we include a power suppression factor in the displacement potential to take into account the power suppression in small scales after shell crossing. However, these simple phenomenological approaches are found to yield limited improvement compared to the standard LPT after the onset of shell crossing.

Chan, Kwan Chuen

2014-04-01

171

Precision displacement reference system  

DOEpatents

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

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

2000-02-22

172

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

173

A platform to study magnetic field amplification of laser driven shocks due to induced turbulence  

NASA Astrophysics Data System (ADS)

Misaligned pressure and temperature gradients associated with asymmetrical shock waves generate currents which seed magnetic fields (Biermann battery process). These fields could then be further amplified by increasing particle gyration driven by vorticity and turbulence. Studies of such phenomena have been conducted at the Rutherford Appleton Laboratory and scaled to astrophysical conditions (e.g., protogalacitc structure formation) using magnetohydrodynamic scaling techniques. Shock waves were driven in a 1 mbar Argon gas filled chamber from ablation of 500 micron Carbon rods using 300 J of 527 nm, 1 ns pulse light. A plastic grid was positioned 1 cm from the target to drive turbulence with outer scale ˜1 mm (the size of the grid opening). An induction coil, located 2 cm from the grid, was used to measure the magnetic field while optical diagnostics were used to track the fluid flow. Preliminary results and comparisons with hydrodynamic codes will be shown.

Meinecke, Jena; Doyle, Hugo; Bell, A. R.; Crowston, Robert; Drake, Paul; Fatenejad, M.; Hartley, Nick; Koenig, Michel; Kuramitsu, Y.; Kuranz, Carolyn; Lamb, Don; MacDonald, Mike; Miniati, F.; Murphy, Chris; Pelka, Alex; Ravasio, Alessandra; Reville, Brian; Sakawa, Y.; Schekochihin, A. A.; Scopatz, Anthony; Tzeferacos, Petros; Wan, Wesley; Woolsey, Nigel; Gregori, Gianluca

2012-10-01

174

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

E-print Network

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

Bezerra, V B; Muniz, C R

2014-01-01

175

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

E-print Network

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

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

2014-01-09

176

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

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

177

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

PubMed

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

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

2011-11-01

178

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

NASA Technical Reports Server (NTRS)

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

Fatuzzo, Marco; Melia, Fulvio

1991-01-01

179

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

NASA Technical Reports Server (NTRS)

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

Estes, Robert D.

1989-01-01

180

Spinmotive force due to domain wall motion in high field regime  

NASA Astrophysics Data System (ADS)

Spinmotive force associated with a moving vortex domain wall is investigated numerically. Dynamics of magnetization textures such as a domain wall exerts a non-conservative spin-force on conduction electrons [1], offering a new concept of magnetic devices [2]. This spinmotive force in permalloy nanowires has been detected by voltage measurement [3] where magnitude of the signal is limited less than 500 nV. Theoretically it is suggested that the spinmotive force signal increases as a function of external magnetic fields. At higher magnetic fields, however, the wall propagation mode becomes rather chaotic involving transformations of the wall structure and it remains to be seen how the spinmotive force appears. Numerical simulations show that the spinmotive force scales with the field even in a field range where the wall motion is no longer associated coherent precession. This feature has been tested in a recent experiment [4]. Further enhancement of the spinmotive force is explored by designing ferromagnetic nanostructures [5] and materials. [1] S. Barnes and S. Maekawa, PRL (2007). [2] S. Barnes, J. Ieda, and S. Maekawa, APL (2006). [3] S. A. Yang et al., PRL (2009). [4] M. Hayashi, J. Ieda et al., submitted. [5] Y. Yamane, J. Ieda et al., APEX (2011).

Ieda, Jun'ichi; Yamane, Yuta; Maekawa, Sadamichi

2012-02-01

181

Field monitoring and modeling of pavement response and service life consumption due to overweight truck traffic  

E-print Network

.................................................................... 6 II FIELD INSTRUMENTS AND DATA ANALYSIS.................................. 8 2.1. General............................................................................................ 8 2.2. Introduction of the WIM System... Measurement ........................................... 118 5.3.1. Analysis of Rut Bar Data...................................................... 120 5.3.2. Analysis of Roughness Data...

Oh, Jeong-Ho

2004-11-15

182

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

PubMed

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

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

1998-07-01

183

Accurate Determination of the Electromagnetic Field Due to WiMAX Base Station Antennas  

Microsoft Academic Search

A method for accurate determination of electromagnetic fields around the Worldwide Interoperability for Microwave Access (WiMAX) base stations (BSs) is developed in this paper. The influence of the characteristics of the WiMAX signal on the settings and parameters of the spectrum analyzer (SA) used for exposure assessment is investigated. Optimal settings of the SA are proposed, and the results obtained

Wout Joseph; Leen Verloock; Luc Martens

2008-01-01

184

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

Microsoft Academic Search

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

T. Janetzke; W. Nitsche; J. Täge

2008-01-01

185

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

PubMed Central

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

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

2014-01-01

186

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

PubMed

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

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

2014-01-01

187

Hidden non-Fermi-liquid behavior due to a crystal-field quartet  

SciTech Connect

We study a realistic Kondo model for crystal field quartet ground states having magnetic and nonmagnetic (quadrupolar) exchange couplings with conduction electrons, using the numerical renormalization group method. We focus on a local effect dependent on singlet excited states coupled to the quartet, which reduces the nonmagnetic coupling significantly and drives non-Fermi-liquid behavior observed in the calculated quadrupolar susceptibility. A crossover from the non-Fermi-liquid state to the Fermi-liquid state is characterized by a small energy scale very sensitive to the nonmagnetic coupling. On the other hand, the Kondo temperature observed in the magnetic susceptibility is less sensitive. The different crystal-field dependence of the two exchange couplings may be related to the different x dependence of quadrupolar and magnetic ordering temperatures in Ce{sub x}La{sub 1-x}B{sub 6}. (c) 2000 The American Physical Society.

Koga, Mikito [Department of Physics, University of California-Davis, Davis, California 95616 (United States)] [Department of Physics, University of California-Davis, Davis, California 95616 (United States)

2000-01-01

188

New experimental method of visualizing the electric field due to surface charges on circuit elements  

NASA Astrophysics Data System (ADS)

Although static surface charges on circuit elements are of enormous interest, recent papers and textbooks have only discussed the problem theoretically using analytical or numerical approaches. The only well-known experimental method to visualize the structure of electric fields around circuit elements was reported by Jefimenko almost half a century ago. In our paper, we report on a simple method to visualize the electric field produced by static surface charges on current-carrying circuit elements. Our method uses a mixture of PTFE (Teflon) sealant and mineral oil, a copper wire placed in the mixture's container, and two 6 kV power supplies. We believe that our new method can be used directly in the classroom.

Jacobs, Rebecca; de Salazar, Alex; Nassar, Antonio

2010-12-01

189

Electromagnetic field in the sea due to an omnidirectional VLF antenna  

NASA Astrophysics Data System (ADS)

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

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

1997-01-01

190

Viscous Evolution and Photoevaporation of Circumstellar Disks Due to External Far Ultraviolet Radiation Fields  

NASA Astrophysics Data System (ADS)

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 ~102-104 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 ?-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 ? = 10-3 are effectively dispersed within 1-3 Myr for higher viscosities (? = 10-2) disks are dispersed within ~0.25-0.5 Myr. Furthermore, disk radii are truncated to less than ~100 AU, which can possibly affect the formation of planets. Our model predictions are consistent with the range of observed masses and radii of proplyds in the Orion Nebula Cluster.

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

2013-09-01

191

Change in the particle action due to magnetic field perturbations in the SSC  

SciTech Connect

The motion of a particle in the linear lattice of the SSC is stable, that is, the Courant-Synder invariant (W/sub 0/) remains exactly constant and the betatron phase (psi) increase by (2..pi nu..) for every revolution around the circumference. However, when magnetic field perturbations are present around the ring, this mode of describing the motion is no longer valid. One can then still speak of action-angle variables (W,phi) which in the limit of zero perturbation reduce to the linear betatron invariant and the betatron phase. The change in phase (phi-psi) is then directly related to the perturbed betatron tune, while the change in action (W-W/sub 0/) is closely related to the idea of ''smear'' or ''change in the linear invariant.'' In this paper, consistent with these concepts, we develop the theory of particle motion for field perturbations around the machine. We confine ourselves to motion in one plane only and treat the field perturbations to first order in their strength. Based on the assumed random multipoles in the SSC dipole magnets, we then obtain an estimate of the ''linear aperture'' of the machine.

Herrera, J.C.

1986-06-01

192

Electric and Magnetic fields due to Dirac particles in FRW spacetime  

E-print Network

Some solutions of the Maxwell equations with Dirac particles for the source in FRW spacetime are discussed. The Green's function of the equation for the radial component of the Maxwell fields, F_{r\\eta} and F_{\\theta\\phi} is solved. Green's function is found to reduce to that of Minkowskian spacetime in the appropriate limit. Also, the Lienard-Wiechert type solution is derived. Also, the solutions with the Dirac particle current is also presented. It is found that the F_{r\\eta} is composed of even angular momentum states while the odd states constitue F_{\\theta\\phi} .

Sharma, S K; Khanal, U

2013-01-01

193

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

PubMed

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

Shoji, Hiroaki; Ozaki, Hisaki

2006-10-01

194

Viscous Evolution and Photoevaporation of Circumstellar Disks due to External FUV Radiation Fields  

E-print Network

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 \\sim 10^{2} - 10^{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,...

Anderson, Kassandra R; Calvet, Nuria

2013-01-01

195

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

196

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

E-print Network

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

V. Majernik

2004-08-19

197

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

PubMed

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

Montaz, Julie; Jacquot, Marion; Coeurdassier, Michaël

2014-11-01

198

Near-Field Scattering due to Topography and Lateral Velocity Heterogeneity  

NASA Astrophysics Data System (ADS)

The scattering of seismic waves traveling in the Earth is not only caused by velocity heterogeneity, but also by rough surface topography. Both factors are known to play an important role on ground motion complexity even at short distances from the source. In this study, we simulate ground motion with a 3D finite-difference wave propagation solver in the frequency band 0-5 Hz using different rough topography models and realistic heterogeneous media characterized by Von Karman correlation functions. We analyze the characteristics of the scattered wave-field, focusing in particular on coda waves. Our study shows that topography and velocity heterogeneity scattering generate coda waves with different characteristics. We notice that, while coda waves originated by velocity heterogeneity have a more diffusive nature presenting envelope broadening as a result of forward scattering, coda waves caused by topography scattering are composed of more coherent body and surface waves reflected and diffracted by irregular topography surface. Results indicate that, for shallow sources, topography scattering can generate more intense early-coda waves at short and intermediate distances from the source. As distance increases, velocity heterogeneity scattering starts to dominate. However results show a rather high degree of variability as topography scattering is very sensitive to source position and features of the topography model. On the other hand, velocity perturbations generate more intense late-coda waves We conclude that topography scattering cannot be used as a proxy for velocity heterogeneity scattering.

Imperatori, Walter; Mai, Martin

2014-05-01

199

Parallel acceleration due to the radial electric field in a magnetized plasma with low-frequency turbulence  

E-print Network

A new physical mechanism of the parallel acceleration of a turbulent magnetized plasma is discovered by using a Fokker-Planck phase space stochastic transport equation. It is found that the random walk of a charged particle is correlated with the random change of the parallel velocity due to the radial electric field and the magnetic moment conservation. This correlation leads to a parallel acceleration of the plasma with a finite parallel fluid flow.

Wang, Shaojie

2014-01-01

200

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

Microsoft Academic Search

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

Yuri Fialko

2004-01-01

201

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

SciTech Connect

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

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

2013-11-15

202

Degradation of dielectric breakdown field of thermal SiO2 films due to structural defects in Czochralski silicon substrates  

NASA Astrophysics Data System (ADS)

We used heat treatment to intentionally introduce various structural defects in Czochralski silicon substrates. The type, size, and number density of the induced defects were surveyed with transmission electron microscopy, and the defects were then incorporated into SiO2 films (10-50 nm thick) during thermal oxidation in dry O2. The effect of the defects on dielectric strength of the SiO2 films was examined with a time zero dielectric breakdown method. Larger platelet oxygen precipitates caused greater decreases of the breakdown field, and precipitates smaller than the SiO2 film thickness did not appreciably reduce the breakdown field. Every large platelet oxygen precipitate incorporated in the SiO2 film caused a degradation. Octahedral oxygen precipitates caused little degradation. The breakdown field was higher than 7 MV/cm and did not depend much on the SiO2 film thickness and precipitate size. We discussed possible mechanisms for the degradation due to both kinds of precipitates. Oxidation-induced stacking faults formed by a surface oxidation did not markedly reduce the breakdown field when only segments of dislocations and stacking faults were incorporated in the SiO2 film. Another serious degradation was caused by pits that were formed by dissolving octahedral oxygen precipitates in a HF solution. The breakdown field was lower for thicker oxide films, and it recovered as the pit shape became smoother during chemical etching. We proposed that this degradation was caused by a local thinning of SiO2 film due to stress generated in the oxidation of pits. These results suggest that voids rather than the other reported grown-in defects play the most important role in the degradation observed for as-grown silicon.

Satoh, Y.; Shiota, T.; Murakami, Y.; Shingyouji, T.; Furuya, H.

1996-05-01

203

Vertical displacements of the current sheet and Hall currents  

NASA Astrophysics Data System (ADS)

Vertical displacements of the peripheral regions of the current sheet with respect to its mean plane have been detected in the case of the sheet formation in the three-dimensional configuration with the X line and longitudinal component of the magnetic field. It has been shown that this effect is due to the generation of Hall currents and the appearance of vertically directed forces. Change in the sign of vertical displacements at the late stage of the sheet evolution has been detected, indicating the generation of opposite Hall currents when the direction of the main current near the side edges of the sheet changes. It has been shown that Hall currents significantly affect the structure of current sheets, and vertical oscillations of the peripheral regions of the current sheet, which appear owing to oppositely directed Hall currents, are involved in the dynamic processes in current sheets.

Frank, A. G.; Satunin, S. N.

2014-09-01

204

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

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

205

Optical displacement sensor  

DOEpatents

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

Carr, Dustin W. (Albuquerque, NM)

2008-04-08

206

Water displacement mercury pump  

DOEpatents

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

Nielsen, M.G.

1984-04-20

207

Water displacement mercury pump  

DOEpatents

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

Nielsen, Marshall G. (Woodside, CA)

1985-01-01

208

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

SciTech Connect

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.

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

2011-09-15

209

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

SciTech Connect

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

Sheng, I.C.; Nian, T.

1993-07-01

210

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

SciTech Connect

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

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

2011-07-01

211

Estimation of optical flow for large displacements  

Microsoft Academic Search

In this paper we present a new method to estimate optical flow for large displacements. It is based on prediction of global flow field parameters, performs better than multi- resolution estimation methods and has been verified using standard test sequences as well as real-world data. Global flow field parameters can be estimated from optical flow measurements in all flow regions.

Torsten Radtke; Horst Salzwedel

2001-01-01

212

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

NASA Astrophysics Data System (ADS)

Electron motion in a single electrostatic wave in a sheared magnetic field is shown to become stochastic in the presence of a second wave at an amplitude well below that obtained from the overlapping pendulum resonance approximation. The enhanced stochasticity occurs for low parallel velocity electrons for which the parallel trapping motion from eE(,(PARLL))/m interacts strongly with the E x B trapping motion due to the presence of magnetic shear. The guiding-center equations for single particle electron orbits in given fields are investigated using both analytical and numerical techniques. The model assumes a slab magnetic field geometry with shear and two electrostatic plane waves propagating at an angle with respect to each other. Collisions and the self-consistent effect of the electron motion upon the fields are ignored. The guiding-center motion in an inertial reference frame moving in phase with the two waves is given by a two degree-of -freedom, autonomous Hamiltonian system. The single wave particle motion may reduced to a two parameter family of one degree-of-freedom Hamiltonians which bifurcate from a pendulum phase space to a topology with three chains of elliptic and hyperbolic fixed points separated in radius about the mode-rational surface. In the presence of a perturbing wave with a different helicity, electrons in the small parallel velocity regime become stochastic at an amplitude scaling as the fourth root of the wave potential. The results obtained for stochastic motion apply directly to the problem of electron diffusion in drift waves occurring in toroidal fusion confinement devices. The effect of an adiabatically changing radial electric field upon guiding -center orbits in tokamaks is also investigated. This perturbation causes a radial polarization drift of trapped particle tokamak orbits.

Robertson, James Alexander

213

Displaced Homemakers: Unresolved Issues.  

ERIC Educational Resources Information Center

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)

Zawada, Mary Ann

1980-01-01

214

Control rod displacement  

Microsoft Academic Search

This patent describes a nuclear reactor including a core, cylindrical control rods, a single support means supporting the control rods from their upper ends in spaced apart positions and movable for displacing the control rods in their longitudinal direction between a first end position in which the control rods are fully inserted into the core and a second end position

Nakazato

1987-01-01

215

Displacement sensors using soft magnetostrictive alloys  

NASA Astrophysics Data System (ADS)

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.

Hristoforou, E.; Reilly, R. E.

1994-09-01

216

3-D Equilibrium and Magnetic Island due to Error Magnetic Field in the DIII-D Tokamak  

NASA Astrophysics Data System (ADS)

The effects of error magnetic field due to toroidal asymmetry of the external shaping coils on the 2-D equilibrium states of DIII-D discharges are studied using a perturbative approach and the VMEC 3-D equilibrium code. In the perturbative approach, the plasma is assumed to stay nearly axisymmetric and the effects of the error magnetic field on the magnetic surfaces are analyzed using the Green's function method. The results indicate that a 1-2 cm radial shift in the external coil location can produce a significant stochastic region near the plasma separatrix boundary and large magnetic islands around the outer rational q surfaces. This may explain the separatrix location differences observed between magnetic reconstructions which assume toroidal symmetry and Thomson scattering measurements of electron temperature in some DIII-D discharges. The results also indicate that the C-coil is more effective in correcting the error magnetic field at the outer rational q surfaces than at the separatrix. At high ?, the plasma response can be significant. This is analyzed using the VMEC 3-D equilibrium code.

Lao, L. L.; Chu, M. S.; Schaffer, M. J.; La Haye, R. J.; Evans, T. E.; You, K. I.; Lazarus, E. A.; Hirshman, S. P.

2002-11-01

217

New look at displacement factor and point of measurement corrections in ionization chamber dosimetry  

SciTech Connect

A new technique is presented for determination of the effective point of measurement when cavity ionization chambers are used to measure the absorbed dose due to ionizing radiation in a dense medium. An algorithm is derived relating the effective point of measurement to the displacement correction factor. This algorithm relates variations of the displacement factor to the radiation field gradient. The technique is applied to derive the magnitudes of the corrections for several chambers in a p(66)Be(49) neutron therapy beam. 30 references, 4 figures, 1 table.

Awschalom, M.; Rosenberg, I.; Ten Haken, R.K.

1983-01-01

218

Computing Displacements And Strains From Video Images  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

219

Improvement of actuation displacement of LIPCA implementing bifurcation phenomena  

NASA Astrophysics Data System (ADS)

In this work, behavior of a unimorph piezoceramic actuator, LIPCA (Lightweight Piezo-Composite Actuator) under compression has been experimentally and numerically investigated. The LIPCA composed of composite laminated tabs, piezoceramic material layer, glass/epoxy composite and carbon fiber composite layers was modeled and analyzed by using a full three-dimensional finite element modeling technique. The geometrically nonlinear analysis was used in the analysis because the LIPCA has the initial curvature due to the curing process, which acts like an initial geometric imperfection. The LIPCA was installed in the simply supported configuration and compressive load was applied in the test jig. By measuring the lateral displacement created by the compressive load, the buckling load of the LIPCA was determined. The measured buckling load agreed well with the computed linear buckling load from the finite element analysis based on the thermal analogy. As various electric fields were applied to the LIPCA under the compressive load, the lateral displacement was measured to examine behavior of the LIPCA under the compressive load and electric field at the same time. From this test, proper combinations of the compressive load and prescribed voltage could be figured out, which can create controlled buckling of the LIPCA under compression by applying the electric field. The measured data showed that the lateral displacement of the LIPCA is significantly increased when a proper electric field is prescribed to the LIPCA in addition to the pre-determined compressive load. The measured data was compared with the computed result from the geometrically nonlinear finite element analysis based on the thermal analogy. The numerical simulation agreed well with the measurement for low compressive load (< 3N) and low electric field (< 150V). The strength of the LIPCA is also calculated to make sure that the actuator can be operated without fracture.

Nguyen, Quoc Viet; Lee, Seungsik; Park, Hoon Cheol

2006-03-01

220

Displacement and Velocity Ratios  

NSDL National Science Digital Library

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

Bourassa, James; Rosz, John

2011-04-05

221

The Displaced Aggression Questionnaire  

Microsoft Academic Search

Previous measures of aggressive personality have focused on direct aggression (i.e., retaliation toward the provoking agent). An original self-report measure of trait displaced aggression is presented. Exploratory and confirmatory factor analyses provided support for a 3-factor conceptualization of the construct. These analyses identified an affective dimension (angry rumination), a cognitive dimension (revenge planning), and a behavioral dimension (general tendency to

Thomas F. Denson; William C. Pedersen; Norman Miller

2006-01-01

222

Above Water: Buoyancy & Displacement  

NSDL National Science Digital Library

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

Jersey, New; Center, Liberty S.; Coalition, New J.

2006-01-01

223

Atmospheric pressure loading displacement of SLR stations  

NASA Astrophysics Data System (ADS)

This paper addresses the local displacement at ground stations of the world-wide Satellite Laser Ranging (SLR) network induced by atmospheric pressure variations. Since currently available modelling options do not satisfy the requirements for the target application (real-time availability, complete coverage of SLR network), a new representation is developed. In a first step, the 3-dimensional displacements are computed from a 6-hourly grid of 1°×1° global pressure data obtained from the ECMWF, for the period 1997-2002. After having been converted into pressure anomalies, this pressure grid is propagated into horizontal and vertical station displacements using Green's functions and integrating contributions covering the entire globe; oceans are assumed to follow the inverted barometer (IB) approximation. In the next step, a linear regression model is developed for each station that approximates the time-series of the predicted vertical displacements as well as possible; this regression model relates the vertical displacement of a particular station to the local (and instantaneous) pressure anomaly. It is shown that such a simple model may represent the actual vertical displacements with an accuracy of better than 1 mm; horizontal displacements are shown to be negligible. Finally, the regression model is tested on actual SLR data on the satellites LAGEOS-1 and LAGEOS-2, covering the period January 2002 until April 2003 (inclusive). Also, two model elements are shown to be potential risk factors: the global pressure field representation (for the convolution method) and the local reference pressure (for the regression method). The inclusion of the atmospheric pressure displacement model gives improvements on most of the elements of the computations, although the effects are smaller than expected since the nominal effect is absorbed by solved-for satellite parameters.

Bock, D.; Noomen, R.; Scherneck, H.-G.

2005-04-01

224

Experimental investigation of local displacement speeds of wrinkled unsteady flames  

NASA Astrophysics Data System (ADS)

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

Sinibaldi, Jose Oscar

225

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

SciTech Connect

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

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

2006-02-01

226

Numerical computation of in-plane displacements and their detection in the near field by double-exposure objective speckle photography  

Microsoft Academic Search

A model of a rough surface to the scale of the optical wavelength is proposed, with randomly distributed zero-mean Gaussian heights. It is assumed that the aforesaid surface is illuminated by a coherent light beam of homogeneous intensity. An in-plane pure translation of this surface is simulated on a PC by means of the Matlab program. In the near-field optical

Francisco Gascón; Félix Salazar

2008-01-01

227

Displacement cascades in polyatomic materials  

SciTech Connect

Using a continuous-slowing-down, random amorphous material model, we have studied displacement cascades in a number of diatomic materials. This paper reviews a number of previous results that elucidate the effects of atomic mass, recoil energy, displacement energy, capture energy and material stoichiometry on the numbers of displacements in a cascade. The displacement cascade reveals a complex structure that is dependent on the type of irradiation and the material properties. Conclusions related to damage analysis for fusion reactors are given.

Parkin, D.M.; Coulter, C.A.

1982-01-01

228

Crack-opening displacement transducer  

NASA Technical Reports Server (NTRS)

Crack-opening displacement transducer consists of 30 deg cone, coil spring, and linear-displacement transducer. Conical probe is used to measure crack opening. Cone is pressed firmly into crack by spring. As applied load causes crack to open up, cone is pushed further into it. Movement of cone, and thus crack growth, is monitored by linear-displacement transducer. Method gives more accurate measurement of crack-opening displacement of very narrow slots.

Simonds, R. A.

1980-01-01

229

Polyimidazoles via aromatic nucleophilic displacement  

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

230

Monitoring Changes in Soil Water Content Using Subsurface Displacement  

NASA Astrophysics Data System (ADS)

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 ?m/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 ?m, 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 groundwater recharge in playas. Two other extensometers were deployed in loess at a field site near Holdredge, NE, where they will be used to help characterize water cycling beneath irrigated agriculture. Calibration data has been obtained and the instruments appear to be functioning properly. The preliminary data suggest that the DELTA technique should be applicable in a variety of soil types.

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

2013-12-01

231

An ion displacement membrame model.  

PubMed

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

Hladky, S B; Harris, J D

1967-09-01

232

Enhanced electro-magnetic energy transfer between a hot and cold body at close spacing due to evanescent fields  

SciTech Connect

Theoretical studies have demonstrated that the energy transfer between a hot and cold body at close spacing (on the order of the radiation wavelength) can greatly exceed the limit for black body radiation (ie, Power = {sigma}T{sup 4}). This effect, due to the coupling of evanescent fields, presents an attractive option for thermo-photovoltaic (TPV) applications (assuming the considerable technical challenges can be overcome). The magnitude of the enhanced energy transfer depends on the optical properties of the hot and cold bodies as characterized by the dielectric functions of the respective materials. The present study considers five different situations as specified by the materials choices for the hot/cold sides: metal/metal, metal/insulator, metal/semiconductor, insulator/insulator, and semiconductor/semiconductor. For each situation, the dielectric functions are specified by typical models. An increase in energy transfer (relative to the black body law) is found for all situations considered, for separations less than one micron, assuming a temperature difference of 1,000 C. The metal/metal situation has the highest increase vs. separation while the semiconductor/semiconductor has the lowest. Factor-of-ten increases are obtained at roughly 0.1 microns for the metal/metal and roughly 0.02 microns for the metal/semiconductor. These studies are helping to increase the understanding of the close-spaced effect in the context of a radiator/TPV context.

Raynolds, J.E. [Lockheed Martin Corp., Schenectady, NY (United States)

1998-10-01

233

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

NASA Technical Reports Server (NTRS)

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

Hill, Charles S.; Oliveras, Ovidio M.

2011-01-01

234

Angular displacement measuring device  

NASA Technical Reports Server (NTRS)

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.

Seegmiller, H. Lee B. (inventor)

1992-01-01

235

Adapting to variable prismatic displacement  

NASA Technical Reports Server (NTRS)

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

Welch, Robert B.; Cohen, Malcolm M.

1989-01-01

236

Numerical Stimulation of Radiant Floor Heating with Displacement Ventilation  

Microsoft Academic Search

Radiant floor heating has received the increasing attention due to the wide advantages, especially the energy saving as compared to the conventional air-conditioning system. This study presents a numerical investigation of radiant floor heating with the displacement ventilation in the room. The air isotherms and flow patterns with and without displacement ventilation, as well as the heat fluxes along the

Liu Xianglong; Gong Guangcai

2010-01-01

237

Holographic contouring by displacing the object and the illumination beam  

Microsoft Academic Search

A contouring technique based on a double exposure hologram is described. Between the two exposures both the illumination source and the object are displaced. The contour fringes originate from the moiré pattern due to the superposition of the fringe patterns resulting from the two displacements. Experimental results are given.

P. Demattia; V. Fossati-Bellani

1978-01-01

238

Estimating Displacement of Periodic Motion With Inertial Sensors  

PubMed Central

Inertial sensors, like accelerometers and gyroscopes, are rarely used by themselves to measure displacement. Accuracy of inertial sensors is greatly handicapped by the notorious integration drift, which arises due to numerical integration of the sensors zero bias error. A solution is proposed in this paper to provide drift free estimation of displacement from inertial sensors. PMID:19924267

Tan, U-Xuan; Veluvolu, Kalyana C.; Latt, Win Tun; Shee, Cheng Yap; Riviere, Cameron N.; Ang, Wei Tech

2009-01-01

239

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)

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 determine the type of geochronology that we will utilize. Both locations are moderately vegetated and likely to yield organic-rich deposits ideal for radiocarbon dating. If sand units are present, we may also use optically stimulated luminescence (OSL) dating, because of the potential for multiple dating techniques to strengthen the age determinations.

Barr, M. A.; Cowgill, E.

2013-12-01

240

Anomalous and classical diffusion of cosmic rays due to nonlinear two-dimensional structures and random magnetic fields  

Microsoft Academic Search

Magnetic field turbulence in the heliosphere is modeled by two-dimensional coherent vortex structures and random-phase linear wave fields added to a background magnetic field. Energetic particle trapping and acceleration by interaction with the turbulent fields are studied numerically. The corresponding radial and field-aligned diffusion coefficients are estimated. Different diffusion regimes (subdiffusion, superdiffusion, classical diffusion) are controlled by the following parameters:

O. P. Verkhoglyadova; J. A. le Roux

2005-01-01

241

Variable displacement blower  

DOEpatents

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

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

1986-01-01

242

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

243

Calculation of Crystallographic Texture due to Displacive Transformations  

E-print Network

of Cambridge, Materials Science and Metallurgy, Cambridge, U.K. Universidade Federal do Cear´a, Engenharia Cerjak who has had a life­long and deep interest in metallurgy. As a gentleman and a scholar, he finds

Cambridge, University of

244

Sensitivity analysis of sub-pixel correlation technique for measuring coseismic displacements using a pair of ASTER images  

NASA Astrophysics Data System (ADS)

Coseismic displacements play a key role in understanding earthquake dynamics. To derive displacement fields from optical and microwave remote sensing datasets, various methods are available. This study evaluated in detail the offset tracking technique on optical ASTER data for 2005 Kashmir earthquake. This technique required input parameters like resampling methods, correlator types, window sizes and step sizes. For accurate displacement field calculation, careful selection of these parameters is imperative which depends on the study area and dataset characteristics. In the study, we made relative comparisons of coseismic displacement fields calculated by using different combinations of input parameters. The results were validated by field based displacement data of vertical separation. Validation was based on the hypothesis that horizontal displacement component may also have vertical component contribution depending upon local characteristics of the fault. Validation results showed that general trend of the measured displacements was in agreement with the field data. Field measurements were bounded within the uncertainty limits of the technique however at some locations significant deviations were also observed. All the coseismic displacement results obtained by using different input parameter were within the uncertainty limit ±1/10 of the pixel size, except for window size 4 × 4 and 8 × 8. The measured component of the fault rupture for northwest of Muzaffarabad is irregular. It may be due to rugged topography as compared to southeast part. The measured fault rupture also coincided to surface rupture mapped in the field. Analysis of the results showed that in comparison to standard parameter set, defined in the literature (Sinc resampling method, Frequential correlator with window size 32 × 32 and step size 8), selection of resampling method and correlator type had no significant effect on the calculated displacement field. However, window size and step size were found to be the most important parameters of the technique. This study showed that changing the window size does not affect the detection limit of the technique but induces bias in the calculations. Step size is used in relation to window size, however relatively larger step size is found to provide better sensitivity and accuracy of the technique.

Yaseen, Muhammad; Anwar, Salma

2013-01-01

245

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

246

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

PubMed Central

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

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

2012-01-01

247

Polar twilight UV-visible radiation field: Perturbations due to multiple scattering, ozone depletion, stratospheric clouds, and surface albedo  

SciTech Connect

The polar twilight atmosphere is different from that at mid-latitude in several ways which lead to significant changes in the wavelength-dependent radiation field. Ozone depletion in the stratosphere leads to increased scattering below 340 nm. Polar stratospheric clouds produce changes in the radiation field which depend on cloud height and thickness. A surface albedo near unity produces a large increase in scattering. Multiple scattering becomes a larger percentage of the radiation field as solar zenith angle increases. These perturbations on the radiation field lead to enhanced ozone destruction in the stratosphere, increased surface irradiance, and a significant wavelength-dependent increase in nadir radiance.

Anderson, D.E., Jr. (Naval Research Lab., Washington, DC (United States)); Lloyd, S.A. (Harvard Univ., Cambridge, MA (United States))

1990-05-20

248

Unsteady flow simulations in a three-lobe positive displacement blower  

NASA Astrophysics Data System (ADS)

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

Liu, Xiaomin; Lu, Jun

2014-05-01

249

Polar twilight UV-visible radiation field: Perturbations due to multiple scattering, ozone depletion, stratospheric clouds, and surface albedo  

Microsoft Academic Search

The polar twilight atmosphere is different from that at mid-latitude in several ways which lead to significant changes in the wavelength-dependent radiation field. Ozone depletion in the stratosphere leads to increased scattering below 340 nm. Polar stratospheric clouds produce changes in the radiation field which depend on cloud height and thickness. A surface albedo near unity produces a large increase

Anderson D. E. Jr; Steven A. Lloyd

1990-01-01

250

LETTER TO THE EDITOR: A simple equation describing the arc movement due to gas streams and magnetic fields  

Microsoft Academic Search

A differential equation for the arc shape is proposed which accounts for three factors which influence the column motion: (i) magnetic fields, (ii) gas flows and (iii) asymmetrical Joule heating. The physical conditions required for the validity of the equation are outlined. The equation is given in a vector form suitable for treating cases with arbitrary field and discharge geometries.

B. E. Djakov; I. Nedelkov

1974-01-01

251

Displacement, Substitution, Sublimation: A Bibliography.  

ERIC Educational Resources Information Center

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…

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

252

CHARACTER DISPLACEMENT IN POLYPHENIC TADPOLES  

Microsoft Academic Search

Biologists have long known that closely related species are often phenotypically different where they occur together, but are indistinguishable where they occur alone. The causes of such character displacement are controversial, however. We used polyphenic spadefoot toad tadpoles (Spea bombifrons and S. multiplicata) to test the hypothesis that character displacement evolves to minimize competition for food. We also sought to

David W. Pfennig; Peter J. Murphy

2000-01-01

253

FDTD Simulation Based on Spark Resistance Formula for Electromagnetic Fields due to Spark between Charged Metal Bars with Ferrite Core Attachment  

NASA Astrophysics Data System (ADS)

The electromagnetic fields emitted from an electrostatic discharge (ESD) event occurring between charged metals cause seriously damage high-tech equipment. In order to clarify the generation mechanism of such ESD fields and also to reduce them, we previously proposed a finite-difference time-domain (FDTD) algorithm based on a delta-gap feeding method and a frequency dispersion characteristic formula (Naito's formula) of ferrite material for simulating the ESD fields due to a spark between the charged metals with ferrite core attachment. In the present study, by integrating the above FDTD algorithm and a spark-resistance formula, we simulated both of the ESD itself and the resultant fields for the metal bars with ferrite core attachment, and demonstrated that the core attachment close to the spark gap suppresses the magnetic field level. This finding was also validated via 6-GHz wide-band measurement of the magnetic near-field.

Taira, Soichiro; Fujiwara, Osamu

254

Displacement of large-scale open solar magnetic fields from the zone of active longitudes and the heliospheric storm of November 3-10, 2004: 2. "Explosion" of singularity and dynamics of sunspot formation and energy release  

NASA Astrophysics Data System (ADS)

A more detailed scenario of one stage (August-November 2004) of the quasibiennial MHD process "Origination ... and dissipation of the four-sector structure of the solar magnetic field" during the decline phase of cycle 23 has been constructed. It has been indicated that the following working hypothesis on the propagation of an MHD disturbance westward (in the direction of solar rotation) and eastward (toward the zone of active longitudes) with the displacement of the large-scale open solar magnetic field (LOSMF) from this zone can be constructed based on LOSMF model representations and data on sunspot formation, flares, active filaments, and coronal ejections as well as on the estimated contribution of sporadic energy release to the flare luminosity and kinetic energy of ejections: (1) The "explosion" of the LOSMF singularity and the formation in the explosion zone of an anemone active region (AR), which produced the satellite sunspot formation that continued west and east of the "anemone," represented a powerful and energy-intensive source of MHD processes at this stage. (2) This resulted in the origination of two "governing" large-scale MHD processes, which regulated various usual manifestations of solar activity: the fast LOSMF along the neutral line in the solar atmosphere, strongly affecting the zone of active longitudes, and the slow LOSMF in the outer layers of the convection zone. The fronts of these processes were identified by powerful (about 1031 erg) coronal ejections. (3) The collision of a wave reflected from the zone of active longitudes with the eastern front of the hydromagnetic impulse of the convection zone resulted in an increase in LOSMF magnetic fluxes, origination of an active sector boundary in the zone of active longitudes, shear-convergent motions, and generation and destabilization of the flare-productive AR 10696 responsible for the heliospheric storm of November 3-10, 2004.

Ivanov, K. G.

2010-12-01

255

Displacement cascades in diatomic materials  

SciTech Connect

A new function, the specified-projectile displacement function p/sub ijk/ (E), is introduced to describe displacement cascades in polyatomic materials. This function describes the specific collision events that produce displacements and hence adds new information not previously available. Calculations of p/sub ijk/ (E) for MgO, Al/sub 2/O/sub 3/ and TaO are presented and discussed. Results show that the parameters that have the largest effect on displacement collision events are the PKA energy and the mass ratio of the atom types in the material. It is further shown that the microscopic nature of the displacement events changes over the entire recoil energy range relevant to fusion neutron spectra and that these changes are different in materials whose mass ratio is near one than in those where it is far from one.

Parkin, D.M.; Coulter, C.A.

1981-01-01

256

Rotation dependence of a phase delay between plasma edge electron density and temperature fields due to a fast rotating, resonant magnetic perturbation field  

SciTech Connect

Measurements of the plasma edge electron density n{sub e} and temperature T{sub e} fields during application of a fast rotating, resonant magnetic perturbation (RMP) field show a characteristic modulation of both, n{sub e} and T{sub e} coherent to the rotation frequency of the RMP field. A phase delay PHI between the n{sub e}(t) and T{sub e}(t) waveforms is observed and it is demonstrated that this phase delay PHI is a function of the radius with PHI(r) depending on the relative rotation of the RMP field and the toroidal plasma rotation. This provides for the first time direct experimental evidence for a rotation dependent damping of the external RMP field in the edge layer of a resistive high-temperature plasma which breaks down at low rotation and high resonant field amplitudes.

Stoschus, H.; Schmitz, O.; Frerichs, H.; Unterberg, B.; Abdullaev, S. S.; Clever, M.; Coenen, J. W.; Kruezi, U.; Schega, D.; Samm, U. [Forschungszentrum Juelich GmbH, Institute for Energy Research--Plasma Physics, Association EURATOM-FZJ, Partner in the Trilateral Euregio Cluster, 52425 Juelich (Germany); Jakubowski, M. W. [Forschungszentrum Juelich GmbH, Institute for Energy Research-Plasma Physics, Association EURATOM-FZJ, Partner in the Trilateral Euregio Cluster, 52425 Juelich (Germany)] [Max Planck Institute for Plasma Physics, Association IPP-EURATOM, 17491 Greifswald (Germany)

2010-06-15

257

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

National Technical Information Service (NTIS)

Electron motion in a single electrostatic wave in a sheared magnetic field is shown to become stochastic in the presence of a second wave at an amplitude well below that obtained from the overlapping pendulum resonance approximation. The enhanced stochast...

J. A. Robertson

1986-01-01

258

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

Microsoft Academic Search

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

A. W. Guy

1968-01-01

259

Continuous Displacement Formulation of Alloys  

NASA Astrophysics Data System (ADS)

The conventional permutational statistics of cooperative phenomena is extended to include displacement of atoms from their reference lattice points. The formulation is done in the cluster variation method (CVM) framework, by changing summations in energy and entropy to integrals. It is demonstrated for the pair approximation of CVM on phase-separating fcc binary alloys. The treatment can take into account local lattice distortion due to atomic size difference, the elastic effects, and the pressure effects. To compare stability of states under pressure, the grand potential ?( T, V, { ? i}) is extended to Z( T, p, { ? i}) by a Legendre transform. Although the new function Z( T, p, { ? i}) vanishes in equilibrium, and is called the ZERO-potential in the paper, it remains nonzero and is used to determine the coexisting phases when the chemical potentials are modified. Numerical calculations are done using the natural iteration technique on model inter-atomic potentials of the Lennard-Jones type. The numerical results of using ?( T, V, { ? i}) and Z( T, p, { ? i}) potentials for phase-separating diagrams, for composition and pressure dependence of the lattice constant, and for the bulk modulus are reported and discussed.

Kikuchi, Ryoichi

1999-06-01

260

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

261

Prediction of the sound field into high-rise building facades due to its balcony ceiling form  

Microsoft Academic Search

This study presents the acoustic performance off tall building facades closed to roadway due to one of balcony configurations, namely ceiling, with an inclined form in terms of traffic noise reduction. Three inclined angles are tested (5,10, and 15°) with different balcony depths by using a Pyramid Tracing model developed by A. Farina. The results in terms of A-weighted sound

H. Hossam El Dien; P. Woloszyn

2004-01-01

262

Potash refinery plants have never been fully simulated due to their complexity. Many experts in the field believe that the  

E-print Network

Objectives Analysis Results ·Potash refinery plants have never been fully simulated due existing and future potash plants. ·Develop an end to end simulation model using the building blocks. ·Identify bottlenecks in the plant processes, alleviate flow issues, and determine if the ROI

263

Transient electrical field characteristics due to polarization of domains in bulk LiNbO3 during Czochralski growth  

NASA Astrophysics Data System (ADS)

The transient behavior of the electric field during simultaneous growth and in situ poling of LiNbO3 has been studied. The transient features have been correlated with the poling of the multidomain seed and crystal, and domain reversal in poled seed. A steady-state condition is obtained after the shoulder region of the crystal is terminated and the crystal reaches its final diameter. Finally, the critical values of field parameters necessary to obtain complete monodomain crystals without causing melt electrolysis at the solid-liquid interface have been analyzed.

Bermúdez, V.; Dutta, P. S.; Serrano, M. D.; Diéguez, E.

1997-01-01

264

Magnetic field effects on the properties of GaAs quantum dot qubit due to electron-phonon interactions  

NASA Astrophysics Data System (ADS)

We investigate the influence of magnetic field on the electron charge qubit in a GaAs single-electron semiconductor quantum dot (QD) including electron-LO-phonon interaction. We analytically and numerically evaluate decoherence time by applying the Lee-Low-Pines-Huybrecht (LLPH) variational calculation considering all coupling strengths. At the same time, the time evolution of the electron probability density is obtained, the dependence of decoherence time and the period of oscillation on the magnetic field strength and the size of QD is investigated. The results are expected to play an important role in designing the solid-state implementation of quantum computing.

Chen, Shi-Hua

2014-11-01

265

Regenerative rotary displacer Stirling engine  

SciTech Connect

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.

Isshiki, Naotsugu; Watanabe, Hiroichi [Nihon Univ. Tokyo (Japan); Raggi, L. [Waseda Univ., Tokyo (Japan); Isshiki, Seita; Hirata, Koichi

1996-12-31

266

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

ERIC Educational Resources Information Center

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

Levitan, Sar A.; Mangum, Stephen L.

267

Singlet-triplet oscillations of spin-correlated radical pairs due to the Larmor precession in low magnetic fields  

NASA Astrophysics Data System (ADS)

Singlet-triplet oscillations in spin-correlated radical pairs have been studied at magnetic field strengths low for one radical and high for the other. Oscillations with frequencies close to the Larmor frequency ?0 of electron spin precession have been predicted under these conditions. Both numerical and exact analytical solutions in arbitrary magnetic fields are presented for three cases of hyperfine couplings in wide-spectrum radical. For the case of unresolved spectrum, singlet-triplet evolution was found to contain a single oscillating term with frequency ?0 . In the case of one spin- I magnetic nucleus, there are two low frequency oscillating terms with frequencies ?- = ?0 - ?0 /(2 I + 1) and ?+ = ?0 + ?0 /(2 I + 1), the amplitude of the first term being larger than that of the second. The case of a number of equivalent protons also has been analysed as a superposition of one-nucleus oscillations. The predicted oscillations were observed in a time resolved magnetic field effect for several radical ion pairs produced by Xray irradiation of alkane solutions with charge acceptors. For pairs ( p -terphenyl- d 14 ) -. /(isooctane)+ . and ( p -terphenyl- d 14 ) -. /(2,4-dimethylpentane) +. the oscillation frequency in a field B 0 of 0.5-4 mT is about 20% lower than ?0 . Oscillations were observed also in pairs with equivalent nuclei( p -terphenyl- d 14 ) +. /(C 6 F 6 )- . and ( p -terphenyl- d 14 ) -. /(hexamethylethane) =. .

Bagryansky, V. A.; Borovkov, V. I.; Molin, Yu. N.

268

Statistical characterization of bed roughness due to bed forms: A field study in the Elbe River at Aken, Germany  

Microsoft Academic Search

Bed form geometry and dynamics in a straight section of the Elbe River in Germany is analyzed considering the measured bed surfaces as two-dimensional random fields of bed elevations. Statistically derived roughness parameters are evaluated from high-resolution digital elevation models, which were available for a range of flow rates from low flows to floods. The key results relate to the

J. Aberle; V. Nikora; M. Henning; B. Ettmer; B. Hentschel

2010-01-01

269

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

NASA Astrophysics Data System (ADS)

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

Uyeda, Chiaki; Hisayoshi, Keiji

270

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

Microsoft Academic Search

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

K. M. Creer

1962-01-01

271

Borehole optical lateral displacement sensor  

DOEpatents

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

Lewis, R.E.

1998-10-20

272

Displacement of bilirubin from albumin by berberine.  

PubMed

A study was made of the effect of berberine, the major ingredient of the Chinese herb huanglian (coptis chinensis) reported to pose some risk for kernicterus among jaundiced newborn Chinese infants, on the protein binding of bilirubin, using the peroxidase kinetic method. Berberine was found in vitro, as to its displacing effect on a molar basis, to be about tenfold superior to phenylbutazone, a known potent displacer of bilirubin, and about hundredfold to papaverine, a berberine-type alkaloid. The chronic intraperitoneal administration of berberine (10 and 20 micrograms/g) daily for 1 week to adult rats (mixed breed of Wistar and Sprague-Dawley) resulted in a significant decrease in mean bilirubin serum protein binding, due to an in vivo displacement effect and a persistent elevation in steady-state serum concentrations of unbound and total bilirubin, possibly due to inhibition of metabolism. The use of the herb and other traditional Chinese medicines containing a high proportion of berberine is best avoided in jaundiced neonates and pregnant women. PMID:8513024

Chan, E

1993-01-01

273

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

Microsoft Academic Search

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

Akimasa Hirata

2005-01-01

274

Superconducting inductive displacement detection of a microcantilever  

E-print Network

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

Vinante, Andrea

2014-01-01

275

Experimental Validation of Displacement Underestimation in ARFI Ultrasound  

PubMed Central

Acoustic radiation force impulse (ARFI) imaging is an elastography technique that uses ultrasonic pulses to both displace and track tissue motion. Previous modeling studies have shown that ARFI displacements are susceptible to underestimation due to lateral and elevational shearing that occurs within the tracking resolution cell. In this study, optical tracking was utilized to experimentally measure the displacement underestimation achieved by acoustic tracking using a clinical ultrasound system. Three optically translucent phantoms of varying stiffness were created, embedded with sub-wavelength diameter microspheres, and ARFI excitation pulses with F/1.5 or F/3 lateral focal configurations were transmitted from a standard linear array to induce phantom motion. Displacements were tracked using confocal optical and acoustic methods. As predicted by earlier FEM studies, significant acoustic displacement underestimation was observed for both excitation focal configurations; the maximum underestimation error was 35% of the optically measured displacement for the F/1.5 excitation pulse in the softest phantom. Using higher F/#, less tightly focused beams in the lateral dimension improved accuracy of displacements by approximately 10 percentage points. This work experimentally demonstrates limitations of ARFI implemented on a clinical scanner using a standard linear array and sets up a framework for future displacement tracking validation studies. PMID:23858054

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

2014-01-01

276

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

277

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

E-print Network

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

O. Petruk

2008-07-12

278

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

PubMed

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

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

2009-12-01

279

Trends in the F2 ionospheric layer due to long-term variations in the Earth's magnetic field  

Microsoft Academic Search

The Earth's magnetic field presents long-term variations with changes in strength and orientation. Particularly, changes in the dip angle (I) and, consequently, in the sin(I)cos(I) factor, affect the thermospheric neutral winds that move the conducting plasma of the ionosphere. In this way, a lowering or lifting of the F2-peak (hmF2) is induced together with changes in foF2, depending on season,

Ana G. Elias

2009-01-01

280

Localization Errors in MR Spectroscopic Imaging due to the Drift of the Main Magnetic Field and their Correction  

PubMed Central

PURPOSE To analyze the effect of B0 field drift on multi voxel MR spectroscopic imaging and to propose an approach for its correction. THEORY AND METHODS It is shown, both theoretically and in a phantom, that for ~30 minute acquisitions a linear B0 drift (~0.1 ppm/hour) will cause localization errors that can reach several voxels (centimeters) in the slower varying phase encoding directions. An efficient and unbiased estimator is proposed for tracking the drift by interleaving short (~T2*), non-localized acquisitions on the non-suppressed water each TR, as shown in 10 volunteers at 1.5 and 3 T. RESULTS The drift is shown to be predominantly linear in both the phantom and the volunteers at both fields. The localization errors are observed and quantified in the phantom. The unbiased estimator is shown to reliably track the instantaneous frequency in-vivo despite only using a small portion of the FID. CONCLUSION Contrary to single-voxel MR spectroscopy, where it leads to line broadening, field drift can lead to localization errors in the longer chemical shift imaging experiments. Fortunately, this drift can be obtained at a negligible cost to sequence timing, and corrected for in post processing. PMID:23165750

Tal, Assaf; Gonen, Oded

2012-01-01

281

Literature Review of Displacement Ventilation  

E-print Network

of Ventilated Rooms, Oslo, Norway. Nielsen, P.V., Hoff, L., Pedersen, L.G. 1988. Displacement Ventilation by Different Types of Diffusers. Proceedings of the 9 th AIVC Conference, Warwick. Niu, J. 1994. Modeling of Cooled-Ceiling Air-Conditioning Systems Ph... slender cylinder in a ventilated room. Proceedings of ROOMVENT ?90: International Conference on Engineergin Aero- and Thermodynamics of Ventilated Rooms, Oslo, Norway. This paper deals with some of the effects of persons present in a displacement...

Cho, S.; Im, P.; Haberl, J. S.

282

Atmospheric measurements of hydroperoxides and aldehydes during field campaigns : new results due to improvement of measurements techniques  

NASA Astrophysics Data System (ADS)

Hydroperoxides and aldehydes are considered as atmospheric reservoirs of OH, HO_2 and RO_2 radicals and can reflect the oxidizing levels of the atmosphere. They are considered as important gas phase photo-oxidants present in the atmosphere. However, the atmospheric role of these compounds can vary from one species to another, therefore it is essential to investigate their measurement and speciation in the atmosphere. Atmospheric measurements were realized during two different field campaigns in the Marseilles area (France). Hydroperoxides were trapped in aqueous phase, with a glass coil and analyzed by HPLC/fluorescence detector with post column derivatization. Aldehydes were trapped in a liquid phase containing 2-4 DNPH, with a mist chamber and analyzed by HPLC/UV. The analytical techniques provided individual separation and quantification of seven hydroperoxides (hydrogen peroxide, hydroxymethyl hydroperoxide, bis(hydroxymethyl) peroxide, 1-hydroxyethyl hydroperoxide, methyl hydroperoxide, ethyl hydroperoxide and peroxyacetic acid) and eleven volatile aldehydes (formaldehyde, acetaldehyde, acrolein, acetone, propionaldehyde, crotonaldehyde, butyraldehyde, benzaldehyde, glyoxal, valeraldehyde and methylglyoxal). The first field campaign was part of the ESCOMPTE project (June 4th to July 16th 2001). During this campaign five different sampling sites, at low altitudes (<= 285 m), were investigated (maritime, urban, sub-industrial, biogenic and rural sites) and atmospheric measurements were realized during photochemical air pollution events. The second field campaign was part of the BOND project (July 2nd to July 14th 2002). Atmospheric measurements of hydroperoxides were carried out on one biogenic site, at altitude 690 m. The measurement system was improved allowing online sampling and analysis. During these field campaigns collection efficiencies were better than 96% for hydroperoxides, and from 78% to 96% for aldehydes. Detection limits were between 7,3× 10-3 ?g.m-3 and 2,4× 10-1 ?g.m-3 with standard deviations from 4% to 22% for hydroperoxides and between 0,55 ?g.m-3 and 2,5 ?g.m-3 with standard deviation from 8% to 29% for aldehydes. The results show that hydroperoxide concentrations were high, when the levels of NOx were low. Aldehyde concentrations were very high during photochemical events and both primary and secondary aldehydes were identified.

François, S.; Sowka, I.; Poulain, L.; Monod, A.; Wortham, H.

2003-04-01

283

Attraction between particles at a liquid interface due to the interplay of gravity- and electric-field-induced interfacial deformations.  

PubMed

In a previous study, we established that the attraction between electrically charged particles attached to a water/tetradecane interface is stronger than predicted on the basis of the gravity-induced lateral capillary force. Here, our goal is to explain this effect. The investigated particles are hydrophobized glass spheres of radii between 240 and 320 microm. Their weight is large enough to deform the liquid interface. The interfacial deformation is considerably greater for charged particles because of the electrodipping force that pushes the particles toward the water phase. By independent experiments with particles placed between two electrodes, we confirmed the presence of electric charges at the particle/tetradecane interface. The theoretical analysis shows that if the distribution of these surface charges is isotropic, the meniscus produced by the particle electric field decays too fast with distance and cannot explain the experimental observations. However, if the surface-charge distribution is anisotropic, it induces a saddle-shaped deformation in the liquid interface around each particle. This deformation, which is equivalent to a capillary quadrupole, decays relatively slow. Its interference with the gravity-induced isotropic meniscus around the other particle gives rise to a long-range attractive capillary force, F approximately 1/L3 (L=interparticle distance). The obtained agreement between the experimental and theoretical curves, and the reasonable values of the parameters determined from the fits, indicate that the observed stronger attraction in the investigated system can be really explained as a hybrid interaction between gravity-induced "capillary charges" and electric-field-induced "capillary quadrupoles". PMID:19719220

Boneva, Mariana P; Danov, Krassimir D; Christov, Nikolay C; Kralchevsky, Peter A

2009-08-18

284

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

PubMed Central

Blood-oxygenation-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is currently the dominant technique for non-invasive investigation of brain functions. One of the challenges with BOLD fMRI, particularly at high fields, is compensation for the effects of spatiotemporally varying magnetic field inhomogeneities (?B0) caused by normal subject respiration, and in some studies, movement of the subject during the scan to perform tasks related to the functional paradigm. The presence of ?B0 during data acquisition distorts reconstructed images and introduces extraneous fluctuations in the fMRI time series that decrease the BOLD contrast-to-noise ratio. Optimization of the fMRI data-processing pipeline to compensate for geometric distortions is of paramount importance to ensure high quality of fMRI data. To investigate ?B0 caused by subject movement, echo-planar imaging scans were collected with and without concurrent motion of a phantom arm. The phantom arm was constructed and moved by the experimenter to emulate forearm motions while subjects remained still and observed a visual stimulation paradigm. These data were then subjected to eight different combinations of preprocessing steps. The best preprocessing pipeline included navigator correction, a complex phase regressor, and spatial smoothing. The synergy between navigator correction and phase regression reduced geometric distortions better than either step in isolation, and preconditioned the data to make them more amenable to the benefits of spatial smoothing. The combination of these steps provided a 10% increase in t-statistics compared to only navigator correction and spatial smoothing, and reduced the noise and false activations in regions where no legitimate effects would occur. PMID:19695810

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

2009-01-01

285

Dispersive effects of transverse displacements of SLC Arc magnets  

SciTech Connect

The SLC Arc magnets are subject to random displacements and field errors resulting in unpredictable transverse displacement of the central trajectory from that of the design. The chosen method of correcting this perturbed trajectory in the SLC Arcs utilizes mechanical movement of the combined function magnets which compose the Arc transport lines. Here we present the results of a recent investigation substantiating the earlier results which led to the adoption of this method.

Murray, J.J.; Fieguth, T.; Kheifets, S.

1986-07-23

286

Nanoliter Reactors Improve Multiple Displacement Amplification  

E-print Network

Nanoliter Reactors Improve Multiple Displacement Amplification of Genomes from Single Cells Yann) Nanoliter reactors improve multiple displacement amplification of genomes from single cells. PLoS Genet 3

Quake, Stephen R.

287

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

NASA Astrophysics Data System (ADS)

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

Zhang, Zhengrong; Jiang, Liying

2014-10-01

288

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

PubMed

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. PMID:23145596

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

2012-11-01

289

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

290

Development of a Wireless Displacement Measurement System Using Acceleration Responses  

PubMed Central

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

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

2013-01-01

291

Amplified hazard of small-volume monogenetic eruptions due to environmental controls, Orakei Basin, Auckland Volcanic Field, New Zealand  

NASA Astrophysics Data System (ADS)

Orakei maar and tuff ring in the Auckland Volcanic Field is an example of a basaltic volcano in which the style and impacts of the eruption of a small volume of magma were modulated by a fine balance between magma flux and groundwater availability. These conditions were optimised by the pre-85 ka eruption being hosted in a zone of fractured and variably permeable Plio-Pleistocene mudstones and sandstones. Orakei maar represents an end-member in the spectrum of short-lived basaltic volcanoes, where substrate conditions rather than the magmatic volatile content was the dominant factor controlling explosivity and eruption styles. The eruption excavated a crater ?80 m deep that was subsequently filled by slumped crater wall material, followed by lacustrine and marine sediments. The explosion crater may have been less than 800 m in diameter, but wall collapse and wave erosion has left a 1,000-m-diameter roughly circular basin. A tuff ring around part of the maar comprises dominantly base surge deposits, along with subordinate fall units. Grain size, texture and shape characteristics indicate a strong influence of magma-water and magma-mud interactions that controlled explosivity throughout the eruption, but also an ongoing secondary role of magmatic gas-driven expansion and fragmentation. The tuff contains >70 % of material recycled from the underlying Plio-Pliestocene sediments, which is strongly predominant in the >2 ? fraction. The magmatic clasts are evolved alkali basalt, consistent with the eruption of a very small batch of magma. The environmental impact of this eruption was disproportionally large, when considering the low volume of magma involved (DRE < 0.003 km3). Hence, this eruption exemplifies one of the worst-case scenarios for an eruption within the densely populated Auckland City, destroying an area of ~3 km2 by crater formation and base surge impact. An equivalent scenario for the same magma conditions without groundwater interaction would yield a scoria/spatter cone with a diameter of 400-550 m, destroying less than a tenth of the area affected by the Orakei event.

Németh, Károly; Cronin, Shane J.; Smith, Ian E. M.; Agustin Flores, Javier

2012-11-01

292

Forest transition in Vietnam and displacement of deforestation abroad  

PubMed Central

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

Meyfroidt, Patrick; Lambin, Eric F.

2009-01-01

293

A DISPLACED SUPERMASSIVE BLACK HOLE IN M87  

SciTech Connect

Isophotal analysis of M87, using data from the Advanced Camera for Surveys, reveals a projected displacement of 6.8 {+-} 0.8 pc ({approx}0.''1) between the nuclear point source (presumed to be the location of the supermassive black hole, SMBH) and the photo-center of the galaxy. The displacement is along a position angle of 307{sup 0} {+-} 17{sup 0} and is consistent with the jet axis. This suggests the active SMBH in M87 does not currently reside at the galaxy center of mass, but is displaced in the counter-jet direction. Possible explanations for the displacement include orbital motion of an SMBH binary, gravitational perturbations due to massive objects (e.g., globular clusters), acceleration by an asymmetric or intrinsically one-sided jet, and gravitational recoil resulting from the coalescence of an SMBH binary. The displacement direction favors the latter two mechanisms. However, jet asymmetry is only viable, at the observed accretion rate, for a jet age of >0.1 Gyr and if the galaxy restoring force is negligible. This could be the case in the low-density core of M87. A moderate recoil {approx}1 Myr ago might explain the disturbed nature of the nuclear gas disk, could be aligned with the jet axis, and can produce the observed offset. Alternatively, the displacement could be due to residual oscillations resulting from a large recoil that occurred in the aftermath of a major merger {<=}1 Gyr ago.

Batcheldor, D.; Perlman, E. S. [Physics and Space Sciences Department, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901 (United States); Robinson, A.; Merritt, D. [Physics Department, Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623-5603 (United States); Axon, D. J., E-mail: dbatcheldor@fit.ed [School of Mathematical and Physical Sciences, University of Sussex, Sussex House, Brighton, BN1 9RH (United Kingdom)

2010-07-01

294

All-optical control in metal nanocomposites due to a reversible transition between the local-field-enhancement and a local-field-depression upon irradiation by ultrashort control-pulses of light  

E-print Network

We theoretically study on non-perturbative effective nonlinear responses of metal nanocomposites based on the intrinsic third-order nonlinear response of metal nanoparticles. The large intrinsic third-order nonlinear susceptibility of metal nanoparticles and an irradiation by ultrashort control pulse of light with a sufficiently high peak intensity and moderate fluence can induce a local-field-depression and a saturated plasmon-bleaching in metal nanoparticles. If the control pulse is on, the metal nanocomposites can behave like a dielectric due to the local-field-depression, while if the control pulse is off, the metal nanocomposites can behave like a metal showing a high absorption due to the local-field-enhancement at the plasmon-resonance. This phenomenon can be applied to an ultrafast and remote control of light in metal nanocomposites.

Im, Song-Jin

2014-01-01

295

Displacement and resonance behaviors of a piezoelectric diaphragm driven by a double-sided spiral electrode  

NASA Astrophysics Data System (ADS)

This paper presents the design of a lead zirconate titanate (PZT) diaphragm actuated by double-sided patterned electrodes. Au/Cr electrodes were deposited on bulk PZT wafers by sputtering while patterned by a lift-off process. SU-8 thick film was used to form the structural layer. Double-spiral electrode induced in-plane poling and piezoelectric elongation are converted to an out-of-plane displacement due to the confined boundary condition. The influence of different drive configurations and electrode parameters on deflection has been calculated by finite element methods (FEM) using a uniform field model. Impedance and quasi-static displacement spectra of the diaphragm were measured after poling. A double-sided patterned electrode diaphragm can be actuated by more drive configurations than a single-sided one. Compared with a single-sided electrode drive, a double-sided out-of-phase drive configuration increases the coupling coefficient of the fundamental resonance from 7.6% to 11.8%. The displacement response of the diaphragm increases from 2.6 to 8.6 nm V-1. Configurations including the electric field component perpendicular to the poling direction can stimulate shear modes of the diaphragm.

Shen, Zhiyuan; Olfatnia, Mohammad; Miao, Jianmin; Wang, Zhihong

2012-05-01

296

Three-dimensional static displacement, stimulated echo NMR elasticity imaging  

NASA Astrophysics Data System (ADS)

This article presents a method for measuring three-dimensional mechanical displacement and strain fields using stimulated echo MRI. Additional gradient pulses encode internal displacements in response to an externally applied deformation. By limiting the mechanical transition to the stimulated echo mixing time, a more accurate static displacement measurement is obtained. A three-dimensional elasticity reconstruction within a region of interest having a uniform shear modulus along its boundary is performed by numerically solving discretized elasticity equilibrium equations. Data acquisition, strain measurements and reconstruction were performed using a silicone gel phantom containing an inclusion of known elastic properties. A comparison between two-dimensional and three-dimensional reconstructions from simulated and experimental displacement data shows higher accuracy from the three-dimensional reconstruction. The long-term objective of this work is to provide a method for remotely palpating and elastically quantitating manually inaccessible tissues.

Steele, Derek D.; Chenevert, Thomas L.; Skovoroda, Andrei R.; Emelianov, Stanislav Y.

2000-06-01

297

Environment-induced Population Displacements  

E-print Network

displacement / mobility related to environmental events Conceptual and methodological issues Climate change, security concerns and policy issues Based on IHDP OPEN MEETING 2009 The Social Challenges of Global Change) Adamo and De Sherbinin (forthcoming). The Impact of Climate Change on the Spatial Distribution

Columbia University

298

Stochastic Microgeometry for Displacement Mapping  

Microsoft Academic Search

Creating surfaces with intricate small-scale features (mi- crogeometry) and detail is an important task in geomet- ric modeling and computer graphics. We present a model processing method capable of producing a wide variety of complex surface features based on displacement mapping and stochastic geometry. The latter is a branch of mathe- matics that analyzes and characterizes the statistical prop- erties

Craig A. Schroeder; David E. Breen; Christopher D. Cera; William C. Regli

2005-01-01

299

Mass Media Displacement and Saturation  

Microsoft Academic Search

This study addresses the contradiction between the theoretical displacement of incumbent media by new media versus empirical evidence of rising consumption of both new and incumbent media. By analyzing 4 years of biannual daypart media consumption surveys, this research reveals trends in the consumer use of advertiser-supported media in the United States. Large gains were seen in new media, such

Jay Newell; Joseph J. Pilotta; John C. Thomas

2008-01-01

300

Tunnel-Effect Displacement Sensor  

NASA Technical Reports Server (NTRS)

Tunnel position sensor simple device measuring small displacements or accelerations. Used to make compact, sensitive accelerometers or strain gauges or to measure impacts of particles. Variation in distance between two electrodes measured via variation in tunneling current between them. Tunnel microsensors provide versatility for application as accelerometers, force sensors, strain sensors, particle detectors, and other devices for space applications.

Kaiser, William J.; Waltman, Steven B.

1989-01-01

301

Retraining Displaced Workers. Policy Brief  

ERIC Educational Resources Information Center

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

LaLonde, Robert; Sullivan, Daniel

2010-01-01

302

Polybenzimidazoles Via Aromatic Nucleophilic Displacement  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

303

Polyphenylquinoxalines Via Aromatic Nucleophilic Displacement  

NASA Technical Reports Server (NTRS)

Process for synthesis of polyphenylquinoxalines (PPQ's) involves nucleophilic displacement reactions of di(hydroxyphenyl) quinoxaline monomers with activated aromatic dihalides. New process costs less than other processes for synthesis of PPQ's. Facilitates synthesis of PPQ's of new and varied molecular structures. Useful as adhesives, coatings, films, membranes, and matrices for composites.

Hergenrother, Paul M.; Connell, John W.

1991-01-01

304

Character displacement in polyphenic tadpoles.  

PubMed

Biologists have long known that closely related species are often phenotypically different where they occur together, but are indistinguishable where they occur alone. The causes of such character displacement are controversial, however. We used polyphenic spadefoot toad tadpoles (Spea bombifrons and S. multiplicata) to test the hypothesis that character displacement evolves to minimize competition for food. We also sought to evaluate the role of phenotypic plasticity in the mediation of competitive interactions between these species. Depending on their diet, individuals of both species develop into either a small-headed omnivore morph, which feeds mostly on detritus, or a large-headed carnivore morph, which specializes on shrimp. Laboratory experiments and surveys of natural ponds revealed that the two species were more dissimilar in their tendency to produce carnivores when they occurred together than when they occurred alone. This divergence in carnivore production was expressed as both character displacement (where S. multiplicata's propensity to produce carnivores was lower in sympatry than in allopatry) and as phenotypic plasticity (where S. multiplicata facultatively enhanced carnivore production in S. bombifrons, and S. bombifrons facultatively suppressed carnivore production in S. multiplicata). In separate experiments, we established that S. bombifrons (the species for which carnivore production was enhanced) was the superior competitor for shrimp. Conversely, S. multiplicata (the species for which carnivore production was suppressed and omnivore production enhanced) was the superior competitor for detritus. These results therefore demonstrate that selection to minimize competition for food can cause character displacement. They also suggest that both character displacement and phenotypic plasticity may mediate competitive interactions between species. PMID:11108600

Pfennig, D W; Murphy, P J

2000-10-01

305

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

306

Analysis of coseismic surface displacement gradients using radar interferometry: New insights into the Landers earthquake  

Microsoft Academic Search

The map of the coseismic displacement field generated by interferometric processing of synthetic aperture radar (SAR) images taken before and after the June 28, 1992, Landers earthquake sequence brings new insights into the nature of deformation caused by these earthquakes. We use the interferometric map generated by Massonnet et al. (1993) to analyze the surface displacement field in the vicinity

Gilles Peltzer; Kenneth W. Hudnut; Kurt L. Feigl

1994-01-01

307

Force transmissibility versus displacement transmissibility  

NASA Astrophysics Data System (ADS)

It is well-known that when a single-degree-of-freedom (sdof) system is excited by a continuous motion of the foundation, the force transmissibility, relating the force transmitted to the foundation to the applied force, equals the displacement transmissibility. Recent developments in the generalization of the transmissibility to multiple-degree-of-freedom (mdof) systems have shown that similar simple and direct relations between both types of transmissibility do not appear naturally from the definitions, as happens in the sdof case. In this paper, the authors present their studies on the conditions under which it is possible to establish a relation between force transmissibility and displacement transmissibility for mdof systems. As far as the authors are aware, such a relation is not currently found in the literature, which is justified by being based on recent developments in the transmissibility concept for mdof systems. Indeed, it does not appear naturally, but the authors observed that the needed link is present when the displacement transmissibility is obtained between the same coordinates where the applied and reaction forces are considered in the force transmissibility case; this implies that the boundary conditions are not exactly the same and instead follow some rules. This work presents a formal derivation of the explicit relation between the force and displacement transmissibilities for mdof systems, and discusses its potential and limitations. The authors show that it is possible to obtain the displacement transmissibility from measured forces, and the force transmissibility from measured displacements, opening new perspectives, for example, in the identification of applied or transmitted forces. With this novel relation, it becomes possible, for example, to estimate the force transmissibility matrix with the structure off its supports, in free boundary conditions, and without measuring the forces. As far as force identification is concerned, this novel approach significantly decreases the computational effort when compared to conventional approaches, as it requires only local information of the sets of coordinates involved. Numerical simulations and experimental examples are presented and discussed, to illustrate the proposed developments.

Lage, Y. E.; Neves, M. M.; Maia, N. M. M.; Tcherniak, D.

2014-10-01

308

Fiber optic multimode displacement sensor  

Microsoft Academic Search

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

Karl A. Fisher; Jacek Jarzynski

1996-01-01

309

Polyphenylquinoxalines via aromatic nucleophilic displacement  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

310

Knowledge integration and displaced volume  

NSDL National Science Digital Library

This study contrasted spontaneous and reflective knowledge integration instruction delivered using a computer learning environment to enhance understanding of displaced volume. Both forms of instruction provided animated experiments and required students to predict outcomes, observe results, and explain their ideas. In addition, the reflective instruction diagnosed specific inconsistencies in student reasoning and encouraged students to reflect on these dilemmas as well as to construct general principles. We distinguished the impact of instruction on students who believed scientific phenomena are governed by principles (cohesive beliefs) versus students who believed that science is a collection of unrelated ldquofactsrdquo (dissociated beliefs). Students typically held multiple models of displacement, using different explanations depending on the form of assessment. For example, we found that 17% of these middle school students made accurate predictions about displacement experiments prior to instruction and 25% could construct an accurate general principle. However, only 12% consistently used the same explanation across assessments. After instruction, students were more accurate and more consistent: over 50% accurately predicted experimental outcomes, 79% gave an accurate general principle, and about 40% gave consistent responses. We found no advantages for enhanced animations over straightforward animated experiments. The reflective integration instruction led to more substantial long-term changes in student understanding than did spontaneous integration instruction. Furthermore, on a delayed posttest we found that students with cohesive beliefs not only sustained their understanding of displaced volume, but, when exposed to reflective integration instruction, actually continued to construct more predictive views following instruction. In contrast, students with dissociated beliefs made no long-term progress independent of the form of instruction.

Linn, Marcia; Eylon, Bat-Sheva

2006-12-07

311

Coupled diffusional/displacive transformations  

E-print Network

COUPLED DIFFUSIONAL/DISPLACIVE TRANSFORMATIONS Shafiq Ahmad Mujahid Darwin College Cambridge A dissertation submitted for the degree of Doctor of Philosophy at the University of Cambridge July 1992 Dedicated to my parents, Saif-ur-Rehman and Mariam... of plate-shaped particle) and dislocation- interface velocity versus interfacial dissipation, identifying stable steady-state velocity for the coupled process. 14 2.2 The Response Functions It is necessary to solve for three unknowns: the carbon...

Mujahid, Shafiq Ahmad

312

Polyphenylquinoxalines via aromatic nucleophilic displacement  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

313

Formation of the Ring-Like Structure in the SN 1987A Nebula due to the Magnetic Pressure of the Toroidal Field  

NASA Astrophysics Data System (ADS)

Several weeks after the explosion of supernova (SN) 1987A, the UV flash of the SN illuminated a ring-like structure in the circumstellar material at about 0.6 5 ly from the SN. The interaction between the stellar winds from the SN progenitor is considered to be the candidate for the formation of the circumstellar structure . In the case that the stellar winds are spherically symmetric, the interaction should result in a shell-like structure. However, in this paper we show that the magnetic field in the winds causes an anisotropy which leads to the formation of a ring-like structure. When the fast wind of the blue supergiant phase of the progenitor sweeps up the surrounding slow wind of the red-supergiant phase, the magnetic field as well as the wind material are piled up in the interaction region. Since the magnetic energy increases in proportion to the square of the amplitude, the magnetic field exhibits its effect prominently at the interaction region; due to the magnetic pressure force the material at lower latitudes is compressed into a ring-like structure. It is suggested that this magnetic process can also explain the newly observed pair of rings of the SN 1987A nebula.

Washimi, Haruichi; Shibata, Shinpei; Mori, Masao

1996-02-01

314

Helium effects on displacement cascades in ?-iron  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations have been performed to investigate the effects of helium on the displacement cascades in ?-iron. Besides conventional analysis tools, a new graphical representation of the data based on ternary plots has been introduced. Results show that the production of defects and their subsequent clustering appear to be greatly influenced by the presence of helium. Calculations reveal that the location of helium atoms, substitutional or interstitial, plays a major role. Compared to pure iron, interstitial helium atoms increase the amount of Frenkel pairs generated during the cascades. Conversely, substitutional helium atoms tend to decrease this production. However, in both cases, it is observed that helium atoms stabilize larger self-interstitial clusters, due to a strong binding energy. These simulations show that helium atoms trap self-interstitial clusters and would thus slow down their subsequent migration. Some helium-vacancy clusters are generated in the core of the displacement cascades but also grow at the periphery of self-interstitial clusters. It is shown that results greatly depend on the irradiation temperature.

Lucas, G.; Schäublin, R.

2008-10-01

315

Comparing Teaching Approaches about Maxwell's Displacement Current  

ERIC Educational Resources Information Center

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…

Karam, Ricardo; Coimbra, Debora; Pietrocola, Maurício

2014-01-01

316

Are microseismic ground displacements a significant geomorphic agent?  

NASA Astrophysics Data System (ADS)

This paper considers the role that microseismic ground displacements may play in fracturing rock via cyclic loading and subcritical crack growth. Using a coastal rock cliff as a case study, we firstly undertake a literature review to define the spatial locations that may be prone to microseismic damage. It is suggested that microseismic weakening of rock can only occur in ‘damage accumulation zones’ of limited spatial extent. Stress concentrations resulting from cliff height, slope angle and surface morphology may nucleate and propagate a sufficiently dense population of microcracks that can then be exploited by microseismic cyclic loading. We subsequently examine a 32-day microseismic dataset obtained from a coastal cliff-top location at Staithes, UK. The dataset demonstrates that microseismic ground displacements display low peak amplitudes that are punctuated by periods of greater displacement during storm conditions. Microseismic displacements generally display limited preferential directivity, though we observe rarely occurring sustained ground motions with a cliff-normal component during storm events. High magnitude displacements and infrequently experienced ground motion directions may be more damaging than the more frequently occurring, reduced magnitude displacements characteristic of periods of relative quiescence. As high magnitude, low frequency events exceed and then increase the damage threshold, these extremes may also render intervening, reduced magnitude microseismic displacements ineffective in terms of damage accumulation as a result of crack tip blunting and the generation of residual compressive stresses that close microcracks. We contend that damage resulting from microseismic ground motion may be episodic, rather than being continuous and in (quasi-)proportional and cumulative response to environmental forcing. A conceptual model is proposed that describes when and where microseismic ground motions can operate effectively. We hypothesise that there are significant spatial and temporal limitations on effective microseismic damage accumulation, such that the net efficacy of microseismic ground motions in preparing rock for fracture, and hence in enhancing erosion, may be considerably lower than previously suggested in locations where high magnitude displacements punctuate ‘standard’ displacement conditions. Determining and measuring the exact effects of microseismic ground displacement on damage accumulation and as a trigger to macro-scale fracture in the field is not currently possible, though our model remains consistent with field observations and conceptual models of controls on rockfall activity.

Brain, Matthew J.; Rosser, Nicholas J.; Norman, Emma C.; Petley, David N.

2014-02-01

317

Estimating Hydrologic Processes from Subsurface Soil Displacements  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

318

A Two-Equation Model For Mixing in Viscous-Fingering Displacements  

NASA Astrophysics Data System (ADS)

We study, by means of numerical simulation, the mixing of two fluids of different viscosities in advection-dominated flows in a porous medium. It is well known that when a less viscous fluid displaces a more viscous fluid, the displacement front is unstable and leads to the formation of a pattern known as viscous fingering. We present a high-resolution simulation approach that is stable for arbitrary viscosity ratios, and study mixing under different configurations with viscosity contrasts up to M = 400. We observe, in agreement with lab experiments, that for high-M displacements, the growth of new fingers follows the trace of previous ones. This channeling effect, which is a result of the nonlocal coupling through the pressure field, greatly reduces mixing. A two-equation mixing model using the scalar variance and its dissipation rate is derived from the advection-diffusion equation. It provides a measure of effective diffusivity due to convective and diffusive mixing processes. Our analysis predicts the optimum range of viscosity contrast and Peclet number that maximizes the interfacial area by balancing the number of fingers with their length before diffusive mixing across the sharp interface takes over. Interesting fingering patterns such as channeling and tip-splitting play an important role in this balancing act which makes degree of mixing a non-monotonic function of the viscosity contrast and the Peclet number.

Jha, Birendra; Cueto-Felgueroso, Luis; Juanes, Ruben

2010-11-01

319

The effect of elbow joint centre displacement on force generation and neural excitation  

Microsoft Academic Search

Joint centre displacement may occur following total elbow replacement due to aseptic loosening or surgical misalignment, and\\u000a has been linked to implant failure. In this study, the effects of joint centre displacement were examined using a neuromusculoskeletal\\u000a model of the elbow joint. Isometric contractions were simulated at a range of joint angles during elbow flexion and extension.\\u000a Displacement of the

Emer P. Doheny; Madeleine M. Lowery; Mark J. O’Malley; David P. FitzPatrick

2009-01-01

320

Morphometric study of the displacement of retinal ganglion cells subserving cones within the human fovea  

Microsoft Academic Search

· Background: A study was carried out to measure the displacement of retinal ganglion cells subserving the cones within the\\u000a human fovea.?· Methods: Four human retinas were examined along the nasal or vertical hemi-meridians. Total displacement was\\u000a estimated by adding the displacement due to fibres of Henle and bipolar cells, measured as the lateral extension of the Henle\\u000a fibres and

Johann Sjöstrand; Zoran Popovic; Nils Conradi; John Marshall

1999-01-01

321

Large-displacement strain theory and its application to graphene  

NASA Astrophysics Data System (ADS)

Under the application of a force a material will deform and, hence, the crystal lattice will experience strain. This induced strain will alter the electronic properties of the material. In particular, strain in graphene generates an artificial vector potential that, if spatially varying, admits a pseudomagnetic field. Current theories for spatially varying strain use linear or finite strain theory, whose derivation is based on small displacements of infinitesimal length vectors. Here we apply a differential geometry method to derive a strain theory for large displacements of finite length vectors. This method gives a finite displacement term whose contribution is comparable to that of the linear strain term. Furthermore, we show that a "domain-wall"-like pseudomagnetic-field profile can be generated when a wide graphene ribbon is subjected to a pair of opposing point forces (point stretch). The resulting field is a function of the new finite displacement term only and displays a maximum strength of over three times that which is predicted by the linear strain theory. These results extend the current theories of strain, which are based on the transformation of infinitesimal length vectors, to finite length vectors, thus providing an accurate description of pseudomagnetic-field structures in strained materials.

Crosse, J. A.

2014-07-01

322

WATER DISPLACEMENT DURING SPARGING UNDER PERCHED WATER-TABLE CONDITIONS  

EPA Science Inventory

The feasibility of using sparging to purposefully displace perched water in silt loam soils was evaluated at a field site in Northwestern Oklahoma. uring sparging, a transient response in water level measurements was observed in observation wells which is attributed to water disp...

323

Water Mist Suppression in Conjunction with Displacement  

E-print Network

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

Hickman, Mark

324

Burglary Reduction and the Myth of Displacement  

Microsoft Academic Search

Burglary remains a significant crime problem across Australia. While the Australian Institute of Criminology is keen to encourage burglary reduction initiatives, it often encounters the view that targeted operations simply displace crime to another area. This perception of total crime displacement is common, but has no strong evidential basis. While some studies have measured a modest degree of displacement in

Jerry Ratcliffe

2002-01-01

325

Displacement, Space and Dwelling: Placing Gentrification Debate  

Microsoft Academic Search

This paper is concerned with the conceptualisations of space which underlie debate of gentrification-related displacement. Using Derrida's concept of the spatial metaphor, the paper illuminates the Cartesian understandings of space that act as architecture for displacement debate. The paper corrects this through arguing that the philosophy of Heidegger and Lefebvre better serves to understand displacement. Emphasising the topology of Heidegger's

Mark Davidson

2009-01-01

326

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

USGS Publications Warehouse

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

Boore, D.M.

2003-01-01

327

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

SciTech Connect

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

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

2012-07-11

328

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

SciTech Connect

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

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

2011-04-15

329

Polyphenylquinoxalines via Aromatic Nucleophilic Displacement  

NASA Technical Reports Server (NTRS)

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.

Hergenrother, Paul M.; Connell, John W.

1988-01-01

330

An Alternative to Maxwell's Displacement Current  

E-print Network

Though sufficient for local conservation of charge, we show that Maxwells displacement current is not necessary. An alternative to the Ampere Maxwell equation is exhibited and the alternative s electric and magnetic fields and scalar and vector potentials are expressed in terms of the charge and current densities. The alternative describes a theory in which action is instantaneous and so may provide a good approximation to Maxwells equations where and when the finite speed of light can be neglected. The result is reminiscent of the Darwin approximation which arose from the study classical charged point particles to order (v/c)2 in the Lagrangian. Unlike Darwin, this approach does not depend on the constitution of the electric current. Instead, this approach grows from a straightforward revision of the Ampere Equation which revision enforces the local conservation of charge.

Wolsky, Alan M

2014-01-01

331

Positioning, displacement, and localization of cells using ultrasonic forces.  

PubMed

This paper presents a method and a device to position and displace cells. The cells are suspended in a fluid layer trapped between the device and an arbitrary surface such as an object slide or a wafer. The device vibrates at ultrasonic frequencies causing a pressure field in the fluid layer. This pressure field results in a force-field capable of positioning cells. Depending on the way in which the device is excited a 2-D or 3-D force-field can be generated, positioning the cells in lines or points respectively. Furthermore, it is possible to subsequently displace the cells with micrometer accuracy. This has been demonstrated using HL60 and MCF10A cells, and can be achieved without causing damage to the cells. PMID:16094668

Haake, Albrecht; Neild, Adrian; Radziwill, Gerald; Dual, Jurg

2005-10-01

332

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

333

Displacement Based Multilevel Structural Optimization  

NASA Technical Reports Server (NTRS)

In the complex environment of true multidisciplinary design optimization (MDO), efficiency is one of the most desirable attributes of any approach. In the present research, a new and highly efficient methodology for the MDO subset of structural optimization is proposed and detailed, i.e., for the weight minimization of a given structure under size, strength, and displacement constraints. Specifically, finite element based multilevel optimization of structures is performed. In the system level optimization, the design variables are the coefficients of assumed polynomially based global displacement functions, and the load unbalance resulting from the solution of the global stiffness equations is minimized. In the subsystems level optimizations, the weight of each element is minimized under the action of stress constraints, with the cross sectional dimensions as design variables. The approach is expected to prove very efficient since the design task is broken down into a large number of small and efficient subtasks, each with a small number of variables, which are amenable to parallel computing.

Sobieszezanski-Sobieski, J.; Striz, A. G.

1996-01-01

334

Interferometric fiber optic displacement sensor  

DOEpatents

A method is presented to produce a change in the optical path length in the gap between two single mode optical fibers proportional to the lateral displacement of either fiber end normal to its axis. This is done with the use of refraction or diffraction at the interface between a guiding and non-guiding media to change the direction of propagation of the light in the gap. A method is also presented for laying a waveguide on a cantilever so that the displacement of the tip of the cantilever produces a proportional path length change in the gap by distancing the waveguide from the neutral axis of the cantilever. The fiber is supported as a cantilever or a waveguide is deposited on a micromachined cantilever and incorporated in an interferometer which is made totally on a silicon substrate with the use of integrated-optic technology. A resonant element in the form of a micro-bridge is incorporated in the ridge waveguide and produces a frequency output which is readily digitizeable and immune to laser frequency noise. Finally, monolithic mechanical means for phase modulation are provided on the same sensor substrate. This is done by vibrating the cantilever or micro-bridge either electrically or optically. 23 figs.

Farah, J.

1999-04-06

335

Interferometric fiber optic displacement sensor  

DOEpatents

A method is presented to produce a change in the optical path length in the gap between two single mode optical fibers proportional to the lateral displacement of either fiber end normal to its axis. This is done with the use of refraction or diffraction at the interface between a guiding and non-guiding media to change the direction of propagation of the light in the gap. A method is also presented for laying a waveguide on a cantilever so that the displacement of the tip of the cantilever produces a proportional path length change in the gap by distancing the waveguide from the neutral axis of the cantilever. The fiber is supported as a cantilever or a waveguide is deposited on a micromachined cantilever and incorporated in an interferometer which is made totally on a silicon substrate with the use of integrated-optic technology. A resonant element in the form of a micro-bridge is incorporated in the ridge waveguide and produces a frequency output which is readily digitizeable and immune to laser frequency noise. Finally, monolithic mechanical means for phase modulation are provided on the same sensor substrate. This is done by vibrating the cantilever or micro-bridge either electrically or optically. 29 figs.

Farah, J.

1995-05-30

336

Systematic Design of Displacement-Amplifying Mechanisms for Piezoelectric Stacked Actuators Using Topology Optimization  

Microsoft Academic Search

Displacement-amplifying mechanisms can be systematically designed using topology optimization. Due to the special need for large displacement amplification of piezoelectric stacked actuators, suitable objective functions should be formulated. Among various possible formulations, this work considers maximum output stroke, magnification factor and mechanical efficiency as objective functions. As the formulation of maximum magnification factor performs better numerically than the rest, it

Gih Keong Lau; Hejun Du; Ningqun Guo; Mong King Lim

2000-01-01

337

Displaced helium and carbon in the Hawaiian plume Albrecht W. Hofmann a,b,  

E-print Network

Displaced helium and carbon in the Hawaiian plume Albrecht W. Hofmann a,b, , Cinzia G. Farnetani c 2011 Available online 1 November 2011 Editor: Y. Ricard Keywords: mantle plumes Hawaii helium vertically due to its low density and viscosity and is thus displaced from the plume center. Helium

Farnetani, Cinzia G.

338

A Theoretical Model to Predict Both Horizontal Displacement and Vertical Displacement for Electromagnetic Induction-Based Deep Displacement Sensors  

PubMed Central

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

Shentu, Nanying; Zhang, Hongjian; Li, Qing; Zhou, Hongliang; Tong, Renyuan; Li, Xiong

2012-01-01

339

Horizontal displacements contribution to tsunami wave energy balance  

E-print Network

The main reason for the generation of tsunamis is the deformation of the bottom of the ocean caused by an underwater earthquake. Usually, only the vertical bottom motion is taken into accound while the horizontal displacements are neglected. In the present paper we study both the vertical and the horizontal bottom motion while we propose a novel methodology for reconstructing the bottom coseismic displacements field which is transmitted to the free surface using a new three-dimensional Weakly Nonlinear (WN) approach. We pay a special attention to the evolution of kinetic and potential energies of the resulting wave while the contribution of horizontal displacements into wave energy balance is also quantified. Approaches proposed in this study are illustrated on the July 17, 2006 Java tsunami.

Dutykh, Denys; Chubarov, Leonid; Shokin, Yuriy

2010-01-01

340

Signal processing for order 10 pm accuracy displacement metrology in real-world scientific applications  

NASA Technical Reports Server (NTRS)

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.

Halverson, Peter G.; Loya, Frank M.

2004-01-01

341

Medium - long term earthquake prediction by the use of the oscillating electric field (T = 365 days) generated due to Earth's orbit around the Sun and due to its consequent oscillating lithospheric deformation  

E-print Network

We study the Earth's electric field monitored at PYR (Greece) monitoring site, for a period of more than six years (May 23rd, 2003 to September 7th, 2009). It is compared, in particular its oscillating component of T = 365 days, with the Perihelion - Aphelion dates of the Earth's orbit around the Sun, with the same component of the Earth's magnetic field, with the corresponding same period tidal oscillation and with the occurred large EQs of the same period of time. The obtained results suggest that the oscillating electric field component is generated by large scale piezoelectricity triggered by the Earth's shape - lithospheric oscillating deformation. The driving mechanism (yearly tidal variation) precedes the Aphelion - Perihelion dates for a month complying with the corresponding tidal friction behavior of the Earth's shape deformation. The Earth's oscillating electric field peaks coincide with the Perihelion - Aphelion dates while the triggered large EQs are clustered very close to the Perihelion - Aphel...

Thanassoulas, C; Tsailas, P; Verveniotis, G; Zymaris, N

2009-01-01

342

Displaceable Gear Torque Controlled Driver  

NASA Technical Reports Server (NTRS)

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.

Cook, Joseph S., Jr. (Inventor)

1997-01-01

343

Polybenzimidazoles Via Aromatic Nucleophilic Displacement  

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

344

Polybenzimidazoles via aromatic nucleophilic displacement  

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

345

Carrier injection property of C60 thin film transistor via displacement current measurement  

NASA Astrophysics Data System (ADS)

Carrier injection into a C60 thin film has been studied from characteristics of a field effect transistor and a displacement current measurement (DCM) using three kinds of metals, Mg, Ag, and Au. The Mg sample shows a highest field effect mobility of 0.62 cm2/Vs and a lowest threshold voltage of 6 V among the samples. A carrier injection and the accumulation are confirmed in the DCM curves by sweeping voltage applied on the back gate. The electron number and the density injected from the electrodes are estimated from the integration of the DCM curves. However, only the curve of the Mg sample shows a two-stage transition in the DCM curves. It could be due to a diffusion of Mg atoms into the C60 layer and a transition of releasing electrons from the donor level could be observed at lower voltage region.

Aoki, N.; Chiba, Y.; Chen, S.-R.; Tsuji, H.; Ueno, M.; Ogawa, K.; Bird, J. P.; Ochiai, Y.

2009-04-01

346

Derivation of the Biot-Savart Law from Ampere's Law Using the Displacement Current  

NASA Astrophysics Data System (ADS)

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.

Buschauer, Robert

2013-12-01

347

Fiber optic multimode displacement sensor  

SciTech Connect

An underwater Optical Motion Sensor (OMS) based on a design first presented by W. B. Spillman, {ital Schlieren} {ital multimode} {ital fiber}-{ital optic} {ital hydrophone}, Applied Physics Letters 37(2), 15 July 1980, p. 145{endash}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{double_prime} OD{times}3/4{double_prime}). 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{endash}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/cm{sup 3} making it almost neutrally buoyant in water. This in conjunction with the performance characteristics make this sensor suitable for use in acoustical sensing applications. {copyright} {ital 1996 American Institute of Physics.}

Fisher, K.A.; Jarzynski, J. [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States)

1996-04-01

348

The Population Genetics of Sperm Displacement  

PubMed Central

This article reports the results of some sperm displacement experiments, as well as the results of a theoretical study of selection arising from genetic differences in displacing ability. The experimental work involved the use of three genetic marker stocks in double and triple matings. The speed of displacement following the matings was determined by scoring the progeny of each female daily. There were clear differences between strains in their displacing ability. It is shown how new information concerning the displacement process results when three markers are used; however, no new light is shed by these experiments on the mechanism of displacement. The theoretical study of selection resulting from displacement uses a one-locus, two-allele model in which three diploid male genotypes confer different displacing abilities. The results indicate stable equilibria if (1) there is heterosis, and (2) there are certain nontransitive relationships in displacing ability among the different kinds of double matings. Some evolutionary consequences are discussed in which sperm displacement is regarded as a form of sexual selection. PMID:838274

Prout, Timothy; Bundgaard, J?rgen

1977-01-01

349

Detection of quasi-static displacement components of LP seismic sources near the volcanic summit  

NASA Astrophysics Data System (ADS)

Seismic long-period (LP) events are still not completely understood, but widely accepted source models involve fluids and fluid-driven resonance processes. Due to the difficulties related to installing seismometers in summit regions of volcanoes, the observations of volcanic seismicity are usually performed at distances not closer than 1-2 km from the hypocentre of a seismic event. Observations from high-density network experiments on different volcanoes lead to a new model proposed by Bean et al. (Nature Geoscience, January 2014). Therein LP events are explained as a consequence of a brittle-ductile failure occurring under the low-stress conditions in the shallow volcanic edifice, rather than fluid-driven resonance. One consequence of this model is a static displacement associated with these LP events. Unfortunately, the expected amplitude of the static shift is only several micrometres, i.e. not detectable by typical deformation measurements. Therefore, we try to develop methods for using seismometers as static shift detecting sensors. Our current inability to recover the full spectrum of recorded displacement results in a band-limited representation of the true process derived from moment-tensor inversions. If the actual source process is of a broadband character, our narrow-band results can be quite misleading. In this study we are focusing on quasi-static displacements we observed on seismometer data from Turrialba Volcano (Costa Rica) and Mt Etna (Italy). These appear as ramp-like signals on displacement traces of LP events, most commonly on all three seismometer components, and have a magnitude of a few micrometres. Laboratory tests confirm that the seismometers used in our field experiments can indeed measure step-like signals, but they also show that long period noise can be a problem when trying to interpret these. Normal high pass filters suitable to remove this noise cannot be applied without losing the signal we are interested in. Therefore special attention has to be paid to the processing steps preceding the interpretation of data. In order to constrain the data and test the applied methods, we compare field data and laboratory data with numerical simulations. Considering the full broadband spectrum of the recorded displacements may shed new light on the long period part of the source process.

Thun, Johannes; Bean, Christopher J.; Lokmer, Ivan

2014-05-01

350

Approaching the Quantum Limits of Displacement Detection  

NASA Astrophysics Data System (ADS)

While high quality factor mechanical resonators (such as cantilevers and membranes) are routinely used as exquisite sensors, only recently are these engineered devices encountering the fundamental limits and opportunities afforded by quantum mechanics. The standard quantum limit of displacement detection requires a balance between the measurement imprecision and momentum imparted on the object of interest. One promising measurement scheme for achieving, and possibly surpassing, these quantum limits of measurement is that of cavity optomechanics---an architecture in which a mechanical resonator modulates the frequency of a high frequency electromagnetic resonance. Ideally, the quantized nature of the measurement photons will impart backaction in the form of radiation pressure shot noise, but observation of this quantum effect in macroscopic mechanical resonators has proven experimental difficult due to the relatively weak forces of the light. We realize a microwave cavity ``opto'' -mechanical system by incorporating a freely-suspended membrane in a superconducting microwave resonant circuit, which simultaneously exhibits high quality factor electrical and mechanical modes [1]. The relatively large electomechanical coupling has led to experimental observation of the strong coupling regime [1] as well as sideband cooling of the mechanical mode to its quantum ground state [2]. I will present recent experiments of similar circuits in which the displacement sensitivity goes beyond that at the standard quantum limit by several orders of magnitude. These measurements also clearly show the fundamental trade-off between measurement imprecision and backaction. We observe the radiation pressure shot noise of the microwave photons and show that it can completely overwhelm the classical, thermal motion of the membrane. [1] Teufel et al., Nature 471, 204-208 (2011).[4pt] [1] Teufel et al., Nature 475, 359-363 (2011).

Teufel, John

2013-03-01

351

Displacement speeds in turbulent premixed flame simulations  

SciTech Connect

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.

Day, Marcus S.; Shepherd, Ian G.; Bell, J.; Grcar, Joseph F.; Lijewski, Michael J.

2007-07-01

352

Microbial Adhesion in Flow Displacement Systems  

PubMed Central

Flow displacement systems are superior to many other (static) systems for studying microbial adhesion to surfaces because mass transport and prevailing shear conditions can be adequately controlled and notoriously ill-defined slight rinsing steps to remove so-called “loosely adhering organisms” can be avoided. In this review, we present the basic background required to calculate mass transport and shear rates in flow displacement systems, focusing on the parallel plate flow chamber as an example. Critical features in the design of flow displacement systems are discussed, as well as different strategies for data analysis. Finally, selected examples of working with flow displacement systems are given for diverse biomedical applications. PMID:16418527

Busscher, Henk J.; van der Mei, Henny C.

2006-01-01

353

Influence of lateral displacement on the levitation performance of a magnetized bulk high-Tc superconductor magnet  

NASA Astrophysics Data System (ADS)

Compared with the permanent magnet, the magnetized bulk high-Tc superconductor magnet (MBSCM) can trap higher magnetic field due to its strong flux pinning ability, so it is a good candidate to improve the levitation performance of high-Tc superconductive (HTS) maglev system. The trapped magnetic flux of a MBSCM is sustained by the inductive superconducting current produced by the magnetizing process and is susceptible to the current intensity as well as configuration. In the HTS maglev system, the lateral displacement is an important process to change the superconducting current within a MBSCM and then affects its levitation performance, which is essential for the traffic ability in curve-way, the loading capacity of lateral impact and so on. The research about influence of lateral displacement on the levitation performance of MBSCM is necessary when MBSCM is applied on the HTS maglev vehicle. The experimental investigations about the influence of lateral displacement on the levitation performance of a MBSCM with different trapped fluxes and applied fields are processed in this article. The analyses and conclusions of this article are useful for the practical application of MBSCM in HTS maglev system.

Liu, W.; Wang, J. S.; Ma, G. T.; Zheng, J.; Tuo, X. G.; Li, L. L.; Ye, C. Q.; Liao, X. L.; Wang, S. Y.

2012-03-01

354

Erosion due to cultivation of calcareous clay soils on hillsides in south-west France. II. Effect of ploughing down the steepest slope  

Microsoft Academic Search

The erosion of calcareous clay soils from Terrefort in south west France is not exclusively due to run-off water. An experiment was carried out in situ to quantify the effect of ploughing on the displacement of soil down the slope. In a field experiment, a trench 0.4 m × 0.4 m × 20 m was dug parallel to the contours

M. Guiresse; J. C. Revel

1995-01-01

355

Contributions to the Gaussian Line Broadening of the Proxyl Spin Probe EPR Spectrum Due to Magnetic-Field Modulation and Unresolved Proton Hyperfine Structure  

NASA Astrophysics Data System (ADS)

A simple expression is derived to compute the total Gaussian linewidth of a Voigt line that is broadened by sinusoidal magnetic-field modulation as follows: ? HGpp( Hm) 2= ? HGpp(0) 2+ ? 2H2m, where ? HGpp( Hm) is the Gaussian linewidth observed with an modulation amplitude Hm/2 and ? HGpp(0) is the Gaussian linewidth in the limit of zero modulation. The field modulation contributes an additional Gaussian broadening of ? Hm, where ? is a constant, which adds in quadrature to ? HGpp(0) to give the total Gaussian linewidth. Denoting the overall linewidth of the Voigt line in the absence of modulation broadening by ? H0pp(0), it is shown, both by analytical means and by spectral simulation, that the constant ? is equal to 1/2 in the limit of Hm? ? H0pp(0); however, using values of Hmas large as ? H0pp(0) leads to only minor departures from ? = 1/2. The formulation is valid both for Lorentzian and Voigt lines and is tested for 2,2,5,5-tetramethylpyrrolidin-1-oxyl-3-carboxylic acid (3-carboxy proxyl) in CCl 4and in aqueous buffer. This spin probe was studied because the proxyl group is the only major spin-probe moiety whose Gaussian linewidth had not been characterized in the literature. For 3-carboxy proxyl, it is found that ? HGpp(0) = 1.04 ± 0.01 G independent of solvent polarity. Precision values of the 14N hyperfine coupling constant for 3-carboxy proxyl at 9.5°C are as follows: 14.128 ± 0.001 G in CCl 4and 16.230 ± 0.002 G in aqueous buffer. The temperature dependence of ? HGpp(0) and the 14N hyperfine coupling constant are reported as empirical equations. Results of the present work taken together with previously published data permits accurate correction for the effects of inhomogeneous broadening due to unresolved hyperfine structure and modulation broadening for the majority of spin probes in common use.

Bales, Barney L.; Peric, Miroslav; Lamy-Freund, Maria Teresa

1998-06-01

356

Polybenzoxazole via aromatic nucleophilic displacement  

NASA Technical Reports Server (NTRS)

Polybenzoxazoles (PBO) are heterocyclic macromolecules which were first synthesized in a two-step process by the initial formation of aromatic diacid chlorides with bis(o-aminophenol)s through solution condensation of aromatic diacid chlorides with bis(o-aminophenol)s followed by thermal cyclodehydration. Since then several methods were utilized in their synthesis. The most common synthetic method for PBO involves a polycondensation of bis(o-aminophenol)s with aromatic diacid diphenyl esters. Another preparative route involves the solution polycondensation of the hydrochloride salts of bis(o-amino phenol)s with aromatic diacids in polyphosphoric acid. Another synthetic method involves the initial formation of poly(o-hydroxy amide)s from silylated bis(o-aminophenol)s with aromatic diacid chlorides followed by thermal cyclodehydration to PBO. A recent preparative route involves the reaction of aromatic bisphenols with bis(fluorophenyl) benzoxazoles by the displacement reaction to form PBO. The novelty of the present invention is that high molecular weight PBO of new chemical structures are prepared that exhibit a favorable combination of physical and mechanical properties.

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

1993-01-01

357

Effects of Fault Displacement on Emplacement Drifts  

SciTech Connect

The purpose of this analysis is to evaluate potential effects of fault displacement on emplacement drifts, including drip shields and waste packages emplaced in emplacement drifts. The output from this analysis not only provides data for the evaluation of long-term drift stability but also supports the Engineered Barrier System (EBS) process model report (PMR) and Disruptive Events Report currently under development. The primary scope of this analysis includes (1) examining fault displacement effects in terms of induced stresses and displacements in the rock mass surrounding an emplacement drift and (2 ) predicting fault displacement effects on the drip shield and waste package. The magnitude of the fault displacement analyzed in this analysis bounds the mean fault displacement corresponding to an annual frequency of exceedance of 10{sup -5} adopted for the preclosure period of the repository and also supports the postclosure performance assessment. This analysis is performed following the development plan prepared for analyzing effects of fault displacement on emplacement drifts (CRWMS M&O 2000). The analysis will begin with the identification and preparation of requirements, criteria, and inputs. A literature survey on accommodating fault displacements encountered in underground structures such as buried oil and gas pipelines will be conducted. For a given fault displacement, the least favorable scenario in term of the spatial relation of a fault to an emplacement drift is chosen, and the analysis is then performed analytically. Based on the analysis results, conclusions are made regarding the effects and consequences of fault displacement on emplacement drifts. Specifically, the analysis will discuss loads which can be induced by fault displacement on emplacement drifts, drip shield and/or waste packages during the time period of postclosure.

F. Duan

2000-04-25

358

The effect of sowing date and rate on seed coat discolouration due to frost in field peas in the southern Mallee of Victoria  

Microsoft Academic Search

Frost occurring during the reproductive period of field peas can cause downgrading through seed coat discolouration and yield loss. During 2001, a field trial was conducted to determine the optimum sowing date (9 May, 17 June and 11 July) and sowing rate (15, 35, 55, 75 and 110 plants\\/m 2 ) of 4 field pea cultivars (Dundale, Parafield, Snowpeak and

Jason Brand; Roger Armstrong; Greg Antonoff

2003-01-01

359

Motion of the Esophagus Due to Cardiac Motion  

PubMed Central

When imaging studies (e.g. CT) are used to quantify morphological changes in an anatomical structure, it is necessary to understand the extent and source of motion which can give imaging artifacts (e.g. blurring or local distortion). The objective of this study was to assess the magnitude of esophageal motion due to cardiac motion. We used retrospective electrocardiogram-gated contrast-enhanced computed tomography angiography images for this study. The anatomic region from the carina to the bottom of the heart was taken at deep-inspiration breath hold with the patients' arms raised above their shoulders, in a position similar to that used for radiation therapy. The esophagus was delineated on the diastolic phase of cardiac motion, and deformable registration was used to sequentially deform the images in nearest-neighbor phases among the 10 cardiac phases, starting from the diastolic phase. Using the 10 deformation fields generated from the deformable registration, the magnitude of the extreme displacements was then calculated for each voxel, and the mean and maximum displacement was calculated for each computed tomography slice for each patient. The average maximum esophageal displacement due to cardiac motion for all patients was 5.8 mm (standard deviation: 1.6 mm, maximum: 10.0 mm) in the transverse direction. For 21 of 26 patients, the largest esophageal motion was found in the inferior region of the heart; for the other patients, esophageal motion was approximately independent of superior-inferior position. The esophagus motion was larger at cardiac phases where the electrocardiogram R-wave occurs. In conclusion, the magnitude of esophageal motion near the heart due to cardiac motion is similar to that due to other sources of motion, including respiratory motion and intra-fraction motion. A larger cardiac motion will result into larger esophagus motion in a cardiac cycle. PMID:24586540

Palmer, Jacob; Yang, Jinzhong; Pan, Tinsu; Court, Laurence E.

2014-01-01

360

Horizontal displacements of rock foundations of dams  

SciTech Connect

This paper uses geodetic survey methods to assess the horizontal displacements of dam foundations for several hydroelectric power plants in the Soviet Union. The effects of filling the reservoirs are outlined and the dependence of the degree of displacement on dam height is analyzed. The results are tabulated.

Karlson, A.A.

1987-08-01

361

A linear stability analysis for miscible displacements  

Microsoft Academic Search

A linear stability analysis has been performed for a miscible displacement in a semi-infinite system of finite thickness and unbounded width. A more general description of dispersion has been adopted than those used by previous workers. It is shown that, when there is a step change in concentration and the mobility ratio is unfavorable, the displacement can be unstable at

Shih-Hsien Chang; John C. Slattery

1986-01-01

362

A thermal modelling of displacement cascades in uranium dioxide  

NASA Astrophysics Data System (ADS)

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.

Martin, G.; Garcia, P.; Sabathier, C.; Devynck, F.; Krack, M.; Maillard, S.

2014-05-01

363

Horizontal displacement profiles in N Reactor horizontal control rod channels  

SciTech Connect

One of the potential results from N Reactor graphite moderator distortion is horizontal curvature of the horizontal control rod (HCR) channels. Mockup testing has identified two possible problem scenarios resulting from such curvature: slow scram times and rod abrasion due to rubbing of the rod on the side of the channel and subsequent displacement of T-blocks that form the sides of the channels. As a result of these potential events, surveillance tools (instrumentation) to measure HCR channel horizontal displacement was recently developed. Surveillance of HCR channel 65, performed on December 11, 1987, indicated a six inch rearward displacement near the center of the channel. This approximated the displacement which mockup testing has identified as a concern with regard to T-block movement. Closed Circuit Television (CCTV) observations indicate that T-block movement has not occurred in HCR channel 65, but that there has been some rubbing of the rod on the channel sides. Review of most recent rod hot scram times indicates normal performance for HCR 65. To further evaluate this concern, horizontal deflection and CCTV surveillance was scheduled in six HCR channels surrounding HCR channel 65. Inspection of the HCR rod tip was also performed. 13 refs., 6 figs.

Woodruff, E.M.

1988-12-01

364

Myocardial strains from 3D displacement encoded magnetic resonance imaging  

PubMed Central

Background The ability to measure and quantify myocardial motion and deformation provides a useful tool to assist in the diagnosis, prognosis and management of heart disease. The recent development of magnetic resonance imaging methods, such as harmonic phase analysis of tagging and displacement encoding with stimulated echoes (DENSE), make detailed non-invasive 3D kinematic analyses of human myocardium possible in the clinic and for research purposes. A robust analysis method is required, however. Methods We propose to estimate strain using a polynomial function which produces local models of the displacement field obtained with DENSE. Given a specific polynomial order, the model is obtained as the least squares fit of the acquired displacement field. These local models are subsequently used to produce estimates of the full strain tensor. Results The proposed method is evaluated on a numerical phantom as well as in vivo on a healthy human heart. The evaluation showed that the proposed method produced accurate results and showed low sensitivity to noise in the numerical phantom. The method was also demonstrated in vivo by assessment of the full strain tensor and to resolve transmural strain variations. Conclusions Strain estimation within a 3D myocardial volume based on polynomial functions yields accurate and robust results when validated on an analytical model. The polynomial field is capable of resolving the measured material positions from the in vivo data, and the obtained in vivo strains values agree with previously reported myocardial strains in normal human hearts. PMID:22533791

2012-01-01

365

Gage for measuring displacements in rock samples  

DOEpatents

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.

Holcomb, D.J.; McNamee, M.J.

1985-07-18

366

Gage for measuring displacements in rock samples  

DOEpatents

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.

Holcomb, David J. (Albuquerque, NM); McNamee, Michael J. (Albuquerque, NM)

1986-01-01

367

Resistance to the Bacillus thuringiensis Bioinsecticide in a Field Population of Plutella xylostella is Due to a Change in a Midgut Membrane Receptor  

Microsoft Academic Search

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 (>200-fold compared with

Juan Ferre; Maria Dolores Real; Jeroen van Rie; Stefan Jansens; Marnix Peferoen

1991-01-01

368

Properties, flowback, and wellbore displacement  

SciTech Connect

Carbon dioxide was introduced as an additive to acid and fracture jobs in 1962. Since then, its use as a well-servicing medium has grown rapidly. This has been due primarily to its excellent flowback properties, although it also offers other advantages. These advantages are described along with methods for making calculations with CO/sub 2/. 7 refs.

Poulson, D.K.

1981-10-19

369

Properties, flowback, and wellbore displacement  

Microsoft Academic Search

Carbon dioxide was introduced as an additive to acid and fracture jobs in 1962. Since then, its use as a well-servicing medium has grown rapidly. This has been due primarily to its excellent flowback properties, although it also offers other advantages. These advantages are described along with methods for making calculations with COâ. 7 refs.

Poulson

1981-01-01

370

Development and Evolution of Character Displacement  

PubMed Central

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. PMID:22257002

Pfennig, David W.; Pfennig, Karin S.

2012-01-01

371

Local interpolation of coseismic displacements measured by InSAR  

NASA Astrophysics Data System (ADS)

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.

Yaseen, M.; Hamm, N. A. S.; Woldai, T.; Tolpekin, V. A.; Stein, A.

2013-08-01

372

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)

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.

Rohrmann, B.

1981-01-01

373

Ultrasensitive measurement of MEMS cantilever displacement sensitivity below the shot noise limit  

E-print Network

The displacement of micro-electro-mechanical-systems(MEMs) cantilevers is used to measure a variety of phenomena in devices ranging from force microscopes for single spin detection[1] to biochemical sensors[2] to uncooled thermal imaging systems[3]. The displacement readout is often performed optically with segmented detectors or interference measurements. Until recently, various noise sources have limited the minimum detectable displacement in MEMs systems, but it is now possible to minimize all other sources[4] so that the noise level of the coherent light field, called the shot noise limit(SNL), becomes the dominant source. Light sources dis- playing quantum-enhanced statistics below this limit are available[5, 6], with applications in gravitational wave astronomy[7] and bioimaging[8], but direct displacement measurements of MEMS cantilevers below the SNL have been impossible until now. Here, we demonstrate the first direct measurement of a MEMs cantilever displacement with sub-SNL sensitivity, thus enabli...

Pooser, R C

2014-01-01

374

Effects of threshold displacement energy on defect production by displacement cascades in ?, ? and ?-LiAlO2  

NASA Astrophysics Data System (ADS)

Threshold displacement energy evaluation and a series of displacement cascade simulations in ?, ?, and ?-LiAlO2 were performed using molecular dynamics. Threshold displacement energy evaluations indicated that higher absolute ionic charge values and larger densities both increase threshold displacement energy. The displacement cascade simulations suggest that the influence of different crystal structures on the number of interstitial atoms generated in a displacement cascade is explainable almost entirely by the difference of the threshold displacement energy.

Tsuchihira, H.; Oda, T.; Tanaka, S.

2013-11-01

375

Anion-exchange displacement centrifugal partition chromatography.  

PubMed

Ion-exchange displacement chromatography has been adapted to centrifugal partition chromatography. The use of an ionic liquid, benzalkonium chloride, as a strong anion-exchanger has proven to be efficient for the preparative separation of phenolic acid regioisomers. Multigram quantities of a mixture of three hydroxycinnamic acid isomers were separated using iodide as a displacer. The displacement process was characterized by a trapezoidal profile of analyte concentration in the eluate with narrow transition zones. By taking advantage of the partition rules involved in support-free liquid-liquid chromatography, a numerical separation model is proposed as a tool for preliminary process validation and further optimization. PMID:15516108

Maciuk, Alexandre; Renault, Jean-Hugues; Margraff, Rodolphe; Trébuchet, Philippe; Zèches-Hanrot, Monique; Nuzillard, Jean-Marc

2004-11-01

376

Topographic amplification of tectonic displacement: Implications for geodetic measurement of strain changes  

SciTech Connect

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.

McTigue, D.F.; Stein, R.S.

1984-02-10

377

Evaluation of two-phase relative permeability and capillary pressure relations for unstable displacements in a pore network  

SciTech Connect

A series of displacement experiments was conducted using five wetting-nonwetting immiscible fluid pairs in a homogenous and uniform pore network. The micromodel was initially saturated with either polyethylene glycol 200 (PEG) or water as a wetting fluid, which was subsequently displaced by a nonwetting fluid (dodecane, hexadecane, or mineral oil) at different flow rates. The experiments were designed to allow determinations of nonwetting fluid relative permeabilities ( ), fluid saturations ( ), and capillary pressure heads ( ). In the displacements, nonwetting fluid saturations increased with increasing flow rates for all five fluid pairs, and viscous fingering, capillary fingering, and stable displacement were observed. Viscous fingering occurred when PEG was displaced by either dodecane or hexadecane. For the water displacements, capillary fingers were observed at low capillary numbers. Due to unstable fingering phenomena, values for the PEG displacements were smaller than for the water displacements. A fitting exercise using the Brooks-Corey (1964) relationship showed that the fitted entry pressure heads are reasonably close to the computed entry pressure head. The fitted pore geometry factor, ?? values for the displacements are considerably lower than what is expected for displacements in homogeneous, highly uniform, porous systems, demonstrating the impact of unstable displacement on the apparent value of ?. It was shown that a continuum-based multiphase model could be used to predict the average behavior for wetting fluid drainage in a pore network as long as independently fitted - and - relations are used. The use of a coupled approach through the Brooks-Corey pore geometry factor underpredicts observed values.

Dehoff, Karl J.; Oostrom, Martinus; Zhang, Changyong; Grate, Jay W.

2012-10-29

378

Spacecraft displacement damage dose calculations for shielded CCDs  

NASA Astrophysics Data System (ADS)

The particle environment within a satellite includes primary and secondary protons and secondary neutrons produced in spacecraft materials which we evaluate using the transport code BRYNTRN. The damaging effects of this mixed particle environment is evaluated for the example of solid state imaging arrays by introducing the concept of displacement damage dose. Having the same relationship as electronic stopping power (LET) and radiation absorbed dose (rad) the nonionizing energy loss rate NIEL) of protons and neutrons are combined in terms of nonionizing radiation absorbed dose (nirad). This quantity is evaluated as a function of Ta and Al shield thickness for both trapped and flare proton environments. Al is shown to be a superior shield material per unit mass partially due to the damaging effects of neutrons which are produced in greater abundance in Ta. This method for combining the damaging effects from all particles using displacement damage dose enables informed shielding decisions and improved prediction of device performance in space. 1.

Dale, Cheryl J.; Marshall, Paul W.; Cummings, Bill; Shamey, Louis; Howard, Russ A.; Delamere, Alan W.

1992-08-01

379

REVERSE DISPLACEMENT ANALYSIS FOR TENSEGRITY STRUCTURES  

E-print Network

REVERSE DISPLACEMENT ANALYSIS FOR TENSEGRITY STRUCTURES By TUNG MINH TRAN A THESIS PRESENTED INTRODUCTION.........................................................................1 2 THREE-THREE TENSEGRITY-THREE TENSEGRITY PLATFORMS WITH AN APPLIED EXTERNAL WRENCH....................................... 28 Plücker

Florida, University of

380

Seismic transducer measures small horizontal displacements  

NASA Technical Reports Server (NTRS)

Pendular seismic transducer mounted on base plate measures small horizontal displacements of structures subjected to vibration where no fixed reference point is available. Enclosure of transducer in transparent plastic case prevents air currents from disturbing the pendulum balance.

Greenwood, T. L.

1965-01-01

381

Scale model studies of displacement ventilation  

E-print Network

Displacement ventilation is an air conditioning method that provides conditioned air to indoor environments with the goal to improve air quality while reducing energy consumption. This study investigates the performance ...

Okutan, Galip Mehmet

1995-01-01

382

Feasibility study on ultrasonic lateral displacement measurement for structural health monitoring  

NASA Astrophysics Data System (ADS)

In structural health monitoring, measuring the relative lateral displacement of the structure is essential for direct damage detection. Although large numbers of studies have been made on the development of the range finder utilizing an optical sensor, little attention has been given to the measuring method for lateral displacement. We propose a novel measurement method for directly measuring the lateral displacement of the structures by means of the air-coupled ultrasound. The measurement system is composed of two flat-type air-coupled ultrasound transducers and a steel wire as a target. The ultrasound transducers are immobilized on a fixed point, whereas a steel wire is separately arranged on the opposite side. When the steel wire is displaced laterally to the ultrasound detectors, the lateral displacement is calculated by taking advantage of the intensity ratio of the reflected ultrasound waves. The accuracy of the lateral displacement measurement is experimentally assessed by conducting a laboratory test. The estimated displacement value in the far field region of the transducer agrees well with the reference. The result shows that the developed displacement measurement method will be useful for the health diagnosis of structures.

Matsuya, Iwao; Matsumoto, Fumiya; Ihara, Ikuo

2014-02-01

383

Wireless displacement sensing system for bridges using multi-sensor fusion  

NASA Astrophysics Data System (ADS)

Accurate displacement sensing or estimation is an important task for reliably assessing the condition of civil infrastructure such as bridges and buildings, because the structural displacement describes the behavior of a structure and indicates structural safety according to the design limit. However, it is difficult to directly measure the displacement of a bridge structure due to the inaccessibility of a reference point especially when bridges are built over a highway, a river or the sea. As an alternative, an indirect displacement estimation using two different types of measurements such as strain and acceleration (i.e., multimetric data) has been developed. While the approach has been seen as promising, the combination of the traditional sensing system based on wired sensors and the multimetric data-based algorithm is inappropriate or impractical in real-world applications of the approach. This paper proposes a new displacement sensing system by incorporating wireless sensor technology with the multimetric data-based algorithm, which can address the difficulties and issues found in the traditional sensing system to realize a practical means of measuring displacement in full-scale bridges. The proposed wireless displacement sensing system enables (a) time-synchronized acceleration and strain measurement, (b) high-precision strain sensing and (c) improved applicability due to the wireless communication as well as the previous two features. The effectiveness of the proposed system is experimentally verified in laboratory and full-scale experiments.

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

2014-04-01

384

High Precision Displacement Measurement Using Fiber Optics  

Microsoft Academic Search

We describe laboratory experiments with a fiber-optic sensor employing a chirped laser that detects, with 20-30 micrometer accuracy, displacements of a remote reflective target at distance of 200-500 mm. The requirements of chirp linearity and laser coherence in order to achieve this sensitivity are elaborated. This sensor can be employed for remotely sensing minute displacements of objects in harsh environments,

G Berkovic; S Rotter; Walter Scandale; E Shafir; Ezio Todesco

2002-01-01

385

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

E-print Network

by Pinel et al. [2007]. We assume 5 km as elastic thickness of the lithosphere, a Young's modulus of 40 GPa decrease in the magma chamber only; both processes show a very similar deformation pattern. This poses, provide an additional source of deformation. The initial elastic response due to a load on the surface

Grapenthin, Ronni

386

The displacement computation and construction pre-control of a foundation pit in Shanghai utilizing FEM and intelligent methods  

Microsoft Academic Search

Controlling the displacements of foundation pit walls and supporting structures is one of the most effective measures for\\u000a ensuring safety of foundation pit construction. Because of this, the accurate displacement computation of foundation pit walls\\u000a and supporting structures is paid great attention by geotechnical scientists and engineers. In this paper, the three-dimensional\\u000a displacement field of Deping Station foundation pit, which

You-Liang Chen; Rafig Azzam; Fu-Bo Zhang

2006-01-01

387

Molecular Dynamics Simulations of Displacement Cascades in Single and Polycrystalline Zirconia  

SciTech Connect

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.

Du Jincheng [Department of Materials Science and Engineering, Center for Advanced Scientific Computing and Modeling, University of North Texas (United States)

2009-03-10

388

Displacement sensor for indoor machine calibrations.  

PubMed

This paper presents a simple displacement sensor for indoor machine calibrations. The sensor, which is placed in the path of a diverging laser beam, consists of two plane mirror pieces laterally displaced with the line joining their centers initially held perpendicular to the optical axis of the beam during the displacement of the sensor with one of the mirrors always traveling along the optical axis of the laser beam. The optical signals from the two mirrors are combined and a simple detector at the interference plane counts the fringes during the sensor displacement. The sensor could be mounted on the moving head of any mechanical machine, e.g., the lathe machine for displacement calibration. The device has been tested over a range of 10 cm beyond a distance of 150 cm from a diverging laser source giving an accuracy of 1.1015 ?m. Theoretical modeling, simulation, and experimental results are presented which establish that the proposed sensor can be used as a promising displacement measuring device. PMID:23736230

Mudassar, Asloob Ahmad; Butt, Saira

2013-05-20

389

Experimental analysis of the contribution of swimming and drifting to the displacement of reef fish larvae  

Microsoft Academic Search

The extent to which behaviour affects the dispersal of pelagic larvae in reef fishes has been a topic of major discussion\\u000a among marine ecologists. Here, we experimentally quantified the extent to which the displacement of late-stage larvae of Abudefduf saxatilis is due to active movement (i.e. swimming) and drifting. We consider drifting as the component of larval displacement accounted\\u000a for

J. Derek Hogan; Camilo Mora

2005-01-01

390

Tsunami mortality and displacement in Aceh province, Indonesia  

E-print Network

Tsunami mortality and displacement in Aceh province, Indonesia Abdur Rofi, MA Mercy Corps Indonesia, Indonesia, Shannon Doocy, PhD Research Associate, Johns Hopkins Bloomberg School of Public Health, US. Keywords: displacement, internally displaced persons (IDPs), Indonesia, mortality, tsunami Introduction

Scharfstein, Daniel

391

A relativistic self-consistent model for studying enhancement of space charge limited field emission due to counter-streaming ions  

NASA Astrophysics Data System (ADS)

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.

Lin, M. C.; Lu, P. S.; Chang, P. C.; Ragan-Kelley, B.; Verboncoeur, J. P.

2014-02-01

392

Displacement analysis of a bend plate test with mechanical loading and laser heating  

SciTech Connect

The surface displacment of a steel plate caused by a permanent deformation as a result of local yielding was modeled by a finite element analysis. The local yielding occurs when a small area of the plate is heated by a laser beam. The calculated displacments are in good agreement with the preliminary experimental data obtained using a bend specimen with laser heating at the University of Alabama at Huntsville. It has been shown computuationally and optically that the relative displacments are less than 1mm near the laser heated area of the specimen. The results demonstrate that the experimental approach is a feasible technique for determining the residual stress under multiaxial stress field.

Lam, P.S.

1997-09-01

393

Direct observation of depth-dependent atomic displacements associated with dislocations in gallium nitride.  

PubMed

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. PMID:25302902

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

394

Direct Observation of Depth-Dependent Atomic Displacements Associated with Dislocations in Gallium Nitride  

NASA Astrophysics Data System (ADS)

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.

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.

2014-09-01

395

Comparison of measured and computed local electric field distributions due to vehicle-mounted antennas using 2D feature selective validation  

Microsoft Academic Search

This paper outlines the results of a validation study based on simulated and measured data obtained for the electric field in the vicinity of a vehicle equipped with a roof-mounted monopole antenna. Evaluations based on simple statistics and a 2D feature selective validation (FSV) analysis are presented. Statistical differences between the measurements and simulations are found be better than ±3

Anthony J. M. Martin; Alastair R. Ruddle; Alistair P. Duffy

2005-01-01

396

Size-scaling experiment in a two-dimensional electron gas using an inhomogeneous magnetic field due to a superconducting gate  

Microsoft Academic Search

We have used a superconducting gate on the top of a two-dimensional electron gas (2DEG) to partition an external magnetic field into a distribution of submicron flux tubes (vortices) and measure the weak localisation contribution to the 2DEG conductance versus spatial separation of the vortices. It is found that the effect of a vortex extends far beyond its actual size.

A. K. Geim; S. V. Dubonos; I. V. Grigorieva; S. J. Bending

1996-01-01

397

Lasing from the domain of collision of ionisation waves produced due to electric field concentration at electrodes with a small radius of curvature  

SciTech Connect

The characteristics of UV lasing in nitrogen and of diffusive discharge produced without an additional ionisation source were experimentally investigated in a nonuniform electric field formed by electrodes with different profiles. High-voltage nanosecond pulses were applied to the blade- and cylinder-shaped electrodes. It was determined that the gap breakdown at elevated pressure was caused by diffusive jets which propagate from the electrodes with a small radius of curvature. The electric field increased in the intersection of counter-propagating jets, with the effect that the threshold of lasing in the C{sup 3}{Pi}{sub u} - B{sup 3}{Pi}{sub g} ({lambda} = 337.1 nm) molecular nitrogen band was attained for low average electric fields (below 60 V cm{sup -1} Torr{sup -1}) and at pressures of 760 Torr and above. With lowering the pressure from 760 to 20 Torr, the voltage of gap breakdown in the nonuniform electric field was observed to increase for a voltage pulse rise time of {approx}300 ps and to decrease for a pulse rise time of {approx}2 ns.

Tarasenko, Viktor F; Tel'minov, A E; Burachenko, A G; Rybka, D V; Baksht, E Kh; Lomaev, Mikhail I; Panchenko, Aleksei N; Vil'tovskii, P O [Institute of High Current Electronics, Siberian Branch, Russian Academy of Sciences, Tomsk (Russian Federation)

2011-12-31

398

Surface displacements in the 1906 san francisco and 1989 loma prieta earthquakes.  

PubMed

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. PMID:17829210

Segall, P; Lisowski, M

1990-11-30

399

Design and Preliminary Results of a Feedback Circuit for Plasma Displacement Control in IR-T1 Tokamak  

SciTech Connect

Since displacement is very important for plasma position control, in IR-T1 tokamak a combination of two cosine coils and two saddle sine coils is used for horizontal displacement measurement. According to the multiple moment theory, the output of these coils linearly depends to radial displacement of plasma column. A new circuit for adding these signals to feedback system designed and unwanted effects of other fields in final output compensated. After compensation and calibration of the system, the output of horizontal displacement circuits applied to feedback control system. By considers the required auxiliary vertical field, a proportional amplifier and driver circuit are constructed to drive power transistors these power transistors switch the feedback bank capacitors. In the experiment, a good linear proportionality between displacement and output observed by applying an appropriate feedback field, the linger confinement time in IR-T1 tokamak obtained, applying this system to discharge increased the plasma duration and realizes repetitive discharges.

TalebiTaher, A.; Ghoranneviss, M.; Tarkeshian, R.; Salem, M. K. [Plasma Physics Research Center, Islamic Azad University, Tehran (Iran, Islamic Republic of); Khorshid, P. [Plasma Physics Research Center, Islamic Azad University, Tehran (Iran, Islamic Republic of); Dep. of Physics, Islamic Azad University, Mashhad (Iran, Islamic Republic of)

2008-04-07

400

Probing neutrino mass with displaced vertices at the Tevatron  

E-print Network

Supersymmetric extensions of the standard model exhibiting bilinear R-parity violation can generate naturally the observed neutrino mass spectrum as well mixings. One interesting feature of these scenarios is that the lightest supersymmetric particle (LSP) is unstable, with several of its decay properties predicted in terms of neutrino mixing angles. A smoking gun of this model in colliders is the presence of displaced vertices due to LSP decays in large parts of the parameter space. In this work we focus on the simplest model of this type that comes from minimal supergravity with universal R-parity conserving soft breaking of supersymmetry (RmSUGRA). We evaluate the potentiality of the Fermilab Tevatron to probe the RmSUGRA parameters through the analysis of events possessing two displaced vertices stemming from LSP decays. We show that requiring two displaced vertices in the events leads to a reach in m_{1/2} twice the one in the usual multilepton signals in a large fraction of the parameter space.

F. de Campos; O. J. P. Eboli; M. B. Magro; W. Porod; D. Restrepo; J. W. F. Valle

2005-01-17

401

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)

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.

Sarma, G. S. R.

1982-01-01

402

Performance gain of displacement receiver with optimized prior probability  

NASA Astrophysics Data System (ADS)

We numerically study the performance of the displacement based quantum receiver for the discrimination of weak 3- and 4-phase-shift keyed (PSK) coherent state signals. We show that due to the nontrivial asymmetry of the receiver structure, optimization of the prior probability increases the mutual information and achieves sub-shot-noise limit discrimination. Moreover, we estimate the cutoff rate for a 4-PSK signal and confirm that the prior probability optimization shortens the code length for a given decoding error criterion. Such consideration for the asymmetric channel matrix is essential in a study of the compassable quantum receiver.

Fujiwara, M.; Izumi, S.; Takeoka, M.; Sasaki, M.

2013-11-01

403

Forced displacement and women's security in Colombia.  

PubMed

In the protracted Colombian conflict, assistance to internally displaced persons has developed in the context of contradictory political processes. The Colombian government's launching of a transitional justice process in the midst of armed conflict has generated a complex situation displaying both conflict and post-conflict characteristics. The progressive Constitutional Court rulings on internal displacement, in particular the gender-sensitive Auto 092, constitute an attempt to bring together humanitarian interventions and transitional justice measures in a rights-based framework. However, the national government is reluctant to adopt them fully and local realities still hamper their integrated implementation. Displaced women, therefore, remain in an especially vulnerable position. This paper argues that gender-sensitive humanitarian interventions must take into account all of these complexities of scale and political process in order to make legal frameworks more effective at the local level. In these contexts, interventions should pay particular attention to strategies that contribute to transforming pre-existing gender regimes. PMID:20132270

Meertens, Donny

2010-04-01

404

Frictional behavior of large displacement experimental faults  

USGS Publications Warehouse

The coefficient of friction and velocity dependence of friction of initially bare surfaces and 1-mm-thick simulated fault gouges (400 mm at 25??C and 25 MPa normal stress. Steady state negative friction velocity dependence and a steady state fault zone microstructure are achieved after ???18 mm displacement, and an approximately constant strength is reached after a few tens of millimeters of sliding on initially bare surfaces. Simulated fault gouges show a large but systematic variation of friction, velocity dependence of friction, dilatancy, and degree of localization with displacement. At short displacement (<10 mm), simulated gouge is strong, velocity strengthening and changes in sliding velocity are accompanied by relatively large changes in dilatancy rate. With continued displacement, simulated gouges become progressively weaker and less velocity strengthening, the velocity dependence of dilatancy rate decreases, and deformation becomes localized into a narrow basal shear which at its most localized is observed to be velocity weakening. With subsequent displacement, the fault restrengthens, returns to velocity strengthening, or to velocity neutral, the velocity dependence of dilatancy rate becomes larger, and deformation becomes distributed. Correlation of friction, velocity dependence of friction and of dilatancy rate, and degree of localization at all displacements in simulated gouge suggest that all quantities are interrelated. The observations do not distinguish the independent variables but suggest that the degree of localization is controlled by the fault strength, not by the friction velocity dependence. The friction velocity dependence and velocity dependence of dilatancy rate can be used as qualitative measures of the degree of localization in simulated gouge, in agreement with previous studies. Theory equating the friction velocity dependence of simulated gouge to the sum of the friction velocity dependence of bare surfaces and the velocity dependence of dilatancy rate of simulated gouge fails to quantitatively account for the experimental observations.

Beeler, N. M.; Tullis, T. E.; Blanpied, M. L.; Weeks, J. D.

1996-01-01

405

Wireless Power Transfer during Displacement Using Electromagnetic Coupling in Resonance  

NASA Astrophysics Data System (ADS)

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

Imura, Takehiro; Okabe, Hiroyuki; Uchida, Toshiyuki; Hori, Yoichi

406

Inhomogeneous Perfect Fluid Universe with Electromagnetic Field in Lyra Geometry  

E-print Network

A new class of cylindrically symmetric inhomogeneous cosmological models for perfect fluid distribution with electromagnetic field is obtained in the context of Lyra's geometry. We have obtained two types of solutions by considering the uniform as well as time dependent displacement field. The source of the magnetic field is due to an electric current produced along the z-axis. Only $F_{12}$ is a non-vanishing component of electromagnetic field tensor. To get the deterministic solution, it has been assumed that the expansion $\\theta$ in the model is proportional to the shear $\\sigma$. It has been found that the solutions are consistent with the recent observations of type Ia supernovae and the displacement vector $\\beta(t)$ affects entropy. Physical and geometric aspects of the models are also discussed in presence and absence of magnetic field.

Anirudh Pradhan; Priya Mathur

2008-06-30

407

Displacement of crude oil by carbon dioxide  

E-print Network

viscosity of 20 cp until water production from the sand pack was essentially KEY TO SCHEMATIC FOR CO2 FLOOD EOUIPMENT FIGURE 1 1. Core 2. Filter 3. Oil Pump 4. Mercury-Antifreeze Vessel 5. Pressure Gauge 6. Oil Reservoir 7. CO2 Source 8... of crude oil displaced from the three sand packs by CO as a function of pressure was essentially the same. For each of the sand packs three regions were recognized. A pressure region of (1) immiscible crude oil displacement, (2) near miscible crude oil...

Omole, Olusegun

2012-06-07

408

INSPECTION OF SURFACE STRAIN IN MATERIALS USING DENSE DISPLACEMENT FIELDS  

E-print Network

of force from a test rig. Not all motion detection algorithms have suitable functional characteristics-based motion detection algorithm can be used as a high confidence estimator of the strain tensor characterising aluminium alloy. Because the algorithm offers increased accuracy near motion con- trast boundaries, its

Torr, Philip H. S.

409

Noise analysis and improvement of displacement vector estimation from angular displacements  

PubMed Central

Elastography or elasticity imaging techniques typically image local strains or Young’s modulus variations along the insonification direction. Recently, techniques that utilize angular displacement estimates obtained from multiple angular insonification of tissue have been reported. Angular displacement estimates obtained along different angular insonification directions have been utilized for spatial-angular compounding to reduce noise artifacts in axial-strain elastograms, and for estimating the axial and lateral components of the displacement vector and the corresponding strain tensors. However, these angular strain estimation techniques were based on the assumption that noise artifacts in the displacement estimates were independent and identically distributed and that the displacement estimates could be modeled using a zero-mean normal probability density function. Independent and identically distributed random variables refer to a collection of variables that have the same probability distribution and are mutually independent. In this article, a modified least-squares approach is presented that does not make any assumption regarding the noise in the angular displacement estimates and incorporates displacement noise artifacts into the strain estimation process using a cross-correlation matrix of the displacement noise artifacts. Two methods for estimating noise artifacts from the displacement images are described. Improvements in the strain tensor (axial and lateral) estimation performance are illustrated utilizing both simulation data obtained using finite-element analysis and experimental data obtained from a tissue-mimicking phantom. Improvements in the strain estimation performance are quantified in terms of the elastographic signal-to-noise and contrast-to-noise ratios obtained with and without the incorporation of the displacement noise artifacts into the least-squares strain estimator. PMID:18561677

Chen, Hao; Varghese, Tomy

2008-01-01

410

Polyclonal infections due to Mycobacterium avium complex in patients with AIDS detected by pulsed-field gel electrophoresis of sequential clinical isolates.  

PubMed Central

Invasive infection with organisms of the Mycobacterium avium complex (MAC) is common among patients with advanced human immunodeficiency virus infection. In previous studies, we analyzed multiple individual colonies of MAC isolated from specimens obtained at the same time and observed that 14 to 20% of patients are simultaneously infected with more than one strain. In this study, we examined sequential isolates from 12 patients with AIDS who had two or more MAC isolates available from clinical specimens collected more than 1 week apart; the intervals between the first and last specimens ranged from 8 to 192 (median, 46) days. For each isolate, restriction digests of genomic DNA were analyzed by pulsed-field gel electrophoresis; DNA was prepared by using a protocol, described here in detail, which had been optimized for conditions of bacterial growth and lysis. The pulsed-field gel electrophoresis analysis identified four patients (33%) infected with two different MAC strains. Both M. avium and M. intracellulare were cultured from blood specimens from two patients. In each of the four patients, the second strain was identified from a culture taken within 14 days of the initial study isolate, and in three of these patients, the first strain was detected again in a subsequent culture. These observations suggest that the presence of two different strains among isolates from sequential cultures may reflect ongoing polyclonal infection. We conclude that polyclonal infection with MAC is common among patients with AIDS. The identification of such infections may be critical in the development of effective treatments. Images PMID:7929773

Slutsky, A M; Arbeit, R D; Barber, T W; Rich, J; von Reyn, C F; Pieciak, W; Barlow, M A; Maslow, J N

1994-01-01

411

Burma: Displaced Karens. Like Water on the Khu Leaf  

Microsoft Academic Search

War disrupts the normal relationship between people and place. Displaced by war, people must adapt to survive, both physically and socially. When people are displaced for a long time, these adaptations become normal; thus displacement starts as an aberration but becomes a constant way of life. In eastern Burma, 'normal' displacement has led to significant changes in the political, cultural

Chris Cusano

1990-01-01

412

Fields  

Microsoft Academic Search

The authors discuss the application of different statistical tests to the study of the spatial distribution of quasars. Applications to data sets of optically selected quasars lead to the detection of a clustering at a typical scale of 10 arcmin. Furthermore, the spatial distribution of quasars in a field around NGC 450 shows a deviation from randomness, towards clustering, at

E. Gosset; J. Surdej; J. P. Swings

1988-01-01

413

Development of A Continuous Process for Displacement Dewatering  

SciTech Connect

The subject of this contract was to investigate the viability of a new process for dewatering paper called displacement pressing. The term “displacement pressing” was coined in the 1980s by researchers to describe a paper dewatering process where air is blown through a sheet of paper while it is being pressed. It was shown at that time that the combination of air and low pressing force could dramatically increase both sheet bulk and sheet solids which in theory would translate into huge savings in energy and fiber consumption. But there was a catch. Although the research results were dramatic, no one could figure out a commercially viable process to carry out displacement pressing. All research work had been done with batch processes, and there was no obvious way to convert these processes into a continuous process. By the end of the early1990’s no one was researching in this area because no continuous process existed. Recently we proposed a new method to carry out displacement pressing. Our process uses special pressing fabrics and a special 4 roll press that we call a “Beck Cluster Press” or BCP. The BCP provides a pressurized atmosphere that acts on a moving web of paper and fabrics. The special fabrics designed for this process use this atmosphere to press the sheet and at the same time, these special fabrics force air through the sheet to carry out displacement pressing. 1 Because of the complexity and cost of building the first functioning BCP, a simple simulator was built to confirm and study the process. Although results from this simulator were extremely favorable, financial times were hard in the paper industry. We are grateful for the DOE contract that allowed us to continue research that showed the tremendous benefits of displacement pressing. Specifically, accomplishments from the DOE contract are as follows: 1. A narrow (5” wide sheet) lab Beck Cluster Press (BCP) was started up, and made operational. This press accepts hand sheets and displacement presses them at conditions that duplicate commercial conditions for dwell time, and pressure. 2. The lab BCP machine was used to verify simulator results. Results showed the lab BCP gave paper dryness that exceeded simulator results for dryness. 3. Sheet samples were obtained for several paper grades. These samples were pressed conventionally (shoe and roll presses) and with the lab BCP. Results showed significant gains in bulk (5-48%) compared to commercially pressed sheets while producing similar or higher dryness. These results verified the predictions of the earlier research papers. 4. Sheet bulk exceeded the Agenda 2020 goal a 7% increase. This increase in bulk was reported by Agenda 2020 as being worth about 3 billion dollars per year in fiber savings. Potential energy savings due to dryness savings could be worth $1 billion per year. However energy savings and fiber savings are inter-related so while savings are likely in both energy and fiber at the same time, increasing one will cause the other to decrease. 5. Based on the significant results of small-scale BCP trials, a 1m pilot BCP press stand was built to determine scalability of the process. 6. 1m pilot press stand was started up. This machine was shown to hold design pressure. Drive issues however prevented operation at operating speed and pressure during the contact period. Improvements to the drive system since the end of the DOE contract have allowed us to reach operating pressure and speed. 7. The last DOE objective of passing paper through the 1m BCP was not reached due to drive issues and the desire to study and qualify sealing systems. All other original objectives and the added objective (by contract revision) of this ambitious project have been met. 8. Several paper companies have showed interest in helping us commercialize this process. Interest is so high that these companies appear willing to invest in further development.

Dave Beck

2006-10-30

414

Crack opening displacement determination in damaged cross-ply laminate using electronic speckle pattern interferometry (ESPI)  

NASA Astrophysics Data System (ADS)

Composite laminates during service undergo complex combinations of thermal and mechanical loading leading to microdamage accumulation in the plies. The most common damage mode and the one examined in this work is intralaminar cracking in layers. The crack opening displacement (COD) and the crack sliding displacement (CSD) during loading reduce the average stress in the damaged layer, thus reducing the laminate stiffness. These parameters depend on material properties of the damaged layer and surrounding layers, on layer orientation and thickness. Previously these parameters have been calculated using finite element method (FEM) assuming linear elastic material with idealized geometry of cracks. To validate these assumptions experimentally the displacement field on the surface of a [90/0/90] carbon fiber/epoxy laminate specimens with multiple intralaminar cracks in the surface layer is studied and the COD dependence on the applied mechanical load is measured. The specimen full-field displacement measurement is carried out using ESPI (Electronic Speckle Pattern Interferometry). The displacement jumps corresponding to cracks are clearly visible and can be used to determine the opening displacement along the cracks. The effect of crack interaction on the COD at high crack density is also investigated.

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

2012-02-01

415

Boundary condition-free elastic modulus reconstructions from ultrasound measured quasi-static displacements.  

PubMed

Quantitative elastic modulus imaging from quasi-static displacement data requires the solution of an inverse elasticity problem. The inverse problem formulation generally requires specification of either displacement or traction boundary conditions. Most current ultrasound devices are not capable of measuring traction data, and the measured displacement field is noisy. The incomplete and imprecise nature of the available boundary information often necessitates that educated guesses be made in order to have adequate knowledge of the boundary conditions to compute mechanical properties. These assumed boundary conditions, however, can to lead to errors in the reconstructions. This abstract proposes a method to perform reconstructions without knowing the boundary conditions a priori. This method relies on using the constrain imposed by the equilibrium equation and an optimization algorithm to estimate the modulus field. This method was verified with simulated displacement data, validated with phantom displacement data, and applied to in-vivo displacement data measured from patients with breast masses. [Authors gratefully acknowledge funding from NSF and NIH (NSF Grant No. 50201109; NIH NCI-R01CA140271).]. PMID:25235053

Babaniyi, Olalekan A; Seidl, Daniel T; Oberai, Assad A; Richards, Michael S; Barbone, Paul E

2014-04-01

416

Estimating changes in rock permeability due to thermal-mechanical effects  

SciTech Connect

This paper presents results of a modeling study of changes in fracture permeability due to thermal-mechanical effects associated with the potential geological repository at Yucca Mountain. a methodology for estimating changes in permeability is developed and applied to the Drift Scale Test (DST) now being conducted in the Exploratory Studies Facility (ESF) at Yucca Mountain. Temperature, stress, and displacement of rock in the heated zone are presented along with predicted zones where slip on fractures may occur. The zones of predicted fracture slip are used as a basis for predicting where permeability may be changed. this new procedure goes beyond previous models that relate stress to strain or displacement, and provides information about rock response that is needed for design of future tests at Yucca Mountain. Our results also contribute to the understanding of coupled processes in the near-field environment of a repository.

Wang, H.F.; Blair, S.C.; Berge, P.A.

1997-10-01

417

Magnetic field calculation and dynamic behavior analyses of the permanent magnetic actuator  

Microsoft Academic Search

Due to its great advantages, the permanent magnetic actuator for a vacuum circuit breaker drew great attention from engineers all over the world. We present the magnetic field and dynamic behavior analyses for the permanent magnetic actuator using finite element method associated with parametrization, for calculating the displacement of the moving parts and the supply current when the actuator is

Lin Xin; Gao Huijun; Cai Zhiyuan

2000-01-01

418

Temporal variations of the gravity field and Earth precession-Nutation  

Microsoft Academic Search

Due to the accuracy now reached by space geodetic techniques, the temporal variations of a few Earth gravity field coefficients can be determined. Such variations result from Earth oceanic and solid tides, as well as from geophysical reservoirs masses displacements and post-glacial rebound. They are related to variations in the Earth's orientation parameters through their effect in the inertia tensor.

G. Bourda; N. Capitaine

2004-01-01

419

Increased upconversion quantum yield in photonic structures due to local field enhancement and modification of the local density of states--a simulation-based analysis.  

PubMed

In upconversion processes, two or more low-energy photons are converted into one higher-energy photon. Besides other applications, upconversion has the potential to decrease sub-band-gap losses in silicon solar cells. Unfortunately, upconverting materials known today show quantum yields, which are too low for this application. In order to improve the upconversion quantum yield, two parameters can be tuned using photonic structures: first, the irradiance can be increased within the structure. This is beneficial, as upconversion is a non-linear process. Second, the rates of the radiative transitions between ionic states within the upconverter material can be altered due to a varied local density of photonic states. In this paper, we present a theoretical model of the impact of a photonic structure on upconversion and test this model in a simulation based analysis of the upconverter material ? -NaYF(4):20% Er(3+) within a dielectric waveguide structure. The simulation combines a finite-difference time-domain simulation model that describes the variations of the irradiance and the change of the local density of photonic states within a photonic structure, with a rate equation model of the upconversion processes. We find that averaged over the investigated structure the upconversion luminescence is increased by a factor of 3.3, and the upconversion quantum yield can be improved in average by a factor of 1.8 compared to the case without the structure for an initial irradiance of 200 Wm(-2). PMID:24104583

Herter, Barbara; Wolf, Sebastian; Fischer, Stefan; Gutmann, Johannes; Bläsi, Benedikt; Goldschmidt, Jan Christoph

2013-09-01

420

Variable-Displacement Hydraulic Drive Unit  

NASA Technical Reports Server (NTRS)

Hydraulic power controlled through multiple feedback loops. In hydraulic drive unit, power closely matched to demand, thereby saving energy. Hydraulic flow to and from motor adjusted by motor-control valve connected to wobbler. Wobbler angle determines motor-control-valve position, which in turn determines motor displacement. Concept applicable to machine tools, aircraft controls, and marine controls.

Lang, D. J.; Linton, D. J.; Markunas, A.

1986-01-01

421

Displacement of Bilirubin from Albumin by Berberine  

Microsoft Academic Search

A study was made of the effect of berberine, the major ingredient of the Chinese herb huanglian (coptis chinensis) reported to pose some risk for kernicterus among jaundiced newborn Chinese infants, on the protein binding of bilirubin, using the peroxidase kinetic method. Berberine was found in vitro, as to its displacing effect on a molar basis, to be about tenfold

Eli Chan

1993-01-01

422

Television and Schooling: Displacement and Distraction Hypotheses.  

ERIC Educational Resources Information Center

Research on two hypotheses regarding television's possible negative effect on children's academic achievement is reviewed. A lack of support is found for the displacement hypothesis (time spent with television is taken away from more academically beneficial activities) and limited support for the distraction hypothesis (exposure to television…

Roberts, Donald F.; And Others

1993-01-01