These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

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

SciTech Connect

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

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

2013-01-01

2

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

3

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

ERIC Educational Resources Information Center

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

Buschauer, Robert

2014-01-01

4

Crustal Displacements Due to Continental Water Loading  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

5

Respiratory failure due to a displaced fracture of the odontoid.  

PubMed

Fractures of the odontoid peg are relatively common in elderly people. Often they are minimally displaced and can be treated with a collar. However, a fracture which is displaced significantly may be difficult to manage. We describe the case of an 80-year-old man with a fracture of the odontoid peg which was completely displaced and caused respiratory distress. After initial closed reduction and application of a halo jacket, open and internal fixation was undertaken and relieved his symptoms. It is a safe and effective way to manage this injury. PMID:20595126

Clarke, A; Hutton, M J; Chan, D

2010-07-01

6

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...

7

Study of displacement and residual displacement field of an interface crack by moire interferometry  

Microsoft Academic Search

Moire interferometry was used to study the deformation field and the residual deformation field around a crack laying along the interface of the adhesive layer and the adherend of graphite epoxy composite. Two steps of the experiment were carried on. First, the specimen was loaded in four levels and the fringe patterns were recorded for analyzing the in-plane displacements under

Y. Y. Wang; Fu-Pen Chiang; Roshdy G. Barsoum; S. T. Chou

1991-01-01

8

Calculation of Crystallographic Texture due to Displacive Transformations  

E-print Network

­controlled weld metals, as a means for counteracting the development of residual stresses in welds. Welding [7, 8] as can heat­treatment in an electrical or magnetic field [9]. In solid­state phase transitions

Cambridge, University of

9

Application of miscible displacement for Field MTX low permeability formations  

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

10

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

E-print Network

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

Paris-Sud XI, Université de

11

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

12

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

13

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

NASA Astrophysics Data System (ADS)

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

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

2015-06-01

14

Pneumatic displacement with intravitreal bevacizumab for massive submacular hemorrhage due to polypoidal choroidal vasculopathy  

PubMed Central

Background The purpose of this study was to compare the effectiveness of pneumatic displacement combined with intravitreal bevacizumab (IVB) with that of pneumatic displacement (PD) alone to treat massive submacular hemorrhage (SMH) secondary to polypoidal choroidal vasculopathy (PCV). Methods Thirty-two eyes of 32 patients with massive SMH secondary to PCV were studied. Twenty-two eyes were treated with a combination of PD and 1.25 mg of intravitreal bevacizumab (PD + IVB group), and ten eyes with pneumatic displacement alone (PD group). Results Pretreatment, the differences in best-corrected visual acuity and size of the SMH between the two groups were not significant (P=0.59 and P=0.72, respectively). Complete displacement of the hemorrhage from under the fovea was achieved in 19 of 22 eyes (86.4%) in the PD + IVB group and in five of ten eyes (50%) in the PD group. The best-corrected visual acuity in the PD + IVB group was significantly better than that in the PD group at one, 3, and 6 months after treatment (P<0.001, P<0.001, and P<0.001, respectively). Improvement in best-corrected visual acuity by >0.3 logMAR units was obtained in 18 eyes (81.8%) in the PD + IVB group and two eyes (20%) in the PD group (P<0.001). The number of eyes that required additional treatments was significantly fewer in the PD + IVB group than in the PD group (P=0.0001). Conclusion The combination of PD and IVB may be a better therapeutic procedure for eyes with massive SMH due to PCV in the short term because of the better visual outcome and less need for additional treatments. PMID:24623972

Kitahashi, Masayasu; Baba, Takayuki; Sakurai, Madoka; Yokouchi, Hirotaka; Kubota-Taniai, Mariko; Mitamura, Yoshinori; Yamamoto, Shuichi

2014-01-01

15

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

Microsoft Academic Search

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

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

2002-01-01

16

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

17

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

18

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

E-print Network

-generated mixed-made displacement fringe patterns Previous work by Barker, Sanford, and Chona7'S has addressed this problem of rigid-body motion in displacement Belds using an overdeterrmnistic, multiple- point, least-squares solution scheme for the case... with the presence of nonstrain-related fringes. In 1980, Sanford developed the least-squares algorithm in matrix form as a solution scheme to determine a set of parameters from full-field fringe patterns. This method takes advantage of computers and image...

Matsumoto, Kay Yuri

1995-01-01

19

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

NASA Astrophysics Data System (ADS)

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

de La Torre-Ibarra, Manuel H.; Ruiz, Pablo D.; Huntley, Jonathan M.

2006-10-01

20

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

21

Electronic Transport in Dual-Gated Bilayer Graphene at Large Displacement Fields  

E-print Network

We study the electronic transport properties of dual-gated bilayer graphene devices. We focus on the regime of low temperatures and high electric displacement fields, where we observe a clear exponential dependence of the ...

Taychatanapat, Thiti

22

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

23

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

E-print Network

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

Keener, Todd Whitney

1996-01-01

24

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

SciTech Connect

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

Katsura, T. (National Laboratory for High Energy Physics, 1-1 Oho, Tsukuba, Ibaraki 305 (Japan)); Fujita, Y. (Nuclear Power Division, Shimizu Corporation, No. 2-3, Shibaura 1-chome, Minato-ku, Tokyo 105 (Japan))

1991-11-01

25

Induced electric and magnetic fields due to wave propagation in a tubular bone.  

PubMed

Electric and magnetic fields in tubular bones induced due to the propagation of travelling axisymmetric torsional waves, are determined in the paper by accounting for the piezoelectricity, inhomogeneity and anisotropy of osseous tissues. Using the derived expressions and experimentally determined values of the involved physical constants, numerical values of the displacement and stress fields, and also the induced fields are computed for points at different locations of the bone specimen. PMID:3351392

Misra, J C; Bera, G C; Samanta, S

1988-01-01

26

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

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

27

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

28

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

PubMed

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

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

2014-08-01

29

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

SciTech Connect

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

Lanfranfo, Giobatta; Fast, James; /Fermilab

2001-07-01

30

Displacement Current and the Generation of Parallel Electric Fields  

SciTech Connect

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

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

2006-04-14

31

Displacement current and the generation of parallel electric fields.  

PubMed

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

Song, Yan; Lysak, Robert L

2006-04-14

32

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

33

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

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

34

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

35

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

36

Determining velocity displacement field from cardiac image sequence  

NASA Astrophysics Data System (ADS)

Estimation of left ventricle motion and deformation from series of images has been an area of attention in the medical image analysis and still remains an open and challenging problem. Left ventricle contractile abnormalities can be an important manifestation of coronary artery disease. The proper motion tracking of left ventricle wall can contribute to isolate the location and extent of ischemic or infarcted myocardium and constitutes a fundamental goal of image modalities, such as Nuclear Medicine. This work describes a method to automatically estimate the velocity vector field for a beating heart based on the study of variation in frequency content in a series of 2D images as time varies. The frequency analysis is performed by computing the Wigner-Ville and the Choi-Williams distributions to each image pixel, yielding the corresponding 3D-frequency spectrum. From this 3D spectrum the local velocity of each pixel is calculated by employing a multiple linear regression model. Experimental validation was carried out using synthetic phantoms that simulate translation and rotation between successive frames. Results obtained from gated SPECT perfusion studies are also presented.

Meyering, Wietske I.; Gutierrez, Marco A.; Robilotta, Cecil C.; Furuie, Sergio S.

2002-04-01

37

Generation displacement, power losses and emissions reduction due to solar thermal water heaters  

Microsoft Academic Search

A big portion of the electricity generated is wasted in the form of losses. Losses occur at all levels of the power system- generation, transmission, and distribution. However, at least 75% of the total system losses occur in the distribution system. We present a study of real power losses reduction at the distribution level due to the use of solar

J. Jimenez-Gonzalez; A. A. Irizarry-Rivera

2005-01-01

38

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

39

Interpretation of Pulsed-Field-Gradient NMR in Terms of Molecular Displacements  

E-print Network

The relationship for Pulsed-Field-Gradient NMR between the amplitude $I(t)$ of the spin echo and the molecular displacement ${\\bf X}(t)$ is examined. $I(t)$ of a single species in a simple solution is determined by the mean-square displacement $\\bar{X(t)^{2}}$. With polydisperse species, or molecular probes in complex fluids showing memory effects, $I(t)$ in general includes large contributions from all higher even moments $\\bar{X(t)^{2n}}$. Conditions under which the NMR signal is indeed determined by the molecular mean-square displacement are noted. A diagnostic that sometimes identifies when these conditions are not met is presented.

George D. J. Phillies

2011-02-22

40

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

NASA Astrophysics Data System (ADS)

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

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

2011-07-01

41

Graphically oriented method for obtaining atomic displacement fields in crystals from irreducible representations of space groups  

NASA Astrophysics Data System (ADS)

A method for obtaining distortion fields in a crystal from a given irreducible representation of the underlying space group is described. The method, based on projection operators of group theory, is graphically oriented and therefore calculation-free. For an example (space group P4¯21m), complete sets of representation matrices are analytically calculated for all irreducible representations which correspond to all wave vectors of the form k=(q,q,0). All 96 linear independent atomic displacement modes in the (3×3×1) supercell, which are induced by the two irreducible representations with k=(13,13,0), are explicitly determined: the obtained atomic displacement fields are plane waves with wave vector k.

Gutmann, Jürgen K.; Böhm, Horst

2000-06-01

42

Identification of plastic constitutive parameters at large deformations from three dimensional displacement fields  

Microsoft Academic Search

The aim of this paper is to provide a general procedure to extract the constitutive parameters of a plasticity model starting\\u000a from displacement measurements and using the Virtual Fields Method. This is a classical inverse problem which has been already\\u000a investigated in the literature, however several new features are developed here. First of all the procedure applies to a general

Marco Rossi; Fabrice Pierron

2011-01-01

43

Electric-field-induced displacement of a charged spherical colloid embedded in an elastic Brinkman medium  

E-print Network

When an electric field is applied to an electrolyte-saturated polymer gel embedded with charged colloidal particles, the force that must be exerted by the hydrogel on each particle reflects a delicate balance of electrical, hydrodynamic and elastic stresses. This paper examines the displacement of a single charged spherical inclusion embedded in an uncharged hydrogel. We present numerically exact solutions of coupled electrokinetic transport and elastic-deformation equations, where the gel is treated as an incompressible, elastic Brinkman medium. This model problem demonstrates how the displacement depends on the particle size and charge, the electrolyte ionic strength, and Young's modulus of the polymer skeleton. The numerics are verified, in part, with an analytical (boundary-layer) theory valid when the Debye length is much smaller than the particle radius. Further, we identify a close connection between the displacement when a colloid is immobilized in a gel and its velocity when dispersed in a Newtonian electrolyte. Finally, we describe an experiment where nanometer-scale displacements might be accurately measured using back-focal-plane interferometry. The purpose of such an experiment is to probe physicochemical and rheological characteristics of hydrogel composites, possibly during gelation.

Reghan J. Hill; Martin Ostoja-Starzewski

2007-07-17

44

Instantaneous velocity field measurements of a turbulent rectangular jet (AR-4) using particle image displacement velocimetry  

NASA Technical Reports Server (NTRS)

A whole field experimental technique, commonly referred to as Particle Image Displacement Velocimetry (PIDV) is used for the measurement of the two dimensional instantaneous velocity fields in the transition region of a three dimensional jet issuing from a rectangular nozzle of an aspect ratio 4. The instability process of an initially laminar jet is studied visually and quantitatively to determine the structure and growth of the mixing region of the jet. The experiments were performed using an air jet at a Reynolds number based on the hydraulic diameter of 3600. The roll-up of the laminar shear layer into vortices and their subsequent interactions are examined.

Lourenco, L.; Krothapalli, A.

1988-01-01

45

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

46

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

47

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

48

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

49

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

50

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

51

Surface displacement field at Terceira island deduced from repeated GPS measurements  

NASA Astrophysics Data System (ADS)

We present the results of six GPS (Global Positioning System) campaigns held in Terceira Island (Azores) between 1999 and 2006 for a group of 17 stations, to estimate the surface displacement field induced by the Eurasian-Nubian interplate motion, and their relationship with the rifting along Terceira Rift and volcanic processes at the island scale. We show that the whole island mainly behaves like a rigid body which absolute motion is closer to Eurasia. The magnitude of the computed intra-island horizontal deformation field (difference between the individual site velocities and the mean rigid-body motion) is still below the observation accuracy, and so cannot be directly related with local processes. We also show that the island is globally subsiding with an average rate close to 1 mm/yr, as it moves to the NE away from the Terceira Rift, mostly attached to the Eurasian plate. The high subsidence rate can be the result of the volcanic processes that shaped the Serreta ridge, NW of Terceira.

Miranda, J. M.; Navarro, A.; Catalão, J.; Fernandes, R. M. S.

2012-03-01

52

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

53

Preliminary design of land displacement-optical fiber sensor and analysis of observation during laboratory and field test  

NASA Astrophysics Data System (ADS)

An optical fiber optic sensor for detecting land displacement is discussed in this paper. The sensor system consists of a laser at wavelength 1.3 um, optical fiber coupler, optical fiber as sensor and light transmitting media, PIN photodiodedetector system, data logger and personal computer. Sensor was made from a curved optical fiber with diameter 35 mm, which will be changed into a heart-shape fiber if it is pulled. The heart-shape fiber sensor is the modification of the earlier displacement fiber sensor model which was in an ellipse form. Light to and from the optical fiber sensor was transmitted into a length of a multi core, single mode optical fiber cable. The scheme of the optical displacement sensor system has been described here. Characterization in the laboratory has been done by applying a series of pulling mechanism, on the heart-shape fiber sensor; which represents the land displacement process. Characterization in the field was carried out by mounting the sensor system on a scaled-down model of a land slope and artificially reproducing the landslide process using a steady-flow of artificial rainfall as the trigger. The voltage sensor output was recorded during the artificial landslide process. The displacement occurence can be indicated from the declining of the sensor signal received by the detector while the reference signal is steady. Characterization in the laboratory resulted in the performance of the optical fiber land displacement, namely, sensitivity 0.027(mV/mV)/mm, resolution 0.37 mm and measurement range 30 mm; compared with earlier optical fiber sensor performance with similar sensitivity and resolution which works only in 8 mm displacement range. Based on the experiment of landslides simulation in the field, we can define a critical condition in the real situation before landslides occurence to take any measures to prevent more casualties and losses.

Bayuwati, Dwi; Waluyo, Tomi B.; Widiyatmoko, Bambang

2015-01-01

54

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

NASA Astrophysics Data System (ADS)

The screw dislocation model (Weertman & Weertman, 1966) gives the horizontal displacement u as a function of the vertical distance d to the dislocation, the horizontal distance x and the slip s on each side of the dislocation. u = - (s/?) arctan(x/d) Savage and Burford (1973) interpreted this model in terms of horizontal displacement across a strike slip fault which is locked down to depth d, s being the plate velocity. Because of its simplicity and because the arctangent shape well represents the displacement that can be measured around most of the major strike slip faults, this model is commonly used to match geodetic data. We present numerical simulations that have been made with the software CASTEM, a finite element code for structural and mechanical modeling. The models are rectangular boxes that have elastic or viscoelastic properties, and three different kinds of conditions are applied on the boundaries of the domain that may have an impact on the localization of the displacement near the fault plane. The first boundary condition imposes the displacement under the plate, this case has been chosen because of its similarity to the Weertman's screw dislocation model. The second boundary condition imposes the displacement in the front, it corresponds to an extrusion. For the third boundary condition, the displacement is imposed laterally and simulates the general plate motion that drags the domain on both sides. We found that the displacement at the free surface does not fit an arctangent in all cases. If a perfectly elastic, homogeneous domain is used, only the first two types of boundary conditions lead to a displacement field resembling the geodetic data. This is awkward since the third kind of boundary conditions seems to be geologically the more relevant one. We then introduced local rheological modifications to reduce locally the equivalent elastic plate thickness in the vicinity of the fault. This is achieved by introducing a viscoelastic relaxation in the model. We point out that a shorter maxwell relaxation time beneath the strike slip fault results in an arctangent like displacement field at the surface and discuss the long term geodynamic basis for this low viscosity zone to form, with regard to the metamorphic core complexes formation. Finally, we compare the results with 3D thermo-mechanical models made with Gale, a CIG code that solves Stokes' problems with a viso-plastic formulation. These models localize the deformation on longer time scale with the formation of a self-consistent viscous notch beneath the fault. Thus, we show that our model, combining viscoelastic properties and geologically relevant boundary conditions, also matches long term rheological behaviors of strike slip faults, and then, that it is compatible with both short and long time scales.

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

2012-04-01

55

Correction of liver displacement due to irregular respiration for SPECT images obtained using a multiple short-time acquisition with breath-holding technique.  

PubMed

Recently, a new method for acquiring single photon emission computed tomography (SPECT) data during breath-holding with a high-speed rotation (HSR-SPECT) technique was applied to hepatic-function scintigraphy. This technique can suppress motion artifact caused by respiration. However, it is challenging to apply this technique to patients with respiratory problems. Our purpose in this study was to analyze projection data and correct liver displacement due to irregular respiration during technetium-99m-diethylenetriaminepentaacetic acid galactosyl human serum albumin ((99m)Tc-GSA) liver SPECT scans. We calculated cross-correlation functions (CCFs) for both intra- and inter-projections to correct irregular projections by shifting them in the longitudinal direction enough to maximize the CCFs. We integrated all of the shifted projections and created a synthesis projection which was used to reconstruct SPECT images. To confirm the effectiveness of our method, we did both a phantom study and a clinical retrospective review. In the phantom study, blurring artifacts due to displacement were reduced using our method. Post-processing using our method showed improvements in the normalized mean square error values ranging from 0.18 to 0.06. Furthermore, our method showed no disadvantage or miss-correction if we applied our method to data without displacement. In the clinical review, our method improved the image clarity for patients who could not repeat consistent respiration. In both the phantom simulation and the clinical application, the results showed the usefulness of our method. The efficiency of our method has the potential to reduce the displacement problem caused by respiration and provides excellent matching SPECT/CT fusion images. PMID:22038313

Ueda, Yasuyuki; Kudomi, Shohei; Koike, Masahiro; Oishi, Yona; Iwanaga, Hideyuki; Ueda, Katsuhiko

2012-01-01

56

Magnetic field distribution due to domain walls in unconventional superconductors  

NASA Astrophysics Data System (ADS)

Steady-state properties of 180? Bloch domain walls (DWs) in superconducting ferromagnets (SCFMs) are studied. The distribution of the magnetic field above and below the surface of the SCFM due to the permanent magnetization supercurrent flowing in the DW plane is calculated by solving Maxwell equations supplemented by the London equation. It is shown that part of the magnetic flux of the two neighboring domains closes in the nearest vicinity of the surface of the sample, giving rise to a decline in the direction of the field from the parallel to the DW plane. As a result, the value of the normal component of the magnetic field at the surface of the sample reaches only half of the value of the bulk magnetic flux. At distances greater than the London penetration depth, the magnetic field decreases as an inverse power law due to the long-range character of the dipole-dipole interaction. The last two circumstances are important for comparing the calculated magnetic field with data obtained by using methods based on measuring the normal component of magnetic field, aiming to confirm the existence of the magnetic order parameter in unconventional superconductors.

Logoboy, N. A.

2008-02-01

57

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

NASA Astrophysics Data System (ADS)

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

Fukao, Yoshio; Hori, Takane; Kodaira, Shuichi

2014-05-01

58

Flow damping due to stochastization of the magnetic field  

PubMed Central

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

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

2015-01-01

59

Flow damping due to stochastization of the magnetic field.  

PubMed

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

Ida, K; Yoshinuma, M; Tsuchiya, H; Kobayashi, T; Suzuki, C; Yokoyama, M; Shimizu, A; Nagaoka, K; Inagaki, S; Itoh, K

2015-01-01

60

A new optical field generated as an output of the displaced Fock state in an amplitude dissipative channel  

NASA Astrophysics Data System (ADS)

We propose a new optical field and show that such an optical field can be generated as an output of a displaced Fock state in an amplitude dissipative channel. We derive new generating function formulas and binomial formula involving two-variable Hermite polynomials to reach this result. The photon number average in this new optical field is which indicates that controlling the photon number can be realized by adjusting the value of m or |?|2 or ?. The time evolution law of displaced Fock state in a thermo reservoir is thus revealed. Project supported by the National Natural Science Foundation of China (Grant Nos. 11174114 and 11175113)and the Natural Science Foundation of Wuxi Institute of Technology of China (Grant No. 4013012931).

Xu, Xue-Fen; Fan, Hong-Yi

2015-01-01

61

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

62

On the Vertigo Due to Static Magnetic Fields  

PubMed Central

Vertigo is sometimes experienced in and around MRI scanners. Mechanisms involving stimulation of the vestibular system by movement in magnetic fields or magnetic field spatial gradients have been proposed. However, it was recently shown that vestibular-dependent ocular nystagmus is evoked when stationary in homogenous static magnetic fields. The proposed mechanism involves Lorentz forces acting on endolymph to deflect semicircular canal (SCC) cupulae. To investigate whether vertigo arises from a similar mechanism we recorded qualitative and quantitative aspects of vertigo and 2D eye movements from supine healthy adults (n?=?25) deprived of vision while pushed into the 7T static field of an MRI scanner. Exposures were variable and included up to 135s stationary at 7T. Nystagmus was mainly horizontal, persisted during long-exposures with partial decline, and reversed upon withdrawal. The dominant vertiginous perception with the head facing up was rotation in the horizontal plane (85% incidence) with a consistent direction across participants. With the head turned 90 degrees in yaw the perception did not transform into equivalent vertical plane rotation, indicating a context-dependency of the perception. During long exposures, illusory rotation lasted on average 50 s, including 42 s whilst stationary at 7T. Upon withdrawal, perception re-emerged and reversed, lasting on average 30 s. Onset fields for nystagmus and perception were significantly correlated (p<.05). Although perception did not persist as long as nystagmus, this is a known feature of continuous SSC stimulation. These observations, and others in the paper, are compatible with magnetic-field evoked-vertigo and nystagmus sharing a common mechanism. With this interpretation, response decay and reversal upon withdrawal from the field, are due to adaptation to continuous vestibular input. Although the study does not entirely exclude the possibility of mechanisms involving transient vestibular stimulation during movement in and out of the bore, we argue these are less likely. PMID:24205304

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

2013-01-01

63

Realization of high sensitivity displacement field from moiré interferometer with rough phase shifting mechanism and pattern matching technique  

NASA Astrophysics Data System (ADS)

In this study, phase shifting method is used to modify moiré system into micro moiré interferometer which can measure displacement field with highly improved sensitivity. Apart from existing micro moiré technique, a low cost and less precise translation stage with rough resolution (10 ?m resolution) is adapted for the phase shifter. Least square algorithm is applied to estimate the arbitrary phase shifted amount and to minimize the errors induced by lowering the cost. Moreover, specimen grating is phase shifted instead of reference grating which enables simple construction from given moiré system. To compensate for rigid body in-plane translation of specimen that may occur during phase shifting, pattern matching algorithm is put into practice to ensure pixel correspondence for each phase shifted images. To verify the newly constructed micro moiré technique, local displacement fields of Fine pitch Ball Grid Array package and Wafer Level Chip Size Package with elevated sensitivity up to 26 nm per fringe was acquired.

Yang, Se Young; Lee, Soon-Bok

2005-06-01

64

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

65

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

66

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

NASA Astrophysics Data System (ADS)

The screw dislocation model (Weertman & Weertman, 1966) gives the horizontal displacement u as a function of the vertical distance d to the dislocation, the horizontal distance x and the slip s on each side of the dislocation. (Eq. 1) u = (s/?) arctan(x/d) Savage and Burford (1973) interpreted this model in terms of horizontal displacement across a strike slip fault which is locked down to depth d, s being the plate velocity. Because of its simplicity (only two parameters used and the solution being independent of elastic properties) this model has become very popular and is commonly used to match geodetic data and infer the size of locked patches of active strike slip faults such as the San Andreas Fault. The plane section where the geodetic u is measured is the Earth's surface, which behaves as a free surface. Yet, originally in the screw dislocation model, the half space above the dislocation is infinite and therefore, on the horizontal section where Eq. 1 is verified, the state of stress is radically different to the one that occurs at the surface of earth. In order to evaluate the error generated by this approximation, numerical simulations have been tested with the software CASTEM, a finite element code for structural and mechanical modelling. We find that the displacement at the free surface fits an arctangent as in Eq. 1 but with an effective locking depth d about twice smaller than the one we input in the numerical model. It remains that the arctangent shape well represents the displacement that can be measured around most strike slip faults. For that purpose, we present various physical models, using elastic or viscoelastic properties and several kinds of boundary conditions, that may have an impact on the localization of the displacement. We set three different kinds of imposed displacement, at the front, underneath or on the lateral sides of the domain. The first type of boundary conditions corresponds to an oceanic transform set up where the displacement is imposed by the accretion parallel to the strike slip fault. The second type corresponds to the Savage model with a displacement imposed locally underneath the elastic plate. The third type corresponds to the case where the plates motion drags laterally the domain on both sides. If a perfectly elastic, homogeneous domain is used, only the first two types of boundary conditions lead to a displacement field resembling the geodetic data. This is awkward since the third kind of boundary conditions seems to be geologically the more relevant one. We also introduce local rheological modifications to reduce locally the equivalent elastic plate thickness in the vicinity of the fault. This is achieved by introducing a viscoelastic relaxation in the model. We show that a shorter maxwell relaxation time beneath the strike slip fault results in an arctangent like displacement field at the surface and discuss the long term geodynamic basis for this low viscosity zone to form.

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

2011-12-01

67

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

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

68

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

NASA Astrophysics Data System (ADS)

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

Soons, Joris; Dirckx, Joris J. J.

2010-09-01

69

Impulse Representation of Sound Field due to a Rigid Wedge  

NASA Astrophysics Data System (ADS)

An impulse representation for calculating a diffraction wave due to a rigid wedge is described. The method is an approximation of the Biot-Tolstoy rigorous closed-form solution for the diffraction of point source radiation by an infinite rigid wedge. The band-limited time-domain function can be reconstructed to the original waveform if it satisfies the sampling theorem, which assumes that sampling takes place at the lowest permissible sampling rate. Therefore, if the energy is concentrated between the first sampling intervals immediately after the rise time of the time-domain function, the rigorous solution can be approximated as a delta function. This paper shows the description methods of the diffraction field near the ridge in three-dimensional space. Using the proposed impulse representation, numerical simulation was performed and the calculation accuracy was examined.

Lawu, Tjundewo; Ueda, Mitsuhiro

2004-05-01

70

Finite deformation and displacement fields on the southern yemen margin using satellite images, topographic data and a restoration method  

NASA Astrophysics Data System (ADS)

Geological interpretations of processed satellite images and structural field measurements were used to calculate the amount of extension and the finite displacement field of two stretched areas located on the northern margin of the Gulf of Aden, in Yemen. This calculation was done by a comparison between the deformed and the undeformed states of each studied area. The structural setting established from satellite-image interpretations and fieldwork yields a detailed geometry of the deformed state. The undeformed state was reconstructed from reference layers chosen on satellite images from folded and faulted geological markers. The strike and dip of those layers were computed directly from dip indicator measurements, identified on three-dimensional (3D) realistic views of the sites (derived from SPOT stereoscopic views and topographic data) and controlled by field measurements. From the previous structural data, a numerical model of the deformed state was prepared with respect to the structural setting. The two stretched areas were then restored to their undeformed state successively by (1) an unfolding method (use of the UNFOLD program on each folded piece bounded by faults), and (2) a best-fit method (fitting along the boundary of the unfolded pieces). The comparison between the deformed and undeformed states leads to quantifying the amount of strain and to establishing the total finite displacement field. The results point to differences in the amount of extension and in the finite displacement field between the two areas studied. Within the regional context of the Afar triple junction kinematics, this leads to the conclusion that there was an early extensional tectonic phase recorded on the southern Yemen margin, probably linked to the earlier opening of the Gulf of Aden.

Thoue, Frédéric; Vidal, Gérard; Gratier, Jean-Pierre

1997-11-01

71

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

PubMed Central

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

Scott, R J; Foster, S A

2000-01-01

72

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.

73

Numerical Simulation of a Displacement Ventilation System with Multi-heat Sources and Analysis of Influential Factors  

E-print Network

Displacement ventilation (DV) is a promising ventilation concept due to its high ventilation efficiency. In this paper, the application of the CFD method, the velocity and temperature fields of three-dimensional displacement ventilation systems...

Wu, X.; Gao, J.; Wu, W.

2006-01-01

74

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

75

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

SciTech Connect

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

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

1981-10-01

76

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

77

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

78

Hydrologic changes at Tauhara field due to exploitation of Wairakei field  

SciTech Connect

The major thermal areas of Tauhara field are situated around the town of Taupo, about 8 km from the Wairakei production borefield. Within Taupo, over 400 wells have been drilled to between 30 and 150 m depth, tapping the near-surface hot water of Tauhara field for domestic heating. Analysis of many measurements made since the 1950's in both domestic wells and the hot springs of Tauhara field has failed to find evidence of a widespread decline in water level or near-surface aquifer pressure. However, a significant increase in both temperature of the near-surface aquifer, and heat flow from thermal areas of Tauhara field has occurred since the mid-1960's. This has resulted in a spread of steaming ground and 3 hydrothermal eruptions on the outskirts of Taupo. A study of pressure changes in deep wells of Tauhara field suggests a decline of around 18 bars has occurred at >400 m depth, due to exploitation at Wairakei. The deep reservoir pressure of Tauhara field is now about 7 bars higher than that of Wairakei field, and significant flow towards Wairakei production borefield is probably occurring. The lack of a significant pressure drop in the surface aquifer of Tauhara field is due to the presence of low permeability lacustrine mudstone layers covering most of the field between 100 and 400 m depth. Deep drawdown of the field has caused a steam zone to form beneath the mudstone layers, and this in turn has caused the increase in steam-heating of the surface aquifer.

Allis, R.G.

1982-01-01

79

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

Microsoft Academic Search

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

Edward K. Onuma; Sek-Wen Hui

1988-01-01

80

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

81

Electromagnetic Field Inside the Building Due to Lightning Stroke  

Microsoft Academic Search

The prediction of electromagnetic fields and their induced effects have become a mandatory requirement in the design phase of lightning protection systems. In the present paper authors are used NEC-2 (Numerical Electromagnetic Code) for computing electromagnetic field at different location, inside a building with 36 m height

B. Vahidi; Sh. Farokhi

2005-01-01

82

Special Relativity and Fields Short questions, due 6th October  

E-print Network

= ara Ã? pa and R = a(tpa - (Ea/c2 )ra) for the explicit matrix structure of the angular momentum tensor the kinetic energy, whereas the magnetic field does not? [2] 4.3 Consider a charged particle in a uniform.4. Explain briefly how a charged particle moves in a magnetic field and why this is the case. [2] 4

St Andrews, University of

83

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

84

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

85

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

86

Neutron star deformation due to multipolar magnetic fields  

NASA Astrophysics Data System (ADS)

Certain multiwavelength observations of neutron stars, such as intermittent radio emissions from rotation-powered pulsars beyond the pair-cascade death line, the pulse profile of the magnetar SGR 1900+14 after its 1998 August 27 giant flare and X-ray spectral features of PSR J0821-4300 and SGR 0418+5729, suggest that the magnetic fields of non-accreting neutron stars are not purely dipolar and may contain higher order multipoles. Here, we calculate the ellipticity of a non-barotropic neutron star with (i) a quadrupole poloidal-toroidal field, and (ii) a purely poloidal field containing arbitrary multipoles, deriving the relation between the ellipticity and the multipole amplitudes. We present, as a worked example, a purely poloidal field comprising dipole, quadrupole and octupole components. We show the correlation between field energy and ellipticity for each multipole, that the l = 4 multipole has the lowest energy, and that l = 5 has the lowest ellipticity. We show how a mixed multipolar field creates an observationally testable mismatch between the principal axes of inertia (to be inferred from gravitational wave data) and the magnetic inclination angle. Strong quadrupole and octupole components (with amplitudes ˜102 times higher than the dipole) in SGR 0418+5729 still yield ellipticity ˜10-8, consistent with current gravitational wave upper limits. The existence of higher multipoles in fast-rotating objects (e.g. newborn magnetars) has interesting implications for the braking law and hence phase tracking during coherent gravitational wave searches.

Mastrano, A.; Lasky, P. D.; Melatos, A.

2013-09-01

87

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

Microsoft Academic Search

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

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

2009-01-01

88

Holographic analysis of near-field acoustic displacement patterns of operating sonar transducer arrays  

NASA Astrophysics Data System (ADS)

Target discrimination and recognition are dependent on the understanding of the dynamic acoustic information processed by a given sonar array. Visualization of the true near-field acoustic energy distribution of an active sonar array would be of great value to the understanding of the effects of structural defects in the array and its interface to the water medium. Knowledge of the projected near-field acoustic energy would also enhance the analysis of returned signals for homing and target recognition. Holographic interferometry has presented itself as a viable and useful method for the realization of this type of information.

Fein, Howard

1993-10-01

89

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

NASA Astrophysics Data System (ADS)

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

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

2005-04-01

90

Time displacement for a wall-stabilized electric arc in a transverse magnetic field.  

E-print Network

magnetic field ; this is frequently employed in arc welding techniques and in DC arc circuit], Meier et al. [13]). Although these arcs are usually cooled by surrounding them with an axial argon gas electrodes and the gas was argon of 99.996 % purity. The arc was switched on by connecting the electrod- es

Paris-Sud XI, Université de

91

Electric fields in the human body due to electrostatic discharges.  

PubMed

Electrostatic discharges (ESDs) occur when two objects at different electric potentials come close enough to arc (spark) across the gap between them. Such discharges may be either single-event or repetitive (e.g., 60 Hz). Some studies have indicated that ESDs may be a causative factor for health effects in electric utility workers. Moreover, a hypothesis has recently been forwarded imperceptible contact currents in the human body may be responsible for health effects, most notably childhood leukemia. Numerical modeling indicates that the electric fields in human tissue resulting from typical contact currents are much greater than those induced from typical exposures to electric and magnetic fields at power line frequencies. Numerical modeling is used here to compute representative spark-discharge dosimetry in a realistic human adult model. The frequency-domain scalar potential finite difference method is applied in conjunction with the Fourier transform to assess electric fields in selected regions and tissues of interest in the body. Electric fields in such tissues as subcutaneous fat (where peripheral nerves may be excited), muscle and bone marrow are of the order of kilovolts per meter in the lower arm. The pulses, however, are of short duration (approximately 100 ns). PMID:15311833

Dawson, T W; Stuchly, M A; Kavet, R

2004-08-01

92

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

NASA Astrophysics Data System (ADS)

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

Hagene, J. K.

2012-04-01

93

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

94

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

95

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

96

Effect of Cyclotron Resonance Frequencies in Particles Due to AC and DC Electromagnetic Fields  

E-print Network

alternating volt- age. Specific biological interaction with extremely low fre- quency (ELF) magnetic fields] observed low frequency magnetic fields interact with biological systems when the fields are adjustedEffect of Cyclotron Resonance Frequencies in Particles Due to AC and DC Electromagnetic Fields

Halgamuge, Malka N.

97

Internal Displacement Monitoring Centre  

NSDL National Science Digital Library

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

98

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

99

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

PubMed Central

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

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

2003-01-01

100

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

101

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

102

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

NASA Astrophysics Data System (ADS)

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 ?peak2=?c2+?pd2/4.

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

2014-07-01

103

Displaced Supersymmetry  

E-print Network

The apparent absence of light superpartners at the LHC strongly constrains the viability of the MSSM as a solution to the hierarchy problem. These constraints can be significantly alleviated by R-parity violation (RPV). Bilinear R-parity violation, with the single operator L H_u, does not require any special flavor structure and can be naturally embedded in a GUT while avoiding constraints from proton decay (unlike baryon-number-violating RPV). The LSP in this scenario can be naturally long-lived, giving rise to displaced vertices. Many collider searches, particularly those selecting b-jets or leptons, are insensitive to events with such detector-scale displaced decays owing to cuts on track quality and impact parameter. We demonstrate that for decay lengths in the window ~1-1000 mm, constraints on superpartner masses can be as low as ~450 GeV for squarks and ~40 GeV for LSPs. In some parts of parameter space light LSPs can dominate the Higgs decay width, hiding the Higgs from existing searches. This framework motivates collider searches for detector-scale displaced vertices. LHCb may be ideally suited to trigger on such events, while ATLAS and CMS may need to trigger on missing energy in the event.

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

2012-04-26

104

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

105

RM due to magnetic fields in the cosmic web and SKA observations  

NASA Astrophysics Data System (ADS)

We estimated that rotation measure (RM) due to the intergalactic magnetic field (IGMF) in the cosmic web is ~ 1-10 rad m-2. The RMs could be tested with the Square Kilometer Array (SKA) and SKA pathfinders.

Akahori, Takuya; Ryu, Dongsu

2015-03-01

106

STUDY OF POSSIBLE USING THE POLYMER SOLUTIONS AS AGENTS OF OIL DISPLACEMENT IN THE FIELDS WITH ABNORMALLY LOW RESERVOIR TEMPERATURES  

Microsoft Academic Search

Rheological, structural and oil displacing properties of the solutions of polyacrylamide (PAA) and carboxymethylcellulose (CMC) are fully investigated in the conditions of abnormally low reservoir temperatures. Physico-chemical processes occurring at a contact of highly mineralized formation water with the polymer solutions of PAA and CMC, which are different in composition, in the pore space of the reservoir are studied. The

A. F. Fyodorova; E. Yu. Shitz; A. S. Portnyagin

107

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

108

Acceleration of electrons and solar flares due to quasi-static electric field  

Microsoft Academic Search

The storage of flare energy, efficient acceleration of electrons and the trigger of the flares are suggested to be attributed to a quasi-static electric field caused by a gas motion near the photosphere without satisfying the frozen condition. The primary cause of the onset of flares would be the acceleration of electrons due to the electric field above a critical

Tatsuo Takakura

1971-01-01

109

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

E-print Network

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

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

2009-07-13

110

Theory of short-scale field-aligned density striations due to ionospheric heating  

NASA Technical Reports Server (NTRS)

The theoretical saturation spectrum of parametrically excited Langmuir waves in a locally uniform ionosphere is shown by the present calculations to produce, by ohmic dissipation, short-scale field-aligned density striations. The spectrum of the calculated striations is not inconsistent with observations of field-aligned scatter of VHF and UHF waves in ionospheric modification experiments if local increases of the pump field due to focusing are invoked.

Lee, M.-C.; Fejer, J. A.

1978-01-01

111

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

112

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

113

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

114

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

115

Modeling Long-Term Soil Losses on Agricultural Fields Due to Ephemeral Gully Erosion  

Technology Transfer Automated Retrieval System (TEKTRAN)

It is now recognized worldwide that soil erosion on agricultural fields due to ephemeral gullies may be greater than those losses attributed to sheet and rill erosion processes. Yet it is not known whether the common practice of repairing or obliterating these gullies during annual tillage activitie...

116

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

E-print Network

PINEAL MELATONIN LEVEL DISRUPTION IN HUMANS DUE TO ELECTROMAGNETIC FIELDS AND ICNIRP LIMITS Malka N to power-frequency (50 or 60 Hz) EMFs is unavoidable. Melatonin is a natural hormone produced by pineal, as a consequence, may decrease the melatonin production. In this study, more than one hundred experimental data

Halgamuge, Malka N.

117

Forces due to fluctuations in the anisotropic phase-field model of solidification  

Microsoft Academic Search

Stochastic forces due to thermodynamic fluctuations are derived for the anisotropic phase-field model of solidification. The stochastic forces turn out to be anisotropic. The derivation utilizes the general principles of irreversible thermodynamics. One of the forces is the divergence of the stochastic heat flux derived by Landau and Lifshitz (Statistical Physics, Pergamon Press, Oxford, 1958). The other force is the

Stanislav G. Pavlik; Robert F. Sekerka

1999-01-01

118

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 April 2012 Available online 23 May 2012 Keywords: Acoustic radiation force Nonlinear acoustics Modulated-called acoustic radiation force) in homogeneous tissue-like solids generated by an elevated-intensity, focused

Guzina, Bojan

119

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

SciTech Connect

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

Chen Xu,Charles Reece,Michael Kelley

2012-07-01

120

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

121

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

SciTech Connect

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

Genenko, Yuri A., E-mail: genenko@mm.tu-darmstadt.de; Hirsch, Ofer [Technische Universität Darmstadt, Darmstadt (Germany); Erhart, Paul [Chalmers University of Technology, Gothenburg (Sweden)

2014-03-14

122

Field ion microscopy of cascades of atomic displacements in metals and alloys after various types of irradiation  

NASA Astrophysics Data System (ADS)

Experimental results on atomic-spatial investigation of radiative defect formation in surface layers of materials, initiated by neutron bombardment (of Pt, E > 0.1 MeV) and ion implantation (in Cu3Au: E = 40 keV, F = 1016 ion/m2, j = 10-3 A/cm2), are considered. Quantitative estimates are obtained for the size, shape, and volume fraction of cascades of atomic displacements formed under various types of irradiation in the surface layers of the materials. It is shown that the average size of radiation clusters after irradiation of platinum to a fast neutron fluence of 6.7 × 1022 m-2 ( E > 0.1 MeV) is about 3.8 nm. The experimentally established average size of a radiation cluster (disordered zone) in the alloy after ion bombardment is 4 × 4 × 1.5 nm.

Ivchenko, V. A.

2014-09-01

123

A new electrohydrodynamic flows due to field-induced conductivity gradient in dielectric liquids  

NASA Astrophysics Data System (ADS)

A dielectric liquid is often preferred as a host fluid of a colloidal system under an electric field, because one can utilize the full benefits of a strong electric field with little concern for occurrence of electrolysis. Hence, dielectric liquids have been employed in many practical applications such as electrorheological fluids, electrophoretic deposition, and electrophoretic display. Nonetheless, the dynamics of colloidal particles in dielectric liquids is poorly understood compared to that in aqueous solutions. In the present paper, we report a novel electrohydrodynamic (EHD) flow which occurs near the objects immersed in dielectric liquids containing small amounts of polar additives. We suggested that the EHD flow is generated due to a electrical conductivity gradient induced by a non-uniform electric-field. Analytical and numerical solutions are obtained and verified by comparision with experimental results. We discuss the effect of electric-field strength, particle size, and ac frequency on velocity and pattern of the EHD flow.

Park, Hyun Jin; Ryu, Jae Chun; Park, Jun Kwon; Kang, Kwan Hyoung

2008-11-01

124

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

125

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

126

Lateral displacement and rotational displacement sensor  

DOEpatents

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

Duden, Thomas

2014-04-22

127

CMB distortion anisotropies due to the decay of primordial magnetic fields  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

128

Frequency shifts in NIST Cs Primary Frequency Standards due To Transverse RF Field Gradients  

E-print Network

A single-particle Green's function (propagator) is introduced to study the detection of laser-cooled Cesium atoms in an atomic fountain due to RF ?field gradients in the Ramsey TE011 cavity. The detection results in a state-dependent loss of atoms at apertures in the physics package, resulting in a frequency bias. A model accounting only for motion in one dimension transverse to the symmetry axis of the fountain is discussed in detail and then generalized to two transverse dimensions. Results for fractional frequency shifts due to transverse field gradients are computed for NIST F-1 and F-2 Cesium fountains. The shifts are found to be negligible except in cases of higher RF power applied to the cavities.

Ashby, Neil; Heavner, Thomas; Jefferts, Steven

2014-01-01

129

Frequency shifts in NIST Cs primary frequency standards due to transverse rf field gradients  

NASA Astrophysics Data System (ADS)

A single-particle Green's function (propagator) is introduced to study the deflection of laser-cooled cesium atoms in an atomic fountain due to microwave magnetic field gradients in the Ramsey TE011 cavity. The deflection results in a state-dependent loss of atoms at apertures in the physics package, resulting in a frequency bias. A model accounting only for motion in one dimension transverse to the symmetry axis of the fountain is discussed in detail and then generalized to two transverse dimensions. Results for fractional frequency shifts due to transverse field gradients are computed for NIST-F1 and NIST-F2 cesium fountains. The shifts are found to be negligible except in cases of higher rf power applied to the cavities.

Ashby, Neil; Barlow, Stephan; Heavner, Thomas; Jefferts, Steven

2015-03-01

130

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

131

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

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

132

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

133

Holographic interferometry applied to characterize the near-field acoustic displacement patterns and dynamics of operating sonar arrays  

NASA Astrophysics Data System (ADS)

The dynamic acoustic information processed by a sonar array is of critical importance to target discrimination and recognition. A visualization of the true near-field acoustic energy distribution of an active sonar array would be of great value to understanding and characterizing the effects of structural defects in the array and its interface to the water medium. Knowledge of the projected near-field acoustic energy would also enhance the analysis of returned sonar signals for homing and target recognition. Holographic interferometry has presented itself as a viable and useful method for the realization of this type of information.

Fein, Howard

1995-07-01

134

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

NASA Technical Reports Server (NTRS)

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

Nedoluha, Gerald E.; Watson, William D.

1990-01-01

135

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

NASA Technical Reports Server (NTRS)

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

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

1974-01-01

136

Determination of the fracture parameters associated with mixed mode displacement fields and applications of high density geometric moire  

E-print Network

fracture behavior of a magnesium plate. Barker, Sanford and Chona' utilized the full- field nature of the moire method to determine the static opening mode stress intensity factor and higher order terms. Their research used the method of local collocation... of polymethylmethacrylate and Sanford' used geometric moire with 40 line/mm gratings to study the dynamic fracture of an aluminum alloy. Little work has been done using the moire method to determine both opening mode and shear mode stress intensity factors simultaneously...

Kmiec, Kenneth James

1994-01-01

137

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

E-print Network

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

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

2009-12-11

138

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

PubMed Central

Ferromagnetic nanostructures have been electrodeposited within the pores of porous silicon templates with average pore diameters between 25 and 60?nm. In this diameter regime, the pore formation in general is accompanied by dendritic growth resulting in rough pore walls, which involves metal deposits also offering a branched structure. These side branches influence the magnetic properties of the composite system not only due to modified and peculiar stray fields but also because of a reduced interpore spacing by the approaching of adjacent side pores. To improve the morphology of the porous silicon structures, a magnetic field up to 8?T has been applied during the formation process. The magnetic field etching results in smaller pore diameters with less dendritic side pores. Deposition of a ferromagnetic metal within these templates leads to less branched nanostructures and, thus, to an enhancement of the coercivity of the system and also to a significantly increased magnetic anisotropy. So magnetic field-assisted etching is an appropriate tool to improve the structure of the template concerning the decrease of the dendritic pore growth and to advance the magnetic properties of the composite material. PMID:22784792

2012-01-01

139

Retention perturbations due to particle-wall interactions in sedimentation field-flow fractionation  

SciTech Connect

In this paper theoretical and experimental results are obtained relating to the perturbation in retention in sedimentation field-flow fractionation due to particle-wall electrostatic and van der Waals interactions. These perturbations are described in relationship to standard retention theory, an ideal theory whose basic assumptions are summarized. A general equation in integral form is given for retention ratio R, and it is shown how the standard retention theory and sterically corrected retention theory are thereby obtained. Expressions are given for the potential energy of a colloidal particle near a wall resulting from electrostatic and van der Waals interactions; these interactions alter the concentration profile in the field-flow fractionation channel in a way that requires numerical integration to get R. By the use of estimated interaction parameters, R is plotted against field strength and ionic strength for several wall materials including stainless steel and fluorocarbon resin. Experimental results are reported for five different carrier solutions including distilled water. The agreement between theory and experimental results is very good considering the approximate nature of the parameters used. Both the calculations and the measurements show that the retentive perturbations are smaller for fluorocarbon resin than for stainless steel, Hastelloy C, and polyimide surfaces. An intermediate ionic strength also appears to be optimal. A new separation technique based on the combination of field-flow fractionation and potential barrier chromatography is suggested, and its possible advantages are discussed.

Hansen, M.E.; Giddings, J.C. (Univ. of Utah, Salt Lake City (USA))

1989-04-15

140

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

141

Computer code in support of the manuscript "Phase field model for coupled displacive and diffusive microstructural processes under thermal loading"  

E-print Network

["form_compiler"]["optimize"] = True # Use PETSc as linear algebra backend parameters["linear_algebra_backend"] = "PETSc" def update(U, U0, v0, a0, beta, gamma, dt): """Update fields at the end of each time step.""" # Get sub-functions (deep copy) u, u0 = U.split(True)[0], U0.split... ): assemble(self.L, tensor=b, form_compiler_parameters=self.ffc_opt) for bc in bcs: bc.apply(b, x) def J(self, A, x): if self.newton_solver.iteration() > 0: self.newton_solver.linear_solver().parameters["preconditioner"]["reuse"] = True assemble(self.a, tensor...

Wells, G N; Maraldi, Mirko

2011-01-01

142

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

143

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

Microsoft Academic Search

We have previously shown that the choice of J(t,L)=0 boundary condition in the model of copper ion drift causes an internal field enhancement at the cathode due to the accumulation of copper ions. The ultimate breakdown of the dielectric occurs due to a combination of the field increase exceeding the intrinsic breakdown strength as well as the intrinsic bond breakage

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

2007-01-01

144

Stochastic Force Due to a Quantum Scalar Field in Minkowski Spacetime  

E-print Network

A method is presented for computing approximate expressions for the stochastic force term $\\xi_{ab}$ which appears in the Einstein-Langevin equation of stochastic gravity. Within this framework, $\\xi_{ab}$ is a stochastic tensor field whose probability distribution mimics the probability distribution of the fluctuations of the quantum stress tensor operator; it is defined to be a random tensor field of zero mean whose correlation function is given by the expectation value of the symmetrized two point function of the stress energy fluctuation operator, called the noise kernel. Approximate expressions are obtained by means of a truncated Karhunen-Loeve transform defined on a random lattice of spacetime points. Due to the singular nature of the noise kernel, a coarse graining procedure is used to regulate divergences; as a result, the expressions obtained for $\\xi_{ab}$ approximate values which might be seen by a probe measuring fluctuations in the stress energy using a sampling profile of finite width. Two realizations of $\\xi_{ab}$ in Minkowski spacetime for the conformally invariant quantum scalar field in the Minkowski vacuum state are presented.

Jason D. Bates

2013-03-07

145

Surface displacement studies using differential SAR interferometry: an overview  

NASA Astrophysics Data System (ADS)

The differential SAR interferometry (DInSAR) has been increasing used to monitor ground surface displacements, which may be caused by various natural disasters such as earthquakes, landslides, mining activities, avalanches etc. Conventionally, these displacements were being estimated through field measurements, which are time consuming, hazardous and with data collected over few point locations. Since all the development and rehabilitation works after a natural disaster strikes is carried out on regional basis, any information at spatial level is advantageous in planning, management and monitoring activities. In recent years, the application of Differential SAR interferometry is gaining momentum to estimate the surface displacements at millimeter level accuracy. The displacement maps produced via this technique provide information at spatial level in the region thereby assisting in judicious developmental and planning works in an efficient and cost-effective manner. The aim of this paper is provide an overview of the use of Differential SAR Interferometry (DinSAR) technology for the study of surface displacements. As a case study, land subsidence occurred due to coal mining in Jharia coal fields, Jharkhand, have been estimated through this technique. All the procedural steps in implementing the approach based on DinSAR have been explained in a simplified manner.

Gupta, Sonal; Sajith V., K.; Arora, Manoj K.; Sharma, Mukut L.

2006-12-01

146

Measuring tidal displacement using GPS  

NASA Astrophysics Data System (ADS)

GPS is making possible high-precision, high-resolution measurements of tidal displacement that could not be achieved with other methods. Earth's surface deforms due to both body tides—the deformation of the solid Earth due to the pull of the Sun and the Moon—and ocean tides—the redistribution of water mass loading over Earth's surface. Body tides and ocean tides both have components that vary on semidiurnal, diurnal, and longer periods.

Balcerak, Ernie

2013-06-01

147

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

Microsoft Academic Search

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

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

1978-01-01

148

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

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

2014-01-01

149

Field location & marking of no-passing zones due to vertical alignments using the global positioning system  

E-print Network

FIELD LOCATION & MARKING OF NO-PASSING ZONES DUE TO VERTICAL ALIGNMENTS USING THE GLOBAL POSITIONING SYSTEM A Thesis by CAMERON LEE WILLIAMS Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE May 2008 Major Subject: Civil Engineering FIELD LOCATION & MARKING OF NO-PASSING ZONES DUE TO VERTICAL ALIGNMENTS USING THE GLOBAL POSITIONING SYSTEM A Thesis by CAMERON LEE WILLIAMS...

Williams, Cameron Lee

2008-10-10

150

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

151

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

NASA Astrophysics Data System (ADS)

The purpose of the present study is to investigate the uncertainties in simulating secondary organic aerosol (SOA) in Mexico City metropolitan area (MCMA) due to meteorological initial uncertainties using the WRF-CHEM model through ensemble simulations. The simulated periods (24 and 29 March 2006) represent two typical meteorological episodes ("Convection-South" and "Convection-North", respectively) in the Mexico City basin during the MILAGRO-2006 field campaign. The organic aerosols are simulated using a non-traditional SOA model including the volatility basis-set modeling method and the contributions from glyoxal and methylglyoxal. Model results demonstrate that uncertainties in meteorological initial conditions have significant impacts on SOA simulations, including the peak time concentrations, the horizontal distributions, and the temporal variations. The ensemble spread of the simulated peak SOA at T0 can reach up to 4.0 µg m-3 during the daytime, which is around 35% of the ensemble mean. Both the basin wide wind speed and the convergence area affect the magnitude and the location of the simulated SOA concentrations inside the Mexico City basin. The wind speed, especially during the previous midnight and the following early morning, influences the magnitude of the peak SOA concentration through ventilation. The surface horizontal convergence zone generally determines the area with high SOA concentrations. The magnitude of the ensemble spreads may vary with different meteorological episodes but has same significance compared to the ensemble mean.

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

2012-07-01

152

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

153

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

154

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

155

Entropy Analysis Due to Temperature and Stress Fields in the Solid Irradiated by a Time Exponentially Varying Laser Pulse  

Microsoft Academic Search

Laser heating of a solid surface results in a temperature rise and thermal stress development in the region irradiated by a laser beam. The thermodynamic irreversibility associated with the temperature and stress fields can be quantified by entropy analysis. Consequently, in the present study, the closed form solutions for temperature and stress fields due to time exponentially varying laser pulse

Bekir S. Yilbas

2005-01-01

156

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

Microsoft Academic Search

In the presence of alternating-sinusoidal or rotating magnetic fields, magnetic nanoparticles will act to realign their magnetic moment with the applied magnetic field. The realignment is characterized by the nanoparticle's time constant, ?. As the magnetic field frequency is increased, the nanoparticle's magnetic moment lags the applied magnetic field at a constant angle for a given frequency, ?, in rad\\/s.

P. Cantillon-Murphy; L. L. Wald; E. Adalsteinsson; M. Zahn

2010-01-01

157

High Displacement Actuator (HDA)  

NASA Technical Reports Server (NTRS)

Positioned beneath a fiber optic displacement sensor is the new High Displacement Actuator (HDA) developed by scientists at NASA Langley Research Center. The high displacement actuator significantly improves the state-of-the-art piezoelectric technology and provides inordinately large mechanical displacements. The HDA is also applicable to high performance sensor applications such as microphones, non-destructive testing, and vibration sensing. Test results on the high displacement actuators show displacements 50 times greater than device thickness and several orders of magnitude increase over state-of-the-art devices. The actuators can be used from DC to frequencies in excess of a megahertz and with displacement loads exceeding 10 Kg (25 lbs). The actuator can also produce displacements comparable to state-of-the-art devices with an order reduction in operating voltage. The high displacement actuators are reliable. They have been laboratory tested to beyond 400 million cycles without failure. The highly efficient electrically- insulated actuator can be operated in a vacuum, in liquids, and in the upper atmosphere. The HDA is versatile and rugged allowing for use in harsh environments for hundreds of commercial applications. In many device applications the high displacement actuator wafer itself can serve the function of several components, e.g. in simple pumps it take the place of piston, piston-rod and crank. The HDA is a packaged flexible laminate of pre-stressed polymeric materials and a piezoelectric ceramic that form a robust, low cost, user friendly device.

1994-01-01

158

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

PubMed Central

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

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

2008-01-01

159

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

160

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

161

Domain wall displacement by current pulses injection in submicrometer Permalloy square ring structures  

E-print Network

be reversibly and controllably displaced by current pulses of different polarity. Their observations can of polarized current pulses rather than by using a magnetic field.3 The current induced DW motion is due- tion reversal in Permalloy Py square rings with a narrow slit at one of the corners and we observed

Metlushko, Vitali

162

Tsunami generation by horizontal displacement of ocean bottom  

Microsoft Academic Search

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

Yuichiro Tanioka; Kenji Satake

1996-01-01

163

Primary Beam Steering Due to Field Leakage from Superconducting SHMS Magnets  

E-print Network

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

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

2014-08-26

164

Primary beam steering due to field leakage from superconducting SHMS magnets  

DOE PAGESBeta

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

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

2014-11-01

165

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

166

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

NASA Astrophysics Data System (ADS)

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

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

2008-04-01

167

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

NASA Astrophysics Data System (ADS)

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

Cantillon-Murphy, P.; Wald, L. L.; Adalsteinsson, E.; Zahn, M.

2010-03-01

168

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

PubMed

In the presence of alternating-sinusoidal or rotating magnetic fields, magnetic nanoparticles will act to realign their magnetic moment with the applied magnetic field. The realignment is characterized by the nanoparticle's time constant, ?. As the magnetic field frequency is increased, the nanoparticle's magnetic moment lags the applied magnetic field at a constant angle for a given frequency, ?, in rad/s. Associated with this misalignment is a power dissipation that increases the bulk magnetic fluid's temperature which has been utilized as a method of magnetic nanoparticle hyperthermia, particularly suited for cancer in low-perfusion tissue (e.g., breast) where temperature increases of between 4°C and 7°C above the ambient in vivo temperature cause tumor hyperthermia. This work examines the rise in the magnetic fluid's temperature in the MRI environment which is characterized by a large DC field, B(0). Theoretical analysis and simulation is used to predict the effect of both alternating-sinusoidal and rotating magnetic fields transverse to B(0). Results are presented for the expected temperature increase in small tumors (~1 cm radius) over an appropriate range of magnetic fluid concentrations (0.002 to 0.01 solid volume fraction) and nanoparticle radii (1 to 10 nm). The results indicate that significant heating can take place, even in low-field MRI systems where magnetic fluid saturation is not significant, with careful selection of the rotating or sinusoidal field parameters (field frequency and amplitude). The work indicates that it may be feasible to combine low-field MRI with a magnetic hyperthermia system using superparamagnetic iron oxide nanoparticles. PMID:20161608

Cantillon-Murphy, P; Wald, L L; Adalsteinsson, E; Zahn, M

2010-03-01

169

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

E-print Network

1.1. Problem Statement ......................................................................... 3 1.2. Research Objectives........................................................................ 5 1.3. Layout of Dissertation... .................................................................... 6 II FIELD INSTRUMENTS AND DATA ANALYSIS.................................. 8 2.1. General............................................................................................ 8 2.2. Introduction of the WIM System...

Oh, Jeong-Ho

2004-11-15

170

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

171

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

172

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

173

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

PubMed Central

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

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

2013-01-01

174

Giant cross-magnetic-field steps due to binary collisions between pair particles  

NASA Astrophysics Data System (ADS)

Giant cross-magnetic-field steps can occur as a result of positron-electron collisions. Within a constant magnetic field (e.g., 1 T), a collision between a positron and an electron can result in a correlated drift across the magnetic field for a continuous range of impact parameters. Within this range, drift distances orders of magnitude larger than that associated with like-charge collisions were observed by computer simulation. Outside of this range, the collisional behavior is similar to that for collisions between particles with the same charge. A theoretical analysis of the phenomenon using center-of-mass and relative coordinates provides insights regarding the occurrence of giant cross-magnetic-field steps.

Aguirre, F. F.; Ordonez, C. A.

2015-03-01

175

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

Microsoft Academic Search

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

Vladimir Skalozub; Vadim Demchik

1999-01-01

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

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

SciTech Connect

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

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

2014-02-15

178

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

PubMed

A new magnetic configuration is proposed for the suppression of co-extracted electrons in a negative-ion accelerator. This configuration is produced by an arrangement of permanent magnets embedded in one accelerator grid and creates an asymmetric local magnetic field on the upstream and downstream sides of this grid. Thanks to the "concentration" of the magnetic field on the upstream side of the grid, the resulting deflection of the ions due to magnetic field can be "intrinsically" cancelled by calibrating the configuration of permanent magnets. At the same time, the suppression of co-extracted electrons can be improved. PMID:24593594

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

2014-02-01

179

Variance and Covariance of Accumulated Displacement Estimates  

PubMed Central

Tracking large deformations in tissue using ultrasound can enable the reconstruction of nonlinear elastic parameters, but poses a challenge to displacement estimation algorithms. Such large deformations have to be broken up into steps, each of which contributes an estimation error to the final accumulated displacement map. The work reported here measured the error variance for single-step and accumulated displacement estimates using one-dimensional numerical simulations of ultrasound echo signals, subjected to tissue strain and electronic noise. The covariance between accumulation steps was also computed. These simulations show that errors due to electronic noise are negatively correlated between steps, and therefore accumulate slowly, while errors due to tissue deformation are positively correlated and accumulate quickly. For reasonably low electronic noise levels, the error variance in the accumulated displacement estimates is remarkably constant as a function of step size, but increases with the length of the tracking kernel. PMID:23493610

Bayer, Matthew; Hall, Timothy J.

2013-01-01

180

Streaming and removal forces due to second-order sound field during megasonic cleaning of silicon wafers  

E-print Network

Streaming and removal forces due to second-order sound field during megasonic cleaning of silicon September 2000 We calculate the second-order streaming force in a fluid in the vicinity of the solid. It is composed of one silicon slab wafer immersed in water. The components of the streaming force parallel

Deymier, Pierre

181

An attempt to detect preseismic displacement field of the 2008 Iwate-Miyagi Nairiku Earthquake using InSAR small baseline time-series analysis  

NASA Astrophysics Data System (ADS)

The Iwate-Miyagi Nairiku Earthquake (Mj 7.2) occurred at 8:43, JST on June 14 2008, in the northeastern Honshu, Japan. This earthquake caused significant amount of ground displacements with more than 2m of uplift and 1.5m of horizontal displacement at the Kurikoma2 GPS station of GEONET network operated by the Geographical Survey Institute (GSI).In a few years prior to the earthquake, the Kurikoma2 station displaced about 1cm and 2cm to the southeast and upward directions, respectively, according to GSI's analysis. We perform an InSAR small baseline (SB) time-series analysis in order to investigate this slow non-steady movement in detail. We applied an InSAR SB time-series analysis based on Schmidt and Bürgmann (2003; JGR, vol. 108). This method can mitigate atmospheric and orbital artifacts, which constitute dominant sources of error, by assuming a temporal smoothness of displacements. We used seven SAR data acquired by PALSAR onboard the ALOS satellite. We selected three interferograms and stacked them after converting to velocity. For the small baseline processing, we selected and processed 17 small-baseline pairs with definition of small baseline to be less than 2000 m for the perpendicular baseline and 1000 days for the temporal baseline. The interferograms were unwrapped and solved for the temporal evolution of displacements with the time steps defined by the SAR acquisition dates. Preliminary results indicate that atmospheric and orbital effects are still higher than the expected amplitude of preseismic displacements. Though the noise may further be mitigated by careful tuning of analysis parameters, our preliminary results suggest that we probably need more realistic atmospheric correction using independent data such as GPS and meteorological data. Acknowledgment PALSAR data are shared by PIXEL (PALSAR Interferometry Consortium to Study our Evolving Land surface), and provided from JAXA under a contract with ERI, Univ. of Tokyo. The ownership of PALSAR data belongs to METI (Ministry of Economy, Trade and Industry) and JAXA.

Arimoto, M.; Fukushima, Y.; Hirahara, K.; Hashimoto, M.

2008-12-01

182

Convective transport due to poloidal electric fields during electron cyclotron heating in IMS  

Microsoft Academic Search

Steady state hollow density profiles, observed during electron cyclotron resonant heating in the Interchangeable Module Stellarator (IMS), are shown to be consistent with a transport model that includes convection in the particle balance equation. The factor of two difference in the confinement time between a hollow profile and a fairly flat profile is due to particle convection and is in

J. N. Talmadge; C. A. Storlie; D. T. Anderson; F. S. B. Anderson; R. P. Doerner; P. H. Probert; J. L. Shohet; P. K. Trost

1989-01-01

183

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

SciTech Connect

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

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

1992-08-01

184

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

185

Neoclassical Drift of Circulating Orbits Due toToroidal Electric Field in Tokamaks  

SciTech Connect

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

Hong, Qin, Xiaoyin Guan and Nathaniel J. Fisch

2011-07-19

186

Kinematics Problem: Displacement  

NSDL National Science Digital Library

A bowling ball is lifted from rest onto a shelf by an external agent (position is in meters and time is in seconds). Rank the paths by the displacement of the bowling ball during the animations (greatest first).

Wolfgang Christian

187

Fluorescence sensing systems: In vivo detection of biophysical variations in field corn due to nitrogen supply  

Microsoft Academic Search

Leaf and canopy fluorescence properties of field corn (Zea mays L.) grown under varying levels of nitrogen (N) fertilization were characterized to provide an improved N sensing capability which may assist growers in site-specific N management decisions. In vivo fluorescence emissions can occur in the wavelength region from 300 to 800 nm and are dependent on the wavelength of illumination.

Lawrence A Corp; James E McMurtrey; Elizabeth M Middleton; Charles L Mulchi; Emmett W Chappelle; Craig S. T Daughtry

2003-01-01

188

Possibility of critical field enhancement due to field penetration in high-Tc sponges and thin films  

Microsoft Academic Search

Magnetic susceptibility measurements of a sample of sintered high-Tc ceramic superconductor of nominal composition Y1Ba2Cu3O(7-y) were conducted as a function of temperature from liquid-He temperatures to Tc. The fitted form of the susceptibility temperature dependence yielded a sample-particle size that was only a few times larger than the field-penetration depth. The particle size was much less than the grain size

E. W. Collings; A. J. Markoworth; K. R. Marken Jr.

1989-01-01

189

Inversion of displacement operators  

Microsoft Academic Search

Abstract. We recall briefly the displacement rankapproach to the computations,with struc- tured matrices, which we trace backto the seminal paper by Kailath, Kung, and Morf [ J. Math. Anal. Appl., 68 (1979), pp. 395–407]. The concluding stage of the computations is the recovery of the output from its compressed,representation via the associated displacement operator L. The recovery amounts to the

V. Y. Pan; X. Wang

2002-01-01

190

The Wrapping of Magnetic Field Lines due to Frame Dragging around a Neutron Star  

NASA Astrophysics Data System (ADS)

In this short paper we report on the results found in modeling of a relativistically rotating neutron star. The star is modeled as a rotating magnetic dipole in a static spherical mass. It is found that the radiation for these relativistically rotating stars is severely reduced due to general relativistic effects. It is also found that in the limit, as the mass of the neutron star approaches 3.2M?, no radiation is emitted; this essentially signifies a black hole.

Herbst, Rhameez S.; Qadir, Asghar; Momoniat, Ebrahim

2015-01-01

191

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

192

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

PubMed

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

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

2010-08-18

193

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

NASA Astrophysics Data System (ADS)

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

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

2007-08-01

194

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

195

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

SciTech Connect

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

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

2013-09-01

196

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

197

Measurements of electric and magnetic fields due to the operation of indoor power distribution substations  

Microsoft Academic Search

In this paper, the electric and magnetic fields with a frequency of 50 Hz, caused by the operation of indoor power distribution substations of 20\\/0.4 kV, are examined. First, the results of previous relevant research studies as well as the reference levels for safe general public and occupational exposure given in the guidelines of the International Commission on Non-Ionizing Radiation

Anastasia S. Safigianni; Christina G. Tsompanidou

2005-01-01

198

Numerical modeling of self-potential anomalies due to leaky dams: Model and field examples  

Microsoft Academic Search

Substantial self-potential anomalies are known to be associated with zones of discharge in leaky dams. The mechanism for generating these SP anomalies. however, is not well understood. In this paper we apply a two-dimensional computer-code to calculate self-potential anomalies for a model of a leaky dam and then apply the code to some field data for a dam site in

M. J. Wilt; R. F. Corwin

1989-01-01

199

Numerical modeling of self-potential anomalies due to leaky dams: Model and field examples  

Microsoft Academic Search

Substantial self-potential anomalies are known to be associated with zones of discharge in leaky dams. The mechanism for generating these SP anomalies. however, is not well understood. In this paper we apply a two-dimensional computer-code to calculate self-potential anomalies for a model of a leaky dam and then apply the code to some field data for a dam site in

M. Wilt; R. Corwin

200

Elastic fields due to centers of dilatation and thermal inhomogeneities in plane-layered solids  

NASA Astrophysics Data System (ADS)

A N IMAGE METHOD for obtaining the solution for a center of dilatation in a three-layer elastic solid with planar interfaces is presented. The three-layered elastic solid consists of an elastic slab sandwiched between two semi-infinite elastic solids. The three elastic solids are perfectly bonded together at the two planar interfaces. The solution is given in terms of Galerkin vectors which are in terms of an infinite series of the Newtonian potential function of a mass point at the center of dilatation, its mirror images and their derivatives. As an application, the solution for the center of dilatation is used to obtain the elastic solution due to thermal inhomogeneities. The thermoelastic solution is obtained by a method which is based on the integration of properly weighted centers of dilatation over the volume occupied by the inhomogeneity. The potential functions for the problem solved are the harmonic potential functions of attracting matter filling the volume of the thermal inhomogeneity and its mirror images. The solution for the thermal elastic stresses due to an expanding (or contracting) thermal inhomogeneity (inclusion) of any shape embedded in one of the solids is given as an example. Numerical results for a spherical inclusion with pure dilatation eigenstrain are also presented and discussed.

Yu, H. Y.; Sanday, S. C.

1993-02-01

201

Displacement and Velocity of the Coronary Arteries: Cardiac and Respiratory Motion  

PubMed Central

This paper presents measurements of three-dimensional (3-D) displacements and velocities of the coronary arteries due to the myocardial beating motion and due to breathing. Data were acquired by reconstructing the coronary arteries and their motion from biplane angiograms in 10 patients. A parametric motion model was used to separate the cardiac and breathing motion fields. The arteries move consistently toward the left, inferior, and anterior during a cardiac contraction. The displacement and velocity of the right coronary artery during a cardiac contraction was larger than measured for the left coronary tree. Cardiac motion dominates the respiratory motion of the coronary arteries during spontaneous breathing. On inspiration, the arteries move caudally, but the motion in the left-right and anterior-posterior axes was variable. Spatial variation in respiratory displacement and velocity of the coronary arteries indicates that the breathing motion of the heart is more complex than a 3-D translation. PMID:16524092

Shechter, Guy; Resar, Jon R.; McVeigh, Elliot R.

2007-01-01

202

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

203

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

SciTech Connect

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

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

2010-11-01

204

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

205

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

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

206

The uncertainty of the Uranian radio source location due to the nonuniqueness of the planetary magnetic field model  

NASA Astrophysics Data System (ADS)

Since the Voyager 2 encounter in early 1986, several investigators have attempted to localize the source regions of the smooth high-frequency radio emission which was observed by the planetary radio astronomy experiment at the nightside of Uranus. The various studies [most of them are based on the offset tilted dipole (OTD) model of the Uranian magnetic field] yielded significantly different source locations around the southern magnetic pole of Uranus. This may be a consequence of the individual a priori assumptions of the source model. However, the simplicity of the OTD model (Ness et al., 1986) also cannot adequately represent the complexity of the magnetic field at the radio source locations near the planet. The aim of this study is twofold. (1) We reanalyze the various source locations given in the literature (most of them are based on the OTD model) in the frame of the Q3 magnetic field model (Connerney et al. , 1987). Our analysis moves some of the previously determined source locations from open toward closed field lines; however, the uncertainty due to the nonuniqueness of the Q3 model remains too large to exclude the possibility that open field lines are the source of smooth Uranian kilometric radiation. (2) We calculate the uncertainty of the radio source locations imposed by the nonuniqueness of the Q3 and OTD magnetic field models. We construct solutions by using generalized inversion techniques (Connerney, 1981) to obtain estimates of those magnetic field parameters (spherical harmonic coefficients up to degree and order 6) that are constrained by the magnetometer observations. The nonuniqueness of the resulting magnetic field models translates into an uncertainty about the radio source locations of some 20° in Uranocentric coordinates at altitudes of about 1.5 Uranian radii (RU). The present results are important for radio source locations at all the outer planets whose magnetic field geometries are represented by nonunique magnetic field models.

Ladreiter, H. P.; Macher, W.; Rabl, G. K. F.; Rucker, H. O.

1993-10-01

207

Ultra-Sensitive Magnetoresistive Displacement Sensing Device  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

208

Parametric Study of Transient Electromagnetic Fields Due to Overhead Transmission Lines and Buried Cables in the Vicinity of Lossy Ground  

Microsoft Academic Search

In this paper, the problem of calculating transient electromagnetic fields due to frequency-dependent multicon- ductor overhead transmission lines above lossy ground and underground cables buried in lossy soil is studied by decomposing the transmission line into a number of small segments. A modified finite-difference time-domain technique is applied to find the current passing through each segment of the excited transmis-

Pooya Taheri; Behzad Kordi; Aniruddha M. Gole

2011-01-01

209

Giant magnetic field-induced strain due to rearrangement of variants in an ordered Fe 3Pt  

Microsoft Academic Search

Magnetic field-induced strain due to rearrangement of martensite variants in a ferromagnetic Fe3Pt alloy single crystal with degree of order of about 0.8 has been investigated. The alloy exhibits a martensitic transformation from an ordered L12-type structure to a tetragonal one at 85 K. The tetragonality of the martensite decreases as temperature decreases, and is about 0.945 at 14 K.

Tatsuaki Sakamoto; Takashi Fukuda; Tomoyuki Kakeshita; Tetsuya Takeuchi; Kohji Kishio

2004-01-01

210

Oscillation of electron mobility in parabolic double quantum well structure due to applied electric field  

NASA Astrophysics Data System (ADS)

We show that oscillation of low temperature electron mobility ? can be obtained by applying an electric field F along the growth direction of the asymmetrically barrier delta doped AlxGa1-xAs parabolic double quantum well structure. The drastic changes in the subband Fermi energies and distributions of subband wave functions as a function of F yield nonmonotonic intra- and intersubband scattering rate matrix elements mediated by intersubband effects. The oscillatory enhancement of ?, which is attributed to the subband mobilities governed by the ionized impurity scattering, magnifies with increase in well width and decrease in height of the parabolic structure potential. The results can be utilized for nanoscale low temperature device applications.

Sahoo, Narayan; Sahu, Trinath

2014-12-01

211

Elastic reciprocity and symmetry constraints on the stress field due to a surface-parallel distribution of  

E-print Network

, a relationship is shown to exist between the changes in- duced by dislocations of orthogonal Burgers vectors, for the same magnitude of Burgers vector (displacement discontinuity) in both 1a and 1b. The original solution

212

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

213

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

214

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

215

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

216

Experimental investigation of heating phenomena in linac mechanical interfaces due to RF field penetration  

SciTech Connect

In a high duty-factor, high-current, drift-tube linear accelerator, a critical interface exists between the drift-tube stem and the tank wall. This interface must provide vacuum integrity and RF continuity, while simultaneously allowing alignment flexibility. Because of past difficulties with RF heating of vacuum bellows and RF joints encountered by others, a paucity of available information, and the high reliability requirement for the Fusion Materials Irradiation Test (FMIT) accelerator, a program was initiated to study the problem. Because RF heating is the common failure mode, an attempt was made to find a correlation between the drift-tube-stem/linac-tank interface geometry and RF field penetration from the tank into the interface region. Experiments were performed at 80 MHz on an RF structure designed to simulate the conditions to which a drift-tube stem and vacuum bellows are exposed in a drift-tube linac. Additional testing was performed on a 367-MHz model of the FMIT prototype drift-tube linac. Experimental results, and a method to predict excessive RF heating, is presented. An experimentally tested solution to the problem is discussed.

Fazio, M.V.; Reid, D.W.; Potter, J.M.

1981-01-01

217

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

218

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

219

Enhanced hole carrier transport due to increased intermolecular contacts in small molecule based field effect transistors.  

PubMed

Small molecules and oligomers can be synthesized with very high purity and precise molecular weights, but they often do not form uniform thin films while processed from solution. Decreased intermolecular contacts between the small molecules are another disadvantage. To increase the intermolecular contacts in small molecules, we have chosen i-indigo, as one of the conjugated molecular units. The electron poor i-indigo has been connected with electron rich triphenylamine to synthesize a donor-acceptor-donor type small molecule. The propeller shaped triphenylamine helps to increase the solubility of the small molecule as well as isotropic charge transport. The intermolecular spacing between the molecules has been found to be low and did not vary as a function of thermal annealing. This implies that the intermolecular contacts between the small molecules are enhanced, and they do not vary as a function of thermal annealing. Organic field effect transistors (OFET) fabricated using a small molecule exhibited a hole carrier mobility (?) of 0.3 cm(2)/(V s) before thermal annealing. A marginal increase in ? was observed upon thermal annealing at 150 °C, which has been attributed to changes in thin film morphology. The morphology of the thin films plays an important role in charge transport in addition to the intermolecular spacing that can be modulated with a judicious choice of the conjugated molecular unit. PMID:23808768

Dharmapurikar, Satej S; Arulkashmir, Arulraj; Das, Chayanika; Muddellu, Pooja; Krishnamoorthy, Kothandam

2013-08-14

220

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

221

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

PubMed

During their travel inside a traveling wave ion mobility cell (TW IMS), ions are susceptible to heating because of the presence of high intensity electric fields. Here, we report effective temperatures Teff,vib obtained at the injection and inside the mobility cell of a SYNAPT G2 HDMS spectrometer for different probe ions: benzylpyridinium ions and leucine enkephalin. Using standard parameter sets, we obtained a temperature of ~800 K at injection and 728?±?2 K into the IMS cell for p-methoxybenzylpyridinium. We found that Teff,vib inside the cell was dependent on the separation parameters and on the nature of the analyte. While the mean energy of the Boltzmann distributions increases with ion size, the corresponding temperature decreases because of increasing numbers of vibrational normal modes. We also investigated conformational rearrangements of 7+ ions of cytochrome c and reveal isomerization of the most compact structure, therefore highlighting the effects of weak heating on the gas-phase structure of biologically relevant ions. PMID:24845353

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

2014-08-01

222

PDT - PARTICLE DISPLACEMENT TRACKING SOFTWARE  

NASA Technical Reports Server (NTRS)

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

Wernet, M. P.

1994-01-01

223

Micrograting Displacement Sensor with Integrated Electrostatic Actuation  

NASA Astrophysics Data System (ADS)

A high-resolution micro-grating displacement sensor with diffraction-based and integrated electrostatic actuation is proposed and experimentally demonstrated. The Al reflecting membrane is fabricated at the bottom of a silicon moving part and the Au micro-gratings are patterned on a transparent substrate. This structure forms a phase sensitive diffraction grating, providing the displacement sensitivity of the micro-grating interferometer. It shows sensitivity adjustment and self-calibration capabilities with electrostatic actuation. Additional system components include a coherent light source, photodiodes, and required electronics. Experimental results show that the displacement sensor has a sensitivity of about 1.8 mV/nm and a resolution of less than 1 nm in the linear region. This displacement sensor is very promising in the fields requiring high sensitivity, broad dynamic range, and immunity to electromagnetic interference.

Yao, Bao-Yin; Feng, Li-Shuang; Wang, Xiao; Liu, Wei-Fang; Liu, Mei-Hua

2014-07-01

224

Dynamic displacement measurement accuracy of GPS for monitoring large civil engineering structures  

NASA Astrophysics Data System (ADS)

Accelerometer and displacement transducer are two common sensors used for structural displacement measurement. Due to their incapability of measuring static deflection of a structure, Global Positioning System (GPS) is developed as a novel sensor for measuring and monitoring both static and dynamic displacement responses of large civil engineering structures under gust winds. However, the accuracy of dynamic displacement measurement with GPS at the sub-centimeter to millimeter level depends on many factors such as required data update rate, satellite coverage, atmospheric effect, multi-path effect, and GPS data processing methods. Therefore, this paper focuses on the assessment of dynamic displacement measurement accuracy of GPS in two orthogonal directions. A 2-D motion simulation table is first developed as a test bed simulating various types of two perpendicular translational motions of tall buildings. The 2-D motion simulation table was then used to assess the performance of GPS through a series of field measurements in an open area. A band-pass filtering scheme is finally designed and applied to the table motion data recorded by the GPS. The comparison of the table motion recorded by the GPS with the original motion generated by the table shows that the GPS can measure sinusoidal or circular dynamic displacements accurately within certain amplitude and frequency ranges. The comparative results also demonstrate that the GPS can trace wind-induced dynamic responses of tall buildings satisfactorily.

Chan, W. S.; Xu, Y. L.; Ding, X. L.; Xiong, Y. L.; Dai, W. J.

2005-05-01

225

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

SciTech Connect

Permeability contrasts exist in multilayer geological formations under consideration for carbon sequestration. To improve our understanding of heterogeneous pore-scale displacements, liquid CO2 (LCO2) - water displacement was evaluated in a pore network micromodel with two distinct permeability zones. Due to the low viscosity ratio (logM = -1.1), unstable displacement occurred at all injection rates over two orders of magnitude. LCO2 displaced water only in the high permeability zone at low injection rates with the mechanism shifting from capillary fingering to viscous fingering with increasing flow rate. At high injection rates, LCO2 displaced water in the low permeability zone with capillary fingering as the dominant mechanism. LCO2 saturation (SLCO2) as a function of injection rate was quantified using fluorescent microscopy. In all experiments, more than 50% of LCO2 resided in the active flowpaths, and this fraction increased as displacement transitioned from capillary to viscous fingering. A continuum-scale two-phase flow model with independently determined fluid and hydraulic parameters was used to predict SLCO2 in the dual-permeability field. Agreement with the micromodel experiments was obtained for low injection rates. However, the numerical model does not account for the unstable viscous fingering processes observed experimentally at higher rates and hence overestimated SLCO2.

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

2011-09-01

226

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

227

Observation of displacement momentum in normal and chiral dielectrics.  

PubMed

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

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

2013-05-10

228

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

229

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

230

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

Microsoft Academic Search

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

Y. F. Dong; H. C. Gea

1998-01-01

231

Spatiotemporal Splitting of Global Eigenmodes due to Cross-Field Coupling via Vortex Dynamics in Drift Wave Turbulence  

NASA Astrophysics Data System (ADS)

Spatiotemporal splitting events of drift wave (DW) eigenmodes due to nonlinear coupling are investigated in a cylindrical helicon plasma device. DW eigenmodes in the radial-azimuthal cross section have been experimentally observed to split at radial locations and recombine into the global eigenmode with a time shorter than the typical DW period (t ?fDW-1 ). The number of splits correlates with the increase of turbulence. The observed dynamics can be theoretically reproduced by a Kuramoto-type model of a network of radially coupled azimuthal eigenmodes. Coupling by E ×B —vortex convection cell dynamics and ion gyro radii motion leads to cross-field synchronization and occasional mode splitting events.

Brandt, C.; Thakur, S. C.; Light, A. D.; Negrete, J.; Tynan, G. R.

2014-12-01

232

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

233

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

234

Formulas Pertinent to the Calculation of Flow-Field Effects at Supersonic Speeds Due to Wing Thickness  

NASA Technical Reports Server (NTRS)

Expressions based on linearized supersonic-flow theory are derived for the perturbation velocity potential in space due to wing thickness for rectangular wings with biconvex airfoil sections and for arrow, delta, and quadrilateral wings with wedge-type airfoil sections. The complete range of supersonic speeds is considered subject to a minor aspect-ratio-Mach number restriction for the rectangular plan form and to the condition that the trailing edge is supersonic for the sweptback wings. The formulas presented can be utilized in determining the induced-flow characteristics at any point in the field and are readily adaptable for either numerical computation or analytical determination of any velocity components desired.

Margolis, Kenneth; Elliott, Miriam H.

1959-01-01

235

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

236

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

237

The field-dependent shock profiles of a magnetorhelogical damper due to high impact: an experimental investigation  

NASA Astrophysics Data System (ADS)

This work proposes a new damper featuring magnetorheological fluid (MR damper) and presents its field-dependent damping forces due to high impact. To achieve this goal, a large MR damper, which can produce a damping force of 100 kN at 6 A, is designed and manufactured based on the analysis of the magnetic flux intensity of the damper. After identifying the field-dependent damping force levels of the manufactured MR damper, a hydraulic horizontal shock tester is established. This shock testing system consists of a velocity generator, impact mass, shock programmer, and test mass. The MR damper is installed at the end of the wall in the shock tester and tested under four different experimental conditions. The shock profile characteristics of the MR damper due to different impact velocities are investigated at various input current levels. In addition, the inner pressure of the MR damper during impact, which depends on the input’s current level, is evaluated at two positions that can represent the pressure drop that generates the damping force of the MR damper. It is demonstrated from this impact testing that the shock profiles can be changed by the magnitude of the input current applied to the MR damper. It directly indicates that a desired shock profile can be achieved by installing the MR damper associated with appropriate control logics to adjust the magnitude of the input current.

Kim, Hwan-Choong; Oh, Jong-Seok; Choi, Seung-Bok

2015-02-01

238

A generalized Kelvin solution based method for analyzing elastic fields in heterogeneous rocks due to reservoir water impoundment  

NASA Astrophysics Data System (ADS)

This paper develops an analytical method for assessing the additional elastic fields in the heterogeneous rocks beneath a reservoir due to its water weight loading. The proposed method is based on the fundamental solution of layered elastic solids and integrates numerically it over the loading areas. It can deal with arbitrarily depth-heterogeneous rock solids and complex surface loads. Specifically, the method is applied to the analysis of the stress increases in the rock strata due to the impoundment of water in the Zipingpu reservoir. Nearby the reservoir, the epicenter of the 2008 Wenchuan earthquake was located. The surface contours of the Zipingpu reservoir from the Google map are utilized to obtain the reservoir topography. It is assumed that the water loads act on the projection surface of the water level of the reservoir on the horizontal plane of the dam foundation. The projection surface is discretized into the element mesh and used to generate the reservoir topography and the water loading on the layered rock surface. The proposed method is used to calculate the additional elastic fields in the neighbourhood of the epicenter and beneath the dam.

Xiao, H. T.; Yue, Z. Q.; Zhao, X. M.

2012-06-01

239

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.

2013-12-18

240

Subsidence due to geothermal fluid withdrawal  

SciTech Connect

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

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

1982-10-01

241

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

242

Displacement measurement with intracavity interferometry  

NASA Astrophysics Data System (ADS)

We present a measuring technique for displacement and position sensing over a limited range with detection of standingwave pattern inside of a passive Fabry-Perot cavity. The concept considers locking of the laser optical frequency and the length of the Fabry-Perot cavity in resonance. Fixing the length of the cavity to e.g. a highly stable mechanical reference allows to stabilize wavelength of the laser in air and thus to eliminate especially the faster fluctuations of refractive index of air due to air flow and inhomogeneities. Sensing of the interference maxima and minima within the cavity along the beam axis has been tested and proven with a low loss photoresistive photodetector based on a thin polycrystalline silicon layer. Reduction of losses was achieved thanks to a design as an optimized set of interference layers acting as an antireflection coating. The principle is demonstrated on an experimental setup.

Lazar, Josef; Holá, Miroslava; Fejfar, Antonín.; Stuchlík, Ji?í; Ko?ka, Jan; Oulehla, Jind?ich; ?íp, Ond?ej

2014-05-01

243

Polyimidazoles via aromatic nucleophilic displacement  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

244

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

245

Displacement Measurement and Its Application in Interframe Image Coding  

Microsoft Academic Search

A new technique for estimating interframe displacement of small blocks with minimum mean square error is presented. An efficient algorithm for searching the direction of displacement has been described. The results of applying the technique to two sets of images are presented which show 8-10 dB improvement in interframe variance reduction due to motion compensation. The motion compensation is applied

JASWANT R. JAIN; ANIL K. JAIN

1981-01-01

246

Gas miscible displacement enhanced oil recovery: Technology status report  

SciTech Connect

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

Not Available

1986-10-01

247

Spatiotemporal splitting of global eigenmodes due to cross-field coupling via vortex dynamics in drift wave turbulence.  

PubMed

Spatiotemporal splitting events of drift wave (DW) eigenmodes due to nonlinear coupling are investigated in a cylindrical helicon plasma device. DW eigenmodes in the radial-azimuthal cross section have been experimentally observed to split at radial locations and recombine into the global eigenmode with a time shorter than the typical DW period (t?fDW(-1)). The number of splits correlates with the increase of turbulence. The observed dynamics can be theoretically reproduced by a Kuramoto-type model of a network of radially coupled azimuthal eigenmodes. Coupling by E×B-vortex convection cell dynamics and ion gyro radii motion leads to cross-field synchronization and occasional mode splitting events. PMID:25615346

Brandt, C; Thakur, S C; Light, A D; Negrete, J; Tynan, G R

2014-12-31

248

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

249

Emission enhancement of GaN/AlGaN single-quantum-wells due to screening of piezoelectric field  

SciTech Connect

Photoluminescence (PL) enhancement due to the screening of piezoelectric field induced by Si-doping is systematically studied in GaN/AlGaN quantum wells (QWs) fabricated by metal organic vapor-phase-epitaxy (MOVPE). The PL enhancement ratio of QWs for Si-doped directly into the wells was much larger than that for doped only into the barrier layers. This result shows that the crystal quality of the quantum well is not so damaged by heavy Si-doping, which is different from the cases of GaAs or InP material systems. The PL intensity enhancement ratio was especially large for thick wells. The typical value of the enhancement ratio was 30 times for a 5 nm-thick single QW. The optimum Si-doping concentration was approximately 4x10{sup 18} cm{sup {minus}3}. From the well width dependence of the PL enhancement ratio and PL peak shift under high excitation conditions, they determined that the dominant effect inducing the PL enhancement is screening of piezoelectric field in the QWs. These results indicate that Si-doping is very effective for the application of GaN/AlGaN QWs to optical devices.

Kinoshita, A.; Hirayama, H.; Riblet, P.; Ainoya, M.; Hirata, A.; Aoyagi, Y.

2000-07-01

250

Flow channeling in a single fracture induced by shear displacement  

Microsoft Academic Search

The effect on the transport properties of a fracture of a shear displacement u? between its complementary surfaces is investigated experimentally and numerically. The shear displacement u? induces an anisotropy of the fracture aperture field with a correlation length scaling of |u?|, which is significantly larger in the direction perpendicular to u?. This reflects the presence of long fluid flow

Harold Auradou; German Drazer; Alexandro Boschan; Jean-Pierre Hulin; Joel Koplik

2006-01-01

251

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

252

Cation disorder and anion displacement in DIIXVI - AIBIIIXVI2 semiconductors  

NASA Astrophysics Data System (ADS)

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

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

2006-09-01

253

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

254

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

PubMed

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

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

2003-03-18

255

Enfranchising Displaced Voters: Lessons from Bosnia-Herzegovina  

E-print Network

their permanent residences due to war, natural disaster, or other conditions. Our article addresses the challenges of enfranchising refugees and internally-displaced persons (IDPs) by assessing statutory and practical experiences of Bosnia-Herzegovina from 1996...

Prather, Lauren; Herron, Erik S.

2007-01-01

256

Elasticity reconstruction from experimental MR displacement data: initial experience with an overlapping subzone finite element  

E-print Network

as elasticity, a Young's modulus image is obtained which reasonably reflects the true distribution within algorithms for elasticity imaging through interpretation of harmonic displacement fields. While inversionElasticity reconstruction from experimental MR displacement data: initial experience

Miga, Michael I.

257

Displacement Parameter Inversion for a Novel Electromagnetic Underground Displacement Sensor  

PubMed Central

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

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

2014-01-01

258

Displacement parameter inversion for a novel electromagnetic underground displacement sensor.  

PubMed

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

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

2014-01-01

259

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

260

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

261

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

PubMed

The eye is said to be one of the most sensitive organs to microwave heating. According to previous studies, the possibility of microwave-induced cataract formation has been experimentally investigated in rabbit and monkey eyes, but not for the human eye due to ethical reasons. In the present study, the temperature elevation in the lens, the skin around the eye and the core temperature of numerical human and rabbit models for far-field and near-field exposures at 2.45 GHz are investigated. The temperature elevations in the human and rabbit models were compared with the threshold temperatures for inducing cataracts, thermal pain in the skin and reversible health effects such as heat exhaustion or heat stroke. For plane-wave exposure, the core temperature elevation is shown to be essential both in the human and in the rabbit models as suggested in the international guidelines and standards. For localised exposure of the human eye, the temperature elevation of the skin was essential, and the lens temperature did not reach its threshold for thermal pain. On the other hand, the lens temperature elevation was found to be dominant for the rabbit eye. PMID:23390146

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

2013-07-01

262

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

263

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

PubMed

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)] 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)] 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. PMID:25353881

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

2014-05-01

264

Monitoring pipe line stress due to ground displacement  

Microsoft Academic Search

Northwest Pipeline Corp. has a large-diameter natural gas pipe line system from Ignacio, Colo., to Sumas, Wash. At Douglas Pass in Colorado, large landslides required several sections of the line to be relocated outside the slide areas: 4,400 ft of new line in April 1962 and 3,200 ft in March 1963. No serious disruptions occurred for the next 16 years.

J. H. Jr

1986-01-01

265

Monitoring pipe line stress due to ground displacement  

SciTech Connect

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

Greenwood, J.H. Jr.

1986-04-01

266

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

Microsoft Academic Search

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

Isidore K Kouadio; Taro Kamigaki; Hitoshi Oshitani

2010-01-01

267

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.

268

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

269

Worker Displacement, 1995-97  

NSDL National Science Digital Library

Thirty-three million workers were displaced from jobs they had held for at least three years, from January 1997 through December 1999. This number is roughly equivalent to the level of job losses covered in a survey that measured worker displacement from January 1995 through December 1997.

270

Development and Displacement in India: Reforming the Economy towards Sustainability  

NASA Astrophysics Data System (ADS)

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

Siddiqui, Kalim

2012-05-01

271

Apes Communicate about Absent and Displaced Objects: Methodology Matters  

PubMed Central

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

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

2013-01-01

272

JOURNAL DE PHYSIQUE ColloqueCl,supplkment au nO 1, Tome41,janvier 1980,page C1-355 M~~SSBAUER ELECTRIC FIELD GRADIENT AM) MEN SQUARE DISPLACEMENT IN NATURALLY OCCURING FeS2 (PYRITE)  

E-print Network

~~SSBAUER ELECTRIC FIELD GRADIENT AM) MEN SQUARE DISPLACEMENT IN NATURALLY OCCURING FeS2 (PYRITE) SINGLE CRYSTALS R Espirito Santo, 29.000 Victoria, E.S., Brazi 2. Pyrite, cubic mineral of FeS2, has four molecules per unit = 0.386, forming four equivalent but differently oriented sites. M8ssbauer spectra of pyrite, fig. 1

Paris-Sud XI, Université de

273

The Analysis of Soil Resistance During Screw Displacement Pile Installation  

NASA Astrophysics Data System (ADS)

The application of screw displacement piles (SDP) is still increasing due to their high efficiency and many advantages. However, one technological problem is a serious disadvantage of those piles. It relates to the generation of very high soil resistance during screw auger penetration, especially when piles are installed in non-cohesive soils. In many situations this problem causes difficulties in creating piles of designed length and diameter. It is necessary to find a proper method for prediction of soil resistance during screw pile installation. The analysis of screw resistances based on model and field tests is presented in the paper. The investigations were carried out as part of research project, financed by the Polish Ministry of Science and Higher Education. As a result of tests and analyses the empirical method for prediction of rotation resistance (torque) during screw auger penetration in non-cohesive subsoil based on CPT is proposed.

Krasinski, Adam

2015-02-01

274

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

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

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

277

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

278

Serial forced displacement in American cities, 1916-2010.  

PubMed

Serial forced displacement has been defined as the repetitive, coercive upheaval of groups. In this essay, we examine the history of serial forced displacement in American cities due to federal, state, and local government policies. We propose that serial forced displacement sets up a dynamic process that includes an increase in interpersonal and structural violence, an inability to react in a timely fashion to patterns of threat or opportunity, and a cycle of fragmentation as a result of the first two. We present the history of the policies as they affected one urban neighborhood, Pittsburgh's Hill District. We conclude by examining ways in which this problematic process might be addressed. PMID:21607786

Fullilove, Mindy Thompson; Wallace, Rodrick

2011-06-01

279

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

280

Estimation of errors due to imperfect alignment of a probe line in cylindrical near field antenna measurement  

NASA Astrophysics Data System (ADS)

An error analysis has been carried out on a near-field measurement (NFM) system in which the probe scanning line is not exactly parallel to the antenna rotation axis. Approximate expressions have been obtained for the far-field radiation patterns in terms of error-free pattern. As an example, far-field patterns generated from a circularly symmetrical distribution with misalignments are calculated and compared with the error-free far-field pattern. The results of the study may be useful in developing cylindrical NFM systems and in interpreting measurement results.

Iigusa, K.; Teshirogi, T.

281

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

282

Superconducting inductive displacement detection of a microcantilever  

SciTech Connect

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

Vinante, A., E-mail: anvinante@fbk.eu [Istituto di Fotonica e Nanotecnologie, CNR - Fondazione Bruno Kessler, I-38123 Povo, Trento (Italy)

2014-07-21

283

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.

Andrea Vinante

2014-05-14

284

Superconducting inductive displacement detection of a microcantilever  

NASA Astrophysics Data System (ADS)

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

Vinante, A.

2014-07-01

285

Preparation of nanodispersions containing ?-carotene by solvent displacement method  

Microsoft Academic Search

The aim of this study is to produce ?-carotene-loaded nanodispersions containing poly(d,l-lactic acid) (PLA) and poly(d,l-lactic-co-glycolic acid) (PLGA), that are widely used as polymer carriers, by solvent displacement method. Nanoparticles containing ?-carotene were produced by interfacial deposition of the biodegradable polymer, due to the displacement of acetone from the dispersed phase. Gelatin or Tween® 20 was used as stabilizing hydrocolloids

Henelyta S. Ribeiro; Boon-Seang Chu; Sosaku Ichikawa; Mitsutoshi Nakajima

2008-01-01

286

Holographic volume displacement calculations via multiwavelength digital holography.  

PubMed

In this work multiwavelength digital holography is applied to calculate the volume displacement of various topographic surface features. To accurately measure the volume displacement of macroscopic features, long synthetic wavelengths up to several millimeters are generated using tunable IR laser sources. Practical methods of implementation are considered, including geometric effects of both Michelson and Mach-Zehnder recording configurations and error due to wavelength selection. PMID:24663416

Williams, L; Banerjee, P P; Nehmetallah, G; Praharaj, S

2014-03-10

287

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

E-print Network

of light travel time between the ground and the lower ionosphere. Indeed, the establishment of the QE field traveling at the speed of light (c) which reflect back and forth between the ground and the ionosphere electric (E) field of the deposited (removed) thundercloud charge and its image in the ionosphere

Pasko, Victor

288

Faraday's law of induction and the force on a body due to change in its magnetization in an electric field  

Microsoft Academic Search

From arguments based on Faraday's Law of induction, it is shown that a body whose intensity of magnetization is changing should, in general, experience a force when situated in an electrostatic field in a manner analogous to the force experienced by a conductor carrying an electric current in a magnetic field.

K. G. Ramanathan

1962-01-01

289

A program to compute magnetic fields, forces, and inductances due to solid rectangular conductors arbitrarily positioned in space  

Microsoft Academic Search

The computer program BUS3D was developed to compute the magnetic field and vector potential produced by a collection of rectangular busbars carrying dc current and arbitrarily oriented in space, using exact analytic expressions. The field and vector potential expressions are used in numerical integrations to obtain forces on individual busbars and inductances or mutual inductances between collections of busbars. The

R. T. Honjo; R. M. del Vecchio

1986-01-01

290

Assimilation of D-InSAR and sub-pixel image correlation displacement measurements for coseismic fault parameter estimation: Application to the 2005 Kashmir earthquake  

NASA Astrophysics Data System (ADS)

We apply both sub-pixel image correlation and differential interferometry (D-InSAR) on a series of ENVISAT images from October 2004 to June 2006 in order to map the deformation due to the Kashmir earthquake (Mw=7.6) of October 8th, 2005. The 3D surface displacement field at the Earth's surface as well as the displacement field at depth on the ruptured fault had previously been estimated based on 6 measurements from sub-pixel image correlation (Pathier et al., 2006). Here, we follow the same approach adding more measurements from sub-pixel image correlation. We also improved the D-InSAR data quality by a multi-scale frequencies analysis, which provides complementary information, less robust but more precise, in the far field, at several hundred meters from the fault trace. Firstly, the 3D displacement at the Earth's surface, with 3 components E, N, Up, is estimated by a linear inversion. The evolution of displacement value as well as associated uncertainty for each component is analyzed while adding redundant measurements from sub-pixel image correlation and D-InSAR. Three strategies of assimilation are proposed, implemented and compared. For each pixel, the 3D displacement field at the Earth's surface is obtained by inversion of 4 selected measurements (displacement in range and azimuth directions for both ascending and descending tracks) whose associated uncertainty is the smallest among all of the available measurements. The 3D displacement field at the Earth's surface is obtained by inversion of all measurements available for a given pixel. We perform several inversions with 4 displacement measurements (displacement in range and azimuth directions for both ascending and descending tracks) each time on each pixel, and then combine the obtained 3D displacement field estimations in order to get a final estimation with reduced uncertainty. Secondly, the fault geometry as well as mean slip, are estimated by inverting a forward model of rectangular dislocation in a homogeneous elastic half-space. The contribution of redundant measurements added, especially the measurements from D-InSAR to the improvement of the model is highlighted. Moreover, the new information provided by D-InSAR in the far field, allows us to test several configurations for the co-seismic fault geometry, such as a single ramp as previously estimated (Pathier et al., 2006) or, a ramp-décollement configuration.

Yan, Yajing; Pinel, Virginie; Trouvé, Emmanuel; Pathier, Erwan

2010-05-01

291

Wirelessly Interrogated Position or Displacement Sensors  

NASA Technical Reports Server (NTRS)

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

Woodard, Stanley E.; Taylor, Bryant D.

2007-01-01

292

Displacement sensing system and method  

DOEpatents

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

VunKannon Jr., Robert S

2006-08-08

293

Literature Review of Displacement Ventilation  

E-print Network

Performance Evaluation and Design Guidelines for Displacement Ventilation” by Chen and Clicksman (2003), were used to begin the literature search. Their references include papers, articles, and web sites presenting major contributions to the understanding...

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

294

Population Displacements Associated with Environmentally  

E-print Network

associated with large infrastructure ­ Typology of displacements ­ Case Studies · Mali · Brazil · South to changing climate (drought flood­ Infrastructure in response to changing climate (drought, flood, disasters Socio economic Impacts Enviro Impacts Dam Climate Change Fresh H20 Salinization Drought Flood

Columbia University

295

Polyimidazoles Via Aromatic Nucleophilic Displacement  

NASA Technical Reports Server (NTRS)

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

Connell, John W.; Hergenrother, Paul M.

1990-01-01

296

Geometric Deformation-Displacement Maps  

Microsoft Academic Search

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

Gershon Elber

2002-01-01

297

40 CFR 205.153 - Engine displacement.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Engine displacement. 205.153 Section 205.153 Protection...CONTROLS Motorcycles § 205.153 Engine displacement. (a) Engine displacement must be calculated using nominal...

2011-07-01

298

40 CFR 205.153 - Engine displacement.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Engine displacement. 205.153 Section 205.153 Protection...CONTROLS Motorcycles § 205.153 Engine displacement. (a) Engine displacement must be calculated using nominal...

2010-07-01

299

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

300

Simulation of degradation of dielectric breakdown field of thermal SiO2 films due to voids in Si wafers  

Microsoft Academic Search

Degradation of the dielectric breakdown field of thermal SiO2 film caused by voids that are formed during growth of silicon single crystal has been a serious problem with reliability of MOS devices. To understand the degradation of breakdown field, local thinning of oxide film grown on pits (i.e., voids exposed at the wafer surface) is simulated using a simple model,

Yuhki Satoh; Takaaki Shiota; Hisashi Furuya

2000-01-01

301

Comparing Teaching Approaches About Maxwell's Displacement Current  

NASA Astrophysics Data System (ADS)

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

Karam, Ricardo; Coimbra, Debora; Pietrocola, Maurício

2014-08-01

302

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

303

Some comments on particle image displacement velocimetry  

NASA Technical Reports Server (NTRS)

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

Lourenco, L. M.

1988-01-01

304

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

305

Phase-sensitive lateral motion estimator for measurement of artery-wall displacement--phantom study.  

PubMed

Artery-wall motion due to the pulsation of the heart is often measured to evaluate mechanical properties of the arterial wall. Such motion is thought to occur only in the arterial radial direction because the main source of the motion is an increase of blood pressure. However, it has recently been reported that the artery also moves in the longitudinal direction. Therefore, a 2-D motion estimator is required even when the artery is scanned in the longitudinal direction because the arterial wall moves both in the radial (axial) and longitudinal (lateral) directions. Methods based on 2-D correlation of RF echoes are often used to estimate the lateral displacement together with axial displacement. However, these methods require much interpolation of the RF echo or correlation function to achieve a sufficient resolution in the estimation of displacement. To overcome this problem, Jensen et al. modulated the ultrasonic field in the lateral direction at a designed spatial frequency to use the lateral phase for the estimation of lateral motion. This method, namely, the lateral modulation method, generates complex signals whose phases change depending on the lateral motion. Therefore, the lateral displacement can be estimated with a good resolution without interpolation, although special beamformers are required. The present paper describes a method that can be applied to ultrasonic echoes obtained by a conventional beamformer to estimate lateral displacements using the phases of lateral fluctuations of ultrasonic echoes. In the proposed method, complex signals were generated by the Hilbert transform, and the phase shift was estimated by correlation-based estimators. The proposed method was validated using a cylindrical phantom mimicking an artery. The error in the lateral displacement estimated by the proposed method was 13.5% of the true displacement of 0.5 mm with a kernel size used for calculating the correlation function of 0.6 mm in the lateral direction, which was slightly smaller than the width at -20 dB of the maximum lateral ultrasonic field (about 0.8 mm). PMID:19942531

Hasegawa, Hideyuki; Kanai, Hiroshi

2009-11-01

306

Contactless sub-millimeter displacement measurements  

NASA Astrophysics Data System (ADS)

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

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

2008-07-01

307

Uncertainty evaluation of dosimetry due to plastic holder for restraining small animal in in vivo near field exposure setup  

Microsoft Academic Search

In most in vivo exposure setups for testing biological effects of cellular telephones on a small animal, a plastic holder is commonly used for restraining the small animal in order to keep a constant near-field exposure. Although the plastic holder should affect the specific absorption rate (SAR) in the small animal, few researchers have considered its influence in their exposure

Jianqing Wang; Takashi Saito; Osamu Fujiwara

2004-01-01

308

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

Microsoft Academic Search

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

C. A. Reddy; C. V. Devasia

1981-01-01

309

FIELD ACTIVITIES PLAN This template is designed to help you ensure you are meeting your due diligence  

E-print Network

; Approx. 6 min. via helicopter or 6 hours on foot 2. Field Research Participants Name: Position: Emergency Helicopters Local Emergency Response Number: 907-789-5600 Juneau Police: 907-586-0600 Other: 911 (available and crossing glacier-fed streams; (4) encounters with black or brown bears; or (5) helicopter-based transport

Machel, Hans

310

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

311

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

312

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

313

Generation of displaced squeezed superpositions of coherent states  

SciTech Connect

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

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

2012-03-15

314

Job Displacement Among Single Mothers:  

PubMed Central

Given the recent era of economic upheaval, studying the effects of job displacement has seldom been so timely and consequential. Despite a large literature associating displacement with worker well-being, relatively few studies focus on the effects of parental displacement on child well-being, and fewer still focus on implications for children of single parent households. Moreover, notwithstanding a large literature on the relationship between single motherhood and children’s outcomes, research on intergenerational effects of involuntary employment separations among single mothers is limited. Using 30 years of nationally representative panel data and propensity score matching methods, we find significant negative effects of job displacement among single mothers on children’s educational attainment and social-psychological well-being in young adulthood. Effects are concentrated among older children and children whose mothers had a low likelihood of displacement, suggesting an important role for social stigma and relative deprivation in the effects of socioeconomic shocks on child well-being. PMID:25032267

Brand, Jennie E.; Thomas, Juli Simon

2015-01-01

315

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

316

Changes in the size distribution of a water-in-oil emulsion due to electric field induced coalescence  

SciTech Connect

A knowledge of the droplet size distribution of a water-in-oil emulsion subjected to an electric field provides useful information regarding electrostatic coalescence which can aid the formulation of coalescence models and the design of commercial electrostatic separators. Water droplet-size distribution measurements made using a laser light-scattering technique during the electrostatic resolution of a low-water-content water-in-oil emulsion are reported. A qualitative explanation of the results is presented.

Williams, T.J.; Bailey, A.G.

1986-05-01

317

Changes in the Size Distribution of a Water-in-Oil Emulsion Due to Electric Field Induced Coalescence  

Microsoft Academic Search

A knowledge of the droplet size distribution of a water-in-oil emulsion subjected to an electric field provides useful information regarding electrostatic coalescence which can aid the formulation of coalescence models and the design of commercial electrostatic separators. Water droplet size-distribution measurements made using a laser light-scattering technique during the electrostatic resolution of a low-water-content water-in-oil emulsion are reported. A qualitative

Trevor J. Williams; Adrian G. Bailey

1986-01-01

318

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

319

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

320

Perceived displacement explains wolfpack effect  

PubMed Central

We investigate the influence of perceived displacement of moving agent-like stimuli on the performance in dynamic interactive tasks. In order to reliably measure perceived displacement we utilize multiple tasks with different task demands. The perceived center of an agent's body is displaced in the direction in which the agent is facing and this perceived displacement is larger than the theoretical position of the center of mass would predict. Furthermore, the displacement in the explicit judgment is dissociated from the displacement obtained by the implicit measures. By manipulating the location of the pivot point, we show that it is not necessary to postulate orientation as an additional cue utilized by perception, as has been suggested by earlier studies. These studies showed that the agent's orientation influences the detection of chasing motion and the detection-related performance in interactive tasks. This influence has been labeled wolfpack effect. In one of the demonstrations of the wolfpack effect participants control a green circle on a display with a computer mouse. It has been shown that participants avoid display areas with agents pointing toward the green circle. Participants do so in favor of areas where the agents point in the direction perpendicular to the circle. We show that this avoidance behavior arises because the agent's pivot point selected by the earlier studies is different from where people locate the center of agent's body. As a consequence, the nominal rotation confounds rotation and translation. We show that the avoidance behavior disappears once the pivot point is set to the center of agent's body. PMID:25566114

Šimkovic, Matúš; Träuble, Birgit

2014-01-01

321

A Wireless Laser Displacement Sensor Node for Structural Health Monitoring  

PubMed Central

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

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

2013-01-01

322

Particle displacement tracking for PIV  

NASA Technical Reports Server (NTRS)

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

Wernet, Mark P.

1990-01-01

323

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

324

Electromagnetic Fields Due to a Loop Current in a CasedBorehole Surrounded by Uniform Whole Space  

SciTech Connect

Precise evaluation of electromagnetic (EM) response in steel-cased borehole is an essential first step towards developing techniques for casing parameter evaluation, which would ultimately help evaluating the formation response. In this report we demonstrate a numerical scheme for accurately computing EM responses in cased borehole environment. For improved numerical accuracy we use explicit representations of the electromagnetic spectra inside the borehole, in the casing, and in the formation. Instead of conventional Hankel transform, FFT is used to improve the numerical accuracy. The FFT approach allows us to compute fields at positions very close to the source loop, including the center of the transmitter loop.

Lee, K.H.; Song, Y.

1998-01-01

325

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

NASA Technical Reports Server (NTRS)

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

Deguchi, Shuji; Watson, William D.

1990-01-01

326

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

327

Job Displacement, Disability, and Divorce  

Microsoft Academic Search

Earnings shocks should affect divorce probability by changing a couple's expected gains from marriage. We find that the divorce hazard rises after a spouse's job displacement but does not change after a spousal disability. This difference casts doubt on a purely pecuniary motivation for divorce following earnings shocks, since both types of shocks exhibit similar long-run economic consequences. Furthermore, the

2004-01-01

328

Displacement meters for liquid measurement  

SciTech Connect

The purpose of this paper is to examine the positive displacement (PD) meter. The emphasis will be on the factors influencing the design and performance of the meter for liquid petroleum measurement. However, these factors can be applied to other liquids as well. Also included are discussions on PD meter enhancements that will increase the PD meter`s performance.

Kalivoda, R.J. [Smith Meter Inc., Erie, PA (United States)

1995-12-01

329

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

330

Effects of seismic intensity and socioeconomic status on injury and displacement after the 2007 Peru earthquake.  

PubMed

Earthquakes are a major cause of displacement, particularly in developing countries. Models of injury and displacement can be applied to assist governments and aid organisations in effectively targeting preparedness and relief efforts. A stratified cluster survey was conducted in January 2008 to evaluate risk factors for injury and displacement following the 15 August 2007 earthquake in southern Peru. In statistical modelling, seismic intensity, distance to rupture, living conditions, and educational attainment collectively explained 54.9 per cent of the variability in displacement rates across clusters. Living conditions was a particularly significant predictor of injury and displacement, indicating a strong relationship between risk and socioeconomic status. Contrary to expectations, urban, periurban, and rural clusters did not exhibit significantly different injury and displacement rates. Proxies of socioeconomic status, particularly the living conditions index score, proved relevant in explaining displacement, likely due to unmeasured aspects of housing construction practices and building materials. PMID:20618381

Milch, Karen; Gorokhovich, Yuri; Doocy, Shannon

2010-10-01

331

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

332

Disability, displacement and public health: a vision for Haiti.  

PubMed

Refugees and internally displaced persons (IDPs) with disabilities are some of the most neglected and socially excluded groups within any population. Natural disasters are events that cause bodily harm resulting in disability and that result in the displacement of people. Many predict a continual increase of natural disasters in the future due to changing climates. People with disabilities constitute one of the most vulnerable social groups in the case of a natural disaster. In 2010, Haiti suffered a devastating earthquake leading to great social, health and economic hardship including the displacement of people with disabilities. Due to the very extent of the structural devastation Haiti experienced and the international focus on assisting Haitians who suffered injuries leading to disabilities, there is an opportunity for Haiti to become a model for future disaster management in terms of mainstreaming the needs of people with disabilities in the restoration, resettlement and reintegration process. PMID:21608390

Wolbring, Gregor

2011-01-01

333

Polymer versus monomer as displacer in immobilized metal affinity chromatography.  

PubMed

Successful immobilized metal affinity chromatography (IMAC) of proteins on Cu2+-iminodiacetic acid Sepharose has been carried out in a displacement mode using a synthetic copolymer of vinyl imidazole and vinyl caprolactam [poly(VI-VCL)] as a displacer. Vinyl caprolactam renders the co-polymer with the thermosensitivity, e.g., property of the co-polymer to precipitate nearly quantitatively from aqueous solution on increase of the temperature to 48 degrees C. A thermostable lactate dehydrogenase from the thermophilic bacterium Bacillus stearothermophilus modified with a (His)6-tag [(His)6-LDH] has been purified using an IMAC column. For the first time it was clearly demonstrated that a polymeric displacer [poly(VI-VCL)] was more efficient compared to a monomeric displacer (imidazole) of the same chemical nature, probably due to the multipoint interaction of imidazole groups within the same macromolecule with one Cu2+ ion. Complete elution of bound (His)6-LDH has been achieved at 3.7 mM concentration of imidazole units of the co-polymer (5 mg/ml), while this concentration of free imidazole was sufficient to elute only weakly bound proteins. Complete elution of (His)6-LDH by the free imidazole was achieved only at concentrations as high as 160 mM. Thus, it was clearly demonstrated, that the efficiency of low-molecular-mass displacer could be improved significantly by converting it into a polymeric displacer having interacting groups of the same chemical nature. PMID:11334341

Arvidsson, P; Ivanov, A E; Galaev IYu; Mattiasson, B

2001-04-01

334

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

SciTech Connect

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

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

2011-02-15

335

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

336

Dynamic displacement measurement of bridges using vision-based system  

NASA Astrophysics Data System (ADS)

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

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

2006-03-01

337

Micro-pixel accuracy centroid displacement estimation and detector calibration  

E-print Network

Micro-pixel accuracy centroid displacement estimation and detector calibration Chengxing Zhai, Mike to sub-micropixel accuracy. Inter-pixel response variations exist in real detectors, e.g. CCDs, which we (PSF) to the image data. Because the PSF is typically not known to high accuracy due to wavefront

Masci, Frank

338

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

339

White Collar Displacement: Job Erosion in the Service Sector.  

ERIC Educational Resources Information Center

The National Commission for Employment Policy estimates that 19 million workers--17 percent of the work force--are in jobs directly threatened by office automation, and the consequences of the displacement of clerical workers due to increasing office computerization are as serious as those from manufacturing job loss. Between 1983 and 1988, almost…

Golden, Lonnie; Danann, Sharon

340

Displacement Synthesis of Cu Shells Surrounding Co Nanoparticles  

E-print Network

70813, USA Copper shells were fabricated by a displacement method around Co nanoparticles (3.2 0.6 nm) at room temperature in a copper-citrate aqueous electrolyte. The nanoparticles were synthesized by a wet spectroscopy XAS studies detected evidence of oxidation due to discontinuous Au coatings around Fe

Guo, John Zhanhu

341

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

342

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

343

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

344

Fixture for Linearly Variable Displacement Transducers  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

345

20 CFR 211.8 - Displacement allowance.  

Code of Federal Regulations, 2010 CFR

...Benefits 1 2010-04-01 2010-04-01 false Displacement allowance. 211.8 Section 211.8 Employees' Benefits...RETIREMENT ACT CREDITABLE RAILROAD COMPENSATION § 211.8 Displacement allowance. An allowance paid to an employee...

2010-04-01

346

20 CFR 211.8 - Displacement allowance.  

Code of Federal Regulations, 2011 CFR

...Benefits 1 2011-04-01 2011-04-01 false Displacement allowance. 211.8 Section 211.8 Employees' Benefits...RETIREMENT ACT CREDITABLE RAILROAD COMPENSATION § 211.8 Displacement allowance. An allowance paid to an employee...

2011-04-01

347

Recession Swells Count of Displaced Workers.  

ERIC Educational Resources Information Center

The weak economy of the early 1990s increased the number of displaced workers. Although a disproportionately large share were in the goods-producing industries, displacements were much more widespread across industries than a decade earlier. (Author)

Gardner, Jennifer M.

1993-01-01

348

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

349

PSInSAR displacements related to soil creep and rainfall intensities in the Alpine foreland of western Slovenia  

NASA Astrophysics Data System (ADS)

An assessment of the relationship between displacement rates of objects located in areas of active soil creep and rainfall intensities was performed using a permanent-scatterer technique of synthetic aperture radar interferometry. The study focussed on two areas in central Slovenia during the period between April 1992 and December 2000. Based on field assessments, six permanent scatterers for one area and 11 scatterers for the other were selected for analysis from > 4300 available permanent scatterers. Displacement rates related to creeping processes were compared with the different durations and intensities of rain in order to assess the threshold values that initiate the creeping process and to assess the relationship between the speed of the movement and the precipitation events. Although the permanent scatterer displacement data contain much noise, our results indicate that soil creep is induced by 20 mm of rain in 1 day or 50 mm of rain in 3 days, causing an average elevation decrease of 0.5 and 1 mm, respectively. The elevation decreases due to soil creep were observed as instantaneous events, since no increased correlations were observed when a time lag between precipitation and displacement was taken into account. Models developed in this research indicated very similar rates of tectonic uplift for the two research areas in the event of no rain, and these rates were found to be faster than the regional tectonic uplift. This suggests that areas with high rates of tectonic uplift and areas of active soil creep may be related.

Žibret, Gorazd; Komac, Marko; Jemec, Mateja

2012-11-01

350

Miscible Displacement Simulation by Finite Element Methods in Distributed Memory  

E-print Network

Lauro Muller 455, Botafogo, 22290­160, Rio de Janeiro, RJ, Brazil Alvaro L. G. A. Coutinho Deptamento de­970, Brazil Abstract Finite element methods taylored for large scale simulation of incompressible misci­ ble computationally intensive field in petroleum engineering. Miscible displacements which model enhanced oil recovery

Coutinho, Alvaro L. G. A.

351

Internal displacement and strain imaging using ultrasonic speckle tracking  

Microsoft Academic Search

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

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

1994-01-01

352

UMBILICS : STATIC PROPERTIES AND SHEAR-INDU CED DISPLACEMENTS  

E-print Network

the structure of umbilical « defects » which should appear under certain conditions in a nematic slab in an electric field. We show that a shear flow can induce a displacement of these defects. LE JOURNAL DE. - A slab contains a nematic monocrystal with a negative dielectric (or magnetic) anisotropy (Fig. 1

Boyer, Edmond

353

20 CFR 627.230 - Displacement.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Displacement. 627.230 Section 627.230...Program Requirements § 627.230 Displacement. (a) No currently employed worker...any participant (including partial displacement such as a reduction in the hours...

2011-04-01

354

The case for character displacement in plants.  

PubMed

The evidence for character displacement as a widespread response to competition is now building. This progress is largely the result of the establishment of rigorous criteria for demonstrating character displacement in the animal literature. There are, however, relatively few well-supported examples of character displacement in plants. This review explores the potential for character displacement in plants by addressing the following questions: (1) Why aren't examples of character displacement in plants more common? (2) What are the requirements for character displacement to occur and how do plant populations meet those requirements? (3) What are the criteria for testing the pattern and process of character displacement and what methods can and have been used to address these criteria in the plant literature? (4) What are some additional approaches for studying character displacement in plants? While more research is needed, the few plant systems in which character displacement hypotheses have been rigorously tested suggest that character displacement may play a role in shaping plant communities. Plants are especially amenable to character displacement studies because of the experimental ease with which they can be used in common gardens, selection analyses, and breeding designs. A deeper investigation of character displacement in plants is critical for a more complete understanding of the ecological and evolutionary processes that permit the coexistence of plant species. PMID:24683467

Beans, Carolyn M

2014-03-01

355

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

356

The case for character displacement in plants  

PubMed Central

The evidence for character displacement as a widespread response to competition is now building. This progress is largely the result of the establishment of rigorous criteria for demonstrating character displacement in the animal literature. There are, however, relatively few well-supported examples of character displacement in plants. This review explores the potential for character displacement in plants by addressing the following questions: (1) Why aren't examples of character displacement in plants more common? (2) What are the requirements for character displacement to occur and how do plant populations meet those requirements? (3) What are the criteria for testing the pattern and process of character displacement and what methods can and have been used to address these criteria in the plant literature? (4) What are some additional approaches for studying character displacement in plants? While more research is needed, the few plant systems in which character displacement hypotheses have been rigorously tested suggest that character displacement may play a role in shaping plant communities. Plants are especially amenable to character displacement studies because of the experimental ease with which they can be used in common gardens, selection analyses, and breeding designs. A deeper investigation of character displacement in plants is critical for a more complete understanding of the ecological and evolutionary processes that permit the coexistence of plant species. PMID:24683467

Beans, Carolyn M

2014-01-01

357

Three-input majority logic gate and multiple input logic circuit based on DNA strand displacement.  

PubMed

In biomolecular programming, the properties of biomolecules such as proteins and nucleic acids are harnessed for computational purposes. The field has gained considerable attention due to the possibility of exploiting the massive parallelism that is inherent in natural systems to solve computational problems. DNA has already been used to build complex molecular circuits, where the basic building blocks are logic gates that produce single outputs from one or more logical inputs. We designed and experimentally realized a three-input majority gate based on DNA strand displacement. One of the key features of a three-input majority gate is that the three inputs have equal priority, and the output will be true if any of the two inputs are true. Our design consists of a central, circular DNA strand with three unique domains between which are identical joint sequences. Before inputs are introduced to the system, each domain and half of each joint is protected by one complementary ssDNA that displays a toehold for subsequent displacement by the corresponding input. With this design the relationship between any two domains is analogous to the relationship between inputs in a majority gate. Displacing two or more of the protection strands will expose at least one complete joint and return a true output; displacing none or only one of the protection strands will not expose a complete joint and will return a false output. Further, we designed and realized a complex five-input logic gate based on the majority gate described here. By controlling two of the five inputs the complex gate can realize every combination of OR and AND gates of the other three inputs. PMID:23710909

Li, Wei; Yang, Yang; Yan, Hao; Liu, Yan

2013-06-12

358

Thermal field of an oil bed in a nonstationary pressure field  

Microsoft Academic Search

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

A. R. Sabitov; R. F. Sharafutdinov

1999-01-01

359

Current Density and Plasma Displacement Near Perturbed Rational Surface  

SciTech Connect

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

A.H. Boozer and N. Pomphrey

2010-10-10

360

Second-order Darboux displacements  

NASA Astrophysics Data System (ADS)

The potentials for a one-dimensional Schrödinger equation that are displaced along the x-axis under second-order Darboux transformations, called 2-SUSY invariant, are characterized in terms of a differential-difference equation. The solutions of the Schrödinger equation with such potentials are given analytically for any value of the energy. The method is illustrated by a two-soliton potential. It is proved that a particular case of the periodic Lamé-Ince potential is 2-SUSY invariant. Both Bloch solutions of the corresponding Schrödinger equation are found for any value of the energy. A simple analytic expression for a family of two-gap potentials is derived.

Samsonov, B. F.; Glasser, M. L.; Negro, J.; Nieto, L. M.

2003-10-01

361

Detection of microwave emission due to rock fracture as a new tool for geophysics: A field test at a volcano in Miyake Island, Japan  

NASA Astrophysics Data System (ADS)

This paper describes a field test to verify a newly discovered phenomenon of microwave emission due to rock fracture in a volcano. The field test was carried out on Miyake Island, 150 km south of Tokyo. The main objective of the test was to investigate the applicability of the phenomenon to the study of geophysics, volcanology, and seismology by extending observations of this phenomenological occurrence from the laboratory to the natural field. We installed measuring systems for 300 MHz, 2 GHz, and 18 GHz-bands on the mountain top and mountain foot in order to discriminate local events from regional and global events. The systems include deliberate data subsystems that store slowly sampled data in the long term, and fast sampled data when triggered. We successfully obtained data from January to February 2008. During this period, characteristic microwave pulses were intermittently detected at 300 MHz. Two photographs taken before and after this period revealed that a considerably large-scale collapse occurred on the crater cliff. Moreover, seismograms obtained by nearby observatories strongly suggest that the crater subsidence occurred simultaneously with microwave signals on the same day during the observation period. For confirmation of the microwave emission caused by rock fracture, these microwave signals must be clearly discriminated from noise, interferences, and other disturbances. We carefully discriminated the microwave data taken at the mountaintop and foot, checked the lightning strike data around the island, and consequently concluded that these microwave signals could not be attributed to lightning. Artificial interferences were discriminated by the nature of their waveforms. Thus, we inferred that the signals detected at 300 MHz were due to rock fractures during cliff collapses. This result may provide a useful new tool for geoscientists and for the mitigation of natural hazards.

Takano, Tadashi; Maeda, Takashi; Miki, Yoji; Akatsuka, Sayo; Hattori, Katsumi; Nishihashi, Masahide; Kaida, Daishi; Hirano, Takuya

2013-07-01

362

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

PubMed

The predictive accuracy of iNPH diagnoses could be increased using a combination of supplemental tests for iNPH. To evaluate the dynamic state of water displacement during the cardiac cycle in idiopathic normal pressure hydrocephalus (iNPH), we determined the change in water displacement using q-space analysis of diffusion magnetic resonance image. ECG-triggered single-shot diffusion echo planar imaging was used. Water displacement was obtained from the displacement probability profile calculated by Fourier transform of the signal decay fitted as a function of the reciprocal spatial vector q. Then maximum minus minimum displacement (delta-displacement), of all cardiac phase images was calculated. We assessed the delta-displacement in white matter in patients with iNPH and atrophic ventricular dilation (atrophic VD), and in healthy volunteers (control group). Delta-displacement in iNPH was significantly higher than those in the atrophic VD and control. This shows that water molecules of the white matter in iNPH are easily fluctuated by volume loading of the cranium during the cardiac cycle, due to the decrease in intracranial compliance. There was no significant correlation between delta-displacement and displacement. The delta-displacement and the displacement do not necessarily yield the same kind of information. Delta-displacement demonstrated to obtain biophysical information about fluctuation. This analysis may be helpful in the understanding physiology and pathological condition in iNPH and the assisting in the diagnosis. PMID:25614094

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

2015-03-01

363

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

E-print Network

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 0.65 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.

Haruichi Washimi; Shinpei Shibata; Masao Mori

1997-11-22

364

Reciprocating magnetic refrigerator employing tandem porous matrices within a reciprocating displacer  

NASA Technical Reports Server (NTRS)

Disclosed is a method and apparatus for a magnetic refrigeration system. A continuously reciprocating displacer houses at least a pair of paramagnetic substances each of which is alternately driven into and out of a magnetic field. Two separate bidirectional pumping systems flow helium gas through the displacer and through both paramagnetic substances to create heat exchange conditions at two separate temperature extremes.

Johnson, D. L. (inventor)

1985-01-01

365

Surface Displacements in the 1906 San Francisco and 1989 Loma Prieta Earthquakes  

Microsoft Academic Search

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

Paul Segall; Mike Lisowski

1990-01-01

366

A computer vision-based approach for structural displacement measurement  

NASA Astrophysics Data System (ADS)

Along with the incessant advancement in optics, electronics and computer technologies during the last three decades, commercial digital video cameras have experienced a remarkable evolution, and can now be employed to measure complex motions of objects with sufficient accuracy, which render great assistance to structural displacement measurement in civil engineering. This paper proposes a computer vision-based approach for dynamic measurement of structures. One digital camera is used to capture image sequences of planar targets mounted on vibrating structures. The mathematical relationship between image plane and real space is established based on computer vision theory. Then, the structural dynamic displacement at the target locations can be quantified using point reconstruction rules. Compared with other tradition displacement measurement methods using sensors, such as accelerometers, linear-variable-differential-transducers (LVDTs) and global position system (GPS), the proposed approach gives the main advantages of great flexibility, a non-contact working mode and ease of increasing measurement points. To validate, four tests of sinusoidal motion of a point, free vibration of a cantilever beam, wind tunnel test of a cross-section bridge model, and field test of bridge displacement measurement, are performed. Results show that the proposed approach can attain excellent accuracy compared with the analytical ones or the measurements using conventional transducers, and proves to deliver an innovative and low cost solution to structural displacement measurement.

Ji, Yunfeng

2010-04-01

367

Displacement structures and fast inversion formulas for q-adic Vandermonde-like matrices  

NASA Astrophysics Data System (ADS)

A new class of so-called q-adic Vandermonde-like matrices over an arbitrary nonalgebraically closed field is introduced. This class generalizes the ordinary Vandermonde-like matrices over the complex field. Three kinds of displacement structures and fast inversion formulas for this class of matrices are presented by using displacement structure theory method, which generalize some of the well-known results for confluent Vandermonde-like matrices in the closed field case.

Yang, Zhenghong; Hu, Yongjian

2005-04-01

368

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

369

Interferometric fiber optic displacement sensor  

DOEpatents

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

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

1995-01-01

370

Interferometric fiber optic displacement sensor  

DOEpatents

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

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

1999-01-01

371

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

372

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

373

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

374

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

375

Radiofrequency heating and magnetically induced displacement of dental magnetic attachments during 3.0 T MRI  

PubMed Central

Objective The aim of this study was to estimate the risk of injury from dental magnetic attachments due to their radiofrequency (RF) heating and magnetically induced displacement during 3.0 T MRI. Methods To examine the magnetic attachments, we adopted the American Society for Testing and Materials F2182-02a and F2052-06 standards in two MRI systems (Achieva 3.0 T Nova Dual; Philips, Tokyo, Japan, and Signa HDxt 3.0 T; GE Healthcare, Milwaukee, WI). The temperature change was measured in a cylindrical keeper (GIGAUSS D600; GC, Tokyo, Japan) with coping of the casting alloy and a keeper with a dental implant at the maximum specific absorption rate (SAR) for 20 min. To measure the magnetically induced displacement force, three sizes of keepers (GIGAUSS D400, D600 and D1000) were used in deflection angle tests conducted at the point of the maximum magnetic field strength. Results Temperature elevations of both coping and implant were higher in the Signa system than in the Achieva system. The highest temperature changes in the keeper with implant and keeper with coping were 0.6 °C and 0.8 °C in the Signa system, respectively. The temperature increase did not exceed 1.0 °C at any location. The deflection angle (?) was not measurable because it exceeded 90°. GIGAUSS D400 required an extra 3.0 g load to constrain the deflection angle to less than 45°; GIGAUSS D600 and D1000 required 5.0 and 9.0 g loads, respectively. Conclusions Dental magnetic attachments pose no risk due to RF heating and magnetically induced displacement at 3.0 T MRI. However, it is necessary to confirm that these keepers are securely attached to the prosthesis before imaging. PMID:22499128

Miyata, K; Hasegawa, M; Abe, Y; Tabuchi, T; Namiki, T; Ishigami, T

2012-01-01

376

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

377

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

378

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

379

Variable delivery, fixed displacement pump  

SciTech Connect

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

Sommars, Mark F. (Sparland, IL)

2001-01-01

380

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

381

Fiber optic multimode displacement sensor  

NASA Astrophysics Data System (ADS)

An underwater Optical Motion Sensor (OMS) based on a design first presented by W. B. Spillman, Schlieren multimode fiber-optic hydrophone, Applied Physics Letters 37(2), 15 July 1980, p. 145-146 is described. The displacement sensor uses the same acoustooptical intensity modulation mechanism as Spillman, however the sensing mechanism is isolated from the ambient fluid environment by a small cylindrical aluminum enclosure (1? OD×3/4?). The enclosure contains an inertial mass and the fiber collimators. The inertial mass is suspended in the center of the enclosure by three small wires rigidly mounted to the walls. The mass and wires act as a cantilever beam system with a mechanical resonance near 100 Hz. The transduction mechanism consists of two opposed optical gratings aligned and positioned between the fiber collimators. One grating is mounted on the inertial mass while the other is mounted on the lower end cap of the enclosure. Relative motion between the gratings causes a modulation of the light transmitted through the gratings. The modulated beam is focused onto a photodetector and converted to electric current. The frequency response is flat from 200 Hz-9 kHz with a minimum detectable displacement of 0.002 A and the dynamic range is 136 dB. The small size and light weight give the sensor an effective density of 1.08 g/cm3 making it almost neutrally buoyant in water. This in conjunction with the performance characteristics make this sensor suitable for use in acoustical sensing applications.

Fisher, Karl A.; Jarzynski, Jacek

1996-04-01

382

Interpretation of Light Scattering Spectra in Terms of Particle Displacements  

E-print Network

Quasi-elastic light scattering spectroscopy of dilute solutions of diffusing mesoscopic probe particles is regularly used to examine the dynamics of the fluid through which the probe particles are moving. For probes in a simple liquid, the light scattering spectrum is a simple exponential; the field correlation function $g^{(1)}_{P}(q,\\tau)$ of the scattering particles is related to their mean-square displacements $\\bar{X^{2}} \\equiv $ during $\\tau$ via $g^{(1)}(q,\\tau) = \\exp(- {1/2} q^{2} \\bar{X^{2}})$. However, historical demonstrations of this expression refer only to ideal Brownian particles in simple liquids, and show that if the form is correct then it is also true that $g^{(1)}(q,\\tau) = \\exp(- \\Gamma \\tau)$, a pure exponential in $\\tau$. In general, $g^{(1)}_{P}(q,\\tau)$ is not a single exponential in time. $g^{(1)}_{P}(q,\\tau)$ reflects not only the mean-square particle displacements but also all higher-order mean displacement moments $\\bar{X^{2n}}$. A correct general form for $g^{(1)}(q,\\tau)$, replacing the generally-incorrect $\\exp(- {1/2} q^{2} \\bar{X^{2}})$, is obtained. A simple experimental diagnostic determining when the field correlation function gives the mean-square displacements is identified, namely $g^{(1)}(q,\\tau)$ reveals $\\bar{X^{2}}$ if $g^{(1)}(q,\\tau)$ is exponential in $\\tau$.

George D. J. Phillies

2005-05-03

383

Testing fault displacement-length scaling relations through analogue modeling in an extensional setting  

NASA Astrophysics Data System (ADS)

The scaling relation between displacement and length of faults plays a crucial role in understanding the growth history of individual faults and their possible linkage and reactivation in future ruptures. Displacement-length relations are commonly based on empirical data. The measurement of fault geometric properties, however, is generally affected by large scattering due not only to intrinsic difficulties of making observations in natural cases (outcrop availability, seismic profiles), but also to the variety of geological factors that may affect the rupture patterns. These can be the interaction between the present-day tectonic regime and an inherited structural fabric, or that between a master fault at depth and shallow structural features. As an alternative to field observations, analogue modeling provides an opportunity to investigate the faulting processes in a controlled environment. During the last decade, the ability of scaled models to properly reproduce such geological processes has greatly improved thanks to the introduction of new materials (e.g. wet kaolin) suitable for reproducing brittle deformation in the upper crust and hi-tech monitoring systems (e.g. laser scanner, particle image velocimetry) with the ability of capturing structural details and performing accurate measurements. We use a dedicated apparatus with such properties to gain insights on the evolution of extensional faults through a suite of experiments which includes (a) setups in homogeneous material to test our ability in meeting general criteria related with fault displacement-length parameters; and (b) increasing complexities attained by inserting various pre-existing fault patterns to analyze how shallow mechanical discontinuities affect our ability to characterize a major fault at depth. Our results show that pre-existing faults can either halt or favor fault development and growth depending on their location/orientation with respect to the applied stress field and suggest the reappraisal of natural case studies under a different perspective.

Bonini, L.; Basili, R.; Burrato, P.; Kastelic, V.; Toscani, G.; Seno, S.; Valensise, G.

2013-12-01

384

Modelling Toehold-Mediated RNA Strand Displacement  

NASA Astrophysics Data System (ADS)

We study the thermodynamics and kinetics of an RNA toehold-mediated strand displacement reaction with a recently developed coarse-grained model of RNA. Strand displacement, during which a single strand displaces a different strand previously bound to a complementary substrate strand, is an essential mechanism in active nucleic acid nanotechnology and has also been hypothesized to occur in vivo. We study the rate of displacement reactions as a function of the length of the toehold and temperature and make two experimentally testable predictions: that the displacement is faster if the toehold is placed at the 5' end of the substrate and that the displacement slows down with increasing temperature for longer toeholds.

Šulc, Petr; Ouldridge, Thomas E.; Romano, Flavio; Doye, Jonathan P. K.; Louis, Ard A.

2015-03-01

385

Modelling toehold-mediated RNA strand displacement.  

PubMed

We study the thermodynamics and kinetics of an RNA toehold-mediated strand displacement reaction with a recently developed coarse-grained model of RNA. Strand displacement, during which a single strand displaces a different strand previously bound to a complementary substrate strand, is an essential mechanism in active nucleic acid nanotechnology and has also been hypothesized to occur in vivo. We study the rate of displacement reactions as a function of the length of the toehold and temperature and make two experimentally testable predictions: that the displacement is faster if the toehold is placed at the 5' end of the substrate; and that the displacement slows down with increasing temperature for longer toeholds. PMID:25762335

Šulc, Petr; Ouldridge, Thomas E; Romano, Flavio; Doye, Jonathan P K; Louis, Ard A

2015-03-10

386

Modelling toehold-mediated RNA strand displacement  

E-print Network

We study the thermodynamics and kinetics of an RNA toehold-mediated strand displacement reaction with a recently developed coarse-grained model of RNA. Strand displacement, during which a single strand displaces a different strand previously bound to a complementary substrate strand, is an essential mechanism in active nucleic acid nanotechnology and has also been hypothesized to occur in vivo. We study the rate of displacement reactions as a function of the length of the toehold and temperature and make two experimentally testable predictions: that the displacement is faster if the toehold is placed at the 5' end of the substrate and that the displacement slows down with increasing temperature for longer toeholds.

Petr Šulc; Thomas E. Ouldridge; Flavio Romano; Jonathan P. K. Doye; Ard A. Louis

2014-11-12

387

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

388

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

389

An improved displacement damage monitor LED  

Microsoft Academic Search

A frequency-domain technique for measuring carrier lifetime in GaAs light-emitting-diode (LED) displacement damage monitors capable of high sensitivity and repeatability is developed. Applications of this technique that take advantage of the high sensitivity of this method, including the measurement of the threshold energy for lattice displacement in GaAs, are described. The measured minimum electron energy for displacement damage was 270±15

A. L. Barry; R. Maxseiner; R. Wojcik; M. A. Briere; D. Braeunig

1990-01-01

390

Generating Sub-nanometer Displacement Using Reduction Mechanism Consisting of Torsional Leaf Spring Hinges  

NASA Astrophysics Data System (ADS)

Recent demand on the measurement resolution of precise positioning comes up to tens of picometers. Some distinguished researches have been performed to measure the displacement in picometer order, however, few of them can verify the measurement performance as available tools in industry. This is not only because the picometer displacement is not yet required for industrial use, but also due to the lack of standard tools to verify such precise displacement. We proposed a displacement reduction mechanism for generating precise displacement using torsional leaf spring hinges (TLSHs) that consist of four leaf springs arranged radially. It has been demonstrated that a prototype of the reduction mechanism was able to provide one-nanometer displacement with 1/1000 reduction rate by a piezoelectric actuator. In order to clarify the potential of the reduction mechanism, a displacement reduction table that can be mounted on AFM stage was newly developed using TLSHs. This paper describes the design of the reduction mechanism and the sub-nanometer displacement performance of the table obtained from its dynamic and static characteristics measured by displacement sensors and from the AFM images

Fukuda, Makoto; Hayashi, Masato; Marita, Sintaro

2014-02-01

391

The stress field in an edge cracked plate in antiplane deformation  

NASA Technical Reports Server (NTRS)

The antiplane strain problem of an edge cracked elastic plate subjected to a surface displacement load is solved, and the surface line loads are obtained using conformal mapping techniques. Results are presented for the yield, stress, strain and displacement distributions, and stress intensity factors in the plate. A superposition technique and Green's functions are used to determine the strain field on the upper plate surface due to arbitrarily applied tensile stress on the lower plate surface.

Li, V. C.; Lim, H. S.

1988-01-01

392

Quantum analysis of a linear DC SQUID mechanical displacement detector  

E-print Network

We provide a quantum analysis of a DC SQUID mechanical displacement detector within the sub-critical Josephson current regime. A segment of the SQUID loop forms the mechanical resonator and motion of the latter is transduced inductively through changes in the flux threading the loop. Expressions are derived for the detector signal response and noise, which are used to evaluate the position and force detection sensitivity. We also investigate cooling of the mechanical resonator due to back reaction noise from the detector.

M. P. Blencowe; E. Buks

2007-07-19

393

Three-dimensional coseismic displacements from point-like target tracking of high-resolution SAR images: Application to the 2011 Van (Turkey) earthquake  

NASA Astrophysics Data System (ADS)

The complete three-dimensional (3D) coseismic displacement field of earthquakes is important for constraining fault slip models. However, Interferometric Synthetic Aperture Radar (InSAR) only provides accurate measurements along the single Line-Of-Sight (LOS) direction, meaning that multiple observations need to be combined to derive the 3D displacement field. This is often achieved by including SAR Pixel-offset (PO) tracking, although less accurate, which can provide unambiguous displacement measurements of both the LOS and along-track (azimuth) directions. Today, X-band data from the COSMO-SkyMed (CSK) and TerraSAR-X (TSX) satellites are the main sources of InSAR data for geoscientific applications. X-band signals do however often decorrelate in a relatively short period because their limited penetration capability and short wavelength. Therefore, the formed interferograms are often unusable due to low coherence and/or aliasing fringes. The accuracy of PO tracking on the other hand has significantly improved because of meter-level pixel spacing of these X-band data. It is therefore useful to reconsider the role of PO tracking in measuring coseismic displacements in the context of high-resolution SAR images. Here, we show that by estimating pixel offsets we can obtain accurate 3D-displacement maps even if the corresponding interferograms are totally decorrelated. Using both ascending TerraSAR-X and descending COSMO-SkyMed images of the 2011 Van (Turkey) earthquake we first coregister the images. We then search for point-like targets and focus our azimuth and range offset estimation on sub-images containing identified targets. The offset measurements are spatially median-filtered before the range and azimuth offsets are combined to estimate the 3D displacement field. The results show strong uplift of the hanging wall with diverging horizontal displacements, as expected from this thrust-faulting earthquake. Our results indicate that point-like offset tracking of high-resolution SAR images can be used to measure coseismic displacement with the accuracy of several centimeters.

Wang, T.; Jonsson, S.

2013-12-01

394

Displacement based multilevel structural optimization  

NASA Technical Reports Server (NTRS)

Multidisciplinary design optimization (MDO) is expected to play a major role in the competitive transportation industries of tomorrow, i.e., in the design of aircraft and spacecraft, of high speed trains, boats, and automobiles. All of these vehicles require maximum performance at minimum weight to keep fuel consumption low and conserve resources. Here, MDO can deliver mathematically based design tools to create systems with optimum performance subject to the constraints of disciplines such as structures, aerodynamics, controls, etc. Although some applications of MDO are beginning to surface, the key to a widespread use of this technology lies in the improvement of its efficiency. This aspect is investigated here for the MDO subset of structural optimization, i.e., for the weight minimization of a given structure under size, strength, and displacement constraints. Specifically, finite element based multilevel optimization of structures (here, statically indeterminate trusses and beams for proof of concept) is performed. In the system level optimization, the design variables are the coefficients of assumed displacement functions, and the load unbalance resulting from the solution of the stiffness equations is minimized. Constraints are placed on the deflection amplitudes and the weight of the structure. In the subsystems level optimizations, the weight of each element is minimized under the action of stress constraints, with the cross sectional dimensions as design variables. This approach is expected to prove very efficient, especially for complex structures, since the design task is broken down into a large number of small and efficiently handled subtasks, each with only a small number of variables. This partitioning will also allow for the use of parallel computing, first, by sending the system and subsystems level computations to two different processors, ultimately, by performing all subsystems level optimizations in a massively parallel manner on separate processors. It is expected that the subsystems level optimizations can be further improved through the use of controlled growth, a method which reduces an optimization to a more efficient analysis with only a slight degradation in accuracy. The efficiency of all proposed techniques is being evaluated relative to the performance of the standard single level optimization approach where the complete structure is weight minimized under the action of all given constraints by one processor and to the performance of simultaneous analysis and design which combines analysis and optimization into a single step. It is expected that the present approach can be expanded to include additional structural constraints (buckling, free and forced vibration, etc.) or other disciplines (passive and active controls, aerodynamics, etc.) for true MDO.

Striz, Alfred G.

1995-01-01

395

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

396

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

397

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

398

Displacement and Knowledge Construction in Literature Reviews.  

ERIC Educational Resources Information Center

Two literature reviews are interpreted to demonstrate how they are informed by what the author labels the "displacement story," that is, a story of how one prevailing professional paradigm is replaced by another. This study demonstrates how the narration, structure, and language in each review render particular tellings of the displacement story.…

Steinley, Gary

399

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

400

Video Games, Adolescents, and the Displacement Effect  

ERIC Educational Resources Information Center

The displacement effect (the idea that time spent in one activity displaces time spent in other activities) was examined within the lens of adolescents' video game use and their time spent reading, doing homework, in physically active sports and activities, in creative play, and with parents and friends. Data were drawn from the Panel Study…

Fisher, Carla Christine

2012-01-01

401

Displaced Homemakers: Vo-Tech Workshop Guide.  

ERIC Educational Resources Information Center

Written for displaced homemaker programs in vocational-technical schools, this curriculum contains material designed so that instructors can prepare student manuals appropriate to almost any educational support situation for displaced homemakers. An overview provides information on special needs groups, curriculum use, and resources and sample…

Peltier, Wanda Jo

402

Drilling with new-generation positive displacement motors  

SciTech Connect

The paper describes a new generation of positive displacement downhole mud motors designed for long interval straight hole drilling with natural or man-made diamonds bits or with conventional three-cone rock bits. Field results have demonstrated that these motors are now cost-competitive with rotary drilling methods. The advantages of increased penetration, deviation control and reduced casing wear contribute to a lower cost per foot of hole drilled compared to rotary techniques. 3 refs.

Herbert, P.

1981-01-01

403

Drilling With New-Generation Positive Displacement Motors  

Microsoft Academic Search

The paper describes a new generation of positive displacement downhole mud motors designed for long interval straight hole drilling with natural or man-made diamonds bits or with conventional three-cone rock bits. Field results have demonstrated that these motors are now cost-competitive with rotary drilling methods. The advantages of increased penetration, deviation control and reduced casing wear contribute to a lower

Pat Herbert

1981-01-01

404

Using a 2D displacement sensor to derive 3D displacement information  

NASA Technical Reports Server (NTRS)

A 2D displacement sensor is used to measure displacement in three dimensions. For example, the sensor can be used in conjunction with a pulse-modulated or frequency-modulated laser beam to measure displacement caused by deformation of an antenna on which the sensor is mounted.

Soares, Schubert F. (Inventor)

2002-01-01

405

Patient-specific analysis of displacement forces acting on fenestrated stent grafts for endovascular aneurysm repair.  

PubMed

Treatment options for abdominal aortic aneurysm (AAA) include highly invasive open surgical repair or minimally invasive endovascular aneurysm repair (EVAR). Despite being minimally invasive, some patients are not suitable for EVAR due to hostile AAA morphology. Fenestrated-EVAR (F-EVAR) was introduced to address these limitations of standard EVAR, where AAA is treated using a Fenestrated Stent Graft (FSG). In order to assess durability of F-EVAR, displacement forces acting on FSGs were analysed in this study, based on patient-specific geometries reconstructed from computed tomography (CT) scans. The magnitude and direction of the resultant displacement forces acting on the FSG were numerically computed using computational fluid dynamics (CFD) with a rigid wall assumption. Although displacement force arises from blood pressure and friction due to blood flow, numerical simulations elucidated that net blood pressure is the dominant contributor to the overall displacement force; as a result, time dependence of the resultant displacement force followed pressure waveform very closely. The magnitude of peak displacement force varied from 1.9N to 14.3N with a median of 7.0N. A strong positive correlation was found between inlet cross-sectional area (CSA), anterior/posterior (A/P) angle and the peak displacement force i.e. as inlet CSA or A/P angle increases, the magnitude of resultant displacement increases. This study manifests that while loads exerted by the pulsatile flow dictates the cyclic variation of the displacement force, its magnitude depends not only on blood pressure but also the FSG morphology, with the latter determining the direction of the displacement force. PMID:25267572

Kandail, Harkamaljot; Hamady, Mohammad; Xu, Xiao Yun

2014-11-01

406

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

407

Lattice Boltzmann simulations of supercritical CO2-water drainage displacement in porous media: CO2 saturation and displacement mechanism.  

PubMed

CO2 geosequestration in deep aquifers requires the displacement of water (wetting phase) from the porous media by supercritical CO2 (nonwetting phase). However, the interfacial instabilities, such as viscous and capillary fingerings, develop during the drainage displacement. Moreover, the burstlike Haines jump often occurs under conditions of low capillary number. To study these interfacial instabilities, we performed lattice Boltzmann simulations of CO2-water drainage displacement in a 3D synthetic granular rock model at a fixed viscosity ratio and at various capillary numbers. The capillary numbers are varied by changing injection pressure, which induces changes in flow velocity. It was observed that the viscous fingering was dominant at high injection pressures, whereas the crossover of viscous and capillary fingerings was observed, accompanied by Haines jumps, at low injection pressures. The Haines jumps flowing forward caused a significant drop of CO2 saturation, whereas Haines jumps flowing backward caused an increase of CO2 saturation (per injection depth). We demonstrated that the pore-scale Haines jumps remarkably influenced the flow path and therefore equilibrium CO2 saturation in crossover domain, which is in turn related to the storage efficiency in the field-scale geosequestration. The results can improve our understandings of the storage efficiency by the effects of pore-scale displacement phenomena. PMID:25427299

Yamabe, Hirotatsu; Tsuji, Takeshi; Liang, Yunfeng; Matsuoka, Toshifumi

2015-01-01

408

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

409

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

410

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

NASA Astrophysics Data System (ADS)

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 10-6 accompanied by elevation change to elevation ratios of order 10-4. 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, David F.; Stein, Ross S.

1984-02-01

411

Two-dimensional simulations of displacement accumulation incorporating shear strain.  

PubMed

Using ultrasound images to track large tissue deformations usually requires breaking up the deformation into steps and then summing the resulting displacement estimates. The accumulated displacement estimation error therefore depends not only on the error in each step but also on the statistical relationships between estimation steps. These relationships have not been thoroughly studied. Building on previous work with one-dimensional (1-D) simulations, the work reported here measured error variance for single-step and accumulated displacement estimates using two-dimensional (2-D) numerical simulations of ultrasound echo signals, subjected to both normal and axial shear strain as well as electronic noise. Previous results from 1-D simulations were confirmed, showing that errors due to electronic noise are negatively correlated between steps and accumulate slowly, while errors due to strain are positively correlated and accumulate quickly. These properties hold for both normal and axial shear strain. An analysis of 2-D kernel size for tissue under normal and axial shear strain was also performed. Under axial shear strain, error variance tends to increase with larger lateral kernel sizes but decrease for larger axial kernel sizes; the opposite relationship holds under normal strain. A combination of these two types of strain limits the practical kernel size in both dimensions. PMID:24275539

Bayer, Matthew; Hall, Timothy J; Neves, Lucio P; Carneiro, A A O

2014-01-01

412

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

413

Probing Baryogenesis with Displaced Vertices at the LHC  

E-print Network

The generation of the asymmetric cosmic baryon abundance requires a departure from thermal equilibrium in the early universe. In a large class of baryogenesis models, the baryon asymmetry results from the out-of-equilibrium decay of a new, massive particle. We highlight that in the interesting scenario where this particle has a weak scale mass, this out-of-equilibrium condition requires a proper decay length larger than O(1) mm. Such new fields are within reach of the LHC, at which they can be pair produced leaving a distinctive, displaced-vertex signature. This scenario is realized in the recently proposed mechanism of baryogenesis where the baryon asymmetry is produced through the freeze-out and subsequent decay of a meta-stable weakly interacting massive particle ("WIMP baryogenesis"). In analogy to missing energy searches for WIMP dark matter, the LHC is an excellent probe of these new long-lived particles responsible for baryogenesis via the low-background displaced vertex channel. In our paper, we estimate the limits on simplified models inspired by WIMP baryogenesis from two of the most sensitive collider searches by CMS and ATLAS with 8 TeV LHC data. We also estimate the LHC reach at 13 TeV using current strategies, and demonstrate that up to a factor of 100 improvement in cross-section limits can be achieved by requiring two displaced vertices while lowering kinematic thresholds. For meta-stable WIMPs produced through electroweak interactions, the high luminosity LHC is sensitive to masses up to 2.5 TeV for lifetimes around 1 cm, while for singlets pair-produced through the off-shell-Higgs portal, the LHC is sensitive to production cross sections of O(10) ab for benchmark masses around 150 GeV. Our analysis and proposals also generally apply to displaced vertex signatures from other new physics such as hidden valley models, twin Higgs models and displaced supersymmetry.

Yanou Cui; Brian Shuve

2015-01-06

414

Probing baryogenesis with displaced vertices at the LHC  

NASA Astrophysics Data System (ADS)

The generation of the asymmetric cosmic baryon abundance requires a departure from thermal equilibrium in the early universe. In a large class of baryogenesis models, the baryon asymmetry results from the out-of-equilibrium decay of a new, massive particle. We highlight that in the interesting scenario where this particle has a weak scale mass, this out-of-equilibrium condition requires a proper decay length larger than O(1) mm. Such new fields are within reach of the LHC, at which they can be pair produced leaving a distinctive, displaced-vertex signature. This scenario is realized in the recently proposed mechanism of baryogenesis where the baryon asymmetry is produced through the freeze-out and subsequent decay of a meta-stable weakly interacting massive particle ("WIMP baryogenesis"). In analogy to missing energy searches for WIMP dark matter, the LHC is an excellent probe of these new long-lived particles responsible for baryogenesis via the low-background displaced vertex channel. In our paper, we estimate the limits on simplified models inspired by WIMP baryogenesis from two of the most sensitive collider searches by CMS and ATLAS with 8 TeV LHC data. We also estimate the LHC reach at 13 TeV using current strategies, and demonstrate that up to a factor of 100 improvement in cross-section limits can be achieved by requiring two displaced vertices while lowering kinematic thresholds. For meta-stable WIMPs produced through electroweak interactions, the high luminosity LHC is sensitive to masses up to 2.5 TeV for lifetimes around 1 cm, while for singlets pair-produced through the off-shell-Higgs portal, the LHC is sensitive to production cross sections of O(10) ab for benchmark masses around 150 GeV. Our analysis and proposals also generally apply to displaced vertex signatures from other new physics such as hidden valley models, twin Higgs models and displaced supersymmetry.

Cui, Yanou; Shuve, Brian

2015-02-01

415

Dynamically Induced Displacements of a Persistent Cold-Air Pool  

NASA Astrophysics Data System (ADS)

We examine the influence of a passing weather system on a persistent cold-air pool (CAP) during the Persistent Cold-Air Pool Study in the Salt Lake Valley, Utah, USA. The CAP experiences a sequence of along-valley displacements that temporarily and partially remove the cold air in response to increasing along-valley winds aloft. The displacements are due to the formation of a mountain wave over the upstream topography as well as adjustments to the regional horizontal pressure gradient and wind-stress divergence acting on the CAP. These processes appear to help establish a balance wherein the depth of the CAP increases to the north. When that balance is disrupted, the CAP tilt collapses, which sends a gravity current of cold air travelling upstream and thereby restores CAP conditions throughout the valley. Intra-valley mixing of momentum, heat, and pollution within the CAP by Kelvin-Helmholtz waves and seiching is also examined.

Lareau, Neil P.; Horel, John D.

2015-02-01

416

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

417

Intrinsic Noise Properties of Atomic Point Contact Displacement Detectors  

NASA Astrophysics Data System (ADS)

By coupling an atomic point contact (APC) to a nanomechanical beam, we measure the noise properties of an APC, an object which is the basis of scanning tunneling microscopy and is used to create electrical contact to single molecules. Using a microwave technique, we detect the resonant motion of the nanomechanical beam at frequencies up to 200 MHz. This measurement is sensitive enough to observe the random thermal motion of the nanomechanical beam at 250 mK. We use this thermal motion to evaluate the noise properties of the APC, demonstrating a displacement imprecision limited by the shot-noise in the number of electrons that tunnel across the APC and observing the force due to measurement backaction. Together, the imprecision and backaction yield a total uncertainty in the beam's displacement that is 42 times the standard quantum limit. In addition, we detect the beam's response to piezoelectric, electric, and magnetic forces, and use feedback to ``squash'' the shot-noise.

Flowers-Jacobs, N. E.; Lehnert, K. W.

2007-03-01

418

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

419

Time?dependent displacement of diaphragm wall induced by soil creep  

Microsoft Academic Search

This paper presents the time?dependent performance of an well?instrumented excavation case using the top?down construction method. Studies show that this time?dependent wall displacement is mostly likely due to undrained creep of clayey soils surrounding the excavation. In other words, soil creep may make significant contributions to diaphragm wall displacement and ground settlement in a deep excavation project in soft clay

2002-01-01

420

Theory of multicomponent gas/oil displacements  

SciTech Connect

Chromatographic separations that occur during two-phase flow in a porous medium are analyzed for one-dimensional, dispersion-free displacement of a liquid hydrocarbon mixture (oil) by a vapor phase mixture (gas). The authors show that displacement behavior is controlled by a set of key equilibrium the lines, all of which are determined by geometric constructions in composition space: two of the key tie lines are those that extend through the initial oil and injection gas compositions, and the remainder are tie lines that are located at intersections of ruled surfaces of tie lines. Very efficient displacement of oil by gas results if any of the key tie lines is a critical tie line. That high displacement efficiency is the basis of so-called miscible gas injection processes for enhanced oil recovery.

Orr, F.M. Jr.; Dindoruk, B.; Johns, R.T. [Stanford Univ., CA (United States). Dept. of Petroleum Engineering

1995-08-01

421

Air Emissions and Oil Displacement Benefits  

E-print Network

may (1) produce fewer greenhouse gas emissions when powered by electricity instead of gasoline gasoline prices, low- emissAir Emissions and Oil Displacement Benefits from Plug-in Vehicles The electrification of passenger

Michalek, Jeremy J.

422

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

423

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

424

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

425

Theory of multicomponent gas\\/oil displacements  

Microsoft Academic Search

Chromatographic separations that occur during two-phase flow in a porous medium are analyzed for one-dimensional, dispersion-free displacement of a liquid hydrocarbon mixture (oil) by a vapor phase mixture (gas). The authors show that displacement behavior is controlled by a set of key equilibrium the lines, all of which are determined by geometric constructions in composition space: two of the key

Franklin M. Orr; Birol Dindoruk; Russell T. Johns

1995-01-01

426

Viral fitness does not correlate with three genotype displacement events involving infectious hematopoietic necrosis virus  

USGS Publications Warehouse

Viral genotype displacement events are characterized by the replacement of a previously dominant virus genotype by a novel genotype of the same virus species in a given geographic region. We examine here the fitness of three pairs of infectious hematopoietic necrosis virus (IHNV) genotypes involved in three major genotype displacement events in Washington state over the last 30 years to determine whether increased virus fitness correlates with displacement. Fitness was assessed using in vivo assays to measure viral replication in single infection, simultaneous co-infection, and sequential superinfection in the natural host, steelhead trout. In addition, virion stability of each genotype was measured in freshwater and seawater environments at various temperatures. By these methods, we found no correlation between increased viral fitness and displacement in the field. These results suggest that other pressures likely exist in the field with important consequences for IHNV evolution.

Kell, Alison M.; Wargo, Andrew R.; Kurath, Gael

2014-01-01

427

40 CFR 86.419-78 - Engine displacement, motorcycle classes.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Engine displacement, motorcycle classes. 86.419-78...Provisions § 86.419-78 Engine displacement, motorcycle classes. (a)(1) Engine displacement shall be calculated using...

2010-07-01

428

24 CFR 882.810 - Displacement, relocation, and acquisition.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Displacement, relocation, and acquisition...Homeless Individuals § 882.810 Displacement, relocation, and acquisition. (a) Minimizing displacement. (1) Consistent with the...

2011-04-01

429

40 CFR 86.419-2006 - Engine displacement, motorcycle classes.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Engine displacement, motorcycle classes. 86.419-2006...Provisions § 86.419-2006 Engine displacement, motorcycle classes. (a)(1) Engine displacement shall be calculated using...

2011-07-01

430

24 CFR 583.310 - Displacement, relocation, and acquisition.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Displacement, relocation, and acquisition...Program Requirements § 583.310 Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the other...

2010-04-01

431

20 CFR 218.30 - Separation, displacement or dismissal allowance.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Separation, displacement or dismissal allowance. 218.30...Beginning Date § 218.30 Separation, displacement or dismissal allowance. (a) General...an employee receives a separation, displacement or dismissal allowance from...

2011-04-01

432

7 CFR 1944.667 - Relocation and displacement.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 true Relocation and displacement. 1944.667 Section 1944.667...Grants § 1944.667 Relocation and displacement. (a) Relocation. ...costs proposed to be allowed. (b) Displacement. The applicant shall include...

2010-01-01

433

24 CFR 886.138 - Displacement, relocation, and acquisition.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Displacement, relocation, and acquisition...HUD-Held Mortgages § 886.138 Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the other...

2011-04-01

434

10 CFR 590.209 - Exchanges by displacement.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Exchanges by displacement. 590.209 Section 590.209...Gas § 590.209 Exchanges by displacement. Any importer of natural gas may enter into an exchange by displacement agreement without the...

2010-01-01

435

40 CFR 86.419-78 - Engine displacement, motorcycle classes.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Engine displacement, motorcycle classes. 86.419-78...Provisions § 86.419-78 Engine displacement, motorcycle classes. (a)(1) Engine displacement shall be calculated using...

2011-07-01

436

24 CFR 92.353 - Displacement, relocation, and acquisition.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Displacement, relocation, and acquisition...Federal Requirements § 92.353 Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the other...

2011-04-01

437

24 CFR 583.310 - Displacement, relocation, and acquisition.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2010-04-01 true Displacement, relocation, and acquisition...Program Requirements § 583.310 Displacement, relocation, and acquisition. (a) Minimizing displacement. Consistent with the other...

2011-04-01

438

40 CFR 86.419-2006 - Engine displacement, motorcycle classes.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Engine displacement, motorcycle classes. 86.419-2006...Provisions § 86.419-2006 Engine displacement, motorcycle classes. (a)(1) Engine displacement shall be calculated using...

2010-07-01

439

7 CFR 1944.667 - Relocation and displacement.  

Code of Federal Regulations, 2011 CFR

...2009-01-01 true Relocation and displacement. 1944.667 Section 1944.667...Grants § 1944.667 Relocation and displacement. (a) Relocation. ...costs proposed to be allowed. (b) Displacement. The applicant shall include...

2011-01-01

440

10 CFR 590.209 - Exchanges by displacement.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 false Exchanges by displacement. 590.209 Section 590.209...Gas § 590.209 Exchanges by displacement. Any importer of natural gas may enter into an exchange by displacement agreement without the...

2011-01-01