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1

Large atomic displacements associated with the nitrogen antisite in GaN T. Mattila*  

E-print Network

techniques has led to a dramatic improvement in the quality of samples. The difficulty in obtaining p-type GaNLarge atomic displacements associated with the nitrogen antisite in GaN T. Mattila* Laboratory of an extensive theoretical study of the nitrogen antisite in GaN. The neutral antisite in c-GaN is reported

2

Large displacement spherical joint  

DOEpatents

A new class of spherical joints has a very large accessible full cone angle, a property which is beneficial for a wide range of applications. Despite the large cone angles, these joints move freely without singularities.

Bieg, Lothar F. (Albuquerque, NM); Benavides, Gilbert L. (Albuquerque, NM)

2002-01-01

3

Estimation of optical flow for large displacements  

Microsoft Academic Search

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

Torsten Radtke; Horst Salzwedel

2001-01-01

4

Frictional behavior of large displacement experimental faults  

USGS Publications Warehouse

The coefficient of friction and velocity dependence of friction of initially bare surfaces and 1-mm-thick simulated fault gouges (400 mm at 25??C and 25 MPa normal stress. Steady state negative friction velocity dependence and a steady state fault zone microstructure are achieved after ???18 mm displacement, and an approximately constant strength is reached after a few tens of millimeters of sliding on initially bare surfaces. Simulated fault gouges show a large but systematic variation of friction, velocity dependence of friction, dilatancy, and degree of localization with displacement. At short displacement (<10 mm), simulated gouge is strong, velocity strengthening and changes in sliding velocity are accompanied by relatively large changes in dilatancy rate. With continued displacement, simulated gouges become progressively weaker and less velocity strengthening, the velocity dependence of dilatancy rate decreases, and deformation becomes localized into a narrow basal shear which at its most localized is observed to be velocity weakening. With subsequent displacement, the fault restrengthens, returns to velocity strengthening, or to velocity neutral, the velocity dependence of dilatancy rate becomes larger, and deformation becomes distributed. Correlation of friction, velocity dependence of friction and of dilatancy rate, and degree of localization at all displacements in simulated gouge suggest that all quantities are interrelated. The observations do not distinguish the independent variables but suggest that the degree of localization is controlled by the fault strength, not by the friction velocity dependence. The friction velocity dependence and velocity dependence of dilatancy rate can be used as qualitative measures of the degree of localization in simulated gouge, in agreement with previous studies. Theory equating the friction velocity dependence of simulated gouge to the sum of the friction velocity dependence of bare surfaces and the velocity dependence of dilatancy rate of simulated gouge fails to quantitatively account for the experimental observations.

Beeler, N. M.; Tullis, T. E.; Blanpied, M. L.; Weeks, J. D.

1996-01-01

5

Use of Atomic Displacement Parameters in Thermoelectric Materials Research  

Microsoft Academic Search

Progress in thermoelectrics requires new materials, and finding new materials requires new ideas and new guidelines for materials selection. Most of the present chapter is devoted to explaining how a particular piece of crystallographic information—atomic displacement parameters (ADPs)—can be used to identify materials with an extremely low lattice thermal conductivity. Before launching into an exposition of this new guideline, however,

Brian C. Sales; David Mandrus; Bryan C. Chakoumakos

6

ELECTROTHERMAL SCS MICROMIRROR WITH LARGE-VERTICAL-DISPLACEMENT ACTUATION  

E-print Network

the mirror plate to remain parallel to the substrate surface, while still taking advantage of the largeELECTROTHERMAL SCS MICROMIRROR WITH LARGE-VERTICAL-DISPLACEMENT ACTUATION Ankur Jain, Hongwei Qu a vertical displacement of 0.2 mm at an actuation voltage of 6 V d.c. This device can also perform

Bowers, John

7

Displacement and deformation measurement for large structures by camera network  

NASA Astrophysics Data System (ADS)

A displacement and deformation measurement method for large structures by a series-parallel connection camera network is presented. By taking the dynamic monitoring of a large-scale crane in lifting operation as an example, a series-parallel connection camera network is designed, and the displacement and deformation measurement method by using this series-parallel connection camera network is studied. The movement range of the crane body is small, and that of the crane arm is large. The displacement of the crane body, the displacement of the crane arm relative to the body and the deformation of the arm are measured. Compared with a pure series or parallel connection camera network, the designed series-parallel connection camera network can be used to measure not only the movement and displacement of a large structure but also the relative movement and deformation of some interesting parts of the large structure by a relatively simple optical measurement system.

Shang, Yang; Yu, Qifeng; Yang, Zhen; Xu, Zhiqiang; Zhang, Xiaohu

2014-03-01

8

Large-displacement strain theory and its application to graphene  

NASA Astrophysics Data System (ADS)

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

Crosse, J. A.

2014-07-01

9

Quantum phonon optics: Coherent and squeezed atomic displacements Xuedong Hu and Franco Nori  

E-print Network

phonons can then be manipulated by the above- mentioned devices, just as in geometric optics. Phonons canQuantum phonon optics: Coherent and squeezed atomic displacements Xuedong Hu and Franco Nori of phonons. The latter allow the possibility of modu- lating the quantum fluctuations of atomic displacements

Nori, Franco

10

Calculations of dynamical properties of skutterudites: thermal conductivity, thermal expansivity and atomic mean square displacement  

SciTech Connect

While the thermal conductivity of the filled skutterudites has been of great interest it had not been calculated within a microscopic theory. Here a central force, Guggenheim-McGlashen, model with parameters largely extracted from first-principles calculations and from spectroscopic data, specific to LaFe{sub 4}Sb{sub 12} or CoSb{sub 3}, is employed in a Green-Kubo/molecular dynamics calculation of thermal conductivity as a function of temperature. We find that the thermal conductivity of a filled solid is more than a factor of two lower than that of an unfilled solid, assuming the 'framework' interatomic force parameters are the same between filled and unfilled solids, and that this decrease is almost entirely due to the cubic anharmonic interaction between filling and framework atoms. In addition, partially as a test of our models, we calculate thermal expansivity and isotropic atomic mean-square displacements using both molecular dynamics and lattice dynamics methods. These quantities are in reasonable agreement with experiment, increasing our confidence in the anharmonic parameters of our models. We also find an anomalously large filling-atom mode Gruneisen parameter that is apparently observed for a filled skutterudite and is observed in a clathrate.

Bernstein, Noam [Naval Research Laboratory, Washington, D.C.; Feldman, J. L. [Naval Research Laboratory, Washington, D.C.; Singh, David J [ORNL

2010-01-01

11

Calculations of dynamical properties of skutterudites: Thermal conductivity, thermal expansivity, and atomic mean-square displacement  

SciTech Connect

While the thermal conductivity of the filled skutterudites has been of great interest it had not been calculated within a microscopic theory. Here a central force, Guggenheim-McGlashen, model with parameters largely extracted from first-principles calculations and from spectroscopic data, specific to LaFe{sub 4} Sb{sub 12} or CoSb{sub 3} , is employed in a Green-Kubo/molecular dynamics calculation of thermal conductivity as a function of temperature. We find that the thermal conductivity of a filled solid is more than a factor of two lower than that of an unfilled solid, assuming the “framework” interatomic force parameters are the same between filled and unfilled solids, and that this decrease is almost entirely due to the cubic anharmonic interaction between filling and framework atoms. In addition, partially as a test of our models, we calculate thermal expansivity and isotropic atomic mean-square displacements using both molecular dynamics and lattice dynamics methods. These quantities are in reasonable agreement with experiment, increasing our confidence in the anharmonic parameters of our models. We also find an anomalously large filling-atom mode Gruneisen parameter that is apparently observed for a filled skutterudite and is observed in a clathrate.

Bernstein, N.; Feldman, J. L.; Singh, David J.

2010-01-01

12

Note: Seesaw actuation of atomic force microscope probes for improved imaging bandwidth and displacement range  

SciTech Connect

The authors describe a method of actuation for atomic force microscope (AFM) probes to improve imaging speed and displacement range simultaneously. Unlike conventional piezoelectric tube actuation, the proposed method involves a lever and fulcrum ''seesaw'' like actuation mechanism that uses a small, fast piezoelectric transducer. The lever arm of the seesaw mechanism increases the apparent displacement range by an adjustable gain factor, overcoming the standard tradeoff between imaging speed and displacement range. Experimental characterization of a cantilever holder implementing the method is provided together with comparative line scans obtained with contact mode imaging. An imaging bandwidth of 30 kHz in air with the current setup was demonstrated.

Torun, H. [Department of Electrical and Electronics Engineering, Bogazici University, Bebek, TR-34342 Istanbul (Turkey); Torello, D.; Degertekin, F. L. [G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

2011-08-15

13

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

14

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

15

Use of Atomic Force Microscopy Force Measurements To Monitor Citrate Displacement by Amines on Gold in  

E-print Network

Use of Atomic Force Microscopy Force Measurements To Monitor Citrate Displacement by Amines on Gold-(dimethylamino)pyridine and pyridine, in aqueous solution, onto trisodium citrate equilibrated gold has been monitored by the decrease in the electrostatic potential of the gold surface with time. Pronounced changes

Chan, Derek Y C

16

On Atomic Displacements in 90° Ferroelectric Domain Walls of Tetragonal BaTiO3 Crystals  

Microsoft Academic Search

The displacement field of atoms in 90° ferroelectric domain walls of tetragonal BaTiO3 is examined by symmetry analysis. Results illustrate advantages and limitations of this approach and demonstrate microscopic features of unusual asymmetric and irreversible domain walls.

V. JANOVEC; M. GROCKÝ; V. KOPSKÝ; Z. KLUIBER

2004-01-01

17

Measurement of transient atomic displacements in thin films with picosecond and femtometer resolution  

E-print Network

resolution extending down to 15 ps, transient changes in the diffraction angle are recorded. These changesMeasurement of transient atomic displacements in thin films with picosecond and femtometer of the transient structural response of weakly photo- excited thin films of BiFeO3, Pb(Zr,Ti)O3, and Bi and time

18

A statistical analysis of the lateral displacement of Si atoms in molecular dynamics simulations of successive bombardment with 20-keV C 60 projectiles  

NASA Astrophysics Data System (ADS)

An important factor that determines the possible lateral resolution in sputter depth profiling experiments is ion induced lateral displacement of substrate atoms. Molecular dynamics (MD) simulations are performed to model the successive bombardment of Si with 20 keV C60 at normal incidence. A statistical analysis of the lateral displacement of atoms that originate from the topmost layer is presented and discussed. From these results, it is determined that the motion is isotropic and can be described mathematically by a simple diffusion equation. A “diffusion coefficient” for lateral displacement is determined to be 3.5 Å2/impact. This value can be used to calculate the average lateral distance moved as a function of the number of impacts. The maximum distance an atom may move is limited by the time that it remains on the surface before it is sputtered. After 800 impacts, 99% of atoms from the topmost layer have been removed, and the average distance moved by these atoms is predicted to be 100 Å. Although the behavior can be described mathematically by the diffusion equation, the behavior of the atoms is different than what is thought of as normal diffusion. Atoms are displaced a large distance due to infrequent large hops.

Krantzman, K. D.; Cook, E. L.; Wucher, A.; Garrison, B. J.

2011-07-01

19

The radial loading of cylindrical vessels—influence of large displacements  

Microsoft Academic Search

This paper examines the behaviour of cylindrical vessels when local radial loads are uniformly applied in both the inward and outward direction. A parametric study is conducted to examine the effect of large displacements on the maximum stresses and displacements which occur in the vessel. Finally a design method is proposed which combines the results obtained for different attachment rigidities1

C. Nadarajah; A. S. Tooth; J. Spence

1996-01-01

20

Polar atomic displacements in multiferroics observed via anomalous x-ray diffraction  

NASA Astrophysics Data System (ADS)

The minute polar atomic displacements in multiferroics are shown to be within the reach of crystallography. A nonconventional methodology with anomalous x-ray diffraction is employed to investigate such displacements in DyMn2O5 with giant magnetoelectric coupling and two distinct Mn3+ and Mn4+ sites. Intensity differences of a selected Bragg reflection were measured as the direction of electric polarization is switched by a poling field. A significant differential effect, which is strongly enhanced at energies near and above the MnK edge, was observed near and below the ferroelectric transition temperature, Tc˜40K . The direct participation of ionic displacements in the ferroelectric polarization, particularly the Mn3+ sublattice, is demonstrated, dismissing a purely electronic mechanism for the multiferroicity.

Azimonte, C.; Granado, E.; Terashita, H.; Park, S.; Cheong, S.-W.

2010-01-01

21

Diffuse scattering measurements of static atomic displacements in crystalline binary solid solutions  

SciTech Connect

Diffuse x-ray scattering from crystalline solid solutions is sensitive to both local chemical order and local bond distances. In short-range ordered alloys, fluctuations of chemistry and bond distances break the long-range symmetry of the crystal within a local region and contribute to the total energy of the alloy. Recent use of tunable synchrotron radiation to change the x-ray scattering contrast between elements has greatly advanced the measurement of bond distances between the three kinds of atom pairs found in crystalline binary alloys. The estimated standard deviation on these recovered static displacements approaches {+-}0.001 {angstrom} (0.0001 nm) which is an order of magnitude more precise than obtained with EXAFS. In addition, both the radial and tangential displacements can be recovered to five near neighbors and beyond. These static displacement measurements provide new information which challenges the most advanced theoretical models of binary crystalline alloys. 29 refs., 8 figs., 2 tabs.

Ice, G.E.; Sparks, C.J.; Jiang, X.; Robertson, L.

1997-09-01

22

Improved calculation of displacements per atom cross section in solids by gamma and electron irradiation  

NASA Astrophysics Data System (ADS)

Several authors had estimated the displacements per atom cross sections under different approximations and models, including most of the main gamma- and electron-material interaction processes. These previous works used numerical approximation formulas which are applicable for limited energy ranges. We proposed the Monte Carlo assisted Classical Method (MCCM), which relates the established theories about atom displacements to the electron and positron secondary fluence distributions calculated from the Monte Carlo simulation. In this study the MCCM procedure is adapted in order to estimate the displacements per atom cross sections for gamma and electron irradiation. The results obtained through this procedure are compared with previous theoretical calculations. An improvement in about 10-90% for the gamma irradiation induced dpa cross section is observed in our results on regard to the previous evaluations for the studied incident energies. On the other hand, the dpa cross section values produced by irradiation with electrons are improved by our calculations in about 5-50% when compared with the theoretical approximations. When thin samples are irradiated with electrons, more precise results are obtained through the MCCM (in about 20-70%) with respect to the previous studies.

Piñera, Ibrahin; Cruz, Carlos M.; Leyva, Antonio; Abreu, Yamiel; Cabal, Ana E.; Espen, Piet Van; Remortel, Nick Van

2014-11-01

23

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

24

Stratification of welding fumes and grinding particles in a large factory hall equipped with displacement ventilation.  

PubMed

The purpose of the study was to investigate the performance of displacement ventilation in a large factory hall where large components of stainless steel for paper, pulp and chemical industries were manufactured. The performance of displacement ventilation was evaluated in terms of concentration distributions of welding fumes and grinding particles, flow field of the supply air and temperature distributions. Large differences in vertical stratification patterns between hexavalent chromium (Cr(VI)) and other particulate contaminants were observed. The concentration of Cr(VI) was notably lower in the zone of occupancy than in the upper part of the factory hall, whereas the concentrations of total airborne particles and trivalent chromium (Cr(III)) were higher in the occupied zone than in the upper zone. The stratification of Cr(VI) had the same tendency as the air temperature stratification caused by the displacement flow field. PMID:11513796

Niemelä, R; Koskela, H; Engström, K

2001-08-01

25

Characterizing absolute piezoelectric microelectromechanical system displacement using an atomic force microscope  

NASA Astrophysics Data System (ADS)

Piezoresponse Force Microscopy (PFM) is a popular tool for the study of ferroelectric and piezoelectric materials at the nanometer level. Progress in the development of piezoelectric MEMS fabrication is highlighting the need to characterize absolute displacement at the nanometer and Ångstrom scales, something Atomic Force Microscopy (AFM) might do but PFM cannot. Absolute displacement is measured by executing a polarization measurement of the ferroelectric or piezoelectric capacitor in question while monitoring the absolute vertical position of the sample surface with a stationary AFM cantilever. Two issues dominate the execution and precision of such a measurement: (1) the small amplitude of the electrical signal from the AFM at the Ångstrom level and (2) calibration of the AFM. The authors have developed a calibration routine and test technique for mitigating the two issues, making it possible to use an atomic force microscope to measure both the movement of a capacitor surface as well as the motion of a micro-machine structure actuated by that capacitor. The theory, procedures, pitfalls, and results of using an AFM for absolute piezoelectric measurement are provided.

Evans, J.; Chapman, S.

2014-08-01

26

A Rapidly Prototyped 2-Axis Positioning Stage for Microassembly Using Large Displacement  

E-print Network

A Rapidly Prototyped 2-Axis Positioning Stage for Microassembly Using Large Displacement Compliant with a rapid prototyping system that is flexible enough to automatically manufacture such devices in a cost assembly and rapid prototyping of sub-centimeter scale robots and mechatronic devices including structural

Fearing, Ron

27

NOVEL ELECTROTHERMAL BIMORPH ACTUATOR FOR LARGE OUT-OF-PLANE DISPLACEMENT AND FORCE  

E-print Network

of polymer layers and stiff plates placed in parallel after each other. When a thin polymer layer is bondedNOVEL ELECTROTHERMAL BIMORPH ACTUATOR FOR LARGE OUT-OF-PLANE DISPLACEMENT AND FORCE J. Wei, T. Chu for out-of-plane actuation that exploits the polymer constraint effect. The proposed concept is capable

Technische Universiteit Delft

28

The Impact of Accretionary Prism Heterogeneity on Seafloor Displacement during Large Subduction Zone Earthquakes  

NASA Astrophysics Data System (ADS)

Large earthquakes often occur in sediment dominated subduction zones where large accretionary prisms have formed. Deformation within the prism creates heterogeneity that can be very difficult to incorporate into models of rupture and coseismic seafloor deformation. Finite element modeling was used to assess the impact of prism heterogeneity on coseismic seafloor displacement. The modeling was based on information from the Nankai Trough subduction zone, where a large splay fault system (the megasplay) carries older sediments over younger, less consolidated sediments. This region is being investigated as part of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE). The major fault zones were incorporated into the model as frictional contacts. Different frictional properties were assigned to the deep portion of the plate boundary fault, the shallow portion of the plate boundary fault, and the megasplay fault. To simulate the earthquake cycle, a lower coefficient of friction was applied to the deep portion of the megathrust during the earthquake than during the interseismic period. This approach allowed stress to build up in the model region prior to the earthquake. Seafloor displacement was compared for simulations with a homogeneous prism and for simulations in which the splay fault's footwall was weaker than the hanging wall. The weaker footwall resulted in greater horizontal seafloor displacement but less vertical displacement than the homogeneous case. This difference in seafloor deformation may have implications for tsunami hazards.

Screaton, E.; Ge, S.; Regueiro, R.

2010-12-01

29

A spongy graphene based bimorph actuator with ultra-large displacement towards biomimetic application.  

PubMed

Bimorph actuators, consisting of two layers with asymmetric expansion and generating bending displacement, have been widely researched. Their actuation performances greatly rely on the difference of coefficients of thermal expansion (CTE) between the two material layers. Here, by introducing a spongy graphene (sG) paper with a large negative CTE as well as high electrical-to-thermal properties, an electromechanical sG/PDMS bimorph actuator is designed and fabricated, showing an ultra-large bending displacement output under low voltage stimulation (curvature of about 1.2 cm(-1) at 10 V for 3 s), a high displacement-to-length ratio (?0.79), and vibration motion at AC voltage (up to 10 Hz), which is much larger and faster than that of the other electromechanical bimorph actuators. Based on the sG/PDMS bimorph serving as the "finger", a mechanical gripper is constructed to realize the fast manipulation of the objects under 0.1 Hz square wave voltage stimulation (0-8 V). The designed bimorph actuator coupled with ultra-large bending displacement, low driven voltage, and the ease of fabrication may open up substantial possibilities for the utilization of electromechanical actuators in practical biomimetic device applications. PMID:25220910

Hu, Ying; Lan, Tian; Wu, Guan; Zhu, Zicai; Chen, Wei

2014-10-01

30

Development of steel dampers for bridges to allow large displacement through a vertical free mechanism  

NASA Astrophysics Data System (ADS)

Isolation bearings and dampers are often installed between piers and superstructures to reduce the seismic responses of bridges under large earthquakes. This paper presents a novel steel damper for bridges. The damper employs steel plates as energy dissipation components, and adopts a vertical free mechanism to achieve a large deformation capacity. Quasi-static tests using displacement-controlled cyclic loading and numerical analyses using a finite element program called ABAQUS are conducted to investigate the behavior of the damper, and a design methodology is proposed based on the tests and numerical analyses. Major conclusions obtained from this study are as follows: (1) the new dampers have stable hysteresis behavior under large displacements; (2) finite element analyses are able to simulate the behavior of the damper with satisfactory accuracy; and (3) simplified design methodology of the damper is effective.

Pan, Peng; Yan, Hong; Wang, Tao; Xu, Peizhen; Xie, Qiang

2014-09-01

31

Magnetic structure and ferroelectric activity in orthorhombic YMnO3: Relative roles of magnetic symmetry breaking and atomic displacements  

NASA Astrophysics Data System (ADS)

We discuss the relative roles played by the magnetic inversion symmetry breaking and the ferroelectric (FE) atomic displacements in the multiferroic state of YMnO3. For these purposes we derive a realistic low-energy model, using results of first-principles electronic structure calculations and experimental parameters of the crystal structure below and above the FE transition. Then, we solve this model in the mean-field Hartree-Fock approximation. We argue that the multiferroic state in YMnO3 has a magnetic origin, and the centrosymmetric Pbnm structure is formally sufficient for explaining the main details of the noncentrosymmetric magnetic ground state. The relativistic spin-orbit interaction lifts the degeneracy, caused by the frustration of isotropic exchange interactions in the ab plane, and stabilizes a twofold periodic noncollinear magnetic state, which is similar to the E state apart from the spin canting. The noncentrosymmetric atomic displacements in the P21nm phase reduce the spin canting, but do not change the symmetry of the magnetic state. The effect of the P21nm distortion on the FE polarization ?Pa, parallel to the orthorhombic a axis, is twofold: (i) It gives rise to ionic contributions, associated with the oxygen and yttrium sites; (ii) it affects the electronic polarization, mainly through the change of the spin canting. The relatively small value of ?Pa, observed in the experiment, is caused by a partial cancellation of the electronic and ionic contributions, as well as different contributions in the ionic part, which takes place for the experimental P21nm structure. The twofold periodic magnetic state competes with the fourfold periodic one and, even in the displaced P21nm phase, these two states continue to coexist in a narrow energy range. Finally, we theoretically optimize the crystal structure. For these purposes we employ the LSDA+U approach and assume the collinear E-type antiferromagnetic alignment. Then, we use the obtained structural information again as the input for the construction and solution of the low-energy model. We have found that the agreement with the experimental data in this case is less satisfactory and |?Pa| is largely overestimated. Although the magnetic structure can be formally tuned by varying the Coulomb repulsion U as a parameter, apparently LSDA+U fails to reproduce some fine details of the experimental structure, and the cancellation of different contributions in ?Pa does not occur.

Solovyev, I. V.; Valentyuk, M. V.; Mazurenko, V. V.

2012-10-01

32

A spongy graphene based bimorph actuator with ultra-large displacement towards biomimetic application  

NASA Astrophysics Data System (ADS)

Bimorph actuators, consisting of two layers with asymmetric expansion and generating bending displacement, have been widely researched. Their actuation performances greatly rely on the difference of coefficients of thermal expansion (CTE) between the two material layers. Here, by introducing a spongy graphene (sG) paper with a large negative CTE as well as high electrical-to-thermal properties, an electromechanical sG/PDMS bimorph actuator is designed and fabricated, showing an ultra-large bending displacement output under low voltage stimulation (curvature of about 1.2 cm-1 at 10 V for 3 s), a high displacement-to-length ratio (~0.79), and vibration motion at AC voltage (up to 10 Hz), which is much larger and faster than that of the other electromechanical bimorph actuators. Based on the sG/PDMS bimorph serving as the ``finger'', a mechanical gripper is constructed to realize the fast manipulation of the objects under 0.1 Hz square wave voltage stimulation (0-8 V). The designed bimorph actuator coupled with ultra-large bending displacement, low driven voltage, and the ease of fabrication may open up substantial possibilities for the utilization of electromechanical actuators in practical biomimetic device applications.Bimorph actuators, consisting of two layers with asymmetric expansion and generating bending displacement, have been widely researched. Their actuation performances greatly rely on the difference of coefficients of thermal expansion (CTE) between the two material layers. Here, by introducing a spongy graphene (sG) paper with a large negative CTE as well as high electrical-to-thermal properties, an electromechanical sG/PDMS bimorph actuator is designed and fabricated, showing an ultra-large bending displacement output under low voltage stimulation (curvature of about 1.2 cm-1 at 10 V for 3 s), a high displacement-to-length ratio (~0.79), and vibration motion at AC voltage (up to 10 Hz), which is much larger and faster than that of the other electromechanical bimorph actuators. Based on the sG/PDMS bimorph serving as the ``finger'', a mechanical gripper is constructed to realize the fast manipulation of the objects under 0.1 Hz square wave voltage stimulation (0-8 V). The designed bimorph actuator coupled with ultra-large bending displacement, low driven voltage, and the ease of fabrication may open up substantial possibilities for the utilization of electromechanical actuators in practical biomimetic device applications. Electronic supplementary information (ESI) available: Video records of the cycled actuation of the sG/PDMS bimorph at 10 V for 5 s and the manipulation of objects by a mechanical gripper at 0.1 Hz, 8 V, and optical images of a prototype voltmeter based on the sG/PDMS bimorph. See DOI: 10.1039/c4nr02768j

Hu, Ying; Lan, Tian; Wu, Guan; Zhu, Zicai; Chen, Wei

2014-10-01

33

PHYSICAL REVIEW B 87, 014417 (2013) Giant atomic displacement at a magnetic phase transition in metastable Mn3O4  

E-print Network

, the Mn2+ spins, which are geometrically frustrated, do not order until a much lower temperature. AlthoughPHYSICAL REVIEW B 87, 014417 (2013) Giant atomic displacement at a magnetic phase transition, Stanford University, California 94305, USA 2 Stanford Institute of Materials and Energy Science, SLAC

Fisher, Ian

34

Atomic displacements in low temperature irradiated chromium crystals M. Biget, F. Maury, P. Vajda, A. Lucasson (*) and P. Lucasson  

E-print Network

293 Atomic displacements in low temperature irradiated chromium crystals M. Biget, F. Maury, P interprétation des différentes sous-étapes jusqu'à 40 K. Abstract. 2014 Monocrystalline specimens of chromium potential particular to each metal. Very little is known about low temperature irradiated chromium. To our

Paris-Sud XI, Université de

35

A statistical analysis of the lateral displacement of Si atoms in molecular dynamics simulations of successive bombardment with 20keV C60 projectiles  

Microsoft Academic Search

An important factor that determines the possible lateral resolution in sputter depth profiling experiments is ion induced lateral displacement of substrate atoms. Molecular dynamics (MD) simulations are performed to model the successive bombardment of Si with 20 keV C60 at normal incidence. A statistical analysis of the lateral displacement of atoms that originate from the topmost layer is presented and

K. D. Krantzman; E. L. Cook; A. Wucher; B. J. Garrison

2011-01-01

36

A statistical analysis of the lateral displacement of Si atoms in molecular dynamics simulations of successive bombardment with 20keV C 60 projectiles  

Microsoft Academic Search

An important factor that determines the possible lateral resolution in sputter depth profiling experiments is ion induced lateral displacement of substrate atoms. Molecular dynamics (MD) simulations are performed to model the successive bombardment of Si with 20keV C60 at normal incidence. A statistical analysis of the lateral displacement of atoms that originate from the topmost layer is presented and discussed.

K. D. Krantzman; E. L. Cook; A. Wucher; B. J. Garrison

2011-01-01

37

Generating atomic multi-dimensional entangled states under large atom-cavity detuning  

E-print Network

We propose a scheme to deterministically generate atomic two-dimensional and three-dimensional entangled states by passing two 87Rb atoms through a high-Q bi-mode cavity alternately. The scheme is insensitive to atomic spontaneous decay because of large atom-cavity detuning, the influence of cavity decay is also discussed. Our strictly numerical simulation shows our proposal is good enough to demonstrate the generation of atomic entanglement with high fidelity and within the current experimental technologies.

Peng Shi; Li-Bo Chen; Wen-Dong Li; Chun-Nian Ren; Chun-Hong Zheng; Yong-Jian Gu

2012-09-25

38

Determination of local atomic displacements in CeO1?xFxBiS2 system  

NASA Astrophysics Data System (ADS)

We have used Bi and Ce L3-edges extended x-ray absorption fine structure measurements to study local structure of CeO1?xFxBiS2 system as a function of F-substitution. The local structure of both BiS2 active layer and CeO1?xFx spacer layer changes systematically. The in-plane Bi–S1 distance decreases (?Rmax ? 0.08 Å) and the out-of-plane Bi–S2 distance increases (?Rmax ? 0.12 Å) with increasing F-content. On the other hand, the Ce-O/F distance increases (?Rmax ? 0.2 Å) with a concomitant decrease of the Ce–S2 distance (?Rmax ? 0.15 Å). Interestingly, the Bi–S1 distance is characterized by a large disorder that increases with F-content. The results provide useful information on the local atomic displacements in CeO1?xFxBiS2, that should be important for the understanding of the coexistence of superconductivity and low temperature ferromagnetism in this system.

Paris, E.; Joseph, B.; Iadecola, A.; Sugimoto, T.; Olivi, L.; Demura, S.; Mizuguchi, Y.; Takano, Y.; Mizokawa, T.; Saini, N. L.

2014-10-01

39

Determination of local atomic displacements in CeO1-xFxBiS2 system.  

PubMed

We have used Bi and Ce L3-edges extended x-ray absorption fine structure measurements to study local structure of CeO1-xFxBiS2 system as a function of F-substitution. The local structure of both BiS2 active layer and CeO1-xFx spacer layer changes systematically. The in-plane Bi-S1 distance decreases (?Rmax ? 0.08 ?) and the out-of-plane Bi-S2 distance increases (?Rmax ? 0.12 ?) with increasing F-content. On the other hand, the Ce-O/F distance increases (?Rmax ? 0.2 ?) with a concomitant decrease of the Ce-S2 distance (?Rmax ? 0.15 ?). Interestingly, the Bi-S1 distance is characterized by a large disorder that increases with F-content. The results provide useful information on the local atomic displacements in CeO1-xFxBiS2, that should be important for the understanding of the coexistence of superconductivity and low temperature ferromagnetism in this system. PMID:25299179

Paris, E; Joseph, B; Iadecola, A; Sugimoto, T; Olivi, L; Demura, S; Mizuguchi, Y; Takano, Y; Mizokawa, T; Saini, N L

2014-10-29

40

Evidence for large-scale effects of competition: niche displacement in Canada lynx and bobcat.  

PubMed

Determining the patterns, causes and consequences of character displacement is central to our understanding of competition in ecological communities. However, the majority of competition research has occurred over small spatial extents or focused on fine-scale differences in morphology or behaviour. The effects of competition on broad-scale distribution and niche characteristics of species remain poorly understood but critically important. Using range-wide species distribution models, we evaluated whether Canada lynx (Lynx canadensis) or bobcat (Lynx rufus) were displaced in regions of sympatry. Consistent with our prediction, we found that lynx niches were less similar to those of bobcat in areas of sympatry versus allopatry, with a stronger reliance on snow cover driving lynx niche divergence in the sympatric zone. By contrast, bobcat increased niche breadth in zones of sympatry, and bobcat niches were equally similar to those of lynx in zones of sympatry and allopatry. These findings suggest that competitively disadvantaged species avoid competition at large scales by restricting their niche to highly suitable conditions, while superior competitors expand the diversity of environments used. Our results indicate that competition can manifest within climatic niche space across species' ranges, highlighting the importance of biotic interactions occurring at large spatial scales on niche dynamics. PMID:24174116

Peers, Michael J L; Thornton, Daniel H; Murray, Dennis L

2013-12-22

41

Exploiting Universality in Atoms with Large Scattering Lengths  

SciTech Connect

The focus of this research project was atoms with scattering lengths that are large compared to the range of their interactions and which therefore exhibit universal behavior at sufficiently low energies. Recent dramatic advances in cooling atoms and in manipulating their scattering lengths have made this phenomenon of practical importance for controlling ultracold atoms and molecules. This research project was aimed at developing a systematically improvable method for calculating few-body observables for atoms with large scattering lengths starting from the universal results as a first approximation. Significant progress towards this goal was made during the five years of the project.

Braaten, Eric

2012-05-31

42

Influence of electron-phonon interaction in doped silicon crystals on the root-mean-square dynamic displacement of atoms  

Microsoft Academic Search

The root-mean-square dynamic displacements (begin{array}{*{20}c} - \\\\ {u^2 } \\\\ _{dyn} ) of silicon atoms in single-crystals doped with phosphorus, arsenic, antimony, boron, gallium, and indium are determined experimentally. Characteristic concentration dependences ofbegin{array}{*{20}c} - \\\\ {u^2 } \\\\ _{dyn} are obtained for boron- and phosphorus-doped silicon. A number of experimental facts indicating the existence of electron-phonon interaction in comparison with

M. D. Kapustina; V. A. Panteleev; T. Yu. Markova

1977-01-01

43

A metrological large range atomic force microscope with improved performance  

NASA Astrophysics Data System (ADS)

A metrological large range atomic force microscope (Met. LR-AFM) has been set up and improved over the past years at Physikalisch-Technische Bundesanstalt (PTB). Being designed as a scanning sample type instrument, the sample is moved in three dimensions by a mechanical ball bearing stage in combination with a compact z-piezostage. Its topography is detected by a position-stationary AFM head. The sample displacement is measured by three embedded miniature homodyne interferometers in the x, y, and z directions. The AFM head is aligned in such a way that its cantilever tip is positioned on the sample surface at the intersection point of the three interferometer measurement beams for satisfying the Abbe measurement principle. In this paper, further improvements of the Met. LR-AFM are reported. A new AFM head using the beam deflection principle has been developed to reduce the influence of parasitic optical interference phenomena. Furthermore, an off-line Heydemann correction method has been applied to reduce the inherent interferometer nonlinearities to less than 0.3 nm (p-v). Versatile scanning functions, for example, radial scanning or local AFM measurement functions, have been implemented to optimize the measurement process. The measurement software is also improved and allows comfortable operations of the instrument via graphical user interface or script-based command sets. The improved Met. LR-AFM is capable of measuring, for instance, the step height, lateral pitch, line width, nanoroughness, and other geometrical parameters of nanostructures. Calibration results of a one-dimensional grating and a set of film thickness standards are demonstrated, showing the excellent metrological performance of the instrument.

Dai, Gaoliang; Wolff, Helmut; Pohlenz, Frank; Danzebrink, Hans-Ulrich

2009-04-01

44

Giant atomic displacement at a magnetic phase transition in metastable Mn3O4  

SciTech Connect

We present x-ray, neutron scattering, and heat capacity data that reveal a coupled first-order magnetic and structural phase transition of the metastable mixed-valence postspinel compound Mn3O4 at 210 K. Powder neutron diffraction measurements reveal a magnetic structure in which Mn3+ spins align antiferromagnetically along the edge-sharing a axis, with a magnetic propagation vector k = [1/2,0,0]. In contrast, the Mn2+ spins, which are geometrically frustrated, do not order until a much lower temperature. Although the Mn2+ spins do not directly participate in the magnetic phase transition at 210 K, structural refinements reveal a large atomic shift at this phase transition, corresponding to a physical motion of approximately 0.25 angstrom, even though the crystal symmetry remains unchanged. This "giant" response is due to the coupled effect of built-in strain in the metastable postspinel structure with the orbital realignment of the Mn3+ ion.

Hirai, Shigeto [Stanford University; Moreira Dos Santos, Antonio F [ORNL; Shapiro, Max C [Stanford University; Molaison, Jamie J [ORNL; Pradhan, Neelam [ORNL; Guthrie, Malcolm [Carnegie Institution of Washington; Tulk, Christopher A [ORNL; Fisher, Ian R [Stanford University; Mao, Wendy [Stanford University

2013-01-01

45

BRIEF COMMUNICATION: Electrothermal bistability tuning in a large displacement micro actuator  

NASA Astrophysics Data System (ADS)

We report on an approach allowing simple yet efficient tuning of the bistability properties in large displacement micro actuators. The devices fabricated from silicon on insulator (SOI) wafers using a deep reactive ion etching (DRIE)-based process incorporate elastic suspension realized as a pair of beams initially curved in-plane and are operated electrostatically by a comb-drive transducer. The curvature of beam and therefore the stability characteristics of the suspension are controlled by passing a current through the suspension and resistive heating the beam material. Experimental results, which are in good agreement with the finite elements model predictions, demonstrate the feasibility of the suggested approach and show that the application of a small tuning current increases the device deflection from 42 to 56 µm, allows adjustment of the critical snap-through and snap-back voltages and makes it possible the control of latching without an additional electrode. The approach can be efficiently implemented in electrical and optical switches and threshold inertial and mass sensors where the use of long displacement actuators with an adjustable bistability range is beneficial.

Gerson, Y.; Krylov, S.; Ilic, B.

2010-11-01

46

American Mineralogist, Volume 75, pages 1253-1267, 1990 A study of the mean-square displacement amplitudes of Si, AI, and 0 atoms in  

E-print Network

amplitudes of Si, AI, and 0 atoms in framework structures: Evidence for rigid bonds, order, twinning of the mean-square displacement amplitudes (MSDA) of the T(Al,Si) and 0 atoms in ordered framework silicates in these crystals are consistent with a rigid bond model. In particular, the MSDAs of the T and 0 atoms

Downs, Robert T.

47

Gaze displacement and inter-segmental coordination during large whole body voluntary rotations.  

PubMed

Displacements of the visual axis and multi-segmental (eye-to-foot) coordination in the yaw plane were studied in ten human subjects (Ss) during voluntary reorientations to illuminated targets of eccentricities up to 180 degrees . We also investigated how knowledge of target location modifies the movement pattern. Eccentric targets (outbound trials) elicited eye, head, trunk and foot movements at latencies ca. 0.5, 0.6, 0.7 and 1.1 s, respectively. Knowledge of target location (return trials) reduced latencies for foot and trunk (but not eye and head) thus eye, head and trunk moved more en bloc. In most trials, the initial gaze shift fell short of the target and more than 50% of the visual angle was covered by the sum of vestibular nystagmic fast phases and head-in-space displacement, until target fixation. This indicates that during large gaze shifts the 'anticompensatory' role of the vestibulo-ocular reflex in target acquisition is prominent. During some predictable trials Ss acquired targets with a single large gaze shift, shortening target acquisition time by more than 200 ms. In these, gaze velocity (trunk-in-space + head-on-trunk + eye-in-orbit) remained often fairly constant for durations of up to 500 ms, suggesting that gaze velocity is a controlled parameter. Such pattern occurred during trunk mobilization, thus eye velocity co-varied with head-in-space rather than head-on-trunk velocity. Foot rotations were stereotyped and of constant frequency, suggesting they are generated by locomotor pattern generators. However, knowledge of target location reduced foot latencies indicating that local and supraspinal mechanisms interact for foot control. We propose that a single controller is responsible for the coupling of the multiple body segments and gaze velocity control during gaze shifts. PMID:19002676

Anastasopoulos, Dimitri; Ziavra, Nausica; Hollands, Mark; Bronstein, Adolfo

2009-03-01

48

Large Kerr nonlinearities on cavity-atom polaritons  

E-print Network

I analyze a scheme that is capable of producing large Kerr nonlinearities on cavity-atom polaritons in a cavity QED system consisting of multiple three-level atoms confined in a cavity mode. A weak control laser coupled to the atoms from free space induces destructive quantum interference in the polariton excitation of the coupled cavity-atom system and creates large Kerr nonlinearities on the intra-cavity light field. The scheme can be used for optical switching or cross-phase modulation of the cavity-atom polariton at ultra-low light levels, which may be useful for applications in quantum state manipulation in cavity QED, quantum measurements, and quantum logic gates.

Zhu, Yifu

2009-01-01

49

Large atom number Bose-Einstein condensate machines  

SciTech Connect

We describe experimental setups for producing large Bose-Einstein condensates of {sup 23}Na and {sup 87}Rb. In both, a high-flux thermal atomic beam is decelerated by a Zeeman slower and is then captured and cooled in a magneto-optical trap. The atoms are then transferred into a cloverleaf-style Ioffe-Pritchard magnetic trap and cooled to quantum degeneracy with radio-frequency-induced forced evaporation. Typical condensates contain 20x10{sup 6} atoms. We discuss the similarities and differences between the techniques used for producing large {sup 87}Rb and {sup 23}Na condensates in the context of nearly identical setups.

Streed, Erik W.; Chikkatur, Ananth P.; Gustavson, Todd L.; Boyd, Micah; Torii, Yoshio; Schneble, Dominik; Campbell, Gretchen K.; Pritchard, David E.; Ketterle, Wolfgang [MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States) and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Belfer Center for Science and International Affairs, Littauer P-14, 79 JFK Street, Harvard University, Cambridge, Massachusetts 02138 (United States); Hansen Experimental Physics Laboratory End Station 3, Room M302, Department of Physics, Stanford University, Stanford, California 94305 (United States); MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States) and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Institute of Physics, University of Tokyo, 3-8-1, Meguru-ku, Komaba, Tokyo 153-8902 (Japan); Physics A-106, Department of Physics and Astronomy, SUNY Stony Brook, Stony Brook, New York 11794 (United States); MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States) and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2006-02-15

50

Fast Edge-Preserving PatchMatch for Large Displacement Optical Flow.  

PubMed

The speed of optical flow algorithm is crucial for many video editing tasks such as slow motion synthesis, selection propagation, tone adjustment propagation, and so on. Variational coarse-to-fine optical flow algorithms can generally produce high-quality results but cannot fulfil the speed requirement of many practical applications. Besides, large motions in real-world videos also pose a difficult problem to coarse-to-fine variational approaches. We, in this paper, present a fast optical flow algorithm that can handle large displacement motions. Our algorithm is inspired by recent successes of local methods in visual correspondence searching as well as approximate nearest neighbor field algorithms. The main novelty is a fast randomized edge-preserving approximate nearest neighbor field algorithm, which propagates self-similarity patterns in addition to offsets. Experimental results on public optical flow benchmarks show that our method is significantly faster than state-of-the-art methods without compromising on quality, especially when scenes contain large motions. Finally, we show some demo applications by applying our technique into real-world video editing tasks. PMID:25252282

Bao, Linchao; Yang, Qingxiong; Jin, Hailin

2014-12-01

51

Kinematic behaviour of a large earthflow defined by surface displacement monitoring, DEM differencing, and ERT imaging  

NASA Astrophysics Data System (ADS)

Large earthflow-type landslides are destructive mass movement phenomena with highly unpredictable behaviour. Knowledge of earthflow kinematics is essential for understanding the mechanisms that control its movements. The present paper characterises the kinematic behaviour of a large earthflow near the village of ?ubietová in Central Slovakia over a period of 35 years following its most recent reactivation in 1977. For this purpose, multi-temporal spatial data acquired by point-based in-situ monitoring and optical remote sensing methods have been used. Quantitative data analyses including strain modelling and DEM differencing techniques have enabled us to: (i) calculate the annual landslide movement rates; (ii) detect the trend of surface displacements; (iii) characterise spatial variability of movement rates; (iv) measure changes in the surface topography on a decadal scale; and (v) define areas with distinct kinematic behaviour. The results also integrate the qualitative characteristics of surface topography, in particular the distribution of surface structures as defined by a high-resolution DEM, and the landslide subsurface structure, as revealed by 2D resistivity imaging. Then, the ground surface kinematics of the landslide is evaluated with respect to the specific conditions encountered in the study area including slope morphology, landslide subsurface structure, and local geological and hydrometeorological conditions. Finally, the broader implications of the presented research are discussed with particular focus on the role that strain-related structures play in landslide kinematic behaviour.

Prokešová, Roberta; Kardoš, Miroslav; Tábo?ík, Petr; Medve?ová, Alžbeta; Stacke, Václav; Chudý, František

2014-11-01

52

Determination of temperature-dependent atomic displacements in the Ca10Ir4As8(Fe2As2)5 superconductor with a metallic spacer layer  

NASA Astrophysics Data System (ADS)

We have used the combination of Fe K-edge and Ir L3-edge x-ray absorption measurements as a function of temperature to investigate local atomic displacements in the newly discovered Ca10Ir4As8(Fe2As2)5 superconducting system. We find relatively relaxed Fe-Fe atomic pair correlations with large displacements in the FeAs4 tetrahedra, revealed by Fe K-edge extended x-ray absorption fine structure (EXAFS) analysis. Similarly, the temperature dependence of Ir L3-edge EXAFS shows nanoscale disorder in the IrAs layer that should have a significant effect on the active FeAs-layer characteristics. Furthermore, x-ray absorption near edge structure data are presented to discuss the evolution of the unoccupied electronic states revealing the marginal role of spin-orbit coupling, while the interlayer interactions and disorder should be important for describing the physics of the Ca10Ir4As8(Fe2As2)5 system.

Paris, E.; Joseph, B.; Iadecola, A.; Marini, C.; Kudo, K.; Mitsuoka, D.; Nohara, M.; Mizokawa, T.; Saini, N. L.

2014-09-01

53

Enhancement of Magneto-Optic Effects via Large Atomic Coherence  

E-print Network

We utilize the generation of large atomic coherence to enhance the resonant nonlinear magneto-optic effect by several orders of magnitude, thereby eliminating power broadening and improving the fundamental signal-to-noise ratio. A proof-of-principle experiment is carried out in a dense vapor of Rb atoms. Detailed numerical calculations are in good agreement with the experimental results. Applications such as optical magnetometry or the search for violations of parity and time reversal symmetry are feasible.

V. A. Sautenkov; M. D. Lukin; C. J. Bednar; G. R. Welch; M. Fleischhauer; V. L. Velichansky; M. O. Scully

1999-04-08

54

Large-displacement structural durability analyses of simple bend specimen emulating rocket nozzle liners  

NASA Technical Reports Server (NTRS)

Large-displacement elastic and elastic-plastic, finite-element stress-strain analyses of an oxygen-tree high-conductivity (OFHC) copper plate specimen were performed using an updated Lagrangian formulation. The plate specimen is intended for low-cost experiments that emulate the most important thermomechanical loading and failure modes of a more complex rocket nozzle. The plate, which is loaded in bending at 593 C, contains a centrally located and internally pressurized channel. The cyclic crack initiation lives were estimated using the results from the analyses and isothermal strain-controlled low-cycle fatigue data for OFHC copper. A comparison of the predicted and experimental cyclic lives showed that an elastic analysis predicts a longer cyclic life than that observed in experiments by a factor greater than 4. The results from elastic-plastic analysis for the plate bend specimen, however, predicted a cyclic life in close agreement with experiment, thus justifying the need for the more rigorous stress-strain analysis.

Arya, Vinod K.; Halford, Gary R.

1994-01-01

55

An arbitrary Lagrangian-Eulerian formulation for solving moving boundary problems with large displacements and rotations  

NASA Astrophysics Data System (ADS)

An Arbitrary Lagrangian-Eulerian (ALE) formulation based on the unstructured finite volume method is proposed for solving moving boundary problems with large displacements and rotations. The numerical method is based on the side-centered arrangement of the primitive variables that does not require any ad-hoc modifications in order to enhance pressure coupling. The continuity equation is satisfied within each element at machine precision and the summation of the continuity equations can be exactly reduced to the domain boundary, which is important for the global mass conservation. A special attention is given to construct an ALE algorithm obeying the discrete geometric conservation law (DGCL). The mesh deformation algorithm is based on the indirect Radial Basis Function (RBF) algorithm at each time level while avoiding remeshing in order to enhance numerical robustness. For the parallel solution of resulting large-scale algebraic equations in a fully coupled form, a matrix factorization is introduced similar to that of the projection method for the whole system and the parallel algebraic multigrid solver BoomerAMG is used for the scaled discrete Laplacian provided by the HYPRE library which we access through the PETSc library. The present numerical algorithm is initially validated for the decaying Taylor-Green vortex flow, the flow past an oscillating circular cylinder in a channel and the flow induced by an oscillating sphere in a cubic cavity. Then the numerical algorithm is applied to the numerical simulation of flow field around a pair of flapping Drosophila wings in hover flight. The time variation of the Eulerian coherent structures in the near wake is shown along with the aerodynamic loads.

Erzincanli, Belkis; Sahin, Mehmet

2013-12-01

56

Parallel-plate MEMS mirror design for large on-resonance displacement  

Microsoft Academic Search

We present an electrostatically actuated MEMS mirror with 65 ?m of displacement. This design provides a 2 mm square reflective surface and allows for easy fabrication, making it suitable for a wide range of applications

S. R. Bhalotra; J. D. Mansell; H. L. Kung; D. A. B. Miller

2000-01-01

57

Multiple Displacement Amplification Enables Large-Scale Clonal Analysis following Retroviral Gene Therapy  

Microsoft Academic Search

Analysis of the fate of retrovirally transduced cells after transplantation is often hampered by the scarcity of available DNA. We evaluated a promising method for whole-genome amplification, called multiple displace- ment amplification (MDA), with respect to even and accurate representation of retrovirally transduced genomic DNA. We proved that MDA is a suitable method to subsequently quantify engraftment efficiencies by quantitative

S. Bleier; P. Maier; H. Allgayer; F. Wenz; W. J. Zeller; S. Fruehauf; S. Laufs

2008-01-01

58

Electronic Ferroelectricity in a Molecular Crystal with Large Polarization Directing Antiparallel to Ionic Displacement  

NASA Astrophysics Data System (ADS)

Ferroelectric polarization of 6.3?Ccm-2 is induced by the neutral-to-ionic transition, upon which nonpolar molecules of electron donor tetrathiafulvalene (TTF) and acceptor p-chloranil (CA) are incompletely ionized to ±0.60e and dimerized along the molecular stacking chain. We find that the ferroelectric properties are governed by intermolecular charge transfer rather than simple displacement of static point charge on molecules. The observed polarization and poling effect on the absolute structural configuration can be interpreted in terms of electronic ferroelectricity, which not only exhibits antiparallel polarity to the ionic displacement but also enhances the polarization more than 20 times that of the point-charge model.

Kobayashi, Kensuke; Horiuchi, Sachio; Kumai, Reiji; Kagawa, Fumitaka; Murakami, Youichi; Tokura, Yoshinori

2012-06-01

59

Chemical and displacement atomic pair correlations in crystalline solid solutions recovered by anomalous x-ray scattering in Fe-Ni alloys  

SciTech Connect

Short-range pair correlations of atoms in crystalline solid solutions consist of both chemical and displacement correlations. Measurement of these pair correlations is fundamental to understanding the properties of solid solutions. We discuss anomalous scattering techniques which have provided an important advance in our ability to recover these pair correlations and to model the local atomic arrangements in crystalline solid solutions of Fe-Ni alloys.

Ice, G.E.; Sparks, C.J. [Oak Ridge National Lab., TN (United States); Shaffer, L.B. [Anderson Univ., Anderson, IN (United States). Dept. of Physics

1992-12-31

60

Dynamics and control of a large displacement suspension system for ground testing of flexible space structures  

NASA Technical Reports Server (NTRS)

As the development in flexible space structures expands, the need for an efficient and accurate suspension system for ground tests increases accordingly. In this article, a disk suspension system was developed. Analytical results describing the dynamics of a passive and active suspension system were generated given realistic parameters of the system. These results for the passive case, were then compared with the data obtained from an experimental model with initial displacement and random forcing inputs. The dynamics of the system was analyzed. Results show that the experimental model resembles closely the analytical model and therefore strongly suggests feasibility of such a suspension system.

Reaves, Mercedes C.; Chew, Meng-Sang; Juang, Jer-Nan; Chiu, Steven H.

1992-01-01

61

Improvement in the Identification of a Crack Tip Echo in Ultrasonic Inspection using Large Displacement Ultrasound Transmission  

NASA Astrophysics Data System (ADS)

As an improvement in the imaging technique for the low S/N ratio of crack tip echo in ultrasonic inspection, we developed the Subharmonic Phased Array Crack Evaluation (SPACE) system. Although the pulser of conventional SPACE can generate large, over tens of nm, displacement ultrasound at a crack, it is effective only for closed cracks and not effective for most industrial cracks. For general use of the SPACE system in industrial inspection, we need to develop larger displacement ultrasound incidence equipment considering crack openings of the order of several nm to sub ?m. In this study, we developed a high voltage excitation SPACE and larger amplitude ultrasound incident to a crack using a high voltage proof transducer. The suitability of the developed system was investigated using typical models of cracks.

Mihara, T.; Ishida, H.

2014-06-01

62

Petascale computations for Large-scale Atomic and Molecular collisions  

E-print Network

Petaflop architectures are currently being utilized efficiently to perform large scale computations in Atomic, Molecular and Optical Collisions. We solve the Schroedinger or Dirac equation for the appropriate collision problem using the R-matrix or R-matrix with pseudo-states approach. We briefly outline the parallel methodology used and implemented for the current suite of Breit-Pauli and DARC codes. Various examples are shown of our theoretical results compared with those obtained from Synchrotron Radiation facilities and from Satellite observations. We also indicate future directions and implementation of the R-matrix codes on emerging GPU architectures.

McLaughlin, Brendan M

2014-01-01

63

Observation of an unusually large atomic parity-violation effect  

NASA Astrophysics Data System (ADS)

We report on observation of a large parity-violation effect in the atoms of ytterbium (Yb). This left-right asymmetry appears naturally in the Standard Model, and is associated with the exchange of a virtual heavy ``gauge" boson between subatomic particles. Eventually, parity violation has been observed and precisely measured by a number of groups in several different atoms, culminating in a 0.3% measurement in cesium (Cs) by Carl Wieman and co-workers at Boulder. The parity-violating amplitude of the 6x^2 ^1S0 -> 5d6s ^3D1 408-nm forbidden transition of ytterbium is found to be two orders of magnitude larger than in cesium. This is the largest atomic parity-violating amplitude yet observed. This also opens the way to future measurements of the parity violation effects for different Yb isotopes in order to test the effect of the neutron distributions within the nucleus and detect the so-called ``anapole moment" by comparing parity-violating amplitudes for various hyperfine components of the transition. So far, Cs is the only system where such a moment has been detected. Measurements of anapole moments are important for understanding the electroweak interactions within the nucleus which are hard to probe by other means.

Tsigutkin, Konstantin

2010-03-01

64

The Chi-Chi, Taiwan earthquake: Large surface displacements on an inland thrust fault  

NASA Astrophysics Data System (ADS)

In the early morning (01:47 local time) of September 21, 1999, the largest earthquake of the century in Taiwan (Mw=7.6, ML=7.3) struck the central island near the small town of Chi-Chi. The hypocenter was located by the Central Weather Bureau Seismological Center at 23.87°N, 120.75°E, with a depth of about 7 km.There were extensive surface ruptures for about 85 km along the Chelungpu fault with vertical thrust and left lateral strike-slip offsets. The maximum displacement of about 9.8 meters is among the largest fault movements ever measured for modern earthquakes. There was severe destruction in the towns of Chungliao, Nantou,Taichung, FengYuan, and Tungshi, with over 2300 fatalities and 8700 injuries.

Ma, Kuo-Fong; Lee, Chyi-Tyi; Tsai, Yi-Ben; Shin, Tzay-Chyn; Mori, Jim

65

Determination of threshold energies for displacements of Fe and Rh atoms in Fe-50 at.%Rh intermetallic compound by using energetic electron irradiation at low temperatures  

NASA Astrophysics Data System (ADS)

Changes in electrical resistivity induced by irradiation with energetic electrons were measured for Fe-50 at.%Rh alloy as a function of electron energy in the range from 0.5 to 2.0 MeV. The irradiation was carried out below 20 K and the resistivity was measured at 10 K. The electron energy dependence of the resistivity change rate was analysed by using a simple displacement theory, and the average threshold energies for atomic displacements, E d, were determined as 30 eV for Fe and 45 eV for Rh. The analysis also revealed that resistivity values for Frenkel pairs, ? F (in units of ?? cm per at.%) were 128 and 181 for Fe atom and Rh atom, respectively. The experimentally determined values of E d and ? F can be used for the quantitative estimate of defect concentration in Fe-50 at.%Rh irradiated with energetic particles.

Kosugi, S.; Ishikawa, N.; Saitoh, Y.; Hori, F.; Iwase, A.

2011-04-01

66

Online monitoring of the distributed lateral displacement in large AC power generators using a high spatial resolution Brillouin optical fiber sensor  

NASA Astrophysics Data System (ADS)

We report for the first time, to the best of our knowledge, online monitoring of the distributed lateral displacement in large AC power generators using high spatial resolution differential pulse-width pair Brillouin optical time-domain analysis (DPP-BOTDA). To perform the measurement of distributed lateral displacements with periods of only a few cm in large AC power generators, a 2 cm spatial resolution strain measurement is realized using the differential pulse pair of 8/8.2 ns in DPP-BOTDA, and then the lateral displacements are reconstructed according to the strain-displacement relation with the assumption of a sine shape function. Using different fiberglass ripple springs, two types of lateral displacement with periods of 3 and 3.25 cm are demonstrated, obtaining a maximum displacement of 0.43 mm with a measurement accuracy of ~ 40 µm. This provides the information on the stator coil tightness through online monitoring of the distributed lateral displacement caused by the fiberglass ripple springs, and ensures safe operating conditions for large AC power generators. In addition, the large number of sensing points associated with distributed optical fiber sensors make it economically and technically practical to monitor large numbers of key components in a generator without any interference from the large magnetic and electrical fields.

Dong, Yongkang; Bao, Xiaoyi; Chen, Liang

2011-11-01

67

Large-scale separation of amino acids by continuous displacement chromatography  

SciTech Connect

Continuous annular chromatography (CAC) is a developing technology that allows truly continuous chromatographic separations. Previous work has demonstrated the utility of this technology for the separation of various materials by isocratic elution on a bench scale. Novel applications and improved operation of the process were studied in this work, demonstrating that CAC is a versatile apparatus which is capable of separations at high throughput. Three specific separation systems were investigated. Pilot-scale separations at high loadings were performed using an industrial sugar mixture as an example of scale-up for isocratic separations. Bench-scale experiments of a low concentration metal ion mixture were performed to demonstrate stepwise elution, a chromatographic technique which decreases dilution and increases sorbent capacity. Finally, the separation of mixtures of amino acids by ion exchange was investigated to demonstrate the use of displacement development on the CAC. This technique, which perhaps has the most potential, when applied to the CAC allowed simultaneous separation and concentration of multicomponent mixtures on a continuous basis. Mathematical models were developed to describe the CAC performance and optimize the operating conditions. For all the systems investigated, the continuous separation performance of the CAC was found to be very nearly the same as the batchwise performance of conventional chromatography. The technology appears, thus, to be very promising for industrial applications.

DeCarli, J.P. II; Carta, G.; Byers, C.H.

1989-10-01

68

Achieving large stable vertical displacement in surface-micromachined microelectromechanical systems (MEMS)  

E-print Network

This thesis describes electrostatic actuation techniques and mechanical design features for realizing large planar analog vertical travel in an electrostatically actuated diffractive mid-infrared optical device, which is ...

Deutsch, Erik R. (Erik Robertson), 1974-

2002-01-01

69

Element-specific modal formulations for large-displacement multibody dynamics  

NASA Technical Reports Server (NTRS)

Large dispacement assumed-mode modeling techniques are examined in the context of multibody elastodynamics. The range of both general and element-specific approaches are studied with the aid of examples involving beams, plates, and shells. For systems undergoing primarily structural bending and twisting with little or no membrane distortion, it is found that fully-linear, element-specific, modal formulations provide the most accurate time history solutions at the least expense. When membrane effects become dominant in structural problems due to loading and boundary conditions, one must naturally resort to a formulation involving a nonlinear stress-strain relationship in addition to nonlinear terms associated with large overall system motion. Such nonlinear models were investigated using assumed modes and found to lead to modal convergence difficulties when standard free-free structural modes are employed. A constrained mode formulation aimed at addressing the convergence problem is proposed.

Ryan, R. R.; Yoo, H. H.

1989-01-01

70

A tale of two carenes: intrinsic optical activity and large-amplitude nuclear displacement.  

PubMed

The specific rotation for two isomeric members of the terpene family, (S)-(+)-2-carene and (S)-(+)-3-carene, has been investigated under complementary solvated and isolated conditions, where the latter vapor-phase work has been performed at excitation wavelengths of 355 and 633 nm by means of ultrasensitive cavity ring-down polarimetry (CRDP). Linear-response computations of dispersive optical activity built upon analogous density-functional (B3LYP/aug-cc-pVTZ) and coupled-cluster (CCSD/aug-cc-pVDZ) levels of theory have been enlisted to unravel the structural and electronic origins of observed behavior. The six-membered portion of the bicyclic skeleton in the nominally rigid 3-carene system is predicted to be near-planar in nature, with calculated and measured rotatory powers for the isolated (gas-phase) species shown to be in excellent agreement. In contrast, the inherent flexibility of 2-carene gives rise to two quasidegenerate conformations that are interconnected by a large-amplitude ring-puckering motion and exhibit antagonistic chiroptical properties. Various approaches to simulate the intrinsic response evoked from a thermally equilibrated ensemble of gaseous (S)-(+)-2-carene molecules have been considered, including implicit averaging over independent conformers and explicit (albeit restricted) averaging over nuclear degrees of freedom. A polarizable continuum model for implicit solvation was found to describe solvent-dependent trends reasonably well in the case of (S)-(+)-2-carene, but failed to reproduce the specific-rotation patterns emerging from polarimetric studies of (S)-(+)-3-carene. PMID:22888793

Lahiri, Priyanka; Wiberg, Kenneth B; Vaccaro, Patrick H

2012-09-27

71

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

72

Displacement cascades in polyatomic materials  

SciTech Connect

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

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

1982-01-01

73

Atomic displacement and disorder in LiNbO3 single crystal caused by high-energy 3He ion irradiation: an x-ray absorption spectroscopy study  

NASA Astrophysics Data System (ADS)

Nb K-edge x-ray absorption fine structure spectra from a single lithium niobate (LN) crystal irradiated with high-energy 3He ions of 41 MeV and from unexposed crystal as the reference material are compared. The differences in the x-ray absorption near edge structure (XANES) spectra are interpreted by simulating Nb K-edge XANES spectra with the FEFF8.2 code. It is found that displacements of Nb and Li atoms, as well as Li and O vacancies, are likely to cause structural disorder leading to change in the refractive index of LN and to diminished birefringence. This finding is in agreement with previous results obtained from SRIM-2003 simulations and transmission electron microscopy measurements.

Vitova, T.; Zamani-Meymian, M. R.; Peithmann, K.; Maier, K.; Hormes, J.

2009-12-01

74

Problem of large displacements of buried pipelines. Part 2. Stability of straight pipeline under ideally plastic of soil deformation  

Microsoft Academic Search

We developed analytical models of the buckling failure of initially rectilinear pipeline in the environment. We specify the\\u000a drawbacks of available analytical methods, which take no account of the possible longitudinal displacement of the pipeline\\u000a points or the limited length of the pipeline portion, as well as, in the limiting case, fail to describe the experimental\\u000a results of buckling failure

I. V. Orynyak; A. V. Bogdan

2007-01-01

75

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

76

Accommodation of Large Displacement along Thin Principal Slip Layer of a Fault: An Example of the Garam Thrust in the Paleozoic Taebaeksan Basin  

NASA Astrophysics Data System (ADS)

The principal slip layer (PSL) along which most of the shear displacement within a fault zone occurs is very narrow (less than 1-5 mm) and it is not so clear how this narrow layer accommodates a large (several m to several km) displacement. The NNW-striking and WSW-dipping Garam Thrust puts the Cambrian Wagok Formation on top of the Ordovician Mungok Formation in the Paleozoic Taebaeksan Basin of Korea. The Wagok Formation of the hanging wall is a massive dolostone consisting of euhedral dolomite grains (0.1-1 mm) and some fossil fragments. In contrast, the Mungok Formation of the footwall is a bedded limestone composed of calcite (20-150 ?m) with some fossil fragments and dolomite. The estimated minimum displacement of the thrust is about 120 m. The principal slip zone between the two formations is only 3-10 mm thick and filled by vein calcites (100-500 ?m in size) with foam texture. The hanging wall dolostone is highly fractured or “pulverized” while the footwall limestone is almost intact except a micro shear zone near the principal slip layer. In and adjacent to the principal slip layer, there are no fault rocks such as gouge or cataclasite. Prismatic euhedral quartz grains (100-200 ?m long) occurs within and around the principal slip layer suggesting infiltration of fluid rich in silica as well as carbonate along the principal slip layer. In view of the absence of fault rocks within and adjacent to the principal slip layer, the possible accommodation processes of the large displacement along the thin layer may include fault lubrication by nano-crystalline decomposition products of carbonate minerals and fluid effect. To test these possibilities, textural analyses on the principal slip zone and micro shear zone using scanning electron microscopy are under way and we will discuss these results.

Kim, S.; Ree, J.

2009-12-01

77

Dynamics and Thermodynamics of Crystalline Polymorphs. 3. ?-Glycine, Analysis of Variable-Temperature Atomic Displacement Parameters, and Comparison of Polymorph Stabilities.  

PubMed

In a series of systematic studies, we have investigated the molecular motion in crystals of the glycine polymorphs and determined their thermodynamic functions from an analysis of multitemperature atomic displacement parameters (ADPs) combined with ONIOM calculation on 15-molecule clusters. The studies are aimed at providing insight into the factors governing the relative stabilities of the ?-, ?-, and ?-polymorphs. This Article, the last in the series, focuses on the most stable polymorph, ?-glycine. Multitemperature diffraction data of the ?-glycine polymorph have been collected to 0.5 Å resolution between 10 and 300 K at two synchrotron beamlines, KEK Photon Factory and ID11 of the ESRF. The ADPs of ?-glycine from these sources differ significantly, as previously observed also for the other two polymorphs. A simple model of rigid body motion explains the ADPs from KEK and their temperature dependence. It provides lattice vibration frequencies that are in line with those from Raman spectroscopy. Together with the internal vibration frequencies from an ONIOM calculation, the thermodynamic functions are estimated using the Einstein, Debye, and Nernst-Lindemann models of heat capacity. The relative stabilities of the three polymorphs of glycine are discussed on the basis of the contributions to their free energies as obtained in this work and from various experimental and theoretical studies. The comparison shows that the free-energy differences are determined primarily by differences in lattice and zero-point vibrational energies. PMID:25271763

Aree, Thammarat; Bürgi, Hans-Beat; Chernyshov, Dmitry; Törnroos, Karl W

2014-10-30

78

Influence of Static Atomic Displacements on Composition Quantification of AlGaN/GaN Heterostructures from HAADF-STEM Images.  

PubMed

In an earlier publication Rosenauer et al. introduced a method for determination of composition in AlGaN/GaN heterostructures from high-angle annular dark field (HAADF) images. Static atomic displacements (SADs) were neglected during simulation of reference data because of the similar covalent radii of Al and Ga. However, SADs have been shown (Grillo et al.) to influence the intensity in HAADF images and therefore could be the reason for an observed slight discrepancy between measured and nominal concentrations. In the present study parameters of the Stillinger-Weber potential were varied in order to fit computed elastic constants, lattice parameters and bonding energies to experimental ones. A reference data set of HAADF images was simulated, in which the new parameterization was used to account for SADs. Two reference samples containing AlGaN layers with different Al concentrations were investigated and Al concentrations in the layers determined based on the new data set. We found that these concentrations were in good agreement with nominal concentrations as well as concentrations determined using alternative techniques such as strain state analysis and energy dispersive X-ray spectroscopy. PMID:25010567

Schowalter, Marco; Stoffers, Ingo; Krause, Florian F; Mehrtens, Thorsten; Müller, Knut; Fandrich, Malte; Aschenbrenner, Timo; Hommel, Detlef; Rosenauer, Andreas

2014-10-01

79

Effective-range corrections to three-body recombination for atoms with large scattering length  

SciTech Connect

Few-body systems with large scattering length a have universal properties that do not depend on the details of their interactions at short distances. The rate constant for three-body recombination of bosonic atoms of mass m into a shallow dimer scales as ({Dirac_h}/2{pi})a{sup 4}/m times a log-periodic function of the scattering length. We calculate the leading and subleading corrections to the rate constant, which are due to the effective range of the atoms, and study the correlation between the rate constant and the atom-dimer scattering length. Our results are applied to {sup 4}He atoms as a test case.

Hammer, H.-W.; Laehde, Timo A.; Platter, L. [Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie), Universitaet Bonn, 53115 Bonn (Germany); Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States); Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701 (United States)

2007-03-15

80

Molecular Dynamics Simulations from SNL's Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS)  

DOE Data Explorer

LAMMPS (http://lammps.sandia.gov/index.html) stands for Large-scale Atomic/Molecular Massively Parallel Simulator and is a code that can be used to model atoms or, as the LAMMPS website says, as a parallel particle simulator at the atomic, meso, or continuum scale. This Sandia-based website provides a long list of animations from large simulations. These were created using different visualization packages to read LAMMPS output, and each one provides the name of the PI and a brief description of the work done or visualization package used. See also the static images produced from simulations at http://lammps.sandia.gov/pictures.html The foundation paper for LAMMPS is: S. Plimpton, Fast Parallel Algorithms for Short-Range Molecular Dynamics, J Comp Phys, 117, 1-19 (1995), but the website also lists other papers describing contributions to LAMMPS over the years.

Plimpton, Steve; Thompson, Aidan; Crozier, Paul

81

Metrological atomic force microscope using a large range scanning dual stage  

Microsoft Academic Search

We developed a metrological atomic force microscope (MAFM) using a large range scanning dual stage and evaluated the performance\\u000a in the measurement of lateral dimension. AFMs are widely used in nanotechnology for very high spatial resolution, but the\\u000a limitation in measurement range should be overcome to expand its application in nanometrology. Therefore, we constructed new\\u000a MAFM having a large measurement

Jong-Ahn Kim; Jae Wan Kim; Chu-Shik Kang; Tae Bong Eom

2009-01-01

82

Rotary reactor for atomic layer deposition on large quantities of nanoparticles  

E-print Network

methods of coating particles have been devel- oped using chemical vapor deposition CVD techniques.8 deposition pro- cesses can lead to nonuniform coatings or the coalescence of the nanoparticles. The highRotary reactor for atomic layer deposition on large quantities of nanoparticles J. A. McCormick, B

George, Steven M.

83

Miocene high-pressure metamorphism in the Cyclades and Crete, Aegean Sea, Greece: Evidence for large-magnitude displacement on the Cretan detachment  

NASA Astrophysics Data System (ADS)

The Cyclades in the backarc region of the present Hellenic subduction zone are known for widespread Late Cretaceous to Eocene high-pressure metamorphism in the Cycladic blueschist unit. We report 40Ar/39Ar and Rb/Sr phengite ages of 24 21 Ma for high- pressure metamorphism (8 10 kbar, 350 400 °C) in the lowest tectonic unit in the Cyclades, the Basal unit, which structurally underlies the Cycladic blueschist unit. The Basal unit is correlated with the Tripolitza unit of the External Hellenides in the forearc region of the Hellenic subduction zone. The Tripolitza unit is unmetamorphosed on Crete, where it is separated from the underlying high-pressure (8 10 kbar, 300 400 °C) Plattenkalk and Phyllite-Quartzite units by the extensional Cretan detachment. The age for high- pressure metamorphism in the latter units is similar to our age for the Basal unit in the Cyclades. Because pressure-temperature conditions in the Plattenkalk and Phyllite- Quartzite units on Crete and the Basal unit in the Cyclades are also similar, they must have been in close proximity in the early Miocene Hellenic subduction zone. A palinspastic reconstruction suggests a subsequent displacement of >100 km on the Cretan detachment. This is one of the greatest displacement magnitudes ever reported from detachment faults. Because of this large offset, the Cretan detachment was an efficient agent for exhuming high-pressure rocks.

Ring, Uwe; Layer, Paul W.; Reischmann, Thomas

2001-05-01

84

Optically trapped atom interferometry using the clock transition of large Rb-87 Bose-Einstein condensates  

E-print Network

We present a Ramsey-type atom interferometer operating with an optically trapped sample of 10^6 Bose-condensed Rb-87 atoms. The optical trap allows us to couple the |F =1, mF =0>\\rightarrow |F =2, mF =0> clock states using a single photon 6.8GHz microwave transition, while state selective readout is achieved with absorption imaging. Interference fringes with contrast approaching 100% are observed for short evolution times. We analyse the process of absorption imaging and show that it is possible to observe atom number variance directly, with a signal-to-noise ratio ten times better than the atomic projection noise limit on 10^6 condensate atoms. We discuss the technical and fundamental noise sources that limit our current system, and outline the improvements that can be made. Our results indicate that, with further experimental refinements, it will be possible to produce and measure the output of a sub-shot-noise limited, large atom number BEC-based interferometer. In an addendum to the original paper, we attribute our inability to observe quantum projection noise to the stability of our microwave oscillator and background magnetic field. Numerical simulations of the Gross-Pitaevskii equations for our system show that dephasing due to spatial dynamics driven by interparticle interactions account for much of the observed decay in fringe visibility at long interrogation times. The simulations show good agreement with the experimental data when additional technical decoherence is accounted for, and suggest that the clock states are indeed immiscible. With smaller samples of 5 \\times 10^4 atoms, we observe a coherence time of {\\tau} = (1.0+0.5-0.3) s.

P. A. Altin; G. McDonald; D. Döring; J. E. Debs; T. Barter; N. P. Robins; J. D. Close; S. A. Haine; T. M. Hanna; R. P. Anderson

2010-11-22

85

Method for large-scale fabrication of atomic-scale structures on material surfaces using surface vacancies  

DOEpatents

A method for forming atomic-scale structures on a surface of a substrate on a large-scale includes creating a predetermined amount of surface vacancies on the surface of the substrate by removing an amount of atoms on the surface of the material corresponding to the predetermined amount of the surface vacancies. Once the surface vacancies have been created, atoms of a desired structure material are deposited on the surface of the substrate to enable the surface vacancies and the atoms of the structure material to interact. The interaction causes the atoms of the structure material to form the atomic-scale structures.

Lim, Chong Wee (Urbana, IL); Ohmori, Kenji (Urbana, IL); Petrov, Ivan Georgiev (Champaign, IL); Greene, Joseph E. (Champaign, IL)

2004-07-13

86

Large scale growth and characterization of atomic hexagonal boron nitride layers.  

PubMed

Hexagonal boron nitride (h-BN), a layered material similar to graphite, is a promising dielectric. Monolayer h-BN, so-called "white graphene", has been isolated from bulk BN and could be useful as a complementary two-dimensional dielectric substrate for graphene electronics. Here we report the large area synthesis of h-BN films consisting of two to five atomic layers, using chemical vapor deposition. These atomic films show a large optical energy band gap of 5.5 eV and are highly transparent over a broad wavelength range. The mechanical properties of the h-BN films, measured by nanoindentation, show 2D elastic modulus in the range of 200-500 N/m, which is corroborated by corresponding theoretical calculations. PMID:20698639

Song, Li; Ci, Lijie; Lu, Hao; Sorokin, Pavel B; Jin, Chuanhong; Ni, Jie; Kvashnin, Alexander G; Kvashnin, Dmitry G; Lou, Jun; Yakobson, Boris I; Ajayan, Pulickel M

2010-08-11

87

Ground State Energy of Large Atoms in a Self-Generated Magnetic Field  

Microsoft Academic Search

We consider a large atom with nuclear charge Z described by non-relativistic quantum mechanics with classical or quantized electromagnetic field. We prove that the absolute\\u000a ground state energy, allowing for minimizing over all possible self-generated electromagnetic fields, is given by the non-magnetic\\u000a Thomas-Fermi theory to leading order in the simultaneous Z ? ?, ? ? 0 limit if Z\\u000a ?

László Erdos; Jan Philip Solovej

2010-01-01

88

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

89

An Atomic Layer Deposition Method to Fabricate Economical and Robust Large Area Microchannel Plates for Photodetectors  

NASA Astrophysics Data System (ADS)

We demonstrate an economical and robust route to fabricate large-area microchannel plate (MCP) detectors which will open new opportunities in larger area MCP-based detector technologies. Using our newly developed bottom-up process flow, we have fabricated large area MCPs (8 x 8). We used Atomic Layer Deposition (ALD), a powerful and precise thin film deposition technique, to tailor the electrical resistance and secondary electron emission (SEE) properties of large area, low cost, borosilicate glass capillary arrays. The self limiting growth mechanism in ALD allows atomic level control over the thickness and composition of resistive and secondary electron emission (SEE) layers that can be deposited conformally on high aspect ratio capillary glass arrays. We have developed several robust and reliable ALD processes for the resistive coatings and SEE layers to give us precise control over the resistance in the target range for MCPs (106-109 ?) and SEE coefficient (up to 8). The MCPs are tested in stacks of one or two plates and exhibit gains as high as 107 for a pair of MCPs. This approach allows the functionalization of microporous, insulating substrates to produce MCPs with high gain and low noise. These capabilities allow separation of the substrate material properties from the amplification properties. We studied the various MCP parameters such as gain, background counts, and resistance as a function of the ALD process parameters. Here we describe a complete process flow to produce fully functionalized working large area MCPs.

Mane, Anil U.; Peng, Qing; Elam, Jeffrey W.; Bennis, Daniel C.; Craven, Christopher A.; Detarando, Michael A.; Escolas, John R.; Frisch, Henry J.; Jokela, Slade J.; McPhate, Jason; Minot, Michael J.; Siegmund, Oswald H. W.; Renaud, Joseph M.; Wagner, Robert G.; Wetstein, Matthew J.

90

A novel atomic layer deposition method to fabricate economical and robust large area microchannel plates  

NASA Astrophysics Data System (ADS)

We demonstrate a cost-effective and robust route to fabricate large-area microchannel plate (MCP) detectors, which will open new potential in larger area MCP-based detector technologies. For the first time, using our newly developed process flow we have fabricated large area (8"x8") MCPs. We used atomic layer deposition (ALD), a powerful thin film deposition technique, to tailor the electrical resistance and secondary electron emission (SEE) properties of large area, low cost, borosilicate glass capillary arrays. The self limiting growth mechanism in ALD allows atomic level control over the thickness and composition of resistive and SEES layers that can be deposited conformally on high aspect ratio capillary glass arrays. We have developed several robust and reliable ALD processes for the resistive coatings and SEE layers to give us precise control over the resistance (106-1010?) and SEE coefficient (up to 5). This novel approach allows the functionalization of microporous, insulating substrates to produce MCPs with high gain and low noise. These capabilities allow a separation of the substrate material properties from the amplification properties. Here we describe a complete process flow to produce large area MCPs.

Mane, Anil U.; Peng, Qing; Wetstein, Matthew J.; Wagner, Robert G.; Frisch, Henry J.; Siegmund, Oswald H. W.; Minot, Michael J.; Adams, Bernhard W.; Chollet, Matthieu C.; Elam, Jeffrey W.

2011-06-01

91

Large area hexagonal boron nitride monolayer as efficient atomically thick insulating coating against friction and oxidation.  

PubMed

Coating is the most widely applied technology to improve surface properties of substrates, and nanotechnology has been playing an important role in enhancing the coating performance. However, the tunability of surface properties by a single atomic layer remains poorly understood. Here we demonstrate that a chemical vapor deposited hexagonal boron nitride (h-BN) monolayer of large area and high quality can serve as a perfect coating to significantly improve friction, oxidation and electric resistance of the substrates. The exceptional low friction and insulation of h-BN monolayer coating facilitate the characterization of the h-BN film vividly by atomic force microscopy, showing the h-BN monolayer consists of domains with size within a few micrometers. This excellent coating performance together with the exceptional high thermal and chemical stability make the h-BN monolayer a promising coating material. PMID:24532053

Li, Xuemei; Yin, Jun; Zhou, Jianxin; Guo, Wanlin

2014-03-14

92

Large area hexagonal boron nitride monolayer as efficient atomically thick insulating coating against friction and oxidation  

NASA Astrophysics Data System (ADS)

Coating is the most widely applied technology to improve surface properties of substrates, and nanotechnology has been playing an important role in enhancing the coating performance. However, the tunability of surface properties by a single atomic layer remains poorly understood. Here we demonstrate that a chemical vapor deposited hexagonal boron nitride (h-BN) monolayer of large area and high quality can serve as a perfect coating to significantly improve friction, oxidation and electric resistance of the substrates. The exceptional low friction and insulation of h-BN monolayer coating facilitate the characterization of the h-BN film vividly by atomic force microscopy, showing the h-BN monolayer consists of domains with size within a few micrometers. This excellent coating performance together with the exceptional high thermal and chemical stability make the h-BN monolayer a promising coating material.

Li, Xuemei; Yin, Jun; Zhou, Jianxin; Guo, Wanlin

2014-03-01

93

Large-Area Atomic Oxygen Facility Used to Clean Fire-Damaged Artwork  

NASA Technical Reports Server (NTRS)

In addition to completely destroying artwork, fires in museums and public buildings can soil a displayed artwork with so much accumulated soot that it can no longer be used for study or be enjoyed by the public. In situations where the surface has not undergone extensive charring or melting, restoration can be attempted. However, soot deposits can be very difficult to remove from some types of painted surfaces, particularly when the paint is fragile or flaking or when the top surface of the paint binder has been damaged. Restoration typically involves the use of organic solvents to clean the surface, but these solvents may cause the paint layers to swell or leach out. Also, immersion of the surface or swabbing during solvent cleaning may move or remove pigment through mechanical contact, especially if the fire damage extends into the paint binder. A noncontact technique of removing organic deposits from surfaces was developed out of NASA research on the effects of oxygen atoms on various materials. Atomic oxygen is present in the atmosphere surrounding the Earth at the altitudes where satellites typically orbit. It can react chemically with surface coatings or deposits that contain carbon. In the reaction, the carbon is converted to carbon monoxide and some carbon dioxide. Water vapor is also a byproduct of the reaction if the surface contains carbon-hydrogen bonds. To study this reaction, NASA developed Earth-based facilities to produce atomic oxygen for material exposure and testing. A vacuum facility designed and built by the Electro-Physics Branch of the NASA Glenn Research Center at Lewis Field to provide atomic oxygen over a large area for studying reactions in low Earth orbit has been used to successfully clean several full-size paintings. (This facility can accommodate paintings up to 1.5 by 2.1 m. The atomic oxygen plasma is produced between two large parallel aluminum plates using a radiofrequency power source operating at roughly 400 W. Atomic oxygen is generated uniformly over this area at an operating pressure of 1 to 5 mtorr.

Rutledge, Sharon K.; Banks, Bruce A.; Steuber, Thomas J.; Sechkar, Edward A.

2000-01-01

94

Ground state energy of large atoms in a self-generated magnetic field  

E-print Network

We consider a large atom with nuclear charge $Z$ described by non-relativistic quantum mechanics with classical or quantized electromagnetic field. We prove that the absolute ground state energy, allowing for minimizing over all possible self-generated electromagnetic fields, is given by the non-magnetic Thomas-Fermi theory to leading order in the simultaneous $Z\\to \\infty$, $\\al\\to 0$ limit if $Z\\al^2\\leq \\kappa$ for some universal $\\kappa$, where $\\al$ is the fine structure constant.

Laszlo Erdos; Jan Philip Solovej

2009-03-10

95

Displacement cascades in diatomic materials  

SciTech Connect

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

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

1981-01-01

96

A probable vacuum state containing a large number of hydrogen atom of excited state or ground state K, Rb or Cs atom  

E-print Network

The linear Stark effect shows that the first excited state of hydrogen atom has large permanent electric dipole moment (EDM), d(H)=3eao (ao is Bohr radius). Using special capacitors our experiments discovered that the ground state K, Rb or Cs atom is polar atom with a large EDM of the order of eao as hydrogen atom of excited state. Their capacitance(C) at different voltage (V) was measured. The C-V curve shows that the saturation polarization of K, Rb or Cs vapor has be observed when the field E more than ten to the fifth power V/m. When the saturation polarization appeared, nearly all K, Rb or Cs atoms(more than 98 percent) turned toward the direction of the field, and C is approximately equal to Co (Co is vacuum capacitance) or their dielectric constant is nearly the same as vacuum! K, Rb or Cs vapor just exist in the lowest energy state, so we see the vacuum state containing a large number of atoms! Due to the saturation polarization of hydrogen vapor of excited state is easily appears, we conjecture that ...

You, Pei-Lin

2008-01-01

97

Very large-scale structures in sintered silica aerogels as evidenced by atomic force microscopy and ultra-small angle  

E-print Network

Very large-scale structures in sintered silica aerogels as evidenced by atomic force microscopy of silica aerogels has been extensively studied mainly by scattering techniques (neutrons, X-rays, light) and atomic force microscopy (AFM) experiments have been carried out on aerogels at dierent steps of densi

Demouchy, Sylvie

98

A large-scale cold atom source in an integrating sphere  

NASA Astrophysics Data System (ADS)

An integrating sphere with a diameter of 10 cm is developed for cooling atoms. The maximum number of 2 × 1010 cold atoms is obtained from a background vapor with 220 mW cooling laser power. The cold atom number can be increased by further increasing the cooling power. Such cold atom source would have potential use for Raman-Ramsey atomic clock with good signal-to-noise ratio (SNR).

Zheng, Ben-Chang; Cheng, Hua-Dong; Meng, Yan-Ling; Liu, Peng; Wang, Xiu-Mei; Xiao, Ling; Wan, Jin-Yin; Liu, Liang

2014-05-01

99

An atomic-absorption method for the determination of gold in large samples of geologic materials  

USGS Publications Warehouse

A laboratory method for the determination of gold in large (100-gram) samples has been developed for use in the study of the gold content of placer deposits and of trace amounts of gold in other geologic materials. In this method the sample is digested with bromine and ethyl ether, the gold is extracted into methyl isobutyl ketone, and the determination is made by atomicabsorption spectrophotometry. The lower limit of detection is 0.005 part per million in the sample. The few data obtained so far by this method agree favorably with those obtained by assay and by other atomic-absorption methods. About 25 determinations can be made per man-day.

VanSickle, Gordon H.; Lakin, Hubert William.

1968-01-01

100

Large scan area high-speed atomic force microscopy using a resonant scanner  

NASA Astrophysics Data System (ADS)

A large scan area high-speed scan stage for atomic force microscopy using the resonant oscillation of a quartz bar has been constructed. The sample scanner can be used for high-speed imaging in both air and liquid environments. The well-defined time-position response of the scan stage due to the use of resonance allows highly linearized images to be obtained with a scan size up to 37.5 ?m in 0.7 s. The scanner is demonstrated for imaging highly topographic silicon test samples and a semicrystalline polymer undergoing crystallization in air, while images of a polymer and a living bacteria, S. aureus, are obtained in liquid.

Zhao, B.; Howard-Knight, J. P.; Humphris, A. D. L.; Kailas, L.; Ratcliffe, E. C.; Foster, S. J.; Hobbs, J. K.

2009-09-01

101

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

102

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

103

Calculations of atomic sputtering and displacement cross-sections in solid elements by electrons with energies from threshold to 1. 5 MV  

SciTech Connect

The kinetics of knock-on collisions of relativistic electrons with nuclei and details of the numerical evaluation of differential, recoil, and total Mott cross-sections are reviewed and discussed. The effects of electron beam induced displacement and sputtering, in the transmission electron microscope (TEM) environment, on microanalysis are analyzed with particular emphasis placed on the removal of material by knock-on sputtering. The mass loss predicted due to transmission knock-on sputtering is significant for many elements under conditions frequently encountered in microanalysis. Total Mott cross-sections are tabulated for all naturally occurring solid elements up to Z = 92 at displacement energies of one, two, four, and five times the sublimation energy and for accelerating voltages accessible in the transmission electron microscope. Fortran source code listings for the calculation of the differential Mott cross-section as a function of electron scattering angle (dMottCS), as a function of nuclear recoil angle (RECOIL), and the total Mott cross-section (TOTCS) are included. 48 refs., 21 figs., 12 tabs.

Bradley, C.R.

1988-12-01

104

Recovery of SRO parameters and pairwise atomic displacements in a Fe{sub 46.5}Ni{sub 53.5} alloy  

SciTech Connect

Resonant (anomalous) x-ray scattering is used to alter the contrast between atoms nearby in the periodic table to recover local pair correlations. Both Warren-Cowley short-range order parameters and chemically specific interatomic distances are recovered from diffusely scattered x-ray intensities measured at three different x-ray energies (3{lambda} method). Analysis of the statistical and systematic errors shows that the average values for the number and kinds of first nearest neighbors are recovered to about one atom in one hundred and their interatomic distances to about {+-}0.002 {angstrom}.

Jiang, X. [Sandia National Labs., CA (United States); Ice, G.E.; Sparks, C.J. [Oak Ridge National Lab., TN (United States)] [and others

1994-12-31

105

Photoresponse properties of large-area MoS2 atomic layer synthesized by vapor phase deposition  

NASA Astrophysics Data System (ADS)

Photoresponse properties of a large area MoS2 atomic layer synthesized by vapor phase deposition method without any catalyst are studied. Scanning electron microscopy, atomic force microscopy, Raman spectrum, and photoluminescence spectrum characterizations confirm that the two-dimensional microstructures of MoS2 atomic layer are of high quality. Photoelectrical results indicate that the as-prepared MoS2 devices have an excellent sensitivity and a good reproducibility as a photodetector, which is proposed to be ascribed to the potential-assisted charge separation mechanism.

Luo, Siwei; Qi, Xiang; Ren, Long; Hao, Guolin; Fan, Yinping; Liu, Yundan; Han, Weijia; Zang, Chen; Li, Jun; Zhong, Jianxin

2014-10-01

106

PHYSICAL REVIEW A 89, 022317 (2014) Large-scale modular quantum-computer architecture with atomic memory  

E-print Network

PHYSICAL REVIEW A 89, 022317 (2014) Large-scale modular quantum-computer architecture with atomic.-M. Duan,5 and J. Kim4 1 Joint Quantum Institute, University of Maryland Department of Physics and National Institute of Standards and Technology, College Park, Maryland 20742, USA 2 Department of Physics

Monroe, Christopher

107

Tunable low-energy Ar fast atom source with large diameter  

SciTech Connect

We have developed a low-energy Ar fast atom source consisting of a surface wave plasma (SWP) source and two carbon electrodes with a diameter of 80 mm. Ions were extracted from the SWP using two carbon electrodes, accelerated and injected to the process chamber and then neutralized by charge exchange reaction without energy loss. Characteristics of the Ar ions and Ar fast atoms were investigated using quadrupole mass spectroscopy with an energy analyzer. Energies of Ar fast atoms were successfully controlled from 20 to 80 eV by varying the acceleration voltage applied at the carbon electrode.

Hara, Yasuhiro; Takashima, Seigo; Yamakawa, Koji; Den, Shoji; Toyoda, Hirotaka; Hori, Masaru [Department of Electrical Engineering and Computer Science, Nagoya University, Furocho, Chikusa-ku, Nagoya 464-8603 (Japan); Katagiri Engineering Co., Ltd., Tsurumi-ku, Yokohama 230-0003 (Japan); Plasma Nanoresearch Center Furo-cho, Chikusa-ku, Nagoya 464-8603 Japan (Japan); Department of Electrical Engineering and Computer Science, Nagoya University, Furocho, Chikusa-ku, Nagoya 464-8603 (Japan)

2007-12-03

108

Large quality factor in sheet metamaterials made from dark dielectric meta-atoms  

E-print Network

Metamaterials-or artificial electromagnetic materials-can create media with properties unattainable in nature, but mitigating dissipation is a key challenge for their further development. Here, we demonstrate a low-loss metamaterial by exploiting dark bound states in dielectric inclusions coupled to the external waves by small nonresonant metallic antennas. We experimentally demonstrate a dispersion-engineered metamaterial based on a meta-atom made from alumina, and we show that its resonance has a much larger quality factor than metal-based meta-atoms. Finally, we show that our dielectric meta-atom can be used to create sheet metamaterials with negative permittivity or permeability.

Jain, Aditya; Koschny, Thomas; Soukoulis, Costas M

2014-01-01

109

Crystal structure and thermoelectric properties of clathrate, Ba{sub 8}Ni{sub 3.5}Si{sub 42.0}: Small cage volume and large disorder of the guest atom  

SciTech Connect

Samples with the type-I clathrate composition Ba{sub 8}Ni{sub x}Si{sub 46-x} have been synthesized and their structure and thermoelectric properties characterized. Microprobe analysis indicates the Ni incorporation to be 2.62{<=}x{<=}3.53. The x=3.5 phase crystallizes in the type-I clathrate structure (space group: Pm-3n) with a lattice parameter of 10.2813(3) A. The refined composition was Ba{sub 8}Ni{sub 3.5}Si{sub 42.0}, with small vacancies, 0.4 and 0.5 atoms per formula unit, at the 2a and 6c sites, respectively. The position of the Ba2 atom in the large cage was modeled using a 4-fold split position (24j site), displaced 0.18 A from the cage center (6d site). The volume of the large cage is calculated to be 146 A{sup 3}, smaller than other clathrates with similar cation displacement. The sample shows n-type behavior with a maximum of -50 {mu}V/K at 823 K above which the Seebeck coefficient decreases, suggesting mixed carriers. Lattice thermal conductivity, {kappa}{sub l}, is 55 mW/K above 600 K. - Graphical abstract: Seebeck coefficient and resistivity of the type-I clathrate Ba{sub 8}Ni{sub 3.5}Si{sub 41.0}. Structure show's large displacement of the Ba cation in the large cage (6c site). Highlights: Black-Right-Pointing-Pointer Crystal structure of the Ba{sub 8}Ni{sub 3.5}Si{sub 41.0} reported. Black-Right-Pointing-Pointer Vacancies at the 2a and 6c sites. Black-Right-Pointing-Pointer Large disorder of Ba guest atom, 0.18 A from cage center. Black-Right-Pointing-Pointer Structure is compared to Ba{sub 8}Si{sub 46} and other type-I clathrates. Black-Right-Pointing-Pointer Max Seebeck of -50.7 {mu}V/C at 798.4 K, thermal conductivity {approx}55 mW/K.

Roudebush, John H., E-mail: jhr@princeton.edu [Department of Chemistry, University of California, One Shields Ave., Davis, CA 95616 (United States); Orellana, Mike [Department of Chemistry, University of California, One Shields Ave., Davis, CA 95616 (United States); Bux, Sabah [Thermal Energy Conversion Technologies Group, Jet Propulsion Laboratory/California Institute of Technology, Pasadena, CA 91109 (United States); Yi Tanghong; Kauzlarich, Susan M. [Department of Chemistry, University of California, One Shields Ave., Davis, CA 95616 (United States)

2012-08-15

110

Large Ground-State Entropy Changes for Hydrogen Atom Transfer Reactions of Iron Complexes  

PubMed Central

Reported herein are the hydrogen atom transfer (HAT) reactions of two closely related dicationic iron tris ?-diimine complexes. FeII(H2bip) (iron(II) tris[2,2?-bi-1,4,5,6-tetra-hydropyrimidine]diperchlorate) and FeII(H2bim) (iron(II) tris[2,2?-bi-2-imidazoline]diperchlorate) both transfer H• to TEMPO (2,2,6,6-tetramethyl-1-piperidinoxyl) to yield the hydroxylamine, TEMPO-H, and the respective deprotonated iron(III) species, FeIII(Hbip) or FeIII(Hbim). The ground-state thermodynamic parameters in MeCN were determined for both systems using both static and kinetic measurements. For FeII(H2bip) + TEMPO: ?G° = ?0.3 ± 0.2 kcal mol?1, ?H° =?9.4 ± 0.6 kcal mol?1, ?S° = ?30 ± 2 cal mol?1 K?1. For FeII(H2bim) + TEMPO: ?G° = 5.0 ± 0.2 kcal mol?1, ?H° = ?4.1 ± 0.9 kcal mol?1, ?S° = ?30 ± 3 cal mol?1 K?1. The large entropy changes for these reactions, |T?S°| = 9 kcal mol?1 at 298 K, are exceptions to the traditional assumption that ?S° ? 0 for simple HAT reactions. Various studies indicate that hydrogen-bonding, solvent effects, ion-pairing, and iron spin-equilibria do not make major contributions to the observed ?S°HAT. Instead, this effect arises primarily from changes in vibrational entropy upon oxidation of the iron center. Measurement of the electron transfer half-reaction entropy, |?S° Fe(H2bim)/ET| = 29 ± 3 cal mol?1 K?1, is consistent with a vibrational origin. This conclusion is supported by UHF/6-31G* calculations on the simplified reaction [FeII(H2N=CHCH=NH2)2(H2bim)]2+•••ONH2 ? [FeII(H2N=CHCH=NH2)2(Hbim)]2+•••HONH2. The discovery that ?S°HAT can deviate significantly from zero has important implications on the study of HAT and proton-coupled electron transfer (PCET) reactions. For instance, these results indicate that free energies, rather than enthalpies, should be used to estimate the driving force for HAT when transition metal centers are involved. PMID:17402735

Mader, Elizabeth A.; Davidson, Ernest R.

2008-01-01

111

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...

112

Towards large area and continuous MoS2 atomic layers via vapor-phase growth: thermal vapor sulfurization  

NASA Astrophysics Data System (ADS)

We report on the effects of substrate, starting material, and temperature on the growth of MoS2 atomic layers by thermal vapor sulfurization in a tube-furnace system. With Mo as the starting material, atomic layers of MoS2 flakes are obtained on sapphire substrates while a bell-shaped MoS2 layer, sandwiched by amorphous SiO2, is obtained on native-SiO2/Si substrates under the same sulfurization conditions. An anomalous thickness-dependent Raman shift (A1g) of the MoS2 atomic layers is observed in Mo-sulfurizations on sapphire substrates, which can be attributed to the competition between the effects of thickness and the surface/interface. Both effects vary with the sulfurizing temperatures for a certain initial Mo thickness. The anomalous frequency trend of A1g is missing when using MoO3 instead of Mo as the starting material. In this case, the lateral growth of MoS2 on sapphire is also largely improved. Furthermore, the area density of the resultant MoS2 atomic layers is significantly increased by increasing the deposition temperature of the starting MoO3 to 700 °C the adjacent ultrathin MoS2 grains coalesce in one or other direction, forming connected chains in wafer scale. The thickness of the so-obtained MoS2 is generally controlled by the thickness of the starting material; however, the structural and morphological properties of MoS2 grains, towards large area and continuous atomic layers, are strongly dependent on the temperature of the initial material deposition, and on the temperature of sulfurization, because of the competition between surface mobility and atom evaporation.

Liu, Hongfei; Ansah Antwi, K. K.; Ying, Jifeng; Chua, Soojin; Chi, Dongzhi

2014-10-01

113

Optically trapped atom interferometry using the clock transition of large 87Rb Bose-Einstein condensates  

NASA Astrophysics Data System (ADS)

In our original paper (Altin et al 2011 New J. Phys. 13 065020), we presented the results from a Ramsey atom interferometer operating with an optically trapped sample of up to 106 Bose-condensed 87Rb atoms in the mF = 0 clock states. We were unable to observe projection noise fluctuations on the interferometer output, which we attribute to the stability of our microwave oscillator and background magnetic field. Numerical simulations of the Gross-Pitaevskii equations for our system show that dephasing due to spatial dynamics driven by interparticle interactions accounts for much of the observed decay in fringe visibility at long interrogation times. The simulations show good agreement with the experimental data when additional technical decoherence is accounted for, and suggest that the clock states are indeed immiscible. With smaller samples of 5 × 104 atoms, we observe a coherence time of ? = 1.0+0.5-0.3 s.

Altin, P. A.; McDonald, G.; Döring, D.; Debs, J. E.; Barter, T. H.; Robins, N. P.; Close, J. D.; Haine, S. A.; Hanna, T. M.; Anderson, R. P.

2011-11-01

114

Mass Media Displacement and Saturation  

Microsoft Academic Search

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

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

2008-01-01

115

Universal ac conduction in large area atomic layers of CVD-grown MoS2  

NASA Astrophysics Data System (ADS)

Here, we report on the ac conductivity [?'(?);10mHzatomically thin, two-dimensional layers of MoS2 grown by chemical vapor deposition (CVD). ?'(?) is observed to display a "universal" power law, i.e., ?'(?)˜?s measured within a broad range of temperatures, 10 K atomically thin, CVD-grown MoS2 layers.

Ghosh, S.; Najmaei, S.; Kar, S.; Vajtai, R.; Lou, J.; Pradhan, N. R.; Balicas, L.; Ajayan, P. M.; Talapatra, S.

2014-03-01

116

GRASP92: a package for large-scale relativistic atomic structure calculations  

NASA Astrophysics Data System (ADS)

Program summaryTitle of program: GRASP92 Catalogue identifier: ADCU_v1_1 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADCU_v1_1 Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Licensing provisions: no Programming language used: Fortran Computer: IBM POWERstation 320H Operating system: IBM AIX 3.2.5+ RAM: 64M words No. of lines in distributed program, including test data, etc.: 65 224 No of bytes in distributed program, including test data, etc.: 409 198 Distribution format: tar.gz Catalogue identifier of previous version: ADCU_v1_0 Journal reference of previous version: Comput. Phys. Comm. 94 (1996) 249 Does the new version supersede the previous version?: Yes Nature of problem: Prediction of atomic spectra—atomic energy levels, oscillator strengths, and radiative decay rates—using a 'fully relativistic' approach. Solution method: Atomic orbitals are assumed to be four-component spinor eigenstates of the angular momentum operator, j=l+s, and the parity operator ?=??. Configuration state functions (CSFs) are linear combinations of Slater determinants of atomic orbitals, and are simultaneous eigenfunctions of the atomic electronic angular momentum operator, J, and the atomic parity operator, P. Lists of CSFs are either explicitly prescribed by the user or generated from a set of reference CSFs, a set of subshells, and rules for deriving other CSFs from these. Approximate atomic state functions (ASFs) are linear combinations of CSFs. A variational functional may be constructed by combining expressions for the energies of one or more ASFs. Average level (AL) functionals are weighted sums of energies of all possible ASFs that may be constructed from a set of CSFs; the number of ASFs is then the same as the number, n, of CSFs. Optimal level (OL) functionals are weighted sums of energies of some subset of ASFs; the GRASP92 package is optimized for this latter class of functionals. The composition of an ASF in terms of CSFs sharing the same quantum numbers is determined using the configuration-interaction (CI) procedure that results upon varying the expansion coefficients to determine the extremum of a variational functional. Radial functions may be determined by numerically solving the multiconfiguration Dirac-Fock (MCDF) equations that result upon varying the orbital radial functions or some subset thereof so as to obtain an extremum of the variational functional. Radial wavefunctions may also be determined using a screened hydrogenic or Thomas-Fermi model, although these schemes generally provide initial estimates for MCDF self-consistent-field (SCF) calculations. Transition properties for pairs of ASFs are computed from matrix elements of multipole operators of the electromagnetic field. All matrix elements of CSFs are evaluated using the Racah algebra. Reasons for the new version: During recent studies using the general relativistic atomic structure package (GRASP92), several errors were found, some of which might have been present already in the earlier GRASP92 version (program ABJN_v1_0, Comput. Phys. Comm. 55 (1989) 425). These errors were reported and discussed by Froese Fischer, Gaigalas, and Ralchenko in a separate publication [C. Froese Fischer, G. Gaigalas, Y. Ralchenko, Comput. Phys. Comm. 175 (2006) 738-744. [7

Parpia, F. A.; Froese Fischer, C.; Grant, I. P.

2006-12-01

117

High-resolution and large dynamic range nanomechanical mapping in tapping-mode atomic force microscopy  

Microsoft Academic Search

High spatial resolution imaging of material properties is an important task for the continued development of nanomaterials and studies of biological systems. Time-varying interaction forces between the vibrating tip and the sample in a tapping-mode atomic force microscope contain detailed information about the elastic, adhesive, and dissipative response of the sample. We report real-time measurement and analysis of the time-varying

Ozgur Sahin; Natalia Erina

2008-01-01

118

Low photon scattering rates and large optical depths of atoms in donut modes of hollow core optical fibers  

NASA Astrophysics Data System (ADS)

We have guided cold rubidium atoms in blue-detuned hollow optical modes of a hollow fiber. These higher order modes allow large optical depth, low scattering rates, and efficient use of guide laser power. Atoms are transported through a 3-cm-long hollow fiber with a 100 micron diameter using the first three optical modes of the fiber. We compare guiding properties in the red-detuned, fundamental HE11 mode with the blue-detuned TE01 (first order) and HE12 (second order) modes. Using guide laser powers below 50 mW and detunings below 1.5 nm, we have directly measured recoil scattering rates in the three different guides and found that atoms in the HE12 mode typically have a 10x lower recoil scattering rate compared to the red-detuned HE11 mode for equal guide peak intensity. Furthermore, we have observed optical depths of ˜20 for the blue-detuned guides with recoil scattering rates below 10 Hz. We will discuss our ongoing experiments using the atoms in these guides. This work supported by the Office of Naval Research and the Defense Advanced Research Projects Agency.

Pechkis, Joseph A.; Fatemi, Fredrik K.

2012-06-01

119

On the performance of large Gaussian basis sets for the computation of total atomization energies  

NASA Technical Reports Server (NTRS)

The total atomization energies of a number of molecules have been computed using an augmented coupled-cluster method and (5s4p3d2f1g) and 4s3p2d1f) atomic natural orbital (ANO) basis sets, as well as the correlation consistent valence triple zeta plus polarization (cc-pVTZ) correlation consistent valence quadrupole zeta plus polarization (cc-pVQZ) basis sets. The performance of ANO and correlation consistent basis sets is comparable throughout, although the latter can result in significant CPU time savings. Whereas the inclusion of g functions has significant effects on the computed Sigma D(e) values, chemical accuracy is still not reached for molecules involving multiple bonds. A Gaussian-1 (G) type correction lowers the error, but not much beyond the accuracy of the G1 model itself. Using separate corrections for sigma bonds, pi bonds, and valence pairs brings down the mean absolute error to less than 1 kcal/mol for the spdf basis sets, and about 0.5 kcal/mol for the spdfg basis sets. Some conclusions on the success of the Gaussian-1 and Gaussian-2 models are drawn.

Martin, J. M. L.

1992-01-01

120

The survivability of large space-borne reflectors under atomic oxygen and micrometeoroid impact  

NASA Technical Reports Server (NTRS)

Solar dynamic power system mirrors for use on space station and other spacecraft flown in low Earth orbit (LEO) are exposed to the harshness of the LEO environment. Both atomic oxygen and micrometeoroids/space debris can degrade the performance of such mirrors. Protective coatings will be required to protect oxidizable reflecting media, such as silver and aluminum, from atomic oxygen attack. Several protective coating materials have been identified as good candidates for use in this application. The durability of these coating/mirror systems after pinhole defects have been inflicted during their fabrication and deployment or through micrometeoroid/space debris impact once on-orbit is of concern. Studies of the effect of an oxygen plasma environment on protected mirror surfaces with intentionally induced pinhole defects have been conducted at NASA Lewis and are reviewed. It has been found that oxidation of the reflective layer and/or the substrate in areas adjacent to a pinhole defect, but not directly exposed by the pinhole, can occur.

Gulino, D. A.

1987-01-01

121

The survivability of large space-borne reflectors under atomic oxygen and micrometeoroid impact  

NASA Technical Reports Server (NTRS)

Solar dynamic power system mirrors for use on Space Station and other spacecraft flown in low earth orbit (LEO) are exposed to the harshness of the LEO environment. Both atomic oxygen and micrometeoroids/space debris can degrade the performance of such mirrors. Protective coatings will be required to protect oxidizable reflecting media, such as silver and aluminum, from atomic oxygen attack. Several protective coating materials have been identified as good candidates for use in this application. The durability of these coating/mirror systems after pinhole defects have been inflicted during their fabrication and deployment or through micrometeoroid/space debris impact once on-orbit is of concern. Studies of the effect of an oxygen plasma environment on protected mirror surfaces with intentionally induced pinhole defects have been conducted at NASA Lewis and are reviewed. It has been found that oxidation of the reflective layer and/or the substrate in areas adjacent to a pinhole defect, but not directly exposed by the pinhole, can occur.

Gulino, Daniel A.

1987-01-01

122

Direct Observation of Dopant Atom Diffusion in a Bulk Semiconductor Crystal Enhanced by a Large Size Mismatch  

NASA Astrophysics Data System (ADS)

Diffusion is one of the fundamental processes that govern the structure, processing, and properties of materials and it plays a crucial role in determining device lifetimes. However, direct observations of diffusion processes have been elusive and limited only to the surfaces of materials. Here we use an aberration-corrected electron microscope to locally excite and directly image the diffusion of single Ce and Mn dopants inside bulk wurtzite-type AlN single crystals, identifying correlated vacancy-dopant and interstitial-dopant kick-out mechanisms. Using a 200 kV electron beam to supply energy, we observe a higher frequency of dopant jumps for the larger and heavier Ce atoms than the smaller Mn atoms. These observations confirm density-functional-theory-based predictions of a decrease in diffusion barrier for large substitutional atoms. The results show that combining depth sensitive microscopy with theoretical calculations represents a new methodology to investigate diffusion mechanisms, not restricted to surface phenomena, but within bulk materials.

Ishikawa, Ryo; Mishra, Rohan; Lupini, Andrew R.; Findlay, Scott D.; Taniguchi, Takashi; Pantelides, Sokrates T.; Pennycook, Stephen J.

2014-10-01

123

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

124

Elucidating common structural features of human pathogenic variations using large-scale atomic-resolution protein networks.  

PubMed

With the rapid growth of structural genomics, numerous protein crystal structures have become available. However, the parallel increase in knowledge of the functional principles underlying biological processes, and more specifically the underlying molecular mechanisms of disease, has been less dramatic. This notwithstanding, the study of complex cellular networks has made possible the inference of protein functions on a large scale. Here, we combine the scale of network systems biology with the resolution of traditional structural biology to generate a large-scale atomic-resolution interactome-network comprising 3,398 interactions between 2,890 proteins with a well-defined interaction interface and interface residues for each interaction. Within the framework of this atomic-resolution network, we have explored the structural principles underlying variations causing human-inherited disease. We find that in-frame pathogenic variations are enriched at both the interface and in the interacting domain, suggesting that variations not only at interface "hot-spots," but in the entire interacting domain can result in alterations of interactions. Further, the sites of pathogenic variations are closely related to the biophysical strength of the interactions they perturb. Finally, we show that biochemical alterations consequent to these variations are considerably more disruptive than evolutionary changes, with the most significant alterations at the protein interaction interface. PMID:24599843

Das, Jishnu; Lee, Hao Ran; Sagar, Adithya; Fragoza, Robert; Liang, Jin; Wei, Xiaomu; Wang, Xiujuan; Mort, Matthew; Stenson, Peter D; Cooper, David N; Yu, Haiyuan

2014-05-01

125

A New Large Echelle Spectrometer for Measuring Atomic Transition Probabilities of Fe-group Ions  

NASA Astrophysics Data System (ADS)

Accurate atomic transition probabilities for weak lines connected to the ground and low metastable levels of Fe-group ions are needed for elemental abundance studies on metal-poor stars. Metal-poor stars represent the oldest observable stellar generation and offer a direct probe into the early history of nucleosynthesis and the chemical evolution of the Galaxy. Unexplained trends in relative Fe-group abundances, such as [Co/Cr], as a function of metallicity, or [Fe/H], have been observed. These trends may result from a breakdown in the local thermodynamic equilibrium (LTE) approximation used in traditional photosphere models underlying elemental abundance determinations. The ground and low metastable levels of Fe-group ions contain most of the Fe-group material in a stellar photosphere, and thus second spectra lines with low E.P.s are essentially immune to non-LTE effects. To improve lab data on important Fe-group lines we have developed a novel instrument based on a 3 meter focal length vacuum echelle spectrograph combined with an aberration corrected cross dispersion system and a UV sensitive CCD array. This spectrometer is capable of recording both emission and absorption spectra with high resolving power, very broad wavelength coverage, and high signal-to-noise. It is also free from the multiplex noise of a FTS, making it ideally suited for measuring branching fractions of very weak lines. The combination of very accurate branching fractions with radiative lifetimes from time-resolved laser-induced fluorescence will yield accurate absolute transition probabilities of weak second spectra lines with low E.P.s for the Fe-group elements. Instrument design and preliminary results will be presented. Supported by NASA Grant NNX09AL13G.

Wood, Michael; Lawler, J. E.

2012-01-01

126

Linking Species Traits to the Abiotic Template of Flowing Waters: Contrasting Eco physiologies Underlie Displacement of Zebra Mussels by Quagga Mussels in a Large River-Estuary  

NASA Astrophysics Data System (ADS)

The St. Lawrence River-Estuary was the gateway of entry for dreissenids to North America and holds some of the oldest populations. The St. Lawrence also has four distinct physical-chemical water masses (a regional scale abiotic template) that both species inhabit. Despite their ecological similarities, quagga mussels are supplanting zebra mussels in much of their shared range. In order to try to better understand the changing distributions of these two species we compared glycogen, shell mass and tissue biomass in each of the water masses. This comparative physiological combined with experimental approaches (estuarine salinity experiments and reciprocal transplants) showed that while quagga mussels should dominate in most habitats, that abiotic/bioenergetic constraints in two regions (the Ottawa River plume and the freshwater-marine transition zone) might prevent them from dominating these locations. These findings are an example of how the interaction of landscape scale abiotic heterogeneity and a species-specific physiology can have strong impacts of distribution of biota large rivers.

Casper, A. F.

2005-05-01

127

Accelerating solidification process simulation for large-sized system of liquid metal atoms using GPU with CUDA  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulation is a powerful tool to simulate and analyze complex physical processes and phenomena at atomic characteristic for predicting the natural time-evolution of a system of atoms. Precise simulation of physical processes has strong requirements both in the simulation size and computing timescale. Therefore, finding available computing resources is crucial to accelerate computation. However, a tremendous computational resource (GPGPU) are recently being utilized for general purpose computing due to its high performance of floating-point arithmetic operation, wide memory bandwidth and enhanced programmability. As for the most time-consuming component in MD simulation calculation during the case of studying liquid metal solidification processes, this paper presents a fine-grained spatial decomposition method to accelerate the computation of update of neighbor lists and interaction force calculation by take advantage of modern graphics processors units (GPU), enlarging the scale of the simulation system to a simulation system involving 10 000 000 atoms. In addition, a number of evaluations and tests, ranging from executions on different precision enabled-CUDA versions, over various types of GPU (NVIDIA 480GTX, 580GTX and M2050) to CPU clusters with different number of CPU cores are discussed. The experimental results demonstrate that GPU-based calculations are typically 9?11 times faster than the corresponding sequential execution and approximately 1.5?2 times faster than 16 CPU cores clusters implementations. On the basis of the simulated results, the comparisons between the theoretical results and the experimental ones are executed, and the good agreement between the two and more complete and larger cluster structures in the actual macroscopic materials are observed. Moreover, different nucleation and evolution mechanism of nano-clusters and nano-crystals formed in the processes of metal solidification is observed with large-sized system.

Jie, Liang; Li, KenLi; Shi, Lin; Liu, RangSu; Mei, Jing

2014-01-01

128

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

129

Job Displacement and Labor Market Mobility. Final Report.  

ERIC Educational Resources Information Center

A study examined the labor market mobility of displaced workers, using a new data file that matches the January 1984, 1986, and 1988 Displaced Worker Surveys (DWS) to the March Current Population Surveys in the same years. This large database provides information on displaced workers and their families and permits comparison of the geographic…

Podgursky, Michael; Swaim, Paul

130

Large displacement fast conducting polymer actuators  

E-print Network

Conducting polymers are a promising class of electroactive materials that undergo volumetric changes under applied potentials, which make them particularly useful for many actuation applications. Polypyrrole , is one of ...

Chen, Angela Y. (Angela Ying-Ju), 1982-

2006-01-01

131

Tracking Nanostructural Evolution in Alloys: Large-Scale Analysis of Atom Probe Tomography Data on Blue Gene\\/L  

Microsoft Academic Search

The advent of Local Electrode Atom Probe (LEAP) tomography is revolutionizing materials science by enabling near atomic scale imaging of materials. Analysis of three-dimensional atom probe tomography (APT) data holds the promise of relating combinatorial arrangement of atoms to material properties and enable better design and synthesis of complex materials. Existing techniques, which are serial and require O(n2) work for

Sudip Seal; Michael Moody; Anna Ceguerra; Simon Ringer; Krishna Rajan; Srinivas Aluru

2008-01-01

132

Continuous Displacement Formulation of Alloys  

NASA Astrophysics Data System (ADS)

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

Kikuchi, Ryoichi

1999-06-01

133

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

134

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

135

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

136

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

NASA Astrophysics Data System (ADS)

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

Ivanov, K. G.

2010-12-01

137

Displaced Homemakers: Unresolved Issues.  

ERIC Educational Resources Information Center

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

Zawada, Mary Ann

1980-01-01

138

Control rod displacement  

Microsoft Academic Search

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

Nakazato

1987-01-01

139

Helium effects on displacement cascades in ?-iron  

NASA Astrophysics Data System (ADS)

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

Lucas, G.; Schäublin, R.

2008-10-01

140

Evidencing `Tight Bound States' in the Hydrogen Atom:. Empirical Manipulation of Large-Scale XD in Violation of QED  

NASA Astrophysics Data System (ADS)

In this work we extend Vigier's recent theory of `tight bound state' (TBS) physics and propose empirical protocols to test not only for their putative existence, but also that their existence if demonstrated provides the 1st empirical evidence of string theory because it occurs in the context of large-scale extra dimensionality (LSXD) cast in a unique M-Theoretic vacuum corresponding to the new Holographic Anthropic Multiverse (HAM) cosmological paradigm. Physicists generally consider spacetime as a stochastic foam containing a zero-point field (ZPF) from which virtual particles restricted by the quantum uncertainty principle (to the Planck time) wink in and out of existence. According to the extended de Broglie-Bohm-Vigier causal stochastic interpretation of quantum theory spacetime and the matter embedded within it is created annihilated and recreated as a virtual locus of reality with a continuous quantum evolution (de Broglie matter waves) governed by a pilot wave - a `super quantum potential' extended in HAM cosmology to be synonymous with the a `force of coherence' inherent in the Unified Field, UF. We consider this backcloth to be a covariant polarized vacuum of the (generally ignored by contemporary physicists) Dirac type. We discuss open questions of the physics of point particles (fermionic nilpotent singularities). We propose a new set of experiments to test for TBS in a Dirac covariant polarized vacuum LSXD hyperspace suggestive of a recently tested special case of the Lorentz Transformation put forth by Kowalski and Vigier. These protocols reach far beyond the recent battery of atomic spectral violations of QED performed through NIST.

Amoroso, Richard L.; Vigier, Jean-Pierre

2013-09-01

141

Displacement and Velocity Ratios  

NSDL National Science Digital Library

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

Bourassa, James; Rosz, John

2011-04-05

142

The Displaced Aggression Questionnaire  

Microsoft Academic Search

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

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

2006-01-01

143

Above Water: Buoyancy & Displacement  

NSDL National Science Digital Library

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

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

2006-01-01

144

Displacement Based Multilevel Structural Optimization  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

145

Crack-opening displacement transducer  

NASA Technical Reports Server (NTRS)

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

Simonds, R. A.

1980-01-01

146

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

147

A cold-atoms based processor for deterministic quantum computation with one qubit in intractably large Hilbert spaces  

NASA Astrophysics Data System (ADS)

We propose the use of Rydberg interactions and ensembles of cold atoms in mixed state for the implementation of a protocol for deterministic quantum computation with one quantum bit that can be readily operated in high dimensional Hilbert spaces. We propose an experimental test for the scalability of the protocol and to study the physics of discord. Furthermore, we explore the possibility of extending to non-trivial unitaries, such as those associated to many-body physics. Finally develop a scheme to add control to cold atom unitaries in order to facilitate their implementation in our proposal.

Mansell, C. W.; Bergamini, S.

2014-05-01

148

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

149

Large-scale displacement along the Median Tectonic Line, Japan: evidence from SHRIMP zircon U-Pb dating of granites and gneisses from the South Kitakami and paleo-Ryoke belts  

NASA Astrophysics Data System (ADS)

In this paper we present new U-Pb zircon ages determined with Sensitive High-Resolution Ion MicroProbe (SHRIMP) for nine plutonic rocks or orthogneisses and one paragneiss from the Higo and Maana belts (here referred to as the paleo-Ryoke belt) in southwest Japan, and the South Kitakami belt in northeast Japan. Both belts are Paleozoic-Mesozoic continental terranes discontinuously distributed along the Median Tectonic Line (MTL), and structurally lying on the Sambagawa belt in the Japanese Islands. Three groups of U-Pb zircon ages showing the timing of different magmatic events were determined for the plutonic rock or orthogneiss samples: ca. 500 Ma (Early Ordovician, two samples), a mean age of 292.0±12.4 Ma (Late Carboniferous-Early Permian, one sample) and ca. 110 Ma (Early Cretaceous, six samples). Furthermore, zircons with core-rim microstructures from a garnet-biotite-cordierite paragneiss in the Higo belt were also dated with SHRIMP. The cores yielded 2155-184 Ma inherited U-Pb ages (mostly varying between 330 and 184 Ma), while the rims yielded a mean age of 116.5±18.7 Ma (Early Cretaceous) U-Pb recrystallization ages comparable with the igneous ages, limiting the sedimentary age of the protolith to between Early-Middle Jurassic (ca. 180 Ma) and Early Cretaceous time. These SHRIMP U-Pb ages of plutonism, metamorphism and sedimentation, together with previously reported radiometric ages, have revealed a strong similarity in the tectonic histories of the paleo-Ryoke and South Kitakami and Abukuma belts, suggesting that these belts can be correlated. At present the paleo-Ryoke belt and the South Kitakami and Abukuma belts are separated by more than 1000 km. However, these belts may have originally comprised a continuous continental terrane that was later displaced and juxtaposed, together with the underlying Sambagawa belt, against the Ryoke belt by large-scale sinistral faulting along the MTL and associated major strike-slip faults during the Latest Cretaceous.

Sakashima, Toshihiko; Terada, Kentaro; Takeshita, Toru; Sano, Yuji

2003-07-01

150

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

151

Visualization of a Large Set of Hydrogen Atomic Orbital Contours Using New and Expanded Sets of Parametric Equations  

ERIC Educational Resources Information Center

Atomic orbitals are a theme throughout the undergraduate chemistry curriculum, and visualizing them has been a theme in this journal. Contour plots as isosurfaces or contour lines in a plane are the most familiar representations of the hydrogen wave functions. In these representations, a surface of a fixed value of the wave function ? is plotted…

Rhile, Ian J.

2014-01-01

152

Adapting to variable prismatic displacement  

NASA Technical Reports Server (NTRS)

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

Welch, Robert B.; Cohen, Malcolm M.

1989-01-01

153

CVD synthesis of large-area, highly crystalline MoSe2 atomic layers on diverse substrates and application to photodetectors.  

PubMed

Synthesis of large-area, atomically thin transition metal dichalcogenides (TMDs) on diverse substrates is of central importance for the large-scale fabrication of flexible devices and heterojunction-based devices. In this work, we successfully synthesized a large area of highly-crystalline MoSe2 atomic layers on SiO2/Si, mica and Si substrates using a simple chemical vapour deposition (CVD) method at atmospheric pressure. Atomic force microscopy (AFM) and Raman spectroscopy reveal that the as-grown ultrathin MoSe2 layers change from a single layer to a few layers. Photoluminescence (PL) spectroscopy demonstrates that while the multi-layer MoSe2 shows weak emission peaks, the monolayer has a much stronger emission peak at ? 1.56 eV, indicating the transition from an indirect to a direct bandgap. Transmission electron microscopy (TEM) analysis confirms the single-crystallinity of MoSe2 layers with a hexagonal structure. In addition, the photoresponse performance of photodetectors based on MoSe2 monolayer was studied for the first time. The devices exhibit a rapid response of ? 60 ms and a good photoresponsivity of ? 13 mA/W (using a 532 nm laser at an intensity of 1 mW mm(-2) and a bias of 10 V), suggesting that MoSe2 monolayer is a promising material for photodetection applications. PMID:24965908

Xia, Jing; Huang, Xing; Liu, Ling-Zhi; Wang, Meng; Wang, Lei; Huang, Ben; Zhu, Dan-Dan; Li, Jun-Jie; Gu, Chang-Zhi; Meng, Xiang-Min

2014-08-01

154

The role of energetic displacement cascades in ion beam modifications of materials  

SciTech Connect

The roles of energetic displacement cascades are ubiquitous in the fields of radiation damage and ion beam modifications of materials. These roles can be described on two time scales. For the first, which lasts approx. =10/sup -11/ s, small cascade volumes are characterized by large supersaturations of point defects and energy densities in excess of some tenths of eV's per atom. During this period, the system can be driven far from equilibrium with significant rearrangement of target atoms and the production of Frenkel pairs. Studies of ion beam mixing in conjunction with molecular dynamics computer simulations, have contributed largely toward understanding these dynamic cascade processes. At later times, the microstructure of the material evolves as cascades begin to overlap, or at elevated temperatures, point defects migrate away from their nascent cascades. It is shown how the primary state of damage in cascades influences this microstructural development. Examples involving radiation enhanced diffusion and ion-induced amorphization are discussed. 40 refs.

Averback, R.S.; Kim, S.J.; Diaz de la Rubia, T.

1986-12-01

155

Tourist displacement in two South African sport mega-events  

Microsoft Academic Search

Crowding-out (or displacement) of non-event visitors has received little attention in the literature on the impact of sports events, largely because it cannot be measured accurately. This paper discusses such effects in conceptual terms and reports the results of an analysis of data on tourist arrivals in South Africa aimed at estimating the displacement effects of two sports events held

Johan Fourie; Krige Siebrits; Karly Spronk

2011-01-01

156

Variable displacement blower  

DOEpatents

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

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

1986-01-01

157

Are large concentration of atomic H storable in tritium-impregnated solid in H2 below 0.10 K  

NASA Technical Reports Server (NTRS)

The storage and release of atomic hydrogen produced by the beta decay of tritium contained in a crystalline solid H2 matrix at concentrations greater than 2% and temperatures below 0.80 K are investigated. The temperature of a sample chamber containing tritium-impregnated H2 and placed in the mixing chamber of a dilution refrigerator was measured as the chamber was heated and cooled in order to determine the rates of energy storage and release. It is found that for samples containing 1.2 wt.% tritium, after storage at 0.054 K for 40 h, an increase in sample temperature to a trigger point of 0.17 K leads to an energy release due to the destabilization of atomic H in H2 as predicted by the phenomenological rate process theory. For a tritium weight fraction of 2.5%, energy releases were triggered at 0.54 and 0.82 K after storage at 0.080 K, indicating the trapping of H atoms at the sites of T2 and HT molecules in the sample. The application of a 15 kG magnetic field is shown to increase the storage capacity of T2 traps while reducing that of HT traps, and to lower the trigger temperatures of both. Results suggest that the direct conversion of nuclear energy to chemical energy may become technically feasible in the future.

Rosen, G.; Webeler, R. W. H.

1979-01-01

158

The atomic strain tensor  

SciTech Connect

A definition of the local atomic strain increments in three dimensions and an algorithm for computing them is presented. An arbitrary arrangement of atoms is tessellated in to Delaunay tetrahedra, identifying interstices, and Voronoi polyhedra, identifying atomic domains. The deformation gradient increment tensor for interstitial space is obtained from the displacement increments of the corner atoms of Delaunay tetrahedra. The atomic site strain increment tensor is then obtained by finding the intersection of the Delaunay tetrahedra with the Voronoi polyhedra, accumulating the individual deformation gradient contributions of the intersected Delaunay tetrahedra into the Voronoi polyhedra. An example application is discussed, showing how the atomic strain clarifies the relative local atomic movement for a polymeric glass treated at the atomic level. 6 refs. 10 figs.

Mott, P.H.; Argon, A.S. (Massachusetts Institute of Technology, Cambridge, MA (United States)); Suter, U.W. (Institut fuer Polymere, Zuerich (Switzerland) Massachusetts Institute of Technology, Cambridge, MA (United States))

1992-07-01

159

Development of a high dynamic range spectroscopic system for observation of neutral hydrogen atom density distribution in Large Helical Device core plasma  

NASA Astrophysics Data System (ADS)

We report development of a high dynamic range spectroscopic system comprising a spectrometer with 30% throughput and a camera with a low-noise fast-readout complementary metal-oxide semiconductor sensor. The system achieves a 106 dynamic range (˜20 bit resolution) and an instrumental function approximated by a Voigt profile with Gauss and Lorentz widths of 31 and 0.31 pm, respectively, for 656 nm light. The application of the system for line profile observations of the Balmer-? emissions from high temperature plasmas generated in the Large Helical Device is also presented. In the observed line profiles, emissions are detected in far wings more than 1.0 nm away from the line center, equivalent to neutral hydrogen atom kinetic energies above 1 keV. We evaluate atom density distributions in the core plasma by analyzing the line profiles.

Fujii, K.; Atsumi, S.; Watanabe, S.; Shikama, T.; Goto, M.; Morita, S.; Hasuo, M.

2014-02-01

160

Iraq's housing crisis : upgrading settlements for IDPS (internally displaced persons)  

E-print Network

The most recent war in Iraq has resulted in a large wave of internal and external displacement with increased sectarian violence and ethnic tension. Subsequent conflict has exacerbated conditions within the nation and ...

Shaikley, Layla Karim

2013-01-01

161

Electron density and transport in top-gated graphene nanoribbon devices: First-principles Green function algorithms for systems containing a large number of atoms  

NASA Astrophysics Data System (ADS)

The recent fabrication of graphene nanoribbon (GNR) field-effect transistors poses a challenge for first-principles modeling of carbon nanoelectronics due to many thousand atoms present in the device. The state of the art quantum transport algorithms, based on the nonequilibrium Green function formalism combined with the density-functional theory (NEGF-DFT), were originally developed to calculate self-consistent electron density in equilibrium and at finite bias voltage (as a prerequisite to obtain conductance or current-voltage characteristics, respectively) for small molecules attached to metallic electrodes where only a few hundred atoms are typically simulated. Here we introduce combination of two numerically efficient algorithms which make it possible to extend the NEGF-DFT framework to device simulations involving large number of atoms. Our first algorithm offers an alternative to the usual evaluation of the equilibrium part of electron density via numerical contour integration of the retarded Green function in the upper complex half-plane. It is based on the replacement of the Fermi function f(E) with an analytic function f˜(E) coinciding with f(E) inside the integration range along the real axis, but decaying exponentially in the upper complex half-plane. Although f˜(E) has infinite number of poles, whose positions and residues are determined analytically, only a finite number of those poles have non-negligible residues. We also discuss how this algorithm can be extended to compute the nonequilibrium contribution to electron density, thereby evading cumbersome real-axis integration (within the bias voltage window) of NEGFs which is very difficult to converge for systems with large number of atoms while maintaining current conservation. Our second algorithm combines the recursive formulas with the geometrical partitioning of an arbitrary multiterminal device into nonuniform segments in order to reduce the computational complexity of the retarded Green function evaluation by extracting only its submatrices required for electron density and transmission function. We illustrate fusion of these two algorithms into the NEGF-DFT-type code by computing charge transfer, charge redistribution and conductance in zigzag- GNR?variable -width-armchair- GNR?zigzag -GNR two-terminal device covered with a gate electrode made of graphene layer as well. The total number of carbon and edge-passivating hydrogen atoms within the simulated central region of this device is ?7000 . Our self-consistent modeling of the gate voltage effect suggests that rather large gate voltage ?3eV might be required to shift the band gap of the proposed AGNR interconnect and switch the transport from insulating into the regime of a single open conducting channel.

Areshkin, Denis A.; Nikoli?, Branislav K.

2010-04-01

162

CVD synthesis of large-area, highly crystalline MoSe2 atomic layers on diverse substrates and application to photodetectors  

NASA Astrophysics Data System (ADS)

Synthesis of large-area, atomically thin transition metal dichalcogenides (TMDs) on diverse substrates is of central importance for the large-scale fabrication of flexible devices and heterojunction-based devices. In this work, we successfully synthesized a large area of highly-crystalline MoSe2 atomic layers on SiO2/Si, mica and Si substrates using a simple chemical vapour deposition (CVD) method at atmospheric pressure. Atomic force microscopy (AFM) and Raman spectroscopy reveal that the as-grown ultrathin MoSe2 layers change from a single layer to a few layers. Photoluminescence (PL) spectroscopy demonstrates that while the multi-layer MoSe2 shows weak emission peaks, the monolayer has a much stronger emission peak at ~1.56 eV, indicating the transition from an indirect to a direct bandgap. Transmission electron microscopy (TEM) analysis confirms the single-crystallinity of MoSe2 layers with a hexagonal structure. In addition, the photoresponse performance of photodetectors based on MoSe2 monolayer was studied for the first time. The devices exhibit a rapid response of ~60 ms and a good photoresponsivity of ~13 mA/W (using a 532 nm laser at an intensity of 1 mW mm-2 and a bias of 10 V), suggesting that MoSe2 monolayer is a promising material for photodetection applications.Synthesis of large-area, atomically thin transition metal dichalcogenides (TMDs) on diverse substrates is of central importance for the large-scale fabrication of flexible devices and heterojunction-based devices. In this work, we successfully synthesized a large area of highly-crystalline MoSe2 atomic layers on SiO2/Si, mica and Si substrates using a simple chemical vapour deposition (CVD) method at atmospheric pressure. Atomic force microscopy (AFM) and Raman spectroscopy reveal that the as-grown ultrathin MoSe2 layers change from a single layer to a few layers. Photoluminescence (PL) spectroscopy demonstrates that while the multi-layer MoSe2 shows weak emission peaks, the monolayer has a much stronger emission peak at ~1.56 eV, indicating the transition from an indirect to a direct bandgap. Transmission electron microscopy (TEM) analysis confirms the single-crystallinity of MoSe2 layers with a hexagonal structure. In addition, the photoresponse performance of photodetectors based on MoSe2 monolayer was studied for the first time. The devices exhibit a rapid response of ~60 ms and a good photoresponsivity of ~13 mA/W (using a 532 nm laser at an intensity of 1 mW mm-2 and a bias of 10 V), suggesting that MoSe2 monolayer is a promising material for photodetection applications. Electronic supplementary information (ESI) available: AFM images and height profile of bilayer and trilayer MoSe2 flakes; A direct transfer method used for preparation of MoSe2 TEM samples. See DOI: 10.1039/c4nr02311k

Xia, Jing; Huang, Xing; Liu, Ling-Zhi; Wang, Meng; Wang, Lei; Huang, Ben; Zhu, Dan-Dan; Li, Jun-Jie; Gu, Chang-Zhi; Meng, Xiang-Min

2014-07-01

163

Electromagnetically induced transparency and four-wave mixing in a cold atomic ensemble with large optical depth  

E-print Network

We report on the delay of optical pulses using electromagnetically induced transparency in an ensemble of cold atoms with an optical depth exceeding 500. To identify the regimes in which four-wave mixing impacts on EIT behaviour, we conduct the experiment in both rubidium 85 and rubidium 87. Comparison with theory shows excellent agreement in both isotopes. In rubidium 87, negligible four-wave mixing was observed and we obtained one pulse-width of delay with 50% efficiency. In rubidium 85, four-wave-mixing contributes to the output. In this regime we achieve a delay-bandwidth product of 3.7 at 50% efficiency, allowing temporally multimode delay, which we demonstrate by compressing two pulses into the memory medium.

J. Geng; G. T. Campbell; J. Bernu; D. Higginbottom; B. M. Sparkes; S. M. Assad; W. P. Zhang; N. P. Robins; P. K. Lam; B. C. Buchler

2014-08-11

164

Large-scale analysis of high-speed atomic force microscopy data sets using adaptive image processing  

PubMed Central

Summary Modern high-speed atomic force microscopes generate significant quantities of data in a short amount of time. Each image in the sequence has to be processed quickly and accurately in order to obtain a true representation of the sample and its changes over time. This paper presents an automated, adaptive algorithm for the required processing of AFM images. The algorithm adaptively corrects for both common one-dimensional distortions as well as the most common two-dimensional distortions. This method uses an iterative thresholded processing algorithm for rapid and accurate separation of background and surface topography. This separation prevents artificial bias from topographic features and ensures the best possible coherence between the different images in a sequence. This method is equally applicable to all channels of AFM data, and can process images in seconds. PMID:23213638

Erickson, Blake W; Coquoz, Severine; Adams, Jonathan D; Burns, Daniel J

2012-01-01

165

Electromagnetically induced transparency and four-wave mixing in a cold atomic ensemble with large optical depth  

NASA Astrophysics Data System (ADS)

We report on the delay of optical pulses using electromagnetically induced transparency (EIT) in an ensemble of cold atoms with an optical depth exceeding 500. To identify the regimes in which four-wave mixing (4WM) impacts on EIT behaviour, we conduct the experiment in both 85Rb and 87Rb. Comparison with theory shows excellent agreement in both isotopes. In 87Rb negligible 4WM was observed and we obtained one pulse-width of delay with 50% efficiency. In 85Rb 4WM contributes to the output. In this regime we achieve a delay-bandwidth product of 3.7 at 50% efficiency, allowing temporally multimode delay, which we demonstrate by compressing two pulses into the memory medium.

Geng, J.; Campbell, G. T.; Bernu, J.; Higginbottom, D. B.; Sparkes, B. M.; Assad, S. M.; Zhang, W. P.; Robins, N. P.; Lam, P. K.; Buchler, B. C.

2014-11-01

166

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.

167

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

168

On the intersection of the shell, collective and cluster models of atomic nuclei II: Symmetry-breaking and large deformations  

E-print Network

We discuss the role of the broken symmetries in the connection of the shell, collective and cluster models. The cluster-shell competition is described in terms of cold quantum phases. Stable quasi-dynamical U(3) symmetry is found for specific large deformations for a Nilsson-type Hamiltonian.

J. Cseh; J. Darai

2014-04-14

169

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

170

Low-temperature in situ large strain plasticity of ceramic SiC nanowires and its atomic-scale mechanism.  

PubMed

Large strain plasticity is phenomenologically defined as the ability of a material to exhibit an exceptionally large deformation rate during mechanical deformation. It is a property that is well established for metals and alloys but is rarely observed for ceramic materials especially at low temperature ( approximately 300 K). With the reduction in dimensionality, however, unusual mechanical properties are shown by ceramic nanomaterials. In this Letter, we demonstrated unusually large strain plasticity of ceramic SiC nanowires (NWs) at temperatures close to room temperature that was directly observed in situ by a novel high-resolution transmission electron microscopy technique. The continuous plasticity of the SiC NWs is accompanied by a process of increased dislocation density at an early stage, followed by an obvious lattice distortion, and finally reaches an entire structure amorphization at the most strained region of the NW. These unusual phenomena for the SiC NWs are fundamentally important for understanding the nanoscale fracture and strain-induced band structure variation for high-temperature semiconductors. Our result may also provide useful information for further studying of nanoscale elastic-plastic and brittle-ductile transitions of ceramic materials with superplasticity. PMID:17298014

Han, X D; Zhang, Y F; Zheng, K; Zhang, X N; Zhang, Z; Hao, Y J; Guo, X Y; Yuan, J; Wang, Z L

2007-02-01

171

Molecular-dynamics simulation of threshold displacement energies in lithium aluminate  

NASA Astrophysics Data System (ADS)

Threshold displacement energies in LiAlO2 were evaluated using molecular dynamics technique. A pairwise potential model was adopted for simplicity, with reliance on high ionicity of LiAlO2. In all the three elements, the threshold displacement energy varied considerably depending on the displacement direction of the primary knock-on atom. The average displacement energies of Li, O and Al over 342 displacement directions were evaluated to be 22, 37 and 84 eV, respectively. The order of these values are consistent with the number of generated defects in displacement cascade simulation with initial PKA energy of 1-5 keV, where the number of generated defects was the largest in Li and the smallest in Al in proportion to the number of atoms included in the system, regardless of the initial PKA energy.

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

2011-07-01

172

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

173

Literature Review of Displacement Ventilation  

E-print Network

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

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

174

Gamma rays from atomic and molecular gas in the large complex of clouds in Orion and Monoceros  

NASA Technical Reports Server (NTRS)

A comparison of COS-B gamma-ray observations of the large complex of interstellar clouds in Orion and Monoceros with the Columbia CO and Berkeley H I surveys of this region reveals a good correlation between gamma-ray emission and total gas distribution. The observed gamma-ray emission is explainable in terms of interactions of cosmic rays that are uniformly distributed in this region with the interstellar gas. The correlation is used as the basis of a calibration of the ratio between H2 column density and the integrated CO line intensity; the value of (2.6 + or - 1.2) X 10 to the 20th mol/sq cm K km s thereby obtained is consistent with the value derived from a similar analysis for the inner galaxy.

Bloemen, J. B. G. M.; Caraveo, P. A.; Hermsen, W.; Lebrun, F.; Maddalena, R. J.; Strong, A. W.; Thaddeus, P.

1984-01-01

175

Atomic structure from large-area, low-dose exposures of materials: A new route to circumvent radiation damage?  

PubMed Central

Beam-induced structural modifications are a major nuisance in the study of materials by high-resolution electron microscopy. Here, we introduce a new approach to circumvent the radiation damage problem by a statistical treatment of large, noisy, low-dose data sets of non-periodic configurations (e.g. defects) in the material. We distribute the dose over a mixture of different defect structures at random positions and with random orientations, and recover representative model images via a maximum likelihood search. We demonstrate reconstructions from simulated images at such low doses that the location of individual entities is not possible. The approach may open a route to study currently inaccessible beam-sensitive configurations. PMID:24315660

Meyer, J.C.; Kotakoski, J.; Mangler, C.

2014-01-01

176

Measurement of axial injection displacement with trim coil current unbalance.  

PubMed

The Dee probe used for measuring internal radial beam intensity shows large losses inside the radius of 20 cm of the 88 in. cyclotron. The current of the top and bottom innermost trim coil 1 is unbalanced to study effects of the axial injection displacement. A beam profile monitor images the ion beam bunches, turn by turn. The experimental bunch center of mass position is compared with calculations of the magnetic mirror effect displacement and shows good agreement. PMID:25173318

Kireeff Covo, Michel

2014-08-01

177

Nanoliter Reactors Improve Multiple Displacement Amplification  

E-print Network

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

Quake, Stephen R.

178

Competitive adsorption, displacement, and transport of organic matter on iron oxide: II. Displacement and transport  

SciTech Connect

The competitive interactions between organic matter compounds and mineral surfaces are poorly understood, yet these interactions may play a significant role in the stability and co-transport of mineral colloids and/or environmental contaminants. In this study, the processes of competitive adsorption, displacement, and transport of Suwannee River natural organic matter (SR-NOM) are investigated with several model organic compounds in packed beds of iron oxide-coated quartz columns. Results demonstrated that strongly-binding organic compounds are competitively adsorbed and displace those weakly-bound organic compounds along the flow path. Among the four organic compounds studied, polyacrylic acid (PAA) appeared to be the most competitive, whereas SR-NOM was more competitive than phthalic and salicylic acids. A diffuse adsorption and sharp desorption front (giving an appearance of irreversible adsorption) of the SR-NOM breakthrough curves are explained as being a result of the competitive time-dependent adsorption and displacement processes between different organic components within the SR-NOM. The stability and transport of iron oxide colloids varied as one organic component competitively displaces another. Relatively large quantities of iron oxide colloids are transported when the more strongly-binding PAA competitively displaces the weakly-binding SR-NOM or when SR-NOM competitively displaces phthalic and salicylic acids. Results of this study suggest that the chemical composition and hence the functional behavior of NOM (e.g., in stabilizing mineral colloids and in complexing contaminants) can change along its flow path as a result of the dynamic competitive interactions between heterogeneous NOM subcomponents. Further studies are needed to better define and quantify these NOM components as well as their roles in contaminant partitioning and transport. 37 refs., 10 figs.

Gu, B; Mehlhorn, T.L.; Liang, Liyuan [Oak Ridge National Lab., TN (United States)] [and others] [Oak Ridge National Lab., TN (United States); and others

1996-08-01

179

Evolution of atomic rearrangements in deformation in metallic glasses  

NASA Astrophysics Data System (ADS)

Atomic rearrangements induced by shear stress are fundamental for understanding deformation mechanisms in metallic glasses (MGs). Using molecular dynamic simulation, the atomic rearrangements characterized by nonaffine displacements (NADs) and their spatial distribution and evolution with tensile stress in Cu50Zr50 MG were investigated. It was found that in the elastic regime the atomic rearrangements with the largest NADs are relatively homogeneous in space, but exhibit strong spatial correlation, become localized and inhomogeneous, and form large clusters as strain increases, which may facilitate the so-called shear transformation zones. Furthermore, initially they prefer to take place around Cu atoms which have more nonicosahedral configurations. As strain increases, the preference decays and disappears in the plastic regime. The atomic rearrangements with the smallest NADs are preferentially located around Cu atoms, too, but with more icosahedral or icosahedral-like atomic configurations. The preference is maintained in the whole deformation process. In contrast, the atomic rearrangements with moderate NADs distribute homogeneously, and do not show explicit preference or spatial correlation, acting as matrix during deformation. Among the atomic rearrangements with different NADs, those with largest and smallest NADs are nearest neighbors initially, but separating with increasing strain, while those with largest and moderate NADs always avoid to each other. The correlations in the fluctuations of the NADs confirm the long-range strain correlation and the scale-free characteristic of NADs in both elastic and plastic deformation, which suggests a universality of the scaling in the plastic flow in MGs.

Shang, B. S.; Li, M. Z.; Yao, Y. G.; Lu, Y. J.; Wang, W. H.

2014-10-01

180

A reference material for dynamic displacement calibration  

NASA Astrophysics Data System (ADS)

Calibration of displacement and strain measurement systems is an essential step in providing traceability and confidence in stress and strain distributions obtained from experiment and used to validate simulations employed in engineering design. Reference materials provide a simple, well-defined distribution of the measured quantity that can be traced to an international standard and can be used to assess the uncertainty associated with the measurement system. Previous work has established a reference material and procedure for calibrating optical systems for measuring static, in-plane strain distributions and also demonstrated its use. A new effort is in progress to extend this work to the measurement of three-dimensional displacement distributions induced by cyclic and dynamic loading, including transients and large-scale deformation. The first step in this effort has been to define both the essential and desirable attributes of a reference material for calibrating systems capable of measurements of dynamic displacement and strain. An international consortium of research laboratories, system designers, manufacturers and end-users has identified a list of attributes and members of the experimental mechanics community have been asked to weight the importance of these attributes. The attributes are being utilised to evaluate candidate designs for the reference material which have been generated through a series of brain-storming sessions within the consortium.

Davighi, A.; Hack, E.; Patterson, E.; Whelan, M.

2010-06-01

181

CHARACTER DISPLACEMENT: ECOLOGICAL AND REPRODUCTIVE RESPONSES TO A COMMON EVOLUTIONARY PROBLEM  

PubMed Central

Character displacement – trait evolution stemming from selection to lessen resource competition or reproductive interactions between species – has long been viewed as an important mechanism for enabling closely related species to coexist. Yet, the causes and consequences of character displacement have not been fully explored. Moreover, character displacement in traits associated with resource use (ecological character displacement) has been studied largely independently of that in traits associated with reproduction (reproductive character displacement). Here, we underscore the commonalities of these two forms of character displacement and discuss how they interact. We focus on the causes of character displacement and explore how character displacement can have downstream effects ranging from speciation to extinction. In short, understanding how organisms respond to competitive and reproductive interactions with heterospecifics offers key insights into the evolutionary consequences of species coexistence and diversification. PMID:19764283

Pfennig, Karin S.; Pfennig, David W.

2012-01-01

182

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

183

Cold Atoms  

NASA Astrophysics Data System (ADS)

This chapter and the following one address collective effects of quantum particles, that is, the effects which are observed when we put together a large number of identical particles, for example, electrons, helium-4 or rubidium-85 atoms. We shall see that quantum particles can be classified into two categories, bosons and fermions, whose collective behavior is radically different. Bosons have a tendency to pile up in the same quantum state, while fermions have a tendency to avoid each other. We say that bosons and fermions obey two different quantum statistics, the Bose-Einstein and the Fermi-Dirac statistics, respectively. Temperature is a collective effect, and in Section 5.1 we shall explain the concept of absolute temperature and its relation to the average kinetic energy of molecules. We shall describe in Section 5.2 how we can cool atoms down thanks to the Doppler effect, and explain how cold atoms can be used to improve the accuracy of atomic clocks by a factor of about 100. The effects of quantum statistics are prominent at low temperatures, and atom cooling will be used to obtain Bose-Einstein condensates at low enough temperatures, when the atoms are bosons.

Bellac, Michel Le

2014-11-01

184

Interaction of displacement cascade with helium bubbles in ?-iron: Computer simulation  

NASA Astrophysics Data System (ADS)

Molecular dynamics (MD) method has been performed to study the interaction of displacement cascade with He bubbles with two sets of potentials. The results show that the stability of He bubbles depends much on the initial He-vacancy (He/V) ratio and the recoil energy. For an initial He/V ratio of 3, the cascade leads to the increase in the number of vacancies in the He bubble and the decrease in the He/V ratio. For an initial He/V ratio of 0.5, the interaction of a cascade with the He/V bubble results in the decrease in the number of vacancies and the increase in the He/V ratio. For an initial He/V ratio of 1, the stability of the bubbles slightly depends on the primary knock-on atom (PKA) energy. Furthermore, a large number of self-interstitial atom clusters are formed after cascade collision for the He/V ratio of 3, while large vacancy clusters are observed for the He/V ratio of 0.5. However, some differences of defect production and clustering between the two sets of potentials are observed, which may be associated the formation energies of He-V clusters, the binding energies of vacancies and He atoms to the clusters and the probability of subcascade formation.

Pu, J.; Yang, L.; Gao, F.; Heinisch, H. L.; Kurtz, R. J.; Zu, X. T.

2008-09-01

185

Environment-induced Population Displacements  

E-print Network

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

Columbia University

186

Stochastic Microgeometry for Displacement Mapping  

Microsoft Academic Search

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

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

2005-01-01

187

Tunnel-Effect Displacement Sensor  

NASA Technical Reports Server (NTRS)

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

Kaiser, William J.; Waltman, Steven B.

1989-01-01

188

Retraining Displaced Workers. Policy Brief  

ERIC Educational Resources Information Center

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

LaLonde, Robert; Sullivan, Daniel

2010-01-01

189

Polybenzimidazoles Via Aromatic Nucleophilic Displacement  

NASA Technical Reports Server (NTRS)

Soluble polybenzimidazoles (PBI's) synthesized by nucleophilic displacement reaction of di(hydroxyphenyl)-benzimidazole monomers with activated aromatic difluoride compounds in presence of anhydrous potassium carbonate. These polymers exhibit good thermal, thermo-oxidative, and chemical stability, and high mechanical properties. Using benzimidazole monomers, more economical, and new PBI's processed more easily than commercial PBI, without loss of desirable physical properties.

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

1994-01-01

190

Polyphenylquinoxalines Via Aromatic Nucleophilic Displacement  

NASA Technical Reports Server (NTRS)

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

Hergenrother, Paul M.; Connell, John W.

1991-01-01

191

Experimental measurement of local displacement and chemical pair correlations in crystalline solid solutions  

SciTech Connect

Measurement of near-neighbor atomic arrangements in crystalline solid solutions is well established and provides meaningful values for chemical preference of atoms for their near neighbors to beyond the first ten neighboring shells. Static displacements (atomic size) between these atom pairs have mostly been either ignored in the recovery of the local pair preferences or removed by making use of the displacement scattering dependence on momentum transfer. With intense and energy tunable x-ray synchrotron sources, our ability to recover these static displacements between atoms has greatly improved. Data taken with multiple x-ray energies to obtain the contrast necessary to separate like from unlike neighbor pair distances are discussed for the two cases studied to date: A locally ordered Ni{sub 77.5}Fe{sub 22.5} crystal and a locally clustered Fe{sub 53}Cr{sub 47} crystal. Analysis of experimental parameters and data gives the systematic and statistical errors on the recovered parameters. Meaningful atomic displacements from the mean lattice can be measured and recovered. These displacements help us understand material properties and will provide theorists with tests for their calculations.

Sparks, C.L.; Ice, G.E.; Robertson, J.L. [Oak Ridge National Lab., TN (United States); Shaffer, L.B. [Anderson Univ., Anderson, IN (United States)

1993-10-01

192

Force transmissibility versus displacement transmissibility  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

193

PHON: A program to calculate phonons using the small displacement method  

NASA Astrophysics Data System (ADS)

The program PHON calculates force constant matrices and phonon frequencies in crystals. From the frequencies it also calculates various thermodynamic quantities, like the Helmholtz free energy, the entropy, the specific heat and the internal energy of the harmonic crystal. The procedure is based on the small displacement method, and can be used in combination with any program capable to calculate forces on the atoms of the crystal. In order to examine the usability of the method, I present here two examples: metallic Al and insulating MgO. The phonons of these two materials are calculated using density functional theory. The small displacement method results are compared with those obtained using the linear response method. In the case of Al the method provides accurate phonon frequencies everywhere in the Brillouin Zone (BZ). In the case of MgO the longitudinal branch of the optical phonons near the centre of the BZ is incorrectly described as degenerate with the two transverse branches, because the non-analytical part of the dynamical matrix is ignored here; however, thermodynamic properties like the Helmholtz free are essentially unaffected. Program summaryProgram title: PHON Catalogue identifier: AEDP_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEDP_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 19 580 No. of bytes in distributed program, including test data, etc.: 612 193 Distribution format: tar.gz Programming language: Fortran 90 Computer: Any Unix, Linux Operating system: Unix RAM: Depends on super-cell size, but usually negligible Classification: 7.8 External routines: Subprograms ZHEEV and DSYEV (Lapack); needs BLAS. A tutorial is provided with the distribution which requires the installation of the quantum-espresso package ( http://www.quantum-espresso.org) Nature of problem: Stable crystals at low temperature can be well described by expanding the potential energy around the atomic equilibrium positions. The movements of the atoms around their equilibrium positions can then be described using harmonic theory, and is characterised by global vibrations called phonons, which can be identified by vectors in the Brillouin zone of the crystal, and there are 3 phonon branches for each atom in the primitive cell. The problem is to calculate the frequencies of these phonons for any arbitrary choice of q-vector in the Brillouin zone. Solution method: The small displacement method: each atom in the primitive cell is displaced by a small amount, and the forces induced on all the other atoms in the crystal are calculated and used to construct the force constant matrix. Supercells of ˜100 atoms are usually large enough to describe the force constant matrix up to the range where its elements have fallen to negligibly small values. The force constant matrix is then used to compute the dynamical matrix at any chosen q-vector in the Brillouin zone, and the diagonalisation of the dynamical matrix provides the squares of the phonon frequencies. The PHON code needs external programs to calculate these forces, and it can be used with any program capable of calculating forces in crystals. The most useful applications are obtained with codes based on density functional theory, but there is no restriction on what can be used. Running time: Negligible, typically a few seconds (or at most a few minutes) on a PC. It can take longer if very dense meshes of q-points are needed, for example, to compute very accurate phonon density of states.

Alfè, Dario

2009-12-01

194

Measurement of Cantilever Displacement Using a Compact Disk/Digital Versatile Disk Pickup Head  

NASA Astrophysics Data System (ADS)

We use the optical pickup head of a commercial compact disk (CD)/digital versatile disk (DVD) read only memory (ROM) drive to detect the vertical displacement of micro fabricated cantilever in atomic force microscopy (AFM). Both the contact and AC modes of AFM are demonstrated. The single atomic steps of graphite can be resolved, indicating that atomic resolution in the vertical displacement detection can be achieved with this new setup. The low cost, compact size, and the light weight of CD/DVD optical pickups may offer new advantages in future AFM designs.

Hwu, En?Te; Huang, Kuang?Yuh; Hung, Shao?Kang; Hwang, Ing?Shouh

2006-03-01

195

A high-resolution neutron powder diffraction investigation of galena (PbS) between 10?K and 350?K: no evidence for anomalies in the lattice parameters or atomic displacement parameters in galena or altaite (PbTe) at temperatures corresponding to the saturation of cation disorder  

NASA Astrophysics Data System (ADS)

The temperature dependences of the unit cell parameter and the atomic displacement parameters (adp) for galena (PbS) have been measured using high resolution neutron powder diffraction in the temperature interval 10-350?K. No evidence has been found for the anomalous behaviour recently reported in a total scattering study of galena, in which the temperature variation of both the unit cell and the adp for lead are reported to undergo a dramatic reduction at a temperature of ~250?K. The linear thermal expansion coefficient calculated from the powder diffraction study is found to be in excellent agreement with literature values over the entire temperature interval studied, and approximately 25% greater at room temperature than that determined by analysis of the pair distribution function (pdf) derived from the total scattering data. This discrepancy is shown to be attributable to a linear, temperature-dependent offset from the published temperatures in the total scattering study, and has arisen from the sample temperature being significantly lower than the experimental set point temperature. Applying this correction to the adps of the lead cation removes the anomalous temperature dependence and shows the pdf results are in agreement with the neutron powder diffraction results. Application of the identical temperature offsets to the results of the pdf analysis of data collected on altaite (PbTe) eliminates the anomalous behaviour in the unit cell and the adp for lead, bringing them in line with literature values. Contrary to the conclusions of the pdf analysis, adps for the lead cation in both galena and altaite can be described in terms of Debye-like behaviour and are consistent with the partial phonon density of states.

Knight, K. S.

2014-09-01

196

A high-resolution neutron powder diffraction investigation of galena (PbS) between 10?K and 350?K: no evidence for anomalies in the lattice parameters or atomic displacement parameters in galena or altaite (PbTe) at temperatures corresponding to the saturation of cation disorder.  

PubMed

The temperature dependences of the unit cell parameter and the atomic displacement parameters (adp) for galena (PbS) have been measured using high resolution neutron powder diffraction in the temperature interval 10-350?K. No evidence has been found for the anomalous behaviour recently reported in a total scattering study of galena, in which the temperature variation of both the unit cell and the adp for lead are reported to undergo a dramatic reduction at a temperature of ~250?K. The linear thermal expansion coefficient calculated from the powder diffraction study is found to be in excellent agreement with literature values over the entire temperature interval studied, and approximately 25% greater at room temperature than that determined by analysis of the pair distribution function (pdf) derived from the total scattering data. This discrepancy is shown to be attributable to a linear, temperature-dependent offset from the published temperatures in the total scattering study, and has arisen from the sample temperature being significantly lower than the experimental set point temperature. Applying this correction to the adps of the lead cation removes the anomalous temperature dependence and shows the pdf results are in agreement with the neutron powder diffraction results. Application of the identical temperature offsets to the results of the pdf analysis of data collected on altaite (PbTe) eliminates the anomalous behaviour in the unit cell and the adp for lead, bringing them in line with literature values. Contrary to the conclusions of the pdf analysis, adps for the lead cation in both galena and altaite can be described in terms of Debye-like behaviour and are consistent with the partial phonon density of states. PMID:25185952

Knight, K S

2014-09-24

197

The variability of the large genomic segment of ?ahy?a orthobunyavirus and an all-atom exploration of its anti-viral drug resistance.  

PubMed

?ahy?a virus (TAHV), a member of the Bunyaviridae family (California complex), is an important but neglected human mosquito-borne pathogen. The virus genome is composed of three segments, i.e., small (S), medium (M), and large (L). Previous studies on genetic variability of viruses within the California complex were focused on S and M segments, but the L segment remains relatively unstudied. To assess the genetic variation and the relation to virus phenotype we analyzed the L segment sequences of biologically diverse TAHV strains isolated in the Czech Republic and Slovakia. Phylogenetic analysis covering all available sequences of the L segment of TAHV clearly revealed two distinguished lineages, tentatively named as "European" and "Asian". The L segment strains within the European lineage are highly conserved (identity 99.3%), whilst Asian strains are more genetically diverse (identity 97%). Based on sequence comparison with other bunyaviruses, several non-synonymous nucleotide substitutions unique for TAHV in the L segment were identified. We also identified specific residue substitutions in the endonuclease domain of TAHV compared with the La Crosse virus. Since the endonuclease domain of the La Crosse virus has been resolved, we employed an all energy landscape algorithm to analyze the ligand migration of a viral polymerase inhibitor. This allowed us to demonstrate, at the atomic level, that this viral polymerase inhibitor randomly explored the specific residue substitutions in the endonuclease domain of the TAHV L segment. PMID:24090866

Kilian, Patrik; Valdes, James J; Lecina-Casas, Daniel; Chrudimský, Tomáš; R?žek, Daniel

2013-12-01

198

Method for quantitative determination and separation of trace amounts of chemical elements in the presence of large quantities of other elements having the same atomic mass  

DOEpatents

Photoionization via autoionizing atomic levels combined with conventional mass spectroscopy provides a technique for quantitative analysis of trace quantities of chemical elements in the presence of much larger amounts of other elements with substantially the same atomic mass. Ytterbium samples smaller than 10 ng have been detected using an ArF* excimer laser which provides the atomic ions for a time-of-flight mass spectrometer. Elemental selectivity of greater than 5:1 with respect to lutetium impurity has been obtained. Autoionization via a single photon process permits greater photon utilization efficiency because of its greater absorption cross section than bound-free transitions, while maintaining sufficient spectroscopic structure to allow significant photoionization selectivity between different atomic species. Separation of atomic species from others of substantially the same atomic mass is also described.

Miller, C.M.; Nogar, N.S.

1982-09-02

199

Fiber optic multimode displacement sensor  

Microsoft Academic Search

An underwater Optical Motion Sensor (OMS) based on a design first presented by W. B. Spillman, Schlieren multimode fiber-optic hydrophone, Applied Physics Letters 37(2), 15 July 1980, p. 145-146 is described. The displacement sensor uses the same acoustooptical intensity modulation mechanism as Spillman, however the sensing mechanism is isolated from the ambient fluid environment by a small cylindrical aluminum enclosure

Karl A. Fisher; Jacek Jarzynski

1996-01-01

200

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

201

Knowledge integration and displaced volume  

NSDL National Science Digital Library

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

Linn, Marcia; Eylon, Bat-Sheva

2006-12-07

202

Coupled diffusional/displacive transformations  

E-print Network

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

Mujahid, Shafiq Ahmad

203

Polyphenylquinoxalines via aromatic nucleophilic displacement  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

204

A DISPLACED SUPERMASSIVE BLACK HOLE IN M87  

SciTech Connect

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

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

2010-07-01

205

Anharmonic thermal motion of atoms in thermoelectric Mg2Si studied via convergent-beam electron diffraction  

NASA Astrophysics Data System (ADS)

We study the thermal motion of the atoms in the thermoelectric material Mg2Si by using electron diffraction. The nanodiffraction or convergent-beam electron diffraction technique we use allows us to observe simultaneously many Bragg reflections with large reciprocal lattice vectors. Previous observations of anharmonicity by single-crystal x-ray diffraction are confirmed, and we determine the anharmonicity parameter of the Mg atom in the tetrahedral environment with high accuracy, ?=(-4.27±0.14)×10-12 erg Å-3 around room temperature. In an alternative picture the Mg atom tends to vibrate around positions displaced 4.50±0.14 pm from the center of the tetrahedron.

Valset, K.; Taftø, J.; Wu, L.; Zhu, Y.

2011-12-01

206

Helmholtz decomposition of the Lagrangian displacement  

NASA Astrophysics Data System (ADS)

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

Chan, Kwan Chuen

2014-04-01

207

The everyday violence of forced displacement : community, memory and identity politics among Kurdish internal forced migrants in Turkey  

Microsoft Academic Search

Kurds in Turkey: the everyday violence of their forced displacement. Roughly fifteen years ago, more than one million Kurds were forcibly displaced from their villages in Southeast Turkey, mostly by Turkish security troops, who were engaged in a violent struggle with the PKK, an armed organization that strives for Kurdish self-rule. Large numbers of displaced Kurds migrated to cities in

M. T. Geerse

2011-01-01

208

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

209

Burglary Reduction and the Myth of Displacement  

Microsoft Academic Search

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

Jerry Ratcliffe

2002-01-01

210

Displacement, Space and Dwelling: Placing Gentrification Debate  

Microsoft Academic Search

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

Mark Davidson

2009-01-01

211

Displacement Compensation of Temperature Probe Data  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

212

Defect-Enhanced Charge Transfer by Ion-Solid Interactions in SiC using Large-Scale AbInitio Molecular Dynamics Simulations  

NASA Astrophysics Data System (ADS)

Large-scale ab initio molecular dynamics simulations of ion-solid interactions in SiC reveal that significant charge transfer occurs between atoms, and defects can enhance charge transfer to surrounding atoms. The results demonstrate that charge transfer to and from recoiling atoms can alter the energy barriers and dynamics for stable defect formation. The present simulations illustrate in detail the dynamic processes for charged defect formation. The averaged values of displacement threshold energies along four main crystallographic directions are smaller than those determined by empirical potentials due to charge-transfer effects on recoil atoms.

Gao, Fei; Xiao, Haiyan; Zu, Xiaotao; Posselt, Matthias; Weber, William J.

2009-07-01

213

Polyphenylquinoxalines via Aromatic Nucleophilic Displacement  

NASA Technical Reports Server (NTRS)

Polyphenylquinoxalines are produced by an aromatic nucleophilic displacement reaction involving an activated aromatic dihalide with an appropriate quinoxaline monomer. Polyphenylquinoxalines are high temperature thermoplastics used as adhesives, coatings, films and composite matrices. The novelty of this invention is threefold: (1) some of the quinoxaline monomers are new compositions of matter; (2) the phenylquinoxaline polymers which are the end products of the invention are new compositions of matter; and (3) the method of forming the polymers is novel, replacing a more costly prior art process, which is also limited in the kinds of products prepared therefrom.

Hergenrother, Paul M.; Connell, John W.

1988-01-01

214

Finding activation pathway of coupled displacive-diffusional defect processes in atomistics: Dislocation climb in fcc copper  

E-print Network

The majority of solid-state deformation and transformation processes involve coupled displacive-diffusional mechanisms, of which a detailed atomic picture does not exist. We present here a complete atomistic description ...

Li, Ju

215

Fast Image Upsampling via the Displacement Field.  

PubMed

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

Wang, Lingfeng; Wu, Huaiyu; Pan, Chunhong

2014-12-01

216

Icosahedral quasicrystals as twins of cubic crystals containing large icosahedral clusters of atoms: The 1012-atom primitive cubic structure of Al6CuLi3, the C-phase Al37Cu3Li21Mg3, and GaMg2Zn3  

PubMed Central

Single-grain precession x-ray diffraction photographs of Al6CuLi3 have been successfully indexed on the basis of icosahedral twinning of cubic crystals with a 1012-atom primitive cubic unit with edge 25.70 Å, giving support to the proposal that the so-called icosahedral quasicrystals are twins of crystals containing eight large icosahedral clusters in the ?-W arrangement. In this compound two of the clusters consist of 104 atoms and six consist of 136 atoms, with 24 atoms shared. The same structure is assigned to the C-phase, Al37Cu3Li21Mg3, and to GaMg2Zn3. A theory of icosahedral quasicrystals and amorphous metals is described. PMID:16593929

Pauling, Linus

1988-01-01

217

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

218

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

219

Atom-by-atom nucleation and growth of graphene nanopores  

E-print Network

February 17, 2012 (received for review December 9, 2011) Graphene is an ideal thin membrane substrate been a goal of nanoscale science (1). The recent ad- vent of graphene (2, 3) provides an ideal thin the cross- section for the process, and obtain a mean edge atom displacement energy of 14.1 Ã? 0.1 e

Golovchenko, Jene A.

220

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

221

Large displacement parallel plate electrostatic actuator with saturation type characteristic  

Microsoft Academic Search

We report on a long travel electrostatic actuator operated by parallel plate electrodes. The actuator architecture is based on a folded suspension composed of initially curved beams with an actuating force applied along the beams. The straightening of the beams, which are used simultaneously as motion amplifiers and suspension elements, is transformed into the long stroke lateral motion of the

Slava Krylov; Yacov Bernstein

2006-01-01

222

Study of the fragmentation of a displacement cascade in subcascades within the Binary Collision Approximation framework  

SciTech Connect

When a material is subjected to irradiation, many primary defects are cre- ated at the atomic level by sequences of ballistic collision events to form highly disordered regions defined as displacement cascades. The long term evolution of materials under irradiation is dictated by the number and the spatial distribution of the surviving defects in the displacement cascade. The peculiar power law shape of collision cross sections is responsible for the frag- mentation of a displacement cascade into smaller subcascades. However, it remains difficult to define a subcascade. Within the fractal geometry frame- work, we demonstrate in this work that the set of atomic trajectories in a displacement cascade exhibit a fractal behavior. From this analysis, we present a new criterion to describe the fragmentation of a displacement cas- cade and to calculate the distribution and the number of defects from this fragmentation. Such an analysis provides the natural framework to estimate the number of defects created in a displacement cascade to integrate with results of MD simulations. From this defiintion of the fragmentation of a displacement cascade, this work gives some new insights to describe both the primary defects produced in a material under irradiation and then to compare different irradiations performed with different particles.

Luneville, Laurence [CEA, Saclay, France; Simone, David [CEA, Saclay, France; Weber, William J [ORNL

2011-01-01

223

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

Microsoft Academic Search

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

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

2000-01-01

224

The 2011 Tohoku-Oki earthquake: displacement reaching the trench axis.  

PubMed

We detected and measured coseismic displacement caused by the 11 March 2011 Tohoku-Oki earthquake [moment magnitude (M(W)) 9.0] by using multibeam bathymetric surveys. The difference between bathymetric data acquired before and after the earthquake revealed that the displacement extended out to the axis of the Japan Trench, suggesting that the fault rupture reached the trench axis. The sea floor on the outermost landward area moved about 50 meters horizontally east-southeast and ~10 meters upward. The large horizontal displacement lifted the sea floor by up to 16 meters on the landward slope in addition to the vertical displacement. PMID:22144619

Fujiwara, Toshiya; Kodaira, Shuichi; No, Tetsuo; Kaiho, Yuka; Takahashi, Narumi; Kaneda, Yoshiyuki

2011-12-01

225

Gumdrop Atoms  

NSDL National Science Digital Library

Students use gumdrops and toothpicks to make lithium atom models. Using these models, they investigate the makeup of atoms, including their relative size. Students are then asked to form molecules out of atoms, much in the same way they constructed atoms out of the particles that atoms are made of. Students also practice adding and subtracting electrons from an atom and determining the overall charges on atoms.

Integrated Teaching And Learning Program

226

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

227

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

228

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

229

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

230

Fiber optic multimode displacement sensor  

SciTech Connect

An underwater Optical Motion Sensor (OMS) based on a design first presented by W. B. Spillman, {ital Schlieren} {ital multimode} {ital fiber}-{ital optic} {ital hydrophone}, Applied Physics Letters 37(2), 15 July 1980, p. 145{endash}146 is described. The displacement sensor uses the same acoustooptical intensity modulation mechanism as Spillman, however the sensing mechanism is isolated from the ambient fluid environment by a small cylindrical aluminum enclosure (1{double_prime} OD{times}3/4{double_prime}). The enclosure contains an inertial mass and the fiber collimators. The inertial mass is suspended in the center of the enclosure by three small wires rigidly mounted to the walls. The mass and wires act as a cantilever beam system with a mechanical resonance near 100 Hz. The transduction mechanism consists of two opposed optical gratings aligned and positioned between the fiber collimators. One grating is mounted on the inertial mass while the other is mounted on the lower end cap of the enclosure. Relative motion between the gratings causes a modulation of the light transmitted through the gratings. The modulated beam is focused onto a photodetector and converted to electric current. The frequency response is flat from 200 Hz{endash}9 kHz with a minimum detectable displacement of 0.002 A and the dynamic range is 136 dB. The small size and light weight give the sensor an effective density of 1.08 g/cm{sup 3} making it almost neutrally buoyant in water. This in conjunction with the performance characteristics make this sensor suitable for use in acoustical sensing applications. {copyright} {ital 1996 American Institute of Physics.}

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

1996-04-01

231

Juvenile songbirds compensate for displacement to oceanic islands during autumn migration.  

PubMed

To what degree juvenile migrant birds are able to correct for orientation errors or wind drift is still largely unknown. We studied the orientation of passerines on the Faroe Islands far off the normal migration routes of European migrants. The ability to compensate for displacement was tested in naturally occurring vagrants presumably displaced by wind and in birds experimentally displaced 1100 km from Denmark to the Faroes. The orientation was studied in orientation cages as well as in the free-flying birds after release by tracking departures using small radio transmitters. Both the naturally displaced and the experimentally displaced birds oriented in more easterly directions on the Faroes than was observed in Denmark prior to displacement. This pattern was even more pronounced in departure directions, perhaps because of wind influence. The clear directional compensation found even in experimentally displaced birds indicates that first-year birds can also possess the ability to correct for displacement in some circumstances, possibly involving either some primitive form of true navigation, or 'sign posts', but the cues used for this are highly speculative. We also found some indications of differences between species in the reaction to displacement. Such differences might be involved in the diversity of results reported in displacement studies so far. PMID:21464975

Thorup, Kasper; Ortvad, Troels Eske; Rabøl, Jørgen; Holland, Richard A; Tøttrup, Anders P; Wikelski, Martin

2011-01-01

232

Juvenile Songbirds Compensate for Displacement to Oceanic Islands during Autumn Migration  

PubMed Central

To what degree juvenile migrant birds are able to correct for orientation errors or wind drift is still largely unknown. We studied the orientation of passerines on the Faroe Islands far off the normal migration routes of European migrants. The ability to compensate for displacement was tested in naturally occurring vagrants presumably displaced by wind and in birds experimentally displaced 1100 km from Denmark to the Faroes. The orientation was studied in orientation cages as well as in the free-flying birds after release by tracking departures using small radio transmitters. Both the naturally displaced and the experimentally displaced birds oriented in more easterly directions on the Faroes than was observed in Denmark prior to displacement. This pattern was even more pronounced in departure directions, perhaps because of wind influence. The clear directional compensation found even in experimentally displaced birds indicates that first-year birds can also possess the ability to correct for displacement in some circumstances, possibly involving either some primitive form of true navigation, or ‘sign posts’, but the cues used for this are highly speculative. We also found some indications of differences between species in the reaction to displacement. Such differences might be involved in the diversity of results reported in displacement studies so far. PMID:21464975

Thorup, Kasper; Ortvad, Troels Eske; Rab?l, J?rgen; Holland, Richard A.; T?ttrup, Anders P.; Wikelski, Martin

2011-01-01

233

The Population Genetics of Sperm Displacement  

PubMed Central

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

Prout, Timothy; Bundgaard, J?rgen

1977-01-01

234

An atom in molecules study of infrared intensity enhancements in fundamental donor stretching bands in hydrogen bond formation.  

PubMed

Vibrational modes ascribed to the stretching of X-H bonds from donor monomers (HXdonor) in complexes presenting hydrogen bonds (HFHF, HClHCl, HCNHCN, HNCHNC, HCNHF, HFHCl and H2OHF) exhibit large (4 to 7 times) infrared intensity increments during complexation according to CCSD/cc-pVQZ-mod calculations. These intensity increases are explained by the charge-charge flux-dipole flux (CCFDF) model based on multipoles from the Quantum Theory of Atoms in Molecules (QTAIM) as resulting from a reinforcing interaction between two contributions to the dipole moment derivatives with respect to the vibrational displacements: charge and charge flux. As such, variations that occur in their intensity cross terms in hydrogen bond formation correlate nicely with the intensity enhancements. These stretching modes of HXdonor bonds can be approximately modeled by sole displacement of the positively charged hydrogens towards the acceptor terminal atom with concomitant electronic charge transfers in the opposite direction that are larger than those occurring for the H atom displacements of their isolated donor molecules. This analysis indicates that the charge-charge flux interaction reinforcement on H-bond complexation is associated with variations of atomic charge fluxes in both parent molecules and small electronic charge transfers between them. The QTAIM/CCFDF model also indicates that atomic dipole flux contributions do not play a significant role in these intensity enhancements. PMID:25325528

Terrabuio, Luiz A; Richter, Wagner E; Silva, Arnaldo F; Bruns, Roy E; Haiduke, Roberto L A

2014-10-22

235

Atomic-orbital close-coupling calculations for collisions involving fusion relevant highly charged impurity ions using very large basis sets  

SciTech Connect

The atomic-orbital close-coupling formalism is a well-known method for the semiclassical treatment of ion-atom collisions. Cross sections for these kinds of collisions are mainly needed in the analysis of certain spectroscopic data from nuclear fusion experiments as well as astrophysical data. We shall outline how the computational implementation can be improved in such a way that collisions involving heavy, highly charged impurity ions, such as Ar{sup 18+} can be treated. Furthermore we show and discuss exemplary results.

Igenbergs, Katharina; Wallerberger, Markus; Schweinzer, Josef; Aumayr, Friedrich [Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstr.8-10/134, A-1040 Vienna (Austria); Max-Planck-Institute of Plasma Physics, Boltzmannstr.2, D-85748 Garching (Germany); Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstr.8-10/134, A-1040 Vienna (Austria)

2012-05-25

236

Approaching the Quantum Limits of Displacement Detection  

NASA Astrophysics Data System (ADS)

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

Teufel, John

2013-03-01

237

Character displacement in the fighting colours of Hetaerina damselflies  

PubMed Central

Aggression between species is a seldom-considered but potentially widespread mechanism of character displacement in secondary sexual characters. Based on previous research showing that similarity in wing coloration directly influences interspecific territorial aggression in Hetaerina damselflies, we predicted that wing coloration would show a pattern of character displacement (divergence in sympatry). A geographical survey of four Hetaerina damselfly species in Mexico and Texas showed evidence for character displacement in both species pairs that regularly occurs sympatrically. Hetaerina titia, a species that typically has large black wing spots and small red wing spots, shifted to having even larger black spots and smaller red wing spots at sites where a congener with large red wing spots is numerically dominant (Hetaerina americana or Hetaerina occisa). Hetaerina americana showed the reverse pattern, shifting towards larger red wing spots where H. titia is numerically dominant. This pattern is consistent with the process of agonistic character displacement, but the ontogenetic basis of the shift remains to be demonstrated. PMID:20591870

Anderson, Christopher N.; Grether, Gregory F.

2010-01-01

238

Character displacement in the fighting colours of Hetaerina damselflies.  

PubMed

Aggression between species is a seldom-considered but potentially widespread mechanism of character displacement in secondary sexual characters. Based on previous research showing that similarity in wing coloration directly influences interspecific territorial aggression in Hetaerina damselflies, we predicted that wing coloration would show a pattern of character displacement (divergence in sympatry). A geographical survey of four Hetaerina damselfly species in Mexico and Texas showed evidence for character displacement in both species pairs that regularly occurs sympatrically. Hetaerina titia, a species that typically has large black wing spots and small red wing spots, shifted to having even larger black spots and smaller red wing spots at sites where a congener with large red wing spots is numerically dominant (Hetaerina americana or Hetaerina occisa). Hetaerina americana showed the reverse pattern, shifting towards larger red wing spots where H. titia is numerically dominant. This pattern is consistent with the process of agonistic character displacement, but the ontogenetic basis of the shift remains to be demonstrated. PMID:20591870

Anderson, Christopher N; Grether, Gregory F

2010-12-01

239

Cholesterol Displaces Palmitoylceramide from Its Tight Packing with Palmitoylsphingomyelin in the Absence of a Liquid-Disordered Phase  

PubMed Central

A set of different biophysical approaches has been used to explore the phase behavior of palmitoylsphingomyelin (pSM)/cholesterol (Chol) model membranes in the presence and absence of palmitoylceramide (pCer). Fluorescence spectroscopy of di-4-ANEPPDHQ-stained pSM/Chol vesicles and atomic force microscopy of supported planar bilayers show gel L?/liquid-ordered (Lo) phase coexistence within the range XChol = 0–0.25 at 22°C. At the latter compositional point and beyond, a single Lo pSM/Chol phase is detected. In ternary pSM/Chol/pCer mixtures, differential scanning calorimetry of multilamellar vesicles and confocal fluorescence microscopy of giant unilamellar vesicles concur in showing immiscibility, but no displacement, between Lo cholesterol-enriched (pSM/Chol) and gel-like ceramide-enriched (pSM/pCer) phases at high pSM/(Chol + pCer) ratios. At higher cholesterol content, pCer is unable to displace cholesterol at any extent, even at XChol < 0.25. It is interesting that an opposite strong cholesterol-mediated pCer displacement from its tight packing with pSM is clearly detected, completely abolishing the pCer ability to generate large microdomains and giving rise instead to a single ternary phase. These observations in model membranes in the absence of the lipids commonly used to form a liquid-disordered phase support the role of cholesterol as the key determinant in controlling its own displacement from Lo domains by ceramide upon sphingomyelinase activity. PMID:20712995

Busto, Jon V.; Sot, Jesus; Requejo-Isidro, Jose; Goni, Felix M.; Alonso, Alicia

2010-01-01

240

Atomic Structure: Investigating Atoms  

NSDL National Science Digital Library

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of three Science Objects in the Atomic Structure SciPack. It discusses the

National Science Teachers Association (NSTA)

2010-05-24

241

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

242

Microbial Adhesion in Flow Displacement Systems  

PubMed Central

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

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

2006-01-01

243

Atomic Physics  

NSDL National Science Digital Library

This collection provides a basic introduction to Atomic Physics. It reviews the building blocks of atomic structure, explores atomic isotopes, explains Einstein's famous equation E = mc2, and introduces the various types of radiation.

Griffith, Christopher

244

Polybenzoxazole via aromatic nucleophilic displacement  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

245

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

246

Displacement, politics and governance : access to low-income housing in a Beirut suburb  

E-print Network

Lebanon witnessed large-scale phases of internal displacement during and after its civil war (1975-1990). This study analyzes access to low-income housing for a Lebanese Shiites group which has already experienced two ...

Bou Akar, Hiba

2005-01-01

247

Displacement damage-induced electrical and structural effects in gallium arsenide solar cells following ion irradiation  

NASA Astrophysics Data System (ADS)

For nearly two decades, deviations between experimental data and the nonionizing energy loss (NIEL) have been observed for GaAs devices. In particular, previous data has suggested that electrical parameters associated with GaAs solar cells can follow different energy dependences with NIEL but only at the higher proton energies. In this paper, displacement damage-induced electrical and structural effects in GaAs solar cells were monitored before and after irradiation with various ions. The radiation-induced defects responsible for causing electrical changes were characterized using illuminated current-voltage, deep level transient spectroscopy (DLTS), and electron beam induced current (EBIC) while the structural changes were monitored using transmission electron microscopy (TEM). The EBIC images showed the existence of radiation-induced active recombination volumes or defect clusters after irradiation with high energy protons (E ? 10 MeV) and 22 MeV silicon ions, which were not produced by lower energy protons. The TEM images revealed strain related defects that correspond to the same irradiation conditions for which the defect clusters were observed, and therefore, the defects in the TEM images are associated with those observed in the EBIC images. These defects were not observed prior to irradiation so the lattice strain in the material is definitely associated with irradiation-induced lattice defects. HRTEM imaging has shown that the disordered regions are not amorphous but probably most likely a cluster of vacancies and a surrounding region rich in interstitials, which is produced when a large number of neighboring atoms are displaced in collision cascades known as the displacement spike. The formation of the U-band defect as determined by DLTS seems to evolve under the same irradiation conditions as the defects in the images. This very broad U-band peak is consistent with what would be expected from defect clusters. From analyses of the recoil spectra, high energy recoils appear to be responsible for the formation of these disordered regions and these regions are independent of the total displacement damage energy deposited. This study has shown that NIEL scaling is only violated for incident ion energies when the defect clusters are observed.

Warner, Jeffrey Hamilton

248

Atom-by-atom nucleation and growth of graphene nanopores  

PubMed Central

Graphene is an ideal thin membrane substrate for creating molecule-scale devices. Here we demonstrate a scalable method for creating extremely small structures in graphene with atomic precision. It consists of inducing defect nucleation centers with energetic ions, followed by edge-selective electron recoil sputtering. As a first application, we create graphene nanopores with radii as small as 3 ?, which corresponds to 10 atoms removed. We observe carbon atom removal from the nanopore edge in situ using an aberration-corrected electron microscope, measure the cross-section for the process, and obtain a mean edge atom displacement energy of 14.1 ± 0.1 eV. This approach does not require focused beams and allows scalable production of single nanopores and arrays of monodisperse nanopores for atomic-scale selectively permeable membranes. PMID:22492975

Russo, Christopher J.; Golovchenko, J. A.

2012-01-01

249

New displacement-based methods for optimal truss topology design  

NASA Technical Reports Server (NTRS)

Two alternate methods for maximum stiffness truss topology design are presented. The ground structure approach is used, and the problem is formulated in terms of displacements and bar areas. This large, nonconvex optimization problem can be solved by a simultaneous analysis and design approach. Alternatively, an equivalent, unconstrained, and convex problem in the displacements only can be formulated, and this problem can be solved by a nonsmooth, steepest descent algorithm. In both methods, the explicit solving of the equilibrium equations and the assembly of the global stiffness matrix are circumvented. A large number of examples have been studied, showing the attractive features of topology design as well as exposing interesting features of optimal topologies.

Bendsoe, Martin P.; Ben-Tal, Aharon; Haftka, Raphael T.

1991-01-01

250

Real-time detection of linear and angular displacements with a modified DVD optical head  

Microsoft Academic Search

Here we demonstrate that an astigmatic detection system (ADS), constructed with a modified digital-versatile-disk (DVD) optical head, can achieve real-time measurement of a linear displacement and two-dimensional (2D) tilt angles with a high sensitivity. An atomic force microscope (AFM), using our detection system to sense the deflection of microfabricated cantilevers, can resolve single atomic steps on graphite surfaces with a

En-Te Hwu; Shao-Kang Hung; Chih-Wen Yang; Kuang-Yuh Huang; Ing-Shouh Hwang

2008-01-01

251

MEMS-based hydraulic displacement amplification mechanism with completely encapsulated liquid  

Microsoft Academic Search

We developed a MEMS-based hydraulic displacement amplification mechanism (HDAM) with completely encapsulated liquid that can be used in applications that require large-displacement micro-actuators, such as tactile displays and microvalves controlling large mass flows. The HDAM contains a microcavity that is sealed by easily deformable thin polydimethylsiloxane (PDMS) membranes encapsulating an incompressible fluid and whose input and output surfaces have different

T. Ninomiya; Y. Okayama; Y. Matsumoto; X. Arouette; K. Osawa; N. Miki

2011-01-01

252

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

253

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

254

A linear stability analysis for miscible displacements  

Microsoft Academic Search

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

Shih-Hsien Chang; John C. Slattery

1986-01-01

255

Implementation of 3D spatial indexing and compression in a large-scale molecular dynamics simulation database for rapid atomic contact detection  

PubMed Central

Background Molecular dynamics (MD) simulations offer the ability to observe the dynamics and interactions of both whole macromolecules and individual atoms as a function of time. Taken in context with experimental data, atomic interactions from simulation provide insight into the mechanics of protein folding, dynamics, and function. The calculation of atomic interactions or contacts from an MD trajectory is computationally demanding and the work required grows exponentially with the size of the simulation system. We describe the implementation of a spatial indexing algorithm in our multi-terabyte MD simulation database that significantly reduces the run-time required for discovery of contacts. The approach is applied to the Dynameomics project data. Spatial indexing, also known as spatial hashing, is a method that divides the simulation space into regular sized bins and attributes an index to each bin. Since, the calculation of contacts is widely employed in the simulation field, we also use this as the basis for testing compression of data tables. We investigate the effects of compression of the trajectory coordinate tables with different options of data and index compression within MS SQL SERVER 2008. Results Our implementation of spatial indexing speeds up the calculation of contacts over a 1 nanosecond (ns) simulation window by between 14% and 90% (i.e., 1.2 and 10.3 times faster). For a 'full' simulation trajectory (51 ns) spatial indexing reduces the calculation run-time between 31 and 81% (between 1.4 and 5.3 times faster). Compression resulted in reduced table sizes but resulted in no significant difference in the total execution time for neighbour discovery. The greatest compression (~36%) was achieved using page level compression on both the data and indexes. Conclusions The spatial indexing scheme significantly decreases the time taken to calculate atomic contacts and could be applied to other multidimensional neighbor discovery problems. The speed up enables on-the-fly calculation and visualization of contacts and rapid cross simulation analysis for knowledge discovery. Using page compression for the atomic coordinate tables and indexes saves ~36% of disk space without any significant decrease in calculation time and should be considered for other non-transactional databases in MS SQL SERVER 2008. PMID:21831299

2011-01-01

256

Hirshfeld atom refinement  

PubMed Central

Hirshfeld atom refinement (HAR) is a method which determines structural parameters from single-crystal X-ray diffraction data by using an aspherical atom partitioning of tailor-made ab initio quantum mechanical molecular electron densities without any further approximation. Here the original HAR method is extended by implementing an iterative procedure of successive cycles of electron density calculations, Hirshfeld atom scattering factor calculations and structural least-squares refinements, repeated until convergence. The importance of this iterative procedure is illustrated via the example of crystalline ammonia. The new HAR method is then applied to X-ray diffraction data of the dipeptide Gly–l-Ala measured at 12, 50, 100, 150, 220 and 295?K, using Hartree–Fock and BLYP density functional theory electron densities and three different basis sets. All positions and anisotropic displacement parameters (ADPs) are freely refined without constraints or restraints – even those for hydrogen atoms. The results are systematically compared with those from neutron diffraction experiments at the temperatures 12, 50, 150 and 295?K. Although non-hydrogen-atom ADPs differ by up to three combined standard uncertainties (csu’s), all other structural parameters agree within less than 2?csu’s. Using our best calculations (BLYP/cc-pVTZ, recommended for organic molecules), the accuracy of determining bond lengths involving hydrogen atoms from HAR is better than 0.009?Å for temperatures of 150?K or below; for hydrogen-atom ADPs it is better than 0.006?Å2 as judged from the mean absolute X-ray minus neutron differences. These results are among the best ever obtained. Remarkably, the precision of determining bond lengths and ADPs for the hydrogen atoms from the HAR procedure is comparable with that from the neutron measurements – an outcome which is obtained with a routinely achievable resolution of the X-ray data of 0.65?Å. PMID:25295177

Capelli, Silvia C.; Burgi, Hans-Beat; Dittrich, Birger; Grabowsky, Simon; Jayatilaka, Dylan

2014-01-01

257

Hirshfeld atom refinement.  

PubMed

Hirshfeld atom refinement (HAR) is a method which determines structural parameters from single-crystal X-ray diffraction data by using an aspherical atom partitioning of tailor-made ab initio quantum mechanical molecular electron densities without any further approximation. Here the original HAR method is extended by implementing an iterative procedure of successive cycles of electron density calculations, Hirshfeld atom scattering factor calculations and structural least-squares refinements, repeated until convergence. The importance of this iterative procedure is illustrated via the example of crystalline ammonia. The new HAR method is then applied to X-ray diffraction data of the dipeptide Gly-l-Ala measured at 12, 50, 100, 150, 220 and 295?K, using Hartree-Fock and BLYP density functional theory electron densities and three different basis sets. All positions and anisotropic displacement parameters (ADPs) are freely refined without constraints or restraints - even those for hydrogen atoms. The results are systematically compared with those from neutron diffraction experiments at the temperatures 12, 50, 150 and 295?K. Although non-hydrogen-atom ADPs differ by up to three combined standard uncertainties (csu's), all other structural parameters agree within less than 2?csu's. Using our best calculations (BLYP/cc-pVTZ, recommended for organic molecules), the accuracy of determining bond lengths involving hydrogen atoms from HAR is better than 0.009?Å for temperatures of 150?K or below; for hydrogen-atom ADPs it is better than 0.006?Å(2) as judged from the mean absolute X-ray minus neutron differences. These results are among the best ever obtained. Remarkably, the precision of determining bond lengths and ADPs for the hydrogen atoms from the HAR procedure is comparable with that from the neutron measurements - an outcome which is obtained with a routinely achievable resolution of the X-ray data of 0.65?Å. PMID:25295177

Capelli, Silvia C; Bürgi, Hans-Beat; Dittrich, Birger; Grabowsky, Simon; Jayatilaka, Dylan

2014-09-01

258

Atom Interferometers  

E-print Network

Interference with atomic and molecular matter waves is a rich branch of atomic physics and quantum optics. It started with atom diffraction from crystal surfaces and the separated oscillatory fields technique used in atomic clocks. Atom interferometry is now reaching maturity as a powerful art with many applications in modern science. In this review we first describe the basic tools for coherent atom optics including diffraction by nanostructures and laser light, three-grating interferometers, and double wells on AtomChips. Then we review scientific advances in a broad range of fields that have resulted from the application of atom interferometers. These are grouped in three categories: (1) fundamental quantum science, (2) precision metrology and (3) atomic and molecular physics. Although some experiments with Bose Einstein condensates are included, the focus of the review is on linear matter wave optics, i.e. phenomena where each single atom interferes with itself.

Alexander D. Cronin; Joerg Schmiedmayer; David E. Pritchard

2007-12-21

259

Systematic calculation of threshold displacement energies: Case study in rutile  

NASA Astrophysics Data System (ADS)

A generalized and systematic method of calculating threshold displacement energies (Ed) using molecular dynamics simulations has been developed and applied to rutile TiO2. Statistically representative results have been achieved through fine sampling of impact energy and trajectory for each atomic species. Each impact trajectory is drawn from a uniform distribution of points on a unit sphere, along which, primary knock-on atoms (PKAs) with kinetic energies in the range of 20-200 eV were introduced into lattices equilibrated to 300 K. Various definitions of Ed are explored, with values presented as probabilities of defect formation. Results for the Ti PKA agree well with experimental data with a value of Ed at around 69 eV. Simulations of O PKAs contrast greatly with Ti PKAs, with displacements occurring at significantly lower energies, resulting in an O value of Ed at 19 eV. Analysis shows that replacement chains on the O sublattice are a common feature and play a significant role in governing defect formation in rutile.

Robinson, M.; Marks, N. A.; Whittle, K. R.; Lumpkin, G. R.

2012-03-01

260

Particle displacement tracking applied to air flows  

NASA Technical Reports Server (NTRS)

Electronic Particle Image Velocimetric (PIV) techniques offer many advantages over conventional photographic PIV methods such as fast turn around times and simplified data reduction. A new all electronic PIV technique was developed which can measure high speed gas velocities. The Particle Displacement Tracking (PDT) technique employs a single CW laser, small seed particles (1 micron), and a single intensified, gated CCD array frame camera to provide a simple and fast method of obtaining two-dimensional velocity vector maps with unambiguous direction determination. Use of a single CCD camera eliminates registration difficulties encountered when multiple cameras are used to obtain velocity magnitude and direction information. An 80386 PC equipped with a large memory buffer frame-grabber board provides all of the data acquisition and data reduction operations. No array processors of other numerical processing hardware are required. Full video resolution (640 x 480 pixel) is maintained in the acquired images, providing high resolution video frames of the recorded particle images. The time between data acquisition to display of the velocity vector map is less than 40 sec. The new electronic PDT technique is demonstrated on an air nozzle flow with velocities less than 150 m/s.

Wernet, Mark P.

1991-01-01

261

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

262

Hydrogen atoms in proteins: Positions and dynamics  

PubMed Central

Hydrogen atoms constitute about half of the atoms in proteins. Thus they contribute to the complex energy landscape of proteins [Frauenfelder, H., Sligar, S. G. & Wolynes, P. G. (1991) Science 254, 1598-1603]. Neutron crystal structure analysis was used to study the positions and mean-square displacements of hydrogen in myoglobin. A test of the reliability of calculated hydrogen atom coordinates by a comparison with our experimental results has been carried out. The result shows that >70% of the coordinates for hydrogen atoms that have a degree of freedom is predicted worse than 0.2 Å. It is shown that the mean-square displacements of the hydrogen atoms obtained from the Debye-Waller factor can be divided into three classes. A comparison with the dynamic mean-square displacements calculated from the elastic intensities obtained from incoherent neutron scattering [Doster, W., Cusack, S. & Petry, W. (1989) Nature 337, 754-756] shows that mainly the side-chain hydrogen atoms contribute to dynamic displacements on a time scale faster than 100 ps. PMID:12937341

Engler, Niklas; Ostermann, Andreas; Niimura, Nobuo; Parak, Fritz G.

2003-01-01

263

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

264

Atom-by-atom assembly  

NASA Astrophysics Data System (ADS)

Atomic manipulation using a scanning tunneling microscope (STM) tip enables the construction of quantum structures on an atom-by-atom basis, as well as the investigation of the electronic and dynamical properties of individual atoms on a one-atom-at-a-time basis. An STM is not only an instrument that is used to ‘see’ individual atoms by means of imaging, but is also a tool that is used to ‘touch’ and ‘take’ the atoms, or to ‘hear’ their movements. Therefore, the STM can be considered as the ‘eyes’, ‘hands’ and ‘ears’ of the scientists, connecting our macroscopic world to the exciting atomic world. In this article, various STM atom manipulation schemes and their example applications are described. The future directions of atomic level assembly on surfaces using scanning probe tips are also discussed.

Hla, Saw Wai

2014-05-01

265

Efficiency Improvements to the Displacement Based Multilevel Structural Optimization Algorithm  

NASA Technical Reports Server (NTRS)

Multilevel Structural Optimization (MSO) continues to be an area of research interest in engineering optimization. In the present project, the weight optimization of beams and trusses using Displacement based Multilevel Structural Optimization (DMSO), a member of the MSO set of methodologies, is investigated. In the DMSO approach, the optimization task is subdivided into a single system and multiple subsystems level optimizations. The system level optimization minimizes the load unbalance resulting from the use of displacement functions to approximate the structural displacements. The function coefficients are then the design variables. Alternately, the system level optimization can be solved using the displacements themselves as design variables, as was shown in previous research. Both approaches ensure that the calculated loads match the applied loads. In the subsystems level, the weight of the structure is minimized using the element dimensions as design variables. The approach is expected to be very efficient for large structures, since parallel computing can be utilized in the different levels of the problem. In this paper, the method is applied to a one-dimensional beam and a large three-dimensional truss. The beam was tested to study possible simplifications to the system level optimization. In previous research, polynomials were used to approximate the global nodal displacements. The number of coefficients of the polynomials equally matched the number of degrees of freedom of the problem. Here it was desired to see if it is possible to only match a subset of the degrees of freedom in the system level. This would lead to a simplification of the system level, with a resulting increase in overall efficiency. However, the methods tested for this type of system level simplification did not yield positive results. The large truss was utilized to test further improvements in the efficiency of DMSO. In previous work, parallel processing was applied to the subsystems level, where the derivative verification feature of the optimizer NPSOL had been utilized in the optimizations. This resulted in large runtimes. In this paper, the optimizations were repeated without using the derivative verification, and the results are compared to those from the previous work. Also, the optimizations were run on both, a network of SUN workstations using the MPICH implementation of the Message Passing Interface (MPI) and on the faster Beowulf cluster at ICASE, NASA Langley Research Center, using the LAM implementation of UP]. The results on both systems were consistent and showed that it is not necessary to verify the derivatives and that this gives a large increase in efficiency of the DMSO algorithm.

Plunkett, C. L.; Striz, A. G.; Sobieszczanski-Sobieski, J.

2001-01-01

266

Anion-exchange displacement centrifugal partition chromatography.  

PubMed

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

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

2004-11-01

267

Molecular dynamics simulation of displacement cascades in ?-Fe: A critical review  

NASA Astrophysics Data System (ADS)

Little more than 10 years ago the first paper on molecular dynamics (MD) simulation of displacement cascades in ?-Fe using a many-body potential was published by Calder and Bacon [J. Nucl. Mater. 207 (1993) 25]. Since then, a large body of literature data has been produced on the subject using different interatomic potentials. In this review, most of the available data from the literature are compared in order to discuss to what extent they are consistent. It is found that, while the number of Frenkel pairs versus cascade energy is essentially the same for most potentials, yielding a defect production efficiency in agreement with experimental estimates, differences exist concerning the point-defect clustered fractions. In the case of self-interstitial atoms (SIA), the criterion used to define clusters is largely responsible for the discrepancies, but differences also exist as a consequence of the different interatomic potentials. Too few data have been published concerning vacancy clusters to draw definitive conclusions. The existing differences do not correlate in any explicit way with the description that the interatomic potential gives of point-defects and their mobility.

Malerba, L.

2006-06-01

268

Probing neutrino mass with displaced vertices at the Tevatron  

E-print Network

Supersymmetric extensions of the standard model exhibiting bilinear R-parity violation can generate naturally the observed neutrino mass spectrum as well mixings. One interesting feature of these scenarios is that the lightest supersymmetric particle (LSP) is unstable, with several of its decay properties predicted in terms of neutrino mixing angles. A smoking gun of this model in colliders is the presence of displaced vertices due to LSP decays in large parts of the parameter space. In this work we focus on the simplest model of this type that comes from minimal supergravity with universal R-parity conserving soft breaking of supersymmetry (RmSUGRA). We evaluate the potentiality of the Fermilab Tevatron to probe the RmSUGRA parameters through the analysis of events possessing two displaced vertices stemming from LSP decays. We show that requiring two displaced vertices in the events leads to a reach in m_{1/2} twice the one in the usual multilepton signals in a large fraction of the parameter space.

F. de Campos; O. J. P. Eboli; M. B. Magro; W. Porod; D. Restrepo; J. W. F. Valle

2005-01-17

269

REVERSE DISPLACEMENT ANALYSIS FOR TENSEGRITY STRUCTURES  

E-print Network

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

Florida, University of

270

Seismic transducer measures small horizontal displacements  

NASA Technical Reports Server (NTRS)

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

Greenwood, T. L.

1965-01-01

271

Scale model studies of displacement ventilation  

E-print Network

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

Okutan, Galip Mehmet

1995-01-01

272

Feasibility study on ultrasonic lateral displacement measurement for structural health monitoring  

NASA Astrophysics Data System (ADS)

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

Matsuya, Iwao; Matsumoto, Fumiya; Ihara, Ikuo

2014-02-01

273

Disappearing charged tracks in association with displaced leptons from supersymmetry  

E-print Network

In this note we discuss a characteristic collider signature of models of gauge mediated supersymmetry breaking in which the selectron and smuon are mass-degenerate co-NLSP. In these models, all processes involving superpartners give rise to two NLSP selectrons or smuons, each of which subsequently decays to a nearly massless LSP gravitino and an electron or a muon. In a large region of the parameter space, the NLSPs travel macroscopic distances, of the order 0.1-1000 mm, before they decay. Hence, these models give rise to collider signatures involving charged tracks that end at vertices, which are inside the detector volume but displaced with respect to the original collision point, from which an electron or a muon is emitted. In order to probe this class of models we propose a search for disappearing charged tracks in association with displaced electrons or muons.

Petersson, Christoffer

2014-01-01

274

Disappearing charged tracks in association with displaced leptons from supersymmetry  

E-print Network

In this note we discuss a characteristic collider signature of models of gauge mediated supersymmetry breaking in which the selectron and smuon are mass-degenerate co-NLSP. In these models, all processes involving superpartners give rise to two NLSP selectrons or smuons, each of which subsequently decays to a nearly massless LSP gravitino and an electron or a muon. In a large region of the parameter space, the NLSPs travel macroscopic distances, of the order 0.1-1000 mm, before they decay. Hence, these models give rise to collider signatures involving charged tracks that end at vertices, which are inside the detector volume but displaced with respect to the original collision point, from which an electron or a muon is emitted. In order to probe this class of models we propose a search for disappearing charged tracks in association with displaced electrons or muons.

Christoffer Petersson

2014-11-03

275

Earthquake-induced soil displacements and their impact on rehabilitations.  

PubMed

A large earthquake can trigger long lasting geotechnical problems, which pose serious issues on both rehabilitations and land conservations. Therefore one of what required of us is to deduce as much hidden signs as possible from observable changes of landforms. Though serious, damage caused by the October 23rd 2004, Mid-Niigata Prefecture Earthquake has given us a rare opportunity to study the landform changes in mountainous terrain hit by this earthquake. An attempt was made to convert changes in elevation in Eulerian description for images obtained from remote-sensing technologies to Lagrangian displacements, because Lagrangian displacements can directly describe behaviors of soils, which are typically history-dependent. This paper documents some big pictures of earthquake-inflicted landform changes obtained through this attempt. PMID:21986310

Konagai, Kazuo

2011-01-01

276

Icosahedral quasicrystals of intermetallic compounds are icosahedral twins of cubic crystals of three kinds, consisting of large (about 5000 atoms) icosahedral complexes in either a cubic body-centered or a cubic face-centered arrangement or smaller (about 1350 atoms) icosahedral complexes in the ?-tungsten arrangement  

PubMed Central

The twofold-axis electron-diffraction photographs of icosahedral quasicrystals are of three kinds, reflecting three different structures of the cubic crystals that by icosahedral twinning form the quasicrystals. The first kind, represented by Al13Cu4Fe3, contains two very large icosahedral complexes, each of about 4680 atoms, in the body-centered arrangement, with six smaller icosahedral complexes (104 atoms each) in the principal interstices. The second kind, represented by Al5Mn, contains four of the very large complexes in the face-centered arrangement (cubic close packing), with four of the smaller clusters in the interstices. The third kind, represented by Al6CuLi3, contains eight icosahedral complexes, each of about 1350 atoms, in the ?-W arrangement. The supporting evidence for these cubic structures is discussed as well as other evidence showing that the simple quasicrystal theory, which states that quasicrystals do not involve any translational identity operations, has to be modified. Images PMID:16594078

Pauling, Linus

1989-01-01

277

Atmospheric pressure loading displacement of SLR stations  

NASA Astrophysics Data System (ADS)

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

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

2005-04-01

278

High Precision Displacement Measurement Using Fiber Optics  

Microsoft Academic Search

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

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

2002-01-01

279

Displacement sensor for indoor machine calibrations.  

PubMed

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

Mudassar, Asloob Ahmad; Butt, Saira

2013-05-20

280

The evolution of fabric with displacement in natural brittle faults  

NASA Astrophysics Data System (ADS)

In experiments performed at room temperature on gouges, a characteristic clast size distribution (CSD) is produced with increasing strain, and shear localization is documented to begin after few millimetres of sliding. But in natural faults active at depth in the crust, mechanical processes are associated with fluid-rock interactions, which might control the deformation and strength recovery. We aim to investigate the microstructural, geochemical and mineralogical evolution of low-displacement faults with increasing shear strain. The faults (cataclasite- and pseudotachylyte-bearing) are hosted in tonalite and were active at 9-11 km and 250-300°C. The samples were collected on a large glacier-polished outcrop, where major faults (accommodating up to 4300 mm of displacement) exploit pre-existing magmatic joints and are connected by a network of secondary fractures and faults (accommodating up to 500 mm of displacement) breaking intact tonalite. We performed optical and cathodoluminescence (CL) microscope, Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Rietveld X-Ray Powder Diffraction and microprobe chemical analysis in deformation zones of secondary faults with various offsets in order to evaluate the transfer of chemical species between dissolution zones and protected zones. Image analysis techniques were applied on SEM-BSE and optical microscope images to compute the CSD in samples, which experienced an increasing amount of strain. The secondary fractures are up to 5 mm thick. Within the first 20 mm of displacement, shear localizes along Y and R1 surfaces and a cataclastic foliation develops. The CSD evolves from a fractal dimension D of 1.3 in fractures without visible displacement to values above 2 after the first 500 mm of displacement. Chemical maps and CL images indicate that the foliation in cataclasite results from the rotation and fragmentation of clasts, with dissolution of quartz and passive concentration of Ti oxides and titanite in the foliation planes. The cataclasites are cemented by pervasive precipitation of K-feldspar plagues and idiomorphic, randomly oriented, epidote and chlorite. We conclude that the textures of these small displacement (< 500 mm) faults are controlled by brittle processes (fracture propagation and cataclastic comminution) similar to those reproduced in friction experiments performed on granite gouge (e.g., Beeler et al., 1996; Logan, 2007). Then progressively, stress driven fluid-rock reactions develop as fracturing and grain size reduction allows the kinetics of these reactions to be more efficient and fracture interconnection allows fluid infiltration. Healing of microfractures and fault rock cementation caused a rapid posteismic recovery of fault strength. References Beeler, N.M., Tullis, T.E., Blanpied, L., Weeks, J.D., 1996. Frictional behaviour of large displacement experimental faults. Journal of Geophysical Research 101, B4, 8697-8715. Logan, J.M., 2007. The progression from damage to localization of displacement observed in laboratory testing of porous rocks, in Lewis, H., and Couples, G.D. (eds.) The relationship between damage and localization. Geological Society of London Special Publication 289, 75-87.

Mittempergher, S.; Di Toro, G.; Gratier, J.; Aretusini, S.; Boullier-Bertrand, A.

2011-12-01

281

Hadronic Atoms  

E-print Network

We review the theory of hadronic atoms in QCD+QED. The non-relativistic effective Lagrangian approach, used to describe this type of bound states, is illustrated with the case of pi+pi- atoms. In addition, we discuss the evaluation of isospin-breaking corrections to hadronic atom observables by invoking chiral perturbation theory.

J. Gasser; V. E. Lyubovitskij; A. Rusetsky

2009-03-02

282

Interference of Rotating Atomic Clouds  

NASA Astrophysics Data System (ADS)

We study the theory of interference between spinning clouds of ultracold atoms; quantifying how intermeshed vortices in two displaced clouds form intricate patterns when the clouds are overlapped. These patterns, dominated by stripes, can be imaged in circumstances where individual vortices cannot be resolved. We contrast these structures (which were recently observed at JILA [Schweikhard et al. Phys. Rev. Lett. 93, 210403 (2003)]) with the ones which will be seen during the interference of two atomic clouds in highly correlated quantum Hall states. The striking differences in these interference patterns allows one to distinguish coherent and correlated states.

Mueller, Erich; Ho, Tin-Lun

2005-03-01

283

Tsunami mortality and displacement in Aceh province, Indonesia  

E-print Network

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

Scharfstein, Daniel

284

Atomic-scale study of electric dipoles near charged and uncharged domain walls in ferroelectric films.  

PubMed

Ferroelectrics are materials exhibiting spontaneous electric polarization due to dipoles formed by displacements of charged ions inside the crystal unit cell. Their exceptional properties are exploited in a variety of microelectronic applications. As ferroelectricity is strongly influenced by surfaces, interfaces and domain boundaries, there is great interest in exploring how the local atomic structure affects the electric properties. Here, using the negative spherical-aberration imaging technique in an aberration-corrected transmission electron microscope, we investigate the cation-oxygen dipoles near 180 degrees domain walls in epitaxial PbZr(0.2)Ti(0.8)O(3) thin films on the atomic scale. The width and dipole distortion across a transversal wall and a longitudinal wall are measured, and on this basis the local polarization is calculated. For the first time, a large difference in atomic details between charged and uncharged domain walls is reported. PMID:18066068

Jia, Chun-Lin; Mi, Shao-Bo; Urban, Knut; Vrejoiu, Ionela; Alexe, Marin; Hesse, Dietrich

2008-01-01

285

Electrode system for electric-discharge generation of atomic iodine in a repetitively pulsed oxygen - iodine laser with a large active volume  

SciTech Connect

Possibilities for increasing the active medium volume of a chemical oxygen - iodine laser (CCOIL) with a pulsed electric-discharge generation of atomic iodine are studied. The reasons are analysed of the low stability of the transverse self-sustained volume discharge in electrode systems with metal cathodes under the conditions of the electric energy input into gas-discharge plasma that are typical for CCOILs: low pressure of mixtures containing a strongly electronegative component, low voltage of discharge burning, low specific energy depositions, and long duration of the current pulse. An efficient electrode system is elaborated with the cathode based on an anisotropically-resistive material, which resulted in a stable discharge in the mixtures of iodide (CH{sub 3}I, n-C{sub 3}H{sub 7}I, C{sub 2}H{sub 5}I) with oxygen and nitrogen at the specific energy depositions of {approx}5 J L{sup -1}, pressures of 10 - 25 Torr, and mixture volume of 2.5 L. (lasers)

Kazantsev, S Yu; Kononov, I G; Podlesnykh, S V; Firsov, K N [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2010-08-03

286

Dependence of radiation damage accumulation in iron on underlying models of displacement cascades and subsequent defect migration  

NASA Astrophysics Data System (ADS)

Groups of displacement cascades calculated independently with different simulation models and computer codes are compared on a statistical basis. The parameters used for this comparison are the number of Frenkel pairs (FP) produced, the percentages of vacancies and self-interstitial atoms (SIAs) in clusters, the spatial extent and the aspect ratio of the vacancies and the SIAs formed in each cascade. One group of cascades was generated in the binary collision approximation (BCA) and all others by full molecular dynamics (MD). The MD results differ primarily due to the empirical interatomic potentials used and, to some extent, in code strategies. Cascades were generated in simulation boxes at different initial equilibrium temperatures. Only modest differences in the predicted numbers of FP are observed, but the other cascade parameters may differ by more than 100%. The consequences of these differences on long-term cluster growth in a radiation environment are examined by means of object kinetic Monte Carlo (OKMC) simulations. These were repeated with three different parameterizations of SIA and SIA cluster mobility. The differences encompassed low to high mobility, one- and three-dimensional migration of clusters, and complete immobility of large clusters. The OKMC evolution was followed until 0.1 dpa was reached. With the range of OKMC parameters used, cluster populations after 0.1 dpa differ by orders of magnitude. Using the groups of cascades from different sources induced no difference larger than a factor of 2 in the OKMC results. No correlation could be identified between the cascade parameters considered and the number densities of vacancies and SIAs predicted by OKMC to cluster in the long term. However, use of random point defect distributions instead of those obtained for displacement cascades as input for the OKMC modeling led to significantly different results. It is therefore suggested that although the displacement cascade characteristics considered do not correlate with cluster populations in the long term, other aspects of the internal structure of cascades do.

Souidi, A.; Becquart, C. S.; Domain, C.; Terentyev, D.; Malerba, L.; Calder, A. F.; Bacon, D. J.; Stoller, R. E.; Osetsky, Yu. N.; Hou, M.

2006-09-01

287

Time Scaling of the Rates of Produced Fluids in Laboratory Displacements  

SciTech Connect

In this report, the use of an asymptotic method, based on the time scaling of the ratio of produced fluids, to infer the relative permeability exponent of the displaced phase near its residual saturation, for immiscible displacements in laboratory cores was proposed. Sufficiently large injection rates, the existence of a power law can be detected, and its exponent inferred, by plotting in an appropriate plot the ratio of the flow rates of the two fluids at the effluent for some time after breakthrough.

Laroche, Catherine; Chen, Min; Yortsos, Yanis C.; Kamath, Jairam

2001-02-27

288

cif core.dic 1 ATOM SITE Dictionary name: cif core.dic  

E-print Network

cif core.dic 1 ATOM SITE Dictionary name: cif core.dic Dictionary version: 2.2 Dictionary last updated: 2001-01-11 Ã?Ã?Ã? Ã? Ã? Data items in the ATOM SITE category record details about the atom sites in a crystal structure, such as the positional coordinates, atomic displacement parameters, magnetic mo- ments

Meagher, Mary

289

Experimental investigation of local displacement speeds of wrinkled unsteady flames  

NASA Astrophysics Data System (ADS)

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

Sinibaldi, Jose Oscar

290

Separation of deformable particles in deterministic lateral displacement devices  

NASA Astrophysics Data System (ADS)

Using numerical simulations, we study the separation of deformable bodies, such as capsules, vesicles, and cells, in deterministic lateral displacement devices, also known as bump arrays. These arrays comprise regular rows of obstacles such as micropillars whose arrangements are shifted between adjacent rows by a fixed amount. We show that, in addition to the zigzag and laterally displaced trajectories that have been observed experimentally, there exists a third type of trajectory which we call dispersive, characterized by seemingly random bumpings off the micropillars. These dispersive trajectories are observed only for large and rigid particles whose diameters are approximately more than half the gap size between micropillars and whose stiffness exceeds approximately 500 MPa. We then map out the regions in phase space, spanned by the row shift, row separation, particle diameter, and particle deformability, in which the different types of trajectories are expected. We also show that, in this phase space, it is possible to transition from zigzag to dispersive trajectories, bypassing lateral displacement. Experimentally, this is undesirable because it limits the ability of the device to sort particles according to size. Finally, we discuss how our numerical simulations may be of use in device prototyping and optimization.

Quek, Raymond; Le, Duc Vinh; Chiam, K.-H.

2011-05-01

291

Corporate Restructuring, Downsizing, and the Middle Class: The Process and Meaning of Worker Displacement in the “New” Economy  

Microsoft Academic Search

This article conceptualizes, describes, and analyzes the phenomenon of corporate downsizing and the experience of worker displacement as a process of work and employment change that occurs within the context of structural changes in the economy, large firms and labor markets. The research is based on a case study of displaced IBM computer and Link aerospace workers in Binghamton, New

Charles Koeber

2002-01-01

292

Forced displacement and women's security in Colombia.  

PubMed

In the protracted Colombian conflict, assistance to internally displaced persons has developed in the context of contradictory political processes. The Colombian government's launching of a transitional justice process in the midst of armed conflict has generated a complex situation displaying both conflict and post-conflict characteristics. The progressive Constitutional Court rulings on internal displacement, in particular the gender-sensitive Auto 092, constitute an attempt to bring together humanitarian interventions and transitional justice measures in a rights-based framework. However, the national government is reluctant to adopt them fully and local realities still hamper their integrated implementation. Displaced women, therefore, remain in an especially vulnerable position. This paper argues that gender-sensitive humanitarian interventions must take into account all of these complexities of scale and political process in order to make legal frameworks more effective at the local level. In these contexts, interventions should pay particular attention to strategies that contribute to transforming pre-existing gender regimes. PMID:20132270

Meertens, Donny

2010-04-01

293

Wireless Power Transfer during Displacement Using Electromagnetic Coupling in Resonance  

NASA Astrophysics Data System (ADS)

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

Imura, Takehiro; Okabe, Hiroyuki; Uchida, Toshiyuki; Hori, Yoichi

294

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

295

Displacement sensors using soft magnetostrictive alloys  

NASA Astrophysics Data System (ADS)

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

Hristoforou, E.; Reilly, R. E.

1994-09-01

296

Displacement of crude oil by carbon dioxide  

E-print Network

viscosity of 20 cp until water production from the sand pack was essentially KEY TO SCHEMATIC FOR CO2 FLOOD EOUIPMENT FIGURE 1 1. Core 2. Filter 3. Oil Pump 4. Mercury-Antifreeze Vessel 5. Pressure Gauge 6. Oil Reservoir 7. CO2 Source 8... of crude oil displaced from the three sand packs by CO as a function of pressure was essentially the same. For each of the sand packs three regions were recognized. A pressure region of (1) immiscible crude oil displacement, (2) near miscible crude oil...

Omole, Olusegun

2012-06-07

297

Noise analysis and improvement of displacement vector estimation from angular displacements  

PubMed Central

Elastography or elasticity imaging techniques typically image local strains or Young’s modulus variations along the insonification direction. Recently, techniques that utilize angular displacement estimates obtained from multiple angular insonification of tissue have been reported. Angular displacement estimates obtained along different angular insonification directions have been utilized for spatial-angular compounding to reduce noise artifacts in axial-strain elastograms, and for estimating the axial and lateral components of the displacement vector and the corresponding strain tensors. However, these angular strain estimation techniques were based on the assumption that noise artifacts in the displacement estimates were independent and identically distributed and that the displacement estimates could be modeled using a zero-mean normal probability density function. Independent and identically distributed random variables refer to a collection of variables that have the same probability distribution and are mutually independent. In this article, a modified least-squares approach is presented that does not make any assumption regarding the noise in the angular displacement estimates and incorporates displacement noise artifacts into the strain estimation process using a cross-correlation matrix of the displacement noise artifacts. Two methods for estimating noise artifacts from the displacement images are described. Improvements in the strain tensor (axial and lateral) estimation performance are illustrated utilizing both simulation data obtained using finite-element analysis and experimental data obtained from a tissue-mimicking phantom. Improvements in the strain estimation performance are quantified in terms of the elastographic signal-to-noise and contrast-to-noise ratios obtained with and without the incorporation of the displacement noise artifacts into the least-squares strain estimator. PMID:18561677

Chen, Hao; Varghese, Tomy

2008-01-01

298

Burma: Displaced Karens. Like Water on the Khu Leaf  

Microsoft Academic Search

War disrupts the normal relationship between people and place. Displaced by war, people must adapt to survive, both physically and socially. When people are displaced for a long time, these adaptations become normal; thus displacement starts as an aberration but becomes a constant way of life. In eastern Burma, 'normal' displacement has led to significant changes in the political, cultural

Chris Cusano

1990-01-01

299

Neutron interactions and atomic recoil spectra  

SciTech Connect

This chapters presents a discussion of neutron interactions with materials that lead to activation, transmutation, and atomic displacements. The emphasis will be on current applications including neutron irradiation facilities, neutron dosimetry techniques, and computer codes for spectral adjustment and radiation damage calculations.

Greenwood, L.R.

1993-08-01

300

A Low-Voltage Large-Displacement Large-Force Inchworm Actuator  

Microsoft Academic Search

Inchworm microactuators are popular in micropositioning applications for their long ranges. However, until now, they could not be considered for applications such as in vivo biomedical applications because of their high input voltages. This paper reports on the modeling, design, fabrication, and testing of a new family of pull-in-based electrostatic inchworm microactuators which provides a solution to this problem. Actuators

Mehmet A. Erismis; Herc P. Neves; Robert Puers; Chris Van Hoof

2008-01-01

301

Neuropsychological functioning in posttraumatic stress disorder following forced displacement in older adults and their offspring.  

PubMed

The aim of the present study was to investigate neuropsychological performance in an untried trauma sample of older adults displaced during childhood at the end of World War II (WWII) with and without posttraumatic stress disorder (PTSD) as well as transgenerational effects of trauma and PTSD on their offspring. Displaced older adults with (n=20) and without PTSD (n=24) and nondisplaced healthy individuals (n=11) as well as one of their respective offspring were assessed with a large battery of cognitive tests (primarily targeting memory functioning). No evidence for deficits in neuropsychological performance was found in the aging group of displaced people with PTSD. Moreover, no group difference emerged in the offspring groups. Findings may be interpreted as first evidence for a rather resilient PTSD group of older adults that is available for assessment 60 years after displacement. PMID:23896354

Jelinek, Lena; Wittekind, Charlotte E; Moritz, Steffen; Kellner, Michael; Muhtz, Christoph

2013-12-15

302

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

SciTech Connect

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

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

2013-05-15

303

Models for prediction of temperature difference and ventilation effectiveness with displacement ventilation  

SciTech Connect

Displacement ventilation may provide better indoor air quality than mixing ventilation. Proper design of displacement ventilation requires information concerning the air temperature difference between the head and foot level of a sedentary person and the ventilation effectiveness at the breathing level. This paper presents models to predict the air temperature difference and the ventilation effectiveness, based on a database of 56 cases with displacement ventilation. The database was generated by using a validated CFD program and covers four different types of US buildings: small offices, large offices with partitions, classrooms, and industrial workshops under different thermal and flow boundary conditions. Both the maximum cooling load that can be removed by displacement ventilation and the ventilation effectiveness are shown to depend on the heat source type and ventilation rate in a room.

Yuan, X.; Chen, Q.; Glicksman, L.R.

1999-07-01

304

Environmental and project displacement of population in India. Part I: Development and deracination.  

PubMed

Official development projects in India have displaced at least 20 million persons since Indian independence in 1947, and the majority have not been relocated in planned resettlement. India is in a race to implement development projects needed to support the growth of its population, which increased from 361 million in 1951 to 840 million in 1990. Through the 1960s and 1970s about 1/4 of these oustees were minimally resettled and the rest had to find their own way to get reestablished. There is no international consensus on the rights of internally displaced persons, but most countries compensate people. Agricultural labor and construction labor are the most common types of work of the landless oustees. 1,589 large dams built since independence ousted the largest number of people. Dams, reservoirs, and canals displaced 11,000,000 people; 2,750,000 were rehabilitated and 8,250,000 found their own way. Mines displaced 1,700,000; 450,000 were rehabilitated and 1,250,000 found their own way. Industries displaced 1,000,000; 300,000 were rehabilitated and 700,000 found their own way. Parks and sanctuaries displaced 600,000; 150,000 were rehabilitated and 450,000 relocated on their own. Other projects displacing people are forest preserves, wildlife sanctuaries, military installations, weapons testing grounds, nuclear installations, and railroads and roads. The World Bank requires compensation for people displaced by 12 dam projects it is funding in India: the underestimated count is 610,500 persons. The Pong Dam, a 130 m high gravel dam, under the western Himalayas ousted 30,330 families, about 167,000 people, but only 16,001 families were found eligible for compensation. The Subarnarekha Project in southern Bihar is displacing 10,000 families, about 55,000 people. The state government estimates that 35% of these will not settle in suggested relocation sites because land is not available. PMID:12317786

Maloney, C

1991-01-01

305

Variable-Displacement Hydraulic Drive Unit  

NASA Technical Reports Server (NTRS)

Hydraulic power controlled through multiple feedback loops. In hydraulic drive unit, power closely matched to demand, thereby saving energy. Hydraulic flow to and from motor adjusted by motor-control valve connected to wobbler. Wobbler angle determines motor-control-valve position, which in turn determines motor displacement. Concept applicable to machine tools, aircraft controls, and marine controls.

Lang, D. J.; Linton, D. J.; Markunas, A.

1986-01-01

306

Displacement of Bilirubin from Albumin by Berberine  

Microsoft Academic Search

A study was made of the effect of berberine, the major ingredient of the Chinese herb huanglian (coptis chinensis) reported to pose some risk for kernicterus among jaundiced newborn Chinese infants, on the protein binding of bilirubin, using the peroxidase kinetic method. Berberine was found in vitro, as to its displacing effect on a molar basis, to be about tenfold

Eli Chan

1993-01-01

307

Television and Schooling: Displacement and Distraction Hypotheses.  

ERIC Educational Resources Information Center

Research on two hypotheses regarding television's possible negative effect on children's academic achievement is reviewed. A lack of support is found for the displacement hypothesis (time spent with television is taken away from more academically beneficial activities) and limited support for the distraction hypothesis (exposure to television…

Roberts, Donald F.; And Others

1993-01-01

308

Character displacement and the origins of diversity  

PubMed Central

In The Origin of Species, Darwin proposed his ‘principle of divergence of character’ (a process now termed ‘character displacement’) to explain how new species arise and why they differ from one other phenotypically. Darwin maintained that the origin of species, and the evolution of differences between them, is ultimately caused by divergent selection acting to minimize competitive interactions between initially similar individuals, populations, and species. Here, we examine the empirical support for the various claims that constitute Darwin’s principle, specifically that: (1) competition promotes divergent trait evolution; (2) the strength of competitively mediated divergent selection increases with increasing phenotypic similarity between competitors; (3) divergence can occur within species; and (4) competitively mediated divergence can trigger speciation. We also explore aspects that Darwin failed to consider. In particular, we describe how: (1) divergence can arise from selection acting to lessen reproductive interactions; (2) divergence is fueled by the intersection of character displacement and sexual selection; and (3) phenotypic plasticity may play a key role in promoting character displacement. Generally, character displacement is well supported empirically, and it remains a vital explanation for how new species arise and diversify. PMID:21043778

Pfennig, David W.; Pfennig, Karin S.

2012-01-01

309

Maximizing Displacement: Mass, Volume and Density  

NSDL National Science Digital Library

This is an indoor lab that uses a boat simulation to demonstrate the concepts of mass, volume and density, and their relationship to displacement. It is a problem solving activity that encourages student creativity resulting in a variety of valid solutions.

310

Ko Displacement Theory for Structural Shape Predictions  

NASA Technical Reports Server (NTRS)

The development of the Ko displacement theory for predictions of structure deformed shapes was motivated in 2003 by the Helios flying wing, which had a 247-ft (75-m) wing span with wingtip deflections reaching 40 ft (12 m). The Helios flying wing failed in midair in June 2003, creating the need to develop new technology to predict in-flight deformed shapes of unmanned aircraft wings for visual display before the ground-based pilots. Any types of strain sensors installed on a structure can only sense the surface strains, but are incapable to sense the overall deformed shapes of structures. After the invention of the Ko displacement theory, predictions of structure deformed shapes could be achieved by feeding the measured surface strains into the Ko displacement transfer functions for the calculations of out-of-plane deflections and cross sectional rotations at multiple locations for mapping out overall deformed shapes of the structures. The new Ko displacement theory combined with a strain-sensing system thus created a revolutionary new structure- shape-sensing technology.

Ko, William L.

2010-01-01

311

Extracting gravity line displacement from stabilographic recordings  

Microsoft Academic Search

Three algorithms for determining gravity line (GL) location from center of pressure (COP) and horizontal force (Fx) recordings are suggested. The algorithms are designed to study upright standing posture and are based on the following premises: (a) the foot(feet) is a solid body and does not move, (b) the axis of rotation of the ankle joint does not displace, and

Deborah L. King; Vladimir M. Zatsiorsky

1997-01-01

312

A Personal Appearance Program for Displaced Homemakers.  

ERIC Educational Resources Information Center

A career counseling program evaluated the self-esteem of 28 displaced homemakers, then presented 3 sessions on the importance of personal appearance in hiring practices, wardrobe management, nonverbal communication, professional image, and self-concept. Analysis of participant evaluations indicated improved levels of control and confidence and…

Fiore, Ann Marie; De Long, Marilyn Revell

1990-01-01

313

THE SYMPLECTIC DISPLACEMENT ENERGY AUGUSTIN BANYAGA  

E-print Network

THE SYMPLECTIC DISPLACEMENT ENERGY AUGUSTIN BANYAGA , DAVID E. HURTUBISE, AND PETER SPAETH Abstract , DAVID E. HURTUBISE, AND PETER SPAETH for all f Symp(M, ) = { Diff(M) | = }. This follows from to the identity. It was proved recently by Buss and Leclercq [6] that the restriction of · HL to Ham

Hurtubise, David E.

314

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

PubMed Central

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

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

2014-01-01

315

Velocity and displacement measurements of microelectromechanical systems using laser vibrometry  

NASA Astrophysics Data System (ADS)

An instrumentation suite for 3D-motion measurement of displacement and velocity of microelectromechanical systems (MEMS) is described. The instrument suite includes an optical microscope with an integrated laser vibrometer and computer-controlled instrumentation for measurement of real-time device dynamics. A long focal-length optical microscope (NA = 0.28) provides mum-scale spatial resolution for positioning the laser beam (lambda = 633nm) on the MEMS structure for nm-resolution interferometry and for imaging through a vacuum viewport. Integrated micromachined mirrors reflect the laser beam into the plane of the MEMS to measure the in-plane motion of the microstructure. The measurement of velocity or displacement of mum-scale features normal to the plane of a reflective MEMS structure is done directly on the MEMS surface. Decoders provide simultaneous measurements of displacement with resolution up to 4nm in a 50kHz bandwidth and velocity with a resolution to 0.5mum/s in a 1.5 MHz bandwidth. The instrument suite includes electronics and software for real-time recording and display of system variables including velocity and displacement. Programmable experimental variables include applied voltage, laser position, optical focus, chamber pressure and temperature. The system can measure device parameters including natural frequency and quality factor. The instrument suite is used to characterize single-crystal Silicon MEMS as a demonstration of its capabilities. Devices studied include lateral actuators and a large displacement XY stage. Characterization of the electromechanical responses of a torsional resonator and a lateral tunneling accelerometer are also presented. The tunneling current response and the electromechanical device performance is measured for the accelerometer. The motion of the torsional resonator can be described by the Mathieu equation. Maps of the stability regions are measured to characterize the response of the device. Resonant frequency, quality factor, linear spring constant, cubic spring constant, and mass are measured experimentally or determined by models. The measurement errors are discussed. Resonant mode maps, phase plots (dx vs. x), pressure dependence data, and other measurements are included to further demonstrate the performance of the instrumentation suite.

Hartwell, Peter George

316

atomic spectra 1 Atomic Spectra  

E-print Network

. Eisberg and Resnick: Quantum Physics of Atoms, Molecules, Solids, Nuclei and Particles, pp. 95-119, p286 Physics, pp. 88-93 (Rutherford nuclear model), 93-106 (atomic structure and electron spectra) 2. D. W. Preston and E. R. Dietz: The Art of Experimental Physics, pp. 397- 399, resolution of optical instruments

Glashausser, Charles

317

Microstrain in tetragonal lead-zirconate-titanate: The effect of pressure on the ionic displacements.  

PubMed

Piezoelectric materials respond to external stimuli by adjusting atomic positions. In solid-solutions, the changes occurring in atomic scale are very complex since the short- and long-range order are different. Standard methods used in diffraction data analysis fail to model the short-range order accurately. Pressure-induced cation displacements in ferroelectric Pb(Zr0.45Ti0.55)O3 perovskite oxide are modeled by starting from a short-range order. We show that the model gives the average structure correctly and properly describes the local structure. The origin of the microstrain in lead zirconate titanate is the spatially varying Zr and Ti concentration and atomic distances, which is taken into account in the simulation. High-pressure neutron powder diffraction and simulation techniques are applied for the determination of atomic positions and bond-valences as a function of pressure. Under hydrostatic pressure, the material loses its piezoelectric properties far before the transition to the cubic phase takes place. The total cation valence +6 is preserved up to 3.31 GPa by compensating the increasing B-cation valence by decreasing Pb-displacement from the high-symmetry position. At 3.31 GPa, Pb-displacement is zero and the material is no more ferroelectric. This is also the pressure at which the Pb-valence is minimized. The average structure is still tetragonal. The model for microstrain predicts that the transition occurs over a finite pressure range: Pb-displacements are spatially varying and follow the distribution of Zr and Ti ions. PMID:25173278

Frantti, J; Fujioka, Y; Zhang, J; Zhu, J; Vogel, S C; Zhao, Y

2014-08-01

318

Simulation of neutron displacement damage in bipolar junction transistors using high-energy heavy ion beams.  

SciTech Connect

Electronic components such as bipolar junction transistors (BJTs) are damaged when they are exposed to radiation and, as a result, their performance can significantly degrade. In certain environments the radiation consists of short, high flux pulses of neutrons. Electronics components have traditionally been tested against short neutron pulses in pulsed nuclear reactors. These reactors are becoming less and less available; many of them were shut down permanently in the past few years. Therefore, new methods using radiation sources other than pulsed nuclear reactors needed to be developed. Neutrons affect semiconductors such as Si by causing atomic displacements of Si atoms. The recoiled Si atom creates a collision cascade which leads to displacements in Si. Since heavy ions create similar cascades in Si we can use them to create similar damage to what neutrons create. This LDRD successfully developed a new technique using easily available particle accelerators to provide an alternative to pulsed nuclear reactors to study the displacement damage and subsequent transient annealing that occurs in various transistor devices and potentially qualify them against radiation effects caused by pulsed neutrons.

Doyle, Barney Lee; Buller, Daniel L.; Hjalmarson, Harold Paul; Fleming, Robert M; Bielejec, Edward Salvador; Vizkelethy, Gyorgy

2006-12-01

319

Role of atomic collisions in fusion  

SciTech Connect

Atomic physics issues have played a large role in controlled fusion research. A general discussion of the present role of atomic processes in both magnetic and inertial controlled fusion work is presented.

Post, D.E.

1982-04-01

320

Acting Atoms.  

ERIC Educational Resources Information Center

Describes a fun game in which students act as electrons, protons, and neutrons. This activity is designed to help students develop a concrete understanding of the abstract concept of atomic structure. (DKM)

Farin, Susan Archie

1997-01-01

321

Kinetic Atom.  

ERIC Educational Resources Information Center

Surveys the research of scientists like Joule, Kelvin, Maxwell, Clausius, and Boltzmann as it comments on the basic conceptual issues involved in the development of a more precise kinetic theory and the idea of a kinetic atom. (Author/SK)

Wilson, David B.

1981-01-01

322

Atom interferometry  

Microsoft Academic Search

We have demonstrated an atom interferometer with completely separated beams using three 200 nm period transmission gratings.\\u000a A stretched 10 cm long and 10 ?m thick metal foil, was inserted in the interferometer so that separated portions of the atom\\u000a wave went on opposite sides of the foil. A fringe amplitude of up to 900 cps was observed, which allows

Jörg Schmiedmayer; Christopher Ekstrom; Michael Chapman; Troy Hammond; David Pritchard

323

Remember Me: Displaced Children of the Holocaust  

NSDL National Science Digital Library

The United States Holocaust Museum (USHM) has worked on a number of important projects, and this might be one of their most moving. Working with the archives of the World Jewish Congress (WJC), they have digitized approximately 1100 photographs of children who were displaced or orphaned as a result of the persecution carried out by the Nazis and their collaborators. The intent of this project is "to identify these children, piece together information about their wartime and postwar experiences, and facilitate renewed connections among these young survivors, their families, and other individuals who were involved in their care during and after the war." Visitors to the site can browse the photos by name or just by viewing the gallery as they see fit. The site also includes a 1945 BBC radio broadcast seeking relatives of displaced children and a section with updates on the project's progress.

324

Regression models for estimating coseismic landslide displacement  

Microsoft Academic Search

Newmark's sliding-block model is widely used to estimate coseismic slope performance. Early efforts to develop simple regression models to estimate Newmark displacement were based on analysis of the small number of strong-motion records then available. The current availability of a much larger set of strong-motion records dictates that these regression equations be updated. Regression equations were generated using data derived

Randall W. Jibson

2007-01-01

325

Displacement-sensitive organic field effect transistor  

Microsoft Academic Search

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

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

2012-01-01

326

Displacement-sensitive organic field effect transistor  

Microsoft Academic Search

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

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

2011-01-01

327

Displacement of bilirubin from albumin by berberine.  

PubMed

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

Chan, E

1993-01-01

328

Large amplitude pairing fluctuations in atomic nuclei  

E-print Network

Pairing fluctuations are self-consistently incorporated on the same footing as the quadrupole deformations in present state of the art calculations including particle number and angular momentum conservation as well as configuration mixing. The approach is complemented by the use of the finite range density dependent Gogny force which, with a unique source for the particle-hole and particle-particle interactions, guarantees a self-consistent interplay in both channels. We have applied our formalism to study the role of the pairing degree of freedom in the description of the most relevant observables like spectra, transition probabilities, separation energies, etc. We find that the inclusion of pairing fluctuations mostly affects the description of excited states, depending on the excitation energy and the angular momentum. $E0$ transition probabilities experiment rather big changes while $E2$'s are less affected. Genuine pairing vibrations are thoroughly studied with the conclusion that deformations strongly inhibits their existence. These studies have been performed for a selection of nuclei: spherical, deformed and with different degree of collectivity.

Nuria López Vaquero; J. Luis Egido; Tomás R. Rodríguez

2013-11-29

329

Bogoliubov theory and bosonic atoms  

E-print Network

We formulate the Bogoliubov variational principle in a mathematical framework similar to the generalized Hartree-Fock theory. Then we analyze the Bogoliubov theory for bosonic atoms in details. We discuss heuristically why the Bogoliubov energy should give the first correction to the leading energy of large bosonic atoms.

Phan Thanh Nam

2011-09-13

330

The Atomicity of Transactional Memory  

Microsoft Academic Search

Transactional memory is perceived as an appealing alternative to critical sections for general pur- pose concurrent programming. Despite the large amount of recent work on transactional memory implementations, however, its actual specification has never been precisely defined. This paper presents TM-atomicity, a new correctness criterion to capture that specification. TM- atomicity extends the notion of strict serializability, itself a strong

Rachid Guerraoui

331

A force/displacement analysis of muscle testing.  

PubMed

Manual muscle testing procedures are the subject of a force and displacement analysis. Equipment was fabricated, tested, and employed to gather force, displacement, and time data for the purpose of examining muscle-test parameters as used by clinicians in applied kinesiology. Simple mathematical procedures are used to process the data to find potential patterns of force and displacement which would correspond to the testing of strong and weak muscles of healthy subjects. Particular attention is paid to the leading edge of the force pulses, as most clinicians report they derive most of their assessment from the initial thrust imparted on the patient's limb. An analysis of the simple linear regression of the slope (distance vs force) of the leading edge of a force pulse indicates that a significantly large slope is indicative of weak muscles (as perceived by the clinician), and a small slope is indicative of strong muscles. Threshold criteria for slopes are specified to create a model that may discriminate between strong and weak muscles. The model is accurate 98% of the time compared to judgments of clinicians with more than 5 years of experience but is considerably lower for clinicians with less than five years of experience (64%). this accuracy rate indicates that the model is reliable in predicting the clinician's perception of muscle strength, and it also indicates that the testing procedure for muscle strength used by experienced clinicians in applied kinesiology are reliable. The experiment lays the groundwork for studies of the objectivity of muscle-strength assessment in applied kinesiology. PMID:11065332

Caruso, W; Leisman, G

2000-10-01

332

Magnetic Monopole Atom  

NASA Astrophysics Data System (ADS)

A N-S monopole pair should form an atom, an analog of positronium. Such atoms might be created by colliding Pb beams at the LHC for which the available energy is 1144 TeV. The difficulty in understanding such systems can be seen by using the textbook positronium formula and Dirac's observation that the effective ``charge'' of a monopole (to use in Coulomb's law) is 67.5 n times the electron charge. Even with the integer n = 1, the energy radiated by a pair of poles as the atom cascades to the ground state is 147 times the rest energy of the pair, in violation of energy conservation. Relativistic corrections increase this value. Vacuum polarization effects give a large correction in the right direction, but the usual QED can not be used because the magnetic fine structure constant is huge, 137/4. Even without detailed calculations it can be assumed that the mass of the atom is much smaller than the mass of two free poles. As a newly produced pair begins to separate, one could expect additional poles to be produced from the vacuum resulting in two atoms moving away from each other. These atoms would self annihilate resulting in back to back jets.

Norbeck, Edwin

2007-10-01

333

Embedded-atom-method effective-pair-interaction study of the structural and thermodynamic properties of Cu-Ni, Cu-Ag, and Au-Ni solid solutions  

SciTech Connect

The structural and thermodynamic properties of Cu-Ni, Cu-Ag, and Au-Ni solid solutions have been studied using a computational approach which combines an embedded-atom-method (EAM) description of alloy energetics with a second-order-expansion (SOE) treatment of compositional and displacive disorder. It is discussed in detail how the SOE approach allows the EAM expression for the energy of a substitutional alloy to be cast in the form of a generalized lattice-gas Hamiltonian containing effective pair interactions with arbitrary range. Furthermore, we show how the SOE-EAM method can be combined with either mean-field or Monte Carlo statistical mechanics techniques in order to calculate short-range-order (SRO) parameters, average nearest-neighbor bond lengths, and alloy thermodynamic properties which include contributions from static displacive relaxations and dynamic atomic vibrations. We demonstrate that the contributions to alloy heats of mixing arising from displacive relaxations can be sizeable, and that the neglect of these terms can lead to large overestimations of calculated phase-transition temperatures. The effects of vibrational free-energy contributions on the results of composition-temperature phase diagram calculations are estimated to be relatively small for the phase-separating alloy systems considered in this study. It is shown that within the SOE approach displacive effects can act only to displace the peak in the Fourier-transformed SRO parameter away from Brillouin-zone-boundary special points and towards the origin. Consistent with this result, we show that the unusual SRO observed in diffuse scattering experiments for Au-Ni solid solutions can be understood as arising from a competition between chemical and displacive driving forces which favor ordering and clustering, respectively. {copyright} {ital 1996 The American Physical Society.}

Asta, M.; Foiles, S.M. [Computational Materials Science Department, Sandia National Laboratories, P.O. Box 939, MS 9163, Livermore, California 94551-0939 (United States)] [Computational Materials Science Department, Sandia National Laboratories, P.O. Box 939, MS 9163, Livermore, California 94551-0939 (United States)

1996-02-01

334

Embedded-atom-method effective-pair-interaction study of the structural and thermodynamic properties of Cu-Ni, Cu-Ag, and Au-Ni solid solutions  

NASA Astrophysics Data System (ADS)

The structural and thermodynamic properties of Cu-Ni, Cu-Ag, and Au-Ni solid solutions have been studied using a computational approach which combines an embedded-atom-method (EAM) description of alloy energetics with a second-order-expansion (SOE) treatment of compositional and displacive disorder. It is discussed in detail how the SOE approach allows the EAM expression for the energy of a substitutional alloy to be cast in the form of a generalized lattice-gas Hamiltonian containing effective pair interactions with arbitrary range. Furthermore, we show how the SOE-EAM method can be combined with either mean-field or Monte Carlo statistical mechanics techniques in order to calculate short-range-order (SRO) parameters, average nearest-neighbor bond lengths, and alloy thermodynamic properties which include contributions from static displacive relaxations and dynamic atomic vibrations. We demonstrate that the contributions to alloy heats of mixing arising from displacive relaxations can be sizeable, and that the neglect of these terms can lead to large overestimations of calculated phase-transition temperatures. The effects of vibrational free-energy contributions on the results of composition-temperature phase diagram calculations are estimated to be relatively small for the phase-separating alloy systems considered in this study. It is shown that within the SOE approach displacive effects can act only to displace the peak in the Fourier-transformed SRO parameter away from Brillouin-zone-boundary special points and towards the origin. Consistent with this result, we show that the unusual SRO observed in diffuse scattering experiments for Au-Ni solid solutions can be understood as arising from a competition between chemical and displacive driving forces which favor ordering and clustering, respectively.

Asta, Mark; Foiles, Stephen M.

1996-02-01

335

Actuated atomizer  

NASA Technical Reports Server (NTRS)

An actuated atomizer is adapted for spray cooling or other applications wherein a well-developed, homogeneous and generally conical spray mist is required. The actuated atomizer includes an outer shell formed by an inner ring; an outer ring; an actuator insert and a cap. A nozzle framework is positioned within the actuator insert. A base of the nozzle framework defines swirl inlets, a swirl chamber and a swirl chamber. A nozzle insert defines a center inlet and feed ports. A spool is positioned within the coil housing, and carries the coil windings having a number of turns calculated to result in a magnetic field of sufficient strength to overcome the bias of the spring. A plunger moves in response to the magnetic field of the windings. A stop prevents the pintle from being withdrawn excessively. A pintle, positioned by the plunger, moves between first and second positions. In the first position, the head of the pintle blocks the discharge passage of the nozzle framework, thereby preventing the atomizer from discharging fluid. In the second position, the pintle is withdrawn from the swirl chamber, allowing the atomizer to release atomized fluid. A spring biases the pintle to block the discharge passage. The strength of the spring is overcome, however, by the magnetic field created by the windings positioned on the spool, which withdraws the plunger into the spool and further compresses the spring.

Tilton, Charles (Inventor); Weiler, Jeff (Inventor); Palmer, Randall (Inventor); Appel, Philip (Inventor)

2008-01-01

336

Atomic research  

NASA Technical Reports Server (NTRS)

Work performed by the University of Alabama in Huntsville's (UAH) Center for Applied Optics (CAO) entitled Atomic Research is documented. Atomic oxygen (AO) effects on materials have long been a critical concern in designing spacecraft to withstand exposure to the Low Earth Orbit (LEO) environment. The objective of this research effort was to provide technical expertise in the design of instrumentation and experimental techniques for analyzing materials exposed to atomic oxygen in accelerated testing at NASA/MSFC. Such testing was required to answer fundamental questions concerning Space Station Freedom (SSF) candidate materials and materials exposed to atomic oxygen aboard the Long-Duration Exposure Facility (LDEF). The primary UAH task was to provide technical design, review, and analysis to MSFC in the development of a state-of-the-art 5eV atomic oxygen beam facility required to simulate the RAM-induced low earth orbit (LEO) AO environment. This development was to be accomplished primarily at NASA/MSFC. In support of this task, contamination effects and ultraviolet (UV) simulation testing was also to be carried out using NASA/MSFC facilities. Any materials analysis of LDEF samples was to be accomplished at UAH.

Hadaway, James B.; Connatser, Robert; Cothren, Bobby; Johnson, R. B.

1993-01-01

337

Very large swelling in hybrid frameworks: a combined computational and powder diffraction study.  

PubMed

Using a combination of simulations and powder diffraction, we report here the study of the very large swelling of a three-dimensional nanoporous iron(III) carboxylate (MIL-88) which exhibits almost a reversible doubling (approximately 85%) of its cell volume while fully retaining its open-framework topology. The crystal structure of the open form of MIL-88 has been successfully refined and indicates that atomic displacements larger than 4 angstroms are observed when water or various alcohols are adsorbed in the porous structure, revealing an unusually flexible crystallized framework. X-ray thermodiffractometry shows that only a displacive transition occurs during the swelling phenomenon, ruling out any bond breaking. PMID:16287320

Mellot-Draznieks, Caroline; Serre, Christian; Surblé, Suzy; Audebrand, Nathalie; Férey, Gérard

2005-11-23

338

24 CFR 42.350 - Relocation assistance for displaced persons.  

...false Relocation assistance for displaced persons. 42.350 Section 42.350 Housing and Urban Development Office of the...of Housing and Community Development Act of 1974 § 42.350 Relocation assistance for displaced...

2014-04-01

339

46 CFR 153.966 - Discharge by liquid displacement.  

... 2014-10-01 false Discharge by liquid displacement. 153.966 Section 153...DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS...Procedures § 153.966 Discharge by liquid displacement. The person in...

2014-10-01

340

46 CFR 153.966 - Discharge by liquid displacement.  

Code of Federal Regulations, 2012 CFR

... 2012-10-01 false Discharge by liquid displacement. 153.966 Section 153...DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS...Procedures § 153.966 Discharge by liquid displacement. The person in...

2012-10-01

341

46 CFR 153.966 - Discharge by liquid displacement.  

Code of Federal Regulations, 2011 CFR

... 2011-10-01 false Discharge by liquid displacement. 153.966 Section 153...DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS...Procedures § 153.966 Discharge by liquid displacement. The person in...

2011-10-01

342

46 CFR 153.966 - Discharge by liquid displacement.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 false Discharge by liquid displacement. 153.966 Section 153...DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS...Procedures § 153.966 Discharge by liquid displacement. The person in...

2013-10-01

343

5 CFR 330.706 - Notification of displaced employees.  

Code of Federal Regulations, 2011 CFR

...Notification of displaced employees. 330.706 Section...SERVICE REGULATIONS RECRUITMENT, SELECTION, AND...Transition Assistance Plan for Displaced Employees § 330.706 Notification...contain guidance to the employee on how to apply for vacancies...

2011-01-01

344

5 CFR 330.706 - Notification of displaced employees.  

Code of Federal Regulations, 2010 CFR

...Notification of displaced employees. 330.706 Section...SERVICE REGULATIONS RECRUITMENT, SELECTION, AND...Transition Assistance Plan for Displaced Employees § 330.706 Notification...contain guidance to the employee on how to apply for vacancies...

2010-01-01

345

Atom Interferometry  

ScienceCinema

Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton?s constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gryoscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be sued to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

Mark Kasevich

2010-01-08

346

The displacement estimation error back-propagation (DEEP) method for a multiple structural displacement monitoring system  

NASA Astrophysics Data System (ADS)

Visually servoed paired structured light system (ViSP) has been found to be useful in estimating 6-DOF relative displacement. The system is composed of two screens facing each other, each with one or two lasers, a 2-DOF manipulator and a camera. The displacement between two sides is estimated by observing positions of the projected laser beams and rotation angles of the manipulators. To apply the system to massive structures, the whole area should be partitioned and each ViSP module is placed in each partition in a cascaded manner. The estimated displacement between adjoining ViSPs is combined with the next partition so that the entire movement of the structure can be estimated. The multiple ViSPs, however, have a major problem that the error is propagated through the partitions. Therefore, a displacement estimation error back-propagation (DEEP) method which uses Newton-Raphson or gradient descent formulation inspired by the error back-propagation algorithm is proposed. In this method, the estimated displacement from the ViSP is updated using the error back-propagated from a fixed position. To validate the performance of the proposed method, various simulations and experiments have been performed. The results show that the proposed method significantly reduces the propagation error throughout the multiple modules.

Jeon, H.; Shin, J. U.; Myung, H.

2013-04-01

347

Atomic Orbitals  

NSDL National Science Digital Library

The Atomic Orbitals Web site "was established as part of an (ongoing) project at Purdue University to develop 'visualization modules' for general chemistry students." Using the Chime plug-in, which allows unique and stunning visualizations, visitors can learn what an atomic orbital is; what the 1s, 2s, 3s, 2p, 3p, and 3d orbitals are; what hybrid orbitals are; and more. The combination of easy-to-read descriptions and educational graphics make the site a great learning resource for high school and even college level chemistry students.

1969-12-31

348

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

Microsoft Academic Search

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

Rémi Michel; Jean-Philippe Avouac; Jean Taboury

1999-01-01

349

Pop Internationalism: Has A Half Century of World Music Trade Displaced Local Culture?  

Microsoft Academic Search

Advances in communication technologies over the past half century have made the cultural goods of one country more readily available to consumers in another, raising concerns that cultural products from large economies – in particular the US – will displace the indigenous cultural products of smaller economies. In this paper we provide stylized facts about the global music consumption and

Fernando Ferreira; Joel Waldfogel

2010-01-01

350

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

Microsoft Academic Search

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

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

2009-01-01

351

Important Generalization Concerning the Role of Competing Forces in Displacive Phase Transitions  

Microsoft Academic Search

On the basis of an analysis of data on a large number of compounds exhibiting displacive phase transitions, it is observed (with no known exceptions) that the transition temperature decreases with hydrostatic pressure for those transitions associated with soft zone-center optic phonons and increases for those transitions associated with soft zone-boundary optic phonons. This difference in behavior is tentatively interpreted

G. A. Samara; T. Sakudo; K. Yoshimitsu

1975-01-01

352

Displacement Addition on Linking Extensional Fault Arrays in the Canyonlands Graben, Utah  

Microsoft Academic Search

Studies of brittle fault populations over the past decade have revealed that large extensional faults grow by the lengthening, interaction and physical linkage of en echelon fault segments. However, the temporal evolution of displacement accumulation during segment interaction and linkage is difficult to unravel due to a lack of direct observation during each stage in the fault array development. The

D. C. Commins; S. Gupta; J. A. Cartwright; W. M. Phillips

2003-01-01

353

Glassy Interfacial Dynamics of Ni Nanoparticles: Part I Colored Noise, Dynamic Heterogeneity and Collective Atomic Motion  

PubMed Central

Most condensed materials exhibit a significant fraction of atoms, molecules or particles that are strongly interacting with each other, while being configured geometrically at any instant of time in an ‘amorphous’ state having a relatively uniform density. Recently, both simulations and experiments have revealed that the dynamics of diverse condensed amorphous materials is generally characterized by significant heterogeneity in the local mobility and by progressively increasing collective motion upon cooling that takes the form of string-like collective particle rearrangements. The direct experimental observation of this type of collective motion, which has been directly linked to the growing relaxation times of glass-forming materials, and its quantification under different thermodynamic conditions, has so far been restricted to colloidal and driven granular fluids. The present work addresses the fundamental problem of how to determine the scale of this type of collective motion in materials composed of molecules or atoms. The basic premise of our work is that large scale dynamic particle clustering in amorphous materials must give rise to large fluctuations in particle mobility so that transport properties, especially those related to particle mobility, should naturally exhibit noise related to the cooperative motion scale. In our initial exploratory study seeking a relationship of this kind, we find 1/f? or ‘colored noise’, in both potential energy and particle displacements fluctuations of the atoms within the glassy interfacial layer of Ni nanoparticles (NPs). A direct relation between the particle displacement (mobility) noise exponent ? and the average polymerization index of the string-like collective motion L is observed for a range of NP sizes, temperatures and for surface doping of the NPs with other metal atoms (Ag, Au, Pt) to change of fragility of the glassy interfacial layer at the surface of the Ni NPs. We also introduce a successful analytic model to understand this relationship between ? and L

Zhang, Hao; Douglas, Jack F.

2014-01-01

354

A review of the recent empirical literature on displaced workers  

Microsoft Academic Search

This article reviews the empirical literature on job displacement. Job displacement is widespread and strongly countercyclical (tending to peak during economic downturns), but concentrated in industries and states that are doing poorly, relative either to other industries and states or to their own prior performance. Displaced workers experience more nonemployment than do nondisplaced workers, but the difference fades after about

Bruce C. Fallick

1996-01-01

355

Development of micro\\/nano displacement sensor for piezoelectric actuator  

Microsoft Academic Search

Micro displacement measurement of the PZT actuator is a micro sensor which could measure the minute displacement in micron or nanometer level. In general, the sensor is required to accommodate little space in order to save the room of measuring device. In this paper, a mechanical micro displacement sensor with smaller volume has been proposed. This paper focus on the

Yong Yu; Bo Song; Yunjian Ge

2009-01-01

356

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

PubMed Central

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

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

2008-01-01

357

Unified treatment of slow atom-atom and ion-atom collisions  

NASA Astrophysics Data System (ADS)

A unified treatment of slow ion-atom and atom-atom collisions for many-electron systems is proposed. The time-dependent electronic wave function is expanded in terms of traveling atomic orbitals of the two collision centers at large internuclear separations and is matched to the solution in the inner region, where it is expanded in terms of molecular orbitals without translational factors. It is shown that this method avoids the difficulties associated with the conventional perturbed-stationary-state approximation. Application to charge transfer in the H(+) + He(+) collision is illustrated.

Kimura, M.; Lin, C. D.

1985-02-01

358

Parapharyngeal Neck Schwannomas with Unusual Vascular Displacement  

PubMed Central

This case report illustrates two unusual cases of parapharyngeal schwannomas mimicking carotid body tumors in terms of characteristic vascular displacement. Carotid body tumors classically cause splaying of internal and external carotid arteries demonstrating the Lyre sign on imaging. Also interestingly, both of these cases were seen in younger ages and include cervical sympathetic chain schwannoma and vagal schwannoma. However, these schwannomas revealed hypovascularity on imaging studies allowing differentiation from hypervascular carotid body tumors. Preoperative distinction between carotid body tumors and schwannomas is very important. PMID:24065994

Sargar, Kiran

2013-01-01

359

Traumatic displacement of stomach - a case report.  

PubMed

These days we have fast paced traffic on our roads to help us keep up with our fast paced life. But every boon has a down side and our high velocity traffic is no exception. Here is a case report of a blunt abdominal injury following a road traffic accident. Externally the deceased had only a few grazed abrasions on the forehead and right forearm. But on internal examination of abdomen, it was noticed that the left hemi-diaphragm was torn and the stomach and intestines were found displaced into the left thoracic cavity. PMID:24365690

Janardhanan, Joshima; Tarvadi, Pratik Vijay; Manipady, Shahnavaz; Shetty, Mahabalesh; Somashekar, C

2014-01-01

360

Superconducting inductive displacement detection of a microcantilever  

E-print Network

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

Vinante, Andrea

2014-01-01

361

Planetary atoms  

Microsoft Academic Search

We have experimentally observed the systematic onset of strong mixing of confirugations in core-excited autoionization states of Ba as a function of excitation level of the core electron relative to the Rydberg electron. This behavior was originally suggested by Percival in his discussion of Planetary Atoms.

W. Cooke; L. Bloomfield; R. Freeman; J. Bokor

362

Planetary atoms  

Microsoft Academic Search

We have experimentally observed the systematic onset of strong mixing of confirugations in core-excited autoionization states of Ba as a function of excitation level of the core electron relative to the Rydberg electron. This behavior was originally suggested by Percival in his discussion of Planetary Atoms.

W. E. Cooke; L. A. Bloomfield; R. R. Freeman; J. Bokor

1985-01-01

363

Atomic Spectra  

NSDL National Science Digital Library

In this Flash animation the user can view the atomic emission spectra (400-700nm) of eight different elements. A dragable marker allows the user to approximate the wavelength of the various spectral lines. The effect of resolution can be examined in the sodium spectrum in the region 550-600nm.

364

Number Theory and Atomic Densities Charles L. Fefferman  

E-print Network

Number Theory and Atomic Densities Charles L. Fefferman Department of Mathematics, Princeton of the atom. One of the successful attempts was Thomas--Fermi theory. According to it, the atomic energy E related to the theory of large atoms in the context of large--Z asymptotics. The goal of that work

Seco, Luis A.

365

Gender-based violence in conflict and displacement: qualitative findings from displaced women in Colombia  

PubMed Central

Introduction Gender-based violence (GBV) is prevalent among, though not specific to, conflict affected populations and related to multifarious levels of vulnerability of conflict and displacement. Colombia has been marked with decades of conflict, with an estimated 5.2 million internally displaced persons (IDPs) and ongoing violence. We conducted qualitative research to understand the contexts of conflict, displacement and dynamics with GBV. This as part of a multi-phase, mixed method study, in collaboration with UNHCR, to develop a screening tool to confidentially identify cases of GBV for referral among IDP women who were survivors of GBV. Methods Qualitative research was used to identify the range of GBV, perpetrators, contexts in conflict and displacement, barriers to reporting and service uptake, as well as to understand experiences of service providers. Thirty-five female IDPs, aged 18 years and older, who self-identified as survivors of GBV were enrolled for in-depth interviews in San Jose de Guaviare and Quibdo, Colombia in June 2012. Thirty-one service providers participated in six focus group discussions and four interviews across these sites. Results Survivors described a range of GBV across conflict and displacement settings. Armed actors in conflict settings perpetrated threats of violence and harm to family members, child recruitment, and, to a lesser degree, rape and forced abortion. Opportunistic violence, including abduction, rape, and few accounts of trafficking were more commonly reported to occur in the displacement setting, often perpetrated by unknown individuals. Intrafamilial violence, intimate partner violence, including physical and sexual violence and reproductive control were salient across settings and may be exacerbated by conflict and displacement. Barriers to reporting and services seeking were reported by survivors and providers alike. Conclusions Findings highlight the need for early identification of GBV cases, with emphasis on confidential approaches and active engagement of survivors in available, quality services. Such efforts may facilitate achievement of the goals of new Colombian laws, which seek to prevent and respond to GBV, including in conflict settings. Ongoing conflict and generalized GBV in displacement, as well as among the wider population, suggests a need to create sustainable solutions that are accessible to both IDPs and general populations. PMID:25076981

2014-01-01

366

High-dynamic angle measurement based on laser displacement sensors.  

PubMed

It is currently difficult to achieve good real-time dynamic angle measurements with high accuracy and large ranges. In this paper, a photoelectric measurement method for dynamic angles based on three laser displacement sensors (LDSs) is proposed. Offline, a dynamic angle vision measurement model is established, and the system is calibrated by using a planar target moved by a 2D moving platform. In the course of measurement, three laser beams emitted from three LDSs are projected onto a rotating plane, and three noncollinear points are acquired synchronously; then the rotation angle is calculated in real time. Simulations verify the feasibility of the method theoretically. Experimental results demonstrate that the method achieves measurement accuracies of 0.008° and 0.046° under quasi-static condition of 80°/s and highly dynamic condition of 1000°/s within the measurement range of about ±40°, respectively. PMID:23938418

Sun, Junhua; Zhang, Jie; Liu, Zhen; Zhang, Guangjun

2013-08-10

367

Poly(1,3,4-oxadiazoles) via aromatic nucleophilic displacement  

NASA Technical Reports Server (NTRS)

Poly(1,3,4-oxadiazoles) (POX) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl) 1,3,4-oxadiazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The polymerizations are carried out in polar aprotic solvents such as sulfolane or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. The di(hydroxyphenyl) 1,3,4-oxadiazole monomers are synthesized by reacting 4-hydroxybenzoic hydrazide with phenyl 4-hydrobenzoate in the melt and also by reacting aromatic dihydrazides with two moles of phenyl 4-hydroxybenzoate in the melt. This synthetic route has provided high molecular weight POX of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the large variety of activated aromatic dihalides which are available.

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

1992-01-01

368

Atomistic simulations of displacement cascades in Y2O3 single crystal  

NASA Astrophysics Data System (ADS)

We study the characteristics of displacement cascades in single crystal Y2O3 using classical molecular dynamics. There are two possible ways to generate the cascades in yttria, using either the Y or the O atoms as the primary knock-on (PKA) atom. It is shown that there is a qualitative difference in the characteristics of the cascades obtained in these two cases. Even though the crystal is seen to be in a highly disordered state in the cascade volume, as seen from the plots of radial distribution function, the correlation between the Y and O atoms is not completely lost. This facilitates a quick recovery of the system during the annealing phase. Topological connectivity of the YO6 polyhedral units plays an important role in imparting stability to the Y2O3 crystal. These characteristics of the cascades can help explain the stability of the yttria nanoparticles when they are dispersed in oxide dispersion strengthened steels.

Dholakia, Manan; Chandra, Sharat; Valsakumar, M. C.; Mathi Jaya, S.

2014-11-01

369

Displacive and Diffusive Transformations in the Formation of the Ni_2Al  

NASA Astrophysics Data System (ADS)

The phase stability of Ni_2Al has been examined by first-principles full-potential linear muffin-tin orbital (FPLMTO) calculations for different atomic configurations. The results of our calculations showed that an ordered B2-type phase is unstable with respect to ?-type shuffles. These calculations indicate that ordering of the atoms is a major factor for the formation of Ni_2Al structures and that a combined displacive/ordering transformation mechanism is important for determining the phase diagram of Ni_2Al. To better understand the origin of the instability of the ordered B2-type Ni_2Al structure with respect to the ?-type distortion, we have used a pair potential for modeling the interactions between the atoms. Calculated lattice parameters for the ordered Ni_2Al phase are in excellent agreement with experiment, and a realistic value for the degree of shuffling has been calculated.

Sanati, M.; Pinski, R. C.

1998-04-01

370

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

NASA Astrophysics Data System (ADS)

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

Spray, J. G.

2003-02-01

371

Coherent range-gated laser displacement metrology with compact optical head.  

PubMed

We describe a new architecture for laser displacement metrology with a drastic reduction in the size and complexity of the optical head. Connected by a single optical fiber, the compact heads are easy to integrate and readily multiplexed to support applications requiring large numbers of sensors. The approach is made possible by modulating the outgoing laser light with a binary random noise code, allowing the detected signals to be discriminated based on their propagation delay. We demonstrate a displacement resolution of 1.1 nm rms. PMID:17938657

Lay, O P; Dubovitsky, S; Shaddock, D A; Ware, B

2007-10-15

372

An interferometric strain-displacement measurement system  

NASA Technical Reports Server (NTRS)

A system for measuring the relative in-plane displacement over a gage length as short as 100 micrometers is described. Two closely spaced indentations are placed in a reflective specimen surface with a Vickers microhardness tester. Interference fringes are generated when they are illuminated with a He-Ne laser. As the distance between the indentations expands or contracts with applied load, the fringes move. This motion is monitored with a minicomputer-controlled system using linear diode arrays as sensors. Characteristics of the system are: (1) gage length ranging from 50 to 500 micrometers, but 100 micrometers is typical; (2) least-count resolution of approximately 0.0025 micrometer; and (3) sampling rate of 13 points per second. In addition, the measurement technique is non-contacting and non-reinforcing. It is useful for strain measurements over small gage lengths and for crack opening displacement measurements near crack tips. This report is a detailed description of a new system recently installed in the Mechanisms of Materials Branch at the NASA Langley Research Center. The intent is to enable a prospective user to evaluate the applicability of the system to a particular problem and assemble one if needed.

Sharpe, William N., Jr.

1989-01-01

373

Robustness of localized DNA strand displacement cascades.  

PubMed

Colocalization can strongly alter the kinetics and efficiency of chemical processes. For instance, in DNA-templated synthesis unfavorable reactions are sped up by placing reactants into close proximity onto a DNA scaffold. In biochemistry, clustering of enzymes has been demonstrated to enhance the reaction flux through some enzymatic cascades. Here we investigate the effect of colocalization on the performance of DNA strand displacement (DSD) reactions, an important class of reactions utilized in dynamic DNA nanotechnology. We study colocalization by immobilizing a two-stage DSD reaction cascade comprised of a “sender” and a “receiver” gate onto a DNA origami platform. The addition of a DNA (or RNA) input strand displaces a signal strand from the sender gate, which can then transfer to the receiver gate. The performance of the cascade is found to vary strongly with the distance between the gates. A cascade with an intermediate gate distance of ?20 nm exhibits faster kinetics than those with larger distances, whereas a cascade with smaller distance is corrupted by excessive intraorigami leak reactions. The 20 nm cascade is found to be considerably more robust with respect to a competing reaction, and implementation of multiple receiver gates further increases this robustness. Our results indicate that for the 20 nm distance a fraction of signal strands is transferred locally to a receiver gate on the same platform, probably involving direct physical contact between the gates. The performance of the cascade is consistent with a simple model that takes “local” and “global” transfer processes into account. PMID:25089925

Teichmann, Mario; Kopperger, Enzo; Simmel, Friedrich C

2014-08-26

374

Regression models for estimating coseismic landslide displacement  

USGS Publications Warehouse

Newmark's sliding-block model is widely used to estimate coseismic slope performance. Early efforts to develop simple regression models to estimate Newmark displacement were based on analysis of the small number of strong-motion records then available. The current availability of a much larger set of strong-motion records dictates that these regression equations be updated. Regression equations were generated using data derived from a collection of 2270 strong-motion records from 30 worldwide earthquakes. The regression equations predict Newmark displacement in terms of (1) critical acceleration ratio, (2) critical acceleration ratio and earthquake magnitude, (3) Arias intensity and critical acceleration, and (4) Arias intensity and critical acceleration ratio. These equations are well constrained and fit the data well (71% < R2 < 88%), but they have standard deviations of about 0.5 log units, such that the range defined by the mean ?? one standard deviation spans about an order of magnitude. These regression models, therefore, are not recommended for use in site-specific design, but rather for regional-scale seismic landslide hazard mapping or for rapid preliminary screening of sites. ?? 2007 Elsevier B.V. All rights reserved.

Jibson, R. W.

2007-01-01

375

Dynamic response of electromagnetic spatial displacement trackers.  

PubMed

Overall system latency--the elapsed time from input human motion until the immediate consequences of that input are available in the display--is one of the most frequently cited shortcoming of current virtual environment (VE) technology. Given that spatial displacement trackers are employed to monitor head and hand position and orientation in many VE applications, the dynamic response intrinsic to these devices is an unavoidable contributor to overall system latency. In this paper, we describe a testbed and method for measurement of tracker dynamic response that use a motorized rotary swing arm to sinusoidally displace the VE sensor at a number of frequencies spanning the bandwidth of volitional human movement. During the tests, actual swing arm angle and VE sensor reports are collected and time stamped. By calibrating the time stamping technique, the tracker's internal transduction and processing time are separated from data transfer and host computer software execution latencies. We have used this test-bed to examine several VE sensors--most recently to compare latency, gain, and noise characteristics of two commercially available electromagnetic trackers: Ascension Technology Corp.'s Flock of Birds(TM) and Polhemus Inc.'s Fastrak(TM). PMID:11540397

Adelstein, B D; Johnston, E R; Ellis, S R

1996-01-01

376

Do alternative energy sources displace fossil fuels?  

NASA Astrophysics Data System (ADS)

A fundamental, generally implicit, assumption of the Intergovernmental Panel on Climate Change reports and many energy analysts is that each unit of energy supplied by non-fossil-fuel sources takes the place of a unit of energy supplied by fossil-fuel sources. However, owing to the complexity of economic systems and human behaviour, it is often the case that changes aimed at reducing one type of resource consumption, either through improvements in efficiency of use or by developing substitutes, do not lead to the intended outcome when net effects are considered. Here, I show that the average pattern across most nations of the world over the past fifty years is one where each unit of total national energy use from non-fossil-fuel sources displaced less than one-quarter of a unit of fossil-fuel energy use and, focusing specifically on electricity, each unit of electricity generated by non-fossil-fuel sources displaced less than one-tenth of a unit of fossil-fuel-generated electricity. These results challenge conventional thinking in that they indicate that suppressing the use of fossil fuel will require changes other than simply technical ones such as expanding non-fossil-fuel energy production.

York, Richard

2012-06-01

377

Transient digitizer with displacement current samplers  

DOEpatents

A low component count, high speed sample gate, and digitizer architecture using the sample gates is based on use of a signal transmission line, a strobe transmission line and a plurality of sample gates connected to the sample transmission line at a plurality of positions. The sample gates include a strobe pickoff structure near the strobe transmission line which generates a charge displacement current in response to propagation of the strobe signal on the strobe transmission line sufficient to trigger the sample gate. The sample gate comprises a two-diode sampling bridge and is connected to a meandered signal transmission line at one end and to a charge-holding cap at the other. The common cathodes are reverse biased. A voltage step is propagated down the strobe transmission line. As the step propagates past a capacitive pickoff, displacement current i=c(dv/dT), flows into the cathodes, driving the bridge into conduction and thereby charging the charge-holding capacitor to a value related to the signal. A charge amplifier converts the charge on the charge-holding capacitor to an output voltage. The sampler is mounted on a printed circuit board, and the sample transmission line and strobe transmission line comprise coplanar microstrips formed on a surface of the substrate. Also, the strobe pickoff structure may comprise a planar pad adjacent the strobe transmission line on the printed circuit board.

McEwan, Thomas E. (Livermore, CA)

1996-01-01

378

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

379

Plastic Optical Fiber Displacement Sensor Based on Dual Cycling Bending  

PubMed Central

In this study, a high sensitivity and easy fabricated plastic optical fiber (POF) displacement sensor is proposed. A POF specimen subjected to dual cyclic bending is used to improve the sensitivity of the POF displacement sensor. The effects of interval between rollers, relative displacement and number of rollers on the sensitivity of the displacement sensor are analyzed both experimentally and numerically. A good agreement between the experimental measurements and numerical calculations is obtained. The results show that the interval between rollers affects sensitivity most significantly than the other design parameters. Based on the experimental data, a linear equation is derived to estimate the relationship between the power loss and the relative displacement. The difference between the estimated results and the experimental results is found to be less than 8%. The results also show that the proposed POF displacement sensor based on dual cyclic bending can be used to detect displacement accurately. PMID:22163465

Kuang, Jao-Hwa; Chen, Pao-Chuan; Chen, Yung-Chuan

2010-01-01

380

Pulse tube stirling machine with warm gas-driven displacer  

NASA Astrophysics Data System (ADS)

A pulse tube type stirling machine with warm gas-driven displacer which has a displacer rod is discussed with numerical simulation when it is used as a cryogenic refrigerator, room temperature refrigerator and engine. It has both the advantages of gas-driven-stirling machine with high efficiency and simplicity and the advantages of pulse tube machine with no moving parts at low temperatures. A nodal analysis method that includes the linear motor and the displacer in the machine is introduced. Numerical results show that it has high potential to be used as the cryogenic refrigerator, room temperature refrigerator and engine. In this type of machine, there is an optimum phase angle between displacer and piston, and an optimum swept volume ratio of displacer over compressor for efficiency. The phase angle and swept volume ratio can be adjusted by the natural frequency of the displacer and the diameter of the displacer rod when it is used as a refrigerator.

Zhu, Shaowei; Nogawa, Masafumi

2010-05-01

381

Superfluid regimes in degenerate atomic Fermi gases  

SciTech Connect

We give a brief overview of recent studies of quantum degenerate regimes in ultracold Fermi gases. The attention is focused on the regime of Bose-Einstein condensation of weakly bound molecules of fermionic atoms, formed at a large positive scattering length for the interspecies atom-atom interaction. We analyze remarkable collisional stability of these molecules and draw prospects for future studies.

Shlyapnikov, G.V. [Laboratoire Physique Theorique et Modeles Statistique, Universite Paris Sud, Bat. 100, 91405 Orsay (France); Van der Waals-Zeeman Institute, University of Amsterdam, Valckenierstraat 65/67, 1018 XEAmsterdam (Netherlands)

2005-05-05

382

Atoms in boxes: From confined atoms to electron-atom scattering  

NASA Astrophysics Data System (ADS)

We show that both confined atoms and electron-atom scattering can be described by a unified basis set method. The central idea behind this method is to place the atom inside a hard potential sphere, enforced by a standard Slater type basis set multiplied by a cutoff factor. For confined atoms, where the wall is placed close to the atomic nucleus, we show how the energy of the highest occupied atomic orbital and the static polarizability of helium and neon atoms evolve with the confinement radius. To our knowledge, these are the first confined atom polarizability calculations that include correlation for many-electron atoms, through the use of time-dependent density-functional theory. By placing the atom in a large spherical box, with a wall outside the electron density, we obtain scattering phase shifts using a recently developed method [M. van Faassen, A. Wasserman, E. Engel, F. Zhang, and K. Burke, Phys. Rev. Lett. 99, 043005 (2007)]. We show that the basis set method gives identical results to previously obtained phase shifts for e-H and e-He+ scattering.

van Faassen, Meta

2009-09-01

383

Atomic Structure: Properties of Atoms  

NSDL National Science Digital Library

Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of three Science Objects in the Atomic Structure SciPack. It explores the

National Science Teachers Association (NSTA)

2010-05-24

384

Atomic-Scale Mechanism of Crack-Tip Plasticity: Dislocation Nucleation and Crack-Tip Shielding  

Microsoft Academic Search

By isolating the process of dislocation emission from a crack tip under an applied tensile stress, we extract from a molecular dynamics simulation the atomic-level displacement and stress fields on the activated slip plane before and after the nucleation event. The stress-displacement relations so obtained provide a direct link with recent continuum descriptions of brittle versus ductile behavior in crack

Fabrizio Cleri; Sidney Yip; Dieter Wolf; Simon R. Phillpot

1997-01-01

385

Long-time mean-square displacements in proteins  

NASA Astrophysics Data System (ADS)

We propose a method for obtaining the intrinsic, long-time mean square displacement (MSD) of atoms and molecules in proteins from finite-time molecular dynamics (MD) simulations. Typical data from simulations are limited to times of 1 to 10 ns, and over this time period the calculated MSD continues to increase without a clear limiting value. The proposed method consists of fitting a model to MD simulation-derived values of the incoherent intermediate neutron scattering function, Iinc(Q,t), for finite times. The infinite-time MSD, , appears as a parameter in the model and is determined by fits of the model to the finite-time Iinc(Q,t). Specifically, the is defined in the usual way in terms of the Debye-Waller factor as I(Q,t=?)=exp(-Q2/3). The method is illustrated by obtaining the intrinsic MSD of hydrated lysozyme powder (h=0.4 g water/g protein) over a wide temperature range. The intrinsic obtained from data out to 1 and to 10 ns is found to be the same. The intrinsic is approximately twice the value of the MSD that is reached in simulations after times of 1 ns which correspond to those observed using neutron instruments that have an energy resolution width of 1 ?eV.

Vural, Derya; Hong, Liang; Smith, Jeremy C.; Glyde, Henry R.

2013-11-01

386

An Absolute Displacement Sensor Using Moire Fringe Techniques With Multimode Optical Fibres  

NASA Astrophysics Data System (ADS)

The feasibility of the use of optical fibres to supply light to, and relay information from, an absolute moire fringe displacement sensor has been demonstrated and a prototype built. Fringe interpolation techniques are employed which reduce the susceptibility of the sensor to adventitious intensity fluctuations. The system is designed to operate over a displacement range of 100 ?m and can resolve displacements down to 12 nm: nonlinearity is ±0.8 ?m, while hysteresis and repeatability are better than 0.3 ?m. The system is largely immune to intensity variations on the input light channel, however differential attenuation between any of the four return light channels more seriously affects the measurement. In order to try and avoid this problem an optical arrangement has been investigated in which intensity information corresponding to four quadrature points on the moire-fringe profile is carried in a single return optical fibre using wavelength separation.

Jones, Barry E.; Philp, Graeme S.

1985-08-01

387

Practical Fabry-Perot displacement interferometry in ambient air conditions with subnanometer accuracy  

NASA Astrophysics Data System (ADS)

Fabry-Perot displacement interferometry (FPI) offers high sensitivity and resolution with direct traceability to optical frequency standards. FPI can provide means for demanding calibration tasks in precision engineering and high-tech systems. We report on our investigation of the measurement methodology applied to highest precision capacitive displacement sensors. We use a dedicated metrological FPI instrumentation that provides an actuated reference target with a relatively large traceable displacement stroke. The envisaged sub-nanometer measurement uncertainty seems very challenging under practical ambient atmospheric conditions and with the necessary sensor mounting components. In anticipation of these limitations, we propose a new FPI instrumental configuration with a very short cavity and discuss expected benefits, most importantly the very low sensitivity to air refractive index variations and the versatility for practical calibration purposes. We aim again for sub-nanometer measurement uncertainty and report on the status of the experimental set-up for this short cavity FPI.

Voigt, Dirk; van de Nes, Arthur S.; van den Berg, Steven A.

2014-07-01

388

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

PubMed

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

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

2010-08-20

389

AN INTERFEROMETRIC ELECTRON RULER WITH PICOMETER ACCURACY IN GAUAGING LATTICE DISPLACEMENT.  

SciTech Connect

We report a novel technique to accurately measure interfacial lattice displacement by forming an electron probe close to a specimen in a manner similar to that originally proposed by Gabor to record a hologram. This method is based on the quantitative analysis of the interference pattern of shadow images in coherent electron diffraction. The approach is unique in that there are no adjustable microscope parameters, the contrast is strong even when the fault is viewed edge-on, and a large number of shadow images of the fault corresponding to different Bragg reflections can be studied simultaneously. Since it is an interferometric technique, the spatial resolution of the measurement is not limited by the wave length of the fast electrons. 1pm accuracy has been demonstrated in measuring the displacement associated stacking faults and grain boundaries in Bi-based superconductors. It is, to our knowledge, the highest that has been ever achieved in measurements of displacement vectors.

WU,L.; ZHU,Y.; TAFTO,J.

2001-08-05

390

History of Atomic Theory  

NSDL National Science Digital Library

Students research websites to find how the atomic theory has developed over the years. Ancient Greek Atoms shapes and sizes Read carefully on this website to find what Democritus thought about the shapes of atoms. Wikibooks Democritus Property of Atoms Atom Builder Atomic Magic Heisenberg (Wave Model Atomic Models PDF Handout Short and sweet and to the point for many of the atomic models used. Atomic Models Webquest Nice pictures of five models plus useful links. Atomic Theories Easy to read Data Table Atomic Theory Atomic Theory Atomic Theory Useful, includes illustration of ...

Mcnees, Mrs.

2010-10-26

391

Wide-area scanner for high-speed atomic force microscopy  

NASA Astrophysics Data System (ADS)

High-speed atomic force microscopy (HS-AFM) has recently been established. The dynamic processes and structural dynamics of protein molecules in action have been successfully visualized using HS-AFM. However, its maximum scan ranges in the X- and Y-directions have been limited to ˜1 ?m and ˜4 ?m, respectively, making it infeasible to observe the dynamics of much larger samples, including live cells. Here, we develop a wide-area scanner with a maximum XY scan range of ˜46 × 46 ?m2 by magnifying the displacements of stack piezoelectric actuators using a leverage mechanism. Mechanical vibrations produced by fast displacement of the X-scanner are suppressed by a combination of feed-forward inverse compensation and the use of triangular scan signals with rounded vertices. As a result, the scan speed in the X-direction reaches 6.3 mm/s even for a scan size as large as ˜40 ?m. The nonlinearity of the X- and Y-piezoelectric actuators' displacements that arises from their hysteresis is eliminated by polynomial-approximation-based open-loop control. The interference between the X- and Y-scanners is also eliminated by the same technique. The usefulness of this wide-area scanner is demonstrated by video imaging of dynamic processes in live bacterial and eukaryotic cells.

Watanabe, Hiroki; Uchihashi, Takayuki; Kobashi, Toshihide; Shibata, Mikihiro; Nishiyama, Jun; Yasuda, Ryohei; Ando, Toshio

2013-05-01

392

A Mechanical Model of Neural Tissue Displacement During Lorentz Effect Imaging  

PubMed Central

Song and co-workers recently proposed a method for MRI detection of biocurrents in nerves called “Lorentz Effect Imaging”. When exposed to a magnetic field, neural currents are subjected to a Lorentz force that moves the nerve. If the displacement is large enough, an artifact is predicted in the MR signal. In this paper, the displacement of a nerve of radius a in a surrounding tissue of radius b and shear modulus µ is analyzed. The nerve carries a current density J and lies in a magnetic field B. The solution to the resulting elasticity problem indicates that the nerve moves a distance BJ4?a2ln(ba). Using realistic parameters for a human median nerve in a 4 T field, this calculated displacement is 0.013 µm or less. The distribution of displacement is widespread throughout the tissue, and is not localized near the nerve. This displacement is orders of magnitude too small to be observed by conventional MRI methods. PMID:19097218

Roth, Bradley J.; Basser, Peter J.

2009-01-01

393

Local displacement of diapir contacts and its importance to pluton emplacement study  

NASA Astrophysics Data System (ADS)

The extent to which mid-crustal plutons have grown by diapirism cannot be deduced from the horizontal shortening of ductilely deformed host rocks and associated displacement of lateral intrusive contacts. By contrast, the vertical shortening above plutons and upward displacement of their roof contacts may provide a good measure of the diapiric component of pluton emplacement. This is related to the vertical bulk translation of buoyant material in immature diapirs and associated escape flow of overlying rocks. The length change of a vertical material line situated above the crest of an immature upright diapir corresponds to the upward displacement of the local contact. The length change of horizonal material lines situated at lateral contacts of model diapirs. however, differs markedly from the contact displacement. This is related to the absence of horizontal symmetry planes in the finite-strain field about upright diapirs of any shape, and the importance of vertical shear at the lateral contacts. The host-rock strain held of a hypothetical pluton grown in situ by spherical expansion ('ballooning') has an infinite number of symmetry planes. The strain held is characterized by large volume losses, but the length change of all radial lines corresponds to the local magnitude of contact displacement. This precludes the possibility of differentiating, in ductile host rocks above plutons. between vertical diapirism and spherical expansion—unless gauges of volume change are available.

Schwerdtner, W. M.

1995-06-01

394

Automatic Alignment of Displacement-Measuring Interferometer  

NASA Technical Reports Server (NTRS)

A control system strives to maintain the correct alignment of a laser beam in an interferometer dedicated to measuring the displacement or distance between two fiducial corner-cube reflectors. The correct alignment of the laser beam is parallel to the line between the corner points of the corner-cube reflectors: Any deviation from parallelism changes the length of the optical path between the reflectors, thereby introducing a displacement or distance measurement error. On the basis of the geometrical optics of corner-cube reflectors, the length of the optical path can be shown to be L = L(sub 0)cos theta, where L(sub 0) is the distance between the corner points and theta is the misalignment angle. Therefore, the measurement error is given by DeltaL = L(sub 0)(cos theta - 1). In the usual case in which the misalignment is small, this error can be approximated as DeltaL approximately equal to -L(sub 0)theta sup 2/2. The control system (see figure) is implemented partly in hardware and partly in software. The control system includes three piezoelectric actuators for rapid, fine adjustment of the direction of the laser beam. The voltages applied to the piezoelectric actuators include components designed to scan the beam in a circular pattern so that the beam traces out a narrow cone (60 microradians wide in the initial application) about the direction in which it is nominally aimed. This scan is performed at a frequency (2.5 Hz in the initial application) well below the resonance frequency of any vibration of the interferometer. The laser beam makes a round trip to both corner-cube reflectors and then interferes with the launched beam. The interference is detected on a photodiode. The length of the optical path is measured by a heterodyne technique: A 100- kHz frequency shift between the launched beam and a reference beam imposes, on the detected signal, an interferometric phase shift proportional to the length of the optical path. A phase meter comprising analog filters and specialized digital circuitry converts the phase shift to an indication of displacement, generating a digital signal proportional to the path length.

Halverson, Peter; Regehr, Martin; Spero, Robert; Alvarez-Salazar, Oscar; Loya, Frank; Logan, Jennifer

2006-01-01

395

Strong-field physics: Displaced creation  

NASA Astrophysics Data System (ADS)

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

Küpper, Jochen

2014-08-01

396

DNA strand displacement system running logic programs.  

PubMed

The paper presents a DNA-based computing model which is enzyme-free and autonomous, not requiring a human intervention during the computation. The model is able to perform iterated resolution steps with logical formulae in conjunctive normal form. The implementation is based on the technique of DNA strand displacement, with each clause encoded in a separate DNA molecule. Propositions are encoded assigning a strand to each proposition p, and its complementary strand to the proposition ¬p; clauses are encoded comprising different propositions in the same strand. The model allows to run logic programs composed of Horn clauses by cascading resolution steps. The potential of the model is demonstrated also by its theoretical capability of solving SAT. The resulting SAT algorithm has a linear time complexity in the number of resolution steps, whereas its spatial complexity is exponential in the number of variables of the formula. PMID:24211259

Rodríguez-Patón, Alfonso; Sainz de Murieta, Iñaki; Sosík, Petr

2014-01-01

397

Inertia and scaling in deterministic lateral displacement  

E-print Network

The ability to separate and analyze chemical species with high resolution, sensitivity, and throughput is central to the development of microfluidics systems. Deterministic lateral displacement (DLD) is a continuous separation method based on the transport of species through an array of obstacles. In the case of force-driven DLD (f-DLD), size-based separation can be modelled effectively using a simple particle-obstacle collision model. We use a macroscopic model to study f-DLD and demonstrate, via a simple scaling, that the method is indeed predominantly a size-based phenomenon at low Reynolds numbers. More importantly, we demonstrate that inertia effects provide the additional capability to separate same size particles but of different densities and could enhance separation at high throughput conditions. We also show that a direct conversion of macroscopic results to microfluidic settings is possible with a simple scaling based on the size of the obstacles that results in a universal curve.

Drazer, Timothy J Bowman German

2014-01-01

398

An Alternative to Maxwell's Displacement Current  

E-print Network

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

Wolsky, Alan M

2014-01-01

399

Characterizing anomalous diffusion by studying displacements  

NASA Astrophysics Data System (ADS)

Subordinated Lévy processes provide very diverse conceptual models for mass transport, beside other paradigms (e.g., fractional Brownian motion) generalizing Brownian motion. Some of that many models exhibit similar empirical Mean Squared Displacements growing non-linearly with time, while their increments have very different characteristic functions. In many media, such functionals can be directly measured, but accurate inversion methods adapted to them and to subordinated processes are still lacking. We show that each such process is associated to an operator that transforms the deviation from 1 of the characteristic function of its increments into a quantity that does not depend on the wave-number. We build an inversion method based on this property: it deduces the individual identity of each subordinated Lévy process from data sampling the characteristic functions of its increments.

Rakotonasy, S. H.; Néel, M. C.; Joelson, M.

2014-07-01

400

Axial flow positive displacement worm gas generator  

NASA Technical Reports Server (NTRS)

An axial flow positive displacement engine has an inlet axially spaced apart and upstream from an outlet. Inner and outer bodies have offset inner and outer axes extend from the inlet to the outlet through first, second, and third sections of a core assembly in serial downstream flow relationship. At least one of the bodies is rotatable about its axis. The inner and outer bodies have intermeshed inner and outer helical blades wound about the inner and outer axes respectively. The inner and outer helical blades extend radially outwardly and inwardly respectively. The helical blades have first, second, and third twist slopes in the first, second, and third sections respectively. The first twist slopes are less than the second twist slopes and the third twist slopes are less than the second twist slopes. A combustor section extends axially downstream through at least a portion of the second section.

Murrow, Kurt David (Inventor); Giffin, Rollin George (Inventor); Fakunle, Oladapo (Inventor)

2010-01-01

401

Intrinsic mean-square displacements in proteins  

NASA Astrophysics Data System (ADS)

The thermal mean-square displacement (MSD) of hydrogen in proteins and its associated hydration water is measured by neutron scattering experiments and used an indicator of protein function. The observed MSD as currently determined depends on the energy resolution width of the neutron scattering instrument employed. We propose a method for obtaining the intrinsic MSD of H in the proteins, one that is independent of the instrument resolution width. The intrinsic MSD is defined as the infinite time value of that appears in the Debye-Waller factor. The method consists of fitting a model to the resolution broadened elastic incoherent structure factor or to the resolution dependent MSD. The model contains the intrinsic MSD, the instrument resolution width, and a rate constant characterizing the motions of H in the protein. The method is illustrated by obtaining the intrinsic MSD of heparan sulphate (HS-0.4), ribonuclease A, and staphysloccal nuclase (SNase) from data in the literature.

Vural, Derya; Glyde, Henry R.

2012-07-01

402

Intrinsic Mean Square Displacement in Lysozyme  

NASA Astrophysics Data System (ADS)

The internal dynamics of proteins is the essential interest of biophysics. The mean square displacement (MSD) of hydrogen in proteins and its associated hydration water is obtained by molecular dynamic (MD) simulation. The MSD as currently determined depends on the time of the MD simulation. A method is proposed in this paper to obtain the intrinsic MSD of hydrogen in the proteins. The intrinsic MSD is independent of the simulation time and defined as the infinite time value of calculated MSD that appears in the Debye-Waller factor. The method consists of fitting a model to the incoherent intermediate scattering function. The model contains the intrinsic MSD and a rate constant characterizing the motions of H in the protein. The method is illustrated by obtaining the intrinsic MSD of lysozyme in 100 ns and 1 ?s MD simulations.

Vural, Derya; Glyde, Henry R.; Hong, Liang

2013-03-01

403

Energy dissipation in multifrequency atomic force microscopy  

PubMed Central

Summary The instantaneous displacement, velocity and acceleration of a cantilever tip impacting onto a graphite surface are reconstructed. The total dissipated energy and the dissipated energy per cycle of each excited flexural mode during the tip interaction is retrieved. The tip dynamics evolution is studied by wavelet analysis techniques that have general relevance for multi-mode atomic force microscopy, in a regime where few cantilever oscillation cycles characterize the tip–sample interaction. PMID:24778976

Pukhova, Valentina; Banfi, Francesco

2014-01-01

404

Systematic review of mini-implant displacement under orthodontic loading  

PubMed Central

A growing number of studies have reported that mini-implants do not remain in exactly the same position during treatment, although they remain stable. The aim of this review was to collect data regarding primary displacement immediately straight after loading and secondary displacement over time. A systematic review was performed to investigate primary and secondary displacement. The amount and type of displacement were recorded. A total of 27 studies were included. Sixteen in vitro studies or studies using finite element analysis addressed primary displacement, and nine clinical studies and two animal studies addressed secondary displacement. Significant primary displacement was detected (6.4–24.4 µm) for relevant orthodontic forces (0.5–2.5 N). The mean secondary displacement ranged from 0 to 2.7 mm for entire mini-implants. The maximum values for each clinical study ranged from 1.0 to 4.1 mm for the head, 1.0 to 1.5 for the body and 1.0 to 1.92 mm for the tail part. The most frequent type of movement was controlled tipping or bodily movement. Primary displacement did not reach a clinically significant level. However, clinicians can expect relevant secondary displacement in the direction of force. Consequently, decentralized insertion within the inter-radicular space, away from force direction, might be favourable. More evidence is needed to provide quantitative recommendations. PMID:24357855

Nienkemper, Manuel; Handschel, Jorg; Drescher, Dieter

2014-01-01

405

Tunable axial potentials for atom chip waveguides  

E-print Network

We present a method for generating algebraically precise magnetic potentials along the axis of a cold atom waveguide near the surface of an atom chip. With a single chip design consisting of several wire pairs, various axial potentials can be created, including double wells, triple wells, and pure harmonic traps with suppression of higher order terms. We characterize the error along a harmonic trap between the expected algebraic form and magnetic field simulations and find excel- lent agreement, particularly at small displacements from the trap center. Finally, we demonstrate experimental control over the bottom fields of an asymmetric double well potential.

Stickney, James A; Imhof, Eric; Kroese, Bethany R; Crow, Jonathon A R; Olson, Spencer E; Squires, Matthew B

2014-01-01

406

Linear stability of radial displacements in porous media: Influence of velocity-induced dispersion and concentration-dependent diffusion  

Microsoft Academic Search

A parametric study is conducted in order to investigate the influence of (a) velocity dependent dispersion, and (b) concentration-dependent diffusion on the stability of miscible porous media displacements in the radial geometry. Numerical solutions for the base concentration profile demonstrate that velocity induced dispersion dominates for short times and large Péclet numbers. For large times, the growth rates approach those

A. Riaz; C. Pankiewitz; E. Meiburg

2004-01-01

407

Atomic Mobile  

NSDL National Science Digital Library

In this hands-on OLogy activity, kids learn about matter by building their own models of carbon out of pipe cleaners, wire, and clay. The activity begins with a kid-friendly introduction to matter, elements, and atoms. The illustrated, step-by-step directions show how to use the information about carbon on the Periodic Table to create a mobile that shows the element's basic structure. A PDF version of the Periodic Table, along with a kid-friendly overview of how to read it, is also included.

408

Character displacement in some Cnemidophorus lizards revisited: A phylogenetic analysis  

PubMed Central

Ecological studies have demonstrated the role of competition in structuring communities; however, the importance of competition as a vehicle for evolution by natural selection and speciation remains unresolved. Study systems of insular faunas have provided several well known cases where ecological character displacement, coevolution of competitors leading to increased morphological separation, is thought to have occurred (e.g., anoline lizards and geospizine finches). Whiptail lizards (genus Cnemidophorus) from the islands of the Sea of Cortez and the surrounding mainland demonstrate a biogeographic pattern of morphological variation suggestive of character displacement. Two species of Cnemidophorus occur on the Baja peninsula, one relatively large (Cnemidophorus tigris) and one smaller (Cnemidophorus hyperythrus). Oceanic islands in the Sea of Cortez contain only single species, five of six having sizes intermediate to both species found on the Baja peninsula. On mainland Mexico C. hyperythrus is absent, whereas C. tigris is the smaller species in whiptail guilds. Here we construct a phylogeny using nucleotide sequences of the cytochrome b gene to infer the evolutionary history of body size change and historical patterns of colonization in the Cnemidophorus system. The phylogenetic analysis indicates that (i) oceanic islands have been founded at least five times from mainland sources by relatives of either C. tigris or C. hyperythrus, (ii) there have been two separate instances of character relaxation on oceanic islands for C. tigris, and (iii) there has been colonization of the oceanic island Cerralvo with retention of ancestral size for Cnemidophorus ceralbensis, a relative of C. hyperythrus. Finally, the phylogenetic analysis reveals potential cryptic species within mainland populations of C. tigris. PMID:9275194

Radtkey, Ray. R.; Fallon, Sylvia M.; Case, Ted J.

1997-01-01

409

Contribution of visual velocity and displacement cues to human balancing of support surface tilt.  

PubMed

Vision helps humans in controlling bipedal stance, interacting mainly with vestibular and proprioceptive cues. This study investigates how postural compensation of support surface tilt is compromised by selectively reducing visual velocity cues by stroboscopic illumination of a stationary visual scene. Healthy adult subjects were presented with pseudorandom tilt sequences in the sagittal plane (tilt frequency range 0.017-2.2 Hz; velocity amplitude spectrum constant up to a frequency of 0.6 Hz, angular displacement amplitude spectrum increasing with decreasing frequencies). Center of mass (COM) sway responses were recorded for stroboscopic illuminations at 48, 32, 16, 8, and 4 Hz, as well as under continuous illumination and with eyes closed. With strobe duration (5 ms) and mean luminance (1 lx) kept constant, visual acuity and perceived brightness remained constant and the visual scene was perceived as stationary. Yet, tilt-evoked COM excursions increased with decreasing strobe frequency in a graded way, with largest effects occurring at tilt frequencies where large tilt velocities coincided with small displacements. In addition, COM excursions were reduced at the lowest strobe frequency compared to eyes closed, with the largest effect occurring at tilt frequencies where tilt displacements were large. We conclude that two mechanisms exist, a velocity mechanism that deals with tilt compensation and is foremost affected by the stroboscopic illumination and a displacement mechanism. This compares favorably to previous findings that, transferred to a stance control model, suggest a velocity mechanism for tilt compensation and a position mechanism for gravity compensation. PMID:23686151

Assländer, Lorenz; Hettich, Georg; Gollhofer, Albert; Mergner, Thomas

2013-07-01

410

Prismatic displacement effect of progressive multifocal glasses on reaction time and accuracy in elderly people  

PubMed Central

Background Multifocal glasses (bifocals, trifocals, and progressives) increase the risk of falling in elderly people, but how they do so is unclear. To explain why glasses with progressive addition lenses increase the risk of falls and whether this can be attributed to false projection, this study aimed to 1) map the prismatic displacement of a progressive lens, and 2) test whether this displacement impaired reaction time and accuracy. Methods The reaction times of healthy ?75-year-olds (31 participants) were measured when grasping for a bar and touching a black line. Participants performed each test twice, wearing their progressives and new, matched single vision (distance) glasses in random order. The line and bar targets were positioned according to the maximum and minimum prismatic displacement effect through the progressive lens, mapped using a focimeter. Results Progressive spectacle lenses have large areas of prismatic displacement in the central visual axis and edges. Reaction time was faster for progressives compared with single vision glasses with a centrally-placed horizontal grab bar (mean difference 101 ms, P=0.011 [repeated measures analysis]) and a horizontal black line placed 300 mm below center (mean difference 80 ms, P=0.007). There was no difference in accuracy between the two types of glasses. Conclusion Older people appear to adapt to the false projection of progressives in the central visual axis. This adaptation means that swapping to new glasses or a large change in prescription may lead to a fall. Frequently updating glasses may be more beneficial. PMID:24872674

Ellison, Ashton C; Campbell, A John; Robertson, M Clare; Sanderson, Gordon F

2014-01-01

411

Atomic Resolution (0.94 ) Structure of Clostridium acidurici Ferredoxin. Detailed Geometry of [4Fe-4S] Clusters in a Protein,  

E-print Network

Atomic Resolution (0.94 Ã?) Structure of Clostridium acidurici Ferredoxin. Detailed Geometry of [4Fe-ray diffraction data extending to atomic resolution, 0.94 Ã?, recorded at 100 K. The model was refined with anisotropic representation of atomic displacement parameters for all non-hydrogen atoms and with hydrogens

412

Displacement of the proton in hydrogen-bonded complexes of hydrogen fluoride by beryllium and magnesium ions  

NASA Astrophysics Data System (ADS)

The displacement of the proton by a beryllium ion and by a magnesium ion from hydrogen-bonded complexes of hydrogen fluoride, of varying hydrogen bond strengths, was investigated theoretically using ab initio methods. Stable metal-containing species were obtained from all of the hydrogen-bonded complexes regardless of the strength of the hydrogen bond. It was found that the beryllium ion was energetically very effective in displacing the proton from hydrogen bonds, whereas the magnesium ion was unable to do so. The high stability of the beryllium-containing complexes is mainly due to the strong electrostatic bonding between the beryllium and fluoride atoms. This work supports the recent finding from a multidisciplinary bioinorganic study that beryllium displaces the proton in many strong hydrogen bonds.

McDowell, Sean A. C.

2009-05-01

413

Displacement of the proton in hydrogen-bonded complexes of hydrogen fluoride by beryllium and magnesium ions  

SciTech Connect

The displacement of the proton by a beryllium ion and by a magnesium ion from hydrogen-bonded complexes of hydrogen fluoride, of varying hydrogen bond strengths, was investigated theoretically using ab initio methods. Stable metal-containing species were obtained from all of the hydrogen-bonded complexes regardless of the strength of the hydrogen bond. It was found that the beryllium ion was energetically very effective in displacing the proton from hydrogen bonds, whereas the magnesium ion was unable to do so. The high stability of the beryllium-containing complexes is mainly due to the strong electrostatic bonding between the beryllium and fluoride atoms. This work supports the recent finding from a multidisciplinary bioinorganic study that beryllium displaces the proton in many strong hydrogen bonds.

McDowell, Sean A. C. [Department of Biological and Chemical Sciences, University of the West Indies, Cave Hill Campus (Barbados)

2009-05-14

414

Atomic Archive  

NSDL National Science Digital Library

This site explores the science, history, and consequences of the invention of the atomic bomb. It offers information about the events and decisions that led to the development of the bomb and the events and decisions that followed, from Hiroshima and Nagasaki to today's post-Cold War era. For users who wish to understand how nuclear weapons work, the site explains basic atomic physics, nuclear fission, and nuclear fusion. It also explores the effects of nuclear weapons and ponders several "what-if" scenarios. The history section tells the stories of the first nuclear reactor and the first nuclear test in New Mexico's desert. A Resource Library includes historical documents and biographies of the nuclear pioneers, including J. Robert Oppenheimer, Albert Einstein, Edward Teller, Enrico Fermi, Hans Bethe, and many others. The site offers educators such teaching aids as interactive maps, animations, a timeline of the nuclear age, and a glossary of terms. The Nuclear News section offers topical summaries of current events pertaining to nuclear issues.

2005-02-22

415

Atomic Models, Nagaoka's Saturnian Model  

Microsoft Academic Search

In late 1903, Hantaro Nagaoka (1865–1950) developed the earliest published quasi-planetary model of the atom. This graduate\\u000a of the University of Tokyo from 1887 spent his postdoctoral period in Vienna, Berlin and Munich before obtaining a professorship\\u000a in Tokyo to become Japan's foremost modern physicist. Nagaoka assumed that the atom is a large, massive, positively charged\\u000a sphere, encircled by very

Klaus Hentschel

416

Atom Skimmers and Atom Lasers Utilizing Them  

NASA Technical Reports Server (NTRS)

Atom skimmers are devices that act as low-pass velocity filters for atoms in thermal atomic beams. An atom skimmer operating in conjunction with a suitable thermal atomic-beam source (e.g., an oven in which cesium is heated) can serve as a source of slow atoms for a magneto-optical trap or other apparatus in an atomic-physics experiment. Phenomena that are studied in such apparatuses include Bose-Einstein condensation of atomic gases, spectra of trapped atoms, and collisions of slowly moving atoms. An atom skimmer includes a curved, low-thermal-conduction tube that leads from the outlet of a thermal atomic-beam source to the inlet of a magneto-optical trap or other device in which the selected low-velocity atoms are to be used. Permanent rare-earth magnets are placed around the tube in a yoke of high-magnetic-permeability material to establish a quadrupole or octupole magnetic field leading from the source to the trap. The atoms are attracted to the locus of minimum magnetic-field intensity in the middle of the tube, and the gradient of the magnetic field provides centripetal force that guides the atoms around the curve along the axis of the tube. The threshold velocity for guiding is dictated by the gradient of the magnetic field and the radius of curvature of the tube. Atoms moving at lesser velocities are successfully guided; faster atoms strike the tube wall and are lost from the beam.

Hulet, Randall; Tollett, Jeff; Franke, Kurt; Moss, Steve; Sackett, Charles; Gerton, Jordan; Ghaffari, Bita; McAlexander, W.; Strecker, K.; Homan, D.

2005-01-01

417

Atomic Transport/ Dense Metallic  

E-print Network

Atomic Transport/ Dense Metallic Hydrogen Separation Systems #12;Participants -- Atomic Transport contaminants + partial pressure #12;Technology Options ­ Atomic Transport/Dense Metallic Systems Pd alloy intensification Membrane plus reactor #12;Barrier Categories-- Atomic Transport/Dense Metallic Systems Membrane

418

Evolution of atomic collision cascades in vanadium crystal with internal structure  

NASA Astrophysics Data System (ADS)

The formation of radiation-damage regions (radiation-damage cascades) in vanadium crystallites with internal structures (intergrain boundary) has been simulated by the molecular-dynamic method. The interatomic interaction is described within the embedded-atom method. A relatively small number of clusters of intrinsic point defects (vacancies and self-interstitial atoms) are formed both in ideal vanadium crystallites and in crystallites with boundaries after the relaxation of atomic-displacement cascades. The evolutionary character of atomic-displacement cascades is determined in many respects by the presence of extended boundaries in materials. The intergrain boundaries hinder the propagation of atomic-displacement cascades and store many radiation-induced defects.

Psakhie, S. G.; Zolnikov, K. P.; Kryzhevich, D. S.; Zheleznyakov, A. V.; Chernov, V. M.

2009-11-01

419

Correlation between Displacement Damage Dose and Proton Irradiation Effects on GaInP/GaAs/Ge Space Solar Cells  

NASA Astrophysics Data System (ADS)

The irradiation effects of 0.28-2.80 MeV protons on GaInP/GaAs/Ge solar cells have been analysed, and then correlated with the displacement damage dose. The results of I-V and spectral response measurements, combined with the SRIM-derived vacancies produced rates, show that the degradation of the solar cells is largely determined by the displacement damage of the GaAs sub-cell. Thus the SRIM-derived NIEL values for protons in the GaAs sub-cell are used to calculate the displacement damage dose. It is shown that the irradiation effects of the solar cells caused by protons at different energies are correlated well with the aid of displacement damage dose.

Liu, Yun-Hong; Wang, Rong; Cui, Xin-Yu; Wang, Yong-Xia

2009-02-01

420

Palaeoseismology related to the displaced Roman archaeological remains at Egna (Adige Valley, northern Italy)  

NASA Astrophysics Data System (ADS)

A Roman building of the 1st century AD has been discovered during archaeological excavations in the village of Egna (Adige Valley, NE Italy) on the distal portion of a large Holocene alluvial fan. The remnants of the walls appear to have been displaced by shear planes having oblique movement with a minor dextral component. Subsequent palaeoseismological analyses have been performed through the excavation of seven trenches inside the ancient building; all of the trenches showed that the sedimentary units have also been displaced. The deepest trench (>6 m) also showed a sudden increase of the vertical offset in the lower portion of the sedimentary succession, therefore suggesting a displacement event which preceded the Roman age event. Archaeological dating of the numerous remains and radiocarbon dating of organic silt, bone and wood fragments permitted the reconstruction of the site history. The most recent event occurred around the middle of the 3rd century AD and was responsible for the displacement, destruction and consequent abandonment of the site, whereas the older event occurred not much after 2581-2197 BC. The alluvial fan deposition occurred after the 3rd century AD (0.60-1.5 m of historical deposits) and the intense urbanisation of the site hid all surficial traces of the 3rd century AD displacement. Geomorphological surveys and drilling data (four boreholes up to 20 m deep) exclude the possibility that the observed displacements were caused by gravity-driven phenomena. It is much more likely that they are the expression of fault activity, possibly related to the Giudicarie fault system. While moderate seismic activity and evidence of recent tectonics have been reported for the southern sector of this structural system, the present palaeoseismological analysis indicates that the northern sector may have also caused earthquakes which resulted in significant surficial deformation.

Galadini, Fabrizio; Galli, Paolo

1999-07-01

421

(Super)alkali atoms interacting with the ? electron cloud: a novel interaction mode triggers large nonlinear optical response of M@P? and M@C?H? (M=Li, Na, K and Li?O).  

PubMed

Under high-level ab initio calculations, the geometrical structures and nonlinear optical properties of M@P? (M=Li, Na, K and Li?O) and M@C?H? (M=Li and Li?O) were investigated; all were found to exhibit considerable first hyperpolarizabilities (18110, 1440, 22490, 50487, 2757 and 31776 au, respectively). The computational results revealed that when doping the (super)alkali atom M into the tetrahedral P? molecule, the original dual spherical aromaticity of the P? moiety is broken and new ? electron cloud is formed on the face of P? part interacting with the M atom. It was found that interaction of the (super)alkali atom with the ? electron cloud is a novel mode to produce diffuse excess electrons effectively to achieve a considerable ?? value. Further, beyond the alkali atom, employing the superalkali unit can be a more effective approach to significantly enhance the first hyperpolarizability of the systems, due to the much lower vertical ionization potential. These results were further supported by the case of the (super)alkali atom interacting with the cyclopropane C?H? molecule with its typical ? aromatic electron cloud. Moreover, the ?? values of the M@P? series are nonmonotonic dependent on alkali atomic number, namely, 1440 au (M = Na) < 18110 au (Li) < 22490 au (K), inferring that the distance between the alkali atom and the interacting surface with the ? electron cloud in P4 is a crucial geometrical factor in determining their first hyperpolarizabilities. These intriguing findings will be advantageous for promoting the design of novel high-performance nonlinear optical materials. PMID:24271644

Zhao, Xingang; Yu, Guangtao; Huang, Xuri; Chen, Wei; Niu, Min

2013-12-01

422

Airbag roll marks & displaced rocks and soil  

NASA Technical Reports Server (NTRS)

Looking southwest from the lander, soil disturbances indicating the spacecraft rolled through the landing site are visible. Arriving from the east, the lander, still encased in its protective airbags, rolled up a slight rise and then rolled back down to its final position. The inset at left shows displaced rocks near the rock 'Flat Top.' Dark patches of disturbed soil indicate where the rocks had originally rested Both insets show rocks that were pushed into the soil from the weight of the lander, visible from the areas of raised rims of dark, disturbed soil around several rocks. The south summit of Twin Peaks is in the background, while a lander petal, deflated airbag, and rear rover deployment ramp are in the foreground.

Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator. JPL is an operating division of the California Institute of Technology (Caltech).

1997-01-01

423

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

424

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

425

Falciparum malaria in a displaced Haitian population.  

PubMed

Falciparum malaria was a major problem among displaced Haitians in temporary camps at the US Naval Base, Guantanamo Bay, Cuba. From December 1991 to March 1992, 235 cases of unmixed falciparum malaria were diagnosed in the laboratory, giving a cumulative attack rate of 160 per 10 000 camp residents. All cases were successfully treated with oral chloroquine. Children under 16 years of age, and especially females, were at substantially higher risk of infection (attack rate 481/10 000 versus 278/ 10 000 for males in the same age range). Malaria attack rates by place of birth in Haiti were calculated per 10 000 people as Cayemite, 530; Baraderes, 375; Pestel, 285; Port Au Prince, 247; and La Gonave, 36. The time to onset of clinical malaria after embarking at the Naval Base ranged from one to 58 d. No malaria transmission was demonstrated in the migrant camp. A non-systematic survey showed a 1.7% prevalence (95% confidence interval +/- 1.9%) of falciparum malaria among asymptomatic residents. Health practitioners in areas that may receive Haitian migrants should plan to care for malaria and preventive medicine measures are indicated, as imported malaria could be transmitted in areas where competent vectors are indigenous. PMID:8594667

Bawden, M P; Slaten, D D; Malone, J D

1995-01-01

426

Percutaneous calcaneoplasty in displaced intraarticular calcaneal fractures.  

PubMed

The ideal treatment for displaced intraarticular calcaneal fractures is still under debate. Open reduction and internal fixation is the most popular surgical procedure; however, wound complications, hardware failure and infection remain a major concern. The aim of this study was to evaluate the results of a new minimally-invasive surgical procedure: closed reduction technique combined with balloon-assisted fracture augmentation with cement or calcium phosphate (minimally-invasive percutaneous calcaneoplasty). We retrospectively reviewed 11 patients that sustained Sander's type II and III calcaneal fractures treated in our institution from January 2008 to June 2010. The same approach and technique was utilized in all cases. Conventional X-rays and CT scan have been performed pre- and post-operatively. The average follow-up was 24 months. The American Orthopaedic Foot and Ankle Society ankle/hindfoot score has been utilized for clinical evaluation and Bohler's angle to assess bone reduction. All cases obtained bony union in 2/3 months, with average Bohler's angle of 22.97° (from 14.21° to 32.83°). No skin complications or adverse reactions were observed, with only one patient complaining of residual pain in the hindfoot. Minimally-invasive percutaneous calcaneoplasty can represent an alternative to open reduction internal fixation in the treatment of calcaneal fractures, allowing stable reduction without plating, early function recovery and short hospital stay. PMID:23744105

Biggi, Francesco; Di Fabio, Stefano; D'Antimo, Corrado; Isoni, Francesco; Salfi, Cosimo; Trevisani, Silvia

2013-12-01

427

Effect of the interatomic potential on the features of displacement cascades in ?-Fe: A molecular dynamics study  

NASA Astrophysics Data System (ADS)

The primary state of damage obtained in molecular dynamics (MD) simulations of displacement cascades in ?-Fe, particularly the fraction of point-defects in clusters, depends on the interatomic potential used to describe the atomic interactions. The differences may influence the microstructural evolution predicted in damage accumulation models which use results from MD cascade simulations as input. In this work, a number of displacement cascades of energy ranging from 5 to 40 keV have been simulated using the same procedure with four different interatomic potentials for ?-Fe, each of them providing, among other things, varying descriptions of self-interstitial atoms (SIA) in this metal. The behaviour of the cascades at their different phases and the final surviving defect population have been studied and compared applying the same cascade analysis criteria for all potentials. The outcome is discussed trying to identify the characteristics of the potential that have the largest influence on the predicted primary state of damage.

Terentyev, D.; Lagerstedt, C.; Olsson, P.; Nordlund, K.; Wallenius, J.; Becquart, C. S.; Malerba, L.

2006-06-01

428

Inertial forces affect fluid front displacement dynamics in a pore-throat network model.  

PubMed

The seemingly regular and continuous motion of fluid displacement fronts in porous media at the macroscopic scale is propelled by numerous (largely invisible) pore-scale abrupt interfacial jumps and pressure bursts. Fluid fronts in porous media are characterized by sharp phase discontinuities and by rapid pore-scale dynamics that underlie their motion; both attributes challenge standard continuum theories of these flow processes. Moreover, details of pore-scale dynamics affect front morphology and subsequent phase entrapment behind a front and thereby shape key macroscopic transport properties of the unsaturated zone. The study presents a pore-throat network model that focuses on quantifying interfacial dynamics and interactions along fluid displacement fronts. The porous medium is represented by a lattice of connected pore throats capable of detaining menisci and giving rise to fluid-fluid interfacial jumps (the study focuses on flow rate controlled drainage). For each meniscus along the displacement front we formulate a local inertial, capillary, viscous, and hydrostatic force balance that is then solved simultaneously for the entire front. The model enables systematic evaluation of the role of inertia and boundary conditions. Results show that while displacement patterns are affected by inertial forces mainly by invasion of throats with higher capillary resistance, phase entrapment (residual saturation) is largely unaffected by inertia, limiting inertial effects on hydrological properties behind a front. Interfacial jump velocities are often an order of magnitude larger than mean front velocity, are strongly dependent on geometrical throat dimensions, and become less predictable (more scattered) when inertia is considered. Model simulations of the distributions of capillary pressure fluctuations and waiting times between invasion events follow an exponential distribution and are in good agreement with experimental results. The modeling approach provides insights into the rich pore-scale dynamics of displacement fronts; these insights not only improve the basic understanding of these ubiquitous processes, but could shed light on solute dispersion and colloids mobilization at fronts and the mechanical consequences of passing fronts. PMID:25215832

Moebius, Franziska; Or, Dani

2014-08-01

429

Determination of earthquake magnitude using GPS displacement waveforms from real-time precise point positioning  

NASA Astrophysics Data System (ADS)

For earthquake and tsunami early warning and emergency response, earthquake magnitude is the crucial parameter to be determined rapidly and correctly. However, a reliable and rapid measurement of the magnitude of an earthquake is a challenging problem, especially for large earthquakes (M > 8). Here, the magnitude is determined based on the GPS displacement waveform derived from real-time precise point positioning (RTPPP). RTPPP results are evaluated with an accuracy of 1 cm in the horizontal components and 2-3 cm in the vertical components, indicating that the RTPPP is capable of detecting seismic waves with amplitude of 1 cm horizontally and 2-3 cm vertically with a confidence level of 95 per cent. In order to estimate the magnitude, the unique information provided by the GPS displacement waveform is the horizontal peak displacement amplitude. We show that the empirical relation of Gutenberg (1945) between peak displacement and magnitude holds up to nearly magnitude 9.0 when displacements are measured with GPS. We tested the proposed method for three large earthquakes. For the 2010 Mw 7.2 El Mayor-Cucapah earthquake, our method provides a magnitude of M7.18 ± 0.18. For the 2011 Mw 9.0 Tohoku-oki earthquake the estimated magnitude is M8.74 ± 0.06, and for the 2010 Mw 8.8 Maule earthquake the value is M8.7 ± 0.1 after excluding some near-field stations. We, therefore, conclude that depending on the availability of high-rate GPS observations, a robust va