Navigation by light polarization in clear and turbid waters

PubMed Central

Lerner, Amit; Sabbah, Shai; Erlick, Carynelisa; Shashar, Nadav

2011-01-01

Certain terrestrial animals use sky polarization for navigation. Certain aquatic species have also been shown to orient according to a polarization stimulus, but the correlation between underwater polarization and Sun position and hence the ability to use underwater polarization as a compass for navigation is still under debate. To examine this issue, we use theoretical equations for per cent polarization and electric vector (e-vector) orientation that account for the position of the Sun, refraction at the air–water interface and Rayleigh single scattering. The polarization patterns predicted by these theoretical equations are compared with measurements conducted in clear and semi-turbid coastal sea waters at 2 m and 5 m depth over sea floors of 6 m and 28 m depth. We find that the per cent polarization is correlated with the Sun's elevation only in clear waters. We furthermore find that the maximum value of the e-vector orientation angle equals the angle of refraction only in clear waters, in the horizontal viewing direction, over the deeper sea floor. We conclude that navigation by use of underwater polarization is possible under restricted conditions, i.e. in clear waters, primarily near the horizontal viewing direction, and in locations where the sea floor has limited effects on the light's polarization. PMID:21282170

Anatomical Reconstruction and Functional Imaging Reveal an Ordered Array of Skylight Polarization Detectors in Drosophila.

PubMed

Weir, Peter T; Henze, Miriam J; Bleul, Christiane; Baumann-Klausener, Franziska; Labhart, Thomas; Dickinson, Michael H

2016-05-11

Many insects exploit skylight polarization as a compass cue for orientation and navigation. In the fruit fly, Drosophila melanogaster, photoreceptors R7 and R8 in the dorsal rim area (DRA) of the compound eye are specialized to detect the electric vector (e-vector) of linearly polarized light. These photoreceptors are arranged in stacked pairs with identical fields of view and spectral sensitivities, but mutually orthogonal microvillar orientations. As in larger flies, we found that the microvillar orientation of the distal photoreceptor R7 changes in a fan-like fashion along the DRA. This anatomical arrangement suggests that the DRA constitutes a detector for skylight polarization, in which different e-vectors maximally excite different positions in the array. To test our hypothesis, we measured responses to polarized light of varying e-vector angles in the terminals of R7/8 cells using genetically encoded calcium indicators. Our data confirm a progression of preferred e-vector angles from anterior to posterior in the DRA, and a strict orthogonality between the e-vector preferences of paired R7/8 cells. We observed decreased activity in photoreceptors in response to flashes of light polarized orthogonally to their preferred e-vector angle, suggesting reciprocal inhibition between photoreceptors in the same medullar column, which may serve to increase polarization contrast. Together, our results indicate that the polarization-vision system relies on a spatial map of preferred e-vector angles at the earliest stage of sensory processing. The fly's visual system is an influential model system for studying neural computation, and much is known about its anatomy, physiology, and development. The circuits underlying motion processing have received the most attention, but researchers are increasingly investigating other functions, such as color perception and object recognition. In this work, we investigate the early neural processing of a somewhat exotic sense, called polarization vision. Because skylight is polarized in an orientation that is rigidly determined by the position of the sun, this cue provides compass information. Behavioral experiments have shown that many species use the polarization pattern in the sky to direct locomotion. Here we describe the input stage of the fly's polarization-vision system. Copyright © 2016 the authors 0270-6474/16/365397-08$15.00/0.

System and method for extracting dominant orientations from a scene

DOEpatents

Straub, Julian; Rosman, Guy; Freifeld, Oren; Leonard, John J.; Fisher, III; , John W.

2017-05-30

In one embodiment, a method of identifying the dominant orientations of a scene comprises representing a scene as a plurality of directional vectors. The scene may comprise a three-dimensional representation of a scene, and the plurality of directional vectors may comprise a plurality of surface normals. The method further comprises determining, based on the plurality of directional vectors, a plurality of orientations describing the scene. The determined plurality of orientations explains the directionality of the plurality of directional vectors. In certain embodiments, the plurality of orientations may have independent axes of rotation. The plurality of orientations may be determined by representing the plurality of directional vectors as lying on a mathematical representation of a sphere, and inferring the parameters of a statistical model to adapt the plurality of orientations to explain the positioning of the plurality of directional vectors lying on the mathematical representation of the sphere.

Magnetic order, hysteresis, and phase coexistence in magnetoelectric LiCoPO 4

DOE PAGES

Fogh, Ellen; Toft-Petersen, Rasmus; Ressouche, Eric; ...

2017-09-15

Here, the magnetic phase diagram of magnetoelectric LiCoPO 4 is established using neutron diffraction and magnetometry in fields up to 25.9T applied along the crystallographic b axis. For fields greater than 11.9T, the magnetic unit cell triples in size with propagation vector Q = (0,1/3,0). A magnetized elliptic cycloid is formed with spins in the (b,c) plane and the major axis oriented along b. Such a structure allows for the magnetoelectric effect with an electric polarization along c induced by magnetic fields applied along b. Intriguingly, additional ordering vectors Q ≈ (0,1/4,0) and Q ≈ (0,1/2,0) appear for increasing fieldsmore » in the hysteresis region below the transition field. Traces of this behavior are also observed in the magnetization. A simple model based on a mean-field approach is proposed to explain these additional ordering vectors. In the field interval 20.5–21.0T, the propagation vector Q = (0,1/3,0) remains but the spins orient differently compared to the cycloid phase. Furthermore, above 21.0T and up until saturation, a commensurate magnetic structure exists with a ferromagnetic component along b and an antiferromagnetic component along« less

Alterations to the orientation of the ground reaction force vector affect sprint acceleration performance in team sports athletes.

PubMed

Bezodis, Neil E; North, Jamie S; Razavet, Jane L

2017-09-01

A more horizontally oriented ground reaction force vector is related to higher levels of sprint acceleration performance across a range of athletes. However, the effects of acute experimental alterations to the force vector orientation within athletes are unknown. Fifteen male team sports athletes completed maximal effort 10-m accelerations in three conditions following different verbal instructions intended to manipulate the force vector orientation. Ground reaction forces (GRFs) were collected from the step nearest 5-m and stance leg kinematics at touchdown were also analysed to understand specific kinematic features of touchdown technique which may influence the consequent force vector orientation. Magnitude-based inferences were used to compare findings between conditions. There was a likely more horizontally oriented ground reaction force vector and a likely lower peak vertical force in the control condition compared with the experimental conditions. 10-m sprint time was very likely quickest in the control condition which confirmed the importance of force vector orientation for acceleration performance on a within-athlete basis. The stance leg kinematics revealed that a more horizontally oriented force vector during stance was preceded at touchdown by a likely more dorsiflexed ankle, a likely more flexed knee, and a possibly or likely greater hip extension velocity.

In-situ Raman microprobe studies of plant cell walls: macromolecular organization and compositional variability in the secondary wall of Picea mariana (Mill.) B.S.P.

Treesearch

U.P. Agarwal; R.H. Atalla

1986-01-01

Native-state organization and distribution of cell-wall components in the secondary wall of woody tissue from P. mariana (Black Spruce) have been investigated using polarized Raman microspectroscopy. Evidence for orientation is detected through Raman intensity variations resulting from rotations of the exciting electric vector with respect to cell-wall geometry....

Cycle/Cocycle Oblique Projections on Oriented Graphs

NASA Astrophysics Data System (ADS)

Polettini, Matteo

2015-01-01

It is well known that the edge vector space of an oriented graph can be decomposed in terms of cycles and cocycles (alias cuts, or bonds), and that a basis for the cycle and the cocycle spaces can be generated by adding and removing edges to an arbitrarily chosen spanning tree. In this paper, we show that the edge vector space can also be decomposed in terms of cycles and the generating edges of cocycles (called cochords), or of cocycles and the generating edges of cycles (called chords). From this observation follows a construction in terms of oblique complementary projection operators. We employ this algebraic construction to prove several properties of unweighted Kirchhoff-Symanzik matrices, encoding the mutual superposition between cycles and cocycles. In particular, we prove that dual matrices of planar graphs have the same spectrum (up to multiplicities). We briefly comment on how this construction provides a refined formalization of Kirchhoff's mesh analysis of electrical circuits, which has lately been applied to generic thermodynamic networks.

Polynomial Chaos decomposition applied to stochastic dosimetry: study of the influence of the magnetic field orientation on the pregnant woman exposure at 50 Hz.

PubMed

Liorni, I; Parazzini, M; Fiocchi, S; Guadagnin, V; Ravazzani, P

2014-01-01

Polynomial Chaos (PC) is a decomposition method used to build a meta-model, which approximates the unknown response of a model. In this paper the PC method is applied to the stochastic dosimetry to assess the variability of human exposure due to the change of the orientation of the B-field vector respect to the human body. In detail, the analysis of the pregnant woman exposure at 7 months of gestational age is carried out, to build-up a statistical meta-model of the induced electric field for each fetal tissue and in the fetal whole-body by means of the PC expansion as a function of the B-field orientation, considering a uniform exposure at 50 Hz.

Haze, clouds and limited sky visibility: polarotactic orientation of crickets under difficult stimulus conditions.

PubMed

Henze, Miriam J; Labhart, Thomas

2007-09-01

Field crickets (Gryllus campestris L.) are able to detect the orientation of the electric vector (e-vector) of linearly polarized light. They presumably use this sense to exploit the celestial polarization pattern for course control or navigation. Polarization vision in crickets can be tested by eliciting a spontaneous polarotactic response. Previously, wide and 100% polarized stimuli were employed to induce this behavior. However, field crickets live on meadows where the observation of the sky is strongly limited by surrounding vegetation. Moreover, degrees of polarization (d) in the natural sky are much lower than 100%. We have therefore investigated thresholds for the behavioral response to polarized light under conditions mimicking those experienced by the insects in the field. We show that crickets are able to rely on polarized stimuli of just 1 degrees diameter. We also provide evidence that they exploit polarization down to an (average) polarization level of less than 7%, irrespective of whether the stimulus is homogeneous, such as under haze, or patched, such as a sky spotted by clouds. Our data demonstrate that crickets can rely on skylight polarization even under unfavorable celestial conditions, emphasizing the significance of polarized skylight orientation for insects.

Method and apparatus for improving the quality and efficiency of ultrashort-pulse laser machining

DOEpatents

Stuart, Brent C.; Nguyen, Hoang T.; Perry, Michael D.

2001-01-01

A method and apparatus for improving the quality and efficiency of machining of materials with laser pulse durations shorter than 100 picoseconds by orienting and maintaining the polarization of the laser light such that the electric field vector is perpendicular relative to the edges of the material being processed. Its use is any machining operation requiring remote delivery and/or high precision with minimal collateral dames.

Experimental investigation on a vectorized aerodynamic dielectric barrier discharge plasma actuator array

NASA Astrophysics Data System (ADS)

Neretti, Gabriele; Cristofolini, Andrea; Borghi, Carlo A.

2014-04-01

The Electro-Hydro-Dynamics (EHD) interaction, induced in atmospheric pressure still air by a surface dielectric barrier discharge (DBD) actuator, had been experimentally studied. A plasma aerodynamic actuator array, able to produce a vectorized jet, with the induced airflow oriented toward the desired direction, had been developed. The array was constituted by a sequence of single surface DBD actuators with kapton as dielectric material. An ac voltage in the range of 0-6 kV peak at 15 kHz had been used. The vectorization had been obtained by feeding the upper electrodes with different voltages and by varying the electrical connections. The lower electrodes had been connected either to ground or to the high voltage source, to produce the desired jet orientation and to avoid plasma formation acting in an undesired direction. Voltage and current measurements had been carried out to evaluate waveforms and to estimate the active power delivered to the discharge. Schlieren imaging allowed to visualize the induced jet and to estimate its orientation. Pitot measurements had been performed to obtain velocity profiles for all jet configurations. A proportional relation between the jet deflection angle and the applied voltage had been found. Moreover, a linear relation had been obtained between the maximum speed in the jet direction and the applied voltage. The active power of the discharge is approximated by both a power law function and an exponential function of the applied voltage.

Spin structure of electron subbands in (110)-grown quantum wells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nestoklon, M. O.; Tarasenko, S. A.; Jancu, J.-M.

We present the theory of fine structure of electron states in symmetric and asymmetric zinc-blende-type quantum wells with the (110) crystallographic orientation. By combining the symmetry analysis, sp{sup 3}d{sup 5}s* tight-binding method, and envelope-function approach we obtain quantitative description of in-plane wave vector, well width and applied electric field dependencies of the zero-magnetic-field spin splitting of electron subbands and extract spin-orbit-coupling parameters.

Evidence for instantaneous e-vector detection in the honeybee using an associative learning paradigm

PubMed Central

Sakura, Midori; Okada, Ryuichi; Aonuma, Hitoshi

2012-01-01

Many insects use the polarization pattern of the sky for obtaining compass information during orientation or navigation. E-vector information is collected by a specialized area in the dorsal-most part of the compound eye, the dorsal rim area (DRA). We tested honeybees' capability of learning certain e-vector orientations by using a classical conditioning paradigm with the proboscis extension reflex. When one e-vector orientation (CS+) was associated with sugar water, while another orientation (CS−) was not rewarded, the honeybees could discriminate CS+ from CS−. Bees whose DRA was inactivated by painting did not learn CS+. When ultraviolet (UV) polarized light (350 nm) was used for CS, the bees discriminated CS+ from CS−, but no discrimination was observed in blue (442 nm) or green light (546 nm). Our data indicate that honeybees can learn and discriminate between different e-vector orientations, sensed by the UV receptors of the DRA, suggesting that bees can determine their flight direction from polarized UV skylight during foraging. Fixing the bees' heads during the experiments did not prevent learning, indicating that they use an ‘instantaneous’ algorithm of e-vector detection; that is, the bees do not need to actively scan the sky with their DRAs (‘sequential’ method) to determine e-vector orientation. PMID:21733901

A New Unified Analysis of Estimate Errors by Model-Matching Phase-Estimation Methods for Sensorless Drive of Permanent-Magnet Synchronous Motors and New Trajectory-Oriented Vector Control, Part II

NASA Astrophysics Data System (ADS)

Shinnaka, Shinji

This paper presents a new unified analysis of estimate errors by model-matching extended-back-EMF estimation methods for sensorless drive of permanent-magnet synchronous motors. Analytical solutions about estimate errors, whose validity is confirmed by numerical experiments, are rich in universality and applicability. As an example of universality and applicability, a new trajectory-oriented vector control method is proposed, which can realize directly quasi-optimal strategy minimizing total losses with no additional computational loads by simply orienting one of vector-control coordinates to the associated quasi-optimal trajectory. The coordinate orientation rule, which is analytically derived, is surprisingly simple. Consequently the trajectory-oriented vector control method can be applied to a number of conventional vector control systems using model-matching extended-back-EMF estimation methods.

Accommodating electric propulsion on SMART-1

NASA Astrophysics Data System (ADS)

Kugelberg, Joakim; Bodin, Per; Persson, Staffan; Rathsman, Peter

2004-07-01

This paper focuses on the technical challenges that arise when electric propulsion is used on a small spacecraft such as SMART-1. The choice of electric propulsion influences not only the attitude control system and the power system, but also the thermal control as well as the spacecraft structure. A description is given on how the design of the attitude control system uses the possibility to control the alignment of the thrust vector in order to reduce the momentum build-up. An outline is made of the philosophy of power generation and distribution and shows how the thermal interfaces to highly dissipating units have been solved. Areas unique for electric propulsion are the added value of a thrust vector orientation mechanism and the special consideration given to the electromagnetic compatibility. SMART-1 is equipped with a thruster gimbal mechanism providing a 10° cone in which the thrust vector can be pointed. Concerning the electromagnetic compatibility, a discussion on how to evaluate the available test results is given keeping in mind that one of the main objectives of the SMART-1 mission is to assess the impact of electric propulsion on the scientific instruments and on other spacecraft systems. Finally, the assembly, integration and test of the spacecraft is described. Compared to traditional propulsion systems, electric propulsion puts different requirements on the integration sequence and limits the possibilities to verify the correct function of the thruster since it needs high quality vacuum in order to operate. Prime contractor for SMART-1 is the Swedish Space Corporation (SSC). The electric propulsion subsystem is procured directly by ESA from SNECMA, France and is delivered to SSC as a customer furnished item. The conclusion of this paper is that electric propulsion is possible on a small spacecraft, which opens up possibilities for a new range of missions for which a large velocity increment is needed. The paper will also present SMART-1 and show how the problems related to the accommodation of electric propulsion have been solved during design and planning of the project.

Electrical valley filtering in transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Hsieh, Tzu-Chi; Chou, Mei-Yin; Wu, Yu-Shu

2018-03-01

This work investigates the feasibility of electrical valley filtering for holes in transition metal dichalcogenides. We look specifically into the scheme that utilizes a potential barrier to produce valley-dependent tunneling rates, and perform the study with both a k .p -based analytic method and a recursive Green's function-based numerical method. The study yields the transmission coefficient as a function of incident energy and transverse wave vector, for holes going through lateral quantum barriers oriented in either armchair or zigzag directions, in both homogeneous and heterogeneous systems. The main findings are the following: (1) The tunneling current valley polarization increases with increasing barrier width or height; (2) both the valley-orbit interaction and band structure warping contribute to valley-dependent tunneling, with the former contribution being manifest in structures with asymmetric potential barriers, and the latter being orientation dependent and reaching maximum for transmission in the armchair direction; and (3) for transmission ˜0.1 , a tunneling current valley polarization of the order of 10 % can be achieved.

Development of a unified guidance system for geocentric transfer. [for solar electric propulsion spacecraft

NASA Technical Reports Server (NTRS)

Cake, J. E.; Regetz, J. D., Jr.

1975-01-01

A method is presented for open loop guidance of a solar electric propulsion spacecraft to geosynchronous orbit. The method consists of determining the thrust vector profiles on the ground with an optimization computer program, and performing updates based on the difference between the actual trajectory and that predicted with a precision simulation computer program. The motivation for performing the guidance analysis during the mission planning phase is discussed, and a spacecraft design option that employs attitude orientation constraints is presented. The improvements required in both the optimization program and simulation program are set forth, together with the efforts to integrate the programs into the ground support software for the guidance system.

Development of a unified guidance system for geocentric transfer. [solar electric propulsion spacecraft

NASA Technical Reports Server (NTRS)

Cake, J. E.; Regetz, J. D., Jr.

1975-01-01

A method is presented for open loop guidance of a solar electric propulsion spacecraft to geosynchronsus orbit. The method consists of determining the thrust vector profiles on the ground with an optimization computer program, and performing updates based on the difference between the actual trajectory and that predicted with a precision simulation computer program. The motivation for performing the guidance analysis during the mission planning phase is discussed, and a spacecraft design option that employs attitude orientation constraints is presented. The improvements required in both the optimization program and simulation program are set forth, together with the efforts to integrate the programs into the ground support software for the guidance system.

Polarized skylight navigation in insects: model and electrophysiology of e-vector coding by neurons in the central complex.

PubMed

Sakura, Midori; Lambrinos, Dimitrios; Labhart, Thomas

2008-02-01

Many insects exploit skylight polarization for visual compass orientation or course control. As found in crickets, the peripheral visual system (optic lobe) contains three types of polarization-sensitive neurons (POL neurons), which are tuned to different ( approximately 60 degrees diverging) e-vector orientations. Thus each e-vector orientation elicits a specific combination of activities among the POL neurons coding any e-vector orientation by just three neural signals. In this study, we hypothesize that in the presumed orientation center of the brain (central complex) e-vector orientation is population-coded by a set of "compass neurons." Using computer modeling, we present a neural network model transforming the signal triplet provided by the POL neurons to compass neuron activities coding e-vector orientation by a population code. Using intracellular electrophysiology and cell marking, we present evidence that neurons with the response profile of the presumed compass neurons do indeed exist in the insect brain: each of these compass neuron-like (CNL) cells is activated by a specific e-vector orientation only and otherwise remains silent. Morphologically, CNL cells are tangential neurons extending from the lateral accessory lobe to the lower division of the central body. Surpassing the modeled compass neurons in performance, CNL cells are insensitive to the degree of polarization of the stimulus between 99% and at least down to 18% polarization and thus largely disregard variations of skylight polarization due to changing solar elevations or atmospheric conditions. This suggests that the polarization vision system includes a gain control circuit keeping the output activity at a constant level.

Reconstruction of the domain orientation distribution function of polycrystalline PZT ceramics using vector piezoresponse force microscopy.

PubMed

Kratzer, Markus; Lasnik, Michael; Röhrig, Sören; Teichert, Christian; Deluca, Marco

2018-01-11

Lead zirconate titanate (PZT) is one of the prominent materials used in polycrystalline piezoelectric devices. Since the ferroelectric domain orientation is the most important parameter affecting the electromechanical performance, analyzing the domain orientation distribution is of great importance for the development and understanding of improved piezoceramic devices. Here, vector piezoresponse force microscopy (vector-PFM) has been applied in order to reconstruct the ferroelectric domain orientation distribution function of polished sections of device-ready polycrystalline lead zirconate titanate (PZT) material. A measurement procedure and a computer program based on the software Mathematica have been developed to automatically evaluate the vector-PFM data for reconstructing the domain orientation function. The method is tested on differently in-plane and out-of-plane poled PZT samples, and the results reveal the expected domain patterns and allow determination of the polarization orientation distribution function at high accuracy.

Reconstruction of interatomic vectors by principle component analysis of nuclear magnetic resonance data in multiple alignments

NASA Astrophysics Data System (ADS)

Hus, Jean-Christophe; Bruschweiler, Rafael

2002-07-01

A general method is presented for the reconstruction of interatomic vector orientations from nuclear magnetic resonance (NMR) spectroscopic data of tensor interactions of rank 2, such as dipolar coupling and chemical shielding anisotropy interactions, in solids and partially aligned liquid-state systems. The method, called PRIMA, is based on a principal component analysis of the covariance matrix of the NMR parameters collected for multiple alignments. The five nonzero eigenvalues and their eigenvectors efficiently allow the approximate reconstruction of the vector orientations of the underlying interactions. The method is demonstrated for an isotropic distribution of sample orientations as well as for finite sets of orientations and internuclear vectors encountered in protein systems.

A New Unified Analysis of Estimate Errors by Model-Matching Phase-Estimation Methods for Sensorless Drive of Permanent-Magnet Synchronous Motors and New Trajectory-Oriented Vector Control, Part I

NASA Astrophysics Data System (ADS)

Shinnaka, Shinji; Sano, Kousuke

This paper presents a new unified analysis of estimate errors by model-matching phase-estimation methods such as rotor-flux state-observers, back EMF state-observers, and back EMF disturbance-observers, for sensorless drive of permanent-magnet synchronous motors. Analytical solutions about estimate errors, whose validity is confirmed by numerical experiments, are rich in universality and applicability. As an example of universality and applicability, a new trajectory-oriented vector control method is proposed, which can realize directly quasi-optimal strategy minimizing total losses with no additional computational loads by simply orienting one of vector-control coordinates to the associated quasi-optimal trajectory. The coordinate orientation rule, which is analytically derived, is surprisingly simple. Consequently the trajectory-oriented vector control method can be applied to a number of conventional vector control systems using one of the model-matching phase-estimation methods.

Maplike representation of celestial E-vector orientations in the brain of an insect.

PubMed

Heinze, Stanley; Homberg, Uwe

2007-02-16

For many insects, the polarization pattern of the blue sky serves as a compass cue for spatial navigation. E-vector orientations are detected by photoreceptors in a dorsal rim area of the eye. Polarized-light signals from both eyes are finally integrated in the central complex, a brain area consisting of two subunits, the protocerebral bridge and the central body. Here we show that a topographic representation of zenithal E-vector orientations underlies the columnar organization of the protocerebral bridge in a locust. The maplike arrangement is highly suited to signal head orientation under the open sky.

Electric control of wave vector filtering in a hybrid magnetic-electric-barrier nanostructure

NASA Astrophysics Data System (ADS)

Kong, Yong-Hong; Lu, Ke-Yu; He, Ya-Ping; Liu, Xu-Hui; Fu, Xi; Li, Ai-Hua

2018-06-01

We theoretically investigate how to manipulate the wave vector filtering effect by a traverse electric field for electrons across a hybrid magnetic-electric-barrier nanostructure, which can be experimentally realized by depositing a ferromagnetic stripe and a Schottky-metal stripe on top and bottom of a GaAs/Al x Ga1- x As heterostructure, respectively. The wave vector filtering effect is found to be related closely to the applied electric field. Moreover, the wave vector filtering efficiency can be manipulated by changing direction or adjusting strength of the traverse electric field. Therefore, such a nanostructure can be employed as an electrically controllable electron-momentum filter for nanoelectronics applications.

Angular-dependent EDMR linewidth for spin-dependent space charge limited conduction in a polycrystalline pentacene

NASA Astrophysics Data System (ADS)

Fukuda, Kunito; Asakawa, Naoki

2017-08-01

Spin-dependent space charge limited carrier conduction in a Schottky barrier diode using polycrystalline p-type π-conjugated molecular pentacene is explored using multiple-frequency electrically detected magnetic resonance (EDMR) spectroscopy with a variable-angle configuration. The measured EDMR spectra are decomposed into two components derived respectively from mobile and trapped positive polarons. The linewidth of the EDMR signal for the trapped polarons increases with increasing resonance magnetic field for an in-plane configuration where the normal vector of the device substrate is perpendicular to the resonance magnetic field, while it is independent of the field for an out-of-plane configuration. This difference is consistent with the pentacene arrangement on the device substrate, where pentacene molecules exhibit a uniaxial orientation on the out-of-substrate plane. By contrast, the mobile polarons do not show anisotropic behavior with respect to the resonance magnetic field, indicating that the anisotropic effect is averaged out owing to carrier motion. These results suggest that the orientational arrangements of polycrystalline pentacene molecules in a nano thin film play a crucial role in spin-dependent electrical conduction.

Combined fast multipole-QR compression technique for solving electrically small to large structures for broadband applications

NASA Technical Reports Server (NTRS)

Jandhyala, Vikram (Inventor); Chowdhury, Indranil (Inventor)

2011-01-01

An approach that efficiently solves for a desired parameter of a system or device that can include both electrically large fast multipole method (FMM) elements, and electrically small QR elements. The system or device is setup as an oct-tree structure that can include regions of both the FMM type and the QR type. An iterative solver is then used to determine a first matrix vector product for any electrically large elements, and a second matrix vector product for any electrically small elements that are included in the structure. These matrix vector products for the electrically large elements and the electrically small elements are combined, and a net delta for a combination of the matrix vector products is determined. The iteration continues until a net delta is obtained that is within predefined limits. The matrix vector products that were last obtained are used to solve for the desired parameter.

Light scattering of rectangular slot antennas: parallel magnetic vector vs perpendicular electric vector

NASA Astrophysics Data System (ADS)

Lee, Dukhyung; Kim, Dai-Sik

2016-01-01

We study light scattering off rectangular slot nano antennas on a metal film varying incident polarization and incident angle, to examine which field vector of light is more important: electric vector perpendicular to, versus magnetic vector parallel to the long axis of the rectangle. While vector Babinet’s principle would prefer magnetic field along the long axis for optimizing slot antenna function, convention and intuition most often refer to the electric field perpendicular to it. Here, we demonstrate experimentally that in accordance with vector Babinet’s principle, the incident magnetic vector parallel to the long axis is the dominant component, with the perpendicular incident electric field making a small contribution of the factor of 1/|ε|, the reciprocal of the absolute value of the dielectric constant of the metal, owing to the non-perfectness of metals at optical frequencies.

System and method employing a minimum distance and a load feature database to identify electric load types of different electric loads

DOEpatents

Lu, Bin; Yang, Yi; Sharma, Santosh K; Zambare, Prachi; Madane, Mayura A

2014-12-23

A method identifies electric load types of a plurality of different electric loads. The method includes providing a load feature database of a plurality of different electric load types, each of the different electric load types including a first load feature vector having at least four different load features; sensing a voltage signal and a current signal for each of the different electric loads; determining a second load feature vector comprising at least four different load features from the sensed voltage signal and the sensed current signal for a corresponding one of the different electric loads; and identifying by a processor one of the different electric load types by determining a minimum distance of the second load feature vector to the first load feature vector of the different electric load types of the load feature database.

In vitro effects of direct current electric fields on adipose-derived stromal cells.

PubMed

Hammerick, Kyle E; Longaker, Michael T; Prinz, Fritz B

2010-06-18

Endogenous electric fields play an important role in embryogenesis, regeneration, and wound repair and previous studies have shown that many populations of cells, leukocytes, fibroblasts, epithelial cells, and endothelial cells, exhibit directed migration in response to electric fields. As regenerative therapies continue to explore ways to control mesenchymal progenitor cells to recreate desirable tissues, it is increasingly necessary to characterize the vast nature of biological responses imposed by physical phenomena. Murine adipose-derived stromal cells (mASCs) migrated toward the cathode in direct current (DC) fields of physiologic strength and show a dose dependence of migration rate to stronger fields. Electric fields also caused mASCs to orient perpendicularly to the field vector and elicited a transient increase in cytosolic calcium. Additionally, their galvanotactic response appears to share classic chemotactic signaling pathways that are involved in the migration of other cell types. Galvanotaxis is one predominant result of electric fields on mASCs and it may be exploited to engineer adult stem cell concentrations and locations within implanted grafts or toward sites of wound repair. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Mechanism of competitive grain growth in a curvilinear channel of crystal-sorter during the orientational solidification of nickel-based heat-resistant alloy

NASA Astrophysics Data System (ADS)

Monastyrskiy, V. P.; Pozdnyakov, A. N.; Ershov, M. Yu.; Monastyrskiy, A. V.

2017-07-01

Using numerical simulation in the ProCAST program complex, the conditions of the solidification of heat-resistant nickel alloy in curvilinear channels of a ceramic mold have been investigated. It has been shown that, in practically important cases, the vector of the temperature gradient is oriented along the axis of the curvilinear channel. In a spiral crystal selector, a cyclic change in the preferred direction of growth occurs because of the cyclic change in the direction of the vector of the temperature gradient. The fact that the vector of the temperature gradient is almost always directed along the axis of the curvilinear channel makes it possible to govern the orientation of the vector of the temperature gradient in space and, therefore, to obtain a grain with the preferred crystallographic orientation. Based on the results of this investigation, a method of the grain selection with a desired azimuthal orientation is proposed.

Dynamics of the Solar Wind Electromagnetic Energy Transmission Into Magnetosphere during Large Geomagnetic Storms

NASA Astrophysics Data System (ADS)

Kuznetsova, Tamara; Laptukhov, Alexej; Petrov, Valery

Causes of the geomagnetic activity (GA) in the report are divided into temporal changes of the solar wind parameters and the changes of the geomagnetic moment orientation relative directions of the solar wind electric and magnetic fields. Based on our previous study we concluded that a reconnection based on determining role of mutual orientation of the solar wind electric field and geomagnetic moment taking into account effects of the Earth's orbital and daily motions is the most effective compared with existing mechanisms. At present a reconnection as paradigma that has applications in broad fields of physics needs analysis of experimental facts to be developed. In terms of reconnection it is important not only mutual orientation of vectors describing physics of interaction region but and reconnection rate which depends from rate of energy flux to those regions where the reconnection is permitted. Applied to magnetosphere these regions first of all are dayside magnetopause and polar caps. Influence of rate of the energy flux to the lobe magnetopause (based on calculations of the Poyting electromagnetic flux component controlling the reconnection rate along the solar wind velocity Pv) on planetary GA (Dst, Kp indices) is investigated at different phases of geomagnetic storms. We study also the rate of energy flux to the polar caps during storms (based on calculations of the Poyting flux vector component along the geomagnetic moment Pm) and its influence on magnetic activity in the polar ionosphere: at the auroral zone (AU,AL indices). Results allow to evaluate contributions of high and low latitude sources of electromagnetic energy to the storm development and also to clear mechanism of the electromagnetic energy transmission from the solar wind to the magnetosphere. We evaluate too power of the solar wind electromagnetic energy during well-known large storms and compare result with power of the energy sources of other geophysical processes (atmosphere, ocean, earthquakes and etc). The study was supported by a grant of RFBR, n 06-05-64998.

Generation of uniformly oriented in-plane magnetization with near-unity purity in 4π microscopy.

PubMed

Wang, Sicong; Cao, Yaoyu; Li, Xiangping

2017-12-01

In this Letter, we numerically demonstrate the all-optical generation of uniformly oriented in-plane magnetization with near-unity purity (more than 99%) under a 4π microscopic configuration. This is achieved through focusing two counter-propagating vector beams consisting of coherently configured linear and radial components. Based on the Debye diffraction theory, constructive and destructive interferences of the focal field components can be tailored under the 4π configuration to generate high-purity uniformly polarized transverse and longitudinal electric-field components in the center of the focal region. Consequently, near-unity purity in-plane magnetization with a uniform orientation within the focal volume defined by the full width at half-maximum can be created through the inverse Faraday effect. In addition, it reveals that the purity of the in-plane magnetization is robust against the numerical aperture of the focal lens. This result expands the flexibility of magnetization manipulations through light and holds great potential in all-optical magnetic recording and spintronics.

A force vector and surface orientation sensor for intelligent grasping

NASA Technical Reports Server (NTRS)

Mcglasson, W. D.; Lorenz, R. D.; Duffie, N. A.; Gale, K. L.

1991-01-01

The paper discusses a force vector and surface orientation sensor suitable for intelligent grasping. The use of a novel four degree-of-freedom force vector robotic fingertip sensor allows efficient, real time intelligent grasping operations. The basis of sensing for intelligent grasping operations is presented and experimental results demonstrate the accuracy and ease of implementation of this approach.

A challenging hysteresis operator for the simulation of Goss-textured magnetic materials

NASA Astrophysics Data System (ADS)

Cardelli, Ermanno; Faba, Antonio; Laudani, Antonino; Pompei, Michele; Quondam Antonio, Simone; Fulginei, Francesco Riganti; Salvini, Alessandro

2017-06-01

A new hysteresis operator for the simulation of Goss-textured ferromagnets is here defined. The operator is derived from the classic Stoner-Wohlfarth model, where the anisotropy energy is assumed to be cubic instead of uniaxial, in order to reproduce the magnetic behavior of Goss textured ferromagnetic materials, such as grain-oriented Fe-Si alloys, Ni-Fe alloys, and Ni-Co alloys. A vector hysteresis model based on a single hysteresis operator is then implemented and used for the prediction of the rotational magnetizations that have been measured in a sample of grain-oriented electrical steel. This is especially promising for FEM based calculations, where the magnetization state in each point must be recalculated at each time step. Finally, the computed loops, as well as the magnetic losses, are compared to the measured data.

Rotation Detection Using the Precession of Molecular Electric Dipole Moment

NASA Astrophysics Data System (ADS)

Ke, Yi; Deng, Xiao-Bing; Hu, Zhong-Kun

2017-11-01

We present a method to detect the rotation by using the precession of molecular electric dipole moment in a static electric field. The molecular electric dipole moments are polarized under the static electric field and a nonzero electric polarization vector emerges in the molecular gas. A resonant radio-frequency pulse electric field is applied to realize a 90° flip of the electric polarization vector of a particular rotational state. After the pulse electric field, the electric polarization vector precesses under the static electric field. The rotation induces a shift in the precession frequency which is measured to deduce the angular velocity of the rotation. The fundamental sensitivity limit of this method is estimated. This work is only a proposal and does not involve experimental results.

The increase in the starting torque of PMSM motor by applying of FOC method

NASA Astrophysics Data System (ADS)

Plachta, Kamil

2017-05-01

The article presents field oriented control method of synchronous permanent magnet motor equipped in optical sensors. This method allows for a wide range regulation of torque and rotational speed of the electric motor. The paper presents mathematical model of electric motor and vector control method. Optical sensors have shorter time response as compared to the inductive sensors, which allow for faster response of the electronic control system to changes of motor loads. The motor driver is based on the digital signal processor which performs advanced mathematical operations in real time. The appliance of Clark and Park transformation in the software defines the angle of rotor position. The presented solution provides smooth adjustment of the rotational speed in the first operating zone and reduces the dead zone of the torque in the second and third operating zones.

A comparison of in situ measurements of vector-E and - vector-V x vector-B from Dynamics Explorer 2

NASA Technical Reports Server (NTRS)

Hanson, W. B.; Coley, W. R.; Heelis, R. A.; Maynard, N. C.; Aggson, T. L.

1993-01-01

Dynamics Explorer-2 provided the first opportunity to make a direct comparison of in situ measurements of the high-latitude convection electric field by two distinctly different techniques. The vector electric field instrument (VEFI) used antennae to measure the intrinsic electric fields and the ion drift meter (IDM) and retarding potential analyzer (RPA) measured the ion drift velocity vector, from which the convection electric field can be deduced. The data from three orbits having large electric fields at high latitude are presented, one at high, one at medium, and one at low altitudes. The general agreement between the two measurements of electric field is very good, with typical differences at high latitudes of the order of a few millivolts per meter, but there are some regions where the particle fluxes are extremely large (e.g., the cusp) and the disagreement is worse, probably because of IDM difficulties. The auroral zone potential patterns derived from the two devices are in excellent agreement for two of the cases, but not in the third, where bad attitude data may be the problem. At low latitudes there are persistent differences in the measurements of a few millivolts per meter, though these differences are quite constant from orbit to orbit. This problem seems to arise from some shortcoming in the VEFI measurments. Overall, however, these measurements confirm the concept of `frozen-in' plasma that drifts with velocity vector-E x vector-B/B(exp 2) within the measurement errors of the two techniques.

Orientation of Calcium in the Mn4Ca Cluster of the Oxygen-Evolving Complex Determined Using Polarized Strontium EXAFS of Photosystem II Membranes†

PubMed Central

Cinco, Roehl M.; Robblee, John H.; Messinger, Johannes; Fernandez, Carmen; Holman, Karen L. McFarlane; Sauer, Kenneth; Yachandra, Vittal K.

2014-01-01

The oxygen-evolving complex of photosystem II (PS II) in green plants and algae contains a cluster of four Mn atoms in the active site, which catalyzes the photoinduced oxidation of water to dioxygen. Along with Mn, calcium and chloride ions are necessary cofactors for proper functioning of the complex. The current study using polarized Sr EXAFS on oriented Sr-reactivated samples shows that Fourier peak II, which fits best to Mn at 3.5 Å rather than lighter atoms (C, N, O, or Cl), is dichroic, with a larger magnitude at 10° (angle between the PS II membrane normal and the X-ray electric field vector) and a smaller magnitude at 80°. Analysis of the dichroism of the Sr EXAFS yields a lower and upper limit of 0° and 23° for the average angle between the Sr–Mn vectors and the membrane normal and an isotropic coordination number (number of Mn neighbors to Sr) of 1 or 2 for these layered PS II samples. The results confirm the contention that Ca (Sr) is proximal to the Mn cluster and lead to refined working models of the heteronuclear Mn4Ca cluster of the oxygen-evolving complex in PS II. PMID:15491134

Mechanical remodeling of normally sized mammalian cells under a gravity vector.

PubMed

Zhang, Chen; Zhou, Lüwen; Zhang, Fan; Lü, Dongyuan; Li, Ning; Zheng, Lu; Xu, Yanhong; Li, Zhan; Sun, Shujin; Long, Mian

2017-02-01

Translocation of the dense nucleus along a gravity vector initiates mechanical remodeling of a cell, but the underlying mechanisms of cytoskeletal network and focal adhesion complex (FAC) reorganization in a mammalian cell remain unclear. We quantified the remodeling of an MC3T3-E1 cell placed in upward-, downward-, or edge-on-orientated substrate. Nucleus longitudinal translocation presents a high value in downward orientation at 24 h or in edge-on orientation at 72 h, which is consistent with orientation-dependent distribution of perinuclear actin stress fibers and vimentin cords. Redistribution of total FAC area and fractionized super mature adhesion number coordinates this dependence at short duration. This orientation-dependent remodeling is associated with nucleus flattering and lamin A/C phosphorylation. Actin depolymerization or Rho-associated protein kinase signaling inhibition abolishes the orientation dependence of nucleus translocation, whereas tubulin polymerization inhibition or vimentin disruption reserves the dependence. A biomechanical model is therefore proposed for integrating the mechanosensing of nucleus translocation with cytoskeletal remodeling and FAC reorganization induced by a gravity vector.-Zhang, C., Zhou, L., Zhang, F., Lü, D., Li, N., Zheng, L., Xu, Y., Li, Z., Sun, S., Long, M. Mechanical remodeling of normally sized mammalian cells under a gravity vector. © FASEB.

Amplitude and dynamics of polarization-plane signaling in the central complex of the locust brain

PubMed Central

Bockhorst, Tobias

2015-01-01

The polarization pattern of skylight provides a compass cue that various insect species use for allocentric orientation. In the desert locust, Schistocerca gregaria, a network of neurons tuned to the electric field vector (E-vector) angle of polarized light is present in the central complex of the brain. Preferred E-vector angles vary along slices of neuropils in a compasslike fashion (polarotopy). We studied how the activity in this polarotopic population is modulated in ways suited to control compass-guided locomotion. To this end, we analyzed tuning profiles using measures of correlation between spike rate and E-vector angle and, furthermore, tested for adaptation to stationary angles. The results suggest that the polarotopy is stabilized by antagonistic integration across neurons with opponent tuning. Downstream to the input stage of the network, responses to stationary E-vector angles adapted quickly, which may correlate with a tendency to steer a steady course previously observed in tethered flying locusts. By contrast, rotating E-vectors corresponding to changes in heading direction under a natural sky elicited nonadapting responses. However, response amplitudes were particularly variable at the output stage, covarying with the level of ongoing activity. Moreover, the responses to rotating E-vector angles depended on the direction of rotation in an anticipatory manner. Our observations support a view of the central complex as a substrate of higher-stage processing that could assign contextual meaning to sensory input for motor control in goal-driven behaviors. Parallels to higher-stage processing of sensory information in vertebrates are discussed. PMID:25609107

Laser printed nano-gratings: orientation and period peculiarities

NASA Astrophysics Data System (ADS)

Stankevič, Valdemar; Račiukaitis, Gediminas; Bragheri, Francesca; Wang, Xuewen; Gamaly, Eugene G.; Osellame, Roberto; Juodkazis, Saulius

2017-01-01

Understanding of material behaviour at nanoscale under intense laser excitation is becoming critical for future application of nanotechnologies. Nanograting formation by linearly polarised ultra-short laser pulses has been studied systematically in fused silica for various pulse energies at 3D laser printing/writing conditions, typically used for the industrial fabrication of optical elements. The period of the nanogratings revealed a dependence on the orientation of the scanning direction. A tilt of the nanograting wave vector at a fixed laser polarisation was also observed. The mechanism responsible for this peculiar dependency of several features of the nanogratings on the writing direction is qualitatively explained by considering the heat transport flux in the presence of a linearly polarised electric field, rather than by temporal and spatial chirp of the laser beam. The confirmed vectorial nature of the light-matter interaction opens new control of material processing with nanoscale precision.

Virtual head rotation reveals a process of route reconstruction from human vestibular signals

PubMed Central

Day, Brian L; Fitzpatrick, Richard C

2005-01-01

The vestibular organs can feed perceptual processes that build a picture of our route as we move about in the world. However, raw vestibular signals do not define the path taken because, during travel, the head can undergo accelerations unrelated to the route and also be orientated in any direction to vary the signal. This study investigated the computational process by which the brain transforms raw vestibular signals for the purpose of route reconstruction. We electrically stimulated the vestibular nerves of human subjects to evoke a virtual head rotation fixed in skull co-ordinates and measure its perceptual effect. The virtual head rotation caused subjects to perceive an illusory whole-body rotation that was a cyclic function of head-pitch angle. They perceived whole-body yaw rotation in one direction with the head pitched forwards, the opposite direction with the head pitched backwards, and no rotation with the head in an intermediate position. A model based on vector operations and the anatomy and firing properties of semicircular canals precisely predicted these perceptions. In effect, a neural process computes the vector dot product between the craniocentric vestibular vector of head rotation and the gravitational unit vector. This computation yields the signal of body rotation in the horizontal plane that feeds our perception of the route travelled. PMID:16002439

The role of computer-aided 3D surgery and stereolithographic modelling for vector orientation in premaxillary and trans-sinusoidal maxillary distraction osteogenesis.

PubMed

Varol, Altan; Basa, Selçuk

2009-06-01

Maxillary distraction osteogenesis is a challenging procedure when it is performed with internal submerged distractors due to obligation of setting accurate distraction vectors. Five patients with severe maxillary retrognathy were planned with Mimics 10.01 CMF and Simplant 10.01 software. Distraction vectors and rods of distractors were arranged in 3D environment and on STL models. All patients were operated under general anaesthesia and complete Le Fort I downfracture was performed. All distractions were performed according to orientated vectors. All patients achieved stable occlusion and satisfactory aesthetic outcome at the end of the treatment period. Preoperative bending of internal maxillary distractors prevents significant loss of operation time. 3D computer-aided surgical simulation and model surgery provide accurate orientation of distraction vectors for premaxillary and internal trans-sinusoidal maxillary distraction. Combination of virtual surgical simulation and stereolithographic models surgery can be validated as an effective method of preoperative planning for complicated maxillofacial surgery cases.

System and method employing a self-organizing map load feature database to identify electric load types of different electric loads

DOEpatents

Lu, Bin; Harley, Ronald G.; Du, Liang; Yang, Yi; Sharma, Santosh K.; Zambare, Prachi; Madane, Mayura A.

2014-06-17

A method identifies electric load types of a plurality of different electric loads. The method includes providing a self-organizing map load feature database of a plurality of different electric load types and a plurality of neurons, each of the load types corresponding to a number of the neurons; employing a weight vector for each of the neurons; sensing a voltage signal and a current signal for each of the loads; determining a load feature vector including at least four different load features from the sensed voltage signal and the sensed current signal for a corresponding one of the loads; and identifying by a processor one of the load types by relating the load feature vector to the neurons of the database by identifying the weight vector of one of the neurons corresponding to the one of the load types that is a minimal distance to the load feature vector.

Graviperception and gravitaxis in flagellates

NASA Astrophysics Data System (ADS)

Häder, D.-P.; Richter, P.; Ntefidou, M.; Lebert, M.

Unicellular flagellates perceive and react to the gravitational vector of the Earth. Previous hypotheses have suggested that the orientation is brought about by a passive physical mechanism such as buoyancy or hydrodynamic alignment. Recent results of experiments on parabolic rocket flights have revealed that in the photosynthetic Euglena only 10 % of the orientation can be explained by passive orientation while the remainder relies on an active physiological sensor and an internal sensory transduction chain. The cellular contents is heavier than the surrounding medium and consequently presses onto the lower membrane where it activates mechano-sensitive ion channels located at the front end under the trailing flagellum. These channels allow a gated influx of calcium (visualized by confocal microscopy) which depolarizes the internal electrical potential and eventually causes a course correction by the flagellar beating. Further elements in the transduction chain are cyclic AMP and related enzymes. Recent experiments during parabolic aircraft flights and on sounding rockets have confirmed this hypothesis and provided detailed insight into the biochemical sensory transduction chain. Currently the molecular mechanisms of graviperception are being studied.

Extraordinary-mode refractive-index change produced by the linear electro-optic effect in LiNbO3 and reverse-poled LiNbO3

NASA Astrophysics Data System (ADS)

Boyd, Joseph T.; Servizzi, Anthony J.; Sriram, S.; Kingsley, Stuart A.

1995-07-01

To examine aspects of an integrated photonic electric-field sensor, we calculate electro-optically induced refractive-index change in regular and reverse-poled LiNbO3. Specifically, for y-propagating extraordinary modes, we determine how index change depends on electric-field magnitude and direction. To accomplish this, changes in index-ellipsoid shape and orientation are found by the use of a numerical eigenvalue procedure to diagonalize the impermeability tensor; then, refractive index is calculated by the use of a vector reference-frame transformation and a small perturbation approximation. A general formula is inferred from calculations for specific field directions. Electro-optic coefficients for reverse-poled LiNbO3 are obtained by application of a tensor reference-frame transformation to those of LiNbO3. The index-calculation procedure has utility beyond the problem that is considered.

Adaptation of orientation vectors of otolith-related central vestibular neurons to gravity.

PubMed

Eron, Julia N; Cohen, Bernard; Raphan, Theodore; Yakushin, Sergei B

2008-09-01

Behavioral experiments indicate that central pathways that process otolith-ocular and perceptual information have adaptive capabilities. Because polarization vectors of otolith afferents are directly related to the electro-mechanical properties of the hair cell bundle, it is unlikely that they change their direction of excitation. This indicates that the adaptation must take place in central pathways. Here we demonstrate for the first time that otolith polarization vectors of canal-otolith convergent neurons in the vestibular nuclei have adaptive capability. A total of 10 vestibular-only and vestibular-plus-saccade neurons were recorded extracellularly in two monkeys before and after they were in side-down positions for 2 h. The spatial characteristics of the otolith input were determined from the response vector orientation (RVO), which is the projection of the otolith polarization vector, onto the head horizontal plane. The RVOs had no specific orientation before animals were in side-down positions but moved toward the gravitational axis after the animals were tilted for extended periods. Vector reorientations varied from 0 to 109 degrees and were linearly related to the original deviation of the RVOs from gravity in the position of adaptation. Such reorientation of central polarization vectors could provide the basis for changes in perception and eye movements related to prolonged head tilts relative to gravity or in microgravity.

The Structure of Martian Magnetosphere at the Dayside Terminator Region as Observed on MAVEN Spacecraft

NASA Astrophysics Data System (ADS)

Vaisberg, O. L.; Ermakov, V. N.; Shuvalov, S. D.; Zelenyi, L. M.; Halekas, J.; DiBraccio, G. A.; McFadden, J.; Dubinin, E. M.

2018-04-01

We analyzed 44 passes of the Mars Atmosphere and Volatile EvolutioN mission (MAVEN) spacecraft through the magnetosphere, arranged by the angle between electric field vector and the projection of spacecraft position radius vector in the plane perpendicular to the Mars-Sun line (θE). All passes were divided into three angular sectors near 0°, 90°, and 180° θE angles in order to estimate the role of the interplanetary magnetic field direction in plasma and magnetic properties of dayside Martian magnetosphere. The time interval chosen was from 17 January to 4 February 2016 when MAVEN was crossing the dayside magnetosphere at solar zenith angle 70°. Magnetosphere as the region with prevailing energetic planetary ions is always found between the magnetosheath and the ionosphere. The analysis of dayside interaction region showed that for each angular sector with different orientation of the solar wind electric field vector E = -1/c V × B one can find specific profiles of the magnetosheath, the magnetic barrier (Michel, 1971, https://doi.org/10.1029/RG009i002p00427; Zhang et al., 1991, https://doi.org/10.1029/91JA00088), and the magnetosphere. Magnetic barrier forms in front of the magnetosphere, and relative magnetic field magnitudes in these two domains vary. The average height of the boundary with ionosphere is 530 km, and the average height of the magnetopause is 730 km. We discuss the implications of the observed magnetosphere structure to the planetary ions loss mechanism.

Spatial orientation of caloric nystagmus in semicircular canal-plugged monkeys.

PubMed

Arai, Yasuko; Yakushin, Sergei B; Cohen, Bernard; Suzuki, Jun-Ichi; Raphan, Theodore

2002-08-01

We studied caloric nystagmus before and after plugging all six semicircular canals to determine whether velocity storage contributed to the spatial orientation of caloric nystagmus. Monkeys were stimulated unilaterally with cold ( approximately 20 degrees C) water while upright, supine, prone, right-side down, and left-side down. The decline in the slow phase velocity vector was determined over the last 37% of the nystagmus, at a time when the response was largely due to activation of velocity storage. Before plugging, yaw components varied with the convective flow of endolymph in the lateral canals in all head orientations. Plugging blocked endolymph flow, eliminating convection currents. Despite this, caloric nystagmus was readily elicited, but the horizontal component was always toward the stimulated (ipsilateral) side, regardless of head position relative to gravity. When upright, the slow phase velocity vector was close to the yaw and spatial vertical axes. Roll components became stronger in supine and prone positions, and vertical components were enhanced in side down positions. In each case, this brought the velocity vectors toward alignment with the spatial vertical. Consistent with principles governing the orientation of velocity storage, when the yaw component of the velocity vector was positive, the cross-coupled pitch or roll components brought the vector upward in space. Conversely, when yaw eye velocity vector was downward in the head coordinate frame, i.e., negative, pitch and roll were downward in space. The data could not be modeled simply by a reduction in activity in the ipsilateral vestibular nerve, which would direct the velocity vector along the roll direction. Since there is no cross coupling from roll to yaw, velocity storage alone could not rotate the vector to fit the data. We postulated, therefore, that cooling had caused contraction of the endolymph in the plugged canals. This contraction would deflect the cupula toward the plug, simulating ampullofugal flow of endolymph. Inhibition and excitation induced by such cupula deflection fit the data well in the upright position but not in lateral or prone/supine conditions. Data fits in these positions required the addition of a spatially orientated, velocity storage component. We conclude, therefore, that three factors produce cold caloric nystagmus after canal plugging: inhibition of activity in ampullary nerves, contraction of endolymph in the stimulated canals, and orientation of eye velocity to gravity through velocity storage. Although the response to convection currents dominates the normal response to caloric stimulation, velocity storage probably also contributes to the orientation of eye velocity.

Vector optical fields with polarization distributions similar to electric and magnetic field lines.

PubMed

Pan, Yue; Li, Si-Min; Mao, Lei; Kong, Ling-Jun; Li, Yongnan; Tu, Chenghou; Wang, Pei; Wang, Hui-Tian

2013-07-01

We present, design and generate a new kind of vector optical fields with linear polarization distributions modeling to electric and magnetic field lines. The geometric configurations of "electric charges" and "magnetic charges" can engineer the spatial structure and symmetry of polarizations of vector optical field, providing additional degrees of freedom assisting in controlling the field symmetry at the focus and allowing engineering of the field distribution at the focus to the specific applications.

Equivalent magnetic vector potential model for low-frequency magnetic exposure assessment

NASA Astrophysics Data System (ADS)

Diao, Y. L.; Sun, W. N.; He, Y. Q.; Leung, S. W.; Siu, Y. M.

2017-10-01

In this paper, a novel source model based on a magnetic vector potential for the assessment of induced electric field strength in a human body exposed to the low-frequency (LF) magnetic field of an electrical appliance is presented. The construction of the vector potential model requires only a single-component magnetic field to be measured close to the appliance under test, hence relieving considerable practical measurement effort—the radial basis functions (RBFs) are adopted for the interpolation of discrete measurements; the magnetic vector potential model can then be directly constructed by summing a set of simple algebraic functions of RBF parameters. The vector potentials are then incorporated into numerical calculations as the equivalent source for evaluations of the induced electric field in the human body model. The accuracy and effectiveness of the proposed model are demonstrated by comparing the induced electric field in a human model to that of the full-wave simulation. This study presents a simple and effective approach for modelling the LF magnetic source. The result of this study could simplify the compliance test procedure for assessing an electrical appliance regarding LF magnetic exposure.

Equivalent magnetic vector potential model for low-frequency magnetic exposure assessment.

PubMed

Diao, Y L; Sun, W N; He, Y Q; Leung, S W; Siu, Y M

2017-09-21

In this paper, a novel source model based on a magnetic vector potential for the assessment of induced electric field strength in a human body exposed to the low-frequency (LF) magnetic field of an electrical appliance is presented. The construction of the vector potential model requires only a single-component magnetic field to be measured close to the appliance under test, hence relieving considerable practical measurement effort-the radial basis functions (RBFs) are adopted for the interpolation of discrete measurements; the magnetic vector potential model can then be directly constructed by summing a set of simple algebraic functions of RBF parameters. The vector potentials are then incorporated into numerical calculations as the equivalent source for evaluations of the induced electric field in the human body model. The accuracy and effectiveness of the proposed model are demonstrated by comparing the induced electric field in a human model to that of the full-wave simulation. This study presents a simple and effective approach for modelling the LF magnetic source. The result of this study could simplify the compliance test procedure for assessing an electrical appliance regarding LF magnetic exposure.

Speed Sensorless Induction Motor Drives for Electrical Actuators: Schemes, Trends and Tradeoffs

NASA Technical Reports Server (NTRS)

Elbuluk, Malik E.; Kankam, M. David

1997-01-01

For a decade, induction motor drive-based electrical actuators have been under investigation as potential replacement for the conventional hydraulic and pneumatic actuators in aircraft. Advantages of electric actuator include lower weight and size, reduced maintenance and operating costs, improved safety due to the elimination of hazardous fluids and high pressure hydraulic and pneumatic actuators, and increased efficiency. Recently, the emphasis of research on induction motor drives has been on sensorless vector control which eliminates flux and speed sensors mounted on the motor. Also, the development of effective speed and flux estimators has allowed good rotor flux-oriented (RFO) performance at all speeds except those close to zero. Sensorless control has improved the motor performance, compared to the Volts/Hertz (or constant flux) controls. This report evaluates documented schemes for speed sensorless drives, and discusses the trends and tradeoffs involved in selecting a particular scheme. These schemes combine the attributes of the direct and indirect field-oriented control (FOC) or use model adaptive reference systems (MRAS) with a speed-dependent current model for flux estimation which tracks the voltage model-based flux estimator. Many factors are important in comparing the effectiveness of a speed sensorless scheme. Among them are the wide speed range capability, motor parameter insensitivity and noise reduction. Although a number of schemes have been proposed for solving the speed estimation, zero-speed FOC with robustness against parameter variations still remains an area of research for speed sensorless control.

Orientation Modeling for Amateur Cameras by Matching Image Line Features and Building Vector Data

NASA Astrophysics Data System (ADS)

Hung, C. H.; Chang, W. C.; Chen, L. C.

2016-06-01

With the popularity of geospatial applications, database updating is getting important due to the environmental changes over time. Imagery provides a lower cost and efficient way to update the database. Three dimensional objects can be measured by space intersection using conjugate image points and orientation parameters of cameras. However, precise orientation parameters of light amateur cameras are not always available due to their costliness and heaviness of precision GPS and IMU. To automatize data updating, the correspondence of object vector data and image may be built to improve the accuracy of direct georeferencing. This study contains four major parts, (1) back-projection of object vector data, (2) extraction of image feature lines, (3) object-image feature line matching, and (4) line-based orientation modeling. In order to construct the correspondence of features between an image and a building model, the building vector features were back-projected onto the image using the initial camera orientation from GPS and IMU. Image line features were extracted from the imagery. Afterwards, the matching procedure was done by assessing the similarity between the extracted image features and the back-projected ones. Then, the fourth part utilized line features in orientation modeling. The line-based orientation modeling was performed by the integration of line parametric equations into collinearity condition equations. The experiment data included images with 0.06 m resolution acquired by Canon EOS Mark 5D II camera on a Microdrones MD4-1000 UAV. Experimental results indicate that 2.1 pixel accuracy may be reached, which is equivalent to 0.12 m in the object space.

The coil orientation dependency of the electric field induced by TMS for M1 and other brain areas.

PubMed

Janssen, Arno M; Oostendorp, Thom F; Stegeman, Dick F

2015-05-17

The effectiveness of transcranial magnetic stimulation (TMS) depends highly on the coil orientation relative to the subject's head. This implies that the direction of the induced electric field has a large effect on the efficiency of TMS. To improve future protocols, knowledge about the relationship between the coil orientation and the direction of the induced electric field on the one hand, and the head and brain anatomy on the other hand, seems crucial. Therefore, the induced electric field in the cortex as a function of the coil orientation has been examined in this study. The effect of changing the coil orientation on the induced electric field was evaluated for fourteen cortical targets. We used a finite element model to calculate the induced electric fields for thirty-six coil orientations (10 degrees resolution) per target location. The effects on the electric field due to coil rotation, in combination with target site anatomy, have been quantified. The results confirm that the electric field perpendicular to the anterior sulcal wall of the central sulcus is highly susceptible to coil orientation changes and has to be maximized for an optimal stimulation effect of the motor cortex. In order to obtain maximum stimulation effect in areas other than the motor cortex, the electric field perpendicular to the cortical surface in those areas has to be maximized as well. Small orientation changes (10 degrees) do not alter the induced electric field drastically. The results suggest that for all cortical targets, maximizing the strength of the electric field perpendicular to the targeted cortical surface area (and inward directed) optimizes the effect of TMS. Orienting the TMS coil based on anatomical information (anatomical magnetic resonance imaging data) about the targeted brain area can improve future results. The standard coil orientations, used in cognitive and clinical neuroscience, induce (near) optimal electric fields in the subject-specific head model in most cases.

Cellular Mechanisms of Gravitropic Response in Higher Plants

NASA Astrophysics Data System (ADS)

Medvedev, Sergei; Smolikova, Galina; Pozhvanov, Gregory; Suslov, Dmitry

The evolutionary success of land plants in adaptation to the vectorial environmental factors was based mainly on the development of polarity systems. In result, normal plant ontogenesis is based on the positional information. Polarity is a tool by which the developing plant organs and tissues are mapped and the specific three-dimensional structure of the organism is created. It is due to their polar organization plants are able to orient themselves relative to the gravity vector and different vectorial cues, and to respond adequately to various stimuli. Gravitation is one of the most important polarized environmental factor that guides the development of plant organisms in space. Every plant can "estimate" its position relative to the gravity vector and correct it, if necessary, by means of polarized growth. The direction and the magnitude of gravitational stimulus are constant during the whole plant ontogenesis. The key plant response to the action of gravity is gravitropism, i.e. the directed growth of organs with respect to the gravity vector. This response is a very convenient model to study the mechanisms of plant orientation in space. The present report is focused on the main cellular mechanisms responsible for graviropic bending in higher plants. These mechanisms and structures include electric polarization of plant cells, Ca ({2+) }gradients, cytoskeleton, G-proteins, phosphoinositides and the machinery responsible for asymmetric auxin distribution. Those mechanisms tightly interact demonstrating some hierarchy and multiple feedbacks. The Ca (2+) gradients provide the primary physiological basis of polarity in plant cells. Calcium ions influence on the bioelectric potentials, the organization of actin cytoskeleton, the activity of Ca (2+) -binding proteins and Ca (2+) -dependent protein kinases. Protein kinases modulate transcription factors activity thereby regulating the gene expression and switching the developmental programs. Actin cytoskeleton affects the molecular machinery of polar auxin transport. It results in the changes of auxin gradients in plant organs and tissues, which modulate all cellular mechanisms of polarity via multiple feedback loops. The understanding of the mechanisms of plant organism orientation relative to the gravity vector will allow us to develop efficient technologies for plant growing in microgravity conditions at orbital space stations and during long piloted space flights. This work was supported by the grant of Russian Foundation for Basic Research (N 14-04-01-624) and by the grant of St.-Petersburg State University (N 1.38.233.2014).

Nonlinear Control of the Doubly Fed Induction Motor with Copper Losses Minimization for Electrical Vehicle

NASA Astrophysics Data System (ADS)

Drid, S.; Nait-Said, M.-S.; Tadjine, M.; Makouf, A.

2008-06-01

There is an increasing interest in electric vehicles due to environmental concerns. Recent efforts are directed toward developing an improved propulsion system for electric vehicles applications with minimal power losses. This paper deals with the high efficient vector control for the reduction of copper losses of the doubly fed motor. Firstly, the feedback linearization control based on Lyapunov approach is employed to design the underlying controller achieving the double fluxes orientation. The fluxes controllers are designed independently of the speed. The speed controller is designed using the Lyapunov method especially employed to the unknown load torques. The global asymptotic stability of the overall system is theoretically proven. Secondly, a new Torque Copper Losses Factor is proposed to deal with the problem of the machine copper losses. Its main function is to optimize the torque in keeping the machine saturation at an acceptable level. This leads to a reduction in machine currents and therefore their accompanied copper losses guaranteeing improved machine efficiency. The simulation results in comparative presentation confirm largely the effectiveness of the proposed DFIM control with a very interesting energy saving contribution.

The parallel-antiparallel signal difference in double-wave-vector diffusion-weighted MR at short mixing times: A phase evolution perspective

NASA Astrophysics Data System (ADS)

Finsterbusch, Jürgen

2011-01-01

Experiments with two diffusion weightings applied in direct succession in a single acquisition, so-called double- or two-wave-vector diffusion-weighting (DWV) experiments at short mixing times, have been shown to be a promising tool to estimate cell or compartment sizes, e.g. in living tissue. The basic theory for such experiments predicts that the signal decays for parallel and antiparallel wave vector orientations differ by a factor of three for small wave vectors. This seems to be surprising because in standard, single-wave-vector experiments the polarity of the diffusion weighting has no influence on the signal attenuation. Thus, the question how this difference can be understood more pictorially is often raised. In this rather educational manuscript, the phase evolution during a DWV experiment for simple geometries, e.g. diffusion between parallel, impermeable planes oriented perpendicular to the wave vectors, is considered step-by-step and demonstrates how the signal difference develops. Considering the populations of the phase distributions obtained, the factor of three between the signal decays which is predicted by the theory can be reproduced. Furthermore, the intermediate signal decay for orthogonal wave vector orientations can be derived when investigating diffusion in a box. Thus, the presented “phase gymnastics” approach may help to understand the signal modulation observed in DWV experiments at short mixing times.

Method and system for operating an electric motor

DOEpatents

Gallegos-Lopez, Gabriel; Hiti, Silva; Perisic, Milun

2013-01-22

Methods and systems for operating an electric motor having a plurality of windings with an inverter having a plurality of switches coupled to a voltage source are provided. A first plurality of switching vectors is applied to the plurality of switches. The first plurality of switching vectors includes a first ratio of first magnitude switching vectors to second magnitude switching vectors. A direct current (DC) current associated with the voltage source is monitored during the applying of the first plurality of switching vectors to the plurality of switches. A second ratio of the first magnitude switching vectors to the second magnitude switching vectors is selected based on the monitoring of the DC current associated with the voltage source. A second plurality of switching vectors is applied to the plurality of switches. The second plurality of switching vectors includes the second ratio of the first magnitude switching vectors to the second magnitude switching vectors.

Initial assessment of an airborne Ku-band polarimetric SAR.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raynal, Ann Marie; Doerry, Armin Walter

2013-02-01

Polarimetric synthetic aperture radar (SAR) has been used for a variety of dual-use research applications since the 1940s. By measuring the direction of the electric field vector from radar echoes, polarimetry may enhance an analysts understanding of scattering effects for both earth monitoring and tactical surveillance missions. Polarimetry may provide insight into surface types, materials, or orientations for natural and man-made targets. Polarimetric measurements may also be used to enhance the contrast between scattering surfaces such as man-made objects and their surroundings. This report represents an initial assessment of the utility of, and applications for, polarimetric SAR at Ku-band formore » airborne or unmanned aerial systems.« less

Orientational Order on Surfaces: The Coupling of Topology, Geometry, and Dynamics

NASA Astrophysics Data System (ADS)

Nestler, M.; Nitschke, I.; Praetorius, S.; Voigt, A.

2018-02-01

We consider the numerical investigation of surface bound orientational order using unit tangential vector fields by means of a gradient flow equation of a weak surface Frank-Oseen energy. The energy is composed of intrinsic and extrinsic contributions, as well as a penalization term to enforce the unity of the vector field. Four different numerical discretizations, namely a discrete exterior calculus approach, a method based on vector spherical harmonics, a surface finite element method, and an approach utilizing an implicit surface description, the diffuse interface method, are described and compared with each other for surfaces with Euler characteristic 2. We demonstrate the influence of geometric properties on realizations of the Poincaré-Hopf theorem and show examples where the energy is decreased by introducing additional orientational defects.

Compass cues used by a nocturnal bull ant, Myrmecia midas.

PubMed

Freas, Cody A; Narendra, Ajay; Cheng, Ken

2017-05-01

Ants use both terrestrial landmarks and celestial cues to navigate to and from their nest location. These cues persist even as light levels drop during the twilight/night. Here, we determined the compass cues used by a nocturnal bull ant, Myrmecia midas , in which the majority of individuals begin foraging during the evening twilight period. Myrmecia midas foragers with vectors of ≤5   m when displaced to unfamiliar locations did not follow the home vector, but instead showed random heading directions. Foragers with larger home vectors (≥10   m) oriented towards the fictive nest, indicating a possible increase in cue strength with vector length. When the ants were displaced locally to create a conflict between the home direction indicated by the path integrator and terrestrial landmarks, foragers oriented using landmark information exclusively and ignored any accumulated home vector regardless of vector length. When the visual landmarks at the local displacement site were blocked, foragers were unable to orient to the nest direction and their heading directions were randomly distributed. Myrmecia midas ants typically nest at the base of the tree and some individuals forage on the same tree. Foragers collected on the nest tree during evening twilight were unable to orient towards the nest after small lateral displacements away from the nest. This suggests the possibility of high tree fidelity and an inability to extrapolate landmark compass cues from information collected on the tree and at the nest site to close displacement sites. © 2017. Published by The Company of Biologists Ltd.

Electric and magnetic superlattices in trilayer graphene

NASA Astrophysics Data System (ADS)

Uddin, Salah; Chan, K. S.

2016-01-01

The properties of one dimensional Kronig-Penney type of periodic electric and vector potential on ABC-trilayer graphene superlattices are investigated. The energy spectra obtained with periodic vector potentials shows the emergence of extra Dirac points in the energy spectrum with finite energies. For identical barrier and well widths, the original as well as the extra Dirac points are located in the ky = 0 plane. An asymmetry between the barrier and well widths causes a shift in the extra Dirac points away from the ky = 0 plane. Extra Dirac points having same electron hole crossing energy as that of the original Dirac point as well as finite energy Dirac points are generated in the energy spectrum when periodic electric potential is applied to the system. By applying electric and vector potential together, the symmetry of the energy spectrum about the Fermi level is broken. A tunable band gap is induced in the energy spectrum by applying both electric and vector potential simultaneously with different barrier and well widths.

Simulation of three-phase induction motor drives using indirect field oriented control in PSIM environment

NASA Astrophysics Data System (ADS)

Aziri, Hasif; Patakor, Fizatul Aini; Sulaiman, Marizan; Salleh, Zulhisyam

2017-09-01

This paper presents the simulation of three-phase induction motor drives using Indirect Field Oriented Control (IFOC) in PSIM environment. The asynchronous machine is well known about natural limitations fact of highly nonlinearity and complexity of motor model. In order to resolve these problems, the IFOC is applied to control the instantaneous electrical quantities such as torque and flux component. As FOC is controlling the stator current that represented by a vector, the torque component is aligned with d coordinate while the flux component is aligned with q coordinate. There are five levels of the incremental system are gradually built up to verify and testing the software module in the system. Indeed, all of system build levels are verified and successfully tested in PSIM environment. Moreover, the corresponding system of five build levels are simulated in PSIM environment which is user-friendly for simulation studies in order to explore the performance of speed responses based on IFOC algorithm for three-phase induction motor drives.

Student Understanding of Cross Product Direction and Use of Right-hand Rules: An Exploration of Representation and Context-dependence

NASA Astrophysics Data System (ADS)

Kustusch, Mary Bridget

2011-12-01

Students in introductory physics struggle with vector algebra and with cross product direction in particular. Some have suggested that this may be due to misapplied right-hand rules, but there are few studies that have had the resolution to explore this. Additionally, previous research on student understanding has noted several kinds of representation-dependence of student performance with vector algebra in both physics and non-physics (or math) contexts (e.g. Hawkins et al., 2009; Van Deventer, 2008). Yet with few exceptions (e.g. Scaife and Heckler, 2010), these findings have not been applied to cross product direction questions or the use of right-hand rules. Also, the extensive work in spatial cognition is particularly applicable to cross product direction due to the spatial and kinesthetic nature of the right-hand rule. A synthesis of the literature from these various fields reveals four categories of problem features likely to impact the understanding of cross product direction: (1) the type of reasoning required, (2) the orientation of the vectors, (3) the need for parallel transport, and (4) the physics context and features (or lack thereof). These features formed the basis of the present effort to systematically explore the context-dependence and representation- dependence of student performance on cross product direction questions. This study used a mix of qualitative and quantitative techniques to analyze twenty-seven individual think-aloud interviews. During these interviews, second semester introductory physics students answered 80-100 cross product direction questions in different contexts and with varying problem features. These features were then used as the predictors in regression analyses for correctness and response time. In addition, each problem was coded for the methods used and the errors made to gain a deeper understanding of student behavior and the impact of these features. The results revealed a wide variety of methods (including six different right-hand rules), many different types of errors, and significant context-dependence and representation-dependence for the features mentioned above. Problems that required reasoning backward to find A⃗ (for C⃗=A⃗ xB⃗ ) presented the biggest challenge for students. Participants who recognized the non-commutativity of the cross product would often reverse the order ( B⃗xA⃗ ) on these problems. Also, this error occurred less frequently when a Guess and Check method was used in addition to the right-hand rule. Three different aspects of orientation had a significant impact on performance: (1) the physical discomfort of using a right-hand rule, (2) the plane of the given vectors, and to a lesser extent, (3) the angle between the vectors. One participant was more likely to switch the order of the vectors for the physically awkward orientations than for the physically easy orientations; and there was evidence that some of the difficulty with vector orientations that were not in the xy-plane was due to misinterpretations of the into and out of the page symbols. The impact of both physical discomfort and the plane of the vectors was reduced when participants rotated the paper. Unlike other problem features, the issue of parallel transport did not appear to be nearly as prevalent for cross product direction as it is for vector addition and subtraction. In addition to these findings, this study confirmed earlier findings regarding physics difficulties with magnetic field and magnetic force, such as differences in performance based on the representation of magnetic field (Scaife and Heckler, 2010) and confusion between electric and magnetic fields (Maloney et al., 2001). It also provided evidence of physics difficulties with magnetic field and magnetic force that have been suspected but never explored, specifically the impact of the sign of the charge and the observation location. This study demonstrated that student difficulty with cross product direction is not as simple as misapplied right-hand rules, although this is an issue. Student behavior on cross product direction questions is significantly dependent on both the context of the question and the representation of various problem features. Although more research is necessary, particularly in regard to individual differences, this study represents a significant step forward in our understanding of student difficulties with cross product direction.

Fault tolerant vector control of induction motor drive

NASA Astrophysics Data System (ADS)

Odnokopylov, G.; Bragin, A.

2014-10-01

For electric composed of technical objects hazardous industries, such as nuclear, military, chemical, etc. an urgent task is to increase their resiliency and survivability. The construction principle of vector control system fault-tolerant asynchronous electric. Displaying recovery efficiency three-phase induction motor drive in emergency mode using two-phase vector control system. The process of formation of a simulation model of the asynchronous electric unbalance in emergency mode. When modeling used coordinate transformation, providing emergency operation electric unbalance work. The results of modeling transient phase loss motor stator. During a power failure phase induction motor cannot save circular rotating field in the air gap of the motor and ensure the restoration of its efficiency at rated torque and speed.

Vectors and Rotations in 3-Dimensions: Vector Algebra for the C++ Programmer

DTIC Science & Technology

2016-12-01

Proving Ground, MD 21005-5068 This report describes 2 C++ classes: a Vector class for performing vector algebra in 3-dimensional space ( 3D ) and a Rotation...class for performing rotations of vectors in 3D . Each class is self-contained in a single header file (Vector.h and Rotation.h) so that a C...vector, rotation, 3D , quaternion, C++ tools, rotation sequence, Euler angles, yaw, pitch, roll, orientation 98 Richard Saucier 410-278-6721Unclassified

Agate Beach BOBr Processed Breaking Wave Data

DOE Data Explorer

Adam C Brown

2013-10-31

This data was recorded of the coast of Newport, OR at Agate Beach in the surf zone. The data was recorded by a 9dof inertial measurement unit and consists of a timestamp, quaternion orientation, acceleration vector, rotation vector, and magnetic vector. The acceleration, rotation, and magnetic vectors have all been corrected back to a North East Down reference frame.

Properties of Vector Preisach Models

NASA Technical Reports Server (NTRS)

Kahler, Gary R.; Patel, Umesh D.; Torre, Edward Della

2004-01-01

This paper discusses rotational anisotropy and rotational accommodation of magnetic particle tape. These effects have a performance impact during the reading and writing of the recording process. We introduce the reduced vector model as the basis for the computations. Rotational magnetization models must accurately compute the anisotropic characteristics of ellipsoidally magnetizable media. An ellipticity factor is derived for these media that computes the two-dimensional magnetization trajectory for all applied fields. An orientation correction must be applied to the computed rotational magnetization. For isotropic materials, an orientation correction has been developed and presented. For anisotropic materials, an orientation correction is introduced.

Robust Vision-Based Pose Estimation Algorithm for AN Uav with Known Gravity Vector

NASA Astrophysics Data System (ADS)

Kniaz, V. V.

2016-06-01

Accurate estimation of camera external orientation with respect to a known object is one of the central problems in photogrammetry and computer vision. In recent years this problem is gaining an increasing attention in the field of UAV autonomous flight. Such application requires a real-time performance and robustness of the external orientation estimation algorithm. The accuracy of the solution is strongly dependent on the number of reference points visible on the given image. The problem only has an analytical solution if 3 or more reference points are visible. However, in limited visibility conditions it is often needed to perform external orientation with only 2 visible reference points. In such case the solution could be found if the gravity vector direction in the camera coordinate system is known. A number of algorithms for external orientation estimation for the case of 2 known reference points and a gravity vector were developed to date. Most of these algorithms provide analytical solution in the form of polynomial equation that is subject to large errors in the case of complex reference points configurations. This paper is focused on the development of a new computationally effective and robust algorithm for external orientation based on positions of 2 known reference points and a gravity vector. The algorithm implementation for guidance of a Parrot AR.Drone 2.0 micro-UAV is discussed. The experimental evaluation of the algorithm proved its computational efficiency and robustness against errors in reference points positions and complex configurations.

A Rotation Invariant in 3-D Reaching

ERIC Educational Resources Information Center

Mitra, Suvobrata; Turvey, M. T.

2004-01-01

In 3 experiments, the authors investigated changes in hand orientation during a 3-D reaching task that imposed specific position and orientation requirements on the hand's initial and final postures. Instantaneous hand orientation was described using 3-element rotation vectors representing current orientation as a rotation from a fixed reference…

78 FR 70574 - Grain-Oriented Electrical Steel From China, Czech Republic, Germany, Japan, Korea, Poland, and...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-26

...)] Grain-Oriented Electrical Steel From China, Czech Republic, Germany, Japan, Korea, Poland, and Russia..., Germany, Japan, Korea, Poland, and Russia of grain-oriented electrical steel, provided for in subheadings... Republic, Germany, Japan, Korea, Poland, and Russia. Accordingly, effective September 18, 2013, the...

Optimized Lentiviral Vector Design Improves Titer and Transgene Expression of Vectors Containing the Chicken β-Globin Locus HS4 Insulator Element

PubMed Central

Hanawa, Hideki; Yamamoto, Motoko; Zhao, Huifen; Shimada, Takashi; Persons, Derek A

2009-01-01

Hematopoietic cell gene therapy using retroviral vectors has achieved success in clinical trials. However, safety issues regarding vector insertional mutagenesis have emerged. In two different trials, vector insertion resulted in the transcriptional activation of proto-oncogenes. One strategy for potentially diminishing vector insertional mutagenesis is through the use of self-inactivating lentiviral vectors containing the 1.2-kb insulator element derived from the chicken β-globin locus. However, use of this element can dramatically decrease both vector titer and transgene expression, thereby compromising its practical use. Here, we studied lentiviral vectors containing either the full-length 1.2-kb insulator or the smaller 0.25-kb core element in both orientations in the partially deleted long-terminal repeat. We show that use of the 0.25-kb core insulator rescued vector titer by alleviating a postentry block to reverse transcription associated with the 1.2-kb element. In addition, in an orientation-dependent manner, the 0.25-kb core element significantly increased transgene expression from an internal promoter due to improved transcriptional termination. This element also demonstrated barrier activity, reducing variability of expression due to position effects. As it is known that the 0.25-kb core insulator has enhancer-blocking activity, this particular insulated lentiviral vector design may be useful for clinical application. PMID:19223867

Polarization rotation locking of vector solitons in a fiber ring laser.

PubMed

Zhao, L M; Tang, D Y; Zhang, H; Wu, X

2008-07-07

Polarization rotation of vector solitons in a fiber ring laser was experimentally studied. It was observed that the period of vector soliton polarization rotation could be locked to the cavity roundtrip time or multiple of it. We further show that multiple vector solitons can be formed in a fiber laser, and all the vector solitons have the same group velocity in cavity, however, their instantaneous polarization ellipse orientations could be orthogonal.

Numerical implementation of the S-matrix algorithm for modeling of relief diffraction gratings

NASA Astrophysics Data System (ADS)

Yaremchuk, Iryna; Tamulevičius, Tomas; Fitio, Volodymyr; Gražulevičiūte, Ieva; Bobitski, Yaroslav; Tamulevičius, Sigitas

2013-11-01

A new numerical implementation is developed to calculate the diffraction efficiency of relief diffraction gratings. In the new formulation, vectors containing the expansion coefficients of electric and magnetic fields on boundaries of the grating layer are expressed by additional constants. An S-matrix algorithm has been systematically described in detail and adapted to a simple matrix form. This implementation is suitable for the study of optical characteristics of periodic structures by using modern object-oriented programming languages and different standard mathematical software. The modeling program has been developed on the basis of this numerical implementation and tested by comparison with other commercially available programs and experimental data. Numerical examples are given to show the usefulness of the new implementation.

Longitudinal elliptically polarized electromagnetic waves in off-diagonal magnetoelectric split-ring composites.

PubMed

Chui, S T; Wang, Weihua; Zhou, L; Lin, Z F

2009-07-22

We study the propagation of plane electromagnetic waves through different systems consisting of arrays of split rings of different orientations. Many extraordinary EM phenomena were discovered in such systems, contributed by the off-diagonal magnetoelectric susceptibilities. We find a mode such that the electric field becomes elliptically polarized with a component in the longitudinal direction (i.e. parallel to the wavevector). Even though the group velocity [Formula: see text] and the wavevector k are parallel, in the presence of damping, the Poynting vector does not just get 'broadened', but can possess a component perpendicular to the wavevector. The speed of light can be real even when the product ϵμ is negative. Other novel properties are explored.

ORIENTATION AND LOCUS OF TROPIC PHOTORECEPTOR MOLECULES IN SPORES OF BOTRYTIS AND OSMUNDA

PubMed Central

Jaffe, Lionel; Etzold, Helmut

1962-01-01

Study of the tropic responses of Botrytis cinerea and Osmunda cinnamomea spores to blue light shows the photoreceptor molecules to be highly dichroic and oriented: in Botrytis their axes of maximum absorption lie perpendicular to the nearby cell surface; in Osmunda, parallel. The chief evidence lies in a comparison of their responses to plane polarized light—both germinate parallel to the vibration planes (defined by the axis of vibration of the electric vector and the axis of light propagation)—with those to partial illumination with unpolarized light: Botrytis grows from its brighter part; Osmunda, from its darker. The degree of orientation produced by polarized light corresponds, at high intensities, to that produced by the imposition of such large (about 100 per cent) intensity differences across a cell as to preclude all alternatives to oriented dichroic receptors. The photoreceptors of the Botrytis spore lie within the cell wall's inner half. The chief evidence lies in the component of its tropic responses to polarized light within the vibration plane: germination peaks about 10° off the vibration axis. This deviation arises from focusing which is effective only in the wall's inner half. At high intensities, anomalies appear in Botrytis which are interpreted as "centering," i.e., a tendency toward growth from the center of two or more equally illuminated points of a cell rather than from one of them. PMID:14450869

78 FR 73562 - Non-Oriented Electrical Steel From China, Germany, Japan, Korea, Sweden, and Taiwan; Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-06

... (Preliminary)] Non-Oriented Electrical Steel From China, Germany, Japan, Korea, Sweden, and Taiwan... industry in the United States is materially injured by reason of imports from China, Germany, Japan, Korea... Taiwan and LTFV imports of non-oriented electrical steel from China, Germany, Japan, Korea, Sweden, and...

Testing resonating vector strength: Auditory system, electric fish, and noise

NASA Astrophysics Data System (ADS)

Leo van Hemmen, J.; Longtin, André; Vollmayr, Andreas N.

2011-12-01

Quite often a response to some input with a specific frequency ν○ can be described through a sequence of discrete events. Here, we study the synchrony vector, whose length stands for the vector strength, and in doing so focus on neuronal response in terms of spike times. The latter are supposed to be given by experiment. Instead of singling out the stimulus frequency ν○ we study the synchrony vector as a function of the real frequency variable ν. Its length turns out to be a resonating vector strength in that it shows clear maxima in the neighborhood of ν○ and multiples thereof, hence, allowing an easy way of determining response frequencies. We study this "resonating" vector strength for two concrete but rather different cases, viz., a specific midbrain neuron in the auditory system of cat and a primary detector neuron belonging to the electric sense of the wave-type electric fish Apteronotus leptorhynchus. We show that the resonating vector strength always performs a clear resonance correlated with the phase locking that it quantifies. We analyze the influence of noise and demonstrate how well the resonance associated with maximal vector strength indicates the dominant stimulus frequency. Furthermore, we exhibit how one can obtain a specific phase associated with, for instance, a delay in auditory analysis.

The Weighted Burgers Vector: a new quantity for constraining dislocation densities and types using electron backscatter diffraction on 2D sections through crystalline materials.

PubMed

Wheeler, J; Mariani, E; Piazolo, S; Prior, D J; Trimby, P; Drury, M R

2009-03-01

The Weighted Burgers Vector (WBV) is defined here as the sum, over all types of dislocations, of [(density of intersections of dislocation lines with a map) x (Burgers vector)]. Here we show that it can be calculated, for any crystal system, solely from orientation gradients in a map view, unlike the full dislocation density tensor, which requires gradients in the third dimension. No assumption is made about gradients in the third dimension and they may be non-zero. The only assumption involved is that elastic strains are small so the lattice distortion is entirely due to dislocations. Orientation gradients can be estimated from gridded orientation measurements obtained by EBSD mapping, so the WBV can be calculated as a vector field on an EBSD map. The magnitude of the WBV gives a lower bound on the magnitude of the dislocation density tensor when that magnitude is defined in a coordinate invariant way. The direction of the WBV can constrain the types of Burgers vectors of geometrically necessary dislocations present in the microstructure, most clearly when it is broken down in terms of lattice vectors. The WBV has three advantages over other measures of local lattice distortion: it is a vector and hence carries more information than a scalar quantity, it has an explicit mathematical link to the individual Burgers vectors of dislocations and, since it is derived via tensor calculus, it is not dependent on the map coordinate system. If a sub-grain wall is included in the WBV calculation, the magnitude of the WBV becomes dependent on the step size but its direction still carries information on the Burgers vectors in the wall. The net Burgers vector content of dislocations intersecting an area of a map can be simply calculated by an integration round the edge of that area, a method which is fast and complements point-by-point WBV calculations.

Design and Simulation of Control Technique for Permanent Magnet Synchronous Motor Using Space Vector Pulse Width Modulation

NASA Astrophysics Data System (ADS)

Khan, Mansoor; Yong, Wang; Mustafa, Ehtasham

2017-07-01

After the rapid advancement in the field of power electronics devices and drives for last few decades, there are different kinds of Pulse Width Modulation techniques which have been brought to the market. The applications ranging from industrial appliances to military equipment including the home appliances. The vey common application for the PWM is three phase voltage source inverter, which is used to convert DC to AC in the homes to supply the power to the house in case electricity failure, usually named as Un-interrupted Power Supply. In this paper Space Vector Pulse Width Modulation techniques is discussed and analysed under the control technique named as Field Oriented Control. The working and implementation of this technique has been studied by implementing on the three phase bridge inverter. The technique is used to control the Permanente Magnet Synchronous Motor. The drive system is successfully implemented in MATLAB/Simulink using the mathematical equation and algorithm to achieve the satisfactory results. PI type of controller is used to tuned ers of the motothe parametr i.e. torque and current.

Slicken 1.0: Program for calculating the orientation of shear on reactivated faults

NASA Astrophysics Data System (ADS)

Xu, Hong; Xu, Shunshan; Nieto-Samaniego, Ángel F.; Alaniz-Álvarez, Susana A.

2017-07-01

The slip vector on a fault is an important parameter in the study of the movement history of a fault and its faulting mechanism. Although there exist many graphical programs to represent the shear stress (or slickenline) orientations on faults, programs to quantitatively calculate the orientation of fault slip based on a given stress field are scarce. In consequence, we develop Slicken 1.0, a software to rapidly calculate the orientation of maximum shear stress on any fault plane. For this direct method of calculating the resolved shear stress on a planar surface, the input data are the unit vector normal to the involved plane, the unit vectors of the three principal stress axes, and the stress ratio. The advantage of this program is that the vertical or horizontal principal stresses are not necessarily required. Due to its nimble design using Java SE 8.0, it runs on most operating systems with the corresponding Java VM. The software program will be practical for geoscience students, geologists and engineers and will help resolve a deficiency in field geology, and structural and engineering geology.

Polarization Control of Morphological Pattern Orientation During Light-Mediated Synthesis of Nanostructured Se–Te Films

DOE PAGES

Carim, Azhar I.; Batara, Nicolas A.; Premkumar, Anjali; ...

2015-11-23

The template-free growth of well ordered, highly anisotropic lamellar structures has been demonstrated during the photoelectrodeposition of Se–Te films, wherein the orientation of the pattern can be directed by orienting the linear polarization of the incident light. This control mechanism was investigated further herein by examining the morphologies of films grown photoelectrochemically using light from two simultaneous sources that had mutually different linear polarizations. Photoelectrochemical growth with light from two nonorthogonally polarized same-wavelength sources generated lamellar morphologies in which the long axes of the lamellae were oriented parallel to the intensity-weighted average polarization orientation. Simulations of light scattering at themore » solution–film interface were consistent with this observation. Computer modeling of these growths using combined full-wave electromagnetic and Monte Carlo growth simulations successfully reproduced the experimental morphologies and quantitatively agreed with the pattern orientations observed experimentally by considering only the fundamental light-material interactions during growth. Deposition with light from two orthogonally polarized same-wavelength as well as different-wavelength sources produced structures that consisted of two intersecting sets of orthogonally oriented lamellae in which the relative heights of the two sets could be varied by adjusting the relative source intensities. Simulations of light absorption were performed in analogous, idealized intersecting lamellar structures and revealed that the lamellae preferentially absorbed light polarized with the electric field vector along their long axes. In conclusion, these data sets cumulatively indicate that anisotropic light scattering and light absorption generated by the light polarization produces the anisotropic morphology and that the resultant morphology is a function of all illumination inputs despite differing polarizations.« less

Electronic structure and its external electric field modulation of PbPdO2 ultrathin slabs with (002) and (211) preferred orientations.

PubMed

Yang, Yanmin; Zhong, Kehua; Xu, Guigui; Zhang, Jian-Min; Huang, Zhigao

2017-07-31

The Electronic structure of PbPdO 2 with (002) and (211) preferred orientations were investigated using first-principles calculation. The calculated results indicate that, (002) and (211) orientations exhibit different electric field dependence of band-gap and carrier concentration. The small band gap and more sensitive electric field modulation of band gap were found in (002) orientation. Moreover, the electric field modulation of the resistivity up to 3-4 orders of magnitude is also observed in (002) slab, which reveals that origin of colossal electroresistance. Lastly, electric field modulation of band gap is well explained. This work should be significant for repeating the colossal electroresistance.

Kinematic sensitivity of robot manipulators

NASA Technical Reports Server (NTRS)

Vuskovic, Marko I.

1989-01-01

Kinematic sensitivity vectors and matrices for open-loop, n degrees-of-freedom manipulators are derived. First-order sensitivity vectors are defined as partial derivatives of the manipulator's position and orientation with respect to its geometrical parameters. The four-parameter kinematic model is considered, as well as the five-parameter model in case of nominally parallel joint axes. Sensitivity vectors are expressed in terms of coordinate axes of manipulator frames. Second-order sensitivity vectors, the partial derivatives of first-order sensitivity vectors, are also considered. It is shown that second-order sensitivity vectors can be expressed as vector products of the first-order sensitivity vectors.

Angular momentum evolution in dark matter haloes: a study of the Bolshoi and Millennium simulations

NASA Astrophysics Data System (ADS)

Contreras, S.; Padilla, N.; Lagos, C. D. P.

2017-12-01

We use three different cosmological dark matter simulations to study how the orientation of the angular momentum (AM) vector in dark matter haloes evolve with time. We find that haloes in this kind of simulations are constantly affected by a spurious change of mass, which translates into an artificial change in the orientation of the AM. After removing the haloes affected by artificial mass change, we found that the change in the orientation of the AM vector is correlated with time. The change in its angle and direction (i.e. the angle subtended by the AM vector in two consecutive time-steps) that affect the AM vector has a dependence on the change of mass that affects a halo, the time elapsed in which the change of mass occurs and the halo mass. We create a Monte Carlo simulation that reproduces the change of angle and direction of the AM vector. We reproduce the angular separation of the AM vector since a lookback time of 8.5 Gyr to today (α) with an accuracy of approximately 0.05 in cos(α). We are releasing this Monte Carlo simulation together with this publication. We also create a Monte Carlo simulation that reproduces the change of the AM modulus. We find that haloes in denser environments display the most dramatic evolution in their AM direction, as well as haloes with a lower specific AM modulus. These relations could be used to improve the way we follow the AM vector in low-resolution simulations.

Creating orbiting vorticity vectors in magnetic particle suspensions through field symmetry transitions–a route to multi-axis mixing

DOE PAGES

Martin, James E.; Solis, Kyle Jameson

2015-11-09

It has recently been reported that two types of triaxial electric or magnetic fields can drive vorticity in dielectric or magnetic particle suspensions, respectively. The first type-symmetry -- breaking rational fields -- consists of three mutually orthogonal fields, two alternating and one dc, and the second type -- rational triads -- consists of three mutually orthogonal alternating fields. In each case it can be shown through experiment and theory that the fluid vorticity vector is parallel to one of the three field components. For any given set of field frequencies this axis is invariant, but the sign and magnitude ofmore » the vorticity (at constant field strength) can be controlled by the phase angles of the alternating components and, at least for some symmetry-breaking rational fields, the direction of the dc field. In short, the locus of possible vorticity vectors is a 1-d set that is symmetric about zero and is along a field direction. In this paper we show that continuous, 3-d control of the vorticity vector is possible by progressively transitioning the field symmetry by applying a dc bias along one of the principal axes. Such biased rational triads are a combination of symmetry-breaking rational fields and rational triads. A surprising aspect of these transitions is that the locus of possible vorticity vectors for any given field bias is extremely complex, encompassing all three spatial dimensions. As a result, the evolution of a vorticity vector as the dc bias is increased is complex, with large components occurring along unexpected directions. More remarkable are the elaborate vorticity vector orbits that occur when one or more of the field frequencies are detuned. As a result, these orbits provide the basis for highly effective mixing strategies wherein the vorticity axis periodically explores a range of orientations and magnitudes.« less

Developmental Testing of Electric Thrust Vector Control Systems for Manned Launch Vehicle Applications

NASA Technical Reports Server (NTRS)

Bates, Lisa B.; Young, David T.

2012-01-01

This paper describes recent developmental testing to verify the integration of a developmental electromechanical actuator (EMA) with high rate lithium ion batteries and a cross platform extensible controller. Testing was performed at the Thrust Vector Control Research, Development and Qualification Laboratory at the NASA George C. Marshall Space Flight Center. Electric Thrust Vector Control (ETVC) systems like the EMA may significantly reduce recurring launch costs and complexity compared to heritage systems. Electric actuator mechanisms and control requirements across dissimilar platforms are also discussed with a focus on the similarities leveraged and differences overcome by the cross platform extensible common controller architecture.

Optimal orientation in flows: providing a benchmark for animal movement strategies.

PubMed

McLaren, James D; Shamoun-Baranes, Judy; Dokter, Adriaan M; Klaassen, Raymond H G; Bouten, Willem

2014-10-06

Animal movements in air and water can be strongly affected by experienced flow. While various flow-orientation strategies have been proposed and observed, their performance in variable flow conditions remains unclear. We apply control theory to establish a benchmark for time-minimizing (optimal) orientation. We then define optimal orientation for movement in steady flow patterns and, using dynamic wind data, for short-distance mass movements of thrushes (Turdus sp.) and 6000 km non-stop migratory flights by great snipes, Gallinago media. Relative to the optimal benchmark, we assess the efficiency (travel speed) and reliability (success rate) of three generic orientation strategies: full compensation for lateral drift, vector orientation (single-heading movement) and goal orientation (continually heading towards the goal). Optimal orientation is characterized by detours to regions of high flow support, especially when flow speeds approach and exceed the animal's self-propelled speed. In strong predictable flow (short distance thrush flights), vector orientation adjusted to flow on departure is nearly optimal, whereas for unpredictable flow (inter-continental snipe flights), only goal orientation was near-optimally reliable and efficient. Optimal orientation provides a benchmark for assessing efficiency of responses to complex flow conditions, thereby offering insight into adaptive flow-orientation across taxa in the light of flow strength, predictability and navigation capacity.

Optimal orientation in flows: providing a benchmark for animal movement strategies

PubMed Central

McLaren, James D.; Shamoun-Baranes, Judy; Dokter, Adriaan M.; Klaassen, Raymond H. G.; Bouten, Willem

2014-01-01

Animal movements in air and water can be strongly affected by experienced flow. While various flow-orientation strategies have been proposed and observed, their performance in variable flow conditions remains unclear. We apply control theory to establish a benchmark for time-minimizing (optimal) orientation. We then define optimal orientation for movement in steady flow patterns and, using dynamic wind data, for short-distance mass movements of thrushes (Turdus sp.) and 6000 km non-stop migratory flights by great snipes, Gallinago media. Relative to the optimal benchmark, we assess the efficiency (travel speed) and reliability (success rate) of three generic orientation strategies: full compensation for lateral drift, vector orientation (single-heading movement) and goal orientation (continually heading towards the goal). Optimal orientation is characterized by detours to regions of high flow support, especially when flow speeds approach and exceed the animal's self-propelled speed. In strong predictable flow (short distance thrush flights), vector orientation adjusted to flow on departure is nearly optimal, whereas for unpredictable flow (inter-continental snipe flights), only goal orientation was near-optimally reliable and efficient. Optimal orientation provides a benchmark for assessing efficiency of responses to complex flow conditions, thereby offering insight into adaptive flow-orientation across taxa in the light of flow strength, predictability and navigation capacity. PMID:25056213

Plasma-electric field controlled growth of oriented graphene for energy storage applications

NASA Astrophysics Data System (ADS)

Ghosh, Subrata; Polaki, S. R.; Kamruddin, M.; Jeong, Sang Mun; (Ken Ostrikov, Kostya

2018-04-01

It is well known that graphene grows as flat sheets aligned with the growth substrate. Oriented graphene structures typically normal to the substrate have recently attracted major attention. Most often, the normal orientation is achieved in a plasma-assisted growth and is believed to be due to the plasma-induced in-built electric field, which is usually oriented normal to the substrate. This work focuses on the effect of an in-built electric field on the growth direction, morphology, interconnectedness, structural properties and also the supercapacitor performance of various configurations of graphene structures and reveals the unique dependence of these features on the electric field orientation. It is shown that tilting of growth substrates from parallel to the normal direction with respect to the direction of in-built plasma electric field leads to the morphological transitions from horizontal graphene layers, to oriented individual graphene sheets and then interconnected 3D networks of oriented graphene sheets. The revealed transition of the growth orientation leads to a change in structural properties, wetting nature, types of defect in graphitic structures and also affects their charge storage capacity when used as supercapacitor electrodes. This simple and versatile approach opens new opportunities for the production of potentially large batches of differently oriented and structured graphene sheets in one production run.

Polarization ellipse and Stokes parameters in geometric algebra.

PubMed

Santos, Adler G; Sugon, Quirino M; McNamara, Daniel J

2012-01-01

In this paper, we use geometric algebra to describe the polarization ellipse and Stokes parameters. We show that a solution to Maxwell's equation is a product of a complex basis vector in Jackson and a linear combination of plane wave functions. We convert both the amplitudes and the wave function arguments from complex scalars to complex vectors. This conversion allows us to separate the electric field vector and the imaginary magnetic field vector, because exponentials of imaginary scalars convert vectors to imaginary vectors and vice versa, while exponentials of imaginary vectors only rotate the vector or imaginary vector they are multiplied to. We convert this expression for polarized light into two other representations: the Cartesian representation and the rotated ellipse representation. We compute the conversion relations among the representation parameters and their corresponding Stokes parameters. And finally, we propose a set of geometric relations between the electric and magnetic fields that satisfy an equation similar to the Poincaré sphere equation.

Low-Angle Radar Tracking

DTIC Science & Technology

1976-02-01

Transition from Specular Reflection to Diffuse Scattering. . . 10 Composition of the Electric-Field Vector as Seen at the Radar...r t (16) R • FIGURE P COMPOSITION OF THE ELECTRIC-FIELD VECTOR AS SEEN AT THE RADAR, R, IN FIG. 2. The electric field at the radar, E, is the sum...wavelengths in the VHP and UHF ranges even subsurface characteristics can be important. So in a field experiment one must be careful to measure

Electric fields and vector potentials of thin cylindrical antennas

NASA Astrophysics Data System (ADS)

King, Ronold W. P.

1990-09-01

The vector potential and electric field generated by the current in a center-driven or parasitic dipole antenna that extends from z = -h to z = h are investigated for each of the several components of the current. These include sin k(h - absolute value of z), sin k (absolute value of z) - sin kh, cos kz - cos kh, and cos kz/2 - cos kh/2. Of special interest are the interactions among the variously spaced elements in parallel nonstaggered arrays. These depend on the mutual vector potentials. It is shown that at a radial distance rho approximately = h and in the range z = -h to h, the vector potentials due to all four components become alike and have an approximately plane-wave form. Simple approximate formulas for the electric fields and vector potentials generated by each of the four distributions are derived and compared with the exact results. The application of the new formulas to large arrays is discussed.

MHD thrust vectoring of a rocket engine

NASA Astrophysics Data System (ADS)

Labaune, Julien; Packan, Denis; Tholin, Fabien; Chemartin, Laurent; Stillace, Thierry; Masson, Frederic

2016-09-01

In this work, the possibility to use MagnetoHydroDynamics (MHD) to vectorize the thrust of a solid propellant rocket engine exhaust is investigated. Using a magnetic field for vectoring offers a mass gain and a reusability advantage compared to standard gimbaled, elastomer-joint systems. Analytical and numerical models were used to evaluate the flow deviation with a 1 Tesla magnetic field inside the nozzle. The fluid flow in the resistive MHD approximation is calculated using the KRONOS code from ONERA, coupling the hypersonic CFD platform CEDRE and the electrical code SATURNE from EDF. A critical parameter of these simulations is the electrical conductivity, which was evaluated using a set of equilibrium calculations with 25 species. Two models were used: local thermodynamic equilibrium and frozen flow. In both cases, chlorine captures a large fraction of free electrons, limiting the electrical conductivity to a value inadequate for thrust vectoring applications. However, when using chlorine-free propergols with 1% in mass of alkali, an MHD thrust vectoring of several degrees was obtained.

Theoretical investigation of confocal microscopy using an elliptically polarized cylindrical vector laser beam: Visualization of quantum emitters near interfaces

NASA Astrophysics Data System (ADS)

Boichenko, Stepan

2018-04-01

We theoretically study laser-scanning confocal fluorescence microscopy using elliptically polarized cylindrical vector excitation light as a tool for visualization of arbitrarily oriented single quantum dipole emitters located (1) near planar surfaces enhancing fluorescence, (2) in a thin supported polymer film, (3) in a freestanding polymer film, and (4) in a dielectric planar microcavity. It is shown analytically that by using a tightly focused azimuthally polarized beam, it is possible to exclude completely the orientational dependence of the image intensity maximum of a quantum emitter that absorbs light as a pair of incoherent independent linear dipoles. For linear dipole quantum emitters, the orientational independence degree higher than 0.9 can normally be achieved (this quantity equal to 1 corresponds to completely excluded orientational dependence) if the collection efficiency of the microscope objective and the emitter's total quantum yield are not strongly orientationally dependent. Thus, the visualization of arbitrarily oriented single quantum emitters by means of the studied technique can be performed quite efficiently.

The Vector Electric Field Instrument on the C/NOFS Satellite

NASA Technical Reports Server (NTRS)

Pfaff, R.; Kujawski, J.; Uribe, P.; Bromund, K.; Fourre, R.; Acuna, M.; Le, G.; Farrell, W.; Holzworth, R.; McCarthy, M.;

Vector magnetic field and vector current density in and around the δ-spot NOAA 10808†

NASA Astrophysics Data System (ADS)

Bommier, Véronique; Landi Degl'Innocenti, Egidio; Schmieder, Brigitte; Gelly, Bernard

2011-08-01

The context is that of the so-called ``fundamental ambiguity'' (also azimuth ambiguity, or 180° ambiguity) in magnetic field vector measurements: two field vectors symmetrical with respect to the line-of-sight have the same polarimetric signature, so that they cannot be discriminated. We propose a method to solve this ambiguity by applying the ``simulated annealing'' algorithm to the minimization of the field divergence, added to the longitudinal current absolute value, the line-of-sight derivative of the magnetic field being inferred by the interpretation of the Zeeman effect observed by spectropolarimetry in two lines formed at different depths. We find that the line pair Fe I λ 6301.5 and Fe I λ 6302.5 is appropriate for this purpose. We treat the example case of the δ-spot of NOAA 10808 observed on 13 September 2005 between 14:25 and 15:25 UT with the THEMIS telescope. Besides the magnetic field resolved map, the electric current density vector map is also obtained. A strong horizontal current density flow is found surrounding each spot inside its penumbra, associated to a non-zero Lorentz force centripetal with respect to the spot center (i.e., oriented towards the spot center). The current wrapping direction is found to depend on the spot polarity: clockwise for the positive polarity, counterclockwise for the negative one. This analysis is made possible thanks to the UNNOFIT2 Milne-Eddington inversion code, where the usual theory is generalized to the case of a line (Fe I λ 6301.5) that is not a normal Zeeman triplet line (like Fe I λ 6302.5).

Regulation of adipose-tissue-derived stromal cell orientation and motility in 2D- and 3D-cultures by direct-current electrical field.

PubMed

Yang, Gang; Long, Haiyan; Ren, Xiaomei; Ma, Kunlong; Xiao, Zhenghua; Wang, Ying; Guo, Yingqiang

2017-02-01

Cell alignment and motility play a critical role in a variety of cell behaviors, including cytoskeleton reorganization, membrane-protein relocation, nuclear gene expression, and extracellular matrix remodeling. Direct current electric field (EF) in vitro can direct many types of cells to align vertically to EF vector. In this work, we investigated the effects of EF stimulation on rat adipose-tissue-derived stromal cells (ADSCs) in 2D-culture on plastic culture dishes and in 3D-culture on various scaffold materials, including collagen hydrogels, chitosan hydrogels and poly(L-lactic acid)/gelatin electrospinning fibers. Rat ADSCs were exposed to various physiological-strength EFs in a homemade EF-bioreactor. Changes of morphology and movements of cells affected by applied EFs were evaluated by time-lapse microphotography, and cell survival rates and intracellular calcium oscillations were also detected. Results showed that EF facilitated ADSC morphological changes, under 6 V/cm EF strength, and that ADSCs in 2D-culture aligned vertically to EF vector and kept a good cell survival rate. In 3D-culture, cell galvanotaxis responses were subject to the synergistic effect of applied EF and scaffold materials. Fast cell movement and intracellular calcium activities were observed in the cells of 3D-culture. We believe our research will provide some experimental references for the future study in cell galvanotaxis behaviors. © 2017 Japanese Society of Developmental Biologists.

Theoretical study of spin Hall effect in conjugated Organic semiconductors

NASA Astrophysics Data System (ADS)

Mahani, M. R.; Delin, A.

The spin Hall effect (SHE), a direct conversion between electronic and spin currents, is a rapidly growing branch of spintronics. The study of SHE in conjugated polymers has gained momentum recently due to the weak spin-orbit couplings and hyperfine interactions in these materials. Our calculations of SHE based on the recent work, are the result of the misalignment of pi-orbitals in triads consisting of three molecules. In disordered organics, where the electronic conduction is through hopping of the electrons among randomly oriented molecules, instead of identifying a hopping triad to represent the entire system, we numerically solve the master equations for electrical and spin hall conductivities by summing the contributions from all triads in a sufficiently large system. The interference between the direct and indirect hoppings in these triads leads to SHE proportional to the orientation vector of molecule at the first order of spin-orbit coupling. Hence, our results show, the degree of molecular alignment as well as the strength of the spin-orbit coupling can be used to control the SHE in organics.

Navigational potential of e-vector sensing by marine animals

NASA Astrophysics Data System (ADS)

Waterman, Talbot H.

1993-02-01

This essay documents an informal talk about the central theme in the author's research career. That has mainly related to the visual physiology and orientation of aquatic animals, particularly with regard to underwater polarized light. This required pioneer measurements of underwater polarized light patterns, proof that oriented behavior could be determined by e- vector direction independently of intensity patterns or other secondary clues and a demonstration of the retinal dichroic mechanism involved, at least in crustacean compound eyes. The relevant visual data processing by two orthogonal channels was also analyzed with regard to oriented swimming behavior. Some current research by others and major unsolved problems are mentioned and the relevant part of the author's bibliography is appended.

Metastable Bound States of Two-Dimensional Magnetoexcitons in the Lowest Landau Levels Approximation

NASA Astrophysics Data System (ADS)

Moskalenko, S. A.; Khadzhi, P. I.; Podlesny, I. V.; Dumanov, E. V.; Liberman, M. A.; Zubac, I. A.

2017-12-01

The possible existence of the two-dimensional bimagnetoexcitons and metastable bound states formed by two magnetoexcitons with opposite in-plane wave vectors k and -k has been studied. Magnetoexcitons taking part in the formation of molecules look as two electric dipoles with the arms oriented in-plane perpendicular to the respective wave vectors and with the length of the arms d=k(l_0)^2, where l_0 is the magnetic length. Two antiparallel dipoles moving with equal, yet antiparallel, wave vectors have the possibility of moving with equal probability in any direction of the plane, which is determined by the trial wave function of relative motion φ_n(|k|), depending on modulus k. The magnetoexcitons are composed of electrons and holes situated on the lowest Landau levels with the cyclotron energies greater than the binding energy of the 2D Wannier-Mott exciton. The description has been made in Landau gauge. The spin states of two electrons have been chosen in the form of antisymmetric or symmetric combinations with parameter η=+/-1. The effective spins of two heavy holes have been combined in the same resultant spinor states as the spin of the electrons. Because the projections of the both spinor states with η=+/-1 are equal to zero, the influence of the Zeeman splitting effect vanishes. In the case of trial wave function, the maximal density of the magnetoexcitons in the momentum space is concentrated on the in-plane ring. In the approximation of the lowest Landau levels, when the influence of the excited Landau levels is neglected, stable bound states of bimagnetoexcitons do not exist for both spin orientations. Instead, in the case of α=0.5 and η=1, a deep metastable bound state with the activation barrier comparable with two magnetoexciton ionization potentials 2I_l has been revealed. In the case of η=-1 and α=3.4, only a shallow metastable bound state can appear.

A parametric study of the behavior of the angular momentum vector during spin rate changes of rigid body spacecraft

NASA Technical Reports Server (NTRS)

Longuski, J. M.

1982-01-01

During a spin-up or spin-down maneuver of a spinning spacecraft, it is usual to have not only a constant body-fixed torque about the desired spin axis, but also small undesired constant torques about the transverse axes. This causes the orientation of the angular momentum vector to change in inertial space. Since an analytic solution is available for the angular momentum vector as a function of time, this behavior can be studied for large variations of the dynamic parameters, such as the initial spin rate, the inertial properties and the torques. As an example, the spin-up and spin-down maneuvers of the Galileo spacecraft was studied and as a result, very simple heuristic solutions were discovered which provide very good approximations to the parametric behavior of the angular momentum vector orientation.

Controlling Growth Orientation of Phthalocyanine Films by Electrical Fields

NASA Technical Reports Server (NTRS)

Zhu, S.; Banks, C. E.; Frazier, D. O.; Ila, D.; Muntele, I.; Penn, B. G.; Sharma, A.; Rose, M. Franklin (Technical Monitor)

2001-01-01

Organic Phthalocyanine films have many applications ranging from data storage to various non-linear optical devices whose quality is affected by the growth orientation of Phthalocyanine films. Due to the structural and electrical properties of Phthalocyanine molecules, the film growth orientation depends strongly on the substrate surface states. In this presentation, an electrical field up to 4000 V/cm is introduced during film growth. The Phthalocyanine films are synthesized on quartz substrates using thermal evaporation. An intermediate layer is deposited on some substrates for introducing the electrical field. Scanning electron microscopy, x-ray diffraction, and Fourier transform infrared spectroscopy are used for measuring surface morphology, film structure, and optical properties, respectively. The comparison of Phthalocyanine films grown with and without the electrical field reveals different morphology, film density, and growth orientation, which eventually change optical properties of these films. These results suggest that the growth method in the electrical field can be used to synthesized Phthalocyanine films with a preferred crystal orientation as well as propose an interaction mechanism between the substrate surface and the depositing molecules. The details of growth conditions and of the growth model of how the Phthalocyanine molecules grow in the electrical field will be discussed.

Orientation selective deep brain stimulation

NASA Astrophysics Data System (ADS)

Lehto, Lauri J.; Slopsema, Julia P.; Johnson, Matthew D.; Shatillo, Artem; Teplitzky, Benjamin A.; Utecht, Lynn; Adriany, Gregor; Mangia, Silvia; Sierra, Alejandra; Low, Walter C.; Gröhn, Olli; Michaeli, Shalom

2017-02-01

Objective. Target selectivity of deep brain stimulation (DBS) therapy is critical, as the precise locus and pattern of the stimulation dictates the degree to which desired treatment responses are achieved and adverse side effects are avoided. There is a clear clinical need to improve DBS technology beyond currently available stimulation steering and shaping approaches. We introduce orientation selective neural stimulation as a concept to increase the specificity of target selection in DBS. Approach. This concept, which involves orienting the electric field along an axonal pathway, was tested in the corpus callosum of the rat brain by freely controlling the direction of the electric field on a plane using a three-electrode bundle, and monitoring the response of the neurons using functional magnetic resonance imaging (fMRI). Computational models were developed to further analyze axonal excitability for varied electric field orientation. Main results. Our results demonstrated that the strongest fMRI response was observed when the electric field was oriented parallel to the axons, while almost no response was detected with the perpendicular orientation of the electric field relative to the primary fiber tract. These results were confirmed by computational models of the experimental paradigm quantifying the activation of radially distributed axons while varying the primary direction of the electric field. Significance. The described strategies identify a new course for selective neuromodulation paradigms in DBS based on axonal fiber orientation.

Vector tomography for reconstructing electric fields with non-zero divergence in bounded domains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koulouri, Alexandra, E-mail: koulouri@uni-muenster.de; Department of Electrical and Electronic Engineering, Imperial College London, Exhibition Road, London SW7 2BT; Brookes, Mike

In vector tomography (VT), the aim is to reconstruct an unknown multi-dimensional vector field using line integral data. In the case of a 2-dimensional VT, two types of line integral data are usually required. These data correspond to integration of the parallel and perpendicular projection of the vector field along the integration lines and are called the longitudinal and transverse measurements, respectively. In most cases, however, the transverse measurements cannot be physically acquired. Therefore, the VT methods are typically used to reconstruct divergence-free (or source-free) velocity and flow fields that can be reconstructed solely from the longitudinal measurements. In thismore » paper, we show how vector fields with non-zero divergence in a bounded domain can also be reconstructed from the longitudinal measurements without the need of explicitly evaluating the transverse measurements. To the best of our knowledge, VT has not previously been used for this purpose. In particular, we study low-frequency, time-harmonic electric fields generated by dipole sources in convex bounded domains which arise, for example, in electroencephalography (EEG) source imaging. We explain in detail the theoretical background, the derivation of the electric field inverse problem and the numerical approximation of the line integrals. We show that fields with non-zero divergence can be reconstructed from the longitudinal measurements with the help of two sparsity constraints that are constructed from the transverse measurements and the vector Laplace operator. As a comparison to EEG source imaging, we note that VT does not require mathematical modeling of the sources. By numerical simulations, we show that the pattern of the electric field can be correctly estimated using VT and the location of the source activity can be determined accurately from the reconstructed magnitudes of the field. - Highlights: • Vector tomography is used to reconstruct electric fields generated by dipole sources. • Inverse solutions are based on longitudinal and transverse line integral measurements. • Transverse line integral measurements are used as a sparsity constraint. • Numerical procedure to approximate the line integrals is described in detail. • Patterns of the studied electric fields are correctly estimated.« less

Effects of coil orientation on the electric field induced by TMS over the hand motor area

NASA Astrophysics Data System (ADS)

Laakso, Ilkka; Hirata, Akimasa; Ugawa, Yoshikazu

2014-01-01

Responses elicited by transcranial magnetic stimulation (TMS) over the hand motor area depend on the position and orientation of the stimulating coil. In this work, we computationally investigate the induced electric field for multiple coil orientations and locations in order to determine which parts of the brain are affected and how the sensitivity of motor cortical activation depends on the direction of the electric field. The finite element method is used for calculating the electric field induced by TMS in two individual anatomical models of the head and brain. The orientation of the coil affects both the strength and depth of penetration of the electric field, and the field strongly depends on the direction of the sulcus, where the target neurons are located. The coil position that gives the strongest electric field in the target cortical region may deviate from the closest scalp location by a distance on the order of 1 cm. Together with previous experimental data, the results support the hypothesis that the cortex is most sensitive to fields oriented perpendicular to the cortical layers, while it is relatively insensitive to fields parallel to them. This has important implications for targeting of TMS. To determine the most effective coil position and orientation, it is essential to consider both biological (the direction of the targeted axons) and physical factors (the strength and direction of the electric field).

The lizard celestial compass detects linearly polarized light in the blue.

PubMed

Beltrami, Giulia; Parretta, Antonio; Petrucci, Ferruccio; Buttini, Paola; Bertolucci, Cristiano; Foà, Augusto

2012-09-15

The present study first examined whether ruin lizards, Podarcis sicula, are able to orientate using plane-polarized light produced by an LCD screen. Ruin lizards were trained and tested indoors, inside a hexagonal Morris water maze positioned under an LCD screen producing white polarized light with a single E-vector, which provided an axial cue. White polarized light did not include wavelengths in the UV. Lizards orientated correctly either when tested with E-vector parallel to the training axis or after 90 deg rotation of the E-vector direction, thus validating the apparatus. Further experiments examined whether there is a preferential region of the light spectrum to perceive the E-vector direction of polarized light. For this purpose, lizards reaching learning criteria under white polarized light were subdivided into four experimental groups. Each group was tested for orientation under a different spectrum of plane-polarized light (red, green, cyan and blue) with equalized photon flux density. Lizards tested under blue polarized light orientated correctly, whereas lizards tested under red polarized light were completely disoriented. Green polarized light was barely discernible by lizards, and thus insufficient for a correct functioning of their compass. When exposed to cyan polarized light, lizard orientation performances were optimal, indistinguishable from lizards detecting blue polarized light. Overall, the present results demonstrate that perception of linear polarization in the blue is necessary - and sufficient - for a proper functioning of the sky polarization compass of ruin lizards. This may be adaptively important, as detection of polarized light in the blue improves functioning of the polarization compass under cloudy skies, i.e. when the alternative celestial compass based on detection of the sun disk is rendered useless because the sun is obscured by clouds.

New method for solving inductive electric fields in the non-uniformly conducting ionosphere

NASA Astrophysics Data System (ADS)

Vanhamäki, H.; Amm, O.; Viljanen, A.

2006-10-01

We present a new calculation method for solving inductive electric fields in the ionosphere. The time series of the potential part of the ionospheric electric field, together with the Hall and Pedersen conductances serves as the input to this method. The output is the time series of the induced rotational part of the ionospheric electric field. The calculation method works in the time-domain and can be used with non-uniform, time-dependent conductances. In addition, no particular symmetry requirements are imposed on the input potential electric field. The presented method makes use of special non-local vector basis functions called the Cartesian Elementary Current Systems (CECS). This vector basis offers a convenient way of representing curl-free and divergence-free parts of 2-dimensional vector fields and makes it possible to solve the induction problem using simple linear algebra. The new calculation method is validated by comparing it with previously published results for Alfvén wave reflection from a uniformly conducting ionosphere.

Software and hardware complex for research and management of the separation process

NASA Astrophysics Data System (ADS)

Borisov, A. P.

2018-01-01

The article is devoted to the development of a program for studying the operation of an asynchronous electric drive using vector-algorithmic switching of windings, as well as the development of a hardware-software complex for controlling parameters and controlling the speed of rotation of an asynchronous electric drive for investigating the operation of a cyclone. To study the operation of an asynchronous electric drive, a method was used in which the average value of flux linkage is found and a method for vector-algorithmic calculation of the power and electromagnetic moment of an asynchronous electric drive feeding from a single-phase network is developed, with vector-algorithmic commutation, and software for calculating parameters. The software part of the complex allows to regulate the speed of rotation of the motor by vector-algorithmic switching of transistors or, using pulse-width modulation (PWM), set any engine speed. Also sensors are connected to the hardware-software complex at the inlet and outlet of the cyclone. The developed cyclone with an inserted complex allows to receive high efficiency of product separation at various entrance speeds. At an inlet air speed of 18 m / s, the cyclone’s maximum efficiency is achieved. For this, it is necessary to provide the rotational speed of an asynchronous electric drive with a frequency of 45 Hz.

Optimum instantaneous impulsive orbital injection to attain a specified asymptotic velocity vector.

NASA Technical Reports Server (NTRS)

Bean, W. C.

1971-01-01

A nalysis of the necessary conditions of Battin for instantaneous orbital injection, with consideration of the uniqueness of his solution, and of the further problem which arises in the degenerate case when radius vector and asymptotic vector are separated by 180 deg. It is shown that when the angular separation between radius vector and asymptotic velocity vector satisfies theta not equal to 180 deg, there are precisely two insertion-velocity vectors which permit attainment of the target asymptotic velocity vector, one yielding posigrade, the other retrograde motion. When theta equals to 180 deg, there is a family of insertion-velocity vectors which permit attainment of a specified asymptotic velocity vector with a unique insertion-velocity vector for every arbitrary orientation of a target unit angular momentum vector.

A sensor for vector electric field measurements through a nonlinear anisotropic optical crystal

NASA Astrophysics Data System (ADS)

Barbieri, Luca; Gondola, Marco; Potenza, Marco; Villa, Andrea; Malgesini, Roberto

2017-11-01

Electrical applications require the development of electric field sensors that can reproduce vector electric field waveforms with a very large spectral width ranging from 50 Hz to at least 70 MHz. This makes it possible to measure both the normal operation modes of electrical components and abnormal behaviors such as the corona emission and partial discharges. In this work, we aim to develop a fully dielectric sensor capable of measuring two components of the electric field using a wide class of optical crystals including anisotropic ones, whereas most of the efforts in this field have been devoted to isotropic crystals. We report the results of the measurements performed at 50 Hz and with a lightning impulse, to validate the sensor.

A combined vector potential-scalar potential method for FE computation of 3D magnetic fields in electrical devices with iron cores

NASA Technical Reports Server (NTRS)

Wang, R.; Demerdash, N. A.

1991-01-01

A method of combined use of magnetic vector potential based finite-element (FE) formulations and magnetic scalar potential (MSP) based formulations for computation of three-dimensional magnetostatic fields is introduced. In this method, the curl-component of the magnetic field intensity is computed by a reduced magnetic vector potential. This field intensity forms the basic of a forcing function for a global magnetic scalar potential solution over the entire volume of the region. This method allows one to include iron portions sandwiched in between conductors within partitioned current-carrying subregions. The method is most suited for large-scale global-type 3-D magnetostatic field computations in electrical devices, and in particular rotating electric machinery.

Huygens' optical vector wave field synthesis via in-plane electric dipole metasurface.

PubMed

Park, Hyeonsoo; Yun, Hansik; Choi, Chulsoo; Hong, Jongwoo; Kim, Hwi; Lee, Byoungho

2018-04-16

We investigate Huygens' optical vector wave field synthesis scheme for electric dipole metasurfaces with the capability of modulating in-plane polarization and complex amplitude and discuss the practical issues involved in realizing multi-modulation metasurfaces. The proposed Huygens' vector wave field synthesis scheme identifies the vector Airy disk as a synthetic unit element and creates a designed vector optical field by integrating polarization-controlled and complex-modulated Airy disks. The metasurface structure for the proposed vector field synthesis is analyzed in terms of the signal-to-noise ratio of the synthesized field distribution. The design of practical metasurface structures with true vector modulation capability is possible through the analysis of the light field modulation characteristics of various complex modulated geometric phase metasurfaces. It is shown that the regularization of meta-atoms is a key factor that needs to be considered in field synthesis, given that it is essential for a wide range of optical field synthetic applications, including holographic displays, microscopy, and optical lithography.

Professor Herman Burger (1893-1965), eminent teacher and scientist, who laid the theoretical foundations of vectorcardiography--and electrocardiography.

PubMed

van Herpen, Gerard

2014-01-01

Einthoven not only designed a high quality instrument, the string galvanometer, for recording the ECG, he also shaped the conceptual framework to understand it. He reduced the body to an equilateral triangle and the cardiac electric activity to a dipole, represented by an arrow (i.e. a vector) in the triangle's center. Up to the present day the interpretation of the ECG is based on the model of a dipole vector being projected on the various leads. The model is practical but intuitive, not physically founded. Burger analysed the relation between heart vector and leads according to the principles of physics. It then follows that an ECG lead must be treated as a vector (lead vector) and that the lead voltage is not simply proportional to the projection of the vector on the lead, but must be multiplied by the value (length) of the lead vector, the lead strength. Anatomical lead axis and electrical lead axis are different entities and the anatomical body space must be distinguished from electrical space. Appreciation of these underlying physical principles should contribute to a better understanding of the ECG. The development of these principles by Burger is described, together with some personal notes and a sketch of the personality of this pioneer of medical physics. Copyright © 2014. Published by Elsevier Inc.

Anisotropy model for modern grain oriented electrical steel based on orientation distribution function

NASA Astrophysics Data System (ADS)

Jiang, Fan; Rossi, Mathieu; Parent, Guillaume

2018-05-01

Accurately modeling the anisotropic behavior of electrical steel is mandatory in order to perform good end simulations. Several approaches can be found in the literature for that purpose but the more often those methods are not able to deal with grain oriented electrical steel. In this paper, a method based on orientation distribution function is applied to modern grain oriented laminations. In particular, two solutions are proposed in order to increase the results accuracy. The first one consists in increasing the decomposition number of the cosine series on which the method is based. The second one consists in modifying the determination method of the terms belonging to this cosine series.

Electromagnetic fluctuations in magnetized plasmas. I. The rigorous relativistic kinetic theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schlickeiser, R., E-mail: rsch@tp4.rub.de, E-mail: yoonp@umd.edu; Yoon, P. H., E-mail: rsch@tp4.rub.de, E-mail: yoonp@umd.edu; School of Space Research, Kyung Hee University, Yongin-Si, Gyeonggi-Do 446-701

2015-07-15

Using the system of the Klimontovich and Maxwell equations, the general linear fluctuation theory for magnetized plasmas is developed. General expressions for the electromagnetic fluctuation spectra (electric and magnetic fields) from uncorrelated plasma particles in plasmas with a uniform magnetic field are derived, which are covariantly correct within the theory of special relativity. The general fluctuation spectra hold for plasmas of arbitrary composition, arbitrary momentum dependences of the plasma particle distribution functions, and arbitrary orientations of the wave vector with respect to the uniform magnetic field. Moreover, no restrictions on the values of the real and the imaginary parts ofmore » the frequency are made. The derived fluctuation spectra apply to both non-collective fluctuations and collective plasma eigenmodes in magnetized plasmas. In the latter case, kinetic equations for the components of fluctuating electric and magnetic fields in magnetized plasmas are derived that include the effect of spontaneous emission and absorption. In the limiting case of an unmagnetized plasmas, the general fluctuation spectra correctly reduce to the unmagnetized fluctuation spectra derived before.« less

Photostop of iodine atoms from electrically oriented ICl molecules

NASA Astrophysics Data System (ADS)

Bao, Da-Xiao; Deng, Lian-Zhong; Xu, Liang; Yin, Jian-Ping

2015-11-01

The dynamics of photostopping iodine atoms from electrically oriented ICl molecules was numerically studied based on their orientational probability distribution functions. Velocity distributions of the iodine atoms and their production rates were investigated for orienting electrical fields of various intensities. For the ICl precursor beams with an initial rotational temperature of ∼ 1 K, the production of the iodine atoms near zero speed will be improved by about ∼ 5 times when an orienting electrical field of ∼ 200 kV/cm is present. A production rate of ∼ 0.5‰ is obtained for photostopped iodine atoms with speeds less than 10 m/s, which are suitable for magnetic trapping. The electrical orientation of ICl precursors and magnetic trapping of photostopped iodine atoms in situ can be conveniently realized with a pair of charged ring magnets. With the maximal value of the trapping field being ∼ 0.28 T, the largest trapping speed is ∼ 7.0 m/s for the iodine atom. Project supported by the National Natural Science Foundation of China (Grant Nos. 11034002, 61205198, and 11274114) and the National Key Basic Research and Development Program of China (Grant No. 2011CB921602).

Study of Equatorial Ionospheric irregularities and Mapping of Electron Density Profiles and Ionograms

DTIC Science & Technology

2012-03-09

equation is a product of a complex basis vector in Jackson and a linear combination of plane wave functions. We convert both the amplitudes and the...wave function arguments from complex scalars to complex vectors . This conversion allows us to separate the electric field vector and the imaginary...magnetic field vector , because exponentials of imaginary scalars convert vectors to imaginary vectors and vice versa, while ex- ponentials of imaginary

Split-Block Waveguide Polarization Twist for 220 to 325 GHz

NASA Technical Reports Server (NTRS)

Ward, John; Chattopadhyay, Goutam

2008-01-01

A split-block waveguide circuit that rotates polarization by 90 has been designed with WR-3 input and output waveguides, which are rectangular waveguides used for a nominal frequency range of 220 to 325 GHz. Heretofore, twisted rectangular waveguides equipped with flanges at the input and output have been the standard means of rotating the polarizations of guided microwave signals. However, the fabrication and assembly of such components become difficult at high frequency due to decreasing wavelength, such that twisted rectangular waveguides become impractical at frequencies above a few hundred gigahertz. Conventional twisted rectangular waveguides are also not amenable to integration into highly miniaturized subassemblies of advanced millimeter- and submillimeter-wave detector arrays now undergoing development. In contrast, the present polarization- rotating waveguide can readily be incorporated into complex integrated waveguide circuits such as miniaturized detector arrays fabricated by either conventional end milling of metal blocks or by deep reactive ion etching of silicon blocks. Moreover, the present split-block design can be scaled up in frequency to at least 5 THz. The main step in fabricating a splitblock polarization-rotating waveguide of the present design is to cut channels having special asymmetrically shaped steps into mating upper and lower blocks (see Figure 1). The dimensions of the steps are chosen to be consistent with the WR-3 waveguide cross section, which is 0.864 by 0.432 mm. The channels are characterized by varying widths with constant depths of 0.432, 0.324, and 0.216 mm and by relatively large corner radii to facilitate fabrication. The steps effect both a geometric transition and the corresponding impedance-matched electromagnetic-polarization transition between (1) a WR-3 rectangular waveguide oriented with the electric field vector normal to the block mating surfaces and (2) a corresponding WR-3 waveguide oriented with its electric field vector parallel to the mating surfaces of the blocks. A prototype has been built and tested. Figure 2 presents test results indicative of good performance over nearly the entire WR-3 waveguide frequency band.

Actin cytoskeleton rearrangements in Arabidopsis roots under stress and during gravitropic response

NASA Astrophysics Data System (ADS)

Pozhvanov, Gregory; Medvedev, Sergei; Suslov, Dmitry; Demidchik, Vadim

Among environmental factors, gravity vector is the only one which is constant in direction and accompanies the whole plant ontogenesis. That said, gravity vector can be considered as an essential factor for correct development of plants. Gravitropism is a plant growth response against changing its position relative to the gravity vector. It is well estableshed that gravitropism is directed by auxin redistribution across the gravistimulated organ. In addition to auxin, actin cytoskeleton was shown to be involved in gravitropism at different stages: gravity perception, signal transduction and gravitropic bending formation. However, the relationship between IAA and actin is still under discussion. In this work we studied rearrangements of actin cytoskeleton during root gravitropic response. Actin microfilaments were visualized in vivo in GFP-fABD2 transgenic Arabidopsis plants, and their angle distribution was acquired from MicroFilament Analyzer software. The curvature of actin microfilaments in root elongation zone was shown to be increased within 30-60 min of gravistimulation, the fraction of axially oriented microfilaments decreased with a concomitant increase in the fraction of oblique and transversally oriented microfilaments. In particular, the fraction of transversally oriented microfilaments (i.e. parallel to the gravity vector) increased 3-5 times. Under 10 min of sub-lethal salt stress impact, actin microfilament orientations widened from an initial axial orientation to a set of peaks at 15(°) , 45(°) and 90(°) . We conclude that the actin cytoskeleton rearrangements observed are associated with the regulation of basic mechanisms of cell extension growth by which the gravitropic bending is formed. Having common stress-related features, gravity-induced actin cytoskeleton rearrangement is slower but results in higher number of g-vector-parallel microfilaments when compared to salt stress-induced rearrangement. Also, differences in gravistimulated root growth between wild type and GFP-fABD2 plants are discussed. Project was supported by the OPTEC / Carl Zeiss Personal grant to G.P. (2012), grants of Russian Foundation for Basic Research (11-04-00701a, 14-04-01624a) and by the grant of St.-Petersburg State University (1.38.233.2014).

Rotating electrical machines: Poynting flow

NASA Astrophysics Data System (ADS)

Donaghy-Spargo, C.

2017-09-01

This paper presents a complementary approach to the traditional Lorentz and Faraday approaches that are typically adopted in the classroom when teaching the fundamentals of electrical machines—motors and generators. The approach adopted is based upon the Poynting vector, which illustrates the ‘flow’ of electromagnetic energy. It is shown through simple vector analysis that the energy-flux density flow approach can provide insight into the operation of electrical machines and it is also shown that the results are in agreement with conventional Maxwell stress-based theory. The advantage of this approach is its complementary completion of the physical picture regarding the electromechanical energy conversion process—it is also a means of maintaining student interest in this subject and as an unconventional application of the Poynting vector during normal study of electromagnetism.

Receptive fields of locust brain neurons are matched to polarization patterns of the sky.

PubMed

Bech, Miklós; Homberg, Uwe; Pfeiffer, Keram

2014-09-22

Many animals, including insects, are able to use celestial cues as a reference for spatial orientation and long-distance navigation [1]. In addition to direct sunlight, the chromatic gradient of the sky and its polarization pattern are suited to serve as orientation cues [2-5]. Atmospheric scattering of sunlight causes a regular pattern of E vectors in the sky, which are arranged along concentric circles around the sun [5, 6]. Although certain insects rely predominantly on sky polarization for spatial orientation [7], it has been argued that detection of celestial E vector orientation may not suffice to differentiate between solar and antisolar directions [8, 9]. We show here that polarization-sensitive (POL) neurons in the brain of the desert locust Schistocerca gregaria can overcome this ambiguity. Extracellular recordings from POL units in the central complex and lateral accessory lobes revealed E vector tunings arranged in concentric circles within large receptive fields, matching the sky polarization pattern at certain solar positions. Modeling of neuronal responses under an idealized sky polarization pattern (Rayleigh sky) suggests that these "matched filter" properties allow locusts to unambiguously determine the solar azimuth by relying solely on the sky polarization pattern for compass navigation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Distribution of electric currents in sunspots from photosphere to corona

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gosain, Sanjay; Démoulin, Pascal; López Fuentes, Marcelo

2014-09-20

We present a study of two regular sunspots that exhibit nearly uniform twist from the photosphere to the corona. We derive the twist parameter in the corona and in the chromosphere by minimizing the difference between the extrapolated linear force-free field model field lines and the observed intensity structures in the extreme-ultraviolet images of the Sun. The chromospheric structures appear more twisted than the coronal structures by a factor of two. Further, we derive the vertical component of electric current density, j{sub z} , using vector magnetograms from the Hinode Solar Optical Telescope (SOT). The spatial distribution of j{sub z}more » has a zebra pattern of strong positive and negative values owing to the penumbral fibril structure resolved by Hinode/SOT. This zebra pattern is due to the derivative of the horizontal magnetic field across the thin fibrils; therefore, it is strong and masks weaker currents that might be present, for example, as a result of the twist of the sunspot. We decompose j{sub z} into the contribution due to the derivatives along and across the direction of the horizontal field, which follows the fibril orientation closely. The map of the tangential component has more distributed currents that are coherent with the chromospheric and coronal twisted structures. Moreover, it allows us to map and identify the direct and return currents in the sunspots. Finally, this decomposition of j{sub z} is general and can be applied to any vector magnetogram in order to better identify the weaker large-scale currents that are associated with coronal twisted/sheared structures.« less

Preparation and characterization of oriented poly(vinyl alcohol)/carbon nanotube composite nanofibers

NASA Astrophysics Data System (ADS)

Shimizu, Akikazu; Kato, Hayato; Sato, Taiga; Kushida, Masahito

2017-07-01

Oriented nanofiber mats blended with carbon nanotubes (CNTs) are expected to be applied as cell seeding scaffolds. Biomaterials that are often used for cell seeding scaffolds generally have low mechanical strength and low electrical conductivity; thus, it has been difficult to apply them to tissues such as heart and nerve. In this study, we prepared oriented poly(vinyl alcohol) (PVA) nanofiber mats blended with various CNT concentrations (up to 10 wt %) by electrospinning using the parallel plate electrodes as collectors with applied voltage. The morphology, mechanical properties, and electrical properties of the prepared oriented nanofiber mats were measured by using various techniques such as scanning electron microscopy (SEM). The tensile strength of the oriented nanofiber mats in the applied voltage direction increased from 2.5 to 9.7 MPa with CNT concentration. Furthermore, the electrical conductivity of the oriented nanofiber mats in the applied voltage direction increased from 0.67 × 10-7 to 4.3 × 10-7 S·m-1. Also, the mechanical strength and electrical conductivity of the oriented nanofiber mats in the applied voltage direction were 3-4 and 2-3 times higher than those in the perpendicular direction, respectively.

Quadratic stark effect in the fullerene C60 at low symmetry orientation in the field

NASA Astrophysics Data System (ADS)

Tuchin, A. V.; Bityutskaya, L. A.; Bormontov, E. N.

2014-08-01

Results of numeric simulation of the influence of the electric field E = 0 - 1 V/Å on the electronic structure of the neutral fullerene C60 taking into account orientational deformation of its carbon cage at arbitrary orientations in the electric field including low symmetry orientations are presented. Splitting of the frontier t 1 u - and h u -levels of the molecule due to the quadratic Stark effect has been investigated. Dependencies of the effective electron work function and the energy gap between the lowest unoccupied and highest occupied molecular orbitals on the strengths of the electric field have been determined.

Visual computed tomographic scoring of emphysema and its correlation with its diagnostic electrocardiographic sign: the frontal P vector.

PubMed

Chhabra, Lovely; Sareen, Pooja; Gandagule, Amit; Spodick, David H

2012-03-01

Verticalization of the frontal P vector in patients older than 45 years is virtually diagnostic of pulmonary emphysema (sensitivity, 96%; specificity, 87%). We investigated the correlation of P vector and the computed tomographic visual score of emphysema (VSE) in patients with established diagnosis of chronic obstructive pulmonary disease/emphysema. High-resolution computed tomographic scans of 26 patients with emphysema (age, >45 years) were reviewed to assess the type and extent of emphysema using the subjective visual scoring. Electrocardiograms were independently reviewed to determine the frontal P vector. The P vector and VSE were compared for statistical correlation. Both P vector and VSE were also directly compared with the forced expiratory volume at 1 second. The VSE and the orientation of the P vector (ÂP) had an overall significant positive correlation (r = +0.68; P = .0001) in all patients, but the correlation was very strong in patients with predominant lower-lobe emphysema (r = +0.88; P = .0004). Forced expiratory volume at 1 second and ÂP had almost a linear inverse correlation in predominant lower-lobe emphysema (r = -0.92; P < .0001). Orientation of the P vector positively correlates with visually scored emphysema. Both ÂP and VSE are strong reflectors of qualitative lung function in patients with predominant lower-lobe emphysema. A combination of more vertical ÂP and predominant lower-lobe emphysema reflects severe obstructive lung dysfunction. Copyright © 2012 Elsevier Inc. All rights reserved.

Spin reorientation of a nonsymmetric body with energy dissipation

NASA Technical Reports Server (NTRS)

Cenker, R. J.

1973-01-01

Stable rotating semi-rigid bodies were demonstrated analytically, and verified in flights such as Explorer 1 and ATS-5 satellites. The problem arises from the two potential orientations which the final spin vector can take after large angle reorientation from minor to major axis, i.e., along the positive or negative axis of the maximum inertia. Reorientation of a satellite initially spinning about the minor axis using an energy dissipation device may require that the final spin orientation be controlled. Examples of possible applications are the Apogee Motor Assembly with Paired Satellites (AMAPS) configuration, where proper orientation of the thruster is required; and reorientation of ATS-5, where the spin sensitive nature of the despin device (yo-yo mechanism) requires that the final spin vector point is a specified direction.

Morphology and Orientation Selection of Non-metallic Inclusions in Electrified Molten Metal

NASA Astrophysics Data System (ADS)

Zhao, Z. C.; Qin, R. S.

2017-10-01

The effect of electric current on morphology and orientation selection of non-metallic inclusions in molten metal has been investigated using theoretical modeling and numerical calculation. Two geometric factors, namely the circularity ( fc ) and alignment ratio ( fe ) were introduced to describe the inclusions shape and configuration. Electric current free energy was calculated and the values were used to determine the thermodynamic preference between different microstructures. Electric current promotes the development of inclusion along the current direction by either expatiating directional growth or enhancing directional agglomeration. Reconfiguration of the inclusions to reduce the system electric resistance drives the phenomena. The morphology and orientation selection follow the routine to reduce electric free energy. The numerical results are in agreement with our experimental observations.

Magnetic Field, Density Current, and Lorentz Force Full Vector Maps of the NOAA 10808 Double Sunspot: Evidence of Strong Horizontal Current Flows in the Penumbra

NASA Astrophysics Data System (ADS)

Bommier, V.; Landi Degl'Innocenti, E.; Schmieder, B.; Gelly, B.

2011-04-01

The context is that of the so-called “fundamental ambiguity” (also azimuth ambiguity, or 180° ambiguity) in magnetic field vector measurements: two field vectors symmetrical with respect to the line-of-sight have the same polarimetric signature, so that they cannot be discriminated. We propose a method to solve this ambiguity by applying the “simulated annealing” algorithm to the minimization of the field divergence, added to the longitudinal current absolute value, the line-of-sight derivative of the magnetic field being inferred by the interpretation of the Zeeman effect observed by spectropolarimetry in two lines formed at different depths. We find that the line pair Fe I λ 6301.5 and Fe I λ 6302.5 is appropriate for this purpose. We treat the example case of the δ-spot of NOAA 10808 observed on 13 September 2005 between 14:25 and 15:25 UT with the THEMIS telescope. Besides the magnetic field resolved map, the electric current density vector map is also obtained. A strong horizontal current density flow is found surrounding each spot inside its penumbra, associated to a non-zero Lorentz force centripetal with respect to the spot center (i.e., oriented towards the spot center). The current wrapping direction is found to depend on the spot polarity: clockwise for the positive polarity, counterclockwise for the negative one. This analysis is made possible thanks to the UNNOFIT2 Milne-Eddington inversion code, where the usual theory is generalized to the case of a line Fe I λ 6301.5) that is not a normal Zeeman triplet line (like Fe I λ 6302.5).

Unique system of FE/PD for magneto-optical recording and magnetic switching devices

DOEpatents

Liu, Chian Q.; Bader, Samuel D.

1992-01-01

A high density magneto-optical information storage medium utilizing the properties of an ultrathin iron film on a palladium substrate. The present invention comprises a magneto-optical medium capable of thermal and magnetic stability and capable of possessing a vertical orientation of the magnetization vector for the magnetic material. Data storage relies on the temperature dependence of the coercivity of the ultrathin film. Data retrieval derives from the Kerr effect which describes the direction of rotation of a plane of polarized light traversing the ultrathin magnetic material as a function of the orientation of the magnetization vector.

Vector electric field measurement via position-modulated Kelvin probe force microscopy

NASA Astrophysics Data System (ADS)

Dwyer, Ryan P.; Smieska, Louisa M.; Tirmzi, Ali Moeed; Marohn, John A.

2017-10-01

High-quality spatially resolved measurements of electric fields are critical to understanding charge injection, charge transport, and charge trapping in semiconducting materials. Here, we report a variation of frequency-modulated Kelvin probe force microscopy that enables spatially resolved measurements of the electric field. We measure electric field components along multiple directions simultaneously by employing position modulation and lock-in detection in addition to numeric differentiation of the surface potential. We demonstrate the technique by recording linescans of the in-plane electric field vector in the vicinity of a patch of trapped charge in a 2,7-diphenyl[1]benzothieno[3,2-b][1]benzothiophene (DPh-BTBT) organic field-effect transistor. This technique is simple to implement and should be especially useful for studying electric fields in spatially inhomogeneous samples like organic transistors and photovoltaic blends.

Vector tomography for reconstructing electric fields with non-zero divergence in bounded domains

NASA Astrophysics Data System (ADS)

Koulouri, Alexandra; Brookes, Mike; Rimpiläinen, Ville

2017-01-01

In vector tomography (VT), the aim is to reconstruct an unknown multi-dimensional vector field using line integral data. In the case of a 2-dimensional VT, two types of line integral data are usually required. These data correspond to integration of the parallel and perpendicular projection of the vector field along the integration lines and are called the longitudinal and transverse measurements, respectively. In most cases, however, the transverse measurements cannot be physically acquired. Therefore, the VT methods are typically used to reconstruct divergence-free (or source-free) velocity and flow fields that can be reconstructed solely from the longitudinal measurements. In this paper, we show how vector fields with non-zero divergence in a bounded domain can also be reconstructed from the longitudinal measurements without the need of explicitly evaluating the transverse measurements. To the best of our knowledge, VT has not previously been used for this purpose. In particular, we study low-frequency, time-harmonic electric fields generated by dipole sources in convex bounded domains which arise, for example, in electroencephalography (EEG) source imaging. We explain in detail the theoretical background, the derivation of the electric field inverse problem and the numerical approximation of the line integrals. We show that fields with non-zero divergence can be reconstructed from the longitudinal measurements with the help of two sparsity constraints that are constructed from the transverse measurements and the vector Laplace operator. As a comparison to EEG source imaging, we note that VT does not require mathematical modeling of the sources. By numerical simulations, we show that the pattern of the electric field can be correctly estimated using VT and the location of the source activity can be determined accurately from the reconstructed magnitudes of the field.

Torque vectoring for improving stability of small electric vehicles

NASA Astrophysics Data System (ADS)

Grzegożek, W.; Weigel-Milleret, K.

2016-09-01

The electric vehicles solutions based on the individually controlled electric motors propel a single wheel allow to improve the dynamic properties of the vehicle by varying the distribution of the driving torque. Most of the literature refer to the vehicles with a track typical for passenger cars. This paper examines whether the narrow vehicle (with a very small track) torque vectoring bring a noticeable change of the understeer characteristics and whether torque vectoring is possible to use in securing a narrow vehicle from roll over (roll mitigation). The paper contains road tests of the steering characteristics (steady state understeer characteristic quasi-static acceleration with a fixed steering wheel (SH = const) and on the constant radius track (R = const)) of the narrow vehicle. The vehicle understeer characteristic as a function of a power distribution is presented.

Evolutionary programming-based univector field navigation method for past mobile robots.

PubMed

Kim, Y J; Kim, J H; Kwon, D S

2001-01-01

Most of navigation techniques with obstacle avoidance do not consider the robot orientation at the target position. These techniques deal with the robot position only and are independent of its orientation and velocity. To solve these problems this paper proposes a novel univector field method for fast mobile robot navigation which introduces a normalized two dimensional vector field. The method provides fast moving robots with the desired posture at the target position and obstacle avoidance. To obtain the sub-optimal vector field, a function approximator is used and trained by evolutionary programming. Two kinds of vector fields are trained, one for the final posture acquisition and the other for obstacle avoidance. Computer simulations and real experiments are carried out for a fast moving mobile robot to demonstrate the effectiveness of the proposed scheme.

Modeling control of eye orientation in three dimensions. I. Role of muscle pulleys in determining saccadic trajectory.

PubMed

Raphan, T

1998-05-01

This study evaluates the effects of muscle axis shifts on the performance of a vector velocity-position integrator in the CNS. Earlier models of the oculomotor plant assumed that the muscle axes remained fixed relative to the head as the eye rotated into secondary and tertiary eye positions. Under this assumption, the vector integrator model generates torsional transients as the eye moves from secondary to tertiary positions of fixation. The torsional transient represents an eye movement response to a spatial mismatch between the torque axes that remain fixed in the head and the displacement plane that changes by half the angle of the change in eye orientation. When muscle axis shifts were incorporated into the model, the torque axes were closer to the displacement plane at each eye orientation throughout the trajectory, and torsional transients were reduced dramatically. Their size and dynamics were close to reported data. It was also shown that when the muscle torque axes were rotated by 50% of the eye rotation, there was no torsional transient and Listing's law was perfectly obeyed. When muscle torque axes rotated >50%, torsional transients reversed direction compared with what occurred for muscle axis shifts of <50%. The model indicates that Listing's law is implemented by the oculomotor plant subject to a two-dimensional command signal that is confined to the pitch-yaw plane, having zero torsion. Saccades that bring the eye to orientations outside Listing's plane could easily be corrected by a roll pulse that resets the roll state of the velocity-position integrator to zero. This would be a simple implementation of the corrective controller suggested by Van Opstal and colleagues. The model further indicates that muscle axis shifts together with the torque orientation relationship for tissue surrounding the eye and Newton's laws of motion form a sufficient plant model to explain saccadic trajectories and periods of fixation when driven by a vector command confined to the pitch-yaw plane. This implies that the velocity-position integrator is probably realized as a subtractive feedback vector integrator and not as a quaternion-based integrator that implements kinematic transformations to orient the eye.

Field-controllable Spin-Hall Effect of Light in Optical Crystals: A Conoscopic Mueller Matrix Analysis.

PubMed

Samlan, C T; Viswanathan, Nirmal K

2018-01-31

Electric-field applied perpendicular to the direction of propagation of paraxial beam through an optical crystal dynamically modifies the spin-orbit interaction (SOI), leading to the demonstration of controllable spin-Hall effect of light (SHEL). The electro- and piezo-optic effects of the crystal modifies the radially symmetric spatial variation in the fast-axis orientation of the crystal, resulting in a complex pattern with different topologies due to the symmetry-breaking effect of the applied field. This introduces spatially-varying Pancharatnam-Berry type geometric phase on to the paraxial beam of light, leading to the observation of SHEL in addition to the spin-to-vortex conversion. A wave-vector resolved conoscopic Mueller matrix measurement and analysis provides a first glimpse of the SHEL in the biaxial crystal, identified via the appearance of weak circular birefringence. The emergence of field-controllable fast-axis orientation of the crystal and the resulting SHEL provides a new degree of freedom for affecting and controlling the spin and orbital angular momentum of photons to unravel the rich underlying physics of optical crystals and aid in the development of active photonic spin-Hall devices.

Heart Electrical Actions as Biometric Indicia

NASA Technical Reports Server (NTRS)

Schipper, John F. (Inventor); Dusan, Sorin V. (Inventor); Jorgensen, Charles C. (Inventor); Belousof, Eugene (Inventor)

2013-01-01

A method and associated system for use of statistical parameters based on peak amplitudes and/or time interval lengths and/or depolarization-repolarization vector angles and/or depolarization-repolarization vector lengths for PQRST electrical signals associated with heart waves, to identify a person. The statistical parameters, estimated to be at least 192, serve as biometric indicia, to authenticate, or to decline to authenticate, an asserted identity of a candidate person.

Vector coding of wavelet-transformed images

NASA Astrophysics Data System (ADS)

Zhou, Jun; Zhi, Cheng; Zhou, Yuanhua

1998-09-01

Wavelet, as a brand new tool in signal processing, has got broad recognition. Using wavelet transform, we can get octave divided frequency band with specific orientation which combines well with the properties of Human Visual System. In this paper, we discuss the classified vector quantization method for multiresolution represented image.

Seasonal dispersal of the oak wilt fungus by Colopterus truncatus and Carpophilus sayi in Minnesota

Treesearch

Angie K. Ambourn; Jennifer Juzwik; Roger D. Moon

2005-01-01

Sap beetles (Nitidulidae) are considered important overland vectors of the oak wilt pathogen, Ceratocystis fagacearum, in the north central United States. Colopterus truncatus and Carpophilus sayi are thought to be the principal sap beetle vectors in Minnesota. Field studies using wind-oriented funnel traps...

Electromagnetically induced transparency in the case of elliptic polarization of interacting fields

NASA Astrophysics Data System (ADS)

Parshkov, Oleg M.

2018-04-01

The theoretical investigation results of disintegration effect of elliptic polarized shot probe pulses of electromagnetically induced transparency in the counterintuitive superposed elliptic polarized control field and in weak probe field approximation are presented. It is shown that this disintegration occurs because the probe field in the medium is the sum of two normal modes, which correspond to elliptic polarized pulses with different speeds of propagation. The polarization ellipses of normal modes have equal eccentricities and mutually perpendicular major axes. Major axis of polarization ellipse of one normal mode is parallel to polarization ellipse major axis of control field, and electric vector of this mode rotates in the opposite direction, than electric vector of the control field. The electric vector other normal mode rotates in the same direction that the control field electric vector. The normal mode speed of the first type aforementioned is less than that of the second type. The polarization characteristics of the normal mode depend uniquely on the polarization characteristics of elliptic polarized control field and remain changeless in the propagation process. The theoretical investigation is performed for Λ-scheme of degenerated quantum transitions between 3P0, 3P10 and 3P2 energy levels of 208Pb isotope.

78 FR 64011 - Tolling of Activity in Antidumping and Countervailing Duty Proceedings

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-25

.... (Preliminary): Grain- Oriented Electrical Steel from China, Czech Republic, Germany, Japan, Korea, Poland, and... 2013, 9:30 a.m. (Preliminary): Non-Oriented Electrical Steel from China, Germany, Japan, Korea, Sweden...

Rigorous theory of molecular orientational nonlinear optics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwak, Chong Hoon, E-mail: chkwak@ynu.ac.kr; Kim, Gun Yeup

2015-01-15

Classical statistical mechanics of the molecular optics theory proposed by Buckingham [A. D. Buckingham and J. A. Pople, Proc. Phys. Soc. A 68, 905 (1955)] has been extended to describe the field induced molecular orientational polarization effects on nonlinear optics. In this paper, we present the generalized molecular orientational nonlinear optical processes (MONLO) through the calculation of the classical orientational averaging using the Boltzmann type time-averaged orientational interaction energy in the randomly oriented molecular system under the influence of applied electric fields. The focal points of the calculation are (1) the derivation of rigorous tensorial components of the effective molecularmore » hyperpolarizabilities, (2) the molecular orientational polarizations and the electronic polarizations including the well-known third-order dc polarization, dc electric field induced Kerr effect (dc Kerr effect), optical Kerr effect (OKE), dc electric field induced second harmonic generation (EFISH), degenerate four wave mixing (DFWM) and third harmonic generation (THG). We also present some of the new predictive MONLO processes. For second-order MONLO, second-order optical rectification (SOR), Pockels effect and difference frequency generation (DFG) are described in terms of the anisotropic coefficients of first hyperpolarizability. And, for third-order MONLO, third-order optical rectification (TOR), dc electric field induced difference frequency generation (EFIDFG) and pump-probe transmission are presented.« less

Experimental investigation into the coupling effects of magnetic field, temperature and pressure on electrical resistivity of non-oriented silicon steel sheet

NASA Astrophysics Data System (ADS)

Xiao, Lijun; Yu, Guodong; Zou, Jibin; Xu, Yongxiang

2018-05-01

In order to analyze the performance of magnetic device which operate at high temperature and high pressure, such as submersible motor, oil well transformer, the electrical resistivity of non-oriented silicon steel sheets is necessary for precise analysis. But the reports of the examination of the measuring method suitable for high temperature up to 180 °C and high pressure up to 140 MPa are few. In this paper, a measurement system based on four-probe method and Archimedes spiral shape measurement specimens is proposed. The measurement system is suitable for measuring the electrical resistivity of unconventional specimens under high temperature and high pressure and can simultaneously consider the influence of the magnetic field on the electrical resistivity. It can be seen that the electrical resistivity of the non-oriented silicon steel sheets will fluctuate instantaneously when the magnetic field perpendicular to the conductive path of the specimens is loaded or removed. The amplitude and direction of the fluctuation are not constant. Without considering the effects of fluctuations, the electrical resistivity of the non-oriented silicon steel sheets is the same when the magnetic field is loaded or removed. And the influence of temperature on the electrical resistivity of the non-oriented silicon steel sheet is still the greatest even though the temperature and the pressure are coupled together. The measurement results also show that the electrical resistivity varies linearly with temperature, so the temperature coefficient of resistivity is given in the paper.

Center of mass trajectory and orientation to ankle and knee in sagittal plane is maintained with forward lean when backpack load changes during treadmill walking.

PubMed

Caron, Robert R; Wagenaar, Robert C; Lewis, Cara L; Saltzman, Elliot; Holt, Kenneth G

2013-01-04

Maintaining the normal shape and amplitude of the vertical trajectory of the center of mass (COM) during stance has been shown to maximize the efficiency of unloaded gait. Kinematic adaptations to load carriage, such as forward lean have yet to be understood in relation to COM movement. The purpose of this study is to better understand how load impacts the vertical COM(TSYS) trajectory and to clarify the impact of forward lean as it relates to the dynamics of sagittal plane COM(TSYS) movement during stance with changing load. 17 subjects walked on treadmill at a constant preferred walking velocity while nine different loads ranging from 12.5% to 40% bodyweight were systematically added and removed from a backpack. Kinematic data were collected using an Optotrak, three-dimensional motion analysis system and used to estimate position of the COM as well as segment and COM-to-joint vector orientation angles. The shape and amplitude of the COM vertical trajectory was maintained across all loaded conditions. The orientations of COM-to-ankle and -knee vectors were maintained in all loaded conditions except the heaviest load (40% BW). Results suggest that forward lean changed linearly with changes in load to maintain the COM-to-ankle and -knee vector orientations. COM vertical trajectory was maintained by a combination of invariants including lower-limb segment angles and a constant direction of toe-off impulse vector. The kinematic invariants found suggest a simplified control mechanism by which the system limits degrees of freedom and potentially minimizes torque about lower-extremity joints with added load. Copyright © 2012 Elsevier Ltd. All rights reserved.

Paleomagnetic Reorientation of Structural Elements in Drill Cores: an example from Tolhuaca Geothermal Field

NASA Astrophysics Data System (ADS)

Perez-Flores, P.; Veloso, E. E.; Cembrano, J. M.; Sánchez, P.; Iriarte, S.; Lohmar, S.

2013-12-01

Reorientation of mesoscopic faults, veins and fractures recovered from drilling is critical to construct reliable structural models that can account for their architecture and deformation regime. However, oriented cores are expensive and time consuming to drill. Some techniques achieve reorientation by introducing tools into the borehole. Problems arise when boreholes are unstable or collapse. One alternative technique allowing reorientation is to obtain reliable paleomagnetic vectors to reorient each core piece after drilling. Here, we present stable and reliable remnant magnetic vectors calculated from the Tol-1 core to analyze the geometry of the fracture network and its relationship to regional tectonic. Tol-1 core is a vertical, 1073 m deep geothermal well, drilled at the Tolhuaca Geothermal Field in the Southern Volcanic Zone of the Andes by MRP Geothermal Chile Ltda (formerly GGE Chile SpA) in 2009. The core consists of basaltic/andesitic volcanic rocks with subordinate pyroclastic/volcaniclastic units, with probable Pleistocene age. Fault planes with slickenlines and mineral fiber kinematic indicators are common in the upper 700 m of the core. Calcite, quartz and calcite-quartz veins are recognized along of entire core, whereas epidote-quartz and calcite-epidote veins occur in the last 350 m, minor chlorite, anhydrite and clay-minerals are present. Orientations of structural features in the core were measured with a goniometer using the core's axis and a false north for each piece; hence, orientation data has a false strike but a real dip. To achieve total reorientation of the pieces, we collected 200 standard-size paleomagnetic specimens, ensuring that at least four of them were recovered from continuous pieces. Thermal (up to 700°C) and alternating field demagnetization (up to 90mT on steps of 2mT) methods were used to isolate a stable remnant magnetization (RM) vector, and each technique yielded similar results. RM vectors were recovered between 0 to 25mT, and between 0 to 625°C. The declination of RM vectors was used to bring pieces to a common anchor orientation calculated through the Geocentric Axial Dipole Model (GAD). The paleomagnetic technique proved to be reliable to reorient the Tol-1 core. Structural analyses along the core show N50-60E-striking preferential vein orientation. In addition, N40-50E- and N60-70W-striking preferential fault orientations were identified. Kinematic analysis of fault-slip data shows a N60E-striking bulk fault plane solution with normal strain regime. The veins and faults orientation show strain axes compatible with published regional stress field (σmax N238E).

Statistics of partially-polarized fields: beyond the Stokes vector and coherence matrix

NASA Astrophysics Data System (ADS)

Charnotskii, Mikhail

2017-08-01

Traditionally, the partially-polarized light is characterized by the four Stokes parameters. Equivalent description is also provided by correlation tensor of the optical field. These statistics specify only the second moments of the complex amplitudes of the narrow-band two-dimensional electric field of the optical wave. Electric field vector of the random quasi monochromatic wave is a nonstationary oscillating two-dimensional real random variable. We introduce a novel statistical description of these partially polarized waves: the Period-Averaged Probability Density Function (PA-PDF) of the field. PA-PDF contains more information on the polarization state of the field than the Stokes vector. In particular, in addition to the conventional distinction between the polarized and depolarized components of the field PA-PDF allows to separate the coherent and fluctuating components of the field. We present several model examples of the fields with identical Stokes vectors and very distinct shapes of PA-PDF. In the simplest case of the nonstationary, oscillating normal 2-D probability distribution of the real electrical field and stationary 4-D probability distribution of the complex amplitudes, the newly-introduced PA-PDF is determined by 13 parameters that include the first moments and covariance matrix of the quadrature components of the oscillating vector field.

A Re-Unification of Two Competing Models for Document Retrieval.

ERIC Educational Resources Information Center

Bodoff, David

1999-01-01

Examines query-oriented versus document-oriented information retrieval and feedback learning. Highlights include a reunification of the two approaches for probabilistic document retrieval and for vector space model (VSM) retrieval; learning in VSM and in probabilistic models; multi-dimensional scaling; and ongoing field studies. (LRW)

Spatial orientation of optokinetic nystagmus and ocular pursuit during orbital space flight

NASA Technical Reports Server (NTRS)

Moore, Steven T.; Cohen, Bernard; Raphan, Theodore; Berthoz, Alain; Clement, Gilles

2005-01-01

On Earth, eye velocity of horizontal optokinetic nystagmus (OKN) orients to gravito-inertial acceleration (GIA), the sum of linear accelerations acting on the head and body. We determined whether adaptation to micro-gravity altered this orientation and whether ocular pursuit exhibited similar properties. Eye movements of four astronauts were recorded with three-dimensional video-oculography. Optokinetic stimuli were stripes moving horizontally, vertically, and obliquely at 30 degrees/s. Ocular pursuit was produced by a spot moving horizontally or vertically at 20 degrees/s. Subjects were either stationary or were centrifuged during OKN with 1 or 0.5 g of interaural or dorsoventral centripetal linear acceleration. Average eye position during OKN (the beating field) moved into the quick-phase direction by 10 degrees during lateral and upward field movement in all conditions. The beating field did not shift up during downward OKN on Earth, but there was a strong upward movement of the beating field (9 degrees) during downward OKN in the absence of gravity; this likely represents an adaptation to the lack of a vertical 1-g bias in-flight. The horizontal OKN velocity axis tilted 9 degrees in the roll plane toward the GIA during interaural centrifugation, both on Earth and in space. During oblique OKN, the velocity vector tilted towards the GIA in the roll plane when there was a disparity between the direction of stripe motion and the GIA, but not when the two were aligned. In contrast, dorsoventral acceleration tilted the horizontal OKN velocity vector 6 degrees in pitch away from the GIA. Roll tilts of the horizontal OKN velocity vector toward the GIA during interaural centrifugation are consistent with the orientation properties of velocity storage, but pitch tilts away from the GIA when centrifuged while supine are not. We speculate that visual suppression during OKN may have caused the velocity vector to tilt away from the GIA during dorsoventral centrifugation. Vertical OKN and ocular pursuit did not exhibit orientation toward the GIA in any condition. Static full-body roll tilts and centrifugation generating an equivalent interaural acceleration produced the same tilts in the horizontal OKN velocity before and after flight. Thus, the magnitude of tilt in OKN velocity was dependent on the magnitude of interaural linear acceleration, rather than the tilt of the GIA with regard to the head. These results favor a 'filter' model of spatial orientation in which orienting eye movements are proportional to the magnitude of low frequency interaural linear acceleration, rather than models that postulate an internal representation of gravity as the basis for spatial orientation.

Polarization masks: concept and initial assessment

NASA Astrophysics Data System (ADS)

Lam, Michael; Neureuther, Andrew R.

2002-07-01

Polarization from photomasks can be used as a new lever to improve lithographic performance in both binary and phase-shifting masks (PSMs). While PSMs manipulate the phase of light to control the temporal addition of electric field vectors, polarization masks manipulate the vector direction of electric field vectors to control the spatial addition of electric field components. This paper explores the theoretical possibilities of polarization masks, showing that it is possible to use bar structures within openings on the mask itself to polarize incident radiation. Rigorous electromagnetic scattering simulations using TEMPEST and imaging with SPLAT are used to give an initial assessment on the functionality of polarization masks, discussing the polarization quality and throughputs achieved with the masks. Openings between 1/8 and 1/3 of a wavelength provide both a low polarization ratio and good transmission. A final overall throughput of 33% - 40% is achievable, corresponding to a dose hit of 2.5x - 3x.

How the borderless science of electropenetrography (EPG) can benefit animal-disease vector research: overview of EPG history, principles, and applications

USDA-ARS?s Scientific Manuscript database

Studying feeding, host injury, and transmission of plant or animal pathogens by vectors is challenging. Vector piercing-sucking mouthparts are probed into opaque tissues, precluding direct observation. Over fifty years ago, this challenge was overcome by development of electrical penetration graph t...

Non-singular spherical harmonic expressions of geomagnetic vector and gradient tensor fields in the local north-oriented reference frame

NASA Astrophysics Data System (ADS)

Du, J.; Chen, C.; Lesur, V.; Wang, L.

2014-12-01

General expressions of magnetic vector (MV) and magnetic gradient tensor (MGT) in terms of the first- and second-order derivatives of spherical harmonics at different degrees and orders, are relatively complicated and singular at the poles. In this paper, we derived alternative non-singular expressions for the MV, the MGT and also the higher-order partial derivatives of the magnetic field in local north-oriented reference frame. Using our newly derived formulae, the magnetic potential, vector and gradient tensor fields at an altitude of 300 km are calculated based on a global lithospheric magnetic field model GRIMM_L120 (version 0.0) and the main magnetic field model of IGRF11. The corresponding results at the poles are discussed and the validity of the derived formulas is verified using the Laplace equation of the potential field.

Vector and Axial-Vector Current Correlators Within the Instanton Model of QCD Vacuum

NASA Astrophysics Data System (ADS)

Dorokhov, A. E.

2005-08-01

The pion electric polarizability, α {π ^ ± }E , the leading order hadronic contribution to the muon anomalous magnetic moment, aμ hvp(1) , and the ratio of the V - A and V + A correlators are found within the instanton model of QCD vacuum. The results are compared with phenomenological estimates of these quantities from the ALEPH and OPAL data on vector and axial-vector spectral densities.

Highly Polarized Fluorescent Illumination Using Liquid Crystal Phase.

PubMed

Gim, Min-Jun; Turlapati, Srikanth; Debnath, Somen; Rao, Nandiraju V S; Yoon, Dong Ki

2016-02-10

Liquid crystal (LC) materials are currently the dominant electronic materials in display technology because of the ease of control of molecular orientation using an electric field. However, this technology requires the fabrication of two polarizers to create operational displays, reducing light transmission efficiency below 10%. It is therefore desirable to develop new technologies to enhance the light efficiency while maintaining or improving other properties such as the modulation speed of the molecular orientation. Here we report a uniaxial-oriented B7 smectic liquid crystalline film, using fluorescent bent-core LC molecules, a chemically modified substrate, and an in-plane electric field. A LC droplet under homeotropic boundary conditions of air/LC as well as LC/substrate exhibits large focal conic like optical textures. The in-plane electric field induced uniaxial orientation of the LC molecules, in which molecular polar directors are aligned in the direction of the electric field. This highly oriented LC film exhibits linearly polarized luminescence and microsecond time-scale modulation characteristics. The resultant device is both cheap and easy to fabricate and thus has great potential for electro-optic applications, including LC displays, bioimaging systems, and optical communications.

Geo-electrical and geological strikes of the Mount Lamongan geothermal area, East Java, Indonesia – preliminary results

NASA Astrophysics Data System (ADS)

Nugraheni, L. R.; Niasari, S. W.; Nukman, M.

2018-04-01

Geothermal manifestations located in the Tiris, Mount Lamongan, Probolinggo, consist of warm springs. These warm springs have temperature from 35° until 45°C. Tiris fault has NW-SE dominant orientation, similar to some lineaments of maars and cinder cones around Mount Lamongan. The Mount Lamongan geothermal area is situated between Bromo and Argapura volcanoes. This study aims to map the geo-electrical and geological strikes in the study area. Phase tensor analysis has been performed in this study to determine geo-electrical strike of study area. Geological field campaign has been conducted to measure geological strikes. Then, orientation of geo-electrical strike was compared to geological strike. The result presents that the regional geological strike of study area is NW-SE while the orientation of geo-electrical strike is N-S.

A Subdivision-Based Representation for Vector Image Editing.

PubMed

Liao, Zicheng; Hoppe, Hugues; Forsyth, David; Yu, Yizhou

2012-11-01

Vector graphics has been employed in a wide variety of applications due to its scalability and editability. Editability is a high priority for artists and designers who wish to produce vector-based graphical content with user interaction. In this paper, we introduce a new vector image representation based on piecewise smooth subdivision surfaces, which is a simple, unified and flexible framework that supports a variety of operations, including shape editing, color editing, image stylization, and vector image processing. These operations effectively create novel vector graphics by reusing and altering existing image vectorization results. Because image vectorization yields an abstraction of the original raster image, controlling the level of detail of this abstraction is highly desirable. To this end, we design a feature-oriented vector image pyramid that offers multiple levels of abstraction simultaneously. Our new vector image representation can be rasterized efficiently using GPU-accelerated subdivision. Experiments indicate that our vector image representation achieves high visual quality and better supports editing operations than existing representations.

Effects of duration of electric pulse on in vitro development of cloned cat embryos with human artificial chromosome vector.

PubMed

Do, Ltk; Wittayarat, M; Terazono, T; Sato, Y; Taniguchi, M; Tanihara, F; Takemoto, T; Kazuki, Y; Kazuki, K; Oshimura, M; Otoi, T

2016-12-01

The current applications for cat cloning include production of models for the study of human and animal diseases. This study was conducted to investigate the optimal fusion protocol on in vitro development of transgenic cloned cat embryos by comparing duration of electric pulse. Cat fibroblast cells containing a human artificial chromosome (HAC) vector were used as genetically modified nuclear donor cells. Couplets were fused and activated simultaneously with a single DC pulse of 3.0 kV/cm for either 30 or 60 μs. Low rates of fusion and embryo development to the blastocyst stage were observed in the reconstructed HAC-transchromosomic embryos, when the duration of fusion was prolonged to 60 μs. In contrast, the prolongation of electric pulse duration improved the embryo development and quality in the reconstructed control embryos without HAC vector. Our results suggested that the optimal parameters of electric pulses for fusion in cat somatic cell nuclear transfer vary among the types used for donor cells. © 2016 Blackwell Verlag GmbH.

Tailored optical vector fields for ultrashort-pulse laser induced complex surface plasmon structuring.

PubMed

Ouyang, J; Perrie, W; Allegre, O J; Heil, T; Jin, Y; Fearon, E; Eckford, D; Edwardson, S P; Dearden, G

2015-05-18

Precise tailoring of optical vector beams is demonstrated, shaping their focal electric fields and used to create complex laser micro-patterning on a metal surface. A Spatial Light Modulator (SLM) and a micro-structured S-waveplate were integrated with a picosecond laser system and employed to structure the vector fields into radial and azimuthal polarizations with and without a vortex phase wavefront as well as superposition states. Imprinting Laser Induced Periodic Surface Structures (LIPSS) elucidates the detailed vector fields around the focal region. In addition to clear azimuthal and radial plasmon surface structures, unique, variable logarithmic spiral micro-structures with a pitch Λ ∼1μm, not observed previously, were imprinted on the surface, confirming unambiguously the complex 2D focal electric fields. We show clearly also how the Orbital Angular Momentum(OAM) associated with a helical wavefront induces rotation of vector fields along the optic axis of a focusing lens and confirmed by the observed surface micro-structures.

The Fundamentals of Dislocation Transport of Hydrogen in BCC Iron.

DTIC Science & Technology

1984-10-01

4.2.1. Single Crystal Material 24 4.2.2. Polycrystalline Material 25 4.3. Single Crystal Orientation Determination 25 4.4. Straining Permeation Test 27...Test 45 4.6. Supersaturation Study 47 S. RESULTS AND DISCUSSION 50 5.1. Single Crystal Orientation Determination 50 5.1.1. Slip System Determination 58...Orientation 162 Determination B.1. Dislocation Line Direction Determination 162 B.2. Burgers Vector Determination 164

Characterization of the Solution Structure of Human Serum Albumin Loaded with a Metal Porphyrin and Fatty Acids

PubMed Central

Junk, Matthias J.N.; Spiess, Hans W.; Hinderberger, Dariush

2011-01-01

The structure of human serum albumin loaded with a metal porphyrin and fatty acids in solution is characterized by orientation-selective double electron-electron resonance (DEER) spectroscopy. Human serum albumin, spin-labeled fatty acids, and Cu(II) protoporphyrin IX—a hemin analog—form a fully self-assembled system that allows obtaining distances and mutual orientations between the paramagnetic guest molecules. We report a simplified analysis for the orientation-selective DEER data which can be applied when the orientation selection of one spin in the spin pair dominates the orientation selection of the other spin. The dipolar spectra reveal a dominant distance of 3.85 nm and a dominant orientation of the spin-spin vectors between Cu(II) protoporphyrin IX and 16-doxyl stearic acid, the electron paramagnetic resonance reporter group of the latter being located near the entry points to the fatty acid binding sites. This observation is in contrast to crystallographic data that suggest an asymmetric distribution of the entry points in the protein and hence the occurrence of various distances. In conjunction with the findings of a recent DEER study, the obtained data are indicative of a symmetric distribution of the binding site entries on the protein's surface. The overall anisotropic shape of the protein is reflected by one spin-spin vector orientation dominating the DEER data. PMID:21539799

Graviperception and gravitaxis in flagellates

NASA Astrophysics Data System (ADS)

Häder, D.; Ntefidou, M.

Many photosynthetic and heterotrophic flagellates perceive and respond to the gravitational vector of the Earth. Some previous hypotheses have suggested that the orientation is brought about by a passive physical mechanism such as buoyancy or hydrodynamic alignment. However, recent results have confirmed that e.g. the photosynthetic Euglena utilizes an active physiological sensor and an internal sensory transduction chain. This unicellular organism senses gravity by the sedimentation of its cellular content, which is heavier than the surrounding medium, onto the lower membrane. This force is believed to activate mechano-sensitive ion channels located at the front end under the trailing flagellum. The channels allow a gated influx of calcium which alters the internal electrical potential and may activate calmodulin. Further elements in the transduction chain are cyclic AMP and related enzymes. Recent flight experiments during parabolic aircraft maneuvers and on sounding rockets have confirmed previous terrestrial results and have provided detailed insight into the biochemical sensory transduction chain.

Continuous micron-scaled rope engineering using a rotating multi-nozzle electrospinning emitter

NASA Astrophysics Data System (ADS)

Zhang, Chunchen; Gao, Chengcheng; Chang, Ming-Wei; Ahmad, Zeeshan; Li, Jing-Song

2016-10-01

Electrospinning (ES) enables simple production of fibers for broad applications (e.g., biomedical engineering, energy storage, and electronics). However, resulting structures are predominantly random; displaying significant disordered fiber entanglement, which inevitably gives rise to structural variations and reproducibility on the micron scale. Surface and structural features on this scale are critical for biomaterials, tissue engineering, and pharmaceutical sciences. In this letter, a modified ES technique using a rotating multi-nozzle emitter is developed and utilized to fabricate continuous micron-scaled polycaprolactone (PCL) ropes, providing control on fiber intercalation (twist) and structural order. Micron-scaled ropes comprising 312 twists per millimeter are generated, and rope diameter and pitch length are regulated using polymer concentration and process parameters. Electric field simulations confirm vector and distribution mechanisms, which influence fiber orientation and deposition during the process. The modified fabrication system provides much needed control on reproducibility and fiber entanglement which is crucial for electrospun biomedical materials.

Polarization singularity indices in Gaussian laser beams

NASA Astrophysics Data System (ADS)

Freund, Isaac

2002-01-01

Two types of point singularities in the polarization of a paraxial Gaussian laser beam are discussed in detail. V-points, which are vector point singularities where the direction of the electric vector of a linearly polarized field becomes undefined, and C-points, which are elliptic point singularities where the ellipse orientations of elliptically polarized fields become undefined. Conventionally, V-points are characterized by the conserved integer valued Poincaré-Hopf index η, with generic value η=±1, while C-points are characterized by the conserved half-integer singularity index IC, with generic value IC=±1/2. Simple algorithms are given for generating V-points with arbitrary positive or negative integer indices, including zero, at arbitrary locations, and C-points with arbitrary positive or negative half-integer or integer indices, including zero, at arbitrary locations. Algorithms are also given for generating continuous lines of these singularities in the plane, V-lines and C-lines. V-points and C-points may be transformed one into another. A topological index based on directly measurable Stokes parameters is used to discuss this transformation. The evolution under propagation of V-points and C-points initially embedded in the beam waist is studied, as is the evolution of V-dipoles and C-dipoles.

An MHD Simulation of Solar Active Region 11158 Driven with a Time-dependent Electric Field Determined from HMI Vector Magnetic Field Measurement Data

NASA Astrophysics Data System (ADS)

Hayashi, Keiji; Feng, Xueshang; Xiong, Ming; Jiang, Chaowei

2018-03-01

For realistic magnetohydrodynamics (MHD) simulation of the solar active region (AR), two types of capabilities are required. The first is the capability to calculate the bottom-boundary electric field vector, with which the observed magnetic field can be reconstructed through the induction equation. The second is a proper boundary treatment to limit the size of the sub-Alfvénic simulation region. We developed (1) a practical inversion method to yield the solar-surface electric field vector from the temporal evolution of the three components of magnetic field data maps, and (2) a characteristic-based free boundary treatment for the top and side sub-Alfvénic boundary surfaces. We simulate the temporal evolution of AR 11158 over 16 hr for testing, using Solar Dynamics Observatory/Helioseismic Magnetic Imager vector magnetic field observation data and our time-dependent three-dimensional MHD simulation with these two features. Despite several assumptions in calculating the electric field and compromises for mitigating computational difficulties at the very low beta regime, several features of the AR were reasonably retrieved, such as twisting field structures, energy accumulation comparable to an X-class flare, and sudden changes at the time of the X-flare. The present MHD model can be a first step toward more realistic modeling of AR in the future.

Initial Results from the Vector Electric Field Investigation on the C/NOFS Satellite

NASA Technical Reports Server (NTRS)

Pfaff, R.; Rowland, D.; Acuna, M.; Le, G.; Farrell, W.; Holzworth, R.; Wilson, G.; Burke, W.; Freudenreich, H.; Bromund, K.;

Altered orientation and flight paths of pigeons reared on gravity anomalies: a GPS tracking study.

PubMed

Blaser, Nicole; Guskov, Sergei I; Meskenaite, Virginia; Kanevskyi, Valerii A; Lipp, Hans-Peter

2013-01-01

The mechanisms of pigeon homing are still not understood, in particular how they determine their position at unfamiliar locations. The "gravity vector" theory holds that pigeons memorize the gravity vector at their home loft and deduct home direction and distance from the angular difference between memorized and actual gravity vector. However, the gravity vector is tilted by different densities in the earth crust leading to gravity anomalies. We predicted that pigeons reared on different gravity anomalies would show different initial orientation and also show changes in their flight path when crossing a gravity anomaly. We reared one group of pigeons in a strong gravity anomaly with a north-to-south gravity gradient, and the other group of pigeons in a normal area but on a spot with a strong local anomaly with a west-to-east gravity gradient. After training over shorter distances, pigeons were released from a gravitationally and geomagnetically normal site 50 km north in the same direction for both home lofts. As expected by the theory, the two groups of pigeons showed divergent initial orientation. In addition, some of the GPS-tracked pigeons also showed changes in their flight paths when crossing gravity anomalies. We conclude that even small local gravity anomalies at the birth place of pigeons may have the potential to bias the map sense of pigeons, while reactivity to gravity gradients during flight was variable and appeared to depend on individual navigational strategies and frequency of position updates.

Rotating magnetizations in electrical machines: Measurements and modeling

NASA Astrophysics Data System (ADS)

Thul, Andreas; Steentjes, Simon; Schauerte, Benedikt; Klimczyk, Piotr; Denke, Patrick; Hameyer, Kay

2018-05-01

This paper studies the magnetization process in electrical steel sheets for rotational magnetizations as they occur in the magnetic circuit of electrical machines. A four-pole rotational single sheet tester is used to generate the rotating magnetic flux inside the sample. A field-oriented control scheme is implemented to improve the control performance. The magnetization process of different non-oriented materials is analyzed and compared.

Vector-beam solutions of Maxwell's wave equation.

PubMed

Hall, D G

1996-01-01

The Hermite-Gauss and Laguerre-Gauss modes are well-known beam solutions of the scalar Helmholtz equation in the paraxial limit. As such, they describe linearly polarized fields or single Cartesian components of vector fields. The vector wave equation admits, in the paraxial limit, of a family of localized Bessel-Gauss beam solutions that can describe the entire transverse electric field. Two recently reported solutions are members of this family of vector Bessel-Gauss beam modes.

High speed flux feedback for tuning a universal field oriented controller capable of operating in direct and indirect field orientation modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Doncker, Rik W. A. A.

The direct (d) and quadrature (q) components of flux, as sensed by flux sensors or determined from voltage and current measurements in a direct field orientation scheme, are processed rapidly and accurately to provide flux amplitude and angular position values for use by the vector rotator of a universal field-oriented (UFO) controller. Flux amplitude (linear or squared) is provided as feedback to tune the UFO controller for operation in direct and indirect field orientation modes and enables smooth transitions from one mode to the other.

High speed flux feedback for tuning a universal field oriented controller capable of operating in direct and indirect field orientation modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Doncker, R.W.A.A.

The direct (d) and quadrature (q) components of flux, as sensed by flux sensors or determined from voltage and current measurements in a direct field orientation scheme, are processed rapidly and accurately to provide flux amplitude and angular position values for use by the vector rotator of a universal field-oriented (UFO) controller. Flux amplitude (linear or squared) is provided as feedback to tune the UFO controller for operation in direct and indirect field orientation modes and enables smooth transitions from one mode to the other. 3 figs.

High speed flux feedback for tuning a universal field oriented controller capable of operating in direct and indirect field orientation modes

DOEpatents

De Doncker, R.W.A.A.

1992-09-01

The direct (d) and quadrature (q) components of flux, as sensed by flux sensors or determined from voltage and current measurements in a direct field orientation scheme, are processed rapidly and accurately to provide flux amplitude and angular position values for use by the vector rotator of a universal field-oriented (UFO) controller. Flux amplitude (linear or squared) is provided as feedback to tune the UFO controller for operation in direct and indirect field orientation modes and enables smooth transitions from one mode to the other. 3 figs.

New Method for Solving Inductive Electric Fields in the Ionosphere

NASA Astrophysics Data System (ADS)

Vanhamäki, H.

2005-12-01

We present a new method for calculating inductive electric fields in the ionosphere. It is well established that on large scales the ionospheric electric field is a potential field. This is understandable, since the temporal variations of large scale current systems are generally quite slow, in the timescales of several minutes, so inductive effects should be small. However, studies of Alfven wave reflection have indicated that in some situations inductive phenomena could well play a significant role in the reflection process, and thus modify the nature of ionosphere-magnetosphere coupling. The input to our calculation method are the time series of the potential part of the ionospheric electric field together with the Hall and Pedersen conductances. The output is the time series of the induced rotational part of the ionospheric electric field. The calculation method works in the time-domain and can be used with non-uniform, time-dependent conductances. In addition no particular symmetry requirements are imposed on the input potential electric field. The presented method makes use of special non-local vector basis functions called Cartesian Elementary Current Systems (CECS). This vector basis offers a convenient way of representing curl-free and divergence-free parts of 2-dimensional vector fields and makes it possible to solve the induction problem using simple linear algebra. The new calculation method is validated by comparing it with previously published results for Alfven wave reflection from uniformly conducting ionosphere.

Implicit, nonswitching, vector-oriented algorithm for steady transonic flow

NASA Technical Reports Server (NTRS)

Lottati, I.

1983-01-01

A rapid computation of a sequence of transonic flow solutions has to be performed in many areas of aerodynamic technology. The employment of low-cost vector array processors makes the conduction of such calculations economically feasible. However, for a full utilization of the new hardware, the developed algorithms must take advantage of the special characteristics of the vector array processor. The present investigation has the objective to develop an efficient algorithm for solving transonic flow problems governed by mixed partial differential equations on an array processor.

Comparison between measured and computed magnetic flux density distribution of simulated transformer core joints assembled from grain-oriented and non-oriented electrical steel

NASA Astrophysics Data System (ADS)

Shahrouzi, Hamid; Moses, Anthony J.; Anderson, Philip I.; Li, Guobao; Hu, Zhuochao

2018-04-01

The flux distribution in an overlapped linear joint constructed in the central region of an Epstein Square was studied experimentally and results compared with those obtained using a computational magnetic field solver. High permeability grain-oriented (GO) and low permeability non-oriented (NO) electrical steels were compared at a nominal core flux density of 1.60 T at 50 Hz. It was found that the experimental results only agreed well at flux densities at which the reluctance of different paths of the flux are similar. Also it was revealed that the flux becomes more uniform when the working point of the electrical steel is close to the knee point of the B-H curve of the steel.

Evaluation of the influence of electric nets on the behaviour of oviposition site seeking Anopheles gambiae s.s

PubMed Central

2014-01-01

Background Electric nets (e-nets) are used to analyse the flight behaviour of insects and have been used extensively to study the host-oriented flight of tsetse flies. Recently we adapted this tool to analyse the oviposition behaviour of gravid malaria vectors, Anopheles gambiae s.s., orienting towards aquatic habitats and traps by surrounding an artificial pond with e-nets and collecting electrocuted mosquitoes on sticky boards on the ground next to the nets. Here we study whether e-nets themselves affect the responses of gravid An. gambiae s.s.. Methods Dual-choice experiments were carried out in 80 m2 screened semi-field systems where 200 gravid An. gambiae s.s. were released each night for 12 nights per experiment. The numbers of mosquito landing on or approaching an oviposition site were studied by adding detergent to the water in an artificial pond or surrounding the pond with a square of e-nets. We also assessed whether the supporting framework of the nets or the sticky boards used to retain electrocuted mosquitoes influenced the catch. Results Two similar detergent treated ponds presented in choice tests caught an equal proportion of the mosquitoes released, whereas a pond surrounded by e-nets caught a higher proportion than an open pond (odds ratio (OR) 1.7, 95% confidence interval (CI) 1.1 - 2.7; p < 0.017). The separate evaluation of the impact of the square of electric nets and the yellow boards on the approach of gravid females towards a pond suggests that the tower-like construction of the square of electric nets did not restrict the approach of females but the yellow sticky boards on the ground attract gravid females to a source of water (OR 2.7 95% CI 1.7 – 4.3; p < 0.001). Conclusion The trapping efficiency of the electric nets is increased when large yellow sticky boards are placed on the ground next to the e-nets to collect electrocuted mosquitoes, possibly because of increased visual contrast to the aquatic habitat. It is therefore important when comparing two treatments that the same trapping device is used in both. The importance of contrast around artificial habitats might be exploited to improve collections of An. gambiae s.s. in gravid traps. PMID:24948354

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moyotl, A.; Rosado, A.; Tavares-Velasco, G.

The magnetic dipole moment and the electric dipole moment of leptons are calculated under the assumption of lepton flavor violation (LFV) induced by spin-1 unparticles with both vector and axial-vector couplings to leptons, including a CP-violating phase. The experimental limits on the muon magnetic dipole moment and LFV process, such as the decay l{sub i}{sup -}{yields}l{sub j}{sup -}l{sub k}{sup -}l{sub k}{sup +}, are then used to constrain the LFV couplings for particular values of the unparticle operator dimension d{sub U} and the unparticle scale {Lambda}{sub U}, assuming that LFV transitions between the tau and muon leptons are dominant. It ismore » found that the current experimental constraints favor a scenario with dominance of the vector couplings over the axial-vector couplings. We also obtain estimates for the electric dipole moments of the electron and the muon, which are well below the experimental values.« less

Plant parasitic and vector nematodes associated with Asiatic and Oriental hybrid lilies.

PubMed

Adekunle, Ojo K; Kulshrestha, Saurabh; Prasad, Ramdeen; Hallan, Vipin; Raikhy, Gaurav; Verma, Neeraj; Ram, Raja; Kumar, Sanjay; Zaidi, A A

2006-02-01

A survey for distribution and abundance of plant parasitic nematodes in fields grown to Lilium in Himachal Pradesh, India at four study sites viz. Nagrota (at 810 m a.s.l.), Palampur (at 1270 m a.s.l.), Sunder Nagar (at 1400 m a.s.l.) and Chail (at 2250 m a.s.l.) was carried out. Moderate (101-500/200 ml soil) to high (501-1000/200 ml soil) populations of phytonematodes including the vectors for plant viruses (Aphelenchoides avenae, Criconemoides spp., Hoplolaimus spp., Longidorus spp., Paratylenchus spp., Pratylenchus spp., Rhabditis spp., Trichodorus spp., Tylenchoryhnchus spp., Tylenchulus spp. and Xiphinema diversicaudatum) were recorded. Mean population of nematodes was positively correlated with pH in all the study sites, negatively correlated with electrical conductivity (EC), percent organic matter (OM%), available potassium (K) and positively correlated with percent carbon (C%), available nitrogen (N) and available phosphorus (P) in all but one study site. The highest incidence of virus-vector nematodes viz. X. diversicaudatum, Longidorus spp. and Trichodorus spp. was recorded at Palampur. Only Strawberry latent ringspot nepovirus (SLRSV) was detected in Lilium cvs. Star Gazer Max and Galeili by Enzyme Linked Immunosorbent Assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR) and in X. diversicaudatum associated with the cultivars by RT-PCR. Cucumis sativus used as bait plants showed SLRSV symptoms after 15 days of nematode inoculation and further SLRSV was again detected by ELISA and RT-PCR in C. sativus plants confirming the transmission of SLRSV by X. diversicaudatum in Lilium.

Arrows as anchors: An analysis of the material features of electric field vector arrows

NASA Astrophysics Data System (ADS)

Gire, Elizabeth; Price, Edward

2014-12-01

Representations in physics possess both physical and conceptual aspects that are fundamentally intertwined and can interact to support or hinder sense making and computation. We use distributed cognition and the theory of conceptual blending with material anchors to interpret the roles of conceptual and material features of representations in students' use of representations for computation. We focus on the vector-arrows representation of electric fields and describe this representation as a conceptual blend of electric field concepts, physical space, and the material features of the representation (i.e., the physical writing and the surface upon which it is drawn). In this representation, spatial extent (e.g., distance on paper) is used to represent both distances in coordinate space and magnitudes of electric field vectors. In conceptual blending theory, this conflation is described as a clash between the input spaces in the blend. We explore the benefits and drawbacks of this clash, as well as other features of this representation. This analysis is illustrated with examples from clinical problem-solving interviews with upper-division physics majors. We see that while these intermediate physics students make a variety of errors using this representation, they also use the geometric features of the representation to add electric field contributions and to organize the problem situation productively.

Contributions of poroelastic-wave potentials to seismoelectromagnetic wavefields and validity of the quasi-static calculation: a view from a borehole model

NASA Astrophysics Data System (ADS)

Guan, Wei; Shi, Peng; Hu, Hengshan

2018-01-01

In this study, we theoretically analyse the contributions of the four poroelastic-wave potentials to seismoelectromagnetic (SEM) wavefields, verify the validity of the quasi-static calculation of the electric field and provide a method to calculate the magnetic field by using the curl-free electric field. Calculations show that both the fast and slow P waves and the SH and SV waves have non-negligible contributions to the SEM fields. The S waves have indirect contribution to the electric field through the EM conversion from the magnetic field, although the direct contribution due to streaming current is negligible if EM wavenumbers are much smaller than those of the S waves. The P waves have indirect contribution to the magnetic field through EM conversion from the electric field, although the direct contribution is absent. The quasi-static calculation of the electric field is practicable since it is normally satisfied in reality that the EM wavenumbers are much smaller than those of poroelastic waves. While the direct contribution of the S waves and the higher-order EM conversions are ignored, the first-order EM conversion from the S-wave-induced magnetic field is reserved through the continuity of the electric-current density. To calculate the magnetic field on this basis, we separate the quasi-static electric field into a rotational and an irrotational part. The magnetic-field solutions are derived through Hertz vectors in which the coefficients of the magnetic Hertz vector are determined from the magnetic-field continuities and those of the electric Hertz vector originate from the irrotational part of the quasi-static electric field.

Coherent anti-Stokes Raman scattering under electric field stimulation

NASA Astrophysics Data System (ADS)

Capitaine, Erwan; Ould Moussa, Nawel; Louot, Christophe; Lefort, Claire; Pagnoux, Dominique; Duclère, Jean-René; Kaneyasu, Junya F.; Kano, Hideaki; Duponchel, Ludovic; Couderc, Vincent; Leproux, Philippe

2016-12-01

We introduce an experiment using electro-CARS, an electro-optical method based on the combination of ultrabroadband multiplex coherent anti-Stokes Raman scattering (M-CARS) spectroscopy and electric field stimulation. We demonstrate that this method can effectively discriminate the resonant CARS signal from the nonresonant background owing to a phenomenon of molecular orientation in the sample medium. Such molecular orientation is intrinsically related to the induction of an electric dipole moment by the applied static electric field. Evidence of the electro-CARS effect is obtained with a solution of n -alkanes (CnH2 n +2 , 15 ≤n ≤40 ), for which an enhancement of the CARS signal-to-noise ratio is achieved in the case of CH2 and CH3 symmetric/asymmetric stretching vibrations. Additionally, an electric-field-induced second-harmonic generation experiment is performed in order to corroborate the orientational organization of molecules due to the electric field excitation. Finally, we use a simple mathematical approach to compare the vibrational information extracted from electro-CARS measurements with spontaneous Raman data and to highlight the impact of electric stimulation on the vibrational signal.

High Power Microwaves (HPM) (les Micro-ondes de forte puissance (MFP).

DTIC Science & Technology

1995-03-01

the polarization vector , [C/m 2], P1 is the polarization term which is linearly dependent on the electric field, and Pnl is The soliton laser [35...which utilizes Kerr nonlinearity in the polarization vector which is nonlinearly dependent on the optical fiber, has also been demonstrated. In the case...forward propa- then applied across the cathode. If the electric gating volume harmonics of the TMO1 mode, field is of the proper polarity , a phase tran- as

Split Octonion Reformulation for Electromagnetic Chiral Media of Massive Dyons

NASA Astrophysics Data System (ADS)

Chanyal, B. C.

2017-12-01

In an explicit, unified, and covariant formulation of an octonion algebra, we study and generalize the electromagnetic chiral fields equations of massive dyons with the split octonionic representation. Starting with 2×2 Zorn’s vector matrix realization of split-octonion and its dual Euclidean spaces, we represent the unified structure of split octonionic electric and magnetic induction vectors for chiral media. As such, in present paper, we describe the chiral parameter and pairing constants in terms of split octonionic matrix representation of Drude-Born-Fedorov constitutive relations. We have expressed a split octonionic electromagnetic field vector for chiral media, which exhibits the unified field structure of electric and magnetic chiral fields of dyons. The beauty of split octonionic representation of Zorn vector matrix realization is that, the every scalar and vector components have its own meaning in the generalized chiral electromagnetism of dyons. Correspondingly, we obtained the alternative form of generalized Proca-Maxwell’s equations of massive dyons in chiral media. Furthermore, the continuity equations, Poynting theorem and wave propagation for generalized electromagnetic fields of chiral media of massive dyons are established by split octonionic form of Zorn vector matrix algebra.

Pinning, rotation, and metastability of BiFeO 3 cycloidal domains in a magnetic field

DOE PAGES

Fishman, Randy S.

2018-01-03

Earlier models for the room-temperature multiferroic BiFeO 3 implicitly assumed that a very strong anisotropy restricts the domain wave vectors q to the threefold-symmetric axis normal to the static polarization P. However, recent measurements demonstrate that the domain wave vectors q rotate within the hexagonal plane normal to P away from the magnetic field orientation m. In this paper, we show that the previously neglected threefold anisotropy K 3 restricts the wave vectors to lie along the threefold axis in zero field. Taking m to lie along a threefold axis, the domain with q parallel to m remains metastable belowmore » B c1≈7 T. Due to the pinning of domains by nonmagnetic impurities, the wave vectors of the other two domains start to rotate away from m above 5.6 T, when the component of the torque τ=M×B along P exceeds a threshold value τ pin. Since τ=0 when m⊥q, the wave vectors of those domains never become completely perpendicular to the magnetic field. Our results explain recent measurements of the critical field as a function of field orientation, small-angle neutron scattering measurements of the wave vectors, as well as spectroscopic measurements with m along a threefold axis. Finally, the model developed in this paper also explains how the three multiferroic domains of BiFeO 3 for a fixed P can be manipulated by a magnetic field.« less

Pinning, rotation, and metastability of BiFeO3 cycloidal domains in a magnetic field

NASA Astrophysics Data System (ADS)

Fishman, Randy S.

2018-01-01

Earlier models for the room-temperature multiferroic BiFeO3 implicitly assumed that a very strong anisotropy restricts the domain wave vectors q to the threefold-symmetric axis normal to the static polarization P . However, recent measurements demonstrate that the domain wave vectors q rotate within the hexagonal plane normal to P away from the magnetic field orientation m . We show that the previously neglected threefold anisotropy K3 restricts the wave vectors to lie along the threefold axis in zero field. Taking m to lie along a threefold axis, the domain with q parallel to m remains metastable below Bc 1≈7 T. Due to the pinning of domains by nonmagnetic impurities, the wave vectors of the other two domains start to rotate away from m above 5.6 T, when the component of the torque τ =M ×B along P exceeds a threshold value τpin. Since τ =0 when m ⊥q , the wave vectors of those domains never become completely perpendicular to the magnetic field. Our results explain recent measurements of the critical field as a function of field orientation, small-angle neutron scattering measurements of the wave vectors, as well as spectroscopic measurements with m along a threefold axis. The model developed in this paper also explains how the three multiferroic domains of BiFeO3 for a fixed P can be manipulated by a magnetic field.

Pinning, rotation, and metastability of BiFeO 3 cycloidal domains in a magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fishman, Randy S.

Earlier models for the room-temperature multiferroic BiFeO 3 implicitly assumed that a very strong anisotropy restricts the domain wave vectors q to the threefold-symmetric axis normal to the static polarization P. However, recent measurements demonstrate that the domain wave vectors q rotate within the hexagonal plane normal to P away from the magnetic field orientation m. In this paper, we show that the previously neglected threefold anisotropy K 3 restricts the wave vectors to lie along the threefold axis in zero field. Taking m to lie along a threefold axis, the domain with q parallel to m remains metastable belowmore » B c1≈7 T. Due to the pinning of domains by nonmagnetic impurities, the wave vectors of the other two domains start to rotate away from m above 5.6 T, when the component of the torque τ=M×B along P exceeds a threshold value τ pin. Since τ=0 when m⊥q, the wave vectors of those domains never become completely perpendicular to the magnetic field. Our results explain recent measurements of the critical field as a function of field orientation, small-angle neutron scattering measurements of the wave vectors, as well as spectroscopic measurements with m along a threefold axis. Finally, the model developed in this paper also explains how the three multiferroic domains of BiFeO 3 for a fixed P can be manipulated by a magnetic field.« less

Effects of electric field on thermodynamics and ordering of a dipolar liquid

NASA Astrophysics Data System (ADS)

Johari, G. P.

2016-10-01

We propose that an electric field's role in changing the structural disorder may be investigated by comparing the field-induced entropy decrease, ΔES, against the pressure-induced and cooling-induced entropy decreases, ΔpS and ΔTS, respectively, for the same increase in the dielectric α-relaxation time, Δτα, or in the viscosity. If these three quantities are found to be the same, the change in the number of microstates, Δln Ω = ΔS/R, would be the same whether there is an electric field-induced dipole vector alignment, or not. The available data [S. Samanta and R. Richert, J. Chem. Phys. 142, 044504 (2015)] show that ΔES ≅ ΔpS, and ΔES ≅ ΔTS. We further argue that in the case of conformational disorder without hydrodynamics, as for a flexible molecule's orientationally disordered or plastic crystal, ΔTS would be more negative than ΔES for the same increase in Δτα. For cyclo-octanol plastic crystal, whose octyl-ring would lose some of its dielectrically inactive conformational degrees of freedom on cooling, ΔTS is five-times ΔES. Hence the entropy of such crystals may not be related to their τα, an aspect relevant to certain biopolymer crystals. We also mention other effects of E. The findings are relevant to a number of recent studies on the analysis of the effect of electric field on a liquid's properties. The method can be used to study the role of other entropy-altering variables in liquid crystals and ferromagnetic liquids.

Time-dependent analysis of the mixed-field orientation of molecules without rotational symmetry

NASA Astrophysics Data System (ADS)

Thesing, Linda V.; Küpper, Jochen; González-Férez, Rosario

2017-06-01

We present a theoretical study of the mixed-field orientation of molecules without rotational symmetry. The time-dependent one-dimensional and three-dimensional orientation of a thermal ensemble of 6-chloropyridazine-3-carbonitrile molecules in combined linearly or elliptically polarized laser fields and tilted dc electric fields is computed. The results are in good agreement with recent experimental results of one-dimensional orientation for weak dc electric fields [J. L. Hansen, J. Chem. Phys. 139, 234313 (2013)]. Moreover, they predict that using elliptically polarized laser fields or strong dc fields, three-dimensional orientation is obtained. The field-dressed dynamics of excited rotational states is characterized by highly non-adiabatic effects. We analyze the sources of these non-adiabatic effects and investigate their impact on the mixed-field orientation for different field configurations in mixed-field-orientation experiments.

Analysis of Discontinuities in a Rectangular Waveguide Using Dyadic Green's Function Approach in Conjunction with Method of Moments

NASA Technical Reports Server (NTRS)

Deshpande, M. D.

1997-01-01

The dyadic Green's function for an electric current source placed in a rectangular waveguide is derived using a magnetic vector potential approach. A complete solution for the electric and magnetic fields including the source location is obtained by simple differentiation of the vector potential around the source location. The simple differentiation approach which gives electric and magnetic fields identical to an earlier derivation is overlooked by the earlier workers in the derivation of the dyadic Green's function particularly around the source location. Numerical results obtained using the Green's function approach are compared with the results obtained using the Finite Element Method (FEM).

Electrical Trades. Suggested Basic Course Outline.

ERIC Educational Resources Information Center

Texas A and M Univ., College Station. Vocational Instructional Services.

This course outline is intended to assist vocational instructors in developing and teaching a course in the electrical trades. Addressed in the individual sections of the outline are the following topics: orientation (a course overview, job orientation, safety, first aid, and Vocational Industrial Clubs of America); basic skills (mathematics,…

Tilted Orientation of Photochromic Dyes with Guest-Host Effect of Liquid Crystalline Polymer Matrix for Electrical UV Sensing

PubMed Central

Ranjkesh, Amid; Park, Min-Kyu; Park, Do Hyuk; Park, Ji-Sub; Choi, Jun-Chan; Kim, Sung-Hoon; Kim, Hak-Rin

2015-01-01

We propose a highly oriented photochromic dye film for an ultraviolet (UV)-sensing layer, where spirooxazine (SO) derivatives are aligned with the liquid crystalline UV-curable reactive mesogens (RM) using a guest-host effect. For effective electrical UV sensing with a simple metal-insulator-metal structure, our results show that the UV-induced switchable dipole moment amount of the SO derivatives is high; however, their tilting orientation should be controlled. Compared to the dielectric layer with the nearly planar SO dye orientation, the photochromic dielectric layer with the moderately tilted dye orientation shows more than seven times higher the UV-induced capacitance variation. PMID:26729116

Electromagnetic potential vectors and the Lagrangian of a charged particle

NASA Technical Reports Server (NTRS)

Shebalin, John V.

1992-01-01

Maxwell's equations can be shown to imply the existence of two independent three-dimensional potential vectors. A comparison between the potential vectors and the electric and magnetic field vectors, using a spatial Fourier transformation, reveals six independent potential components but only four independent electromagnetic field components for each mode. Although the electromagnetic fields determined by Maxwell's equations give a complete description of all possible classical electromagnetic phenomena, potential vectors contains more information and allow for a description of such quantum mechanical phenomena as the Aharonov-Bohm effect. A new result is that a charged particle Lagrangian written in terms of potential vectors automatically contains a 'spontaneous symmetry breaking' potential.

Illustrating dynamical symmetries in classical mechanics: The Laplace-Runge-Lenz vector revisited

NASA Astrophysics Data System (ADS)

O'Connell, Ross C.; Jagannathan, Kannan

2003-03-01

The inverse square force law admits a conserved vector that lies in the plane of motion. This vector has been associated with the names of Laplace, Runge, and Lenz, among others. Many workers have explored aspects of the symmetry and degeneracy associated with this vector and with analogous dynamical symmetries. We define a conserved dynamical variable α that characterizes the orientation of the orbit in two-dimensional configuration space for the Kepler problem and an analogous variable β for the isotropic harmonic oscillator. This orbit orientation variable is canonically conjugate to the angular momentum component normal to the plane of motion. We explore the canonical one-parameter group of transformations generated by α(β). Because we have an obvious pair of conserved canonically conjugate variables, it is desirable to use them as a coordinate-momentum pair. In terms of these phase space coordinates, the form of the Hamiltonian is nearly trivial because neither member of the pair can occur explicitly in the Hamiltonian. From these considerations we gain a simple picture of dynamics in phase space. The procedure we use is in the spirit of the Hamilton-Jacobi method.

The contactless detection of local normal transitions in superconducting coils by using Poynting’s vector method

NASA Astrophysics Data System (ADS)

Habu, K.; Kaminohara, S.; Kimoto, T.; Kawagoe, A.; Sumiyoshi, F.; Okamoto, H.

2010-11-01

We have developed a new monitoring system to detect an unusual event in the superconducting coils without direct contact on the coils, using Poynting's vector method. In this system, the potential leads and pickup coils are set around the superconducting coils to measure local electric and magnetic fields, respectively. By measuring the sets of magnetic and electric fields, the Poynting's vectors around the coil can be obtained. An unusual event in the coil can be detected as the result of the change of the Poynting's vector. This system has no risk of the voltage breakdown which may happen with the balance voltage method, because there is no need of direct contacts on the coil windings. In a previous paper, we have demonstrated that our system can detect the normal transitions in the Bi-2223 coil without direct contact on the coil windings by using a small test system. For our system to be applied to practical devices, it is necessary for the early detection of an unusual event in the coils to be able to detect local normal transitions in the coils. The signal voltages of the small sensors to measure local magnetic and electric fields are small. Although the increase in signals of the pickup coils is attained easily by an increase in the number of turns of the pickup coils, an increase in the signals of the potential lead is not easily attained. In this paper, a new method to amplify the signal of local electric fields around the coil is proposed. The validity of the method has been confirmed by measuring local electric fields around the Bi-2223 coil.

The Vector Electric Field Investigation on the C/NOFS Satellite

NASA Technical Reports Server (NTRS)

Pfaff, R.; Acuna, M.; Kujawski, J.; Fourre, R.; Uribe, P.; Hunsaker, F.; Rowland, D.; Le, G.; Farrell, W.; Maynard, N.;

a Robust Descriptor Based on Spatial and Frequency Structural Information for Visible and Thermal Infrared Image Matching

NASA Astrophysics Data System (ADS)

Fu, Z.; Qin, Q.; Wu, C.; Chang, Y.; Luo, B.

2017-09-01

Due to the differences of imaging principles, image matching between visible and thermal infrared images still exist new challenges and difficulties. Inspired by the complementary spatial and frequency information of geometric structural features, a robust descriptor is proposed for visible and thermal infrared images matching. We first divide two different spatial regions to the region around point of interest, using the histogram of oriented magnitudes, which corresponds to the 2-D structural shape information to describe the larger region and the edge oriented histogram to describe the spatial distribution for the smaller region. Then the two vectors are normalized and combined to a higher feature vector. Finally, our proposed descriptor is obtained by applying principal component analysis (PCA) to reduce the dimension of the combined high feature vector to make our descriptor more robust. Experimental results showed that our proposed method was provided with significant improvements in correct matching numbers and obvious advantages by complementing information within spatial and frequency structural information.

Non-singular spherical harmonic expressions of geomagnetic vector and gradient tensor fields in the local north-oriented reference frame

NASA Astrophysics Data System (ADS)

Du, J.; Chen, C.; Lesur, V.; Wang, L.

2015-07-01

General expressions of magnetic vector (MV) and magnetic gradient tensor (MGT) in terms of the first- and second-order derivatives of spherical harmonics at different degrees/orders are relatively complicated and singular at the poles. In this paper, we derived alternative non-singular expressions for the MV, the MGT and also the third-order partial derivatives of the magnetic potential field in the local north-oriented reference frame. Using our newly derived formulae, the magnetic potential, vector and gradient tensor fields and also the third-order partial derivatives of the magnetic potential field at an altitude of 300 km are calculated based on a global lithospheric magnetic field model GRIMM_L120 (GFZ Reference Internal Magnetic Model, version 0.0) with spherical harmonic degrees 16-90. The corresponding results at the poles are discussed and the validity of the derived formulas is verified using the Laplace equation of the magnetic potential field.

Measuring Acetabular Cup Orientation on Antero-Posterior Radiographs of the Hip after Total Hip Arthroplasty with a Vector Arithmetic Radiological Method. Is It Valid and Verified for Daily Clinical Practice?

PubMed

Craiovan, B; Weber, M; Worlicek, M; Schneider, M; Springorum, H R; Zeman, F; Grifka, J; Renkawitz, T

2016-06-01

The aim of this prospective study is to validate a vector arithmetic method for measuring acetabular cup orientation after total hip arthroplasty (THA) and to verify the clinical practice. We measured cup anteversion and inclination of 123 patients after cementless primary THA twice by two examiners on AP pelvic radiographs with a vector arithmetic method and compared with a 3D-CT based reconstruction model within the same radiographic coronal plane. The mean difference between the radiographic and the 3D-CT measurements was - 1.4° ± 3.9° for inclination and 0.8°± 7.9° for anteversion with excellent correlation for inclination (r = 0.81, p < 0.001) and moderate correlation for anteversion (r = 0.65, p < 0.001). The intraclass correlation coefficient for measurements on radiographs ranged from 0.98 (95 %-CI: 0.98; 0.99) for the first observer to 0.94 (95 %-CI: 0.92; 0.96) for the second observer. The interrater reliability was 0.96 (95 %-CI: 0.93; 0.98) for inclination and 0.93 (95 %-CI: 0.85; 0.96) for anteversion. The largest errors in measurements were associated with an extraordinary pelvic tilt. In order to get a valuable measurement for measuring cup position after THA on pelvic radiographs by this vector arithmetic method, there is a need for a correct postoperative ap view, with special regards to the pelvic tilt for the future. • Measuring acetabular cup orientation on anteroposterior radiographs of the hip after THA is a helpful procedure in everyday clinical practice as a first-line imaging modality• CT remains the golden standard to accurately determine acetabular cup position.• Future measuring on radiographs for cup orientation after THA should account for integration of the pelvic tilt in order to maximize the measurement accuracy. Citation Format: • Craiovan B, Weber M, Worlicek M et al. Measuring Acetabular Cup Orientation on Antero-Posterior Radiographs of the Hip after Total Hip Arthroplasty with a Vector Arithmetic Radiological Method. Is It Valid and Verified for Daily Clinical Practice?. Fortschr Röntgenstr 2016; 188: 574 - 581. © Georg Thieme Verlag KG Stuttgart · New York.

Neutron Electric Dipole Moment from Gauge-String Duality.

PubMed

Bartolini, Lorenzo; Bigazzi, Francesco; Bolognesi, Stefano; Cotrone, Aldo L; Manenti, Andrea

2017-03-03

We compute the electric dipole moment of nucleons in the large N_{c} QCD model by Witten, Sakai, and Sugimoto with N_{f}=2 degenerate massive flavors. Baryons in the model are instantonic solitons of an effective five-dimensional action describing the whole tower of mesonic fields. We find that the dipole electromagnetic form factor of the nucleons, induced by a finite topological θ angle, exhibits complete vector meson dominance. We are able to evaluate the contribution of each vector meson to the final result-a small number of modes are relevant to obtain an accurate estimate. Extrapolating the model parameters to real QCD data, the neutron electric dipole moment is evaluated to be d_{n}=1.8×10^{-16}θ e cm. The electric dipole moment of the proton is exactly the opposite.

Electric-field control of spin waves in multiferroic BiFeO3: Theory

NASA Astrophysics Data System (ADS)

de Sousa, Rogério; Rovillain, P.; Gallais, Y.; Sacuto, A.; Méasson, M. A.; Colson, D.; Forget, A.; Bibes, M.; Barthélémy, A.; Cazayous, M.

2011-03-01

Our recent experiment demonstrated gigantic (30%) electric-field tuning of magnon frequencies in multiferroic BiFeO3. We demonstrate that the origin of this effect is related to two linear magnetoelectric interactions that couple the component of electric field perpendicular to the ferroelectric vector to a quadratic form of the Néel vector. We calculate the magnon spectra due to each of these interactions and show that only one of them is consistent with experimental data. At high electric fields, this interaction induces a phase transition to a homogeneous state, and the multi-magnon spectra will fuse into two magnon frequencies. We discuss the possible microscopic mechanisms responsible for this novel interaction and the prospect for applications in magnonics. We acknowledge support from NSERC-Discovery (Canada) and the Agence Nationale pour la Recherche (France).

Dynamic measurement of local displacements within curing resin-based dental composite using optical coherence elastography

NASA Astrophysics Data System (ADS)

Tomlins, Peter H.; Rahman, Mohammed Wahidur; Donnan, Robert S.

2016-04-01

This study aimed to determine the feasibility of using optical coherence elastography to measure internal displacements during the curing phase of a light-activated, resin-based composite material. Displacement vectors were spatially mapped over time within a commercial dental composite. Measurements revealed that the orientation of cure-induced displacement vectors varied spatially in a complex manner; however, each vector showed a systematic evolution with time. Precision of individual displacements was estimated to be ˜1 to 2 μm, enabling submicrometer time-varying displacements to be detected.

Effect of ac electric field on the dynamics of a vesicle under shear flow in the small deformation regime

NASA Astrophysics Data System (ADS)

Sinha, Kumari Priti; Thaokar, Rochish M.

2018-03-01

Vesicles or biological cells under simultaneous shear and electric field can be encountered in dielectrophoretic devices or designs used for continuous flow electrofusion or electroporation. In this work, the dynamics of a vesicle subjected to simultaneous shear and uniform alternating current (ac) electric field is investigated in the small deformation limit. The coupled equations for vesicle orientation and shape evolution are derived theoretically, and the resulting nonlinear equations are handled numerically to generate relevant phase diagrams that demonstrate the effect of electrical parameters on the different dynamical regimes such as tank treading (TT), vacillating breathing (VB) [called trembling (TR) in this work], and tumbling (TU). It is found that while the electric Mason number (Mn), which represents the relative strength of the electrical forces to the shear forces, promotes the TT regime, the response itself is found to be sensitive to the applied frequency as well as the conductivity ratio. While higher outer conductivity promotes orientation along the flow axis, orientation along the electric field is favored when the inner conductivity is higher. Similarly a switch of orientation from the direction of the electric field to the direction of flow is possible by a mere change of frequency when the outer conductivity is higher. Interestingly, in some cases, a coupling between electric field-induced deformation and shear can result in the system admitting an intermediate TU regime while attaining the TT regime at high Mn. The results could enable designing better dielectrophoretic devices wherein the residence time as well as the dynamical states of the vesicular suspension can be controlled as per the application.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Vishal C.; Gopalakrishnan, Ganesh; Krishnamoorthy, Sriram

The systems resilience research community has developed methods to manually insert additional source-program level assertions to trap errors, and also devised tools to conduct fault injection studies for scalar program codes. In this work, we contribute the first vector oriented LLVM-level fault injector VULFI to help study the effects of faults in vector architectures that are of growing importance, especially for vectorizing loops. Using VULFI, we conduct a resiliency study of nine real-world vector benchmarks using Intel’s AVX and SSE extensions as the target vector instruction sets, and offer the first reported understanding of how faults affect vector instruction sets.more » We take this work further toward automating the insertion of resilience assertions during compilation. This is based on our observation that during intermediate (e.g., LLVM-level) code generation to handle full and partial vectorization, modern compilers exploit (and explicate in their code-documentation) critical invariants. These invariants are turned into error-checking code. We confirm the efficacy of these automatically inserted low-overhead error detectors for vectorized for-loops.« less

Some Specifications for a Computer-Oriented First Course in Electrical Engineering.

ERIC Educational Resources Information Center

Commission on Engineering Education, Washington, DC.

Reported are specifications for a computer-oriented first course in electrical engineering giving new direction to the development of texts and alternative courses of study. Guidelines for choice of topics, a statement of fundamental concepts, pitfalls to avoid, and some sample course outlines are given. The study of circuits through computer…

78 FR 59059 - Grain-Oriented Electrical Steel From China, Czech Republic, Germany, Japan, Korea, Poland, and...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-25

... INTERNATIONAL TRADE COMMISSION [Investigation Nos. 701-TA-505 and 731-TA-1231-1237 (Preliminary)] Grain-Oriented Electrical Steel From China, Czech Republic, Germany, Japan, Korea, Poland, and Russia... Republic, Germany, Japan, Korea, Poland, and Russia that are alleged to be sold in the United States at...

The Effects on Students' Conceptual Understanding of Electric Circuits of Introducing Virtual Manipulatives within a Physical Manipulatives-Oriented Curriculum

ERIC Educational Resources Information Center

Zacharia, Zacharias C.; de Jong, Ton

2014-01-01

This study investigates whether Virtual Manipulatives (VM) within a Physical Manipulatives (PM)-oriented curriculum affect conceptual understanding of electric circuits and related experimentation processes. A pre-post comparison study randomly assigned 194 undergraduates in an introductory physics course to one of five conditions: three…

Orientation of Space Station Freedom electrical power system in environmental effects assessment

NASA Technical Reports Server (NTRS)

Lu, Cheng-Yi

1990-01-01

The orientation effects of six Space Station Freedom Electrical Power System (EPS) components are evaluated for three environmental interactions: aerodynamic drag, atomic oxygen erosion, and orbital debris impact. Designers can directly apply these orientation factors to estimate the magnitude of the examined environment and the environmental effects for the EPS component of interest. The six EPS components are the solar array, photovoltaic module radiator, integrated equipment assembly, solar dynamic concentrator, solar dynamic radiator, and beta gimbal.

Reduction, Analysis, and Properties of Electric Current Systems in Solar Active Regions

NASA Technical Reports Server (NTRS)

Gary, G. Allen; Demoulin, Pascal

1995-01-01

The specific attraction and, in large part, the significance of solar vector magnetograms lie in the fact that they give the most important data on the electric currents and the nonpotentiality of active regions. Using the vector magnetograms from the Marshall Space Flight Center (MSFC), we employ a unique technique in the area of data analysis for resolving the 180 degree ambiguity in order to calculate the spatial structure of the vertical electric current density. The 180 degree ambiguity is resolved by applying concepts from the nonlinear multivariable optimization theory. The technique is shown to be of particular importance in very nonpotential active regions. The characterization of the vertical electric current density for a set of vector magnetograms using this method then gives the spatial scale, locations, and magnitude of these current systems. The method, which employs an intermediate parametric function which covers the magnetogram and which defines the local "preferred" direction, minimizes a specific functional of the observed transverse magnetic field. The specific functional that is successful is the integral of the square of the vertical current density. We find that the vertical electric current densities have common characteristics for the extended bipolar beta gamma delta-regions studied. The largest current systems have j(sub z)'s which maximizes around 30 mA per square meter and have a linear decreasing distribution to a diameter of 30 Mm.

Hemispheric Patterns in Electric Current Helicity of Solar Magnetic Fields During Solar Cycle 24: Results from SOLIS, SDO and Hinode

NASA Astrophysics Data System (ADS)

Gusain, S.

2017-12-01

We study the hemispheric patterns in electric current helicity distribution on the Sun. Magnetic field vector in the photosphere is now routinely measured by variety of instruments. SOLIS/VSM of NSO observes full disk Stokes spectra in photospheric lines which are used to derive vector magnetograms. Hinode SP is a space based spectropolarimeter which has the same observable as SOLIS albeit with limited field-of-view (FOV) but high spatial resolution. SDO/HMI derives vector magnetograms from full disk Stokes measurements, with rather limited spectral resolution, from space in a different photospheric line. Further, these datasets now exist for several years. SOLIS/VSM from 2003, Hinode SP from 2006, and SDO HMI since 2010. Using these time series of vector magnetograms we compute the electric current density in active regions during solar cycle 24 and study the hemispheric distributions. Many studies show that the helicity parameters and proxies show a strong hemispheric bias, such that Northern hemisphere has preferentially negative and southern positive helicity, respectively. We will confirm these results for cycle 24 from three different datasets and evaluate the statistical significance of the hemispheric bias. Further, we discuss the solar cycle variation in the hemispheric helicity pattern during cycle 24 and discuss its implications in terms of solar dynamo models.

LOPES-3D - vectorial measurements of radio emission from cosmic ray induced air showers

NASA Astrophysics Data System (ADS)

Huber, D.; Apel, W. D.; Arteaga-Velázquez, J. C.; Bähren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Chiavassa, A.; Daumiller, K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Fuchs, B.; Fuhrmann, D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer, A.; Huege, T.; Isar, P. G.; Kampert, K.-H.; Kang, D.; Krömer, O.; Kuijpers, J.; Link, K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.; Melissas, M.; Morello, C.; Oehlschläger, J.; Palmieri, N.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle, C.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Schröder, F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.; Zabierowski, J.; Zensus, J. A.

2013-05-01

LOPES-3D is able to measure all three components of the electric field vector of the radio emission from air showers. This allows a better comparison with emission models. The measurement of the vertical component increases the sensitivity to inclined showers. By measuring all three components of the electric field vector LOPES-3D demonstrates by how much the reconstruction accuracy of primary cosmic ray parameters increases. Thus LOPES-3D evaluates the usefulness of vectorial measurements for large scale applications.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dupertuis, M.A.; Proctor, M.; Acklin, B.

Energy balance and reciprocity relations are studied for harmonic inhomogeneous plane waves that are incident upon a stack of continuous absorbing dielectric media that are macroscopically characterized by their electric and magnetic permittivities and their conductivities. New cross terms between parallel electric and parallel magnetic modes are identified in the fully generalized Poynting vector. The symmetry and the relations between the general Fresnel coefficients are investigated in the context of energy balance at the interface. The contributions of the so-called mixed Poynting vector are discussed in detail. In particular a new transfer matrix is introduced for energy fluxes in thin-filmmore » optics based on the Poynting and mixed Poynting vectors. Finally, the study of reciprocity relations leads to a generalization of a theorem of reversibility for conducting and dielectric media. 16 refs.« less

Modeling, analysis, control and design application guidelines of Doubly Fed Induction Generator (DFIG) for wind power applications

NASA Astrophysics Data System (ADS)

Masaud, Tarek

Double Fed Induction Generators (DFIG) has been widely used for the past two decades in large wind farms. However, there are many open-ended problems yet to be solved before they can be implemented in some specific applications. This dissertation deals with the general analysis, modeling, control and applications of the DFIG for large wind farm applications. A detailed "d-q" model of DFIG along with other applications is simulated using the MATLAB/Simulink platform. The simulation results have been discussed in detail in both sub-synchronous and super-synchronous mode of operation. An improved vector control strategy based on the rotor flux oriented vector control has been proposed to control the active power output of the DFIG. The new vector control strategy is compared with the stator flux oriented vector control which is commonly used. It is observed that the new improved vector control method provides a better active power tracking accuracy compare with the stator flux oriented vector control. The behavior of the DFIG -based wind farm under the various grid disturbances is also studied in this dissertation. The implementation of the Flexible AC Transmission System devices (FACTS) to overcome the voltage stability issue for such applications is investigated. The study includes the implementation of both a static synchronous compensator (STATCOM), and the static VAR compensator (SVC) as dynamic reactive power compensators at the point of common coupling to support DFIG-based wind farm during disturbances. Integrating FACTS protect the grid connected DFIG-based wind farm from going offline during and after the disturbances. It is found that the both devices improve the transient performance and therefore helps the wind turbine generator system to remain in service during grid faults. A comparison between the performance of the two devices in terms of the amount of reactive power injected, time response and the application cost has been discussed in this dissertation. Finally, the integration of the battery energy storage system (BESS) into a grid connected DFIG- based wind turbine as a proposed solution to smooth out the output power during wind speed variations is also addressed.

Process for structural geologic analysis of topography and point data

DOEpatents

Eliason, Jay R.; Eliason, Valerie L. C.

1987-01-01

A quantitative method of geologic structural analysis of digital terrain data is described for implementation on a computer. Assuming selected valley segments are controlled by the underlying geologic structure, topographic lows in the terrain data, defining valley bottoms, are detected, filtered and accumulated into a series line segments defining contiguous valleys. The line segments are then vectorized to produce vector segments, defining valley segments, which may be indicative of the underlying geologic structure. Coplanar analysis is performed on vector segment pairs to determine which vectors produce planes which represent underlying geologic structure. Point data such as fracture phenomena which can be related to fracture planes in 3-dimensional space can be analyzed to define common plane orientation and locations. The vectors, points, and planes are displayed in various formats for interpretation.

Finite-Difference Algorithm for Simulating 3D Electromagnetic Wavefields in Conductive Media

NASA Astrophysics Data System (ADS)

Aldridge, D. F.; Bartel, L. C.; Knox, H. A.

2013-12-01

Electromagnetic (EM) wavefields are routinely used in geophysical exploration for detection and characterization of subsurface geological formations of economic interest. Recorded EM signals depend strongly on the current conductivity of geologic media. Hence, they are particularly useful for inferring fluid content of saturated porous bodies. In order to enhance understanding of field-recorded data, we are developing a numerical algorithm for simulating three-dimensional (3D) EM wave propagation and diffusion in heterogeneous conductive materials. Maxwell's equations are combined with isotropic constitutive relations to obtain a set of six, coupled, first-order partial differential equations governing the electric and magnetic vectors. An advantage of this system is that it does not contain spatial derivatives of the three medium parameters electric permittivity, magnetic permeability, and current conductivity. Numerical solution methodology consists of explicit, time-domain finite-differencing on a 3D staggered rectangular grid. Temporal and spatial FD operators have order 2 and N, where N is user-selectable. We use an artificially-large electric permittivity to maximize the FD timestep, and thus reduce execution time. For the low frequencies typically used in geophysical exploration, accuracy is not unduly compromised. Grid boundary reflections are mitigated via convolutional perfectly matched layers (C-PMLs) imposed at the six grid flanks. A shared-memory-parallel code implementation via OpenMP directives enables rapid algorithm execution on a multi-thread computational platform. Good agreement is obtained in comparisons of numerically-generated data with reference solutions. EM wavefields are sourced via point current density and magnetic dipole vectors. Spatially-extended inductive sources (current carrying wire loops) are under development. We are particularly interested in accurate representation of high-conductivity sub-grid-scale features that are common in industrial environments (borehole casing, pipes, railroad tracks). Present efforts are oriented toward calculating the EM responses of these objects via a First Born Approximation approach. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Testing of the Support Vector Machine for Binary-Class Classification

NASA Technical Reports Server (NTRS)

Scholten, Matthew

2011-01-01

The Support Vector Machine is a powerful algorithm, useful in classifying data in to species. The Support Vector Machines implemented in this research were used as classifiers for the final stage in a Multistage Autonomous Target Recognition system. A single kernel SVM known as SVMlight, and a modified version known as a Support Vector Machine with K-Means Clustering were used. These SVM algorithms were tested as classifiers under varying conditions. Image noise levels varied, and the orientation of the targets changed. The classifiers were then optimized to demonstrate their maximum potential as classifiers. Results demonstrate the reliability of SMV as a method for classification. From trial to trial, SVM produces consistent results

Currentless reversal of Néel vector in antiferromagnets

NASA Astrophysics Data System (ADS)

Semenov, Yuriy; Li, Xilai; Kim, Ki Wook

The bias driven perpendicular magnetic anisotropy is a magneto-electric effect that can realize 900 magnetization rotation and even 1800 flip along the easy axis in the ferromagnets with a minimal energy consumption. This study theoretically demonstrates a similar phenomenon of the Néel vector reversal via a short electrical pulse that can mediate perpendicular magnetic anisotropy in the antiferromagnets. The analysis based on the dynamical equations as well as the micromagnetic simulations reveals the important role of the inertial behavior in the antiferromagnets that facilitates the Néel vector to overcome the barrier between two free-energy minima of the bistable states along the easy axis. In contrast to the ferromagnets, this Néel vector reversal does not accompany angular moment transfer to the environment, leading to acceleration in the dynamical response by a few orders of magnitude. Further, a small switching energy requirement of a few attojoules illustrates an added advantage of the phenomenon in low-power spintronic applications.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lebedev, Oleg V.; N.S. Enikolopov Institute of Synthetic Polymer Materials of RAS, Profsoyuznaya st., Moscow, 117393; Kechek’yan, Alexander S.

Electrically conductive oriented polymer nano-composites of different compositions, based on the reactor powder of ultra-high-molecular-weight polyethylene (UHMWPE) with a special morphology, filled with particles of nanostructured graphite (NG), multi-walled carbon nanotubes (MWCNTs), and electrically conductive carbon black (CB), were investigated. Polymer composites were obtained via compaction of the mechanical mixture of the polymer and filler powder, followed by uniaxial deformation of the material under homogeneous shear (HS) conditions (all of the processing stages were conducted at room temperature). Resulted composites possess a high tensile strength, high level of the electrical conductivity and low percolation threshold, owing it to the formationmore » of the segregated conductive structure, The influence of the type of nanosized carbon filler, degree of the deformation under HS condition, temperature and etc. on the electrical conductivity and mechanical properties of strengthened conductive composites oriented under homogeneous shear conditions was investigated. Changes in the electrical conductivity of oriented composite materials during reversible “tension–shrinkage” cycles along the orientation axis direction were studied. A theoretical approach, describing the process of transformation of the conductive system as a response on polymer phase deformation and volume change, was proposed, based on the data received from the analysis of the conductivity behavior during the uniaxial deformation and thermal treatment of composites.« less

Technique for Solving Electrically Small to Large Structures for Broadband Applications

NASA Technical Reports Server (NTRS)

Jandhyala, Vikram; Chowdhury, Indranil

2011-01-01

Fast iterative algorithms are often used for solving Method of Moments (MoM) systems, having a large number of unknowns, to determine current distribution and other parameters. The most commonly used fast methods include the fast multipole method (FMM), the precorrected fast Fourier transform (PFFT), and low-rank QR compression methods. These methods reduce the O(N) memory and time requirements to O(N log N) by compressing the dense MoM system so as to exploit the physics of Green s Function interactions. FFT-based techniques for solving such problems are efficient for spacefilling and uniform structures, but their performance substantially degrades for non-uniformly distributed structures due to the inherent need to employ a uniform global grid. FMM or QR techniques are better suited than FFT techniques; however, neither the FMM nor the QR technique can be used at all frequencies. This method has been developed to efficiently solve for a desired parameter of a system or device that can include both electrically large FMM elements, and electrically small QR elements. The system or device is set up as an oct-tree structure that can include regions of both the FMM type and the QR type. The system is enclosed with a cube at a 0- th level, splitting the cube at the 0-th level into eight child cubes. This forms cubes at a 1st level, recursively repeating the splitting process for cubes at successive levels until a desired number of levels is created. For each cube that is thus formed, neighbor lists and interaction lists are maintained. An iterative solver is then used to determine a first matrix vector product for any electrically large elements as well as a second matrix vector product for any electrically small elements that are included in the structure. These matrix vector products for the electrically large and small elements are combined, and a net delta for a combination of the matrix vector products is determined. The iteration continues until a net delta is obtained that is within the predefined limits. The matrix vector products that were last obtained are used to solve for the desired parameter. The solution for the desired parameter is then presented to a user in a tangible form; for example, on a display.

Random vectors and spatial analysis by geostatistics for geotechnical applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, D.S.

1987-08-01

Geostatistics is extended to the spatial analysis of vector variables by defining the estimation variance and vector variogram in terms of the magnitude of difference vectors. Many random variables in geotechnology are in vectorial terms rather than scalars, and its structural analysis requires those sample variable interpolations to construct and characterize structural models. A better local estimator will result in greater quality of input models; geostatistics can provide such estimators; kriging estimators. The efficiency of geostatistics for vector variables is demonstrated in a case study of rock joint orientations in geological formations. The positive cross-validation encourages application of geostatistics tomore » spatial analysis of random vectors in geoscience as well as various geotechnical fields including optimum site characterization, rock mechanics for mining and civil structures, cavability analysis of block cavings, petroleum engineering, and hydrologic and hydraulic modelings.« less

Double Stokes-Mueller polarimetry in KTP (Potassium Titanyl Phosphate) crystal

NASA Astrophysics Data System (ADS)

Shaji, Chitra; S B, Sruthil Lal; Sharan, Alok

2017-04-01

Ultra-structural properties of material are being probed by Double Stokes-Mueller polarimetry (DSMP) technique. It makes use of higher dimensions of Stokes vector (9 X 1) and Mueller matrix (4 X9) to characterize the nonlinear optical properties of a material. Second harmonic generation (SHG) at 532nm using 1064nm as fundamental cw beam from Nd: YAG laser in type II phase matched KTP (Potassium Titanyl Phosphate) crystal is studied using DSMP. The experimental measurements for determining double Mueller matrix are carried out in the ``Polarization In Polarization Out'' (PIPO) arrangement. Nine input polarization states are incident on the sample and the linear Stokes vector of the emerging light from the sample is measured. The KTP crystal is oriented such that the SHG signal efficiency at the incident horizontal and vertical polarizations is high as compared to diagonal polarization states. The susceptibility tensor components and the phase difference between them at this orientation are determined from the double Mueller matrix elements. These determined values give information regarding the crystal axis orientations. To our knowledge, this is the first report of the use of DSMP technique to determine the crystal orientations of a biaxial crystal.

Exploring the transformation and upgrading of China's economy using electricity consumption data: A VAR-VEC based model

NASA Astrophysics Data System (ADS)

Zhang, Chi; Zhou, Kaile; Yang, Shanlin; Shao, Zhen

2017-05-01

Since the reforming and opening up in 1978, China has experienced a miraculous development. To investigate the transformation and upgrading of China's economy, this study focuses on the relationship between economic growth and electricity consumption of the secondary and tertiary industry in China. This paper captures the dynamic interdependencies among the related variables using a theoretical framework based on a Vector Autoregressive (VAR)-Vector Error Correction (VEC) model. Using the macroeconomic and electricity consumption data, the results show that, for secondary industry, there is only a unidirectional Granger causality from electricity consumption to Gross Domestic Product (GDP) from 1980 to 2000. However, for the tertiary industry, it only occurs that GDP Granger causes electricity consumption from 2001 to 2014. All these conclusions are verified by the impulse response function and variance decomposition. This study has a great significance to reveal the relationship between industrial electricity consumption and the pattern of economic development. Meanwhile, it further suggests that, since China joined the World Trade Organization (WTO) in 2001, the trend of the economic transformation and upgrading has gradually appeared.

Dielectric relaxation analysis of Pb(Zr{sub 0.54},Ti{sub 0.46})O{sub 3} thin films: Electric field dependence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ponchel, F., E-mail: freddy.ponchel@univ-valenciennes.fr; Rémiens, D.; Sama, N.

2014-12-28

350 nm-thick Perovskite PbZr{sub 0.54}Ti{sub 0.46}O{sub 3} (PZT) thin films were deposited on Al{sub 2}O{sub 3} substrates by sputtering with and without an additional 10-nm-thick TiO{sub x} buffer layer. X-ray diffraction patterns showed that in presence of TiO{sub x} buffer layer, PZT film was highly oriented along the (111) direction film, whereas the unbuffered, counterpart was polycrystalline. A full wave electromagnetic analysis using a vector finite element method was performed to determine the tunability and the complex permittivity up to 67 GHz. A comparison between the electromagnetic analysis and Cole-Cole relaxation model was proposed. Through an original study of the relaxation timemore » as a function of the electric field, values, such as 2 ps and 0.6 ps, were estimated for E{sub DC} = 0 kV/cm and 235 kV/cm, respectively, and in both cases (111)-PZT and polycrystalline-PZT. The distribution of relaxation times is found to be larger for (111)-PZT film, which is probably related to the film microstructure.« less

Maximum power extraction under different vector-control schemes and grid-synchronization strategy of a wind-driven Brushless Doubly-Fed Reluctance Generator.

PubMed

Mousa, Mohamed G; Allam, S M; Rashad, Essam M

2018-01-01

This paper proposes an advanced strategy to synchronize the wind-driven Brushless Doubly-Fed Reluctance Generator (BDFRG) to the grid-side terminals. The proposed strategy depends mainly upon determining the electrical angle of the grid voltage, θ v and using the same transformation matrix of both the power winding and grid sides to ensure that the generated power-winding voltage has the same phase-sequence of the grid-side voltage. On the other hand, the paper proposes a vector-control (power-winding flux orientation) technique for maximum wind-power extraction under two schemes summarized as; unity power-factor operation and minimum converter-current. Moreover, a soft-starting method is suggested to avoid the employed converter over-current. The first control scheme is achieved by adjusting the command power-winding reactive power at zero for a unity power-factor operation. However, the second scheme depends on setting the command d-axis control-winding current at zero to maximize the ratio of the generator electromagnetic-torque per the converter current. This enables the system to get a certain command torque under minimum converter current. A sample of the obtained simulation and experimental results is presented to check the effectiveness of the proposed control strategies. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Determination of ground and excited state dipole moments via electronic Stark spectroscopy: 5-methoxyindole

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilke, Josefin; Wilke, Martin; Schmitt, Michael, E-mail: mschmitt@uni-duesseldorf.de

2016-01-28

The dipole moments of the ground and lowest electronically excited singlet state of 5-methoxyindole have been determined by means of optical Stark spectroscopy in a molecular beam. The resulting spectra arise from a superposition of different field configurations, one with the static electric field almost parallel to the polarization of the exciting laser radiation, the other nearly perpendicular. Each field configuration leads to different intensities in the rovibronic spectrum. With an automated evolutionary algorithm approach, the spectra can be fit and the ratio of both field configurations can be determined. A simultaneous fit of two spectra with both field configurationsmore » improved the precision of the dipole moment determination by a factor of two. We find a reduction of the absolute dipole moment from 1.59(3) D to 1.14(6) D upon electronic excitation to the lowest electronically excited singlet state. At the same time, the dipole moment orientation rotates by 54{sup ∘} showing the importance of the determination of the dipole moment components. The dipole moment in the electronic ground state can approximately be obtained from a vector addition of the indole and the methoxy group dipole moments. However, in the electronically excited state, vector addition completely fails to describe the observed dipole moment. Several reasons for this behavior are discussed.« less

Positivity of the universal pairing in 3 dimensions

NASA Astrophysics Data System (ADS)

Calegari, Danny; Freedman, Michael H.; Walker, Kevin

2010-01-01

Associated to a closed, oriented surface S is the complex vector space with basis the set of all compact, oriented 3 -manifolds which it bounds. Gluing along S defines a Hermitian pairing on this space with values in the complex vector space with basis all closed, oriented 3 -manifolds. The main result in this paper is that this pairing is positive, i.e. that the result of pairing a nonzero vector with itself is nonzero. This has bearing on the question of what kinds of topological information can be extracted in principle from unitary (2+1) -dimensional TQFTs. The proof involves the construction of a suitable complexity function c on all closed 3 -manifolds, satisfying a gluing axiom which we call the topological Cauchy-Schwarz inequality, namely that c(AB) le max(c(AA),c(BB)) for all A,B which bound S , with equality if and only if A=B . The complexity function c involves input from many aspects of 3 -manifold topology, and in the process of establishing its key properties we obtain a number of results of independent interest. For example, we show that when two finite-volume hyperbolic 3 -manifolds are glued along an incompressible acylindrical surface, the resulting hyperbolic 3 -manifold has minimal volume only when the gluing can be done along a totally geodesic surface; this generalizes a similar theorem for closed hyperbolic 3 -manifolds due to Agol-Storm-Thurston.

Pestiferous nature, resting sites, aggregation, and host-seeking behavior of the eye fly Siphunculina funicola (Diptera: Chloropidae) in Thailand.

PubMed

Mulla, Mir S; Chansang, Uruyakorn

2007-12-01

Species of eye flies and eye gnats (Diptera: Chloropidae) are severe and persistent pests of man, domestic and wild animals, and potential vectors of pathogens. The species prevailing in the Oriental region belong to the genus Siphunculina, while those in the Neotropic and Nearctic regions belong to Liohippelates and Hippelates. These are small insects of 1-2 mm that feed on wounds, lacerations, scratches, and mucous membranes of man and higher animals. One species, Siphunculina funicola, commonly known as the Oriental eye fly, is considered the most anthropophilic in the genus, with potential involvement in the spread and mechanical transmission of infectious agents to humans and animals. Very little is known about the biology, prevalence, host-seeking, and aggregation behavior of this species in South and Southeast Asia. We initiated studies on biological aspects of this potential vector and human pest in central Thailand. The most significant findings of our study were the aggregation behaviors of S. funicola, that both sexes attack hosts, and that males outnumbered females attacking humans, dogs, and other domestic animals. They feed on wounds, scabs, lacerations, eyes, and mucous membranes. They hover around and feed on hosts during the daylight hours when host-seeking activities are more pronounced at temperatures above 25-27 degrees C under calm conditions. We noted that large masses of males and females aggregated on a variety of hanging objects such as strings, trailings, electrical lines, decorations, ropes, twines, abandoned cob webs, clothes hangers, and other hanging substrates in open shade of structures and dwellings. This behavior of eye flies brings them closer to human and animal hosts. In these aggregations, both males and females were present, with mating pairs frequently noted. In the aggregations, about 37% of the females had fully developed eggs in the rainy season, but only <1-3.6% were gravid in the hot and dry season. The average number of eggs per female was generally 42 to 44.

Crystal orientation dependence of the dielectric properties for epitaxial BaZr0.15Ti0.85O3 thin films

NASA Astrophysics Data System (ADS)

Miao, J.; Yuan, J.; Wu, H.; Yang, S. B.; Xu, B.; Cao, L. X.; Zhao, B. R.

2007-01-01

Epitaxial Ba0.15Zr0.85TiO3 (BZT) ferroelectric thin films with (001), (011), and (111) orientations were, respectively, grown on La0.67Sr0.33MnO3 (LSMO) buffered LaAlO3 substrates by pulsed laser deposition method. The dc electric-field dependence of permittivity and dielectric loss of (001)-, (011)-, and (111)-oriented BZT/LSMO heterostructures obeys the Johnson formula, and the ac electric-field dependence of that obeys the Rayleigh law under the subswitching field region. The anisotropic dielectric properties are attributed to the higher mobility of the charge carriers, the concentration of mobile interfacial domain walls, and boundaries in the (111)-oriental films than in the (110)- and (100)-oriented films.

Connection between the two branches of the quantum two-stream instability across the k space

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bret, A.; Haas, F.

2010-05-15

The stability of two quantum counterstreaming electron beams is investigated within the quantum plasma fluid equations for arbitrarily oriented wave vectors k. The analysis reveals that the two quantum two-stream unstable branches are indeed connected by a continuum of unstable modes with oblique wave vectors. Using the longitudinal approximation, the stability domain for any k is analytically explained, together with the growth rate.

Modulation of an ultraviolet mutational hotspot in a shuttle vector Xeroderma cells.

PubMed Central

Seetharam, S; Seidman, M M

1991-01-01

Ultraviolet mutagenesis of the shuttle vector plasmid pZ189 in Xeroderma Pigmentosum cells yields a mutational pattern marked by hotspots at photoproduct sites on both strands of the supF marker gene. In order to test the influence of strand orientation on the appearance of hotspots the mutagenesis study was repeated on a vector with the supF gene in the inverted orientation. We recovered a pattern the same as that in the earlier work and conclude that the nature of the DNA polymerase involved in the replication of specific strands is not a primary determinant of hotspot occurrence in this system. One of the hotspots lies in an 8 base palindrome while the corresponding site on the other strand was not a hotspot. These results were obtained with calcium phosphate transfection of the UV treated vector. When DEAE dextran was used as a transfection agent both sites in the palindrome were hotspots. In a mixing experiment the calcium phosphate pattern was recovered. Our data suggest that the sequence determinants of mutational probability at these two sites lie outside the 8 bases of the palindrome and that mutagenesis at one, but not the other, site is sensitive to perturbation of cellular calcium levels. PMID:2027767

The Utility of SAR to Monitor Ocean Processes.

DTIC Science & Technology

1981-11-01

echo received from ocean waves include the motion of the a horizontally polarized wave will have its E vector parallel to scattering surfaces, the so...radiation is defined by the direction of the electric field intensity, E, vector . For example, a horizontally polarized wave will have its E vector ...Oil Spill Off the East Coast of the United States ................ .... 55 19. L-band Parallel and Cross Polarized SAR Imagery of Ice in the Beaufort

Electrical remodeling reflected by QRS and T vector changes following cardiac resynchronization therapy is related to survival in heart failure patients with left bundle branch block.

PubMed

Floré, V; Bartunek, J; Goethals, M; Verstreken, S; Timmermans, W; De Pauw, F; Van Bockstal, K; Vanderheyden, M

2015-01-01

We investigated changes in electrocardiographic spatial QRS and T vectors as markers of electrical remodeling before and after cardiac resynchronization therapy (CRT) and their association with altered outcome. In 41 patients with LBBB, ECGpost was recorded during intrinsic rhythm after interrupting CRT pacing and compared to the pre-implant ECGpre and the ECG during CRT (ECGCRT). Mean spatial angles between QRS and T vectors were determined with the Kors matrix conversion. Left ventricular ejection fraction (LVEF) was determined with nuclear isotope ventriculography before CRT implantation (LVEFpre) and at inclusion (LVEFpost). Following CRT, LVEF improved significantly from 26 ± 10 to 36 ± 14% (p=0.01). Duration of QRSpre (168 ± 15 ms) was not different from QRSpost (166 ± 15 ms). A smaller angle between QRSCRT and Tpost was related to a greater angle between Tpre and Tpost (Pearson's R -0.61 - p<0.001). During follow-up (30 ± 2 months) 9 patients (22%) died. Univariate Cox regression revealed higher mortality in the patients with lower LVEFpost (HR 1.10, p=0.01), a larger angle QRSCRTTpost (HR 1.03, p=0.03), a smaller angle QRSpreQRSpost (HR 0.97, p=0.03) and smaller angle TpreTpost (HR 0.95, p<0.01). After adjusting for LVEFpost, only smaller angle TpreTpost was associated with mortality (HR 0.96, p=0.03). Electrical remodeling can be quantified by measuring the angles between spatial QRS and T vectors before, during and after CRT. In absence of QRS duration changes, more extensive electrical remodeling is associated with a significantly better survival. QRS and T vector changes deserve further investigation to better understand the individual response to CRT. Copyright © 2015 Elsevier Inc. All rights reserved.

Introduction to Electrodynamics

NASA Astrophysics Data System (ADS)

Griffiths, David J.

2017-06-01

1. Vector analysis; 2. Electrostatics; 3. Potentials; 4. Electric fields in matter; 5. Magnetostatics; 6. Magnetic fields in matter; 7. Electrodynamics; 8. Conservation laws; 9. Electromagnetic waves; 10. Potentials and fields; 11. Radiation; 12. Electrodynamics and relativity; Appendix A. Vector calculus in curvilinear coordinates; Appendix B. The Helmholtz theorem; Appendix C. Units; Index.

Simplified moment tensor analysis and unified decomposition of acoustic emission source: Application to in situ hydrofracturing test

NASA Astrophysics Data System (ADS)

Ohtsu, Masayasu

1991-04-01

An application of a moment tensor analysis to acoustic emission (AE) is studied to elucidate crack types and orientations of AE sources. In the analysis, simplified treatment is desirable, because hundreds of AE records are obtained from just one experiment and thus sophisticated treatment is realistically cumbersome. Consequently, a moment tensor inversion based on P wave amplitude is employed to determine six independent tensor components. Selecting only P wave portion from the full-space Green's function of homogeneous and isotropic material, a computer code named SiGMA (simplified Green's functions for the moment tensor analysis) is developed for the AE inversion analysis. To classify crack type and to determine crack orientation from moment tensor components, a unified decomposition of eigenvalues into a double-couple (DC) part, a compensated linear vector dipole (CLVD) part, and an isotropic part is proposed. The aim of the decomposition is to determine the proportion of shear contribution (DC) and tensile contribution (CLVD + isotropic) on AE sources and to classify cracks into a crack type of the dominant motion. Crack orientations determined from eigenvectors are presented as crack-opening vectors for tensile cracks and fault motion vectors for shear cracks, instead of stereonets. The SiGMA inversion and the unified decomposition are applied to synthetic data and AE waveforms detected during an in situ hydrofracturing test. To check the accuracy of the procedure, numerical experiments are performed on the synthetic waveforms, including cases with 10% random noise added. Results show reasonable agreement with assumed crack configurations. Although the maximum error is approximately 10% with respect to the ratios, the differences on crack orientations are less than 7°. AE waveforms detected by eight accelerometers deployed during the hydrofracturing test are analyzed. Crack types and orientations determined are in reasonable agreement with a predicted failure plane from borehole TV observation. The results suggest that tensile cracks are generated first at weak seams and then shear cracks follow on the opened joints.

Dissociable cognitive mechanisms underlying human path integration.

PubMed

Wiener, Jan M; Berthoz, Alain; Wolbers, Thomas

2011-01-01

Path integration is a fundamental mechanism of spatial navigation. In non-human species, it is assumed to be an online process in which a homing vector is updated continuously during an outward journey. In contrast, human path integration has been conceptualized as a configural process in which travelers store working memory representations of path segments, with the computation of a homing vector only occurring when required. To resolve this apparent discrepancy, we tested whether humans can employ different path integration strategies in the same task. Using a triangle completion paradigm, participants were instructed either to continuously update the start position during locomotion (continuous strategy) or to remember the shape of the outbound path and to calculate home vectors on basis of this representation (configural strategy). While overall homing accuracy was superior in the configural condition, participants were quicker to respond during continuous updating, strongly suggesting that homing vectors were computed online. Corroborating these findings, we observed reliable differences in head orientation during the outbound path: when participants applied the continuous updating strategy, the head deviated significantly from straight ahead in direction of the start place, which can be interpreted as a continuous motor expression of the homing vector. Head orientation-a novel online measure for path integration-can thus inform about the underlying updating mechanism already during locomotion. In addition to demonstrating that humans can employ different cognitive strategies during path integration, our two-systems view helps to resolve recent controversies regarding the role of the medial temporal lobe in human path integration.

An application of an optimal statistic for characterizing relative orientations

NASA Astrophysics Data System (ADS)

Jow, Dylan L.; Hill, Ryley; Scott, Douglas; Soler, J. D.; Martin, P. G.; Devlin, M. J.; Fissel, L. M.; Poidevin, F.

2018-02-01

We present the projected Rayleigh statistic (PRS), a modification of the classic Rayleigh statistic, as a test for non-uniform relative orientation between two pseudo-vector fields. In the application here, this gives an effective way of investigating whether polarization pseudo-vectors (spin-2 quantities) are preferentially parallel or perpendicular to filaments in the interstellar medium. For example, there are other potential applications in astrophysics, e.g. when comparing small-scale orientations with larger scale shear patterns. We compare the efficiency of the PRS against histogram binning methods that have previously been used for characterizing the relative orientations of gas column density structures with the magnetic field projected on the plane of the sky. We examine data for the Vela C molecular cloud, where the column density is inferred from Herschel submillimetre observations, and the magnetic field from observations by the Balloon-borne Large-Aperture Submillimetre Telescope in the 250-, 350- and 500-μm wavelength bands. We find that the PRS has greater statistical power than approaches that bin the relative orientation angles, as it makes more efficient use of the information contained in the data. In particular, the use of the PRS to test for preferential alignment results in a higher statistical significance, in each of the four Vela C regions, with the greatest increase being by a factor 1.3 in the South-Nest region in the 250 - μ m band.

Extraction and Analysis of Mega Cities’ Impervious Surface on Pixel-based and Object-oriented Support Vector Machine Classification Technology: A case of Bombay

NASA Astrophysics Data System (ADS)

Yu, S. S.; Sun, Z. C.; Sun, L.; Wu, M. F.

2017-02-01

The object of this paper is to study the impervious surface extraction method using remote sensing imagery and monitor the spatiotemporal changing patterns of mega cities. Megacity Bombay was selected as the interesting area. Firstly, the pixel-based and object-oriented support vector machine (SVM) classification methods were used to acquire the land use/land cover (LULC) products of Bombay in 2010. Consequently, the overall accuracy (OA) and overall Kappa (OK) of the pixel-based method were 94.97% and 0.96 with a running time of 78 minutes, the OA and OK of the object-oriented method were 93.72% and 0.94 with a running time of only 17s. Additionally, OA and OK of the object-oriented method after a post-classification were improved up to 95.8% and 0.94. Then, the dynamic impervious surfaces of Bombay in the period 1973-2015 were extracted and the urbanization pattern of Bombay was analysed. Results told that both the two SVM classification methods could accomplish the impervious surface extraction, but the object-oriented method should be a better choice. Urbanization of Bombay experienced a fast extending during the past 42 years, implying a dramatically urban sprawl of mega cities in the developing countries along the One Belt and One Road (OBOR).

Electricity-Electronics Curriculum Guide. Instructional Modules Level II.

ERIC Educational Resources Information Center

California State Dept. of Education, Sacramento. Div. of Vocational Education.

These teacher's materials are for a 24-unit competency-based secondary education course on electricity and electronics designed for California public schools. The 24 units are: (1) an orientation; (2) an introduction to electricity; (3) safety; (4) history of electricity; (5) basic electrical skills; (6) magnetism; (7) the nature of electricity;…

Detection of License Plate using Sliding Window, Histogram of Oriented Gradient, and Support Vector Machines Method

NASA Astrophysics Data System (ADS)

Astawa, INGA; Gusti Ngurah Bagus Caturbawa, I.; Made Sajayasa, I.; Dwi Suta Atmaja, I. Made Ari

2018-01-01

The license plate recognition usually used as part of system such as parking system. License plate detection considered as the most important step in the license plate recognition system. We propose methods that can be used to detect the vehicle plate on mobile phone. In this paper, we used Sliding Window, Histogram of Oriented Gradient (HOG), and Support Vector Machines (SVM) method to license plate detection so it will increase the detection level even though the image is not in a good quality. The image proceed by Sliding Window method in order to find plate position. Feature extraction in every window movement had been done by HOG and SVM method. Good result had shown in this research, which is 96% of accuracy.

Observations on Student Difficulties with Mathematics in Upper-Division Electricity and Magnetism

ERIC Educational Resources Information Center

Pepper, Rachel E.; Chasteen, Stephanie V.; Pollock, Steven J.; Perkins, Katherine K.

2012-01-01

We discuss common difficulties in upper-division electricity and magnetism (E&M) in the areas of Gauss's law, vector calculus, and electric potential using both quantitative and qualitative evidence. We also show that many of these topical difficulties may be tied to student difficulties with mathematics. At the junior level, some students…

The analysis of the quality of the frequency control of induction motor carried out on the basis of the processes in the rotor circuit

NASA Astrophysics Data System (ADS)

Kodkin, V. L.; Anikin, A. S.; Baldenkov, A. A.

2018-01-01

The results of researches of asynchronous electric drives with the frequency control which are carried out for the purpose of establishment of causes and effect relationships between a control method, the implementable standard frequency converter of the Schneider Electric company (ATV-71, ATV-32) and its efficiency are given in article. Tests with asynchronous motors with wound rotor were for the first time carried out. It allowed registering during the experiments the instantaneous values not only the stator currents, but also rotor currents. Authors for the first time applied spectrum analysis of stator and rotor currents, it showed that «sensorless vector» control leads to origin of high-frequency harmonicas with the considerable amplitude and, as a result of they are non-sinusoidal of the created torque and inefficiency of the electric drive. The accelerations that are carried out during the researches to 94, 157 and 251 Rad/s confirmed this feature of vector control that appears incapable to linearize the asynchronous electric drive as it was supposed authors of a method. These results do not contradict theoretical provisions if not to neglect assumptions which usually become in case of an output of the equations of vector control. Unfortunately, the modern researchers do not subject these assumptions to doubts. Continued studies make it possible to create an effective frequency management of asynchronous electric drives required for current technology.

Electrokinetic Control of Viscous Fingering

NASA Astrophysics Data System (ADS)

Mirzadeh, Mohammad; Bazant, Martin Z.

2017-10-01

We present a theory of the interfacial stability of two immiscible electrolytes under the coupled action of pressure gradients and electric fields in a Hele-Shaw cell or porous medium. Mathematically, our theory describes a phenomenon of "vector Laplacian growth," in which the interface moves in response to the gradient of a vector-valued potential function through a generalized mobility tensor. Physically, we extend the classical Saffman-Taylor problem to electrolytes by incorporating electrokinetic (EK) phenomena. A surprising prediction is that viscous fingering can be controlled by varying the injection ratio of electric current to flow rate. Beyond a critical injection ratio, stability depends only upon the relative direction of flow and current, regardless of the viscosity ratio. Possible applications include porous materials processing, electrically enhanced oil recovery, and EK remediation of contaminated soils.

Measurements of rain effects on an 18-GHz dual-polarized propagation link

NASA Technical Reports Server (NTRS)

Bostian, C. W.; Stutzman, W. L.; Wiley, P. H.; Marshall, R. E.

1976-01-01

The paper presents highlights of rain attenuation and depolarization data collected between August 1972 and March 1974 in an experimental setup consisting of a 1.43-km line-of-sight path with 1.22-m diam dual-polarized parabolic reflector antennas at each end. The antennas used question-mark mounted scalar feeds oriented to transmit or receive linearly polarized 17.65-GHz signals having electric field vectors at +45 deg and -45 deg from the vertical. Rain data were collected and analyzed for 24 individual storms in which the rain rate exceeded 10 mm/hr. Received signal levels were sampled once each second and stored by a small digital computer which controlled the experiment and performed preliminary data processing. The results are compared with a theoretical model presented by Wiley et al. (1974). Experimental cross-polarization isolation data are found to agree well with theoretical values, especially at high rain rates where the antenna effects are the least significant.

Landau levels with magnetic tunneling in a Weyl semimetal and magnetoconductance of a ballistic p -n junction

NASA Astrophysics Data System (ADS)

Saykin, D. R.; Tikhonov, K. S.; Rodionov, Ya. I.

2018-01-01

We study the Landau levels (LLs) of a Weyl semimetal with two adjacent Weyl nodes. We consider different orientations η =∠ (B ,k0) of magnetic field B with respect to k0, the vector of Weyl node splitting. A magnetic field facilitates the tunneling between the nodes, giving rise to a gap in the transverse energy of the zeroth LL. We show how the spectrum is rearranged at different η and how this manifests itself in the change of behavior of the differential magnetoconductance d G (B )/d B of a ballistic p -n junction. Unlike the single-cone model where Klein tunneling reveals itself in positive d G (B )/d B , in the two-cone case, G (B ) is nonmonotonic with a maximum at Bc∝Φ0k02/ln(k0lE) for large k0lE , where lE=√{ℏ v /|e |E } , with E for the built-in electric field and Φ0 for the magnetic flux quantum.

Microwave absorbing property of silicone rubber composites with added carbonyl iron particles and graphite platelet

NASA Astrophysics Data System (ADS)

Xu, Yonggang; Zhang, Deyuan; Cai, Jun; Yuan, Liming; Zhang, Wenqiang

2013-02-01

Silicone rubber composites filled with carbonyl iron particles (CIPs) and graphite platelet (GP) were prepared using non-coating or coating processes. The complex permittivity and permeability of the composites were measured using a vector network analyzer in the frequency range of 1-18 GHz and dc electric conductivity was measured by the standard four-point contact method. The results showed that CIPs/GP composites fabricated in the coating process had the highest permittivity and permeability due to the particle orientation and interactions between the two absorbents. The coating process resulted in a decreased effective eccentricity of the absorbents, and the dc conductivity increased according to Neelakanta's equations. The reflection loss (RL) value showed that the composites had an excellent absorbing property in the L-band, minimum -11.85 dB at 1.5 mm and -15.02 dB at 2 mm. Thus, GP could be an effective additive in preparing thin absorbing composites in the L-band.

Introduction to power-frequency electric and magnetic fields.

PubMed Central

Kaune, W T

1993-01-01

This paper introduces the reader to electric and magnetic fields, particularly those fields produced by electric power systems and other sources using frequencies in the power-frequency range. Electric fields are produced by electric charges; a magnetic field also is produced if these charges are in motion. Electric fields exert forces on other charges; if in motion, these charges will experience magnetic forces. Power-frequency electric and magnetic fields induce electric currents in conducting bodies such as living organisms. The current density vector is used to describe the distribution of current within a body. The surface of the human body is an excellent shield for power-frequency electric fields, but power-frequency magnetic fields penetrate without significant attenuation; the electric fields induced inside the body by either exposure are comparable in magnitude. Electric fields induced inside a human by most environmental electric and magnetic fields appear to be small in magnitude compared to levels naturally occurring in living tissues. Detection of such fields thus would seem to require the existence of unknown biological mechanisms. Complete characterization of a power-frequency field requires measurement of the magnitudes and electrical phases of the fundamental and harmonic amplitudes of its three vector components. Most available instrumentation measures only a small subset, or some weighted average, of these quantities. Hand-held survey meters have been used widely to measure power-frequency electric and magnetic fields. Automated data-acquisition systems have come into use more recently to make electric- and magnetic-field recordings, covering periods of hours to days, in residences and other environments.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8206045

Applying machine learning methods for characterization of hexagonal prisms from their 2D scattering patterns - an investigation using modelled scattering data

NASA Astrophysics Data System (ADS)

Salawu, Emmanuel Oluwatobi; Hesse, Evelyn; Stopford, Chris; Davey, Neil; Sun, Yi

2017-11-01

Better understanding and characterization of cloud particles, whose properties and distributions affect climate and weather, are essential for the understanding of present climate and climate change. Since imaging cloud probes have limitations of optical resolution, especially for small particles (with diameter < 25 μm), instruments like the Small Ice Detector (SID) probes, which capture high-resolution spatial light scattering patterns from individual particles down to 1 μm in size, have been developed. In this work, we have proposed a method using Machine Learning techniques to estimate simulated particles' orientation-averaged projected sizes (PAD) and aspect ratio from their 2D scattering patterns. The two-dimensional light scattering patterns (2DLSP) of hexagonal prisms are computed using the Ray Tracing with Diffraction on Facets (RTDF) model. The 2DLSP cover the same angular range as the SID probes. We generated 2DLSP for 162 hexagonal prisms at 133 orientations for each. In a first step, the 2DLSP were transformed into rotation-invariant Zernike moments (ZMs), which are particularly suitable for analyses of pattern symmetry. Then we used ZMs, summed intensities, and root mean square contrast as inputs to the advanced Machine Learning methods. We created one random forests classifier for predicting prism orientation, 133 orientation-specific (OS) support vector classification models for predicting the prism aspect-ratios, 133 OS support vector regression models for estimating prism sizes, and another 133 OS Support Vector Regression (SVR) models for estimating the size PADs. We have achieved a high accuracy of 0.99 in predicting prism aspect ratios, and a low value of normalized mean square error of 0.004 for estimating the particle's size and size PADs.

Extracting Time-Accurate Acceleration Vectors From Nontrivial Accelerometer Arrangements.

PubMed

Franck, Jennifer A; Blume, Janet; Crisco, Joseph J; Franck, Christian

2015-09-01

Sports-related concussions are of significant concern in many impact sports, and their detection relies on accurate measurements of the head kinematics during impact. Among the most prevalent recording technologies are videography, and more recently, the use of single-axis accelerometers mounted in a helmet, such as the HIT system. Successful extraction of the linear and angular impact accelerations depends on an accurate analysis methodology governed by the equations of motion. Current algorithms are able to estimate the magnitude of acceleration and hit location, but make assumptions about the hit orientation and are often limited in the position and/or orientation of the accelerometers. The newly formulated algorithm presented in this manuscript accurately extracts the full linear and rotational acceleration vectors from a broad arrangement of six single-axis accelerometers directly from the governing set of kinematic equations. The new formulation linearizes the nonlinear centripetal acceleration term with a finite-difference approximation and provides a fast and accurate solution for all six components of acceleration over long time periods (>250 ms). The approximation of the nonlinear centripetal acceleration term provides an accurate computation of the rotational velocity as a function of time and allows for reconstruction of a multiple-impact signal. Furthermore, the algorithm determines the impact location and orientation and can distinguish between glancing, high rotational velocity impacts, or direct impacts through the center of mass. Results are shown for ten simulated impact locations on a headform geometry computed with three different accelerometer configurations in varying degrees of signal noise. Since the algorithm does not require simplifications of the actual impacted geometry, the impact vector, or a specific arrangement of accelerometer orientations, it can be easily applied to many impact investigations in which accurate kinematics need to be extracted from single-axis accelerometer data.

Correlated Topic Vector for Scene Classification.

PubMed

Wei, Pengxu; Qin, Fei; Wan, Fang; Zhu, Yi; Jiao, Jianbin; Ye, Qixiang

2017-07-01

Scene images usually involve semantic correlations, particularly when considering large-scale image data sets. This paper proposes a novel generative image representation, correlated topic vector, to model such semantic correlations. Oriented from the correlated topic model, correlated topic vector intends to naturally utilize the correlations among topics, which are seldom considered in the conventional feature encoding, e.g., Fisher vector, but do exist in scene images. It is expected that the involvement of correlations can increase the discriminative capability of the learned generative model and consequently improve the recognition accuracy. Incorporated with the Fisher kernel method, correlated topic vector inherits the advantages of Fisher vector. The contributions to the topics of visual words have been further employed by incorporating the Fisher kernel framework to indicate the differences among scenes. Combined with the deep convolutional neural network (CNN) features and Gibbs sampling solution, correlated topic vector shows great potential when processing large-scale and complex scene image data sets. Experiments on two scene image data sets demonstrate that correlated topic vector improves significantly the deep CNN features, and outperforms existing Fisher kernel-based features.

Fabrication of field-effect transistor utilizing oriented thin film of octahexyl-substituted phthalocyanine and its electrical anisotropy based on columnar structure

NASA Astrophysics Data System (ADS)

Ohmori, Masashi; Nakatani, Mitsuhiro; Kajii, Hirotake; Miyamoto, Ayano; Yoneya, Makoto; Fujii, Akihiko; Ozaki, Masanori

2018-03-01

Field-effect transistors with molecularly oriented thin films of metal-free non-peripherally octahexyl-substituted phthalocyanine (C6PcH2), which characteristically form a columnar structure, have been fabricated, and the electrical anisotropy of C6PcH2 has been investigated. The molecularly oriented thin films of C6PcH2 were prepared by the bar-coating technique, and the uniform orientation in a large area and the surface roughness at a molecular level were observed by polarized spectroscopy and atomic force microscopy, respectively. The field effect mobilities parallel and perpendicular to the column axis of C6PcH2 were estimated to be (1.54 ± 0.24) × 10-2 and (2.10 ± 0.23) × 10-3 cm2 V-1 s-1, respectively. The electrical anisotropy based on the columnar structure has been discussed by taking the simulated results obtained by density functional theory calculation into consideration.

Electrical control of optical orientation of neutral and negatively charged excitons in an n -type semiconductor quantum well

NASA Astrophysics Data System (ADS)

Dzhioev, R. I.; Korenev, V. L.; Lazarev, M. V.; Sapega, V. F.; Gammon, D.; Bracker, A. S.

2007-01-01

We report electric field induced increase of spin orientation of negatively charged excitons (trions) localized in n -type GaAs/AlGaAs quantum well. Under resonant excitation of free neutral heavy-hole excitons, the polarization of trions increases dramatically with electrical injection of electrons. The polarization enhancement correlates strongly with trion/exciton luminescence intensity ratio. This effect results from a very efficient trapping of free neutral excitons by the quantum well interfacial fluctuations (“natural” quantum dots) containing resident electrons.

Determining polarizable force fields with electrostatic potentials from quantum mechanical linear response theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Hao; Yang, Weitao, E-mail: weitao.yang@duke.edu; Department of Physics, Duke University, Durham, North Carolina 27708

We developed a new method to calculate the atomic polarizabilities by fitting to the electrostatic potentials (ESPs) obtained from quantum mechanical (QM) calculations within the linear response theory. This parallels the conventional approach of fitting atomic charges based on electrostatic potentials from the electron density. Our ESP fitting is combined with the induced dipole model under the perturbation of uniform external electric fields of all orientations. QM calculations for the linear response to the external electric fields are used as input, fully consistent with the induced dipole model, which itself is a linear response model. The orientation of the uniformmore » external electric fields is integrated in all directions. The integration of orientation and QM linear response calculations together makes the fitting results independent of the orientations and magnitudes of the uniform external electric fields applied. Another advantage of our method is that QM calculation is only needed once, in contrast to the conventional approach, where many QM calculations are needed for many different applied electric fields. The molecular polarizabilities obtained from our method show comparable accuracy with those from fitting directly to the experimental or theoretical molecular polarizabilities. Since ESP is directly fitted, atomic polarizabilities obtained from our method are expected to reproduce the electrostatic interactions better. Our method was used to calculate both transferable atomic polarizabilities for polarizable molecular mechanics’ force fields and nontransferable molecule-specific atomic polarizabilities.« less

Texture and anisotropy in ferroelectric lead metaniobate

NASA Astrophysics Data System (ADS)

Iverson, Benjamin John

Ferroelectric lead metaniobate, PbNb2O6, is a piezoelectric ceramic typically used because of its elevated Curie temperature and anisotropic properties. However, the piezoelectric constant, d33, is relatively low in randomly oriented ceramics when compared to other ferroelectrics. Crystallographic texturing is often employed to increase the piezoelectric constant because the spontaneous polarization axes of grains are better aligned. In this research, crystallographic textures induced through tape casting are distinguished from textures induced through electrical poling. Texture is described using multiple quantitative approaches utilizing X-ray and neutron time-of-flight diffraction. Tape casting lead metaniobate with an inclusion of acicular template particles induces an orthotropic texture distribution. Templated grain growth from seed particles oriented during casting results in anisotropic grain structures. The degree of preferred orientation is directly linked to the shear behavior of the tape cast slurry. Increases in template concentration, slurry viscosity, and casting velocity lead to larger textures by inducing more particle orientation in the tape casting plane. The maximum 010 texture distributions were two and a half multiples of a random distribution. Ferroelectric texture was induced by electrical poling. Electric poling increases the volume of material oriented with the spontaneous polarization direction in the material. Samples with an initial paraelectric texture exhibit a greater change in the domain volume fraction during electrical poling than randomly oriented ceramics. In tape cast samples, the resulting piezoelectric response is proportional to the 010 texture present prior to poling. This results in property anisotropy dependent on initial texture. Piezoelectric properties measured on the most textured ceramics were similar to those obtained with a commercial standard.

Modulating protein behaviors on responsive surface by external electric fields: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Xie, Yun; Pan, Yufang; Zhang, Rong; Liang, Ying; Li, Zhanchao

2015-01-01

Molecular dynamics simulations were employed to investigate the modulation of protein behaviors on the electrically responsive zwitterionic phosphorylcholine self-assembled monolayers (PC-SAMs). Results show that PC-SAMs could sensitively respond to the applied electric fields and exhibit three states with different charge distributions, namely both the negatively charged phosphate groups and the positively charged choline groups are exposed to the solution in the absence of electric fields (state 1), phosphate groups exposed in the presence of positive electric fields (state 2), and choline groups exposed in the presence of negative electric fields (state 3). Under state 1, the adsorption of Cyt c on the PC-SAM is reversible and the orientations of Cyt c are randomly distributed. Under state 2, the adsorption of Cyt c is enhanced due to the electrostatic attractions between the exposed phosphate groups and the positively charged protein; when adsorbed on the PC-SAMs, Cyt c tends to adopt the orientation with the heme plane perpendicular to the surface plane, and the percentage of this orientation increases as the field strength rises up. Under state 3, the adsorption of Cyt c is retarded because of the electrostatic repulsions between the exposed choline groups and the protein; however, if the gaps between PC chains are large enough, Cyt c could insert into the PC-SAM and access the phosphate groups after overcoming a slight energy barrier. Under three states, the basic backbone structures of Cyt c are well kept within the simulation time since the conformation of Cyt c is mainly affected by the surface-generated electric fields, whose strengths are modulated by the external electric fields and are not strong enough to deform protein. The results indicate the possibility of regulating protein behaviors, including promoting or retarding protein adsorption and regulating protein orientations, on responsive surfaces by applying electric fields on the surfaces without worrying protein deformation, which may be helpful in the applications of protein separation and controlled drug delivery.

A terrestrial lidar-based workflow for determining three-dimensional slip vectors and associated uncertainties

USGS Publications Warehouse

Gold, Peter O.; Cowgill, Eric; Kreylos, Oliver; Gold, Ryan D.

2012-01-01

Three-dimensional (3D) slip vectors recorded by displaced landforms are difficult to constrain across complex fault zones, and the uncertainties associated with such measurements become increasingly challenging to assess as landforms degrade over time. We approach this problem from a remote sensing perspective by using terrestrial laser scanning (TLS) and 3D structural analysis. We have developed an integrated TLS data collection and point-based analysis workflow that incorporates accurate assessments of aleatoric and epistemic uncertainties using experimental surveys, Monte Carlo simulations, and iterative site reconstructions. Our scanning workflow and equipment requirements are optimized for single-operator surveying, and our data analysis process is largely completed using new point-based computing tools in an immersive 3D virtual reality environment. In a case study, we measured slip vector orientations at two sites along the rupture trace of the 1954 Dixie Valley earthquake (central Nevada, United States), yielding measurements that are the first direct constraints on the 3D slip vector for this event. These observations are consistent with a previous approximation of net extension direction for this event. We find that errors introduced by variables in our survey method result in <2.5 cm of variability in components of displacement, and are eclipsed by the 10–60 cm epistemic errors introduced by reconstructing the field sites to their pre-erosion geometries. Although the higher resolution TLS data sets enabled visualization and data interactivity critical for reconstructing the 3D slip vector and for assessing uncertainties, dense topographic constraints alone were not sufficient to significantly narrow the wide (<26°) range of allowable slip vector orientations that resulted from accounting for epistemic uncertainties.

Three-dimensional tool radius compensation for multi-axis peripheral milling

NASA Astrophysics Data System (ADS)

Chen, Youdong; Wang, Tianmiao

2013-05-01

Few function about 3D tool radius compensation is applied to generating executable motion control commands in the existing computer numerical control (CNC) systems. Once the tool radius is changed, especially in the case of tool size changing with tool wear in machining, a new NC program has to be recreated. A generic 3D tool radius compensation method for multi-axis peripheral milling in CNC systems is presented. The offset path is calculated by offsetting the tool path along the direction of the offset vector with a given distance. The offset vector is perpendicular to both the tangent vector of the tool path and the orientation vector of the tool axis relative to the workpiece. The orientation vector equations of the tool axis relative to the workpiece are obtained through homogeneous coordinate transformation matrix and forward kinematics of generalized kinematics model of multi-axis machine tools. To avoid cutting into the corner formed by the two adjacent tool paths, the coordinates of offset path at the intersection point have been calculated according to the transition type that is determined by the angle between the two tool path tangent vectors at the corner. Through the verification by the solid cutting simulation software VERICUT® with different tool radiuses on a table-tilting type five-axis machine tool, and by the real machining experiment of machining a soup spoon on a five-axis machine tool with the developed CNC system, the effectiveness of the proposed 3D tool radius compensation method is confirmed. The proposed compensation method can be suitable for all kinds of three- to five-axis machine tools as a general form.

USSR and Eastern Europe Scientific Abstracts- Physics - Number 45

DTIC Science & Technology

1978-10-02

compound, a function of the angle between the electrical vector of the ’ light wave and the optical c-axis of the crystal. Heterodiodes have first...of naturally radioactive U, Th and K in a 1-liter sample. USSR A VECTOR MESON IN A QUANTUM ELECTROMAGNETIC FIELD Moscow TEORETICHESKAYA I...arbitrary spin in a classical plane electromagnetic field are used to find the exact wave function of a vector meson in the quantum field of a linearly

Radar Differential Phase Signatures of Ice Orientation for the Prediction of Lightning Initiation and Cessation

NASA Technical Reports Server (NTRS)

Carey, L.D.; Petersen, W.A.; Deierling, W.

2009-01-01

The majority of lightning-related casualties typically occur during thunderstorm initiation (e.g., first flash) or dissipation (e.g., last flash). The physics of electrification and lightning production during thunderstorm initiation is fairly well understood. As such, the literature includes a number of studies presenting various radar techniques (using reflectivity and, if available, other dual-polarimetric parameters) for the anticipation of initial electrification and first lightning flash. These radar techniques have shown considerable skill at forecasting first flash. On the other hand, electrical processes and lightning production during thunderstorm dissipation are not nearly as well understood and few, if any, successful techniques have been developed to anticipate the last flash and subsequent cessation of lightning. One promising approach involves the use of dual-polarimetric radar variables to infer the presence of oriented ice crystals in lightning producing storms. In the absence of strong vertical electric fields, ice crystals fall with their largest (semi-major) axis in the horizontal associated with gravitational and aerodynamic forces. In thunderstorms, strong vertical electric fields (100-200 kV m(sup -1)) have been shown to orient small (less than 2 mm) ice crystals such that their semi-major axis is vertical (or nearly vertical). After a lightning flash, the electric field is typically relaxed and prior radar research suggests that ice crystals rapidly resume their preferred horizontal orientation. In active thunderstorms, the vertical electric field quickly recovers and the ice crystals repeat this cycle of orientation for each nearby flash. This change in ice crystal orientation from primarily horizontal to vertical during the development of strong vertical electric fields prior to a lightning flash forms the physical basis for anticipating lightning initiation and, potentially, cessation. Research has shown that radar reflectivity (Z) and other co-polar back-scattering radar measurements like differential reflectivity (Z(sub dr)) typically measured by operational dual-polarimetric radars are not sensitive to these changes in ice crystal orientation. However, prior research has demonstrated that oriented ice crystals cause significant propagation effects that can be routinely measured by most dual-polarimetric radars from X-band (3 cm) to S-band (10 cm) wavelengths using the differential propagation phase shift (often just called differential phase, phi(sub dp)) or its range derivative, the specific differential phase (K(sub dp)). Advantages of the differential phase include independence from absolute or relative power calibration, attenuation, differential attenuation and relative insensitivity to ground clutter and partial beam occultation effects (as long as the signal remains above noise). In research mode, these sorts of techniques have been used to anticipate initial cloud electrification, lightning initiation, and cessation. In this study, we develop a simplified model of ice crystal size, shape, orientation, dielectric, and associated radar scattering and propagation effects in order to simulate various idealized scenarios of ice crystals responding to a hypothetical electric field and their dual-polarimetric radar signatures leading up to lightning initiation and particularly cessation. The sensitivity of the K(sub dp) ice orientation signature to various ice properties and radar wavelength will be explored. Since K(sub dp) is proportional to frequency in the Rayleigh- Gans scattering regime, the ice orientation signatures should be more obvious at higher (lower) frequencies (wavelengths). As a result, simulations at radar wavelengths from 10 cm down to 1 cm (Ka-band) will be conducted. Resonance effects will be considered using the T-matrix method. Since most K(sub dp) Vbased observations have been shown at S-band, we will present ice orientation signatures from C-band (UAH/NASA ARMOR) and X-bd (UAH MAX) dual-polarimetric radars located in Northern Alabama. Issues related to optimal radar scanning for the detection of oriented ice will be discussed. Preliminary suggestions on how these differential phase signatures of oriented ice could contribute to lightning initiation and cessation algorithms will be presented.

Measurement of Anisotropic Particle Interactions with Nonuniform ac Electric Fields.

PubMed

Rupp, Bradley; Torres-Díaz, Isaac; Hua, Xiaoqing; Bevan, Michael A

2018-02-20

Optical microscopy measurements are reported for single anisotropic polymer particles interacting with nonuniform ac electric fields. The present study is limited to conditions where gravity confines particles with their long axis parallel to the substrate such that particles can be treated using quasi-2D analysis. Field parameters are investigated that result in particles residing at either electric field maxima or minima and with long axes oriented either parallel or perpendicular to the electric field direction. By nonintrusively observing thermally sampled positions and orientations at different field frequencies and amplitudes, a Boltzmann inversion of the time-averaged probability of states yields kT-scale energy landscapes (including dipole-field, particle-substrate, and gravitational potentials). The measured energy landscapes show agreement with theoretical potentials using particle conductivity as the sole adjustable material property. Understanding anisotropic particle-field energy landscapes vs field parameters enables quantitative control of local forces and torques on single anisotropic particles to manipulate their position and orientation within nonuniform fields.

Sustainer electric propulsion system application for spacecraft attitude control

NASA Astrophysics Data System (ADS)

Obukhov, V. A.; Pokryshkin, A. I.; Popov, G. A.; Yashina, N. V.

2010-07-01

Application of electric propulsion system (EPS) requires spacecraft (SC) equipping with large solar panels (SP) for the power supply to electric propulsions. This makes the problem of EPS-equipped SC control at the insertion stage more difficult to solve than in the case of SC equipped with chemical engines, because in addition to the SC attitude control associated with the mission there appears necessity in keeping SP orientation to Sun that is necessary for generation of electric power sufficient for the operation of service systems, purpose-oriented equipment, and EPS. The theoretical study of the control problem is the most interesting for a non-coplanar transfer from high elliptic orbit (HEO) to geostationary orbit (GSO).

Real-time detection with AdaBoost-svm combination in various face orientation

NASA Astrophysics Data System (ADS)

Fhonna, R. P.; Nasution, M. K. M.; Tulus

2018-03-01

Most of the research has used algorithm AdaBoost-SVM for face detection. However, to our knowledge so far there is no research has been facing detection on real-time data with various orientations using the combination of AdaBoost and Support Vector Machine (SVM). Characteristics of complex and diverse face variations and real-time data in various orientations, and with a very complex application will slow down the performance of the face detection system this becomes a challenge in this research. Face orientation performed on the detection system, that is 900, 450, 00, -450, and -900. This combination method is expected to be an effective and efficient solution in various face orientations. The results showed that the highest average detection rate is on the face detection oriented 00 and the lowest detection rate is in the face orientation 900.

Back contact to film silicon on metal for photovoltaic cells

DOEpatents

Branz, Howard M.; Teplin, Charles; Stradins, Pauls

2013-06-18

A crystal oriented metal back contact for solar cells is disclosed herein. In one embodiment, a photovoltaic device and methods for making the photovoltaic device are disclosed. The photovoltaic device includes a metal substrate with a crystalline orientation and a heteroepitaxial crystal silicon layer having the same crystal orientation of the metal substrate. A heteroepitaxial buffer layer having the crystal orientation of the metal substrate is positioned between the substrate and the crystal silicon layer to reduce diffusion of metal from the metal foil into the crystal silicon layer and provide chemical compatibility with the heteroepitaxial crystal silicon layer. Additionally, the buffer layer includes one or more electrically conductive pathways to electrically couple the crystal silicon layer and the metal substrate.

Extrema of mass, first law of black hole mechanics, and a staticity theorem in Einstein-Maxwell-axion-dilaton gravity

NASA Astrophysics Data System (ADS)

Rogatko, Marek

1998-08-01

Using the ADM formulation of the Einstein-Maxwell axion-dilaton gravity we derive the formulas for the variation of mass and other asymptotic conserved quantities in the theory under consideration. Generalizing this kind of reasoning to the initial data for the manifold with an interior boundary we get the generalized first law of black hole mechanics. We consider an asymptotically flat solution to the Einstein-Maxwell axion-dilaton gravity describing a black hole with a Killing vector field timelike at infinity, the horizon of which comprises a bifurcate Killing horizon with a bifurcate surface. Supposing that the Killing vector field is asymptotically orthogonal to the static hypersurface with boundary S and a compact interior, we find that the solution is static in the exterior world, when the timelike vector field is normal to the horizon and has vanishing electric and axion-electric fields on static slices.

Analyzing Small Signal Stability of Power System based on Online Data by Use of SMES

NASA Astrophysics Data System (ADS)

Ishikawa, Hiroyuki; Shirai, Yasuyuki; Nitta, Tanzo; Shibata, Katsuhiko

The purpose of this study is to estimate eigen-values and eigen-vectors of a power system from on-line data to evaluate the power system stability. Power system responses due to the small power modulation of known pattern from SMES (Superconducting Magnetic Energy Storage) were analyzed, and the transfer functions between the power modulation and power oscillations of generators were obtained. Eigen-values and eigen-vectors were estimated from the transfer functions. Experiments were carried out by use of a model SMES and Advanced Power System Analyzer (APSA), which is an analogue type power system simulator of Kansai Electric Power Company Inc., Japan. Changes in system condition were observed by the estimated eigen-values and eigen-vectors. Result agreed well with the resent report and digital simulation. This method gives a new application for SMES, which will be installed for improving electric power quality.

Interfacial dislocations in (111) oriented (Ba 0.7Sr 0.3)TiO 3 films on SrTiO 3 single crystal

DOE PAGES

Shen, Xuan; Yamada, Tomoaki; Lin, Ruoqian; ...

2015-10-08

In this study, we have investigated the interfacial structure of epitaxial (Ba,Sr)TiO 3 films grown on (111)-oriented SrTiO 3 single-crystal substrates using transmission electron microscopy (TEM) techniques. Compared with the (100) epitaxial perovskite films, we observe dominant dislocation half-loop with Burgers vectors of a<110> comprised of a misfit dislocation along <112>, and threading dislocations along <110> or <100>. The misfit dislocation with Burgers vector of a <110> can dissociate into two ½ a <110> partial dislocations and one stacking fault. We found the dislocation reactions occur not only between misfit dislocations, but also between threading dislocations. Via three-dimensional electron tomography,more » we retrieved the configurations of the threading dislocation reactions. The reactions between threading dislocations lead to a more efficient strain relaxation than do the misfit dislocations alone in the near-interface region of the (111)-oriented (Ba 0.7Sr 0.3)TiO 3 films.« less

A neural network simulating human reach-grasp coordination by continuous updating of vector positioning commands.

PubMed

Ulloa, Antonio; Bullock, Daniel

2003-10-01

We developed a neural network model to simulate temporal coordination of human reaching and grasping under variable initial grip apertures and perturbations of object size and object location/orientation. The proposed model computes reach-grasp trajectories by continuously updating vector positioning commands. The model hypotheses are (1) hand/wrist transport, grip aperture, and hand orientation control modules are coupled by a gating signal that fosters synchronous completion of the three sub-goals. (2) Coupling from transport and orientation velocities to aperture control causes maximum grip apertures that scale with these velocities and exceed object size. (3) Part of the aperture trajectory is attributable to an aperture-reducing passive biomechanical effect that is stronger for larger apertures. (4) Discrepancies between internal representations of targets partially inhibit the gating signal, leading to movement time increases that compensate for perturbations. Simulations of the model replicate key features of human reach-grasp kinematics observed under three experimental protocols. Our results indicate that no precomputation of component movement times is necessary for online temporal coordination of the components of reaching and grasping.

X-ray vector radiography of a human hand

NASA Astrophysics Data System (ADS)

Jud, Christoph; Braig, Eva; Dierolf, Martin; Eggl, Elena; Günther, Benedikt; Achterhold, Klaus; Gleich, Bernhard; Rummeny, Ernst; Noël, Peter; Pfeiffer, Franz; Münzel, Daniela

2017-03-01

Grating based x-ray phase-contrast reveals differential phase-contrast (DPC) and dark-field contrast (DFC) on top of the conventional absorption image. X-ray vector radiography (XVR) exploits the directional dependence of the DFC and yields the mean scattering strength, the degree of anisotropy and the orientation of scattering structures by combining several DFC-projections. Here, we perform an XVR of an ex vivo human hand specimen. Conventional attenuation images have a good contrast between the bones and the surrounding soft tissue. Within the bones, trabecular structures are visible. However, XVR detects subtler differences within the trabecular structure: there is isotropic scattering in the extremities of the phalanx in contrast to anisotropic scattering in its body. The orientation changes as well from relatively random in the extremities to an alignment along the longitudinal trabecular orientation in the body. In the other bones measured, a similar behavior was found. These findings indicate a deeper insight into the anatomical configuration using XVR compared to conventional radiography. Since microfractures cause a discontinuous trabecular structure, XVR could help to detect so-called radiographically occult fractures of the trabecular bones.

Effect of magnetic and electric coupling fields on micro- and nano- structure of carbon films in the CVD diamond process and their electron field emission property

NASA Astrophysics Data System (ADS)

Wang, Yijia; Li, Jiaxin; Hu, Naixiu; Jiang, Yunlu; Wei, Qiuping; Yu, Zhiming; Long, Hangyu; Zhu, Hekang; Xie, Youneng; Ma, Li; Lin, Cheng-Te; Su, Weitao

2018-03-01

In this paper, both electric field and magnetic field were used to assist the hot filament chemical vapor deposition (HFCVD) and we systematically investigated the effects of which on the (1) phase composition, (2) grain size, (3) thickness and (4) preferred orientation of diamond films through SEM, Raman and XRD. The application of magnetic field in electric field, so called ‘the magnetic and electric coupling fields’, enhanced the graphitization and refinement of diamond crystals, slowed down the decrease of film thickness along with the increase of bias current, and suppressed diamond (100) orientation. During the deposition process, the electric field provided additional energy to HFCVD system and generated large number of energetic particles which might annihilate at the substrate and lose kinetic energy, while the Lorentz force, provided by magnetic field, could constrict charged particles (including electrons) to do spiral movement, which prolonged their moving path and life, thus the system energy increased. With the graphitization of diamond films intensified, the preferred orientation of diamond films completely evolved from (110) to (100), until the orientation and diamond phase disappeared, which can be attributed to (I) the distribution and concentration ratio of carbon precursors (C2H2 and CH3) and (II) graphitization sequence of diamond crystal facets. Since the electron field emission property of carbon film is sensitive to the phase composition, thickness and preferred orientation, nano- carbon cones, prepared by the negative bias current of 20 mA and magnetic field strength of 80 Gauss, exhibited the lowest turn-on field of 6.1 V -1 μm-1.

Microscopic vertical orientation of nano-interspaced graphene architectures in deposit films as electrodes for enhanced supercapacitor performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jang, Gyoung Gug; Song, Bo; Li, Liyi

This paper reported a novel two-step process to fabricate high-performance supercapacitor films that contain microscale domains of nano-interspaced, re-stacked graphene sheets oriented perpendicular to the surface of current collector substrate, i.e., carbon fiber paper. In the two-step process, we first used ligand molecules to modify the surface of graphene oxide (GO) sheets and manipulate the interspacing between the re-stacked GO sheets. The ligand-modified GOs, i.e., m-GOs, were then reduced to obtain more conductive graphene (m-rGO), where X-ray diffraction measurement results indicated well-controlled interlayer spacing between the restacked m-rGO sheets up to 1 nm. The typical lateral dimension of the restackedmore » m-rGO sheets were ~40 µm. Then, electrical field was introduced during m-rGO slurry deposition process to induce the vertical orientation of the m-rGO sheets/stacks in the film deposit. The direct current electrical field induced the orientation of the domains of m-rGO stacks along the direction perpendicular to the surface of deposit film, i.e., direction of electric field. Also, the applied electric field increased the interlayer spacing further, which should enhance the diffusion and accessibility of electrolyte ions. As compared with the traditionally deposited “control” films, the field-processed film deposits that contain oriented structure of graphene sheets/stacks have shown up to ~1.6 times higher values in capacitance (430 F/g at 0.5 A/g) and ~67% reduction in equivalent series resistance. Finally, the approach of using electric field to tailor the microscopic architecture of graphene-based deposit films is effective to fabricate film electrodes for high performance supercapacitors.« less

Microscopic vertical orientation of nano-interspaced graphene architectures in deposit films as electrodes for enhanced supercapacitor performance

DOE PAGES

Jang, Gyoung Gug; Song, Bo; Li, Liyi; ...

2016-12-14

This paper reported a novel two-step process to fabricate high-performance supercapacitor films that contain microscale domains of nano-interspaced, re-stacked graphene sheets oriented perpendicular to the surface of current collector substrate, i.e., carbon fiber paper. In the two-step process, we first used ligand molecules to modify the surface of graphene oxide (GO) sheets and manipulate the interspacing between the re-stacked GO sheets. The ligand-modified GOs, i.e., m-GOs, were then reduced to obtain more conductive graphene (m-rGO), where X-ray diffraction measurement results indicated well-controlled interlayer spacing between the restacked m-rGO sheets up to 1 nm. The typical lateral dimension of the restackedmore » m-rGO sheets were ~40 µm. Then, electrical field was introduced during m-rGO slurry deposition process to induce the vertical orientation of the m-rGO sheets/stacks in the film deposit. The direct current electrical field induced the orientation of the domains of m-rGO stacks along the direction perpendicular to the surface of deposit film, i.e., direction of electric field. Also, the applied electric field increased the interlayer spacing further, which should enhance the diffusion and accessibility of electrolyte ions. As compared with the traditionally deposited “control” films, the field-processed film deposits that contain oriented structure of graphene sheets/stacks have shown up to ~1.6 times higher values in capacitance (430 F/g at 0.5 A/g) and ~67% reduction in equivalent series resistance. Finally, the approach of using electric field to tailor the microscopic architecture of graphene-based deposit films is effective to fabricate film electrodes for high performance supercapacitors.« less

Dislocation structures and electrical conduction properties of low angle tilt grain boundaries in LiNbO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Furushima, Yuho; Nakamura, Atsutomo, E-mail: nakamura@numse.nagoya-u.ac.jp; Toyoura, Kazuaki

Dislocations in crystalline materials constitute unique, atomic-scale, one-dimensional structure and have a potential to induce peculiar physical properties that are not found in the bulk. In this study, we fabricated LiNbO{sub 3} bicrystals with low angle tilt grain boundaries and investigated the relationship between the atomic structure of the boundary dislocations and their electrical conduction properties. Observations by using transmission electron microscopy revealed that dislocation structures at the (0001) low angle tilt grain boundaries depend on the tilt angle of the boundaries. Specifically, the characteristic dislocation structures with a large Burgers vector were formed in the boundary with the tiltmore » angle of 2°. It is noteworthy that only the grain boundary of 2° exhibits distinct electrical conductivity after reduction treatment, although LiNbO{sub 3} is originally insulating. This unique electrical conductivity is suggested to be due to the characteristic dislocation structures with a large Burgers vector.« less

Results of solar electric thrust vector control system design, development and tests

NASA Technical Reports Server (NTRS)

Fleischer, G. E.

1973-01-01

Efforts to develop and test a thrust vector control system TVCS for a solar-energy-powered ion engine array are described. The results of solar electric propulsion system technology (SEPST) III real-time tests of present versions of TVCS hardware in combination with computer-simulated attitude dynamics of a solar electric multi-mission spacecraft (SEMMS) Phase A-type spacecraft configuration are summarized. Work on an improved solar electric TVCS, based on the use of a state estimator, is described. SEPST III tests of TVCS hardware have generally proved successful and dynamic response of the system is close to predictions. It appears that, if TVCS electronic hardware can be effectively replaced by control computer software, a significant advantage in control capability and flexibility can be gained in future developmental testing, with practical implications for flight systems as well. Finally, it is concluded from computer simulations that TVCS stabilization using rate estimation promises a substantial performance improvement over the present design.

New Materials, Techniques and Device Concepts for Organic NLO Chromophore-based Electrooptic Devices. Part 1

DTIC Science & Technology

2006-08-23

polarization the electric field vector is parallel to the substrate, for TM polarization the magnetic field vector is parallel to the substrate. Figure...section can be obtained for the case of the two electromagnetic field polarization vectors λ and µ describing the two photons being absorbed (of the same or... polarization effects on two-photon absorption as investigated by the technique of thermal lensing detected absorption of a mode- locked laser beam. This

Electromagnetic Fields of a Uniform Sphere in a Uniform Conducting Medium with Application to Dipole Sources

DTIC Science & Technology

1991-09-01

12b. DISTRIBUTION CODE Approved for public release; distribution is unlimited. 13. ABSTRACT (Maximum 200 words) Vector spherical harmonic expansions are...electric and magnetic field vectors from E rand B - r alone. Genural expressions are given relating the scattered field expansion coefficients to the source...Prescnbed by ANSI Std. Z39-18 29W-102 NCSC TR 426-90 CONTENTS Pag o INTRODUCTION 1 BACKGROUND 1 ANGULAR MOMENTUM OPERATOR AND VECTOR SPHERICAL

Industrial Education. Electricity/Electronics Curriculum Guide, Phase II. Instructional Modules, Level III.

ERIC Educational Resources Information Center

Lillo, Robert E.; Soffiotto, Nicholas S.

Designed for students in the tenth grade, this electricity/electronics curriculum guide contains instructional modules for sixteen units of instruction: (1) orientation, (2) introduction to electricity/electronics, (3) electricity/electronics safety, (4) fundamental skills, (5) direct current circuits, (6) graphical illustrations, (7) circuit…

Rear wheel torque vectoring model predictive control with velocity regulation for electric vehicles

NASA Astrophysics Data System (ADS)

Siampis, Efstathios; Velenis, Efstathios; Longo, Stefano

2015-11-01

In this paper we propose a constrained optimal control architecture for combined velocity, yaw and sideslip regulation for stabilisation of the vehicle near the limit of lateral acceleration using the rear axle electric torque vectoring configuration of an electric vehicle. A nonlinear vehicle and tyre model are used to find reference steady-state cornering conditions and design two model predictive control (MPC) strategies of different levels of fidelity: one that uses a linearised version of the full vehicle model with the rear wheels' torques as the input, and another one that neglects the wheel dynamics and uses the rear wheels' slips as the input instead. After analysing the relative trade-offs between performance and computational effort, we compare the two MPC strategies against each other and against an unconstrained optimal control strategy in Simulink and Carsim environment.

From Morphology to Neural Information: The Electric Sense of the Skate

PubMed Central

Camperi, Marcelo; Tricas, Timothy C; Brown, Brandon R

2007-01-01

Morphology typically enhances the fidelity of sensory systems. Sharks, skates, and rays have a well-developed electrosense that presents strikingly unique morphologies. Here, we model the dynamics of the peripheral electrosensory system of the skate, a dorsally flattened batoid, moving near an electric dipole source (e.g., a prey organism). We compute the coincident electric signals that develop across an array of the skate's electrosensors, using electrodynamics married to precise morphological measurements of sensor location, infrastructure, and vector projection. Our results demonstrate that skate morphology enhances electrosensory information. Not only could the skate locate prey using a simple population vector algorithm, but its morphology also specifically leads to quick shifts in firing rates that are well-suited to the demonstrated bandwidth of the electrosensory system. Finally, we propose electrophysiology trials to test the modeling scheme. PMID:17571918

Art and Physics.

ERIC Educational Resources Information Center

Altshuler, Ken

1994-01-01

Presents a method using art classics to teach that a third vector axis is required to represent orientations in three-dimensional space. Helps students understand the importance of perspective, frame of reference, balance, and color theory. (MVL)

Altered Orientation and Flight Paths of Pigeons Reared on Gravity Anomalies: A GPS Tracking Study

PubMed Central

Blaser, Nicole; Guskov, Sergei I.; Meskenaite, Virginia; Kanevskyi, Valerii A.; Lipp, Hans-Peter

2013-01-01

The mechanisms of pigeon homing are still not understood, in particular how they determine their position at unfamiliar locations. The “gravity vector” theory holds that pigeons memorize the gravity vector at their home loft and deduct home direction and distance from the angular difference between memorized and actual gravity vector. However, the gravity vector is tilted by different densities in the earth crust leading to gravity anomalies. We predicted that pigeons reared on different gravity anomalies would show different initial orientation and also show changes in their flight path when crossing a gravity anomaly. We reared one group of pigeons in a strong gravity anomaly with a north-to-south gravity gradient, and the other group of pigeons in a normal area but on a spot with a strong local anomaly with a west-to-east gravity gradient. After training over shorter distances, pigeons were released from a gravitationally and geomagnetically normal site 50 km north in the same direction for both home lofts. As expected by the theory, the two groups of pigeons showed divergent initial orientation. In addition, some of the GPS-tracked pigeons also showed changes in their flight paths when crossing gravity anomalies. We conclude that even small local gravity anomalies at the birth place of pigeons may have the potential to bias the map sense of pigeons, while reactivity to gravity gradients during flight was variable and appeared to depend on individual navigational strategies and frequency of position updates. PMID:24194860

Measurements of the STS orbiter's angular stability during in-orbit operations

NASA Technical Reports Server (NTRS)

Neupert, Werner M.; Epstein, Gabriel L.; Houston, James; Zarechnak, Andrew

1995-01-01

We report on measurements of the angular stability, commonly called 'jitter', of the STS Orbiter during normal operations in space. Measurements were carried out by measuring optically the Orbiter's roll and pitch orientation relative to the solar vector as the orbiter was held in a -Z(sub 0) solar inertial orientation (orbiter bay oriented toward the Sun). We also report observations of an interesting perturbation to the orbiter's orientation noted by the crew during the STS-60 mission. These data may be useful in analyzing the in-orbit response of the Orbiter to thruster firings and other applied torques, and may aid in the planning of future experiments that require fine-pointed operations by the orbiter.

Fluctuations of local electric field and dipole moments in water between metal walls.

PubMed

Takae, Kyohei; Onuki, Akira

2015-10-21

We examine the thermal fluctuations of the local electric field Ek (loc) and the dipole moment μk in liquid water at T = 298 K between metal walls in electric field applied in the perpendicular direction. We use analytic theory and molecular dynamics simulation. In this situation, there is a global electrostatic coupling between the surface charges on the walls and the polarization in the bulk. Then, the correlation function of the polarization density pz(r) along the applied field contains a homogeneous part inversely proportional to the cell volume V. Accounting for the long-range dipolar interaction, we derive the Kirkwood-Fröhlich formula for the polarization fluctuations when the specimen volume v is much smaller than V. However, for not small v/V, the homogeneous part comes into play in dielectric relations. We also calculate the distribution of Ek (loc) in applied field. As a unique feature of water, its magnitude |Ek (loc)| obeys a Gaussian distribution with a large mean value E0 ≅ 17 V/nm, which arises mainly from the surrounding hydrogen-bonded molecules. Since |μk|E0 ∼ 30kBT, μk becomes mostly parallel to Ek (loc). As a result, the orientation distributions of these two vectors nearly coincide, assuming the classical exponential form. In dynamics, the component of μk(t) parallel to Ek (loc)(t) changes on the time scale of the hydrogen bonds ∼5 ps, while its smaller perpendicular component undergoes librational motions on time scales of 0.01 ps.

Surface Charge Effects on the Electro-Orientation of Insulating Nanotubes in Aqueous Electrolytes

NASA Astrophysics Data System (ADS)

Cetindag, Semih; Tiwari, Bishnu; Zhang, Dongyan; Yap, Yoke Khin; Kim, Sangil; Shan, Jerry W.

2017-11-01

While the alignment of electrically conductive nanowires and nanotubes by electric fields in liquid solution has been well studied, much less is known about the electro-orientation of insulating 1D particles, such as boron-nitride nanotubes (BNNTs). Here, we demonstrate for the first time the electro-orientation of individual insulating BNNTs in aqueous KCl solutions under AC fields. Comparison to theory indicates that the observed frequency response is not related to the crossover for Maxwell-Wagner interfacial polarization. Instead, the cross-over frequency in the low-frequency regime scales as the square root of solution conductivity, indicating that alignment is associated with the formation and motion of an electrical double layer (EDL), much like induced-charge electro-osmosis for a conducting particle. However, the mechanism for the formation of the EDL is presumably different for insulating particles like BNNTs as compared to conductors. By varying the surface charge of the particle by changing pH, we show that the alignment rate increases with increasing surface charge, and is likely a result of counter-ion migration and EDL polarization under the influence of applied electric field. Thus, particle surface charge (large Dukhin number) is believed to play a vital role in the electro-orientation of insulating particles in aqueous solutions. NSF CBET-1604931 and NSF DMR-1261910.

Effect of difference of cupula and endolymph densities on the dynamics of semicircular canal.

PubMed

Kondrachuk, A V; Sirenko, S P; Boyle, R

2008-01-01

The effect of different densities of a cupula and endolymph on the dynamics of the semicircular canals is considered within the framework of a simplified one-dimensional mathematical model where the canal is approximated by a torus. If the densities are equal, the model is represented by Steinhausen's phenomenological equation. The difference of densities results in the complex dynamics of the cupulo-endolymphatic system, and leads to a dependence on the orientation of both the gravity vector relative to the canal plane and the axis of rotation, as well as on the distance between the axis of rotation and the center of the semicircular canal. Our analysis focused on two cases of canal stimulation: rotation with a constant velocity and a time-dependent (harmonically oscillating) angular velocity. Two types of spatial orientation of the axis of rotation, the axis of canal symmetry, and the vector of gravity were considered: i) the gravity vector and axis of rotation lie in the canal plane, and ii) the axis of rotation and gravity vector are normal to the canal plane. The difference of the cupula and endolymph densities reveals new features of cupula dynamics, for instance--a shift of the cupula to a new position of equilibrium that depends on the gravity vector and the parameters of head rotation, and the onset of cupula oscillations with multiple frequencies that results in the distortion of cupula dynamics relative to harmonic stimulation. Factors that might influence the density difference effects and the conditions under which these effects occur are discussed.

The influence of assist gas on magnetic properties of electrotechnical steel sheets cut with laser

NASA Astrophysics Data System (ADS)

Gaworska-Koniarek, Dominika; Szubzda, Bronisław; Wilczyński, Wiesław; Drosik, Jerzy; Karaś, Kazimierz

2011-07-01

The paper presents the influence of assist gas (air and nitrogen) during laser cutting on magnetization, magnetic permeability and loss characteristics of non-oriented electrical steels. The research was made on an non-oriented M330-50A grade electrical steels by means of single sheet tester. In order to enhance the effect of cutting and the same degradation zone on magnetic properties, strips with different width were achieved. Measurements results indicate that application of air as assist gas has more destructive effect on magnetic properties of electrical steels than nitrogen one.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schoenfeld, A; Poppinga, D; Poppe, B

Purpose: This study aims to investigate the optical properties of radiochromic EBT3 films on exposure to polarized incident light. Methods: An optical table setup was used to investigate the properties of exposed and unexposed EBT3 films. The films were placed with their long side horizontally and illuminated with polarized incident white light. The polarization of light with the electrical vector pointing vertically is referred to as 0°, accordingly horizontal orientation corresponds to 90°. The light transmission was measured depending on the polarization angle of the incident light and the polarization of a polarizer in front of the detector. Secondly, themore » scattering properties of exposed and unexposed films were measured by placing a plane convex lens behind the films and a screen in its focal plane. Thereby, the distribution of the scattering angles appears as an intensity map on the screen. The distributions of scattering angles caused by EBT3 films and by neutral density filters were compared. Results: EBT3 films show a strong dependence of the light transmission on the polarization of the incident light. With both polarizers parallel, a peak transmission was found at 90° orientation of the polarizers. With the rear polarizer at right angles with the front polarizer, peak transmissions were found at front polarizer orientations 45° and 135°. The scattering appears to be anisotropic with a preference direction parallel to the long side of the film. The portion of scattered light and the half value scattering angle both increase with the dose on the film. Conclusion: EBT3 films show dose dependent changes in polarized light transmission and anisotropic light scattering. These effects impair the light absorption measurements on exposed films performed with commercial flatbed scanners and are causing the well-known artifacts of radiochromic film dosimetry with flatbed scanners, the “orientation effect” and the “parabola effect”.« less

Nanoscale Control over the Mixing Behavior of Surface-Confined Bicomponent Supramolecular Networks Using an Oriented External Electric Field

PubMed Central

2017-01-01

Strong electric fields are known to influence the properties of molecules as well as materials. Here we show that by changing the orientation of an externally applied electric field, one can locally control the mixing behavior of two molecules physisorbed on a solid surface. Whether the starting two-component network evolves into an ordered two-dimensional (2D) cocrystal, yields an amorphous network where the two components phase separate, or shows preferential adsorption of only one component depends on the solution stoichiometry. The experiments are carried out by changing the orientation of the strong electric field that exists between the tip of a scanning tunneling microscope and a solid substrate. The structure of the two-component network typically changes from open porous at negative substrate bias to relatively compact when the polarity of the applied bias is reversed. The electric-field-induced mixing behavior is reversible, and the supramolecular system exhibits excellent stability and good response efficiency. When molecular guests are adsorbed in the porous networks, the field-induced switching behavior was found to be completely different. Plausible reasons behind the field-induced mixing behavior are discussed. PMID:29112378

Prediction of protein orientation upon immobilization on biological and nonbiological surfaces

NASA Astrophysics Data System (ADS)

Talasaz, Amirali H.; Nemat-Gorgani, Mohsen; Liu, Yang; Ståhl, Patrik; Dutton, Robert W.; Ronaghi, Mostafa; Davis, Ronald W.

2006-10-01

We report on a rapid simulation method for predicting protein orientation on a surface based on electrostatic interactions. New methods for predicting protein immobilization are needed because of the increasing use of biosensors and protein microarrays, two technologies that use protein immobilization onto a solid support, and because the orientation of an immobilized protein is important for its function. The proposed simulation model is based on the premise that the protein interacts with the electric field generated by the surface, and this interaction defines the orientation of attachment. Results of this model are in agreement with experimental observations of immobilization of mitochondrial creatine kinase and type I hexokinase on biological membranes. The advantages of our method are that it can be applied to any protein with a known structure; it does not require modeling of the surface at atomic resolution and can be run relatively quickly on readily available computing resources. Finally, we also propose an orientation of membrane-bound cytochrome c, a protein for which the membrane orientation has not been unequivocally determined. electric double layer | electrostatic simulations | orientation flexibility

The ICDP Snake River Geothermal Drilling Project: preliminary overview of borehole geophysics

USGS Publications Warehouse

Schmitt, Douglas R.; Liberty, Lee M.; Kessler, James E.; Kuck, Jochem; Kofman, Randolph; Bishop, Ross; Shervais, John W.; Evans, James P.; Champion, Duane E.

2012-01-01

Hotspot: The Snake River Geothermal Drilling Project was undertaken to better understand the geothermal systems in three locations across the Snake River Plain with varying geological and hydrological structure. An extensive series of standard and specialized geophysical logs were obtained in each of the wells. Hydrogen-index neutron and γ-γ density logs employing active sources were deployed through the drill string, and although not fully calibrated for such a situation do provide semi-quantitative information related to the ‘stratigraphy’ of the basalt flows and on the existence of alteration minerals. Electrical resistivity logs highlight the existence of some fracture and mineralized zones. Magnetic susceptibility together with the vector magnetic field measurements display substantial variations that, in combination with laboratory measurements, may provide a tool for tracking magnetic field reversals along the borehole. Full waveform sonic logs highlight the variations in compressional and shear velocity along the borehole. These, together with the high resolution borehole seismic measurements display changes with depth that are not yet understood. The borehole seismic measurements indicate that seismic arrivals are obtained at depth in the formations and that strong seismic reflections are produced at lithological contacts seen in the corresponding core logging. Finally, oriented ultrasonic borehole televiewer images were obtained over most of the wells and these correlate well with the nearly 6 km of core obtained. This good image log to core correlations, particularly with regards to drilling induced breakouts and tensile borehole and core fractures will allow for confident estimates of stress directions and or placing constraints on stress magnitudes. Such correlations will be used to orient in core orientation giving information useful in hydrological assessments, paleomagnetic dating, and structural volcanology.

Dipole Relaxation in an Electric Field.

ERIC Educational Resources Information Center

Neumann, Richard M.

1980-01-01

Derives an expression for the orientational entropy of a rigid rod (electric dipole) from Boltzmann's equation. Subsequent application of Newton's second law of motion produces Debye's classical expression for the relaxation of an electric dipole in a viscous medium. (Author/GS)

DC Electric Fields, Associated Plasma Drifts, and Irregularities Observed on the C/NOFS Satellite

NASA Technical Reports Server (NTRS)

Pfaff, R.; Freudenreich, H.; Klenzing, J.

2011-01-01

Results are presented from the Vector Electric Field Investigation (VEFI) on the Air Force Communication/Navigation Outage Forecasting System (C/NOFS) satellite, a mission designed to understand, model, and forecast the presence of equatorial ionospheric irregularities. The VEFI instrument includes a vector DC electric field detector, a fixed-bias Langmuir probe operating in the ion saturation regime, a flux gate magnetometer, an optical lightning detector, and associated electronics including a burst memory. Compared to data obtained during more active solar conditions, the ambient DC electric fields and their associated E x B drifts are variable and somewhat weak, typically < 1 mV/m. Although average drift directions show similarities to those previously reported, eastward/outward during day and westward/downward at night, this pattern varies significantly with longitude and is not always present. Daytime vertical drifts near the magnetic equator are largest after sunrise, with smaller average velocities after noon. Little or no pre-reversal enhancement in the vertical drift near sunset is observed, attributable to the solar minimum conditions creating a much reduced neutral dynamo at the satellite altitude. The nighttime ionosphere is characterized by larger amplitude, structured electric fields, even where the plasma density appears nearly quiescent. Data from successive orbits reveal that the vertical drifts and plasma density are both clearly organized with longitude. The spread-F density depletions and corresponding electric fields that have been detected thus far have displayed a preponderance to appear between midnight and dawn. Associated with the narrow plasma depletions that are detected are broad spectra of electric field and plasma density irregularities for which a full vector set of measurements is available for detailed study. The VEFI data represents a new set of measurements that are germane to numerous fundamental aspects of the electrodynamics and irregularities inherent to the Earth s low latitude ionosphere.

Electric field controlled emulsion phase contactor

DOEpatents

Scott, Timothy C.

1995-01-01

A system for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity.

Method of using an electric field controlled emulsion phase contactor

DOEpatents

Scott, Timothy C.

1993-01-01

A system for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity.

Electric field controlled emulsion phase contactor

DOEpatents

Scott, T.C.

1995-01-31

A system is described for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity. 5 figs.

A Tunable Reentrant Resonator with Transverse Orientation of Electric Field for in Vivo EPR Spectroscopy

NASA Astrophysics Data System (ADS)

Chzhan, Michael; Kuppusamy, Periannan; Samouilov, Alexandre; He, Guanglong; Zweier, Jay L.

1999-04-01

There has been a need for development of microwave resonator designs optimized to provide high sensitivity and high stability for EPR spectroscopy and imaging measurements ofin vivosystems. The design and construction of a novel reentrant resonator with transversely oriented electric field (TERR) and rectangular sample opening cross section for EPR spectroscopy and imaging ofin vivobiological samples, such as the whole body of mice and rats, is described. This design with its transversely oriented capacitive element enables wide and simple setting of the center frequency by trimming the dimensions of the capacitive plate over the range 100-900 MHz with unloadedQvalues of approximately 1100 at 750 MHz, while the mechanical adjustment mechanism allows smooth continuous frequency tuning in the range ±50 MHz. This orientation of the capacitive element limits the electric field based loss of resonatorQobserved with large lossy samples, and it facilitates the use of capacitive coupling. Both microwave performance data and EPR measurements of aqueous samples demonstrate high sensitivity and stability of the design, which make it well suited forin vivoapplications.

Vector calculus in non-integer dimensional space and its applications to fractal media

NASA Astrophysics Data System (ADS)

Tarasov, Vasily E.

2015-02-01

We suggest a generalization of vector calculus for the case of non-integer dimensional space. The first and second orders operations such as gradient, divergence, the scalar and vector Laplace operators for non-integer dimensional space are defined. For simplification we consider scalar and vector fields that are independent of angles. We formulate a generalization of vector calculus for rotationally covariant scalar and vector functions. This generalization allows us to describe fractal media and materials in the framework of continuum models with non-integer dimensional space. As examples of application of the suggested calculus, we consider elasticity of fractal materials (fractal hollow ball and fractal cylindrical pipe with pressure inside and outside), steady distribution of heat in fractal media, electric field of fractal charged cylinder. We solve the correspondent equations for non-integer dimensional space models.

Storm orientation impacts on atmospheric river induced precipitation efficiency

NASA Astrophysics Data System (ADS)

Mehran, A.; Lettenmaier, D. P.

2016-12-01

Atmospheric Rivers (ARs) along the Pacific North coast are often associated with heavy winter precipitation and flooding. We analyze 35 years (1981 2016) of landfalling ARs over a transect along the U.S. West Coast consisting of four river basins from coastal Washington to Southern California (Chehalis, Russian, Santa Ana, and Santa Margarita Rivers) to assess the impact of storm orientation on precipitation rainout efficiency. We define precipitation rainout efficiency as the correlation coefficient between the net integrated vapor transport and precipitation rate. We use 6-hourly climate data from the Climate Forecast System Reanalysis (CFSR) for each of the landfalling ARs. We compute storm orientation from CFSR wind vectors (daily averaged over atmospheric levels between 1000 hPa and 300 hPa) associated with each AR event. We also compute integrated vapor transport (IVT) by multiplying precipitable water by the wind vector and compare with daily averaged precipitation averaged over the river basins, where daily precipitation is taken from Parameter-Elevation Relationships on Independent Slopes Model (PRISM) to evaluate the impact of storm orientation on rainfall efficiency. We calculate the local topographic orientation of each river basin (slope and aspect) from ArcGIS, which we related to storm orientation. To evaluate the impact of storm orientation on rainout efficiency over the Russian River basin (Northern California), we first calculated approaching IVT (for all of AR induced precipitations from 1981 to 2016) and daily averaged precipitation rate. Next, we calculated the correlation coefficient between IVT and precipitation rate (for all AR induced rainouts over the Russian River basin). Finally, by considering the local topographical changes (slope and aspect from ArcGIS) and integrating them into an effective IVT, we compared the correlation coefficients between actual and effective IVT and basin-average precipitation. We find that over the Russian River basin, the rainout efficiency increases from 55 to 75 % when we account for storm orientation relative to topography.

Single molecular orientation switching of an endohedral metallofullerene.

PubMed

Yasutake, Yuhsuke; Shi, Zujin; Okazaki, Toshiya; Shinohara, Hisanori; Majima, Yutaka

2005-06-01

The single molecular orientation switching of the Tb@C82 endohedral metallofullerene has been studied by using low-temperature ultrahigh vacuum (UHV) scanning tunneling microscopy (STM). An octanethiol self-assembled monolayer (SAM) was introduced between Tb@C82 and the Au111 substrate to control the thermal rotational states of Tb@C82. Scanning tunneling spectroscopy (STS) of Tb@C82 on an octanethiol SAM at 13 K demonstrated hysteresis including negative differential conductance (NDC). This observed hysteresis and NDC is interpreted in terms of a switching of the Tb@C82 molecular orientation caused by the interaction between its electric dipole moment and an external electric field.

Cryosurgery with pulsed electric fields.

PubMed

Daniels, Charlotte S; Rubinsky, Boris

2011-01-01

This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF) are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF) was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused PEFs could be used to ablate cells in the high subzero freezing region of a cryosurgical lesion.

Confined, Oriented, and Electrically Anisotropic Graphene Wrinkles on Bacteria.

PubMed

Deng, Shikai; Gao, Enlai; Wang, Yanlei; Sen, Soumyo; Sreenivasan, Sreeprasad Theruvakkattil; Behura, Sanjay; Král, Petr; Xu, Zhiping; Berry, Vikas

2016-09-27

Curvature-induced dipole moment and orbital rehybridization in graphene wrinkles modify its electrical properties and induces transport anisotropy. Current wrinkling processes are based on contraction of the entire substrate and do not produce confined or directed wrinkles. Here we show that selective desiccation of a bacterium under impermeable and flexible graphene via a flap-valve operation produces axially aligned graphene wrinkles of wavelength 32.4-34.3 nm, consistent with modified Föppl-von Kármán mechanics (confinement ∼0.7 × 4 μm(2)). Further, an electrophoretically oriented bacterial device with confined wrinkles aligned with van der Pauw electrodes was fabricated and exhibited an anisotropic transport barrier (ΔE = 1.69 meV). Theoretical models were developed to describe the wrinkle formation mechanism. The results obtained show bio-induced production of confined, well-oriented, and electrically anisotropic graphene wrinkles, which can be applied in electronics, bioelectromechanics, and strain patterning.

A model for the characterization of the spatial properties in vestibular neurons

NASA Technical Reports Server (NTRS)

Angelaki, D. E.; Bush, G. A.; Perachio, A. A.

1992-01-01

Quantitative study of the static and dynamic response properties of some otolith-sensitive neurons has been difficult in the past partly because their responses to different linear acceleration vectors exhibited no "null" plane and a dependence of phase on stimulus orientation. The theoretical formulation of the response ellipse provides a quantitative way to estimate the spatio-temporal properties of such neurons. Its semi-major axis gives the direction of the polarization vector (i.e., direction of maximal sensitivity) and it estimates the neuronal response for stimulation along that direction. In addition, the semi-minor axis of the ellipse provides an estimate of the neuron's maximal sensitivity in the "null" plane. In this paper, extracellular recordings from otolith-sensitive vestibular nuclei neurons in decerebrate rats were used to demonstrate the practical application of the method. The experimentally observed gain and phase dependence on the orientation angle of the acceleration vector in a head-horizontal plane was described and satisfactorily fit by the response ellipse model. In addition, the model satisfactorily fits neuronal responses in three-dimensions and unequivocally demonstrates that the response ellipse formulation is the general approach to describe quantitatively the spatial properties of vestibular neurons.

Walking Drosophila align with the e-vector of linearly polarized light through directed modulation of angular acceleration

PubMed Central

Velez, Mariel M.; Wernet, Mathias F.; Clark, Damon A.

2014-01-01

Understanding the mechanisms that link sensory stimuli to animal behavior is a central challenge in neuroscience. The quantitative description of behavioral responses to defined stimuli has led to a rich understanding of different behavioral strategies in many species. One important navigational cue perceived by many vertebrates and insects is the e-vector orientation of linearly polarized light. Drosophila manifests an innate orientation response to this cue (‘polarotaxis’), aligning its body axis with the e-vector field. We have established a population-based behavioral paradigm for the genetic dissection of neural circuits guiding polarotaxis to both celestial as well as reflected polarized stimuli. However, the behavioral mechanisms by which flies align with a linearly polarized stimulus remain unknown. Here, we present a detailed quantitative description of Drosophila polarotaxis, systematically measuring behavioral parameters that are modulated by the stimulus. We show that angular acceleration is modulated during alignment, and this single parameter may be sufficient for alignment. Furthermore, using monocular deprivation, we show that each eye is necessary for modulating turns in the ipsilateral direction. This analysis lays the foundation for understanding how neural circuits guide these important visual behaviors. PMID:24810784

Magsat - A new satellite to survey the earth's magnetic field

NASA Technical Reports Server (NTRS)

Mobley, F. F.; Eckard, L. D.; Fountain, G. H.; Ousley, G. W.

1980-01-01

The Magsat satellite was launched on Oct. 30, 1979 into a sun-synchronous dawn-dusk orbit, of 97 deg inclination, 350 km perigee, and 550 km apogee. It contains a precision vector magnetometer and a cesium-vapor scalar magnetometer at the end of a 6-m long graphite epoxy scissors boom. The magnetometers are accurate to 2 nanotesla. A pair of star cameras are used to define the body orientation to 10 arc sec rms. An 'attitude transfer system' measures the orientation of the magnetometer sensors relative to the star cameras to approximately 5 arc sec rms. The satellite position is determined to 70 meters rms by Doppler tracking. The overall objective is to determine each component of the earth's vector magnetic field to an accuracy of 6 nanotesla rms. The Magsat satellite gathers a complete picture of the earth's magnetic field every 12 hours. The vector components are sampled 16 times per second with a resolution of 0.5 nanotesla. The data will be used by the U.S. Geological Survey to prepare 1980 world magnetic field charts and to detect large-scale magnetic anomalies in the earth's crust for use in planning resource exploration strategy.

Ponderomotive Force in the Presence of Electric Fields

NASA Technical Reports Server (NTRS)

Khazanov, G. V.; Krivorutsky, E. N.

2013-01-01

This paper presents averaged equations of particle motion in an electromagnetic wave of arbitrary frequency with its wave vector directed along the ambient magnetic field. The particle is also subjected to an E cross B drift and a background electric field slowly changing in space and acting along the magnetic field line. The fields, wave amplitude, and the wave vector depend on the coordinate along the magnetic field line. The derivations of the ponderomotive forces are done by assuming that the drift velocity in the ambient magnetic field is comparable to the particle velocity. Such a scenario leads to new ponderomotive forces, dependent on the wave magnetic field intensity, and, as a result, to the additional energy exchange between the wave and the plasma particles. It is found that the parallel electric field can lead to the change of the particle-wave energy exchange rate comparable to that produced by the previously discussed ponderomotive forces.

Electricity Load Forecasting Using Support Vector Regression with Memetic Algorithms

PubMed Central

Hu, Zhongyi; Xiong, Tao

2013-01-01

Electricity load forecasting is an important issue that is widely explored and examined in power systems operation literature and commercial transactions in electricity markets literature as well. Among the existing forecasting models, support vector regression (SVR) has gained much attention. Considering the performance of SVR highly depends on its parameters; this study proposed a firefly algorithm (FA) based memetic algorithm (FA-MA) to appropriately determine the parameters of SVR forecasting model. In the proposed FA-MA algorithm, the FA algorithm is applied to explore the solution space, and the pattern search is used to conduct individual learning and thus enhance the exploitation of FA. Experimental results confirm that the proposed FA-MA based SVR model can not only yield more accurate forecasting results than the other four evolutionary algorithms based SVR models and three well-known forecasting models but also outperform the hybrid algorithms in the related existing literature. PMID:24459425

Electricity load forecasting using support vector regression with memetic algorithms.

PubMed

Hu, Zhongyi; Bao, Yukun; Xiong, Tao

2013-01-01

Electricity load forecasting is an important issue that is widely explored and examined in power systems operation literature and commercial transactions in electricity markets literature as well. Among the existing forecasting models, support vector regression (SVR) has gained much attention. Considering the performance of SVR highly depends on its parameters; this study proposed a firefly algorithm (FA) based memetic algorithm (FA-MA) to appropriately determine the parameters of SVR forecasting model. In the proposed FA-MA algorithm, the FA algorithm is applied to explore the solution space, and the pattern search is used to conduct individual learning and thus enhance the exploitation of FA. Experimental results confirm that the proposed FA-MA based SVR model can not only yield more accurate forecasting results than the other four evolutionary algorithms based SVR models and three well-known forecasting models but also outperform the hybrid algorithms in the related existing literature.

Stokes' theorem, gauge symmetry and the time-dependent Aharonov-Bohm effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Macdougall, James, E-mail: jbm34@mail.fresnostate.edu; Singleton, Douglas, E-mail: dougs@csufresno.edu

2014-04-15

Stokes' theorem is investigated in the context of the time-dependent Aharonov-Bohm effect—the two-slit quantum interference experiment with a time varying solenoid between the slits. The time varying solenoid produces an electric field which leads to an additional phase shift which is found to exactly cancel the time-dependent part of the usual magnetic Aharonov-Bohm phase shift. This electric field arises from a combination of a non-single valued scalar potential and/or a 3-vector potential. The gauge transformation which leads to the scalar and 3-vector potentials for the electric field is non-single valued. This feature is connected with the non-simply connected topology ofmore » the Aharonov-Bohm set-up. The non-single valued nature of the gauge transformation function has interesting consequences for the 4-dimensional Stokes' theorem for the time-dependent Aharonov-Bohm effect. An experimental test of these conclusions is proposed.« less

Interaction and Impact Studies for Distributed Energy Resource, Transactive Energy, and Electric Grid, using High Performance Computing ?based Modeling and Simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kelley, B. M.

The electric utility industry is undergoing significant transformations in its operation model, including a greater emphasis on automation, monitoring technologies, and distributed energy resource management systems (DERMS). With these changes and new technologies, while driving greater efficiencies and reliability, these new models may introduce new vectors of cyber attack. The appropriate cybersecurity controls to address and mitigate these newly introduced attack vectors and potential vulnerabilities are still widely unknown and performance of the control is difficult to vet. This proposal argues that modeling and simulation (M&S) is a necessary tool to address and better understand these problems introduced by emergingmore » technologies for the grid. M&S will provide electric utilities a platform to model its transmission and distribution systems and run various simulations against the model to better understand the operational impact and performance of cybersecurity controls.« less

Retaining {1 0 0} texture from initial columnar grains in 6.5 wt% Si electrical steels

NASA Astrophysics Data System (ADS)

Liang, Ruiyang; Yang, Ping; Mao, Weimin

2017-11-01

6.5 wt% Si electrical steel is a superior soft magnetic material with excellent magnetic properties which highly depends on texture. In this study, based on the heredity of 〈0 0 1〉 orientation in columnar grains, columnar grains are used as the initial material to prepare non-oriented 6.5 wt% Si electrical steel with excellent magnetic properties. EBSD and XRD techniques are adopted to explore the structure and texture evolution during hot rolling, warm rolling, cold rolling and annealing. The results show that, due to the heredity of "structure and texture" from the initial strong {1 0 0} columnar grains, annealed sheet with {1 0 0}〈0 0 1〉 texture had better magnetic properties, which can be used as non-oriented high-silicon electrical steel. Both preferred cube grain nucleation in deformed {1 1 3}〈3 6 1〉 grains in subsurface and coarse {1 0 0}〈0 0 1〉 deformed grains in center layer show the effect of initial columnar grains with {1 0 0} texture.

Industrial Education. Electricity/Electronics Curriculum Guide, Phase II. Instructional Modules, Level I (9 Week).

ERIC Educational Resources Information Center

Lillo, Robert E.; Soffiotto, Nicholas S.

Designed for students in grades 7 and 8, this electricity/electronics curriculum guide contains instructional modules for ten units of instruction (nine-week class): (1) orientation; (2) understanding electricity; (3) safety; (4) methods to generate electricity; (5) wiring tools and wire; (6) soldering; (7) magnetism and electromagnetism; (8)…

Industrial Education. Electricity/Electronics Curriculum Guide, Phase II. Instructional Modules, Level I (18 Week).

ERIC Educational Resources Information Center

Lillo, Robert E.; Soffiotto, Nicholas S.

Designed for students in grades 7 and 8, this electricity/electronics curriculum guide contains instructional modules for twelve units of instruction: (1) orientation; (2) understanding electricity; (3) safety; (4) methods to generate electricity; (5) wiring tools and wire; (6) soldering; (7) magnetism and electromagnetism; (8) circuits, symbols,…

Conductive network formation of carbon nanotubes in elastic polymer microfibers and its effect on the electrical conductance: Experiment and simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, Hyun Woo; Kim, Jeongmin; Sung, Bong June, E-mail: jjpark@chonnam.ac.kr, E-mail: bjsung@sogang.ac.kr

We investigate how the electrical conductance of microfibers (made of polymers and conductive nanofillers) decreases upon uniaxial deformation by performing both experiments and simulations. Even though various elastic conductors have been developed due to promising applications for deformable electronic devices, the mechanism at a molecular level for electrical conductance change has remained elusive. Previous studies proposed that the decrease in electrical conductance would result from changes in either distances or contact numbers between conductive fillers. In this work, we prepare microfibers of single walled carbon nanotubes (SWCNTs)/polyvinyl alcohol composites and investigate the electrical conductance and the orientation of SWCNTs uponmore » uniaxial deformation. We also perform extensive Monte Carlo simulations, which reproduce experimental results for the relative decrease in conductance and the SWCNTs orientation. We investigate the electrical networks of SWCNTs in microfibers and find that the decrease in the electrical conductance upon uniaxial deformation should be attributed to a subtle change in the topological structure of the electrical network.« less

Atlas of optimal coil orientation and position for TMS: A computational study.

PubMed

Gomez-Tames, Jose; Hamasaka, Atsushi; Laakso, Ilkka; Hirata, Akimasa; Ugawa, Yoshikazu

2018-04-17

Transcranial magnetic stimulation (TMS) activates target brain structures in a non-invasive manner. The optimal orientation of the TMS coil for the motor cortex is well known and can be estimated using motor evoked potentials. However, there are no easily measurable responses for activation of other cortical areas and the optimal orientation for these areas is currently unknown. This study investigated the electric field strength, optimal coil orientation, and relative locations to optimally stimulate the target cortex based on computed electric field distributions. A total of 518,616 stimulation scenarios were studied using realistic head models (2401 coil locations × 12 coil angles × 18 head models). Inter-subject registration methods were used to generate an atlas of optimized TMS coil orientations on locations on the standard brain. We found that the maximum electric field strength is greater in primary somatosensory cortex and primary motor cortex than in other cortical areas. Additionally, a universal optimal coil orientation applicable to most subjects is more feasible at the primary somatosensory cortex and primary motor cortex. We confirmed that optimal coil angle follows the anatomical shape of the hand motor area to realize personalized optimization of TMS. Finally, on average, the optimal coil positions for TMS on the scalp deviated 5.5 mm from the scalp points with minimum cortex-scalp distance. This deviation was minimal at the premotor cortex and primary motor cortex. Personalized optimal coil orientation is preferable for obtaining the most effective stimulation. Copyright © 2018. Published by Elsevier Inc.

Towards human behavior recognition based on spatio temporal features and support vector machines

NASA Astrophysics Data System (ADS)

Ghabri, Sawsen; Ouarda, Wael; Alimi, Adel M.

2017-03-01

Security and surveillance are vital issues in today's world. The recent acts of terrorism have highlighted the urgent need for efficient surveillance. There is indeed a need for an automated system for video surveillance which can detect identity and activity of person. In this article, we propose a new paradigm to recognize an aggressive human behavior such as boxing action. Our proposed system for human activity detection includes the use of a fusion between Spatio Temporal Interest Point (STIP) and Histogram of Oriented Gradient (HoG) features. The novel feature called Spatio Temporal Histogram Oriented Gradient (STHOG). To evaluate the robustness of our proposed paradigm with a local application of HoG technique on STIP points, we made experiments on KTH human action dataset based on Multi Class Support Vector Machines classification. The proposed scheme outperforms basic descriptors like HoG and STIP to achieve 82.26% us an accuracy value of classification rate.

Customer demand prediction of service-oriented manufacturing using the least square support vector machine optimized by particle swarm optimization algorithm

NASA Astrophysics Data System (ADS)

Cao, Jin; Jiang, Zhibin; Wang, Kangzhou

2017-07-01

Many nonlinear customer satisfaction-related factors significantly influence the future customer demand for service-oriented manufacturing (SOM). To address this issue and enhance the prediction accuracy, this article develops a novel customer demand prediction approach for SOM. The approach combines the phase space reconstruction (PSR) technique with the optimized least square support vector machine (LSSVM). First, the prediction sample space is reconstructed by the PSR to enrich the time-series dynamics of the limited data sample. Then, the generalization and learning ability of the LSSVM are improved by the hybrid polynomial and radial basis function kernel. Finally, the key parameters of the LSSVM are optimized by the particle swarm optimization algorithm. In a real case study, the customer demand prediction of an air conditioner compressor is implemented. Furthermore, the effectiveness and validity of the proposed approach are demonstrated by comparison with other classical predication approaches.

Polarimetric signatures of a coniferous forest canopy based on vector radiative transfer theory

NASA Technical Reports Server (NTRS)

Karam, M. A.; Fung, A. K.; Amar, F.; Mougin, E.; Lopes, A.; Beaudoin, A.

1992-01-01

Complete polarization signatures of a coniferous forest canopy are studied by the iterative solution of the vector radiative transfer equations up to the second order. The forest canopy constituents (leaves, branches, stems, and trunk) are embedded in a multi-layered medium over a rough interface. The branches, stems and trunk scatterers are modeled as finite randomly oriented cylinders. The leaves are modeled as randomly oriented needles. For a plane wave exciting the canopy, the average Mueller matrix is formulated in terms of the iterative solution of the radiative transfer solution and used to determine the linearly polarized backscattering coefficients, the co-polarized and cross-polarized power returns, and the phase difference statistics. Numerical results are presented to investigate the effect of transmitting and receiving antenna configurations on the polarimetric signature of a pine forest. Comparison is made with measurements.

Shallow-trap-induced positive absorptive two-beam coupling 'gain' and light-induced transparency in nominally undoped barium titanate

NASA Technical Reports Server (NTRS)

Garrett, M. H.; Tayebati, P.; Chang, J. Y.; Jenssen, H. P.; Warde, C.

1992-01-01

The asymmetry of beam coupling with respect to the orientation of the polar axis in a nominally undoped barium titanate crystal is used to determine the electro-optic and absorptive 'gain' in the usual beam-coupling geometry. For small grating wave vectors, the electrooptic coupling vanishes but the absorptive coupling remains finite and positive. Positive absorptive coupling at small grating wave vectors is correlated with the light-induced transparency of the crystal described herein. The intensity and grating wave vector dependence of the electrooptic and absorptive coupling, and the light-induced transparency are consistent with a model incorporating deep and shallow levels.

Method for multi-axis, non-contact mixing of magnetic particle suspensions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, James E.; Solis, Kyle J.

Continuous, three-dimensional control of the vorticity vector is possible by progressively transitioning the field symmetry by applying or removing a dc bias along one of the principal axes of mutually orthogonal alternating fields. By exploiting this transition, the vorticity vector can be oriented in a wide range of directions that comprise all three spatial dimensions. Detuning one or more field components to create phase modulation causes the vorticity vector to trace out complex orbits of a wide variety, creating very robust multiaxial stirring. This multiaxial, non-contact stirring is particularly attractive for applications where the fluid volume has complex boundaries, ormore » is congested.« less

Adding localization information in a fingerprint binary feature vector representation

NASA Astrophysics Data System (ADS)

Bringer, Julien; Despiegel, Vincent; Favre, Mélanie

2011-06-01

At BTAS'10, a new framework to transform a fingerprint minutiae template into a binary feature vector of fixed length is described. A fingerprint is characterized by its similarity with a fixed number set of representative local minutiae vicinities. This approach by representative leads to a fixed length binary representation, and, as the approach is local, it enables to deal with local distortions that may occur between two acquisitions. We extend this construction to incorporate additional information in the binary vector, in particular on localization of the vicinities. We explore the use of position and orientation information. The performance improvement is promising for utilization into fast identification algorithms or into privacy protection algorithms.

Physically Damped Noise Canceling Hydrophone

DTIC Science & Technology

2016-06-24

Description of the Prior Art [0004] An acoustic hydrophone can transfer underwater pressure waves to electrical energy. As a result, an output charge...includes two types of piezoelectric transducers coupled together. One transducer maintains voids and is sensitive to hydrostatic acoustic signals. The...the cable assembly. [0009] Cray (United States Patent No. 6,370,084) discloses an acoustic vector sensor. An accelerometer of the acoustic vector

Oriented Polar Molecules in a Solid Inert-Gas Matrix: A Proposed Method for Measuring the Electric Dipole Moment of the Electron

NASA Astrophysics Data System (ADS)

Vutha, A.; Horbatsch, M.; Hessels, E.

2018-01-01

We propose a very sensitive method for measuring the electric dipole moment of the electron using polar molecules embedded in a cryogenic solid matrix of inert-gas atoms. The polar molecules can be oriented in the $\\hat{\\rm{z}}$ direction by an applied electric field, as has recently been demonstrated by Park, et al. [Angewandte Chemie {\\bf 129}, 1066 (2017)]. The trapped molecules are prepared into a state which has its electron spin perpendicular to $\\hat{\\rm{z}}$, and a magnetic field along $\\hat{\\rm{z}}$ causes precession of this spin. An electron electric dipole moment $d_e$ would affect this precession due to the up to 100~GV/cm effective electric field produced by the polar molecule. The large number of polar molecules that can be embedded in a matrix, along with the expected long coherence times for the precession, allows for the possibility of measuring $d_e$ to an accuracy that surpasses current measurements by many orders of magnitude. Because the matrix can inhibit molecular rotations and lock the orientation of the polar molecules, it may not be necessary to have an electric field present during the precession. The proposed technique can be applied using a variety of polar molecules and inert gases, which, along with other experimental variables, should allow for careful study of systematic uncertainties in the measurement.

Electrical and Self-Sensing Properties of Ultra-High-Performance Fiber-Reinforced Concrete with Carbon Nanotubes

PubMed Central

You, Ilhwan; Yoo, Doo-Yeol; Kim, Soonho; Kim, Min-Jae; Zi, Goangseup

2017-01-01

This study examined the electrical and self-sensing capacities of ultra-high-performance fiber-reinforced concrete (UHPFRC) with and without carbon nanotubes (CNTs). For this, the effects of steel fiber content, orientation, and pore water content on the electrical and piezoresistive properties of UHPFRC without CNTs were first evaluated. Then, the effect of CNT content on the self-sensing capacities of UHPFRC under compression and flexure was investigated. Test results indicated that higher steel fiber content, better fiber orientation, and higher amount of pore water led to higher electrical conductivity of UHPFRC. The effects of fiber orientation and drying condition on the electrical conductivity became minor as sufficiently high amount of steel fibers, 3% by volume, was added. Including only steel fibers did not impart UHPFRC with piezoresistive properties. Addition of CNTs substantially improved the electrical conductivity of UHPFRC. Under compression, UHPFRC with a CNT content of 0.3% or greater had a self-sensing ability that was activated by the formation of cracks, and better sensing capacity was achieved by including greater amount of CNTs. Furthermore, the pre-peak flexural behavior of UHPFRC was precisely simulated with a fractional change in resistivity when 0.3% CNTs were incorporated. The pre-cracking self-sensing capacity of UHPFRC with CNTs was more effective under tensile stress state than under compressive stress state. PMID:29109388

Electrical and Self-Sensing Properties of Ultra-High-Performance Fiber-Reinforced Concrete with Carbon Nanotubes.

PubMed

You, Ilhwan; Yoo, Doo-Yeol; Kim, Sooho; Kim, Min-Jae; Zi, Goangseup

2017-10-29

This study examined the electrical and self-sensing capacities of ultra-high-performance fiber-reinforced concrete (UHPFRC) with and without carbon nanotubes (CNTs). For this, the effects of steel fiber content, orientation, and pore water content on the electrical and piezoresistive properties of UHPFRC without CNTs were first evaluated. Then, the effect of CNT content on the self-sensing capacities of UHPFRC under compression and flexure was investigated. Test results indicated that higher steel fiber content, better fiber orientation, and higher amount of pore water led to higher electrical conductivity of UHPFRC. The effects of fiber orientation and drying condition on the electrical conductivity became minor as sufficiently high amount of steel fibers, 3% by volume, was added. Including only steel fibers did not impart UHPFRC with piezoresistive properties. Addition of CNTs substantially improved the electrical conductivity of UHPFRC. Under compression, UHPFRC with a CNT content of 0.3% or greater had a self-sensing ability that was activated by the formation of cracks, and better sensing capacity was achieved by including greater amount of CNTs. Furthermore, the pre-peak flexural behavior of UHPFRC was precisely simulated with a fractional change in resistivity when 0.3% CNTs were incorporated. The pre-cracking self-sensing capacity of UHPFRC with CNTs was more effective under tensile stress state than under compressive stress state.

Photorefractive Tungsten Bronze Crystals for Optical Limiters and Filters.

DTIC Science & Technology

1996-01-01

vector , X is the laser light wavelength, 0 is the half- angle between the two crossing laser beams, and k0 is the Debye screening wave vector given by...between the grating and the dielectric constant E’ = 950) such that the grating’ vector is interference pattern, the intensities of the output beams from...substituting Io, I, and Id into expression 0 ple d 2o0o 25i00 (8), we can calculate the phase shift between the grating and Applied Electric Feild in V

On three-dimensional misorientation spaces.

PubMed

Krakow, Robert; Bennett, Robbie J; Johnstone, Duncan N; Vukmanovic, Zoja; Solano-Alvarez, Wilberth; Lainé, Steven J; Einsle, Joshua F; Midgley, Paul A; Rae, Catherine M F; Hielscher, Ralf

2017-10-01

Determining the local orientation of crystals in engineering and geological materials has become routine with the advent of modern crystallographic mapping techniques. These techniques enable many thousands of orientation measurements to be made, directing attention towards how such orientation data are best studied. Here, we provide a guide to the visualization of misorientation data in three-dimensional vector spaces, reduced by crystal symmetry, to reveal crystallographic orientation relationships. Domains for all point group symmetries are presented and an analysis methodology is developed and applied to identify crystallographic relationships, indicated by clusters in the misorientation space, in examples from materials science and geology. This analysis aids the determination of active deformation mechanisms and evaluation of cluster centres and spread enables more accurate description of transformation processes supporting arguments regarding provenance.

On three-dimensional misorientation spaces

NASA Astrophysics Data System (ADS)

Krakow, Robert; Bennett, Robbie J.; Johnstone, Duncan N.; Vukmanovic, Zoja; Solano-Alvarez, Wilberth; Lainé, Steven J.; Einsle, Joshua F.; Midgley, Paul A.; Rae, Catherine M. F.; Hielscher, Ralf

2017-10-01

Determining the local orientation of crystals in engineering and geological materials has become routine with the advent of modern crystallographic mapping techniques. These techniques enable many thousands of orientation measurements to be made, directing attention towards how such orientation data are best studied. Here, we provide a guide to the visualization of misorientation data in three-dimensional vector spaces, reduced by crystal symmetry, to reveal crystallographic orientation relationships. Domains for all point group symmetries are presented and an analysis methodology is developed and applied to identify crystallographic relationships, indicated by clusters in the misorientation space, in examples from materials science and geology. This analysis aids the determination of active deformation mechanisms and evaluation of cluster centres and spread enables more accurate description of transformation processes supporting arguments regarding provenance.

Attitude control study for a large flexible spacecraft using a Solar Electric Propulsion System (SEPS)

NASA Technical Reports Server (NTRS)

Tolivar, A. F.; Key, R. W.

1980-01-01

The attitude control performance of the solar electric propulsion system (SEPS) was evaluated. A thrust vector control system for powered flight control was examined along with a gas jet reaction control system, and a reaction wheel system, both of which have been proposed for nonpowered flight control. Comprehensive computer simulations of each control system were made and evaluated using a 30 mode spacecraft model. Results obtained indicate that thrust vector control and reaction wheel systems offer acceptable smooth proportional control. The gas jet control system is shown to be risky for a flexible structure such as SEPS, and is therefore, not recommended as a primary control method.

Poynting-vector based method for determining the bearing and location of electromagnetic sources

DOEpatents

Simons, David J.; Carrigan, Charles R.; Harben, Philip E.; Kirkendall, Barry A.; Schultz, Craig A.

2008-10-21

A method and apparatus is utilized to determine the bearing and/or location of sources, such as, alternating current (A.C.) generators and loads, power lines, transformers and/or radio-frequency (RF) transmitters, emitting electromagnetic-wave energy for which a Poynting-Vector can be defined. When both a source and field sensors (electric and magnetic) are static, a bearing to the electromagnetic source can be obtained. If a single set of electric (E) and magnetic (B) sensors are in motion, multiple measurements permit location of the source. The method can be extended to networks of sensors allowing determination of the location of both stationary and moving sources.

O Electromagnetic Power Waves and Power Density Components.

NASA Astrophysics Data System (ADS)

Petzold, Donald Wayne

1980-12-01

On January 10, 1884 Lord Rayleigh presented a paper entitled "On the Transfer of Energy in the Electromagnetic Field" to the Royal Society of London. This paper had been authored by the late Fellow of Trinity College, Cambridge, Professor J. H. Poynting and in it he claimed that there was a general law for the transfer of electromagnetic energy. He argued that associated with each point in space is a quantity, that has since been called the Poynting vector, that is a measure of the rate of energy flow per unit area. His analysis was concerned with the integration of this power density vector at all points over an enclosing surface of a specific volume. The interpretation of this Poynting vector as a true measure of the local power density was viewed with great skepticism unless the vector was integrated over a closed surface, as the development of the concept required. However, within the last decade or so Shadowitz indicates that a number of prominent authors have argued that the criticism of the interpretation of Poynting's vector as a local power density vector is unjustified. The present paper is not concerned with these arguments but instead is concerned with a decomposition of Poynting's power density vector into two and only two components: one vector which has the same direction as Poynting's vector and which is called the forward power density vector, and another vector, directed opposite to the Poynting vector and called the reverse power density vector. These new local forward and reverse power density vectors will be shown to be dependent upon forward and reverse power wave vectors and these vectors in turn will be related to newly defined forward and reverse components of the electric and magnetic fields. The sum of these forward and reverse power density vectors, which is simply the original Poynting vector, is associated with the total electromagnetic energy traveling past the local point. Another vector which is the difference between the forward and reverse power density vectors and which will be shown to be associated with the total electric and magnetic field energy densities existing at a local point will also be introduced. These local forward and reverse power density vectors may be integrated over a surface to determine the forward and reverse powers and from these results problems related to maximum power transfer or efficiency of electromagnetic energy transmission in space may be studied in a manner similar to that presently being done with transmission lines, wave guides, and more recently with two port multiport lumped parameter systems. These new forward and reverse power density vectors at a point in space are analogous to the forward and revoltages or currents and power waves as used with the transmission line, waveguide, or port. These power wave vectors in space are a generalization of the power waves as developed by Penfield, Youla, and Kurokawa and used with the scattering parameters associated with transmission lines, waveguides and ports.

An object-oriented approach to nested data parallelism

NASA Technical Reports Server (NTRS)

Sheffler, Thomas J.; Chatterjee, Siddhartha

1994-01-01

This paper describes an implementation technique for integrating nested data parallelism into an object-oriented language. Data-parallel programming employs sets of data called 'collections' and expresses parallelism as operations performed over the elements of a collection. When the elements of a collection are also collections, then there is the possibility for 'nested data parallelism.' Few current programming languages support nested data parallelism however. In an object-oriented framework, a collection is a single object. Its type defines the parallel operations that may be applied to it. Our goal is to design and build an object-oriented data-parallel programming environment supporting nested data parallelism. Our initial approach is built upon three fundamental additions to C++. We add new parallel base types by implementing them as classes, and add a new parallel collection type called a 'vector' that is implemented as a template. Only one new language feature is introduced: the 'foreach' construct, which is the basis for exploiting elementwise parallelism over collections. The strength of the method lies in the compilation strategy, which translates nested data-parallel C++ into ordinary C++. Extracting the potential parallelism in nested 'foreach' constructs is called 'flattening' nested parallelism. We show how to flatten 'foreach' constructs using a simple program transformation. Our prototype system produces vector code which has been successfully run on workstations, a CM-2, and a CM-5.

Thermally Stable, Piezoelectric and Pyroelectric Polymeric Substrates and Method Relating Thereto

NASA Technical Reports Server (NTRS)

Simpson, Joycelyn O. (Inventor); St.Clair, Terry L. (Inventor)

1995-01-01

Production of an electric voltage in response to mechanical excitation (piezoelectricity) or thermal excitation (pyroelectricity) requires a material to have a preferred dipole orientation in its structure. This preferred orientation or polarization occurs naturally in some crystals such as quartz and can be induced into some ceramic and polymeric materials by application of strong electric or mechanical fields. For some materials, a combination of mechanical and electrical orientation is necessary to completely polarize the material. The only commercially available piezoelectric polymer is poly(vinylidene fluoride) (PVF2). However, this polymer has material and process limitations which prohibit its use in numerous device applications where thermal stability is a requirement. By the present invention, thermally stable, piezoelectric and pyroelectric polymeric substrates were prepared from polymers having a softening temperature greater than 1000C. A metal electrode material is deposited onto the polymer substrate and several electrical leads are attached to it. The polymer substrate is heated in a low dielectric medium to enhance molecular mobility of the polymer chains. A voltage is then applied to the polymer substrate inducing polarization. The voltage is then maintained while the polymer substrate is cooled 'freezing in' the molecular orientation. The novelty of the invention resides in the process of preparing the piezoelectric and pyroelectric polymeric substrate. The nonobviousness of the invention is found in heating the polymeric substrate in a low dielectric medium while applying a voltage.

Theory of electrical conductivity and dielectric permittivity of highly aligned graphene-based nanocomposites.

PubMed

Xia, Xiaodong; Hao, Jia; Wang, Yang; Zhong, Zheng; Weng, George J

2017-05-24

Highly aligned graphene-based nanocomposites are of great interest due to their excellent electrical properties along the aligned direction. Graphene fillers in these composites are not necessarily perfectly aligned, but their orientations are highly confined to a certain angle, [Formula: see text] with 90° giving rise to the randomly oriented state and 0° to the perfectly aligned one. Recent experiments have shown that electrical conductivity and dielectric permittivity of highly aligned graphene-polymer nanocomposites are strongly dependent on this distribution angle, but at present no theory seems to exist to address this issue. In this work we present a new effective-medium theory that is derived from the underlying physical process including the effects of graphene orientation, filler loading, aspect ratio, percolation threshold, interfacial tunneling, and Maxwell-Wagner-Sillars polarization, to determine these two properties. The theory is formulated in the context of preferred orientational average. We highlight this new theory with an application to rGO/epoxy nanocomposites, and demonstrate that the calculated in-plane and out-of-plane conductivity and permittivity are in agreement with the experimental data as the range of graphene orientations changes from the randomly oriented to the highly aligned state. We also show that the percolation thresholds of highly aligned graphene nanocomposites are in general different along the planar and the normal directions, but they converge into a single one when the statistical distribution of graphene fillers is spherically symmetric.

Method of using an electric field controlled emulsion phase contactor

DOEpatents

Scott, T.C.

1993-11-16

A system is described for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity. 5 figures.

Biodiversity can help prevent malaria outbreaks in tropical forests.

PubMed

Laporta, Gabriel Zorello; Lopez de Prado, Paulo Inácio Knegt; Kraenkel, Roberto André; Coutinho, Renato Mendes; Sallum, Maria Anice Mureb

2013-01-01

Plasmodium vivax is a widely distributed, neglected parasite that can cause malaria and death in tropical areas. It is associated with an estimated 80-300 million cases of malaria worldwide. Brazilian tropical rain forests encompass host- and vector-rich communities, in which two hypothetical mechanisms could play a role in the dynamics of malaria transmission. The first mechanism is the dilution effect caused by presence of wild warm-blooded animals, which can act as dead-end hosts to Plasmodium parasites. The second is diffuse mosquito vector competition, in which vector and non-vector mosquito species compete for blood feeding upon a defensive host. Considering that the World Health Organization Malaria Eradication Research Agenda calls for novel strategies to eliminate malaria transmission locally, we used mathematical modeling to assess those two mechanisms in a pristine tropical rain forest, where the primary vector is present but malaria is absent. The Ross-Macdonald model and a biodiversity-oriented model were parameterized using newly collected data and data from the literature. The basic reproduction number ([Formula: see text]) estimated employing Ross-Macdonald model indicated that malaria cases occur in the study location. However, no malaria cases have been reported since 1980. In contrast, the biodiversity-oriented model corroborated the absence of malaria transmission. In addition, the diffuse competition mechanism was negatively correlated with the risk of malaria transmission, which suggests a protective effect provided by the forest ecosystem. There is a non-linear, unimodal correlation between the mechanism of dead-end transmission of parasites and the risk of malaria transmission, suggesting a protective effect only under certain circumstances (e.g., a high abundance of wild warm-blooded animals). To achieve biological conservation and to eliminate Plasmodium parasites in human populations, the World Health Organization Malaria Eradication Research Agenda should take biodiversity issues into consideration.

Control of Rydberg atom blockade by dc electric field orientation in a quasi-one-dimensional sample

NASA Astrophysics Data System (ADS)

Goncalves, Luís Felipe; Marcassa, Luis Gustavo

2017-04-01

Rydberg atoms posse a strong atom-atom interaction, which limits its density in an atomic sample. Such effect is known as Rydberg atom blockade. Here, we present a novel way to control such effect by direct orienting the induced atomic dipole moment using a dc external electrical field. To demonstrate it, we excite the 50S1 / 2 Rb atomic state in a quasi-one-dimensional sample held in a quasi-electrostatic trap. A pure nS state holds only van der Waals interaction at long range, but in the presence of an external electric field the state mixing leads to strong dipole-dipole interactions. We have measured the Rydberg atom population as a function of ground state atoms density for several angles between the electric field and the main axis of the unidimensional sample. The results indicate that the limit on the final Rydberg density can be controlled by electric field orientation. Besides, we have characterized the sample by using direct spatial ion imaging, demonstrating that it does behave as an unidimensional sample. This work was supported by Sao Paulo Research Foundation (FAPESP) Grants No. 2011/22309-8 and No. 2013/02816- 8, the U.S. Army Research Office Grant No. W911NF-15-1-0638 and CNPq.

Central neural coding of sky polarization in insects.

PubMed

Homberg, Uwe; Heinze, Stanley; Pfeiffer, Keram; Kinoshita, Michiyo; el Jundi, Basil

2011-03-12

Many animals rely on a sun compass for spatial orientation and long-range navigation. In addition to the Sun, insects also exploit the polarization pattern and chromatic gradient of the sky for estimating navigational directions. Analysis of polarization-vision pathways in locusts and crickets has shed first light on brain areas involved in sky compass orientation. Detection of sky polarization relies on specialized photoreceptor cells in a small dorsal rim area of the compound eye. Brain areas involved in polarization processing include parts of the lamina, medulla and lobula of the optic lobe and, in the central brain, the anterior optic tubercle, the lateral accessory lobe and the central complex. In the optic lobe, polarization sensitivity and contrast are enhanced through convergence and opponency. In the anterior optic tubercle, polarized-light signals are integrated with information on the chromatic contrast of the sky. Tubercle neurons combine responses to the UV/green contrast and e-vector orientation of the sky and compensate for diurnal changes of the celestial polarization pattern associated with changes in solar elevation. In the central complex, a topographic representation of e-vector tunings underlies the columnar organization and suggests that this brain area serves as an internal compass coding for spatial directions.

Central neural coding of sky polarization in insects

PubMed Central

Homberg, Uwe; Heinze, Stanley; Pfeiffer, Keram; Kinoshita, Michiyo; el Jundi, Basil

2011-01-01

Many animals rely on a sun compass for spatial orientation and long-range navigation. In addition to the Sun, insects also exploit the polarization pattern and chromatic gradient of the sky for estimating navigational directions. Analysis of polarization–vision pathways in locusts and crickets has shed first light on brain areas involved in sky compass orientation. Detection of sky polarization relies on specialized photoreceptor cells in a small dorsal rim area of the compound eye. Brain areas involved in polarization processing include parts of the lamina, medulla and lobula of the optic lobe and, in the central brain, the anterior optic tubercle, the lateral accessory lobe and the central complex. In the optic lobe, polarization sensitivity and contrast are enhanced through convergence and opponency. In the anterior optic tubercle, polarized-light signals are integrated with information on the chromatic contrast of the sky. Tubercle neurons combine responses to the UV/green contrast and e-vector orientation of the sky and compensate for diurnal changes of the celestial polarization pattern associated with changes in solar elevation. In the central complex, a topographic representation of e-vector tunings underlies the columnar organization and suggests that this brain area serves as an internal compass coding for spatial directions. PMID:21282171

A simple device to illustrate the Einthoven triangle.

PubMed

Jin, Benjamin E; Wulff, Heike; Widdicombe, Jonathan H; Zheng, Jie; Bers, Donald M; Puglisi, Jose L

2012-12-01

The Einthoven triangle is central to the field of electrocardiography, but the concept of cardiac vectors is often a difficult notion for students to grasp. To illustrate this principle, we constructed a device that recreates the conditions of an ECG reading using a battery to simulate the electrical vector of the heart and three voltmeters for the main electrocardiographic leads. Requiring minimal construction with low cost, this device provides hands-on practice that enables students to rediscover the principles of the Einthoven triangle, namely, that the direction of the cardiac dipole can be predicted from the deflections in any two leads and that lead I + lead III = lead II independent of the position of heart's electrical vector. We built a total of 6 devices for classes of 30 students and tested them in the first-year Human Physiology course at the University of California-Davis School of Medicine. Combined with traditional demonstrations with ECG machines, this equipment demonstrated its ability to help medical students obtain a solid foundation of the basic principles of electrocardiography.

Localization of thermal anomalies in electrical equipment using Infrared Thermography and support vector machine

NASA Astrophysics Data System (ADS)

Laib dit Leksir, Y.; Mansour, M.; Moussaoui, A.

2018-03-01

Analysis and processing of databases obtained from infrared thermal inspections made on electrical installations require the development of new tools to obtain more information to visual inspections. Consequently, methods based on the capture of thermal images show a great potential and are increasingly employed in this field. However, there is a need for the development of effective techniques to analyse these databases in order to extract significant information relating to the state of the infrastructures. This paper presents a technique explaining how this approach can be implemented and proposes a system that can help to detect faults in thermal images of electrical installations. The proposed method classifies and identifies the region of interest (ROI). The identification is conducted using support vector machine (SVM) algorithm. The aim here is to capture the faults that exist in electrical equipments during an inspection of some machines using A40 FLIR camera. After that, binarization techniques are employed to select the region of interest. Later the comparative analysis of the obtained misclassification errors using the proposed method with Fuzzy c means and Ostu, has also be addressed.

Tilted hexagonal post arrays: DNA electrophoresis in anisotropic media

PubMed Central

Chen, Zhen; Dorfman, Kevin D.

2013-01-01

Using Brownian dynamics simulations, we show that DNA electrophoresis in a hexagonal array of micron-sized posts changes qualitatively when the applied electric field vector is not coincident with the lattice vectors of the array. DNA electrophoresis in such “tilted” post arrays is superior to the standard “un-tilted” approach; while the time required to achieve a resolution of unity in a tilted post array is similar to an un-tilted array at a low electric field strengths, this time (i) decreases exponentially with electric field strength in a tilted array and (ii) increases exponentially with electric field strength in an un-tilted array. Although the DNA dynamics in a post array are complicated, the electrophoretic mobility results indicate that the “free path”, i.e., the average distance of ballistic trajectories of point sized particles launched from random positions in the unit cell until they intersect the next post, is a useful proxy for the detailed DNA trajectories. The analysis of the free path reveals a fundamental connection between anisotropy of the medium and DNA transport therein that goes beyond simply improving the separation device. PMID:23868490

Real time hardware implementation of power converters for grid integration of distributed generation and STATCOM systems

NASA Astrophysics Data System (ADS)

Jaithwa, Ishan

Deployment of smart grid technologies is accelerating. Smart grid enables bidirectional flows of energy and energy-related communications. The future electricity grid will look very different from today's power system. Large variable renewable energy sources will provide a greater portion of electricity, small DERs and energy storage systems will become more common, and utilities will operate many different kinds of energy efficiency. All of these changes will add complexity to the grid and require operators to be able to respond to fast dynamic changes to maintain system stability and security. This thesis investigates advanced control technology for grid integration of renewable energy sources and STATCOM systems by verifying them on real time hardware experiments using two different systems: d SPACE and OPAL RT. Three controls: conventional, direct vector control and the intelligent Neural network control were first simulated using Matlab to check the stability and safety of the system and were then implemented on real time hardware using the d SPACE and OPAL RT systems. The thesis then shows how dynamic-programming (DP) methods employed to train the neural networks are better than any other controllers where, an optimal control strategy is developed to ensure effective power delivery and to improve system stability. Through real time hardware implementation it is proved that the neural vector control approach produces the fastest response time, low overshoot, and, the best performance compared to the conventional standard vector control method and DCC vector control technique. Finally the entrepreneurial approach taken to drive the technologies from the lab to market via ORANGE ELECTRIC is discussed in brief.

The effect of receiver coil orientations on the imaging performance of magnetic induction tomography

NASA Astrophysics Data System (ADS)

Gürsoy, D.; Scharfetter, H.

2009-10-01

Magnetic induction tomography is an imaging modality which aims to reconstruct the conductivity distribution of the human body. It uses magnetic induction to excite the body and an array of sensor coils to detect the perturbations in the magnetic field. Up to now, much effort has been expended with the aim of finding an efficient coil configuration to extend the dynamic range of the measured signal. However, the merits of different sensor orientations on the imaging performance have not been studied in great detail so far. Therefore, the aim of the study is to fill the void of a systematic investigation of coil orientations on the reconstruction quality of the designs. To this end, a number of alternative receiver array designs with different coil orientations were suggested and the evaluations of the designs were performed based on the singular value decomposition. A generalized class of quality measures, the subclasses of which are linked to both the spatial resolution and uncertainty measures, was used to assess the performance on the radial and axial axes of a cylindrical phantom. The detectability of local conductivity perturbations in the phantom was explored using the reconstructed images. It is possible to draw the conclusion that the proper choice of the coil orientations significantly influences the number of usable singular vectors and accordingly the stability of image reconstruction, although the effect of increased stability on the quality of the reconstructed images was not of paramount importance due to the reduced independent information content of the associated singular vectors.

Modeling spatial tuning of adaptation of the angular vestibulo-ocular reflex

PubMed Central

Yakushin, Sergei B.

2012-01-01

Gain adaptation of the yaw angular vestibular ocular reflex (aVOR) induced in side-down positions has gravity-independent (global) and -dependent (localized) components. When the head oscillation angles are small during adaptation, localized gain changes are maximal in the approximate position of adaptation. Concurrently, polarization vectors of canal–otolith vestibular neurons adapt their orientations during these small-angle adaptation paradigms. Whether there is orientation adaptation with large amplitude head oscillations, when the head is not localized to a specific position, is unknown. Yaw aVOR gains were decreased by oscillating monkeys about a yaw axis in a side-down position in a subject–stationary visual surround for 2 h. Amplitudes of head oscillation ranged from 15° to 180°. The yaw aVOR gain was tested in darkness at 0.5 Hz, with small angles of oscillation (±15°) while upright and in tilted positions. The peak value of the gain change was highly tuned for small angular oscillations during adaptation and significantly broadened with larger oscillation angles during adaptation. When the orientation of the polarization vectors associated with the gravity-dependent component of the neural network model was adapted toward the direction of gravity, it predicted the localized learning for small angles and the broadening when the orientation adaptation was diminished. The model-based analysis suggests that the otolith orientation adaptation plays an important role in the localized behavior of aVOR as a function of gravity and in regulating the relationship between global and localized adaptation. PMID:22660376

Spatial orientation of semicircular canals and afferent sensitivity vectors in pigeons

NASA Technical Reports Server (NTRS)

Dickman, J. D.

1996-01-01

Rotational head motion in vertebrates is detected by the semicircular canal system, whose innervating primary afferent fibers carry information about movement in specific head planes. The semicircular canals have been qualitatively examined over a number of years, and the canal planes have been quantitatively characterized in several animal species. The present study first determined the geometric relationship between individual semicircular canals and between the canals and the stereotactic head planes in pigeons. Stereotactic measurements of multiple points along the circumference of the bony canals were taken, and the measured points fitted with a three-dimensional planar surface. Direction normals to the plane's surface were calculated and used to define angles between semicircular canal pairs. Because of the unusual shape of the anterior semicircular canals in pigeons, two planes, a major and a minor, were fitted to the canal's course. Calculated angle values for all canals indicated that the horizontal and posterior semicircular canals are nearly orthogonal, but the anterior canals have substantial deviations from orthogonality with other canal planes. Next, the responses of the afferent fibers that innervate each of the semicircular canals to 0.5 Hz sinusoidal rotation about an earth-vertical axis were obtained. The head orientation relative to the rotation axis was systematically varied so that directions of maximum sensitivity for each canal afferent could be determined. These sensitivity vectors were then compared with the canal plane direction normals. The afferents that innervated specific semicircular canals formed homogeneous clusters of sensitivity vectors in different head planes. The horizontal and posterior afferents had average sensitivity vectors that were largely co-incident with the innervated canal plane direction normals. Anterior canal afferents, however, appeared to synthesize contributions from the major and minor plane components of the bony canal structure to produce a resultant sensitivity vector that was positioned between the canal planes. Calculated angles between the average canal afferent sensitivity vectors revealed that direction orthogonality is preserved at the afferent signal level, even though deviations from canal plane orthogonality exist.

An alternative clinical routine for subjective refraction based on power vectors with trial frames.

PubMed

María Revert, Antonia; Conversa, Maria Amparo; Albarrán Diego, César; Micó, Vicente

2017-01-01

Subjective refraction determines the final point of refractive error assessment in most clinical environments and its foundations have remained unchanged for decades. The purpose of this paper is to compare the results obtained when monocular subjective refraction is assessed in trial frames by a new clinical procedure based on a pure power vector interpretation with conventional clinical refraction procedures. An alternative clinical routine is described that uses power vector interpretation with implementation in trial frames. Refractive error is determined in terms of: (i) the spherical equivalent (M component), and (ii) a pair of Jackson Crossed Cylinder lenses oriented at 0°/90° (J 0 component) and 45°/135° (J 45 component) for determination of astigmatism. This vector subjective refraction result (VR) is compared separately for right and left eyes of 25 subjects (mean age, 35 ± 4 years) against conventional sphero-cylindrical subjective refraction (RX) using a phoropter. The VR procedure was applied with both conventional tumbling E optotypes (VR1) and modified optotypes with oblique orientation (VR2). Bland-Altman plots and intra-class correlation coefficient showed good agreement between VR, and RX (with coefficient values above 0.82) and anova showed no significant differences in any of the power vector components between RX and VR. VR1 and VR2 procedure results were similar (p ≥ 0.77). The proposed routine determines the three components of refractive error in power vector notation [M, J 0 , J 45 ], with a refraction time similar to the one used in conventional subjective procedures. The proposed routine could be helpful for inexperienced clinicians and for experienced clinicians in those cases where it is difficult to get a valid starting point for conventional RX (irregular corneas, media opacities, etc.) and for refractive situations/places with inadequate refractive facilities/equipment. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

Potassium Loss during Galvanotaxis of Slime Mold

PubMed Central

Anderson, John D.

1962-01-01

The posterior reticulated regions of the plasmodia of the slime mold, Physarum polycephalum, whose migration has been oriented by direct current (3.0 to 5.0 µa/mm2 in the agar substrate), contain 30 per cent less potassium than the advancing non-reticulated region. The anterior regions have the same potassium concentration as that of the controls, approximately 32 meq/kg wet weight. Differences in potassium concentration between anterior and posterior regions of control plasmodia, not oriented by electric current, are less than 5 per cent. Sodium, in contrast to potassium, is generally less concentrated in the anterior than in the posterior regions of electrically oriented plasmodia, but sodium concentrations are extremely variable. No significant difference in protein concentration was found between oriented and control plasmodia. Thirty-five per cent of the total potassium, but none of the sodium, is found in acidified ethanol precipitates from plasmodial homogenates. Potassium, but not sodium, appears to be closely associated with processes which differentiate anterior from posterior in an oriented plasmodium. PMID:13861244

Electric auxiliary power unit for Shuttle evolution

NASA Technical Reports Server (NTRS)

Meyer, Doug; Weber, Kent; Scott, Walter

1989-01-01

The Space Shuttle Orbiter currently uses three hydrazine fueled auxiliary power units (APUs) to provide hydraulic power for the vehicle aerodynamic surface controls, main engine thrust vector control, landing gear, steering, and brakes. Electric auxiliary power units have been proposed as possible replacements to the hydrazine auxiliary power units. Along with the potential advantages, this paper describes an Electric APU configuration and addresses the technical issues and risks associated with the subsystem components. Additionally, characteristics of an Electric APU compared to the existing APU and the direction of future study with respect to the Electric APU is suggested.

Standardized Curriculum for Electricity/Electronics.

ERIC Educational Resources Information Center

Mississippi State Dept. of Education, Jackson. Office of Vocational, Technical and Adult Education.

Standardized vocational education course titles and core contents are provided for two courses in Mississippi: electricity/electronics I and II. The first course contains the following units: (1) orientation, safety, and leadership; (2) basic principles of electricity/electronics; (3) direct current (DC) theory; (4) magnetism and DC motors; (5)…

Analysis of large power systems

NASA Technical Reports Server (NTRS)

Dommel, H. W.

1975-01-01

Computer-oriented power systems analysis procedures in the electric utilities are surveyed. The growth of electric power systems is discussed along with the solution of sparse network equations, power flow, and stability studies.

Polarization Catastrophe Contributing to Rotation and Tornadic Motion in Cumulo-Nimbus Clouds

NASA Astrophysics Data System (ADS)

Handel, P. H.

2007-05-01

When the concentration of sub-micron ice particles in a cloud exceeds 2.5E21 per cubic cm, divided by the squared average number of water molecules per crystallite, the polarization catastrophe occurs. Then all ice crystallites nucleated on aerosol dust particles align their dipole moments in the same direction, and a large polarization vector field is generated in the cloud. Often this vector field has a radial component directed away from the vertical axis of the cloud. It is induced by the pre-existing electric field caused by the charged screening layers at the cloud surface, the screening shell of the cloud. The presence of a vertical component of the magnetic field of the earth creates a density of linear momentum G=DxB in the azimuthal direction, where D=eE+P is the electric displacement vector and e is the vacuum permittivity. This linear momentum density yields an angular momentum density vector directed upward in the nordic hemisphere, if the polarization vector points away from the vertical axis of the cloud. When the cloud becomes colloidally unstable, the crystallites grow beyond the size limit at which they still could carry a large ferroelectric saturation dipole moment, and the polarization vector quickly disappears. Then the cloud begins to rotate with an angular momentum that has the same direction. Due to the large average number of water molecules in a crystallite, the polarization catastrophe (PC) is present in practically all clouds, and is compensated by masking charges. In cumulo-nimbus (thunder-) clouds the collapse of the PC is rapid, and the masking charges lead to lightning, and in the upper atmosphere also to sprites, elves, and blue jets. In stratus clouds, however, the collapse is slow, and only leads to reverse polarity in dissipating clouds (minus on the bottom), as compared with growing clouds (plus on the bottom, because of the excess polarization charge). References: P.H. Handel: "Polarization Catastrophe Theory of Cloud Electricity", J. Geophysical Research 90, 5857-5863 (1985). P.H. Handel and P.B. James: "Polarization Catastrophe Model of Static Electrification and Spokes in the B-Ring of Saturn", Geophys. Res. Lett. 10, 1-4 (1983).

Parallel heater system for subsurface formations

DOEpatents

Harris, Christopher Kelvin [Houston, TX; Karanikas, John Michael [Houston, TX; Nguyen, Scott Vinh [Houston, TX

2011-10-25

A heating system for a subsurface formation is disclosed. The system includes a plurality of substantially horizontally oriented or inclined heater sections located in a hydrocarbon containing layer in the formation. At least a portion of two of the heater sections are substantially parallel to each other. The ends of at least two of the heater sections in the layer are electrically coupled to a substantially horizontal, or inclined, electrical conductor oriented substantially perpendicular to the ends of the at least two heater sections.

Direct k-space imaging of Mahan cones at clean and Bi-covered Cu(111) surfaces

NASA Astrophysics Data System (ADS)

Winkelmann, Aimo; Akin Ünal, A.; Tusche, Christian; Ellguth, Martin; Chiang, Cheng-Tien; Kirschner, Jürgen

2012-08-01

Using a specifically tailored experimental approach, we revisit the exemplary effect of photoemission from quasi-free electronic states in crystals. Applying a momentum microscope, we measure photoelectron momentum patterns emitted into the complete half-space above the sample after excitation from a linearly polarized laser light source. By the application of a fully three-dimensional (3D) geometrical model of direct optical transitions, we explain the characteristic intensity distributions that are formed by the photoelectrons in k-space under the combination of energy conservation and crystal momentum conservation in the 3D bulk as well as at the two-dimensional (2D) surface. For bismuth surface alloys on Cu(111), the energy-resolved photoelectron momentum patterns allow us to identify specific emission processes in which bulk excited electrons are subsequently diffracted by an atomic 2D surface grating. The polarization dependence of the observed intensity features in momentum space is explained based on the different relative orientations of characteristic reciprocal space directions with respect to the electric field vector of the incident light.

Project ISIAH - Experiment on the effects of micro-gravity on hornets' nest building and activity

NASA Astrophysics Data System (ADS)

Brull, Lily

1992-10-01

An Israel Space Agency Investigation About Hornets (ISIAH) aimed at determining whether hornets are capable of retaining their unique ability of orientation under microgravity conditions is described. The Oriental Hornets used in the experiment are capable of building combs in the direction of the gravitational vector and detecting minute changes in gravitational force. Data obtained may be used to facilitate human adaptation to space conditions as well as rehabilitation after returning to earth.

The Association of PSR B1757-24 and the SNR G5.4-1.2

NASA Astrophysics Data System (ADS)

Gvaramadze, V. V.

The association of PSR B1757-24 and the supernova remnant (SNR) G5.4-1.2 was recently questioned by Thorsett et al. (2002) on the basis of proper motion measurements of the pulsar and the "incorrect" orientation of the vector of pulsar transverse velocity (inferred from the orientation of the cometary-shaped pulsar wind nebula). We show, however, that the association could be real if both objects are the remnants of an off-centered cavity supernova explosion.

Silhouette-Slice Theorems.

DTIC Science & Technology

1986-09-01

necessary to define "canonical" * parameterizations. Examples of proposed parameterizations are Munge N...of a slice of the surface oriented along the vector CT on the surface is given by STr -(A4.24) 11 is clear from the above expression, that when a slice

One Solution of the Forward Problem of DC Resistivity Well Logging by the Method of Volume Integral Equations with Allowance for Induced Polarization

NASA Astrophysics Data System (ADS)

Kevorkyants, S. S.

2018-03-01

For theoretically studying the intensity of the influence exerted by the polarization of the rocks on the results of direct current (DC) well logging, a solution is suggested for the direct inner problem of the DC electric logging in the polarizable model of plane-layered medium containing a heterogeneity by the example of the three-layer model of the hosting medium. Initially, the solution is presented in the form of a traditional vector volume-integral equation of the second kind (IE2) for the electric current density vector. The vector IE2 is solved by the modified iteration-dissipation method. By the transformations, the initial IE2 is reduced to the equation with the contraction integral operator for an axisymmetric model of electrical well-logging of the three-layer polarizable medium intersected by an infinitely long circular cylinder. The latter simulates the borehole with a zone of penetration where the sought vector consists of the radial J r and J z axial (relative to the cylinder's axis) components. The decomposition of the obtained vector IE2 into scalar components and the discretization in the coordinates r and z lead to a heterogeneous system of linear algebraic equations with a block matrix of the coefficients representing 2x2 matrices whose elements are the triple integrals of the mixed derivatives of the second-order Green's function with respect to the parameters r, z, r', and z'. With the use of the analytical transformations and standard integrals, the integrals over the areas of the partition cells and azimuthal coordinate are reduced to single integrals (with respect to the variable t = cos ϕ on the interval [-1, 1]) calculated by the Gauss method for numerical integration. For estimating the effective coefficient of polarization of the complex medium, it is suggested to use the Siegel-Komarov formula.

Aligned Immobilization of Proteins Using AC Electric Fields.

PubMed

Laux, Eva-Maria; Knigge, Xenia; Bier, Frank F; Wenger, Christian; Hölzel, Ralph

2016-03-01

Protein molecules are aligned and immobilized from solution by AC electric fields. In a single-step experiment, the enhanced green fluorescent proteins are immobilized on the surface as well as at the edges of planar nanoelectrodes. Alignment is found to follow the molecules' geometrical shape with their longitudinal axes parallel to the electric field. Simultaneous dielectrophoretic attraction and AC electroosmotic flow are identified as the dominant forces causing protein movement and alignment. Molecular orientation is determined by fluorescence microscopy based on polarized excitation of the proteins' chromophores. The chromophores' orientation with respect to the whole molecule supports X-ray crystal data. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gravitaxis in Euglena.

PubMed

Häder, Donat-P; Hemmersbach, Ruth

2017-01-01

Motile microorganisms utilize a number of responses to external stimuli including light, temperature, chemicals as well as magnetic and electric fields. Gravity is a major clue to select a niche in their environment. Positive gravitaxis leads an organism down into the water column and negative gravitaxis brings it to the surface. In Euglena the precision of gravitaxis is regulated by an internal rhythm entrained by the daily light/dark cycle. This and the cooperation with phototaxis bring the cells into an optimal position in the water column. In the past a passive orientation based on a buoy mechanism has been proposed for Euglena gracilis, but now it has been proven that this flagellate possesses a physiological gravireceptor and an active orientation. Numerous experiments in space using satellites, rockets and shuttles as well as in parabolic flights have been conducted as well as in functional weightlessness (simulated microgravity) on ground-based facilities such as clinostats to characterize the gravitaxis of Euglena. The threshold for gravity perception was determined and physiological, biochemical and molecular components of the signal transduction chain have been identified. In contrast to higher plants, some algae and ciliates, Euglena does not possess sedimenting statoliths to detect the direction of the gravity vector of the Earth. The gravireceptors were found to be mechano-sensitive Ca 2+ -conducting ion channels thought to be located at the front end of the cell underneath the trailing flagellum. When activated by gravity-induced pressure due to sedimentation of the whole cell body, they allow a passive influx of calcium along a previously established ion gradient. The entering calcium binds to a specific calmodulin (CaM.2) which in turn activates an adenylyl cyclase producing cAMP from ATP. This cAMP is believed to activate a specific protein kinase A (PK.4), which is postulated to phosphorylate proteins inside the flagellum resulting in a bending and thus a course correction and reorientation with respect to the direction of the gravity vector. The elements of the signal transduction chain have been characterized by inhibitors and by RNAi to prove their involvement in gravitaxis.

All-fiber 3D vector displacement (bending) sensor based on an eccentric FBG.

PubMed

Bao, Weijia; Rong, Qiangzhou; Chen, Fengyi; Qiao, Xueguang

2018-04-02

We demonstrate a fiber-optic 3D vector displacement sensor based on the monitoring of Bragg reflection from an eccentric grating inscribed in a depressed-cladding fiber using the femtosecond laser side-illumination and phase-mask technique. The compact sensing probe consists of a short section of depressed cladding fiber (DCF) containing eccentrically positioned fiber Bragg gratings. The eccentric grating breaks the cylindrical symmetry of the fiber cross-section and further has bending orientation-dependence. The generated fundamental resonance is strongly sensitive to bending of the fiber, and the direction of the bending plane can be determined from its responses. When integrated with axis strain monitoring, the sensor achieves a 3D vector displacement measurement via simple geometric analysis.

An examination of techniques for reformatting digital cartographic data/part 1: the raster-to- vector process.

USGS Publications Warehouse

Peuquet, D.J.

1981-01-01

Current graphic devices suitable for high-speed computer input and output of cartographic data are tending more and more to be raster-oriented, such as the rotating drum scanner and the color raster display. However, the majority of commonly used manipulative techniques in computer-assisted cartography and automated spatial data handling continue to require that the data be in vector format. This situation has recently precipitated the requirement for very fast techniques for converting digital cartographic data from raster to vector format for processing, and then back into raster format for plotting. The current article is part 1 of a 2 part paper concerned with examining the state-of-the-art in these conversion techniques. -from Author

On three-dimensional misorientation spaces

PubMed Central

Bennett, Robbie J.; Vukmanovic, Zoja; Solano-Alvarez, Wilberth; Lainé, Steven J.; Einsle, Joshua F.; Midgley, Paul A.; Rae, Catherine M. F.; Hielscher, Ralf

2017-01-01

Determining the local orientation of crystals in engineering and geological materials has become routine with the advent of modern crystallographic mapping techniques. These techniques enable many thousands of orientation measurements to be made, directing attention towards how such orientation data are best studied. Here, we provide a guide to the visualization of misorientation data in three-dimensional vector spaces, reduced by crystal symmetry, to reveal crystallographic orientation relationships. Domains for all point group symmetries are presented and an analysis methodology is developed and applied to identify crystallographic relationships, indicated by clusters in the misorientation space, in examples from materials science and geology. This analysis aids the determination of active deformation mechanisms and evaluation of cluster centres and spread enables more accurate description of transformation processes supporting arguments regarding provenance. PMID:29118660

Effect of orientation on electrically conducting thermoplastic composite properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Genetti, W.B.; Grady, B.P.

1996-10-01

Properties of electrically conducting composites made from low density polyethylene (LDPE), high density polyethylene (HDPE), and polypropylene (PP) filled with nickel flake are being studied as a function of nickel concentration and draw ratio. The effect on electrical conduction, crystallinity, melt temperature, tensile modulus, and elongation at break are being tested. The melt temperature increases with increasing nickel concentration. The electrical conduction increases slowly with increased nickel concentration to the percolation volume fraction, then increases sharply. Orientation by uniaxial stretching of the films should allow conductive pathways to form throughout the polymer more easily by forcing particles closer together, thusmore » reducing the percolation volume fraction. This process could be caused by both alignment of the polymer chains and by stress induced crystallization that forces the particles into smaller amorphous regions.« less

Contactless Determination of Electrical Conductivity of One-Dimensional Nanomaterials by Solution-Based Electro-orientation Spectroscopy

DOE PAGES

Akin, Cevat; Yi, Jingang; Feldman, Leonard C.; ...

2015-05-05

For nanowires of the same composition, and even fabricated within the same batch, often exhibit electrical conductivities that can vary by orders of magnitude. Unfortunately, existing electrical characterization methods are time-consuming, making the statistical survey of highly variable samples essentially impractical. Here, we demonstrate a contactless, solution-based method to efficiently measure the electrical conductivity of 1D nanomaterials based on their transient alignment behavior in ac electric fields of different frequencies. In comparison with direct transport measurements by probe-based scanning tunneling microscopy shows that electro-orientation spectroscopy can quantitatively measure nanowire conductivity over a 5-order-of-magnitude range, 10–5–1 Ω–1 m–1 (corresponding to resistivitiesmore » in the range 102–107 Ω·cm). With this method, we statistically characterize the conductivity of a variety of nanowires and find significant variability in silicon nanowires grown by metal-assisted chemical etching from the same wafer. We also find that the active carrier concentration of n-type silicon nanowires is greatly reduced by surface traps and that surface passivation increases the effective conductivity by an order of magnitude. Moreover, this simple method makes electrical characterization of insulating and semiconducting 1D nanomaterials far more efficient and accessible to more researchers than current approaches. Electro-orientation spectroscopy also has the potential to be integrated with other solution-based methods for the high-throughput sorting and manipulation of 1D nanomaterials for postgrowth device assembly.« less

Evaluation method for in situ electric field in standardized human brain for different transcranial magnetic stimulation coils

NASA Astrophysics Data System (ADS)

Iwahashi, Masahiro; Gomez-Tames, Jose; Laakso, Ilkka; Hirata, Akimasa

2017-03-01

This study proposes a method to evaluate the electric field induced in the brain by transcranial magnetic stimulation (TMS) to realize focal stimulation in the target area considering the inter-subject difference of the brain anatomy. The TMS is a non-invasive technique used for treatment/diagnosis, and it works by inducing an electric field in a specific area of the brain via a coil-induced magnetic field. Recent studies that report on the electric field distribution in the brain induced by TMS coils have been limited to simplified human brain models or a small number of detailed human brain models. Until now, no method has been developed that appropriately evaluates the coil performance for a group of subjects. In this study, we first compare the magnetic field and the magnetic vector potential distributions to determine if they can be used as predictors of the TMS focality derived from the electric field distribution. Next, the hotspots of the electric field on the brain surface of ten subjects using six coils are compared. Further, decisive physical factors affecting the focality of the induced electric field by different coils are discussed by registering the computed electric field in a standard brain space for the first time, so as to evaluate coil characteristics for a large population of subjects. The computational results suggest that the induced electric field in the target area cannot be generalized without considering the morphological variability of the human brain. Moreover, there was no remarkable difference between the various coils, although focality could be improved to a certain extent by modifying the coil design (e.g., coil radius). Finally, the focality estimated by the electric field was more correlated with the magnetic vector potential than the magnetic field in a homogeneous sphere.

Evaluation method for in situ electric field in standardized human brain for different transcranial magnetic stimulation coils.

PubMed

Iwahashi, Masahiro; Gomez-Tames, Jose; Laakso, Ilkka; Hirata, Akimasa

2017-03-21

This study proposes a method to evaluate the electric field induced in the brain by transcranial magnetic stimulation (TMS) to realize focal stimulation in the target area considering the inter-subject difference of the brain anatomy. The TMS is a non-invasive technique used for treatment/diagnosis, and it works by inducing an electric field in a specific area of the brain via a coil-induced magnetic field. Recent studies that report on the electric field distribution in the brain induced by TMS coils have been limited to simplified human brain models or a small number of detailed human brain models. Until now, no method has been developed that appropriately evaluates the coil performance for a group of subjects. In this study, we first compare the magnetic field and the magnetic vector potential distributions to determine if they can be used as predictors of the TMS focality derived from the electric field distribution. Next, the hotspots of the electric field on the brain surface of ten subjects using six coils are compared. Further, decisive physical factors affecting the focality of the induced electric field by different coils are discussed by registering the computed electric field in a standard brain space for the first time, so as to evaluate coil characteristics for a large population of subjects. The computational results suggest that the induced electric field in the target area cannot be generalized without considering the morphological variability of the human brain. Moreover, there was no remarkable difference between the various coils, although focality could be improved to a certain extent by modifying the coil design (e.g., coil radius). Finally, the focality estimated by the electric field was more correlated with the magnetic vector potential than the magnetic field in a homogeneous sphere.

Pressure sensor using liquid crystals

NASA Technical Reports Server (NTRS)

Parmar, Devendra S. (Inventor); Holmes, Harlan K. (Inventor)

1994-01-01

A pressure sensor includes a liquid crystal positioned between transparent, electrically conductive films (18 and 20), that are biased by a voltage (V) which induces an electric field (E) that causes the liquid crystal to assume a first state of orientation. Application of pressure (P) to a flexible, transparent film (24) causes the conductive film (20) to move closer to or farther from the conductive film (18), thereby causing a change in the electric field (E'(P)) which causes the liquid crystal to assume a second state of orientation. Polarized light (P.sub.1) is directed into the liquid crystal and transmitted or reflected to an analyzer (A or 30). Changes in the state of orientation of the liquid crystal induced by applied pressure (P) result in a different light intensity being detected at the analyzer (A or 30) as a function of the applied pressure (P). In particular embodiments, the liquid crystal is present as droplets (10) in a polymer matrix (12) or in cells (14) in a polymeric or dielectric grid (16) material in the form of a layer (13) between the electrically conductive films (18 and 20). The liquid crystal fills the open wells in the polymer matrix (12) or grid (16) only partially.

A comparison of blood loss during the Halal slaughter of lambs following Traditional Religious Slaughter without stunning, Electric Head-Only Stunning and Post-Cut Electric Head-Only Stunning.

PubMed

Khalid, Rizvan; Knowles, Toby G; Wotton, Steve B

2015-12-01

Blood lost at exsanguination during the Halal slaughter of lambs was compared between the slaughter methods of Traditional Religious Slaughter without stunning (TRS), Electric Head-Only Stunning (EHOS) and Post-Cut Electric Head-Only Stunning (PCEHOS). Two protocols were examined, Experimental (80 lambs) and Commercial (360 lambs), assessing varying periods of animal orientation during the 4 min bleeding process (upright orientation before vertical hanging). Live-weight, blood weight (Experimental only), carcass weights and by-product weights were recorded. The Experimental protocol highlighted an increase in blood loss at 60s in EHOS and PCEHOS compared to TRS (P<0.001) but by 90 s there was no significant difference. A post-slaughter change in animal orientation from an upright to a vertical hanging position aided the amount of blood loss. The bleeding of lambs is largely completed by 2 min. There were no significant differences (P>0.05) in final blood loss between treatments. This research was undertaken to inform discussion on the merits of different slaughter methods compatible with Halal requirements. Copyright © 2015. Published by Elsevier Ltd.

Characterizing Electric Field Exposed P3HT Thin Films Using Polarized-Light Spectroscopies

DOE PAGES

Bhattacharjee, Ujjal; Elshobaki, Moneim; Santra, Kalyan; ...

2016-06-23

P3HT (poly (3-hexylthiophene)) has been widely used as a donor in the active layer in organic photovoltaic devices. Although moderately high-power conversion efficiencies have been achieved with P3HT-based devices, structural details, such as the orientation of polymer units and the extent of H- and J-aggregation are not yet fully understood; and different measures have been taken to control the ordering in the material. One such measure, which we have exploited, is to apply an electric field from a Van de Graaff generator. We used fluorescence (to measure anisotropy instead of polarization, which is more commonly measured) and Raman spectroscopy tomore » characterize the order of P3HT molecules in thin films resulting from the field. We determine preferential orientations of the units in a thin film, consistent with observed hole mobility in thin-film-transistors, and observe that the apparent H-coupling strength changes when the films are exposed to oriented electrical fields during drying.« less

An examination of techniques for reformatting digital cartographic data. Part 2: the vector-to raster process.

USGS Publications Warehouse

Peuquet, D.J.

1981-01-01

Current graphic devices suitable for high-speed computer input and output of cartographic data are tending more and more to be raster-oriented, such as the rotating drum scanner and the color raster display. However, the majority of commonly used manipulative techniques in computer-assisted cartography and automated spatial data handling continue to require that the data be in vector format. The current article is the second part of a two-part paper that examines the state of the art in these conversion techniques. - from Author

Acoustic vector tomography and its application to magnetoacoustic tomography with magnetic induction (MAT-MI).

PubMed

Li, Xu; Xia, Rongmin; He, Bin

2008-01-01

A new tomographic algorithm for reconstructing a curl-free vector field, whose divergence serves as acoustic source is proposed. It is shown that under certain conditions, the scalar acoustic measurements obtained from a surface enclosing the source area can be vectorized according to the known measurement geometry and then be used to reconstruct the vector field. The proposed method is validated by numerical experiments. This method can be easily applied to magnetoacoustic tomography with magnetic induction (MAT-MI). A simulation study of applying this method to MAT-MI shows that compared to existing methods, the proposed method can give an accurate estimation of the induced current distribution and a better reconstruction of electrical conductivity within an object.

Initial Results of DC Electric Fields, Associated Plasma Drifts, Magnetic Fields, and Plasma Waves Observed on the C/NOFS Satellite

NASA Technical Reports Server (NTRS)

Pfaff, R.; Freudenreich, H.; Bromund, K.; Klenzing, J.; Rowland, D.; Maynard, N.

2010-01-01

Initial results are presented from the Vector Electric Field Investigation (VEFI) on the Air Force Communication/Navigation Outage Forecasting System (C/NOFS) satellite, a mission designed to understand, model, and forecast the presence of equatorial ionospheric irregularities. The VEFI instrument includes a vector DC electric field detector, a fixed-bias Langmuir probe operating in the ion saturation regime, a flux gate magnetometer, an optical lightning detector, and associated electronics including a burst memory. Compared to data obtained during more active solar conditions, the ambient DC electric fields and their associated E x B drifts are variable and somewhat weak, typically < 1 mV/m. Although average drift directions show similarities to those previously reported, eastward/outward during day and westward/downward at night, this pattern varies significantly with longitude and is not always present. Daytime vertical drifts near the magnetic equator are largest after sunrise, with smaller average velocities after noon. Little or no pre-reversal enhancement in the vertical drift near sunset is observed, attributable to the solar minimum conditions creating a much reduced neutral dynamo at the satellite altitude. The nighttime ionosphere is characterized by larger amplitude, structured electric fields, even where the plasma density appears nearly quiescent. Data from successive orbits reveal that the vertical drifts and plasma density are both clearly organized with longitude. The spread-F density depletions and corresponding electric fields that have been detected thus far have displayed a preponderance to appear between midnight and dawn. Associated with the narrow plasma depletions that are detected are broad spectra of electric field and plasma density irregularities for which a full vector set of measurements is available for detailed study. Finally, the data set includes a wide range of ELF/VLF/HF oscillations corresponding to a variety of plasma waves, in particular banded ELF hiss, whistlers, and lower hybrid wave turbulence triggered by lightning-induced sferics. The VEFI data represents a new set of measurements that are germane to numerous fundamental aspects of the electrodynamics and irregularities inherent to the Earth's low latitude ionosphere.

Design of 2D time-varying vector fields.

PubMed

Chen, Guoning; Kwatra, Vivek; Wei, Li-Yi; Hansen, Charles D; Zhang, Eugene

2012-10-01

Design of time-varying vector fields, i.e., vector fields that can change over time, has a wide variety of important applications in computer graphics. Existing vector field design techniques do not address time-varying vector fields. In this paper, we present a framework for the design of time-varying vector fields, both for planar domains as well as manifold surfaces. Our system supports the creation and modification of various time-varying vector fields with desired spatial and temporal characteristics through several design metaphors, including streamlines, pathlines, singularity paths, and bifurcations. These design metaphors are integrated into an element-based design to generate the time-varying vector fields via a sequence of basis field summations or spatial constrained optimizations at the sampled times. The key-frame design and field deformation are also introduced to support other user design scenarios. Accordingly, a spatial-temporal constrained optimization and the time-varying transformation are employed to generate the desired fields for these two design scenarios, respectively. We apply the time-varying vector fields generated using our design system to a number of important computer graphics applications that require controllable dynamic effects, such as evolving surface appearance, dynamic scene design, steerable crowd movement, and painterly animation. Many of these are difficult or impossible to achieve via prior simulation-based methods. In these applications, the time-varying vector fields have been applied as either orientation fields or advection fields to control the instantaneous appearance or evolving trajectories of the dynamic effects.

Velocity-tunable slow beams of cold O2 in a single spin-rovibronic state with full angular-momentum orientation by multistage Zeeman deceleration

NASA Astrophysics Data System (ADS)

Wiederkehr, A. W.; Schmutz, H.; Motsch, M.; Merkt, F.

2012-08-01

Cold samples of oxygen molecules in supersonic beams have been decelerated from initial velocities of 390 and 450 m s-1 to final velocities in the range between 150 and 280 m s-1 using a 90-stage Zeeman decelerator. (2 + 1) resonance-enhanced-multiphoton-ionization (REMPI) spectra of the 3sσ g 3Π g (C) ? two-photon transition of O2 have been recorded to characterize the state selectivity of the deceleration process. The decelerated molecular sample was found to consist exclusively of molecules in the J ‧‧ = 2 spin-rotational component of the X ? ground state of O2. Measurements of the REMPI spectra using linearly polarized laser radiation with polarization vector parallel to the decelerator axis, and thus to the magnetic-field vector of the deceleration solenoids, further showed that only the ? magnetic sublevel of the N‧‧ = 1, J ‧‧ = 2 spin-rotational level is populated in the decelerated sample, which therefore is characterized by a fully oriented total-angular-momentum vector. By maintaining a weak quantization magnetic field beyond the decelerator, the polarization of the sample could be maintained over the 5 cm distance separating the last deceleration solenoid and the detection region.

A new orientation relationship between cementite and austenite and coexistence of pseudo-primary and secondary dislocations in the habit plane

NASA Astrophysics Data System (ADS)

Xu, Wen-Sheng; Zhang, Wen-Zheng

2018-01-01

A new orientation relationship (OR) is found between Widmanstätten cementite precipitates and the austenite matrix in a 1.3C-14Mn steel. The associated habit plane (HP) and the dislocations in the HP have been investigated with transmission electron microscopy. The HP is parallel to ? in cementite, and it is parallel to ? in austenite. Three groups of interfacial dislocations are observed in the HP, with limited quantitative experimental data. The line directions, the spacing and the Burgers vectors of two sets of dislocations have been calculated based on a misfit analysis, which combines the CSL/DSC/O-lattice theories, row matching and good matching site (GMS) mappings. The calculated results are in reasonable agreement with the experimental results. The dislocations 'Coarse 1' and 'Fine 1' are in the same direction as the matching rows, i.e. ?. 'Coarse 1' dislocations are secondary dislocations with a Burgers vector of ?, and 'Fine 1' dislocations are pseudo-primary dislocations with a plausible Burgers vector of ?. The reason why the fraction of the new OR is much less than that of the dominant Pitsch OR has been discussed in terms of the degree of matching in the HPs.

Towards Ultra-High Resolution Fibre Tract Mapping of the Human Brain – Registration of Polarised Light Images and Reorientation of Fibre Vectors

PubMed Central

Palm, Christoph; Axer, Markus; Gräßel, David; Dammers, Jürgen; Lindemeyer, Johannes; Zilles, Karl; Pietrzyk, Uwe; Amunts, Katrin

2009-01-01

Polarised light imaging (PLI) utilises the birefringence of the myelin sheaths in order to visualise the orientation of nerve fibres in microtome sections of adult human post-mortem brains at ultra-high spatial resolution. The preparation of post-mortem brains for PLI involves fixation, freezing and cutting into 100-μm-thick sections. Hence, geometrical distortions of histological sections are inevitable and have to be removed for 3D reconstruction and subsequent fibre tracking. We here present a processing pipeline for 3D reconstruction of these sections using PLI derived multimodal images of post-mortem brains. Blockface images of the brains were obtained during cutting; they serve as reference data for alignment and elimination of distortion artefacts. In addition to the spatial image transformation, fibre orientation vectors were reoriented using the transformation fields, which consider both affine and subsequent non-linear registration. The application of this registration and reorientation approach results in a smooth fibre vector field, which reflects brain morphology. PLI combined with 3D reconstruction and fibre tracking is a powerful tool for human brain mapping. It can also serve as an independent method for evaluating in vivo fibre tractography. PMID:20461231

Effect of spaceflight on the spatial orientation of the vestibulo-ocular reflex during eccentric roll rotation: A case report.

PubMed

Reschke, Millard F; Wood, Scott J; Clément, Gilles

2018-01-01

Ground-based studies have reported shifts of the vestibulo-ocular reflex (VOR) slow phase velocity (SPV) axis toward the resultant gravito-inertial force vector. The VOR was examined during eccentric roll rotation before, during and after an 8-day orbital mission. On orbit this vector is aligned with the head z-axis. Our hypothesis was that eccentric roll rotation on orbit would generate horizontal eye movements. Two subjects were rotated in a semi-supine position with the head nasal-occipital axis parallel to the axis of rotation and 0.5 m off-center. The chair accelerated at 120 deg/s2 to 120 deg/s, rotated at constant velocity for one minute, and then decelerated to a stop in similar fashion. On Earth, the stimulation primarily generated torsional VOR. During spaceflight, in one subject torsional VOR became horizontal VOR, and then decayed very slowly. In the other subject, torsional VOR was reduced on orbit relative to pre- and post-flight, but the SPV axis did not rotate. We attribute the shift from torsional to horizontal VOR on orbit to a spatial orientation of velocity storage toward alignment with the gravito-inertial force vector, and the inter-individual difference to cognitive factors related to the subjective straight-ahead.

Magnetosensitive neurons mediate geomagnetic orientation in Caenorhabditis elegans

PubMed Central

Vidal-Gadea, Andrés; Ward, Kristi; Beron, Celia; Ghorashian, Navid; Gokce, Sertan; Russell, Joshua; Truong, Nicholas; Parikh, Adhishri; Gadea, Otilia; Ben-Yakar, Adela; Pierce-Shimomura, Jonathan

2015-01-01

Many organisms spanning from bacteria to mammals orient to the earth's magnetic field. For a few animals, central neurons responsive to earth-strength magnetic fields have been identified; however, magnetosensory neurons have yet to be identified in any animal. We show that the nematode Caenorhabditis elegans orients to the earth's magnetic field during vertical burrowing migrations. Well-fed worms migrated up, while starved worms migrated down. Populations isolated from around the world, migrated at angles to the magnetic vector that would optimize vertical translation in their native soil, with northern- and southern-hemisphere worms displaying opposite migratory preferences. Magnetic orientation and vertical migrations required the TAX-4 cyclic nucleotide-gated ion channel in the AFD sensory neuron pair. Calcium imaging showed that these neurons respond to magnetic fields even without synaptic input. C. elegans may have adapted magnetic orientation to simplify their vertical burrowing migration by reducing the orientation task from three dimensions to one. DOI: http://dx.doi.org/10.7554/eLife.07493.001 PMID:26083711

New Ro-Vibrational Kinetic Energy Operators using Polyspherical Coordinates for Polyatomic Molecules

NASA Technical Reports Server (NTRS)

Schwenke, David W.; Kwak, Dochan (Technical Monitor)

2002-01-01

We illustrate how one can easily derive kinetic energy operators for polyatomic molecules using polyspherical coordinates with very general choices for z-axis embeddings arid angles used to specify relative orientations of internal vectors. Computer algebra is not required.

Seismic refraction and electrical resistivity tests for fracture induced hydraulic anisotropy in a mountain watershed.

NASA Astrophysics Data System (ADS)

Mendieta, A. L.; Bradford, J.; Liberty, L. M.; McNamara, J. P.

2016-12-01

Granitic based terrains often have complex hydrogeological systems. It is often assumed that the bedrock is impermeable, unless it is fractured. If the bedrock is fractured this can greatly affect fluid flow, depending on fracture density and orientation. Recently there has been a substantial increase in the number of geophysical studies designed to investigate hydrologic processes in mountain watersheds, however few of these studies have taken fracture induced geophysical and hydraulic anisotropy into consideration. Vertically oriented fractures with a preferred orientation produce azimuthal anisotropy in the electrical resistivity, the seismic primary wave (P-wave) velocity, and the hydraulic permeability. By measuring the electrical and seismic anisotropy we can estimate fracture orientation and density which improves our understanding of hydraulic properties. Despite numerous previous studies of the hydrologic system, the subsurface hydraulic system at the Dry Creek Experimental Watershed (DCEW), located near Boise, Idaho, is not completely understood. This is particularly true of the deep (>5m) system which is difficult to study using conventional hydrologic measurements, particularly in rugged and remote mountain environments. From previous studies, it is hypothesized that there is a system of fractures that may be aligned according to the local stress field. To test for the preferential alignment, ergo the direction of preferential water flow, we collected seismic and electrical resistivity profiles along different azimuths. The preliminary results show an azimuthal dependence of the P-wave velocities in the bedrock, at depths greater than 18 m; P-wave velocities range from 3500 to 4100 m/s, which represents a 17.5 % difference. We interpret this difference to be caused by fractures present in the bedrock. At the same location, we measured an electric resistivity value of 29 ohm-m, and we expect a difference of 37 %, if the fractures are fully saturated. Future studies will include coincident multi-azimuthal electrical resistivity surveys both to verify the results of the seismic study and to improve our understanding of the hydraulic properties.

Registering myocardial fiber orientations with heart geometry using iterative closest points algorithms

NASA Astrophysics Data System (ADS)

Deng, Dongdong; Jiao, Peifeng; Shou, Guofa; Xia, Ling

2009-10-01

Myocardial electrical excitation propagation is anisotropic, with the most rapid spread of current along the direction of the long axis of the fiber. Fiber orientation is also an important determinant of myocardial mechanics. So myocardial fiber orientations are very important to heart modeling and simulation. Accurately construction of myocardial fiber orientations, however, is still a challenge. The purpose of this paper is to construct a heart geometrical model with myocardial fiber orientations based on CT and 3D laser scanned pictures. The iterative closest points (ICP) algorithms were used to register the fiber orientations with the heart geometry.

Support vector machine for day ahead electricity price forecasting

NASA Astrophysics Data System (ADS)

Razak, Intan Azmira binti Wan Abdul; Abidin, Izham bin Zainal; Siah, Yap Keem; Rahman, Titik Khawa binti Abdul; Lada, M. Y.; Ramani, Anis Niza binti; Nasir, M. N. M.; Ahmad, Arfah binti

2015-05-01

Electricity price forecasting has become an important part of power system operation and planning. In a pool- based electric energy market, producers submit selling bids consisting in energy blocks and their corresponding minimum selling prices to the market operator. Meanwhile, consumers submit buying bids consisting in energy blocks and their corresponding maximum buying prices to the market operator. Hence, both producers and consumers use day ahead price forecasts to derive their respective bidding strategies to the electricity market yet reduce the cost of electricity. However, forecasting electricity prices is a complex task because price series is a non-stationary and highly volatile series. Many factors cause for price spikes such as volatility in load and fuel price as well as power import to and export from outside the market through long term contract. This paper introduces an approach of machine learning algorithm for day ahead electricity price forecasting with Least Square Support Vector Machine (LS-SVM). Previous day data of Hourly Ontario Electricity Price (HOEP), generation's price and demand from Ontario power market are used as the inputs for training data. The simulation is held using LSSVMlab in Matlab with the training and testing data of 2004. SVM that widely used for classification and regression has great generalization ability with structured risk minimization principle rather than empirical risk minimization. Moreover, same parameter settings in trained SVM give same results that absolutely reduce simulation process compared to other techniques such as neural network and time series. The mean absolute percentage error (MAPE) for the proposed model shows that SVM performs well compared to neural network.

Cryosurgery with Pulsed Electric Fields

PubMed Central

Daniels, Charlotte S.; Rubinsky, Boris

2011-01-01

This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF) are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF) was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused PEFs could be used to ablate cells in the high subzero freezing region of a cryosurgical lesion. PMID:22087224

Multi-mode energy management strategy for fuel cell electric vehicles based on driving pattern identification using learning vector quantization neural network algorithm

NASA Astrophysics Data System (ADS)

Song, Ke; Li, Feiqiang; Hu, Xiao; He, Lin; Niu, Wenxu; Lu, Sihao; Zhang, Tong

2018-06-01

The development of fuel cell electric vehicles can to a certain extent alleviate worldwide energy and environmental issues. While a single energy management strategy cannot meet the complex road conditions of an actual vehicle, this article proposes a multi-mode energy management strategy for electric vehicles with a fuel cell range extender based on driving condition recognition technology, which contains a patterns recognizer and a multi-mode energy management controller. This paper introduces a learning vector quantization (LVQ) neural network to design the driving patterns recognizer according to a vehicle's driving information. This multi-mode strategy can automatically switch to the genetic algorithm optimized thermostat strategy under specific driving conditions in the light of the differences in condition recognition results. Simulation experiments were carried out based on the model's validity verification using a dynamometer test bench. Simulation results show that the proposed strategy can obtain better economic performance than the single-mode thermostat strategy under dynamic driving conditions.

Probing the radio emission from air showers with polarization measurements

NASA Astrophysics Data System (ADS)

Aab, A.; Abreu, P.; Aglietta, M.; Ahlers, M.; Ahn, E. J.; Albuquerque, I. F. M.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Alves Batista, R.; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Antičić, T.; Aramo, C.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Badescu, A. M.; Barber, K. B.; Bardenet, R.; Bäuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; BenZvi, S.; Berat, C.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blanco, F.; Blanco, M.; Bleve, C.; Blümer, H.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Candusso, M.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Cheng, S. H.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Colalillo, R.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Criss, A.; Cronin, J.; Curutiu, A.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; De Domenico, M.; de Jong, S. J.; De La Vega, G.; de Mello Junior, W. J. M.; de Mello Neto, J. R. T.; De Mitri, I.; de Souza, V.; de Vries, K. D.; del Peral, L.; Deligny, O.; Dembinski, H.; Dhital, N.; Di Giulio, C.; Di Matteo, A.; Diaz, J. C.; Díaz Castro, M. L.; Diep, P. N.; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dong, P. N.; Dorofeev, A.; dos Anjos, J. C.; Dova, M. T.; Ebr, J.; Engel, R.; Erdmann, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Facal San Luis, P.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipčič, A.; Foerster, N.; Fox, B. D.; Fracchiolla, C. E.; Fraenkel, E. D.; Fratu, O.; Fröhlich, U.; Fuchs, B.; Gaior, R.; Gamarra, R. F.; Gambetta, S.; García, B.; Garcia Roca, S. T.; Garcia-Gamez, D.; Garcia-Pinto, D.; Garilli, G.; Gascon Bravo, A.; Gemmeke, H.; Ghia, P. L.; Giammarchi, M.; Giller, M.; Gitto, J.; Glaser, C.; Glass, H.; Gomez Albarracin, F.; Gómez Berisso, M.; Gómez Vitale, P. F.; Gonçalves, P.; Gonzalez, J. G.; Gookin, B.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grebe, S.; Griffith, N.; Grillo, A. F.; Grubb, T. D.; Guardincerri, Y.; Guarino, F.; Guedes, G. P.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Hollon, N.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huber, D.; Huege, T.; Insolia, A.; Isar, P. G.; Jansen, S.; Jarne, C.; Josebachuili, M.; Kadija, K.; Kambeitz, O.; Kampert, K. H.; Karhan, P.; Kasper, P.; Katkov, I.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Knapp, J.; Krause, R.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kunka, N.; La Rosa, G.; LaHurd, D.; Latronico, L.; Lauer, R.; Lauscher, M.; Lautridou, P.; Le Coz, S.; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Lopez Agüera, A.; Louedec, K.; Lozano Bahilo, J.; Lu, L.; Lucero, A.; Ludwig, M.; Lyberis, H.; Maccarone, M. C.; Malacari, M.; Maldera, S.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Mariş, I. C.; Marquez Falcon, H. R.; Marsella, G.; Martello, D.; Martin, L.; Martinez, H.; Martínez Bravo, O.; Martraire, D.; Masías Meza, J. J.; Mathes, H. J.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melissas, M.; Melo, D.; Menichetti, E.; Menshikov, A.; Messina, S.; Meyhandan, R.; Mićanović, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Monnier Ragaigne, D.; Montanet, F.; Morales, B.; Morello, C.; Moreno, J. C.; Mostafá, M.; Moura, C. A.; Muller, M. A.; Müller, G.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navarro, J. L.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nhung, P. T.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Nožka, L.; Oehlschläger, J.; Olinto, A.; Oliveira, M.; Ortiz, M.; Pacheco, N.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Palmieri, N.; Parente, G.; Parra, A.; Pastor, S.; Paul, T.; Pech, M.; PeÂķala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Pesce, R.; Petermann, E.; Petrera, S.; Petrolini, A.; Petrov, Y.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Pontz, M.; Porcelli, A.; Preda, T.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.; Ridky, J.; Riggi, S.; Risse, M.; Ristori, P.; Rivera, H.; Rizi, V.; Roberts, J.; Rodrigues de Carvalho, W.; Rodriguez Cabo, I.; Rodriguez Fernandez, G.; Rodriguez Martino, J.; Rodriguez Rojo, J.; Rodríguez-Frías, M. D.; Ros, G.; Rosado, J.; Rossler, T.; Roth, M.; Rouillé-d'Orfeuil, B.; Roulet, E.; Rovero, A. C.; Rühle, C.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Salesa Greus, F.; Salina, G.; Sánchez, F.; Sanchez-Lucas, P.; Santo, C. E.; Santos, E.; Santos, E. M.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sato, R.; Scharf, N.; Scherini, V.; Schieler, H.; Schiffer, P.; Schmidt, A.; Scholten, O.; Schoorlemmer, H.; Schovánek, P.; Schröder, F. G.; Schulz, A.; Schulz, J.; Sciutto, S. J.; Scuderi, M.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sidelnik, I.; Sigl, G.; Sima, O.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sorokin, J.; Spinka, H.; Squartini, R.; Srivastava, Y. N.; Stanič, S.; Stapleton, J.; Stasielak, J.; Stephan, M.; Straub, M.; Stutz, A.; Suarez, F.; Suomijärvi, T.; Supanitsky, A. D.; Šuša, T.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Szuba, M.; Tapia, A.; Tartare, M.; Taşcǎu, O.; Thao, N. T.; Tiffenberg, J.; Timmermans, C.; Tkaczyk, W.; Todero Peixoto, C. J.; Toma, G.; Tomankova, L.; Tomé, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Travnicek, P.; Tridapalli, D. B.; Trovato, E.; Tueros, M.; Ulrich, R.; Unger, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van den Berg, A. M.; van Velzen, S.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Varner, G.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Verzi, V.; Vicha, J.; Videla, M.; Villaseñor, L.; Wahlberg, H.; Wahrlich, P.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weidenhaupt, K.; Weindl, A.; Werner, F.; Westerhoff, S.; Whelan, B. J.; Widom, A.; Wieczorek, G.; Wiencke, L.; Wilczyńska, B.; Wilczyński, H.; Will, M.; Williams, C.; Winchen, T.; Wundheiler, B.; Wykes, S.; Yamamoto, T.; Yapici, T.; Younk, P.; Yuan, G.; Yushkov, A.; Zamorano, B.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zaw, I.; Zepeda, A.; Zhou, J.; Zhu, Y.; Zimbres Silva, M.; Ziolkowski, M.; Pierre Auger Collaboration

2014-03-01

The emission of radio waves from air showers has been attributed to the so-called geomagnetic emission process. At frequencies around 50 MHz this process leads to coherent radiation which can be observed with rather simple setups. The direction of the electric field induced by this emission process depends only on the local magnetic field vector and on the incoming direction of the air shower. We report on measurements of the electric field vector where, in addition to this geomagnetic component, another component has been observed that cannot be described by the geomagnetic emission process. The data provide strong evidence that the other electric field component is polarized radially with respect to the shower axis, in agreement with predictions made by Askaryan who described radio emission from particle showers due to a negative charge excess in the front of the shower. Our results are compared to calculations which include the radiation mechanism induced by this charge-excess process.

Wind Velocity and Position Sensor-less Operation for PMSG Wind Generator

NASA Astrophysics Data System (ADS)

Senjyu, Tomonobu; Tamaki, Satoshi; Urasaki, Naomitsu; Uezato, Katsumi; Funabashi, Toshihisa; Fujita, Hideki

Electric power generation using non-conventional sources is receiving considerable attention throughout the world. Wind energy is one of the available non-conventional energy sources. Electrical power generation using wind energy is possible in two ways, viz. constant speed operation and variable speed operation using power electronic converters. Variable speed power generation is attractive, because maximum electric power can be generated at all wind velocities. However, this system requires a rotor speed sensor, for vector control purpose, which increases the cost of the system. To alleviate the need of rotor speed sensor in vector control, we propose a new sensor-less control of PMSG (Permanent Magnet Synchronous Generator) based on the flux linkage. We can estimate the rotor position using the estimated flux linkage. We use a first-order lag compensator to obtain the flux linkage. Furthermore‚we estimate wind velocity and rotation speed using a observer. The effectiveness of the proposed method is demonstrated thorough simulation results.

Dielectric and permeability

NASA Technical Reports Server (NTRS)

Cole, K. D.

1982-01-01

Using the unabridged Maxwell equations (including vectors D, E and H) new effects in collisionless plasmas are uncovered. In a steady state, it is found that spatially varying energy density of the electric field (E perpendicular) orthogonal to B produces electric current leading, under certain conditions, to the relationship P perpendicular+B(2)/8 pi-epsilon E perpendicular(2)/8 pi = constant, where epsilon is the dielectric constant of the plasma for fields orthogonal to B. In steady state quasi-two-dimensional flows in plasmas, a general relationship between the components of electric field parallel and perpendicular to B is found. These effects are significant in goephysical and astrophysical plasmas. The general conditions for a steady state in collisionless plasma are deduced. With time variations in a plasma, slow compared to ion-gyroperiod, there is a general current, (j*), which includes the well-known polarisation current, given by J*=d/dt (ExM)+(PxB)xB B(-2) where M and P are the magnetization and polarization vectors respectively.

Silver nanocube aggregation gradient materials in search for total internal reflection with high phase sensitivity

NASA Astrophysics Data System (ADS)

König, Tobias A. F.; Ledin, Petr A.; Russell, Michael; Geldmeier, Jeffrey A.; Mahmoud, Mahmoud. A.; El-Sayed, Mostafa A.; Tsukruk, Vladimir V.

2015-03-01

We fabricated monolayer coatings of a silver nanocube aggregation to create a step-wise optical strip by applying different surface pressures during slow Langmuir-Blodgett deposition. The varying amount of randomly distributed nanocube aggregates with different surface coverages in gradient manner due to changes in surface pressure allows for continuous control of the polarization sensitive absorption of the incoming light over a broad optical spectrum. Optical characterization under total internal reflection conditions combined with electromagnetic simulations reveal that the broadband light absorption depends on the relative orientation of the nanoparticles to the polarization of the incoming light. By using computer simulations, we found that the electric field vector of the s-polarized light interacts with the different types of silver nanocube aggregations to excite different plasmonic resonances. The s-polarization shows dramatic changes of the plasmonic resonances at different angles of incidence (shift of 64 nm per 10° angle of incidence). With a low surface nanocube coverage (from 5% to 20%), we observed a polarization-selective high absorption of 80% (with an average 75%) of the incoming light over a broad optical range in the visible region from 400 nm to 700 nm. This large-area gradient material with location-dependent optical properties can be of particular interest for broadband light absorption, phase-sensitive sensors, and imaging.We fabricated monolayer coatings of a silver nanocube aggregation to create a step-wise optical strip by applying different surface pressures during slow Langmuir-Blodgett deposition. The varying amount of randomly distributed nanocube aggregates with different surface coverages in gradient manner due to changes in surface pressure allows for continuous control of the polarization sensitive absorption of the incoming light over a broad optical spectrum. Optical characterization under total internal reflection conditions combined with electromagnetic simulations reveal that the broadband light absorption depends on the relative orientation of the nanoparticles to the polarization of the incoming light. By using computer simulations, we found that the electric field vector of the s-polarized light interacts with the different types of silver nanocube aggregations to excite different plasmonic resonances. The s-polarization shows dramatic changes of the plasmonic resonances at different angles of incidence (shift of 64 nm per 10° angle of incidence). With a low surface nanocube coverage (from 5% to 20%), we observed a polarization-selective high absorption of 80% (with an average 75%) of the incoming light over a broad optical range in the visible region from 400 nm to 700 nm. This large-area gradient material with location-dependent optical properties can be of particular interest for broadband light absorption, phase-sensitive sensors, and imaging. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06430e

Estimate of accuracy of determining the orientation of the star sensor system according to the experimental data

NASA Astrophysics Data System (ADS)

Avanesov, G. A.; Bessonov, R. V.; Kurkina, A. N.; Nikitin, A. V.; Sazonov, V. V.

2018-01-01

The BOKZ-M60 star sensor (Unit for Measuring Star Coordinates) is intended for determining the parameters of the orientation of the axes of the intrinsic coordinate system relative to the axes of the inertial system by observations of the regions of the stellar sky. It is convenient to characterize an error of the single determination of the orientation of the intrinsic coordinate system of the sensor by the vector of an infinitesimal turn of this system relative to its found position. Full-scale ground-based tests have shown that, for a resting sensor the root-mean-square values of the components of this vector along the axes of the intrinsic coordinate system lying in the plane of the sensor CCD matrix are less than 2″ and the component along the axis perpendicular to the matrix plane is characterized by the root-mean-square value of 15″. The joint processing of one-stage readings of several sensors installed on the same platform allows us to improve the indicated accuracy characteristics. In this paper, estimates of the accuracy of systems from BOKZ-M60 with two and four sensors performed from measurements carried out during the normal operation of these sensors on the Resurs-P satellite are given. Processing the measurements of the sensor system allowed us to increase the accuracy of determining the each of their orientations and to study random and systematic errors in these measurements.

A feasibility study of automatic lung nodule detection in chest digital tomosynthesis with machine learning based on support vector machine

NASA Astrophysics Data System (ADS)

Lee, Donghoon; Kim, Ye-seul; Choi, Sunghoon; Lee, Haenghwa; Jo, Byungdu; Choi, Seungyeon; Shin, Jungwook; Kim, Hee-Joung

2017-03-01

The chest digital tomosynthesis(CDT) is recently developed medical device that has several advantage for diagnosing lung disease. For example, CDT provides depth information with relatively low radiation dose compared to computed tomography (CT). However, a major problem with CDT is the image artifacts associated with data incompleteness resulting from limited angle data acquisition in CDT geometry. For this reason, the sensitivity of lung disease was not clear compared to CT. In this study, to improve sensitivity of lung disease detection in CDT, we developed computer aided diagnosis (CAD) systems based on machine learning. For design CAD systems, we used 100 cases of lung nodules cropped images and 100 cases of normal lesion cropped images acquired by lung man phantoms and proto type CDT. We used machine learning techniques based on support vector machine and Gabor filter. The Gabor filter was used for extracting characteristics of lung nodules and we compared performance of feature extraction of Gabor filter with various scale and orientation parameters. We used 3, 4, 5 scales and 4, 6, 8 orientations. After extracting features, support vector machine (SVM) was used for classifying feature of lesions. The linear, polynomial and Gaussian kernels of SVM were compared to decide the best SVM conditions for CDT reconstruction images. The results of CAD system with machine learning showed the capability of automatically lung lesion detection. Furthermore detection performance was the best when Gabor filter with 5 scale and 8 orientation and SVM with Gaussian kernel were used. In conclusion, our suggested CAD system showed improving sensitivity of lung lesion detection in CDT and decide Gabor filter and SVM conditions to achieve higher detection performance of our developed CAD system for CDT.

Orientationally invariant metrics of apparent compartment eccentricity from double pulsed field gradient diffusion experiments.

PubMed

Jespersen, Sune Nørhøj; Lundell, Henrik; Sønderby, Casper Kaae; Dyrby, Tim B

2013-12-01

Pulsed field gradient diffusion sequences (PFG) with multiple diffusion encoding blocks have been indicated to offer new microstructural tissue information, such as the ability to detect nonspherical compartment shapes in macroscopically isotropic samples, i.e. samples with negligible directional signal dependence on diffusion gradients in standard diffusion experiments. However, current acquisition schemes are not rotationally invariant in the sense that the derived metrics depend on the orientation of the sample, and are affected by the interplay of sampling directions and compartment orientation dispersion when applied to macroscopically anisotropic systems. Here we propose a new framework, the d-PFG 5-design, to enable rotationally invariant estimation of double wave vector diffusion metrics (d-PFG). The method is based on the idea that an appropriate orientational average of the signal emulates the signal from a powder preparation of the same sample, where macroscopic anisotropy is absent by construction. Our approach exploits the theory of exact numerical integration (quadrature) of polynomials on the rotation group, and we exemplify the general procedure with a set consisting of 60 pairs of diffusion wave vectors (the d-PFG 5-design) facilitating a theoretically exact determination of the fourth order Taylor or cumulant expansion of the orientationally averaged signal. The d-PFG 5-design is evaluated with numerical simulations and ex vivo high field diffusion MRI experiments in a nonhuman primate brain. Specifically, we demonstrate rotational invariance when estimating compartment eccentricity, which we show offers new microstructural information, complementary to that of fractional anisotropy (FA) from diffusion tensor imaging (DTI). The imaging observations are supported by a new theoretical result, directly relating compartment eccentricity to FA of individual pores. Copyright © 2013 John Wiley & Sons, Ltd.

Trimethylamine N-oxide (TMAO) and tert-butyl alcohol (TBA) at hydrophobic interfaces: insights from molecular dynamics simulations.

PubMed

Fiore, Andrew; Venkateshwaran, Vasudevan; Garde, Shekhar

2013-06-25

TMAO, a potent osmolyte, and TBA, a denaturant, have similar molecular architecture but somewhat different chemistry. We employ extensive molecular dynamics simulations to quantify their behavior at vapor-water and octane-water interfaces. We show that interfacial structure-density and orientation-and their dependence on solution concentration are markedly different for the two molecules. TMAO molecules are moderately surface active and adopt orientations with their N-O vector approximately parallel to the aqueous interface. That is, not all methyl groups of TMAO at the interface point away from the water phase. In contrast, TBA molecules act as molecular amphiphiles, are highly surface active, and, at low concentrations, adopt orientations with their methyl groups pointing away and the C-O vector pointing directly into water. The behavior of TMAO at aqueous interfaces is only weakly dependent on its solution concentration, whereas that of TBA depends strongly on concentration. We show that this concentration dependence arises from their different hydrogen bonding capabilities-TMAO can only accept hydrogen bonds from water, whereas TBA can accept (donate) hydrogen bonds from (to) water or other TBA molecules. The ability to self-associate, particularly visible in TBA molecules in the interfacial layer, allows them to sample a broad range of orientations at higher concentrations. In light of the role of TMAO and TBA in biomolecular stability, our results provide a reference with which to compare their behavior near biological interfaces. Also, given the ubiquity of aqueous interfaces in biology, chemistry, and technology, our results may be useful in the design of interfacially active small molecules with the aim to control their orientations and interactions.

Spacetime algebra as a powerful tool for electromagnetism

NASA Astrophysics Data System (ADS)

Dressel, Justin; Bliokh, Konstantin Y.; Nori, Franco

2015-08-01

We present a comprehensive introduction to spacetime algebra that emphasizes its practicality and power as a tool for the study of electromagnetism. We carefully develop this natural (Clifford) algebra of the Minkowski spacetime geometry, with a particular focus on its intrinsic (and often overlooked) complex structure. Notably, the scalar imaginary that appears throughout the electromagnetic theory properly corresponds to the unit 4-volume of spacetime itself, and thus has physical meaning. The electric and magnetic fields are combined into a single complex and frame-independent bivector field, which generalizes the Riemann-Silberstein complex vector that has recently resurfaced in studies of the single photon wavefunction. The complex structure of spacetime also underpins the emergence of electromagnetic waves, circular polarizations, the normal variables for canonical quantization, the distinction between electric and magnetic charge, complex spinor representations of Lorentz transformations, and the dual (electric-magnetic field exchange) symmetry that produces helicity conservation in vacuum fields. This latter symmetry manifests as an arbitrary global phase of the complex field, motivating the use of a complex vector potential, along with an associated transverse and gauge-invariant bivector potential, as well as complex (bivector and scalar) Hertz potentials. Our detailed treatment aims to encourage the use of spacetime algebra as a readily available and mature extension to existing vector calculus and tensor methods that can greatly simplify the analysis of fundamentally relativistic objects like the electromagnetic field.

Optimal run-and-tumble-based transportation of a Janus particle with active steering

NASA Astrophysics Data System (ADS)

Mano, Tomoyuki; Delfau, Jean-Baptiste; Iwasawa, Junichiro; Sano, Masaki

2017-03-01

Although making artificial micrometric swimmers has been made possible by using various propulsion mechanisms, guiding their motion in the presence of thermal fluctuations still remains a great challenge. Such a task is essential in biological systems, which present a number of intriguing solutions that are robust against noisy environmental conditions as well as variability in individual genetic makeup. Using synthetic Janus particles driven by an electric field, we present a feedback-based particle-guiding method quite analogous to the “run-and-tumbling” behavior of Escherichia coli but with a deterministic steering in the tumbling phase: the particle is set to the run state when its orientation vector aligns with the target, whereas the transition to the “steering” state is triggered when it exceeds a tolerance angle αα. The active and deterministic reorientation of the particle is achieved by a characteristic rotational motion that can be switched on and off by modulating the ac frequency of the electric field, which is reported in this work. Relying on numerical simulations and analytical results, we show that this feedback algorithm can be optimized by tuning the tolerance angle αα. The optimal resetting angle depends on signal to noise ratio in the steering state, and it is shown in the experiment. The proposed method is simple and robust for targeting, despite variability in self-propelling speeds and angular velocities of individual particles.

Effect of cubic Dresselhaus interaction on the longitudinal optical conductivity of a spin-orbit coupled system

NASA Astrophysics Data System (ADS)

Cruz, Elmer; López-Bastidas, Catalina; Maytorena, Jesús A.

2018-03-01

We investigate the effect of the oft-neglected cubic terms of the Dresselhaus spin-orbit coupling on the longitudinal current response of a two-dimensional electron gas with both Rashba and linear Dresselhaus interactions. For a quantum well grown in the [001] direction, the changes caused by these nonlinear-in-momentum terms on the absorption spectrum become more notable under SU(2) symmetry conditions, when the Rashba and linear Dresselhaus coupling strengths are tuned to be equal. The longitudinal optical response no longer vanishes then and shows a strong dependence on the direction of the externally applied electric field, giving a signature of the relative size of several spin-orbit contributions. This anisotropic response arises from the nonisotropic splitting of the spin states induced by the interplay of Rashba and Dresselhaus couplings. However, the presence of cubic terms introduces characteristic spectral features and can modify the overall shape of the spectra for some values of the relative sizes of the spin-orbit parameters. We compare this behavior to the case of a sample with [110] crystal orientation which, under conditions of spin-preserving symmetry, has a collinear spin-orbit vector field that leads to vanishing conductivity, even in the presence of cubic terms. In addition to the control through the driven frequency or electrical gating, such a directional aspect of the current response suggests new ways of manipulation and supports the use of interband optics as a sensitive probe of spin-orbit mechanisms in semiconductor spintronics.

Strategic avionics technology definition studies. Subtask 3-1A3: Electrical Actuation (ELA) Systems Test Facility

NASA Technical Reports Server (NTRS)

Rogers, J. P.; Cureton, K. L.; Olsen, J. R.

1994-01-01

Future aerospace vehicles will require use of the Electrical Actuator systems for flight control elements. This report presents a proposed ELA Test Facility for dynamic evaluation of high power linear Electrical Actuators with primary emphasis on Thrust Vector Control actuators. Details of the mechanical design, power and control systems, and data acquisition capability of the test facility are presented. A test procedure for evaluating the performance of the ELA Test Facility is also included.

Electric Propulsion: Experimental Research

NASA Technical Reports Server (NTRS)

Ruyten, W. M.; Friedly, V. J.; Keefer, D.

1995-01-01

This paper describes experimental electric propulsion research which was carried out at the University of Tennessee Space Institute with support from the Center for Space Transportation and Applied Research. Specifically, a multiplexed LIF technique for obtaining vector velocities, Doppler temperatures, and relative number densities in the exhaust plumes form electric propulsion devices is described, and results are presented that were obtained on a low power argon arcjet. Also, preliminary Langmuir probe measurements on an ion source are described, and an update on the vacuum facility is presented.

Electric propulsion: Experimental research

NASA Technical Reports Server (NTRS)

Ruyten, W. M.; Friedly, V. J.; Keefer, D.

1992-01-01

This paper describes experimental electric propulsion research which was carried out at the University of Tennessee Space Institute with support from the Center for Space Transportation and Applied Research. Specifically, a multiplexed laser induced fluorescence (LIF) technique for obtaining vector velocities, Doppler temperatures, and relative number densities in the exhaust plumes from electric propulsion devices is described, and results are presented that were obtained on a low power argon arcjet. Also, preliminary Langmuir probe measurements on an ion source are described, and an update on the vacuum facility is presented.

Note on the helicity decomposition of spin and orbital optical currents

NASA Astrophysics Data System (ADS)

Aiello, Andrea; Berry, M. V.

2015-06-01

In the helicity representation, the Poynting vector (current) for a monochromatic optical field, when calculated using either the electric or the magnetic field, separates into right-handed and left-handed contributions, with no cross-helicity contributions. Cross-helicity terms do appear in the orbital and spin contributions to the current. But when the electric and magnetic formulas are averaged (‘electric-magnetic democracy’), these terms cancel, restoring the separation into right-handed and left-handed currents for orbital and spin separately.

Stress-oriented driver assistance system for electric vehicles.

PubMed

Athanasiou, Georgia; Tsotoulidis, Savvas; Mitronikas, Epaminondas; Lymberopoulos, Dimitrios

2014-01-01

Stress is physiological and physical reaction that appears in highly demanding situations and affects human's perception and reaction capability. Occurrence of stress events within highly dynamic road environment could lead to life-threatening situation. With the perspective of safety and comfort driving provision to anxious drivers, in this paper a stress-oriented Driver Assistance System (DAS) is proposed. The DAS deployed on Electric Vehicle. This novel DAS customizes driving command signal in respect to road context, when stress is detected. The effectiveness of this novel DAS is verified by simulation in MATLAB/SIMULINK environment.

Photothermal Nanocomposite Hydrogel Actuator with Electric-Field-Induced Gradient and Oriented Structure.

PubMed

Yang, Yang; Tan, Yun; Wang, Xionglei; An, Wenli; Xu, Shimei; Liao, Wang; Wang, Yuzhong

2018-03-07

Recent research of hydrogel actuators is still not sophisticated enough to meet the requirement of fast, reversible, complex, and robust reconfiguration. Here, we present a new kind of poly( N-isopropylacrylamide)/graphene oxide gradient hydrogel by utilizing direct current electric field to induce gradient and oriented distribution of graphene oxide into poly( N-isopropylacrylamide) hydrogel. Upon near-infrared light irradiation, the hydrogel exhibited excellent comprehensive actuation performance as a result of directional bending deformation, promising great potential in the application of soft actuators and optomechanical system.

Methods for controlling pore morphology in aerogels using electric fields and products thereof

DOE Office of Scientific and Technical Information (OSTI.GOV)

Worsley, Marcus A.; Baumann, Theodore F.; Satcher, Jr., Joe H.

In one embodiment, an aerogel or xerogel includes column structures of a material having minor pores therein and major pores devoid of the material positioned between the column structures, where longitudinal axes of the major pores are substantially parallel to one another. In another embodiment, a method includes heating a sol including aerogel or xerogel precursor materials to cause gelation thereof to form an aerogel or xerogel and exposing the heated sol to an electric field, wherein the electric field causes orientation of a microstructure of the sol during gelation, which is retained by the aerogel or xerogel. In onemore » approach, an aerogel has elongated pores extending between a material arranged in column structures having structural characteristics of being formed from a sol exposed to an electric field that causes orientation of a microstructure of the sol during gelation which is retained by the elongated pores of the aerogel.« less

An all-electric single-molecule motor.

PubMed

Seldenthuis, Johannes S; Prins, Ferry; Thijssen, Joseph M; van der Zant, Herre S J

2010-11-23

Many types of molecular motors have been proposed and synthesized in recent years, displaying different kinds of motion, and fueled by different driving forces such as light, heat, or chemical reactions. We propose a new type of molecular motor based on electric field actuation and electric current detection of the rotational motion of a molecular dipole embedded in a three-terminal single-molecule device. The key aspect of this all-electronic design is the conjugated backbone of the molecule, which simultaneously provides the potential landscape of the rotor orientation and a real-time measure of that orientation through the modulation of the conductivity. Using quantum chemistry calculations, we show that this approach provides full control over the speed and continuity of motion, thereby combining electrical and mechanical control at the molecular level over a wide range of temperatures. Moreover, chemistry can be used to change all key parameters of the device, enabling a variety of new experiments on molecular motors.

Role of crystal orientation on electrical tuning of dynamic permeability in strain-mediated multiferroic structures

NASA Astrophysics Data System (ADS)

Phuoc, Nguyen N.; Ong, C. K.

2017-06-01

Multiferroic structures of FeCo/NiFe/[Pb(Mg1/3Nb2/3)O3]0.68-[PbTiO3]0.32 (PMN-PT) with three different crystal orientations of PMN-PT(0 1 1), PMN-PT(0 0 1) and PMN-PT(1 1 1) were fabricated by a sputtering deposition system. Their dynamic magnetic properties were characterized under various applied electrical fields. The sample with PMN-PT(0 1 1) orientation shows a large tuning of the permeability spectra while the ones with PMN-PT(0 0 1) and PMN-PT(1 1 1) orientations exhibit a moderate and little change in the permeability spectra, respectively. The result can be explained via the magnetoelectric effect by considering the role of the piezoelectric coefficients being highly dependent on the crystal orientation along which the PMN-PT is poled. This explanation is consistent with the static magnetic characteristics of the samples before and after poling.

Turbine Engine Component Analysis: Cantilevered Composite Flat Plate Analysis

DTIC Science & Technology

1989-11-01

4/5 element which translates into the ADIN. shell element (Type 7) with thickness correction. PATADI automatically generates midsurface normal vectors...for each node referenced by a shell element. Using thickness correction, the element thickness will be oriented along the midsurface direction. If no

Anisotropy of electrical conductivity in dc due to intrinsic defect formation in α-Al2O3 single crystal implanted with Mg ions

NASA Astrophysics Data System (ADS)

Tardío, M.; Egaña, A.; Ramírez, R.; Muñoz-Santiuste, J. E.; Alves, E.

2016-07-01

The electrical conductivity in α-Al2O3 single crystals implanted with Mg ions in two different crystalline orientations, parallel and perpendicular to c axis, was investigated. The samples were implanted at room temperature with energies of 50 and 100 keV and fluences of 1 × 1015, 5 × 1015 and 5 × 1016 ions/cm2. Optical characterization reveals slight differences in the absorption bands at 6.0 and 4.2 eV, attributed to F type centers and Mie scattering from Mg precipitates, respectively. DC electrical measurements using the four and two-point probe methods, between 295 and 490 K, were used to characterize the electrical conductivity of the implanted area (Meshakim and Tanabe, 2001). Measurements in this temperature range indicate that: (1) the electrical conductivity is thermally activated independently of crystallographic orientation, (2) resistance values in the implanted region decrease with fluence levels, and (3) the I-V characteristic of electrical contacts in samples with perpendicular c axis orientation is clearly ohmic, whereas contacts are blocking in samples with parallel c axis. When thin layers are sequentially removed from the implanted region by immersing the sample in a hot solution of nitric and fluorhydric acids the electrical resistance increases until reaching the values of non-implanted crystal (Jheeta et al., 2006). We conclude that the enhancement in conductivity observed in the implanted regions is related to the intrinsic defects created by the implantation rather than to the implanted Mg ions (da Silva et al., 2002; Tardío et al., 2001; Tardío et al., 2008).

Kalman-Filter-Based Orientation Determination Using Inertial/Magnetic Sensors: Observability Analysis and Performance Evaluation

PubMed Central

Sabatini, Angelo Maria

2011-01-01

In this paper we present a quaternion-based Extended Kalman Filter (EKF) for estimating the three-dimensional orientation of a rigid body. The EKF exploits the measurements from an Inertial Measurement Unit (IMU) that is integrated with a tri-axial magnetic sensor. Magnetic disturbances and gyro bias errors are modeled and compensated by including them in the filter state vector. We employ the observability rank criterion based on Lie derivatives to verify the conditions under which the nonlinear system that describes the process of motion tracking by the IMU is observable, namely it may provide sufficient information for performing the estimation task with bounded estimation errors. The observability conditions are that the magnetic field, perturbed by first-order Gauss-Markov magnetic variations, and the gravity vector are not collinear and that the IMU is subject to some angular motions. Computer simulations and experimental testing are presented to evaluate the algorithm performance, including when the observability conditions are critical. PMID:22163689

Interplanetary sector boundaries, 1971 - 1973

NASA Technical Reports Server (NTRS)

Klein, L.; Burlaga, L. F.

1979-01-01

Eighteen interplanetary sector boundary crossings observed at 1 AU by the magnetometer on the IMP-6 spacecraft are discussed. The events were examined on many different time scales ranging from days on either side of the boundary to high resolution measurements of 12.5 vectors per second. Two categories of boundaries were found, one group being relatively thin and the other being thick. In many cases the field vector rotated in a plane from one polarity to the other. Only two of the transitions were null sheets. Using the minimum variance analysis to determine the normals to the plane of rotation, and assuming that this is the same as the normal to the sector boundary surface, it was found that the normals were close to the ecliptic plane. An analysis of tangential discontinuities contained in 4-day periods about the events showed that their orientations were generally not related to the orientations of the sector boundary surface, but rather their characteristics were about the same as those for discontinuities outside the sector boundaries.

Images of Bottomside Irregularities Observed at Topside Altitudes (Postprint)

DTIC Science & Technology

2012-04-04

pairs of 20 m tip-to-tip double probes and a fluxgate magnetometer on a 0.6 m boom [Pfaff et al., 2010]. Vector electric fields are obtained with 16-bit... magnetometer out- puts. AC electric fields are measured by passing VEFI data streams though low (0–6 Hz) and high-pass (3–8,000 Hz) filters. AC magnetic field

Micropulsations in the electric field near the plasmapause, observed by ISEE-1

NASA Technical Reports Server (NTRS)

Moe, T. E.; Maynard, N. C.; Heppner, J. P.

1979-01-01

The occurrence of micropulsations near and inside the plasmapause was surveyed. The observed pulsations, classified as Pc3 and Pi2, are discussed. In addition one single event of Pc1 was observed. The frequencies in the Pc3 and Pi2 bands, the amplitude ranges, and the direction of rotation for the electric field vector are reported.

Theoretical study of the generation of terahertz radiation by the interaction of two laser beams with graphite nanoparticles

NASA Astrophysics Data System (ADS)

Sepehri Javan, N.; Rouhi Erdi, F.

2017-12-01

In this theoretical study, we investigate the generation of terahertz radiation by considering the beating of two similar Gaussian laser beams with different frequencies of ω1 and ω2 in a spatially modulated medium of graphite nanoparticles. The medium is assumed to contain spherical graphite nanoparticles of two different configurations: in the first configuration, the electric fields of the laser beams are parallel to the normal vector of the basal plane of the graphite structure, whereas in the second configuration, the electric fields are perpendicular to the normal vector of the basal plane. The interaction of the electric fields of lasers with the electronic clouds of the nanoparticles generates a ponderomotive force that in turn leads to the creation of a macroscopic electron current in the direction of laser polarizations and at the beat frequency ω1-ω2 , which can generate terahertz radiation. We show that, when the beat frequency lies near the effective plasmon frequency of the nanoparticles and the electric fields are parallel to the basal-plane normal, a resonant interaction of the laser beams causes intense terahertz radiation.

Tilted hexagonal post arrays: DNA electrophoresis in anisotropic media.

PubMed

Chen, Zhen; Dorfman, Kevin D

2014-02-01

Using Brownian dynamics simulations, we show that DNA electrophoresis in a hexagonal array of micron-sized posts changes qualitatively when the applied electric field vector is not coincident with the lattice vectors of the array. DNA electrophoresis in such "tilted" post arrays is superior to the standard "un-tilted" approach; while the time required to achieve a resolution of unity in a tilted post array is similar to an un-tilted array at a low-electric field strengths, this time (i) decreases exponentially with electric field strength in a tilted array and (ii) increases exponentially with electric field strength in an un-tilted array. Although the DNA dynamics in a post array are complicated, the electrophoretic mobility results indicate that the "free path," i.e. the average distance of ballistic trajectories of point-sized particles launched from random positions in the unit cell until they intersect the next post, is a useful proxy for the detailed DNA trajectories. The analysis of the free path reveals a fundamental connection between anisotropy of the medium and DNA transport therein that goes beyond simply improving the separation device. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A pair of new BAC and BIBAC vectors that facilitate BAC/BIBAC library construction and intact large genomic DNA insert exchange.

PubMed

Shi, Xue; Zeng, Haiyang; Xue, Yadong; Luo, Meizhong

2011-10-11

Large-insert BAC and BIBAC libraries are important tools for structural and functional genomics studies of eukaryotic genomes. To facilitate the construction of BAC and BIBAC libraries and the transfer of complete large BAC inserts into BIBAC vectors, which is desired in positional cloning, we developed a pair of new BAC and BIBAC vectors. The new BAC vector pIndigoBAC536-S and the new BIBAC vector BIBAC-S have the following features: 1) both contain two 18-bp non-palindromic I-SceI sites in an inverted orientation at positions that flank an identical DNA fragment containing the lacZ selection marker and the cloning site. Large DNA inserts can be excised from the vectors as single fragments by cutting with I-SceI, allowing the inserts to be easily sized. More importantly, because the two vectors contain different antibiotic resistance genes for transformant selection and produce the same non-complementary 3' protruding ATAA ends by I-SceI that suppress self- and inter-ligations, the exchange of intact large genomic DNA inserts between the BAC and BIBAC vectors is straightforward; 2) both were constructed as high-copy composite vectors. Reliable linearized and dephosphorylated original low-copy pIndigoBAC536-S and BIBAC-S vectors that are ready for library construction can be prepared from the high-copy composite vectors pHZAUBAC1 and pHZAUBIBAC1, respectively, without the need for additional preparation steps or special reagents, thus simplifying the construction of BAC and BIBAC libraries. BIBAC clones constructed with the new BIBAC-S vector are stable in both E. coli and Agrobacterium. The vectors can be accessed through our website http://GResource.hzau.edu.cn. The two new vectors and their respective high-copy composite vectors can largely facilitate the construction and characterization of BAC and BIBAC libraries. The transfer of complete large genomic DNA inserts from one vector to the other is made straightforward.

Benefit from NASA

NASA Image and Video Library

1993-01-01

The development of the electric space actuator represents an unusual case of space technology transfer wherein the product was commercialized before it was used for the intended space purpose. MOOG, which supplies the thrust vector control hydraulic actuators for the Space Shuttle and brake actuators for the Space Orbiter, initiated development of electric actuators for aerospace and industrial use in the early 1980s. NASA used the technology to develop an electric replacement for the Space Shuttle main engine TVC actuator. An electric actuator is used to take passengers on a realistic flight to Jupiter at the US Space and Rocket Center, Huntsville, Alabama.

A simple device to illustrate the Einthoven triangle

PubMed Central

Jin, Benjamin E.; Wulff, Heike; Widdicombe, Jonathan H.; Zheng, Jie; Bers, Donald M.

2012-01-01

The Einthoven triangle is central to the field of electrocardiography, but the concept of cardiac vectors is often a difficult notion for students to grasp. To illustrate this principle, we constructed a device that recreates the conditions of an ECG reading using a battery to simulate the electrical vector of the heart and three voltmeters for the main electrocardiographic leads. Requiring minimal construction with low cost, this device provides hands-on practice that enables students to rediscover the principles of the Einthoven triangle, namely, that the direction of the cardiac dipole can be predicted from the deflections in any two leads and that lead I + lead III = lead II independent of the position of heart's electrical vector. We built a total of 6 devices for classes of 30 students and tested them in the first-year Human Physiology course at the University of California-Davis School of Medicine. Combined with traditional demonstrations with ECG machines, this equipment demonstrated its ability to help medical students obtain a solid foundation of the basic principles of electrocardiography. PMID:23209014

Dynamic Price Vector Formation Model-Based Automatic Demand Response Strategy for PV-Assisted EV Charging Stations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Qifang; Wang, Fei; Hodge, Bri-Mathias

A real-time price (RTP)-based automatic demand response (ADR) strategy for PV-assisted electric vehicle (EV) Charging Station (PVCS) without vehicle to grid is proposed. The charging process is modeled as a dynamic linear program instead of the normal day-ahead and real-time regulation strategy, to capture the advantages of both global and real-time optimization. Different from conventional price forecasting algorithms, a dynamic price vector formation model is proposed based on a clustering algorithm to form an RTP vector for a particular day. A dynamic feasible energy demand region (DFEDR) model considering grid voltage profiles is designed to calculate the lower and uppermore » bounds. A deduction method is proposed to deal with the unknown information of future intervals, such as the actual stochastic arrival and departure times of EVs, which make the DFEDR model suitable for global optimization. Finally, both the comparative cases articulate the advantages of the developed methods and the validity in reducing electricity costs, mitigating peak charging demand, and improving PV self-consumption of the proposed strategy are verified through simulation scenarios.« less

Confidence regions of planar cardiac vectors

NASA Technical Reports Server (NTRS)

Dubin, S.; Herr, A.; Hunt, P.

1980-01-01

A method for plotting the confidence regions of vectorial data obtained in electrocardiology is presented. The 90%, 95% and 99% confidence regions of cardiac vectors represented in a plane are obtained in the form of an ellipse centered at coordinates corresponding to the means of a sample selected at random from a bivariate normal distribution. An example of such a plot for the frontal plane QRS mean electrical axis for 80 horses is also presented.

Subband directional vector quantization in radiological image compression

NASA Astrophysics Data System (ADS)

Akrout, Nabil M.; Diab, Chaouki; Prost, Remy; Goutte, Robert; Amiel, Michel

1992-05-01

The aim of this paper is to propose a new scheme for image compression. The method is very efficient for images which have directional edges such as the tree-like structure of the coronary vessels in digital angiograms. This method involves two steps. First, the original image is decomposed at different resolution levels using a pyramidal subband decomposition scheme. For decomposition/reconstruction of the image, free of aliasing and boundary errors, we use an ideal band-pass filter bank implemented in the Discrete Cosine Transform domain (DCT). Second, the high-frequency subbands are vector quantized using a multiresolution codebook with vertical and horizontal codewords which take into account the edge orientation of each subband. The proposed method reduces the blocking effect encountered at low bit rates in conventional vector quantization.

The Eccentric Behavior of Nearly Frozen Orbits

NASA Technical Reports Server (NTRS)

Sweetser, Theodore H.; Vincent, Mark A.

2013-01-01

Frozen orbits are orbits which have only short-period changes in their mean eccentricity and argument of periapse, so that they basically keep a fixed orientation within their plane of motion. Nearly frozen orbits are those whose eccentricity and argument of periapse have values close to those of a frozen orbit. We call them "nearly" frozen because their eccentricity vector (a vector whose polar coordinates are eccentricity and argument of periapse) will stay within a bounded distance from the frozen orbit eccentricity vector, circulating around it over time. For highly inclined orbits around the Earth, this distance is effectively constant over time. Furthermore, frozen orbit eccentricity values are low enough that these orbits are essentially eccentric (i.e., off center) circles, so that nearly frozen orbits around Earth are bounded above and below by frozen orbits.

Viral vector-based tools advance knowledge of basal ganglia anatomy and physiology.

PubMed

Sizemore, Rachel J; Seeger-Armbruster, Sonja; Hughes, Stephanie M; Parr-Brownlie, Louise C

2016-04-01

Viral vectors were originally developed to deliver genes into host cells for therapeutic potential. However, viral vector use in neuroscience research has increased because they enhance interpretation of the anatomy and physiology of brain circuits compared with conventional tract tracing or electrical stimulation techniques. Viral vectors enable neuronal or glial subpopulations to be labeled or stimulated, which can be spatially restricted to a single target nucleus or pathway. Here we review the use of viral vectors to examine the structure and function of motor and limbic basal ganglia (BG) networks in normal and pathological states. We outline the use of viral vectors, particularly lentivirus and adeno-associated virus, in circuit tracing, optogenetic stimulation, and designer drug stimulation experiments. Key studies that have used viral vectors to trace and image pathways and connectivity at gross or ultrastructural levels are reviewed. We explain how optogenetic stimulation and designer drugs used to modulate a distinct pathway and neuronal subpopulation have enhanced our mechanistic understanding of BG function in health and pathophysiology in disease. Finally, we outline how viral vector technology may be applied to neurological and psychiatric conditions to offer new treatments with enhanced outcomes for patients. Copyright © 2016 the American Physiological Society.

Viral vector-based tools advance knowledge of basal ganglia anatomy and physiology

PubMed Central

Sizemore, Rachel J.; Seeger-Armbruster, Sonja; Hughes, Stephanie M.

2016-01-01

Viral vectors were originally developed to deliver genes into host cells for therapeutic potential. However, viral vector use in neuroscience research has increased because they enhance interpretation of the anatomy and physiology of brain circuits compared with conventional tract tracing or electrical stimulation techniques. Viral vectors enable neuronal or glial subpopulations to be labeled or stimulated, which can be spatially restricted to a single target nucleus or pathway. Here we review the use of viral vectors to examine the structure and function of motor and limbic basal ganglia (BG) networks in normal and pathological states. We outline the use of viral vectors, particularly lentivirus and adeno-associated virus, in circuit tracing, optogenetic stimulation, and designer drug stimulation experiments. Key studies that have used viral vectors to trace and image pathways and connectivity at gross or ultrastructural levels are reviewed. We explain how optogenetic stimulation and designer drugs used to modulate a distinct pathway and neuronal subpopulation have enhanced our mechanistic understanding of BG function in health and pathophysiology in disease. Finally, we outline how viral vector technology may be applied to neurological and psychiatric conditions to offer new treatments with enhanced outcomes for patients. PMID:26888111

Gate control of quantum dot-based electron spin-orbit qubits

NASA Astrophysics Data System (ADS)

Wu, Shudong; Cheng, Liwen; Yu, Huaguang; Wang, Qiang

2018-07-01

We investigate theoretically the coherent spin dynamics of gate control of quantum dot-based electron spin-orbit qubits subjected to a tilted magnetic field under electric-dipole spin resonance (EDSR). Our results reveal that Rabi oscillation of qubit states can be manipulated electrically based on rapid gate control of SOC strength. The Rabi frequency is strongly dependent on the gate-induced electric field, the strength and orientation of the applied magnetic field. There are two major EDSR mechanisms. One arises from electric field-induced spin-orbit hybridization, and the other arises from magnetic field-induced energy-level crossing. The SOC introduced by the gate-induced electric field allows AC electric fields to drive coherent Rabi oscillations between spin-up and -down states. After the crossing of the energy-levels with the magnetic field, the spin-transfer crossing results in Rabi oscillation irrespective of whether or not the external electric field is present. The spin-orbit qubit is transferred into the orbit qubit. Rabi oscillation is anisotropic and periodic with respect to the tilted and in-plane orientation of the magnetic field originating from the interplay of the SOC, orbital, and Zeeman effects. The strong electrically-controlled SOC strength suggests the possibility for scalable applications of gate-controllable spin-orbit qubits.

Transverse spin and transverse momentum in scattering of plane waves.

PubMed

Saha, Sudipta; Singh, Ankit K; Ray, Subir K; Banerjee, Ayan; Gupta, Subhasish Dutta; Ghosh, Nirmalya

2016-10-01

We study the near field to the far field evolution of spin angular momentum (SAM) density and the Poynting vector of the scattered waves from spherical scatterers. The results show that at the near field, the SAM density and the Poynting vector are dominated by their transverse components. While the former (transverse SAM) is independent of the helicity of the incident circular polarization state, the latter (transverse Poynting vector) depends upon the polarization state. It is further demonstrated that the interference of the transverse electric and transverse magnetic scattering modes enhances both the magnitudes and the spatial extent of the transverse SAM and the transverse momentum components.

EM-ANIMATE - COMPUTER PROGRAM FOR DISPLAYING AND ANIMATING THE STEADY-STATE TIME-HARMONIC ELECTROMAGNETIC NEAR FIELD AND SURFACE-CURRENT SOLUTIONS

NASA Technical Reports Server (NTRS)

Hom, K. W.

1994-01-01

The EM-ANIMATE program is a specialized visualization program that displays and animates the near-field and surface-current solutions obtained from an electromagnetics program, in particular, that from MOM3D (LAR-15074). The EM-ANIMATE program is windows based and contains a user-friendly, graphical interface for setting viewing options, case selection, file manipulation, etc. EM-ANIMATE displays the field and surface-current magnitude as smooth shaded color fields (color contours) ranging from a minimum contour value to a maximum contour value for the fields and surface currents. The program can display either the total electric field or the scattered electric field in either time-harmonic animation mode or in the root mean square (RMS) average mode. The default setting is initially set to the minimum and maximum values within the field and surface current data and can be optionally set by the user. The field and surface-current value are animated by calculating and viewing the solution at user selectable radian time increments between 0 and 2pi. The surface currents can also be displayed in either time-harmonic animation mode or in RMS average mode. In RMS mode, the color contours do not vary with time, but show the constant time averaged field and surface-current magnitude solution. The electric field and surface-current directions can be displayed as scaled vector arrows which have a length proportional to the magnitude at each field grid point or surface node point. These vector properties can be viewed separately or concurrently with the field or surface-current magnitudes. Animation speed is improved by turning off the display of the vector arrows. In RMS modes, the direction vectors are still displayed as varying with time since the time averaged direction vectors would be zero length vectors. Other surface properties can optionally be viewed. These include the surface grid, the resistance value assigned to each element of the grid, and the power dissipation of each element which has an assigned resistance value. The EM-ANIMATE program will accept up to 10 different surface current cases each consisting of up to 20,000 node points and 10,000 triangle definitions and will animate one of these cases. The capability is used to compare surface-current distribution due to various initial excitation directions or electric field orientations. The program can accept up to 50 planes of field data consisting of a grid of 100 by 100 field points. These planes of data are user selectable and can be viewed individually or concurrently. With these preset limits, the program requires 55 megabytes of core memory to run. These limits can be changed in the header files to accommodate the available core memory of an individual workstation. An estimate of memory required can be made as follows: approximate memory in bytes equals (number of nodes times number of surfaces times 14 variables times bytes per word, typically 4 bytes per floating point) plus (number of field planes times number of nodes per plane times 21 variables times bytes per word). This gives the approximate memory size required to store the field and surface-current data. The total memory size is approximately 400,000 bytes plus the data memory size. The animation calculations are performed in real time at any user set time step. For Silicon Graphics Workstations that have multiple processors, this program has been optimized to perform these calculations on multiple processors to increase animation rates. The optimized program uses the SGI PFA (Power FORTRAN Accelerator) library. On single processor machines, the parallelization directives are seen as comments to the program and will have no effect on compilation or execution. EM-ANIMATE is written in FORTRAN 77 for implementation on SGI IRIS workstations running IRIX 3.0 or later. A minimum of 55Mb of RAM is required for execution of this program; however, the code may be modified to accommodate the available memory of an individual workstation. For program execution, twenty-four bit, double-buffered color capability is suggested, but not required. Sample input and output files and a sample executable are provided on the distribution medium. Electronic documentation is provided in PostScript format and in the form of IRIX man pages. The standard distribution medium for EM-ANIMATE is a .25 inch streaming magnetic IRIX tape cartridge in UNIX tar format. EM-ANIMATE is also available as part of a bundled package, COS-10048 that includes MOM3D, an IRIS program that produces electromagnetic near field and surface current solutions. This program was developed in 1993.

Start-up of electrophoresis of an arbitrarily oriented dielectric cylinder.

PubMed

Chen, Guan Y; Keh, Huan J

2014-09-01

An analytical study is presented for the transient electrophoretic response of a circular cylindrical particle to the step application of an electric field. The electric double layer adjacent to the particle surface is thin but finite compared with the radius of the particle. The time-evolving electroosmotic velocity at the outer boundary of the double layer is utilized as a slip condition so that the transient momentum conservation equation for the bulk fluid flow is solved. Explicit formulas for the unsteady electrophoretic velocity of the particle are obtained for both axially and transversely applied electric fields, and can be linearly superimposed for an arbitrarily-oriented applied field. If the cylindrical particle is neutrally buoyant in the suspending fluid, the transient electrophoretic velocity is independent of the orientation of the particle relative to the applied electric field and will be in the direction of the applied field. If the particle is different in density from the fluid, then the direction of electrophoresis will not coincide with that of the applied field until the steady state is attained. The growth of the electrophoretic mobility with the elapsed time for a cylindrical particle is substantially slower than for a spherical particle. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Developing Multimedia Courseware for the Internet's Java versus Shockwave.

ERIC Educational Resources Information Center

Majchrzak, Tina L.

1996-01-01

Describes and compares two methods for developing multimedia courseware for use on the Internet: an authoring tool called Shockwave, and an object-oriented language called Java. Topics include vector graphics, browsers, interaction with network protocols, data security, multithreading, and computer languages versus development environments. (LRW)

Anomalous Rashba spin-orbit interaction in electrically controlled topological insulator based on InN/GaN quantum wells

NASA Astrophysics Data System (ADS)

Łepkowski, Sławomir P.; Bardyszewski, Witold

2017-05-01

We study theoretically the topological phase transition and the Rashba spin-orbit interaction in electrically biased InN/GaN quantum wells. We show that that for properly chosen widths of quantum wells and barriers, one can effectively tune the system through the topological phase transition applying an external electric field perpendicular to the QW plane. We find that in InN/GaN quantum wells with the inverted band structure, when the conduction band s-type level is below the heavy hole and light hole p-type levels, the spin splitting of the subbands decreases with increasing the amplitude of the electric field in the quantum wells, which reveals the anomalous Rashba effect. Derived effective Rashba Hamiltonians can describe the subband spin splitting only for very small wave vectors due to strong coupling between the subbands. Furthermore, we demonstrate that for InN/GaN quantum wells in a Hall bar geometry, the critical voltage for the topological phase transition depends distinctly on the width of the structure and a significant spin splitting of the edge states lying in the 2D band gap can be almost switched off by increasing the electric field in quantum wells only by a few percent. We show that the dependence of the spin splitting of the upper branch of the edge state dispersion curve on the wave vector has a threshold-like behavior with the on/off spin splitting ratio reaching two orders of magnitude for narrow Hall bars. The threshold wave vector depends weakly on the Hall bar width, whereas it increases significantly with the bias voltage due to an increase of the energetic distance between the s-type and p-type quantum well energy levels and a reduction of the coupling between the subbands.

Anomalous Rashba spin-orbit interaction in electrically controlled topological insulator based on InN/GaN quantum wells.

PubMed

Łepkowski, Sławomir P; Bardyszewski, Witold

2017-05-17

We study theoretically the topological phase transition and the Rashba spin-orbit interaction in electrically biased InN/GaN quantum wells. We show that that for properly chosen widths of quantum wells and barriers, one can effectively tune the system through the topological phase transition applying an external electric field perpendicular to the QW plane. We find that in InN/GaN quantum wells with the inverted band structure, when the conduction band s-type level is below the heavy hole and light hole p-type levels, the spin splitting of the subbands decreases with increasing the amplitude of the electric field in the quantum wells, which reveals the anomalous Rashba effect. Derived effective Rashba Hamiltonians can describe the subband spin splitting only for very small wave vectors due to strong coupling between the subbands. Furthermore, we demonstrate that for InN/GaN quantum wells in a Hall bar geometry, the critical voltage for the topological phase transition depends distinctly on the width of the structure and a significant spin splitting of the edge states lying in the 2D band gap can be almost switched off by increasing the electric field in quantum wells only by a few percent. We show that the dependence of the spin splitting of the upper branch of the edge state dispersion curve on the wave vector has a threshold-like behavior with the on/off spin splitting ratio reaching two orders of magnitude for narrow Hall bars. The threshold wave vector depends weakly on the Hall bar width, whereas it increases significantly with the bias voltage due to an increase of the energetic distance between the s-type and p-type quantum well energy levels and a reduction of the coupling between the subbands.

Blow molding electric drives of Mechanical Engineering

NASA Astrophysics Data System (ADS)

Bukhanov, S. S.; Ramazanov, M. A.; Tsirkunenko, A. T.

2018-03-01

The article considers the questions about the analysis of new possibilities, which gives the use of adjustable electric drives for blowing mechanisms of plastic production. Thus, the use of new semiconductor converters makes it possible not only to compensate the instability of the supply network by using special dynamic voltage regulators, but to improve (correct) the power factor. The calculation of economic efficiency in controlled electric drives of blowing mechanisms is given. On the basis of statistical analysis, the calculation of the reliability parameters of the regulated electric drives’ elements under consideration is given. It is shown that an increase in the reliability of adjustable electric drives is possible both due to overestimation of the electric drive’s installed power, and in simpler schemes with pulse-vector control.

Electromagnetic multipole moments of elementary spin-1/2, 1, and 3/2 particles

NASA Astrophysics Data System (ADS)

Delgado-Acosta, E. G.; Kirchbach, M.; Napsuciale, M.; Rodríguez, S.

2012-06-01

We study multipole decompositions of the electromagnetic currents of spin-1/2, 1, and 3/2 particles described in terms of representation-specific wave equations which are second order in the momenta and which emerge within the recently elaborated Poincaré covariant-projector method, where the respective Lagrangians explicitly depend on the Lorentz group generators of the representations of interest. The currents are then the ordinary linear Noether currents related to phase invariance, and present themselves always as two-terms motion-plus spin-magnetization currents. The spin-magnetization currents appear weighted by the gyromagnetic ratio g, a free parameter in the method which we fix either by unitarity of forward Compton scattering amplitudes in the ultraviolet for spin-1 and spin-3/2, or in the spin-1/2 case, by their asymptotic vanishing, thus ending up in all three cases with the universal g value of g=2. Within the method under discussion, we calculate the electric multipoles of the above spins for the spinor, the four-vector, and the four-vector-spinor representations, and find it favorable in some aspects, specifically in comparison with the conventional Proca and Rarita-Schwinger frameworks. We furthermore attend to the most general non-Lagrangian spin-3/2 currents, which are allowed by Lorentz invariance to be up to third order in the momenta and construct the linear-current equivalent of identical multipole moments of one of them. We conclude that nonlinear non-Lagrangian spin-3/2 currents are not necessarily more general and more advantageous than the linear spin-3/2 Lagrangian current emerging within the covariant-projector formalism. Finally, we test the representation dependence of the multipoles by placing spin-1 and spin-3/2 in the respective (1,0)⊕(0,1) and (3/2,0)⊕(0,3/2) single-spin representations. We observe representation independence of the charge monopoles and the magnetic dipoles, in contrast to the higher multipoles, which turn out to be representation-dependent. In particular, we find the bi-vector (1,0)⊕(0,1) to be characterized by an electric quadrupole moment of opposite sign to the one found in (1/2,1/2), and consequently to the W boson. This observation allows us to explain the positive electric quadrupole moment of the ρ meson extracted from recent analyses of the ρ meson electric form factor. Our finding points toward the possibility that the ρ-meson could transform as part of an antisymmetric tensor with an a1 mesonlike state as its representation companion, a possibility consistent with the empirically established ρ and a1 vector meson dominance of the hadronic vector and axial-vector currents.

Forward and Inverse Modeling of Self-potential. A Tomography of Groundwater Flow and Comparison Between Deterministic and Stochastic Inversion Methods

NASA Astrophysics Data System (ADS)

Quintero-Chavarria, E.; Ochoa Gutierrez, L. H.

2016-12-01

Applications of the Self-potential Method in the fields of Hydrogeology and Environmental Sciences have had significant developments during the last two decades with a strong use on groundwater flows identification. Although only few authors deal with the forward problem's solution -especially in geophysics literature- different inversion procedures are currently being developed but in most cases they are compared with unconventional groundwater velocity fields and restricted to structured meshes. This research solves the forward problem based on the finite element method using the St. Venant's Principle to transform a point dipole, which is the field generated by a single vector, into a distribution of electrical monopoles. Then, two simple aquifer models were generated with specific boundary conditions and head potentials, velocity fields and electric potentials in the medium were computed. With the model's surface electric potential, the inverse problem is solved to retrieve the source of electric potential (vector field associated to groundwater flow) using deterministic and stochastic approaches. The first approach was carried out by implementing a Tikhonov regularization with a stabilized operator adapted to the finite element mesh while for the second a hierarchical Bayesian model based on Markov chain Monte Carlo (McMC) and Markov Random Fields (MRF) was constructed. For all implemented methods, the result between the direct and inverse models was contrasted in two ways: 1) shape and distribution of the vector field, and 2) magnitude's histogram. Finally, it was concluded that inversion procedures are improved when the velocity field's behavior is considered, thus, the deterministic method is more suitable for unconfined aquifers than confined ones. McMC has restricted applications and requires a lot of information (particularly in potentials fields) while MRF has a remarkable response especially when dealing with confined aquifers.

Co-Investigator Proposal for Enstrophy - - Filamentation of Auroral Currents

NASA Technical Reports Server (NTRS)

Kintner, Paul M.

2000-01-01

Cornell University provided three instruments for the Enstrophy experiment: an electric field meter, a plasma wave receiver, and a magnetometer for measuring FAC. The electric field meter consisted of a 6 m Weitzmann boom system with analog signal processing and 12 bit ADC, which yielded one electric field component instantaneously and a two dimensional electric field every half spin. The plasma wave receiver used the same sensing system with the addition of pre-amplifiers in the spheres to sense plasma waves up to and including the electron Langmuir frequency. Signal processing employed a variety of continuous and snap shot techniques depending on the frequency range and band width. The science magnetometer provided by Cornell University was a Billingsly design fluxgate previously used on spacecraft missions but without radiation hardening. The magnetometer was mounted on a one meter, stiff aluminum "flop-down" boom. The Enstrophy payload was launched on february 11, 1999. Because of a design flaw in the event timers, the magnetometer boom was deployed before the payload despun. As a result the magnetometer separated mechanically from the boom but maintained electrical connection. This was confirmed by the calculation of the scalar magnetic field from all three vector components of the magnetic field. However, the individual vector values had no scientific value. The electric field and plasma wave instrumentation worked as designed. The data from these instruments was provided to the University of New Hampshire and to the Principal Investigator, as proposed.

A procedure for accurate calibration of the orientation of the three sensors in a vector magnetometer. [at the Goddard Space Flight Center

NASA Technical Reports Server (NTRS)

Mcpherron, R. L.

1977-01-01

Procedures are described for the calibration of a vector magnetometer of high absolute accuracy. It is assumed that the calibration will be performed in the magnetic test facility of Goddard Space Flight Center (GSFC). The first main section of the report describes the test equipment and facility calibrations required. The second presents procedures for calibrating individual sensors. The third discusses the calibration of the sensor assembly. In a final section recommendations are made to GSFC for modification of the test facility required to carry out the calibration procedures.

The Magsat precision vector magnetometer

NASA Technical Reports Server (NTRS)

Acuna, M. H.

1980-01-01

This paper examines the Magsat precision vector magnetometer which is designed to measure projections of the ambient field in three orthogonal directions. The system contains a highly stable and linear triaxial fluxgate magnetometer with a dynamic range of + or - 2000 nT (1 nT = 10 to the -9 weber per sq m). The magnetometer electronics, analog-to-digital converter, and digitally controlled current sources are implemented with redundant designs to avoid a loss of data in case of failures. Measurements are carried out with an accuracy of + or - 1 part in 64,000 in magnitude and 5 arcsec in orientation (1 arcsec = 0.00028 deg).

Real-Time Symbol Extraction From Grey-Level Images

NASA Astrophysics Data System (ADS)

Massen, R.; Simnacher, M.; Rosch, J.; Herre, E.; Wuhrer, H. W.

1988-04-01

A VME-bus image pipeline processor for extracting vectorized contours from grey-level images in real-time is presented. This 3 Giga operation per second processor uses large kernel convolvers and new non-linear neighbourhood processing algorithms to compute true 1-pixel wide and noise-free contours without thresholding even from grey-level images with quite varying edge sharpness. The local edge orientation is used as an additional cue to compute a list of vectors describing the closed and open contours in real-time and to dump a CAD-like symbolic image description into a symbol memory at pixel clock rate.

Comment on "An experimental study of symmetry lowering of analcime"

NASA Astrophysics Data System (ADS)

Nespolo, Massimo

2018-04-01

In a recent article (Phys Chem Minerals. https://doi.org/10.1007/s00269-017-0922-1, 2018), analcime hydrothermally synthesized from a gel and then reheated was reported to have undergone a loss of symmetry to Ibca. We show that the reheated samples, reported as different, are identical to each other and actually tetragonal. The fact that the tetragonal axis was oriented along the a or b vector in the two reheated samples instead of the c vector as in the conventional setting seems to have been the cause of the misinterpretation of the diffraction pattern.

Chemically modified graphene/polyimide composite films based on utilization of covalent bonding and oriented distribution.

PubMed

Huang, Ting; Lu, Renguo; Su, Chao; Wang, Hongna; Guo, Zheng; Liu, Pei; Huang, Zhongyuan; Chen, Haiming; Li, Tongsheng

2012-05-01

Herein, we have developed a rather simple composite fabrication approach to achieving molecular-level dispersion and planar orientation of chemically modified graphene (CMG) in the thermosetting polyimide (PI) matrix as well as realizing strong adhesion at the interfacial regions between reinforcing filler and matrix. The covalent adhesion of CMG to PI matrix and oriented distribution of CMG were carefully confirmed and analyzed by detailed investigations. Combination of covalent bonding and oriented distribution could enlarge the effectiveness of CMG in the matrix. Efficient stress transfer was found at the CMG/PI interfaces. Significant improvements in the mechanical performances, thermal stability, electrical conductivity, and hydrophobic behavior were achieved by addition of only a small amount of CMG. Furthermore, it is noteworthy that the hydrophilic-to-hydrophobic transition and the electrical percolation were observed at only 0.2 wt % CMG in this composite system. This facile methodology is believed to afford broad application potential in graphene-based polymer nanocomposites, especially other types of high-performance thermosetting systems.

Electrical characterization of vertically stacked p-FET SOI nanowires

NASA Astrophysics Data System (ADS)

Cardoso Paz, Bruna; Cassé, Mikaël; Barraud, Sylvain; Reimbold, Gilles; Vinet, Maud; Faynot, Olivier; Antonio Pavanello, Marcelo

2018-03-01

This work presents the performance and transport characteristics of vertically stacked p-type MOSFET SOI nanowires (NWs) with inner spacers and epitaxial growth of SiGe raised source/drain. The conventional procedure to extract the effective oxide thickness (EOT) and Shift and Ratio Method (S&R) have been adapted and validated through tridimensional numerical simulations. Electrical characterization is performed for NWs with [1 1 0]- and [1 0 0]-oriented channels, as a function of both fin width (WFIN) and channel length (L). Results show a good electrostatic control and reduced short channel effects (SCE) down to 15 nm gate length, for both orientations. Effective mobility is found around two times higher for [1 1 0]- in comparison to [1 0 0]-oriented NWs due to higher holes mobility contribution in (1 1 0) plan. Improvements obtained on ION/IOFF by reducing WFIN are mainly due to subthreshold slope decrease, once small and none mobility increase is obtained for [1 1 0]- and [1 0 0]-oriented NWs, respectively.

Optical switch based on the electrically controlled liquid crystal interface.

PubMed

Komar, Andrei A; Tolstik, Alexei L; Melnikova, Elena A; Muravsky, Alexander A

2015-06-01

The peculiarities of the linearly polarized light beam reflection at the interface within the bulk of a nematic liquid crystal (NLC) cell with different orientations of the director are analyzed. Two methods to create the interface are considered. Combination of the planar and homeotropic orientations of the NLC director is realized by means of a spatially structured electrode under the applied voltage. In-plane patterned azimuthal alignment of the NLC director is created by the patterned rubbing alignment technique. All possible orthogonal orientations of the LC director are considered; the configurations for realization of total internal reflection are determined. The revealed relationship between the propagation of optical beams in a liquid crystal material and polarization of laser radiation has enabled realization of the spatial separation for the orthogonally polarized light beams at the interface between two regions of NLC with different director orientations (domains). Owing to variations in the applied voltage and, hence, in the refractive index gradient, the light beam propagation directions may be controlled electrically.

Second harmonic generation in photonic crystal cavities in (111)-oriented GaAs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buckley, Sonia, E-mail: bucklesm@stanford.edu; Radulaski, Marina; Vučković, Jelena

2013-11-18

We demonstrate second harmonic generation at telecommunications wavelengths in photonic crystal cavities in (111)-oriented GaAs. We fabricate 30 photonic crystal structures in both (111)- and (100)-oriented GaAs and observe an increase in generated second harmonic power in the (111) orientation, with the mean power increased by a factor of 3, although there is a large scatter in the measured values. We discuss possible reasons for this increase, in particular, the reduced two photon absorption for transverse electric modes in (111) orientation, as well as a potential increase due to improved mode overlap.

Anisotropy of synthetic quartz electrical conductivity at high pressure and temperature

NASA Astrophysics Data System (ADS)

Wang, Duojun; Li, Heping; Yi, Li; Matsuzaki, Takuya; Yoshino, Takashi

2010-09-01

AC measurements of the electrical conductivity of synthetic quartz along various orientations were made between 0.1 and 1 MHz, at ˜855˜1601 K and at 1.0 GPa. In addition, the electrical conductivity of quartz along the c axis has been studied at 1.0-3.0 GPa. The impedance arcs representing bulk conductivity occur in the frequency range of 103-106 Hz, and the electrical responses of the interface between the sample and the electrode occur in the 0.1˜103 Hz range. The pressure has a weak effect on the electrical conductivity. The electrical conductivity experiences no abrupt change near the α - β phase transition point. The electrical conductivity of quartz is highly anisotropic; the electrical conductivity along the c axis is strongest and several orders of magnitude larger than in other directions. The activation enthalpies along various orientations are determined to be 0.6 and 1.2 eV orders of magnitude, respectively. The interpretation of the former is based on the contribution of alkali ions, while the latter effect is attributed to additional unassociated aluminum ions. Comparison of determined anisotropic conductivity of quartz determined with those from field geophysical models shows that the quartz may potentially provide explanations for the behavior of electrical conductivity of anisotropy in the crust that are inferred from the transverse magnetic mode.

Effect of oxygen concentration on fire growth of various types of cable bending in horizontal and vertical orientations

NASA Astrophysics Data System (ADS)

Pangaribuan, Adrianus; Dhiputra, I. M. K.; Nugroho, Yulianto S.

2017-03-01

Electrical cable is a whole of the material including metal (cooper) conductor and its insulation, when an electrical cable is flowed by electric current, based on its own capacity, the temperature of cable conductor increases gradually. If the current flows above the cable carrying capacity, then an extreme temperature rises are expected. When temperature increase, the electric current flow inside cable conductor will decrease gradually related to the resistance and could occur repeatedly in a period. Since electrical faults on electrical cable system are often suspected as the cause of fires, thus this research aims to investigate measures of preventing the fire to start by means of controlling oxygen concentration in a cable compartment. The experimental work was conducted in laboratory by using electrical power cable of 1.5 mm2 size. Two transparent chambers were applied for studying the effect of vertical and horizontal orientations on the cable temperature rise, under various oxygen concentration of the gas streams. In the present work, the electrical was maintained at a constant level during a typical test run. Parametric studies reported in the paper include the use of a bare and insulated cables as well as the bending shape of the cable lines of a straight cable, coiled cable and randomly bent cable which were loaded with the same electric load and oxygen concentration in the gas supply.

Fold-and-thrust belt curvature in the Fars region, eastern Zagros, achieved by variable thrust slip vectors and fault block rotations

NASA Astrophysics Data System (ADS)

Edey, Alex; Allen, Mark B.

2017-04-01

Many fold-and-thrust belts are curved in plan view, but the origins of this curvature are debated. Understanding which mechanism(s) is appropriate is important to constrain the behaviour of the lithosphere during compressional deformation. Here we analyse the active deformation of the Fars Arc region in the eastern part of the Zagros, Iran, including slip vectors of 92 earthquakes, published GPS and palaeomagnetism data, and the distributions of young and/or active folds. The fold-and-thrust belt in the Fars Arc shows pronounced curvature, convex southwards. Folds trends vary from NW-SE in the west to ENE-WSW in the east. The GPS-derived velocity field shows NNE to SSW convergence, towards the foreland on the Arabian Plate, without dispersion. Earthquake slip vectors are highly variable, spanning a range of azimuths from SW to SSE in an Arabian Plate reference frame. The full variation of azimuths occurs within small (10s of km) sub-regions, but this variation is superimposed on a radial pattern, whereby slip vectors tend to be parallel to the regional topographic gradient. Given the lack of variation in the GPS vectors, we conclude that the Fars Arc is not curved as a result of gravitational spreading over the adjacent foreland, but as a result of deformation being restricted at tectonic boundaries at the eastern and western margins of the Arc. Fault blocks and folds within the Fars Arc, each 20-40 km long, rotate about vertical axes to achieve the overall curvature, predominantly clockwise in the west and counter-clockwise in the east. Active folds of different orientations may intersect and produce dome-and-basin interference patterns, without the need for a series of separate deformation phases of different stress orientations. The Fars Arc clearly contrasts with the Himalayas, where both GPS and earthquake slip vectors display radial patterns towards the foreland, and gravitational spreading is a viable mechanism for producing fold-and-thrust belt curvature.

Sleeping Beauty-baculovirus hybrid vectors for long-term gene expression in the eye.

PubMed

Turunen, Tytteli Anni Kaarina; Laakkonen, Johanna Päivikki; Alasaarela, Laura; Airenne, Kari Juhani; Ylä-Herttuala, Seppo

2014-01-01

A baculovirus vector is capable of efficiently transducing many nondiving and diving cell types. However, the potential of baculovirus is restricted for many gene delivery applications as a result of the transient gene expression that it mediates. The plasmid-based Sleeping Beauty (SB) transposon system integrates transgenes into target cell genome efficiently with a genomic integration pattern that is generally considered safer than the integration of many other integrating vectors; yet efficient delivery of therapeutic genes into cells of target tissues in vivo is a major challenge for nonviral gene therapy. In the present study, SB was introduced into baculovirus to obtain novel hybrid vectors that would combine the best features of the two vector systems (i.e. effective gene delivery and efficient integration into the genome), thus circumventing the major limitations of these vectors. We constructed and optimized SB-baculovirus hybrid vectors that bear either SB100x transposase or SB transposon in the forward or reverse orientations with respect to the viral backbone The functionality of the novel hybrid vectors was investigated in cell cultures and in a proof-of-concept study in the mouse eye. The hybrid vectors showed high and sustained transgene expression that remained stable and demonstrated no signs of decline during the 2 months follow-up in vitro. These results were verified in the mouse eye where persistent transgene expression was detected two months after intravitreal injection. Our results confirm that (i) SB-baculovirus hybrid vectors mediate long-term gene expression in vitro and in vivo, and (ii) the hybrid vectors are potential new tools for the treatment of ocular diseases. Copyright © 2014 John Wiley & Sons, Ltd.

Reviving a neglected celestial underwater polarization compass for aquatic animals.

PubMed

Waterman, Talbot H

2006-02-01

Substantial in situ measurements on clear days in a variety of marine environments at depths in the water down to 200 m have demonstrated the ubiquitous daytime presence of sun-related e-vector (=plane of polarization) patterns. In most lines of sight the e-vectors tilt from horizontal towards the sun at angles equal to the apparent underwater refracted zenith angle of the sun. A maximum tilt-angle of approximately 48.5 degrees , is reached in horizontal lines of sight at 90 degrees to the sun's bearing (the plane of incidence). This tilt limit is set by Snell's window, when the sun is on the horizon. The biological literature since the 1980s has been pervaded with assumptions that daytime aquatic e-vectors are mainly horizontal. This review attempts to set the record straight concerning the potential use of underwater e-vectors as a visual compass and to reopen the field to productive research on aquatic animals' orientation and navigation.

Attosecond electronic recollision as field detector

NASA Astrophysics Data System (ADS)

Carpeggiani, P. A.; Reduzzi, M.; Comby, A.; Ahmadi, H.; Kühn, S.; Frassetto, F.; Poletto, L.; Hoff, D.; Ullrich, J.; Schröter, C. D.; Moshammer, R.; Paulus, G. G.; Sansone, G.

2018-05-01

We demonstrate the complete reconstruction of the electric field of visible–infrared pulses with energy as low as a few tens of nanojoules. The technique allows for the reconstruction of the instantaneous electric field vector direction and magnitude, thus giving access to the characterization of pulses with an arbitrary time-dependent polarization state. The technique combines extreme ultraviolet interferometry with the generation of isolated attosecond pulses.

Biodiversity Can Help Prevent Malaria Outbreaks in Tropical Forests

PubMed Central

Laporta, Gabriel Zorello; de Prado, Paulo Inácio Knegt Lopez; Kraenkel, Roberto André; Coutinho, Renato Mendes; Sallum, Maria Anice Mureb

2013-01-01

Background Plasmodium vivax is a widely distributed, neglected parasite that can cause malaria and death in tropical areas. It is associated with an estimated 80–300 million cases of malaria worldwide. Brazilian tropical rain forests encompass host- and vector-rich communities, in which two hypothetical mechanisms could play a role in the dynamics of malaria transmission. The first mechanism is the dilution effect caused by presence of wild warm-blooded animals, which can act as dead-end hosts to Plasmodium parasites. The second is diffuse mosquito vector competition, in which vector and non-vector mosquito species compete for blood feeding upon a defensive host. Considering that the World Health Organization Malaria Eradication Research Agenda calls for novel strategies to eliminate malaria transmission locally, we used mathematical modeling to assess those two mechanisms in a pristine tropical rain forest, where the primary vector is present but malaria is absent. Methodology/Principal Findings The Ross–Macdonald model and a biodiversity-oriented model were parameterized using newly collected data and data from the literature. The basic reproduction number () estimated employing Ross–Macdonald model indicated that malaria cases occur in the study location. However, no malaria cases have been reported since 1980. In contrast, the biodiversity-oriented model corroborated the absence of malaria transmission. In addition, the diffuse competition mechanism was negatively correlated with the risk of malaria transmission, which suggests a protective effect provided by the forest ecosystem. There is a non-linear, unimodal correlation between the mechanism of dead-end transmission of parasites and the risk of malaria transmission, suggesting a protective effect only under certain circumstances (e.g., a high abundance of wild warm-blooded animals). Conclusions/Significance To achieve biological conservation and to eliminate Plasmodium parasites in human populations, the World Health Organization Malaria Eradication Research Agenda should take biodiversity issues into consideration. PMID:23556023

Electric Field and Plasma Density Observations of Irregularities and Plasma Instabilities in the Low Latitude Ionosphere Gathered by the C/NOFS Satellite

NASA Technical Reports Server (NTRS)

Pfaff, Robert F.; Freudenreich, H.; Rowland, D.; Klenzing, J.; Liebrecht, C.

2012-01-01

The Vector Electric Field Investigation (VEFI) on the C/NOFS equatorial satellite provides a unique data set which includes detailed measurements of irregularities associated with the equatorial ionosphere and in particular with spread-F depletions. We present vector AC electric field observations gathered on C/NOFS that address a variety of key questions regarding how plasma irregularities, from meter to kilometer scales, are created and evolve. The talk focuses on occasions where the ionosphere F-peak has been elevated above the C/NOFS satellite perigee of 400 km as solar activity has increased. In particular, during the equinox periods of 2011, the satellite consistently journeyed below the F-peak whenever the orbit was in the region of the South Atlantic anomaly after sunset. During these passes, data from the electric field and plasma density probes on the satellite have revealed two types of instabilities which had not previously been observed in the C/NOFS data set: The first is evidence for 400-500km-scale bottomside "undulations" that appear in the density and electric field data. In one case, these large scale waves are associated with a strong shear in the zonal E x B flow, as evidenced by variations in the meridional (outward) electric fields observed above and below the F-peak. These undulations are devoid of smaller scale structures in the early evening, yet appear at later local times along the same orbit associated with fully-developed spread-F with smaller scale structures. This suggests that they may be precursor waves for spread-F, driven by a collisional shear instability, following ideas advanced previously by researchers using data from the Jicamarca radar. A second result is the appearance of km-scale irregularities that are a common feature in the electric field and plasma density data that also appear when the satellite is near or below the F-peak at night. The vector electric field instrument on C/NOFS clearly shows that the electric field component of these waves is strongest in the zonal direction. These waves are strongly correlated with simultaneous observations of plasma density oscillations and appear both with, and without, evidence of larger-scale spread-F depletions. These km-scale, quasi-coherent waves strongly resemble the bottomside, sinusoidal irregularities reported in the Atmosphere Explorer satellite data set by Valladares et al. and are believed to cause scintillations of VHF radiowaves. We interpret these new observations in terms of fundamental plasma instabilities associated with the unstable, nighttime equatorial ionosphere.

The past, present, and future of the U.S. electric power sector: Examining regulatory changes using multivariate time series approaches

NASA Astrophysics Data System (ADS)

Binder, Kyle Edwin

The U.S. energy sector has undergone continuous change in the regulatory, technological, and market environments. These developments show no signs of slowing. Accordingly, it is imperative that energy market regulators and participants develop a strong comprehension of market dynamics and the potential implications of their actions. This dissertation contributes to a better understanding of the past, present, and future of U.S. energy market dynamics and interactions with policy. Advancements in multivariate time series analysis are employed in three related studies of the electric power sector. Overall, results suggest that regulatory changes have had and will continue to have important implications for the electric power sector. The sector, however, has exhibited adaptability to past regulatory changes and is projected to remain resilient in the future. Tests for constancy of the long run parameters in a vector error correction model are applied to determine whether relationships among coal inventories in the electric power sector, input prices, output prices, and opportunity costs have remained constant over the past 38 years. Two periods of instability are found, the first following railroad deregulation in the U.S. and the second corresponding to a number of major regulatory changes in the electric power and natural gas sectors. Relationships among Renewable Energy Credit prices, electricity prices, and natural gas prices are estimated using a vector error correction model. Results suggest that Renewable Energy Credit prices do not completely behave as previously theorized in the literature. Potential reasons for the divergence between theory and empirical evidence are the relative immaturity of current markets and continuous institutional intervention. Potential impacts of future CO2 emissions reductions under the Clean Power Plan on economic and energy sector activity are estimated. Conditional forecasts based on an outlined path for CO2 emissions are developed from a factor-augmented vector autoregressive model for a large dataset. Unconditional and conditional forecasts are compared for U.S. industrial production, real personal income, and estimated factors. Results suggest that economic growth will be slower under the Clean Power Plan than it would otherwise; however, CO2 emissions reductions and economic growth can be achieved simultaneously.

Giant piezoelectric property of (110) oriented BaxSr1-xTiO3 films

NASA Astrophysics Data System (ADS)

Chen, Z. H.; Chen, Z.; Qiu, J. H.; Yuan, N. Y.; Ding, J. N.

2017-10-01

A phenomenological Landau-Devonshire theory is applied to investigate the phase diagrams and physical properties of (110) oriented BaxSr1-xTiO3 films. New ferroelectric phases, such as the tetragonal a1 phase and the orthorhombic a2 c phase, appear in the ;misfit strain-temperature; phase diagrams for (110) oriented films compared with that of (001) oriented films. Moreover, the orthorhombic a2 c phase, and the tetragonal c phase and the triclinic γ phase are stable at low temperature for x = 0.5 and x = 0.7 , respectively. The ferroelectric, dielectric, and piezoelectric properties strongly depend on the misfit strain and electric field. (110) oriented Ba0.7Sr0.3TiO3 film has the larger ferroelectric polarization and piezoelectric coefficient than that of Ba0.5Sr0.5TiO3 film. The giant piezoelectric coefficient of 340 pm / V is obtained at the electric field of 50 KV / cm in (110) oriented Ba0.7Sr0.3TiO3 film, which is comparable with the values of Pb (Zr1-xTix)O3 and (1 - x) Pb (Mg1/3Nb2/3)O3 -xPbTiO3 films. It makes (110) oriented BaxSr1-xTiO3 films suitable for applications in electromechanical devices.

Measurement of the orientation of buffer-gas-cooled, electrostatically-guided ammonia molecules

NASA Astrophysics Data System (ADS)

Steer, Edward W.; Petralia, Lorenzo S.; Western, Colin M.; Heazlewood, Brianna R.; Softley, Timothy P.

2017-02-01

The extent to which the spatial orientation of internally and translationally cold ammonia molecules can be controlled as molecules pass out of a quadrupole guide and through different electric field regions is examined. Ammonia molecules are collisionally cooled in a buffer gas cell, and are subsequently guided by a three-bend electrostatic quadrupole into a detection chamber. The orientation of ammonia molecules is probed using (2 + 1) resonance-enhanced multiphoton ionisation (REMPI), with the laser polarisation axis aligned both parallel and perpendicular to the time-of-flight axis. Even with the presence of a near-zero field region, the ammonia REMPI spectra indicate some retention of orientation. Monte Carlo simulations propagating the time-dependent Schrödinger equation in a full basis set including the hyperfine interaction enable the orientation of ammonia molecules to be calculated - with respect to both the local field direction and a space-fixed axis - as the molecules pass through different electric field regions. The simulations indicate that the orientation of ∼95% of ammonia molecules in JK =11 could be achieved with the application of a small bias voltage (17 V) to the mesh separating the quadrupole and detection regions. Following the recent combination of the buffer gas cell and quadrupole guide apparatus with a linear Paul ion trap, this result could enable one to examine the influence of molecular orientation on ion-molecule reaction dynamics and kinetics.

Reduction, analysis, and properties of electric current systems in solar active regions

NASA Technical Reports Server (NTRS)

Gary, G. Allen; Demoulin, Pascal

1995-01-01

The specific attraction and, in large part, the significance of solar magnetograms lie in the fact that they give the most important data on the electric currents and the nonpotentiality of active regions. Using the vector magnetograms from the Marshall Space Flight Center (MSFC), we employ a unique technique in the area of data analysis for resolving the 180 deg ambiguity in order to calculate the spatial structure of the vertical electric current density. The 180 deg ambiguity is resolved by applying concepts from the nonlinear multivariable optimization theory. The technique is shown to be of particular importance in very nonpotential active regions. The characterization of the vertical electric current density for a set of vector magnetograms using this method then gives the spatial scale, locations, and magnitude of these current systems. The method, which employs an intermediate parametric function which covers the magnetogram and which defines the local `preferred' direction, minimizes a specific functional of the observed transverse magnetic field. The specific functional that is successful is the integral of the square of the vertical current density. We find that the vertical electric current densities have common characteristics for the extended bipolar (beta) (gamma) (delta)-regions studied. The largest current systems have j(sub z)'s which maximizes around 30 mA/sq m and have a linear decreasing distribution to a diameter of 30 Mn.

Determination of Specific Losses in the Limbs of an Epstein Frame Using a Three Epstein Frame Methodology Applied to Grain Oriented Electrical Steels

PubMed Central

Parent, Guillaume; Penin, Rémi; Lecointe, Jean-Philippe; Brudny, Jean-François; Belgrand, Thierry

2016-01-01

An experimental method to characterize the magnetic properties of Grain Oriented Electrical Steel in the rolling direction is proposed in this paper. It relies on the use of three 25 cm Epstein frames combined to generate three test-frames of different lengths. This enables the identification of the effective specific losses of the electrical steel when magnetization is applied along the rolling direction. As a consequence, it evidences the deviation of the loss figures obtained using the standardised Epstein test. The difference in losses is explained by the fact that the described method gives “only” the losses attached to the straight parts. The concept of the magnetic path length as defined by the standard is discussed. PMID:27271637

Determination of Specific Losses in the Limbs of an Epstein Frame Using a Three Epstein Frame Methodology Applied to Grain Oriented Electrical Steels.

PubMed

Parent, Guillaume; Penin, Rémi; Lecointe, Jean-Philippe; Brudny, Jean-François; Belgrand, Thierry

2016-06-04

An experimental method to characterize the magnetic properties of Grain Oriented Electrical Steel in the rolling direction is proposed in this paper. It relies on the use of three 25 cm Epstein frames combined to generate three test-frames of different lengths. This enables the identification of the effective specific losses of the electrical steel when magnetization is applied along the rolling direction. As a consequence, it evidences the deviation of the loss figures obtained using the standardised Epstein test. The difference in losses is explained by the fact that the described method gives "only" the losses attached to the straight parts. The concept of the magnetic path length as defined by the standard is discussed.

Organic magnetic field sensor

DOEpatents

McCamey, Dane; Boehme, Christoph

2017-01-24

An organic, spin-dependent magnetic field sensor (10) includes an active stack (12) having an organic material with a spin-dependence. The sensor (10) also includes a back electrical contact (14) electrically coupled to a back of the active stack (12) and a front electrical contact (16) electrically coupled to a front of the active stack (12). A magnetic field generator (18) is oriented so as to provide an oscillating magnetic field which penetrates the active stack (12).

Short-Circuit Fault Detection and Classification Using Empirical Wavelet Transform and Local Energy for Electric Transmission Line.

PubMed

Huang, Nantian; Qi, Jiajin; Li, Fuqing; Yang, Dongfeng; Cai, Guowei; Huang, Guilin; Zheng, Jian; Li, Zhenxin

2017-09-16

In order to improve the classification accuracy of recognizing short-circuit faults in electric transmission lines, a novel detection and diagnosis method based on empirical wavelet transform (EWT) and local energy (LE) is proposed. First, EWT is used to deal with the original short-circuit fault signals from photoelectric voltage transformers, before the amplitude modulated-frequency modulated (AM-FM) mode with a compactly supported Fourier spectrum is extracted. Subsequently, the fault occurrence time is detected according to the modulus maxima of intrinsic mode function (IMF₂) from three-phase voltage signals processed by EWT. After this process, the feature vectors are constructed by calculating the LE of the fundamental frequency based on the three-phase voltage signals of one period after the fault occurred. Finally, the classifier based on support vector machine (SVM) which was constructed with the LE feature vectors is used to classify 10 types of short-circuit fault signals. Compared with complementary ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and improved CEEMDAN methods, the new method using EWT has a better ability to present the frequency in time. The difference in the characteristics of the energy distribution in the time domain between different types of short-circuit faults can be presented by the feature vectors of LE. Together, simulation and real signals experiment demonstrate the validity and effectiveness of the new approach.

Short-Circuit Fault Detection and Classification Using Empirical Wavelet Transform and Local Energy for Electric Transmission Line

PubMed Central

Huang, Nantian; Qi, Jiajin; Li, Fuqing; Yang, Dongfeng; Cai, Guowei; Huang, Guilin; Zheng, Jian; Li, Zhenxin

2017-01-01

In order to improve the classification accuracy of recognizing short-circuit faults in electric transmission lines, a novel detection and diagnosis method based on empirical wavelet transform (EWT) and local energy (LE) is proposed. First, EWT is used to deal with the original short-circuit fault signals from photoelectric voltage transformers, before the amplitude modulated-frequency modulated (AM-FM) mode with a compactly supported Fourier spectrum is extracted. Subsequently, the fault occurrence time is detected according to the modulus maxima of intrinsic mode function (IMF2) from three-phase voltage signals processed by EWT. After this process, the feature vectors are constructed by calculating the LE of the fundamental frequency based on the three-phase voltage signals of one period after the fault occurred. Finally, the classifier based on support vector machine (SVM) which was constructed with the LE feature vectors is used to classify 10 types of short-circuit fault signals. Compared with complementary ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and improved CEEMDAN methods, the new method using EWT has a better ability to present the frequency in time. The difference in the characteristics of the energy distribution in the time domain between different types of short-circuit faults can be presented by the feature vectors of LE. Together, simulation and real signals experiment demonstrate the validity and effectiveness of the new approach. PMID:28926953

Research on Extrusion of Rubber Composites Reinforced by Short Fibers Orientation Based on FEA

NASA Astrophysics Data System (ADS)

Zhang, Dewei; Wang, Chuansheng; Shen, Bo; Li, Shaoming; Bian, Huiguang

2018-06-01

In recent years, rubber composites reinforced by short fibers has been researched deeply, because of its good performances such as higher wear resistance, higher cut resistance and so on. Some research results indicated that if short fibers get orientation in rubber composites, the performances of rubber products could be promoted greatly. But how to make short fibers get orientation in rubber matrix during extrusion is still a real problem. And there are many parameters affect the short fibers orientation. So, in this paper, the effects of die structure including expansion-die and dam-expansion-die on extrusion flow field of short fiber and rubber composite material during extrusion process has been researched by Polyflow. And the FEA results about the pressure field, velocity field and the velocity vector of the rubber composites flow field indicate that, comparing with expansion-die and the dam-expansion-die, the latter one is better for the extrusion process of rubber composites and making short fibers get radial orientation in rubber matrix.

CuInS2 Films Deposited by Aerosol-Assisted Chemical Vapor Deposition Using Ternary Single-Source Precursors

NASA Technical Reports Server (NTRS)

Jin, Michael; Banger, Kal; Harris, Jerry; Hepp, Aloysius

2003-01-01

Polycrystalline CuInS2 films were deposited by aerosol-assisted chemical vapor deposition using both solid and liquid ternary single-source precursors (SSPs) which were prepared in-house. Films with either (112) or (204/220) preferred orientation, had a chalcopyrite structure, and (112)-oriented films contained more copper than (204/220)-oriented films. The preferred orientation of the film is likely related to the decomposition and reaction kinetics associated with the molecular structure of the precursors at the substrate. Interestingly, the (204/220)-oriented films were always In-rich and were accompanied by a secondary phase. From the results of post-growth annealing, etching experiments, and Raman spectroscopic data, the secondary phase was identified as an In-rich compound. On the contrary, (112)-oriented films were always obtained with a minimal amount of the secondary phase, and had a maximum grain size of about 0.5 micron. Electrical and optical properties of all the films grown were characterized. They all showed p-type conduction with an electrical resistivity between 0.1 and 30 Omega-cm, and an optical band gap of approximately 1.46 eV +/- 0.02, as deposited. The material properties of deposited films revealed this methodology of using SSPs for fabricating chalcopyrite-based solar cells to be highly promising.

Polarization switching behavior of one-axis-oriented lead zirconate titanate films fabricated on metal oxide nanosheet layer

NASA Astrophysics Data System (ADS)

Uchida, Hiroshi; Ichinose, Daichi; Shiraishi, Takahisa; Shima, Hiromi; Kiguchi, Takanori; Akama, Akihiko; Nishida, Ken; Konno, Toyohiko J.; Funakubo, Hiroshi

2017-10-01

For the application of electronic devices using ferroelectric/piezoelectric components, one-axis-oriented tetragonal Pb(Zr0.40Ti0.60)O3 (PZT) films with thicknesses of up to 1 µm were fabricated with the aid of a Ca2Nb3O10 nanosheet (ns-CN) template for preferential crystal growth for evaluating their polarization switching behavior. The ns-CN template was supported on ubiquitous silicon (Si) wafer by a simple dip coating technique, followed by the repetitive chemical solution deposition (CSD) of PZT films. The PZT films were grown successfully with preferential crystal orientation of PZT(100) up to the thickness of 1020 nm. The (100)-oriented PZT film with ∼1 µm thickness exhibited unique polarization behavior of ferroelectric polarization, i.e., a marked increase in remanent polarization (P r) up to approximately 40 µC/cm2 induced by domain switching under high electric field, whereas the film with a lower thickness showed only a lower P r of approximately 11 µC/cm2 even under a high electric field. The ferroelectric property of the (100)-oriented PZT film after domain switching on ns-CN/Pt/Si can be comparable to those of (001)/(100)-oriented epitaxial PZT films.

Irradiation, microwave and alternative energy-based treatments for low water activity foods

USDA-ARS?s Scientific Manuscript database

There is an increasing recognition of low water activity foods as vectors for human pathogens. Partially or fully dried agricultural commodities, along with modern formulated dried food products, are complex, and designed to meet a variety of nutritional, sensory, and market-oriented goal. This comp...

A phagostimulant blend for the Asian citrus psyllid

USDA-ARS?s Scientific Manuscript database

Chemical cues that condition orientation by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), are of great interest because it is the primary vector of the causal pathogen of citrus greening disease. Previous work in our lab identified a blend of formic and acetic acids as s...

Multiple chemosensory targets for discovery of novel chemicals for disruption of mosquito behavior

USDA-ARS?s Scientific Manuscript database

The yellow-fever mosquito Aedes aegypti is an important vector of diseases including dengue fever, yellow fever, chikungunya and West Nile virus. Olfactory and gustatory signals play important roles in the orientation of female mosquitoes to vertebrate hosts and initiation of blood feeding. Using re...

Phagostimulants for the Asian citrus psyllid also elicit volatile release from citrus leaves

USDA-ARS?s Scientific Manuscript database

Chemical cues that elicit orientation by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), are of great interest because it is the primary vector of the causal pathogen of citrus greening disease. We identified an optimal blend ratio of formic and acetic acids that stimulate...

The Musical Taste of Young People

ERIC Educational Resources Information Center

Mozgot, V. G.

2014-01-01

Data from a longitudinal survey of the musical tastes of young people distinguish five basic vectors of its development: an orientation toward the Western paradigm; young people's unlimited amount of time spent in the consumption of music; the indiscriminate nature of their music interests; the influence that a person's membership in a particular…

User's guide to Model Viewer, a program for three-dimensional visualization of ground-water model results

USGS Publications Warehouse

Hsieh, Paul A.; Winston, Richard B.

2002-01-01

Model Viewer is a computer program that displays the results of three-dimensional groundwater models. Scalar data (such as hydraulic head or solute concentration) may be displayed as a solid or a set of isosurfaces, using a red-to-blue color spectrum to represent a range of scalar values. Vector data (such as velocity or specific discharge) are represented by lines oriented to the vector direction and scaled to the vector magnitude. Model Viewer can also display pathlines, cells or nodes that represent model features such as streams and wells, and auxiliary graphic objects such as grid lines and coordinate axes. Users may crop the model grid in different orientations to examine the interior structure of the data. For transient simulations, Model Viewer can animate the time evolution of the simulated quantities. The current version (1.0) of Model Viewer runs on Microsoft Windows 95, 98, NT and 2000 operating systems, and supports the following models: MODFLOW-2000, MODFLOW-2000 with the Ground-Water Transport Process, MODFLOW-96, MOC3D (Version 3.5), MODPATH, MT3DMS, and SUTRA (Version 2D3D.1). Model Viewer is designed to directly read input and output files from these models, thus minimizing the need for additional postprocessing. This report provides an overview of Model Viewer. Complete instructions on how to use the software are provided in the on-line help pages.

Thin film with oriented cracks on a flexible substrate

DOEpatents

Feng, Bao; McGilvray, Andrew; Shi, Bo

2010-07-27

A thermoelectric film is disclosed. The thermoelectric film includes a substrate that is substantially electrically non-conductive and flexible and a thermoelectric material that is deposited on at least one surface of the substrate. The thermoelectric film also includes multiple cracks oriented in a predetermined direction.

The U.S. and Japanese amorphous silicon technology programs A comparison

NASA Technical Reports Server (NTRS)

Shimada, K.

1984-01-01

The U.S. Department of Energy/Solar Energy Research Institute Amorphous Silicon (a-Si) Solar Cell Program performs R&D on thin-film hydrogenated amorphous silicon for eventual development of stable amorphous silicon cells with 12 percent efficiency by 1988. The Amorphous Silicon Solar Cell Program in Japan is sponsored by the Sunshine Project to develop an alternate energy technology. While the objectives of both programs are to eventually develop a-Si photovoltaic modules and arrays that would produce electricity to compete with utility electricity cost, the U.S. program approach is research oriented and the Japanese is development oriented.

Auto Body Welding 2 (Course Outline), Automotive Body Repair and Refinishing 1: 9033.04.

ERIC Educational Resources Information Center

Dade County Public Schools, Miami, FL.

The 90-hour course is a foundation quinmester course in welding for the auto body repairman. The outline consists of seven blocks of instruction (orientation, 6 hours; auto body oxyacetylene welding, 10 hours; electric arc welding equipment, 6 hours; auto body electric arc welding, 8 hours; position welding, 40 hours; electric spot welders, 16…

Orientation diffusions.

PubMed

Perona, P

1998-01-01

Diffusions are useful for image processing and computer vision because they provide a convenient way of smoothing noisy data, analyzing images at multiple scales, and enhancing discontinuities. A number of diffusions of image brightness have been defined and studied so far; they may be applied to scalar and vector-valued quantities that are naturally associated with intervals of either the real line, or other flat manifolds. Some quantities of interest in computer vision, and other areas of engineering that deal with images, are defined on curved manifolds;typical examples are orientation and hue that are defined on the circle. Generalizing brightness diffusions to orientation is not straightforward, especially in the case where a discrete implementation is sought. An example of what may go wrong is presented.A method is proposed to define diffusions of orientation-like quantities. First a definition in the continuum is discussed, then a discrete orientation diffusion is proposed. The behavior of such diffusions is explored both analytically and experimentally. It is shown how such orientation diffusions contain a nonlinearity that is reminiscent of edge-process and anisotropic diffusion. A number of open questions are proposed at the end.

The need for plant electro-physiology

NASA Astrophysics Data System (ADS)

Gorgolewski, S.

The already experimentaly evidenced existance of electrotropism for some plant species permits me to propose to extend these studies. Electrotropism is not well defined in plant physiology handbooks. There is a confusion of current and electric field which leads to communication problems between biologists and physicists. The electric field E, is measured in units of volts/metre=newtons/coulomb. We do not attach any wires to the plant leaves but subject them to the electric field. The plant distords the electrical field lines which in turn modify the shape of the plant. It has been verified in fitotron experiments that the direction and strength of the E vector relative to the gravitational force has different effects on plant growth. The natural fair weather global value of E is close to 130 V/m with positive charges in the air and negative on the ground. The most important results are: fields of (1.6 kV/m) enhance plant growth. Reversed fields overwhelm the gravitational field and plants grow towards the grownd. Horizontal E also enhances the plant growth in the horizontal direction ignoring the gravity. It shows that we can restore the directional orientation for plants in the absence of gravity by means of electrotropism. This is an important result for the plant growth in micro-gravity, basic advantage for long duration space fligths for raising edible crops for the vegetarian crew. It has the advantage of selecting in laboratory environment the plants which are suitable for space applications. The use of electic fields in ground based and space plant cultivation opens up important applications based on these novel trends also in modern greenhouses including the Biosphere 2. In addition to the fitotron experiments we have also studied plant growth in natural and modified natural electrical field environment. Two pioneering papers describing the above mentioned results and their possible ground based and space applications are cited as well as several references to biology and physics books. The presentation shall be richly illustrated with colour digital pictures of experimental and natural examples of the effects of electrical fields on plant growth shape and rate. Reference is also made to the already performed space experiments of plant cultivation in microgravity, and it is shown that the plants used were not electrotropic and these results thus do not contradict our fitotron and natural habitats observations.

Pretransitional phenomena and pinning in liquid-crystalline blue phases

NASA Astrophysics Data System (ADS)

Demikhov, E.; Stegemeyer, H.; Tsukruk, V.

1992-10-01

Blue phases (BP's) in liquid-crystalline systems of high chirality exhibiting a short cholesteric temperature interval are investigated. In a BP I supercooled with respect to the cholesteric phase, the orientation of the cubic lattice with the (1,1,0) wave vector perpendicular to the substrate is spontaneously turned to a [200] orientation within small areas of several tenths of micrometers in diameter. A pinning of BP I lattice temperature waves is observed on the [200] orientational inhomogeneities. The pinning effect explains the observed saturation of the BP I lattice constant on decreasing temperature and its dependence on the cooling rate observed in supercooled region. A different type of cubic blue phase, BP S (``S'' represents supercooled), is observed transforming reversibly from the supercooled BP I but metastable with respect to the cholesteric phase. The BP S has two scales of order: a long-range orientational blue-phase-like order and a short-range positional smecticlike order.

Crack orientation and depth estimation in a low-pressure turbine disc using a phased array ultrasonic transducer and an artificial neural network.

PubMed

Yang, Xiaoxia; Chen, Shili; Jin, Shijiu; Chang, Wenshuang

2013-09-13

Stress corrosion cracks (SCC) in low-pressure steam turbine discs are serious hidden dangers to production safety in the power plants, and knowing the orientation and depth of the initial cracks is essential for the evaluation of the crack growth rate, propagation direction and working life of the turbine disc. In this paper, a method based on phased array ultrasonic transducer and artificial neural network (ANN), is proposed to estimate both the depth and orientation of initial cracks in the turbine discs. Echo signals from cracks with different depths and orientations were collected by a phased array ultrasonic transducer, and the feature vectors were extracted by wavelet packet, fractal technology and peak amplitude methods. The radial basis function (RBF) neural network was investigated and used in this application. The final results demonstrated that the method presented was efficient in crack estimation tasks.

Crack Orientation and Depth Estimation in a Low-Pressure Turbine Disc Using a Phased Array Ultrasonic Transducer and an Artificial Neural Network

PubMed Central

Yang, Xiaoxia; Chen, Shili; Jin, Shijiu; Chang, Wenshuang

2013-01-01

Stress corrosion cracks (SCC) in low-pressure steam turbine discs are serious hidden dangers to production safety in the power plants, and knowing the orientation and depth of the initial cracks is essential for the evaluation of the crack growth rate, propagation direction and working life of the turbine disc. In this paper, a method based on phased array ultrasonic transducer and artificial neural network (ANN), is proposed to estimate both the depth and orientation of initial cracks in the turbine discs. Echo signals from cracks with different depths and orientations were collected by a phased array ultrasonic transducer, and the feature vectors were extracted by wavelet packet, fractal technology and peak amplitude methods. The radial basis function (RBF) neural network was investigated and used in this application. The final results demonstrated that the method presented was efficient in crack estimation tasks. PMID:24064602

Giant reversible anisotropy changes at room temperature in a (La,Sr)MnO3/Pb(Mg,Nb,Ti)O3 magneto-electric heterostructure.

PubMed

Chopdekar, Rajesh Vilas; Buzzi, Michele; Jenkins, Catherine; Arenholz, Elke; Nolting, Frithjof; Takamura, Yayoi

2016-06-08

In a model artificial multiferroic system consisting of a (011)-oriented ferroelectric Pb(Mg,Nb,Ti)O3 substrate intimately coupled to an epitaxial ferromagnetic (La,Sr)MnO3 film, electric field pulse sequences of less than 6 kV/cm induce large, reversible, and bistable remanent strains. The magnetic anisotropy symmetry reversibly switches from a highly anisotropic two-fold state to a more isotropic one, with concomitant changes in resistivity. Anisotropy changes at the scale of a single ferromagnetic domain were measured using X-ray microscopy, with electric-field dependent magnetic domain reversal showing that the energy barrier for magnetization reversal is drastically lowered. Free energy calculations confirm this barrier lowering by up to 70% due to the anisotropic strain changes generated by the substrate. Thus, we demonstrate that an electric field pulse can be used to 'set' and 'reset' the magnetic anisotropy orientation and resistive state in the film, as well as to lower the magnetization reversal barrier, showing a promising route towards electric-field manipulation of multifunctional nanostructures at room temperature.

Electric field control of magnetic states in isolated and dipole-coupled FeGa nanomagnets delineated on a PMN-PT substrate.

PubMed

Ahmad, Hasnain; Atulasimha, Jayasimha; Bandyopadhyay, Supriyo

2015-10-09

We report observation of a 'non-volatile' converse magneto-electric effect in elliptical FeGa nanomagnets delineated on a piezoelectric PMN-PT substrate. The nanomagnets are first magnetized with a magnetic field directed along their nominal major axes. Subsequent application of a strong electric field across the piezoelectric substrate generates strain in the substrate, which is partially transferred to the nanomagnets and rotates the magnetizations of some of them away from their initial orientations. The rotated magnetizations remain in their new orientations after the field is removed, resulting in 'non-volatility'. In isolated nanomagnets, the magnetization rotates by <90° upon application of the electric field, but in a dipole-coupled pair consisting of one 'hard' and one 'soft' nanomagnet, which are both initially magnetized in the same direction by the magnetic field, the soft nanomagnet's magnetization rotates by [Formula: see text] upon application of the electric field because of the dipole influence of the hard nanomagnet. This effect can be utilized for a nanomagnetic NOT logic gate.

Different Relative Orientation of Static and Alternative Magnetic Fields and Cress Roots Direction of Growth Changes Their Gravitropic Reaction

NASA Astrophysics Data System (ADS)

Sheykina, Nadiia; Bogatina, Nina

The following variants of roots location relatively to static and alternative components of magnetic field were studied. At first variant the static magnetic field was directed parallel to the gravitation vector, the alternative magnetic field was directed perpendicular to static one; roots were directed perpendicular to both two fields’ components and gravitation vector. At the variant the negative gravitropysm for cress roots was observed. At second variant the static magnetic field was directed parallel to the gravitation vector, the alternative magnetic field was directed perpendicular to static one; roots were directed parallel to alternative magnetic field. At third variant the alternative magnetic field was directed parallel to the gravitation vector, the static magnetic field was directed perpendicular to the gravitation vector, roots were directed perpendicular to both two fields components and gravitation vector; At forth variant the alternative magnetic field was directed parallel to the gravitation vector, the static magnetic field was directed perpendicular to the gravitation vector, roots were directed parallel to static magnetic field. In all cases studied the alternative magnetic field frequency was equal to Ca ions cyclotron frequency. In 2, 3 and 4 variants gravitropism was positive. But the gravitropic reaction speeds were different. In second and forth variants the gravitropic reaction speed in error limits coincided with the gravitropic reaction speed under Earth’s conditions. At third variant the gravitropic reaction speed was slowed essentially.

Electrically detected crystal orientation dependent spin-Rabi beat oscillation of c-Si(111)/SiO2 interface states

NASA Astrophysics Data System (ADS)

Paik, Seoyoung; Lee, Sang-Yun; McCamey, Dane R.; Boehme, Christoph

2011-12-01

Electrically detected spin-Rabi beat oscillation of pairs of paramagnetic near interface states at the phosphorous doped (1016 cm-3) Si(111)/SiO2 interface is reported. Due to the g-factor anisotropy of the Pb center (a silicon surface dangling bond), one can tune intrapair Larmor frequency differences (Larmor separations) by orientation of the crystal with regard to an external magnetic field. Since Larmor separation governs the number of beating spin pairs, crystal orientation can control the beat current. This is used to identify spin states that are paired by mutual electronic transitions. The experiments confirm the presence of the previously reported 31P-Pb transition and provide direct experimental evidence of the previously hypothesized Pb-E' center (a near interface SiO2 bulk state) transition.

Conductive layer for biaxially oriented semiconductor film growth

DOEpatents

Findikoglu, Alp T.; Matias, Vladimir

2007-10-30

A conductive layer for biaxially oriented semiconductor film growth and a thin film semiconductor structure such as, for example, a photodetector, a photovoltaic cell, or a light emitting diode (LED) that includes a crystallographically oriented semiconducting film disposed on the conductive layer. The thin film semiconductor structure includes: a substrate; a first electrode deposited on the substrate; and a semiconducting layer epitaxially deposited on the first electrode. The first electrode includes a template layer deposited on the substrate and a buffer layer epitaxially deposited on the template layer. The template layer includes a first metal nitride that is electrically conductive and has a rock salt crystal structure, and the buffer layer includes a second metal nitride that is electrically conductive. The semiconducting layer is epitaxially deposited on the buffer layer. A method of making such a thin film semiconductor structure is also described.

(111)-oriented Pb(Zr ,Ti)O3 films deposited on SrRuO3/Pt electrodes: Reproducible preparation by metal organic chemical vapor deposition, top electrode influence, and reliability

NASA Astrophysics Data System (ADS)

Menou, Nicolas; Funakubo, Hiroshi

2007-12-01

(111)-textured Pb(Zr0.4Ti0.6)O3 films (thickness of ˜120nm) were deposited on (111)-oriented SrRuO3 bottom electrodes by pulse metal organic chemical vapor deposition (MOCVD). PZT single phase was evidenced over a large range of Pb precursor input rate into the MOCVD chamber. In this process window, the good control of the (111) texture of PZT films was confirmed. It is shown that the control of both the composition and orientation of PZT films leads to reproducible electric properties (Pr, Vc, resistance to fatigue) across the process window. Furthermore, the impact of the top electrode chemical nature, elaboration process, and annealing process upon the electric properties was studied systematically.

Electric fields in the plasma sheet and plasma sheet boundary layer

NASA Technical Reports Server (NTRS)

Pedersen, A.; Cattell, C. A.; Faelthammar, C. G.; Knott, K.; Lindqvist, P. A.; Manka, R. H.; Mozer, F. S.

1984-01-01

Data from the spherical double probe electric-field experiment on ISEE-1 were used to study plasmasheet/lobe boundary crossings during substorms, identified by plasma measurements and by using the electric field probes as a reference for measurements of the spacecraft potential. There are strong electric fields, with a dominant dawn-to-dusk component, throughout the boundary layer outside the plasmasheet for contracting and expanding motions of the plasmasheet and for different magnetic field directions. Characteristic amplitudes and durations are 5 to 10 mV/m and 5 to 15 min. The corresponding E x B vectors are always towards the plasmasheet.

A Heuristic Potential Theory of Electric and Magnetic Monopoles without Strings.

ERIC Educational Resources Information Center

Barker, William A.; Graziani, Frank

1978-01-01

Shows how Maxwell's equations can be obtained by starting with a relatively simple pseudoscalar and scalar potential employing only the Lorentz transformation for a four vector (or pseudovector). (GA)

Black holes with halos

NASA Astrophysics Data System (ADS)

Monten, Ruben; Toldo, Chiara

2018-02-01

We present new AdS4 black hole solutions in N =2 gauged supergravity coupled to vector and hypermultiplets. We focus on a particular consistent truncation of M-theory on the homogeneous Sasaki–Einstein seven-manifold M 111, characterized by the presence of one Betti vector multiplet. We numerically construct static and spherically symmetric black holes with electric and magnetic charges, corresponding to M2 and M5 branes wrapping non-contractible cycles of the internal manifold. The novel feature characterizing these nonzero temperature configurations is the presence of a massive vector field halo. Moreover, we verify the first law of black hole mechanics and we study the thermodynamics in the canonical ensemble. We analyze the behavior of the massive vector field condensate across the small-large black hole phase transition and we interpret the process in the dual field theory.

Introducing the Filtered Park's and Filtered Extended Park's Vector Approach to detect broken rotor bars in induction motors independently from the rotor slots number

NASA Astrophysics Data System (ADS)

Gyftakis, Konstantinos N.; Marques Cardoso, Antonio J.; Antonino-Daviu, Jose A.

2017-09-01

The Park's Vector Approach (PVA), together with its variations, has been one of the most widespread diagnostic methods for electrical machines and drives. Regarding the broken rotor bars fault diagnosis in induction motors, the common practice is to rely on the width increase of the Park's Vector (PV) ring and then apply some more sophisticated signal processing methods. It is shown in this paper that this method can be unreliable and is strongly dependent on the magnetic poles and rotor slot numbers. To overcome this constraint, the novel Filtered Park's/Extended Park's Vector Approach (FPVA/FEPVA) is introduced. The investigation is carried out with FEM simulations and experimental testing. The results prove to satisfyingly coincide, whereas the proposed advanced FPVA method is desirably reliable.