WorldWideScience

Sample records for shaped field mwmtm-arrays

  1. Electric Field Activated Shape Memory Polymer Composite

    Science.gov (United States)

    Kang, Jin Ho (Inventor); Siochi, Emilie J. (Inventor); Penner, Ronald K. (Inventor); Turner, Travis L. (Inventor)

    2017-01-01

    Provided is an electrically activated shape memory polymer composite capable of thermal shape reformation using electric power to heat the composite through its matrix glass transition temperature. The composite includes an adaptable polymer matrix component using a diglycidyl ether resin, at least one substantially well-dispersed conductive or magnetic nano-filler component, and at least one elastic, laminated layer. Also provided are methods of preparing the composite and methods of activating the composite. A shape reformation of the composite is triggered by applying an electric field at DC and/or at a frequency above about 1.mu.Hz for a sufficient time.

  2. Cylindrical-shaped nanotube field effect transistor

    KAUST Repository

    Hussain, Muhammad Mustafa

    2015-12-29

    A cylindrical-shaped nanotube FET may be manufactured on silicon (Si) substrates as a ring etched into a gate stack and filled with semiconductor material. An inner gate electrode couples to a region of the gate stack inside the inner circumference of the ring. An outer gate electrode couples to a region of the gate stack outside the outer circumference of the ring. The multi-gate cylindrical-shaped nanotube FET operates in volume inversion for ring widths below 15 nanometers. The cylindrical-shaped nanotube FET demonstrates better short channel effect (SCE) mitigation and higher performance (I.sub.on/I.sub.off) than conventional transistor devices. The cylindrical-shaped nanotube FET may also be manufactured with higher yields and cheaper costs than conventional transistors.

  3. AC Electric Field Activated Shape Memory Polymer Composite

    Science.gov (United States)

    Kang, Jin Ho; Siochi, Emilie J.; Penner, Ronald K.; Turner, Travis L.

    2011-01-01

    Shape memory materials have drawn interest for applications like intelligent medical devices, deployable space structures and morphing structures. Compared to other shape memory materials like shape memory alloys (SMAs) or shape memory ceramics (SMCs), shape memory polymers (SMPs) have high elastic deformation that is amenable to tailored of mechanical properties, have lower density, and are easily processed. However, SMPs have low recovery stress and long response times. A new shape memory thermosetting polymer nanocomposite (LaRC-SMPC) was synthesized with conductive fillers to enhance its thermo-mechanical characteristics. A new composition of shape memory thermosetting polymer nanocomposite (LaRC-SMPC) was synthesized with conductive functionalized graphene sheets (FGS) to enhance its thermo-mechanical characteristics. The elastic modulus of LaRC-SMPC is approximately 2.7 GPa at room temperature and 4.3 MPa above its glass transition temperature. Conductive FGSs-doped LaRC-SMPC exhibited higher conductivity compared to pristine LaRC SMP. Applying an electric field at between 0.1 Hz and 1 kHz induced faster heating to activate the LaRC-SMPC s shape memory effect relative to applying DC electric field or AC electric field at frequencies exceeding1 kHz.

  4. Shape modelling using Markov random field restoration of point correspondences.

    Science.gov (United States)

    Paulsen, Rasmus R; Hilger, Klaus B

    2003-07-01

    A method for building statistical point distribution models is proposed. The novelty in this paper is the adaption of Markov random field regularization of the correspondence field over the set of shapes. The new approach leads to a generative model that produces highly homogeneous polygonized shapes and improves the capability of reconstruction of the training data. Furthermore, the method leads to an overall reduction in the total variance of the point distribution model. Thus, it finds correspondence between semi-landmarks that are highly correlated in the shape tangent space. The method is demonstrated on a set of human ear canals extracted from 3D-laser scans.

  5. Shape Modelling Using Markov Random Field Restoration of Point Correspondences

    DEFF Research Database (Denmark)

    Paulsen, Rasmus Reinhold; Hilger, Klaus Baggesen

    2003-01-01

    A method for building statistical point distribution models is proposed. The novelty in this paper is the adaption of Markov random field regularization of the correspondence field over the set of shapes. The new approach leads to a generative model that produces highly homogeneous polygonized...... shapes and improves the capability of reconstruction of the training data. Furthermore, the method leads to an overall reduction in the total variance of the point distribution model. Thus, it finds correspondence between semilandmarks that are highly correlated in the shape tangent space. The method...

  6. Biodegradable shape memory nanocomposites with thermal and magnetic field responsiveness.

    Science.gov (United States)

    Zhang, Xvming; Lu, Xili; Wang, Zhaomin; Wang, Jianyong; Sun, Zhijie

    2013-01-01

    Thermal and magnetic field responsive biodegradable shape memory polymer nanocomposite was prepared with Fe3O4 nanoparticles and poly(L-lactides) (PLLA). The magnetic Fe3O4 nanoparticles with an average size of 9 nm were initially synthesized by co-precipitation method and then followed by surface modification using oleic acid. The TEM and SEM results show that the surface modified Fe3O4 nanoparticles can evenly disperse in chloroform and PLLA polymer matrix. The tensile test results show that the addition of Fe3O4 nanoparticles to a PLLA matrix greatly improved the elastic modulus, tensile strength, elongation at break, and the shape memory properties as well. Moreover, the shape recovery process of the nanocomposites driven by an alternating magnetic field was also observed. However, the shape recovery ratio and the recovery speed in an alternating magnetic field are lower than that occurred in 70 °C water. The lower shape recovery ratio and the recovery speed in an alternating magnetic field is attributed to the low frequency and strength of the magnetic field, which lead to small heat generated by Fe3O4 nanoparticles.

  7. Radio-optical galaxy shape correlations in the COSMOS field

    OpenAIRE

    Tunbridge, Ben; Harrison, Ian; Brown, Michael L.

    2016-01-01

    We investigate the correlations in galaxy shapes between optical and radio wavelengths using archival observations of the Cosmic Evolution Survey (COSMOS) field. Cross-correlation studies between different wavebands will become increasingly important for precision cosmology as future large surveys may be dominated by systematic rather than statistical errors. In the case of weak lensing, galaxy shapes must be measured to extraordinary accuracy (shear systematics of <0.01 percent) in order ...

  8. Marginal Shape Deep Learning: Applications to Pediatric Lung Field Segmentation.

    Science.gov (United States)

    Mansoor, Awais; Cerrolaza, Juan J; Perez, Geovanny; Biggs, Elijah; Nino, Gustavo; Linguraru, Marius George

    2017-02-11

    Representation learning through deep learning (DL) architecture has shown tremendous potential for identification, localization, and texture classification in various medical imaging modalities. However, DL applications to segmentation of objects especially to deformable objects are rather limited and mostly restricted to pixel classification. In this work, we propose marginal shape deep learning (MaShDL), a framework that extends the application of DL to deformable shape segmentation by using deep classifiers to estimate the shape parameters. MaShDL combines the strength of statistical shape models with the automated feature learning architecture of DL. Unlike the iterative shape parameters estimation approach of classical shape models that often leads to a local minima, the proposed framework is robust to local minima optimization and illumination changes. Furthermore, since the direct application of DL framework to a multi-parameter estimation problem results in a very high complexity, our framework provides an excellent run-time performance solution by independently learning shape parameter classifiers in marginal eigenspaces in the decreasing order of variation. We evaluated MaShDL for segmenting the lung field from 314 normal and abnormal pediatric chest radiographs and obtained a mean Dice similarity coefficient of 0.927 using only the four highest modes of variation (compared to 0.888 with classical ASM 1 (p-value=0.01) using same configuration). To the best of our knowledge this is the first demonstration of using DL framework for parametrized shape learning for the delineation of deformable objects.

  9. Marginal shape deep learning: applications to pediatric lung field segmentation

    Science.gov (United States)

    Mansoor, Awais; Cerrolaza, Juan J.; Perez, Geovany; Biggs, Elijah; Nino, Gustavo; Linguraru, Marius George

    2017-02-01

    Representation learning through deep learning (DL) architecture has shown tremendous potential for identification, local- ization, and texture classification in various medical imaging modalities. However, DL applications to segmentation of objects especially to deformable objects are rather limited and mostly restricted to pixel classification. In this work, we propose marginal shape deep learning (MaShDL), a framework that extends the application of DL to deformable shape segmentation by using deep classifiers to estimate the shape parameters. MaShDL combines the strength of statistical shape models with the automated feature learning architecture of DL. Unlike the iterative shape parameters estimation approach of classical shape models that often leads to a local minima, the proposed framework is robust to local minima optimization and illumination changes. Furthermore, since the direct application of DL framework to a multi-parameter estimation problem results in a very high complexity, our framework provides an excellent run-time performance solution by independently learning shape parameter classifiers in marginal eigenspaces in the decreasing order of variation. We evaluated MaShDL for segmenting the lung field from 314 normal and abnormal pediatric chest radiographs and obtained a mean Dice similarity coefficient of 0:927 using only the four highest modes of variation (compared to 0:888 with classical ASM1 (p-value=0:01) using same configuration). To the best of our knowledge this is the first demonstration of using DL framework for parametrized shape learning for the delineation of deformable objects.

  10. Magnetic field assisted programming of particle shapes and patterns.

    Science.gov (United States)

    Xu, Wenwen; Yao, Yuyu; Klassen, John S; Serpe, Michael J

    2015-09-28

    Anisotropic particles have generated an enormous amount of research interest due to their applications for drug delivery, electronic displays and as micromotors. However, up till now, there is no single protocol capable of generating particles of "patchy" composition with a variety of well-defined and predictable shapes. To address this, in this submission we dispersed magnetic nanoparticles (MNPs) in a non-magnetic fluid containing monomer and crosslinker. This solution was added to the surface of Teflon, which was submerged in the solvent 2,2,4-trimethylpentane. Under these conditions a round, stable droplet was formed on the Teflon. Upon exposure to a permanent magnet, the MNPs self-assembled into clusters with a variety shapes and sizes. The shape and size of the clusters depended on the magnetic field strength, which we controlled by systematically varying the distance between the magnet and the droplet. Interestingly, the shape of the liquid droplet was also influenced by the magnetic field. Upon polymerization, the MNP patterns and the droplet shape was preserved. We also show that very complex MNP patterns and particle shapes could be generated by controlling the distance between the drop and both a magnet above and below the droplet. In this case, the resulting patterns depended on whether the magnets were attracting or repelling each other, which was capable of changing the field lines that the MNPs align with. Overall, this approach is capable of generating particles with predictable MNP patterns and particle shapes without the use of any templates or complex synthetic steps. Furthermore, by using a sprayer (or similar approaches, e.g., ink jet printing) this technique can be easily scaled up to produce many complex anisotropic particles in a short amount of time.

  11. MINERAL HORIZONS, ELECTROMAGNETIC FIELDS AND CIRCULAR SHAPES IN THE GRASS

    Directory of Open Access Journals (Sweden)

    Valentino Straser

    2009-12-01

    Full Text Available The occasional appearance of circular shapes in meadows and farmland located on slopes usually affected by gravitational phenomena, offered an occasion for verifying the possible relation between the position of the circles in the grass, the gravitational movement of the slope affecting its mineral horizons and the variations of electric and static magnetic fields close to the circular shapes and in the surrounding area. The stress caused by the “creeping” movement in the uderlying ground turned out to be in direct relation with the variation in the electric and magnetic fields caused by piezoelectric and piezomagnetic minerals such as quartz. The onset of the electromagnetic process involves the conversion of electric energy on the surface into an area of spherical shape which is linked with a different growth of herbaceous species compared to the surrounding vegetation.

  12. Equilibrium Shape of Ferrofluid in the Uniform External Field

    Science.gov (United States)

    2017-07-14

    ellipsoidal solutions in the problems of electromagnetism , can be found in the works of Stratton,3 Landau and Lifshitz,4 and Akhiezer et al.5 Fig...applied external electromagnetic fields. Even in the static regimes, they demonstrate a variety of qualitative and quantitative transformations often... problems numerically. 15. SUBJECT TERMS ellipsoidal solutions, equilibrium shapes, Maxwell stress tensor, thermodynamics, variational computational

  13. Mechanisms for shaping receptive field in monkey area TE.

    Science.gov (United States)

    Obara, Keitaro; O'Hashi, Kazunori; Tanifuji, Manabu

    2017-10-01

    Visual object information is conveyed from V1 to area TE along the ventral visual pathway with increasing receptive field (RF) sizes. The RFs of TE neurons are known to be large, but it is largely unknown how large RFs are shaped along the ventral visual pathway. In this study, we addressed this question in two aspects, static and dynamic mechanisms, by recording neural responses from macaque area TE and V4 to object stimuli presented at various locations in the visual field. As a component related to static mechanisms, we found that in area TE, but not in V4, response latency to objects presented at fovea were different from objects in periphery. As a component of the dynamic mechanisms, we examined effects of spatial attention on the RFs of TE neurons. Spatial attention did not affect response latency but modulated response magnitudes depending on attended location, shifting of the longitudinal axis of RFs toward the attended locations. In standard models of large RF formation, downstream neurons pool information from nearby RFs, and this process is repeated across the visual field and at each step along the ventral visual pathway. The present study revealed that this mechanism is not that simple: 1) different circuit mechanisms for foveal and peripheral visual fields may be situated between V4 and area TE, and 2) spatial attention dynamically changes the shape of RFs.NEW & NOTEWORTHY Receptive fields (RFs) of neurons are progressively increased along the ventral visual pathway so that an RF at the final stage, area TE, covers a large area of the visual field. We explored the mechanism and suggested involvement of parallel circuit mechanisms between V4 and TE for foveal and peripheral parts of visual field. We also found a dynamic component of RF shape formation through attentional modulation of responses in a location-dependent manner. Copyright © 2017 the American Physiological Society.

  14. Shape and director field deformation of tactoids of plate-like colloids in a magnetic field

    NARCIS (Netherlands)

    Verhoeff, A.A.|info:eu-repo/dai/nl/304829579; Otten, R.H.J.; van der Schoot, P.; Lekkerkerker, H.N.W.|info:eu-repo/dai/nl/159054885

    2009-01-01

    We investigated by means of polarization microscopy the influence of a magnetic field on the shape and director field of nematic droplets in dispersions of plate-like colloidal particles. To interpret the experimental observations, we put forward a simple theory in which we presume strong anchoring

  15. Shaping magnetic fields to direct therapy to ears and eyes.

    Science.gov (United States)

    Shapiro, B; Kulkarni, S; Nacev, A; Sarwar, A; Preciado, D; Depireux, D A

    2014-07-11

    Magnetic fields have the potential to noninvasively direct and focus therapy to disease targets. External magnets can apply forces on drug-coated magnetic nanoparticles, or on living cells that contain particles, and can be used to manipulate them in vivo. Significant progress has been made in developing and testing safe and therapeutic magnetic constructs that can be manipulated by magnetic fields. However, we do not yet have the magnet systems that can then direct those constructs to the right places, in vivo, over human patient distances. We do not yet know where to put the external magnets, how to shape them, or when to turn them on and off to direct particles or magnetized cells-in blood, through tissue, and across barriers-to disease locations. In this article, we consider ear and eye disease targets. Ear and eye targets are too deep and complex to be targeted by a single external magnet, but they are shallow enough that a combination of magnets may be able to direct therapy to them. We focus on how magnetic fields should be shaped (in space and time) to direct magnetic constructs to ear and eye targets.

  16. High-resolution field shaping utilizing a masked multileaf collimator.

    Science.gov (United States)

    Williams, P C; Cooper, P

    2000-08-01

    Multileaf collimators (MLCs) have become an important tool in the modern radiotherapy department. However, the current limit of resolution (1 cm at isocentre) can be too coarse for acceptable shielding of all fields. A number of mini- and micro-MLCs have been developed, with thinner leaves to achieve approved resolution. Currently however, such devices are limited to modest field sizes and stereotactic applications. This paper proposes a new method of high-resolution beam collimation by use of a tertiary grid collimator situated below the conventional MLC. The width of each slit in the grid is a submultiple of the MLC width. A composite shaped field is thus built up from a series of subfields, with the main MLC defining the length of each strip within each subfield. Presented here are initial findings using a prototype device. The beam uniformity achievable with such a device was examined by measuring transmission profiles through the grid using a diode. Profiles thus measured were then copied and superposed to generate composite beams, from which the uniformity achievable could be assessed. With the average dose across the profile normalized to 100%, hot spots up to 5.0% and troughs of 3% were identified for a composite beam of 2 x 5.0 mm grids, as measured at Dmax for a 6 MV beam. For a beam composed from 4 x 2.5 mm grids, the maximum across the profile was 3.0% above the average, and the minimum 2.5% below. Actual composite profiles were also formed using the integrating properties of film, with the subfield indexing performed using an engineering positioning stage. The beam uniformity for these fields compared well with that achieved in theory using the diode measurements. Finally sine wave patterns were generated to demonstrate the potential improvements in field shaping and conformity using this device as opposed to the conventional MLC alone. The scalloping effect on the field edge commonly seen on MLC fields was appreciably reduced by use of 2 x 5.0 mm

  17. Formation of v-shaped potentials. [auroral zone electric fields

    Science.gov (United States)

    Thiemann, H.; Singh, N.; Schunk, R. W.

    1983-01-01

    The V-shaped potential structures formed by the injection of a non-neutral electron current into a cold background plasma were simulated numerically. The injection disturbs the initial quasi-neutral plasma, leading to the excitation of strong turbulences which heat the plasma. This leads to expulsion of the plasma from the simulation region. Due to ambipolar electric fields the current injection is interrupted and the initial background plasma is extracted from the system. A particle composition with the characteristics of the two plasma reservoirs now represents the plasma in the simulation region. The interaction of the electron beam with this plasma excites turbulences of smaller amplitudes. A nearly constant time averaged potential drop with nonstationary distribution develops across the system. Single and multiple double layers may form for the duration of one ion plasma period.

  18. Active subthreshold dendritic conductances shape the local field potential.

    Science.gov (United States)

    Ness, Torbjørn V; Remme, Michiel W H; Einevoll, Gaute T

    2016-07-01

    The local field potential (LFP), the low-frequency part of extracellular potentials recorded in neural tissue, is often used for probing neural circuit activity. Interpreting the LFP signal is difficult, however. While the cortical LFP is thought mainly to reflect synaptic inputs onto pyramidal neurons, little is known about the role of the various subthreshold active conductances in shaping the LFP. By means of biophysical modelling we obtain a comprehensive qualitative understanding of how the LFP generated by a single pyramidal neuron depends on the type and spatial distribution of active subthreshold currents. For pyramidal neurons, the h-type channels probably play a key role and can cause a distinct resonance in the LFP power spectrum. Our results show that the LFP signal can give information about the active properties of neurons and imply that preferred frequencies in the LFP can result from those cellular properties instead of, for example, network dynamics. The main contribution to the local field potential (LFP) is thought to stem from synaptic input to neurons and the ensuing subthreshold dendritic processing. The role of active dendritic conductances in shaping the LFP has received little attention, even though such ion channels are known to affect the subthreshold neuron dynamics. Here we used a modelling approach to investigate the effects of subthreshold dendritic conductances on the LFP. Using a biophysically detailed, experimentally constrained model of a cortical pyramidal neuron, we identified conditions under which subthreshold active conductances are a major factor in shaping the LFP. We found that, in particular, the hyperpolarization-activated inward current, Ih , can have a sizable effect and cause a resonance in the LFP power spectral density. To get a general, qualitative understanding of how any subthreshold active dendritic conductance and its cellular distribution can affect the LFP, we next performed a systematic study with a

  19. Non-potential Field Formation in the X-shaped Quadrupole Magnetic Field Configuration

    Science.gov (United States)

    Kawabata, Y.; Inoue, S.; Shimizu, T.

    2017-06-01

    Some types of solar flares are observed in X-shaped quadrupolar field configuration. To understand the magnetic energy storage in such a region, we studied non-potential field formation in an X-shaped quadrupolar field region formed in the active region NOAA 11967, which produced three X-shaped M-class flares on 2014 February 2. Nonlinear force-free field modeling was applied to a time series of vector magnetic field maps from the Solar Optical Telescope on board Hinode and the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. Our analysis of the temporal three-dimensional magnetic field evolution shows that the sufficient free energy had already been stored more than 10 hr before the occurrence of the first M-class flare and that the storage was observed in a localized region. In this localized region, quasi-separatrix layers (QSLs) started to develop gradually from 9 hr before the first M-class flare. One of the flare ribbons that appeared in the first M-class flare was co-spatial with the location of the QSLs, suggesting that the formation of the QSLs is important in the process of energy release. These QSLs do not appear in the potential field calculation, indicating that they were created by the non-potential field. The formation of the QSLs was associated with the transverse photospheric motion of the pre-emerged flux and the emergence of a new flux. This observation indicates that the occurrence of the flares requires the formation of QSLs in the non-potential field in which free magnetic energy is stored in advance.

  20. Shape oscillation of bubbles in the acoustic field

    OpenAIRE

    Matsumoto, Keishi; Ueno, Ichiro

    2009-01-01

    The authors introduce dynamics of multiple air bubbles exposed to ultrasonic wave while ascending in water in the present fluid dynamics video. The authors pay attention to the shape oscillation and the transition from the volume to the shape oscillations of the bubble. Correlation between the bubble size and the mechanism of the excitation of the shape oscillation is introduced.

  1. Anatomy of nuclear shape transition in the relativistic mean field theory

    OpenAIRE

    Sil, Tapas; Agrawal, B. K.; De, J. N.; Samaddar, S. K.

    2001-01-01

    A detailed microscopic study of the temperature dependence of the shapes of some rare-earth nuclei is made in the relativistic mean field theory. Analyses of the thermal evolution of the single-particle orbitals and their occupancies leading to the collapse of the deformation are presented. The role of the non-linear $\\sigma-$field on the shape transition in different nuclei is also investigated; in its absence the shape transition is found to be sharper.

  2. Alignment of rod-shaped gold particles by electric fields

    NARCIS (Netherlands)

    Zande, B.M.I. van der; Koper, G.J.M.; Lekkerkerker, H.N.W.

    1999-01-01

    The electro-optical response of colloidal dispersions of rod-shaped gold particles is studied for various aspect ratios (2.6 < L/d < 49; d = 15 nm) by monitoring the absorbance spectra in the visible wavelength regime. The absorbance spectra strongly depend on the degree of orientational order of

  3. Experimental comparison of ring and diamond shaped planar Hall effect bridge magnetic field sensors

    DEFF Research Database (Denmark)

    Henriksen, Anders Dahl; Rizzi, Giovanni; Hansen, Mikkel Fougt

    2015-01-01

    Planar Hall effect magnetic field sensors with ring and diamond shaped geometries are experimentally compared with respect to their magnetic field sensitivity and total signal variation. Theoretically, diamond shaped sensors are predicted to be 41% more sensitive than corresponding ring shaped...... improvement varied from 0% to 35% where the largest improvement was observed for sensor stacks with comparatively strong exchange bias. This is explained by the ring sensors being less affected by shape anisotropy than the diamond sensors. To study the effect of shape anisotropy, we also characterized sensors...... that were surrounded by the magnetic stack with a small gap of 3 lm. These sensors were found to be less effected by shape anisotropy and thus showed higher low-field sensitivities....

  4. Intraband carrier kinetics and picosecond pulse shaping in field-enhanced bulk semiconductor absorbers.

    Science.gov (United States)

    Uskov, A V; McInerney, J; Karin, J R; Bowers, J E

    1998-03-01

    Picosecond pulse propagation through a field-enhanced waveguide bulk semiconductor saturable absorber is studied numerically. Fast switching from unsaturated absorption to delayed strong saturation and gain, as well as the predicted dependence of saturation energy on electric field, is based on intraband carrier kinetics and electric-field dynamics in the absorber and can lead to improved, controllable pulse shaping.

  5. Automatic construction of statistical shape models using deformable simplex meshes with vector field convolution energy.

    Science.gov (United States)

    Wang, Jinke; Shi, Changfa

    2017-04-24

    In the active shape model framework, principal component analysis (PCA) based statistical shape models (SSMs) are widely employed to incorporate high-level a priori shape knowledge of the structure to be segmented to achieve robustness. A crucial component of building SSMs is to establish shape correspondence between all training shapes, which is a very challenging task, especially in three dimensions. We propose a novel mesh-to-volume registration based shape correspondence establishment method to improve the accuracy and reduce the computational cost. Specifically, we present a greedy algorithm based deformable simplex mesh that uses vector field convolution as the external energy. Furthermore, we develop an automatic shape initialization method by using a Gaussian mixture model based registration algorithm, to derive an initial shape that has high overlap with the object of interest, such that the deformable models can then evolve more locally. We apply the proposed deformable surface model to the application of femur statistical shape model construction to illustrate its accuracy and efficiency. Extensive experiments on ten femur CT scans show that the quality of the constructed femur shape models via the proposed method is much better than that of the classical spherical harmonics (SPHARM) method. Moreover, the proposed method achieves much higher computational efficiency than the SPHARM method. The experimental results suggest that our method can be employed for effective statistical shape model construction.

  6. On the Shape of Force-Free Field Lines in the Solar Corona

    KAUST Repository

    Prior, C.

    2012-02-02

    This paper studies the shape parameters of looped field lines in a linear force-free magnetic field. Loop structures with a sufficient amount of kinking are generally seen to form S or inverse S (Z) shapes in the corona (as viewed in projection). For a single field line, we can ask how much the field line is kinked (as measured by the writhe), and how much neighbouring flux twists about the line (as measured by the twist number). The magnetic helicity of a flux element surrounding the field line can be decomposed into these two quantities. We find that the twist helicity contribution dominates the writhe helicity contribution, for field lines of significant aspect ratio, even when their structure is highly kinked. These calculations shed light on some popular assumptions of the field. First, we show that the writhe of field lines of significant aspect ratio (the apex height divided by the footpoint width) can sometimes be of opposite sign to the helicity. Secondly, we demonstrate the possibility of field line structures which could be interpreted as Z-shaped, but which have a helicity value sign expected of an S-shaped structure. These results suggest that caution should be exercised in using two-dimensional images to draw conclusions on the helicity value of field lines and flux tubes. © 2012 Springer Science+Business Media B.V.

  7. Statistical Shape Modelling and Markov Random Field Restoration (invited tutorial and exercise)

    DEFF Research Database (Denmark)

    Hilger, Klaus Baggesen

    This tutorial focuses on statistical shape analysis using point distribution models (PDM) which is widely used in modelling biological shape variability over a set of annotated training data. Furthermore, Active Shape Models (ASM) and Active Appearance Models (AAM) are based on PDMs and have proven...... themselves a generic holistic tool in various segmentation and simulation studies. Finding a basis of homologous points is a fundamental issue in PDMs which effects both alignment and decomposition of the training data, and may be aided by Markov Random Field Restoration (MRF) of the correspondence...... deformation field between shapes. The tutorial demonstrates both generative active shape and appearance models, and MRF restoration on 3D polygonized surfaces. ''Exercise: Spectral-Spatial classification of multivariate images'' From annotated training data this exercise applies spatial image restoration...

  8. Markov Random Field Restoration of Point Correspondences for Active Shape Modelling

    DEFF Research Database (Denmark)

    Hilger, Klaus Baggesen; Paulsen, Rasmus Reinhold; Larsen, Rasmus

    2004-01-01

    In this paper it is described how to build a statistical shape model using a training set with a sparse of landmarks. A well defined model mesh is selected and fitted to all shapes in the training set using thin plate spline warping. This is followed by a projection of the points of the warped...... model mesh to the target shapes. When this is done by a nearest neighbour projection it can result in folds and inhomogeneities in the correspondence vector field. The novelty in this paper is the use and extension of a Markov random field regularisation of the correspondence field. The correspondence...... model that produces highly homogeneous polygonised shapes with improved reconstruction capabilities of the training data. Furthermore, the method leads to an overall reduction in the total variance of the resulting point distribution model. The method is demonstrated on a set of human ear canals...

  9. Effects of the shape anisotropy and biasing field on the magnetization reversal process of the diamond-shaped NiFe nano films

    Science.gov (United States)

    Xu, Sichen; Yin, Jianfeng; Tang, Rujun; Zhang, Wenxu; Peng, Bin; Zhang, Wanli

    2017-11-01

    The effects of the planar shape anisotropy and biasing field on the magnetization reversal process (MRP) of the diamond-shaped NiFe nano films have been investigated by micromagnetic simulations. Results show that when the length to width ratio (LWR) of the diamond-shaped film is small, the MRP of the diamond-shaped films are sensitive to LWR. But when LWR is larger than 2, a stable domain switching mode is observed which nucleates from the center of the diamond and then expands to the edges. At a fixed LWR, the magnitude of the switching fields decrease with the increase of the biasing field, but the domain switching mode is not affected by the biasing field. Further analysis shows that demagnetization energy dominates over the MRP of the diamond-shaped films. The above LWR dependence of MRP can be well explained by a variation of the shape anisotropic factor with LWR.

  10. Calculation of pressure fields from arbitrarily shaped, apodized, and excited ultrasound transducers

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Svendsen, Niels Bruun

    1992-01-01

    A method for simulation of pulsed pressure fields from arbitrarily shaped, apodized and excited ultrasound transducers is suggested. It relies on the Tupholme-Stepanishen method for calculating pulsed pressure fields, and can also handle the continuous wave and pulse-echo case. The field...... is calculated by dividing the surface into small rectangles and then Summing their response. A fast calculation is obtained by using the far-field approximation. Examples of the accuracy of the approach and actual calculation times are given...

  11. Field dependence of the Josephson current and Fiske resonances in specially shaped Josephson junctions

    Science.gov (United States)

    Gijsbertsen, J. G.; Houwman, E. P.; Klopman, B. B. G.; Flokstra, J.; Rogalla, H.; Quenter, D.; Lemke, S.

    1995-02-01

    We investigated the magnetic-field dependence of the Josephson current and Fiske resonances in specially shaped Josephson junctions. In order to be able to use junctions for high-resolution X-ray spectroscopy, a very good suppression of the sidelobes of both the Josephson current and the Fiske resonances must be achieved. In a theoretical argument we show that a properly chosen junction shape leads to the sidelobe suppression of both the critical current and Fiske resonance amplitudes. The Josephson current and Fiske resonance amplitudes were measured as a function of the magnetic field, for junctions fabricated in Nb/Al technology. As expected, a very good sidelobe suppression was obtained for quartic-shaped junctions. For junctions with anodized structures within the tunneling area, the shape of the internal structures is reflected in the field dependence of both the Josephson current and the Fiske resonances. Finally, Fiske modes in these junctions have been imaged with low-temperature scanning electron microscopy, and we conclude that a quartic junction can be approximated by a rectangle, to describe the lower-order Fiske modes, whereas the high-order modes are specific to the exact shape of the junction.

  12. Particle shape effects on ferrofuids flow and heat transfer under influence of low oscillating magnetic field

    Science.gov (United States)

    Hassan, Mohsan; Zeeshan, Ahmad; Majeed, Aaqib; Ellahi, Rahmat

    2017-12-01

    The purpose of this study is to theoretically examine nanoparticle shapes behavior on mass and heat flow of ferrofluid over a rotating disk with the presence of low oscillating magnetic field. Ferrofluid is prepared by water and iron nanoparticles of three different shapes like sphere, oblate ellipsoid and prolate ellipsoid. The problem has been formulated by employing the controllable force into the fundamental hydrodynamic equations and its effect along with particle shape factor on physical properties of fluid is discussed. These equations are converted into a system of ordinary differential equations by employing appropriate similarity approach and then solved by HAM based Bvph2 package. Effects of particle shape, particle volume fraction and magnetization parameter on axial, radial and tangential velocities along with temperature profile are demonstrated through graphically. The results for local Nusselt number are calculated and analyzed and the path for enhancement in heat transfer is also proposed.

  13. Pulse shape optimization for electron-positron production in rotating fields

    Science.gov (United States)

    Fillion-Gourdeau, François; Hebenstreit, Florian; Gagnon, Denis; MacLean, Steve

    2017-07-01

    We optimize the pulse shape and polarization of time-dependent electric fields to maximize the production of electron-positron pairs via strong field quantum electrodynamics processes. The pulse is parametrized in Fourier space by a B -spline polynomial basis, which results in a relatively low-dimensional parameter space while still allowing for a large number of electric field modes. The optimization is performed by using a parallel implementation of the differential evolution, one of the most efficient metaheuristic algorithms. The computational performance of the numerical method and the results on pair production are compared with a local multistart optimization algorithm. These techniques allow us to determine the pulse shape and field polarization that maximize the number of produced pairs in computationally accessible regimes.

  14. D-shaped tilted fiber Bragg grating using magnetic fluid for magnetic field sensor

    Science.gov (United States)

    Ying, Yu; Zhang, Rui; Si, Guang-Yuan; Wang, Xin; Qi, Yuan-Wei

    2017-12-01

    In our work, a numerical investigation of a magnetic field sensor based on a D-shaped tilted fiber Bragg grating and magnetic fluid is performed. The sensing probe is constructed by placing the magnetic fluid film on the flat surface of the D-shaped tilted fiber Bragg grating. We investigate the resonance wavelengths of the proposed structure with different tilted angles of grating ranging from 0° to 20°, and analyze the magnetic field sensing characteristics. The simulation results show that the optical fiber sensor exhibits optimal transmission characteristics with a tilted angle of 8°. The wavelength sensitivity of the magnetic field sensor is as high as -0.18nm/Oe in the range of 30Oe-270Oe, and it demonstrates a linearity up to R2= -0.9998. Such sensor has potential applications in determining magnetic sensing field.

  15. Shape and deformation measurements of 3D objects using volume speckle field and phase retrieval

    DEFF Research Database (Denmark)

    Anand, A; Chhaniwal, VK; Almoro, Percival

    2009-01-01

    the shape and deformation of 3D objects from the sequential intensity measurements of volume speckle field and phase retrieval based on angular-spectrum propagation technique is described here. The shape of a convex spherical surface was measured directly from the calculated phase map, and micrometer......Shape and deformation measurement of diffusely reflecting 3D objects are very important in many application areas, including quality control, nondestructive testing, and design. When rough objects are exposed to coherent beams, the scattered light produces speckle fields. A method to measure......-sized deformation induced on a metal sheet was obtained upon subtraction of the phase, corresponding to unloaded and loaded states. Results from computer simulations confirm the experiments. (C) 2009 Optical Society of America....

  16. Mitigation of Power frequency Magnetic Fields. Using Scale Invariant and Shape Optimization Methods

    Energy Technology Data Exchange (ETDEWEB)

    Salinas, Ener; Yueqiang Liu; Daalder, Jaap; Cruz, Pedro; Antunez de Souza, Paulo Roberto Jr; Atalaya, Juan Carlos; Paula Marciano, Fabianna de; Eskinasy, Alexandre

    2006-10-15

    The present report describes the development and application of two novel methods for implementing mitigation techniques of magnetic fields at power frequencies. The first method makes use of scaling rules for electromagnetic quantities, while the second one applies a 2D shape optimization algorithm based on gradient methods. Before this project, the first method had already been successfully applied (by some of the authors of this report) to electromagnetic designs involving pure conductive Material (e.g. copper, aluminium) which implied a linear formulation. Here we went beyond this approach and tried to develop a formulation involving ferromagnetic (i.e. non-linear) Materials. Surprisingly, we obtained good equivalent replacement for test-transformers by varying the input current. In spite of the validity of this equivalence constrained to regions not too close to the source, the results can still be considered useful, as most field mitigation techniques are precisely developed for reducing the magnetic field in regions relatively far from the sources. The shape optimization method was applied in this project to calculate the optimal geometry of a pure conductive plate to mitigate the magnetic field originated from underground cables. The objective function was a weighted combination of magnetic energy at the region of interest and dissipated heat at the shielding Material. To our surprise, shapes of complex structure, difficult to interpret (and probably even harder to anticipate) were the results of the applied process. However, the practical implementation (using some approximation of these shapes) gave excellent experimental mitigation factors.

  17. Classic Articles in Special Education Articles That Shaped the Field, 1960 to 1996

    Science.gov (United States)

    McLeskey, J.

    2004-01-01

    There is little consensus regarding which articles have shaped the field of special education and are therefore classics. To begin to address this issue, this article uses an objective, databased procedure to identify the 50 most frequently cited articles in general special education journals (i.e., Exceptional Children, Remedial and Special…

  18. Dynamics of arbitrary shaped propellers driven by a rotating magnetic field

    Science.gov (United States)

    Morozov, Konstantin I.; Mirzae, Yoni; Kenneth, Oded; Leshansky, Alexander M.

    2017-04-01

    Motion in fluids at the micro(nano)metric scale is dominated by viscosity. One efficient propulsion method relies on a weak uniform rotating magnetic field that drives a chiral object. From bacterial flagella to artificial magnetic micro- or nanohelices, rotation of a corkscrew is considered as a universally efficient propulsion gait in viscous environments. However, recent experimental studies have demonstrated that geometrically achiral microscale objects or random-shaped magnetic aggregates can propel similarly to helical micromotors. Although approximate theories concerning dynamics of helical magnetic propellers are available, propulsion of achiral particles or objects with complex shapes is not understood. Here we present a general theory of rotation and propulsion of magnetized object of arbitrary shape driven by a rotating magnetic field. Intrinsic symmetries of the viscous mobility tensors yield compact classification of stable rotational states depending on the orientation of the magnetic moment with respect to principal rotation axes of the object. Propulsion velocity can be written in terms of geometry-dependent chirality matrix Ch , where both the diagonal elements (owing to orientation-dependent handedness) and off-diagonal entries (that do not necessitate handedness) contribute in a similar way. In general, the theory anticipates multiplicity of stable rotational states corresponding to two (complimentary to π ) angles the magnetization forms with the field rotation axis. Thus, two identical magnetic objects may propel with different speeds or even in opposite directions. However, for a class of simple achiral objects, there is a particular magnetization whereas the pair of symmetric rotational states gives rise to a unique chiral-like propulsion gait, closely resembling that of an ideal helical propeller. In other words, a geometrically achiral object can acquire apparent chirality due to its interaction with the external magnetic field. The

  19. Influences of the Cloud Shape of Fuel-Air Mixtures on the Overpressure Field

    Directory of Open Access Journals (Sweden)

    Chunhua Bai

    2016-01-01

    Full Text Available This paper presents an experiment system in the open field, which comprises a charge structure (approximately 166.2 kg, a high-speed camera subsystem, and a pressure measurement subsystem. Through a series of experiments under the cylindrical clouds with different diameters, heights, and diameter-to-height ratios (D : H, the influences of various cloud shapes on the overpressure field were analyzed and discussed. Based on the experimental results, the overpressure field was divided into two zones: detonation wave zone and shock wave zone. It is found that the overpressure of shock waves at the same distance from the explosion center increased with the diameters, but the variations of heights had little impact on the overpressure. Therefore, the pancake-shaped cloud of fuel-air mixtures is the optimal shape for obtaining the wider overpressure field. Moreover, it is found that the overpressure field gets the maximum under the diameter-to-height ratios of 5.7 in the same distance within the studied range.

  20. Strong field line shapes and photon statistics from a single molecule under anomalous noise.

    Science.gov (United States)

    Sanda, Frantisek

    2009-10-01

    We revisit the line-shape theory of a single molecule with anomalous stochastic spectral diffusion. Waiting time profiles for bath induced spectral jumps in the ground and excited states become different when a molecule, probed by continuous-wave laser field, reaches the steady state. This effect is studied for the stationary dichotomic continuous-time-random-walk spectral diffusion of a single two-level chromophore with power-law distributions of waiting times. Correlated waiting time distributions, line shapes, two-point fluorescence correlation function, and Mandel Q parameter are calculated for arbitrary magnitude of laser field. We extended previous weak field results and examined the breakdown of the central limit theorem in photon statistics, indicated by asymptotic power-law growth of Mandel Q parameter. Frequency profile of the Mandel Q parameter identifies the peaks of spectrum, which are related to anomalous spectral diffusion dynamics.

  1. Far-field beam shaping through static wavefront correction in the near field on the HELEN laser

    Science.gov (United States)

    Bett, Thomas H.; Hopps, N. W.; Nolan, J. R.

    2002-10-01

    This report discusses the design and installation of a phase optic inserted in the near field of the HELEN high power glass laser. The element is designed to shape the intensity distribution at the focal spot of the laser to produce an increase in the peak intensity through correction of static and thermally induced wavefront errors on the beam. A phase element has been fabricated commercially using a magneto-rheological finishing tool. Test data is presented.

  2. Chirality-dependent propagations of domain walls in L-shaped nanostrips under unidirectional fields

    Science.gov (United States)

    Dong, Xinwei; Wang, Ruifang

    2017-12-01

    The propagations of domain walls (DWs) in L-shaped nanostrips under unidirectional fields were investigated by micromagnetic simulations. The DWs’ transmission fields, moving speeds, and width variations are all chirality-dependent. From the viewpoint of magnetic charge distribution, these phenomena can be attributed to the near-field and chirality-dependent interaction between the DWs (behaving as a magnetic charge pair) and the corner (having two different charge pairs). With increasing corner inner radius, the chirality dependence becomes weak and even disappears at a large inner radius of 1000 nm.

  3. The effect of magnetic field on the shape of etch pits of paracetamol crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ivashchenko, V.E. [Kemerovo State University, Novosibirsk (Russian Federation); Research and Educational Center, Novosibirsk State University (Russian Federation); Boldyrev, V.V.; Shakhtshneider, T.P. [Institute of Solid State Chemistry and Mechanochemistry, RAS, Novosibirsk (Russian Federation); Zakharov, Yu.A.; Krasheninin, V.I. [Kemerovo State University, Novosibirsk (Russian Federation); Ermakov, A.E. [Institute of Physics of Metals, Ural Branch of RAS, Ekaterinburg (Russian Federation)

    2002-04-01

    In the present study we investigate the effect of magnetic field on the shape of etch pits of the crystals of p-hydroxyacetanilide (paracetamol), which is widely used in pharmacy as antipyretic, antiphlogistic medicine. It was discovered that the magnetic field (H=0.5 T, {tau}=15 min) changes the morphology of etch pits and shifts dislocations in paracetamol crystal. Activation energy of the changes induced by the action of the magnetic field was determined to be 63 kJ/mol, which is comparable with the energy of hydrogen bonds in crystal lattice. (orig.)

  4. The Influence of Vesicle Shape and Medium Conductivity on Possible Electrofusion under a Pulsed Electric Field.

    Science.gov (United States)

    Liu, Linying; Mao, Zheng; Zhang, Jianhua; Liu, Na; Liu, Qing Huo

    2016-01-01

    The effects of electric field on lipid membrane and cells have been extensively studied in the last decades. The phenomena of electroporation and electrofusion are of particular interest due to their wide use in cell biology and biotechnology. However, numerical studies on the electrofusion of cells (or vesicles) with different deformed shapes are still rare. Vesicle, being of cell size, can be treated as a simple model of cell to investigate the behaviors of cell in electric field. Based on the finite element method, we investigate the effect of vesicle shape on electrofusion of contact vesicles in various medium conditions. The transmembrane voltage (TMV) and pore density induced by a pulsed field are examined to analyze the possibility of vesicle fusion. In two different medium conditions, the prolate shape is observed to have selective electroporation at the contact area of vesicles when the exterior conductivity is smaller than the interior one; selective electroporation is more inclined to be found at the poles of the oblate vesicles when the exterior conductivity is larger than the interior one. Furthermore, we find that when the exterior conductivity is lower than the internal conductivity, the pulse can induce a selective electroporation at the contact area between two vesicles regardless of the vesicle shape. Both of these two findings have important practical applications in guiding electrofusion experiments.

  5. Controlling the shapes of coated silicon substrates via magnetic fields, a progress report

    Science.gov (United States)

    Ulmer, Melville P.; Coppejans, Rocco; Buchholz, David B.; Cao, Jian; Wang, Xiaoli; Mercado, Alejandro M.; Qian, Jun; Assoufid, Lahsen; O'Donnell, Allison E.; Condron, Kyle S.; Harpt, Benjamin E.

    2017-08-01

    We describe our progress in developing a method for correcting residual figure errors in X-ray mirrors. The technology has applications to both synchrotron radiation beamlines and X-ray astronomy. Our concept is to develop mirrors that are on the order of a millimeter thick. A magnetic smart material (MSM) is deposited onto the mirror substrate (silicon) and coated with a magnetically hard material. The shape of the mirror can be controlled by applying an external magnetic field to the mirror. This causes the MSM to expand or contract, thereby applying a magnetostrictive stress to the mirror and changing its shape. The shape change is maintained after the field has been removed by the magnetic hard material, which retains part of the field and prevents the MSM from relaxing. Here we present the results of shaping 200 µm thick silicon (100) 14 × 2 mm cantilevers and 50 × 50 × 0.1 mm substrates. We demonstrate that not only can a sizable deflection be created, but it can also be retained for ˜ 60 hours.

  6. Estimation of surface curvature from full-field shape data using principal component analysis

    Science.gov (United States)

    Sharma, Sameer; Vinuchakravarthy, S.; Subramanian, S. J.

    2017-01-01

    Three-dimensional digital image correlation (3D-DIC) is a popular image-based experimental technique for estimating surface shape, displacements and strains of deforming objects. In this technique, a calibrated stereo rig is used to obtain and stereo-match pairs of images of the object of interest from which the shapes of the imaged surface are then computed using the calibration parameters of the rig. Displacements are obtained by performing an additional temporal correlation of the shapes obtained at various stages of deformation and strains by smoothing and numerically differentiating the displacement data. Since strains are of primary importance in solid mechanics, significant efforts have been put into computation of strains from the measured displacement fields; however, much less attention has been paid to date to computation of curvature from the measured 3D surfaces. In this work, we address this gap by proposing a new method of computing curvature from full-field shape measurements using principal component analysis (PCA) along the lines of a similar work recently proposed to measure strains (Grama and Subramanian 2014 Exp. Mech. 54 913-33). PCA is a multivariate analysis tool that is widely used to reveal relationships between a large number of variables, reduce dimensionality and achieve significant denoising. This technique is applied here to identify dominant principal components in the shape fields measured by 3D-DIC and these principal components are then differentiated systematically to obtain the first and second fundamental forms used in the curvature calculation. The proposed method is first verified using synthetically generated noisy surfaces and then validated experimentally on some real world objects with known ground-truth curvatures.

  7. Tuning near-field enhancements on an off-resonance nanorod dimer via temporally shaped femtosecond laser

    Science.gov (United States)

    Du, Guangqing; Yang, Qing; Chen, Feng; Lu, Yu; Wu, Yanmin; Ou, Yan; Hou, Xun

    2015-11-01

    We theoretically investigated ultrafast thermal dynamics tuning of near-field enhancements on an off-resonance gold nanorod dimer via temporally shaped femtosecond (fs) laser double pulses. The nonequilibrium thermal excitation is self-consistently coupled into a near-field scattering model for exploring the ultrafast near-field enhancement effects. It is revealed that the near electric-field localized within the gold nanorod dimer can be largely promoted via optimizing the temporal separation and the pulse energy ratio of temporally shaped femtosecond laser double pulses. The results are explained as thermal dynamics manipulation of plasmon resonances in the nanorod dimer via tailoring temporally shaped femtosecond laser. This study provides basic understanding for tuning near-field properties on poorly fabricated metallic nano-structures via temporally shaped femtosecond laser, which can find potential applications in the fields such as fs super-resolution near-field imaging, near-field optical tweezers, and fs photothermal therapy.

  8. Determination of strain fields in porous shape memory alloys using micro-computed tomography

    Science.gov (United States)

    Bormann, Therese; Friess, Sebastian; de Wild, Michael; Schumacher, Ralf; Schulz, Georg; Müller, Bert

    2010-09-01

    Shape memory alloys (SMAs) belong to 'intelligent' materials since the metal alloy can change its macroscopic shape as the result of the temperature-induced, reversible martensite-austenite phase transition. SMAs are often applied for medical applications such as stents, hinge-less instruments, artificial muscles, and dental braces. Rapid prototyping techniques, including selective laser melting (SLM), allow fabricating complex porous SMA microstructures. In the present study, the macroscopic shape changes of the SMA test structures fabricated by SLM have been investigated by means of micro computed tomography (μCT). For this purpose, the SMA structures are placed into the heating stage of the μCT system SkyScan 1172™ (SkyScan, Kontich, Belgium) to acquire three-dimensional datasets above and below the transition temperature, i.e. at room temperature and at about 80°C, respectively. The two datasets were registered on the basis of an affine registration algorithm with nine independent parameters - three for the translation, three for the rotation and three for the scaling in orthogonal directions. Essentially, the scaling parameters characterize the macroscopic deformation of the SMA structure of interest. Furthermore, applying the non-rigid registration algorithm, the three-dimensional strain field of the SMA structure on the micrometer scale comes to light. The strain fields obtained will serve for the optimization of the SLM-process and, more important, of the design of the complex shaped SMA structures for tissue engineering and medical implants.

  9. A Fixpoint-Based Calculus for Graph-Shaped Computational Fields

    DEFF Research Database (Denmark)

    Lluch Lafuente, Alberto; Loreti, Michele; Montanari, Ugo

    2015-01-01

    topology is represented by a graph-shaped field, namely a network with attributes on both nodes and arcs, where arcs represent interaction capabilities between nodes. We propose a calculus where computation is strictly synchronous and corresponds to sequential computations of fixpoints in the graph......-shaped field. Under some conditions, those fixpoints can be computed by synchronised iterations, where in each iteration the attributes of a node is updated based on the attributes of the neighbours in the previous iteration. Basic constructs are reminiscent of the semiring μ-calculus, a semiring......-valued generalisation of the modal μ-calculus, which provides a flexible mechanism to specify the neighbourhood range (according to path formulae) and the way attributes should be combined (through semiring operators). Additional control-How constructs allow one to conveniently structure the fixpoint computations. We...

  10. Factors Shaping Qatari Students’ Career Expectations in STEM, Business or Public Sector Fields

    OpenAIRE

    Sellami, Abdellatif; Kimmel, Linda; Wittrock, Jill; Hunscher, Brian; Cotter, Anna; Al-emadi, Ahmed; Al-Emadi, Darwish

    2017-01-01

    The purpose of this study was to identify factors shaping career expectations of Qatari students. The study examined individual and motivational variables likely to influence career expectations in STEM fields, the public sector, and business. This study used survey data of 802 Qatari students and 543 parents from the 2012 Qatar Education Study. The results suggest a varied, context-dependent portrait of career expectations. The results indicate that the education system in Qat...

  11. Experimental Investigation of Dynamic Wetting Models: Interface Shapes and Velocity Fields Near the Moving Contact Line.

    Science.gov (United States)

    Chen, Qun

    Dynamic wetting is the displacement of one fluid by another immiscible fluid across a solid surface as it spreads. Such processes control many natural phenomena and technological applications. The spreading dynamics of macroscopic fluid bodies are dictated by the hydrodynamics in a microscopic region near the moving contact line. Analytical models have been developed to describe the interface shape and velocity field near the contact line. Using videomicroscopy, particle image velocimetry, and digital image analysis, we make simultaneous measurements of the fluid/fluid interface shape and fluid flow field within the first few hundred microns near a moving contact line. Our experiments establish the validity and limitations of these analytical models. This work extensively tests assumptions embedded in the models and sets up bounds on the parameter space in which the models are valid. The models successfully describe the hydrodynamics near the contact line up to a capillary number ~0.10 but break down at higher capillary number. We determine the origins of this breakdown. We also carefully probe those regions near the contact line where the interface shape and flow field are independent of the macroscopic geometry. Our experimental technique provides a means of obtaining such material-dependent,, geometry-independent information about the system. Such information serves as boundary conditions transferable among different macroscopic geometries. It is an essential ingredient for numerical calculations of the spreading dynamics. The work reported in this thesis sets the stage for predictive modeling of dynamic wetting.

  12. Shape matters: Near-field fluid mechanics dominate the collective motions of ellipsoidal squirmers.

    Science.gov (United States)

    Kyoya, K; Matsunaga, D; Imai, Y; Omori, T; Ishikawa, T

    2015-12-01

    Microswimmers show a variety of collective motions. Despite extensive study, questions remain regarding the role of near-field fluid mechanics in collective motion. In this paper, we describe precisely the Stokes flow around hydrodynamically interacting ellipsoidal squirmers in a monolayer suspension. The results showed that various collective motions, such as ordering, aggregation, and whirls, are dominated by the swimming mode and the aspect ratio. The collective motions are mainly induced by near-field fluid mechanics, despite Stokes flow propagation over a long range. These results emphasize the importance of particle shape in collective motion.

  13. Gendered Expectations: Examining How Peers Shape Female Students' Intent to Pursue STEM Fields.

    Science.gov (United States)

    Riegle-Crumb, Catherine; Morton, Karisma

    2017-01-01

    Building on prior psychological and sociological research on the power of local environments to shape gendered outcomes in STEM fields, this study focuses on the critical stage of adolescence to explore the potential negative impact of exposure to exclusionary messages from peers within girls' science classrooms, as well as the positive potential impact of inclusionary messages. Specifically, utilizing longitudinal data from a diverse sample of adolescent youth, analyses examine how the presence of biased male peers, as well as confident female peers, shape girls' subsequent intentions to pursue different STEM fields, focusing specifically on intentions to pursue the male-dominated fields of computer science and engineering, as well as more gender equitable fields. Results reveal that exposure to a higher percentage of 8th grade male peers in the classroom who endorsed explicit gender/STEM stereotypes significantly and negatively predicted girls' later intentions to pursue a computer science/engineering (CS/E) major. Yet results also reveal that exposure to a higher percentage of confident female peers in the science classroom positively predicted such intentions. These results were specific to CS/E majors, suggesting that peers are an important source of messages regarding whether or not girls should pursue non-traditional STEM fields. This study calls attention to the importance of examining both positive and negative sources of influence within the local contexts where young people live and learn. Limitations and directions for future research are also discussed.

  14. Epitaxial graphene growth and shape dynamics on copper: phase-field modeling and experiments.

    Science.gov (United States)

    Meca, Esteban; Lowengrub, John; Kim, Hokwon; Mattevi, Cecilia; Shenoy, Vivek B

    2013-01-01

    The epitaxial growth of graphene on copper foils is a complex process, influenced by thermodynamic, kinetic, and growth parameters, often leading to diverse island shapes including dendrites, squares, stars, hexagons, butterflies, and lobes. Here, we introduce a phase-field model that provides a unified description of these diverse growth morphologies and compare the model results with new experiments. Our model explicitly accounts for the anisotropies in the energies of growing graphene edges, kinetics of attachment of carbon at the edges, and the crystallinity of the underlying copper substrate (through anisotropy in surface diffusion). We show that anisotropic diffusion has a very important, counterintuitive role in the determination of the shape of islands, and we present a "phase diagram" of growth shapes as a function of growth rate for different copper facets. Our results are shown to be in excellent agreement with growth shapes observed for high symmetry facets such as (111) and (001) as well as for high-index surfaces such as (221) and (310).

  15. Phase-field study of three-dimensional steady-state growth shapes in directional solidification

    Science.gov (United States)

    Gurevich, Sebastian; Karma, Alain; Plapp, Mathis; Trivedi, Rohit

    2010-01-01

    We use a quantitative phase-field approach to study directional solidification in various three-dimensional geometries for realistic parameters of a transparent binary alloy. The geometries are designed to study the steady-state growth of spatially extended hexagonal arrays, linear arrays in thin samples, and axisymmetric shapes constrained in a tube. As a basis to address issues of dynamical pattern selection, the phase-field simulations are specifically geared to identify ranges of primary spacings for the formation of the classically observed “fingers” (deep cells) with blunt tips and “needles” with parabolic tips. Three distinct growth regimes are identified that include a low-velocity regime with only fingers forming, a second intermediate-velocity regime characterized by coexistence of fingers and needles that exist on separate branches of steady-state growth solutions for small and large spacings, respectively, and a third high-velocity regime where those two branches merge into a single one. Along the latter, the growth shape changes continuously from fingerlike to needlelike with increasing spacing. These regimes are strongly influenced by crystalline anisotropy with the third regime extending to lower velocity for larger anisotropy. Remarkably, however, steady-state shapes and tip undercoolings are only weakly dependent on the growth geometry. Those results are used to test existing theories of directional finger growth as well as to interpret the hysteretic nature of the cell-to-dendrite transition.

  16. Dynamic X-ray radiography reveals particle size and shape orientation fields during granular flow.

    Science.gov (United States)

    Guillard, François; Marks, Benjy; Einav, Itai

    2017-08-15

    When granular materials flow, the constituent particles segregate by size and align by shape. The impacts of these changes in fabric on the flow itself are not well understood, and thus novel non-invasive means are needed to observe the interior of the material. Here, we propose a new experimental technique using dynamic X-ray radiography to make such measurements possible. The technique is based on Fourier transformation to extract spatiotemporal fields of internal particle size and shape orientation distributions during flow, in addition to complementary measurements of velocity fields through image correlation. We show X-ray radiography captures the bulk flow properties, in contrast to optical methods which typically measure flow within boundary layers, as these are adjacent to any walls. Our results reveal the rich dynamic alignment of particles with respect to streamlines in the bulk during silo discharge, the understanding of which is critical to preventing destructive instabilities and undesirable clogging. The ideas developed in this paper are directly applicable to many other open questions in granular and soft matter systems, such as the evolution of size and shape distributions in foams and biological materials.

  17. Examination of the switching field distribution (SFD) and the shape anisotropy constant of nickel nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Kraemer, Florian; Bender, Philipp; Tschoepe, Andreas; Birringer, Rainer [Universitaet des Saarlandes, Saarbruecken (Germany)

    2011-07-01

    Nickel nanorods with diameters D<64nm and aspect ratios n>3 are expected to be uniaxial ferromagnetic single domain particles. The most simple approach to estimate their magnetic behavior is the Stoner-Wohlfarth-Modell (SWM), where magnetic reversal of ellipsoidal particles is assumed to occur by delocalized coherent rotation. However measurements of Ni nanorods show that their coercivity is significantly smaller than predicted by the SWM. There are two possible explanations for this discrepancy: first, a reduced shape anisotropy constant, and second, deviations from the proposed delocalized coherent rotation.The objective of this work was to study the magnetism of Ni nanorods with varying geometry (D=12-22 nm, n>5), in terms of their switching field distribution and shape anisotropy constant.The Ni nanorods were synthesized by current-pulsed electrodeposition of Ni into hexagonally ordered porous alumina templates. The nanorods were released from the templates by dissolution of the alumina in aqueous NaOH and dispersed in gelatine solutions (10 wt% gelatine) at 60 C. Applying an external homogenous magnetic field during gelation enables the preparation of magnetically textured ferrogels with negligible dipolar interaction between the rods.The shape anisotropy constant and SFD's of the nanorods were determined from static magnetization measurements of the uniaxial ferrogels.

  18. Optical fiber magnetic field sensors with peanut-shape structure cascaded with LPFG

    Science.gov (United States)

    Cao, Ye; Zhao, Yue; Tong, Zheng-rong; Wang, Yan

    2016-09-01

    An optical fiber magnetic field sensor for the dual-parameter simultaneous measurement is proposed and demonstrated. The sensor head is constructed by a peanut-shape structure and long period fiber grating (LPFG) coated by magnetic fluid (MF). The external magnetic field intensity can be measured by the variation of characteristic wavelength (Dip1 and Dip2) in interference spectrum since the effective refractive index of MF changes with external magnetic field intensity. When the external magnetic field intensity changes from 0 mT to 20 mT, the magnetic field sensitivities of Dip1 and Dip2 are -0.064 nm/mT and -0.041 nm/mT, respectively. Experimental results show that the temperature sensitivities of the Dip1 and Dip2 are 0.233 nm/°C and 0.186 nm/°C, respectively. Therefore, the simultaneous measurement of the magnetic field intensity and temperature is demonstrated based on the sensitive matrix. It has some potential applications in aerospace, environmental monitoring and medical sensing fields.

  19. An Outflow-shaped Magnetic Field Toward the Class 0 Protostellar Source Serpens SMM1

    Science.gov (United States)

    Hull, Charles; Girart, Josep M.; Tychoniec, Lukasz; Rao, Ramprasad; Cortés, Paulo; Pokhrel, Riwaj; Zhang, Qizhou; Houde, Martin; Dunham, Michael; Kristensen, Lars; Lai, Shih-Ping; Li, Zhi-Yun; Plambeck, Richard

    2018-01-01

    The results from the polarization system at the Atacama Large Millimeter/submillimeter Array (ALMA) have begun both to expand and to confound our understanding of the role of the magnetic field in low-mass star formation. Here we show the highest resolution and highest sensitivity polarization images made to date toward the very young, intermediate-mass Class 0 protostellar source Serpens SMM1, the brightest source in the Serpens Main star-forming region. These ALMA observations achieve ~140 AU resolution, allowing us to probe dust polarization—and thus magnetic field orientation—in the innermost regions surrounding the protostar. By complementing these observations with polarization observations from the Submillimeter Array (SMA) and archival data from the Combined Array for Research in Millimeter-wave Astronomy (CARMA) and the James Clerk Maxwell Telescopes (JCMT), we can compare the magnetic field orientations at different spatial scales. We find major changes in the magnetic field orientation between large (~0.1 pc) scales—where the magnetic field is oriented E–W, perpendicular to the major axis of the dusty filament where SMM1 is embedded—and the intermediate and small scales probed by CARMA (~1000 au resolution), the SMA (~350 au resolution), and ALMA. The ALMA maps reveal that the redshifted lobe of the bipolar outflow is clearly shaping the magnetic field in SMM1 on the southeast side of the source. High-spatial-resolution continuum and spectral-line observations also reveal a tight (~130 au) protobinary system in SMM1-b, the eastern component of which is launching an extremely high-velocity, one-sided jet visible in both CO(2-1) and SiO(5-4); however, that jet does not appear to be shaping the magnetic field. These observations show that with the sensitivity and resolution of ALMA, we can now begin to understand the role that feedback (e.g., from protostellar outflows) plays in shaping the magnetic field in very young, star-forming sources like

  20. LED beam shaping lens based on the near-field illumination.

    Science.gov (United States)

    Joo, Jae Young; Kang, Chang Seog; Park, Soon Sub; Lee, Sun-Kyu

    2009-12-21

    This paper presents a novel method in near-field beam shaping based on the precise optical modeling of a gallium nitride light-emitting diode (GaN LED). A Monte Carlo ray tracing simulation has been utilized to calculate the spatial photon distribution near the LED's top. By analyzing the ray data in near-field, the miniaturized lens profile is created and machined with aspherical surfaces and total internal reflection (TIR) Fresnel facets. The prototype lens reduce the viewing angle of the LED from 150 degrees to 17.5 degrees at full width half maximum (FWHM) while increasing the peak luminous intensity 10 times. The array of proposed lens with CSP LEDs exhibits feasibility of ultra thin uniform illumination in near-field.

  1. Wave shape recovery for terahertz pulse field detection via photoconductive antenna.

    Science.gov (United States)

    Liu, Jinsong; Zou, Si; Yang, Zhengang; Wang, Kejia; Ye, Kefei

    2013-07-01

    For photoconductive (PC) antennae used as terahertz (THz) detectors, traditional data processing methods should be improved because the space-charge and radiation field screening effects and the time dependence of photocarriers density have not been considered. Through developing a double-probe-pulse THz detection technique and using an equivalent-circuit model to describe PC antennae, we present a new method to restore the THz-field wave shape from the measurement data of currents between two electrodes on the antenna. This method is verified to be effective through building a special THz time-domain spectroscopy system with double probes. This work is significant for the accurate determination of pulse THz fields.

  2. SHAPE RESTORATIONS OF OBJECT SURFACE ON POLARIZATION STRUCTURE OF REFLECTED ELECTROMAGNETIC WAVE FIELD

    Directory of Open Access Journals (Sweden)

    2016-01-01

    Full Text Available A problem of electromagnetic wave backscattering on a chosen 3D object is solved. A differential equation which is linked change of polarization coefficient of reflected wave with variation of matrix elements of object scattering is ob- tained. Obtained relation enables to develop algorithms of fast numerical solution of inverse problem of scattering on this object that is determination of complex function of object surface scattering and restoration of unknown object shape on phase distribution of reflected wave. The method uses ray representation of scattering fields based on principle Huygens- Fresnel. The algorithm of object shape restoration on phase of reflected wave allows to restore not only smooth surfaces, but also object surfaces with smaller roughness than a wave length.

  3. Localized X-shaped field generated by a superluminal electric charge.

    Science.gov (United States)

    Recami, Erasmo; Zamboni-Rached, Michel; Dartora, César A

    2004-02-01

    It is now well known that Maxwell equations admit of wavelet-type solutions endowed with arbitrary group velocities (0< v(g)< infinity). Some of them, which are rigidly moving and have been called localized solutions, attracted large attention. In particular, much work has been done with regard to the superluminal localized solutions (SLSs), the most interesting of which are the "X-shaped" ones. The SLSs have been actually produced in a number of experiments, always by suitable interference of ordinary-speed waves. In this paper we show, by contrast, that even a superluminal charge creates an electromagnetic X-shaped wave: namely, on the basis of Maxwell equations, we are able to evaluate the field associated with a superluminal charge (under the approximation of pointlikeness): it results in constituting a very simple example of a true X wave.

  4. Shape from specular reflection in calibrated environments and the integration of spatial normal fields

    KAUST Repository

    Balzer, Jonathan

    2011-09-01

    Reflections of a scene in a mirror surface contain information on its shape. This information is accessible by measurement through an optical metrology technique called deflectometry. The result is a field of normal vectors to the unknown surface having the remarkable property that it equally changes in all spatial directions, unlike normal maps occurring, e.g., in Shape from Shading. Its integration into a zero-order reconstruction of the surface thus deserves special attention. We develop a novel algorithm for this purpose which is relatively straightforward to implement yet outperforms existing ones in terms of efficiency and robustness. Experimental results on synthetic and real data complement the theoretical discussion. © 2011 IEEE.

  5. Shaping markets : A neoinstitutional analysis of the emerging organizational field of renewable energy in China

    Energy Technology Data Exchange (ETDEWEB)

    Hoeyrup Christensen, N.

    2013-02-01

    Today, China is the world leading investor in renewable energy. At the heart of this effort lies China's ability to shape markets through industrial policies. Through a neoinstitutional theoretical perspective this dissertation views China's efforts within renewable energy as the emergence of a new organizational field. Despite the importance of organizational fields as a key concept in the neoinstitutional literature, there is a lack of studies on exactly how they emerge. Throughout four articles this dissertation scrutinizes therefore the emergence of the field of renewable energy in China and the mechanisms driving this emergence. Firstly, the relation between state and market is examined, and it is argued that Chinese state interventions in markets, for instance through subsidies, are based in deeply rooted historic grounds. Thus, the article explains the general context in which the Party-state handles subsidized markets, like renewable energy. Secondly, the specific development of the idea of sustainable development, and how it evolves into an institutional logic of its own, is analysed. It is around this institutional logic that renewable energy emerges as a field. The key mechanism in play is the idea work of the Party state by which sustainable development is positioned in the Partystate discourse. Thirdly, subsidization of renewable energy in China is examined as an important feature of the increasing institutionalization of the organizational field. It is shown how negotiation between companies and Party-state is the vital mechanism by which subsidies are determined. Fourthly, it is analysed how the institutional entrepreneurship of one single company resulted in an official recognition of biomass power production as a source of renewable energy, and thereby an expansion of the organizational field. Again, the main mechanism was the company's idea work, through which a crucial link between biomass and sustainable development was

  6. Effect of initial void shape on ductile failure in a shear field

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    2015-01-01

    For voids in a shear field unit cell model analyses have been used to show that ductile failure is predicted even though the stress triaxiality is low or perhaps negative, so that the void volume fraction does not grow during deformation. Here, the effect of the void shape is studied by analyzing...... with circular cross-section, i.e. the voids in shear flatten out to micro-cracks, which rotate and elongate until interaction with neighboring micro-cracks gives coalescence. Even though the mechanism of ductile failure is the same, the load carrying capacity predicted, for the same initial void volume fraction...

  7. A Gauss-Newton method for the integration of spatial normal fields in shape Space

    KAUST Repository

    Balzer, Jonathan

    2011-08-09

    We address the task of adjusting a surface to a vector field of desired surface normals in space. The described method is entirely geometric in the sense, that it does not depend on a particular parametrization of the surface in question. It amounts to solving a nonlinear least-squares problem in shape space. Previously, the corresponding minimization has been performed by gradient descent, which suffers from slow convergence and susceptibility to local minima. Newton-type methods, although significantly more robust and efficient, have not been attempted as they require second-order Hadamard differentials. These are difficult to compute for the problem of interest and in general fail to be positive-definite symmetric. We propose a novel approximation of the shape Hessian, which is not only rigorously justified but also leads to excellent numerical performance of the actual optimization. Moreover, a remarkable connection to Sobolev flows is exposed. Three other established algorithms from image and geometry processing turn out to be special cases of ours. Our numerical implementation founds on a fast finite-elements formulation on the minimizing sequence of triangulated shapes. A series of examples from a wide range of different applications is discussed to underline flexibility and efficiency of the approach. © 2011 Springer Science+Business Media, LLC.

  8. Characterization of the acoustic field generated by a horn shaped ultrasonic transducer

    Energy Technology Data Exchange (ETDEWEB)

    Hu, B.; Lerch, J. E.; Chavan, A. H.; Weber, J. K. R.; Tamalonis, A.; Suthar, K. J.; DiChiara, A. D.

    2017-09-04

    A horn shaped Langevin ultrasonic transducer used in a single axis levitator was characterized to better understand the role of the acoustic profile in establishing stable traps. The method of characterization included acoustic beam profiling performed by raster scanning an ultrasonic microphone as well as finite element analysis of the horn and its interface with the surrounding air volume. The results of the model are in good agreement with measurements and demonstrate the validity of the approach for both near and far field analyses. Our results show that this style of transducer produces a strong acoustic beam with a total divergence angle of 10 degree, a near-field point close to the transducer surface and a virtual sound source. These are desirable characteristics for a sound source used for acoustic trapping experiments

  9. Characterization of the acoustic field generated by a horn shaped ultrasonic transducer

    Science.gov (United States)

    Hu, B.; Lerch, J. E.; Chavan, A. H.; Weber, J. K. R.; Tamalonis, A.; Suthar, K. J.; DiChiara, A. D.

    2017-09-01

    A horn shaped Langevin ultrasonic transducer used in a single axis levitator was characterized to better understand the role of the acoustic profile in establishing stable traps. The method of characterization included acoustic beam profiling performed by raster scanning an ultrasonic microphone as well as finite element analysis of the horn and its interface with the surrounding air volume. The results of the model are in good agreement with measurements and demonstrate the validity of the approach for both near and far field analyses. Our results show that this style of transducer produces a strong acoustic beam with a total divergence angle of 10°, a near-field point close to the transducer surface and a virtual sound source. These are desirable characteristics for a sound source used for acoustic trapping experiments.

  10. On the importance of electrode parameters for shaping electric field patterns generated by tDCS

    DEFF Research Database (Denmark)

    B. Saturnino, Guilherme; Antunes, André; Thielscher, Axel

    2015-01-01

    Transcranial direct current stimulation (tDCS) uses electrode pads placed on the head to deliver weak direct current to the brain and modulate neuronal excitability. The effects depend on the intensity and spatial distribution of the electric field. This in turn depends on the geometry and electric...... properties of the head tissues and electrode pads. Previous numerical studies focused on providing a reasonable level of detail of the head anatomy, often using simplified electrode models. Here, we explore via finite element method (FEM) simulations based on a high-resolution head model how detailed...... electrode modeling influences the calculated electric field in the brain. We take into account electrode shape, size, connector position and conductivities of different electrode materials (including saline solutions and electrode gels). These factors are systematically characterized to demonstrate...

  11. Parametric Study of the Scattered Electromagnetic Field by Differently-Shaped Buried Objects in Various Scenarios

    Science.gov (United States)

    Stoja, Endri; Hoxha, Julian; Domnori, Elton; Pajewski, Lara; Frezza, Fabrizio

    2017-04-01

    In this study the electromagnetic field scattered by a buried object is obtained by use of a commercial full-wave frequency-domain solver which implements the Finite Element Method (FEM). The buried object is supposed to have different simple shapes and material composition such as a cylinder or cylindrical shell modelling for example a void in concrete or a poly-vinyl chloride (PVC) pipeline, respectively. Material properties available in literature are correctly modelled by data interpolation. The model is excited by a linearly-polarized plane wave impinging normally on the interface between air and soil/cement half-space. Comparison with simulation data provided by another simulator implementing the finite-difference time domain (FDTD) technique in the case of a simple buried perfect electric cylinder allows for FEM data validation. We further study the properties and the spatial variation of the scattered fields in different contexts by varying the geometrical and material properties of the model relative to the impinging wave characteristics. The aim is to clearly determine the conditions under which detection is possible. Moreover, by application of signal processing techniques to scattered field data, the position, shape, and object orientation recognition problems are considered. Results from different DSP algorithms are compared with the goal to find the best performing one relative to the context. Performance is evaluated in terms of detection success and resolving ability. The use of ground penetrating radar (GPR) techniques in the field of Civil Engineering offers inspection capabilities in the structure with no destructive intervention. Acknowledgement This abstract is a contribution to COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar", www.GPRadar.eu, www.cost.eu.

  12. Computation of Electromagnetic Fields Scattered From Dielectric Objects of Uncertain Shapes Using MLMC

    KAUST Repository

    Litvinenko, Alexander

    2015-01-07

    Simulators capable of computing scattered fields from objects of uncertain shapes are highly useful in electromagnetics and photonics, where device designs are typically subject to fabrication tolerances. Knowledge of statistical variations in scattered fields is useful in ensuring error-free functioning of devices. Oftentimes such simulators use a Monte Carlo (MC) scheme to sample the random domain, where the variables parameterize the uncertainties in the geometry. At each sample, which corresponds to a realization of the geometry, a deterministic electromagnetic solver is executed to compute the scattered fields. However, to obtain accurate statistics of the scattered fields, the number of MC samples has to be large. This significantly increases the total execution time. In this work, to address this challenge, the Multilevel MC (MLMC [1]) scheme is used together with a (deterministic) surface integral equation solver. The MLMC achieves a higher efficiency by “balancing” the statistical errors due to sampling of the random domain and the numerical errors due to discretization of the geometry at each of these samples. Error balancing results in a smaller number of samples requiring coarser discretizations. Consequently, total execution time is significantly shortened.

  13. Computation of Electromagnetic Fields Scattered From Dielectric Objects of Uncertain Shapes Using MLMC Center for Uncertainty

    KAUST Repository

    Litvinenko, Alexander

    2015-01-05

    Simulators capable of computing scattered fields from objects of uncertain shapes are highly useful in electromagnetics and photonics, where device designs are typically subject to fabrication tolerances. Knowledge of statistical variations in scattered fields is useful in ensuring error-free functioning of devices. Oftentimes such simulators use a Monte Carlo (MC) scheme to sample the random domain, where the variables parameterize the uncertainties in the geometry. At each sample, which corresponds to a realization of the geometry, a deterministic electromagnetic solver is executed to compute the scattered fields. However, to obtain accurate statistics of the scattered fields, the number of MC samples has to be large. This significantly increases the total execution time. In this work, to address this challenge, the Multilevel MC (MLMC) scheme is used together with a (deterministic) surface integral equation solver. The MLMC achieves a higher efficiency by “balancing” the statistical errors due to sampling of the random domain and the numerical errors due to discretization of the geometry at each of these samples. Error balancing results in a smaller number of samples requiring coarser discretizations. Consequently, total execution time is significantly shortened.

  14. Computation of Electromagnetic Fields Scattered From Dielectric Objects of Uncertain Shapes Using MLMC

    KAUST Repository

    Litvinenko, Alexander

    2016-01-06

    Simulators capable of computing scattered fields from objects of uncertain shapes are highly useful in electromagnetics and photonics, where device designs are typically subject to fabrication tolerances. Knowledge of statistical variations in scattered fields is useful in ensuring error-free functioning of devices. Oftentimes such simulators use a Monte Carlo (MC) scheme to sample the random domain, where the variables parameterize the uncertainties in the geometry. At each sample, which corresponds to a realization of the geometry, a deterministic electromagnetic solver is executed to compute the scattered fields. However, to obtain accurate statistics of the scattered fields, the number of MC samples has to be large. This significantly increases the total execution time. In this work, to address this challenge, the Multilevel MC (MLMC [1]) scheme is used together with a (deterministic) surface integral equation solver. The MLMC achieves a higher efficiency by balancing the statistical errors due to sampling of the random domain and the numerical errors due to discretization of the geometry at each of these samples. Error balancing results in a smaller number of samples requiring coarser discretizations. Consequently, total execution time is significantly shortened.

  15. Electromagnetic field enhancement and spectrum shaping through plasmonically integrated optical vortices.

    Science.gov (United States)

    Ahn, Wonmi; Boriskina, Svetlana V; Hong, Yan; Reinhard, Björn M

    2012-01-11

    We introduce a new design approach for surface-enhanced Raman spectroscopy (SERS) substrates that is based on molding the optical powerflow through a sequence of coupled nanoscale optical vortices "pinned" to rationally designed plasmonic nanostructures, referred to as Vortex Nanogear Transmissions (VNTs). We fabricated VNTs composed of Au nanodiscs by electron beam lithography on quartz substrates and characterized their near- and far-field responses through combination of computational electromagnetism, and elastic and inelastic scattering spectroscopy. Pronounced dips in the far-field scattering spectra of VNTs provide experimental evidence for an efficient light trapping and circulation within the nanostructures. Furthermore, we demonstrate that VNT integration into periodic arrays of Au nanoparticles facilitates the generation of high E-field enhancements in the VNTs at multiple defined wavelengths. We show that spectrum shaping in nested VNT structures is achieved through an electromagnetic feed-mechanism driven by the coherent multiple scattering in the plasmonic arrays and that this process can be rationally controlled by tuning the array period. The ability to generate high E-field enhancements at predefined locations and frequencies makes nested VNTs interesting substrates for challenging SERS applications. © 2011 American Chemical Society

  16. Elastic fields in two imperfectly bonded half-planes with a thermal inclusion of arbitrary shape

    Science.gov (United States)

    Wang, X.; Sudak, L. J.; Ru, C. Q.

    2007-05-01

    A general method is presented for the rigorous solution of Eshelby’s problem concerned with an arbitrary shaped inclusion embedded within one of two dissimilar elastic half-planes in plane elasticity. The bonding between the half-planes is considered to be imperfect with the assumption that the interface imperfections are uniform. Using analytic continuation, the basic boundary value problem is reduced to a set of two coupled nonhomogeneous first-order differential equations for two analytic functions defined in the lower half-plane which is free of the thermal inclusion. Using diagonalization, the two coupled differential equations are decoupled into two independent nonhomogeneous first-order differential equations for two newly defined analytic functions. The resulting closed-form solutions are given in terms of the constant imperfect interface parameters and the auxiliary function constructed from the conformal mapping which maps the exterior of the inclusion onto the exterior of the unit circle. The method is illustrated using several examples of an imperfect interface. In particular, when the same degree of imperfection is realized in both the normal and tangential directions between the two half-planes, a thermal inclusion of arbitrary shape in the upper half-plane does not cause any mean stress to develop in the lower half-plane. Alternatively, when the imperfect interface parameters are not equal, then a nonzero mean stress will be induced in the lower half-plane by the thermal inclusion of arbitrary shape in the upper half-plane. Detailed results are presented for the mean stress and the interfacial normal and shear stresses caused by a circular and elliptical thermal inclusion, respectively. Results from these calculations reveal that the imperfect bonding condition has a significant effect on the internal stress field induced within the inclusion as well as on the interfacial normal and shear stresses existing between the two half-planes especially

  17. On the importance of electrode parameters for shaping electric field patterns generated by tDCS.

    Science.gov (United States)

    Saturnino, Guilherme B; Antunes, André; Thielscher, Axel

    2015-10-15

    Transcranial direct current stimulation (tDCS) uses electrode pads placed on the head to deliver weak direct current to the brain and modulate neuronal excitability. The effects depend on the intensity and spatial distribution of the electric field. This in turn depends on the geometry and electric properties of the head tissues and electrode pads. Previous numerical studies focused on providing a reasonable level of detail of the head anatomy, often using simplified electrode models. Here, we explore via finite element method (FEM) simulations based on a high-resolution head model how detailed electrode modeling influences the calculated electric field in the brain. We take into account electrode shape, size, connector position and conductivities of different electrode materials (including saline solutions and electrode gels). These factors are systematically characterized to demonstrate their impact on the field distribution in the brain. The goals are to assess the effect of simplified electrode models; and to develop practical rules-of-thumb to achieve a stronger stimulation of the targeted brain regions underneath the electrode pads. We show that for standard rectangular electrode pads, lower saline and gel conductivities result in more homogeneous fields in the region of interest (ROI). Placing the connector at the center of the electrode pad or farthest from the second electrode substantially increases the field strength in the ROI. Our results highlight the importance of detailed electrode modeling and of having an adequate selection of electrode pads/gels in experiments. We also advise for a more detailed reporting of the electrode montages when conducting tDCS experiments, as different configurations significantly affect the results. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. A Multi-layered Model for the Shape, Zonal Winds and Gravitational Field of Jupiter

    Science.gov (United States)

    Schubert, G.; Zhang, K.; Kong, D.

    2016-12-01

    We have developed a three-dimensional, finite-element, multi-layered, non-spheroidal model of Jupiter consisting of an inner core, a metallic dynamo region and an outer molecular electrically insulating envelope. Different polytropic equations of state are used in the metallic and molecular regions. The zonal winds are on cylinders parallel to the rotation axis and are confined within the molecular envelope by magnetic braking. The effect of rotational distortion is fully accounted for; it is not treated as simply a small perturbation on a spherically symmetric state. The model determines the density, size and shape of the inner core, the irregular shape of the 1-bar pressure level, and the internal structure of Jupiter. It produces the known mass, the known equatorial and polar radii, and the known zonal gravitational coefficient J2 of Jupiter within their error bars; it also yields the coefficients J4 and J6 with an accuracy of a few percent. The variation of the gravitational field caused solely by the effect of the zonal winds on the rotationally distorted Jupiter is also determined. Different cases, ranging from a deep wind profile to a very shallow profile, are considered. The model enables accurate interpretation of the zonal gravitational coefficients expected from the Juno mission.

  19. Shape and Topology Optimization in Stokes Flow with a Phase Field Approach

    Energy Technology Data Exchange (ETDEWEB)

    Garcke, Harald, E-mail: harald.garcke@mathematik.uni-regensburg.de; Hecht, Claudia, E-mail: claudia.hecht@mathematik.uni-regensburg.de [Universität Regensburg, Fakultät für Mathematik (Germany)

    2016-02-15

    In this paper we introduce a new formulation for shape optimization problems in fluids in a diffuse interface setting that can in particular handle topological changes. By adding the Ginzburg–Landau energy as a regularization to the objective functional and relaxing the non-permeability outside the fluid region by introducing a porous medium approach we hence obtain a phase field problem where the existence of a minimizer can be guaranteed. This problem is additionally related to a sharp interface problem, where the permeability of the non-fluid region is zero. In both the sharp and the diffuse interface setting we can derive necessary optimality conditions using only the natural regularity of the minimizers. We also pass to the limit in the first order conditions.

  20. Optimization of multi-tip-shaped field emitters with bilayer protective coatings

    Science.gov (United States)

    Sominskii, G. G.; Taradaev, E. P.

    2017-06-01

    The calculations needed to optimize the ordered multi-tip-shaped silicon field emitters with the two-layer protective metal-fullerene coatings intended for use in high voltage electronic devices operating in technical vacuum have been performed. The calculations are fulfilled using the COMSOL program. The influence of the morphology of the surface on the emission characteristics of the emitters is determined, including the needles height and radius of their vertices, and also the distance between needles. It has been shown that the emitters with an area of 0.2 cm2, operating under the conditions of partial mutual screening, can provide currents of several hundred milliamps for fairly high voltages.

  1. Experimental approach to shape field relevant blast wave profiles in compressed gas-driven shock tube

    Directory of Open Access Journals (Sweden)

    Aravind eSundaramurthy

    2014-12-01

    Full Text Available Detonation of a high explosive produces shock-blast wave, shrapnel, and gaseous products. While direct exposure to blast is a concern near the epicenter, shock-blast can affect subjects even at farther distances, which is termed as primary blast injury, which is the theme of this work. The shock-blast profile is characterized with blast overpressure, positive time duration, and impulse as shock-blast wave parameters (SWPs. These parameters in turn are a function of field factors, such as the strength of high explosive and the distance of the human subjects from the epicenter. The shape and magnitude of the profile determine the severity of injury to the subjects. As shown in some of our recent works (Chandra et al., 2011;Sundaramurthy et al., 2012;Skotak et al., 2013, the profile not only determines the survival of the animal but also the acute and chronic biomechanical injuries along with the following bio-chemical sequelae. It is extremely important to carefully design and operate the shock tube to produce field relevant SWPs. Furthermore, it is vital to identify and eliminate the artifacts that are inadvertently introduced in the shock-blast profile that may affect the results. In this work, we examine the relationship between shock tube adjustable parameters (SAPs and SWPs that can be used to control the blast profile; the results can be easily applied to many of the laboratory shock tubes. Further, exact replication of shock profile (magnitude and shape can be related to field explosions and can be a standard in comparing results across different laboratories. 40 experiments are carried out by judiciously varying SAPs such as membrane thickness, breech length (66.68 to 1209.68 mm, measurement location, and type of driver gas (nitrogen, helium. The relationships between SAPs and the resulting shock-blast profiles are characterized. Finally, shock-blast profiles of a TNT explosion from ConWep software is compared with the profiles obtained

  2. Study of shape evaluation for mask and silicon using large field of view

    Science.gov (United States)

    Matsuoka, Ryoichi; Mito, Hiroaki; Shinoda, Shinichi; Toyoda, Yasutaka

    2010-09-01

    We have developed a highly integrated method of mask and silicon metrology. The aim of this integration is evaluating the performance of the silicon corresponding to Hotspot on a mask. It can use the mask shape of a large field, besides. The method adopts a metrology management system based on DBM (Design Based Metrology). This is the high accurate contouring created by an edge detection algorithm used in mask CD-SEM and silicon CD-SEM. Currently, as semiconductor manufacture moves towards even smaller feature size, this necessitates more aggressive optical proximity correction (OPC) to drive the super-resolution technology (RET). In other words, there is a trade-off between highly precise RET and mask manufacture, and this has a big impact on the semiconductor market that centers on the mask business. As an optimal solution to these issues, we provide a DFM solution that extracts 2-dimensional data for a more realistic and error-free simulation by reproducing accurately the contour of the actual mask, in addition to the simulation results from the mask data. On the other hand, there is roughness in the silicon form made from a mass-production line. Moreover, there is variation in the silicon form. For this reason, quantification of silicon form is important, in order to estimate the performance of a pattern. In order to quantify, the same form is equalized in two dimensions. And the method of evaluating based on the form is popular. In this study, we conducted experiments for averaging method of the pattern (Measurement Based Contouring) as two-dimensional mask and silicon evaluation technique. That is, observation of the identical position of a mask and a silicon was considered. The result proved its detection accuracy and reliability of variability on two-dimensional pattern (mask and silicon) and is adaptable to following fields of mask quality management. •Discrimination of nuisance defects for fine pattern. •Determination of two-dimensional variability of

  3. Shape effect on the second order nonlinear optical properties in triangular quantum dots with applied electric field

    Science.gov (United States)

    Li, Keyin; Guo, Kangxian; Liang, Litao

    2017-11-01

    The shape effect of triangular quantum dots (TQDs) on the second-harmonic generations (SHG) coefficient and the optical rectification (OR) coefficient with the applied electric field has been theoretically investigated, by using the compact-density-matrix approach and iterative method. Within the effective-mass approximation, the energy levels and the wave functions of the system are obtained. The results show that both the strength of external electric field and the shape of triangular quantum dots have a significant influence on the second-harmonic generations and the optical rectification.

  4. Effect of common building materials in narrow shaped X-ray fields transmission

    Science.gov (United States)

    Vlachos, I.; Tsantilas, X.; Fountos, G.; Delis, H.; Kandarakis, I.; Panayiotakis, G.

    2015-09-01

    Diagnostic and interventional radiology, are an essential part of present day medical practice. Advances in X-ray imaging technology, together with developments in digital imaging have had a significant impact on the practice of radiology. This includes improvement in image quality, reduction in dose and a broader range of available applications resulting to better patient diagnosis and treatment. X-rays have the potential for damaging healthy cells and tissues, therefore all medical procedures employing X-ray equipment must be carefully managed. In all facilities and for all equipment types, procedures must be in place in order to ensure that exposures to patients, staff and the public are kept as low as reasonably achievable. Commonly used construction materials such as, ceramic tiles and plasterboards can provide a certain degree of protection against X-radiation. In this study, the secondary radiation transmission through common building materials is investigated, in the case of narrow shaped X-ray fields. Double plasterboard and double reinforced in thickness ceramic tile provided better radiation protection results.

  5. Quantification of lacrimal function after D-shaped field irradiation for retinoblastoma

    Energy Technology Data Exchange (ETDEWEB)

    Imhof, S.M.; Tan, K.E.W.P. (Free Univ. Hospital, Amsterdam (Netherlands). Dept. of Ophthalmology); Hofman, P. (Utrecht Univ. Hospital (Netherlands). Dept. of Radiotherapy)

    1993-08-01

    To study the quantitative effects of mega-voltage external beam irradiation in a D-shaped field in patients with retinoblastoma, biomicroscopy was performed in 61 patients and tear function tests (Schirmer-lactoferrin and lysozyme tests) on 45 eyes in 34 irradiated patients. The results were compared with those obtained in 25 non-irradiated control eyes. The Schirmer test was significantly diminished in irradiated eyes, as were the lactoferrin and lysozyme values. A mild to severe keratitis was found in 17 of the 61 patients (28%). A significant correlation (p<0.005) was found between the severe keratitis and the mean Schirmer values; the mean lactoferrin and lysozyme values were diminished in all patients but did not correlate significantly with the corneal abnormalities. These quantitative data, obtained in patients treated for retinoblastoma, affirm the qualitative data found in patients irradiated for other reasons such as orbital or sinus tumours. Irradiation for retinoblastoma is not a harmless treatment and serious late side effects have to be considered. (Author).

  6. A field study investigating effects of landmarks on territory size and shape.

    Science.gov (United States)

    Suriyampola, Piyumika S; Eason, Perri K

    2014-01-01

    Few studies have examined how landmarks affect territories' fundamental characteristics. In this field study, we investigated effects of landmarks on territory size, shape and location in a cichlid fish (Amatitlania siquia). We provided cans as breeding sites and used plastic plants as landmarks. During 10 min trials, we recorded locations where residents chased intruders and used those locations to outline and measure the territory. In two experiments, we observed pairs without landmarks and with either a point landmark (one plant) or linear landmark (four plants) placed near the nest can. We alternated which trial occurred first and performed the second trial 24 h after the first. Territories were approximately round without landmarks or with a point landmark but were significantly more elongated when we added a linear landmark. Without landmarks, nests were centrally located; however, with any landmark, pairs set territory boundaries closer to the landmark and thus the nest. Territory size was significantly reduced in the presence of any landmark. This reduction suggests that a smaller territory with well-defined boundaries has greater benefits than a larger territory with less well-defined borders.

  7. Radiofrequency electric field hyperthermia with gold nanostructures: role of particle shape and surface chemistry.

    Science.gov (United States)

    Amini, Seyed Mohammad; Kharrazi, Sharmin; Rezayat, Seyed Mahdi; Gilani, Kambiz

    2017-09-10

    Hyperthermia treatment of cancerous cells has been recently developed drastically with the help of nanostructures. Heating of gold nanoparticles in non-invasive radiofrequency electric field (RF-EF) is a promising and unique technique for cancer hyperthermia. However, because of differences between particles (i.e. their surface chemistry and dispersion medium) and between RF-EF sources, the research community has not reached a consensus yet. Here, we report the results of investigations on heating of gold nanoparticles and gold nanorods under RF-EF and feasibility of in-vitro cancer hyperthermia. The heating experiments were performed to investigate the role of particle shape and surface chemistry (CTAB, citrate and PEG molecules). In-vitro hyperthermia was performed on human pancreatic cancer cell (MIA Paca-2) with PEG-coated GNPs and GNRs at concentrations that were found non-toxic based on the results of cytotoxicity assay. Application of RF-EF on cells treated with PEG-GNPs and PEG-GNRs proved highly effective in killing cells.

  8. Experimental realization of crossover in shape and director field of nematic tactoids

    NARCIS (Netherlands)

    Jamali, Vida; Behabtu, Natnael; Senyuk, Bohdan; Lee, J. Alex; Smalyukh, Ivan I.; van der Schoot, Paul; Pasquali, Matteo

    2015-01-01

    Spindle-shaped nematic droplets (tactoids) form in solutions of rod-like molecules at the onset of the liquid crystalline phase. Their unique shape and internal structure result from the interplay of the elastic deformation of the nematic and anisotropic surface forces. The balance of these forces

  9. Influence of nonuniform external magnetic fields and anode--cathode shaping on magnetic insulation in coaxial transmission lines

    Energy Technology Data Exchange (ETDEWEB)

    Mostrom, M.A.

    1979-01-01

    Coaxial transmission lines, used to transfer the high voltage pulse into the diode region of a relativistic electron beam generator, have been studied using the two-dimensional time-dependent fully relativistic and electromagnetic particle simulation code CCUBE. A simple theory of magnetic insulation that agrees well with simulation results for a straight cylindrical coax in a uniform external magnetic field is used to interpret the effects of anode--cathode shaping and nonuniform external magnetic fields. Loss of magnetic insulation appears to be minimized by satisfying two conditions: (1) the cathode surface should follow a flux surface of the external magnetic field; (2) the anode should then be shaped to insure that the magnetic insulation impedance, including transients, is always greater than the effective load impedance wherever there is an electron flow in the anode--cathode gap.

  10. Shape effects of GeSbTe nanodots on the near-field interaction with a silver triangle antenna

    Science.gov (United States)

    Kojima, Naoto; Ota, Norio; Asakawa, Kiyoshi; Shiraishi, Kenji; Yamada, Keisaku

    2015-04-01

    We investigated the shape effects of GeSbTe nanodots on the near-field interaction with a silver triangle antenna using the three-dimensional finite-difference time-domain method, avoiding the difficulty of detecting near-field signals from a single dot that occurs in current measurements. The surface plasmon resonance of silver strengthens the near-field around nanodots made of GeSbTe, commonly used in phase-change recording. Using GeSbTe spheres and pillar dots with various top plane shapes, we investigated the relationship between the inner electric field concentration of GeSbTe nanodots and the radius of curvature of the corners facing the antenna tip. Reducing the radius of curvature strengthens the inner electric field of the dots, enhancing the near-field difference in intensity for the GeSbTe phase change. GeSbTe diamond pillars with a radius of curvature of 1 nm exhibit a near-field difference in intensity of 28% for the phase change. Using the antenna and the GeSbTe nanodot array, optical write-once recording is realized. The preliminary research in this study is expected to realize future optical disk storage using GeSbTe nanodots with diameters below 10 nm.

  11. Nudging children towards whole wheat bread: a field experiment on the influence of fun bread roll shape on breakfast consumption.

    Science.gov (United States)

    van Kleef, Ellen; Vrijhof, Milou; Polet, Ilse A; Vingerhoeds, Monique H; de Wijk, René A

    2014-09-02

    Many children do not eat enough whole grains, which may have negative health consequences. Intervention research is increasingly focusing on nudging as a way to influence food choices by affecting unconscious behavioural processes. The aim of this field study was to examine whether the shape of bread rolls is able to shift children's bread choices from white to whole wheat during breakfast to increase whole grain intake. In a between-subjects experiment conducted at twelve primary schools in the Netherlands, with school as the unit of condition assignment, children were exposed to an assortment of white and whole wheat bread rolls, both varying in shape (regular versus fun). Children were free to choose the type and number of bread rolls and toppings to eat during breakfast. Consumption of bread rolls was measured at class level via the number of bread rolls before and after breakfast. In addition, children (N = 1113) responded to a survey including questions about the breakfast. Results of the field experiment showed that about 76% of bread consumption consisted of white bread rolls. Consumption of white bread rolls did not differ according to shape (all P-values > 0.18). However, presenting fun-shaped whole wheat bread rolls almost doubled consumption of whole wheat bread (P = 0.001), particularly when the simultaneously presented white bread rolls had a regular shape (interaction P = 0.02). Survey results suggest that slight increases in perceived pleasure and taste are associated with these effects. Overall, presenting whole wheat bread in fun shapes may be helpful in increasing consumption of whole wheat bread in children. Future research could examine how improving the visual appeal of healthy foods may lead to sustained behaviour changes.

  12. PERIODIC ORBIT FAMILIES IN THE GRAVITATIONAL FIELD OF IRREGULAR-SHAPED BODIES

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Yu [State Key Laboratory of Astronautic Dynamics, Xi’an Satellite Control Center, Xi’an 710043 (China); Baoyin, Hexi, E-mail: jiangyu_xian_china@163.com [School of Aerospace Engineering, Tsinghua University, Beijing 100084 (China)

    2016-11-01

    The discovery of binary and triple asteroids in addition to the execution of space missions to minor celestial bodies in the past several years have focused increasing attention on periodic orbits around irregular-shaped celestial bodies. In the present work, we adopt a polyhedron shape model for providing an accurate representation of irregular-shaped bodies and employ the model to calculate their corresponding gravitational and effective potentials. We also investigate the characteristics of periodic orbit families and the continuation of periodic orbits. We prove a fact, which provides a conserved quantity that permits restricting the number of periodic orbits in a fixed energy curved surface about an irregular-shaped body. The collisions of Floquet multipliers are maintained during the continuation of periodic orbits around the comet 1P/Halley. Multiple bifurcations in the periodic orbit families about irregular-shaped bodies are also discussed. Three bifurcations in the periodic orbit family have been found around the asteroid 216 Kleopatra, which include two real saddle bifurcations and one period-doubling bifurcation.

  13. Depolarized light scattering from prolate anisotropic particles: The influence of the particle shape on the field autocorrelation function.

    Science.gov (United States)

    Passow, Christopher; ten Hagen, Borge; Löwen, Hartmut; Wagner, Joachim

    2015-07-28

    We provide a theoretical analysis for the intermediate scattering function typically measured in depolarized dynamic light scattering experiments. We calculate the field autocorrelation function g1(VH)(Q,t) in dependence on the wave vector Q and the time t explicitly in a vertical-horizontal scattering geometry for differently shaped solids of revolution. The shape of prolate cylinders, spherocylinders, spindles, and double cones with variable aspect ratio is expanded in rotational invariants flm(r). By Fourier transform of these expansion coefficients, a formal multipole expansion of the scattering function is obtained, which is used to calculate the weighting coefficients appearing in the depolarized scattering function. In addition to translational and rotational diffusion, especially the translational-rotational coupling of shape-anisotropic objects is considered. From the short-time behavior of the intermediate scattering function, the first cumulants Γ(Q) are calculated. In a depolarized scattering experiment, they deviate from the simple proportionality to Q(2). The coefficients flm(Q) strongly depend on the geometry and aspect ratio of the particles. The time dependence, in addition, is governed by the translational and rotational diffusion tensors, which are calculated by means of bead models for differently shaped particles in dependence on their aspect ratio. Therefore, our analysis shows how details of the particle shape--beyond their aspect ratio--can be determined by a precise scattering experiment. This is of high relevance in understanding smart materials which involve suspensions of anisotropic colloidal particles.

  14. Assessing Shape Characteristics of Jupiter Trojans in the Kepler Campaign 6 Field

    Science.gov (United States)

    Sharkey, Benjamin; Ryan, Erin L.; Woodward, Charles E.

    2017-10-01

    We report estimates of spin pole orientations and body-centric axis ratios of nine Jupiter Trojan asteroids through convex shape models derived from Kepler K2 photometry. Our sample contains single-component as well as candidate binary systems (identified through lightcurve features). Photometric baselines on the targets covered 7 to 93 full rotation periods. By incorporating a bias against highly elongated physical shapes, spin vector orientations of single-component systems were constrained to several discrete regions. Single-component convex models failed to converge on two binary candidates while two others demonstrated pronounced tapering that may be consistent with concavities of contact binaries. Further work to create two-component models is likely necessary to constrain the candidate binary targets. We find that Kepler K2 photometry provides robust datasets capable of providing detailed information on physical shape parameters of Jupiter Trojans.

  15. Individual differences in visual field shape modulate the effects of attention on the lower visual field advantage in crowding.

    Science.gov (United States)

    Fortenbaugh, Francesca C; Silver, Michael A; Robertson, Lynn C

    2015-02-12

    It has previously been reported that visual crowding of a target by flankers is stronger in the upper visual field than in the lower, and this finding has been attributed to greater attentional resolution in the lower hemifield (He, Cavanagh, & Intriligator, 1996). Here we show that the upper/lower asymmetry in visual crowding can be explained by natural variations in the borders of each individual's visual field. Specifically, asymmetry in crowding along the vertical meridian can be almost entirely accounted for by replacing the conventional definition of visual field location, in units of degrees of visual angle, with a definition based on the ratio of the extents of an individual's upper and lower visual field. We also show that the upper/lower crowding asymmetry is eliminated when stimulus eccentricity is expressed in units of percentage of visual field extent but is present when the conventional measure of visual angle is used. We further demonstrate that the relationship between visual field extent and perceptual asymmetry is most evident when participants are able to focus their attention on the target location. These results reveal important influences of visual field boundaries on visual perception, even for visual field locations far from those boundaries. © 2015 ARVO.

  16. Analysis of the modulation mechanisms of the electric field and breakdown performance in AlGaN/GaN HEMT with a T-shaped field-plate

    Science.gov (United States)

    Mao, Wei; Fan, Ju-Sheng; Du, Ming; Zhang, Jin-Feng; Zheng, Xue-Feng; Wang, Chong; Ma, Xiao-Hua; Zhang, Jin-Cheng; Hao, Yue

    2016-12-01

    A novel AlGaN/GaN high electron mobility transistor (HEMT) with a source-connected T-shaped field-plate (ST-FP HEMT) is proposed for the first time in this paper. The source-connected T-shaped field-plate (ST-FP) is composed of a source-connected field-plate (S-FP) and a trench metal. The physical intrinsic mechanisms of the ST-FP to improve the breakdown voltage and the FP efficiency and to modulate the distributions of channel electric field and potential are studied in detail by means of two-dimensional numerical simulations with Silvaco-ATLAS. A comparison to the HEMT and the HEMT with an S-FP (S-FP HEMT) shows that the ST-FP HEMT could achieve a broader and more uniform channel electric field distribution with the help of a trench metal, which could increase the breakdown voltage and the FP efficiency remarkably. In addition, the relationship between the structure of the ST-FP, the channel electric field, the breakdown voltage as well as the FP efficiency in ST-FP HEMT is analyzed. These results could open up a new effective method to fabricate high voltage power devices for the power electronic applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 61574112, 61334002, 61306017, 61474091, and 61574110) and the Natural Science Basic Research Plan in Shaanxi Province, China (Grant No. 605119425012).

  17. Analysis of Stress and Strain Fields in and around Inclusions of Various Shapes in a Cylindrical Specimen Loaded in Tension

    Directory of Open Access Journals (Sweden)

    Neimitz A.

    2016-06-01

    Full Text Available A numerical analysis is performed of the stress field in and around inclusions of various shapes. Inclusions both stiffer and more compliant than the metal matrix are analysed. The critical stresses required for inclusion fracture are estimated after observation of cavities and inclusions by scanning electron microscopy. Real inclusions were observed after performing uniaxial loading to different amounts of overall strain. The material tested was Hardox-400 steel.

  18. Nudging children towards whole wheat bread: a field experiment on the influence of fun bread roll shape on breakfast consumption

    OpenAIRE

    Kleef, van, J.; Vrijhof, M.N.; Polet, I.A.; Vingerhoeds, M.H.; Wijk, van, C.A.Ph.

    2014-01-01

    Background: Many children do not eat enough whole grains, which may have negative health consequences. Intervention research is increasingly focusing on nudging as a way to influence food choices by affecting unconscious behavioural processes. The aim of this field study was to examine whether the shape of bread rolls is able to shift children’s bread choices from white to whole wheat during breakfast to increase whole grain intake. Methods: In a between-subjects experiment conducted at twelv...

  19. Explicit solution of the Volterra integral equation for transient fields on inhomogeneous arbitrarily shaped dielectric bodies

    KAUST Repository

    Al Jarro, Ahmed

    2011-09-01

    A new predictor-corrector scheme for solving the Volterra integral equation to analyze transient electromagnetic wave interactions with arbitrarily shaped inhomogeneous dielectric bodies is considered. Numerical results demonstrating stability and accuracy of the proposed method are presented. © 2011 IEEE.

  20. Full-field 3D shape measurement of specular object having discontinuous surfaces

    Science.gov (United States)

    Zhang, Zonghua; Huang, Shujun; Gao, Nan; Gao, Feng; Jiang, Xiangqian

    2017-06-01

    This paper presents a novel Phase Measuring Deflectometry (PMD) method to measure specular objects having discontinuous surfaces. A mathematical model is established to directly relate the absolute phase and depth, instead of the phase and gradient. Based on the model, a hardware measuring system has been set up, which consists of a precise translating stage, a projector, a diffuser and a camera. The stage locates the projector and the diffuser together to a known position during measurement. By using the model-based and machine vision methods, system calibration is accomplished to provide the required parameters and conditions. The verification tests are given to evaluate the effectiveness of the developed system. 3D (Three-Dimensional) shapes of a concave mirror and a monolithic multi-mirror array having multiple specular surfaces have been measured. Experimental results show that the proposed method can obtain 3D shape of specular objects having discontinuous surfaces effectively

  1. Study of magnetic field distribution in anisotropic single twin-boundary magnetic shape memory (MSM) element in actuators

    Science.gov (United States)

    Gabdullin, N.; Khan, S. H.

    2017-10-01

    Magnetic shape memory effect exhibited by certain alloys at room temperature is known for almost 20 years. The most studied MSM alloys are Ni-Mn-Ga alloys which exhibit up to 12% magnetic field-induced strain (change in shape) depending on microstructure. A multibillion cycle operation without malfunction along with their “smart” properties make them very promising for application in electromagnetic (EM) actuators and sensors. However, considerable twinning stress of MSM crystals resulting in magneto-mechanical hysteresis decreases the efficiency and output force of MSM actuators. Whereas twinning stress of conventional MSM crystals has been significantly decreased over the years, novel crystals with Type II twin boundaries (TBs) possess even lower twinning stress. Unfortunately, the microstructure of MSM crystals with very low twinning stress tends to be unstable leading to their rapid crack growth. Whilst this phenomenon has been studied experimentally, the magnetic field distribution in anisotropic single twin-boundary MSM elements has not been considered yet. This paper analyses the magnetic field distribution in two-variant single twin-boundary MSM elements and discusses its effects on magnetic field-induced stress acting on the twin boundary.

  2. Colour and shape analysis techniques for weed detection in cereal fields

    DEFF Research Database (Denmark)

    Pérez, A.J; López, F; Benlloch, J.V.

    2000-01-01

    Information on weed distribution within the field is necessary to implement spatially variable herbicide application. This paper deals with the development of near-ground image capture and processing techniques in order to detect broad-leaved weeds in cereal crops under actual field conditions. T...

  3. Spectral shaping of attosecond pulses using two-colour laser fields

    Energy Technology Data Exchange (ETDEWEB)

    Mansten, E; Dahlstroem, J M; Johnsson, P; Swoboda, M; L' Huillier, A; Mauritsson, J [Department of Physics, Lund University, P O Box 118, SE-221 00 Lund (Sweden)], E-mail: erik.mansten@fysik.lth.se, E-mail: johan.mauritsson@fysik.lth.se

    2008-08-15

    We use a strong two-colour laser field composed of the fundamental (800 nm) and the second harmonic (400 nm) of an infrared (IR) laser field to generate attosecond pulses with controlled spectral and temporal properties. With a second-harmonic intensity equal to 15% of the IR intensity the second-harmonic field is strong enough to significantly alter and control the electron trajectories in the generation process. This enables us to tune the central photon energy of the attosecond pulses by changing the phase difference between the IR and the second-harmonic fields. In the time domain the radiation is emitted as a sequence of pulses separated by a full IR cycle. We also perform calculations showing that the effect of even stronger second-harmonic fields leads to an extended tunable range under conditions that are experimentally feasible.

  4. Experimental study of directionally solidified ferromagnetic shape memory alloy under multi-field coupling

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yuping, E-mail: zhuyuping@126.com [Institute of Geophysics, China Earthquake Administration, Beijing 100081 (China); Chen, Tao; Teng, Yao [Faculty of Civil Engineering and Mechanics, Jiangsu University, Zhenjiang 212013 (China); Liu, Bingfei [Airport College, Civil Aviation University of China, Tianjin 300300 (China); Xue, Lijun [Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System, School of Mechanical Engineering, Tianjin University of Technology, Tianjin 300384 (China)

    2016-11-01

    Directionally solidified, polycrystalline Ni–Mn–Ga is studied in this paper. The polycrystalline Ni–Mn–Ga samples were cut at different angles to solidification direction. The magnetic field induced strain under constant stress and the temperature-induced strain under constant magnetic field during the loading–unloading cycle were measured. The experimental results show that the mechanical behavior during the loading–unloading cycle of the material is nonlinear and anisotropic. Based on the experimental results, the effects of multi-field coupling factors, such as stress, magnetic field, temperature and cutting angle on the mechanical behaviors were analyzed. Some useful conclusions were obtained, which will provide guidance for practical applications. - Highlights: • The magnetic-induced strains in different directions are tested. • The temperature-induced strains in different directions are tested. • The effects of coupling factors on directional solidification samples are studied.

  5. Experimental study of directionally solidified ferromagnetic shape memory alloy under multi-field coupling

    Science.gov (United States)

    Zhu, Yuping; Chen, Tao; Teng, Yao; Liu, Bingfei; Xue, Lijun

    2016-11-01

    Directionally solidified, polycrystalline Ni-Mn-Ga is studied in this paper. The polycrystalline Ni-Mn-Ga samples were cut at different angles to solidification direction. The magnetic field induced strain under constant stress and the temperature-induced strain under constant magnetic field during the loading-unloading cycle were measured. The experimental results show that the mechanical behavior during the loading-unloading cycle of the material is nonlinear and anisotropic. Based on the experimental results, the effects of multi-field coupling factors, such as stress, magnetic field, temperature and cutting angle on the mechanical behaviors were analyzed. Some useful conclusions were obtained, which will provide guidance for practical applications.

  6. Imaging large fields of small targets with shaped EM fields, adaptive beam steering and dynamic constellation antennas

    OpenAIRE

    Blondel, Philippe; Guigné, Jacques; Mundell, Carole

    2017-01-01

    Space debris is an increasing problem, with ca. 18,000 objects large enough to be tracked from the ground and conservative estimates of 670,000 small (1 – 10 cm) debris. Collisions have become a key issue in operation and decommissioning of spacecraft, adding costs and risks to space missions in all orbits, with the added threat of collisional cascading if some debris fields become dense enough. Their accurate mapping in 3-D, and their evolutionwith time, therefore become paramount, but in-fl...

  7. Stress- and Magnetic Field-Induced Martensitic Transformation at Cryogenic Temperatures in Fe-Mn-Al-Ni Shape Memory Alloys

    Science.gov (United States)

    Xia, Ji; Xu, Xiao; Miyake, Atsushi; Kimura, Yuta; Omori, Toshihiro; Tokunaga, Masashi; Kainuma, Ryosuke

    2017-11-01

    Stress-induced and magnetic-field-induced martensitic transformation behaviors at low temperatures were investigated for Fe-Mn-Al-Ni alloys. The magnetic-field-induced reverse martensitic transformation was directly observed by in situ optical microscopy. Magnetization measurements under pulsed magnetic fields up to 50 T were carried out at temperatures between 4.2 and 125 K on a single-crystal sample; full magnetic-field-induced reverse martensitic transformation was confirmed at all tested temperatures. Compression tests from 10 to 100 K were conducted on a single-crystal sample; full shape recovery was obtained at all tested temperatures. It was found that the temperature dependence of both the critical stress and critical magnetic field is small and that the transformation hysteresis is less sensitive to temperature even at cryogenic temperatures. The temperature dependence of entropy change during martensitic transformation up to 100 K was then derived using the Clausius-Clapeyron relation with critical stresses and magnetic fields.

  8. Stress- and Magnetic Field-Induced Martensitic Transformation at Cryogenic Temperatures in Fe-Mn-Al-Ni Shape Memory Alloys

    Science.gov (United States)

    Xia, Ji; Xu, Xiao; Miyake, Atsushi; Kimura, Yuta; Omori, Toshihiro; Tokunaga, Masashi; Kainuma, Ryosuke

    2017-12-01

    Stress-induced and magnetic-field-induced martensitic transformation behaviors at low temperatures were investigated for Fe-Mn-Al-Ni alloys. The magnetic-field-induced reverse martensitic transformation was directly observed by in situ optical microscopy. Magnetization measurements under pulsed magnetic fields up to 50 T were carried out at temperatures between 4.2 and 125 K on a single-crystal sample; full magnetic-field-induced reverse martensitic transformation was confirmed at all tested temperatures. Compression tests from 10 to 100 K were conducted on a single-crystal sample; full shape recovery was obtained at all tested temperatures. It was found that the temperature dependence of both the critical stress and critical magnetic field is small and that the transformation hysteresis is less sensitive to temperature even at cryogenic temperatures. The temperature dependence of entropy change during martensitic transformation up to 100 K was then derived using the Clausius-Clapeyron relation with critical stresses and magnetic fields.

  9. Numerical Investigation of the Effect of Magnetic Field on Natural Convection in a Curved-Shape Enclosure

    Directory of Open Access Journals (Sweden)

    M. Sheikholeslami

    2013-01-01

    Full Text Available This investigation reports the magnetic field effect on natural convection heat transfer in a curved-shape enclosure. The numerical investigation is carried out using the control volume-based-finite element method (CVFEM. The numerical investigations are performed for various values of Hartmann number and Rayleigh number. The obtained results are depicted in terms of streamlines and isotherms which show the significant effects of Hartmann number on the fluid flow and temperature distribution inside the enclosure. Also, it was found that the Nusselt number decreases with an increase in the Hartmann number.

  10. A linear-field plasma jet for generating a brush-shaped laminar plume at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xuechen; Jia, Pengying, E-mail: plasmalab@126.com [College of Physics Science and Technology, Hebei University, Baoding 071002 (China); Key Laboratory of Photo-Electronics Information Materials of Hebei Province, Baoding 071002 (China); Li, Jiyuan; Chu, Jingdi; Zhang, Panpan [College of Physics Science and Technology, Hebei University, Baoding 071002 (China)

    2016-06-15

    A linear-field plasma jet composed of line-to-plate electrodes is used to generate a large-scale brush-shaped plasma plume with flowing argon used as working gas. Through electrical measurement and fast photography, it is found that the plasma plume bridges the two electrodes for the discharge in the positive voltage half-cycle, which behaves like fast moving plasma bullets directed from the anode to the cathode. Compared with the positive discharge, the negative discharge only develops inside the nozzle and propagates much slower. Results also indicate that the gas temperature of the plume is close to room temperature, which is promising for biomedical application.

  11. 3D shape measurement using deterministic phase retrieval and a partially developed speckle field

    DEFF Research Database (Denmark)

    Almoro, Percival F.; Waller, Laura; Agour, Mostafa

    2012-01-01

    Fourier domain. The local variations of the recorded speckle patterns and the defocus distance approximate the axial intensity derivative which, in turn, is required to recover the wavefront phase via the transport of intensity equation (TIE). The SLM setup reduces the speckle recording time and the TIE......For deterministic phase retrieval, the problem of insignificant axial intensity variations upon defocus of a smooth object wavefront is addressed. Our proposed solution is based on the use of a phase diffuser facilitating the formation of a partially-developed speckle field (i.e., a field with both...... allows direct (i.e., non-iterative) calculation of the phase. The pre-requisite partially-developed speckle field in our technique facilitates high image contrast and significant axial intensity variation. Wavefront reconstruction for the 3D refractive test object used demonstrates the effectiveness...

  12. Flow field analysis of a pentagonal-shaped bridge deck by unsteady RANS

    Directory of Open Access Journals (Sweden)

    Md. Naimul Haque

    2016-01-01

    Full Text Available Long-span cable-stayed bridges are susceptible to dynamic wind effects due to their inherent flexibility. The fluid flow around the bridge deck should be well understood for the efficient design of an aerodynamically stable long-span bridge system. In this work, the aerodynamic features of a pentagonal-shaped bridge deck are explored numerically. The analytical results are compared with past experimental work to assess the capability of two-dimensional unsteady RANS simulation for predicting the aerodynamic features of this type of deck. The influence of the bottom plate slope on aerodynamic response and flow features was investigated. By varying the Reynolds number (2 × 104 to 20 × 104 the aerodynamic behavior at high wind speeds is clarified.

  13. Judicious distribution of laser emitters to shape the desired far-field patterns

    Science.gov (United States)

    Valagiannopoulos, Constantinos A.; Kovanis, Vassilios

    2017-06-01

    The far-field pattern of a simple one-dimensional laser array of emitters radiating into free space is considered. In the course of investigating the inverse problem for their near fields leading to a target beam form, surprisingly, we found that the result is successful when the matrix of the corresponding linear system is not well scaled. The essence of our numerical observations is captured by an elegant inequality defining the functional range of the optical distance between two neighboring emitters. Our finding can restrict substantially the parametric space of integrated photonic systems and simplify significantly the subsequent optimizations.

  14. Laser-pulse-shape control of photofragmentation in the weak-field limit

    DEFF Research Database (Denmark)

    Tiwari, Ashwani Kumar; Dey, Diptesh; Henriksen, Niels Engholm

    2014-01-01

    We demonstrate theoretically that laser-induced coherent quantum interference control of asymptotic states of dissociating molecules is possible even in the (one-photon) weak-field limit starting from a single vibrational eigenstate. Thus, phase dependence in the interaction with a fixed energy...

  15. Bulkiness versus anisotropy: The optimal shape of polarizable Brownian nanoparticles for alignment in electric fields

    NARCIS (Netherlands)

    Kwaadgras, B.W.; Dijkstra, M.|info:eu-repo/dai/nl/123538807; van Roij, R.H.H.G.|info:eu-repo/dai/nl/152978984

    2012-01-01

    Self-assembly and alignment of anisotropic colloidal particles are important processes that can be influenced by external electric fields. However, dielectric nanoparticles are generally hard to align this way because of their small size and low polarizability. In this work, we employ the coupled

  16. Religious Studies: The Shaping of a Field and a Guide to Reference Resources.

    Science.gov (United States)

    Lippy, Charles H.

    1992-01-01

    Discusses the development of religious studies as an academic discipline. Examines the work of leading thinkers in the field, including anthropologists Sir James Fraser and Edward Burnett Taylor, sociologist Max Weber, and psychologist Erik Erikson. Identifies some of the many reference works that deal with religious studies. (SG)

  17. Field configuring events shaping sustainability transitions? The case of solar PV in India

    NARCIS (Netherlands)

    Jolly, Suyash; Raven, R.P.J.M.

    Abstract The sustainability transitions literature has emphasized the analytical challenges in understanding the trade-offs in protecting niche innovations. This paper builds on an emerging body of literature that argues that the concept of field-configuring events (FCE) is useful for understanding

  18. Shape, size, velocity and field-aligned currents of dayside plasma injections: a multi-altitude study

    Directory of Open Access Journals (Sweden)

    A. Marchaudon

    2009-03-01

    Full Text Available On 20 February 2005, Cluster in the outer magnetosphere and Double Star-2 (TC-2 at mid-altitude are situated in the vicinity of the northern cusp/mantle, with Cluster moving sunward and TC-2 anti-sunward. Their magnetic footprints come very close together at about 15:28 UT, over the common field-of-view of SuperDARN radars. Thanks to this conjunction, we determine the velocity, the transverse sizes, perpendicular and parallel to this velocity, and the shape of three magnetic flux tubes of magnetosheath plasma injection. The velocity of the structures determined from the Cluster four-spacecraft timing analysis is almost purely antisunward, in contrast with the antisunward and duskward convection velocity inside the flux tubes. The transverse sizes are defined from the Cluster-TC-2 separation perpendicular to the magnetic field, and from the time spent by a Cluster spacecraft in one structure; they are comprised between 0.6 and 2 RE in agreement with previous studies. Finally, using a comparison between the eigenvectors deduced from a variance analysis of the magnetic perturbation at the four Cluster and at TC-2, we show that the upstream side of the injection flux tubes is magnetically well defined, with even a concave front for the third one giving a bean-like shape, whereas the downstream side is far more turbulent. We also realise the first quantitative comparison between field-aligned currents at Cluster calculated with the curlometer technique and with the single-spacecraft method, assuming infinite parallel current sheets and taking into account the velocity of the injection flux tubes. The results agree nicely, confirming the validity of both methods. Finally, we compare the field-aligned current distribution of the three injection flux tubes at the altitudes of Cluster and TC-2. Both profiles are fairly similar, with mainly a pair of opposite field-aligned currents, upward at low-latitude and downward at high

  19. Shape, size, velocity and field-aligned currents of dayside plasma injections: a multi-altitude study

    Directory of Open Access Journals (Sweden)

    A. Marchaudon

    2009-03-01

    Full Text Available On 20 February 2005, Cluster in the outer magnetosphere and Double Star-2 (TC-2 at mid-altitude are situated in the vicinity of the northern cusp/mantle, with Cluster moving sunward and TC-2 anti-sunward. Their magnetic footprints come very close together at about 15:28 UT, over the common field-of-view of SuperDARN radars. Thanks to this conjunction, we determine the velocity, the transverse sizes, perpendicular and parallel to this velocity, and the shape of three magnetic flux tubes of magnetosheath plasma injection. The velocity of the structures determined from the Cluster four-spacecraft timing analysis is almost purely antisunward, in contrast with the antisunward and duskward convection velocity inside the flux tubes. The transverse sizes are defined from the Cluster-TC-2 separation perpendicular to the magnetic field, and from the time spent by a Cluster spacecraft in one structure; they are comprised between 0.6 and 2 RE in agreement with previous studies. Finally, using a comparison between the eigenvectors deduced from a variance analysis of the magnetic perturbation at the four Cluster and at TC-2, we show that the upstream side of the injection flux tubes is magnetically well defined, with even a concave front for the third one giving a bean-like shape, whereas the downstream side is far more turbulent. We also realise the first quantitative comparison between field-aligned currents at Cluster calculated with the curlometer technique and with the single-spacecraft method, assuming infinite parallel current sheets and taking into account the velocity of the injection flux tubes. The results agree nicely, confirming the validity of both methods. Finally, we compare the field-aligned current distribution of the three injection flux tubes at the altitudes of Cluster and TC-2. Both profiles are fairly similar, with mainly a pair of opposite field-aligned currents, upward at low-latitude and downward at high-latitude. In terms of

  20. Dynamically Harmonized FT-ICR Cell with Specially Shaped Electrodes for Compensation of Inhomogeneity of the Magnetic Field. Computer Simulations of the Electric Field and Ion Motion Dynamics

    Science.gov (United States)

    Kostyukevich, Yury I.; Vladimirov, Gleb N.; Nikolaev, Eugene N.

    2012-12-01

    The recently introduced ion trap for FT-ICR mass spectrometers with dynamic harmonization showed the highest resolving power ever achieved both for ions with moderate masses 500-1000 Da (peptides) as well as ions with very high masses of up to 200 kDa (proteins). Such results were obtained for superconducting magnets of very high homogeneity of the magnetic field. For magnets with lower homogeneity, the time of transient duration would be smaller. In superconducting magnets used in FT-ICR mass spectrometry the inhomogeneity of the magnetic field in its axial direction prevails over the inhomogeneity in other directions and should be considered as the main factor influencing the synchronic motion of the ion cloud. The inhomogeneity leads to a dependence of the cyclotron frequency from the amplitude of axial oscillation in the potential well of the ion trap. As a consequence, ions in an ion cloud become dephased, which leads to signal attenuation and decrease in the resolving power. Ion cyclotron frequency is also affected by the radial component of the electric field. Hence, by appropriately adjusting the electric field one can compensate the inhomogeneity of the magnetic field and align the cyclotron frequency in the whole range of amplitudes of z-oscillations. A method of magnetic field inhomogeneity compensation in a dynamically harmonized FT-ICR cell is presented, based on adding of extra electrodes into the cell shaped in such a way that the averaged electric field created by these electrodes produces a counter force to the forces caused by the inhomogeneous magnetic field.

  1. Effect of an eccentric rotation on the equilibrium shapes and stability of liquid bridges in a lateral gravity field

    Science.gov (United States)

    Laverón-Simavilla, Ana; Lapuerta, Victoria; Rodríguez, Angel; Perales, Jose Manuel

    A cylindrical liquid bridge supported between two circular-shaped disks in isorotation is considered. The combined effect of a lateral gravity field and an offset between the rotation axis and the axis of the supporting disks (eccentricity) on the stability of the liquid bridge is here studied. In a previous work a numerical method used to determine the stability limit for different values of eccentricity was validated by comparing with analytical results at small eccentricity. In this work we use an extension of that algorithm applied to liquid bridges in a lateral gravitational field rotating around an eccentric axis to study the combined effect of rotation, eccentricity and lateral gravity. The analysis shows that the combined effect of lateral gravity and eccentricity can narrow or broaden the stability region depending on the angle between the gravity direction and the eccentric axis displacement.

  2. Comparison of hinge microflow fields of bileaflet mechanical heart valves implanted in different sinus shape and downstream geometry.

    Science.gov (United States)

    Kuan, Yee Han; Kabinejadian, Foad; Nguyen, Vinh-Tan; Su, Boyang; Yoganathan, Ajit P; Leo, Hwa Liang

    2015-01-01

    The characterization of the bileaflet mechanical heart valves (BMHVs) hinge microflow fields is a crucial step in heart valve engineering. Earlier in vitro studies of BMHV hinge flow at the aorta position in idealized straight pipes have shown that the aortic sinus shapes and sizes may have a direct impact on hinge microflow fields. In this paper, we used a numerical study to look at how different aortic sinus shapes, the downstream aortic arch geometry, and the location of the hinge recess can influence the flow fields in the hinge regions. Two geometric models for sinus were investigated: a simplified axisymmetric sinus and an idealized three-sinus aortic root model, with two different downstream geometries: a straight pipe and a simplified curved aortic arch. The flow fields of a 29-mm St Jude Medical BMHV with its four hinges were investigated. The simulations were performed throughout the entire cardiac cycle. At peak systole, recirculating flows were observed in curved downsteam aortic arch unlike in straight downstream pipe. Highly complex three-dimensional leakage flow through the hinge gap was observed in the simulation results during early diastole with the highest velocity at 4.7 m/s, whose intensity decreased toward late diastole. Also, elevated wall shear stresses were observed in the ventricular regions of the hinge recess with the highest recorded at 1.65 kPa. Different flow patterns were observed between the hinge regions in straight pipe and curved aortic arch models. We compared the four hinge regions at peak systole in an aortic arch downstream model and found that each individual hinge did not vary much in terms of the leakage flow rate through the valves.

  3. Prescription, Description, Reflection: the shape of the software process improvement field

    DEFF Research Database (Denmark)

    Hansen, Bo; Rose, Jeremy; Tjørnehøj, Gitte

    2004-01-01

    This article reviews 322 representative contributions to the the Software Process Improvement (SPI) literature. The contributions are categorised according to a simple framework: whether their primary goal is (to tell SPI professionals what to do), (to report actual instances of SPI programs...... in software organisations), or   prescriptive descriptive reflective (theoretically analytical). The field is found to be rather dominated by one approach (the Capability Maturity Model (CMM)) and heavily biased towards prescriptive contributions. Neither of these trends is necessarily beneficial...

  4. Electromagnetic Field Enhancement and Spectrum Shaping through Plasmonically Integrated Optical Vortices

    OpenAIRE

    Ahn, Wonmi; Boriskina, Svetlana V.; Hong, Yan; Reinhard, Björn M.

    2011-01-01

    We introduce a new design approach for surface enhanced Raman spectroscopy (SERS) substrates that is based on molding the optical powerflow through a sequence of coupled nanoscale optical vortices ‘pinned’ to rationally-designed plasmonic nanostructures, referred to as Vortex Nanogear Transmissions (VNTs). We fabricated VNTs composed of Au nanodiscs by electron beam lithography on quartz substrates and characterized their near- and far-field responses through combination of computational elec...

  5. Gendered Pathways: How Mathematics Ability Beliefs Shape Secondary and Postsecondary Course and Degree Field Choices

    Science.gov (United States)

    Perez-Felkner, Lara; Nix, Samantha; Thomas, Kirby

    2017-01-01

    Do mathematics ability beliefs explain gender gaps in the physical science, engineering, mathematics, and computer science fields (PEMC) and other science fields? We leverage U.S. nationally representative longitudinal data to estimate gendered differences in girls' and boys' perceptions of mathematics ability with the most difficult or challenging material. Our analyses examine the potentially interacting effects of gender and these ability beliefs on students' pathways to scientific careers. Specifically, we study how beliefs about ability with challenging mathematics influence girls' and boys' choices to pursue PEMC degrees, evaluating educational milestones over a 6-year period: advanced science course completion in secondary school and postsecondary major retention and selection. Our findings indicate even at the same levels of observed ability, girls' mathematics ability beliefs under challenge are markedly lower than those of boys. These beliefs matter over time, potentially tripling girls' chances of majoring in PEMC sciences, over and above biological science fields, all else being equal. Implications and potential interventions are discussed. PMID:28428762

  6. Electric field-induced nonlinearity enhancement in strained semi-spheroid-shaped quantum dots coupled to wetting layer

    Directory of Open Access Journals (Sweden)

    Mohammad Sabaeian

    2014-12-01

    Full Text Available In this work, the effects of vertical electric field on the electronic and optical properties of strained semi-spheroid-shaped InAs/GaAs quantum dot (QD coupled to its wetting layer (WL aimed to enhance the nonlinear optical properties were investigated. The dependence of energy eigenvalues of S- and P- states and intersubband P-to-S transition energy on applied electric field was studied. A ∼∓ߙ10 meV Stark shift in the intersubband P-to-S transition energy was calculated for a semi-spheroid-shaped QD with height of 5 nm and base-length of 20 nm when bias voltage was varied from 0 V to ±0.8V. The dependence of transition dipole moment and linear and nonlinear optical properties of the system on bias voltage was also studied. It was concluded that increasing the bias voltage from -0.8V to +0.8V leads to increase in figure of merit of the system from ∼0.153 to ∼0.198.

  7. Electric field-induced nonlinearity enhancement in strained semi-spheroid-shaped quantum dots coupled to wetting layer

    Energy Technology Data Exchange (ETDEWEB)

    Sabaeian, Mohammad, E-mail: sabaeian@scu.ac.ir; Shahzadeh, Mohammadreza; Farbod, Mansoor [Physics Department, Faculty of Science, Shahid Chamran University of Ahvaz, 61357-43135 (Iran, Islamic Republic of)

    2014-12-15

    In this work, the effects of vertical electric field on the electronic and optical properties of strained semi-spheroid-shaped InAs/GaAs quantum dot (QD) coupled to its wetting layer (WL) aimed to enhance the nonlinear optical properties were investigated. The dependence of energy eigenvalues of S- and P- states and intersubband P-to-S transition energy on applied electric field was studied. A ∼∓10 meV Stark shift in the intersubband P-to-S transition energy was calculated for a semi-spheroid-shaped QD with height of 5 nm and base-length of 20 nm when bias voltage was varied from 0 V to ±0.8V. The dependence of transition dipole moment and linear and nonlinear optical properties of the system on bias voltage was also studied. It was concluded that increasing the bias voltage from -0.8V to +0.8V leads to increase in figure of merit of the system from ∼0.153 to ∼0.198.

  8. Obstacle-shape effect in a two-dimensional granular silo flow field

    Science.gov (United States)

    Endo, K.; Reddy, K. Anki; Katsuragi, H.

    2017-09-01

    We conduct a simple experiment and numerical simulation of two-dimensional granular discharge flow driven by gravity under the influence of an obstacle. According to previous work [Zuriguel et al., Phys. Rev. Lett. 107, 278001 (2011), 10.1103/PhysRevLett.107.278001], the clogging of granular discharge flow can be suppressed by putting a circular obstacle at a proper position. In order to investigate the details of the obstacle effect in granular flow, we focus on particle dynamics in this study. From the experimental and numerical data, we find that the obstacle remarkably affects the horizontal-velocity distribution and packing fraction in the vicinity of the exit. In addition to the circular obstacle, we utilize triangular, inverted-triangular, and horizontal-bar obstacles to discuss the obstacle-shape effect in granular discharge flow. Based on the investigation of dynamical quantities such as velocity distributions, granular temperature, and volume fraction, we find that the triangular obstacle or horizontal bar could be very effective in preventing the clogging. From the result obtained, we consider that the detouring of particles around the obstacle and resultant low packing fraction at the exit region effectively prevent the clogging in a certain class of granular discharge flow.

  9. Network Neurodegeneration in Alzheimer’s Disease via MRI based Shape Diffeomorphometry and High Field Atlasing

    Directory of Open Access Journals (Sweden)

    Michael I Miller

    2015-05-01

    Full Text Available This paper examines MRI analysis of neurodegeneration in Alzheimer’s Disease (AD in a network of structures within the medial temporal lobe using diffeomorphometry methods coupled with high-field atlasing in which the entorhinal cortex is partitioned into nine subareas. The morphometry markers for three groups of subjects (controls, preclinical AD and symptomatic AD are indexed to template coordinates measured with respect to these nine subareas. The location and timing of changes are examined within the subareas as it pertains to the classic Braak and Braak staging by comparing the three groups. We demonstrate that the earliest preclinical changes in the population occur in the lateral most sulcal extent in the entorhinal cortex (alluded to as trans entorhinal cortex by Braak and Braak, and then proceeds medially which is consistent with the Braak and Braak staging. We use high field 11T atlasing to demonstrate that the network changes are occurring at the junctures of the substructures in this medial temporal lobe network. Temporal progression of the disease through the network is also examined via changepoint analysis demonstrating earliest changes in entorhinal cortex. The differential expression of rate of atrophy with progression signaling the changepoint time across the network is demonstrated to be signaling in the intermediate caudal subarea of the entorhinal cortex, which has been noted to be proximal to the hippocampus. This coupled to the findings of the nearby basolateral involvement in amygdala demonstrates the selectivity of neurodegeneration in early AD.

  10. Anisotropic colloidal assembly: Kinetics, shape complementarity, and field-mediated propulsion

    Science.gov (United States)

    Colon-Melendez, Laura D.

    We use confocal microscopy and particle tracking methods to study the binding kinetics and equilibrium thermodynamics of suspensions of anisotropic lock and key colloids that self-assemble in the presence of polyethylene oxide polymeric depletant. We find that specific lock-key bonds form by (1) the diffusion of a key into the lock dimple from bulk as well as (2) by the surface diffusion of a key particle that binds to the spherical surface of the lock and diffuses on its surface until binding to the lock dimple. We compare experimental results to a Smoluchowski diffusion-migration model and find quantitative agreement between both. We also perform equilibrium binding experiments with different sized key particles and find lower free energies of specific bond formation for key particles smaller than the dimple size implying that smaller keys have better overall binding affinity to the lock dimple than keys larger than the lock dimple. These results agree with previous modeling work that predicts optimized formation of specific lock-key bonds for spherical key particles smaller than the lock cavity radius. In the second part of the dissertation, we investigate the emerging propulsion of colloidal spheres in binary suspensions subject to a low frequency oscillatory electric field perpendicular to the plane of motion of the particles. The effect is switchable: particles revert back to normal diffusion upon turning off the electric field. The active motion of particles is attributed to unbalanced electrohydrodynamic flow. Large particle motion is characterized using confocal microscopy and particle tracking algorithms. We find that the mean-squared displacement of the particles is well fit by single-particle active motion model of mean-squared displacement. The propulsion speed of large particles increases with increasing applied voltage and decreases with increasing frequency of oscillation. We find that the short-time ballistic motion of a large particle depends on

  11. Shape, zonal winds and gravitational field of Jupiter: a fully self-consistent, multi-layered model

    Science.gov (United States)

    Schubert, Gerald; Kong, Dali; Zhang, Keke

    2016-10-01

    We construct a three-dimensional, finite-element, fully self-consistent, multi-layered,non-spheroidal model of Jupiter consisting of an inner core, a metallic electrically conducting dynamo region and an outer molecular electrically insulating envelope. We assume that the Jovian zonal winds are on cylinders parallel to the rotation axis but, due to the effect of magnetic braking, are confined within the outer molecular envelope. Two related calculations are carried out. The first provides an accurate description of the shape and internal density profile of Jupiter; the effect of rotational distortion is not treated as a small perturbation on a spherically symmetric state. This calculation determines the density, size and shape of the inner core, the irregular shape of the 1-bar pressure level, and the internal structure of Jupiter; the full effect of rotational distortion, without the influence of the zonal winds, is accounted for. Our multi-layered model is able to produce the known mass, the known equatorial and polar radii, and the known zonal gravitational coefficient J2 of Jupiter within their error bars; it also yields the coefficients J4 and J6 within about 5% accuracy, and the core equatorial radius 0.09RJ containing 3.73 Earth masses.The second calculation determines the variation of the gravitational field caused solely by the effect of the zonal winds on the rotationally distorted non-spheroidal Jupiter. Four different cases, ranging from a deep wind profile to a very shallow profile, are considered and implications for accurate interpretation of the zonal gravitational coefficients expected from the Juno mission are discussed.

  12. Shape of the equatorial magnetopause affected by the radial interplanetary magnetic field

    Science.gov (United States)

    Grygorov, K.; Šafránková, J.; Němeček, Z.; Pi, G.; Přech, L.; Urbář, J.

    2017-11-01

    The ability of a prediction of the magnetopause location under various upstream conditions can be considered as a test of our understanding of the solar wind-magnetosphere interaction. The present magnetopause models are parametrized with the solar wind dynamic pressure and usually with the north-south interplanetary magnetic field (IMF) component. However, several studies pointed out an importance of the radial IMF component, but results of these studies are controversial up to now. The present study compares magnetopause observations by five THEMIS spacecraft during long lasting intervals of the radial IMF with two empirical magnetopause models. A comparison reveals that the magnetopause location is highly variable and that the average difference between the observed and predicted positions is ≈ + 0.7 RE under this condition. The difference does not depend on the local times and other parameters, like the upstream pressure, IMF north-south component, or tilt angle of the Earth dipole. We conclude that our results strongly support the suggestion on a global expansion of the equatorial magnetopause during intervals of the radial IMF.

  13. Computational Field Shaping for Deep Brain Stimulation With Thousands of Contacts in a Novel Electrode Geometry.

    Science.gov (United States)

    Willsie, Andrew C; Dorval, Alan D

    2015-10-01

    Deep brain stimulation (DBS) alleviates symptoms associated with some neurological disorders by stimulating specific deep brain targets. However, incomplete stimulation of the target region can provide suboptimal therapy, and spread of stimulation to tissue outside the target can generate side-effects. Existing DBS electrodes generate stimulation profiles that are roughly spherical, neither matching nor enabling the mapping of therapeutic targets. We present a novel electrode design and will perform computational modeling of the new design to investigate its use as a next generation DBS electrode. Computational simulations of a finite element model are performed for both the novel electrode and for a commercially available DBS electrode. Computational modeling results show that this new electrode design is able to steer stimulation radially around the device, creating voltage distributions that may more closely match deep brain targets. The ability to better match the anatomy and compensate for targeting errors during implantation will enable strict localization of the generated stimulation fields to within target tissues, potentially providing more complete symptom alleviation while reducing the occurrence of side-effects. © 2015 International Neuromodulation Society.

  14. Investigation on the corner effect of L-shaped tunneling field-effect transistors and their fabrication method.

    Science.gov (United States)

    Kim, Sang Wan; Choi, Woo Young; Sun, Min-Chul; Park, Byung-Gook

    2013-09-01

    In this work, electrical characteristics of L-shaped tunneling field-effect transistors (TFETs) have been studied and optimized by a commercial device simulator: Synopsys Sentaurus. Unlike our previous study performed by using Silvaco Atlas, there exists a kink phenomenon in a transfer curve which degrades the subthreshold swing (SS) and on-current (lon) of TFETs. According to simulation results, the kink results from abrupt source doping. Rounding the source junction edge with gradual doping profile is helpful to alleviate it. Based on those results, a novel fabrication flow has been proposed to suppress the kink effect induced by source corners. It is predicted that the performance of L-shaped TFETs is improved in terms of SS and Ion under the optimized process condition. Furthremore, the effect of high-k gate dielectric and narrow band gap material on device performance has been examined. Using 2-nm-thick HfO2 for gate dielectric and Si0.7Ge0.3 for intrinsic tunneling region, gate controllability to the channel and tunneling probability have been enhanced. As a result, its threshold voltage (Vth), SS and Ion have been improved by 0.13 V, 16 mV/dec, and 3.62 microA/microm, respectively.

  15. Force, torque, and absorbed energy for a body of arbitrary shape and constitution in an electromagnetic radiation field

    Science.gov (United States)

    Farsund, Ø.; Felderhof, B. U.

    1996-02-01

    The force and torque exerted on a body of arbitrary shape and constitution by a stationary radiation field are in principle given by integrals of Minkowski's stress tensor over a surface surrounding the body. Similarly the absorbed energy is given by an integral of the Poynting vector. These integrals are notoriously difficult to evaluate, and so far only spherical bodies have been considered. It is shown here that the integrals may be cast into a simpler form by use of Debye potentials. General expressions for the integrals are derived as sums of bilinear expressions in the coefficients of the expansion of the incident and scattered waves in terms of vector spherical waves. The expressions are simplified for small particles, such as atoms, for which the electric dipole approximation may be used. It is shown that the calculation is also relevant for bodies with nonlinear electromagnetic response.

  16. A sphericon-shaped magnetic millirobot rolling on a surface actuated by an external wobbling magnetic field

    Directory of Open Access Journals (Sweden)

    Seungmun Jeon

    2017-05-01

    Full Text Available This paper proposes a novel sphericon-shaped magnetic millirobot (SSMM that can roll on a variety of surfaces. The SSMM comprises four identical half cones with a cylindrical magnet inserted into the geometric center. It can roll forward or backward on a surface with repeated rolling cone motions (wobbling motions. Since a rolling SSMM develops its entire surface by means of line contact, a relatively large maximum static friction force can make the SSMM move on a surface steadily and effectively. In this work, a new type of external wobbling magnetic field (EWMF was also derived to manipulate the SSMM’s rolling motions precisely. Then, the controlled rolling motions of prototype SSMMs under various surface conditions were demonstrated to examine the rolling ability of the proposed SSMM.

  17. Physical investigation on silver-water nanofluid natural convection for an F-shaped cavity under the magnetic field effects

    Science.gov (United States)

    Yadollahi, A.; Khalesidoost, A.; Kasaeipoor, A.; Hatami, M.; Jing, D.

    2017-08-01

    The effects of a magnetic field on a free convection regime of silver-water nanofluid are investigated. The considered geometry is an F-shaped cavity under the influence of a constant magnetic field. The left vertical walls temperature is Th, while the middle and right walls are at a constant temperature Tc, and the other walls are insulated. A FORTRAN program is developed for the numerical simulation of the considered problem. The governing equations are solved using the FVM with the SIMPLE algorithm. The effect of important physical parameters such as the Rayleigh number, the Hartmann number, AR and φ on the problem are discussed in detail. We have concluded that the increase in the Hartmann number causes a decrease in vertical velocity and heat transfer. By increasing the Rayleigh number, the influence of the Hartmann number will be increased. An increase in the dimensional ratio of the cavity causes a decrease in the Nusselt number except in AR = 0.4. The AR has the maximum impact on the local Nusselt number, at the bottom of the hot wall. The effect of the dimensional ratio of the cavity on the Nusselt number is reversed on top of the wall. The maximum value of the Nusselt number is observed at AR = 0.4.

  18. A Parametric Approach to Shape Field-Relevant Blast Wave Profiles in Compressed-Gas-Driven Shock Tube

    Science.gov (United States)

    Sundaramurthy, Aravind; Chandra, Namas

    2014-01-01

    Detonation of a high-explosive produces shock-blast wave, shrapnel, and gaseous products. While direct exposure to blast is a concern near the epicenter, shock-blast can affect subjects, even at farther distances. When a pure shock-blast wave encounters the subject, in the absence of shrapnels, fall, or gaseous products the loading is termed as primary blast loading and is the subject of this paper. The wave profile is characterized by blast overpressure, positive time duration, and impulse and called herein as shock-blast wave parameters (SWPs). These parameters in turn are uniquely determined by the strength of high explosive and the distance of the human subjects from the epicenter. The shape and magnitude of the profile determine the severity of injury to the subjects. As shown in some of our recent works (1–3), the profile not only determines the survival of the subjects (e.g., animals) but also the acute and chronic biomechanical injuries along with the following bio-chemical sequelae. It is extremely important to carefully design and operate the shock tube to produce field-relevant SWPs. Furthermore, it is vital to identify and eliminate the artifacts that are inadvertently introduced in the shock-blast profile that may affect the results. In this work, we examine the relationship between shock tube adjustable parameters (SAPs) and SWPs that can be used to control the blast profile; the results can be easily applied to many of the laboratory shock tubes. Further, replication of shock profile (magnitude and shape) can be related to field explosions and can be a standard in comparing results across different laboratories. Forty experiments are carried out by judiciously varying SAPs such as membrane thickness, breech length (66.68–1209.68 mm), measurement location, and type of driver gas (nitrogen, helium). The effects SAPs have on the resulting shock-blast profiles are shown. Also, the shock-blast profiles of a TNT explosion from ConWep software is

  19. A parametric approach to shape field-relevant blast wave profiles in compressed-gas-driven shock tube.

    Science.gov (United States)

    Sundaramurthy, Aravind; Chandra, Namas

    2014-01-01

    Detonation of a high-explosive produces shock-blast wave, shrapnel, and gaseous products. While direct exposure to blast is a concern near the epicenter, shock-blast can affect subjects, even at farther distances. When a pure shock-blast wave encounters the subject, in the absence of shrapnels, fall, or gaseous products the loading is termed as primary blast loading and is the subject of this paper. The wave profile is characterized by blast overpressure, positive time duration, and impulse and called herein as shock-blast wave parameters (SWPs). These parameters in turn are uniquely determined by the strength of high explosive and the distance of the human subjects from the epicenter. The shape and magnitude of the profile determine the severity of injury to the subjects. As shown in some of our recent works (1-3), the profile not only determines the survival of the subjects (e.g., animals) but also the acute and chronic biomechanical injuries along with the following bio-chemical sequelae. It is extremely important to carefully design and operate the shock tube to produce field-relevant SWPs. Furthermore, it is vital to identify and eliminate the artifacts that are inadvertently introduced in the shock-blast profile that may affect the results. In this work, we examine the relationship between shock tube adjustable parameters (SAPs) and SWPs that can be used to control the blast profile; the results can be easily applied to many of the laboratory shock tubes. Further, replication of shock profile (magnitude and shape) can be related to field explosions and can be a standard in comparing results across different laboratories. Forty experiments are carried out by judiciously varying SAPs such as membrane thickness, breech length (66.68-1209.68 mm), measurement location, and type of driver gas (nitrogen, helium). The effects SAPs have on the resulting shock-blast profiles are shown. Also, the shock-blast profiles of a TNT explosion from ConWep software is compared

  20. Tailoring the electronic properties of a Z-shaped graphene field effect transistor via B/N doping

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Mohit; Gaur, Nitesh; Kumar, Puneet; Singh, Sangeeta [Nanoelectronics and VLSI Lab., Indian Institute of Information Technology, Design and Manufacturing (IIITDM), Jabalpur 482005 (India); Jaiswal, Neeraj K., E-mail: neeraj@iiitdmj.ac.in [Discipline of Physics, Indian Institute of Information Technology, Design and Manufacturing (IIITDM), Jabalpur 482005 (India); Kondekar, P.N. [Nanoelectronics and VLSI Lab., Indian Institute of Information Technology, Design and Manufacturing (IIITDM), Jabalpur 482005 (India)

    2015-03-20

    We performed first-principles calculations to reveal a viable way for tailoring the electronic properties of Z-shaped double gate graphene field effect transistor (Z-GFET). We used B/N impurities in channel region of Z-GFET. It is revealed that doping of channel region by B/N has a significant effect on its band gap which is directly reflected in the corresponding current–voltage characteristics. A semiconducting to metallic transition is also observed in selected configurations. For B–N co-doping (config. W), direct band gap of 1.84 eV is obtained which is 20% lower than that of pristine channel. Present results are useful for future electronic devices. - Highlights: • Doping of B/N can be used to tailor the electronic properties of graphene based FET. • The band structure is sensitive to doping site as well as doping concentration. • B–N co-doped channel exhibits 20% lower band gap than that of pristine channel. • Configurations with N doped channel show highest current amongst others.

  1. Numerical investigation of the sequential-double-ionization dynamics of helium in different few-cycle-laser-field shapes

    Science.gov (United States)

    Wustelt, Philipp; Möller, Max; Schöffler, Markus S.; Xie, Xinhua; Hanus, Vaclav; Sayler, A. Max; Baltuska, Andrius; Paulus, Gerhard G.; Kitzler, Markus

    2017-02-01

    We investigate sequential double ionization of helium by intense near-circularly polarized few-cycle laser pulses using a semiclassical ionization model with two independent electrons. Simulated He2 + ion momentum distributions are compared to those obtained in recent benchmark experiments [M. S. Schöffler, X. Xie, P. Wustelt, M. Möller, S. Roither, D. Kartashov, A. M. Sayler, A. Baltuska, G. G. Paulus, and M. Kitzler, Phys. Rev. A 93, 063421 (2016), 10.1103/PhysRevA.93.063421]. We study the influence of a number of pulse parameters such as peak intensity, carrier-envelope phase, pulse duration, and second- and third-order spectral phase on the shape of the ion momentum distributions. Good agreement is found in the main features of these distributions and of their dependence on the laser pulse duration, peak intensity, and carrier-envelope phase. Furthermore, we find that for explaining certain fine-scale features observed in the experiments, it becomes important to consider subtle timing variations in the two-electron emissions introduced by small values of chirp. This result highlights the possibility of measuring and controlling multielectron dynamics on the attosecond time scale by fine tuning the field evolution of intense close-to-single-cycle laser pulses.

  2. On beam shaping of the field radiated by a line source coupled to finite or infinite photonic crystals.

    Science.gov (United States)

    Ceccuzzi, Silvio; Jandieri, Vakhtang; Baccarelli, Paolo; Ponti, Cristina; Schettini, Giuseppe

    2016-04-01

    Comparison of the beam-shaping effect of a field radiated by a line source, when an ideal infinite structure constituted by two photonic crystals and an actual finite one are considered, has been carried out by means of two different methods. The lattice sums technique combined with the generalized reflection matrix method is used to rigorously investigate the radiation from the infinite photonic crystals, whereas radiation from crystals composed of a finite number of rods along the layers is analyzed using the cylindrical-wave approach. A directive radiation is observed with the line source embedded in the structure. With an increased separation distance between the crystals, a significant edge diffraction appears that provides the main radiation mechanism in the finite layout. Suitable absorbers are implemented to reduce the above-mentioned diffraction and the reflections at the boundaries, thus obtaining good agreement between radiation patterns of a localized line source coupled to finite and infinite photonic crystals, when the number of periods of the finite structure is properly chosen.

  3. In vivo measurement of the shape of the tissue-refractive-index correlation function and its application to detection of colorectal field carcinogenesis.

    Science.gov (United States)

    Gomes, Andrew J; Ruderman, Sarah; DelaCruz, Mart; Wali, Ramesh K; Roy, Hemant K; Backman, Vadim

    2012-04-01

    Polarization-gated spectroscopy is an established method to depth-selectively interrogate the structural properties of biological tissue. We employ this method in vivo in the azoxymethane (AOM)-treated rat model to monitor the morphological changes that occur in the field of a tumor during early carcinogenesis. The results demonstrate a statistically significant change in the shape of the refractive-index correlation function for AOM-treated rats versus saline-treated controls. Since refractive index is linearly proportional to mass density, these refractive-index changes can be directly linked to alterations in the spatial distribution patterns of macromolecular density. Furthermore, we found that alterations in the shape of the refractive-index correlation function shape were an indicator of both present and future risk of tumor development. These results suggest that noninvasive measurement of the shape of the refractive-index correlation function could be a promising marker of early cancer development.

  4. Phase-only shaped laser pulses in optimal control theory: Application to indirect photofragmentation dynamics in the weak-field limit

    DEFF Research Database (Denmark)

    Shu, Chuan-Cun; Henriksen, Niels E.

    2012-01-01

    We implement phase-only shaped laser pulses within quantum optimal control theory for laser-molecule interaction. This approach is applied to the indirect photofragmentation dynamics of NaI in the weak-field limit. It is shown that optimized phase-modulated pulses with a fixed frequency distribut...

  5. Isotoxal star-shaped polygonal voids and rigid inclusions in nonuniform antiplane shear fields. Part II: Singularities, annihilation and invisibility

    CERN Document Server

    Corso, Francesco Dal; Bigoni, Davide

    2016-01-01

    Notch stress intensity factors and stress intensity factors are obtained analytically for isotoxal star-shaped polygonal voids and rigid inclusions (and also for the corresponding limit cases of star-shaped cracks and stiffeners), when loaded through remote inhomogeneous (self-equilibrated, polynomial) antiplane shear stress in an infinite linear elastic matrix. Usually these solutions show stress singularities at the inclusion corners. It is shown that an infinite set of geometries and loading conditions exist for which not only the singularity is absent, but the stress vanishes ('annihilates') at the corners. Thus the material, which even without the inclusion corners would have a finite stress, remains unstressed at these points in spite of the applied remote load. Moreover, similar conditions are determined in which a star-shaped crack or stiffener leaves the ambient stress completely unperturbed, thus reaching a condition of 'quasi-static invisibility'. Stress annihilation and invisibility define optimal...

  6. Line shapes and time dynamics of the Förster resonances between two Rydberg atoms in a time-varying electric field

    KAUST Repository

    Yakshina, E. A.

    2016-10-21

    The observation of the Stark-tuned Förster resonances between Rydberg atoms excited by narrowband cw laser radiation requires usage of a Stark-switching technique in order to excite the atoms first in a fixed electric field and then to induce the interactions in a varied electric field, which is scanned across the Förster resonance. In our experiments with a few cold Rb Rydberg atoms, we have found that the transients at the edges of the electric pulses strongly affect the line shapes of the Förster resonances, since the population transfer at the resonances occurs on a time scale of ∼100 ns, which is comparable with the duration of the transients. For example, a short-term ringing at a certain frequency causes additional radio-frequency-assisted Förster resonances, while nonsharp edges lead to asymmetry. The intentional application of the radio-frequency field induces transitions between collective states, whose line shape depends on the interaction strengths and time. Spatial averaging over the atom positions in a single interaction volume yields a cusped line shape of the Förster resonance. We present a detailed experimental and theoretical analysis of the line shape and time dynamics of the Stark-tuned Förster resonances Rb(nP3/2)+Rb(nP3/2)→Rb(nS1/2)+Rb([n+1]S1/2) for two Rb Rydberg atoms interacting in a time-varying electric field.

  7. Efficiency enhancement of slow-wave electron-cyclotron maser by a second-order shaping of the magnetic field in the low-gain limit

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Si-Jia; Zhang, Yu-Fei; Wang, Kang [School of Science, Beijing University of Chemical Technology, Beijing 100029 (China); Li, Yong-Ming [Information Science and Engineering College, XinJiang University, Urumqi XinJiang 830046 (China); Jing, Jian, E-mail: jingjian@mail.buct.edu.cn [School of Science, Beijing University of Chemical Technology, Beijing 100029 (China)

    2017-03-15

    Based on the anomalous Doppler effect, we put forward a proposal to enhance the conversion efficiency of the slow-wave electron cyclotron masers (ECM) under the resonance condition. Compared with previous studies, we add a second-order shaping term in the guild magnetic field. Theoretical analyses and numerical calculations show that it can enhance the conversion efficiency in the low-gain limit. The case of the initial velocity spread of electrons satisfying the Gaussian distribution is also analysed numerically.

  8. An Application of Artificial Intelligence for the Joint Estimation of Amplitude and Two-Dimensional Direction of Arrival of Far Field Sources Using 2-L-Shape Array

    OpenAIRE

    Fawad Zaman; Ijaz Mansoor Qureshi; Junaid Ali Khan; Zafar Ullah Khan

    2013-01-01

    An easy and efficient approach, based on artificial intelligence technique, is proposed to jointly estimate the amplitude, elevation, and azimuth angles of far field sources impinging on 2-L-shape array. In these proposed artificial intelligence techniques, the metaheuristics based on genetic algorithm and simulated annealing are used as global optimizers assisted with rapid local version of pattern search for optimization of the adaptive parameters. The performance metric is employed on a fi...

  9. Magnetic field hysteresis under various sweeping rates for Ni-Co-Mn-In metamagnetic shape memory alloys

    Science.gov (United States)

    Xu, Xiao; Kihara, Takumi; Tokunaga, Masashi; Matsuo, Akira; Ito, Wataru; Umetsu, Rie Y.; Kindo, Koichi; Kainuma, Ryosuke

    2013-09-01

    Magnetic field-induced transition of Ni45Co5Mn36.7In13.3 was investigated under magnetic fields with different sweeping rates. A static magnetic field produced by a superconducting magnet, a semi-static magnetic field created by a flywheel DC generator-powered magnet, and a pulsed magnetic field resulting from a condenser bank-powered magnet were used in this study, which covers sweeping rates of more than 6 orders. The magnetic field hysteresis is enlarged with increasing sweeping rate. The experimental results were consistent with a phenomenological model, and the activation energy for the thermally activated process was determined to be 0.7 eV for this alloy.

  10. Magnetic Field-Induced Phase Transformation in Magnetic Shape Memory Alloys with High Actuation Stress and Work Output

    Science.gov (United States)

    2010-05-03

    H.E., Gama , S., and Brown, D.E., “High-Energy Synchrotron X- Ray Diffraction for In-Situ Study of Structural Phase Transformations,” Symposium on...J, Maier HJ, Karaman I, Karaca HE, and Chumlyakov YI, “On the Role of Cooling Rate and Crystallographic Orientation on the Shape Memory Properties of...Mechanisms for Advanced Properties in Phase Transforming Materials, Materials Science & Technology 2009 Conference, October 25-29, 2009, Pittsburgh, PA

  11. Noninvasive bipolar double-pulsed-field-gradient NMR reveals signatures for pore size and shape in polydisperse, randomly oriented, inhomogeneous porous media.

    Science.gov (United States)

    Shemesh, Noam; Ozarslan, Evren; Adiri, Tal; Basser, Peter J; Cohen, Yoram

    2010-07-28

    Noninvasive characterization of pore size and shape in opaque porous media is a formidable challenge. NMR diffusion-diffraction patterns were found to be exceptionally useful for obtaining such morphological features, but only when pores are monodisperse and coherently placed. When locally anisotropic pores are randomly oriented, conventional diffusion NMR methods fail. Here, we present a simple, direct, and general approach to obtain both compartment size and shape even in such settings and even when pores are characterized by internal field gradients. Using controlled porous media, we show that the bipolar-double-pulsed-field-gradient (bp-d-PFG) methodology yields diffusion-diffraction patterns from which pore size can be directly obtained. Moreover, we show that pore shape, which cannot be obtained by conventional methods, can be directly inferred from the modulation of the signal in angular bp-d-PFG experiments. This new methodology significantly broadens the types of porous media that can be studied using noninvasive diffusion-diffraction NMR.

  12. Unique visible-light-assisted field emission of tetrapod-shaped ZnO/reduced graphene-oxide core/coating nanocomposites

    Science.gov (United States)

    Wu, Chaoxing; Kim, Tae Whan; Guo, Tailiang; Li, Fushan

    2016-12-01

    The electronic and the optoelectronic properties of graphene-based nanocomposites are controllable, making them promising for applications in diverse electronic devices. In this work, tetrapod-shaped zinc oxide (T-ZnO)/reduced graphene oxide (rGO) core/coating nanocomposites were synthesized by using a hydrothermal-assisted self-assemble method, and their optical, photoelectric, and field-emission properties were investigated. The ZnO, an ideal ultraviolet-light-sensitive semiconductor, was observed to have high sensitivity to visible light due to the rGO coating, and the mechanism of that sensitivity was investigated. We demonstrated for the first time that the field-emission properties of the T-ZnO/rGO core/coating nanocomposites could be dramatically enhanced under visible light by decreasing the turn-on field from 1.54 to 1.41 V/μm and by increasing the current density from 5 to 12 mA/cm2 at an electric field of 3.5 V/μm. The visible-light excitation induces an electron jump from oxygen vacancies on the surface of ZnO to the rGO layer, resulting in a decrease in the work function of the rGO and an increase in the emission current. Furthermore, a field-emission light-emitting diode with a self-enhanced effect was fabricated making full use of the photo-assisted field-emission process.

  13. A Nuanced Look at Women in STEM Fields at Two-Year Colleges: Factors That Shape Female Students' Transfer Intent.

    Science.gov (United States)

    Wang, Xueli; Chan, Hsun-Yu; Soffa, Sara Jimenez; Nachman, Brett Ranon

    2017-01-01

    In this study, we explored the relationship between the intent to transfer upward and a set of motivational, contextual, and socio-demographic background factors among 696 female students beginning in science, technology, engineering, and mathematics (STEM) programs or courses at two-year colleges in a Midwestern state. Drawing upon survey data and administrative records, our multinomial logistic regression analysis revealed that students' math and science self-efficacy beliefs, as well as transfer-oriented interaction, were significant and positive predictors for their intent to transfer into STEM fields as opposed to having no intent to transfer. In addition, the association between transfer intent and these key motivational and contextual factors was moderated by students' racial/ethnic backgrounds, marital status, and childcare obligations. For example, despite the positive relationship between transfer-oriented interaction and the intention to transfer into STEM fields, Black women were less likely to have intent to transfer into STEM fields than White students until Black students reported a moderate level of transfer-oriented interaction. Conversely, Hispanic students were more likely to report intent to transfer into STEM fields than their White peers, even when Hispanic students reported a relatively low level of engagement in transfer-oriented interaction. These and other reported findings bear important and nuanced implications as policymakers, educators, and researchers continue to discover ways to better support women's educational pathways and success in STEM fields at and through two-year colleges.

  14. A Nuanced Look at Women in STEM Fields at Two-Year Colleges: Factors That Shape Female Students' Transfer Intent

    Science.gov (United States)

    Wang, Xueli; Chan, Hsun-yu; Soffa, Sara Jimenez; Nachman, Brett Ranon

    2017-01-01

    In this study, we explored the relationship between the intent to transfer upward and a set of motivational, contextual, and socio-demographic background factors among 696 female students beginning in science, technology, engineering, and mathematics (STEM) programs or courses at two-year colleges in a Midwestern state. Drawing upon survey data and administrative records, our multinomial logistic regression analysis revealed that students' math and science self-efficacy beliefs, as well as transfer-oriented interaction, were significant and positive predictors for their intent to transfer into STEM fields as opposed to having no intent to transfer. In addition, the association between transfer intent and these key motivational and contextual factors was moderated by students' racial/ethnic backgrounds, marital status, and childcare obligations. For example, despite the positive relationship between transfer-oriented interaction and the intention to transfer into STEM fields, Black women were less likely to have intent to transfer into STEM fields than White students until Black students reported a moderate level of transfer-oriented interaction. Conversely, Hispanic students were more likely to report intent to transfer into STEM fields than their White peers, even when Hispanic students reported a relatively low level of engagement in transfer-oriented interaction. These and other reported findings bear important and nuanced implications as policymakers, educators, and researchers continue to discover ways to better support women's educational pathways and success in STEM fields at and through two-year colleges. PMID:28220102

  15. Lower critical fields in an ellipsoid-shaped YBa[sub 2]Cu[sub 3]O[sub 6. 95] single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Liang, R.; Dosanjh, P.; Bonn, D.A.; Hardy, W.N. (Department of Physics, University of British Columbia, Vancouver, British Columbia, V6T1Z1 (Canada)); Berlinsky, A.J. (Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S4M1 (Canada))

    1994-08-01

    The lower critical fields of YBa[sub 2]Cu[sub 3]O[sub 6.95] have been determined by magnetization [ital M]([ital H]) measurements using an ellipsoidal-shaped crystal and a thin platelet for [bold H][parallel][ital c] and [bold H][perpendicular][ital c], respectively. Careful data analysis rules out the effects of surface barriers. The data show a linear temperature dependence of [ital H][sub [ital c]1] below about 0.5[ital T][sub [ital c

  16. Measuring unintended effects in peacebuilding: What the field of international cooperation can learn from innovative approaches shaped by complex contexts.

    Science.gov (United States)

    Lemon, Adrienne; Pinet, Mélanie

    2017-09-23

    Capturing unintended impacts has been a persistent struggle in all fields of international development, and the field of peacebuilding is no exception. However, because peacebuilding focuses on relationships in complex contexts, the field of peacebuilding has, by necessity, made efforts towards finding practical ways to reflect upon both the intended and unintended effects of this work. To explore what lessons can be learned from the peacebuilding field, this study examines the evaluations of Search for Common Ground, a peacebuilding organisation working in over 35 countries across the world. Analysis focuses on 96 evaluations completed between 2013 and 2016 in 24 countries across Africa, Asia, and the MENA regions that found unintended effects. Programmes focusing on women, youth, and radio were most effective at identifying and explaining unintended effects, likely because the project design guided broader lines of questioning from the beginning. The paper argues that OECD-DAC guidelines are not enough on their own to guide evaluators into exploration of unintended effects, and teams instead need to work together to decide where, when and how they will look for them. Different approaches were also used to capture positive and negative outcomes, suggesting that evaluators need to decide at what level they are evaluating and how to tie effects back to the project's contribution. This study explores evaluation techniques and approaches used to understand impact in complex contexts in the peacebuilding field, and draws on lessons learned for the benefit of other fields dealing with similar complexities in international development and cooperation among actors. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Tailoring the pulse shape to efficiently populate atomic electron metastable states in a relativistically intense high-frequency laser field

    Science.gov (United States)

    Emelin, M. Yu.; Smirnov, L. A.; Ryabikin, M. Yu.

    2017-10-01

    The results of both quantum-mechanical numerical calculations beyond the electric dipole approximation and relativistic classical Monte Carlo simulations are presented for a ground-state hydrogen atom exposed to a high-frequency circularly polarized laser field in a wide intensity range. The persistence of the light-induced metastable bound states well into the relativistic regime of laser-atom interaction is demonstrated. The feasibility of high-efficiency electron trapping into these metastable states is examined in the frame of a simple two-stage scenario for a laser field turning on. The optimal parameters of the laser pulse front are found, which provide an optimal balance between the needs to achieve as quickly as possible the higher intensities, for which the decay rate of the metastable states is lower, and to ensure sufficient adiabaticity of the field turning on to avoid the unwanted "shake-off" processes. As a result, more than 60% probability of electron trapping into the metastable states in a relativistically intense high-frequency laser field is demonstrated.

  18. Nudging children towards whole wheat bread: a field experiment on the influence of fun bread roll shape on breakfast consumption

    NARCIS (Netherlands)

    Kleef, van E.; Vrijhof, M.N.; Polet, I.A.; Vingerhoeds, M.H.; Wijk, de R.A.

    2014-01-01

    Background: Many children do not eat enough whole grains, which may have negative health consequences. Intervention research is increasingly focusing on nudging as a way to influence food choices by affecting unconscious behavioural processes. The aim of this field study was to examine whether the

  19. U-shaped Ladder TEM-Coil Structure with Truncated Sensitivity Profile in z-Direction for High Field MRI

    NARCIS (Netherlands)

    Leussler, C.; Wirtz, D.; Wuelbern, J.H.; Vernickel, P.; Forthmann, P.

    2012-01-01

    Conventional TEM-coils [1] come with a sensitivity profile and field-of view (FOV) that is largely extended in the z-direction comparedwith birdcage coils (BC) [2]. There is an analog situation when comparing TEM coil arrays [3] and degenerate birdcages (DBC) [4]. The excess z-FOV leads to safety

  20. An Application of Artificial Intelligence for the Joint Estimation of Amplitude and Two-Dimensional Direction of Arrival of Far Field Sources Using 2-L-Shape Array

    Directory of Open Access Journals (Sweden)

    Fawad Zaman

    2013-01-01

    Full Text Available An easy and efficient approach, based on artificial intelligence technique, is proposed to jointly estimate the amplitude, elevation, and azimuth angles of far field sources impinging on 2-L-shape array. In these proposed artificial intelligence techniques, the metaheuristics based on genetic algorithm and simulated annealing are used as global optimizers assisted with rapid local version of pattern search for optimization of the adaptive parameters. The performance metric is employed on a fitness evaluation function depending on mean square error which is optimum and requires single snapshot to converge. The proposed approaches are easy to understand, and simple to implement; the genetic algorithm specifically hybridized with pattern search generates fairly good results. The comparison of the given schemes is carried out with 1-L-shape array, as well as, with parallel-shape array and is found to be in good agreement in terms of accuracy, convergence rate, computational complexity, and mean square error. The effectiveness and efficiency of the given schemes are examined through Monte Carlo simulations and their inclusive statistical analysis.

  1. Perspectives in shape analysis

    CERN Document Server

    Bruckstein, Alfred; Maragos, Petros; Wuhrer, Stefanie

    2016-01-01

    This book presents recent advances in the field of shape analysis. Written by experts in the fields of continuous-scale shape analysis, discrete shape analysis and sparsity, and numerical computing who hail from different communities, it provides a unique view of the topic from a broad range of perspectives. Over the last decade, it has become increasingly affordable to digitize shape information at high resolution. Yet analyzing and processing this data remains challenging because of the large amount of data involved, and because modern applications such as human-computer interaction require real-time processing. Meeting these challenges requires interdisciplinary approaches that combine concepts from a variety of research areas, including numerical computing, differential geometry, deformable shape modeling, sparse data representation, and machine learning. On the algorithmic side, many shape analysis tasks are modeled using partial differential equations, which can be solved using tools from the field of n...

  2. Giant low-field magnetic entropy changes in Ni45Mn44-xCrxSn11 ferromagnetic shape memory alloys

    Science.gov (United States)

    Zhang, C. L.; Zou, W. Q.; Xuan, H. C.; Han, Z. D.; Wang, D. H.; Gu, B. X.; Du, Y. W.

    2007-12-01

    A series of Ni45Mn44-xCrxSn11 (x = 0, 1, 2) ferromagnetic shape memory alloys were prepared. With slight doping of Cr, the martensitic transition temperatures decrease rapidly. The magnetic entropy changes at a low magnetic field were investigated in these alloys. The maximum value of ΔSM is 23.4 J kg-1 K-1, which was observed in Ni45Mn43CrSn11 alloys. The origin of the magnetic entropy changes in these alloys has been discussed. The giant low-field magnetic entropy changes and low cost make Ni45Mn44-xCrxSn11 alloys a promising candidate for magnetic refrigeration.

  3. Mechanism of spin crossover in LaCoO3 resolved by shape magnetostriction in pulsed magnetic fields

    Science.gov (United States)

    Rotter, M.; Wang, Z.-S.; Boothroyd, A. T.; Prabhakaran, D.; Tanaka, A.; Doerr, M.

    2014-11-01

    In the scientific description of unconventional transport properties of oxides (spin-dependent transport, superconductivity etc.), the spin-state degree of freedom plays a fundamental role. Because of this, temperature- or magnetic field-induced spin-state transitions are in the focus of solid-state physics. Cobaltites, e.g. LaCoO3, are prominent examples showing these spin transitions. However, the microscopic nature of the spontaneous spin crossover in LaCoO3 is still controversial. Here we report magnetostriction measurements on LaCoO3 in magnetic fields up to 70 T to study the sharp, field-induced transition at Hc ~ 60 T. Measurements of both longitudinal and transversal magnetostriction allow us to separate magnetovolume and magnetodistortive changes. We find a large increase in volume, but only a very small increase in tetragonal distortion at Hc. The results, supported by electronic energy calculations by the configuration interaction cluster method, provide compelling evidence that above Hc LaCoO3 adopts a correlated low spin/high spin state.

  4. Lehr's fields of campaniform sensilla in beetles (Coleoptera): functional morphology. III. Modification of elytral mobility or shape in flying beetles.

    Science.gov (United States)

    Frantsevich, Leonid; Gorb, Stanislav; Radchenko, Vladimir; Gladun, Dmytro

    2015-03-01

    Some flying beetles have peculiar functional properties of their elytra, if compared with the vast majority of beetles. A "typical" beetle covers its pterothorax and the abdomen from above with closed elytra and links closed elytra together along the sutural edges. In the open state during flight, the sutural edges diverge much more than by 90°. Several beetles of unrelated taxa spread wings through lateral incisions on the elytra and turn the elytron during opening about 10-12° (Cetoniini, Scarabaeus, Gymnopleurus) or elevate their elytra without partition (Sisyphus, Tragocerus). The number of campaniform sensilla in their elytral sensory field is diminished in comparison with beetles of closely related taxa lacking that incision. Elytra are very short in rove beetles and in long-horn beetles Necydalini. The abundance of sensilla in brachyelytrous long-horn beetles Necydalini does not decrease in comparison with macroelytrous Cerambycinae. Strong reduction of the sensory field was found in brachyelytrous Staphylinidae. Lastly, there are beetles lacking the linkage of the elytra down the sutural edge (stenoelytry). Effects of stenoelytry were also not uniform: Oedemera and flying Meloidae have the normal amount of sensilla with respect to their body size, whereas the sensory field in the stenoelytrous Eulosia bombyliformis is 5-6 times less than in chafers of the same size but with normally linking broad elytra. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Low-Programmable-Voltage Nonvolatile Memory Devices Based on Omega-shaped Gate Organic Ferroelectric P(VDF-TrFE) Field Effect Transistors Using p-type Silicon Nanowire Channels

    National Research Council Canada - National Science Library

    Ngoc Huynh Van Jae-Hyun Lee Dongmok Whang Dae Joon Kang

    2015-01-01

    A facile approach was demonstrated for fabricating high-performance nonvolatile memory devices based on ferroelectric-gate field effect transistors using a p-type Si nanowire coated with omega-shaped...

  6. Intercostal high intensity focused ultrasound for liver ablation: The influence of beam shaping on sonication efficacy and near-field risks

    Energy Technology Data Exchange (ETDEWEB)

    Greef, M. de, E-mail: m.degreef@umcutrecht.nl; Wijlemans, J. W.; Bartels, L. W.; Moonen, C. T. W.; Ries, M. [Imaging Division, University Medical Center Utrecht, Utrecht 3508GA (Netherlands); Schubert, G.; Koskela, J. [Philips Healthcare, Vantaa FI-01511 (Finland)

    2015-08-15

    Purpose: One of the major issues in high intensity focused ultrasound ablation of abdominal lesions is obstruction of the ultrasound beam by the thoracic cage. Beam shaping strategies have been shown by several authors to increase focal point intensity while limiting rib exposure. However, as rib obstruction leaves only part of the aperture available for energy transmission, conserving total emitted acoustic power, the intensity in the near-field tissues inherently increases after beam shaping. Despite of effective rib sparing, those tissues are therefore subjected to increased risk of thermal damage. In this study, for a number of clinically representative intercostal sonication geometries, modeling clinically available hardware, the effect of beam shaping on both the exposure of the ribs and near-field to acoustic energy was evaluated and the implications for the volumetric ablation rate were addressed. Methods: A relationship between rib temperature rise and acoustic energy density was established by means of in vivo MR thermometry and simulations of the incident acoustic energy for the corresponding anatomies. This relationship was used for interpretation of rib exposure in subsequent numerical simulations in which rib spacing, focal point placement, and the focal point trajectory were varied. The time required to heat a targeted region to 65 °C was determined without and with the application of beam shaping. The required sonication time was used to calculate the acoustic energy density at the fat–muscle interface and at the surface of the ribs. At the fat–muscle interface, exposure was compared to available literature data and rib exposure was interpreted based on the earlier obtained relation between measured temperature rise and simulated acoustic energy density. To estimate the volumetric ablation rate, the cool-down time between periods of energy exposure was estimated using a time-averaged power limit of 100 kJ/h. Results: At the level of the ribs

  7. Using baseline-dependent window functions for data compression and field-of-interest shaping in radio interferometry

    Science.gov (United States)

    Atemkeng, M. T.; Smirnov, O. M.; Tasse, C.; Foster, G.; Jonas, J.

    2016-11-01

    In radio interferometry, observed visibilities are intrinsically sampled at some interval in time and frequency. Modern interferometers are capable of producing data at very high time and frequency resolution; practical limits on storage and computation costs require that some form of data compression be imposed. The traditional form of compression is a simple averaging of the visibilities over coarser time and frequency bins. This has an undesired side effect: the resulting averaged visibilities `decorrelate', and do so differently depending on the baseline length and averaging interval. This translates into a non-trivial signature in the image domain known as `smearing', which manifests itself as an attenuation in amplitude towards off-centre sources. With the increasing fields of view and/or longer baselines employed in modern and future instruments, the trade-off between data rate and smearing becomes increasingly unfavourable. In this work, we investigate alternative approaches to low-loss data compression. We show that averaging of the visibility data can be treated as a form of convolution by a boxcar-like window function, and that by employing alternative baseline-dependent window functions a more optimal interferometer smearing response may be induced. In particular, we show improved amplitude response over a chosen field of interest, and better attenuation of sources outside the field of interest. The main cost of this technique is a reduction in nominal sensitivity; we investigate the smearing versus sensitivity trade-off, and show that in certain regimes a favourable compromise can be achieved. We show the application of this technique to simulated data from the Karl G. Jansky Very Large Array (VLA) and the European Very-long-baseline interferometry Network (EVN).

  8. Speed hysteresis and noise shaping of traveling fronts in neural fields: role of local circuitry and nonlocal connectivity

    Science.gov (United States)

    Capone, Cristiano; Mattia, Maurizio

    2017-01-01

    Neural field models are powerful tools to investigate the richness of spatiotemporal activity patterns like waves and bumps, emerging from the cerebral cortex. Understanding how spontaneous and evoked activity is related to the structure of underlying networks is of central interest to unfold how information is processed by these systems. Here we focus on the interplay between local properties like input-output gain function and recurrent synaptic self-excitation of cortical modules, and nonlocal intermodular synaptic couplings yielding to define a multiscale neural field. In this framework, we work out analytic expressions for the wave speed and the stochastic diffusion of propagating fronts uncovering the existence of an optimal balance between local and nonlocal connectivity which minimizes the fluctuations of the activation front propagation. Incorporating an activity-dependent adaptation of local excitability further highlights the independent role that local and nonlocal connectivity play in modulating the speed of propagation of the activation and silencing wavefronts, respectively. Inhomogeneities in space of local excitability give raise to a novel hysteresis phenomenon such that the speed of waves traveling in opposite directions display different velocities in the same location. Taken together these results provide insights on the multiscale organization of brain slow-waves measured during deep sleep and anesthesia.

  9. Binaural inhibition is important in shaping the free-field frequency selectivity of single neurons in the inferior colliculus.

    Science.gov (United States)

    Gooler, D M; Xu, J; Feng, A S

    1996-10-01

    1. We have shown previously that under free-field stimulation in the frontal field, frequency selectivity of the majority of inferior colliculus (IC) neurons became sharper when the loudspeaker was shifted to ipsilateral azimuths. These results indicated that binaural inhibition may be responsible for the direction-dependent sharpening of frequency selectivity. To test the above hypothesis directly, we investigated the frequency selectivity of IC neurons under several conditions: monaural stimulation using a semiclosed acoustical stimulation system, binaural stimulation dichotically also using a semiclosed system, free-field stimulation from different azimuths, and free-field stimulation when the ipsilateral ear was occluded monaurally (coated with a thick layer of petroleum jelly, which effectively attenuated acoustic input to this ear). 2. The binaural interaction pattern of 98 IC neurons of northern leopard frogs (Rana pipiens pipiens) were evaluated; of these neurons, there were 34 EE and 64 EO neurons. The majority of IC neurons (92 of 98) showed some degree of binaural inhibition (i.e., showing diminished response when the ipsilateral and contralateral ears were stimulated simultaneously) whether they were designated as EE or EO; these IC neurons thus were classified as EE-I or EO-I. Neurons were classified as exhibiting strong inhibition if the ILD function showed a pronounced response decrement, i.e., a decrease of > or = 50% of the response to monaural stimulation of the contralateral ear. Those neurons that showed smaller response decrements (decrease was > or = 25% but neurons (n = 68) showed strong binaural inhibition. 3. In agreement with results from our earlier studies, frequency threshold curves (FTCs) of IC neurons were altered by sound azimuth. Independent of binaural interaction pattern, most IC neurons (59 of 98) showed a narrowing of the FTC as sound direction was changed from contralateral 90 deg (c90 degrees) to ipsilateral 90 deg (i90

  10. Unique visible-light-assisted field emission of tetrapod-shaped ZnO/reduced graphene-oxide core/coating nanocomposites

    Science.gov (United States)

    Wu, Chaoxing; Kim, Tae Whan; Guo, Tailiang; Li, Fushan

    2016-01-01

    The electronic and the optoelectronic properties of graphene-based nanocomposites are controllable, making them promising for applications in diverse electronic devices. In this work, tetrapod-shaped zinc oxide (T-ZnO)/reduced graphene oxide (rGO) core/coating nanocomposites were synthesized by using a hydrothermal-assisted self-assemble method, and their optical, photoelectric, and field-emission properties were investigated. The ZnO, an ideal ultraviolet-light-sensitive semiconductor, was observed to have high sensitivity to visible light due to the rGO coating, and the mechanism of that sensitivity was investigated. We demonstrated for the first time that the field-emission properties of the T-ZnO/rGO core/coating nanocomposites could be dramatically enhanced under visible light by decreasing the turn-on field from 1.54 to 1.41 V/μm and by increasing the current density from 5 to 12 mA/cm2 at an electric field of 3.5 V/μm. The visible-light excitation induces an electron jump from oxygen vacancies on the surface of ZnO to the rGO layer, resulting in a decrease in the work function of the rGO and an increase in the emission current. Furthermore, a field-emission light-emitting diode with a self-enhanced effect was fabricated making full use of the photo-assisted field-emission process. PMID:27941822

  11. Effect of Aspect Ratio and Boundary Conditions in Modeling Shape Memory Alloy Nanostructures with 3D Coupled Dynamic Phase-Field Theories

    Directory of Open Access Journals (Sweden)

    R. Dhote

    2016-01-01

    Full Text Available The behavior of shape memory alloy (SMA nanostructures is influenced by strain rate and temperature evolution during dynamic loading. The coupling between temperature, strain, and strain rate is essential to capture inherent thermomechanical behavior in SMAs. In this paper, we propose a new 3D phase-field model that accounts for two-way coupling between mechanical and thermal physics. We use the strain-based Ginzburg-Landau potential for cubic-to-tetragonal phase transformations. The variational formulation of the developed model is implemented in the isogeometric analysis framework to overcome numerical challenges. We have observed a complete disappearance of the out-of-plane martensitic variant in a very high aspect ratio SMA domain as well as the presence of three variants in equal portions in a low aspect ratio SMA domain. The dependence of different boundary conditions on the microstructure morphology has been examined energetically. The tensile tests on rectangular prism nanowires, using the displacement based loading, demonstrate the shape memory effect and pseudoelastic behavior. We have also observed that higher strain rates, as well as the lower aspect ratio domains, resulting in high yield stress and phase transformations occur at higher stress during dynamic axial loading.

  12. Three-dimensional shapes and distribution of FePd nanoparticles observed by electron tomography using high-angle annular dark-field scanning transmission electron microscopy

    Science.gov (United States)

    Sato, Kazuhisa; Aoyagi, Kenta; Konno, Toyohiko J.

    2010-01-01

    We have studied three-dimensional shapes and distribution of FePd nanoparticles, prepared by electron beam deposition and postdeposition annealing, by means of single-axis tilt tomography using atomic number contrasts obtained by high-angle annular dark-field scanning transmission electron microscopy. Particle size, shape, and locations were reconstructed by weighted backprojection (WBP), as well as by simultaneous iterative reconstruction technique (SIRT). We have also estimated the particle size by simple extrapolation of tilt-series original data sets, which proved to be quite powerful. The results of the two algorithms for reconstruction have been compared quantitatively with those obtained by the extrapolation method and those independently reported by electron holography. It was found that the reconstructed intensity map by WBP contains a small amount of dotlike artifacts, which do not exist in the results by SIRT, and that the particle surface obtained by WBP is rougher than that by SIRT. We demonstrate, on the other hand, that WBP yields a better estimation of the particle size in the z direction than SIRT does, most likely due to the presence of a "missing wedge" in the original data set.

  13. Simultaneous adaptive control of dual deformable mirrors for full-field beam shaping with the improved stochastic parallel gradient descent algorithm.

    Science.gov (United States)

    Ma, Haotong; Liu, Zejin; Xu, Xiaojun; Chen, Jinbao

    2013-02-01

    We propose and demonstrate the simultaneous adaptive control of a dual deformable mirror system for full-field beam shaping based on an improved stochastic parallel gradient descent (SPGD) algorithm and dual-phase-only liquid crystal spatial light modulators (LC-SLMs). One LC-SLM adaptively redistributes the intensity of the input beam and the other adaptively compensates the wavefront of the output beam. However, the intensity redistribution and wavefront compensation closed loops run simultaneously. In addition, the intensity redistribution and wavefront compensation closed loops adopt their respective metric functions independently. Experimental results show that the improved SPGD algorithm can not only be used for controlling dual deformable mirror configuration to adaptively generate near diffraction-limited flattop beams with desired intensity distributions, but also can greatly improve the control bandwidth.

  14. Cold field emission dominated photoconductivity in ordered three-dimensional assemblies of octapod-shaped CdSe/CdS nanocrystals

    KAUST Repository

    Zhang, Yang

    2013-01-01

    Semiconductor nanocrystals, especially their ordered assemblies, are promising materials for various applications. In this paper, we investigate the photoconductive behavior of sub-micron size, ordered three-dimensional (3D) assemblies of octapod-shaped CdSe/CdS nanocrystals that are contacted by overlay electron-beam lithography. The regular structure of the assemblies leads to photocurrent-voltage curves that can be described by the cold field electron emission model. Mapping of the photoconductivity versus excitation wavelength and bias voltage allows the extraction of the band gap and identification of the photoactive region in the voltage and spectral domain. These results have important implications for the understanding of photoconductive transport in similar systems. © 2013 The Royal Society of Chemistry.

  15. Martensitic transformation and shape memory effect of Ni-rich Ni{sub 2}MnGa sputtered films under magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Ohtsuka, M. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)]. E-mail: ohtsuka@tagen.tohoku.ac.jp; Matsumoto, M. [Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Koike, K. [Department of Basic Technology, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510 (Japan); Takagi, T. [Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Itagaki, K. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2007-03-15

    The inference of a magnetic field on the martensitic transformation (MT) temperatures and shape memory effect (SME) was investigated for the Ni-rich Ni{sub 2}MnGa sputtered films. The compositions of the films were Ni{sub 51.4}Mn{sub 28.3}Ga{sub 20.3}, Ni{sub 54.1}Mn{sub 23.0}Ga{sub 22.9} and Ni{sub 54.4}Mn{sub 21.3}Ga{sub 24.3}. The films were heat treated at 1073 K for 3.6 ks and aged at 673 K for 3.6 ks in a constrained condition. Hereafter, the constraint-aged films were described as N51.4(AG), N54.1(AG) and N54.4(AG) using nickel content, respectively. The reversible two-way SME by the thermal change was confirmed for the all constraint-aged films through the MT and its reversion. The gradient of the strain-temperature curve, the amount of strain accompanied by the two-way SME and the width of thermal hysteresis were dependent on the composition of the films. The strain-temperature curves shifted to a high temperature region and the martensitic phase was stabilized by the magnetic field. The strain at the outer surface was given by {epsilon}=d/2r, where d was the thickness of the films and r was the radius of a curvature for the films. The increase of MT temperatures caused by a magnetic field was about 1 K/T. Furthermore, the two-way SME by the magnetic field was observed around the MT temperature on cooling for the N54.4(AG) film with the large gradient and small thermal hysteresis in the strain-temperature curve.

  16. Midpoint Shapes.

    Science.gov (United States)

    Welchman, Rosamond; Urso, Josephine

    2000-01-01

    Emphasizes the importance of children exploring hands-on and minds-on mathematics. Presents a midpoint shape activity for students to explore the midpoint shape of familiar quadrilaterals, such as squares and rectangles. (KHR)

  17. Optimization of Type-II 'W' shaped InGaAsP/GaAsSb nanoscale-heterostructure under electric field and temperature

    Science.gov (United States)

    Dolia, Richa; Bhardwaj, Garima; Singh, A. K.; Kumar, Shalendra; Alvi, P. A.

    2017-12-01

    Designing of a type-II nanoscale heterostructure and simulating their optical properties is critical for many applications and remains a challenge. This paper reports designing of a complex type - II 'W' shaped symmetric InGaAsP/GaAsSb nano-scale heterostructure grown on InP substrate and mechanism of the transitions taking place within the heterostructure which are responsible for optical properties. In addition, the band alignment, optical gain and lasing wavelength are also studied under the effect of applied external electric field ranging from 10 to 200 kV/cm and variable temperature. On the basis of outcome of the calculations, the proposed heterostructure can be claimed to show a very high optical gain (∼8000/cm) within the MIR (mid infrared) region. Moreover, the results achieved in the study suggest that the application of the both variable temperature and applied external electric field on the heterostructure can control the optical gain as well as lasing wavelength linearly. Due to the linear behavior of the proposed heterostructure, the tunable type -II InGaAsP/GaAsSb nano-scale heterostructure can be claimed as a very suitable heterostructure for the designing of photovoltaic devices operating in the IR region.

  18. An Analysis of the Far-Field Radiation Pattern of the Ultraviolet Light-Emitting Diode (LED) Engin LZ4-00UA00 Diode with and without Beam Shaping Optics

    Science.gov (United States)

    2015-09-01

    SEP 2015 US Army Research Laboratory An Analysis of the Far-Field Radiation Pattern of the Ultraviolet Light - Emitting Diode (LED) Engin...Radiation Pattern of the Ultraviolet Light - Emitting Diode (LED) Engin LZ4-00UA00 Diode with and without Beam Shaping Optics 5a. CONTRACT NUMBER... light - emitting diode (LED), with and without beam shaping optics. This LED has 4 emitters arranged in a square pattern that are off-center from the

  19. [Shaping the future of vocational rehabilitation of adults: eight fields of action as starting points for a cross-actor innovation process].

    Science.gov (United States)

    Riedel, H-P; Ellger-Rüttgardt, S; Karbe, H; Niehaus, M; Rauch, A; Schian, H-M; Schmidt, C; Schott, T; Schröder, H; Spijkers, W; Wittwer, U

    2009-12-01

    Established by the Federal Ministry of Labour and Social Affairs (BMAS) in October 2007, the Scientific Expert Group RehaFutur had been commissioned to elaborate cornerstones for the medium- and long-term development of vocational rehabilitation of adults with disabilities (re-integration). Initial questions inter alia were as follows: Which function should vocational rehabilitation have in a service- and knowledge-oriented working world that will increasingly be affected by demographic change? How can disabled persons' right to occupational participation by way of vocational rehabilitation, a right stipulated both under the German constitution and in German law, be realized as needed also in the future? Various fields of action have been derived on the basis, for one, of an investigation of the factors, social law, social and education policy as well as European, influencing vocational rehabilitation and, for the other, of an evaluation of current labour market and demographic developments. Dealt with in the fields of action outlined are the aspects: equitable opportunities of access, developmental and needs orientation, closeness to the real occupational and working world, as well as the role of self-determination and self-responsibility. The fields of action are to be understood as framework concept for shaping a cross-actor innovation process. Sustainable vocational rehabilitation is characterized in particular by the fact that it is specifically targeted at promoting disabled persons' self-determination and self-responsibility actively using these in the process and that it strengthens an independent lifestyle, ensures social participation by inclusive structures; also, it facilitates continued participation in working life by ongoing education involving holistic development of professional and personal competencies oriented towards the individual's resources and potentials, safeguarding it by systematic networking with companies. The concept presented for

  20. Comparison of extended field-of-view reconstructions in C-arm flat-detector CT using patient size, shape or attenuation information

    Energy Technology Data Exchange (ETDEWEB)

    Kolditz, Daniel; Meyer, Michael; Kyriakou, Yiannis; Kalender, Willi A, E-mail: daniel.kolditz@imp.uni-erlangen.d [Institute of Medical Physics, University of Erlangen-Nuernberg (Germany)

    2011-01-07

    In C-arm-based flat-detector computed tomography (FDCT) it frequently happens that the patient exceeds the scan field of view (SFOV) in the transaxial direction because of the limited detector size. This results in data truncation and CT image artefacts. In this work three truncation correction approaches for extended field-of-view (EFOV) reconstructions have been implemented and evaluated. An FDCT-based method estimates the patient size and shape from the truncated projections by fitting an elliptical model to the raw data in order to apply an extrapolation. In a camera-based approach the patient is sampled with an optical tracking system and this information is used to apply an extrapolation. In a CT-based method the projections are completed by artificial projection data obtained from the CT data acquired in an earlier exam. For all methods the extended projections are filtered and backprojected with a standard Feldkamp-type algorithm. Quantitative evaluations have been performed by simulations of voxelized phantoms on the basis of the root mean square deviation and a quality factor Q (Q = 1 represents the ideal correction). Measurements with a C-arm FDCT system have been used to validate the simulations and to investigate the practical applicability using anthropomorphic phantoms which caused truncation in all projections. The proposed approaches enlarged the FOV to cover wider patient cross-sections. Thus, image quality inside and outside the SFOV has been improved. Best results have been obtained using the CT-based method, followed by the camera-based and the FDCT-based truncation correction. For simulations, quality factors up to 0.98 have been achieved. Truncation-induced cupping artefacts have been reduced, e.g., from 218% to less than 1% for the measurements. The proposed truncation correction approaches for EFOV reconstructions are an effective way to ensure accurate CT values inside the SFOV and to recover peripheral information outside the SFOV.

  1. Comparison of extended field-of-view reconstructions in C-arm flat-detector CT using patient size, shape or attenuation information

    Science.gov (United States)

    Kolditz, Daniel; Meyer, Michael; Kyriakou, Yiannis; Kalender, Willi A.

    2011-01-01

    In C-arm-based flat-detector computed tomography (FDCT) it frequently happens that the patient exceeds the scan field of view (SFOV) in the transaxial direction because of the limited detector size. This results in data truncation and CT image artefacts. In this work three truncation correction approaches for extended field-of-view (EFOV) reconstructions have been implemented and evaluated. An FDCT-based method estimates the patient size and shape from the truncated projections by fitting an elliptical model to the raw data in order to apply an extrapolation. In a camera-based approach the patient is sampled with an optical tracking system and this information is used to apply an extrapolation. In a CT-based method the projections are completed by artificial projection data obtained from the CT data acquired in an earlier exam. For all methods the extended projections are filtered and backprojected with a standard Feldkamp-type algorithm. Quantitative evaluations have been performed by simulations of voxelized phantoms on the basis of the root mean square deviation and a quality factor Q (Q = 1 represents the ideal correction). Measurements with a C-arm FDCT system have been used to validate the simulations and to investigate the practical applicability using anthropomorphic phantoms which caused truncation in all projections. The proposed approaches enlarged the FOV to cover wider patient cross-sections. Thus, image quality inside and outside the SFOV has been improved. Best results have been obtained using the CT-based method, followed by the camera-based and the FDCT-based truncation correction. For simulations, quality factors up to 0.98 have been achieved. Truncation-induced cupping artefacts have been reduced, e.g., from 218% to less than 1% for the measurements. The proposed truncation correction approaches for EFOV reconstructions are an effective way to ensure accurate CT values inside the SFOV and to recover peripheral information outside the SFOV.

  2. Analog/RF performance of L- and U-shaped channel tunneling field-effect transistors and their application as digital inverters

    Science.gov (United States)

    Wang, Qianqiong; Wang, Shulong; Liu, Hongxia; Li, Wei; Chen, Shupeng

    2017-06-01

    The inverter performance comparisons of L- and U-shaped channel tunneling field-effect transistors (LTFET and UTFET) are investigated by using Sentaurus TCAD tool. The RF figures of merit for these two TFETs are analyzed in terms of transconductance (g m), output conductance (g ds), gate capacitance (C gg), gate-to-source capacitance (C gs), gate-to-drain capacitance (C gd), unit-gain cut-off frequency (f T), the maximum frequency of oscillation (f MAX) and gain bandwidth product (GBW). The simulation results reveal that LTFET and UTFET have the similar DC characteristic due to the identical tunneling process. And the better RF performance LTFET provides due to it has the much smaller C gd than UTFET. Meanwhile, this work uses mixed device-circuit simulations to predict the performance of inverter circuit implemented with LTFET and UTFET for the first time. And the calculated results demonstrate LTFET is more optimization for inverter circuit design in the novel generation transistors. And all the simulation results in this paper can be used as a reference to choose the characteristic parameters of novel TFETs for inverter applications.

  3. Cross-Sectional Channel Shape Dependence of Short-Channel Effects in Fin-Type Double-Gate Metal Oxide Semiconductor Field-Effect Transistors

    Science.gov (United States)

    Liu, Yongxun; Ishii, Kenichi; Masahara, Meishoku; Tsutsumi, Toshiyuki; Takashima, Hidenori; Yamauchi, Hiromi; Suzuki, Eiichi

    2004-04-01

    The dependence of short-channel effects (SCEs) on the cross-sectional channel shape of the fin-type double-gate metal oxide semiconductor field-effect transistors (MOSFETs) has been experimentally investigated from the viewpoint of fin fabrication. The three types of fin-type double-gate MOSFETs (FinFETs) with a rectangular-cross-section channel on a (110)-oriented silicon-on-insulator (SOI) wafer, and a triangular and trapezoidal channels on a (100)-oriented SOI wafer were fabricated using the same orientation-dependent wet etching process. The experimental results show that the SCEs in rectangular-cross-section silicon (Si)-fin channel devices are well suppressed compared with those in a triangular or a trapezoidal Si-fin channel device fabricated using a similar mask pattern, in the regimes of the gate length of less than 85 nm and Si fin height of larger than 65 nm. The presented experimental results are valuable for FinFET design and fabrication.

  4. Shape analysis in medical image analysis

    CERN Document Server

    Tavares, João

    2014-01-01

    This book contains thirteen contributions from invited experts of international recognition addressing important issues in shape analysis in medical image analysis, including techniques for image segmentation, registration, modelling and classification, and applications in biology, as well as in cardiac, brain, spine, chest, lung and clinical practice. This volume treats topics such as, anatomic and functional shape representation and matching; shape-based medical image segmentation; shape registration; statistical shape analysis; shape deformation; shape-based abnormity detection; shape tracking and longitudinal shape analysis; machine learning for shape modeling and analysis; shape-based computer-aided-diagnosis; shape-based medical navigation; benchmark and validation of shape representation, analysis and modeling algorithms. This work will be of interest to researchers, students, and manufacturers in the fields of artificial intelligence, bioengineering, biomechanics, computational mechanics, computationa...

  5. The role of predation in variation in body shape in guppies Poecilia reticulata: a comparison of field and common garden phenotypes.

    Science.gov (United States)

    Burns, J G; Di Nardo, P; Rodd, F H

    2009-10-01

    The body shapes of both wild-caught and laboratory-reared male and female Trinidadian guppies Poecilia reticulata from two low-predation and two high-predation populations were studied, but predation regime did not seem to be the most important factor affecting body shape. Instead, complicated patterns of plasticity in body shape among populations and the sexes were found. In particular, populations differed in the depth of the caudal peduncle, which is the muscular region just anterior to the tail fin rays and from which most swimming power is generated. Strikingly, the direction of population differences in caudal peduncle depth observed in wild-caught individuals was reversed when P. reticulata were raised in a common laboratory environment.

  6. Dynamic shape.

    Science.gov (United States)

    Koenderink, J J; van Doorn, A J

    1986-01-01

    Many useful notions of partial order and/or similarity and relatedness of different geometrical features of smooth shapes that occur in psychologically valid descriptions of shape have no equivalents in the usual geometrical shape theories. This is especially true where similarities are noted between objects of different connectivity: in almost all of the present theories the topological type generates the primary categorization. It is argued that such relations find a logical place only in shape theories that involve morphogenesis. Any object can be embedded uniquely in a morphogenetic sequence if one takes resolution as the parameter of the sequence. A theory of measurement is presented that allows one to define surfaces and (boundary-) curves on multiple levels of resolution. The embedding is essentially unique and is generated via a partial differential equation that governs the evolution. A canonical projection connects any high resolution specimen to lower resolution versions. The bifurcation set of the projection generates natural part boundaries. Singularities of the evolution are completely characterized as emergence, accretion and versification processes (involving topological change) and singularities by which inflections (inflection points for curves, parabolic curves for surfaces) are generated. The latter singularities involve a single process for the generation of inflections and three other processes by which the existing inflection structure may be changed. Relations with existing theories in vogue in robotics and AI, as well as in psychophysics are discussed.

  7. Intercostal high intensity focused ultrasound for liver ablation : The influence of beam shaping on sonication efficacy and near-field risks

    NARCIS (Netherlands)

    de Greef, M.; Schubert, G.; Wijlemans, J. W.; Koskela, J.; Bartels, L. W.; Moonen, C. T. W.; Ries, M.

    Purpose: One of the major issues in high intensity focused ultrasound ablation of abdominal lesions is obstruction of the ultrasound beam by the thoracic cage. Beam shaping strategies have been shown by several authors to increase focal point intensity while limiting rib exposure. However, as rib

  8. Ring-shaped velocity distribution functions in energy-dispersed structures formed at the boundaries of a proton stream injected into a transverse magnetic field: Test-kinetic results

    CERN Document Server

    Voitcu, Gabriel

    2016-01-01

    In this paper, we discuss the formation of ring-shaped and gyro-phase restricted velocity distribution functions (VDFs) at the edges of a cloud of protons injected into non-uniform distributions of the electromagnetic field. The velocity distribution function is reconstructed using the forward test-kinetic method. We consider two profiles of the electric field: (1) a non-uniform E-field obtained by solving the Laplace equation consistent with the conservation of the electric drift and (2) a constant and uniform E-field. In both cases, the magnetic field is similar to the solutions obtained for tangential discontinuities. The initial velocity distribution function is Liouville mapped along numerically integrated trajectories. The numerical results show the formation of an energy-dispersed structure due to the energy-dependent displacement of protons towards the edges of the cloud by the gradient-B drift. Another direct effect of the gradient-B drift is the formation of ring-shaped velocity distribution functio...

  9. Magnetic shape memory: Magnetoelastic sponges

    Science.gov (United States)

    Acet, Mehmet

    2009-11-01

    Nickel-manganese-gallium foams connected internally by sizeable single-crystalline elements provide magnetic-field-induced strains comparable to free-standing bulk single crystals, and demonstrate feasibility for the application of magnetic shape memory.

  10. Laser beam shaping techniques

    Energy Technology Data Exchange (ETDEWEB)

    DICKEY,FRED M.; WEICHMAN,LOUIS S.; SHAGAM,RICHARD N.

    2000-03-16

    Industrial, military, medical, and research and development applications of lasers frequently require a beam with a specified irradiance distribution in some plane. A common requirement is a laser profile that is uniform over some cross-section. Such applications include laser/material processing, laser material interaction studies, fiber injection systems, optical data image processing, lithography, medical applications, and military applications. Laser beam shaping techniques can be divided into three areas: apertured beams, field mappers, and multi-aperture beam integrators. An uncertainty relation exists for laser beam shaping that puts constraints on system design. In this paper the authors review the basics of laser beam shaping and present applications and limitations of various techniques.

  11. Metal release in a stainless steel Pulsed Electric Field (PEF) system Part I. Effect of different pulse shapes; theory and experimental method

    NARCIS (Netherlands)

    Roodenburg, B.; Morren, J.; Berg, H.E.; Haan, S.W.H.de

    2005-01-01

    Liquid pumpable food is mostly pasteurised by heat treatment. In the last decennia there is an increasing interest in so-called Pulsed Electric Field (PEF) treatment. During this treatment food is pumped between two metal electrodes and exposed to short high electric field pulses, typical 2-4 kV

  12. Eye shape and peripheral visual field recording in high myopia at approximately 54 years of age, as based on ultrasonography and Goldmann kinetic perimetry

    DEFF Research Database (Denmark)

    Fledelius, Hans C; Goldschmidt, Ernst

    2010-01-01

    This study describes the posterior pole contour and visual field (VF) findings in an unselected series of adults (aged approximately 54 years) with high myopia.......This study describes the posterior pole contour and visual field (VF) findings in an unselected series of adults (aged approximately 54 years) with high myopia....

  13. The Dynamics of Shape

    CERN Document Server

    Gomes, Henrique

    2011-01-01

    This thesis consists of two parts, connected by one central theme: the dynamics of the "shape of space". The first part of the thesis concerns the construction of a theory of gravity dynamically equivalent to general relativity (GR) in 3+1 form (ADM). What is special about this theory is that it does not possess foliation invariance, as does ADM. It replaces that "symmetry" by another: local conformal invariance. In so doing it more accurately reflects a theory of the "shape of space", giving us reason to call it \\emph{shape dynamics} (SD). In the first part we will try to present some of the highlights of results so far, and indicate what we can and cannot do with shape dynamics. Because this is a young, rapidly moving field, we have necessarily left out some interesting new results which are not yet in print and were developed alongside the writing of the thesis. The second part of the thesis will develop a gauge theory for "shape of space"--theories. To be more precise, if one admits that the physically re...

  14. Tunable polymer multi-shape memory effect.

    Science.gov (United States)

    Xie, Tao

    2010-03-11

    Shape memory polymers are materials that can memorize temporary shapes and revert to their permanent shape upon exposure to an external stimulus such as heat, light, moisture or magnetic field. Such properties have enabled a variety of applications including deployable space structures, biomedical devices, adaptive optical devices, smart dry adhesives and fasteners. The ultimate potential for a shape memory polymer, however, is limited by the number of temporary shapes it can memorize in each shape memory cycle and the ability to tune the shape memory transition temperature(s) for the targeted applications. Currently known shape memory polymers are capable of memorizing one or two temporary shapes, corresponding to dual- and triple-shape memory effects (also counting the permanent shape), respectively. At the molecular level, the maximum number of temporary shapes a shape memory polymer can memorize correlates directly to the number of discrete reversible phase transitions (shape memory transitions) in the polymer. Intuitively, one might deduce that multi-shape memory effects are achievable simply by introducing additional reversible phase transitions. The task of synthesizing a polymer with more than two distinctive and strongly bonded reversible phases, however, is extremely challenging. Tuning shape memory effects, on the other hand, is often achieved through tailoring the shape memory transition temperatures, which requires alteration in the material composition. Here I show that the perfluorosulphonic acid ionomer (PFSA), which has only one broad reversible phase transition, exhibits dual-, triple-, and at least quadruple-shape memory effects, all highly tunable without any change to the material composition.

  15. Geologic shapes inversion in field engineering using production data; Inversion de formes geologiques en ingenierie de gisements en utilisant les donnees de production

    Energy Technology Data Exchange (ETDEWEB)

    Edoa, P.F.

    1999-03-09

    The work of this thesis is to study and to solve a shape inversion problem in petroleum reservoir engineering. We developed history matching methods of production data such as well measurements in order to better identify the geometry of geological bodies in a reservoir. Fluid flows are single phase or multiphase. The numerical simulation of these flows is based on a finite volume method on structured meshes. In this context, classical shape optimisation techniques based on mesh perturbations can not be applicable. In fact, each time the surface describing the region to optimize crosses a new grid mesh, the discrete problem gets non differentiable. In order to overcome the difficulty, some authors propose very expensive optimisation methods that only need evaluations of the criterion to be minimized. In this thesis, we propose an approach that consists in working on the continuous problem that is differentiable. In our problem, we generally work a great number of parameters. For this reason, the adjoint state method has been used to calculate the derivative of the cost function with respect to the geometry. Then, it allowed us to calculate rapidly the gradients by discretization of the derivative obtained and to elaborate inversion. processes based on classical algorithms of optimisation. During this thesis, we also pointed out the possibility to modify the topology of the domain using the idea of topological gradient. The development of this topological optimisation method was made possible thanks to the efficiency of the adjoint state method. The adaptation cost of the results was small, especially for the calculation of the sensitivities with respect to the position of small size obstacles. The proposed applications concern the identification of the thickness and the width of channels of the position and the size of faults, of top surface and reservoir limits. An example of application of topological optimisation was performed with geostatistical models

  16. Women in Shape Modeling Workshop

    CERN Document Server

    Tari, Sibel

    2015-01-01

    Presenting the latest research from the growing field of mathematical shape analysis, this volume is comprised of the collaborations of participants of the Women in Shape Modeling (WiSh) workshop, held at UCLA's Institute for Pure and Applied Mathematics in July 2013. Topics include: Simultaneous spectral and spatial analysis of shape Dimensionality reduction and visualization of data in tree-spaces, such as classes of anatomical trees like airways and blood vessels Geometric shape segmentation, exploring shape segmentation from a Gestalt perspective, using information from the Blum medial axis of edge fragments in an image Representing and editing self-similar details on 3D shapes, studying shape deformation and editing techniques Several chapters in the book directly address the problem of continuous measures of context-dependent nearness and right shape models. Medical and biological applications have been a major source of motivation in shape research, and key topics are examined here in detail. All...

  17. Penning-trap mass spectrometry and mean-field study of nuclear shape coexistence in the neutron-deficient lead region

    Science.gov (United States)

    Manea, V.; Ascher, P.; Atanasov, D.; Barzakh, A. E.; Beck, D.; Blaum, K.; Borgmann, Ch.; Breitenfeldt, M.; Cakirli, R. B.; Cocolios, T. E.; Day Goodacre, T.; Fedorov, D. V.; Fedosseev, V. N.; George, S.; Herfurth, F.; Kowalska, M.; Kreim, S.; Litvinov, Yu. A.; Lunney, D.; Marsh, B.; Neidherr, D.; Rosenbusch, M.; Rossel, R. E.; Rothe, S.; Schweikhard, L.; Wienholtz, F.; Wolf, R. N.; Zuber, K.

    2017-05-01

    We present a study of nuclear shape coexistence in the region of neutron-deficient lead isotopes. The midshell gold isotopes 180,185,188,190Au (Z =79 ), the two long-lived nuclear states in 197At (Z =85 ), and the neutron-rich nuclide 219At were produced by the ISOLDE facility at CERN and their masses were determined with the high-precision Penning-trap mass spectrometer ISOLTRAP. The studied gold isotopes address the trend of binding energies in a region of the nuclear chart where the nuclear charge radii show pronounced discontinuities. Significant deviations from the atomic-mass evaluation were found for Au,190188. The new trend of two-neutron separation energies is smoother, although it does reveal the onset of deformation. The origin of this effect is interpreted in connection to the odd-even staggering of binding energies, as well as theoretically by Hartree-Fock-Bogoliubov calculations including quasiparticle blocking. The role of blocking for reproducing the large odd-even staggering of charge radii in the mercury isotopic chain is illustrated.

  18. Co-rotational thermo-mechanically coupled multi-field framework and finite element for the large displacement analysis of multi-layered shape memory alloy beam-like structures

    Science.gov (United States)

    Solomou, Alexandros G.; Machairas, Theodoros T.; Karakalas, Anargyros A.; Saravanos, Dimitris A.

    2017-06-01

    A thermo-mechanically coupled finite element (FE) for the simulation of multi-layered shape memory alloy (SMA) beams admitting large displacements and rotations (LDRs) is developed to capture the geometrically nonlinear effects which are present in many SMA applications. A generalized multi-field beam theory implementing a SMA constitutive model based on small strain theory, thermo-mechanically coupled governing equations and multi-field kinematic hypotheses combining first order shear deformation assumptions with a sixth order polynomial temperature field through the thickness of the beam section are extended to admit LDRs. The co-rotational formulation is adopted, where the motion of the beam is decomposed to rigid body motion and relative small deformation in the local frame. A new generalized multi-layered SMA FE is formulated. The nonlinear transient spatial discretized equations of motion of the SMA structure are synthesized and solved using the Newton-Raphson method combined with an implicit time integration scheme. Correlations of models incorporating the present beam FE with respective results of models incorporating plane stress SMA FEs, demonstrate excellent agreement of the predicted LDRs response, temperature and phase transformation fields, as well as, significant gains in computational time.

  19. A Case-Based Study of Students' Visuohaptic Experiences of Electric Fields around Molecules: Shaping the Development of Virtual Nanoscience Learning Environments

    Directory of Open Access Journals (Sweden)

    Gunnar E. Höst

    2013-01-01

    Full Text Available Recent educational research has suggested that immersive multisensory virtual environments offer learners unique and exciting knowledge-building opportunities for the construction of scientific knowledge. This paper delivers a case-based study of students’ immersive interaction with electric fields around molecules in a multisensory visuohaptic virtual environment. The virtual architecture presented here also has conceptual connections to the flourishing quest in contemporary literature for the pressing need to communicate nanoscientific ideas to learners. Five upper secondary school students’ prior conceptual understanding of electric fields and their application of this knowledge to molecular contexts, were probed prior to exposure to the virtual model. Subsequently, four students interacted with the visuohaptic model while performing think-aloud tasks. An inductive and heuristic treatment of videotaped verbal and behavioural data revealed distinct interrelationships between students’ interactive strategies implemented when executing tasks in the virtual system and the nature of their conceptual knowledge deployed. The obtained qualitative case study evidence could serve as an empirical basis for informing the rendering and communication of overarching nanoscale ideas. At the time of composing this paper for publication in the current journal, the research findings of this study have been put into motion in informing a broader project goal of developing educational virtual environments for depicting nanophenomena.

  20. Fusing Markov random fields with anatomical knowledge and shape-based analysis to segment multiple sclerosis white matter lesions in magnetic resonance images of the brain

    Science.gov (United States)

    AlZubi, Stephan; Toennies, Klaus D.; Bodammer, N.; Hinrichs, Herman

    2002-05-01

    This paper proposes an image analysis system to segment multiple sclerosis lesions of magnetic resonance (MR) brain volumes consisting of 3 mm thick slices using three channels (images showing T1-, T2- and PD -weighted contrast). The method uses the statistical model of Markov Random Fields (MRF) both at low and high levels. The neighborhood system used in this MRF is defined in three types: (1) Voxel to voxel: a low-level heterogeneous neighborhood system is used to restore noisy images. (2) Voxel to segment: a fuzzy atlas, which indicates the probability distribution of each tissue type in the brain, is registered elastically with the MRF. It is used by the MRF as a-priori knowledge to correct miss-classified voxels. (3) Segment to segment: Remaining lesion candidates are processed by a feature based classifier that looks at unary and neighborhood information to eliminate more false positives. An expert's manual segmentation was compared with the algorithm.

  1. Observing quantum control of up-conversion luminescence in Dy3+ ion doped glass from weak to intermediate shaped femtosecond laser fields

    Science.gov (United States)

    Liu, Pei; Cheng, Wenjing; Yao, Yunhua; Xu, Cheng; Zheng, Ye; Deng, Lianzhong; Jia, Tianqing; Qiu, Jianrong; Sun, Zhenrong; Zhang, Shian

    2017-11-01

    Controlling the up-conversion luminescence of rare-earth ions in real-time, in a dynamical and reversible manner, is very important for their application in laser sources, fiber-optic communications, light-emitting diodes, color displays and biological systems. In previous studies, the up-conversion luminescence control mainly focused on the weak femtosecond laser field. Here, we further extend this control behavior from weak to intermediate femtosecond laser fields. In this work, we experimentally and theoretically demonstrate that the up-conversion luminescence in Dy3+ ion doped glass can be artificially controlled by a π phase step modulation, but the up-conversion luminescence control behavior will be affected by the femtosecond laser intensity, and the up-conversion luminescence is suppressed by lower laser intensity while enhanced by higher laser intensity. We establish a new theoretical model (i.e. the fourth-order perturbation theory) to explain the physical control mechanism by considering the two- and four-photon absorption processes, and the theoretical results show that the relative weight of four-photon absorption in the whole excitation process will increase with the increase in laser intensity, and the interference between two- and four-photon absorptions results in up-conversion luminescence control modulation under different laser intensities. These theoretical and experimental works can provide a new method to control and understand up-conversion luminescence in rare-earth ions, and also may open a new opportunity to the related application areas of rare-earth ions.

  2. Porous Shape Memory Polymers

    Science.gov (United States)

    Hearon, Keith; Singhal, Pooja; Horn, John; Small, Ward; Olsovsky, Cory; Maitland, Kristen C.; Wilson, Thomas S.; Maitland, Duncan J.

    2013-01-01

    Porous shape memory polymers (SMPs) include foams, scaffolds, meshes, and other polymeric substrates that possess porous three-dimensional macrostructures. Porous SMPs exhibit active structural and volumetric transformations and have driven investigations in fields ranging from biomedical engineering to aerospace engineering to the clothing industry. The present review article examines recent developments in porous SMPs, with focus given to structural and chemical classification, methods of characterization, and applications. We conclude that the current body of literature presents porous SMPs as highly interesting smart materials with potential for industrial use. PMID:23646038

  3. Radiotherapy for stage I seminoma of the testis: Organ equivalent dose to partially in-field structures and second cancer risk estimates on the basis of a mechanistic, bell-shaped, and plateau model

    Energy Technology Data Exchange (ETDEWEB)

    Mazonakis, Michalis, E-mail: mazonak@med.uoc.gr; Damilakis, John [Department of Medical Physics, Faculty of Medicine, University of Crete, P.O. Box 2208, Iraklion, Crete 71003 (Greece); Varveris, Charalambos; Lyraraki, Efrossyni [Department of Radiotherapy and Oncology, University Hospital of Iraklion, Iraklion, Crete 71110 (Greece)

    2015-11-15

    Purpose: The aim of the current study was to (a) calculate the organ equivalent dose (OED) and (b) estimate the associated second cancer risk to partially in-field critical structures from adjuvant radiotherapy for stage I seminoma of the testis on the basis of three different nonlinear risk models. Methods: Three-dimensional plans were created for twelve patients who underwent a treatment planning computed tomography of the abdomen. The plans for irradiation of seminoma consisted of para-aortic anteroposterior and posteroanterior fields giving 20 Gy to the target site with 6 MV photons. The OED of stomach, colon, liver, pancreas, and kidneys, that were partially included in the treatment volume, was calculated using differential dose–volume histograms. The mechanistic, bell-shaped, and plateau models were employed for these calculations provided that organ-specific parameters were available for the subsequent assessment of the excess absolute risk (EAR) for second cancer development. The estimated organ-specific lifetime risks were compared with the respective nominal intrinsic probabilities for cancer induction. Results: The mean OED, which was calculated from the patients’ treatment plans, varied from 0.54 to 6.61 Gy by the partially in-field organ of interest and the model used for dosimetric calculations. The difference between the OED of liver derived from the mechanistic model with those from the bell-shaped and plateau models was less than 1.8%. An even smaller deviation of 1.0% was observed for colon. For the rest organs of interest, the differences between the OED values obtained by the examined models varied from 8.6% to 50.0%. The EAR for stomach, colon, liver, pancreas, and kidney cancer induction at an age of 70 yr because of treatment of a typical 39-yr-old individual was up to 4.24, 11.39, 0.91, 3.04, and 0.14 per 10 000 persons-yr, respectively. Patient’s irradiation was found to elevate the lifetime intrinsic risks by 8.3%–63.0% depending

  4. Bayesian Vision for Shape Recovery

    Science.gov (United States)

    Jalobeanu, Andre

    2004-01-01

    We present a new Bayesian vision technique that aims at recovering a shape from two or more noisy observations taken under similar lighting conditions. The shape is parametrized by a piecewise linear height field, textured by a piecewise linear irradiance field, and we assume Gaussian Markovian priors for both shape vertices and irradiance variables. The observation process. also known as rendering, is modeled by a non-affine projection (e.g. perspective projection) followed by a convolution with a piecewise linear point spread function. and contamination by additive Gaussian noise. We assume that the observation parameters are calibrated beforehand. The major novelty of the proposed method consists of marginalizing out the irradiances considered as nuisance parameters, which is achieved by Laplace approximations. This reduces the inference to minimizing an energy that only depends on the shape vertices, and therefore allows an efficient Iterated Conditional Mode (ICM) optimization scheme to be implemented. A Gaussian approximation of the posterior shape density is computed, thus providing estimates both the geometry and its uncertainty. We illustrate the effectiveness of the new method by shape reconstruction results in a 2D case. A 3D version is currently under development and aims at recovering a surface from multiple images, reconstructing the topography by marginalizing out both albedo and shading.

  5. Corrosion behavior of Cu Al Ni shape memory alloy in an oil land field produced fluid; Corrosao da liga com memoria de forma CuAlNi em fluido produzido de campo terrestre de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Ricardo Estefany Aquino [PETROBRAS S.A., Aracaju/Maceio, SE/AL (Brazil). Unidade de Negocios SE-AL; Cruz, Maria Clara Pinto; Figueiredo, Renan T.; Souza, Luciete da Paixao; Araujo, Paulo M.M. [Universidade Tiradentes (UNIT), Aracaju, SE (Brazil)

    2008-07-01

    The corrosion behavior of the CuAlNi shape memory alloy in oil landfield produced groundwater was investigated with polarization curve and mass loss measurements, the latter carried out by immersion in laboratory and field tests. The physico-chemical analysis of five types of oil landfield produced groundwater showed the presence of H{sub 2}S and CO{sub 2}, high salinity, chloride, sulfide and iron ions and relatively neutral pH. The results from electrochemical tests in aerated produced groundwater, in the range of salinity encountered, suggested that the corrosion rate increases at higher saline concentrations. The results from field tests with corrosion test specimens showed a moderate to severe corrosion rate and suggested, in the other hand, that corrosion rates were influenced not only by salinity and oxidizing ions present in the flowing fluid, but also by solid materials in suspension, the fluid's temperature, and the flow velocity. This research is part of a major project which aims to develop couplings for landfield produced fluid transportation pipe connections without welded nor threaded joints. (author)

  6. A New Electrochemical System Based on a Flow-Field Shaped Solid Electrode and 3D-Printed Thin-Layer Flow Cell: Detection of Pb(2+) Ions by Continuous Flow Accumulation Square-Wave Anodic Stripping Voltammetry.

    Science.gov (United States)

    Sun, Qianwen; Wang, Jikui; Tang, Meihua; Huang, Liming; Zhang, Zhiyi; Liu, Chang; Lu, Xiaohua; Hunter, Kenneth W; Chen, Guosong

    2017-05-02

    Here we describe a new and sensitive flow electrochemical detection system that employs a novel flow-field shaped solid electrode (FFSSE). The system was constructed with a 3D-printed thin-layer flow cell (TLFC) and a flat screen-printed FFSSE with USB connection. This interface facilitates continuous flow accumulation square-wave anodic stripping voltammetry (ASV). The flow distribution in the working space of TLFC was simulated using the finite element method (FEM) and the shape and configuration of electrodes were optimized accordingly. We demonstrated the electrochemical determination of Pb(2+) using this newly designed TLFC-FFSSE detection system without removal of oxygen from samples. This TLFC-FFSSE based system showed an attractive stripping voltammetric performance compared to a traditional ASV based method. A linear range for detection of Pb(2+) was found to be 0.5-100 μg/L (0.5 to 100 ppb) and a detection limit of 0.2 μg/L (0.2 ppb) was achieved in the presence of bismuth as codeposition metal. The system was further applied to detect Pb(2+) in biological broths of methane fermentation. The electrochemical detection results were consistent with that obtained from atomic fluorescence spectroscopy (AFS) analysis and the average recovery was found to be 95.5-106.5% using a standard addition method. This new flow electrochemical detection system showed better sensitivity and reproducibility compared to a traditional ASV based method. Such a system offers great potential for on-site and real-time detection of heavy metals where compact, inexpensive, robust, and low-volume analysis is required.

  7. Influence of Microfield Directionality on Line Shapes

    Directory of Open Access Journals (Sweden)

    Annette Calisti

    2014-06-01

    Full Text Available In the framework of the Spectral Line Shapes in Plasmas Code Comparison Workshop (SLSP, large discrepancies appeared between the different approaches to account for ion motion effects in spectral line shape calculations. For a better understanding of these effects, in the second edition of the SLSP in August, 2013, two cases were dedicated to the study of the ionic field directionality on line shapes. In this paper, the effects of the direction and magnitude fluctuations are separately analyzed. The effects of two variants of electric field models, (i a pure rotating field with constant magnitude and (ii a time-dependent magnitude field in a given direction, together with the effects of the time-dependent ionic field on shapes of the He II Lyman-α and -β lines for different densities and temperatures, are discussed.

  8. Zeptosecond precision pulse shaping.

    Science.gov (United States)

    Köhler, Jens; Wollenhaupt, Matthias; Bayer, Tim; Sarpe, Cristian; Baumert, Thomas

    2011-06-06

    We investigate the temporal precision in the generation of ultrashort laser pulse pairs by pulse shaping techniques. To this end, we combine a femtosecond polarization pulse shaper with a polarizer and employ two linear spectral phase masks to mimic an ultrastable common-path interferometer. In an all-optical experiment we study the interference signal resulting from two temporally delayed pulses. Our results show a 2σ-precision of 300 zs = 300 × 10(-21) s in pulse-to-pulse delay. The standard deviation of the mean is 11 zs. The obtained precision corresponds to a variation of the arm's length in conventional delay stage based interferometers of 0.45 Å. We apply these precisely generated pulse pairs to a strong-field quantum control experiment. Coherent control of ultrafast electron dynamics via photon locking by temporal phase discontinuities on a few attosecond timescale is demonstrated.

  9. Shape memory polymers

    Science.gov (United States)

    Wilson, Thomas S.; Bearinger, Jane P.

    2015-06-09

    New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxyl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

  10. Shape memory polymers

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Thomas S.; Bearinger, Jane P.

    2017-08-29

    New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

  11. Shape Analysis and the Classification of Objects

    Science.gov (United States)

    Neal, F. Brent; Russ, John C.

    Quantification of shape remains an area of active study in the field of image analysis and machine vision. We present a comparative survey of three approaches to shape measurement: classical dimensionless ratios, harmonic analysis, and invariant moments, showing their suitability for classification of objects and other statistical analyses, including quantitative structure-property relationships. We show that for topologically simple shapes and well controlled imaging conditions, all three methods can provide robust classification of objects.

  12. Minimization of Gate-Induced Drain Leakage by Controlling Gate Underlap Length for Low-Standby-Power Operation of 20-nm-Level Four-Terminal Silicon-on-Insulator Fin-Shaped Field Effect Transistor

    Science.gov (United States)

    Seongjae Cho,; Shinichi O'uchi,; Kazuhiko Endo,; Takashi Matsukawa,; Kunihiro Sakamoto,; Yongxun Liu,; Byung-Gook Park,; Meishoku Masahara,

    2010-02-01

    Recently, gate-induced drain leakage (GIDL) has become a crucial factor of current characteristics as junction doping concentration becomes more abruptly graded owing to device scaling. It should be effectively suppressed for the low-standby-power operation of ultra small metal-oxide-semiconductor field effect transistor (MOSFET) devices. In this work, the appropriate underlap length range for the effective minimization of GIDL in 20-nm-level four-terminal (4-T) fin-shaped FET (FinFET) on silicon-on-insulator (SOI) is established. In order to identify the effect of underlap length on GIDL more precisely, the source and drain (S/D) junction doping profile and the majority/minority carrier lifetimes have been extracted by the measurement of a p-n junction test element group (TEG). The TEG was fabricated under the same process conditions that were used in forming the S/D junctions of 100-nm-level 4-T SOI FinFET in our previous research. The GIDL component in the off-state current is investigated with underlap length variation along with the inspection of basic current characteristics. For low-standby-power operation, an underlap junction is more desirable than an overlap junction, and the underlap length should be at least 10 nm to suppress GIDL effectively.

  13. Discriminative Shape Alignment

    DEFF Research Database (Denmark)

    Loog, M.; de Bruijne, M.

    2009-01-01

    The alignment of shape data to a common mean before its subsequent processing is an ubiquitous step within the area shape analysis. Current approaches to shape analysis or, as more specifically considered in this work, shape classification perform the alignment in a fully unsupervised way......, not taking into account that eventually the shapes are to be assigned to two or more different classes. This work introduces a discriminative variation to well-known Procrustes alignment and demonstrates its benefit over this classical method in shape classification tasks. The focus is on two...

  14. Modeling and Correspondence of Topologically Complex 3D Shapes

    OpenAIRE

    Alhashim, Ibraheem

    2015-01-01

    3D shape creation and modeling remains a challenging task especially for novice users. Many methods in the field of computer graphics have been proposed to automate the often repetitive and precise operations needed during the modeling of detailed shapes. This report surveys different approaches of shape modeling and correspondence especially for shapes exhibiting topological complexity. We focus on methods designed to help generate or process shapes with large number of interconnected compon...

  15. Self-erecting shapes

    Energy Technology Data Exchange (ETDEWEB)

    Reading, Matthew W.

    2017-07-04

    Technologies for making self-erecting structures are described herein. An exemplary self-erecting structure comprises a plurality of shape-memory members that connect two or more hub components. When forces are applied to the self-erecting structure, the shape-memory members can deform, and when the forces are removed the shape-memory members can return to their original pre-deformation shape, allowing the self-erecting structure to return to its own original shape under its own power. A shape of the self-erecting structure depends on a spatial orientation of the hub components, and a relative orientation of the shape-memory members, which in turn depends on an orientation of joining of the shape-memory members with the hub components.

  16. Shaped Recess Flow Control

    Science.gov (United States)

    Shyam, Vikram (Inventor); Poinsatte, Philip (Inventor); Thurman, Douglas (Inventor)

    2017-01-01

    One or more embodiments of techniques or systems for shaped recess flow control are provided herein. A shaped recess or cavity can be formed on a surface associated with fluid flow. The shaped recess can be configured to create or induce fluid effects, temperature effects, or shedding effects that interact with a free stream or other structures. The shaped recess can be formed at an angle to a free stream flow and may be substantially "V" shaped. The shaped recess can be coupled with a cooling channel, for example. The shaped recess can be upstream or downstream from a cooling channel and aligned in a variety of manners. Due to the fluid effects, shedding effects, and temperature effects created by a shaped recess, lift-off or separation of cooling jets of cooling channels can be mitigated, thereby enhancing film cooling effectiveness.

  17. New trends in shape optimization

    CERN Document Server

    Leugering, Günter

    2015-01-01

    This volume reflects “New Trends in Shape Optimization” and is based on a workshop of the same name organized at the Friedrich-Alexander University Erlangen-Nürnberg in September 2013. During the workshop senior mathematicians and young scientists alike presented their latest findings. The format of the meeting allowed fruitful discussions on challenging open problems, and triggered a number of new and spontaneous collaborations. As such, the idea was born to produce this book, each chapter of which was written by a workshop participant, often with a collaborator. The content of the individual chapters ranges from survey papers to original articles; some focus on the topics discussed at the Workshop, while others involve arguments outside its scope but which are no less relevant for the field today. As such, the book offers readers a balanced introduction to the emerging field of shape optimization.

  18. Shape design sensitivity analysis using domain information

    Science.gov (United States)

    Seong, Hwal-Gyeong; Choi, Kyung K.

    1985-01-01

    A numerical method for obtaining accurate shape design sensitivity information for built-up structures is developed and demonstrated through analysis of examples. The basic character of the finite element method, which gives more accurate domain information than boundary information, is utilized for shape design sensitivity improvement. A domain approach for shape design sensitivity analysis of built-up structures is derived using the material derivative idea of structural mechanics and the adjoint variable method of design sensitivity analysis. Velocity elements and B-spline curves are introduced to alleviate difficulties in generating domain velocity fields. The regularity requirements of the design velocity field are studied.

  19. The Hue of Shapes

    Science.gov (United States)

    Albertazzi, Liliana; Da Pos, Osvaldo; Canal, Luisa; Micciolo, Rocco; Malfatti, Michela; Vescovi, Massimo

    2013-01-01

    This article presents an experimental study on the naturally biased association between shape and color. For each basic geometric shape studied, participants were asked to indicate the color perceived as most closely related to it, choosing from the Natural Color System Hue Circle. Results show that the choices of color for each shape were not…

  20. Building with shapes

    CERN Document Server

    Mooney, Carla

    2014-01-01

    There are shapes everywhere you look. You can put shapes together or build with them. What can you build with three circles? In this title, students will explore and understand that certain attributes define what a shape is called. This title will allow students to identify the main purpose of a text, including what the author wants to answer, explain, or describe.

  1. Strategic Planning: Shaping Future Success

    Science.gov (United States)

    2016-09-01

    Defense AT&L: September-October 2016 46 Strategic Planning Shaping Future Success Brian Schultz “What’s the use of running if you are not on the...fielding, the PM may also be planning for future increments, sustainment and other long-term ef- forts. Strategic planning can help the PM position these...future programs and actions for good outcomes. So what is this strategic planning all about? Let’s start with some background, including a strategic

  2. Alpha Shapes and Proteins

    DEFF Research Database (Denmark)

    Winter, Pawel; Sterner, Henrik; Sterner, Peter

    2009-01-01

    We provide a unified description of (weighted) alpha shapes, beta shapes and the corresponding simplicialcomplexes. We discuss their applicability to various protein-related problems. We also discuss filtrations of alpha shapes and touch upon related persistence issues.We claim that the full...... potential of alpha-shapes and related geometrical constructs in protein-related problems yet remains to be realized and verified. We suggest parallel algorithms for (weighted) alpha shapes, and we argue that future use of filtrations and kinetic variants for larger proteins will need such implementation....

  3. Transforming shape in design

    DEFF Research Database (Denmark)

    Prats, Miquel; Lim, Sungwoo; Jowers, Iestyn

    2009-01-01

    This paper is concerned with how design shapes are generated and explored by means of sketching. It presents research into the way designers transform shapes from one state to another using sketch representations. An experimental investigation of the sketching processes of designers is presented....... Connections between sketches are defined in terms of shape transformations and described according to shape rules. These rules provide a formal description of the shape exploration process and develop understanding of the mechanics of sketching in design. The paper concludes by discussing the important...

  4. Nuclear shapes: from earliest ideas to multiple shape coexisting structures

    Science.gov (United States)

    Heyde, K.; Wood, J. L.

    2016-08-01

    The concept of the atomic nucleus being characterized by an intrinsic property such as shape came as a result of high precision hyperfine studies in the field of atomic physics, which indicated a non-spherical nuclear charge distribution. Herein, we describe the various steps taken through ingenious experimentation and bold theoretical suggestions that mapped the way for later work in the early 50s by Aage Bohr, Ben Mottelson and James Rainwater. We lay out a long and winding road that marked, in the period of 50s to 70s, the way shell-model and collective-model concepts were reconciled. A rapid increase in both accelerator and detection methods (70s towards the early 2000s) opened new vistas into nuclear shapes, and their coexistence, in various regions of the nuclear mass table. Next, we outline a possible unified view of nuclear shapes: emphasizing decisive steps taken as well as questions remaining, next to the theoretical efforts that could result in an emerging understanding of nuclear shapes, building on the nucleus considered as a strongly interacting system of nucleons as the microscopic starting point.

  5. Manifolds with integrable affine shape operator

    Directory of Open Access Journals (Sweden)

    Daniel A. Joaquín

    2005-05-01

    Full Text Available This work establishes the conditions for the existence of vector fields with the property that theirs covariant derivative, with respect to the affine normal connection, be the affine shape operatorS in hypersurfaces. Some results are obtained from this property and, in particular, for some kind of affine decomposable hypersurfaces we explicitely get the actual vector fields.

  6. Tonality: The Shape of Affect

    Directory of Open Access Journals (Sweden)

    Mine Doğantan-Dack

    2013-12-01

    Full Text Available The last decade has witnessed an increasing interest in studying music as it relates to human evolution, leading to the establishment of so-called evolutionary musicology as a new field of enquiry. Researchers in this field maintain that music indeed played as crucial a role as the development of language in the evolution of humankind. The most frequently cited musical phenomena in relation to various adaptive functions include rhythm, meter, and melodic contour. In this connection, the universal phenomenon of tonal organisation of pitch in musical systems received no attention. This article provides a hypothesis regarding the evolutionary origins of tonality as a system for the dynamic shaping of affect, and establishes further connections between music and affective states by proposing a link between the emergence of tonality and of the human capacity to regulate inter-subjective dynamics by shaping the course of affect towards stable states. The article also proposes that tonality provides an archetypal psychological space within which the human ability to shape different paths towards stable affective states could evolve.

  7. Method and apparatus for shaping and enhancing acoustical levitation forces

    Science.gov (United States)

    Oran, W. A.; Berge, L. H.; Reiss, D. A.; Johnson, J. L. (Inventor)

    1980-01-01

    A method and apparatus for enhancing and shaping acoustical levitation forces in a single-axis acoustic resonance system wherein specially shaped drivers and reflectors are utilized to enhance to levitation force and better contain fluid substance by means of field shaping is described.

  8. Shape from touch

    NARCIS (Netherlands)

    Kappers, A.M.L.; Bergmann Tiest, W.M.

    2014-01-01

    The shape of objects cannot only be recognized by vision, but also by touch. Vision has the advantage that shapes can be seen at a distance, but touch has the advantage that during exploration many additional object properties become available, such as temperature (Jones, 2009), texture (Bensmaia,

  9. The exchangeability of shape

    Directory of Open Access Journals (Sweden)

    Kaba Dramane

    2010-10-01

    Full Text Available Abstract Background Landmark based geometric morphometrics (GM allows the quantitative comparison of organismal shapes. When applied to systematics, it is able to score shape changes which often are undetectable by traditional morphological studies and even by classical morphometric approaches. It has thus become a fast and low cost candidate to identify cryptic species. Due to inherent mathematical properties, shape variables derived from one set of coordinates cannot be compared with shape variables derived from another set. Raw coordinates which produce these shape variables could be used for data exchange, however they contain measurement error. The latter may represent a significant obstacle when the objective is to distinguish very similar species. Results We show here that a single user derived dataset produces much less classification error than a multiple one. The question then becomes how to circumvent the lack of exchangeability of shape variables while preserving a single user dataset. A solution to this question could lead to the creation of a relatively fast and inexpensive systematic tool adapted for the recognition of cryptic species. Conclusions To preserve both exchangeability of shape and a single user derived dataset, our suggestion is to create a free access bank of reference images from which one can produce raw coordinates and use them for comparison with external specimens. Thus, we propose an alternative geometric descriptive system that separates 2-D data gathering and analyzes.

  10. Shape memory polymer foams

    Science.gov (United States)

    Santo, Loredana

    2016-02-01

    Recent advances in shape memory polymer (SMP) foam research are reviewed. The SMPs belong to a new class of smart polymers which can have interesting applications in microelectromechanical systems, actuators and biomedical devices. They can respond to specific external stimulus changing their configuration and then remember the original shape. In the form of foams, the shape memory behaviour can be enhanced because they generally have higher compressibility. Considering also the low weight, and recovery force, the SMP foams are expected to have great potential applications primarily in aerospace. This review highlights the recent progress in characterization, evaluation, and proposed applications of SMP foams mainly for aerospace applications.

  11. Shape instability of a magnetic elastomer membrane

    Energy Technology Data Exchange (ETDEWEB)

    Raikher, Yu L; Stolbov, O V [Institute of Continuous Media Mechanics, Ural Branch of RAS, 614013 Perm (Russian Federation); Stepanov, G V [State Scientific Center ' Institute of Chemistry and Technology of Organoelement Compounds' , 11123 Moscow (Russian Federation)], E-mail: raikher@icmm.ru

    2008-08-07

    Shape instability occurring in a thin plate (membrane) made of a soft magnetoelastic material under a uniform magnetic field is predicted and analysed. The instability onset is shown to be similar to the second-order transition; the dependence of the threshold field on the magnetic and geometric parameters of the membrane is derived analytically; the membrane shapes (domes) are evaluated with the aid of numerical simulation. The theory proposed is in general agreement with experiments performed on a siloxane rubber/iron carbonyl composite. (fast track communication)

  12. Shape memory polyurethane foams

    Directory of Open Access Journals (Sweden)

    B. K. Kim

    2012-01-01

    Full Text Available Molded flexible polyurethane (PU foams have been synthesized from polypropylene glycol (PPG with different molecular weights (Mw and functionalities (f, and 2,4/2,6-toluene diisocyanate (TDI-80 with water as blowing agent. It was found that the glassy state properties of the foam mainly depended on the urethane group content while the rubbery state properties on the crosslink density. That is, PPG of low MW and low f (more urethane groups provided superior glass state modulus, strength, density, shape fixity and glass transition temperature (Tg, while that of high Mw and high f (higher crosslink density showed high rubbery modulus and shape recovery. Consequently shape fixity of low Mw PPG decreased from 85 to 72% while shape recovery increased from 52 to 63% as the content of high Mw PPG increased from 0 to 40%.

  13. Reinforced Airfoil Shaped Body

    DEFF Research Database (Denmark)

    2011-01-01

    The present invention relates to an airfoil shaped body with a leading edge and a trailing edge extending along the longitudinal extension of the body and defining a profile chord, the airfoil shaped body comprising an airfoil shaped facing that forms the outer surface of the airfoil shaped body...... and surrounds an internal volume of the body, a distance member that is connected to the facing inside the body and extends from the facing and into the internal volume of the body, and at least one reinforcing member that operates in tension for reinforcing the facing against inward deflections...... and that is connected to the facing inside the internal volume of the body at the same side of the profile chord as the connection of the distance member to the facing and to the distance member at a distance from the facing....

  14. Shaft mode shape demonstration

    Science.gov (United States)

    Grissom, R.

    1985-01-01

    The dynamic response of a rotating machine is directly influenced by its geometric configuration and all aspects of the rotor construction. These determine two significant parameters, mass distribution and stiffness, which yield a spectrum of natural frequencies and mode shapes. The mode shapes can be presented as snapshots of the characteristic amplitude/phase reponse patterns of the shaft, due to the major forcing function of unbalance, at different rotative speeds. To demonstrate the three shaft mode shapes of the rotor rig using the Shaft Mode Demonstrator and oscilloscopes. The synchronous (1X) amplitude and phase of the rotor vibration in the vertical direction from several points along the shaft is displayed on corresponding points of the demonstrator. Unfiltered vibration from vertical and horizontal probe pairs is displayed on the oscilloscopes in orbit format for a dynamic presentation of the mode shape.

  15. Shape memory polyurethane nanocomposites

    Science.gov (United States)

    Cao, Feina

    Shape memory polymers are smart materials which can remember their original shapes. However, the low recovery stress and low mechanical strength limit the commercial applications of shape memory polymers. In this study, nanoclays were introduced to shape memory polyurethanes (SMPU) to augment these properties by enhance the network of SMPU. Several factors which influence the shape recovery stress were evaluated, including the nature of polymer chain by using different monomers, type of clay particles, extent of filler dispersion, clay content and deformation conditions. It was found that only reactive clay particles were well dispersed into polyurethane matrix by the tethering between --CH2CH 2OH functional groups in clay surfactants and polyurethane chains. Two different shape memory polyurethanes (Systems I & II) prepared by bulk polymerization were compared. The shape memory effect of System I was triggered by melting of the soft segment crystals, while that of System II was by glass transition of the soft segments. It was seen that the reactive clay particles dispersed well in both polyurethane matrices and augmented the recovery stress, e.g., 20% increase with 1 wt % nanoclay in System I and 40% increase with 5 wt % nanoclay in System II were observed. In System I, clay particles interfered with soft segment crystallization, and promoted phase mixing between the hard and soft segments, thus affecting the fixity and recovery ratio. Nevertheless, the soft segment crystallinity was still enough and in some cases increased due to stretching to exhibit excellent shape fixity and shape recovery ratio. The higher loading of clay particles accelerated the stress relaxation, resulting in reduction of recovery stress. In System II, no significant effect of clay particles in phase separation was observed, so there was no influence of clay on shape fixity and recovery ratio. The recovery stress increased with reactive nanoclay content. It was also found that the recovery

  16. Shaping the Global Environment

    Science.gov (United States)

    2002-04-09

    SHAPING THE GLOBAL ENVIRONMENT BY LIEUTENANT COLONEL MICHAEL D. ELLERBE United States Army DISTRIBUTION STATEMENT A: Approved for public release...THE GLOBAL ENVIRONMENT by Lieutenant Colonel Michael D. Ellerbe United States Army Colonel Jef Troxel Project Advisor The views expressed in this...Distribution is unlimited. ii ABSTRACT AUTHOR: Michael D. Ellerbe TITLE: SHAPING THE GLOBAL ENVIRONMENT FORMAT: Strategy Research Project DATE: 09 April

  17. Ultrathin Shape Change Smart Materials.

    Science.gov (United States)

    Xu, Weinan; Kwok, Kam Sang; Gracias, David H

    2018-01-23

    With the discovery of graphene, significant research has focused on the synthesis, characterization, and applications of ultrathin materials. Graphene has also brought into focus other ultrathin materials composed of organics, polymers, inorganics, and their hybrids. Together, these ultrathin materials have unique properties of broad significance. For example, ultrathin materials have a large surface area and high flexibility which can enhance conformal contact in wearables and sensors leading to improved sensitivity. When porous, the short transverse diffusion length in these materials allows rapid mass transport. Alternatively, when impermeable, these materials behave as an ultrathin barrier. Such controlled permeability is critical in the design of encapsulation and drug delivery systems. Finally, ultrathin materials often feature defect-free and single-crystal-like two-dimensional atomic structures resulting in superior mechanical, optical, and electrical properties. A unique property of ultrathin materials is their low bending rigidity, which suggests that they could easily be bent, curved, or folded into 3D shapes. In this Account, we review the emerging field of 2D to 3D shape transformations of ultrathin materials. We broadly define ultrathin to include materials with a thickness below 100 nm and composed of a range of organic, inorganic, and hybrid compositions. This topic is important for both fundamental and applied reasons. Fundamentally, bending and curving of ultrathin films can cause atomistic and molecular strain which can alter their physical and chemical properties and lead to new 3D forms of matter which behave very differently from their planar precursors. Shape change can also lead to new 3D architectures with significantly smaller form factors. For example, 3D ultrathin materials would occupy a smaller space in on-chip devices or could permeate through tortuous media which is important for miniaturized robots and smart dust applications. Our

  18. On Characterizing Particle Shape

    Science.gov (United States)

    Ennis, Bryan J.; Rickman, Douglas; Rollins, A. Brent; Ennis, Brandon

    2014-01-01

    It is well known that particle shape affects flow characteristics of granular materials, as well as a variety of other solids processing issues such as compaction, rheology, filtration and other two-phase flow problems. The impact of shape crosses many diverse and commercially important applications, including pharmaceuticals, civil engineering, metallurgy, health, and food processing. Two applications studied here include the dry solids flow of lunar simulants (e.g. JSC-1, NU-LHT-2M, OB-1), and the flow properties of wet concrete, including final compressive strength. A multi-dimensional generalized, engineering method to quantitatively characterize particle shapes has been developed, applicable to both single particle orientation and multi-particle assemblies. The two-dimension, three dimension inversion problem is also treated, and the application of these methods to DEM model particles will be discussed. In the case of lunar simulants, flow properties of six lunar simulants have been measured, and the impact of particle shape on flowability - as characterized by the shape method developed here -- is discussed, especially in the context of three simulants of similar size range. In the context of concrete processing, concrete construction is a major contributor to greenhouse gas production, of which the major contributor is cement binding loading. Any optimization in concrete rheology and packing that can reduce cement loading and improve strength loading can also reduce currently required construction safety factors. The characterization approach here is also demonstrated for the impact of rock aggregate shape on concrete slump rheology and dry compressive strength.

  19. Shapes of interacting RNA complexes

    DEFF Research Database (Denmark)

    Fu, Benjamin Mingming; Reidys, Christian

    2014-01-01

    Shapes of interacting RNA complexes are studied using a filtration via their topological genus. A shape of an RNA complex is obtained by (iteratively) collapsing stacks and eliminating hairpin loops.This shape-projection preserves the topological core of the RNA complex and for fixed topological...... genus there are only finitely many such shapes. Our main result is a new bijection that relates the shapes of RNA complexes with shapes of RNA structures. This allows to compute the shape polynomial of RNA complexes via the shape polynomial of RNA structures. We furthermore present a linear time uniform...... sampling algorithm for shapes of RNA complexes of fixed topological genus....

  20. The shape of eParticipation

    DEFF Research Database (Denmark)

    Sæbø, Øystein; Rose, Jeremy; Flak, Leif Skiftenes

    2008-01-01

    The phenomenon of eParticipation is receiving increasing attention, demonstrated by recent technology implementations, experiments, government reports and research programs. Understanding such an emerging field is a complex endeavour because there is no generally agreed upon definition of the field...... point for a grounded analysis leading to the development of an overview model: the field of eParticipation seen from a researcher's perspective. The model provides structure for understanding the emerging shape of the field as well as an initial indication of its content. It also provides the basis...

  1. SHAPE selection (SHAPES) enrich for RNA structure signal in SHAPE sequencing-based probing data

    DEFF Research Database (Denmark)

    Poulsen, Line Dahl; Kielpinski, Lukasz Jan; Salama, Sofie R

    2015-01-01

    transcriptase. Here, we introduce a SHAPE Selection (SHAPES) reagent, N-propanone isatoic anhydride (NPIA), which retains the ability of SHAPE reagents to accurately probe RNA structure, but also allows covalent coupling between the SHAPES reagent and a biotin molecule. We demonstrate that SHAPES...

  2. Flaw shape reconstruction – an experimental approach

    Directory of Open Access Journals (Sweden)

    Marilena STANCULESCU

    2009-05-01

    Full Text Available Flaws can be classified as acceptable and unacceptable flaws. As a result of nondestructive testing, one takes de decision Admit/Reject regarding the tested product related to some acceptability criteria. In order to take the right decision, one should know the shape and the dimension of the flaw. On the other hand, the flaws considered to be acceptable, develop in time, such that they can become unacceptable. In this case, the knowledge of the shape and dimension of the flaw allows determining the product time life. For interior flaw shape reconstruction the best procedure is the use of difference static magnetic field. We have a stationary magnetic field problem, but we face the problem given by the nonlinear media. This paper presents the results of the experimental work for control specimen with and without flaw.

  3. Shape memory polymer medical device

    Science.gov (United States)

    Maitland, Duncan [Pleasant Hill, CA; Benett, William J [Livermore, CA; Bearinger, Jane P [Livermore, CA; Wilson, Thomas S [San Leandro, CA; Small, IV, Ward; Schumann, Daniel L [Concord, CA; Jensen, Wayne A [Livermore, CA; Ortega, Jason M [Pacifica, CA; Marion, III, John E.; Loge, Jeffrey M [Stockton, CA

    2010-06-29

    A system for removing matter from a conduit. The system includes the steps of passing a transport vehicle and a shape memory polymer material through the conduit, transmitting energy to the shape memory polymer material for moving the shape memory polymer material from a first shape to a second and different shape, and withdrawing the transport vehicle and the shape memory polymer material through the conduit carrying the matter.

  4. Recent Advances in Shape Memory Soft Materials for Biomedical Applications.

    Science.gov (United States)

    Chan, Benjamin Qi Yu; Low, Zhi Wei Kenny; Heng, Sylvester Jun Wen; Chan, Siew Yin; Owh, Cally; Loh, Xian Jun

    2016-04-27

    Shape memory polymers (SMPs) are smart and adaptive materials able to recover their shape through an external stimulus. This functionality, combined with the good biocompatibility of polymers, has garnered much interest for biomedical applications. In this review, we discuss the design considerations critical to the successful integration of SMPs for use in vivo. We also highlight recent work on three classes of SMPs: shape memory polymers and blends, shape memory polymer composites, and shape memory hydrogels. These developments open the possibility of incorporating SMPs into device design, which can lead to vast technological improvements in the biomedical field.

  5. Transparency windows of the plasmonic nanostructure composed of C-shaped and U-shaped resonators

    Science.gov (United States)

    Zhou, Xin; Ouyang, Min; Tang, Bin; Wang, Zhibing; He, Jun

    2017-02-01

    We in this study investigated numerically the plasmon-induced transparency (PIT) effect on the plasmonic nanostructures composed of C-shaped and U-shaped resonators by using finite difference time domain (FDTD) method. The PIT effect in the nanosystem stemmed from the near field coupling between the bright and dark modes. The nanostructure composed of three resonators exhibited double PIT effect. And the PIT spectral response of the proposed nanostructures was demonstrated having a dependence on the parameters of the compound plasmonic system such as the widths of C-shaped resonator and U-shaped resonator, the resonators spatial arrangement and the edge-to-edge distance between the adjacent resonators. The electric and magnetic field distributions of certain resonance wavelengths were also given to discuss the underlying physics. The resonator design strategy opens up a rich pathway to develop the building block of systems for all optical switching, plasmonic sensing applications.

  6. Apparatuses and methods for generating electric fields

    Science.gov (United States)

    Scott, Jill R; McJunkin, Timothy R; Tremblay, Paul L

    2013-08-06

    Apparatuses and methods relating to generating an electric field are disclosed. An electric field generator may include a semiconductive material configured in a physical shape substantially different from a shape of an electric field to be generated thereby. The electric field is generated when a voltage drop exists across the semiconductive material. A method for generating an electric field may include applying a voltage to a shaped semiconductive material to generate a complex, substantially nonlinear electric field. The shape of the complex, substantially nonlinear electric field may be configured for directing charged particles to a desired location. Other apparatuses and methods are disclosed.

  7. Shaping Adolescent Gambling Behavior.

    Science.gov (United States)

    Arcuri, Alan F.; And Others

    1985-01-01

    Surveyed the incidence of casino gambling by adolescents. Results indicated that 64 percent of the students at one Atlantic City high school had gambled at the casinos. The dangers of shaping compulsive gambling behavior through societal acceptance of legalized gambling are discussed. (Author/BL)

  8. Shape Up Europe

    DEFF Research Database (Denmark)

    Simovska, Venka; Jensen, Bjarne Bruun

    "Shape Up: a School Community Approach to Influencing the Determinants of Childhood Overweight and Obesity, Lessons Learnt" is a report that aims to provide a synthesis of the project overall evaluation documentation, with a view to systematically review and discuss lessons learnt, and to suggest...... recommendations concerning future practice and policy in the area of preventing childhood overweight and obesity....

  9. Aerodynamically shaped vortex generators

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver; Velte, Clara Marika; Øye, Stig

    2016-01-01

    An aerodynamically shaped vortex generator has been proposed, manufactured and tested in a wind tunnel. The effect on the overall performance when applied on a thick airfoil is an increased lift to drag ratio compared with standard vortex generators. Copyright © 2015 John Wiley & Sons, Ltd....

  10. Trends Shaping Education 2010

    Science.gov (United States)

    OECD Publishing (NJ3), 2010

    2010-01-01

    "Trends Shaping Education 2010" brings together evidence showing the effects on education of globalisation, social challenges, changes in the workplace, the transformation of childhood, and ICT. To make the content accessible, each trend is presented on a double page, containing an introduction, two charts with brief descriptive text and a set of…

  11. How life shaped Earth.

    Science.gov (United States)

    Gross, Michael

    2015-10-05

    Earth is much more complex than all the other solar system objects that we know. Thanks to its rich and diverse geology, our planet can offer habitats to a wide range of living species. Emerging insights suggest that this is not just a happy coincidence, but that life itself has in many ways helped to shape the planet.

  12. Shaping Faster Question Answering.

    Science.gov (United States)

    Brooks, Lloyd O.

    To test a hypothesis that question answering speed and accuracy can be increased by an automated shaping procedure, a film, "The Analysis of Behavior," was presented individually by a teaching machine during twice-per-week sessions to one high school student and 12 junior college students. Six of the students were informed of monetary rewards for…

  13. Tornado-Shaped Curves

    Science.gov (United States)

    Martínez, Sol Sáez; de la Rosa, Félix Martínez; Rojas, Sergio

    2017-01-01

    In Advanced Calculus, our students wonder if it is possible to graphically represent a tornado by means of a three-dimensional curve. In this paper, we show it is possible by providing the parametric equations of such tornado-shaped curves.

  14. Analysis of () Line Shape

    Indian Academy of Sciences (India)

    The line shape is also simulated by the Monte–Carlo method, the molecular dissociation contributes to 57% neutral atoms and 53% emission intensity in front of the limiter, and 85% neutral atoms and 82% emission intensity in front of the wall. The processes of atoms and molecules influence on the energy balance is ...

  15. Bend me, shape me

    CERN Multimedia

    2002-01-01

    A Japanese team has found a way to bend and shape silicon substrates by growing a thin layer of diamond on top. The technique has been proposed as an alternative to mechanical bending, which is currently used to make reflective lenses for X-ray systems and particle physics systems (2 paragraphs).

  16. Ferromagnetic shape memory alloys

    Indian Academy of Sciences (India)

    ugc

    (sensor), magnetocaloric (refrigeration), and shape memory effect. (actuation) may be important for their future application. Magnetoresistance (8%). Giant magnetocaloric ..... Experimental studies on Ga. 2. MnNi: SEM, EDAX, DSC. T. M. = 780 K. Homogeneous, composition Ga. 1.9. Mn. 0.8. Ni. 1.02. Secondary electron ...

  17. Duality based contact shape optimization

    DEFF Research Database (Denmark)

    Vondrák, Vít; Dostal, Zdenek; Rasmussen, John

    2001-01-01

    An implementation of semi-analytic method for the sensitivity analysis in contact shape optimization without friction is described. This method is then applied to the contact shape optimization.......An implementation of semi-analytic method for the sensitivity analysis in contact shape optimization without friction is described. This method is then applied to the contact shape optimization....

  18. Styrene-based shape memory foam: fabrication and mathematical modeling

    Science.gov (United States)

    Yao, Yongtao; Zhou, Tianyang; Qin, Chao; Liu, Yanju; Leng, Jinsong

    2016-10-01

    Shape memory polymer foam is a promising kind of structure in the biomedical and aerospace field. Shape memory styrene foam with uniform and controlled open-cell structure was successfully fabricated using a salt particulate leaching method. Shape recovery capability exists for foam programming in both high-temperature compression and low-temperature compression (Shape recovery properties such as shape fixing property and shape recovery ratio were also characterized. In order to provide guidance for the future fabrication of shape memory foam, the theories of Gibson and Ashby as well as differential micromechanics theory were applied to predict Young’s modulus and the mechanical behavior of SMP styrene foams during the compression process.

  19. Breathing Life into Shapes.

    Science.gov (United States)

    Jacobson, Alec

    2015-01-01

    Shape articulation transforms a lifeless geometric object into a vibrant character. Computers enrich artists' toolsets dramatically. They not only endow artists with the power to manipulate virtual 2D and 3D scenes, but they also eliminate tedium and expedite prototyping, freeing artists to focus on creative aspects. With such power comes a temptation to lean entirely on the computer. Computationally intensive animation systems sacrifice real-time feedback for physical accuracy. How can we leverage modern computational power to create the best possible shape deformations while maintaining real-time performance as a mandatory invariant? This article summarizes efforts to answer this, culminating in a deformation system with the quality of slow, nonlinear optimization, but at lightning speed.

  20. Shaping the Social

    DEFF Research Database (Denmark)

    Andersen, Susan; Tolstrup, Janne Schurmann; Rod, Morten Hulvej

    2015-01-01

    BACKGROUND: The social environment at schools is an important setting to promote educational attainment, and health and well-being of young people. However, within upper secondary education there is a need for evidence-based school intervention programmes. The Shaping the Social intervention...... is a comprehensive programme integrating social and educational activities to promote student well-being and reduce smoking and dropout in upper secondary vocational education. The evaluation design is reported here. METHODS/DESIGN: The evaluation employed a non-randomised cluster controlled design, and schools were...... national education registers through a 2-year follow-up period. DISCUSSION: Shaping the Social was designed to address that students at Danish vocational schools constitute a high risk population concerning health behaviour as well as school dropout by modifying the school environment, alongside developing...

  1. Shape Changing Airfoil

    Science.gov (United States)

    Ott, Eric A.

    2005-01-01

    Scoping of shape changing airfoil concepts including both aerodynamic analysis and materials-related technology assessment effort was performed. Three general categories of potential components were considered-fan blades, booster and compressor blades, and stator airfoils. Based on perceived contributions to improving engine efficiency, the fan blade was chosen as the primary application for a more detailed assessment. A high-level aerodynamic assessment using a GE90-90B Block 4 engine cycle and fan blade geometry indicates that blade camber changes of approximately +/-4deg would be sufficient to result in fan efficiency improvements nearing 1 percent. Constraints related to flight safety and failed mode operation suggest that use of the baseline blade shape with actuation to the optimum cruise condition during a portion of the cycle would be likely required. Application of these conditions to the QAT fan blade and engine cycle was estimated to result in an overall fan efficiency gain of 0.4 percent.

  2. Shaping the Social

    DEFF Research Database (Denmark)

    Andersen, Susan; Tolstrup, Janne Schurmann; Rod, Morten Hulvej

    2015-01-01

    is a comprehensive programme integrating social and educational activities to promote student well-being and reduce smoking and dropout in upper secondary vocational education. The evaluation design is reported here. METHODS/DESIGN: The evaluation employed a non-randomised cluster controlled design, and schools were......BACKGROUND: The social environment at schools is an important setting to promote educational attainment, and health and well-being of young people. However, within upper secondary education there is a need for evidence-based school intervention programmes. The Shaping the Social intervention...... national education registers through a 2-year follow-up period. DISCUSSION: Shaping the Social was designed to address that students at Danish vocational schools constitute a high risk population concerning health behaviour as well as school dropout by modifying the school environment, alongside developing...

  3. Social Shaping of Innovation

    DEFF Research Database (Denmark)

    Buur, Jacob; Mack, Alexandra

    - in particular in a large corporation? This workshop explores how innovation is socially shaped in organizations. Based on our experiences with practices around innovation and collaboration, we start from three proposition about the social shaping of innovation: • Ideas don't thrive as text (i.e. we need......Why is it that some business proposals – no matter how well researched with users and business developed – don’t seem to make it through the organizational jungle to become a real product, while others do? How shall we understand the innovative practices that we engage with our ethnographic work...... to consider other media) • Ideas need socialization (ideas are linked to people, we need to be careful about how we support the social innovation context) • Ideas are local (ideas spring out of a local contingency, we need to take care in how we like them to travel)....

  4. Biomedical Shape Memory Polymers

    Directory of Open Access Journals (Sweden)

    SHEN Xue-lin

    2017-07-01

    Full Text Available Shape memory polymers(SMPs are a class of functional "smart" materials that have shown bright prospects in the area of biomedical applications. The novel smart materials with multifunction of biodegradability and biocompatibility can be designed based on their general principle, composition and structure. In this review, the latest process of three typical biodegradable SMPs(poly(lactide acide, poly(ε-caprolactone, polyurethane was summarized. These three SMPs were classified in different structures and discussed, and shape-memory mechanism, recovery rate and fixed rate, response speed was analysed in detail, also, some biomedical applications were presented. Finally, the future development and applications of SMPs are prospected: two-way SMPs and body temperature induced SMPs will be the focus attension by researchers.

  5. Audiometric shape and presbycusis.

    Science.gov (United States)

    Demeester, Kelly; van Wieringen, Astrid; Hendrickx, Jan-jaap; Topsakal, Vedat; Fransen, Erik; van Laer, Lut; Van Camp, Guy; Van de Heyning, Paul

    2009-04-01

    The aim of this study was to describe the prevalence of specific audiogram configurations in a healthy, otologically screened population between 55 and 65 years old. The audiograms of 1147 subjects (549 males and 598 females between 55 and 65 years old) were collected through population registries and classified according to the configuration of hearing loss. Gender and noise/solvent-exposure effects on the prevalence of the different audiogram shapes were determined statistically. In our population 'Flat' audiograms were most dominantly represented (37%) followed by 'High frequency Gently sloping' audiograms (35%) and 'High frequency Steeply sloping' audiograms (27%). 'Low frequency Ascending' audiograms, 'Mid frequency U-shape' audiograms and 'Mid frequency Reverse U-shape' audiograms were very rare (together less than 1%). The 'Flat'-configuration was significantly more common in females, whereas the 'High frequency Steeply sloping'-configuration was more common in males. Exposure to noise and/or solvents did not change this finding. In addition, females with a 'Flat' audiogram had a significantly larger amount of overall hearing loss compared to males. Furthermore, our data reveal a significant association between the prevalence of 'High frequency Steeply sloping' audiograms and the degree of noise/solvent exposure, despite a relatively high proportion of non-exposed subjects showing a 'High frequency Steeply sloping' audiogram as well.

  6. Simple Array Beam-Shaping Using Phase-Only Adjustments.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-07-01

    Conventional beam-shaping for array antennas is accomplished via an amplitude-taper on the elemental radiators. It is well known that proper manipulation of the elemental phases can also shape the antenna far-field pattern. A fairly simple transformation from a desired amplitude-taper to a phase-taper can yield nearly equivalent results.

  7. Towards robust and effective shape modeling: sparse shape composition.

    Science.gov (United States)

    Zhang, Shaoting; Zhan, Yiqiang; Dewan, Maneesh; Huang, Junzhou; Metaxas, Dimitris N; Zhou, Xiang Sean

    2012-01-01

    Organ shape plays an important role in various clinical practices, e.g., diagnosis, surgical planning and treatment evaluation. It is usually derived from low level appearance cues in medical images. However, due to diseases and imaging artifacts, low level appearance cues might be weak or misleading. In this situation, shape priors become critical to infer and refine the shape derived by image appearances. Effective modeling of shape priors is challenging because: (1) shape variation is complex and cannot always be modeled by a parametric probability distribution; (2) a shape instance derived from image appearance cues (input shape) may have gross errors; and (3) local details of the input shape are difficult to preserve if they are not statistically significant in the training data. In this paper we propose a novel Sparse Shape Composition model (SSC) to deal with these three challenges in a unified framework. In our method, a sparse set of shapes in the shape repository is selected and composed together to infer/refine an input shape. The a priori information is thus implicitly incorporated on-the-fly. Our model leverages two sparsity observations of the input shape instance: (1) the input shape can be approximately represented by a sparse linear combination of shapes in the shape repository; (2) parts of the input shape may contain gross errors but such errors are sparse. Our model is formulated as a sparse learning problem. Using L1 norm relaxation, it can be solved by an efficient expectation-maximization (EM) type of framework. Our method is extensively validated on two medical applications, 2D lung localization in X-ray images and 3D liver segmentation in low-dose CT scans. Compared to state-of-the-art methods, our model exhibits better performance in both studies. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Abstract shape analysis of RNA.

    Science.gov (United States)

    Janssen, Stefan; Giegerich, Robert

    2014-01-01

    Abstract shape analysis abstract shape analysis is a method to learn more about the complete Boltzmann ensemble of the secondary structures of a single RNA molecule. Abstract shapes classify competing secondary structures into classes that are defined by their arrangement of helices. It allows us to compute, in addition to the structure of minimal free energy, a set of structures that represents relevant and interesting structural alternatives. Furthermore, it allows to compute probabilities of all structures within a shape class. This allows to ensure that our representative subset covers the complete Boltzmann ensemble, except for a portion of negligible probability. This chapter explains the main functions of abstract shape analysis, as implemented in the tool RNA shapes. RNA shapes It reports on some other types of analysis that are based on the abstract shapes idea and shows how you can solve novel problems by creating your own shape abstractions.

  9. Constraining Light Colored Particles with Event Shapes

    Science.gov (United States)

    Kaplan, David E.; Schwartz, Matthew D.

    2008-07-01

    Using recently developed techniques for computing event shapes with soft-collinear effective theory, CERN Large Electron Positron Collider event shape data are used to derive strong model-independent bounds on new colored particles. In the effective field theory computation, colored particles contribute in loops not only to the running of αs but also to the running of hard, jet, and soft functions. Moreover, the differential distribution in the effective theory explicitly probes many energy scales, so even shapes have a strong sensitivity to new particle thresholds. Using thrust data from ALEPH and OPAL, colored adjoint fermions (such as a gluino) below 51.0 GeV are ruled out to 95% confidence. This is nearly an order-of-magnitude improvement over the previous model-independent bound of 6.3 GeV.

  10. Polymorphic Ring-Shaped Molecular Clusters Made of Shape-Variable Building Blocks

    Directory of Open Access Journals (Sweden)

    Keitel Cervantes-Salguero

    2015-02-01

    Full Text Available Self-assembling molecular building blocks able to dynamically change their shapes, is a concept that would offer a route to reconfigurable systems. Although simulation studies predict novel properties useful for applications in diverse fields, such kinds of building blocks, have not been implemented thus far with molecules. Here, we report shape-variable building blocks fabricated by DNA self-assembly. Blocks are movable enough to undergo shape transitions along geometrical ranges. Blocks connect to each other and assemble into polymorphic ring-shaped clusters via the stacking of DNA blunt-ends. Reconfiguration of the polymorphic clusters is achieved by the surface diffusion on mica substrate in response to a monovalent salt concentration. This work could inspire novel reconfigurable self-assembling systems for applications in molecular robotics.

  11. Propagating uncertainties in statistical model based shape prediction

    Science.gov (United States)

    Syrkina, Ekaterina; Blanc, Rémi; Székely, Gàbor

    2011-03-01

    This paper addresses the question of accuracy assessment and confidence regions estimation in statistical model based shape prediction. Shape prediction consists in estimating the shape of an organ based on a partial observation, due e.g. to a limited field of view or poorly contrasted images, and generally requires a statistical model. However, such predictions can be impaired by several sources of uncertainty, in particular the presence of noise in the observation, limited correlations between the predictors and the shape to predict, as well as limitations of the statistical shape model - in particular the number of training samples. We propose a framework which takes these into account and derives confidence regions around the predicted shape. Our method relies on the construction of two separate statistical shape models, for the predictors and for the unseen parts, and exploits the correlations between them assuming a joint Gaussian distribution. Limitations of the models are taken into account by jointly optimizing the prediction and minimizing the shape reconstruction error through cross-validation. An application to the prediction of the shape of the proximal part of the human tibia given the shape of the distal femur is proposed, as well as the evaluation of the reliability of the estimated confidence regions, using a database of 184 samples. Potential applications are reconstructive surgery, e.g. to assess whether an implant fits in a range of acceptable shapes, or functional neurosurgery when the target's position is not directly visible and needs to be inferred from nearby visible structures.

  12. Microbial synthesis of Flower-shaped gold nanoparticles.

    Science.gov (United States)

    Singh, Priyanka; Kim, Yeon Ju; Wang, Chao; Mathiyalagan, Ramya; Yang, Deok Chun

    2016-09-01

    The shape of nanoparticles has been recognized as an important attribute that determines their applicability in various fields. The flower shape (F-shape) has been considered and is being focused on, because of its enhanced properties when compared to the properties of the spherical shape. The present study proposed the microbial synthesis of F-shaped gold nanoparticles within 48 h using the Bhargavaea indica DC1 strain. The F-shaped gold nanoparticles were synthesized extracellularly by the reduction of auric acid in the culture supernatant of B. indica DC1. The shape, size, purity, and crystalline nature of F-shaped gold nanoparticles were revealed by various instrumental techniques including UV-Vis, FE-TEM, EDX, elemental mapping, XRD, and DLS. The UV-Vis absorbance showed a maximum peak at 536 nm. FE-TEM revealed the F-shaped structure of nanoparticles. The EDX peak obtained at 2.3 keV indicated the purity. The peaks obtained on XRD analysis corresponded to the crystalline nature of the gold nanoparticles. In addition, the results of elemental mapping indicated the maximum distribution of gold elements in the nanoproduct obtained. Particle size analysis revealed that the average diameter of the F-shaped gold nanoparticles was 106 nm, with a polydispersity index (PDI) of 0.178. Thus, the methodology developed for the synthesis of F-shaped gold nanoparticles is completely green and economical.

  13. Oriented active shape models.

    Science.gov (United States)

    Liu, Jiamin; Udupa, Jayaram K

    2009-04-01

    Active shape models (ASM) are widely employed for recognizing anatomic structures and for delineating them in medical images. In this paper, a novel strategy called oriented active shape models (OASM) is presented in an attempt to overcome the following five limitations of ASM: 1) lower delineation accuracy, 2) the requirement of a large number of landmarks, 3) sensitivity to search range, 4) sensitivity to initialization, and 5) inability to fully exploit the specific information present in the given image to be segmented. OASM effectively combines the rich statistical shape information embodied in ASM with the boundary orientedness property and the globally optimal delineation capability of the live wire methodology of boundary segmentation. The latter characteristics allow live wire to effectively separate an object boundary from other nonobject boundaries with similar properties especially when they come very close in the image domain. The approach leads to a two-level dynamic programming method, wherein the first level corresponds to boundary recognition and the second level corresponds to boundary delineation, and to an effective automatic initialization method. The method outputs a globally optimal boundary that agrees with the shape model if the recognition step is successful in bringing the model close to the boundary in the image. Extensive evaluation experiments have been conducted by utilizing 40 image (magnetic resonance and computed tomography) data sets in each of five different application areas for segmenting breast, liver, bones of the foot, and cervical vertebrae of the spine. Comparisons are made between OASM and ASM based on precision, accuracy, and efficiency of segmentation. Accuracy is assessed using both region-based false positive and false negative measures and boundary-based distance measures. The results indicate the following: 1) The accuracy of segmentation via OASM is considerably better than that of ASM; 2) The number of landmarks

  14. Lower bounds on Q of some dipole shapes

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.

    2016-01-01

    The lower bound on the radiation Q of an arbitrary electrically small antenna shape can be determined by finding the optimal electric current density on the exterior surface of the shape, such that the Q of this current radiating in free space is minimized, and then augmenting it with a magnetic...... current density cancelling the fields inside the shape's surface. The Q of these coupled electric and magnetic currents radiating in free space is the lower bound on Q for the given shape. The approach is exemplified and its general applicability is substantiated by computing the lower bounds...

  15. Mechanisms of the Shape Memory Effect in Polymeric Materials

    Directory of Open Access Journals (Sweden)

    Xuelian Wu

    2013-09-01

    Full Text Available This review paper summarizes the recent research progress in the underlying mechanisms behind the shape memory effect (SME and some newly discovered shape memory phenomena in polymeric materials. It is revealed that most polymeric materials, if not all, intrinsically have the thermo/chemo-responsive SME. It is demonstrated that a good understanding of the fundamentals behind various types of shape memory phenomena in polymeric materials is not only useful in design/synthesis of new polymeric shape memory materials (SMMs with tailored performance, but also helpful in optimization of the existing ones, and thus remarkably widens the application field of polymeric SMMs.

  16. Pairwise harmonics for shape analysis

    KAUST Repository

    Zheng, Youyi

    2013-07-01

    This paper introduces a simple yet effective shape analysis mechanism for geometry processing. Unlike traditional shape analysis techniques which compute descriptors per surface point up to certain neighborhoods, we introduce a shape analysis framework in which the descriptors are based on pairs of surface points. Such a pairwise analysis approach leads to a new class of shape descriptors that are more global, discriminative, and can effectively capture the variations in the underlying geometry. Specifically, we introduce new shape descriptors based on the isocurves of harmonic functions whose global maximum and minimum occur at the point pair. We show that these shape descriptors can infer shape structures and consistently lead to simpler and more efficient algorithms than the state-of-the-art methods for three applications: intrinsic reflectional symmetry axis computation, matching shape extremities, and simultaneous surface segmentation and skeletonization. © 2012 IEEE.

  17. Mast Wake Reduction by Shaping

    National Research Council Canada - National Science Library

    Beauchamp, Charles H

    2005-01-01

    The present invention relates to various mast shapes, in which the mast shapes minimize the production of visible, electro-optic, infrared and radar cross section wake signatures produced by water surface piercing masts...

  18. Issues in Biological Shape Modelling

    DEFF Research Database (Denmark)

    Hilger, Klaus Baggesen

    This talk reflects parts of the current research at informatics and Mathematical Modelling at the Technical University of Denmark within biological shape modelling. We illustrate a series of generalizations, modifications, and applications of the elements of constructing models of shape or appear......This talk reflects parts of the current research at informatics and Mathematical Modelling at the Technical University of Denmark within biological shape modelling. We illustrate a series of generalizations, modifications, and applications of the elements of constructing models of shape...

  19. What shapes output of policy reform?

    DEFF Research Database (Denmark)

    Carlsen, Kirsten

    This thesis deals with the factors shaping forest policy output during the stages implementation and bases its main message on empirical findings from the forestry sector in Ghana. Policy and institutional factors are important underlying causes for deforestation, especially in the tropics. Fores...... government, civil society, timber industry and local communities and thus provides important contributions to the existing logic within the field of tropical forest governance....

  20. Laser beam shaping theory and techniques, second edition

    CERN Document Server

    Dickey, Fred M

    2014-01-01

    Laser Beam Shaping: Theory and Techniques addresses the theory and practice of every important technique for lossless beam shaping. Complete with experimental results as well as guidance on when beam shaping is practical and when each technique is appropriate, the Second Edition is updated to reflect significant developments in the field. This authoritative text:Features new chapters on axicon light ring generation systems, laser-beam-splitting (fan-out) gratings, vortex beams, and microlens diffusersDescribes the latest advances in beam profile measurement technology and laser beam shaping using diffractive diffusersContains new material on wavelength dependence, channel integrators, geometrical optics, and optical softwareLaser Beam Shaping: Theory and Techniques, Second Edition not only provides a working understanding of the fundamentals, but also offers insight into the potential application of laser-beam-profile shaping in laser system design.

  1. The quintuple-shape memory effect in electrospun nanofiber membranes

    Science.gov (United States)

    Zhang, Fenghua; Zhang, Zhichun; Liu, Yanju; Lu, Haibao; Leng, Jinsong

    2013-08-01

    Shape memory fibrous membranes (SMFMs) are an emerging class of active polymers, which are capable of switching from a temporary shape to their permanent shape upon appropriate stimulation. Quintuple-shape memory membranes based on the thermoplastic polymer Nafion, with a stable fibrous structure, are achieved via electrospinning technology, and possess a broad transition temperature. The recovery of multiple temporary shapes of electrospun membranes can be triggered by heat in a single triple-, quadruple-, quintuple-shape memory cycle, respectively. The fiber morphology and nanometer size provide unprecedented design flexibility for the adjustable morphing effect. SMFMs enable complex deformations at need, having a wide potential application field including smart textiles, artificial intelligence robots, bio-medical engineering, aerospace technologies, etc in the future.

  2. The shape dependence of chameleon screening

    Science.gov (United States)

    Burrage, Clare; Copeland, Edmund J.; Moss, Adam; Stevenson, James A.

    2018-01-01

    Chameleon scalar fields can screen their associated fifth forces from detection by changing their mass with the local density. These models are an archetypal example of a screening mechanism, and have become an important target for both cosmological surveys and terrestrial experiments. In particular there has been much recent interest in searching for chameleon fifth forces in the laboratory. It is known that the chameleon force is less screened around non-spherical sources, but only the field profiles around a few simple shapes are known analytically. In this work we introduce a numerical code that solves for the chameleon field around arbitrary shapes with azimuthal symmetry placed in a spherical vacuum chamber. We find that deviations from spherical symmetry can increase the chameleon acceleration experienced by a test particle, and that the least screened objects are those which minimize some internal dimension. For the shapes considered in this work, keeping the mass, density and background environment fixed, the accelerations due to the source varied by a factor of ~ 3.

  3. Shaping 3-D boxes

    DEFF Research Database (Denmark)

    Stenholt, Rasmus; Madsen, Claus B.

    2011-01-01

    Enabling users to shape 3-D boxes in immersive virtual environments is a non-trivial problem. In this paper, a new family of techniques for creating rectangular boxes of arbitrary position, orientation, and size is presented and evaluated. These new techniques are based solely on position data......F) docking experiment against an existing technique, which requires the user to perform the rotation and scaling of the box explicitly. The precision of the users' box construction is evaluated by a novel error metric measuring the difference between two boxes. The results of the experiment strongly indicate...... that for precision docking of 9 DoF boxes, some of the proposed techniques are significantly better than ones with explicit rotation and scaling. Another interesting result is that the number of DoF simultaneously controlled by the user significantly influences the precision of the docking....

  4. Magnetic Shape Memory Microactuators

    Directory of Open Access Journals (Sweden)

    Manfred Kohl

    2014-11-01

    Full Text Available By introducing smart materials in micro systems technologies, novel smart microactuators and sensors are currently being developed, e.g., for mobile, wearable, and implantable MEMS (Micro-electro-mechanical-system devices. Magnetic shape memory alloys (MSMAs are a promising material system as they show multiple coupling effects as well as large, abrupt changes in their physical properties, e.g., of strain and magnetization, due to a first order phase transformation. For the development of MSMA microactuators, considerable efforts are undertaken to fabricate MSMA foils and films showing similar and just as strong effects compared to their bulk counterparts. Novel MEMS-compatible technologies are being developed to enable their micromachining and integration. This review gives an overview of material properties, engineering issues and fabrication technologies. Selected demonstrators are presented illustrating the wide application potential.

  5. SHAPE Selection (SHAPES) enrich for RNA structure signal in SHAPE sequencing-based probing data

    Science.gov (United States)

    Poulsen, Line Dahl; Kielpinski, Lukasz Jan; Salama, Sofie R.; Krogh, Anders; Vinther, Jeppe

    2015-01-01

    Selective 2′ Hydroxyl Acylation analyzed by Primer Extension (SHAPE) is an accurate method for probing of RNA secondary structure. In existing SHAPE methods, the SHAPE probing signal is normalized to a no-reagent control to correct for the background caused by premature termination of the reverse transcriptase. Here, we introduce a SHAPE Selection (SHAPES) reagent, N-propanone isatoic anhydride (NPIA), which retains the ability of SHAPE reagents to accurately probe RNA structure, but also allows covalent coupling between the SHAPES reagent and a biotin molecule. We demonstrate that SHAPES-based selection of cDNA–RNA hybrids on streptavidin beads effectively removes the large majority of background signal present in SHAPE probing data and that sequencing-based SHAPES data contain the same amount of RNA structure data as regular sequencing-based SHAPE data obtained through normalization to a no-reagent control. Moreover, the selection efficiently enriches for probed RNAs, suggesting that the SHAPES strategy will be useful for applications with high-background and low-probing signal such as in vivo RNA structure probing. PMID:25805860

  6. Photo-Responsive Shape-Memory and Shape-Changing Liquid-Crystal Polymer Networks

    Directory of Open Access Journals (Sweden)

    Danish Iqbal

    2013-01-01

    Full Text Available “Surrounding matters” is a phrase that has become more significant in recent times when discussing polymeric materials. Although regular polymers do respond to external stimuli like softening of material at higher temperatures, that response is gradual and linear in nature. Smart polymers (SPs or stimuli-responsive polymers (SRPs behave differently to those external stimuli, as their behavior is more rapid and nonlinear in nature and even a small magnitude of external stimulus can cause noticeable changes in their shape, size, color or conductivity. Of these SRPs, two types of SPs with the ability to actively change can be differentiated: shape-memory polymers and shape-changing polymers. The uniqueness of these materials lies not only in the fast macroscopic changes occurring in their structure but also in that some of these shape changes are reversible. This paper presents a brief review of current progress in the area of light activated shape-memory polymers and shape-changing polymers and their possible field of applications.

  7. Shape-controlled nanostructures in heterogeneous catalysis.

    Science.gov (United States)

    Zaera, Francisco

    2013-10-01

    Nanotechnologies have provided new methods for the preparation of nanomaterials with well-defined sizes and shapes, and many of those procedures have been recently implemented for applications in heterogeneous catalysis. The control of nanoparticle shape in particular offers the promise of a better definition of catalytic activity and selectivity through the optimization of the structure of the catalytic active site. This extension of new nanoparticle synthetic procedures to catalysis is in its early stages, but has shown some promising leads already. Here, we survey the major issues associated with this nanotechnology-catalysis synergy. First, we discuss new possibilities associated with distinguishing between the effects originating from nanoparticle size versus those originating from nanoparticle shape. Next, we survey the information available to date on the use of well-shaped metal and non-metal nanoparticles as active phases to control the surface atom ensembles that define the catalytic site in different catalytic applications. We follow with a brief review of the use of well-defined porous materials for the control of the shape of the space around that catalytic site. A specific example is provided to illustrate how new selective catalysts based on shape-defined nanoparticles can be designed from first principles by using fundamental mechanistic information on the reaction of interest obtained from surface-science experiments and quantum-mechanics calculations. Finally, we conclude with some thoughts on the state of the field in terms of the advances already made, the future potentials, and the possible limitations to be overcome. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Shape integral method for magnetospheric shapes. [boundary layer calculations

    Science.gov (United States)

    Michel, F. C.

    1979-01-01

    A method is developed for calculating the shape of any magnetopause to arbitrarily high precision. The method uses an integral equation which is evaluated for a trial shape. The resulting values of the integral equation as a function of auxiliary variables indicate how close one is to the desired solution. A variational method can then be used to improve the trial shape. Some potential applications are briefly mentioned.

  9. Nonparametric joint shape learning for customized shape modeling

    OpenAIRE

    Ünal, Gözde; Unal, Gozde

    2010-01-01

    We present a shape optimization approach to compute patient-specific models in customized prototyping applications. We design a coupled shape prior to model the transformation between a related pair of surfaces, using a nonparametric joint probability density estimation. The coupled shape prior forces with the help of application-specific data forces and smoothness forces drive a surface deformation towards a desired output surface. We demonstrate the usefulness of the method for generatin...

  10. Shape vocabulary: a robust and efficient shape representation for shape matching.

    Science.gov (United States)

    Bai, Xiang; Rao, Cong; Wang, Xinggang

    2014-09-01

    In this paper, a learning-based shape descriptor for shape matching is demonstrated. Formulated in a bag-of-words like framework, the proposed method summarizes the local features extracted from certain shape to generate a integrated representation. It contributes to the speed-up of shape matching, since the distance metric in the vector space analysis can be directly applied to compare the constructed global descriptors, eliminating the time consuming stage of local feature matching. Similar to the philosophy in spatial pyramid matching, a strategy for feature division is applied in the phase of encoded feature pooling and vocabulary learning, which helps to construct a more discriminative descriptor incorporating both global and local information. Also, a local contour-based feature extraction method is designed for 2D shapes, while significant properties of the local contours are inspected for the design of feature division rules. The designed local feature extraction method and the feature division rules manage to reduce the variances of shape representation due to the changes in rotation. In addition to 2D shape, we also present a simple and natural method to extend the proposed method to the scenario of 3D shape representation. The proposed shape descriptor is validated on several benchmark data sets for evaluating 2D and 3D shape matching algorithms, and it is observed that the investigated shape descriptor maintains superior discriminative power as well as high time efficiency.

  11. Pathways to Shape the Bioeconomy

    Directory of Open Access Journals (Sweden)

    Carmen Priefer

    2017-02-01

    Full Text Available In view of the increasing depletion of fossil fuel resources, the concept “bioeconomy” aims at the gradual replacement of fossil fuels by renewable feedstock. Seen as a comprehensive societal transition, the bioeconomy is a complex field that includes a variety of sectors, actors, and interests and is related to far-reaching changes in today’s production systems. While the objectives pursued—such as reducing dependence on fossil fuels, mitigating climate change, ensuring global food security, and increasing the industrial use of biogenic resources—are not generally contentious, there is fierce controversy over the possible pathways for achieving these objectives. Based on a thorough literature review, the article identifies major lines of conflict in the current discourse. Criticism of the prevalent concept refers mainly to the strong focus on technology, the lack of consideration given to alternative implementation pathways, the insufficient differentiation of underlying sustainability requirements, and the inadequate participation of societal stakeholders. Since today it cannot be predicted which pathway will be the most expedient—the one already being taken or one of the others proposed—this paper suggests pursuing a strategy of diversity concerning the approaches to shape the bioeconomy, the funding of research topics, and the involvement of stakeholders.

  12. Surface shape memory in polymers

    Science.gov (United States)

    Mather, Patrick

    2012-02-01

    Many crosslinked polymers exhibit a shape memory effect wherein a permanent shape can be prescribed during crosslinking and arbitrary temporary shapes may be set through network chain immobilization. Researchers have extensively investigated such shape memory polymers in bulk form (bars, films, foams), revealing a multitude of approaches. Applications abound for such materials and a significant fraction of the studies in this area concern application-specific characterization. Recently, we have turned our attention to surface shape memory in polymers as a means to miniaturization of the effect, largely motivated to study the interaction of biological cells with shape memory polymers. In this presentation, attention will be given to several approaches we have taken to prepare and study surface shape memory phenomenon. First, a reversible embossing study involving a glassy, crosslinked shape memory material will be presented. Here, the permanent shape was flat while the temporary state consisted of embossed parallel groves. Further the fixing mechanism was vitrification, with Tg adjusted to accommodate experiments with cells. We observed that the orientation and spreading of adherent cells could be triggered to change by the topographical switch from grooved to flat. Second, a functionally graded shape memory polymer will be presented, the grading being a variation in glass transition temperature in one direction along the length of films. Characterization of the shape fixing and recovery of such films utilized an indentation technique that, along with polarizing microscopy, allowed visualization of stress distribution in proximity to the indentations. Finally, very recent research concerning shape memory induced wrinkle formation on polymer surfaces will be presented. A transformation from smooth to wrinkled surfaces at physiological temperatures has been observed to have a dramatic effect on the behavior of adherent cells. A look to the future in research and

  13. Mean gust shapes

    DEFF Research Database (Denmark)

    Larsen, Gunner Chr.

    2003-01-01

    The gust events described in the IEC-standard are formulated as coherent gusts of an inherent deterministic character, whereas the gusts experienced in real situation are of a stochastic nature with a limited spatial extension. This conceptual differencemay cause substantial differences in the load...... on the spatial structure of the wind speed gust and relies only on conventional wind fieldparameters. The theoretical expression is verified by comparison with simulated wind fields as well as with measured wind fields covering a broad range of mean wind speed situations and terrain conditions. The work reported...... makes part of the project“Modelling of Extreme Gusts for Design Calculations ” (NEWGUST), which is co-funded through JOULEIII on contract no. JOR3-CT98-0239....

  14. Shaping a Scientific Self

    DEFF Research Database (Denmark)

    Andrade-Molina, Melissa; Valero, Paola

    us to understand how a truth is reproduced, circulating among diverse fields of human knowledge. Also it will show why we accept and reproduce a particular discourse. Finally, we state Euclidean geometry as a truth that circulates in scientific discourse and performs a scientific self. We unfold...... the importance of having students following the path of what schools perceive a real scientist is, no to become a scientist, but to become a logical thinker, a problem solver, a productive citizen who uses reason....

  15. Vaccines: Shaping global health.

    Science.gov (United States)

    Pagliusi, Sonia; Ting, Ching-Chia; Lobos, Fernando

    2017-03-14

    The Developing Countries Vaccine Manufacturers' Network (DCVMN) gathered leaders in immunization programs, vaccine manufacturing, representatives of the Argentinean Health Authorities and Pan American Health Organization, among other global health stakeholders, for its 17th Annual General Meeting in Buenos Aires, to reflect on how vaccines are shaping global health. Polio eradication and elimination of measles and rubella from the Americas is a result of successful collaboration, made possible by timely supply of affordable vaccines. After decades of intense competition for high-value markets, collaboration with developing countries has become critical, and involvement of multiple manufacturers as well as public- and private-sector investments are essential, for developing new vaccines against emerging infectious diseases. The recent Zika virus outbreak and the accelerated Ebola vaccine development exemplify the need for international partnerships to combat infectious diseases. A new player, Coalition for Epidemic Preparedness Innovations (CEPI) has made its entrance in the global health community, aiming to stimulate research preparedness against emerging infections. Face-to-face panel discussions facilitated the dialogue around challenges, such as risks of viability to vaccine development and regulatory convergence, to improve access to sustainable vaccine supply. It was discussed that joint efforts to optimizing regulatory pathways in developing countries, reducing registration time by up to 50%, are required. Outbreaks of emerging infections and the global Polio eradication and containment challenges are reminders of the importance of vaccines' access, and of the importance of new public-private partnerships. Copyright © 2017.

  16. Porous inorganic—organic shape memory polymers

    Science.gov (United States)

    Zhang, Dawei; Burkes, William L.; Schoener, Cody A.; Grunlan, Melissa A.

    2012-01-01

    Thermoresponsive shape memory polymers (SMPs) are a type of stimuli-sensitive materials that switch from a temporary shape back to their permanent shape upon exposure to heat. While the majority of SMPs have been fabricated in the solid form, porous SMP foams exhibit distinct properties and are better suited for certain applications, including some in the biomedical field. Like solid SMPs, SMP foams have been restricted to a limited group of organic polymer systems. In this study, we prepared inorganic–organic SMP foams based on the photochemical cure of a macromer comprised of inorganic polydimethylsiloxane (PDMS) segments and organic poly(ε-caprolactone) (PCL) segments, diacrylated PCL40-block-PDMS37-block-PCL40. To achieve tunable pore size with high interconnectivity, the SMP foams were prepared via a refined solvent-casting/particulate-leaching (SCPL) method. By varying design parameters such as degree of salt fusion, macromer concentration in the solvent and salt particle size, the SMP foams with excellent shape memory behavior and tunable pore size, pore morphology, and modulus were obtained. PMID:22956854

  17. Combined Shape and Topology Optimization

    DEFF Research Database (Denmark)

    Christiansen, Asger Nyman

    Shape and topology optimization seeks to compute the optimal shape and topology of a structure such that one or more properties, for example stiffness, balance or volume, are improved. The goal of the thesis is to develop a method for shape and topology optimization which uses the Deformable...... Simplicial Complex (DSC) method. Consequently, we present a novel method which combines current shape and topology optimization methods. This method represents the surface of the structure explicitly and discretizes the structure into non-overlapping elements, i.e. a simplicial complex. An explicit surface...... representation usually limits the optimization to minor shape changes. However, the DSC method uses a single explicit representation and still allows for large shape and topology changes. It does so by constantly applying a set of mesh operations during deformations of the structure. Using an explicit instead...

  18. Virtual Technologies and Social Shaping

    OpenAIRE

    Kreps, David

    2010-01-01

    International audience; Virtual Technologies have enabled us all to become publishers and broadcasters. The world of information has become saturated with a multitude of opinions, and opportunities to express them. Track 2 "Virtual Technologies and Social Shaping" of the 9th Conference on Human Choice and Computers (HCC9) explores some of the issues that have arisen in this new information society, how we are shaped by it, and how we shape it, through i) two papers addressing issues of identi...

  19. Detail-replicating shape stretching

    OpenAIRE

    Alhashim, Ibraheem Abbas

    2011-01-01

    Mesh deformation methods are useful for creating shape variations. Existing deformation techniques work on preserving surface details under bending and twisting operations. Stretching different parts of a shape is also a useful operation for generating shape variations. Under stretching, texture-like geometric details should not be preserved but rather replicated. We propose a simple method that help create model variation by applying non-uniform stretching on 3D models. The method replicates...

  20. Nanoscale magnetic ratchets based on shape anisotropy

    Science.gov (United States)

    Cui, Jizhai; Keller, Scott M.; Liang, Cheng-Yen; Carman, Gregory P.; Lynch, Christopher S.

    2017-02-01

    Controlling magnetization using piezoelectric strain through the magnetoelectric effect offers several orders of magnitude reduction in energy consumption for spintronic applications. However strain is a uniaxial effect and, unlike directional magnetic field or spin-polarized current, cannot induce a full 180° reorientation of the magnetization vector when acting alone. We have engineered novel ‘peanut’ and ‘cat-eye’ shaped nanomagnets on piezoelectric substrates that undergo repeated deterministic 180° magnetization rotations in response to individual electric-field-induced strain pulses by breaking the uniaxial symmetry using shape anisotropy. This behavior can be likened to a magnetic ratchet, advancing magnetization clockwise with each piezostrain trigger. The results were validated using micromagnetics implemented in a multiphysics finite elements code to simulate the engineered spatial and temporal magnetic behavior. The engineering principles start from a target device function and proceed to the identification of shapes that produce the desired function. This approach opens a broad design space for next generation magnetoelectric spintronic devices.

  1. Computation-Friendly Shape Grammars with Application to Determining the Interior Layout of Buildings from Image Data

    Science.gov (United States)

    Yue, Kui

    2009-01-01

    A shape grammar is a formalism that has been widely applied, in many different fields, to analyzing designs. Computer implementation of a shape grammar interpreter is vital to both research and application. However, implementing a shape grammar interpreter is hard, especially for parametric shapes defined by open terms. This dissertation…

  2. Cellinoid Shape Model for Asteroids

    Science.gov (United States)

    Lu, Xiaoping; Zhao, Haibin; You, Zhong

    2014-08-01

    The ellipsoid shape model plays an important role in physical research on asteroids. However, its symmetric structure cannot practically simulate real asteroids. This article applies a general shape model, named the cellinoid, instead of the ellipsoid model to simulate the asymmetric shape of asteroids. The cellinoid shape model consists of eight octants of ellipsoids having different semi-axes, with the constraint that adjacent octants must have two equal semi-axes in common. Totally, the shape of the cellinoid model is controlled by six parameters, not three as in the case of the shape of the ellipsoid. Using this shape model, the brightness of asteroids observed from the Earth can be fitted numerically by the surface triangularization of the cellinoid. The Levenberg-Marquardt algorithm is also employed here to solve a nonlinear minimization problem. Owing to the asymmetric shape of the cellinoid, the physical parameters of asteroids, such as the rotation period and pole orientation, can be fitted more accurately than in the case of the ellipsoid model. Finally, this is confirmed numerically by applying the shape to both synthetic light curves and real light curves of asteroids. Additionally, the center of mass and moment of inertia of the cellinoid are analyzed explicitly.

  3. Pulse shaping with transmission lines

    Science.gov (United States)

    Wilcox, Russell B.

    1987-01-01

    A method and apparatus for forming shaped voltage pulses uses passive reflection from a transmission line with nonuniform impedance. The impedance of the reflecting line varies with length in accordance with the desired pulse shape. A high voltage input pulse is transmitted to the reflecting line. A reflected pulse is produced having the desired shape and is transmitted by pulse removal means to a load. Light activated photoconductive switches made of silicon can be utilized. The pulse shaper can be used to drive a Pockels cell to produce shaped optical pulses.

  4. The Shaped Charge Concept. Part 3. Applications of Shaped Charges

    Science.gov (United States)

    1990-10-01

    perforating charges. Well perforator cones usually have an apex angle of 450 to About 600. The smaller angle increases penetation , but the hole size is...hole digging and underwaterdemlition via shaped charles . Byei (1949.1950) picacuw novel shaped chare designs for mining, hole drilling, and boulde

  5. Acoustophoresis in Variously Shaped Liquid Droplets

    CERN Document Server

    Yu, Gan; Xu, Jie; 10.1039/c1sm05871a

    2012-01-01

    The ability to precisely trap, transport and manipulate micrometer-sized objects, including biological cells, DNA-coated microspheres and microorganisms, is very important in life science studies and biomedical applications. In this study, acoustic radiation force in an ultrasonic standing wave field is used for micro-objects manipulation, a technique termed as acoustophoresis. Free surfaces of liquid droplets are used as sound reflectors to confine sound waves inside the droplets. Two techniques were developed for precise control of droplet shapes: edge pinning and hydrophilic/hydrophobic interface pinning. For all tested droplet shapes, including circular, annular and rectangular, our experiments show that polymer micro particles can be manipulated by ultrasound and form into a variety of patterns, for example, concentric rings and radial lines in an annular droplet. The complexity of the pattern increases with increasing frequency, and the observations are in line with simulation results. The acoustic mani...

  6. Isogeometric Analysis and Shape Optimization in Fluid Mechanics

    DEFF Research Database (Denmark)

    Nielsen, Peter Nørtoft

    This thesis brings together the fields of fluid mechanics, as the study of fluids and flows, isogeometric analysis, as a numerical method to solve engineering problems using computers, and shape optimization, as the art of finding "best" shapes of objects based on some notion of goodness. The flow...... approximations, and for shape optimization purposes also due to its tight connection between the analysis and geometry models. The thesis is initiated by short introductions to fluid mechanics, and to the building blocks of isogeometric analysis. As the first contribution of the thesis, a detailed description...... isogeometric analysis may serve as a natural framework for shape optimization within fluid mechanics. We construct an efficient regularization measure for avoiding inappropriate parametrizations during optimization, and various numerical examples of shape optimization for fluids are considered, serving...

  7. Branch length similarity entropy-based descriptors for shape representation

    Science.gov (United States)

    Kwon, Ohsung; Lee, Sang-Hee

    2017-11-01

    In previous studies, we showed that the branch length similarity (BLS) entropy profile could be successfully used for the shape recognition such as battle tanks, facial expressions, and butterflies. In the present study, we proposed new descriptors, roundness, symmetry, and surface roughness, for the recognition, which are more accurate and fast in the computation than the previous descriptors. The roundness represents how closely a shape resembles to a circle, the symmetry characterizes how much one shape is similar with another when the shape is moved in flip, and the surface roughness quantifies the degree of vertical deviations of a shape boundary. To evaluate the performance of the descriptors, we used the database of leaf images with 12 species. Each species consisted of 10 - 20 leaf images and the total number of images were 160. The evaluation showed that the new descriptors successfully discriminated the leaf species. We believe that the descriptors can be a useful tool in the field of pattern recognition.

  8. Particle shape effects in vitro and in vivo.

    Science.gov (United States)

    Harris, Bradley J; Dalhaimer, Paul

    2012-06-01

    Particles that have the potential to deliver imaging agents and drugs to cells and tissue now have many different shapes and sizes. This diversity in particle shape could provide new options for potential treatments of diseases because geometry affects biodistribution. However, the myriad of particle shapes now available increases the number of variables or parameters that must be taken into consideration for the drug delivery field to understand particle-cell interactions. This is especially true when the shape of a particle is a tunable parameter along with particle chemistry, charge, and hydrophobicity. Here we review the impact of shape on particle-cell interactions in vitro and the ramifications of different particle geometries on circulation, biodistribution, localization to tumors, and toxicology in rodents.

  9. Iso-geometric shape optimization of magnetic density separators

    DEFF Research Database (Denmark)

    Dang Manh, Nguyen; Evgrafov, Anton; Gravesen, Jens

    2014-01-01

    Purpose The waste recycling industry increasingly relies on magnetic density separators. These devices generate an upward magnetic force in ferro-fluids allowing to separate the immersed particles according to their mass density. Recently, a new separator design has been proposed that significantly......, these shapes should enable larger amounts of waste to be processed than the previous design. Originality/value This paper treats the shapes optimization of magnetic density separators systematically and presents new shapes for the ferromagnetic poles covers....... is obtained at the cost of a pole cover shape that differs per pole. This limitation has negligible impact on the manufacturing of the separator. The new pole cover shapes therefore lead to improved performance of the density separation. Practical implications Due to the larger uniformity the generated field...

  10. The equilibrium shape of bubbles on curved interfaces

    Science.gov (United States)

    Bird, James; Poe, Daniel; Walls, Peter

    2016-11-01

    The equilibrium shape for a bubble resting at a free surface depends on a balance of hydrostatic and capillary forces, with the smallest bubbles approximating a sphere and a hemisphere for the largest. This shape has been shown to be important to several processes ranging from gas transfer across the thin film cap to the production of jet droplets. Past works calculating the equilibrium shape assume that the interface is flat. However, there are instances where the curvature of the boundary may be comparable to the bubble itself. For example, a bubble bursting on the surface of a rain droplet. Here we relax the assumption of a flat interface and extend the classic bubble shape calculations to account for a curved interface boundary. An understanding of the extent of this deformation and the precise equilibrium bubble shape is important to applications in fields ranging from air-sea exchange to combustion dynamics. We acknowledge financial support from NSF Grant No. 1351466.

  11. Robust, Optimal Subsonic Airfoil Shapes

    Science.gov (United States)

    Rai, Man Mohan

    2014-01-01

    A method has been developed to create an airfoil robust enough to operate satisfactorily in different environments. This method determines a robust, optimal, subsonic airfoil shape, beginning with an arbitrary initial airfoil shape, and imposes the necessary constraints on the design. Also, this method is flexible and extendible to a larger class of requirements and changes in constraints imposed.

  12. Shape Factor Modeling and Simulation

    Science.gov (United States)

    2016-06-01

    10 3. Shape Factor Distributions for Natural Fragments 12 3.1 Platonic Solids and Uniform Viewing from All Viewpoints 12 3.2 Natural Fragments from...12 Fig. 9 The 5 Platonic solids. ............................................................. 12 Fig. 10 Mean shape factor of...of the 5 Platonic solids............................................ 13 Table 3 Sequence of viewing angles in Icosahedron Gage

  13. Shape memory alloy based motor

    Indian Academy of Sciences (India)

    http://www.ias.ac.in/article/fulltext/sadh/033/05/0699-0712. Keywords. Shape Memory Alloy (SMA); poly phase; rotary actuator; torque; ripple. Abstract. Design and characterization of a new shape memory alloy wire based Poly Phase Motor has been reported in this paper. The motor can be used either in stepping mode or ...

  14. Pileup subtraction for jet shapes

    CERN Document Server

    Soyez, Gregory; Kim, Jihun; Dutta, Souvik; Cacciari, Matteo

    2013-01-01

    Jet shapes have the potential to play a role in many LHC analyses, for example in quark-gluon discrimination or jet substructure analyses for hadronic decays of boosted heavy objects. Most shapes, however, are significantly affected by pileup. We introduce a general method to correct for pileup effects in shapes, which acts event-by-event and jet-by-jet, and accounts also for hadron masses. It involves a numerical determination, for each jet, of a given shape's susceptibility to pileup. Together with existing techniques for determining the level of pileup, this then enables an extrapolation to zero pileup. The method can be used for a wide range of jet shapes and we show its successful application in the context of quark/gluon discrimination and top-tagging.

  15. Functional and shape data analysis

    CERN Document Server

    Srivastava, Anuj

    2016-01-01

    This textbook for courses on function data analysis and shape data analysis describes how to define, compare, and mathematically represent shapes, with a focus on statistical modeling and inference. It is aimed at graduate students in analysis in statistics, engineering, applied mathematics, neuroscience, biology, bioinformatics, and other related areas. The interdisciplinary nature of the broad range of ideas covered—from introductory theory to algorithmic implementations and some statistical case studies—is meant to familiarize graduate students with an array of tools that are relevant in developing computational solutions for shape and related analyses. These tools, gleaned from geometry, algebra, statistics, and computational science, are traditionally scattered across different courses, departments, and disciplines; Functional and Shape Data Analysis offers a unified, comprehensive solution by integrating the registration problem into shape analysis, better preparing graduate students for handling fu...

  16. Shape and Deformation Analysis of the Human Ear Canal

    DEFF Research Database (Denmark)

    Darkner, Sune

    is on the extraction and analysis of the shape and deformation of the ear canal due to movements of the mandible, leaning over, and turning of the head. Methods for surface registration with focus on non-rigid registration are presented, as well as a wide range of statistical methods used for analyzing the shapes...... and deformation fields. The results show that the ear canal changes shape significantly in all subjects and that the deformation is more complicated than previously described in the literature. It is shown that the deformation at specific locations in the ear is significantly correlated to comfort issues reported...

  17. A survey of visual preprocessing and shape representation techniques

    Science.gov (United States)

    Olshausen, Bruno A.

    1988-01-01

    Many recent theories and methods proposed for visual preprocessing and shape representation are summarized. The survey brings together research from the fields of biology, psychology, computer science, electrical engineering, and most recently, neural networks. It was motivated by the need to preprocess images for a sparse distributed memory (SDM), but the techniques presented may also prove useful for applying other associative memories to visual pattern recognition. The material of this survey is divided into three sections: an overview of biological visual processing; methods of preprocessing (extracting parts of shape, texture, motion, and depth); and shape representation and recognition (form invariance, primitives and structural descriptions, and theories of attention).

  18. Shape of Te isotopes in mean-field formalism

    Indian Academy of Sciences (India)

    However, for a quantitative analysis, electromagnetic transition rates and ratios of excitation energies of nuclei should be cal- culated [35]. For this reason, the generator coordinate method (GCM) has been used to employ configuration mixing of angular momentum and particle-number projected rel- ativistic wave functions ...

  19. Managing the transcription revolution. Industry forces shape future of field.

    Science.gov (United States)

    Faulkner, Scott D

    2003-01-01

    You may be struggling with contract issues with a vendor. Or maybe you're contemplating the pros and cons of working with outsource, at-home, or overseas transcriptionists. It's a fact: if transcription processes aren't working efficiently, the entire HIM department may be adversely affected. Factor in additional concerns such as data capture for electronic health records, compliance, and patient safety, and the importance of ensuring quality and cost-efficient transcription becomes even more apparent. To help you answer some of these questions, the Journal of AHIMA is launching a four-part series dedicated to transcription issues from the HIM professional's point of view. In this issue, we begin with MTIA president Scott Faulkner's overview of the industry and where it's going next. In upcoming issues, other experts will look at controlling cost and monitoring quality, navigating new technologies, and dealing with contract-related issues.

  20. Geometric phase shaping of terahertz vortex beams.

    Science.gov (United States)

    Minasyan, Amalya; Trovato, Clément; Degert, Jérôme; Freysz, Eric; Brasselet, Etienne; Abraham, Emmanuel

    2017-01-01

    We propose a topological beam-shaping strategy of terahertz (THz) beams using geometric phase elements made of space-variant birefringent slabs. Quasi-monochromatic THz vortex beams are produced and characterized both in amplitude and phase from the reconstructed real-time two-dimensional imaging of the electric field. Nonseparable superpositions of such vortex beams are also obtained and characterized by two-dimensional polarimetric analysis. These results emphasize the versatility of the spin-orbit electromagnetic toolbox to prepare on-demand structured light endowed with polarization-controlled orbital angular momentum content in the THz domain, which should find many uses in future THz technologies.

  1. Energy from Swastika-Shaped Rotors

    Directory of Open Access Journals (Sweden)

    McCulloch M. E.

    2015-04-01

    Full Text Available It is suggested here that a swastika-shaped rotor exposed to waves will rotate in the di- rection its arms are pointing (towards the arm-tips due to a sheltering effect. A formula is derived to predict the motion obtainable from swastika rotors of different sizes given the ocean wave height and phase speed and it is suggested that the rotor could provide a new, simpler method of wave energy generation. It is also proposed that the swastika rotor could generate energy on a smaller scale from sound waves and Brownian motion, and potentially the zero point field.

  2. The science of computing shaping a discipline

    CERN Document Server

    Tedre, Matti

    2014-01-01

    The identity of computing has been fiercely debated throughout its short history. Why is it still so hard to define computing as an academic discipline? Is computing a scientific, mathematical, or engineering discipline? By describing the mathematical, engineering, and scientific traditions of computing, The Science of Computing: Shaping a Discipline presents a rich picture of computing from the viewpoints of the field's champions. The book helps readers understand the debates about computing as a discipline. It explains the context of computing's central debates and portrays a broad perspecti

  3. Shape Memory Alloys Application: Trailing Edge Shape Control

    National Research Council Canada - National Science Library

    Berton, Benoit

    2006-01-01

    .... A demonstrator of this adaptive trailing edge has been designed and manufactured. An original actuation concept has been developed based on a mixed system made of push-pull SMA (Shape Memory Alloy...

  4. A theory of shape identification

    CERN Document Server

    Cao, Frédéric; Morel, Jean-Michel; Musé, Pablo; Sur, Frédéric

    2008-01-01

    Recent years have seen dramatic progress in shape recognition algorithms applied to ever-growing image databases. They have been applied to image stitching, stereo vision, image mosaics, solid object recognition and video or web image retrieval. More fundamentally, the ability of humans and animals to detect and recognize shapes is one of the enigmas of perception. The book describes a complete method that starts from a query image and an image database and yields a list of the images in the database containing shapes present in the query image. A false alarm number is associated to each detection. Many experiments will show that familiar simple shapes or images can reliably be identified with false alarm numbers ranging from 10-5 to less than 10-300. Technically speaking, there are two main issues. The first is extracting invariant shape descriptors from digital images. The second is deciding whether two shape descriptors are identifiable as the same shape or not. A perceptual principle, the Helmholtz princi...

  5. Premeiotic microsporocyte cell shape influences shape of tetrads during microsporogenesis

    OpenAIRE

    Penet, Laurent

    2012-01-01

    Angiosperm microspores are grouped into tetrads before they mature into functional pollen grains. This tetrad stage is an important step in microsporogenesis. Tetrad shapes are diverse across angiosperms, with high levels of variation sometimes occurring within species, reflecting variation in early developmental events of nuclear and cell division (i.e., meiosis and cytokinesis). Among these developmental influences, the shape of the microsporocyte (pollen mother cell; hereafter PMC) is like...

  6. The earth's shape and gravity

    CERN Document Server

    Garland, G D; Wilson, J T

    2013-01-01

    The Earth's Shape and Gravity focuses on the progress of the use of geophysical methods in investigating the interior of the earth and its shape. The publication first offers information on gravity, geophysics, geodesy, and geology and gravity measurements. Discussions focus on gravity measurements and reductions, potential and equipotential surfaces, absolute and relative measurements, and gravity networks. The text then elaborates on the shape of the sea-level surface and reduction of gravity observations. The text takes a look at gravity anomalies and structures in the earth's crust; interp

  7. Reconfigurable assemblies of shape-changing nanorods.

    Science.gov (United States)

    Nguyen, Trung Dac; Glotzer, Sharon C

    2010-05-25

    Reconfigurable nanostructures represent an exciting new direction for materials. Applications of reversible transformations between nanostructures induced by molecular conformations under external fields can be found in a broad range of advanced technologies including smart materials, electromagnetic sensors, and drug delivery. With recent breakthroughs in synthesis and fabrication techniques, shape-changing nanoparticles are now possible. Such novel building blocks provide a conceptually new and exciting approach to self-assembly and phase transformations by providing tunable parameters fundamentally different from the usual thermodynamic parameters. Here we investigate via molecular simulation a transformation between two thermodynamically stable structures self-assembled by laterally tethered nanorods whose rod length is switched between two values. Building blocks with longer rods assemble into a square grid structure, while those with short rods form bilayer sheets with internal smectic A ordering at the same thermodynamic conditions. By shortening or lengthening the rods over a short time scale relative to the system equilibration time, we observe a transformation from the square grid structure into bilayer sheets, and vice versa. We also observe honeycomb grid and pentagonal grid structures for intermediate rod lengths. The reconfiguration between morphologically distinct nanostructures induced by dynamically switching the building block shape serves to motivate the fabrication of shape-changing nanoscale building blocks as a new approach to the self-assembly of reconfigurable materials.

  8. Aging changes in body shape

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003998.htm Aging changes in body shape To use the sharing ... and both sexes. Height loss is related to aging changes in the bones, muscles, and joints. People ...

  9. Nuclear Shape, Mechanics, and Mechanotransduction

    National Research Council Canada - National Science Library

    Dahl, Kris Noel; Ribeiro, Alexandre J.S; Lammerding, Jan

    2008-01-01

    .... Here, we discuss the effect of intra- and extracellular forces on nuclear shape and structure and how these force-induced changes could be implicated in nuclear mechanotransduction, ie, force-induced...

  10. S-shaped learning curves.

    Science.gov (United States)

    Murre, Jaap M J

    2014-04-01

    In this article, learning curves for foreign vocabulary words are investigated, distinguishing between a subject-specific learning rate and a material-specific parameter that is related to the complexity of the items, such as the number of syllables. Two experiments are described, one with Turkish words and one with Italian words. In both, S-shaped learning curves were observed, which were most obvious if the subjects were not very familiar with the materials and if they were slow learners. With prolonged learning, the S shapes disappeared. Three different mathematical functions are proposed to explain these S-shaped curves. A further analysis clarifies why S-shaped learning curves may go unnoticed in many experiments.

  11. Shape-Morphing Nanocomposite Origami

    Science.gov (United States)

    2015-01-01

    Nature provides a vast array of solid materials that repeatedly and reversibly transform in shape in response to environmental variations. This property is essential, for example, for new energy-saving technologies, efficient collection of solar radiation, and thermal management. Here we report a similar shape-morphing mechanism using differential swelling of hydrophilic polyelectrolyte multilayer inkjets deposited on an LBL carbon nanotube (CNT) composite. The out-of-plane deflection can be precisely controlled, as predicted by theoretical analysis. We also demonstrate a controlled and stimuli-responsive twisting motion on a spiral-shaped LBL nanocomposite. By mimicking the motions achieved in nature, this method offers new opportunities for the design and fabrication of functional stimuli-responsive shape-morphing nanoscale and microscale structures for a variety of applications. PMID:24689908

  12. From Curves to Trees: A Tree-like Shapes Distance Using the Elastic Shape Analysis Framework.

    Science.gov (United States)

    Mottini, A; Descombes, X; Besse, F

    2015-04-01

    Trees are a special type of graph that can be found in various disciplines. In the field of biomedical imaging, trees have been widely studied as they can be used to describe structures such as neurons, blood vessels and lung airways. It has been shown that the morphological characteristics of these structures can provide information on their function aiding the characterization of pathological states. Therefore, it is important to develop methods that analyze their shape and quantify differences between their structures. In this paper, we present a method for the comparison of tree-like shapes that takes into account both topological and geometrical information. This method, which is based on the Elastic Shape Analysis Framework, also computes the mean shape of a population of trees. As a first application, we have considered the comparison of axon morphology. The performance of our method has been evaluated on two sets of images. For the first set of images, we considered four different populations of neurons from different animals and brain sections from the NeuroMorpho.org open database. The second set was composed of a database of 3D confocal microscopy images of three populations of axonal trees (normal and two types of mutations) of the same type of neurons. We have calculated the inter and intra class distances between the populations and embedded the distance in a classification scheme. We have compared the performance of our method against three other state of the art algorithms, and results showed that the proposed method better distinguishes between the populations. Furthermore, we present the mean shape of each population. These shapes present a more complete picture of the morphological characteristics of each population, compared to the average value of certain predefined features.

  13. Electrochromic fiber-shaped supercapacitors.

    Science.gov (United States)

    Chen, Xuli; Lin, Huijuan; Deng, Jue; Zhang, Ye; Sun, Xuemei; Chen, Peining; Fang, Xin; Zhang, Zhitao; Guan, Guozhen; Peng, Huisheng

    2014-12-23

    An electrochromic fiber-shaped super-capacitor is developed by winding aligned carbon nanotube/polyaniline composite sheets on an elastic fiber. The fiber-shaped supercapacitors demonstrate rapid and reversible chromatic transitions under different working states, which can be directly observed by the naked eye. They are also stretchable and flexible, and are woven into textiles to display designed signals in addition to storing energy. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. ESR powder line shape calculations

    Energy Technology Data Exchange (ETDEWEB)

    Vitko, J. Jr.; Huddleston, R.E.

    1976-05-01

    A program has been developed for computing the ESR spectrum of a collection of randomly oriented spins subject only to an electronic Zeeman interaction and having a Lorentzian single crystal line shape. Other single crystal line shapes, including numerical solutions of the Bloch equations, can be accommodated with minor modifications. The program differs in several features from those existing elsewhere, thus enabling one to study saturation effects, over-modulation effects, both absorptive and dispersive signals, and second and higher order derivative signals.

  15. NONCONVEX REGULARIZATION FOR SHAPE PRESERVATION

    Energy Technology Data Exchange (ETDEWEB)

    CHARTRAND, RICK [Los Alamos National Laboratory

    2007-01-16

    The authors show that using a nonconvex penalty term to regularize image reconstruction can substantially improve the preservation of object shapes. The commonly-used total-variation regularization, {integral}|{del}u|, penalizes the length of the object edges. They show that {integral}|{del}u|{sup p}, 0 < p < 1, only penalizes edges of dimension at least 2-p, and thus finite-length edges not at all. We give numerical examples showing the resulting improvement in shape preservation.

  16. Interactive online brain shape visualization

    Directory of Open Access Journals (Sweden)

    Anisha Keshavan

    2017-02-01

    Full Text Available The open-source Mindboggle package improves the labeling and morphometry estimates of brain imaging data. At the 2015 Brainhack event, we developed a web-based, interactive, brain shape visualization of Mindboggle outputs. The application links a 3D brain visualization with boxplots that describe shape measures across a selected cortical label. The code is freely available at http://www.github.com/akeshavan/roygbiv and a demo is online at http://roygbiv.mindboggle.info.

  17. Detecting shapes in noise: tuning characteristics of global shape mechanisms

    Science.gov (United States)

    Schmidtmann, Gunnar; Gordon, Gael E.; Bennett, David M.; Loffler, Gunter

    2013-01-01

    The proportion of signal elements embedded in noise needed to detect a signal is a standard tool for investigating motion perception. This paradigm was applied to the shape domain to determine how local information is pooled into a global percept. Stimulus arrays consisted of oriented Gabor elements that sampled the circumference of concentric radial frequency (RF) patterns. Individual Gabors were oriented tangentially to the shape (signal) or randomly (noise). In different conditions, signal elements were located randomly within the entire array or constrained to fall along one of the concentric contours. Coherence thresholds were measured for RF patterns with various frequencies (number of corners) and amplitudes (“sharpness” of corners). Coherence thresholds (about 10% = 15 elements) were lowest for circular shapes. Manipulating shape frequency or amplitude showed a range where thresholds remain unaffected (frequency ≤ RF4; amplitude ≤ 0.05). Increasing either parameter caused thresholds to rise. Compared to circles, thresholds increased by approximately four times for RF13 and five times for amplitudes of 0.3. Confining the signals to individual contours significantly reduced the number of elements needed to reach threshold (between 4 and 6), independent of the total number of elements on the contour or contour shape. Finally, adding external noise to the orientation of the elements had a greater effect on detection thresholds than adding noise to their position. These results provide evidence for a series of highly sensitive, shape-specific analysers which sum information globally but only from within specific annuli. These global mechanisms are tuned to position and orientation of local elements from which they pool information. The overall performance for arrays of elements can be explained by the sensitivity of multiple, independent concentric shape detectors rather than a single detector integrating information widely across space (e.g. Glass

  18. Shape memory polymer foams for endovascular therapies

    Science.gov (United States)

    Wilson, Thomas S [Castro Valley, CA; Maitland, Duncan J [Pleasant Hill, CA

    2012-03-13

    A system for occluding a physical anomaly. One embodiment comprises a shape memory material body wherein the shape memory material body fits within the physical anomaly occluding the physical anomaly. The shape memory material body has a primary shape for occluding the physical anomaly and a secondary shape for being positioned in the physical anomaly.

  19. Emotional collectives: How groups shape emotions and emotions shape groups.

    Science.gov (United States)

    van Kleef, Gerben A; Fischer, Agneta H

    2016-01-01

    Group settings are epicentres of emotional activity. Yet, the role of emotions in groups is poorly understood. How do group-level phenomena shape group members' emotional experience and expression? How are emotional expressions recognised, interpreted and shared in group settings? And how do such expressions influence the emotions, cognitions and behaviours of fellow group members and outside observers? To answer these and other questions, we draw on relevant theoretical perspectives (e.g., intergroup emotions theory, social appraisal theory and emotions as social information theory) and recent empirical findings regarding the role of emotions in groups. We organise our review according to two overarching themes: how groups shape emotions and how emotions shape groups. We show how novel empirical approaches break important new ground in uncovering the role of emotions in groups. Research on emotional collectives is thriving and constitutes a key to understanding the social nature of emotions.

  20. Elucidation of ultrafast photophysics with optical pulse shaping

    Science.gov (United States)

    Grumstrup, Erik Martin

    Optical pulse shaping is an incisive tool of laser spectroscopy that allows the experimentalist extensive flexibility to manipulate the electric field of an excitation laser pulse. In this thesis, four applications of optical pulse shaping are examined. In Chapter 2, a partially non-collinear implementation of two-dimensional electronic spectroscopy is demonstrated for the first time on rubidium vapor. The use of a pulse shaper in this context is advantageous as it significantly reduces the complexity of the experimental apparatus. Unfortunately, non-ideal pulse shaping due to pixelation effects in some pulse-shaping devices leads to spurious pulse generation when the spatial masks become highly modulated. To model the effects on recovered 2D spectra, the optical Bloch model is numerically propagated with an explicit inclusion of the electric field modified by pixelation effects. Finally, steps necessary to minimize distortions are outlined. Chapter 3 describes a series of experiments designed to study the mechanism of multiple exciton generation in semiconductor quantum dots through open and closed loop coherent control schemes. The data collected with open loop control methods indicate that the initially formed exciton relaxes on an ultrafast time scale (bridge between the fields of nonlinear spectroscopy and coherent control by describing the light-matter interactions characteristic of this type of pulse shaping using the tools of time-dependent perturbation theory. This description allows experimentalists to predict and test theories of coherent control simply and with little ambiguity, furthering the usefulness of coherent control as a spectroscopic tool.

  1. Shape Control of Solar Collectors Using Shape Memory Alloy Actuators

    Science.gov (United States)

    Lobitz, D. W.; Grossman, J. W.; Allen, J. J.; Rice, T. M.; Liang, C.; Davidson, F. M.

    1996-01-01

    Solar collectors that are focused on a central receiver are designed with a mechanism for defocusing the collector or disabling it by turning it out of the path of the sun's rays. This is required to avoid damaging the receiver during periods of inoperability. In either of these two cases a fail-safe operation is very desirable where during power outages the collector passively goes to its defocused or deactivated state. This paper is principally concerned with focusing and defocusing the collector in a fail-safe manner using shape memory alloy actuators. Shape memory alloys are well suited to this application in that once calibrated the actuators can be operated in an on/off mode using a minimal amount of electric power. Also, in contrast to other smart materials that were investigated for this application, shape memory alloys are capable of providing enough stroke at the appropriate force levels to focus the collector. Design and analysis details presented, along with comparisons to test data taken from an actual prototype, demonstrate that the collector can be repeatedly focused and defocused within accuracies required by typical solar energy systems. In this paper the design, analysis and testing of a solar collector which is deformed into its desired shape by shape memory alloy actuators is presented. Computations indicate collector shapes much closer to spherical and with smaller focal lengths can be achieved by moving the actuators inward to a radius of approximately 6 inches. This would require actuators with considerably more stroke and some alternate SMA actuators are currently under consideration. Whatever SMA actuator is finally chosen for this application, repeatability and fatigue tests will be required to investigate the long term performance of the actuator.

  2. Recovery behaviour of shape memory polyurethane based laminates after thermoforming

    Science.gov (United States)

    Wu, Shuiliang; Xu, Wensen; Prasath Balamurugan, G.; Thompson, Michael R.; Nielsen, Kent E.; Brandys, Frank A.

    2017-11-01

    Shape memory polymers (SMPs) can be used to produce a new class of decorative films capable of improved formability and shape recovery in polymer laminates, which are increasingly being used for automotive, aerospace, construction and commercial applications. As a relatively new field there is little knowledge on the shape recovery behaviour of laminates with a SMP film and few methods of quantify that behaviour. The influences of different variables that affect the recovery behaviour of thermoplastic shape memory polyurethanes based laminates including ambient temperature (45 °C and 65 °C), material modulus, and adhesive strength were investigated after thermoforming, through both experimental and modelling methods. The empirical model assisted in identifying the contributions of the adhesive to transfer stresses, which dampened the recovery of the laminate with lower shear strength adhesives. Increasing ambient temperature and the film modulus increased both the final angle recovery ratios and recovery rates.

  3. Measurement of shape and deformation of insect wing

    Science.gov (United States)

    Yin, Duo; Wei, Zhen; Wang, Zeyu; Zhou, Changqiu

    2018-01-01

    To measure the shape and deformation of an insect wing, a scanning setup adopting laser triangulation and image matching was developed. Only one industry camera with two light sources was employed to scan the transparent insect wings. 3D shape and point to point full field deformation of the wings could be obtained even when the wingspan is less than 3 mm. The venation and corrugation could be significantly identified from the results. The deformation of the wing under pin loading could be seen clearly from the results as well. Calibration shows that the shape and deformation measurement accuracies are no lower than 0.01 mm. Laser triangulation and image matching were combined dexterously to adapt wings' complex shape, size, and transparency. It is suitable for insect flight research or flapping wing micro-air vehicle development.

  4. A comparison between Chinese and Caucasian head shapes.

    Science.gov (United States)

    Ball, Roger; Shu, Chang; Xi, Pengcheng; Rioux, Marc; Luximon, Yan; Molenbroek, Johan

    2010-10-01

    Univariate anthropometric data have long documented a difference in head shape proportion between Chinese and Caucasian populations. This difference has made it impossible to create eyewear, helmets and facemasks that fit both groups well. However, it has been unknown to what extend and precisely how the two populations differ from each other in form. In this study, we applied geometric morphometrics to dense surface data to quantify and characterize the shape differences using a large data set from two recent 3D anthropometric surveys, one in North America and Europe, and one in China. The comparison showed the significant variations between head shapes of the two groups and results demonstrated that Chinese heads were rounder than Caucasian counterparts, with a flatter back and forehead. The quantitative measurements and analyses of these shape differences may be applied in many fields, including anthropometrics, product design, cranial surgery and cranial therapy.

  5. Triangular and Y-shaped hadrons in QCD

    Energy Technology Data Exchange (ETDEWEB)

    D. S. Kuzmenko; Yu. A. Simonov

    2002-03-01

    Gauge invariant extended configurations are considered for 3 fundamental (quarks) or adjoint (gluons) particles. For 3 quarks it is proved that the only possible gauge-invariant configuration is the Y-shaped one, proposed long ago, while the triangular one proposed recently is ruled out. For adjoint sources both configurations are possible. Static potential is computed in all cases. For baryons the Y-shaped configuration leads to a significant depletion of field-strength density at the string-junction position, which decreases the effective potential slope at R {approx} 0.5 fm by 10-15%, as observed on the lattice. For adjoint sources the Y-shaped and {Delta}-shaped potentials are very close, leading to almost degenerate masses of 3--3g glueballs and odderon trajectories.

  6. Statistical models of shape optimisation and evaluation

    CERN Document Server

    Davies, Rhodri; Taylor, Chris

    2014-01-01

    Deformable shape models have wide application in computer vision and biomedical image analysis. This book addresses a key issue in shape modelling: establishment of a meaningful correspondence between a set of shapes. Full implementation details are provided.

  7. Investigation of shape-dependent switching of coupled nanomagnets

    Science.gov (United States)

    Imre, Alexandra; Csaba, György; Bernstein, Gary H.; Porod, Wolfgang; Metlushko, Vitali

    2003-09-01

    This paper presents a magnetic force microscopy study of antiferromagnetic ordering along chains of dipole-coupled single-domain permalloy nanomagnets with a variety of shapes. Magnetization reversal processes occur due to antiferromagnetic coupling between the closely spaced dots when an appropriate external magnetic field is applied. The goal of this study was to investigate the switching properties and correlation lengths as a function of nanomagnet geometry. We have found that certain shapes (due to their stronger stray fields) clearly show stronger interaction than others when the chain is demagnetized. In addition we have seen that the performance of the nanomagnets also depends on the method of demagnetization, and this fact must be taken into account when shape engineering is used to design coupled nanomagnet systems for a given application.

  8. The influence of shape-holding conditions on shape recovery of polyurethane-shape memory polymer foams

    Science.gov (United States)

    Tobushi, H.; Matsui, R.; Hayashi, S.; Shimada, D.

    2004-08-01

    The thermomechanical properties of polyurethane-shape memory polymer (SMP) foams and the influence of shape-holding conditions on shape recovery were investigated experimentally. The results obtained can be summarized as follows. (1) By cooling the foam down to below the glass transition temperature Tg after compressive deformation above Tg, stress decreases and the deformed shape is fixed. By heating the shape-fixed foam up to above Tg under no load, the original shape is recovered. (2) The shape deformed above Tg is maintained for six months under no load at Tg- 60 K without depending on the maximum strain, and the original shape is recovered by heating thereafter. (3) If the deformed shape is held at high temperature, the original shape is not recovered. (4) The ratio of shape irrecovery increases in proportion to the holding strain, holding temperature and holding time.

  9. Lunar Regolith Particle Shape Analysis

    Science.gov (United States)

    Kiekhaefer, Rebecca; Hardy, Sandra; Rickman, Douglas; Edmunson, Jennifer

    2013-01-01

    Future engineering of structures and equipment on the lunar surface requires significant understanding of particle characteristics of the lunar regolith. Nearly all sediment characteristics are influenced by particle shape; therefore a method of quantifying particle shape is useful both in lunar and terrestrial applications. We have created a method to quantify particle shape, specifically for lunar regolith, using image processing. Photomicrographs of thin sections of lunar core material were obtained under reflected light. Three photomicrographs were analyzed using ImageJ and MATLAB. From the image analysis measurements for area, perimeter, Feret diameter, orthogonal Feret diameter, Heywood factor, aspect ratio, sieve diameter, and sieve number were recorded. Probability distribution functions were created from the measurements of Heywood factor and aspect ratio.

  10. Event shape engineering with ALICE

    CERN Document Server

    Dobrin, A

    2013-01-01

    The strong fluctuations in the initial energy density of heavy-ion collisions allow an efficient selection of events corresponding to a specific initial geometry. For such "shape engineered events", the elliptic flow coefficient, $v_2$, of unidentified charged particles, pions and (anti-)protons in Pb-Pb collisions at $\\snn = 2.76$ TeV is measured by the ALICE collaboration. $v_2$ obtained with the event plane method at mid-rapidity, $|\\eta|<0.8$, is reported for different collision centralities as a function of transverse momentum, $\\pt$, out to $\\pt=20$ GeV/$c$. The measured $v_2$ for the shape engineered events is significantly larger or smaller than the average which demonstrates the ability to experimentally select events with the desired shape of the initial spatial asymmetry.

  11. Shape and Dimensions of Ripples

    DEFF Research Database (Denmark)

    Jacobsen, Niels Gjøl

    In this work, the flow and bed load transport over ripple profiles under the influence of oscillatory will be investigated. The investigation is made through a parametric study, where the bed shape and the ripple steepness are varied. For the sediment transport, the Shields parameter relative to ...... is to investigate how a perturbation on top of the ripple influences the flow. It will be seen that both the shape and the velocity of the crest are affecting the period averaged flow globally.......In this work, the flow and bed load transport over ripple profiles under the influence of oscillatory will be investigated. The investigation is made through a parametric study, where the bed shape and the ripple steepness are varied. For the sediment transport, the Shields parameter relative...

  12. Quantifying the shape of aging

    DEFF Research Database (Denmark)

    Wrycza, Tomasz F; Missov, Trifon I; Baudisch, Annette

    2015-01-01

    of aging rates, suggest the shape of aging as a novel and valuable alternative concept for comparative aging research. The concept of shape captures the direction and degree of change in the force of mortality over age, which—on a demographic level—reflects aging. We 1) provide a list of shape properties......In Biodemography, aging is typically measured and compared based on aging rates. We argue that this approach may be misleading, because it confounds the time aspect with the mere change aspect of aging. To disentangle these aspects, here we utilize a time-standardized framework and, instead...... suggested here aim to provide a general means to classify aging patterns independent of any particular mortality model and independent of any species-specific time-scale. Thereby they support systematic comparative aging research across different species or between populations of the same species under...

  13. Optimal shapes for best draining

    Science.gov (United States)

    Sherwood, J. D.

    2009-11-01

    The container shape that minimizes the volume of draining fluid remaining on the walls of the container after it has been emptied from its base is determined. The film of draining fluid is assumed to wet the walls of the container, and is sufficiently thin so that its curvature may be neglected. Surface tension is ignored. The initial value problem for the thickness of a film of Newtonian fluid is studied, and is shown to lead asymptotically to a similarity solution. From this, and from equivalent solutions for power-law fluids, the volume of the residual film is determined. The optimal container shape is not far from hemispherical, to minimize the surface area, but has a conical base to promote draining. The optimal shape for an axisymmetric mixing vessel, with a hole at the center of its base for draining, is also optimal when inverted in the manner of a washed wine glass inverted and left to drain.

  14. Emotional collectives : How groups shape emotions and emotions shape groups

    NARCIS (Netherlands)

    van Kleef, G.A.; Fischer, A.H.

    2016-01-01

    Group settings are epicentres of emotional activity. Yet, the role of emotions in groups is poorly understood. How do group-level phenomena shape group members’ emotional experience and expression? How are emotional expressions recognised, interpreted and shared in group settings? And how do such

  15. Explaining lengths and shapes of yeast by scaling arguments.

    Directory of Open Access Journals (Sweden)

    Daniel Riveline

    Full Text Available Lengths and shapes are approached in different ways in different fields: they serve as a read-out for classifying genes or proteins in cell biology whereas they result from scaling arguments in condensed matter physics. Here, we propose a combined approach with examples illustrated for the fission yeast Schizosaccharomyces pombe.

  16. The shape of an axisymmetric bubble in uniform motion

    Indian Academy of Sciences (India)

    the use of an analytical representation for the bubble shape, a surface singularity method to compute potential flows ... this motion, it can be neglected when studying the steady terminal state. In fact, as shown by Levich .... The axisymmetric case, which is of relevance to us, is based on the field due to an axisymmetric ring ...

  17. Kink shape solutions of the Maxwell-Lorentz system

    DEFF Research Database (Denmark)

    Sørensen, Mads Peter; Webb, G.M.; Brio, M.

    2005-01-01

    In the limit of high amplitude oscillating electromagnetic fields, a sequence of kink antikink shaped optical waves has been found in the Maxwell's equations coupled to a single Lorentz oscillator and with Kerr nonlinearity. The individual kinks and antikinks result from a traveling wave assumption...

  18. A motionless actuation system for magnetic shape memory devices

    Science.gov (United States)

    Armstrong, Andrew; Finn, Kevin; Hobza, Anthony; Lindquist, Paul; Rafla, Nader; Müllner, Peter

    2017-10-01

    Ni-Mn-Ga is a Magnetic Shape Memory (MSM) alloy that changes shape in response to a variable magnetic field. We can intentionally manipulate the shape of the material to function as an actuator, and the material can thus replace complicated small electromechanical systems. In previous work, a very simple and precise solid-state micropump was developed, but a mechanical rotation was required to translate the position of the magnetic field. This mechanical rotation defeats the purpose of the motionless solid-state device. Here we present a solid-state electromagnetic driver to linearly progress the position of the applied magnetic field and the associated shrinkage. The generated magnetic field was focused at either of two pole pieces, providing a mechanism for moving the localized shrinkage in the MSM element. We confirmed that our driver has sufficient strength to actuate the MSM element using optical microscopy. We validated the whole design by comparing results obtained with finite element analysis with the experimentally measured flux density. This drive system serves as a possible replacement to the mechanical rotation of the magnetic field by using a multi-pole electromagnet that sweeps the magnetic field across the MSM micropump element, solid-state switching the current to each pole piece in the multi-pole electromagnet.

  19. Star-Shaped Conjugated Systems

    Directory of Open Access Journals (Sweden)

    Heiner Detert

    2010-05-01

    Full Text Available The present review deals with the preparation and the properties of star-shaped conjugated compounds. Three, four or six conjugated arms are attached to cross-conjugated cores, which consist of single atoms (B, C+, N, benzene or azine rings or polycyclic ring systems, as for example triphenylene or tristriazolotriazine. Many of these shape-persistent [n]star compounds tend to π-stacking and self-organization, and exhibit interesting properties in materials science: Linear and non-linear optics, electrical conductivity, electroluminescence, formation of liquid crystalline phases, etc.

  20. Emergent properties of patch shapes affect edge permeability to animals.

    Directory of Open Access Journals (Sweden)

    Vilis O Nams

    Full Text Available Animal travel between habitat patches affects populations, communities and ecosystems. There are three levels of organization of edge properties, and each of these can affect animals. At the lowest level are the different habitats on each side of an edge, then there is the edge itself, and finally, at the highest level of organization, is the geometry or structure of the edge. This study used computer simulations to (1 find out whether effects of edge shapes on animal behavior can arise as emergent properties solely due to reactions to edges in general, without the animals reacting to the shapes of the edges, and to (2 generate predictions to allow field and experimental studies to test mechanisms of edge shape response. Individual animals were modeled traveling inside a habitat patch that had different kinds of edge shapes (convex, concave and straight. When animals responded edges of patches, this created an emergent property of responding to the shape of the edge. The response was mostly to absolute width of the shapes, and not the narrowness of them. When animals were attracted to edges, then they tended to collect in convexities and disperse from concavities, and the opposite happened when animals avoided edges. Most of the responses occurred within a distance of 40% of the perceptual range from the tip of the shapes. Predictions were produced for directionality at various locations and combinations of treatments, to be used for testing edge behavior mechanisms. These results suggest that edge shapes tend to either concentrate or disperse animals, simply because the animals are either attracted to or avoid edges, with an effect as great as 3 times the normal density. Thus edge shape could affect processes like pollination, seed predation and dispersal and predator abundance.

  1. Shape analysis of synthetic diamond

    CERN Document Server

    Mullan, C

    1997-01-01

    Two-dimensional images of synthetic industrial diamond particles were obtained using a camera, framegrabber and PC-based image analysis software. Various methods for shape quantification were applied, including two-dimensional shape factors, Fourier series expansion of radius as a function of angle, boundary fractal analysis, polygonal harmonics, and comer counting methods. The shape parameter found to be the most relevant was axis ratio, defined as the ratio of the minor axis to the major axis of the ellipse with the same second moments of area as the particle. Axis ratio was used in an analysis of the sorting of synthetic diamonds on a vibrating table. A model was derived based on the probability that a particle of a given axis ratio would travel to a certain bin. The model described the sorting of bulk material accurately but it was found not to be applicable if the shape mix of the feed material changed dramatically. This was attributed to the fact that the particle-particle interference was not taken int...

  2. How Faults Shape the Earth.

    Science.gov (United States)

    Bykerk-Kauffman, Ann

    1992-01-01

    Presents fault activity with an emphasis on earthquakes and changes in continent shapes. Identifies three types of fault movement: normal, reverse, and strike faults. Discusses the seismic gap theory, plate tectonics, and the principle of superposition. Vignettes portray fault movement, and the locations of the San Andreas fault and epicenters of…

  3. Cell shape: taking the heat.

    Science.gov (United States)

    Kunda, Patricia; Rohn, Jennifer L; Baum, Buzz

    2008-06-03

    Preservation of cell architecture under physically stressful conditions is a basic requirement for many biological processes and is critical for mechanosensory systems built to translate subtle changes in cell shape into changes in organism behaviour. A new study reveals how an extracellular protein--Spam--helps mechanosensory organs in the fruit fly to withstand the effects of the water loss that accompanies heat shock.

  4. The pear-shaped bladder.

    Science.gov (United States)

    Ambos, M A; Bosniak, M A; Lefleur, R S; Madayag, M A

    1977-01-01

    The tear-drop or pear-shaped bladder was originally described in cases of pelvic hematoma. It may also be seen, however, with a variety of other entities, including pelvic lipomatosis, inferior vena cava occlusion, lymphocysts, and enlarged pelvic lymph nodes. Pertinent radiographic findings of these conditions are reviewed.

  5. Visual field

    Science.gov (United States)

    Perimetry; Tangent screen exam; Automated perimetry exam; Goldmann visual field exam; Humphrey visual field exam ... Confrontation visual field exam. This is a quick and basic check of the visual field. The health care provider ...

  6. SHAPE CHARACTERIZATION OF CONCRETE AGGREGATE

    Directory of Open Access Journals (Sweden)

    Jing Hu

    2011-05-01

    Full Text Available As a composite material, the performance of concrete materials can be expected to depend on the properties of the interfaces between its two major components, aggregate and cement paste. The microstructure at the interfacial transition zone (ITZ is assumed to be different from the bulk material. In general, properties of conventional concrete have been found favoured by optimum packing density of the aggregate. Particle size is a common denominator in such studies. Size segregation in the ITZ among the binder particles in the fresh state, observed in simulation studies by concurrent algorithm-based SPACE system, additionally governs density as well as physical bonding capacity inside these shell-like zones around aggregate particles. These characteristics have been demonstrated qualitatively pertaining also after maturation of the concrete. Such properties of the ITZs have direct impact on composite properties. Despite experimental approaches revealed effects of aggregate grain shape on different features of material structure (among which density, and as a consequence on mechanical properties, it is still an underrated factor in laboratory studies, probably due to the general feeling that a suitable methodology for shape characterization is not available. A scientific argument hindering progress is the interconnected nature of size and shape. Presently, a practical problem preventing shape effects to be emphasized is the limitation of most computer simulation systems in concrete technology to spherical particles. New developments at Delft University of Technology will make it possible in the near future to generate jammed states, or other high-density fresh particle mixtures of non-spherical particles, which thereupon can be subjected to hydration algorithms. This paper will sketch the outlines of a methodological approach for shape assessment of loose (non-embedded aggregate grains, and demonstrate its use for two types of aggregate, allowing

  7. Relaxed MHD equilibria inside 3D shaped conducting surfaces

    Science.gov (United States)

    Hassam, A.; Tenbarge, J.; Dorland, W.; Landreman, M.; Sengupta, W.

    2017-10-01

    A 3D nonlinear dissipative MHD code is developed to allow relaxation to low-beta MHD equilibrium inside a shaped 3D conducting boundary with prescribed conserved axial magnetic flux and no external current. Formation of magnetic islands is allowed. Heat sources would be eventually introduced to allow possible non-stationary convection depending on the MHD stability properties. The initial development is done using UMHD (Guzdar et al., PF, 1993). A primary objective is to minimize numerical boundary noise. In particular, codes which specify the normal magnetic field B.n on bounding surfaces are prone to boundary noise generation. We shape the boundary to conform to the desired field shape so that B.n is zero on the boundary, employing curvilinear coordinates. Significant noise reduction has been achieved by this approach. Boundary noise is strongly suppressed if the boundary is modeled as a sharp ramp-down in resistivity, allowing relaxation to equilibrium but no penetration into the low resistivity region. Initial results have been verified w.r.t. analytic calculation in the weak shaping limit. A rotational transform is observed in helical shaping. Relaxed equilibria inside helically symmetric conducting boundaries will be presented.

  8. On artistic shaping of citizens’ political gatherings

    Directory of Open Access Journals (Sweden)

    Dimić Zoran

    2013-01-01

    Full Text Available Following the new reading of Kant’s third critique, which was proposed by Hannah Arendt in her Lectures on Kant’s Political Philosophy, in this paper, the author deals with the function of art in the establishment, organization and profiling of political communities. The focus is primarily on the field of music. The analysis begins with ancient philosophers (Pythagoras, Plato, Aristotle and continues with the problems which relate to artistic shaping of citizens’ lives in modern epoch (Rousseau, Kant, Schiller. The goal of the paper is to show that the philosophy of art and the philosophy of music, could be taken as a political philosophy, precisely because the analysis of these phenomena constantly convinces a close intertwining of politics and aesthetics, i.e. art and power, music and power. As a conclusion, we might say that a general aesthetic sense can be seen as a kind of human organ for public aesthetic gathering of citizens. Music, poetry, visual arts, etc., have become tools for the political shaping of citizens, i.e. the tools of their political life.

  9. Square shaped flat-top beam in refractive beam shapers

    Science.gov (United States)

    Laskin, Alexander; Laskin, Vadim; Ostrun, Aleksei

    2015-08-01

    Lossless transformation of round Gaussian to square shaped flat-top collimated beam is important in building highpower solid state laser systems to improve optical pumping or amplification. There are industrial micromachining applications like scribing, display repair, which performance is improved when a square shaped spot with uniform intensity is created. Proved beam shaping solutions to these techniques are refractive field mapping beam shapers having some important features: flatness of output phase front, small output divergence, high transmittance, extended depth of field, operation with TEM00 and multimode lasers. Usual approach to design refractive beam shapers implies that input and output beams have round cross-section, therefore the only way to create a square shaped output beam is using a square mask, which leads to essential losses. When an input laser beam is linearly polarized it is suggested to generate square shaped flat-top output by applying beam shaper lenses from birefringent materials or by using additional birefringent components. Due to birefringence there is introduced phase retardation in beam parts and is realized a square shaped interference pattern at the beam shaper output. Realization of this approach requires small phase retardation, therefore weak birefringence effect is enough and birefringent optical components, operating in convergent or divergent beams, can be made from refractive materials, which crystal optical axis is parallel to optical axis of entire beam shaper optical system. There will be considered design features of beam shapers creating square shaped flat-top beams. Examples of real implementations and experimental results will be presented as well.

  10. Peripheral Refraction, Peripheral Eye Length, and Retinal Shape in Myopia.

    Science.gov (United States)

    Verkicharla, Pavan K; Suheimat, Marwan; Schmid, Katrina L; Atchison, David A

    2016-09-01

    To investigate how peripheral refraction and peripheral eye length are related to retinal shape. Relative peripheral refraction (RPR) and relative peripheral eye length (RPEL) were determined in 36 young adults (M +0.75D to -5.25D) along horizontal and vertical visual field meridians out to ±35° and ±30°, respectively. Retinal shape was determined in terms of vertex radius of curvature Rv, asphericity Q, and equivalent radius of curvature REq using a partial coherence interferometry method involving peripheral eye lengths and model eye raytracing. Second-order polynomial fits were applied to RPR and RPEL as functions of visual field position. Linear regressions were determined for the fits' second order coefficients and for retinal shape estimates as functions of central spherical refraction. Linear regressions investigated relationships of RPR and RPEL with retinal shape estimates. Peripheral refraction, peripheral eye lengths, and retinal shapes were significantly affected by meridian and refraction. More positive (hyperopic) relative peripheral refraction, more negative RPELs, and steeper retinas were found along the horizontal than along the vertical meridian and in myopes than in emmetropes. RPR and RPEL, as represented by their second-order fit coefficients, correlated significantly with retinal shape represented by REq. Effects of meridian and refraction on RPR and RPEL patterns are consistent with effects on retinal shape. Patterns derived from one of these predict the others: more positive (hyperopic) RPR predicts more negative RPEL and steeper retinas, more negative RPEL predicts more positive relative peripheral refraction and steeper retinas, and steeper retinas derived from peripheral eye lengths predict more positive RPR.

  11. Pencil-shaped silicon nanowire synthesis and photovoltaic application

    Science.gov (United States)

    Jevasuwan, Wipakorn; Chen, Junyi; Subramani, Thiyagu; Pradel, Ken C.; Takei, Toshiaki; Dai, Kotaro; Shinotsuka, Kei; Hatta, Yoshihisa; Fukata, Naoki

    2017-08-01

    Pencil-shaped silicon nanowires (SiNWs) were synthesized by colloidal lithography and inductively coupled plasma reactive ion etching for photovoltaic application. Light reflectance of below 10% could be obtained by the asymmetric pencil-shaped SiNW array. The pencil-shaped SiNW structure and properties were investigated and compared with metal catalyzed electroless etching (MCEE) and nanoimprinted SiNWs. Single-junction solar cells consisting of pencil-shaped n-SiNW substrates and p-Si shell layer grown by chemical vapor deposition were fabricated. A combination of two-step H2 annealing and back surface field formation was applied to improve the solar cell properties. Good crystal quality and surface of pencil-shaped SiNWs provided an excellent solar cell junction interface. The great light trapping of the pencil-shaped SiNW solar cell could enhance the conversion efficiency by more than 0.6% compared to the solar cells using MCEE and nanoimprinted SiNWs.

  12. Calculation of the line shapes of radiators immersed in plasma

    Science.gov (United States)

    Hayrapetian, Alek Savad

    The fluctuating electric field of plasma perturbs the atomic structure of the immersed ion or atoms. The perturbed line shape is an important diagnostic tool for the temperature and density measurements of plasma. The line shape calculation is done by first deriving the line shape expression, then it is shown that the problem is equivalent to calculating the temperature Green's function of the bound electron. The total Hamiltonian of the system includes the atomic, plasma and atom-plasma parts. The temperature Green's function is calculated perturbatively by expanding in orders of atom-plasma interation. By solving a Dyson equation the dressed Green's function of the bound electrons are obtained. At this point the line shape is calculated by an analytic continuation from the complex frequency plane to real line. To derive the atomic electron Green's function the momentum integral in the self energy is approximated by a Riemann sum. With this approximation the algebraic form of the line shape is obtained for an undetermined number of terms in the Riemann sum. Numerical calculation of line shape is done by using this result.

  13. 3D Shape Modeling Using High Level Descriptors

    DEFF Research Database (Denmark)

    Andersen, Vedrana

    The goal of this Ph.D. project is to investigate and improve the methods for describing the surface of 3D objects, with focus on modeling geometric texture on surfaces. Surface modeling being a large field of research, the work done during this project concentrated around a few smaller areas...... features like thorns, bark and scales. Presented here is a simple method for easy modeling, transferring and editing that kind of texture. The method is an extension of the height-field texture, but incorporates an additional tilt of the height field. Related to modeling non-heightfield textures, a part...... of my work involved developing feature-aware resizing of models with complex surfaces consisting of underlying shape and a distinctive texture detail. The aim was to deform an object while preserving the shape and size of the features....

  14. From correlation functions to event shapes

    CERN Document Server

    Belitsky, A V; Korchemsky, G P; Sokatchev, E; Zhiboedov, A

    2014-01-01

    We present a new approach to computing event shape distributions or, more precisely, charge flow correlations in a generic conformal field theory (CFT). These infrared finite observables are familiar from collider physics studies and describe the angular distribution of global charges in outgoing radiation created from the vacuum by some source. The charge flow correlations can be expressed in terms of Wightman correlation functions in a certain limit. We explain how to compute these quantities starting from their Euclidean analogues by means of a non-trivial analytic continuation which, in the framework of CFT, can elegantly be performed in Mellin space. The relation between the charge flow correlations and Euclidean correlation functions can be reformulated directly in configuration space, bypassing the Mellin representation, as a certain Lorentzian double discontinuity of the correlation function integrated along the cuts. We illustrate the general formalism in N=4 SYM, making use of the well-known results...

  15. Suppression of I[sub c] and Fiske resonances in specially shaped Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Gijsbertsen, J.G. (Dept. of Applied Physics, Univ. of Twente, Enschede (Netherlands)); Houwman, E.P. (Dept. of Applied Physics, Univ. of Twente, Enschede (Netherlands)); Flokstra, J. (Dept. of Applied Physics, Univ. of Twente, Enschede (Netherlands)); Rogalla, H. (Dept. of Applied Physics, Univ. of Twente, Enschede (Netherlands))

    1994-02-01

    In some applications of Josephson junctions it is necessary to suppress the critical current and Fiske resonances with a relatively small magnetic field. The sidelobes of the Fraunhofer pattern can be suppressed by taking an appropriate shape for the junction. A suppression of the first sidelobe below 1% of the zero-field critical current is possible as was shown experimentally. However, Fiske resonances are still present. We investigated how an adaptation of the junction shape may suppress these resonances, still maintaining the suppression of the sidelobes of the Fraunhofer pattern. Measurements of the critical current and Fiske resonance heights as a function of the magnetic field for a junction with a special shape and an adapted specially shaped junction were performed. For both types of junctions, the sidelobes of the I[sub c](B) patterns are suppressed. No extra suppression of the I[sub F](B) patterns due to the adaptation of the shape is observed. (orig.)

  16. Suppression of I c and Fiske resonances in specially shaped Josephson junctions

    Science.gov (United States)

    Gijsbertsen, J. G.; Houwman, E. P.; Flokstra, J.; Rogalla, H.

    1994-02-01

    In some applications of Josephson junctions it is necessary to suppress the critical current and Fiske resonances with a relatively small magnetic field. The sidelobes of the Fraunhofer pattern can be suppressed by taking an appropriate shape for the junction. A suppression of the first sidelobe below 1% of the zero-field critical current is possible as was shown experimentally. However, Fiske resonances are still present. We investigated how an adaptation of the junction shape may suppress these resonances, still maintaining the suppression of the sidelobes of the Fraunhofer pattern. Measurements of the critical current and Fiske resonance heights as a function of the magnetic field for a junction with a special shape and an adapted specially shaped junction were performed. For both types of junctions, the sidelobes of the I c(B) patterns are suppressed. No extra suppression of the I F(B) patterns due to the adaptation of the shape is observed.

  17. Shape perception in human and computer vision an interdisciplinary perspective

    CERN Document Server

    Dickinson, Sven J

    2013-01-01

    This comprehensive and authoritative text/reference presents a unique, multidisciplinary perspective on Shape Perception in Human and Computer Vision. Rather than focusing purely on the state of the art, the book provides viewpoints from world-class researchers reflecting broadly on the issues that have shaped the field. Drawing upon many years of experience, each contributor discusses the trends followed and the progress made, in addition to identifying the major challenges that still lie ahead. Topics and features: examines each topic from a range of viewpoints, rather than promoting a speci

  18. Antidot shape dependence of switching mechanism in permalloy samples

    Science.gov (United States)

    Yetiş, Hakan; Denizli, Haluk

    2017-01-01

    We study antidot shape dependence of the switching magnetization for various permalloy samples with square and triangular arrays of nanometer scale antidots. The remnant magnetization, squareness ratio, and coercive fields of the samples are extracted from the hysteresis loops which are obtained by solving the Landau-Lifshitz-Gilbert (LLG) equation numerically. We find several different magnetic spin configurations which reveal the existence of superdomain wall structures. Our results are discussed in terms of the local shape anisotropy, array geometry, and symmetry properties in order to explain the formation of inhomogeneous domain structures.

  19. A New Method of Designing Circularly Symmetric Shaped Dual Reflector Antennas Using Distorted Conics

    Directory of Open Access Journals (Sweden)

    Mohammad Asif Zaman

    2014-01-01

    Full Text Available A new method of designing circularly symmetric shaped dual reflector antennas using distorted conics is presented. The surface of the shaped subreflector is expressed using a new set of equations employing differential geometry. The proposed equations require only a small number of parameters to accurately describe practical shaped subreflector surfaces. A geometrical optics (GO based method is used to synthesize the shaped main reflector surface corresponding to the shaped subreflector. Using the proposed method, a shaped Cassegrain dual reflector system is designed. The field scattered from the subreflector is calculated using uniform geometrical theory of diffraction (UTD. Finally, a numerical example is provided showing how a shaped subreflector produces more uniform illumination over the main reflector aperture compared to an unshaped subreflector.

  20. Limit Shapes in the Six Vertex Model

    Science.gov (United States)

    Sridhar, Ananth

    The purpose of this thesis is to present some new results about the six-vertex model and dimer model, andi in particular some aspects of the limit shapes that form in the thermodynamic limit and the partial differential equations that arise in their study. Chapter 1 provides a detailed introduction to limit shape phenomena and its mathematics. Chapter 2 reviews basic facts about the six-vertex model and dimer model and their properties in the thermodynamic limit. Chapter 3 investigates the role of integrability of the six vertex model in the formation of limit shapes. By integrability we mean, on one hand the discrete integrability of the six-vertex model in the sense of commutative families of transfer matrices, and on the other hand the integrability in the continuum limit in the Liouville sense of Poisson commutative families of functions (integrals of motion) on the phase space. The main result is to show that the partial differential equations describing the limit shape have an infinite number of conserved quantities. Chapter 4 explains the results of the previous chapter in a more general setting. The main result is a straightforward theorem in Hamiltonian mechanics, which gives conditions for the Poisson commutativity of two Hamiltonian functions in terms of their principal action functions. It suggests a generalization of our previous results to other integrable lattice models, for example, the generalizations of the six-vertex model related to other Lie algebras. Chapter 5 studies the six-vertex model for a special class of weights called the stochastic six-vertex model. for which the six vertex model is closely related to interacting particle models. The main result of this chapter is the derivation for the partial differential equations for the height function of the stochastic 6-vertex model on the cylinder. Chapter 6 studies models at the intersection of discrete geometry and statistical mechanics. The main result is the asymptotic expansion of the

  1. Shape analysis with subspace symmetries

    KAUST Repository

    Berner, Alexander

    2011-04-01

    We address the problem of partial symmetry detection, i.e., the identification of building blocks a complex shape is composed of. Previous techniques identify parts that relate to each other by simple rigid mappings, similarity transforms, or, more recently, intrinsic isometries. Our approach generalizes the notion of partial symmetries to more general deformations. We introduce subspace symmetries whereby we characterize similarity by requiring the set of symmetric parts to form a low dimensional shape space. We present an algorithm to discover subspace symmetries based on detecting linearly correlated correspondences among graphs of invariant features. We evaluate our technique on various data sets. We show that for models with pronounced surface features, subspace symmetries can be found fully automatically. For complicated cases, a small amount of user input is used to resolve ambiguities. Our technique computes dense correspondences that can subsequently be used in various applications, such as model repair and denoising. © 2010 The Author(s).

  2. Shape completion for automatic inspection

    Science.gov (United States)

    Preston, Adrian; Forte, Peter

    1996-08-01

    In this paper we outline an approach to a fast low-cost system for the inspection and evaluation of surface-mount assemblies and solder joints, giving particular focus to the need for robustness in such a system. We describe the software modules involved in extracting features, and shape analysis for the purpose of inspection. A common problem during the early stages of image processing is the loss of information about the edges of shape because of noise, weak contrast, or occlusion, which often increases the amount of incorrect interpretations of a given image when presented to higher levels of processing. An algorithm is described which significantly reduces the effect of such problems before information is passed to later stages of the vision process. The algorithm, which uses information about contour to correct dropouts is generic, employing no application specific information and is therefore applicable to vision systems in general.

  3. Specification of ROP flux shape

    Energy Technology Data Exchange (ETDEWEB)

    Min, Byung Joo [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Gray, A. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada)

    1997-06-01

    The CANDU 9 480/SEU core uses 0.9% SEU (Slightly Enriched Uranium) fuel. The use f SEU fuel enables the reactor to increase the radial power form factor from 0.865, which is typical in current natural uranium CANDU reactors, to 0.97 in the nominal CANDU 9 480/SEU core. The difference is a 12% increase in reactor power. An additional 5% increase can be achieved due to a reduced refuelling ripple. The channel power limits were also increased by 3% for a total reactor power increase of 20%. This report describes the calculation of neutron flux distributions in the CANDU 9 480/SEU core under conditions specified by the C and I engineers. The RFSP code was used to calculate of neutron flux shapes for ROP analysis. Detailed flux values at numerous potential detector sites were calculated for each flux shape. (author). 6 tabs., 70 figs., 4 refs.

  4. Shaping Robust System through Evolution

    CERN Document Server

    Kaneko, Kunihiko

    2008-01-01

    Biological functions are generated as a result of developmental dynamics that form phenotypes governed by genotypes. The dynamical system for development is shaped through genetic evolution following natural selection based on the fitness of the phenotype. Here we study how this dynamical system is robust to noise during development and to genetic change by mutation. We adopt a simplified transcription regulation network model to govern gene expression, which gives a fitness function. Through simulations of the network that undergoes mutation and selection, we show that a certain level of noise in gene expression is required for the network to acquire both types of robustness. The results reveal how the noise that cells encounter during development shapes any network's robustness, not only to noise but also to mutations. We also establish a relationship between developmental and mutational robustness through phenotypic variances caused by genetic variation and epigenetic noise. A universal relationship betwee...

  5. Isogeometric Analysis and Shape Optimisation

    DEFF Research Database (Denmark)

    Gravesen, Jens; Evgrafov, Anton; Gersborg, Allan Roulund

    One of the attractive features of isogeometric analysis is the exact representation of the geometry. The geometry is furthermore given by a relative low number of control points and this makes isogeometric analysis an ideal basis for shape optimisation. I will describe some of the results we have...... obtained and also some of the problems we have encountered. One of these problems is that the geometry of the shape is given by the boundary alone. And, it is the parametrisation of the boundary which is changed by the optimisation procedure. But isogeometric analysis requires a parametrisation...... of the whole domain. So in every optimisation cycle we need to extend a parametrisation of the boundary of a domain to the whole domain. It has to be fast in order not to slow the optimisation down but it also has to be robust and give a parametrisation of high quality. These are conflicting requirements so we...

  6. Shape optimization of corrugated airfoils

    Science.gov (United States)

    Jain, Sambhav; Bhatt, Varun Dhananjay; Mittal, Sanjay

    2015-12-01

    The effect of corrugations on the aerodynamic performance of a Mueller C4 airfoil, placed at a 5° angle of attack and Re=10{,}000, is investigated. A stabilized finite element method is employed to solve the incompressible flow equations in two dimensions. A novel parameterization scheme is proposed that enables representation of corrugations on the surface of the airfoil, and their spontaneous appearance in the shape optimization loop, if indeed they improve aerodynamic performance. Computations are carried out for different location and number of corrugations, while holding their height fixed. The first corrugation causes an increase in lift and drag. Each of the later corrugations leads to a reduction in drag. Shape optimization of the Mueller C4 airfoil is carried out using various objective functions and optimization strategies, based on controlling airfoil thickness and camber. One of the optimal shapes leads to 50 % increase in lift coefficient and 23 % increase in aerodynamic efficiency compared to the Mueller C4 airfoil.

  7. Angular-shaped naphthalene tetracarboxylic diimides for n-channel organic transistor semiconductors.

    Science.gov (United States)

    Chen, Shan-ci; Zhang, Qikai; Zheng, Qingdong; Tang, Changquan; Lu, Can-Zhong

    2012-01-30

    A series of compounds based on the angular-shaped naphthalene tetracarboxylic diimide core have been synthesized, characterized and used as active layers of organic field-effect transistors (OFETs). The fabricated OFET devices exhibit n-type semiconducting characteristics, demonstrating the first examples of semiconductors based on angular-shaped naphthalene tetracarboxylic diimides.

  8. The Shaping of the Scandinavian Socio-technical IS Research Tradition

    DEFF Research Database (Denmark)

    Bjørn-Andersen, Niels; Clemmensen, Torkil

    2017-01-01

    This paper relates stories instrumental in shaping the career of an individual and which have also contributed to shaping of the IS field in general and the ‘Scandinavian Socio-Technical (S/T) Information Systems Research Tradition’ in particular. The method in this paper is an autoethnography (L...

  9. The Shaping of the Scandinavian Socio-technical IS Research Tradition

    DEFF Research Database (Denmark)

    Bjørn-Andersen, Niels; Clemmensen, Torkil

    2017-01-01

    This paper relates stories instrumental in shaping the career of an individual and which have also contributed to shaping of the IS field in general and the ‘Scandinavian Socio-Technical (S/T) Information Systems Research Tradition’ in particular. The method in this paper is an autoethnography...

  10. Hydrothermal growth of wheatear-shaped ZnO microstructures and ...

    Indian Academy of Sciences (India)

    shaped ZnO microstructures at alow temperature (85 ∘ C) without the assistance of any template agent. X-ray diffraction and field emission scanning electron microscopy were used to characterize the structure and morphology of the samples.

  11. Idea Generation in Highly Institutionalized Fields

    DEFF Research Database (Denmark)

    Agoguè, Marine; Boxenbaum, Eva

    The early phase of innovation processes in highly institutionalized fields relies on the capabilities of actors to generate new ideas that break with the field frame. Informed by a dominant logic, a field frame shapes collective cognition and can thus prevent the generation of new ideas and block...

  12. First Principles Modelling of Shape Memory Alloys Molecular Dynamics Simulations

    CERN Document Server

    Kastner, Oliver

    2012-01-01

    Materials sciences relate the macroscopic properties of materials to their microscopic structure and postulate the need for holistic multiscale research. The investigation of shape memory alloys is a prime example in this regard. This particular class of materials exhibits strong coupling of temperature, strain and stress, determined by solid state phase transformations of their metallic lattices. The present book presents a collection of simulation studies of this behaviour. Employing conceptually simple but comprehensive models, the fundamental material properties of shape memory alloys are qualitatively explained from first principles. Using contemporary methods of molecular dynamics simulation experiments, it is shown how microscale dynamics may produce characteristic macroscopic material properties. The work is rooted in the materials sciences of shape memory alloys and  covers  thermodynamical, micro-mechanical  and crystallographical aspects. It addresses scientists in these research fields and thei...

  13. Actin filaments growing against a barrier with fluctuating shape.

    Science.gov (United States)

    Sadhu, Raj Kumar; Chatterjee, Sakuntala

    2016-06-01

    We study force generation by a set of parallel actin filaments growing against a nonrigid obstacle, in the presence of an external load. The filaments polymerize by either moving the whole obstacle, with a large energy cost, or by causing local distortion in its shape which costs much less energy. The nonrigid obstacle also has local thermal fluctuations due to which its shape can change with time and we describe this using fluctuations in the height profile of a one-dimensional interface with Kardar-Parisi-Zhang dynamics. We find the shape fluctuations of the barrier strongly affect the force generation mechanism. The qualitative nature of the force-velocity curve is crucially determined by the relative time scale of filament and barrier dynamics. The height profile of the barrier also shows interesting variation with the external load. Our analytical calculations within mean-field theory show reasonable agreement with our simulation results.

  14. Bayesian data assimilation in shape registration

    KAUST Repository

    Cotter, C J

    2013-03-28

    In this paper we apply a Bayesian framework to the problem of geodesic curve matching. Given a template curve, the geodesic equations provide a mapping from initial conditions for the conjugate momentum onto topologically equivalent shapes. Here, we aim to recover the well-defined posterior distribution on the initial momentum which gives rise to observed points on the target curve; this is achieved by explicitly including a reparameterization in the formulation. Appropriate priors are chosen for the functions which together determine this field and the positions of the observation points, the initial momentum p0 and the reparameterization vector field ν, informed by regularity results about the forward model. Having done this, we illustrate how maximum likelihood estimators can be used to find regions of high posterior density, but also how we can apply recently developed Markov chain Monte Carlo methods on function spaces to characterize the whole of the posterior density. These illustrative examples also include scenarios where the posterior distribution is multimodal and irregular, leading us to the conclusion that knowledge of a state of global maximal posterior density does not always give us the whole picture, and full posterior sampling can give better quantification of likely states and the overall uncertainty inherent in the problem. © 2013 IOP Publishing Ltd.

  15. Suppression of the critical current and Fiske resonances in specially shaped Josephson junctions

    OpenAIRE

    Gijsbertsen, J.G.; Gijsbertsen, Hans; Houwman, Evert Pieter; Flokstra, Jakob; Rogalla, Horst

    1994-01-01

    In some applications of Josephson junctions it is necessary to suppress the critical current and Fiske resonances with a relatively small magnetic field. The sidelobes of the Fraunhofer pattern can be suppressed by taking an appropriate shape for the junction. A suppression of the first sidelobe below 1% of the zero-field critical current is possible as was shown experimentally. However, Fiske resonances are still present. We investigated how an adaptation of the junction shape may suppress t...

  16. Cartography of irregularly shaped satellites

    Science.gov (United States)

    Batson, R. M.; Edwards, Kathleen

    1987-01-01

    Irregularly shaped satellites, such as Phobos and Amalthea, do not lend themselves to mapping by conventional methods because mathematical projections of their surfaces fail to convey an accurate visual impression of the landforms, and because large and irregular scale changes make their features difficult to measure on maps. A digital mapping technique has therefore been developed by which maps are compiled from digital topographic and spacecraft image files. The digital file is geometrically transformed as desired for human viewing, either on video screens or on hard copy. Digital files of this kind consist of digital images superimposed on another digital file representing the three-dimensional form of a body.

  17. Phase Field

    Science.gov (United States)

    Koyama, Toshiyuki

    The term phase field has recently become known across many fields of materials science. The meaning of phase field is the spatial and temporal order parameter field defined in a continuum-diffused interface model. By using the phase field order parameters, many types of complex microstructure changes observed in materials science are described effectively. This methodology has been referred to as the phase field method, phase field simulation, phase field modeling, phase field approach, etc. In this chapter, the basic concept and theoretical background for the phase field approach is explained in Sects. 21.1 and 21.2. The overview of recent applications of the phase field method is demonstrated in Sects. 21.3 to 21.6.

  18. Eye gaze tracking based on the shape of pupil image

    Science.gov (United States)

    Wang, Rui; Qiu, Jian; Luo, Kaiqing; Peng, Li; Han, Peng

    2018-01-01

    Eye tracker is an important instrument for research in psychology, widely used in attention, visual perception, reading and other fields of research. Because of its potential function in human-computer interaction, the eye gaze tracking has already been a topic of research in many fields over the last decades. Nowadays, with the development of technology, non-intrusive methods are more and more welcomed. In this paper, we will present a method based on the shape of pupil image to estimate the gaze point of human eyes without any other intrusive devices such as a hat, a pair of glasses and so on. After using the ellipse fitting algorithm to deal with the pupil image we get, we can determine the direction of the fixation by the shape of the pupil.The innovative aspect of this method is to utilize the new idea of the shape of the pupil so that we can avoid much complicated algorithm. The performance proposed is very helpful for the study of eye gaze tracking, which just needs one camera without infrared light to know the changes in the shape of the pupil to determine the direction of the eye gazing, no additional condition is required.

  19. Extracting and shaping the light of OLED devices

    Science.gov (United States)

    Riedel, Daniel; Dlugosch, Julian; Wehlus, Thomas; Brabec, Christoph

    2015-09-01

    Before the market entry of organic light emitting diodes (OLEDs) into the field of general illumination can occur, limitations in lifetime, luminous efficacy and cost must be overcome. Additional requirements for OLEDs used for general illumination may be imposed by workplace glare reduction requirements, which demand limited luminance for high viewing angles. These requirements contrast with the typical lambertian emission characteristics of OLEDs, which result in the same luminance levels for all emission angles. As a consequence, without additional measures glare reduction could limit the maximum possible luminance of lambertian OLEDs to relatively low levels. However, high luminance levels are still desirable in order to obtain high light output. We are presenting solutions to overcome this dilemma. Therefore this work is focused on light-shaping structures for OLEDs with an internal light extraction layer. Simulations of beam-shaping structures and shapes are presented, followed by experimental measurements to verify the simulations of the most promising structures. An investigation of the loss channels has been carried out and the overall optical system efficiency was evaluated for all structures. The most promising light shaping structures achieve system efficiencies up to 80%. Finally, a general illumination application scenario has been simulated. The number of OLEDs needed to illuminate an office room has been deduced from this scenario. By using light-shaping structures for OLEDs, the number of OLEDs needed to reach the mandatory illuminance level for a workplace environment can be reduced to one third compared to lambertian OLEDs.

  20. Dark Energy Survey Year 1 Results: Weak Lensing Shape Catalogues

    Energy Technology Data Exchange (ETDEWEB)

    Zuntz, J.; et al.

    2017-08-04

    We present two galaxy shape catalogues from the Dark Energy Survey Year 1 data set, covering 1500 square degrees with a median redshift of $0.59$. The catalogues cover two main fields: Stripe 82, and an area overlapping the South Pole Telescope survey region. We describe our data analysis process and in particular our shape measurement using two independent shear measurement pipelines, METACALIBRATION and IM3SHAPE. The METACALIBRATION catalogue uses a Gaussian model with an innovative internal calibration scheme, and was applied to $riz$-bands, yielding 34.8M objects. The IM3SHAPE catalogue uses a maximum-likelihood bulge/disc model calibrated using simulations, and was applied to $r$-band data, yielding 21.9M objects. Both catalogues pass a suite of null tests that demonstrate their fitness for use in weak lensing science. We estimate the 1$\\sigma$ uncertainties in multiplicative shear calibration to be $0.013$ and $0.025$ for the METACALIBRATION and IM3SHAPE catalogues, respectively.

  1. A TQFT of Tuarev-Viro type on shaped triangulations

    Energy Technology Data Exchange (ETDEWEB)

    Kashaev, Rinat [Geneva Univ. (Switzerland); Luo, Feng [Rutgers Univ., Piscataway, NJ (United States). Dept. of Mathematics; Vartanov, Grigory [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2012-10-15

    A shaped triangulation is a finite triangulation of an oriented pseudo three manifold where each tetrahedron carries dihedral angles of an ideal hyberbolic tetrahedron. To each shaped triangulation, we associate a quantum partition function in the form of an absolutely convergent state integral which is invariant under shaped 3-2 Pachner moves and invariant with respect to shape gauge transformations generated by total dihedral angles around internal edges through the Neumann-Zagier Poisson bracket. Similarly to Turaev-Viro theory, the state variables live on edges of the triangulation but take their values on the whole real axis. The tetrahedral weight functions are composed of three hyperbolic gamma functions in a way that they enjoy a manifest tetrahedral symmetry. We conjecture that for shaped triangulations of closed 3-manifolds, our partition function is twice the absolute value squared of the partition function of Techmueller TQFT defined by Andersen and Kashaev. This is similar to the known relationship between the Turaev-Viro and the Witten-Reshetikhin-Turaev invariants of three manifolds. We also discuss interpretations of our construction in terms of three-dimensional supersymmetric field theories related to triangulated three-dimensional manifolds.

  2. Joint shape segmentation with linear programming

    KAUST Repository

    Huang, Qixing

    2011-01-01

    We present an approach to segmenting shapes in a heterogenous shape database. Our approach segments the shapes jointly, utilizing features from multiple shapes to improve the segmentation of each. The approach is entirely unsupervised and is based on an integer quadratic programming formulation of the joint segmentation problem. The program optimizes over possible segmentations of individual shapes as well as over possible correspondences between segments from multiple shapes. The integer quadratic program is solved via a linear programming relaxation, using a block coordinate descent procedure that makes the optimization feasible for large databases. We evaluate the presented approach on the Princeton segmentation benchmark and show that joint shape segmentation significantly outperforms single-shape segmentation techniques. © 2011 ACM.

  3. Quantitative shape measurements of distal volcanic ash

    National Research Council Canada - National Science Library

    Colleen M. Riley; William I. Rose; Gregg J. S. Bluth

    2003-01-01

    ...‐shaped particles affect transport processes and radiative transfer measurements. In this study, a methodology was developed to characterize particle shapes, sizes, and terminal velocities for three ash samples of different compositions...

  4. Edge energies and shapes of nanoprecipitates.

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, John C.

    2006-01-01

    In this report we present a model to explain the size-dependent shapes of lead nano-precipitates in aluminum. Size-dependent shape transitions, frequently observed at nanolength scales, are commonly attributed to edge energy effects. This report resolves an ambiguity in the definition and calculation of edge energies and presents an atomistic calculation of edge energies for free clusters. We also present a theory for size-dependent shapes of Pb nanoprecipitates in Al, introducing the concept of ''magic-shapes'' defined as precipitate shapes having near zero elastic strains when inserted into similarly shaped voids in the Al matrix. An algorithm for constructing a complete set of magic-shapes is presented. The experimental observations are explained by elastic strain energies and interfacial energies; edge energies play a negligible role. We replicate the experimental observations by selecting precipitates having magic-shapes and interfacial energies less than a cutoff value.

  5. Axisymmetric Drop Shape Analysis (ADSA): An Outline.

    Science.gov (United States)

    Saad, Sameh M I; Neumann, A Wilhelm

    2016-12-01

    Drop shape techniques for the measurement of interfacial tension are powerful, versatile and flexible. The shape of the drop/bubble depends on the balance between surface tension and external forces, e.g. gravity. This balance is reflected mathematically in the Laplace equation of capillarity. Axisymmetric Drop Shape Analysis (ADSA) is a commonly used drop shape technique. A streamlined version of the development of ADSA over the past several decades is presented to illustrate its validity and range of utility. Several configurations of interest will be considered and presented systematically. Shape and surface tension will be linked to a shape parameter based on proper concepts of differential geometry. The resulting shape parameter will be shown to allow determination of the range of applicability of such a drop shape method. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Shape Memory Effect Actuators from Chlorides Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Shape Change Technologies is developing a radical new technique for the fabrication of Shape Memory alloys, such as TiNi and its ternary alloys of Hf, Zr, and Cu....

  7. Pulse shaping using a spatial light modulator

    CSIR Research Space (South Africa)

    Botha, N

    2009-07-01

    Full Text Available Femtosecond pulse shaping can be done by different kinds of pulse shapers, such as liquid crystal spatial light modulators (LC SLM), acousto optic modulators (AOM) and deformable and movable mirrors. A few applications where pulse shaping...

  8. Enhanced backscattering of optical vortex fields.

    Science.gov (United States)

    Schwartz, Chaim; Dogariu, Aristide

    2005-06-15

    The effect of an incident field with a phase screw dislocation (a so-called optical vortex) on the shape of the enhanced backscattering cone was studied theoretically and demonstrated experimentally. We show that the correlation function of the incident field acts as a filter that modifies the shape of the enhanced backscattering cone. The peak value is reduced, and its width is increased as the topological charge of the phase dislocation increases.

  9. Justifications shape ethical blind spots.

    Science.gov (United States)

    Pittarello, Andrea; Leib, Margarita; Gordon-Hecker, Tom; Shalvi, Shaul

    2015-06-01

    To some extent, unethical behavior results from people's limited attention to ethical considerations, which results in an ethical blind spot. Here, we focus on the role of ambiguity in shaping people's ethical blind spots, which in turn lead to their ethical failures. We suggest that in ambiguous settings, individuals' attention shifts toward tempting information, which determines the magnitude of their lies. Employing a novel ambiguous-dice paradigm, we asked participants to report the outcome of the die roll appearing closest to the location of a previously presented fixation cross on a computer screen; this outcome would determine their pay. We varied the value of the die second closest to the fixation cross to be either higher (i.e., tempting) or lower (i.e., not tempting) than the die closest to the fixation cross. Results of two experiments revealed that in ambiguous settings, people's incorrect responses were self-serving. Tracking participants' eye movements demonstrated that people's ethical blind spots are shaped by increased attention toward tempting information. © The Author(s) 2015.

  10. Shape Modelling Using Maximum Autocorrelation Factors

    DEFF Research Database (Denmark)

    Larsen, Rasmus

    2001-01-01

    of Active Shape Models by Timothy Cootes and Christopher Taylor by building new information into the model. This new information consists of two types of prior knowledge. First, in many situation we will be given an ordering of the shapes of the training set. This situation occurs when the shapes....... Both these types of knowledge may be used to defined Shape Maximum Autocorrelation Factors. The resulting point distribution models are compared to ordinary principal components analysis using leave-one-out validation....

  11. Tunable microwave properties of rhomboid shaped nanomagnet pairs

    Science.gov (United States)

    Tian, Chang; Adeyeye, Adekunle Olusola

    2017-12-01

    The magnetization dynamics of a multilayer rhomboid shaped nanomagnet pair is investigated using micro-focused Brillouin light scattering spectroscopy. The multilayer structure consists of two permalloy layers separated by a nonmagnetic Cr spacer layer. As compared with a single-layer rhomboid shaped nanomagnet pair with two distinct magnetic ground states (ferromagnetic and antiferromagnetic), the multilayer nanomagnetic pair displays multiple magnetic ground states upon different initialization fields due to the presence of both in-plane and out-of-plane dipolar coupling. The dynamic response as a function of initialization field has been systematically investigated. Distinct microwave absorption behavior and resonance frequency shift are observed when the nanomagnet pair is switched into different magnetic ground states. Micromagnetic simulations validate our experimental observations.

  12. Optimal design of UAV's pod shape

    Science.gov (United States)

    Wei, Qun; Jia, Hong-guang

    2011-08-01

    In the modern war, UAV(unmanned aircraft system) plays a more and more important role in the army. UAVs always carry electrical-optical reconnaissance systems. These systems are used to accomplish the missions of observing and reconnaissance the battlefield. For traditional UAV, the shape of the pod on UAV is sphericity. In addition, the pod of UAV not only has the job of observing and reconnaissance the battlefield, but its shape also has impact on the UAV's drag when it flies in the air. In this paper, two different kinds of pod models are set up, one is the traditional sphericity model, the other is a new model. Unstructured grid is used on the flow field. Using CFD(computational fluid dynamic) method, the results of the drags of the different kinds of pod are got. The drag's relationship between the pod and the UAV is obtained by comparing the results of simulations. After analyzing the results we can get: when UAV flies at low speed(0.3Ma{0.7Ma), the drag's difference between the two kinds of pod is little, the pod's drag takes a small part of the UAV's whole drag which is only about 14%. At transonic speed(0.8Ma{1.2Ma), the drag's difference between these two kinds of pod is getting bigger and bigger along with the speed goes higher. The traditional pod's drag is 1/3 of the UAV's whole drag value, but for the new pod, it is only 1/5. At supersonic speed(1.3Ma{2.0Ma), the traditional pod's drag goes up rapidly, but the new kind of pod's drag goes up slowly. This makes the difference between the two kinds of UAVs' total drag comes greater. For example, at 2Ma, the total drag of new UAV is only 2/3 of the traditional UAV. These results show: when the UAV flies at low speed, these two kinds of pod have little difference in drag. But if it flies at supersonic speed, the pod has great impact on the UAV's total drag, so the designer of UAV's pod should pay more attention on the out shape.

  13. Orbital maneuvers around irregular shaped bodies

    Science.gov (United States)

    Venditti, Flaviane; Rocco, E. M.; Almeida Prado, A. B.

    2013-05-01

    Abstract (2,250 Maximum Characters): In the solar system there are many small bodies called asteroids. The large majority of these bodies are located in the asteroid belt, between the orbits of the planets Mars and Jupiter. The Near- Earth Objects, or NEOs, are objects with perihelion below 1.3AU, which include comets and asteroids. The NEOs are considered to have orbits passing close to the Earth’s orbit and, in the case of asteroids, are called Near-Earth Asteroids (NEAs). Among the NEAs there are bodies considered potentially hazardous asteroids (PHAs), whose minimum orbit intersection distance with Earth is 0.05AU and that have absolute magnitude (H) of 22, which would mean an asteroid of at least 110-240 meters, depending on its albedo. One of the major characteristic of the asteroids is the irregular shape, causing the dynamics of orbits around these bodies to be different from a spherical shaped one. The fact that an object is not spherical generates a perturbation on the gravitational field. The disturbing force can be determined considering the shape of the specific body. A satellite orbiting this body would suffer the effects of this perturbation, but knowing the disturbing force, it’s possible to correct and control the orbit according to the desired mission. The polyhedron method is a traditional way to model an asteroid by dividing the object into smaller parts. The data used on this work are composed by a combination of triangular faces. The total disturbing force is a sum of the force on each piece of the model. Therefore, after the simulations are obtained, it’s possible to apply the desired corrections of the perturbation using continuous low thrust in closed loop, making it possible to perform maneuvers near these bodies. One of the important applications of the study shown above is in the ASTER mission, that is under study by INPE and several other Brazilian academic institutions, which goal is to send a spacecraft to an asteroid and then

  14. Shape memory alloys–characterization techniques

    Indian Academy of Sciences (India)

    Shape memory alloys are the generic class of alloys that show both thermal and mechanical memory. The basic physics involved in the shape memory effect is the reversible thermoelastic martensitic transformation. In general, there exists two phases in shape memory alloys, viz., a hightemperature phase or austenitic ...

  15. Interfacial Modulus Mapping during Structural Transformation in Shape Memory Alloys

    Science.gov (United States)

    Wan, Jianfeng; Cui, Shushan; Zhang, Jihua; Rong, Yonghua

    2017-10-01

    Through the modified phase-field model the local soft mode mechanism of nucleation during martensitic transformation was confirmed in shape memory alloys. It was discovered that the modulus loss (8 pct) depended on the martensitic nucleation exceeding the loss (1 pct) during the martensitic growth. The elastic modulus and the stress across the martensite/parent interface differed from those across the martensitic twin boundary. The modulus losses in systems with three variants, two variants, and one variant were compared.

  16. Shape recovery and irrecoverable strain control in polyurethane shape-memory polymer

    Directory of Open Access Journals (Sweden)

    Hisaaki Tobushi et al

    2008-01-01

    Full Text Available In shape-memory polymers, large strain can be fixed at a low temperature and thereafter recovered at a high temperature. If the shape-memory polymer is held at a high temperature for a long time, the irrecoverable strain can attain a new intermediate shape between the shape under the maximum stress and the primary shape. Irrecoverable strain control can be applied to the fabrication of a shape-memory polymer element with a complex shape in a simple method. In the present study, the influence of the strain-holding conditions on the shape recovery and the irrecoverable strain control in polyurethane shape-memory polymer is investigated by tension test of a film and three-point bending test of a sheet. The higher the shape-holding temperature and the longer the shape-holding time, the higher the irrecoverable strain rate. The equation that expresses the characteristics of the irrecoverable strain control is formulated.

  17. Studies of impact of plasma shaping on edge localized modes with a nonlinear code BOUT + +

    Science.gov (United States)

    Li, G. Q.; Xu, X. Q.; Snyder, P. B.; Turnbull, A. D.; Xia, T. Y.

    2014-10-01

    The plasma shaping has important effects on the edge localized modes (ELMs). In this work, with the 3-field BOUT + + code, we study the impact of the plasma shaping on the ELMs. Three kinds of typical plasma shapes are studied: circular (cbm), elongated (dbm) and shaped with X-point (meudas). Our calculations show that the shaped plasma and the X-point geometry have stabilizing effect on the ELMs. For linear ideal MHD calculation we benchmark BOUT + + results with ELITE and GATO codes. Then we study the role of non-ideal effects such as resistivity on the ELMs for the X-point geometry. Also the nonlinear calculations are carried out to study the impact of plasma shape on the ELM size. Work supported by China National Magnetic Confinement Fusion Science Program under Grant Nos. 2014GB106001 and 2013GB111000. Also performed for USDOE by LLNL under DE-AC52-07NA27344. LLNL-ABS-656997.

  18. Mathematics of shape description a morphological approach to image processing and computer graphics

    CERN Document Server

    Ghosh, Pijush K

    2009-01-01

    Image processing problems are often not well defined because real images are contaminated with noise and other uncertain factors. In Mathematics of Shape Description, the authors take a mathematical approach to address these problems using the morphological and set-theoretic approach to image processing and computer graphics by presenting a simple shape model using two basic shape operators called Minkowski addition and decomposition. This book is ideal for professional researchers and engineers in Information Processing, Image Measurement, Shape Description, Shape Representation and Computer Graphics. Post-graduate and advanced undergraduate students in pure and applied mathematics, computer sciences, robotics and engineering will also benefit from this book.  Key FeaturesExplains the fundamental and advanced relationships between algebraic system and shape description through the set-theoretic approachPromotes interaction of image processing geochronology and mathematics in the field of algebraic geometryP...

  19. Optical Manipulation with Plasmonic Beam Shaping Antenna Structures

    Directory of Open Access Journals (Sweden)

    Young Chul Jun

    2012-01-01

    Full Text Available Near-field optical trapping of objects using plasmonic antenna structures has recently attracted great attention. However, metal nanostructures also provide a compact platform for general wavefront engineering of intermediate and far-field beams. Here, we analyze optical forces generated by plasmonic beam shaping antenna structures and show that they can be used for general optical manipulation such as guiding of a dielectric particle along a linear or curved trajectory. This removes the need for bulky diffractive optical components and facilitates the integration of optical force manipulation into a highly functional, compact system.

  20. A Geometric Framework for Rectangular Shape Detection.

    Science.gov (United States)

    Li, Qi

    2014-07-25

    Rectangular shape detection has a wide range of applications, such as license plate detection, vehicle detection and building detection. In this paper, we propose a geometric framework for rectangular shape detection based on the channelscale space of RGB images. The framework consists of algorithms developed to address three issues of a candidate shape (i.e., a connected component of edge points), including: i) outliers, ii) open shape, and iii) fragmentation. Furthermore, we propose an interestness measure for rectangular shapes by integrating imbalanced points (one type of interest points). Our experimental study shows the promise of the proposed framework.

  1. A case of impaired shape integration

    DEFF Research Database (Denmark)

    Gerlach, Christian; Marstrand, Lisbet; Habekost, Thomas

    2005-01-01

    integration is not a prerequisite for normal object naming. However, on more demanding tests of visual object recognition, HE's performance deteriorated, with her performance being inversely related to the demand placed on integration of local elements into more elaborate shape descriptions. From this we...... conclude that shape integration is important for normal object recognition....... the notion that grouping may be divided into two general steps: (i) element clustering and (ii) shape configuration, with the latter operation being impaired in HE. As opposed to previous cases with shape integration deficits, HE was able to name objects accurately. Initially, this might suggest that shape...

  2. Social reward shapes attentional biases.

    Science.gov (United States)

    Anderson, Brian A

    2016-01-01

    Paying attention to stimuli that predict a reward outcome is important for an organism to survive and thrive. When visual stimuli are associated with tangible, extrinsic rewards such as money or food, these stimuli acquire high attentional priority and come to automatically capture attention. In humans and other primates, however, many behaviors are not motivated directly by such extrinsic rewards, but rather by the social feedback that results from performing those behaviors. In the present study, I examine whether positive social feedback can similarly influence attentional bias. The results show that stimuli previously associated with a high probability of positive social feedback elicit value-driven attentional capture, much like stimuli associated with extrinsic rewards. Unlike with extrinsic rewards, however, such stimuli also influence task-specific motivation. My findings offer a potential mechanism by which social reward shapes the information that we prioritize when perceiving the world around us.

  3. Children Literature: Shaping Gender Identities

    Directory of Open Access Journals (Sweden)

    IQRA JABEEN

    2014-02-01

    Full Text Available The aim of this paper is to analyze stereotype construction of gender roles in the text of children's stories which inculcate in the children’s crude minds socially developed gender differences. For this purpose, the study followed Dell Hymes’ speaking model. This model has sixteen components that can be applied to different types of Discourse (speech interaction: message form; message content; setting; scene; Speaker/sender; address or; the hearer/receiver/audience; addressee; purposes (outcomes; purposes (goals; key; channels; forms of speech; norms of interaction; norms of interpretation; and genres. Selected children's stories were analyzed to identify their role as primary thought developing sources in the mind of young learners thus shaping their gender identities. This study would be beneficial in drawing the attention of authors, editors and writers of children's literature to redefine gender roles in order to minimize gender differences.

  4. The perfect shape spiral stories

    CERN Document Server

    Hammer, Øyvind

    2016-01-01

    This book uses the spiral shape as a key to a multitude of strange and seemingly disparate stories about art, nature, science, mathematics, and the human endeavour. In a way, the book is itself organized as a spiral, with almost disconnected chapters circling around and closing in on the common theme. A particular strength of the book is its extremely cross-disciplinary nature - everything is fun, and everything is connected! At the same time, the author puts great emphasis on mathematical and scientific correctness, in contrast, perhaps, with some earlier books on spirals. Subjects include the mathematical properties of spirals, sea shells, sun flowers, Greek architecture, air ships, the history of mathematics, spiral galaxies, the anatomy of the human hand, the art of prehistoric Europe, Alfred Hitchcock, and spider webs, to name a few.

  5. Shape memory thermal conduction switch

    Science.gov (United States)

    Vaidyanathan, Rajan (Inventor); Krishnan, Vinu (Inventor); Notardonato, William U. (Inventor)

    2010-01-01

    A thermal conduction switch includes a thermally-conductive first member having a first thermal contacting structure for securing the first member as a stationary member to a thermally regulated body or a body requiring thermal regulation. A movable thermally-conductive second member has a second thermal contacting surface. A thermally conductive coupler is interposed between the first member and the second member for thermally coupling the first member to the second member. At least one control spring is coupled between the first member and the second member. The control spring includes a NiTiFe comprising shape memory (SM) material that provides a phase change temperature <273 K, a transformation range <40 K, and a hysteresis of <10 K. A bias spring is between the first member and the second member. At the phase change the switch provides a distance change (displacement) between first and second member by at least 1 mm, such as 2 to 4 mm.

  6. Shape Memory Composite Hybrid Hinge

    Science.gov (United States)

    Fang, Houfei; Im, Eastwood; Lin, John; Scarborough, Stephen

    2012-01-01

    There are two conventional types of hinges for in-space deployment applications. The first type is mechanically deploying hinges. A typical mechanically deploying hinge is usually composed of several tens of components. It is complicated, heavy, and bulky. More components imply higher deployment failure probability. Due to the existence of relatively moving components among a mechanically deploying hinge, it unavoidably has microdynamic problems. The second type of conventional hinge relies on strain energy for deployment. A tape-spring hinge is a typical strain energy hinge. A fundamental problem of a strain energy hinge is that its deployment dynamic is uncontrollable. Usually, its deployment is associated with a large impact, which is unacceptable for many space applications. Some damping technologies have been experimented with to reduce the impact, but they increased the risks of an unsuccessful deployment. Coalescing strain energy components with shape memory composite (SMC) components to form a hybrid hinge is the solution. SMCs are well suited for deployable structures. A SMC is created from a high-performance fiber and a shape memory polymer resin. When the resin is heated to above its glass transition temperature, the composite becomes flexible and can be folded or packed. Once cooled to below the glass transition temperature, the composite remains in the packed state. When the structure is ready to be deployed, the SMC component is reheated to above the glass transition temperature, and it returns to its as-fabricated shape. A hybrid hinge is composed of two strain energy flanges (also called tape-springs) and one SMC tube. Two folding lines are placed on the SMC tube to avoid excessive strain on the SMC during folding. Two adapters are used to connect the hybrid hinge to its adjacent structural components. While the SMC tube is heated to above its glass transition temperature, a hybrid hinge can be folded and stays at folded status after the temperature

  7. HOW PARTICIPATION SHAPES LOCAL DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    Muhadjir Darwin

    2016-12-01

    Full Text Available This article elaborates citizens’ participation in shaping local development in the Indonesian context. The main question is how to make local development more participatory as a guarantee that citizens’ rights are fully realized. In that respects, social accountability is a key that should be improved from supply and demand sides simultaneously. From the supply side, there is a need to reform local governance, in order to improve the quality of local regulations, local planning, local budgeting, and local public service provision. While from the demand side, there is a need to empower local citizens so that they are engaged in five forms or local development efforts: local regulation formulation, local development planning, local budgeting, community driven development, and public service provision.

  8. Research about the shape control of the space membrane mirror

    Science.gov (United States)

    Qi, Y. C.; Jin, G.; Sun, X. W.

    The space membrane mirror whose substrate is polyimide film is a developing new technology Relative to normal reflector it has prominent thermal endurance radiation resistance and mechanical property Its area density is only 17 gram pre square meter and solves the restrict between the aperture and weight of conventional reflector Integrating with its nicer pliability it also can eliminate the limit of the carrying capacity and space of launch vehicle to the aperture and weight of the optical system and satisfy the require of lightweight and high resolution Membrane mirror can get its shape by applying lateral load on flat polyimide film whose verge is fasten and this lateral load can be electrostatic force getting from the mutual effect between high voltage electrostatic field and metallic membrane coated on the surface of polyimide film In this paper the possibility of controlling the reflector surface by high voltage electrostatic field is studied Through distinguishing different fashion and intensity of the loaded electrostatic field the distortion of the mirror is calculated by FEA and the coupling of electrostatic and force field method and the shape precision is gotten by programming interface program based on Zernike polynomial and wave surface fit The conclusion that favorable polyimide membrane mirror can be received by adjusting the loading fashion and intensity of the electrostatic field is gotten

  9. Effective calculation of laser stripping via a broad shape resonance

    Directory of Open Access Journals (Sweden)

    T. Gorlov

    2010-07-01

    Full Text Available This paper presents the theory and method of calculation of laser assisted charge exchange injection via a broad shape resonance of the hydrogen atom with a new level of accuracy. The method is optimized for fast calculations, needed for practical estimations of laser-stripping efficiency for charge exchange injection. The novelty is that we take into account the resonance width and continuous spectrum of the hydrogen atom in our model. As a result we show that the broad shape resonance can fully compensate the Doppler broadening of the laser frequency in realistic beams without applying laser chirp and increasing laser power. The resulting scheme can be realized by applying a magnetic field of optimal strength to the high-energy beam irradiated by laser field. Another novelty is that we use the temporal Schrödinger equation as the basis of our model in contrast with the existing method of semiempirical cross sections, which is widely considered in atomic physics. The strict quantum mechanical approach gives the temporal evolution of the wave function and the ionization probability of the hydrogen atom as a function of laser and static electric fields. Moreover, it reveals quantum effects at the strong laser field which cannot be described with the cross section treatment. It is shown that the effects play a significant role in the optimization of the magnetic field for the laser-stripping scheme.

  10. Scattering of Gaussian beam by arbitrarily shaped inhomogeneous particles

    Science.gov (United States)

    Cui, Z. W.; Han, Y. P.; Wang, J. J.; Zhao, W. J.

    2012-04-01

    A hybrid finite element-boundary integral method is applied to characterize the scattering of an arbitrarily incident-focused Gaussian beam by arbitrarily shaped inhomogeneous particles. Specifically, the Davis-Barton fifth-order approximation in combination with rotation Euler angles is used to represent the arbitrarily incident Gaussian beams. The finite element method is employed to formulate the fields in the interior region of the inhomogeneous particle, while the boundary integral equation is applied to represent the fields in the exterior region. The interior and exterior fields are coupled by means of the field continuity conditions. To reduce the computational burden, the frontal method and the multilevel fast multipole algorithm are adopted to solve the resultant matrix equation. Numerical results for differential scattering cross sections of several selected inhomogeneous particles are presented and can be served as further study on this subject.

  11. Updated Methods for Seed Shape Analysis

    Directory of Open Access Journals (Sweden)

    Emilio Cervantes

    2016-01-01

    Full Text Available Morphological variation in seed characters includes differences in seed size and shape. Seed shape is an important trait in plant identification and classification. In addition it has agronomic importance because it reflects genetic, physiological, and ecological components and affects yield, quality, and market price. The use of digital technologies, together with development of quantification and modeling methods, allows a better description of seed shape. Image processing systems are used in the automatic determination of seed size and shape, becoming a basic tool in the study of diversity. Seed shape is determined by a variety of indexes (circularity, roundness, and J index. The comparison of the seed images to a geometrical figure (circle, cardioid, ellipse, ellipsoid, etc. provides a precise quantification of shape. The methods of shape quantification based on these models are useful for an accurate description allowing to compare between genotypes or along developmental phases as well as to establish the level of variation in different sets of seeds.

  12. Influence of strain-holding conditions on shape recovery and secondary-shape forming in polyurethane-shape memory polymer

    Science.gov (United States)

    Tobushi, H.; Hayashi, S.; Hoshio, K.; Miwa, N.

    2006-08-01

    It was found in previous work on the thermomechanical properties of the polyurethane-shape memory polymer foam that the shape fixity and shape recovery become imperfect and that secondary-shape forming appears, depending on the strain-holding conditions. The main factors of the strain-holding conditions which affect the secondary-shape forming are the holding temperature, holding time and holding strain. In the present study, the influence of the strain-holding conditions on the shape recovery and secondary-shape forming was investigated for the polyurethane-shape memory polymer film. It was found that the secondary-shape forming appears markedly if the holding temperature is higher than the glass transition temperature and does not appear if the holding temperature is lower than the glass transition temperature. The rate of secondary-shape forming increases with an increase in the holding time if the holding temperature is higher than the glass transition temperature. The irrecoverable strain increases in proportion to the holding strain.

  13. Shape optimisation and performance analysis of flapping wings

    KAUST Repository

    Ghommem, Mehdi

    2012-09-04

    In this paper, shape optimisation of flapping wings in forward flight is considered. This analysis is performed by combining a local gradient-based optimizer with the unsteady vortex lattice method (UVLM). Although the UVLM applies only to incompressible, inviscid flows where the separation lines are known a priori, Persson et al. [1] showed through a detailed comparison between UVLM and higher-fidelity computational fluid dynamics methods for flapping flight that the UVLM schemes produce accurate results for attached flow cases and even remain trend-relevant in the presence of flow separation. As such, they recommended the use of an aerodynamic model based on UVLM to perform preliminary design studies of flapping wing vehicles Unlike standard computational fluid dynamics schemes, this method requires meshing of the wing surface only and not of the whole flow domain [2]. From the design or optimisation perspective taken in our work, it is fairly common (and sometimes entirely necessary, as a result of the excessive computational cost of the highest fidelity tools such as Navier-Stokes solvers) to rely upon such a moderate level of modelling fidelity to traverse the design space in an economical manner. The objective of the work, described in this paper, is to identify a set of optimised shapes that maximise the propulsive efficiency, defined as the ratio of the propulsive power over the aerodynamic power, under lift, thrust, and area constraints. The shape of the wings is modelled using B-splines, a technology used in the computer-aided design (CAD) field for decades. This basis can be used to smoothly discretize wing shapes with few degrees of freedom, referred to as control points. The locations of the control points constitute the design variables. The results suggest that changing the shape yields significant improvement in the performance of the flapping wings. The optimisation pushes the design to "bird-like" shapes with substantial increase in the time

  14. Directed Field Ionization

    Science.gov (United States)

    Gregoric, Vincent C.; Kang, Xinyue; Liu, Zhimin Cheryl; Rowley, Zoe A.; Carroll, Thomas J.; Noel, Michael W.

    2017-04-01

    Selective field ionization is an important experimental technique used to study the state distribution of Rydberg atoms. This is achieved by applying a steadily increasing electric field, which successively ionizes more tightly bound states. An atom prepared in an energy eigenstate encounters many avoided Stark level crossings on the way to ionization. As it traverses these avoided crossings, its amplitude is split among multiple different states, spreading out the time resolved electron ionization signal. By perturbing the electric field ramp, we can change how the atoms traverse the avoided crossings, and thus alter the shape of the ionization signal. We have used a genetic algorithm to evolve these perturbations in real time in order to arrive at a target ionization signal shape. This process is robust to large fluctuations in experimental conditions. This work was supported by the National Science Foundation under Grants No. 1607335 and No. 1607377 and used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant Number OCI-1053575.

  15. Towards high efficiency heliostat fields

    Science.gov (United States)

    Arbes, Florian; Wöhrbach, Markus; Gebreiter, Daniel; Weinrebe, Gerhard

    2017-06-01

    CSP power plants have great potential to substantially contribute to world energy supply. To set this free, cost reductions are required for future projects. Heliostat field layout optimization offers a great opportunity to improve field efficiency. Field efficiency primarily depends on the positions of the heliostats around the tower, commonly known as the heliostat field layout. Heliostat shape also influences efficiency. Improvements to optical efficiency results in electricity cost reduction without adding any extra technical complexity. Due to computational challenges heliostat fields are often arranged in patterns. The mathematical models of the radial staggered or spiral patterns are based on two parameters and thus lead to uniform patterns. Optical efficiencies of a heliostat field do not change uniformly with the distance to the tower, they even differ in the northern and southern field. A fixed pattern is not optimal in many parts of the heliostat field, especially when used as large scaled heliostat field. In this paper, two methods are described which allow to modify field density suitable to inconsistent field efficiencies. A new software for large scale heliostat field evaluation is presented, it allows for fast optimizations of several parameters for pattern modification routines. It was used to design a heliostat field with 23,000 heliostats, which is currently planned for a site in South Africa.

  16. Rapid shape detection signals in area V4.

    Science.gov (United States)

    Weiner, Katherine F; Ghose, Geoffrey M

    2014-01-01

    Vision in foveate animals is an active process that requires rapid and constant decision-making. For example, when a new object appears in the visual field, we can quickly decide to inspect it by directing our eyes to the object's location. We studied the contribution of primate area V4 to these types of rapid foveation decisions. Animals performed a reaction time task that required them to report when any shape appeared within a peripherally-located noisy stimulus by making a saccade to the stimulus location. We found that about half of the randomly sampled V4 neurons not only rapidly and precisely represented the appearance of this shape, but they were also predictive of the animal's saccades. A neuron's ability to predict the animal's saccades was not related to the specificity with which the cell represented a single type of shape but rather to its ability to signal whether any shape was present. This relationship between sensory sensitivity and behavioral predictiveness was not due to global effects such as alertness, as it was equally likely to be observed for cells with increases and decreases in firing rate. Careful analysis of the timescales of reliability in these neurons implies that they reflect both feedforward and feedback shape detecting processes. In approximately 7% of our recorded sample, individual neurons were able to predict both the delay and precision of the animal's shape detection performance. This suggests that a subset of V4 neurons may have been directly and causally contributing to task performance and that area V4 likely plays a critical role in guiding rapid, form-based foveation decisions.

  17. Efficient magnetic fields for supporting toroidal plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Landreman, Matt, E-mail: mattland@umd.edu [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Boozer, Allen H. [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)

    2016-03-15

    The magnetic field that supports tokamak and stellarator plasmas must be produced by coils well separated from the plasma. However, the larger the separation, the more difficult it is to produce a given magnetic field in the plasma region, so plasma configurations should be chosen that can be supported as efficiently as possible by distant coils. The efficiency of an externally generated magnetic field is a measure of the field's shaping component magnitude at the plasma compared to the magnitude near the coils; the efficiency of a plasma equilibrium can be measured using the efficiency of the required external shaping field. Counterintuitively, plasma shapes with low curvature and spectral width may have low efficiency, whereas plasma shapes with sharp edges may have high efficiency. Two precise measures of magnetic field efficiency, which correctly identify such differences in difficulty, will be examined. These measures, which can be expressed as matrices, relate the externally produced normal magnetic field on the plasma surface to the either the normal field or current on a distant control surface. A singular value decomposition (SVD) of either matrix yields an efficiency ordered basis for the magnetic field distributions. Calculations are carried out for both tokamak and stellarator cases. For axisymmetric surfaces with circular cross-section, the SVD is calculated analytically, and the range of poloidal and toroidal mode numbers that can be controlled to a given desired level is determined. If formulated properly, these efficiency measures are independent of the coordinates used to parameterize the surfaces.

  18. Principles of shape from specular reflection

    KAUST Repository

    Balzer, Jonathan

    2010-12-01

    The reconstruction of (partially) specular object by means of deflectometric methods is a challenging task. It has a long and fairly branched history within the metrology and machine vision communities. We are not aware of any scientific publication surveying the state of the art in a unifying manner and thus stimulating further research. This contribution is intended to close this gap, bringing together prominent ideas from both fields. In avoidance of unnecessary technicality, we lay out the basic theory, including all known forward models of the reflection process. The corresponding inverse problem is ill-posed, so that special emphasis is put on the question of regularization. We embed some novel results on the uniqueness problem and the effectiveness of regularization approaches. Also an overview of numerical methods related to Shape from Specular Reflection is given. For the sake of completeness, we share some thoughts on the construction of an actual measurement system and discuss a practical example. © 2010 Elsevier Ltd. All rights reserved.

  19. Beam Shape and Halo Monitor Study

    CERN Document Server

    Lallement, J B; Hori, M; CERN. Geneva. AB Department

    2006-01-01

    The Beam Shape and Halo Monitor, designed by Masaki Hori, is the main diagnostic tool for the 3 MeV test stand scheduled in 2008. This detector will be able to measure the transverse halo generated in the RFQ and the Chopper-line and to detect and measure the longitudinal halo composed of the incompletely chopped bunches. Its principle of functioning is the following: H- ions hit a carbon foil and generate secondary electrons with the same spatial distribution than the incoming beam and a current depending on an emission coefficient given by the carbon foil. These electrons are accelerated towards a phosphor screen by an electric field applied between accelerating grids. Once the electrons reach the phosphor screen, they generate light which is transmitted to a CCD camera via optic fibers [1]. It is expected to give a time resolution of 1-2ns and a spatial resolution of 1mm. The first test of the BSHM done with a Laser has shown a spatial resolution bigger than 1cm and the time resolution bigger than 2ns[2]. ...

  20. Shape memory alloys for micromembrane actuation

    Science.gov (United States)

    Surbled, Patrick; Le Pioufle, Bruno; Yang, E. H.; Fujita, Hiroyuki

    1999-09-01

    More and more technologies and new materials have been combined with silicon process technologies to enhance the performances of microsystems and extend the application fields. Among these technologies, the Shape Memory Alloys (SMA's) as thin films have been developed recently. They have been shown to induce high displacement and large force/mass ratio under low voltage. They can produce work output higher than can be provided with other kinds of actuators. However, such SMA actuators are not easy to make because specific annealing treatments or mechanical bias springs are needed to realize cyclic device operation. Moreover, adhesion problems of SMA thin films may occur during the annealing treatment. We have developed a simple fabrication process allowing a reliable operation principle of a micromembrane. The cyclic actuation is ensured by membrane thickness residual stresses that avoids the assembling steps. These membranes whose surface varies from 200 X 200 micrometer2 up to 2 X 2 mm2 have been successfully tested. As developed, they are very adapted to integration process of microelectronics and can be applied to many applications such as optical, fluidic devices, and especially for biomedical applications as SMA's are biocompatible.

  1. Biomedical Applications of Shape Memory Alloys

    Directory of Open Access Journals (Sweden)

    Lorenza Petrini

    2011-01-01

    behaviors, due to the peculiar crystallographic structure of the alloys, assure the recovery of the original shape even after large deformations and the maintenance of a constant applied force in correspondence of significant displacements. These properties, joined with good corrosion and bending resistance, biological and magnetic resonance compatibility, explain the large diffusion, in the last 20 years, of SMA in the production of biomedical devices, in particular for mini-invasive techniques. In this paper a detailed review of the main applications of NiTi alloys in dental, orthopedics, vascular, neurological, and surgical fields is presented. In particular for each device the main characteristics and the advantages of using SMA are discussed. Moreover, the paper underlines the opportunities and the room for new ideas able to enlarge the range of SMA applications. However, it is fundamental to remember that the complexity of the material and application requires a strict collaboration between clinicians, engineers, physicists and chemists for defining accurately the problem, finding the best solution in terms of device design and accordingly optimizing the NiTi alloy properties.

  2. Direct-write fabrication of 4D active shape-changing behavior based on a shape memory polymer and its nanocomposite (Conference Presentation)

    Science.gov (United States)

    Wei, Hongqiu; Zhang, Qiwei; Yao, Yongtao; Liu, Liwu; Liu, Yanju; Leng, Jinsong

    2017-04-01

    Shape memory polymers (SMPs), a typical class of smart materials, have been witnessed significant advances in the past decades. Based on the unique performance to recover the initial shape after going through a shape deformation, the applications of SMPs have aroused growing interests. However, most of the researches are hindered by traditional processing technologies which limit the design space of SMPs-based structures. Three-dimension (3D) printing as an emerging technology endows design freedom to manufacture materials with complex structures. In present article, we show that by employing direct-write printing method; one can realize the printing of SMPs to achieve 4D active shape-changing structures. We first fabricated a kind of 3D printable polylactide (PLA)-based SMPs and characterized the overall properties of such materials. Results demonstrated the prepared PLA-based SMPs presenting excellent shape memory effect. In what follows, the rheological properties of such PLA-based SMP ink during printing process were discussed in detail. Finally, we designed and printed several 3D configurations for investigation. By combining 3D printing with shape memory behavior, these printed structures achieve 4D active shape-changing performance under heat stimuli. This research presents a high flexible method to realize the fabrication of SMP-based 4D active shape-changing structures, which opens the way for further developments and improvements of high-tech fields like 4D printing, soft robotics, micro-systems and biomedical devices.

  3. Shaping Consciousness in Kindergarten. Conformity to School Norms through the Formation of a Child's Story

    Science.gov (United States)

    Poimenidou, Maria; Papadopoulou, Maria

    2013-01-01

    Communication is a multidimensional process. No matter what the field of the interaction is, there is always a crucial point in terms of the negotiation of social roles. This becomes more apparent in the field of education where institutional norms influence not only the children's behaviour, but at the same time the shaping of their…

  4. Supernova Explosions Stay In Shape

    Science.gov (United States)

    2009-12-01

    At a very early age, children learn how to classify objects according to their shape. Now, new research suggests studying the shape of the aftermath of supernovas may allow astronomers to do the same. A new study of images from NASA's Chandra X-ray Observatory on supernova remnants - the debris from exploded stars - shows that the symmetry of the remnants, or lack thereof, reveals how the star exploded. This is an important discovery because it shows that the remnants retain information about how the star exploded even though hundreds or thousands of years have passed. "It's almost like the supernova remnants have a 'memory' of the original explosion," said Laura Lopez of the University of California at Santa Cruz, who led the study. "This is the first time anyone has systematically compared the shape of these remnants in X-rays in this way." Astronomers sort supernovas into several categories, or "types", based on properties observed days after the explosion and which reflect very different physical mechanisms that cause stars to explode. But, since observed remnants of supernovas are leftover from explosions that occurred long ago, other methods are needed to accurately classify the original supernovas. Lopez and colleagues focused on the relatively young supernova remnants that exhibited strong X-ray emission from silicon ejected by the explosion so as to rule out the effects of interstellar matter surrounding the explosion. Their analysis showed that the X-ray images of the ejecta can be used to identify the way the star exploded. The team studied 17 supernova remnants both in the Milky Way galaxy and a neighboring galaxy, the Large Magellanic Cloud. For each of these remnants there is independent information about the type of supernova involved, based not on the shape of the remnant but, for example, on the elements observed in it. The researchers found that one type of supernova explosion - the so-called Type Ia - left behind relatively symmetric, circular

  5. Event Shape Analysis in ALICE

    CERN Document Server

    Ortiz Velasquez, Antonio

    2009-01-01

    The jets are the final state manifestation of the hard parton scattering. Since at LHC energies the production of hard processes in proton-proton collisions will be copious and varied, it is important to develop methods to identify them through the study of their final states. In the present work we describe a method based on the use of some shape variables to discriminate events according their topologies. A very attractive feature of this analysis is the possibility of using the tracking information of the TPC+ITS in order to identify specific events like jets. Through the correlation between the quantities: thrust and recoil, calculated in minimum bias simulations of proton-proton collisions at 10 TeV, we show the sensitivity of the method to select specific topologies and high multiplicity. The presented results were obtained both at level generator and after reconstruction. It remains that with any kind of jet reconstruction algorithm one will confronted in general with overlapping jets. The present meth...

  6. Doughnut-shaped soap bubbles.

    Science.gov (United States)

    Préve, Deison; Saa, Alberto

    2015-10-01

    Soap bubbles are thin liquid films enclosing a fixed volume of air. Since the surface tension is typically assumed to be the only factor responsible for conforming the soap bubble shape, the realized bubble surfaces are always minimal area ones. Here, we consider the problem of finding the axisymmetric minimal area surface enclosing a fixed volume V and with a fixed equatorial perimeter L. It is well known that the sphere is the solution for V=L(3)/6π(2), and this is indeed the case of a free soap bubble, for instance. Surprisingly, we show that for Vbubble is known to be ultimately unstable and, hence, it will eventually lose its axisymmetry by breaking apart in smaller bubbles. Indisputably, however, the topological transition from spherical to toroidal surfaces is mandatory here for obtaining the global solution for this axisymmetric isoperimetric problem. Our result suggests that deformed bubbles with V<αL(3)/6π(2) cannot be stable and should not exist in foams, for instance.

  7. Shaping non-diffracting beams with a digital micromirror device

    Science.gov (United States)

    Ren, Yu-Xuan; Fang, Zhao-Xiang; Lu, Rong-De

    2016-02-01

    The micromechanical digital micromirror device (DMD) performs as a spatial light modulator to shape the light wavefront. Different from the liquid crystal devices, which use the birefringence to modulate the light wave, the DMD regulates the wavefront through an amplitude modulation with the digitally controlled mirrors switched on and off. The advantages of such device are the fast speed, polarization insensitivity, and the broadband modulation ability. The fast switching ability for the DMD not only enables the shaping of static light mode, but also could dynamically compensate for the wavefront distortion due to scattering medium. We have employed such device to create the higher order modes, including the Laguerre-Gaussian, Hermite-Gaussian, as well as Mathieu modes. There exists another kind of beam with shape-preservation against propagation, and self-healing against obstacles. Representative modes are the Bessel modes, Airy modes, and the Pearcey modes. Since the DMD modulates the light intensity, a series of algorithms are developed to calculate proper amplitude hologram for shaping the light. The quasi-continuous gray scale images could imitate the continuous amplitude hologram, while the binary amplitude modulation is another means to create the modulation pattern for a steady light field. We demonstrate the generation of the non-diffracting beams with the binary amplitude modulation via the DMD, and successfully created the non-diffracting Bessel beam, Airy beam, and the Pearcey beam. We have characterized the non-diffracting modes through propagation measurements as well as the self-healing measurements.

  8. Non-Axisymmetric Shaping of Tokamaks Preserving Quasi-Axisymmetry

    Energy Technology Data Exchange (ETDEWEB)

    Long-Poe Ku and Allen H. Boozer

    2009-06-05

    If quasi-axisymmetry is preserved, non-axisymmetric shaping can be used to design tokamaks that do not require current drive, are resilient to disruptions, and have robust plasma stability without feedback. Suggestions for addressing the critical issues of tokamaks can only be validated when presented with sufficient specificity that validating experiments can be designed. The purpose of this paper is provide that specificity for non-axisymmetric shaping. To our knowledge, no other suggestions for the solution of a number of tokamak issues, such as disruptions, have reached this level of specificity. Sequences of three-field-period quasi-axisymmetric plasmas are studied. These sequences address the questions: (1) What can be achieved at various levels of non-axisymmetric shaping? (2) What simplifications to the coils can be achieved by going to a larger aspect ratio? (3) What range of shaping can be achieved in a single experimental facility? The sequences of plasmas found in this study provide a set of interesting and potentially important configurations.

  9. Droplet coalescence at microchannel intersection chambers with different shapes.

    Science.gov (United States)

    Liu, Zhaomiao; Wang, Xiang; Cao, Rentuo; Pang, Yan

    2016-06-29

    The influence of microchannel intersection chamber shape on the droplet coalescence process is investigated in this study. Three kinds of chamber shapes (half-round, triangle and camber) are designed to realize head-on droplet coalescence. The coalescence processes are visualized using a high-speed camera system and the internal flow patterns are resolved using a micro-PIV system. Experimental analyses on the coalescence position and coalescence time of droplets and the critical conditions are discussed. Both direct coalescence and late coalescence can be observed in the camber junction while only the late coalescence is present for the half-round and the triangle junction. The critical capillary number Ca* varies for different working systems or intersection shapes. Ca* in the camber junction is larger than that in the other two junctions for each working system and it decreases with the increase of the viscosity ratio for each intersection shape. Moreover, the characteristics of the velocity fields for different coalescence cases are analyzed for an in-depth understanding of the process.

  10. Droplets coalescence at microchannel intersection chambers with different shapes

    Science.gov (United States)

    Liu, Zhaomiao; Wang, Xiang; Cao, Rentuo; Pang, Yan

    2016-11-01

    The influence of microchannel intersection chamber shape on droplets coalescence process is investigated in this study. Three kinds of chamber shapes (half-round, triangle and camber) are designed to realize head-on droplets coalescence. The coalescence processes are visualized with high-speed camera system and the internal flow patterns are resolved with micro-PIV system. Experimental analyses on droplets coalescence position, coalescence time and the critical conditions are discussed. Both direct coalescence and late coalescence can be observed in the camber junction while only the late coalescence is present for the half-round and the triangle junction. The critical capillary number Ca* varies for different working systems or intersection shapes. Ca* in the camber junction is larger than that in the other two junctions for each working system and it decreases with the increase of the viscosity ratios for each intersection shape. Moreover, the characteristics of the velocity fields for different coalescence cases are analyzed for in-depth understanding of the process. The authors do appreciate the financial support of No.11572013 of National Nature Scicence Funding of China.

  11. Shape Memory Polyurethanes Based on Zwitterionic Hard Segments

    Directory of Open Access Journals (Sweden)

    Shuqin Fu

    2017-09-01

    Full Text Available This work aimed at elucidating the influence of zwitterionic hard segments on the structures and properties of shape memory polyurethanes (SMPUs. A series of zwitterionic SMPUs was successfully prepared with N-methyldiethanolamine (MDEA, 1,3-propanesultone (1,3-PS, 1,6-hexamethylene diisocyanate (HDI and polyethylene glycol (PEG6000. The influence of MDEA-PS-based zwitterionic hard segment on structure, morphology, thermal property, shape memory property and cytocompatibility were systematically investigated. The results demonstrated that the PEG-based zwitterionic SMPUs (PEG-ZSMPUs formed phase separation structure consisting of crystalline soft phase and amorphous hard phase. The MDEA-PS zwitterionic segments showed a tendency to form ionic clusters in hard segments, which served as reinforced net points. Shape memory analysis showed that zwitterionic PEG-ZSMPUs containing a high content of zwitterionic segments had thermal-induced shape memory effects. Finally, cytotoxic assays demonstrated that MDEA-PS zwitterionic segment improved the biocompatibility of PEG-ZSMPUs. The zwitterionic PEG-ZSMPUs could thus have a promising application in smart biomedical fields.

  12. Shape Determination for Deformed Electromagnetic Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Akcelik, Volkan; Ko, Kwok; Lee, Lie-Quan; Li, Zhenghai; Ng, Cho-Kuen; Xiao, Liling; /SLAC

    2007-12-10

    The measured physical parameters of a superconducting cavity differ from those of the designed ideal cavity. This is due to shape deviations caused by both loose machine tolerances during fabrication and by the tuning process for the accelerating mode. We present a shape determination algorithm to solve for the unknown deviations from the ideal cavity using experimentally measured cavity data. The objective is to match the results of the deformed cavity model to experimental data through least-squares minimization. The inversion variables are unknown shape deformation parameters that describe perturbations of the ideal cavity. The constraint is the Maxwell eigenvalue problem. We solve the nonlinear optimization problem using a line-search based reduced space Gauss-Newton method where we compute shape sensitivities with a discrete adjoint approach. We present two shape determination examples, one from synthetic and the other from experimental data. The results demonstrate that the proposed algorithm is very effective in determining the deformed cavity shape.

  13. Shaping asteroid models using genetic evolution (SAGE)

    Science.gov (United States)

    Bartczak, P.; Dudziński, G.

    2018-02-01

    In this work, we present SAGE (shaping asteroid models using genetic evolution), an asteroid modelling algorithm based solely on photometric lightcurve data. It produces non-convex shapes, orientations of the rotation axes and rotational periods of asteroids. The main concept behind a genetic evolution algorithm is to produce random populations of shapes and spin-axis orientations by mutating a seed shape and iterating the process until it converges to a stable global minimum. We tested SAGE on five artificial shapes. We also modelled asteroids 433 Eros and 9 Metis, since ground truth observations for them exist, allowing us to validate the models. We compared the derived shape of Eros with the NEAR Shoemaker model and that of Metis with adaptive optics and stellar occultation observations since other models from various inversion methods were available for Metis.

  14. Shape Descriptors for the Quantification of Microstructures

    Science.gov (United States)

    2016-01-05

    interacted with Dr. Alan Ardell (UCLA) to compare their shape analysis of super alloy gamma’ particles with our own. She also collaborated with Prof. Veera...them. Furthermore, this project should establish a mathematical and numerical methodology for the analysis and identification of 3-D shapes based on...a mathematical and numerical methodology for the analysis and identification of 3-D shapes based on random 2-D sections and explore ways in which this

  15. Shape measurements of volcanic particles by CAMSIZER

    OpenAIRE

    Lo Castro, Maria Deborah; Andronico, Daniele; Nunnari, Giuseppe; Spata, Alessandro; Torrisi, Alessio

    2009-01-01

    The shape of volcanic particles is an important parameter holding information related to physical and geochemical processes. The study of particle shape may help improving knowledge on the main eruptive processes (fragmentation, transport and sedimentation) during explosive activity. In general, volcanic ash is formed by different components, namely juvenile, lithic and crystal particles, each one characterized by peculiar morphology. Moreover, quantifying the shape of pyroclasts is needed by...

  16. Post polymerization cure shape memory polymers

    Science.gov (United States)

    Wilson, Thomas S; Hearon, Michael Keith; Bearinger, Jane P

    2014-11-11

    This invention relates to chemical polymer compositions, methods of synthesis, and fabrication methods for devices regarding polymers capable of displaying shape memory behavior (SMPs) and which can first be polymerized to a linear or branched polymeric structure, having thermoplastic properties, subsequently processed into a device through processes typical of polymer melts, solutions, and dispersions and then crossed linked to a shape memory thermoset polymer retaining the processed shape.

  17. Post polymerization cure shape memory polymers

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Thomas S.; Hearon, II, Michael Keith; Bearinger, Jane P.

    2017-01-10

    This invention relates to chemical polymer compositions, methods of synthesis, and fabrication methods for devices regarding polymers capable of displaying shape memory behavior (SMPs) and which can first be polymerized to a linear or branched polymeric structure, having thermoplastic properties, subsequently processed into a device through processes typical of polymer melts, solutions, and dispersions and then crossed linked to a shape memory thermoset polymer retaining the processed shape.

  18. A Cable-Shaped Lithium Sulfur Battery.

    Science.gov (United States)

    Fang, Xin; Weng, Wei; Ren, Jing; Peng, Huisheng

    2016-01-20

    A carbon nanostructured hybrid fiber is developed by integrating mesoporous carbon and graphene oxide into aligned carbon nanotubes. This hybrid fiber is used as a 1D cathode to fabricate a new cable-shaped lithium-sulfur battery. The fiber cathode exhibits a decent specific capacity and lifespan, which makes the cable-shaped lithium-sulfur battery rank far ahead of other fiber-shaped batteries. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Topology-Varying Shape Matching and Modeling

    OpenAIRE

    Alhashim, Ibraheem

    2015-01-01

    The automatic creation of man-made 3D objects is an active area in computer graphics. Computer-assisted mixing and blending of components or subcomponents from existing example shapes can help users quickly produce interesting and creative designs. A key factor for automating this task is using algorithms that can match compatible parts between objects of different shape and structure. However, due to the coarse correspondence computed by current matching algorithms, automatic shape blending ...

  20. Binary asteroid orbit evolution due to primary shape deformation

    Science.gov (United States)

    Hirabayashi, Masatoshi; Jacobson, Seth A.; Davis, Alex

    2017-10-01

    About a sixth of all small asteroid systems are binary [Margot et al., Science, 2002]. Many binary asteroids consist of an elongated synchronous secondary body orbiting a fast-rotating spheroidal primary body with ridges on its equator. The primary in such systems has experienced a long-term spin-up due to the YORP effect [Vokrouhlick'y et al., Asteroid IV, 2015]. This spin-up process can make the primary reach its spin barrier inducing shape deformation processes that ease the structural condition for failure inside the primary [e.g., Holsapple, Icarus, 2010]. Earlier works have shown that structural heterogeneities in the primary such as the shape and density distribution induce asymmetric deformation [Sánchez and Scheeres, Icarus, 2016]. Here, we investigate how asymmetric shape deformation in the primary affects the mutual motion of a binary system. We use a dynamics model for an irregularly shaped binary system that accounts for possible deformation of the primary [Hirabayashi et al., LPSC, 2017]. In this model, we consider asymmetric deformation that occurs based on structural failure in the primary and thus it modifies the location of the center of mass of the system. Using 1999 KW4 as an example, we study a hypothetical case in which the primary is initially identical to the current shape [Ostro et al., Science, 2006] with an aspect ratio (AR) of 0.83 and then suddenly changes its shape to an AR of 0.76. The results show that the asymmetric deformation process and the shift of the center of mass excite the eccentricity of the mutual orbit. Considering that the original mutual orbit has an eccentricity of 0.0004, after the primary shape change the eccentricity reaches values up to 0.15. Also, since the gravity field is modified after deformation, the secondary’s spin is desynchronized from the mutual orbit. Since synchronicity is a requirement for the binary YORP (BYORP) effect, which modifies the semi-major axis of binary asteroids, a primary shape

  1. Can partial coherence interferometry be used to determine retinal shape?

    Science.gov (United States)

    Atchison, David A; Charman, W Neil

    2011-05-01

    To determine likely errors in estimating retinal shape using partial coherence interferometric instruments when no allowance is made for optical distortion. Errors were estimated using Gullstrand no. 1 schematic eye and variants which included a 10 diopter (D) axial myopic eye, an emmetropic eye with a gradient-index lens, and a 10.9 D accommodating eye with a gradient-index lens. Performance was simulated for two commercial instruments, the IOLMaster (Carl Zeiss Meditec) and the Lenstar LS 900 (Haag-Streit AG). The incident beam was directed toward either the center of curvature of the anterior cornea (corneal-direction method) or the center of the entrance pupil (pupil-direction method). Simple trigonometry was used with the corneal intercept and the incident beam angle to estimate retinal contour. Conics were fitted to the estimated contours. The pupil-direction method gave estimates of retinal contour that were much too flat. The cornea-direction method gave similar results for IOLMaster and Lenstar approaches. The steepness of the retinal contour was slightly overestimated, the exact effects varying with the refractive error, gradient index, and accommodation. These theoretical results suggest that, for field angles ≤30°, partial coherence interferometric instruments are of use in estimating retinal shape by the corneal-direction method with the assumptions of a regular retinal shape and no optical distortion. It may be possible to improve on these estimates out to larger field angles by using optical modeling to correct for distortion.

  2. Individual personalities shape task differentiation in a social spider.

    Science.gov (United States)

    Grinsted, Lena; Pruitt, Jonathan N; Settepani, Virginia; Bilde, Trine

    2013-09-22

    Deciphering the mechanisms involved in shaping social structure is key to a deeper understanding of the evolutionary processes leading to sociality. Individual specialization within groups can increase colony efficiency and consequently productivity. Here, we test the hypothesis that within-group variation in individual personalities (i.e. boldness and aggression) can shape task differentiation. The social spider Stegodyphus sarasinorum (Eresidae) showed task differentiation (significant unequal participation) in simulated prey capture events across 10-day behavioural assays in the field, independent of developmental stage (level of maturation), eliminating age polyethism. Participation in prey capture was positively associated with level of boldness but not with aggression. Body size positively correlated with being the first spider to emerge from the colony as a response to prey capture but not with being the first to attack, and dispersal distance from experimental colonies correlated with attacking but not with emerging. This suggests that different behavioural responses to prey capture result from a complex set of individual characteristics. Boldness and aggression correlated positively, but neither was associated with body size, developmental stage or dispersal distance. Hence, we show that personalities shape task differentiation in a social spider independent of age and maturation. Our results suggest that personality measures obtained in solitary, standardized laboratory settings can be reliable predictors of behaviour in a social context in the field. Given the wealth of organisms that show consistent individual behavioural differences, animal personality could play a role in social organization in a diversity of animals.

  3. A Theory of Shape-Shifting Droplets

    Science.gov (United States)

    Haas, Pierre; Goldstein, Raymond; Smoukov, Stoyan; Denkov, Nikolai

    2016-11-01

    Recent observations of cooled oil emulsion droplets uncovered a remarkable array of shape transformations: the initially spherical droplets flatten into polygonal shapes, first hexagons, then triangles or quadrilaterals that ultimately grow thin protrusions from their corners. These transformations are driven by a partial phase transition of the bulk liquid phase. In this talk, we explore theoretically the simplest geometric competition between this phase transition and surface tension in planar polygons. We recover the experimental sequence of shapes and predict shape statistics in qualitative agreement with experiments. Extending the model to capture some of the three-dimensional structure of the droplets, we analyse the topological transition of droplet puncture observed in experiments.

  4. The natural shape balloon and related models

    Science.gov (United States)

    Baginski, F.; Winker, J.

    Typically, the design shape of a large scientific balloon is an axisymmetric stat- ically determinate shape in which only the weight of the balloon system and the lifting gas are taken into consideration. These equations were originally developed in the 1950s at the University of Minnesota, and in the special case when the circumferential stress is zero, have come to be known as the natural shape equations. Over the years, variants of these equations have been redis- covered and their relation to the general framework sometimes obscured. We will present a brief exposition of the natural shape equations, and show how a number of balloon models follow from it.

  5. Preliminary Measurement of Lunar Particle Shapes.

    Science.gov (United States)

    Rickman, Doug

    2013-01-01

    Particle shape is a basic parameter and essential for many engineering applications. Very little data is published on the shape of lunar particles. An unpublished review found that even where the same samples were studied the results were contradictory, probably because of extremely small sample sizes. Other workers have made fundamental errors in algorithms. There are many ways to measure particle shape. One common approach is to examine the particles as intersected by a plain, such as a thin section. If discrete particles can be segmented from the image, programs such as ImageJ can readily obtain shape measurements for each particle.

  6. ISR Radial Field Magnet

    CERN Multimedia

    1983-01-01

    There were 37 (normal) + 3 (special) Radial Field magnets in the ISR to adjust vertically the closed orbit. Gap heights and strengths were 200 mm and .12 Tm in the normal magnets, 220 mm and .18 Tm in the special ones. The core length was 430 mm in both types. Due to their small length as compared to the gap heights the end fringe field errors were very important and had to be compensated by suitably shaping the poles. In order to save on cables, as these magnets were located very far from their power supplies, the coils of the normal type magnets were formed by many turns of solid cpper conductor with some interleaved layers of hollow conductor directly cooled by circulating water

  7. Recoverable Wire-Shaped Supercapacitors with Ultrahigh Volumetric Energy Density for Multifunctional Portable and Wearable Electronics.

    Science.gov (United States)

    Shi, Minjie; Yang, Cheng; Song, Xuefeng; Liu, Jing; Zhao, Liping; Zhang, Peng; Gao, Lian

    2017-05-24

    Wire-shaped supercapacitors (SCs) based on shape memory materials are of considerable interest for next-generation portable and wearable electronics. However, the bottleneck in this field is how to develop the devices with excellent electrochemical performance while well-maintaining recoverability and flexibility. Herein, a unique asymmetric electrode concept is put forward to fabricate smart wire-shaped SCs with ultrahigh energy density, which is realized by using porous carbon dodecahedra coated on NiTi alloy wire and flexible graphene fiber as yarn electrodes. Notably, the wire-shaped SCs not only exhibit high flexibility that can be readily woven into real clothing but also represent the available recoverable ability. When irreversible plastic deformations happen, the deformed shape of the devices can automatically resume the initial predesigned shape in a warm environment (about 35 °C). More importantly, the wire-shaped SCs act as efficient energy storage devices, which display high volumetric energy density (8.9 mWh/cm(3)), volumetric power density (1080 mW/cm(3)), strong durability in multiple mechanical states, and steady electrochemical behavior after repeated shape recovery processes. Considering their relative facile fabrication technology and excellent electrochemical performance, this asymmetric electrode strategy produced smart wire-shaped supercapacitors desirable for multifunctional portable and wearable electronics.

  8. Magnetic Field

    DEFF Research Database (Denmark)

    Olsen, Nils

    2015-01-01

    of the fluid flow at the top of the core. However, what is measured at or near the surface of the Earth is the superposition of the core field and fields caused by magnetized rocks in the Earth’s crust, by electric currents flowing in the ionosphere, magnetosphere, and oceans, and by currents induced......he Earth has a large and complicated magnetic field, the major part of which is produced by a self-sustaining dynamo operating in the fluid outer core. Magnetic field observations provide one of the few tools for remote sensing the Earth’s deep interior, especially regarding the dynamics...... in the Earth by time-varying external fields. These sources have their specific characteristics in terms of spatial and temporal variations, and their proper separation, based on magnetic measurements, is a major challenge. Such a separation is a prerequisite for remote sensing by means of magnetic field...

  9. Metamaterials based on wedge-shaped electrodynamic structures

    Directory of Open Access Journals (Sweden)

    Mitrokhin Vladimir

    2017-01-01

    Full Text Available The paper studies a possibility of simulation of artificial composite media with negative values of the real part of the equivalent dielectric (magnetic permittivity, by the use of segments of hollow composite waveguides with cylindrical guided waves in evanescent mode. Reactive evanescent fields of wedge-shaped waveguide eigenmodes are formed in the evanescent region before the critical section of the waveguide which separates the quasistatic field region from the distributing field of the evanescent waveguide mode. The possibility of simulation is determined by the equivalence of dispersion equation of the eigenmode propagation constant and the dispersion equation for the electric (magnetic permittivity of plasma-like medium if cut-off frequency and electric (magnetic plasma frequency of the medium are equal.

  10. 3D shape measurement system developed on mobile platform

    Science.gov (United States)

    Wu, Zhoujie; Chang, Meng; Shi, Bowen; Zhang, Qican

    2017-02-01

    Three-dimensional (3-D) shape measurement technology based on structured light has become one hot research field inspired by the increasing requirements. Many methods have been implemented and applied in the industry applications, but most of their equipments are large and complex, cannot be portable. Meanwhile, the popularity of the smart mobile terminals, such as smart phones, provides a platform for the miniaturization and portability of this technology. The measurement system based on phase-shift algorithm and Gray-code pattern under the Android platform on a mobile phone is mainly studied and developed, and it has been encapsulated into a mobile phone application in order to reconstruct 3-D shape data in the employed smart phone easily and quickly. The experimental results of two measured object are given in this paper and demonstrate the application we developed in the mobile platform is effective.

  11. A Novel 2D Z-Shaped Electromagnetic Bandgap Structure

    Directory of Open Access Journals (Sweden)

    I. Iliev

    2015-02-01

    Full Text Available This paper researches a novel 2D Z-shaped Electromagnetic Band-Gap (EBG structure, its dispersion diagram and application field. Based on a transmission line model, the dispersion equation is derived and theoretically investigated. In order to validate theoretical results, a full wave analysis is performed and the electromagnetic properties of the structure are revealed. The theoretical results show good agreement with the full wave simulation results. The frequency response of the structure is compared to the well know structures of Jerusalem cross and patch EBG. The results show the applicability of the proposed 2D Z-shaped EBG in microstrip patch antennas, microstrip filters and high speed switching circuits, where the suppression of parasitic surface wave is required.

  12. Modelling shape of architectural structure: Elliptic hyperboloid of one sheet

    Directory of Open Access Journals (Sweden)

    Dragović Magdalena

    2014-01-01

    Full Text Available The combination of straight lines of constructive elements and curved contours of structural shapes is always challenging in the engineering practice. The 2nd order surface - elliptic hyperboloid of one sheet (ELHY provides such combination. Given that in the architectural surroundings, arts, or other scientific fields ELHY is less common, than the other representatives of the same family of ruled surfaces, it is worth of attention and research. Here presented constructive geometry approach resulted in Auto CAD application for generating 3D wire-frame and triangulated net model of ELHY surface and some examples of structures - prototypes of structural shapes, designed by using ELHY fragments. [Projekat Ministarstva nauke Republike Srbije, br. TR36008: Development and application of scientific methods in design and building of high economic structural systems by application of new technologies, the part of which is the present study

  13. A comparative analysis of leaf shape of wheat, barley and maize using an empirical shape model.

    Science.gov (United States)

    Dornbusch, Tino; Watt, Jillian; Baccar, Rim; Fournier, Christian; Andrieu, Bruno

    2011-04-01

    The phenotypes of grasses show differences depending on growth conditions and ontogenetic stage. Understanding these responses and finding suitable mathematical formalizations are an essential part of the development of plant and crop models. Usually, a marked change in architecture between juvenile and adult plants is observed, where dimension and shape of leaves are likely to change. In this paper, the plasticity of leaf shape is analysed according to growth conditions and ontogeny. Leaf shape of Triticum aestivum, Hordeum vulgare and Zea mays cultivars grown under varying conditions was measured using digital image processing. An empirical leaf shape model was fitted to measured shape data of single leaves. Obtained values of model parameters were used to analyse the patterns in leaf shape. The model was able to delineate leaf shape of all studied species. The model error was small. Differences in leaf shape between juvenile and adult leaves in T. aestivum and H. vulgare were observed. Varying growth conditions impacted leaf dimensions but did not impact leaf shape of the respective species. Leaf shape of the studied T. aestivum and H. vulgare cultivars was remarkably stable for a comparable ontogenetic stage (leaf rank), but differed between stages. Along with other aspects of grass architecture, leaf shape changed during the transition from juvenile to adult growth phase. Model-based analysis of leaf shape is a method to investigate these differences. Presented results can be integrated into architectural models of plant development to delineate leaf shape for different species, cultivars and environmental conditions.

  14. Shape memory alloys applied to improve rotor-bearing system dynamics - an experimental investigation

    DEFF Research Database (Denmark)

    Enemark, Søren; Santos, Ilmar; Savi, Marcelo A.

    2015-01-01

    hysteretic stress-strain relations which may be utilized for damping purposes. These ideas are tested in this study on a dedicated test-rig, consisting of a rigid shaft and disc held vertically by passive magnetic bearings, where the damping is low. The bearing housings is flexibly supported by shape memory......tor-bearing systems have critical speeds and to pass through them is an ongoing challenge in the field of mechanical engineering. The incorporation of shape memory alloys in rotating systems has an increasing importance to improve system performance and to avoid potential damaging situations when...... passing through critical speeds. In this work, the feasibility of applying shape memory alloys to a rotating system is experimentally investigated. Shape memory alloys can change their stiffness with temperature variations and thus they may change system dynamics. Shape memory alloys also exhibit...

  15. Conceptual shape optimization of entry vehicles applied to capsules and winged fuselage vehicles

    CERN Document Server

    Dirkx, Dominic

    2017-01-01

    This book covers the parameterization of entry capsules, including Apollo capsules and planetary probes, and winged entry vehicles such as the Space Shuttle and lifting bodies. The aerodynamic modelling is based on a variety of panel methods that take shadowing into account, and it has been validated with flight and wind tunnel data of Apollo and the Space Shuttle. The shape optimization is combined with constrained trajectory analysis, and the multi-objective approach provides the engineer with a Pareto front of optimal shapes. The method detailed in Conceptual Shape Optimization of Entry Vehicles is straightforward, and the output gives the engineer insight in the effect of shape variations on trajectory performance. All applied models and algorithms used are explained in detail, allowing for reconstructing the design tool to the researcher’s requirements. Conceptual Shape Optimization of Entry Vehicles will be of interest to both researchers and graduate students in the field of aerospace engineering, an...

  16. Combining Shape-Changing Interfaces and Spatial Augmented Reality Enables Extended Object Appearance

    DEFF Research Database (Denmark)

    Lindlbauer, David; Grønbæk, Jens Emil; Birk, Morten

    2016-01-01

    for increasing the realism of 3D objects such as bump mapping. This extensible framework helps us identify challenges of the two techniques and benefits of their combination. We utilize our prototype shape-changing device enriched with spatial augmented reality through projection mapping to demonstrate...... the concept. We present a novel mechanical distance-fields algorithm for real-time fitting of mechanically constrained shape-changing devices to arbitrary 3D graphics. Furthermore, we present a technique for increasing effective screen real estate for spatial augmented reality through view-dependent shape......We propose combining shape-changing interfaces and spatial augmented reality for extending the space of appearances and interactions of actuated interfaces. While shape-changing interfaces can dynamically alter the physical appearance of objects, the integration of spatial augmented reality...

  17. Shaping science policy in Europe.

    Science.gov (United States)

    Celis, Julio E; Gago, José Mariano

    2014-05-01

    The Lisbon Strategy was adopted by the Heads of State and Government of the European Union (EU) in 2000. By moving science into a central position for the development of a European knowledge-based economy and society, its adoption at political level seems to have been a powerful catalyst for the increased involvement of scientists in science policy in the EU. Recognising the need for scientists to act collectively in order to contribute to shape the future of science policy in Europe, a pioneering group of European science organisations leaders and representatives, as well as other scientists, initiated a European, interdisciplinary, inclusive movement leading to the creation of the European Research Council (ERC) to support basic research of the highest quality. Having scientists' campaign for the funding of bottom-up research by the EU Framework Programmes exclusively on scientific grounds, and for an ERC, was a unique event in the recent history of European science policy. For the first time, the scientific community acted collectively and across disciplinary or national boundaries as a political actor for the sake of a better science policy for Europe. As is often the case when first-hand experience is gained through the creation of a new organization, novel forms of collaboration arise. The European biomedical community has recently proposed the creation of a strategic action plan for health research (the European Council of Health Research; EuCHR), provisionally translated at present into a Scientific Panel for Health (SPH) research in Horizon 2020, the EU's research-funding programme for the period 2014-2020. The creation of such Scientific Panel should be viewed as an important contribution by the biomedical community as a major political agreement has been reached on the need for a comprehensive and long-term scientific strategy to accelerate research and facilitate innovation at EU level. It is our belief that describing and analyzing the process leading

  18. Physics conclusions in support of ITER W divertor monoblock shaping

    Directory of Open Access Journals (Sweden)

    R.A. Pitts

    2017-08-01

    Full Text Available The key remaining physics design issue for the ITER tungsten (W divertor is the question of monoblock (MB front surface shaping in the high heat flux target areas of the actively cooled targets. Engineering tolerance specifications impose a challenging maximum radial step between toroidally adjacent MBs of 0.3mm. Assuming optical projection of the parallel heat loads, magnetic shadowing of these edges is required if quasi-steady state melting is to be avoided under certain conditions during burning plasma operation and transiently during edge localized mode (ELM or disruption induced power loading. An experiment on JET in 2013 designed to investigate the consequences of transient W edge melting on ITER, found significant deficits in the edge power loads expected on the basis of simple geometric arguments, throwing doubt on the understanding of edge loading at glancing field line angles. As a result, a coordinated multi-experiment and simulation effort was initiated via the International Tokamak Physics Activity (ITPA and through ITER contracts, aimed at improving the physics basis supporting a MB shaping decision from the point of view both of edge power loading and melt dynamics. This paper reports on the outcome of this activity, concluding first that the geometrical approximation for leading edge power loading on radially misaligned poloidal leading edges is indeed valid. On this basis, the behaviour of shaped and unshaped monoblock surfaces under stationary and transient loads, with and without melting, is compared in order to examine the consequences of melting, or power overload in context of the benefit, or not, of shaping. The paper concludes that MB top surface shaping is recommended to shadow poloidal gap edges in the high heat flux areas of the ITER divertor targets.

  19. Shape configuration and category-specificity

    DEFF Research Database (Denmark)

    Gerlach, Christian; Law, Ian; Paulson, Olaf B.

    2006-01-01

    We examined the neural correlates of visual shape configuration, the binding of local shape characteristics into wholistic object descriptions, by comparing the regional cerebral blood flow associated with recognition of outline drawings and fragmented drawings. We found no areas that responded m...

  20. Listening to the Shape of a Drum

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 3; Issue 10. Listening to the Shape of a Drum - You Cannot Hear the Shape of a Drum! S Kesavan. General Article Volume 3 Issue 10 October 1998 pp 49-58. Fulltext. Click here to view fulltext PDF. Permanent link:

  1. Encounters on a Shape-changing Bench

    DEFF Research Database (Denmark)

    Kinch, Sofie; Grönvall, Erik; Petersen, Marianne Graves

    2014-01-01

    ; a concert hall, an airport and a shopping mall. We gathered insights from more than 120 people, as they unexpectedly encountered the shape changing capabilities of the bench. By taking the user tests out of the lab and into the wild, we explored the influence of context on the users experience of a shape...

  2. Isogeometric shape optimization in fluid mechanics

    DEFF Research Database (Denmark)

    Nørtoft, Peter; Gravesen, Jens

    2013-01-01

    The subject of this work is numerical shape optimization in fluid mechanics, based on isogeometric analysis. The generic goal is to design the shape of a 2-dimensional flow domain to minimize some prescribed objective while satisfying given geometric constraints. As part of the design problem...

  3. Continuous Aerodynamic Modelling of Entry Shapes

    NARCIS (Netherlands)

    Dirkx, D.; Mooij, E.

    2011-01-01

    During the conceptual design phase of a re-entry vehicle, the vehicle shape can be varied and its impact on performance evaluated. To this end, the continuous modeling of the aerodynamic characteristics as a function of the shape is useful in exploring the full design space. Local inclination

  4. Haptic perception of shapes and line drawings

    NARCIS (Netherlands)

    Wijntjes, M.W.A.

    2008-01-01

    In this thesis various aspect of haptic perception were studied. The first part of the thesis is mainly concerned with haptic perception of two-dimensional shapes and line drawings. We first studied the angular acuity of two-dimensional shapes an found that the manner of exploration as well as the

  5. Deformable segmentation via sparse shape representation.

    Science.gov (United States)

    Zhang, Shaoting; Zhan, Yiqiang; Dewan, Maneesh; Huang, Junzhou; Metaxas, Dimitris N; Zhou, Xiang Sean

    2011-01-01

    Appearance and shape are two key elements exploited in medical image segmentation. However, in some medical image analysis tasks, appearance cues are weak/misleading due to disease/artifacts and often lead to erroneous segmentation. In this paper, a novel deformable model is proposed for robust segmentation in the presence of weak/misleading appearance cues. Owing to the less trustable appearance information, this method focuses on the effective shape modeling with two contributions. First, a shape composition method is designed to incorporate shape prior on-the-fly. Based on two sparsity observations, this method is robust to false appearance information and adaptive to statistically insignificant shape modes. Second, shape priors are modeled and used in a hierarchical fashion. More specifically, by using affinity propagation method, our deformable surface is divided into multiple partitions, on which local shape models are built independently. This scheme facilitates a more compact shape prior modeling and hence a more robust and efficient segmentation. Our deformable model is applied on two very diverse segmentation problems, liver segmentation in PET-CT images and rodent brain segmentation in MR images. Compared to state-of-art methods, our method achieves better performance in both studies.

  6. Alpha Shape Topology of the Cosmic Web

    NARCIS (Netherlands)

    Weygaert, Rien van de; Platen, Erwin; Vegter, Gert; Eldering, Bob; Kruithof, Nico

    2010-01-01

    We study the topology of the Megaparsec Cosmic Web on the basis of the Alpha Shapes of the galaxy distribution. The simplicial complexes of the alpha shapes are used to determine the set of Betti numbers (βk, k = 1, . . . , D), which represent a complete characterization of the topology of a

  7. Alpha Shape Topology of the Cosmic Web

    NARCIS (Netherlands)

    Weygaert, Rien van de; Vegter, Gert; Platen, Erwin; Kruithof, Nico; Eldering, Bob

    2010-01-01

    Abstract—We study the topology of the Megaparsec Cosmic Web on the basis of the Alpha Shapes of the galaxy distribution. The simplicial complexes of the alpha shapes are used to determine the set of Betti numbers (k; k = 1; : : : ;D), which represent a complete characterization of the topology of a

  8. Shaping Education Policy: Power and Process

    Science.gov (United States)

    Mitchell, Douglas E., Ed.; Crowson, Robert L., Ed.; Shipps, Dorothy, Ed.

    2011-01-01

    "Shaping Education Policy" is a comprehensive overview of education politics and policy during the most turbulent and rapidly changing period in American history. Respected scholars review the history of education policy to explain the political powers and processes that shape education today. Chapters cover major themes that have…

  9. Nanoparticle Netpoints for Shape-Memory Polymers

    KAUST Repository

    Agarwal, Praveen

    2011-08-02

    Forget-me-not: Nanoparticle fillers in shape-memory polymers usually improve mechanical properties at the expense of shape-memory performance. A new approach overcomes these drawbacks by cross-linking the functionalized poly(ethylene glycol) tethers on silica nanoparticles (see picture). Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Shape memory alloys – characterization techniques

    Indian Academy of Sciences (India)

    A space-rotating platform is designed and fabricated, using an actuator of shape memory spring, for obtaining controlled rotations. The efficiency and the reliability of this actuator has been tested, over a million thermal cycles. Keywords. Shape memory alloys; characterization techniques; austenitic phase; martensitic phase;.

  11. Resummed coefficient function for the shape function

    OpenAIRE

    Aglietti, U.

    2001-01-01

    We present a leading evaluation of the resummed coefficient function for the shape function. It is also shown that the coefficient function is short-distance-dominated. Our results allow relating the shape function computed on the lattice to the physical QCD distributions.

  12. Active haptic detection and discrimination of shape

    NARCIS (Netherlands)

    Louw, S.; Kappers, A.M.L.; Koenderink, J.J.

    2002-01-01

    In previous research, we have shown that detection thresholds for Gaussian shapes increase with a power of 1.3 of spatial width. In the present three experiments, we generalized this finding to more complex shapes and to discrimination tasks. In Experiment 1, we found that the slope of the

  13. Shape recovery of viscoelastic beams after stowage

    DEFF Research Database (Denmark)

    Kwok, Kawai

    2015-01-01

    for the load relaxation and shape recovery of a linear viscoelastic beam subject to such time-varying constraints. It is shown that a viscoelastic beam recovers to its original shape asymptotically over time. The analytical solutions are employed to investigate the effect of temperature and stowage time...

  14. Fourier Series, the DFT and Shape Modelling

    DEFF Research Database (Denmark)

    Skoglund, Karl

    2004-01-01

    This report provides an introduction to Fourier series, the discrete Fourier transform, complex geometry and Fourier descriptors for shape analysis. The content is aimed at undergraduate and graduate students who wish to learn about Fourier analysis in general, as well as its application to shape...

  15. Hand Shape Affects Access to Memories

    NARCIS (Netherlands)

    K. Dijkstra (Katinka); M.P. Kaschak; R.A. Zwaan (Rolf)

    2008-01-01

    textabstractThe present study examined the ways that body posture facilitated retrieval of autobiographical memories in more detail by focusing on two aspects of congruence in position of a specific body part: hand shape and hand orientation. Hand shape is important in the tactile perception and

  16. Protein transfer to membranes upon shape deformation

    NARCIS (Netherlands)

    Sagis, L.M.C.; Bijl, E.; Antono, L.; Ruijter, de N.C.A.; Valenberg, van H.J.F.

    2013-01-01

    Red blood cells, milk fat droplets, or liposomes all have interfaces consisting of lipid membranes. These particles show significant shape deformations as a result of flow. Here we show that these shape deformations can induce adsorption of proteins to the membrane. Red blood cell deformability is

  17. Information Communication Technology (ICT) Shaping Student Affairs.

    Science.gov (United States)

    Broughton, Elizabeth

    This paper opens with the following questions: "How prepared are you as a student affairs professional for information communication technology (ICT)? Do you understand such concepts as portals, e-business, Napster, computer use policies, and wireless communication? Will student affairs be shaped by ICT or will student affairs help shape ICT on…

  18. Thermal, electrochemical and mechanical properties of shape ...

    African Journals Online (AJOL)

    ... resemblance with structure of casted shape memory alloy obtained from the vacuum induction process. The Vickers hardness test was also performed. Quenched microstructure with improved hardness than pre-quenched structure was observed. Keywords: Shape Memory Alloy, Microstructure, Mechanical Properties ...

  19. Shape Grammars for Innovative Hybrid Typological Design

    DEFF Research Database (Denmark)

    Al-kazzaz, Dhuha; Bridges, Alan; Chase, Scott Curland

    2010-01-01

    This paper describes a new methodology of deriving innovative hybrid designs using shape grammars of heterogeneous designs. The method is detailed within three phases of shape grammars: analysis, synthesis and evaluation. In the analysis phase, the research suggests that original rules of each de...

  20. Abnormal fetal head shape: aetiology and management

    DEFF Research Database (Denmark)

    Petersen, Olav Bjørn; David, Anna; Thomasson, Louise

    2007-01-01

    (lemon-shaped), 18.4% with aneuploidy (mostly strawberry-shaped). 19.5% were dolicocephalic, most secondary to fetal position or oligohydramnios (see table). 13 had confirmed craniosynostosis, including thanatophoric dysplasia, Craniofrontonasal dysplasia, Aperts syndrome, Baller-Gerold syndrome, I...