WorldWideScience

Sample records for subgrain boundary types

  1. Influence of subgrain boundaries on coarsening of grain structures

    Science.gov (United States)

    Zöllner, D.; Skrotzki, W.

    2017-05-01

    In the present work, the influence of subgrain boundaries on the coarsening kinetics of individual grains embedded in an average environment as well as within a grain structure is investigated. It is found that a specific introduction of subgrain boundaries not only influences the speed with which grains shrink or grow, but in contrast to the von Neumann-Mullins-law, a distinct manipulation of the location of the subgrain boundaries allows even grains with few edges to grow, while grains with many edges shrink. During these circumstances one fact stays the same: the area of the individual grains is a linear function of annealing time as long as the environment does not change.

  2. EBSD analysis of subgrain boundaries and dislocation slip systems in Antarctic and Greenland ice

    Science.gov (United States)

    Weikusat, Ilka; Kuiper, Ernst-Jan N.; Pennock, Gill M.; Kipfstuhl, Sepp; Drury, Martyn R.

    2017-09-01

    Ice has a very high plastic anisotropy with easy dislocation glide on basal planes, while glide on non-basal planes is much harder. Basal glide involves dislocations with the Burgers vector b = 〈a〉, while glide on non-basal planes can involve dislocations with b = 〈a〉, b = [c], and b = 〈c + a〉. During the natural ductile flow of polar ice sheets, most of the deformation is expected to occur by basal slip accommodated by other processes, including non-basal slip and grain boundary processes. However, the importance of different accommodating processes is controversial. The recent application of micro-diffraction analysis methods to ice, such as X-ray Laue diffraction and electron backscattered diffraction (EBSD), has demonstrated that subgrain boundaries indicative of non-basal slip are present in naturally deformed ice, although so far the available data sets are limited. In this study we present an analysis of a large number of subgrain boundaries in ice core samples from one depth level from two deep ice cores from Antarctica (EPICA-DML deep ice core at 656 m of depth) and Greenland (NEEM deep ice core at 719 m of depth). EBSD provides information for the characterization of subgrain boundary types and on the dislocations that are likely to be present along the boundary. EBSD analyses, in combination with light microscopy measurements, are presented and interpreted in terms of the dislocation slip systems. The most common subgrain boundaries are indicative of basal 〈a〉 slip with an almost equal occurrence of subgrain boundaries indicative of prism [c] or 〈c + a〉 slip on prism and/or pyramidal planes. A few subgrain boundaries are indicative of prism 〈a〉 slip or slip of 〈a〉 screw dislocations on the basal plane. In addition to these classical polygonization processes that involve the recovery of dislocations into boundaries, alternative mechanisms are discussed for the formation of subgrain boundaries that are not related to the

  3. EBSD analysis of subgrain boundaries and dislocation slip systems in Antarctic and Greenland ice

    Directory of Open Access Journals (Sweden)

    I. Weikusat

    2017-09-01

    Full Text Available Ice has a very high plastic anisotropy with easy dislocation glide on basal planes, while glide on non-basal planes is much harder. Basal glide involves dislocations with the Burgers vector b = 〈a〉, while glide on non-basal planes can involve dislocations with b = 〈a〉, b = [c], and b = 〈c + a〉. During the natural ductile flow of polar ice sheets, most of the deformation is expected to occur by basal slip accommodated by other processes, including non-basal slip and grain boundary processes. However, the importance of different accommodating processes is controversial. The recent application of micro-diffraction analysis methods to ice, such as X-ray Laue diffraction and electron backscattered diffraction (EBSD, has demonstrated that subgrain boundaries indicative of non-basal slip are present in naturally deformed ice, although so far the available data sets are limited. In this study we present an analysis of a large number of subgrain boundaries in ice core samples from one depth level from two deep ice cores from Antarctica (EPICA-DML deep ice core at 656 m of depth and Greenland (NEEM deep ice core at 719 m of depth. EBSD provides information for the characterization of subgrain boundary types and on the dislocations that are likely to be present along the boundary. EBSD analyses, in combination with light microscopy measurements, are presented and interpreted in terms of the dislocation slip systems. The most common subgrain boundaries are indicative of basal 〈a〉 slip with an almost equal occurrence of subgrain boundaries indicative of prism [c] or 〈c + a〉 slip on prism and/or pyramidal planes. A few subgrain boundaries are indicative of prism 〈a〉 slip or slip of 〈a〉 screw dislocations on the basal plane. In addition to these classical polygonization processes that involve the recovery of dislocations into boundaries, alternative mechanisms are discussed for the formation of subgrain

  4. Subgrain boundaries in Antarctic ice quantified by X-ray Laue diffraction

    OpenAIRE

    Weikusat, Ilka; Miyamoto,Atsushi; Faria, Sergio H.; Kipfstuhl, Sepp; Azuma, Nobuhiko; Hondoh,Takeo

    2011-01-01

    Ice in polar ice sheets undergoes deformation during its flow towards the coast. Deformation and recrystallization microstructures such as subgrain boundaries can be observed and recorded using high-resolution light microscopy of sublimation-edged sample surfaces (microstructure mapping). Subgrain boundaries observed by microstructure mapping reveal characteristic shapes and arrangements. As these arrangements are related to the basal plane orientation, full crystallographic or...

  5. Microscopic Distributions of Defect Luminescence From Subgrain Boundaries in Multicrystalline Silicon Wafers

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Hieu T.; Jensen, Mallory A.; Li, Li; Samundsett, Christian; Sio, Hang C.; Lai, Barry; Buonassisi, Tonio; Macdonald, Daniel

    2017-05-01

    We investigate the microscopic distributions of sub-band-gap luminescence emission (the so-called D-lines D1/D2/D3/D4) and the band-to-band luminescence intensity, near recombination-active sub-grain boundaries in multicrystalline silicon wafers for solar cells. We find that the sub-band-gap luminescence from decorating defects/impurities (D1/D2) and from intrinsic dislocations (D3/D4) have distinctly different spatial distributions, and are asymmetric across the sub-grain boundaries. The presence of D1/D2 is correlated with a strong reduction in the band-to-band luminescence, indicating a higher recombination activity. In contrast, D3/D4 emissions are not strongly correlated with the band-to-band intensity. Based on spatially-resolved, synchrotron-based micro-X-ray fluorescence measurements of metal impurities, we confirm that high densities of metal impurities are present at locations with strong D1/D2 emission but low D3/D4 emission. Finally, we show that the observed asymmetry of the sub-band-gap luminescence across the sub-grain boundaries is due to their inclination below the wafer surface. Based on the luminescence asymmetries, the sub-grain boundaries are shown to share a common inclination locally, rather than be orientated randomly.

  6. Segmentation of 3D EBSD data for subgrain boundary identification and feature characterization

    Energy Technology Data Exchange (ETDEWEB)

    Loeb, Andrew, E-mail: ael89@cornell.edu [Department of Engineering, Harvey Mudd College, 301 Platt Blvd, Claremont, CA 91711 (United States); Ferry, Michael [School of Materials Science and Engineering, The University of New South Wales, NSW 2052 (Australia); Bassman, Lori [Department of Engineering, Harvey Mudd College, 301 Platt Blvd, Claremont, CA 91711 (United States)

    2016-02-15

    Subgrain structures formed during plastic deformation of metals can be observed by electron backscatter diffraction (EBSD) but are challenging to identify automatically. We have adapted a 2D image segmentation technique, fast multiscale clustering (FMC), to 3D EBSD data using a novel variance function to accommodate quaternion data. This adaptation, which has been incorporated into the free open source texture analysis software package MTEX, is capable of segmenting based on subtle and gradual variation as well as on sharp boundaries within the data. FMC has been further modified to group the resulting closed 3D segment boundaries into distinct coherent surfaces based on local normals of a triangulated surface. We demonstrate the excellent capabilities of this technique with application to 3D EBSD data sets generated from cold rolled aluminum containing well-defined microbands, cold rolled and partly recrystallized extra low carbon steel microstructure containing three magnitudes of boundary misorientations, and channel-die plane strain compressed Goss-oriented nickel crystal containing microbands with very subtle changes in orientation. - Highlights: • Novel fast multiscale clustering (FMC) implementation segments 3D EBSD data. • FMC segments based on subtle or gradual variation as well as sharp boundaries. • A modification of FMC segments surfaces of microstructural feature volumes. • Method is incorporated in free open source texture analysis software package MTEX. • Several data sets demonstrate FMC and its advantages over Kuwahara filtering.

  7. Subgrain boundary analyses in deformed orthopyroxene by TEM/STEM with EBSD-FIB sample preparation technique

    Science.gov (United States)

    Kogure, Toshihiro; Raimbourg, Hugues; Kumamoto, Akihito; Fujii, Eiko; Ikuhara, Yuichi

    2014-12-01

    High-resolution structure analyses using electron beam techniques have been performed for the investigation of subgrain boundaries (SGBs) in deformed orthopyroxene (Opx) in mylonite from Hidaka Metamorphic Belt, Hokkaido, Japan, to understand ductile deformation mechanism of silicate minerals in shear zones. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) analysis of Opx porphyroclasts in the mylonitic rock indicated that the crystal orientation inside the Opx crystals gradually changes by rotation about the b-axis by SGBs and crystal folding. In order to observe the SGBs along the b-axis by transmission electron microscopy (TEM) or scanning TEM (STEM), the following sample preparation protocol was adopted. First, petrographic thin sections were slightly etched with hydrofluoric acid to identify SGBs in SEM. The Opx crystals whose b-axes were oriented close to the normal of the surface were identified by EBSD, and the areas containing SGBs were picked and thinned for (S) TEM analysis with a focused ion beam instrument with micro-sampling system. High-resolution TEM imaging of the SGBs in Opx revealed various boundary structures from a periodic array of dissociated (100) [001] edge dislocations to partially or completely incoherent crystals, depending on the misorientation angle. Atomic-resolution STEM imaging clearly confirmed the formation of clinopyroxene (Cpx) structure between the dissociated partial dislocations. Moreover, X-ray microanalysis in STEM revealed that the Cpx contains a considerable amount of calcium replacing iron. Such chemical inhomogeneity may limit glide motion of the dislocation and eventually the plastic deformation of the Opx porphyroclasts at a low temperature. Chemical profiles across the high-angle incoherent SGB also showed an enrichment of the latter in calcium at the boundary, suggesting that SGBs are an efficient diffusion pathway of calcium out of host Opx grain during cooling.

  8. EBSD analysis of heterogeneous microstructures in experimentally deformed calcite: development of core and mantle subgrains, grain boundary bulges and recrystallised grains. Geologica Ultraiectina (289)

    NARCIS (Netherlands)

    Valcke, S.L.A.|info:eu-repo/dai/nl/304833452

    2008-01-01

    Geodynamic processes such as subduction and rifting are mainly controlled by high temperature plastic deformation of rocks. It is known that elements of the microstructure in plastically deformed rocks, such as subgrains and recrystallised grains, are potentially useful as indicators of past

  9. The Role of Stress-Effected Subgrain Size Distribution in Anelastic Recovery: An Experimental Study on Polycrystalline Ice-Ih

    Science.gov (United States)

    Caswell, T. E.; Goldsby, D. L.; Cooper, R. F.; Prior, D. J.

    2013-12-01

    Anelasticity, or time-dependent and recoverable strain, is the source of attenuation at seismic and sub-seismic frequencies, yet the processes governing anelastic recovery are poorly resolved. Numerous experimental studies [e.g., 1-3] have demonstrated that anelasticity occurs via diffusion-effected relaxation along grain boundaries, which leads to a significant grain size sensitivity. Similar studies, however, conducted on deformed single crystals [e.g. 4], coarse-grained metals deforming in dislocation creep [e.g., 5] and polycrystalline ice deforming via a dislocation-accommodated mechanism [6] demonstrate the same frequency dependence, consistent with the grain boundary mechanism, but with no sensitivity to grain size. We postulate that it is the deformation-effected distribution of subgrains, which possesses unique diffusive properties relative to a defect-free lattice, that dominates attenuation in these situations. To test this idea we are conducting creep and stress-drop experiments on polycrystalline ice-Ih with concurrent high-resolution microstructural analysis conducted via Electron Backscatter Diffraction (EBSD) [7] to characterize the relationship between subgrain size distribution and diffusion-effected anelasticity. Our experiments establish the subgrain size distribution in steady-state creep of fine-grained ice-1h at compressional stresses between 0.1-4 MPa, which for the grain sizes and temperatures of our experiments places the rheology squarely within the regime of grain boundary sliding that is accommodated by basal dislocation slip [8]. We then explore the dynamics of the established microstructure, which includes subgrain formation [cf. 9], via stress-drop experiments [e.g. 10]. Experiments of this type allow the characterization of microstructural 'hardness,' i.e., the viscosity of the polycrystalline solid as effected by finite strain, from which we can discern the diffusive kinetics of subgrain boundaries [11, 12]. We are currently

  10. Study on Subgrain Rotation Behavior at Different Interfaces of a Solder Joint During Thermal Shock

    Science.gov (United States)

    Han, Jing; Tan, Shihai; Guo, Fu

    2016-12-01

    In order to investigate subgrain rotation behavior in the recrystallized region of lead-free solder joints, a ball grid array (BGA) specimen with a cross-sectioned edge row was thermally shocked. Electron backscattered diffraction (EBSD) was used to obtain the microstructure and orientations of Sn grains or subgrains in as-reflowed and thermally shocked conditions. Orientation imaging microscopy (OIM) showed that several subgrains were formed at the tilted twin grain boundaries, near the chip side and near the printed circuit board (PCB) side after 200 thermal shocks due to a highly mismatched coefficient of thermal expansion (CTE) of twin grains. Also, subgrains formed at the chip side and PCB side in the solder joint were selected to research the grain rotation behavior in lead-free solder joints. The analysis of subgrain rotation also indicated that the rotation behavior of subgrains was different between the chip side and PCB side. It was closely related with the large different crystal orientations between the chip side and PCB side. Furthermore, electron backscattered patterns (EBSPs) at several parts of the joint were not obtained after 300 thermal shocks due to the serious deformation caused by mismatched CTE during thermal shock. But 4 subgrains were selected and compared with that of the initial state and 200-thermal shock conditions. The results showed that the subgrains at the chip side were also rotated around the Sn [101] and [001] axes and the subgrains at the PCB side were also rotated around the Sn [100] axis, which indicated a continuous process of subgrain rotation.

  11. Simple Type is Not a Boundary Phenomenon

    CERN Document Server

    Sadun, L A

    1997-01-01

    This is an expository article, explaining recent work by D. Groisser and myself [GS] on the extent to which the boundary region of moduli space contributes to the ``simple type'' condition of Donaldson theory. The presentation is intended to complement [GS], presenting the essential ideas rather than the analytical details. It is shown that the boundary region of moduli space contributes 6/64 of the homology required for simple type, regardless of the topology or geometry of the underlying 4-manifold. The simple type condition thus reduces to a statement about the interior of moduli space, namely that the interior of the (k+1)st ASD moduli space, intersected with two representatives of (4 times) the point class, be homologous to 58 copies of the (k)-th moduli space. This is peculiar, since the only known embeddings of the (k)-th moduli space into the (k+1)st involve Taubes patching, and the image of such an embedding lies entirely in the boundary region.

  12. Boundaries and level of experience with six types of dreams.

    Science.gov (United States)

    Hicks, R A; Bautista, J; Hicks, G J

    1999-12-01

    The self-reported levels of experience to six types of dreams were compared for groups of students who classified as having either thin (n = 30) or thick (n = 86) boundaries. Consistent with predictions drawn from the literature, the thin-boundary group scored significantly higher on level of experience for each dream type than the thick-boundary group. These data provide additional validation for Hartmann's Boundary Questionnaire.

  13. Lyapunov-type inequalities for fractional boundary-value problems

    Directory of Open Access Journals (Sweden)

    Mohamed Jleli

    2015-04-01

    Full Text Available In this article, we establish some Lyapunov-type inequalities for fractional boundary-value problems under Sturm-Liouville boundary conditions. As applications, we obtain intervals where linear combinations of certain Mittag-Leffler functions have no real zeros. We deduce also nonexistence results for some fractional boundary-value problems.

  14. The effect of strain path change on subgrain volume fraction determined from in situ X-ray measurements

    DEFF Research Database (Denmark)

    Wejdemann, Christian; Poulsen, Henning Friis; Lienert, U.

    2009-01-01

    dislocation density called subgrains bounded by dislocation rich walls. With the new technique reciprocal space maps, consisting of sharp peaks arising from the subgrains superimposed on a cloud of lower intensity arising from the dislocation walls, are obtained, which allows properties such as subgrain...

  15. Simple Type and the Boundary of Moduli Space

    CERN Document Server

    Groisser, D; Groisser, David; Sadun, Lorenzo

    1997-01-01

    We measure, in two distinct ways, the extent to which the boundary region of moduli space contributes to the ``simple type'' condition of Donaldson theory. Using a geometric representative of \\mu(pt), the boundary region of moduli space contributes 6/64 of the homology required for simple type, regardless of the topology or geometry of the underlying 4-manifold. The simple type condition thus reduces to the interior of the k+1st ASD moduli space, intersected with two representatives of (4 times) the point class, being homologous to 58 copies of the k-th moduli space. This is peculiar, since the only known embeddings of the k-th moduli space into the k+1st involve Taubes gluing, and the images of such embeddings lie entirely in the boundary region. When using de Rham representatives of mu(pt), the boundary region contributes 1/8 of what is needed for simple type, again regardless of the topology or geometry of the underlying 4-manifold. The difference between this and the geometric representative answer is sur...

  16. Boundary identification in EBSD data with a generalization of fast multiscale clustering

    Energy Technology Data Exchange (ETDEWEB)

    McMahon, Cullen, E-mail: cullen_mcmahon@hmc.edu [Department of Engineering, Harvey Mudd College, 301 Platt Blvd, Claremont, CA 91711 (United States); Soe, Brian, E-mail: brian_soe@hmc.edu [Department of Engineering, Harvey Mudd College, 301 Platt Blvd, Claremont, CA 91711 (United States); Loeb, Andrew, E-mail: andrew_loeb@hmc.edu [Department of Engineering, Harvey Mudd College, 301 Platt Blvd, Claremont, CA 91711 (United States); Vemulkar, Ayyappa, E-mail: ayyappa_vemulkar@hmc.edu [Department of Engineering, Harvey Mudd College, 301 Platt Blvd, Claremont, CA 91711 (United States); Ferry, Michael, E-mail: m.ferry@unsw.edu.au [School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Bassman, Lori, E-mail: bassman@hmc.edu [Department of Engineering, Harvey Mudd College, 301 Platt Blvd, Claremont, CA 91711 (United States)

    2013-10-15

    Electron backscatter diffraction (EBSD) studies of cellular or subgrain microstructures present problems beyond those in the study of coarse-grained polycrystalline aggregates. In particular, identification of boundaries delineating some subgrain structures, such as microbands, cannot be accomplished simply with pixel-to-pixel misorientation thresholding because many of the boundaries are gradual transitions in crystallographic orientation. Fast multiscale clustering (FMC) is an established data segmentation technique that is combined here with quaternion representation of orientation to segment EBSD data with gradual transitions. This implementation of FMC addresses a common problem with segmentation algorithms, handling data sets with both high and low magnitude boundaries, by using a novel distance function that is a modification of Mahalanobis distance. It accommodates data representations, such as quaternions, whose features are not necessarily linearly correlated but have known distance functions. To maintain the linear run time of FMC with such data, the method requires a novel variance update rule. Although FMC was originally an algorithm for two-dimensional data segmentation, it can be generalized to analyze three-dimensional data sets. As examples, several segmentations of quaternion EBSD data sets are presented. - Highlights: • EBSD data with gradual or subtle boundaries presents problems in segmentation. • Fast multiscale clustering is modified for use with quaternion data. • Further generalizations to any data type with a distance metric are possible. • Polycrystalline and subgrain EBSD data sets are segmented as demonstration.

  17. Mapping and statistics of ferroelectric domain boundary angles and types

    Science.gov (United States)

    Desmarais, Joseph; Ihlefeld, Jon F.; Heeg, Tassilo; Schubert, Jürgen; Schlom, Darrell G.; Huey, Bryan D.

    2011-10-01

    Ferroelectric domain orientations have been mapped using piezo-force microscopy, allowing the calculation and statistical analysis of interfacial polarization angles, the head-to-tail or head-to-head configuration, and any cross-coupling terms. Within 1 µm2 of an epitaxial (001)p-oriented BiFeO3 film, there are >40 µm of linear domain boundary based on over 500 interfaces. 71° domain walls dominate the interfacial polarization angles, with a 2:1 preference for uncharged head-to-tail versus charged head-to-head boundary types. This mapping technique offers a unique perspective on domain boundary distributions, important for ferroelectric and multiferroic applications where domain wall parameters are critical.

  18. EBSD analysis of subgrain boundaries and dislocation slip systems in Antarctic and Greenland ice

    NARCIS (Netherlands)

    Weikusat, I.; Kuiper, E. N.; Pennock, G. M.; Kipfstuhl, S.; Drury, M. R.

    2017-01-01

    Ice has a very high plastic anisotropy with easy dislocation glide on basal planes, while glide on non-basal planes is much harder. Basal glide involves dislocations with the Burgers vector b = 〈a〉, while glide on non-basal planes can involve dislocations with b = 〈a〉, b = [c], and b = 〈c + a〉.

  19. Effects of subgrain size and static recrystallization on the mechanical performance of polycrystalline material: A microstructure-based crystal plasticity finite element analysis

    Directory of Open Access Journals (Sweden)

    Fengbo Han

    2015-02-01

    Full Text Available In this paper, the effects of subgrain size and static recrystallization on the mechanical performance of polycrystalline material were investigated using a microstructure-based crystal plasticity finite element (CPFE model. Firstly, polycrystalline microstructures with different mean subgrain sizes were prepared using simple assumption based on experimental observations, and intermediate microstructures during static recrystallization (SRX were simulated by a cellular automata model adopting curvature driven grain/subgrain growth mechanism. Then, CPFE method was applied to perform stress analysis of plane strain tension on these virtual microstructures. The results show that the subgrains inside pre-existing grains have an effect on the heterogeneity of the stress distributions. The average stress decreases with increasing the mean subgrain radius. As grain/subgrain grows during SRX, the average stress also decreases. It can be deduced that well-defined and finer subgrain structure may strengthen the polycrystalline material, while grain/subgrain growth during SRX process will degrade the strength.

  20. The evolution of disorientations for several types of boundaries

    DEFF Research Database (Denmark)

    Pantleon, W.

    2001-01-01

    origin of disorientations is considered, additional deterministic contributions arising from geometrical reasons are taken into account for geometrically necessary boundaries. The resulting diversity in the modelled boundary behaviour explains the experimentally observed differences in the dependence...

  1. Solvability of some Neumann-type boundary value problems for biharmonic equations

    Directory of Open Access Journals (Sweden)

    Valery Karachik

    2017-09-01

    Full Text Available We study some boundary-value problems for inhomogeneous biharmonic equation with periodic boundary conditions. These problems are generalization to periodic data of the Neumann-type boundary-value problems considered before by the authors. We obtain existence and uniqueness of solutions for the problems under consideration.

  2. Nonlinear Dynamics of Vortices in Different Types of Grain Boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Sheikhzada, Ahmad [Old Dominion Univ., Norfolk, VA (United States)

    2017-05-01

    As a major component of linear particle accelerators, superconducting radio-frequency (SRF) resonator cavities are required to operate with lowest energy dissipation and highest accelerating gradient. SRF cavities are made of polycrystalline materials in which grain boundaries can limit maximum RF currents and produce additional power dissipation sources due to local penetration of Josephson vortices. The essential physics of vortex penetration and mechanisms of dissipation of vortices driven by strong RF currents along networks of grain boundaries and their contribution to the residual surface resistance have not been well understood. To evaluate how GBs can limit the performance of SRF materials, particularly Nb and Nb3Sn, we performed extensive numerical simulations of nonlinear dynamics of Josephson vortices in grain boundaries under strong dc and RF fields. The RF power due to penetration of vortices both in weakly-coupled and strongly-coupled grain boundaries was calculated as functions of the RF field and frequency. The result of this calculation manifested a quadratic dependence of power to field amplitude at strong RF currents, an illustration of resistive behavior of grain boundaries. Our calculations also showed that the surface resistance is a complicated function of field controlled by penetration and annihilation of vortices and antivortices in strong RF fields which ultimately saturates to normal resistivity of grain boundary. We found that Cherenkov radiation of rapidly moving vortices in grain boundaries can produce a new instability causing generation of expanding vortex-antivortex pair which ultimately drives the entire GB in a resistive state. This effect is more pronounced in polycrystalline thin film and multilayer coating structures in which it can cause significant increase in power dissipation and results in hysteresis effects in I-V characteristics, particularly at low temperatures.

  3. Solvability of boundary-value problems for Poisson equations with Hadamard type boundary operator

    Directory of Open Access Journals (Sweden)

    Batirkhan Turmetov

    2016-06-01

    Full Text Available In this article we study properties of some integro-differential operators of fractional order. As an application of the properties of these operators for Poisson equation we examine questions on solvability of a fractional analogue of Neumann problem and analogues of periodic boundary-value problems for circular domains. The exact conditions for solvability of these problems are found.

  4. Ginzburg-Landau-type theory of antiphase boundaries in polytwinned structures

    CERN Document Server

    Vaks, V G

    2001-01-01

    The conventional Landau-Ginzburg theory of interphase boundaries is generalized to the case of not small values of order parameters, with application to polytwinned structures characteristic of cubic-tetragonal-type phase transitions. Explicit expressions for the structure and energy of antiphase boundaries via the functions entering the free energy functional are given. A peculiar dependence of equilibrium orientations of antiphase boundaries on the interaction type is predicted, and it qualitatively agrees with available experimental data

  5. Boundary Conditions for a New Type of Design Task

    DEFF Research Database (Denmark)

    McAloone, Tim C.

    2011-01-01

    -teresting to understand the shifting focus and identification of boundary conditions that manufacturing organisations must undergo, in order to develop just as systematic an approach to the service-related aspects of their business development, as they have in place for their product development. This chapter...... and knowledge associated with the use of the product is increasingly perceived to be the new design object. But how to organise the design of combined products and services, over expanded time domains and new stakeholder boundaries? The design research community is paying increasing attention to this new design...

  6. Subgrain and dislocation structure changes in hot-deformed high-temperature Fe-Ni austenitic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ducki, K.J.; Rodak, K.; Hetmanczyk, M.; Kuc, D

    2003-08-28

    The influence of plastic deformation on the substructure of a high-temperature austenitic Fe-Ni alloy has been presented. Hot-torsion tests were executed at constant strain rates of 0.1 and 1.0 s{sup -1}, at testing temperatures in the range 900-1150 deg. C. The examination of the microstructure was carried out, using transmission electron microscopy. Direct measurements on the micrographs allowed the calculation of structural parameters: the average subgrain area, and the mean dislocation density. A detailed investigation has shown that the microstructure is inhomogeneous, consisting of dense dislocation walls, subgrains and recrystallized regions.

  7. Properties of grain boundary networks in the NEEM ice core analyzed by combined transmission and reflection optical microscopy

    Science.gov (United States)

    Binder, Tobias; Weikusat, Ilka; Garbe, Christoph; Svensson, Anders; Kipfstuhl, Sepp

    2014-05-01

    Microstructure analysis of ice cores is vital to understand the processes controlling the flow of ice on the microscale. To quantify the microstructural variability (and thus occurring processes) on centimeter, meter and kilometer scale along deep polar ice cores, a large number of sections has to be analyzed. In the last decade, two different methods have been applied: On the one hand, transmission optical microscopy of thin sections between crossed polarizers yields information on the distribution of crystal c-axes. On the other hand, reflection optical microscopy of polished and controlled sublimated section surfaces allows to characterize the high resolution properties of a single grain boundary, e.g. its length, shape or curvature (further developed by [1]). Along the entire NEEM ice core (North-West Greenland, 2537 m length) drilled in 2008-2011 we applied both methods to the same set of vertical sections. The data set comprises series of six consecutive 6 x 9 cm2 sections in steps of 20 m - in total about 800 images. A dedicated method for automatic processing and matching both image types has recently been developed [2]. The high resolution properties of the grain boundary network are analyzed. Furthermore, the automatic assignment of c-axis misorientations to visible sublimation grooves enables us to quantify the degree of similarity between the microstructure revealed by both analysis techniques. The reliability to extract grain boundaries from both image types as well as the appearance of sublimation groove patterns exhibiting low misorientations is investigated. X-ray Laue diffraction measurements (yielding full crystallographic orientation) have validated the sensitivity of the surface sublimation method for sub-grain boundaries [3]. We introduce an approach for automatic extraction of sub-grain structures from sublimation grooves. A systematic analysis of sub-grain boundary densities indicates a possible influence of high impurity contents (amongst

  8. Metallographic screening of grain boundary engineered type 304 austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Hanning, F., E-mail: Fabian.Hanning@googlemail.com; Engelberg, D.L., E-mail: Dirk.engelberg@manchester.ac.uk

    2014-08-15

    An electrochemical etching method for the identification of grain boundary engineered type 304 austenitic stainless steel microstructures is described. The method can be applied for rapid microstructure screening to complement electron backscatter diffraction analysis. A threshold parameter to identify grain boundary engineered microstructure is proposed, and the application of metallographic etching for characterising the degree of grain boundary engineering discussed. - Highlights: • As-received (annealed) and grain boundary engineered microstructures were compared. • Electro-chemical polarisation in nitric acid solutions was carried out. • A metallographic screening method has been developed. • The screening method complements EBSD analysis for microstructure identification.

  9. Analytic Approximations to Nonlinear Boundary Value Problems Modeling Beam-Type Nano-Electromechanical Systems

    Science.gov (United States)

    Zou, Li; Liang, Songxin; Li, Yawei; Jeffrey, David J.

    2017-03-01

    Nonlinear boundary value problems arise frequently in physical and mechanical sciences. An effective analytic approach with two parameters is first proposed for solving nonlinear boundary value problems. It is demonstrated that solutions given by the two-parameter method are more accurate than solutions given by the Adomian decomposition method (ADM). It is further demonstrated that solutions given by the ADM can also be recovered from the solutions given by the two-parameter method. The effectiveness of this method is demonstrated by solving some nonlinear boundary value problems modeling beam-type nano-electromechanical systems.

  10. Analytic approximations to nonlinear boundary value problems modeling beam-type nano-electromechanical systems

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Li [Dalian Univ. of Technology, Dalian City (China). State Key Lab. of Structural Analysis for Industrial Equipment; Liang, Songxin; Li, Yawei [Dalian Univ. of Technology, Dalian City (China). School of Mathematical Sciences; Jeffrey, David J. [Univ. of Western Ontario, London (Canada). Dept. of Applied Mathematics

    2017-06-01

    Nonlinear boundary value problems arise frequently in physical and mechanical sciences. An effective analytic approach with two parameters is first proposed for solving nonlinear boundary value problems. It is demonstrated that solutions given by the two-parameter method are more accurate than solutions given by the Adomian decomposition method (ADM). It is further demonstrated that solutions given by the ADM can also be recovered from the solutions given by the two-parameter method. The effectiveness of this method is demonstrated by solving some nonlinear boundary value problems modeling beam-type nano-electromechanical systems.

  11. A memory type boundary stabilization of a mildly damped wave equation

    Directory of Open Access Journals (Sweden)

    Mokhtar Kirane

    1999-01-01

    Full Text Available We consider the wave equation with a mild internal dissipation. It is proved that any small dissipation inside the domain is sufficient to uniformly stabilize the solution of this equation by means of a nonlinear feedback of memory type acting on a part of the boundary. This is established without any restriction on the space dimension and without geometrical conditions on the domain or its boundary.

  12. A new type of shooting method for nonlinear boundary value problems

    Directory of Open Access Journals (Sweden)

    Muhammad Ahsan

    2013-12-01

    Full Text Available In this article we introduce a new type of iterative method for initial value problems (IVPs. We enhance this method by using shooting techniques and interpolation for the boundary value problems. Our method is more accurate and applicable than built in methods used in different software packages. We solved several examples for initial value problems and linear and non-linear boundary value problems and compared results to those obtained using MATLAB.

  13. Application of the perturbation iteration method to boundary layer type problems.

    Science.gov (United States)

    Pakdemirli, Mehmet

    2016-01-01

    The recently developed perturbation iteration method is applied to boundary layer type singular problems for the first time. As a preliminary work on the topic, the simplest algorithm of PIA(1,1) is employed in the calculations. Linear and nonlinear problems are solved to outline the basic ideas of the new solution technique. The inner and outer solutions are determined with the iteration algorithm and matched to construct a composite expansion valid within all parts of the domain. The solutions are contrasted with the available exact or numerical solutions. It is shown that the perturbation-iteration algorithm can be effectively used for solving boundary layer type problems.

  14. Subgrain Rotation Behavior in Sn3.0Ag0.5Cu-Sn37Pb Solder Joints During Thermal Shock

    Science.gov (United States)

    Han, Jing; Tan, Shihai; Guo, Fu

    2018-01-01

    Ball grid array (BGA) samples were soldered on a printed circuit board with Sn37Pb solder paste to investigate the recrystallization induced by subgrain rotation during thermal shock. The composition of the solder balls was Sn3.0Ag0.5Cu-Sn37Pb, which comprised mixed solder joints. The BGA component was cross-sectioned before thermal shock. The microstructure and grain orientations were obtained by a scanning electron microscope equipped with an electron back-scattered diffraction system. Two mixed solder joints at corners of the BGA component were selected as the subjects. The results showed that recrystallization occurred at the corner of the solder joints after 200 thermal shock cycles. The recrystallized subgrains had various new grain orientations. The newly generated grain orientations were closely related to the initial grain orientations, which indicated that different subgrain rotation behaviors could occur in one mixed solder joint with the same initial grain orientation. When the misorientation angles were very small, the rotation axes were about Sn [100], [010] and [001], as shown by analyzing the misorientation angles and subgrain rotation axes, while the subgrain rotation behavior with large misorientation angles in the solder joints was much more complicated. As Pb was contained in the solder joints and the stress was concentrated on the corner of the mixed solder joints, concaves and cracks were formed. When the adjacent recrystallized subgrains were separated, and the process of the continuous recrystallization was limited.

  15. Highly mobile type II twin boundary in Ni-Mn-Ga five-layered martensite

    Energy Technology Data Exchange (ETDEWEB)

    Sozinov, A.; Lanska, N.; Soroka, A. [AdaptaMat Ltd., Yrityspiha 5, Helsinki FIN-00390 (Finland); Straka, L. [School of Science and Technology, Laboratory of Engineering Materials, Aalto University, PL 14200, FIN-00076 AALTO (Finland)

    2011-09-19

    Twin relationships and stress-induced reorientation were studied in Ni{sub 2}Mn{sub 1.14}Ga{sub 0.86} single crystal with five-layered modulated martensite crystal structure. Very low twinning stress of about 0.1 MPa was found for twin boundaries which deviated a few degrees from the (011) crystallographic plane. However, twin boundaries oriented exactly parallel to the (011) plane exhibited considerably higher level of twinning stress, above 1 MPa. X-ray diffraction experiments and calculations based on approximation of the martensite crystal lattice as a tetragonal lattice with a slight monoclinic distortion identified the two different kinds of twin interfaces as type II and type I twin boundaries.

  16. The Interaction between Particles and Low Angle Boundaries during Recovering of Aluminium-Alumina Alloys

    DEFF Research Database (Denmark)

    Jones, A.R.; Hansen, Niels

    1981-01-01

    Certain quantitative and qualitative aspects both of subgrain growth and of the interaction between particles and low angle grain boundaries during recovery have been investigated in two aluminium alloys containing low volume fractions of small alumina particles. Quantitative data have been...... boundaries during recovery involves effects in addition to those of simple Zener pinning of migrating boundaries. For the current alloys it is found that a determination of the limits to normal subgrain growth in terms of a modified Zener analysis produces an underestimate of the true extent of particle...

  17. Eigenvalues for Iterative Systems of (n,p-Type Fractional Order Boundary Value Problems

    Directory of Open Access Journals (Sweden)

    K. R. Prasad

    2014-04-01

    Full Text Available In this paper, we determine the eigenvalue intervals of λ1, λ2, ..., λn for which the iterative system of (n,p-type fractional order two-point boundary value problem has a positive solution by an application of Guo-Krasnosel’skii fixed point theorem on a cone.

  18. Numerical solution to inverse elliptic problem with Neumann type overdetermination and mixed boundary conditions

    Directory of Open Access Journals (Sweden)

    Charyyar Ashyralyyev

    2015-07-01

    Full Text Available This article studies the numerical solution of inverse problems for the multidimensional elliptic equation with Dirichlet-Neumann boundary conditions and Neumann type overdetermination. We present first and second order accuracy difference schemes. The stability and almost coercive stability inequalities for the solution are obtained. Numerical examples with explanation on the implementation illustrate the theoretical results.

  19. Nonlinear parabolic problems with Neumann-type boundary conditions and L^1-data

    Directory of Open Access Journals (Sweden)

    Abderrahmane El Hachimi

    2007-11-01

    $$ \\frac{\\partial u}{\\partial t}-\\triangle_{p}u+\\alpha(u=f \\quad \\text{in } ]0,\\ T[\\times\\Omega, $$ with Neumann-type boundary conditions and initial data in $L^1$. Our approach is based essentially on the time discretization technique by Euler forward scheme.

  20. BOUNDARY VALUE PROBLEM FOR A LOADED EQUATION ELLIPTIC-HYPERBOLIC TYPE IN A DOUBLY CONNECTED DOMAIN

    Directory of Open Access Journals (Sweden)

    O.Kh. Abdullaev

    2014-06-01

    Full Text Available We study the existence and uniqueness of the solution of one boundary value problem for the loaded elliptic-hyperbolic equation of the second order with two lines of change of type in double-connected domain. Similar results have been received by D.M.Kuryhazov, when investigated domain is one-connected.

  1. (2,2) and (0,4) supersymmetric boundary conditions in 3d N =4 theories and type IIB branes

    Science.gov (United States)

    Chung, Hee-Joong; Okazaki, Tadashi

    2017-10-01

    The half-BPS boundary conditions preserving N =(2 ,2 ) and N =(0 ,4 ) supersymmetry in 3d N =4 supersymmetric gauge theories are examined. The BPS equations admit decomposition of the bulk supermultiplets into specific boundary supermultiplets of preserved supersymmetry. Nahm-like equations arise in the vector multiplet BPS boundary condition preserving N =(0 ,4 ) supersymmetry, and Robin-type boundary conditions appear for the hypermultiplet coupled to the vector multiplet when N =(2 ,2 ) supersymmetry is preserved. The half-BPS boundary conditions are realized in the brane configurations of type IIB string theory.

  2. Effect of boundary conditions on magnetocapacitance effect in a ring-type magnetoelectric structure

    Science.gov (United States)

    Zhang, Juanjuan

    2017-12-01

    By considering the nonlinear magneto-elastic coupling relationships of magnetostrictive materials, an analytical model is proposed. The resonance frequencies can be accurately predicted by this theoretical model, and they are in good agreement with experimental data. Subsequently, the magnetocapacitance effect in a ring-type magnetoelectric (ME) structure with different boundary conditions is investigated, and it is found that various mechanical boundaries, the frequency, the magnetic field, the geometric size, and the interface bonding significantly affect the capacitance of the ME structure. Further, additional resonance frequencies can be predicted by considering appropriate imperfect interface bonding. Finally, the influence of an external force on the capacitance is studied. The result shows that an external force on the boundary changes the capacitance, but has only a weak influence on the resonance frequency.

  3. On the rutile alpha-PbO"2-type phase boundary of TiO"2

    DEFF Research Database (Denmark)

    Olsen, J.S.; Gerward, Leif; Jiang, Jianzhong

    1999-01-01

    The high-pressure, high-temperature phase quilibria of TiO"2 have been studied with special emphasis on the rutile and alpha-PbO"2-type phases. It is found that the phase boundary, when plotted in a pressure-temperature diagram, changes from having a negative to having a positive slope...... with increasing temperature at about 6GPa and 850^oC. For nanophase material, the phase boundary is shifted towards lower pressure. The room-temperature bulk moduli are 210(120)GPa, 258(8)GPa and 290(20)GPa for rutile, the alpha-PbO"2-type phase and the baddeleyite-type phase, respectively....

  4. A Boundary Value Problem with Multivariables Integral Type Condition for Parabolic Equations

    Directory of Open Access Journals (Sweden)

    A. L. Marhoune

    2009-01-01

    Full Text Available We study a boundary value problem with multivariables integral type condition for a class of parabolic equations. We prove the existence, uniqueness, and continuous dependence of the solution upon the data in the functional wieghted Sobolev spaces. Results are obtained by using a functional analysis method based on two-sided a priori estimates and on the density of the range of the linear operator generated by the considered problem.

  5. The Formation of Boundary Clinopyroxenes and Associated Glass Veins in Type B1 CAIs

    Energy Technology Data Exchange (ETDEWEB)

    Paque, J M; Beckett, J R; Ishii, H A; Toppani, A; Burnett, D S; Teslich, N; Dai, Z R; Bradley, J P

    2008-05-18

    We used focused ion beam thin section preparation and scanning transmission electron microscopy (FIB/STEM) to examine the interfacial region between spinel and host melilite for three spinel grains, two from the mantle and one from the core of an Allende type B1 inclusion, and a second pair of spinel grains from a type B1 inclusion from the Leoville carbonaceous chondrite. The compositions of boundary clinopyroxenes decorating spinel surfaces are generally consistent with those of coarser clinopyroxenes from the same region of the inclusion, suggesting little movement of spinels between mantle and core regions after the formation of boundary clinopyroxenes. The host melilite displays no anomalous compositions near the interface, and anorthite or other late-stage minerals are not observed, suggesting that crystallization of residual liquid was not responsible for the formation of boundary clinopyroxenes. Allende spinels display either direct spinel-melilite contact or an intervening boundary clinopyroxene between the two phases. In the core, boundary clinopyroxene is mantled by a thin (1-2 {micro}m thick) layer of normally zoned (X{sub Ak} increasing away from the melilite-clinopyroxene contact) melilite with X{sub Ak} matching that of the host melilite at the melilite-melilite contact. In the mantle, X{sub Ak} near boundary spinels is constant. Spinels in a Leoville type B1 inclusion are more complex with boundary clinopyroxene, as observed in Allende, but also variable amounts of glass ({approx}1 {micro}m width), secondary calcite, perovskite, and an unknown Mg-, Al-, OH-rich and Ca-, Si-poor crystalline phase that may be a layered double hydrate. Glass compositions are consistent to first order with a precursor consisting mostly of Mg-carpholite or sudoite with some aluminous diopside. One possible scenario of formation for the glass veins is that open system alteration of melilite produced a porous, hydrated aggregate of Mg-carpholite or sudoite + aluminous

  6. Comparison of oxygen fugacities of S-type granites across the Archean-Proterozoic boundary

    Science.gov (United States)

    Bucholz, C. E.; Eiler, J. M.; Stolper, E. M.; Breaks, F. B.

    2016-12-01

    We investigate whether changes in atmospheric O2 levels across the Archean-Proterozoic (AP) boundary were translated into the igneous record via partial melting or assimilation of sedimentary rocks with potentially differing oxidation states. To isolate the effects of sediment melting, we studied 5 S-type granites from the Superior Province (2640-2685 Ma) and 19 from the Paleoproterozoic (PP) Trans-Hudson and Wopmay orogenies (1715-1885 Ma), which were derived from sediments deposited at most 100-400 Ma before subsequent burial and partial melting. Published data from sediment melting experiments indicate that at a fixed temperature, the FeT/Mg ratios of partial melts - and therefore also FeT/Mg in biotites in granites formed from such melts - are sensitive to the abundance of Fe-Ti oxides in the residue. Specifically, FeT/Mg melt and biotite ratios are lower when Fe-Ti oxides are modally important in the residue due to the incorporation of a significant amount of bulk sediment Fe in the oxide phase. In turn, Fe-Ti oxide stability is highly sensitive to the Fe oxidation state inherited from the sedimentary source, being favored at high Fe3+/Fe2+ ratios. Analyzed biotite compositions from the Archean S-type granites have higher FeT/Mg ratios than those from the PP (2.7-3.7 v. 1.6-2.3) and therefore likely reflect more reducing conditions. The simplest explanation of our results is that the Archean S-type granites were derived from more reduced metasedimentary sources relative to the PP S-type granites, being richer in Fe2+-bearing minerals (e.g., pyrite or siderite) and poorer in Fe3+-bearing phases (e.g., magnetite or hematite). The variation in Fe oxidation state of S-type granites across the AP boundary could reflect the effect on sediments of the Great Oxygenation Event that roughly coincides with this boundary. Another possibility is that there is more reduced organic carbon in the sources of the Archean versus PP S-type granites; however, existing data

  7. Grain boundary modification to suppress lithium penetration through garnet-type solid electrolyte

    Science.gov (United States)

    Hongahally Basappa, Rajendra; Ito, Tomoko; Morimura, Takao; Bekarevich, Raman; Mitsuishi, Kazutaka; Yamada, Hirotoshi

    2017-09-01

    Garnet-type solid electrolytes are one of key materials to enable practical usage of lithium metal anode for high-energy-density batteries. However, it suffers from lithium growth in pellets on charging, which causes short circuit. In this study, grain boundaries of Li6.5La3Zr1.5Ta0.5O12 (LLZT) pellets are modified with Li2CO3 and LiOH to investigate the influence of the microstructure of grain boundaries on lithium growth and to study the mechanism of the lithium growth. In spite of similar properties (relative density of ca. 96% and total ionic conductivity of 7 × 10-4 S cm-1 at 25 °C), the obtained pellets exhibit different tolerance on the short circuit. The LLZT pellets prepared from LiOH-modified LLZT powders exhibit rather high critical current density of 0.6 mA cm-2, at which short circuit occurs. On the other hand, the LLZT pellets without grain boundary modification short-circuited at 0.15 mA cm-2. Microstructural analyses by means of SEM, STEM and EIS suggest that lithium grows through interconnected open voids, and reveal that surface layers such as Li2CO3 and LiOH are not only plug voids but also facilitate the sintering of LLZT to suppress the lithium growth. The results indicate a strategy towards short-circuit-free lithium metal batteries.

  8. Iterative Method for Solving the Second Boundary Value Problem for Biharmonic-Type Equation

    Directory of Open Access Journals (Sweden)

    Dang Quang A.

    2012-01-01

    Full Text Available Solving boundary value problems (BVPs for the fourth-order differential equations by the reduction of them to BVPs for the second-order equations with the aim to use the achievements for the latter ones attracts attention from many researchers. In this paper, using the technique developed by ourselves in recent works, we construct iterative method for the second BVP for biharmonic-type equation, which describes the deflection of a plate resting on a biparametric elastic foundation. The convergence rate of the method is established. The optimal value of the iterative parameter is found. Several numerical examples confirm the efficiency of the proposed method.

  9. Ulam Type Stability for a Coupled System of Boundary Value Problems of Nonlinear Fractional Differential Equations

    Directory of Open Access Journals (Sweden)

    Aziz Khan

    2017-01-01

    Full Text Available We discuss existence, uniqueness, and Hyers-Ulam stability of solutions for coupled nonlinear fractional order differential equations (FODEs with boundary conditions. Using generalized metric space, we obtain some relaxed conditions for uniqueness of positive solutions for the mentioned problem by using Perov’s fixed point theorem. Moreover, necessary and sufficient conditions are obtained for existence of at least one solution by Leray-Schauder-type fixed point theorem. Further, we also develop some conditions for Hyers-Ulam stability. To demonstrate our main result, we provide a proper example.

  10. An Efficient Spectral Approximation for Solving Several Types of Parabolic PDEs with Nonlocal Boundary Conditions

    Directory of Open Access Journals (Sweden)

    E. Tohidi

    2014-01-01

    Full Text Available The problem of solving several types of one-dimensional parabolic partial differential equations (PDEs subject to the given initial and nonlocal boundary conditions is considered. The main idea is based on direct collocation and transforming the considered PDEs into their associated algebraic equations. After approximating the solution in the Legendre matrix form, we use Legendre operational matrix of differentiation for representing the mentioned algebraic equations clearly. Three numerical illustrations are provided to show the accuracy of the presented scheme. High accurate results with respect to the Bernstein Tau technique and Sinc collocation method confirm this accuracy.

  11. Existence theory for sequential fractional differential equations with anti-periodic type boundary conditions

    Directory of Open Access Journals (Sweden)

    Aqlan Mohammed H.

    2016-01-01

    Full Text Available We develop the existence theory for sequential fractional differential equations involving Liouville-Caputo fractional derivative equipped with anti-periodic type (non-separated and nonlocal integral boundary conditions. Several existence criteria depending on the nonlinearity involved in the problems are presented by means of a variety of tools of the fixed point theory. The applicability of the results is shown with the aid of examples. Our results are not only new in the given configuration but also yield some new special cases for specific choices of parameters involved in the problems.

  12. Direct observation of strain in bulk subgrains and dislocation walls by high angular resolution three-dimensional X-ray diffraction

    DEFF Research Database (Denmark)

    Jakobsen, Bo; Lienert, U.; Almer, J.

    2008-01-01

    associated with the grain, shows a distinct structure consisting of sharp bright peaks superimposed on a cloud of enhanced intensity. The bright peaks (which arise from individual subgrains) are found to be subjected to backward strain (on average) while the fraction of the material giving rise to the cloud...

  13. Oblique derivative problems for generalized Rassias equations of mixed type with several characteristic boundaries

    Directory of Open Access Journals (Sweden)

    Guo Chun Wen

    2009-05-01

    Full Text Available This article concerns the oblique derivative problems for second-order quasilinear degenerate equations of mixed type with several characteristic boundaries, which include the Tricomi problem as a special case. First we formulate the problem and obtain estimates of its solutions, then we show the existence of solutions by the successive iterations and the Leray-Schauder theorem. We use a complex analytic method: elliptic complex functions are used in the elliptic domain, and hyperbolic complex functions in the hyperbolic domain, such that second-order equations of mixed type with degenerate curve are reduced to the first order mixed complex equations with singular coefficients. An application of the complex analytic method, solves (1.1 below with $m=n=1$, $a=b=0$, which was posed as an open problem by Rassias.

  14. Free Vibration Analysis of a Rectangular Plate with Kelvin Type Boundary Conditions

    Directory of Open Access Journals (Sweden)

    R. Kırışık

    2007-01-01

    Full Text Available The transverse vibrations of a rectangular plate with the Kelvin type boundary conditions at four corners are investigated. The plate is modeled as being attached to four lumped spring-damper systems at the corners. An analytical procedure is proposed based on the modal analysis. The completely free case of the plate is first studied. The expressions for the eigenfrequencies and eigenfunctions of the plate are obtained by utilizing the separation of variables. Then, the case in which the stiffness and the viscous damping as external forces acting at the corners of the plate is studied. Following the modal analysis procedure, the general solution for the equation of motion of the rectangular plate is derived. Some numerical results are presented.

  15. The Second-Order Shape Derivative of Kohn–Vogelius-Type Cost Functional Using the Boundary Differentiation Approach

    OpenAIRE

    Bacani, Jerico B.; Gunther Peichl

    2014-01-01

    A shape optimization method is used to study the exterior Bernoulli free boundaryproblem. We minimize the Kohn–Vogelius-type cost functional over a class of admissibledomains subject to two boundary value problems. The first-order shape derivative of the costfunctional is recalled and its second-order shape derivative for general domains is computedvia the boundary differentiation scheme. Additionally, the second-order shape derivative ofJ at the solution of the Bernoulli problem is computed ...

  16. Existence and Analytic Approximation of Solutions of Duffing Type Nonlinear Integro-Differential Equation with Integral Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Alsaedi Ahmed

    2009-01-01

    Full Text Available A generalized quasilinearization technique is developed to obtain a sequence of approximate solutions converging monotonically and quadratically to a unique solution of a boundary value problem involving Duffing type nonlinear integro-differential equation with integral boundary conditions. The convergence of order for the sequence of iterates is also established. It is found that the work presented in this paper not only produces new results but also yields several old results in certain limits.

  17. Numerical simulation of 'X-wing' type biplane flapping wings in 3D using the Immersed Boundary Method (IBM)

    NARCIS (Netherlands)

    Tay, W.B.; Van Oudheusden, B.W.; Bijl, H.

    2013-01-01

    The numerical simulation of a “X-wing” type biplane flapping wings, has been performed in 3D using the Immersed Boundary Method (IBM). This “X-wing” type flapping configuration draws its inspiration from Delfly [1], a family of ornithopters developed by the Delft University of Technology, as shown

  18. Effects of thermal aging on the microstructure of Type-II boundaries in dissimilar metal weld joints

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Seung Chang; Choi, Kyoung Joon [School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), 100 Banyeon-ri, Eonyang-eup, Ulju-gun, Ulsan 689-798 (Korea, Republic of); Bahn, Chi Bum [School of Mechanical Engineering, Pusan National University, 63-gil, Geumjeong-Gu, Pusan 609-735 (Korea, Republic of); Kim, Si Hoon; Kim, Ju Young [School of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), 100 Banyeon-ri, Eonyang-eup, Ulju-gun, Ulsan 689-798 (Korea, Republic of); Kim, Ji Hyun, E-mail: kimjh@unist.ac.kr [School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), 100 Banyeon-ri, Eonyang-eup, Ulju-gun, Ulsan 689-798 (Korea, Republic of)

    2015-04-15

    In order to investigate the effects of long-term thermal aging on the microstructural evolution of Type-II boundary regions in the weld metal of Alloy 152, a representative dissimilar metal weld was fabricated from Alloy 690, Alloy 152, and A533 Gr.B. This mock-up was thermally aged at 450 °C to accelerate the effects of thermal aging in a nuclear power plant operation condition (320 °C). The microstructure of the Type-II boundary region of the weld root, which is parallel to and within 100 μm of the fusion boundary and known to be more susceptible to material degradation, was then characterized after different aging times using a scanning electron microscope equipped with an energy dispersive X-ray spectroscope for micro-compositional analysis, electron backscattered diffraction detector for grain and grain boundary orientation analysis, and a nanoindenter for measurement of mechanical properties. Through this, it was found that a steep compositional gradient and high grain average misorientation is created in the narrow zone between the Type-II and fusion boundaries, while the concentration of chromium and number of low-angle grain boundaries increases with aging time. A high average hardness was also observed in the same region of the dissimilar metal welds, with hardness peaking with thermal aging simulating an operational time of 15 years.

  19. Effects of thermal aging on the microstructure of Type-II boundaries in dissimilar metal weld joints

    Science.gov (United States)

    Yoo, Seung Chang; Choi, Kyoung Joon; Bahn, Chi Bum; Kim, Si Hoon; Kim, Ju Young; Kim, Ji Hyun

    2015-04-01

    In order to investigate the effects of long-term thermal aging on the microstructural evolution of Type-II boundary regions in the weld metal of Alloy 152, a representative dissimilar metal weld was fabricated from Alloy 690, Alloy 152, and A533 Gr.B. This mock-up was thermally aged at 450 °C to accelerate the effects of thermal aging in a nuclear power plant operation condition (320 °C). The microstructure of the Type-II boundary region of the weld root, which is parallel to and within 100 μm of the fusion boundary and known to be more susceptible to material degradation, was then characterized after different aging times using a scanning electron microscope equipped with an energy dispersive X-ray spectroscope for micro-compositional analysis, electron backscattered diffraction detector for grain and grain boundary orientation analysis, and a nanoindenter for measurement of mechanical properties. Through this, it was found that a steep compositional gradient and high grain average misorientation is created in the narrow zone between the Type-II and fusion boundaries, while the concentration of chromium and number of low-angle grain boundaries increases with aging time. A high average hardness was also observed in the same region of the dissimilar metal welds, with hardness peaking with thermal aging simulating an operational time of 15 years.

  20. X-Ray and Neutron Diffraction Measurements of Dislocation Density and Subgrain Size in a Friction-Stir-Welded Aluminum Alloy

    Science.gov (United States)

    Woo, Wanchuck; Ungár, Tamás; Feng, Zhili; Kenik, Edward; Clausen, Bjørn

    2010-05-01

    The dislocation density and subgrain size were determined in the base material and friction-stir welds of 6061-T6 aluminum alloy. High-resolution X-ray diffraction measurement was performed in the base material. The result of the line profile analysis of the X-ray diffraction peak shows that the dislocation density is about 4.5 × 1014 m-2 and the subgrain size is about 200 nm. Meanwhile, neutron diffraction measurements have been performed to observe the diffraction peaks during friction-stir welding (FSW). The deep penetration capability of the neutron enables us to measure the peaks from the midplane of the Al plate underneath the tool shoulder of the friction-stir welds. The peak broadening analysis result using the Williamson-Hall method shows the dislocation density of about 3.2 × 1015 m-2 and subgrain size of about 160 nm. The significant increase of the dislocation density is likely due to the severe plastic deformation during FSW. This study provides an insight into understanding the transient behavior of the microstructure under severe thermomechanical deformation.

  1. Two generalized Lyapunov-type inequalities for a fractional p-Laplacian equation with fractional boundary conditions.

    Science.gov (United States)

    Liu, Yang; Xie, Dapeng; Yang, Dandan; Bai, Chuanzhi

    2017-01-01

    In this paper, we investigate the existence of positive solutions for the boundary value problem of nonlinear fractional differential equation with mixed fractional derivatives and p-Laplacian operator. Then we establish two smart generalizations of Lyapunov-type inequalities. Some applications are given to demonstrate the effectiveness of the new results.

  2. Classical solutions for discrete potential boundary value problems with generalized Leray-Lions type operator and variable exponent

    Directory of Open Access Journals (Sweden)

    Bila Adolphe Kyelem

    2017-04-01

    Full Text Available In this article, we prove the existence of solutions for some discrete nonlinear difference equations subjected to a potential boundary type condition. We use a variational technique that relies on Szulkin's critical point theory, which ensures the existence of solutions by ground state and mountain pass methods.

  3. A Semilinear Wave Equation with a Boundary Condition of Many-Point Type: Global Existence and Stability of Weak Solutions

    Directory of Open Access Journals (Sweden)

    Giai Giang Vo

    2015-01-01

    Full Text Available This paper is devoted to the study of a wave equation with a boundary condition of many-point type. The existence of weak solutions is proved by using the Galerkin method. Also, the uniqueness and the stability of solutions are established.

  4. Cryogenic EBSD on ice: preserving a stable surface in a low pressure SEM

    NARCIS (Netherlands)

    Weikusat, I.; Winter, D.A.M. de; Pennock, G.M.; Hayles, M.; Schneijdenberg, C.T.W.M.; Drury, M.R.

    2011-01-01

    Naturally deformed ice contains subgrains with characteristic geometries that have recently been identified in etched surfaces using high-resolution light microscopy (LM). The probable slip systems responsible for these subgrain boundary types can be determined using electron backscattered

  5. New Modified Adomian Decomposition Recursion Schemes for Solving Certain Types of Nonlinear Fractional Two-Point Boundary Value Problems

    Directory of Open Access Journals (Sweden)

    Sekson Sirisubtawee

    2017-01-01

    Full Text Available We apply new modified recursion schemes obtained by the Adomian decomposition method (ADM to analytically solve specific types of two-point boundary value problems for nonlinear fractional order ordinary and partial differential equations. The new modified recursion schemes, which sometimes utilize the technique of Duan’s convergence parameter, are derived using the Duan-Rach modified ADM. The Duan-Rach modified ADM employs all of the given boundary conditions to compute the remaining unknown constants of integration, which are then embedded in the integral solution form before constructing recursion schemes for the solution components. New modified recursion schemes obtained by the method are generated in order to analytically solve nonlinear fractional order boundary value problems with a variety of two-point boundary conditions such as Robin and separated boundary conditions. Some numerical examples of such problems are demonstrated graphically. In addition, the maximal errors (MEn or the error remainder functions (ERn(x of each problem are calculated.

  6. Semilinear Evolution Problems with Ventcel-Type Conditions on Fractal Boundaries

    Directory of Open Access Journals (Sweden)

    Maria Rosaria Lancia

    2014-01-01

    Full Text Available A semilinear parabolic transmission problem with Ventcel's boundary conditions on a fractal interface S or the corresponding prefractal interface Sh is studied. Regularity results for the solution in both cases are proved. The asymptotic behaviour of the solutions of the approximating problems to the solution of limit fractal problem is analyzed.

  7. On the First Boundary Value Problem for Hypoelliptic Evolution Equations: Perron-Wiener Solutions and Cone-Type Criteria

    Directory of Open Access Journals (Sweden)

    Alessia E. Kogoj

    2016-12-01

    Full Text Available For every bounded open set Ω in RN+1, we study the first boundary problem for a wide class of hypoelliptic evolution operators. The operators are assumed to be endowed with a well behaved global fundamental solution that allows us to construct a generalized solution in the sense of Perron-Wiener of the Dirichlet problem. Then, we give a criterion of regularity for boundary points in terms of the behavior, close to the point, of the fundamental solution of the involved operator. We deduce exterior conetype criteria for operators of Kolmogorov-Fokker-Planck-type, for the heat operators and more general evolution invariant operators on Lie groups. Our criteria extend and generalize the classical parabolic-cone condition for the classical heat operator due to Effros and Kazdan. The results presented are contained in [K16].

  8. Dubious types and boundary disputes : contested understandings of concepts of discrimination

    OpenAIRE

    Wrench, John

    2016-01-01

    A prevailing notion of racial/ethnic discrimination is that it is rooted in racism and ethnic prejudice. In fact there are many 'types' of racial/ethnic discrimination, and direct racist discrimination is only one of them. However, whilst direct racist discrimination is perhaps the easiest type to understand, some of the other types are contested in their meaning and used inconsistently in the academic literature. The paper begins by listing the types of discrimination related to the area of ...

  9. Characterisation of net type thermal insulators at 1.8 K low boundary temperature

    CERN Document Server

    Peón-Hernández, G; Szeless, Balázs

    1997-01-01

    The Large Hadron Collider's superconducting magnets are cooled by superfluid helium at 1.8 K and housed in cryostats that minimise the heat inleak to this temperature level by extracting heat at 70 and 5 K. In the first generation of prototype cryostats, the radiative heat to the 1.8 K temperature level accounted for 70 % of the total heat inleak. An alternative to enhance the cryostat thermal performance incorporates a thermalised radiation screen at 5 K. In order to avoid contact between the 5 K radiation screen and the cold mass, insulators are placed between both surfaces. Sets of commercial fibre glass nets are insulator candidates to minimise the heat inleak caused by a accidental contact between the two temperature levels. A model to estimate their performance is presented. A set-up to thermally characterise them has been designed and is also described in the paper. Finally, results as a function of the number of the spacer nets, the boundary temperatures and the compressive force in the spacer are pre...

  10. On grain boundary facetting under stress during high temperature deformation of Al and Al-Ga alloys

    Energy Technology Data Exchange (ETDEWEB)

    Weygand, D.; Doisneau-Cottignies, B.; Brechet, Y. [Domaine Univ. de Grenoble, St. Martin d`Heres (France). LTPCM; Blandin, J.J. [GPMM, Domaine Universitaire de Grenoble, 38402 St. Martin d`Heres (France)

    1997-08-30

    Aluminuim of high purity and aluminium with 50 ppm gallium were deformed under various strain rates and temperatures in order to investigate the possible influence of liquid like grain boundaries on grain boundary sliding and macroscopic deformation behaviour. Under all conditions, serrated grain boundaries were observed to develop during the tensile test. Those serrated structures were correlated to the development of subgrains observed by optical metallography and transmission electron microscopy. In the absence of an applied stress, further annealing lead to disappearing of the serrated grain boundaries when the annealing temperature was higher than the tensile test temperature under which the serrations were developed. (orig.) 9 refs.

  11. Boundary Value Problems with Integral Gluing Conditions for Fractional-Order Mixed-Type Equation

    Directory of Open Access Journals (Sweden)

    A. S. Berdyshev

    2011-01-01

    Full Text Available Analogs of the Tricomi and the Gellerstedt problems with integral gluing conditions for mixed parabolic-hyperbolic equation with parameter have been considered. The considered mixed-type equation consists of fractional diffusion and telegraph equation. The Tricomi problem is equivalently reduced to the second-kind Volterra integral equation, which is uniquely solvable. The uniqueness of the Gellerstedt problem is proven by energy integrals' method and the existence by reducing it to the ordinary differential equations. The method of Green functions and properties of integral-differential operators have been used.

  12. Development of a boundary-layer-type solver based on simultaneous iteration technique for axisymmetric separated flows

    Science.gov (United States)

    Halim, A. A. M.

    A boundary-layer-type solver is developed for the numerical solution of axisymmetric separated flows. A new fully implicit coupling scheme for the viscous and inviscid regions is demonstrated. This fully implicit coupling technique is similar to the work of Carter, Veldman, and an extension of an earlier work of Halim and Hafez. A comparison is made for the convergence rate using this new fully implicit coupling technique and the semiimplicit coupling of Halim and Hafez. Numerical results using the fully implicit coupling are obtained for laminar incompressible separated flows, including a boattail and a series of trough geometries. Also, the near-wake flow problem is considered using the present formulation. A clear conclusion of this investigation is that the present scheme using the fully implicit coupling method converges at a faster rate than the semiimplicit coupling and the partially parabolized Navier-Stokes (PPNS) procedures.

  13. Existence of solutions for Riemann-Liouvillle type coupled systems of fractional integro-differential equations and boundary conditions

    Directory of Open Access Journals (Sweden)

    Ahmed Alsaedi

    2016-08-01

    Full Text Available In this article, we study a boundary value problem of coupled systems of nonlinear Riemann-Liouvillle fractional integro-differential equations supplemented with nonlocal Riemann-Liouvillle fractional integro-differential boundary conditions. Our results rely on some standard tools of the fixed point theory. An illustrative example is also discussed.

  14. Anti-phase boundaries and magnetic domain structures in Ni{sub 2}MnGa-type Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Venkateswaran, S.P. [Department of Materials Science and Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Nuhfer, N.T. [Department of Materials Science and Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); De Graef, M. [Department of Materials Science and Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States)]. E-mail: degraef@cmu.edu

    2007-05-15

    The microstructure and magnetic domain structure of austenitic Heusler Ni{sub 2}MnGa are investigated as a function of heat treatment to study the interplay of anti-phase boundaries and magnetic domain walls. Conventional electron microscopy observations on arc-melted polycrystalline samples show that anti-phase boundaries in this system are invisible for standard two-beam imaging conditions, due to the large extinction distance of the Heusler superlattice reflections. Lorentz Fresnel and Foucault observations on quenched samples reveal a wavy magnetic domain morphology, reminiscent of curved anti-phase boundaries. A close inspection of the domain images indicates that the anti-phase boundaries have a magnetization state different from that of the matrix. Fresnel image simulations for a simple magnetization model are in good agreement with the observations. Magnetic coercivity measurements show a decrease in coercivity with annealing, which correlates with the microscopy observations of reduced anti-phase boundary density for annealed samples.

  15. Microstructure and crystallographic preferred orientation of polycrystalline microgarnet aggregates developed during progressive creep, recovery, and grain boundary sliding

    Science.gov (United States)

    Massey, M.A.; Prior, D.J.; Moecher, D.P.

    2011-01-01

    Optical microscopy, electron probe microanalysis, and electron backscatter diffraction methods have been used to examine a broad range of garnet microstructures within a high strain zone that marks the western margin of a major transpression zone in the southern New England Appalachians. Garnet accommodated variable states of finite strain, expressed as low strain porphyroclasts (Type 1), high strain polycrystalline aggregates (Type 2), and transitional morphologies (Type 3) that range between these end members. Type 1 behaved as rigid porphyroclasts and is characterized by four concentric Ca growth zones. Type 2 help define foliation and lineation, are characterized by three Ca zones, and possess a consistent bulk crystallographic preferred orientation of (100) symmetrical to the tectonic fabric. Type 3 show variable degrees of porphyroclast associated with aggregate, where porphyroclasts display complex compositional zoning that corresponds to lattice distortion, low-angle boundaries, and subgrains, and aggregate CPO mimics porphyroclast orientation. All aggregates accommodated a significant proportion of greenschist facies deformation through grain boundary sliding, grain rotation and impingement, and pressure solution, which lead to a cohesive behavior and overall strain hardening of the aggregates. The characteristic CPO could not have been developed in this manner, and was the result of an older phase of partitioned amphibolite facies dislocation creep, recovery including chemical segregation, and recrystallization of porphyroclasts. This study demonstrates the significance of strain accommodation within garnet and its affect on composition under a range of PT conditions, and emphasizes the importance of utilizing EBSD methods with studies that rely upon a sound understanding of garnet. ?? 2010 Elsevier Ltd.

  16. Numerical simulation of X-wing type biplane flapping wings in 3D using the immersed boundary method.

    Science.gov (United States)

    Tay, W B; van Oudheusden, B W; Bijl, H

    2014-09-01

    The numerical simulation of an insect-sized 'X-wing' type biplane flapping wing configuration is performed in 3D using an immersed boundary method solver at Reynolds numbers equal to 1000 (1 k) and 5 k, based on the wing's root chord length. This X-wing type flapping configuration draws its inspiration from Delfly, a bio-inspired ornithopter MAV which has two pairs of wings flapping in anti-phase in a biplane configuration. The objective of the present investigation is to assess the aerodynamic performance when the original Delfly flapping wing micro-aerial vehicle (FMAV) is reduced to the size of an insect. Results show that the X-wing configuration gives more than twice the average thrust compared with only flapping the upper pair of wings of the X-wing. However, the X-wing's average thrust is only 40% that of the upper wing flapping at twice the stroke angle. Despite this, the increased stability which results from the smaller lift and moment variation of the X-wing configuration makes it more suited for sharp image capture and recognition. These advantages make the X-wing configuration an attractive alternative design for insect-sized FMAVS compared to the single wing configuration. In the Reynolds number comparison, the vorticity iso-surface plot at a Reynolds number of 5 k revealed smaller, finer vortical structures compared to the simulation at 1 k, due to vortices' breakup. In comparison, the force output difference is much smaller between Re = 1 k and 5 k. Increasing the body inclination angle generates a uniform leading edge vortex instead of a conical one along the wingspan, giving higher lift. Understanding the force variation as the body inclination angle increases will allow FMAV designers to optimize the thrust and lift ratio for higher efficiency under different operational requirements. Lastly, increasing the spanwise flexibility of the wings increases the thrust slightly but decreases the efficiency. The thrust result is similar to one of the

  17. Non-axisymmetric vibrations of a transversely isotropic piezoelectric cylinder with different types of electric boundary conditions

    CSIR Research Space (South Africa)

    Shatalov, MY

    2007-04-01

    Full Text Available . The dispersion curves are plotted for propagating waves for non-axisymmetric vibrations of the cylinder. It is shown that the dispersion curves are sensitive to the form of electric boundary conditions...

  18. Boundary problems for mixed parabolic-hyperbolic equations with two lines of changing type and fractional derivative

    Directory of Open Access Journals (Sweden)

    Bakhtiyor Kadirkulov

    2014-02-01

    Full Text Available In this article, we study a boundary value problem for a parabolic-hyperbolic equation with Caputo fractional derivative. Under certain conditions, we prove its unique solvability using methods of integral equations and Green's functions.

  19. Numerical Analysis of Boundary Value Problem of Elliptic Type by Means Penalty and the Finite Difference and Its Application to Free Boundary Problem.

    Science.gov (United States)

    1983-07-01

    type of (1.11) was successfully studied by Murat-Simon (1977), Chesnais (1975), Pironneau (.1976) and Dervieux (1981). The characteristic of our method...1959). Chesnais , D., On the existence of a solution in a domain identification problem, J. of Math. Anal. and Appl., Vol. 52, No. 2 (1975). Ciarlet, Ph

  20. STATEMENT AND RESEARCH METHOD SOME BOUNDARY VALUE PROBLEMS FOR A CLASS OF FOURTH ORDER PARABOLIC-HYPERBOLIC TYPE

    Directory of Open Access Journals (Sweden)

    M. Mamajonov

    2014-06-01

    Full Text Available This paper studies the methods of investigation of some boundary value problems for a class of parabolic-hyperbolic equations of the third order in the hexagonal concave areas that take advantage of the study of problems of mathematical physics in the magistracy.

  1. General characteristics of quartz arenite types and their role in the recognition of sequence stratigraphic boundaries in ancient coastal and near shore sediments. A case study from Egypt and Saudi Arabia

    Science.gov (United States)

    Khalifa, M. A.

    2017-06-01

    Quartz arenites are useful in the recognition of depositional sequences and cycle boundaries in ancient coastal and near shore facies. In this study two types of quartz arenite are recognized: 1) depositional quartz arenite (calcareous, dolomitic, ferruginous and kaolinitic quartz arenites), and 2) diagenetic quartz arenite (orthoquartzite, siliceous quartz arenite, compact quartz arenite, and dedolomitic quartz arenite). Depositional quartz arenite often occurs on the tops (upper boundaries) of the depositional sequences that are bounded by sequence boundaries (with or without evidence of subaerial exposure) or correlative conformity surfaces that mark the change from forced regression to lowstand normal regression. Therefore, depositional quartz arenite can define the upper boundaries of third and fourth-order depositional sequences, cycle bases and tops (boundaries) within lowstand, transgressive and highstand systems tracts. Diagenetic quartz arenite (orthoquartzite, siliceous quartz arenite and dedolomitic quartz arenite) usually occurs at the tops (upper boundaries) of depositional sequences that have subaerial sequence boundary and have been subjected to prolonged subaerial weathering and hence is closely associated with subaerial unconformity sequence boundary surfaces and consequently indicates a sharp drop in sea level. Thus, diagenetic quartz arenite types can be used to recognize the tops (upper boundaries) of first and second-order depositional sequences. Compact quartz arenite that is considered the fourth type of diagenetic quartz arenite consists entirely of packed quartz grains, but lacking cement, occurs at the base of each fining-upward cycle (lower boundaries) in lowstand systems tracts and may define the bases of some different-order depositional sequences.

  2. Subgrain-scale decoupling of Re and 187Os and assessment of laser ablation ICP-MS spot dating in molybdenite

    Science.gov (United States)

    Stein, Holly; Scherstén, Anders; Hannah, Judith; Markey, Richard

    2003-10-01

    Reproducibility of Re-Os molybdenite ages depends on sample size and homogeneity, suggesting that Re and Os are decoupled within individual molybdenite crystals and do not remain spatially linked over time. In order to investigate the Re-Os systematics of molybdenite at the subgrain (micron) scale, we report LA-ICP-MS Re-Os ages for an Archean molybdenite crystal from Aittojärvi, Finland, analyzed in situ in a white aplite matrix. A related Aittojärvi molybdenite (A996D), in the form of a very fine-grained mineral separate, is used as one of our in-house NTIMS standards, and thus its age of 2760 ± 9 Ma is well established. Measurements of ( 187Re + 187Os)/ 185Re on micron scale spots along 200 μm traverses across the crystal yield a wide range of ages demonstrating that, in this case, microsampling of molybdenite does not produce geologically meaningful ages. Experimentation with mineral separations and sample size over a 7-yr period predicted that this would be the outcome. We suggest that 187Os is more likely to be the mobile species, based on its charge and ionic radius, and that 187Os becomes decoupled from parent 187Re with time on the micron and larger scale. Incompatible charge and ionic radius for Os ions formed during reduction of molybdenite-forming fluids may explain the widely observed absence of common (initial) Os in molybdenite. Geologically accurate ages for molybdenite can only be obtained for fully homogenized crystals (or crystal aggregates) so that any post-crystallization 187Re- 187Os decoupling is overcome. A growing number of geologically accurate ID-NTIMS 187Re- 187Os ages for homogenized molybdenite suggest that postcrystallization mobility of radiogenic 187Os must be limited to within the molybdenite mineral phase. We suggest that radiogenic 187Os may be stored in micron scale dislocations, kink bands, and delamination cracks produced by deformation, and that the unusual structure and deformation response of molybdenite results in an

  3. Boundary-Layer Transition on Hollow Cylinders in Supersonic Free Flight as Affected by Mach Number and a Screwthread Type of Surface Roughness

    Science.gov (United States)

    James, Carlton S.

    1959-01-01

    The effects of Mach number and surface-roughness variation on boundary-layer transition were studied using fin-stabilized hollow-tube models in free flight. The tests were conducted over the Mach number range from 2.8 to 7 at a nominally constant unit Reynolds number of 3 million per inch, and with heat transfer to the model surface. A screwthread type of distributed two-dimensional roughness was used. Nominal thread heights varied from 100 microinches to 2100 microinches. Transition Reynolds number was found to increase with increasing Mach number at a rate depending simultaneously on Mach number and roughness height. The laminar boundary layer was found to tolerate increasing amounts of roughness as Mach number increased. For a given Mach number an optimum roughness height was found which gave a maximum laminar run greater than was obtained with a smooth surface.

  4. Ground boundaries

    Science.gov (United States)

    Balluffi, R. W.; Bristowe, P. D.

    The present document is a progress report describing the work accomplished on the study of grain boundaries in Ag, Au, Ni, Si, and Ge. Research was focused on the following four major efforts: study of the atomic structure of grain boundaries by means of x-ray diffraction, transmission electron microscopy and computer modeling; grain boundary migration; short-circuit diffusion along grain boundaries; and development of Thin-Film Deposition/Bonding Apparatus for the manufacture of high purity bicrystals.

  5. A fast semi-implicit algorithm for problems of mixed type. [initial-boundary value problems modeled by partial differential equations

    Science.gov (United States)

    Frederickson, P. O.; Wessel, W. R.

    1979-01-01

    Certain physical processes are modeled by partial differential equations which are parabolic over part of the domain and elliptic over the remainder. A family of semi-implicit algorithms which are well suited to initial-boundary value problems of this mixed type is discussed. One important feature of these algorithms is the use of an approximate inverse for the solution of the implicit linear system. A strong error analysis results in an estimate of the total error as a function of approximate inverse error e and time step h.

  6. The effect of bottom boundary condition type on the behavior of adhesive contact of spherical probe on an elastic film

    Science.gov (United States)

    Zhu, X.; Xu, W.

    2017-11-01

    This study presents an investigation on the behavior of adhesive contact between a rigid sphere and an elastic film which is either perfectly bonded (case I) or in frictionless contact (case II) with a rigid substrate. By using linear fracture mechanics, we formulate an convenient semi-analytical approach to develop relations between the applied force, penetration depth and contact radius. Finite element analysis (FEA) is used to verify the relationships. Our results reveal that the interfacial boundary conditions between the film and substrate have distinct effects on the adhesive contact behavior between the sphere and the film. The aim of the present study is to provide an instructive inspiration for controlling adhesion strength of the thin film subject to adhesive contact.

  7. Analytical Study of Microwave Heating of the Coal Layer With Mixed Boundary Conditions of I and III Types

    Directory of Open Access Journals (Sweden)

    Salomatov Vladimir

    2016-01-01

    Full Text Available This work is dedicated to the search for the exact analytical dependences of microwave heating due to absorption of a plane electromagnetic wave by coal layer with asymmetric and non-uniform heat dissipation conditions I and III kind. Some of simplifications have been made, such as one-dimensional problem, uniformity and isotropic coal material, and the constancy of the electrical properties of thermal coal during heating of microwave radiation. This has led to the fact that the Maxwell’s task is solved separately from the Fourier’s task, and a heat source generated in the carbon layer is subject to Bouguer law. For the system of equations of heat transfer has been found a new dependent variable, which is to simplify the search for a final solution. All this has given the possibility of finding rigorous analytical solution of the problem of microwave heating of the coal layer in the presence of asymmetric and inhomogeneous boundary conditions I and III kind.

  8. Ground boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Balluffi, R.W.; Bristowe, P.D.

    1990-01-01

    The present document is a progress report describing the work accomplished on the study of grain boundaries in Ag, Au, Ni, Si, and Ge. Research was focused on the following four major efforts: study of the atomic structure of grain boundaries by means of x-ray diffraction, transmission electron microscopy and computer modeling; grain boundary migration; short-circuit diffusion along grain boundaries; and development of Thin-Film Deposition/Bonding Apparatus for the manufacture of high purity bicrystals. 10 refs., 1 fig.

  9. The putative Notch ligand HyJagged is a transmembrane protein present in all cell types of adult Hydra and upregulated at the boundary between bud and parent.

    Science.gov (United States)

    Prexl, Andrea; Münder, Sandra; Loy, Bernhard; Kremmer, Elisabeth; Tischer, Susanne; Böttger, Angelika

    2011-09-07

    The Notch signalling pathway is conserved in pre-bilaterian animals. In the Cnidarian Hydra it is involved in interstitial stem cell differentiation and in boundary formation during budding. Experimental evidence suggests that in Hydra Notch is activated by presenilin through proteolytic cleavage at the S3 site as in all animals. However, the endogenous ligand for HvNotch has not been described yet. We have cloned a cDNA from Hydra, which encodes a bona-fide Notch ligand with a conserved domain structure similar to that of Jagged-like Notch ligands from other animals. Hyjagged mRNA is undetectable in adult Hydra by in situ hybridisation but is strongly upregulated and easily visible at the border between bud and parent shortly before bud detachment. In contrast, HyJagged protein is found in all cell types of an adult hydra, where it localises to membranes and endosomes. Co-localisation experiments showed that it is present in the same cells as HvNotch, however not always in the same membrane structures. The putative Notch ligand HyJagged is conserved in Cnidarians. Together with HvNotch it may be involved in the formation of the parent-bud boundary in Hydra. Moreover, protein distribution of both, HvNotch receptor and HyJagged indicate a more widespread function for these two transmembrane proteins in the adult hydra, which may be regulated by additional factors, possibly involving endocytic pathways.

  10. The putative Notch ligand HyJagged is a transmembrane protein present in all cell types of adult Hydra and upregulated at the boundary between bud and parent

    Directory of Open Access Journals (Sweden)

    Tischer Susanne

    2011-09-01

    Full Text Available Abstract Background The Notch signalling pathway is conserved in pre-bilaterian animals. In the Cnidarian Hydra it is involved in interstitial stem cell differentiation and in boundary formation during budding. Experimental evidence suggests that in Hydra Notch is activated by presenilin through proteolytic cleavage at the S3 site as in all animals. However, the endogenous ligand for HvNotch has not been described yet. Results We have cloned a cDNA from Hydra, which encodes a bona-fide Notch ligand with a conserved domain structure similar to that of Jagged-like Notch ligands from other animals. Hyjagged mRNA is undetectable in adult Hydra by in situ hybridisation but is strongly upregulated and easily visible at the border between bud and parent shortly before bud detachment. In contrast, HyJagged protein is found in all cell types of an adult hydra, where it localises to membranes and endosomes. Co-localisation experiments showed that it is present in the same cells as HvNotch, however not always in the same membrane structures. Conclusions The putative Notch ligand HyJagged is conserved in Cnidarians. Together with HvNotch it may be involved in the formation of the parent-bud boundary in Hydra. Moreover, protein distribution of both, HvNotch receptor and HyJagged indicate a more widespread function for these two transmembrane proteins in the adult hydra, which may be regulated by additional factors, possibly involving endocytic pathways.

  11. Negotiating boundaries

    DEFF Research Database (Denmark)

    Aarhus, Rikke; Ballegaard, Stinne Aaløkke

    2010-01-01

    to maintain the order of the home when managing disease and adopting new healthcare technology. In our analysis we relate this boundary work to two continuums of visibility-invisibility and integration-segmentation in disease management. We explore five factors that affect the boundary work: objects......To move treatment successfully from the hospital to that of technology assisted self-care at home, it is vital in the design of such technologies to understand the setting in which the health IT should be used. Based on qualitative studies we find that people engage in elaborate boundary work......, activities, places, character of disease, and collaboration. Furthermore, the processes are explored of how boundary objects move between social worlds pushing and shaping boundaries. From this we discuss design implications for future healthcare technologies for the home....

  12. Boundary Spanning

    DEFF Research Database (Denmark)

    Zølner, Mette

    The paper explores how locals span boundaries between corporate and local levels. The aim is to better comprehend potentialities and challenges when MNCs draws on locals’ culture specific knowledge. The study is based on an in-depth, interpretive case study of boundary spanning by local actors...... in the period of post-acquisition when their organization is being integrated into the acquiring MNC. The paper contributes to the literature on boundary spanning in three ways: First, by illustrating that boundary spanning is performed by numerous organizational actors in a variety of positions in MNCs......, inclusively by locals in subsidiaries. Second, by showing that boundary spanning is ‘situated’ in the sense that its result depends on the kind of knowledge to be transmitted and the attitude of the receivers. A third contribution is methodological. The study illustrates that combining bottom-up grounded...

  13. Inverse boundary spectral problems

    CERN Document Server

    Kachalov, Alexander; Lassas, Matti

    2001-01-01

    Inverse boundary problems are a rapidly developing area of applied mathematics with applications throughout physics and the engineering sciences. However, the mathematical theory of inverse problems remains incomplete and needs further development to aid in the solution of many important practical problems.Inverse Boundary Spectral Problems develop a rigorous theory for solving several types of inverse problems exactly. In it, the authors consider the following: ""Can the unknown coefficients of an elliptic partial differential equation be determined from the eigenvalues and the boundary value

  14. Grain boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Balluffi, R.W.; Bristowe, P.D.

    1991-01-01

    The present document is a progress report describing the work accomplished to date during the second year of our four-year grant (February 15, 1990--February 14, 1994) to study grain boundaries. The research was focused on the following three major efforts: Study of the atomic structure of grain boundaries by means of x-ray diffraction, transmission electron microscopy and computer modeling; study of short-circuit diffusion along grain boundaries; and development of a Thin-film Deposition/Bonding Apparatus for the manufacture of high purity bicrystals.

  15. Grain boundaries

    Science.gov (United States)

    Balluffi, R. W.; Bristowe, P. D.

    The present document is a progress report describing the work accomplished to date during the second year of our four-year grant (February 15, 1990 to February 14, 1994) to study grain boundaries. The research was focused on the following three major efforts: study of the atomic structure of grain boundaries by means of x-ray diffraction, transmission electron microscopy and computer modeling; study of short-circuit diffusion along grain boundaries; and development of a Thin-film Deposition/Bonding Apparatus for the manufacture of high purity bicrystals.

  16. Boundary issues and personality disorders.

    Science.gov (United States)

    Gutheil, Thomas G

    2005-03-01

    The author first presents an overview of the basic elements of boundary theory and clarifies the distinction between boundary crossings and boundary violations. The concepts of context dependence, power asymmetry, and fiduciary duty as they relate to boundary problems are also discussed. The intrinsic and extrinsic consequences of boundary problems are reviewed. The extrinsic consequences fall into three major categories: civil lawsuits, complaints to the board of registration, and complaints to professional societies. The author then reviews types of boundary issues that arise in relation to histrionic, dependent, antisocial, and borderline personality disorders. Countertransference issues that arise in working with patients with personality disorders are discussed, as well as cultural differences that may affect the perception of boundary problems. The article ends with a list of risk management principles and recommendations for avoiding boundary problems in the therapeutic relationship.

  17. Blurring the boundaries between ion sources: The application of the RILIS inside a FEBIAD type ion source at ISOLDE

    Energy Technology Data Exchange (ETDEWEB)

    Day Goodacre, T., E-mail: thomas.day.goodacre@cern.ch [CERN, CH-1211 Geneva 23 (Switzerland); School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom); Billowes, J. [School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom); Catherall, R. [CERN, CH-1211 Geneva 23 (Switzerland); Cocolios, T.E. [School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom); Crepieux, B. [CERN, CH-1211 Geneva 23 (Switzerland); Fedorov, D.V. [Petersburg Nuclear Physics Institute, 188350 Gatchina (Russian Federation); Fedosseev, V.N. [CERN, CH-1211 Geneva 23 (Switzerland); Gaffney, L.P. [KU Leuven, Instituut voor Kern- en Stralingsfysica, 3001 Leuven (Belgium); Giles, T.; Gottberg, A.; Lynch, K.M.; Marsh, B.A.; Mendonça, T.M. [CERN, CH-1211 Geneva 23 (Switzerland); Ramos, J.P. [CERN, CH-1211 Geneva 23 (Switzerland); Laboratory of Powder Technology, EPFL, CH-1015 Lausanne (Switzerland); Rossel, R.E. [CERN, CH-1211 Geneva 23 (Switzerland); Institut für Physik, Johannes Gutenberg Universität, D-55099 Mainz (Germany); Faculty of Design, Computer Science and Media, Hochschule RheinMain, 65197 Wiesbaden (Germany); Rothe, S. [CERN, CH-1211 Geneva 23 (Switzerland); Sels, S.; Sotty, C. [KU Leuven, Instituut voor Kern- en Stralingsfysica, 3001 Leuven (Belgium); Stora, T. [CERN, CH-1211 Geneva 23 (Switzerland); Van Beveren, C. [KU Leuven, Instituut voor Kern- en Stralingsfysica, 3001 Leuven (Belgium); and others

    2016-06-01

    For the first time, the laser resonance photo-ionization technique has been applied inside a FEBIAD-type ion source at an ISOL facility. This was achieved by combining the ISOLDE RILIS with the ISOLDE variant of the FEBIAD ion source (the VADIS) in a series of off-line and on-line tests at CERN. The immediate applications of these developments include the coupling of the RILIS with molten targets at ISOLDE and the introduction of two new modes of FEBIAD operation: an element selective RILIS mode and a RILIS + VADIS mode for increased efficiency compared to VADIS mode operation alone. This functionality has been demonstrated off-line for gallium and barium and on-line for mercury and cadmium. Following this work, the RILIS mode of operation was successfully applied on-line for the study of nuclear ground state and isomer properties of mercury isotopes by in-source resonance ionization laser spectroscopy. The results from the first studies of the new operational modes, of what has been termed the Versatile Arc Discharge and Laser Ion Source (VADLIS), are presented and possible directions for future developments are outlined.

  18. Blurring Boundaries

    DEFF Research Database (Denmark)

    Neergaard, Ulla; Nielsen, Ruth

    2010-01-01

    This article builds on the results obtained in the so-called Blurring Boundaries project which was undertaken at the Law Department, Copenhagen Business School, in the period from 2007 to 2009. It looks at the sustainability of the Danish welfare state in an EU law context and on the integration...... of welfare functions into EU law both from an internal market law and a constitutional law perspective. The main problem areas covered by the Blurring Boundaries project were studied in sub-projects on: 1) Internal market law and welfare services; 2) Fundamental rights and non-discrimination law aspects......; and 3) Services of general interest. In the Blurring Boundaries project, three aspects of the European Social Model have been particularly highlighted: the constitutionalisation of the European Social Model, its multi-level legal character, and the clash between market access justice at EU level...

  19. Conformal boundaries of warped products

    DEFF Research Database (Denmark)

    Kokkendorff, Simon Lyngby

    2006-01-01

    In this note we prove a result on how to determine the conformal boundary of a type of warped product of two length spaces in terms of the individual conformal boundaries. In the situation, that we treat, the warping and conformal distortion functions are functions of distance to a base point....... The result is applied to produce examples of CAT(0)-spaces, where the conformal and ideal boundaries differ in interesting ways....

  20. A Priori Estimates of Solution of a Homogeneous Boundary Value Problem for Parabolic Type Equations by the Discontinuous Galerkin Method on Staggered Grids

    Directory of Open Access Journals (Sweden)

    Ruslan V. Zhalnin

    2017-12-01

    Full Text Available Introduction: In this paper, we present a priori error analysis of the solution of a homogeneous boundary value problem for a second-order differential equation by the discontinuous Galerkin method on staggered grids. Materials and Methods: This study is based on the unified hp-version error analysis of local discontinuous Galerkin method proposed by Castillo et al. [Optimal a priori error estimates for the hp-version of the local discontinuous Galerkin method for convection-diffusion problems, 2002]. The purpose of this paper is to present a new approach to the error analysis of the solution of parabolic equations by the discontinuous Galerkin method on staggered grids. Results: We suggest that approximation errors depend on the characteristic size of the cells and the degree of polynomials used in the basis functions. The necessary lemmas are formulated for the problem solution. The complete proof of the lemmas formulated is carried out. We formulated and proved a theorem, in which a priori error estimates are given for solving parabolic equations using the discontinuous Galerkin method on staggered grids Discussion and Conclusions: The obtained results are consistent with similar studies of other authors and complement them. Further work on this topic involves the study of diffusion-type equations of order higher than the first and the production of a posteriori error estimates.

  1. A transfer function type of simplified electrochemical model with modified boundary conditions and Padé approximation for Li-ion battery: Part 2. Modeling and parameter estimation

    Science.gov (United States)

    Yuan, Shifei; Jiang, Lei; Yin, Chengliang; Wu, Hongjie; Zhang, Xi

    2017-06-01

    The electrochemistry-based battery model can provide physics-meaningful knowledge about the lithium-ion battery system with extensive computation burdens. To motivate the development of reduced order battery model, three major contributions have been made throughout this paper: (1) the transfer function type of simplified electrochemical model is proposed to address the current-voltage relationship with Padé approximation method and modified boundary conditions for electrolyte diffusion equations. The model performance has been verified under pulse charge/discharge and dynamic stress test (DST) profiles with the standard derivation less than 0.021 V and the runtime 50 times faster. (2) the parametric relationship between the equivalent circuit model and simplified electrochemical model has been established, which will enhance the comprehension level of two models with more in-depth physical significance and provide new methods for electrochemical model parameter estimation. (3) four simplified electrochemical model parameters: equivalent resistance Req, effective diffusion coefficient in electrolyte phase Deeff, electrolyte phase volume fraction ε and open circuit voltage (OCV), have been identified by the recursive least square (RLS) algorithm with the modified DST profiles under 45, 25 and 0 °C. The simulation results indicate that the proposed model coupled with RLS algorithm can achieve high accuracy for electrochemical parameter identification in dynamic scenarios.

  2. Commercial-scale recycling of NdFeB-type magnets with grain boundary modification yields products with 'designer properties' that exceed those of starting materials.

    Science.gov (United States)

    Zakotnik, M; Tudor, C O

    2015-10-01

    NdFeB-type magnets dominate the market for high performance magnetic materials, yet production of 'virgin' magnets via mining is environmentally, financially and energetically costly. Hence, interest is growing in 'magnet to magnet' recycling schemes that offer the potential for cheaper, more environmentally-friendly solutions to the world's growing appetite for rare-earth based magnetic materials. Unfortunately, previously described recycling processes only partially capitalise on this potential, because the methods described to date are limited to 'laboratory scale' or operate only under ideal conditions and result in products that fail to recapture the coercivity of the starting, scrap materials. Herein, we report a commercial scale process (120 kg batches) that completely recovers the properties of the starting scrap magnets. Indeed, 'grain boundary modification', via careful addition of a proprietary mix of blended elements, produces magnets with 'designer properties' that can exceed those of the starting materials and can be closely tailored to meet a wide variety of end-user applications, including high-coercivity (>2000 kA/m), sintered magnets suitable for motor applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Boundaries and Boundary Marks - Substantive Cultural Heritage of Extensive Importance

    Science.gov (United States)

    Waldhaeusl, P.; Koenig, H.; Mansberger, R.

    2015-08-01

    The Austrian Society for surveying and Geoinformation (ASG) has proposed to submit "Boundaries and Boundary Marks" for the UNESCO World Heritage title. It was time that boundaries, borders and limits of all types as well as ownership rights would find the proper attention in the global public. Landmarks symbolize the real property and the associated rights and obligations, in a figurative sense, the property generally and all legal limits. A democratic state of law is impossible at today's population density without a functioning land administration system with surveying and jurisdiction. As monumental World Heritage representatives of the geodetic artwork "Boundaries and Boundary Marks" are specifically proposed: remaining monuments of the original cadastral geodetic network, the first pan-Austrian surveying headquarters in Vienna, and a specific selection of outstanding boundary monuments. Landmarks are monuments to the boundaries which separate rights and obligations, but also connect the neighbors peacefully after written agreement. "And cursed be he who does not respect the boundaries" you wrote already 3000 years ago. Boundaries and Boundary Marks are a real thing; they all belong to the tangible or material heritage of human history. In this context also the intangible heritage is discussed. This refers to oral tradition and expressions, performing arts; social practices, rituals and festive events; as well as to knowledge and practices handling nature and the universe. "Boundaries and Boundary Marks" do not belong to it, but clearly to the material cultural world heritage. "Boundary and Boundary Marks" is proposed to be listed according to the criteria (ii),(iv),(vi).

  4. Albedo Boundary

    Science.gov (United States)

    2003-01-01

    MGS MOC Release No. MOC2-510, 11 October 2003The sharp, nearly straight line that runs diagonally across the center of this April 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image is an albedo boundary. Albedois a term that refers to reflectance of sunlight. A surface with a low albedo is one that appears dark because it reflects less light than a high albedo (bright) surface. On Mars, albedo boundaries occur between two materials of differing texture, particle size, or composition, or some combination of these three factors. The boundary shown here is remarkable because it is so sharp and straight. This is caused by wind. Most likely, the entire surface was once covered with the lower-albedo (darker) material that is now seen in the upper half of the image. At some later time, wind stripped away this darker material from the surfaces in the lower half of the image. The difference in albedo here might be related to composition, and possibly particle size. This picture is located near the southwest rim of Schiaparelli Basin at 5.5oS, 345.9oW. The picture covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the left.

  5. Multiple positive solutions for (n-1, 1-type semipositone conjugate boundary value problems for coupled systems of nonlinear fractional differential equations

    Directory of Open Access Journals (Sweden)

    Chengjun Yuan

    2011-02-01

    where $\\lambda$ is a parameter, $\\alpha\\in(n-1, n]$ is a real number and $n\\geq 3$, and $\\mathbf{D}_{0+}^\\alpha$ is the Riemann-Liouville's fractional derivative, and $f, g$ are continuous and semipositone. We give properties of Green's function of the boundary value problem, and derive an interval on $\\lambda$ such that for any $\\lambda$ lying in this interval, the semipositone boundary value problem has multiple positive solutions.

  6. Boundary issues

    Science.gov (United States)

    Townsend, Alan R.; Porder, Stephen

    2011-03-01

    What is our point of no return? Caesar proclaimed 'the die is cast' while crossing the Rubicon, but rarely does modern society find so visible a threshold in our continued degradation of ecosystems and the services they provide. Humans have always used their surroundings to make a living— sometimes successfully, sometimes not (Diamond 2005)—and we intuitively know that there are boundaries to our exploitation. But defining these boundaries has been a challenge since Malthus first prophesied that nature would limit the human population (Malthus 1798). In 2009, Rockström and colleagues tried to quantify what the 6.8 billion (and counting) of us could continue to get away with, and what we couldn't (Rockström et al 2009). In selecting ten 'planetary boundaries', the authors contend that a sustainable human enterprise requires treating a number of environmental thresholds as points of no return. They suggest we breach these Rubicons at our own peril, and that we've already crossed three: biodiversity loss, atmospheric CO2, and disruption of the global nitrogen (N) cycle. As they clearly hoped, the very act of setting targets has provoked scientific inquiry about their accuracy, and about the value of hard targets in the first place (Schlesinger 2009). Such debate is a good thing. Despite recent emphasis on the science of human-ecosystem interactions, understanding of our planetary boundaries is still in its infancy, and controversy can speed scientific progress (Engelhardt and Caplan 1987). A few weeks ago in this journal, Carpenter and Bennett (2011) took aim at one of the more controversial boundaries in the Rockström analysis: that for human alteration of the global phosphorus (P) cycle. Rockström's group chose riverine P export as the key indicator, suggesting that humans should not exceed a value that could trigger widespread marine anoxic events—and asserting that we have not yet crossed this threshold. There are defensible reasons for a marine

  7. boundary dissipation

    Directory of Open Access Journals (Sweden)

    Mehmet Camurdan

    1998-01-01

    are coupled by appropriate trace operators. This overall model differs from those previously studied in the literature in that the elastic chamber floor is here more realistically modeled by a hyperbolic Kirchoff equation, rather than by a parabolic Euler-Bernoulli equation with Kelvin-Voight structural damping, as in past literature. Thus, the hyperbolic/parabolic coupled system of past literature is replaced here by a hyperbolic/hyperbolic coupled model. The main result of this paper is a uniform stabilization of the coupled PDE system by a (physically appealing boundary dissipation.

  8. COMPARING THE FLOYD AND IDEAL BOUNDARIES OF A METRIC SPACE

    DEFF Research Database (Denmark)

    Buckley, S.M.; Kokkendorff, Simon Lyngby

    2009-01-01

    We discuss and compare the notions of ideal boundaries, Floyd boundaries and Gromov boundaries of metric spaces. The three types of boundaries at infinity are compared in the general setting of unbounded length spaces as well as in the special cases of CAT(0) and Gromov hyperbolic spaces. Gromov...... boundaries, usually defined only for Gromov hyperbolic spaces, are extended to arbitrary metric spaces....

  9. The Boundary Function Method. Fundamentals

    Science.gov (United States)

    Kot, V. A.

    2017-03-01

    The boundary function method is proposed for solving applied problems of mathematical physics in the region defined by a partial differential equation of the general form involving constant or variable coefficients with a Dirichlet, Neumann, or Robin boundary condition. In this method, the desired function is defined by a power polynomial, and a boundary function represented in the form of the desired function or its derivative at one of the boundary points is introduced. Different sequences of boundary equations have been set up with the use of differential operators. Systems of linear algebraic equations constructed on the basis of these sequences allow one to determine the coefficients of a power polynomial. Constitutive equations have been derived for initial boundary-value problems of all the main types. With these equations, an initial boundary-value problem is transformed into the Cauchy problem for the boundary function. The determination of the boundary function by its derivative with respect to the time coordinate completes the solution of the problem.

  10. Breaking Boundaries

    DEFF Research Database (Denmark)

    produce desperate attempts to maintain old or create new differences. Political and sociological research into these complex processes has been mainly guided by structural and normative concerns. Faced with growing evidence about the instability of world order and domestic social structures alike, policy....... As a fundamental human experience, liminality transmits cultural practices, codes, rituals, and meanings in-between aggregate structures and uncertain outcomes. As a methodological tool it is well placed to overcome disciplinary boundaries, which often direct attention to specific structures or sectors of society....... Its capacity to provide explanatory accounts of seemingly unstructured situations provides an opportunity to link experience-based and culture-oriented approaches not only to contemporary problems but also to undertake comparisons across historical periods. From a perspective of liminality...

  11. Effects of boundary characteristics on resistance to temper embrittlement and segregation behavior of Ni-Cr-Mo low alloy steel

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sang-Gyu; Lee, Ki-Hyoung [Nuclear Materials Research Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Kim, Min-Chul, E-mail: mckim@kaeri.re.kr [Nuclear Materials Research Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Lee, Bong-Sang [Nuclear Materials Research Division, Korea Atomic Energy Research Institute, Daedeok-daero 989-111, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)

    2013-01-20

    SA508 Gr.4N Ni-Cr-Mo low alloy steel has higher strength and fracture toughness than those of commercial SA508 Gr.3 low alloy steel, due to its tempered martensitic microstructure as well as the solid solution effect and its higher contents of Ni and Cr. Hence, several studies have been performed on SA508 Gr.4N for nuclear application. In this study, the effects of microstructure on temper embrittlement and segregation behaviors in Ni-Cr-Mo low alloy steel were evaluated from the viewpoint of grain boundary characteristics. To evaluate the microstructural effect while excluding chemistry effects, the same heat was used but different microstructure samples were prepared by changing the cooling rate after austenitization. The increased volume fraction of martensite reduces the resistance to temper embrittlement, showing an increased transition-temperature shift (TTS) and increased P segregation at prior austenite boundaries. The segregation occurred intensively at prior austenite grain boundaries in tempered martensite, while the segregation occurred simultaneously at both prior austenite boundaries and packet boundaries in tempered bainite. In the EBSD results, most of the packet boundaries in tempered martensite are special boundaries such as N-Ary-Summation 3 coincident site lattice (CSL) boundaries. The differences in P segregation between tempered martensite and tempered bainite are mainly caused by different portions of low energy special boundaries among the sub-grain boundaries. The reduction of temper embrittlement resistance in tempered martensite could be explained by the increased fraction of low energy CSL boundaries, which leads to a concentrated segregation of P at prior austenite grain boundaries.

  12. Frequency of postlicensure registered nurse boundary violations with patients in the state of Ohio: a comparison based on type of prelicensure registered nurse education.

    Science.gov (United States)

    Jones, Jeffrey S; Fitzpatrick, Joyce J; Drake, Virginia K

    2008-12-01

    Nurse-Patient boundary violations remain a problem. Efforts to address the problem through postlicensure education and stronger disciplinary measures are well documented. However, efforts to understand this problem based on prelicensure components are less studied. Using data from The Ohio Board of Nursing from 2002 to 2006, the difference in frequency of incidents of violations between associate degree-prepared registered nurses and baccalaureate degree-prepared registered nurses was studied. A statistically significant difference was found through chi-square analysis: Associate degree-prepared nurses had higher frequency of boundary violations. Further studies on prelicensure curricular influences on registered nurses' postlicensure behavior, particularly in relation to curricular content focused on interpersonal skill development, are recommended.

  13. The steady Navier–Stokes problem with the inhomogeneous Navier-type boundary conditions in a 2D multiply-connected bounded domain

    Czech Academy of Sciences Publication Activity Database

    Neustupa, Jiří

    2015-01-01

    Roč. 35, č. 3 (2015), s. 201-212 ISSN 0174-4747 R&D Projects: GA ČR GA13-00522S Institutional support: RVO:67985840 Keywords : steady Navier-Stokes problem * slip boundary conditions Subject RIV: BA - General Mathematics http://www.degruyter.com/view/j/anly.2015.35.issue-3/anly-2014-1304/anly-2014-1304. xml

  14. Technology for Boundaries

    DEFF Research Database (Denmark)

    Bødker, Susanne; Kristensen, Jannie Friis; Nielsen, Christina

    2003-01-01

    This paper presents a study of an organisation, which is undergoing a process transforming organisational and technological boundaries. In particular, we shall look at three kinds of boundaries: the work to maintain and change the boundary between the organisation and its customers; boundaries.......After analysing the history and the current boundary work, the paper will propose new technological support for boundary work. In particular the paper will suggest means of supporting boundaries when these are productive and for changing boundaries when this seems more appropriate. In total, flexible technologies...... seem a core issue when dealing with technology for boundaries....

  15. Internal microstructure observation of enhanced grain-boundary sliding at room temperature in AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ando, D., E-mail: daisuke.ando.c4@tohoku.ac.jp; Sutou, Y.; Koike, J.

    2016-06-01

    The origin of grain boundary sliding (GBS) is known to be slip-induced due to plastic incompatibility near the grain boundary at room temperature. In this study, the relationship between GBS and crystal orientation was investigated in AZ31 Mg alloy rolled sheets at room temperature. The GBS tendency was determined as related to basal dislocation slip where the GBS boundaries were generally located between the grains with respectively high and low or high and high Schmid factors for basal slip. The results indicate that GBS is attributed to the plastic incompatibility caused by anisotropic basal and prismatic slip. Furthermore, GBS was located in regions with localized deformation near grain boundaries. Cross-sectional focused ion beam/transmission electron microscopy (FIB/TEM) observations of these regions revealed seriately arranged subgrains adjacent to a grain boundary. Therefore, we propose that RT-GBS in AZ31 can be caused by localized crystal rotation due to dynamic recover and recrystallization by stress concentration near the grain boundary but not ordinary GBS.

  16. Boundary cap neural crest stem cells homotopically implanted to the injured dorsal root transitional zone give rise to different types of neurons and glia in adult rodents

    OpenAIRE

    Trolle, Carl; Abrahamsson, Ninnie; König, Niclas; Vasylovska, Svitlana; Kozlova, Elena

    2014-01-01

    The boundary cap is a transient group of neural crest-derived cells located at the presumptive dorsal root transitional zone (DRTZ) when sensory axons enter the spinal cord during development. Later, these cells migrate to dorsal root ganglia and differentiate into subtypes of sensory neurons and glia. After birth when the DRTZ is established, sensory axons are no longer able to enter the spinal cord. Here we explored the fate of mouse bNCSCs implanted to the uninjured DRTZ after dorsal root ...

  17. Dimension of Fractal Basin Boundaries.

    Science.gov (United States)

    Park, Bae-Sig

    In many dynamical systems, multiple attractors coexist for certain parameter ranges. The set of initial conditions that asymptotically approach each attractor is its basin of attraction. These basins can be intertwined on arbitrary small scales. Basin boundary can be either smooth or fractal. Dynamical systems that have fractal basin boundary show "final state sensitivity" of the initial conditions. A measure of this sensitivity (uncertainty exponent alpha) is related to the dimension of the basin boundary d = D - alpha , where D is the dimension of the phase space and d is the dimension of the basin boundary. At metamorphosis values of the parameter, there might happen a conversion from smooth to fractal basin boundary (smooth-fractal metamorphosis) or a conversion from fractal to another fractal basin boundary characteristically different from the previous fractal one (fractal-fractal metamorphosis). The dimension changes continuously with the parameter except at the metamorphosis values where the dimension of the basin boundary jumps discontinuously. We chose the Henon map and the forced damped pendulum to investigate this. Scaling of the basin volumes near the metamorphosis values of the parameter is also being studied for the Henon map. Observations are explained analytically by using low dimensional model map. We look for universal scalings of the dimension of fractal basin boundaries near type I and type III intermittency transitions to chaos. Type I intermittency can occur as the system experiences a saddle-node (tangent) bifurcation and type III intermittency can occur as the system experiences an inverted period doubling bifurcation. At these bifurcations, multiple attractors with fractal basin boundaries can be created. It is found the dimension scales, with the parameter, according to the power law d = d_{o } - k| p - p_{c}| ^{beta} with beta = 1/2, where p is the system parameter, p _{c} is the bifurcation value, k is a scaling constant, and d_{o} is

  18. Solvability of a (p, n-p-type multi-point boundary-value problem for higher-order differential equations

    Directory of Open Access Journals (Sweden)

    Yuji Liu

    2003-12-01

    Full Text Available In this article, we study the differential equation $$ (-1^{n-p} x^{(n}(t=f(t,x(t,x'(t,dots,x^{(n-1}(t, $$ subject to the multi-point boundary conditions $$displaylines{ x^{(i}(0=0 quad hbox{for }i=0,1,dots,p-1,cr x^{(i}(1=0 quad hbox{for }i=p+1,dots,n-1,cr sum_{i=1}^malpha_ix^{(p}(xi_i=0, }$$ where $1le ple n-1$. We establish sufficient conditions for the existence of at least one solution at resonance and another at non-resonance. The emphasis in this paper is that $f$ depends on all higher-order derivatives. Examples are given to illustrate the main results of this article.

  19. Grain boundaries: Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Balluffi, R.W.; Bristowe, P.D.

    1988-02-01

    Quantitative measurements of grain boundary structure factors using x-ray diffraction have been performed on low angle (001) twist boundaries in gold. Also, a computer atomistic simulation program is being implemented to examine the equilibrium properties of a series of boundaries in gold. Simulation of boundaries at room temperature have been performed. Electron microscopy of grain boundary melting in aluminum was also performed. Results indicated an absence of melting. (CBS)

  20. Boundaries of flat compact surfaces

    DEFF Research Database (Denmark)

    Røgen, Peter

    1999-01-01

    type. The number of $3$-singular points (points of zero curvature or if not then of zero torsion) on the boundary of a flat immersed compact surface is greater than or equal to twice the absolute value of the Euler characteristic of the surface. A set of necessary and, in a weakened sense, sufficient...

  1. BUBBLE - an urban boundary layer meteorology project

    DEFF Research Database (Denmark)

    Rotach, M.W.; Vogt, R.; Bernhofer, C.

    2005-01-01

    The Basel urban Boundary Layer Experiment (BUBBLE) was a year-long experimental effort to investigate in detail the boundary layer structure in the City of Basel, Switzerland. At several sites over different surface types (urban, sub-urban and rural reference) towers up to at least twice the main...

  2. Hierarchies of DIFFdifference boundary value problems II ...

    African Journals Online (AJOL)

    This paper provides an illustration of the work done in [14] where a hierarchy of difference boundary value problems was developed. In particular, we studied the effect of applying a Crum-type transformation to a weighted second order difference equation with general -dependent boundary conditions at the end points, ...

  3. THE LINEAR INVERSE PROBLEM FOR THE MIXED TYPE EQUATION OF THE SECOND KIND OF THE SECOND ORDER WITH NONLOCAL BOUNDARY CONDITIONS IN THREE-DIMENSIONAL SPACE

    Directory of Open Access Journals (Sweden)

    Djamalov

    2016-12-01

    Full Text Available In the present work the problems of correctness of a linear inverse problem for the mixed type equation of the second kind of the second order in three-dimensional space are considered. For this problem, the theorems on existence and uniqueness of the solution are proved in certain class by «ε-regularization», Galerkin’s and of successive approximations methods.

  4. Global boundary conditions for the Dirac operator

    CERN Document Server

    Falomir, H A

    1997-01-01

    Ellipticity of boundary value problems is characterized in terms of the Calderon projector. The presence of topological obstructions for the chiral Dirac operator under local boundary conditions in even dimension is discussed. Functional determinants for Dirac operators on manifolds with boundary are considered. The functional determinant for a Dirac operator on a bidimensional disk, in the presence of an Abelian gauge field and subject to global boundary conditions of the type introduced by Atiyah-Patodi-Singer, is evaluated. The relationship with the index theorem is also commented.

  5. State Agency Administrative Boundaries

    Data.gov (United States)

    Kansas Data Access and Support Center — This database comprises 28 State agency boundaries and point of contact. The Kansas Geological Survey collected legal descriptions of the boundaries for various...

  6. Allegheny County Municipal Boundaries

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset demarcates the municipal boundaries in Allegheny County. Data was created to portray the boundaries of the 130 Municipalities in Allegheny County the...

  7. HUD GIS Boundary Files

    Data.gov (United States)

    Department of Housing and Urban Development — The HUD GIS Boundary Files are intended to supplement boundary files available from the U.S. Census Bureau. The files are for community planners interested in...

  8. Political State Boundary (National)

    Data.gov (United States)

    Department of Transportation — State boundaries with political limit - boundaries extending into the ocean (NTAD). The TIGER/Line Files are shapefiles and related database files (.dbf) that are an...

  9. Repeated judgment sampling: Boundaries

    Directory of Open Access Journals (Sweden)

    Johannes Muller-Trede

    2011-06-01

    Full Text Available This paper investigates the boundaries of the recent result that eliciting more than one estimate from the same person and averaging these can lead to accuracy gains in judgment tasks. It first examines its generality, analysing whether the kind of question being asked has an effect on the size of potential gains. Experimental results show that the question type matters. Previous results reporting potential accuracy gains are reproduced for year-estimation questions, and extended to questions about percentage shares. On the other hand, no gains are found for general numerical questions. The second part of the paper tests repeated judgment sampling's practical applicability by asking judges to provide a third and final answer on the basis of their first two estimates. In an experiment, the majority of judges do not consistently average their first two answers. As a result, they do not realise the potential accuracy gains from averaging.

  10. Ångström coefficient as an indicator of the atmospheric aerosol type for a well-mixed atmospheric boundary layer: Part 1: Model development

    Directory of Open Access Journals (Sweden)

    Jolanta Kuśmierczyk-Michulec

    2009-03-01

    Full Text Available The physical and optical properties of an atmospheric aerosol mixture depend on a number of factors. The relative humidity influences the size of hydroscopic particles and the effective radius of an aerosol mixture. In consequence, values of the aerosol extinction, the aerosol optical thickness and the Ångström coefficient are modified. A similar effect is observed when the aerosol composition changes. A higher content of small aerosol particles causes the effective radius of an aerosol mixture to decrease and the Ångström coefficient to increase. Both effects are analysed in this paper. The parameters of the size distribution and the type of components used to represent natural atmospheric aerosol mixtures are based on experimental data. The main components are sea-salts (SSA, anthropogenic salts (WS, e.g. NH4HSO4, NH4NO3, (NH42 SO4, organic carbon (OC and black carbon (BC. The aerosol optical thickness is modelled using the external mixing approach. The influence of relative humidity on the optical and physical properties of the following aerosol mixtures is investigated: (SSA & WS, (SSA & OC, (SSA & BC, (SSA, WS & OC and (WS, OC & BC. It is demonstrated that the Ängström coefficient can be used as a rough indicator of the aerosol type.

  11. Free boundary ballooning mode representation

    Science.gov (United States)

    Zheng, L. J.

    2012-10-01

    A new type of ballooning mode invariance is found in this paper. Application of this invariance is shown to be able to reduce the two-dimensional problem of free boundary high n modes, such as the peeling-ballooning modes, to a one-dimensional problem. Here, n is toroidal mode number. In contrast to the conventional ballooning representation, which requires the translational invariance of the Fourier components of the perturbations, the new invariance reflects that the independent solutions of the high n mode equations are translationally invariant from one radial interval surrounding a single singular surface to the other intervals. The conventional ballooning mode invariance breaks down at the vicinity of plasma edge, since the Fourier components with rational surfaces in vacuum region are completely different from those with rational surfaces in plasma region. But, the new type of invariance remains valid. This overcomes the limitation of the conventional ballooning mode representation for studying free boundary modes.

  12. Characterizations of boundary pluripolar hulls

    NARCIS (Netherlands)

    Djire, I.K.; Wiegerinck, J.

    2016-01-01

    We present some basic properties of the so-called boundary relative extremal function and discuss boundary pluripolar sets and boundary pluripolar hulls. We show that for B-regular domains the boundary pluripolar hull is always trivial on the boundary of the domain and present a “boundary version”

  13. Projective drawings: helping adult survivors of childhood abuse recognize boundaries.

    Science.gov (United States)

    Glaister, J A

    1994-10-01

    1. Boundary issues for adult childhood trauma survivors are complex, problematic, difficult to resolve, and occur on a level of unawareness. 2. Boundary concepts can be found in all types of projective drawings. 3. Projective drawings can facilitate awareness and understanding of boundary problems experienced by adult childhood trauma survivors.

  14. 46 CFR 116.415 - Fire control boundaries.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Fire control boundaries. 116.415 Section 116.415... ARRANGEMENT Fire Protection § 116.415 Fire control boundaries. (a) Type and construction of fire control... Class 0 minutes (iv) Penetrations in B-Class fire control boundaries for electrical cables, pipes...

  15. Navigating Cross-Boundary Connections in Educational Research

    Science.gov (United States)

    Oikonomidoy, Eleni; Wiest, Lynda R.

    2017-01-01

    Drawing on insights from reflective research accounts in the social sciences, this paper attends to the complexities of conducting cross-boundary educational research. Cross-boundary research is defined as any type of inquiry that is conducted across cultural and/or structural boundaries, including but not limited to race, class, gender, language,…

  16. Grain Boundary Complexions

    Science.gov (United States)

    2014-05-01

    deter- mine bulk materials behavior and properties such as superplasticity, creep, fatigue, corrosion , strength and conductivity [2]. Grain boundary...interface (i.e. lattice mismatch accommodated by interface dislocations ), wetting transitions will not occur. A wetting transition is possible in the case...melting only starts around dislocations at low- angle grain boundaries; the grain boundary structure con- sists of isolated liquid pools separated by

  17. Stable Boundary Layer Issues

    OpenAIRE

    Steeneveld, G.J.

    2012-01-01

    Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The development of robust stable boundary layer parameterizations for use in NWP and climate models is hampered by the multiplicity of processes and their unknown interactions. As a result, these models suffer ...

  18. Oxygen boundary crossing probabilities.

    Science.gov (United States)

    Busch, N A; Silver, I A

    1987-01-01

    The probability that an oxygen particle will reach a time dependent boundary is required in oxygen transport studies involving solution methods based on probability considerations. A Volterra integral equation is presented, the solution of which gives directly the boundary crossing probability density function. The boundary crossing probability is the probability that the oxygen particle will reach a boundary within a specified time interval. When the motion of the oxygen particle may be described as strongly Markovian, then the Volterra integral equation can be rewritten as a generalized Abel equation, the solution of which has been widely studied.

  19. Stable Boundary Layer Issues

    NARCIS (Netherlands)

    Steeneveld, G.J.

    2012-01-01

    Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The

  20. Path Integrals on Manifolds with Boundary

    Science.gov (United States)

    Ludewig, Matthias

    2017-09-01

    We give time-slicing path integral formulas for solutions to the heat equation corresponding to a self-adjoint Laplace type operator acting on sections of a vector bundle over a compact Riemannian manifold with boundary. More specifically, we show that such a solution can be approximated by integrals over finite-dimensional path spaces of piecewise geodesics subordinated to increasingly fine partitions of the time interval. We consider a subclass of mixed boundary conditions which includes standard Dirichlet and Neumann boundary conditions.

  1. Helmholtz bright and boundary solitons

    Energy Technology Data Exchange (ETDEWEB)

    Christian, J M [Joule Physics Laboratory, School of Computing, Science and Engineering, Institute for Materials Research, University of Salford, Salford M5 4WT (United Kingdom); McDonald, G S [Joule Physics Laboratory, School of Computing, Science and Engineering, Institute for Materials Research, University of Salford, Salford M5 4WT (United Kingdom); Chamorro-Posada, P [Departmento de TeorIa de la Senal y Comunicaciones e IngenierIa Telematica, Universidad de Valladolid, ETSI Telecomunicacion, Campus Miguel Delibes s/n, 47011 Valladolid (Spain)

    2007-02-16

    We report, for the first time, exact analytical boundary solitons of a generalized cubic-quintic nonlinear Helmholtz (NLH) equation. These solutions have a linked-plateau topology that is distinct from conventional dark soliton solutions; their amplitude and intensity distributions are spatially delocalized and connect regions of finite and zero wave-field disturbances (suggesting also the classification as 'edge solitons'). Extensive numerical simulations compare the stability properties of recently derived Helmholtz bright solitons, for this type of polynomial nonlinearity, to those of the new boundary solitons. The latter are found to possess a remarkable stability characteristic, exhibiting robustness against perturbations that would otherwise lead to the destabilizing of their bright-soliton counterparts.

  2. Stokes equations with penalised slip boundary conditions

    Science.gov (United States)

    Dione, Ibrahima; Tibirna, Cristian; Urquiza, José

    2013-07-01

    We consider the finite-element approximation of Stokes equations with slip boundary conditions imposed with the penalty method. In the case of a smooth curved boundary, our numerical results suggest that curved finite elements, regularised normal vectors or reduced integration techniques can be used to avoid a Babuska's-type paradox and ensure the convergence of finite-element approximations to the exact solution. Convergence orders with these remedies are also compared.

  3. Seeking the boundary of boundary extension.

    Science.gov (United States)

    McDunn, Benjamin A; Siddiqui, Aisha P; Brown, James M

    2014-04-01

    Boundary extension (BE) is a remarkably consistent visual memory error in which participants remember seeing a more wide-angle image of a scene than was actually viewed (Intraub & Richardson, Journal of Experimental Psychology: Learning, Memory, and Cognition 15:179-187, 1989). Multiple stimulus factors are thought to contribute to the occurrence of BE, including object recognition, conceptual knowledge of scenes, and amodal perception at the view boundaries (Intraub, Wiley Interdisciplinary Reviews: Cognitive Science 3:117-127, 2012). In the present study, we used abstract scenes instead of images of the real world, in order to remove expectations based on semantic associations with objects and the schematic context of the view. Close-angle and wide-angle scenes were created using irregular geometric shapes rated by independent observers as lacking any easily recognizable structure. The abstract objects were tested on either a random-dot or a blank background in order to assess the influence of implied continuation of the image beyond its boundaries. The random-dot background conditions had background occlusion cues either present or absent at the image border, in order to test their influence on BE in the absence of high-level information about the scenes. The results indicate that high-level information about objects and schematic context is unnecessary for BE to occur, and that occlusion information at the image boundary also has little influence on BE. Contrary to previous studies, we also found clear BE for all conditions, despite using scenes depicting undetailed objects on a blank white background. The results highlighted the ubiquitous nature of BE and the adaptability of scene perception processes.

  4. Administrative Area Boundaries 2 (State Boundaries), Region 9, 2010, NAVTEQ

    Data.gov (United States)

    U.S. Environmental Protection Agency — NAVTEQ Administrative Area Boundaries 2 (State Boundaries) for Region 9. There are five Administrative Area Boundaries layers (1, 2, 3, 4, 5). These layers contain...

  5. Administrative Area Boundaries 4 (City Boundaries), Region 9, 2010, NAVTEQ

    Data.gov (United States)

    U.S. Environmental Protection Agency — NAVTEQ Administrative Area Boundaries 4 (City Boundaries) for Region 9. There are five Administrative Area Boundaries layers (1, 2, 3, 4, 5). These layers contain...

  6. Beyond the Boundary

    DEFF Research Database (Denmark)

    Gorm Hansen, Birgitte

    2011-01-01

    Whether celebratory or critical, STS research on science-industry relations has focused on the blurring of boundaries and hybridization of codes and practices. However, the vocabulary of boundary and hybrid tends to reify science and industry as separate in the attempt to map their relation...... as the negotiation of a preexisting science-industry boundary. Rather, viability is obtained through a strategy of "circumventing" the science-industry food chain and "sequestering" biotech components within the research center. Symbiosis allows academic scientists to do biology while at the same time demonstrating...

  7. Beyond the Boundary

    DEFF Research Database (Denmark)

    Gorm Hansen, Birgitte

    2012-01-01

    Whether celebratory or critical, STS research on science-industry relations has focused on the blurring of boundaries and hybridization of codes and practices. However, the vocabulary of boundary and hybrid tends to reify science and industry as separate in the attempt to map their relation...... as the negotiation of a preexisting science-industry boundary. Rather, viability is obtained through a strategy of circumventing the science-industry food chain and sequestering biotech components within the research center. Symbiosis allows academic scientists to do biology while at the same time demonstrating...

  8. HUC 8 Boundaries

    Data.gov (United States)

    Kansas Data Access and Support Center — This data set is a digital hydrologic unit boundary that is at the 4-digit, 6-digit, 8-digit, and 11-digit level. The data set was developed by delineating the...

  9. FWS Approved Acquisition Boundaries

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This data layer depicts the external boundaries of lands and waters that are approved for acquisition by the U.S. Fish and Wildlife Service (USFWS) in North America,...

  10. National Forest Boundaries

    Data.gov (United States)

    Minnesota Department of Natural Resources — This theme shows the USFS national forest boundaries in the state. This data was acquired from the GIS coordinators at both the Chippewa National Forest and the...

  11. VT Telephone Exchange Boundaries

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The UtilityTelecom_EXCHANGE represents Vermont Telephone Exchange boundaries as defined by the VT Public Service Board. The original data was...

  12. State Park Statutory Boundaries

    Data.gov (United States)

    Minnesota Department of Natural Resources — Legislative statutory boundaries for sixty six state parks, six state recreation areas, and eight state waysides. These data are derived principally from DNR's...

  13. 500 Cities: City Boundaries

    Data.gov (United States)

    U.S. Department of Health & Human Services — This city boundary shapefile was extracted from Esri Data and Maps for ArcGIS 2014 - U.S. Populated Place Areas. This shapefile can be joined to 500 Cities...

  14. Allegheny County Parcel Boundaries

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset contains parcel boundaries attributed with county block and lot number. Use the Property Information Extractor for more control downloading a filtered...

  15. Watershed Boundary Areas

    Data.gov (United States)

    Department of Homeland Security — This map layer contains hydrologic unit boundaries and codes for the United States, Puerto Rico, and the U.S. Virgin Islands. It was revised for inclusion in the...

  16. NM School District Boundaries

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The dataset represents the boundaries of all public school districts in the state of New Mexico. The source for the data layer is the New Mexico Public Education...

  17. Allegheny County Boundary

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset contains the Allegheny County boundary. If viewing this description on the Western Pennsylvania Regional Data Center’s open data portal...

  18. Boundary representation modelling techniques

    CERN Document Server

    2006-01-01

    Provides the most complete presentation of boundary representation solid modelling yet publishedOffers basic reference information for software developers, application developers and users Includes a historical perspective as well as giving a background for modern research.

  19. Site Area Boundaries

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset consists of site boundaries from multiple Superfund sites in U.S. EPA Region 8. These data were acquired from multiple sources at different times and...

  20. Tax Unit Boundaries

    Data.gov (United States)

    Kansas Data Access and Support Center — The Statewide GIS Tax Unit boundary file was created through a collaborative partnership between the State of Kansas Department of Revenue Property Valuation...

  1. VT Federal Aid Urban Boundaries

    Data.gov (United States)

    Vermont Center for Geographic Information — Federal Aid Urban boundaries are defined based on US Census data. The roadways within these boundaries have urban classifications. These FAU boundaries were updated...

  2. Moving boundary approximation for curved streamer ionization fronts: solvability analysis

    NARCIS (Netherlands)

    F. Brau (Fabian); B. Davidovitch; U. Ebert (Ute)

    2008-01-01

    textabstractThe minimal density model for negative streamer ionization fronts is investigated. An earlier moving boundary approximation for this model consisted of a “kinetic undercooling” type boundary condition in a Laplacian growth problem of Hele-Shaw type. Here we derive a curvature

  3. Boundary element method for internal axisymmetric flow

    Directory of Open Access Journals (Sweden)

    Gokhman Alexander

    1999-01-01

    Full Text Available We present an accurate fast method for the computation of potential internal axisymmetric flow based on the boundary element technique. We prove that the computed velocity field asymptotically satisfies reasonable boundary conditions at infinity for various types of inlet/exit. Computation of internal axisymmetric potential flow is an essential ingredient in the three-dimensional problem of computation of velocity fields in turbomachines. We include the results of a practical application of the method to the computation of flow in turbomachines of Kaplan and Francis types.

  4. Adaptive Sentence Boundary Disambiguation

    CERN Document Server

    Palmer, D D; Palmer, David D.; Hearst, Marti A.

    1994-01-01

    Labeling of sentence boundaries is a necessary prerequisite for many natural language processing tasks, including part-of-speech tagging and sentence alignment. End-of-sentence punctuation marks are ambiguous; to disambiguate them most systems use brittle, special-purpose regular expression grammars and exception rules. As an alternative, we have developed an efficient, trainable algorithm that uses a lexicon with part-of-speech probabilities and a feed-forward neural network. After training for less than one minute, the method correctly labels over 98.5\\% of sentence boundaries in a corpus of over 27,000 sentence-boundary marks. We show the method to be efficient and easily adaptable to different text genres, including single-case texts.

  5. The Bottom Boundary Layer.

    Science.gov (United States)

    Trowbridge, John H; Lentz, Steven J

    2018-01-03

    The oceanic bottom boundary layer extracts energy and momentum from the overlying flow, mediates the fate of near-bottom substances, and generates bedforms that retard the flow and affect benthic processes. The bottom boundary layer is forced by winds, waves, tides, and buoyancy and is influenced by surface waves, internal waves, and stratification by heat, salt, and suspended sediments. This review focuses on the coastal ocean. The main points are that (a) classical turbulence concepts and modern turbulence parameterizations provide accurate representations of the structure and turbulent fluxes under conditions in which the underlying assumptions hold, (b) modern sensors and analyses enable high-quality direct or near-direct measurements of the turbulent fluxes and dissipation rates, and (c) the remaining challenges include the interaction of waves and currents with the erodible seabed, the impact of layer-scale two- and three-dimensional instabilities, and the role of the bottom boundary layer in shelf-slope exchange.

  6. Boundary conditions in CO5BOLD

    Science.gov (United States)

    Freytag, Bernd

    The declaration of boundary conditions is a crucial step in the setup of a CO5BOLD simulation (and many others) due to the physical nature of the problem, that is reflected in the mathematical description by partial differential equations, discrete versions of which are integrated by the numerical solver(s). While parameters controlling the flux of energy through the computational box are most important for all simulations of convective flows, the detailed specifications describing the behavior of energy, gas and dust densities, velocities, and magnetic fields at or just beyond the boundaries influence the flow, dynamics, and stratification within the box. Recent refinements of the treatment of boundary conditions in CO5BOLD resulted in reliably working implementations of open and closed versions for top, bottom, and ``inner'' boundaries even under conditions with strong velocity fields (waves, shocks, or downdrafts). They are implemented and available in the current version of CO5BOLD - but have to be activated properly with parameters adapted to the type of the star under consideration (by defining for instance the depth of the damping layers for the closed-bottom boundary or by specifying the damping constants for the open-bottom boundary).

  7. Implementation of Boundary Condition to THALES Code

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Beomjun; Chun, Chong Kuk; Park, Ho Young; Woo, Hae-Seuk [KEPCO Nuclear Fuel, Daejeon (Korea, Republic of)

    2016-10-15

    The boundary condition of momentum equation of THALES code utilizes the exit pressure boundary to solve the elliptic partial difference momentum equations. This method is the same as the most of the subchannel analysis codes. Other codes such as VIPRE utilize the uniform pressure distribution as outlet boundary condition. In this case, uniform inlet flow rate is assumed. In order to test the core flow field regarding the boundary conditions, analysis was performed for two core conditions. One condition is nominal plant operating condition. In this paper, generic THALES power distribution is used. For nominal operation case, there are no different results depending on the type of outlet pressure boundary condition. But low-power and high-peaking case, density difference for lateral direction becomes large due to high peaking power of core. Since density change causes pressure change, In this case, uniform outlet pressure distribution can't be assumed anymore. Design outlet pressure distribution is measured at nominal core condition. Therefore, design outlet pressure distribution also can't be used due to the difference in core power and flow rate. As a result, it is reasonable that neumann boundary condition is applied in low-power and high peaking core condition including various accident condition.

  8. Application of Laplace transform for determination of albedo type boundary conditions for neutronic calculations; Aplicacao da transformada de Laplace para determinacao de condicoes de contorno tipo albedo para calculos neutronicos

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, Claudio Zen

    2008-07-01

    In this dissertation we use the Laplace transform to derive expressions for nonstandard albedo boundary conditions for one and two non-multiplying regions at the ends of one dimensional domains. In practice, the fuel regions of reactor cores are surrounded by reflector regions that reduce neutron leakage. In order to exclude the reflector regions from the calculations, we introduce a reflection coefficient or albedo. We use the present albedo boundary conditions to solve numerically slab-geometry monoenergetic and multigroup diffusion equations using the conventional finite difference method. Numerical results are generated for fixed source and eigenvalue diffusion problems in slab geometry(author)

  9. Minnesota County Boundaries - lines

    Data.gov (United States)

    Minnesota Department of Natural Resources — Minnesota county boundaries derived from a combination of 1:24,000 scale PLS lines, 1:100,000 scale TIGER, 1:100,000 scale DLG, and 1:24,000 scale hydrography lines....

  10. Knowledge production at boundaries

    NARCIS (Netherlands)

    Stange, Kari

    2017-01-01

    This thesis addresses how knowledge is used and produced in stakeholder-led collaborations to make long-term management plans for European fishery management. Boundary object theory is applied and developed to explain how stakeholders from the fishing industry interact with each other, and with

  11. Environmentalists without Boundaries

    African Journals Online (AJOL)

    GREGORY

    2009-03-16

    Mar 16, 2009 ... African Journal of Environmental Science and Technology Vol. ... The most fruitful scientific endeavors invariably cross boundaries – across ... The White Man's Burden: Why the West's Efforts to Aid the Rest Have Done So Much ... cooperation and capacity (7)stimulating economic development and growth, ...

  12. Environmentalists without Boundaries

    African Journals Online (AJOL)

    GREGORY

    2009-03-16

    Mar 16, 2009 ... Hence, this is a laudable project, but Coca Cola should also be cognizant of the growing African environmental pollution problems associated with plastics disposal as they market bottled water and other juices on the continent. This is an example of a challenge associated with advertent boundary crossing ...

  13. Minnesota County Boundaries

    Data.gov (United States)

    Minnesota Department of Natural Resources — Minnesota county boundaries derived from a combination of 1:24,000 scale PLS lines, 1:100,000 scale TIGER, 1:100,000 scale DLG, and 1:24,000 scale hydrography lines....

  14. Boundaries of the universe

    CERN Document Server

    Glasby, John S

    2013-01-01

    The boundaries of space exploration are being pushed back constantly, but the realm of the partially understood and the totally unknown is as great as ever. Among other things this book deals with astronomical instruments and their application, recent discoveries in the solar system, stellar evolution, the exploding starts, the galaxies, quasars, pulsars, the possibilities of extraterrestrial life and relativity.

  15. Dual boundary spanning

    DEFF Research Database (Denmark)

    Li-Ying, Jason

    2016-01-01

    The extant literature runs short in understanding openness of innovation regarding and the different pathways along which internal and external knowledge resources can be combined. This study proposes a unique typology for outside-in innovations based on two distinct ways of boundary spanning...

  16. Environmentalists without Boundaries

    African Journals Online (AJOL)

    GREGORY

    2009-03-16

    Mar 16, 2009 ... idea that development and environmental sustainability require poverty eradication is not a shocking one, but many scholars remain skeptical about the ... in developing countries has potentially solved this boundary problem by asking for donations through the purchase of bottled water at a price that will ...

  17. Boundary-Layer Bypass Transition Over Large-Scale Bodies

    Science.gov (United States)

    2016-12-16

    AFRL-AFOSR-UK-TR-2017-0007 Boundary - layer bypass transition over large-scale bodies Pierre Ricco UNIVERSITY OF SHEFFIELD, DEPARTMENT OF PSYCHOLOGY...REPORT TYPE Final 3. DATES COVERED (From - To) 01 Sep 2013 to 31 Aug 2016 4. TITLE AND SUBTITLE Boundary - layer bypass transition over large-scale...shape of the streamwise velocity profile compared to the flat-plate boundary layer . The research showed that the streamwise wavenumber plays a key role

  18. Interactions between Dislocations and Grain Boundaries

    NARCIS (Netherlands)

    Soer, Wouter Anthon

    2006-01-01

    Dislocations (line defects) and grain boundaries (planar defects) are two types of lattice defects that are crucial to the deformation behavior of metals. Permanent deformation of a crystalline material is microscopically associated with the nucleation and propagation of dislocations, and extensive

  19. An h-principle with boundary condition

    DEFF Research Database (Denmark)

    Dotto, Emanuele

    2010-01-01

    We prove an h-principle with boundary condition for a certain class of topological spaces valued sheaves. The techniques used in the proof come from the study of the homotopy type of the cobordism categories, and they are of simplicial and categorical nature. Applying the main result of this paper...

  20. Grain Boundary Segregation in Metals

    CERN Document Server

    Lejcek, Pavel

    2010-01-01

    Grain boundaries are important structural components of polycrystalline materials used in the vast majority of technical applications. Because grain boundaries form a continuous network throughout such materials, their properties may limit their practical use. One of the serious phenomena which evoke these limitations is the grain boundary segregation of impurities. It results in the loss of grain boundary cohesion and consequently, in brittle fracture of the materials. The current book deals with fundamentals of grain boundary segregation in metallic materials and its relationship to the grain boundary structure, classification and other materials properties.

  1. Stationary solutions and Neumann boundary conditions in the Sivashinsky equation.

    Science.gov (United States)

    Denet, Bruno

    2006-09-01

    New stationary solutions of the (Michelson) Sivashinsky equation of premixed flames are obtained numerically in this paper. Some of these solutions, of the bicoalescent type recently described by Guidi and Marchetti, are stable with Neumann boundary conditions. With these boundary conditions, the time evolution of the Sivashinsky equation in the presence of a moderate white noise is controlled by jumps between stationary solutions.

  2. Computed Structure of Grain Boundaries Compared with TEM Observations

    NARCIS (Netherlands)

    Hosson, J.Th.M. De; Heringa, J.R.; Schapink, F.W.; Evans, J.H.; Veen, A. van

    1984-01-01

    Employing computer simulation techniques several studies of the relaxation of atoms in coincidence type grain boundaries have been performed in recent years. Often it is difficult to obtain a clear representation of the relaxed boundary structure, especially in the case of small atomic

  3. Boundary-layer theory

    CERN Document Server

    Schlichting (Deceased), Hermann

    2017-01-01

    This new edition of the near-legendary textbook by Schlichting and revised by Gersten presents a comprehensive overview of boundary-layer theory and its application to all areas of fluid mechanics, with particular emphasis on the flow past bodies (e.g. aircraft aerodynamics). The new edition features an updated reference list and over 100 additional changes throughout the book, reflecting the latest advances on the subject.

  4. Measuring the Substellar Boundary

    Science.gov (United States)

    Cancino, Adolfo Andrew; Dupuy, Trent

    2018-01-01

    Brown dwarfs are not massive enough to undergo hydrogen fusion and therefore constantly lose heat and change luminosity over their lifetime. Because of this, brown dwarfs do not follow the same pattern that stars on the main sequence follow. Brown dwarfs can have similar luminosities but widely differing masses, or vice versa, while stars follow a tight relationship between mass and luminosity. In principle, mass and luminosity measurements straddling the boundary between stars and brown dwarfs could be used to directly measure this dividing line in mass. We present a method for determining this boundary accurately given a limited sample size. We tested our method with Monte Carlo simulated samples of brown dwarfs and stars with randomly drawn masses and ages, using evolutionary models to infer luminosities. In our simulation designed to mimic the largest current sample of such mass measurements (37 objects; Dupuy & Liu 2017), we find that the uncertainty in the dividing line that can be inferred from the data is ± 4 MJup. This implies that distinguishing between competing evolutionary model predictions for the boundary (~70-80 MJup) will be difficult given the current sample size of mass measurements.

  5. Boundary layer receptivity phenomena in three-dimensional and high-speed boundary layers

    Science.gov (United States)

    Choudhari, Meelan; Streett, Craig L.

    1990-01-01

    The process by which the boundary layer internalizes the environmental disturbances in the form of instability waves is known as the boundary-layer receptivity. The paper discusses the importance of receptivity in transition research. The receptivity scenario for three-dimensional and high-speed boundary layers is examined. It is found that, while receptivity mechanisms present in the low-speed case are also operative in these complex flows, certain uniquely 'compressible' receptivity mechanisms may come into play as well. Both numerical, and where convenient, asymptotic procedures are utilized to develop quantitative predictions of the localized generation of a variety of instability types (Tollmien-Schlichting, inflectional, higher modes, crossflow vortices) in boundary layer flows relevant to the National Aero-Space Plane (NASP).

  6. Boundary properties of solutions of equations of minimal surface kind

    Science.gov (United States)

    Miklyukov, V. M.

    2001-10-01

    Generalized solutions of equations of minimal-surface type are studied. It is shown that a solution makes at most countably many jumps at the boundary. In particular, a solution defined in the exterior of a disc extends by continuity to the boundary circle everywhere outside a countable point set. An estimate of the sum of certain non-local characteristics of the jumps of a solution at the boundary is presented. A result similar to Fatou's theorem on angular boundary values is proved.

  7. Allegheny County Zip Code Boundaries

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset demarcates the zip code boundaries that lie within Allegheny County. These are not clipped to the Allgeheny County boundary. If viewing this...

  8. Boundaries of a complex world

    CERN Document Server

    Ludu, Andrei

    2016-01-01

    The central theme of this book is the extent to which the structure of the free dynamical boundaries of a system controls the evolution of the system as a whole. Applying three orthogonal types of thinking - mathematical, constructivist and morphological, it illustrates these concepts using applications to selected problems from the social and life sciences, as well as economics. In a broader context, it introduces and reviews some modern mathematical approaches to the science of complex systems. Standard modeling approaches (based on non-linear differential equations, dynamic systems, graph theory, cellular automata, stochastic processes, or information theory) are suitable for studying local problems. However they cannot simultaneously take into account all the different facets and phenomena of a complex system, and new approaches are required to solve the challenging problem of correlations between phenomena at different levels and hierarchies, their self-organization and memory-evolutive aspects, the grow...

  9. Boundary migration during recrystallization: experimental observations

    DEFF Research Database (Denmark)

    Zhang, Yubin; Juul Jensen, Dorte

    2015-01-01

    materials. This type of analysis has largely been based on the assumption that all or groups of recrystallizing grains grow in the same uniform manner, therefore the results represent average growth behaviors on a macro scale. Recently, significant efforts have been made to quantify the boundary migration......Quantitative analysis of boundary migration during recrystallization is a key task to understand the recrystallization process and to improve recrystallization models. In the last 25-30 years, quantification of boundary migration has mostly been conducted in term of average growth rates in many...... during recrystallization on local grain scales, using different advanced experimental characterization and computer simulation techniques. This paper aims at summarizing these recent achievements with focus on the potentials of the various advanced experimental characterization techniques. Suggestions...

  10. Boundary Shear Stress Along Vegetated Streambanks

    Science.gov (United States)

    Clark, L. A.; Wynn, T.

    2007-12-01

    Sediment, a leading cause of water quality impairment, damages aquatic ecosystems and interferes with recreational uses and water treatment processes. Streambank retreat can contribute as much as 85% of watershed sediment yield. Vegetation is an important component of stream restoration designs used to control streambank retreat, but vegetation effects on streambank boundary shear stress (SBSS) need to be quantified. The overall goal of this experiment is to predict boundary shear stress along vegetated streambanks. This goal will be met by determining a method for measuring boundary shear stress in the field along hydraulically rough streambanks, evaluating the effects of streambank vegetation on boundary shear stress in the field, and developing predictive methods based on measurable vegetative properties. First, three streambank vegetation types (herbaceous, shrubbery, and woody) will be modeled in a flume study to examine both boundary shear stress measurement theory and instruments for field use. An appropriate method (law of the wall, Reynold's stresses, TKE, or average wall shear stress) and field instrument (ADV, propeller, or Pitot tube) will be selected, resulting in a field technique to measure SBSS. Predictive methods for estimating SBSS, based on common vegetation measurements, will be developed in the flume study and validated with field data. This research is intended to improve our understanding of the role of riparian vegetation in stream morphology by evaluating the effects of vegetation on boundary shear stress, providing insight to the type and density of vegetation required for streambank stability. The results will also aide in quantifying sediment inputs from streambanks, providing quantitative information for stream restoration projects and watershed management planning.

  11. Progress report on grain boundaries

    Science.gov (United States)

    Balluffi, R. W.; Bristowe, P. D.

    1989-06-01

    The research was focused on the following three major areas: (1) study of the atomic structure of grain boundaries by means of X-ray diffraction, transmission electron microscopy and computer modeling; (2) study of grain boundary phase transitions by electron microscopy and computer modeling; (3) investigation of the mechanism of high angle grain boundary migration. Results are briefly discussed.

  12. Progress report on grain boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Balluffi, R.W.; Bristowe, P.D.

    1989-06-01

    The research was focused on the following three major areas: (1) study of the atomic structure of grain boundaries by means of x-ray diffraction, transmission electron microscopy and computer modeling; (2) study of grain boundary phase transitions by electron microscopy and computer modeling; (3) investigation of the mechanism of high angle grain boundary migration. Results are briefly discussed. 20 refs.

  13. Periodic and boundary value problems for second order differential ...

    Indian Academy of Sciences (India)

    Liouville and periodic boundary conditions. The vector field (, , ) is Caratheodory and in some instances the continuity condition on or is replaced by a monotonicity type hypothesis. Using the method of upper and lower solutions as well ...

  14. Boundary and sub-boundary hardening in tempered martensitic 9Cr steel during long-term creep at 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Fujio [National Institute for Materials Science, Sengen, Tsukuba (Japan)

    2010-07-01

    The boundary and sub-boundary hardening is shown to be the most important strengthening mechanism in creep of the 9% Cr steel base metal and welded joints. The addition of boron reduces the coarsening rate of M{sub 23}C{sub 6} carbides along boundaries near prior austenite grain boundaries during creep, enhancing the boundary and sub-boundary hardening. This improves long-term creep strength of base metal. The enhancement of boundary and sub-boundary hardening is significantly reduced in fine-grained region of Ac{sub 3} HAZ simulated specimens of conventional steel P92. In NIMS 9Cr boron steel welded joints, the grain size and distribution of carbonitrides are substantially the same between the HAZ and base metal, where fine carbonitrides are distributed along the lath and block boundaries as well as along prior austenite grain boundaries. This is essential for the suppression of Type IV fracture in NIMS 9% Cr boron steel welded joints. Newly alloy-designed 9Cr steel with 160 ppm boron and 85 ppm nitrogen exhibits much higher creep rupture strength of base metal than P92 and also no Tpe-IV fracture in welded joints at 650 C. (orig.)

  15. The system of equations for mixed BVP with one Dirichlet boundary condition and three Neumann boundary conditions

    Science.gov (United States)

    Yusop, Nur Syaza Mohd; Mohamed, Nurul Akmal

    2017-05-01

    Boundary Element Method (BEM) is a numerical way to approximate the solutions of a Boundary Value Problem (BVP). The potential problem which involves the Laplace's equation on the square shape domain will be considered where the boundary is divided into four sets of linear boundary elements. We study the derivation system of equation for mixed BVP with one Dirichlet Boundary Condition (BC) is prescribed on one element of the boundary and Neumann BC on the other three elements. The mixed BVP will be reduced to a Boundary Integral Equation (BIE) by using a direct method which involves Green's second identity representation formula. Then, linear interpolation is used where the boundary will be discretized into some linear elements. As the result, we then obtain the system of linear equations. In conclusion, the specific element in the mixed BVP will have the specific prescribe value depends on the type of boundary condition. For Dirichlet BC, it has only one value at each node but for the Neumann BC, there will be different values at the corner nodes due to outward normal. Therefore, the assembly process for the system of equations related to the mixed BVP may not be as straight forward as Dirichlet BVP and Neumann BVP. For the future research, we will consider the different shape domains for mixed BVP with different prescribed boundary conditions.

  16. A classification of ecological boundaries

    Science.gov (United States)

    Strayer, D.L.; Power, M.E.; Fagan, W.F.; Pickett, S.T.A.; Belnap, J.

    2003-01-01

    Ecologists use the term boundary to refer to a wide range of real and conceptual structures. Because imprecise terminology may impede the search for general patterns and theories about ecological boundaries, we present a classification of the attributes of ecological boundaries to aid in communication and theory development. Ecological boundaries may differ in their origin and maintenance, their spatial structure, their function, and their temporal dynamics. A classification system based on these attributes should help ecologists determine whether boundaries are truly comparable. This system can be applied when comparing empirical studies, comparing theories, and testing theoretical predictions against empirical results.

  17. Transcending Organizational Boundaries

    DEFF Research Database (Denmark)

    Kringelum, Louise Tina Brøns

    This thesis explores how processes of business model innovation can unfold in a port authority by transcending organizational boundaries through inter-organizational collaboration. The findings contribute to two fields of academic inquiry: the study of business model innovation and the study of how...... by applying the engaged scholarship approach, thereby providing a methodological contribution to both port and business model research. Emphasizing the interplay of intra- and inter-organizational business model innovation, the thesis adds insight into the roles of port authorities, business model trends...

  18. Dynamical simulation of structural multiplicity in grain boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Majid, I.; Bristowe, P.D.

    1987-06-01

    Work on a computer simulation study of a low-energy high-angle boundary structure which is not periodic have been recently reported. This result is of interest since grain boundary structures are usually assumed to have a periodicity corresponding to the appropriate coincidence site lattice (CSL) and many experimental observations of the structure of grain boundaries performed using conventional and high-resolution electron microscopy, electron diffraction and x-ray diffraction appear to support this work. However, this work, using empirical interatomic pair potentials and the relaxation method of molecular statics, have simulated a ..sigma.. = 5 36.87/sup 0/ (001) twist boundary and found a low energy structure having a larger repeat cell than the CSL and is composed of two different types of structural unit that are randomly distributed in the boundary plane. This result, which has been termed the multiplicity of grain boundary structures, has also been found in the simulation of tilt boundaries. The multiplicity phenomenon is of special interest in twist boundaries since it is used as a structural model to explain the x-ray scattering from a ..sigma.. = 5 boundary in gold. These scattering patterns had previously remained unexplained using stable structures that had simple CSL periodicity. Also, the effect of having a multiple number of low energy structural units coexisting in the grain boundary is of more general interest since it implies that the boundary structures may be quasi-periodic and, in some circumstances, may even result in a roughening of the boundary plane. This paper extends this work by showing, using molecular dynamics, that a multiplicity of structural units can actually nucleate spontaneously in a high-angle grain boundary at finite temperatures.

  19. Dynamical simulation of structural multiplicity in grain boundaries

    Science.gov (United States)

    Majid, I.; Bristowe, P. D.

    1987-06-01

    Work on a computer simulation study of a low-energy high-angle boundary structure which is not periodic have been recently reported. This result is of interest since grain boundary structures are usually assumed to have a periodicity corresponding to the appropriate coincidence site lattice (CSL) and many experimental observations of the structure of grain boundaries performed using conventional and high-resolution electron microscopy, electron diffraction and X-ray diffraction appear to support this work. However, this work, using empirical interatomic pair potentials and the relaxation method of molecular statics, have simulated a Sigma=5 (36.87 deg)(001) twist boundary and found a low energy structure having a larger repeat cell than the CSL and is composed of two different types of structural unit randomly distributed in the boundary plane. This result, termed the multiplicity of grain boundary structures, has also been found in the simulation of tilt boundaries. The multiplicity phenomenon is of special interest in twist boundaries since it is used as a structural model to explain the X-ray scattering from a Sigma=5 boundary in gold. These scattering patterns had previously remained unexplained using stable structures that had simple CSL periodicity. Also, the effect of having a multiple number of low energy structural units coexisting in the grain boundary is of more general interest since it implies that the boundary structures may be quasi-periodic and, in some circumstances, may even result in a roughening of the boundary plane. This work is extended by showing, using molecular dynamics, that a multiplicity of structural units can actually nucleate spontaneously in a high-angle grain boundary at finite temperatures.

  20. Grain Boundary Energies in Copper.

    Science.gov (United States)

    Omar, Ramli

    Available from UMI in association with The British Library. Requires signed TDF. The dependence of grain boundary energy on boundary orientation was studied in copper annealed at 1000 ^circC. Grain boundary orientations and the disorientations across the boundaries were measured. A rotation matrix notation is used to interpret selected area electron channelling patterns observed in a scanning electron microscope. The Herring and Shewmon torque terms were investigated using wire specimens having a "bamboo" structure. The Herring torque terms were determined using the Hess relation. The (110) section of the Sigma 11 gamma-plot (i.e. the variation of grain boundary energy with boundary orientation) was evaluated. In this plot, minima in energies were found at the (311) and (332) mirror planes. Sigma 3 and Sigma9 boundaries were investigated in sheet specimens. The (110) and (111) sections of the Sigma3 gamma -plot were evaluated. In addition to the sharp cusps occurring at the Sigma3 {111} planes, the further shallower cusps occur at the incoherent Sigma 3 boundaries with the interfacial planes approximately parallel to {322} in one crystal and {11.44} in the other crystal. Flat and curved Sigma9 boundaries were investigated. The break up of Sigma9 boundaries into two Sigma3 boundaries and the relation between the Sigma3 and Sigma 9 gamma-plots was also examined. The (110) section of the Sigma9 gamma-plot was constructed.

  1. Reweighting twisted boundary conditions

    CERN Document Server

    Bussone, Andrea; Hansen, Martin; Pica, Claudio

    2015-01-01

    Imposing twisted boundary conditions on the fermionic fields is a procedure extensively used when evaluating, for example, form factors on the lattice. Twisting is usually performed for one flavour and only in the valence, and this causes a breaking of unitarity. In this work we explore the possibility of restoring unitarity through the reweighting method. We first study some properties of the approach at tree level and then we stochastically evaluate ratios of fermionic determinants for different boundary conditions in order to include them in the gauge averages, avoiding in this way the expensive generation of new configurations for each choice of the twisting angle, $\\theta$. As expected the effect of reweighting is negligible in the case of large volumes but it is important when the volumes are small and the twisting angles are large. In particular we find a measurable effect for the plaquette and the pion correlation function in the case of $\\theta=\\pi/2$ in a volume $16\\times 8^3$, and we observe a syst...

  2. An Optical Study of Ice Grain Boundaries

    Science.gov (United States)

    Thomson, Erik S.

    The equilibrium phase geometry and evolution of polycrystals underlies the nature of materials. In particular, grain boundaries dominate the total interfacial area within polycrystalline materials. Our experimental studies are motivated by the importance of the structure, evolution, and thermodynamic behavior of grain boundaries near bulk melting temperatures. Ice is singled out as a material of interest due to its geophysical importance and its advantageous optical properties. An experimental apparatus and light reflection technique is designed to measure grain boundary melting in ice bicrystals, in thermodynamic equilibrium The technique allows continuous monitoring of reflected light intensity from the grain boundary as the temperature and solutal composition are systematically varied. For each sample the individual crystal orientations are also measured. The type and concentration of impurity in the liquid is controlled and the temperature is continuously recorded and controlled over a range near the melting point. An optical model of the interface is developed in order to convert experimental reflection data into a physical measurement of the liquidity of the grain boundary. Solutions are found for reflection and transmission amplitude coefficients for waves propagating from an arbitrarily oriented uniaxial anisotropic material into an isotropic material. This general model is used to determine solutions for three layer, ice/water/ice, systems with crystals of arbitrary orientation, and is broadly applicable to layered materials. Experimental results show thicker grain boundary liquid layers than expected from classical colligative effects. A physically realistic model of intermolecular interactions succeeds in bounding the measurements. These measurements may have important implications for understanding a wide range of effects in polycrystalline materials. Likewise, the experimental techniques and optical theory may be applied to other systems of broad

  3. Structure and properties of grain boundaries

    Science.gov (United States)

    Balluffi, R. W.; Bristowe, P. D.

    1984-03-01

    Results were obtained in the following areas: determination of relative grain boundary energies by the rotating crystallite method; simple structural unit model for core dependent properties of tilt boundaries; twist boundary energies for metals with long ranged pairwise interatomic potentials; structural unit/grain boundary dislocation model for grain boundary structure; detection of expansion of boundaries using diffraction; effect of secondary relaxations on diffraction from high-(SIGMA) 001 twist boundaries; and mechanism of grain boundary migration.

  4. Boundary work for implementing adaptive management: A water sector application.

    Science.gov (United States)

    Adem Esmail, Blal; Geneletti, Davide; Albert, Christian

    2017-09-01

    Boundary work, defined as effort to mediate between knowledge and action, is a promising approach for facilitating knowledge co-production for sustainable development. Here, we investigate a case study of knowledge co-production, to assess the applicability of boundary work as a conceptual framework to support implementing adaptive management in the water sector. We refer to a boundary work classification recently proposed by Clark et al., (2016), based on three types of knowledge uses, i.e. enlightenment, decision-, and negotiation-support, and three types of sources, i.e. personal expertise, single, and multiple communities of expertise. Our empirical results confirm boundary work has been crucial for the three types of knowledge use. For enlightenment and decision-support, effective interaction among knowledge producers and users was achieved through diverse boundary work practices, including joint agenda setting, and sharing of data and expertise. This initial boundary work eased subsequent knowledge co-production for decision-support and negotiations, in combination with stepping up of cooperation between relevant actors, suitable legislation and pressure for problem solving. Our analysis highlighted the temporal dimension matters - building trust around enlightenment first, and then using this as a basis for managing knowledge co-production for decision-, and negotiation support. We reconfirmed that boundary work is not a single time achievement, rather is a dynamic process, and we emphasized the importance of key actors driving the process, such as water utilities. Our results provide a rich case study of how strategic boundary work can facilitate knowledge co-production for adaptive management in the water sector. The boundary work practices employed here could also be transferred to other cases. Water utilities, as intermediaries between providers and beneficiaries of the important water-related ecosystem service of clean water provision, can indeed serve

  5. Negotiating Cluster Boundaries

    DEFF Research Database (Denmark)

    Giacomin, Valeria

    2017-01-01

    Palm oil was introduced to Malay(si)a as an alternative to natural rubber, inheriting its cluster organizational structure. In the late 1960s, Malaysia became the world’s largest palm oil exporter. Based on archival material from British colonial institutions and agency houses, this paper focuses...... on the governance dynamics that drove institutional change within this cluster during decolonization. The analysis presents three main findings: (i) cluster boundaries are defined by continuous tug-of-war style negotiations between public and private actors; (ii) this interaction produces institutional change...... within the cluster, in the form of cumulative ‘institutional rounds’ – the correction or disruption of existing institutions or the creation of new ones; and (iii) this process leads to a broader inclusion of local actors in the original cluster configuration. The paper challenges the prevalent argument...

  6. Superfluid Boundary Layer.

    Science.gov (United States)

    Stagg, G W; Parker, N G; Barenghi, C F

    2017-03-31

    We model the superfluid flow of liquid helium over the rough surface of a wire (used to experimentally generate turbulence) profiled by atomic force microscopy. Numerical simulations of the Gross-Pitaevskii equation reveal that the sharpest features in the surface induce vortex nucleation both intrinsically (due to the raised local fluid velocity) and extrinsically (providing pinning sites to vortex lines aligned with the flow). Vortex interactions and reconnections contribute to form a dense turbulent layer of vortices with a nonclassical average velocity profile which continually sheds small vortex rings into the bulk. We characterize this layer for various imposed flows. As boundary layers conventionally arise from viscous forces, this result opens up new insight into the nature of superflows.

  7. Public Computation & Boundary Play

    CERN Document Server

    Sengupta, Pratim

    2016-01-01

    In this paper, we introduce 'public computation' as a genre of learning environments that can be used to radically broaden public participation in authentic, computation-enabled STEM disciplinary practices. Our paradigmatic approach utilizes open source software designed for professional scientists, engineers and digital artists, and situates them in an undiluted form, alongside live and archived expert support, in a public space. We present a case study of DigiPlay, a prototypical public computation space we designed at the University of Calgary, where users can interact directly with scientific simulations as well as the underlying open source code using an array of massive multi- touch screens. We argue that in such a space, public interactions with the code can be thought of as boundary work and play, through which public participation becomes legitimate scientific act, as the public engages in scientific creation through truly open-ended explorations with the code.

  8. Challenging the Boundaries

    DEFF Research Database (Denmark)

    Nørgaard, Nina

    2004-01-01

    to explore in the study and teaching of foreign languages. Not only may linguistics and literature be employed to shed light on each other, the insights gained may furthermore prove useful in a broader context in our foreign language studies. The article begins with a brief introduction to literary...... linguistics in general and to Hallidayan linguistics in particular. The theoretical framework thus laid out, it is exemplified how Halliday's theory of language may be employed in the analysis of literature. The article concludes by considering the possible status of literary linguistics in a broader......To many people, challenging the boundaries between the traditional disciplines in foreign language studies means doing cultural studies. The aim of this article is to pull in a different direction by suggesting how the interface between linguistics and literature may be another fertile field...

  9. The Plasmasphere Boundary Layer

    Directory of Open Access Journals (Sweden)

    D. L. Carpenter

    2004-12-01

    Full Text Available As an inner magnetospheric phenomenon the plasmapause region is of interest for a number of reasons, one being the occurrence there of geophysically important interactions between the plasmas of the hot plasma sheet and of the cool plasmasphere. There is a need for a conceptual framework within which to examine and discuss these interactions and their consequences, and we therefore suggest that the plasmapause region be called the Plasmasphere Boundary Layer, or PBL. Such a term has been slow to emerge because of the complexity and variability of the plasma populations that can exist near the plasmapause and because of the variety of criteria used to identify the plasmapause in experimental data. Furthermore, and quite importantly in our view, a substantial obstacle to the consideration of the plasmapause region as a boundary layer has been the longstanding tendency of textbooks on space physics to limit introductory material on the plasmapause phenomenon to zeroth order descriptions in terms of ideal MHD theory, thus implying that the plasmasphere is relatively well understood. A textbook may introduce the concept of shielding of the inner magnetosphere from perturbing convection electric fields, but attention is not usually paid to the variety of physical processes reported to occur in the PBL, such as heating, instabilities, and fast longitudinal flows, processes which must play roles in plasmasphere dynamics in concert with the flow regimes associated with the major dynamo sources of electric fields. We believe that through the use of the PBL concept in future textbook discussions of the plasmasphere and in scientific communications, much progress can be made on longstanding questions about the physics involved in the formation of the plasmapause and in the cycles of erosion and recovery of the plasmasphere. Key words. Magnetospheric physics (plasmasphere; plasma convection; MHD waves and instabilities

  10. The Plasmasphere Boundary Layer

    Directory of Open Access Journals (Sweden)

    D. L. Carpenter

    2004-12-01

    Full Text Available As an inner magnetospheric phenomenon the plasmapause region is of interest for a number of reasons, one being the occurrence there of geophysically important interactions between the plasmas of the hot plasma sheet and of the cool plasmasphere. There is a need for a conceptual framework within which to examine and discuss these interactions and their consequences, and we therefore suggest that the plasmapause region be called the Plasmasphere Boundary Layer, or PBL. Such a term has been slow to emerge because of the complexity and variability of the plasma populations that can exist near the plasmapause and because of the variety of criteria used to identify the plasmapause in experimental data. Furthermore, and quite importantly in our view, a substantial obstacle to the consideration of the plasmapause region as a boundary layer has been the longstanding tendency of textbooks on space physics to limit introductory material on the plasmapause phenomenon to zeroth order descriptions in terms of ideal MHD theory, thus implying that the plasmasphere is relatively well understood. A textbook may introduce the concept of shielding of the inner magnetosphere from perturbing convection electric fields, but attention is not usually paid to the variety of physical processes reported to occur in the PBL, such as heating, instabilities, and fast longitudinal flows, processes which must play roles in plasmasphere dynamics in concert with the flow regimes associated with the major dynamo sources of electric fields. We believe that through the use of the PBL concept in future textbook discussions of the plasmasphere and in scientific communications, much progress can be made on longstanding questions about the physics involved in the formation of the plasmapause and in the cycles of erosion and recovery of the plasmasphere.

    Key words. Magnetospheric physics (plasmasphere; plasma convection; MHD waves and instabilities

  11. Solution of a Problem Linear Plane Elasticity with Mixed Boundary Conditions by the Method of Boundary Integrals

    Directory of Open Access Journals (Sweden)

    Nahed S. Hussein

    2014-01-01

    Full Text Available A numerical boundary integral scheme is proposed for the solution to the system of …eld equations of plane. The stresses are prescribed on one-half of the circle, while the displacements are given. The considered problem with mixed boundary conditions in the circle is replaced by two problems with homogeneous boundary conditions, one of each type, having a common solution. The equations are reduced to a system of boundary integral equations, which is then discretized in the usual way, and the problem at this stage is reduced to the solution to a rectangular linear system of algebraic equations. The unknowns in this system of equations are the boundary values of four harmonic functions which define the full elastic solution and the unknown boundary values of stresses or displacements on proper parts of the boundary. On the basis of the obtained results, it is inferred that a stress component has a singularity at each of the two separation points, thought to be of logarithmic type. The results are discussed and boundary plots are given. We have also calculated the unknown functions in the bulk directly from the given boundary conditions using the boundary collocation method. The obtained results in the bulk are discussed and three-dimensional plots are given. A tentative form for the singular solution is proposed and the corresponding singular stresses and displacements are plotted in the bulk. The form of the singular tangential stress is seen to be compatible with the boundary values obtained earlier. The efficiency of the used numerical schemes is discussed.

  12. Grain boundary melting in ice

    OpenAIRE

    Thomson, E. S.; Hansen-Goos, Hendrik; Wilen, L. A.; Wettlaufer, J. S.

    2012-01-01

    We describe an optical scattering study of grain boundary premelting in water ice. Ubiquitous long ranged attractive polarization forces act to suppress grain boundary melting whereas repulsive forces originating in screened Coulomb interactions and classical colligative effects enhance it. The liquid enhancing effects can be manipulated by adding dopant ions to the system. For all measured grain boundaries this leads to increasing premelted film thickness with increasing electrolyte concentr...

  13. Analysis of turbulent boundary layers

    CERN Document Server

    Cebeci, Tuncer

    1974-01-01

    Analysis of Turbulent Boundary Layers focuses on turbulent flows meeting the requirements for the boundary-layer or thin-shear-layer approximations. Its approach is devising relatively fundamental, and often subtle, empirical engineering correlations, which are then introduced into various forms of describing equations for final solution. After introducing the topic on turbulence, the book examines the conservation equations for compressible turbulent flows, boundary-layer equations, and general behavior of turbulent boundary layers. The latter chapters describe the CS method for calculati

  14. Symbolic Boundary Work in Schools: Demarcating and Denying Ethnic Boundaries

    Science.gov (United States)

    Tabib-Calif, Yosepha; Lomsky-Feder, Edna

    2014-01-01

    This article examines the symbolic boundary work that is carried out at a school whose student population is heterogeneous in terms of ethnicity and class. Based on ethnography, the article demonstrates how the school's staff seeks to neutralize ethnic boundaries and their accompanying discourse, while the pupils try to bring ethnic…

  15. Collaboration in Healthcare Through Boundary Work and Boundary Objects

    DEFF Research Database (Denmark)

    Meier, Ninna

    2015-01-01

    This article contributes to our understanding of how boundary work is practiced in healthcare settings. Previous studies have shown how boundaries are constantly changing, multiple, and co-existing, and can also be relatively stable cognitive and social distinctions between individuals and groups....... In highly specialized, knowledge-intensive organizations such as healthcare organizations, organizational, professional, and disciplinary boundaries mark the formal structure and division of work. Collaboration and coordination across these boundaries are essential to minimizing gaps in patient care......, but also may be challenging to achieve in practice. By drawing on data from an ethnographic study of two hospital wards, this article investigates practices of cross-disciplinary and professional collaboration and adds to our knowledge of how this kind of boundary work is produced in context. Moreover...

  16. Boundary-Layer & health

    Science.gov (United States)

    Costigliola, V.

    2010-09-01

    It has long been known that specific atmospheric processes, such as weather and longer-term climatic fluctuations, affect human health. The biometeorological literature refers to this relationship as meteorotropism, defined as a change in an organism that is correlated with a change in atmospheric conditions. Plenty of (patho)physiological functions are affected by those conditions - like the respiratory diseases - and currently it is difficult to put any limits for pathologies developed in reply. Nowadays the importance of atmospheric boundary layer and health is increasingly recognised. A number of epidemiologic studies have reported associations between ambient concentrations of air pollution, specifically particulate pollution, and adverse health effects, even at the relatively low concentrations of pollution found. Since 1995 there have been over twenty-one studies from four continents that have explicitly examined the association between ambient air pollutant mixes and daily mortality. Statistically significant and positive associations have been reported in data from various locations around the world, all with varying air pollutant concentrations, weather conditions, population characteristics and public health policies. Particular role has been given to atmospheric boundary layer processes, the impact of which for specific patient-cohort is, however, not well understood till now. Assessing and monitoring air quality are thus fundamental to improve Europe's welfare. One of current projects run by the "European Medical Association" - PASODOBLE will develop and demonstrate user-driven downstream information services for the regional and local air quality sectors by combining space-based and in-situ data with models in 4 thematic service lines: - Health community support for hospitals, pharmacies, doctors and people at risk - Public information for regions, cities, tourist industry and sporting event organizers - Compliance monitoring support on particulate

  17. Seismic link at plate boundary

    Indian Academy of Sciences (India)

    transfer between two major faults, and parallel to the geothermal area extension. 1. Introduction. Plate boundaries are the zones where most earth dynamics are focussed. The complexity of tectonic boundaries draws attention to them as the largest earthquakes are felt in these areas and they elicit the natural hazard of ...

  18. Exclusion Process with Slow Boundary

    Science.gov (United States)

    Baldasso, Rangel; Menezes, Otávio; Neumann, Adriana; Souza, Rafael R.

    2017-06-01

    We study the hydrodynamic and the hydrostatic behavior of the simple symmetric exclusion process with slow boundary. The term slow boundary means that particles can be born or die at the boundary sites, at a rate proportional to N^{-θ }, where θ > 0 and N is the scaling parameter. In the bulk, the particles exchange rate is equal to 1. In the hydrostatic scenario, we obtain three different linear profiles, depending on the value of the parameter θ ; in the hydrodynamic scenario, we obtain that the time evolution of the spatial density of particles, in the diffusive scaling, is given by the weak solution of the heat equation, with boundary conditions that depend on θ . If θ \\in (0,1), we get Dirichlet boundary conditions, (which is the same behavior if θ =0, see Farfán in Hydrostatics, statical and dynamical large deviations of boundary driven gradient symmetric exclusion processes, 2008); if θ =1, we get Robin boundary conditions; and, if θ \\in (1,∞), we get Neumann boundary conditions.

  19. Fuzzy Boundary and Fuzzy Semiboundary

    OpenAIRE

    Athar, M.; Ahmad, B.

    2008-01-01

    We present several properties of fuzzy boundary and fuzzy semiboundary which have been supported by examples. Properties of fuzzy semi-interior, fuzzy semiclosure, fuzzy boundary, and fuzzy semiboundary have been obtained in product-related spaces. We give necessary conditions for fuzzy continuous (resp., fuzzy semicontinuous, fuzzy irresolute) functions. Moreover, fuzzy continuous (resp., fuzzy semicontinuous, fuzzy irresolute) functions have been characterized via fuzzy...

  20. Nucleation of small angle boundaries

    CSIR Research Space (South Africa)

    Nabarro, FRN

    1996-12-01

    Full Text Available The internal stresses induced by the strain gradients in an array of lattice cells delineated by low-angle dislocation boundaries are partially relieved by the creation of new low-angle boundaries. This is shown to be a first-order transition...

  1. How Firms Make Boundary Decisions

    DEFF Research Database (Denmark)

    Dobrajska, Magdalena; Billinger, Stephan; Becker, Markus

    2014-01-01

    We report findings from an analysis of 234 firm boundary decisions that a manufacturing firm has made during a 10 year period. Extensive interviews with all major decision makers located both at the headquarters and subsidiaries allow us to examine (a) who was involved in each boundary decision...

  2. A barotropic planetary boundary layer

    Science.gov (United States)

    Yordanov, D.; Syrakov, D.; Djolov, G.

    1983-04-01

    The temperature and wind profiles in the planetary boundary layer (PBL) are investigated. Assuming stationary and homogeneous conditions, the turbulent state in the PBL is uniquely determined by the external Rossby number and the stratification parameters. In this study, a simple two-layer barotropic model is proposed. It consists of a surface (SL) and overlying Ekman-type layer. The system of dynamic and heat transfer equations is closed using K theory. In the SL, the turbulent exchange coefficient is consistent with the results of similarity theory while in the Ekman layer, it is constant. Analytical solutions for the wind and temperature profiles in the PBL are obtained. The SL and thermal PBL heights are properly chosen functions of the stratification so that from the solutions for wind and temperature, the PBL resistance laws can be easily deduced. The internal PBL characteristics necessary for the calculation (friction velocity, angle between surface and geostrophic winds and internal stratification parameter) are presented in terms of the external parameters. Favorable agreement with experimental data and model results is demonstrated. The simplicity of the model allows it to be incorporated in large-scale weather prediction models as well as in the solution of various other meteorological problems.

  3. Nonlinear Elliptic Boundary Value Problems at Resonance with Nonlinear Wentzell Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Ciprian G. Gal

    2017-01-01

    Full Text Available Given a bounded domain Ω⊂RN with a Lipschitz boundary ∂Ω and p,q∈(1,+∞, we consider the quasilinear elliptic equation -Δpu+α1u=f in Ω complemented with the generalized Wentzell-Robin type boundary conditions of the form bx∇up-2∂nu-ρbxΔq,Γu+α2u=g on ∂Ω. In the first part of the article, we give necessary and sufficient conditions in terms of the given functions f, g and the nonlinearities α1, α2, for the solvability of the above nonlinear elliptic boundary value problems with the nonlinear boundary conditions. In other words, we establish a sort of “nonlinear Fredholm alternative” for our problem which extends the corresponding Landesman and Lazer result for elliptic problems with linear homogeneous boundary conditions. In the second part, we give some additional results on existence and uniqueness and we study the regularity of the weak solutions for these classes of nonlinear problems. More precisely, we show some global a priori estimates for these weak solutions in an L∞-setting.

  4. Prediction of dislocation boundary characteristics

    DEFF Research Database (Denmark)

    Winther, Grethe

    Plastic deformation of both fcc and bcc metals of medium to high stacking fault energy is known to result in dislocation patterning in the form of cells and extended planar dislocation boundaries. The latter align with specific crystallographic planes, which depend on the crystallographic....... Crystal plasticity calculations combined with the hypothesis that these boundaries separate domains with local differences in the slip system activity are introduced to address precise prediction of the experimentally observed boundaries. The presentation will focus on two cases from fcc metals...... orientation of the grain [1]. For selected boundaries it has been experimentally verified that the boundaries consist of fairly regular networks of dislocations, which come from the active slip systems [2]. The networks have been analyzed within the framework of Low-Energy-Dislocation-Structures (LEDS...

  5. Boundary Drawing in Clinical Work

    DEFF Research Database (Denmark)

    Meier, Ninna

    The aim of this paper is to show how health care professionals temporarily dissolve and redraw boundaries in their everyday work, in order to coordinate clinical work and facilitate collaboration in patient pathways. Boundaries are social constructions that help us make sense of our complex, social...... world. In health care, formal boundaries are important distinctions that separate health care practitioners into medical specialties, professions and organizational departments. But clinical work also relies on the ability of health care practitioners to collaborate around patients in formal...... arrangements or emergent, temporary teams. Focusing on the cognitive and social boundaries we draw to establish identity and connection (to a profession, team or person) the paper shows how health care professionals can use inter-personal relationships to temporarily dismiss formal boundaries. By redrawing...

  6. Distributed Tuning of Boundary Resources

    DEFF Research Database (Denmark)

    Eaton, Ben; Elaluf-Calderwood, Silvia; Sørensen, Carsten

    2015-01-01

    in the context of a paradoxical tension between the logic of generative and democratic innovations and the logic of infrastructural control. Boundary resources play a critical role in managing the tension as a firm that owns the infrastructure can secure its control over the service system while independent...... firms can participate in the service system. In this study, we explore the evolution of boundary resources. Drawing on Pickering’s (1993) and Barrett et al.’s (2012) conceptualizations of tuning, the paper seeks to forward our understanding of how heterogeneous actors engage in the tuning of boundary...... resources within Apple’s iOS service system. We conduct an embedded case study of Apple’s iOS service system with an in-depth analysis of 4,664 blog articles concerned with 30 boundary resources covering 6 distinct themes. Our analysis reveals that boundary resources of service systems enabled by digital...

  7. Modeling the summertime Arctic cloudy boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Curry, J.A.; Pinto, J.O. [Univ. of Colorado, Boulder, CO (United States); McInnes, K.L. [CSIRO Division of Atmospheric Research, Mordialloc (Australia)

    1996-04-01

    Global climate models have particular difficulty in simulating the low-level clouds during the Arctic summer. Model problems are exacerbated in the polar regions by the complicated vertical structure of the Arctic boundary layer. The presence of multiple cloud layers, a humidity inversion above cloud top, and vertical fluxes in the cloud that are decoupled from the surface fluxes, identified in Curry et al. (1988), suggest that models containing sophisticated physical parameterizations would be required to accurately model this region. Accurate modeling of the vertical structure of multiple cloud layers in climate models is important for determination of the surface radiative fluxes. This study focuses on the problem of modeling the layered structure of the Arctic summertime boundary-layer clouds and in particular, the representation of the more complex boundary layer type consisting of a stable foggy surface layer surmounted by a cloud-topped mixed layer. A hierarchical modeling/diagnosis approach is used. A case study from the summertime Arctic Stratus Experiment is examined. A high-resolution, one-dimensional model of turbulence and radiation is tested against the observations and is then used in sensitivity studies to infer the optimal conditions for maintaining two separate layers in the Arctic summertime boundary layer. A three-dimensional mesoscale atmospheric model is then used to simulate the interaction of this cloud deck with the large-scale atmospheric dynamics. An assessment of the improvements needed to the parameterizations of the boundary layer, cloud microphysics, and radiation in the 3-D model is made.

  8. Brain response to prosodic boundary cues depends on boundary position

    Directory of Open Access Journals (Sweden)

    Julia eHolzgrefe

    2013-07-01

    Full Text Available Prosodic information is crucial for spoken language comprehension and especially for syntactic parsing, because prosodic cues guide the hearer’s syntactic analysis. The time course and mechanisms of this interplay of prosody and syntax are not yet well understood. In particular, there is an ongoing debate whether local prosodic cues are taken into account automatically or whether they are processed in relation to the global prosodic context in which they appear. The present study explores whether the perception of a prosodic boundary is affected by its position within an utterance. In an event-related potential (ERP study we tested if the brain response evoked by the prosodic boundary differs when the boundary occurs early in a list of three names connected by conjunctions (i.e., after the first name as compared to later in the utterance (i.e., after the second name. A closure positive shift (CPS — marking the processing of a prosodic phrase boundary — was elicited only for stimuli with a late boundary, but not for stimuli with an early boundary. This result is further evidence for an immediate integration of prosodic information into the parsing of an utterance. In addition, it shows that the processing of prosodic boundary cues depends on the previously processed information from the preceding prosodic context.

  9. Uniqueness for a boundary identification problem in thermal imaging

    Directory of Open Access Journals (Sweden)

    Kurt Bryan

    1998-11-01

    Full Text Available An inverse problem for an initial-boundary value problem is considered. The goal is to determine an unknown portion of the boundary of a region in ${mathbb R}^n$ from measurements of Cauchy data on a known portion of the boundary. The dynamics in the interior of the region are governed by a differential operator of parabolic type. Utilizing a unique continuation result for evolution operators, along with the method of eigenfunction expansions, it is shown that uniqueness holds for a large and physically reasonable class of Cauchy data pairs.

  10. Active control of ionized boundary layers

    CERN Document Server

    Mendes, R V

    1997-01-01

    The challenging problems, in the field of control of chaos or of transition to chaos, lie in the domain of infinite-dimensional systems. Access to all variables being impossible in this case and the controlling action being limited to a few collective variables, it will not in general be possible to drive the whole system to the desired behaviour. A paradigmatic problem of this type is the control of the transition to turbulence in the boundary layer of fluid motion. By analysing a boundary layer flow for an ionized fluid near an airfoil, one concludes that active control of the transition amounts to the resolution of an generalized integro-differential eigenvalue problem. To cope with the required response times and phase accuracy, electromagnetic control, whenever possible, seems more appropriate than mechanical control by microactuators.

  11. On weak solvability of boundary value problems for elliptic systems

    OpenAIRE

    Ponce, Felipe; Lebedev, Leonid,; Rendón, Leonardo,

    2013-01-01

    This paper concerns with existence and uniqueness of a weak solution for elliptic systems of partial differential equations with mixed boundary conditions. The proof is based on establishing the coerciveness of bilinear forms, related with the system of equations, which depend on first-order derivatives of vector functions in Rn. The condition of coerciveness relates to Korn's type inequalities. The result is illustrated by an example of boundary value problems for a class of elliptic equatio...

  12. On a Nonlinear Degenerate Evolution Equation with Nonlinear Boundary Damping

    Directory of Open Access Journals (Sweden)

    A. T. Lourêdo

    2015-01-01

    Full Text Available This paper deals essentially with a nonlinear degenerate evolution equation of the form Ku″-Δu+∑j=1nbj∂u′/∂xj+uσu=0 supplemented with nonlinear boundary conditions of Neumann type given by ∂u/∂ν+h·, u′=0. Under suitable conditions the existence and uniqueness of solutions are shown and that the boundary damping produces a uniform global stability of the corresponding solutions.

  13. Right focal boundary value problems for difference equations

    Directory of Open Access Journals (Sweden)

    Johnny Henderson

    2010-01-01

    Full Text Available An application is made of a new Avery et al. fixed point theorem of compression and expansion functional type in the spirit of the original fixed point work of Leggett and Williams, to obtain positive solutions of the second order right focal discrete boundary value problem. In the application of the fixed point theorem, neither the entire lower nor entire upper boundary is required to be mapped inward or outward. A nontrivial example is also provided.

  14. A finite difference method for free boundary problems

    KAUST Repository

    Fornberg, Bengt

    2010-04-01

    Fornberg and Meyer-Spasche proposed some time ago a simple strategy to correct finite difference schemes in the presence of a free boundary that cuts across a Cartesian grid. We show here how this procedure can be combined with a minimax-based optimization procedure to rapidly solve a wide range of elliptic-type free boundary value problems. © 2009 Elsevier B.V. All rights reserved.

  15. Boundary and sub-boundary hardening in high-Cr ferritic steels during long-term creep at 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Abe, F. [National Institute for Materials Science (NIMS) (Japan)

    2008-07-01

    The sub-boundary hardening is shown to be the most important strengthening mechanism in creep of the 9% Cr steel base metal and welded joints. The addition of boron reduces the coarsening rate of M{sub 23}C{sub 6} carbides along boundaries near prior austenite grain boundaries during creep, enhancing the sub-boundary hardening. This improves long-term creep strength. The enhancement of boundary and subboundary hardening by fine distribution of precipitates along boundaries is significantly reduced in fine-grained region of Ac{sub 3} HAZ simulated specimens of conventional steels P92 and P122. In NIMS 9% Cr boron steel welded joints, the grain size and distribution of carbonitrides are substantially the same between the HAZ and base metal, where fine carbonitrides are distributed along the lath and block boundaries as well as along prior austenite grain boundaries. This is essential for the suppression of Type IV fracture in NIMS 9% Cr boron steel welded joints. (orig.)

  16. Boundaries of dreams, boundaries of dreamers: thin and thick boundaries as a new personality measure.

    Science.gov (United States)

    Hartmann, E

    1989-11-01

    Previous work by the author and his collaborators on frequent nightmare sufferers demonstrated that these people had striking personality characteristics which could be called "thin boundaries" in a number of different senses. In order to measure thin and thick boundaries, a 145-item questionnaire, the Boundary Questionnaire, has been developed which has now been taken by over 1,000 persons. Preliminary results are presented indicating that, as predicted a priori, several new groups of nightmare sufferers and groups of art students scored usually "thin," whereas a group of naval officers had usually "thick" boundaries. Overall, thinness on the Boundary Questionnaire correlated highly positively (r = .40) with frequency of dream recall and also significantly (r = .16) with length of sleep.

  17. Vibrations of stretched damped beams under non-ideal boundary ...

    Indian Academy of Sciences (India)

    Stretched beam vibrations; non-ideal boundary conditions; method of multiple time scales. 1. Introduction. Beams are frequently used as design models for vibration analysis. In such analysis, types of support conditions are important and have direct effect on the solutions and natural fre- quencies. Different types of supports ...

  18. Identifying deformation mechanisms in the NEEM ice core using EBSD measurements

    Science.gov (United States)

    Kuiper, Ernst-Jan; Weikusat, Ilka; Drury, Martyn R.; Pennock, Gill M.; de Winter, Matthijs D. A.

    2015-04-01

    Deformation of ice in continental sized ice sheets determines the flow behavior of ice towards the sea. Basal dislocation glide is assumed to be the dominant deformation mechanism in the creep deformation of natural ice, but non-basal glide is active as well. Knowledge of what types of deformation mechanisms are active in polar ice is critical in predicting the response of ice sheets in future warmer climates and its contribution to sea level rise, because the activity of deformation mechanisms depends critically on deformation conditions (such as temperature) as well as on the material properties (such as grain size). One of the methods to study the deformation mechanisms in natural materials is Electron Backscattered Diffraction (EBSD). We obtained ca. 50 EBSD maps of five different depths from a Greenlandic ice core (NEEM). The step size varied between 8 and 25 micron depending on the size of the deformation features. The size of the maps varied from 2000 to 10000 grid point. Indexing rates were up to 95%, partially by saving and reanalyzing the EBSP patterns. With this method we can characterize subgrain boundaries and determine the lattice rotation configurations of each individual subgrain. Combining these observations with arrangement/geometry of subgrain boundaries the dislocation types can be determined, which form these boundaries. Three main types of subgrain boundaries have been recognized in Antarctic (EDML) ice core¹². Here, we present the first results obtained from EBSD measurements performed on the NEEM ice core samples from the last glacial period, focusing on the relevance of dislocation activity of the possible slip systems. Preliminary results show that all three subgrain types, recognized in the EDML core, occur in the NEEM samples. In addition to the classical boundaries made up of basal dislocations, subgrain boundaries made of non-basal dislocations are also common. ¹Weikusat, I.; de Winter, D. A. M.; Pennock, G. M.; Hayles, M

  19. Evolution of the substructure of a novel 12% Cr steel under creep conditions

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Surya Deo, E-mail: surya.yadav@tugraz.at [Institute of Materials Science and Welding, Graz University of Technology, Graz (Austria); Kalácska, Szilvia, E-mail: kalacska@metal.elte.hu [Department of Materials Physics, Eötvös Loránd University, Budapest (Hungary); Dománková, Mária, E-mail: maria.domankova@stuba.sk [Institute of Materials Science of MTF STU, Trnava (Slovakia); Yubero, David Canelo, E-mail: david.caneloyubero@tugraz.at [Institute of Materials Science and Welding, Graz University of Technology, Graz (Austria); Resel, Roland, E-mail: roland.resel@tugraz.at [Institute of Solid State Physics, Graz University of Technology, Graz (Austria); Groma, István, E-mail: groma@metal.elte.hu [Department of Materials Physics, Eötvös Loránd University, Budapest (Hungary); Beal, Coline, E-mail: coline.beal@tugraz.at [Institute of Materials Science and Welding, Graz University of Technology, Graz (Austria); Sonderegger, Bernhard, E-mail: bernhard.sonderegger@tugraz.at [Institute of Materials Science and Welding, Graz University of Technology, Graz (Austria); Sommitsch, Christof, E-mail: christof.sommitsch@tugraz.at [Institute of Materials Science and Welding, Graz University of Technology, Graz (Austria); Poletti, Cecilia, E-mail: cecilia.poletti@tugraz.at [Institute of Materials Science and Welding, Graz University of Technology, Graz (Austria)

    2016-05-15

    In this work we study the microstruture evolution of a newly developed 12% Cr martensitic/ferritic steel in as-received condition and after creep at 650 °C under 130 MPa and 80 MPa. The microstructure is described as consisting of mobile dislocations, dipole dislocations, boundary dislocations, precipitates, lath boundaries, block boundaries, packet boundaries and prior austenitic grain boundaries. The material is characterized employing light optical microscopy (LOM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). TEM is used to characterize the dislocations (mobile + dipole) inside the subgrains and XRD measurements are used to the characterize mobile dislocations. Based on the subgrain boundary misorientations obtained from EBSD measurements, the boundary dislocation density is estimated. The total dislocation density is estimated for the as-received and crept conditions adding the mobile, boundary and dipole dislocation densities. Additionally, the subgrain size is estimated from the EBSD measurements. In this publication we propose the use of three characterization techniques TEM, XRD and EBSD as necessary to characterize all type of dislocations and quantify the total dislocation densty in martensitic/ferritic steels. - Highlights: • Creep properties of a novel 12% Cr steel alloyed with Ta • Experimental characterization of different types of dislocations: mobile, dipole and boundary • Characterization and interpretation of the substructure evolution using unique combination of TEM, XRD and EBSD.

  20. Optimal boundary control and boundary stabilization of hyperbolic systems

    CERN Document Server

    Gugat, Martin

    2015-01-01

    This brief considers recent results on optimal control and stabilization of systems governed by hyperbolic partial differential equations, specifically those in which the control action takes place at the boundary.  The wave equation is used as a typical example of a linear system, through which the author explores initial boundary value problems, concepts of exact controllability, optimal exact control, and boundary stabilization.  Nonlinear systems are also covered, with the Korteweg-de Vries and Burgers Equations serving as standard examples.  To keep the presentation as accessible as possible, the author uses the case of a system with a state that is defined on a finite space interval, so that there are only two boundary points where the system can be controlled.  Graduate and post-graduate students as well as researchers in the field will find this to be an accessible introduction to problems of optimal control and stabilization.

  1. EBSD in Antarctic and Greenland Ice

    Science.gov (United States)

    Weikusat, Ilka; Kuiper, Ernst-Jan; Pennock, Gill; Sepp, Kipfstuhl; Drury, Martyn

    2017-04-01

    Ice, particularly the extensive amounts found in the polar ice sheets, impacts directly on the global climate by changing the albedo and indirectly by supplying an enormous water reservoir that affects sea level change. The discharge of material into the oceans is partly controlled by the melt excess over snow accumulation, partly by the dynamic flow of ice. In addition to sliding over bedrock, an ice body deforms gravitationally under its own weight. In order to improve our description of this flow, ice microstructure studies are needed that elucidate the dominant deformation and recrystallization mechanisms involved. Deformation of hexagonal ice is highly anisotropic: ice is easily sheared in the basal plane and is about two orders of magnitude harder parallel to the c-axis. As dislocation creep is the dominant deformation mechanism in polar ice this strong anisotropy needs to be understood in terms of dislocation activity. The high anisotropy of the ice crystal is usually ascribed to a particular behaviour of dislocations in ice, namely the extension of dislocations into partials on the basal plane. Analysis of EBSD data can help our understanding of dislocation activity by characterizing subgrain boundary types thus providing a tool for comprehensive dislocation characterization in polar ice. Cryo-EBSD microstructure in combination with light microscopy measurements from ice core material from Antarctica (EPICA-DML deep ice core) and Greenland (NEEM deep ice core) are presented and interpreted regarding substructure identification and characterization. We examined one depth for each ice core (EDML: 656 m, NEEM: 719 m) to obtain the first comparison of slip system activity from the two ice sheets. The subgrain boundary to grain boundary threshold misorientation was taken to be 3-5° (Weikusat et al. 2011). EBSD analyses suggest that a large portion of edge dislocations with slip systems basal gliding on the basal plane were indeed involved in forming subgrain

  2. Structural unit/grain boundary dislocation model for twist boundaries in cubic crystals

    Science.gov (United States)

    Bristowe, P. D.; Belluffi, R. W.

    1984-10-01

    The systemics of 001 twist boundary structure is presented formally in terms of a structure unit/grain boundary dislocation (GBD) hierarchical model and the earlier model of Sutton is generalized. By comparison with experimental observation and atomistic calculation using pair potential models, the physical significance of the individual members of the hierarchy is determined. Comparison with experiment indicates a strong 110 type primary relaxation for theta is equal to or 36.9 deg. and a significant secondary relaxation near Sigma 5 which must result from oblique perturbations in the array of primary GBDs. On the other hand, comparison with available calculated results indicate a strong 110 type relaxation at low angles but a progressively weaker relaxation at higher angles. Also, no evidence is found for any significant secondary relaxations when at least one pair potential is employed.

  3. Grain boundary melting in ice

    Science.gov (United States)

    Thomson, E. S.; Hansen-Goos, Hendrik; Wettlaufer, J. S.; Wilen, L. A.

    2013-03-01

    We describe an optical scattering study of grain boundary premelting in water ice. Ubiquitous long ranged attractive polarization forces act to suppress grain boundary melting whereas repulsive forces originating in screened Coulomb interactions and classical colligative effects enhance it. The liquid enhancing effects can be manipulated by adding dopant ions to the system. For all measured grain boundaries this leads to increasing premelted film thickness with increasing electrolyte concentration. Although we understand that the interfacial surface charge densities qs and solute concentrations can potentially dominate the film thickness, we cannot directly measure them within a given grain boundary. Therefore, as a framework for interpreting the data we consider two appropriate qs dependent limits; one is dominated by the colligative effect and other is dominated by electrostatic interactions.

  4. Allegheny County School District Boundaries

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset demarcates the school district boundaries within Allegheny County If viewing this description on the Western Pennsylvania Regional Data Center’s open...

  5. Boundary Layer Control on Airfoils.

    Science.gov (United States)

    Gerhab, George; Eastlake, Charles

    1991-01-01

    A phenomena, boundary layer control (BLC), produced when visualizing the fluidlike flow of air is described. The use of BLC in modifying aerodynamic characteristics of airfoils, race cars, and boats is discussed. (KR)

  6. County Boundaries with Shorelines (National)

    Data.gov (United States)

    Department of Transportation — County boundaries with shorelines cut in (NTAD). The TIGER/Line Files are shapefiles and related database files (.dbf) that are an extract of selected geographic and...

  7. HUC 8-11 Boundaries

    Data.gov (United States)

    Kansas Data Access and Support Center — This data set is a digital hydrologic unit boundary that is at the 4-digit, 6-digit, 8-digit, and 11-digit level. The data set was developed by delineating the...

  8. The laminar boundary layer equations

    CERN Document Server

    Curle, N

    2017-01-01

    Thorough introduction to boundary layer problems offers an ordered, logical presentation accessible to undergraduates. The text's careful expositions of the limitations and accuracy of various methods will also benefit professionals. 1962 edition.

  9. State Highway District Boundaries - 2004

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — This data represents the NM Department of Transportation District boundaries as legislatively defined (i.e. these are not maintenance defined districts).

  10. Boundary Spanners in Global Partnerships

    DEFF Research Database (Denmark)

    Søderberg, Anne-Marie; Romani, Laurence

    2017-01-01

    client relationships and coordinating highly complex projects. We analyze vendor managers’ narratives of their collaboration with a European client in a long-term project, which is presented as a strategic partnership in an outsourcing 3.0 mode. The study offers a rich and conceptualized account of those...... technology (IT) development projects from the rare perspective of Indian vendor managers in one of the world’s largest IT service companies. It draws on a qualitative study of a collaborative partnership and focuses on the key boundary spanners who are responsible for developing trustful and sustainable...... managers’ boundary-spanning activities and a context-sensitive understanding of their boundary work. The study applies Bourdieu’s concept of capital (economic, cultural, social, and symbolic) not only in its analysis of the two powerful partners but also in its discussion of the boundary...

  11. Recognition of boundary feedback systems

    DEFF Research Database (Denmark)

    Pedersen, Michael

    1989-01-01

    A system that has been the object of intense research is outlined. In view of that and recent progress of the theory of pseudodifferential boundary operator calculus, the author describes some features that could prove to be interesting in connection with the problems of boundary feedback...... stabilizability. It is shown that it is possible to use the calculus to consider more general feedback systems in a variational setup....

  12. Robust Shot Boundary Detection from Video Using Dynamic Texture

    Directory of Open Access Journals (Sweden)

    Peng Taile

    2014-03-01

    Full Text Available Video boundary detection belongs to a basis subject in computer vision. It is more important to video analysis and video understanding. The existing video boundary detection methods always are effective to certain types of video data. These methods have relatively low generalization ability. We present a novel shot boundary detection algorithm based on video dynamic texture. Firstly, the two adjacent frames are read from a given video. We normalize the two frames to get the same size frame. Secondly, we divide these frames into some sub-domain on the same standard. The following thing is to calculate the average gradient direction of sub-domain and form dynamic texture. Finally, the dynamic texture of adjacent frames is compared. We have done some experiments in different types of video data. These experimental results show that our method has high generalization ability. To different type of videos, our algorithm can achieve higher average precision and average recall relative to some algorithms.

  13. Boundary Control of Linear Evolution PDEs - Continuous and Discrete

    DEFF Research Database (Denmark)

    Rasmussen, Jan Marthedal

    2004-01-01

    erential equations. This field has mostly concerned engineers and others with practical applications in mind. This thesis makes an attempt to bridge the two research areas. More specifically, we make finite dimensional approximations to certain evolution PDEs, and analyze how properties of the discrete......Consider a partial di erential equation (PDE) of evolution type, such as the wave equation or the heat equation. Assume now that you can influence the behavior of the solution by setting the boundary conditions as you please. This is boundary control in a broad sense. A substantial amount...... systems resemble the properties of the continuous system. A common framework in which the continuous systems are formulated will be provided. The treatment includes many types of linear evolution PDEs and boundary conditions. We also consider di erent types of controllability, such as approximate, null...

  14. Slip systems, lattice rotations and dislocation boundaries

    DEFF Research Database (Denmark)

    Winther, Grethe

    2008-01-01

    Plastic deformation by slip induces rotations of the crystallographic lattice and evolution of dislocation structures. Both lattice rotations and dislocation structures exhibit a dependence on the grain orientation, which reflects underlying relations to the slip pattern. Relations between the type...... of dislocation structure formed, in particular the crystallographic alignment of dislocation boundaries, and the slip pattern are demonstrated. These relations are applied to polycrystals deformed in tension and rolling, producing good agreement with experiment for rolling but less good agreement for tension...... of these discrepancies is discussed. Finally, the implications of the relations between slip and dislocation structures for the modelling of mechanical properties are discussed....

  15. Scalar boundary conditions in hyperscaling violating geometry

    Directory of Open Access Journals (Sweden)

    Jian-Pin Wu

    2016-02-01

    Full Text Available We study the possible boundary conditions of scalar field modes in a hyperscaling violation (HV geometry with Lifshitz dynamical exponent z (z≥1 and hyperscaling violation exponent θ (θ≠0. For the case with θ>0, we show that in the parameter range 1≤z≤2, −z+d−12, −z+d−10, which has been addressed in Ref. [1]. Meanwhile, we also carry out the parallel investigation in the case with θ0, only one type is available.

  16. Universal entanglement and boundary geometry in conformal field theory

    Energy Technology Data Exchange (ETDEWEB)

    Herzog, Christopher P.; Huang, Kuo-Wei; Jensen, Kristan [C.N. Yang Institute for Theoretical Physics, Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (United States)

    2016-01-27

    Employing a conformal map to hyperbolic space cross a circle, we compute the universal contribution to the vacuum entanglement entropy (EE) across a sphere in even-dimensional conformal field theory. Previous attempts to derive the EE in this way were hindered by a lack of knowledge of the appropriate boundary terms in the trace anomaly. In this paper we show that the universal part of the EE can be treated as a purely boundary effect. As a byproduct of our computation, we derive an explicit form for the A-type anomaly contribution to the Wess-Zumino term for the trace anomaly, now including boundary terms. In d=4 and 6, these boundary terms generalize earlier bulk actions derived in the literature.

  17. Boundary slip from the immersed boundary lattice Boltzmann models.

    Science.gov (United States)

    Le, Guigao; Zhang, Junfeng

    2009-02-01

    We report an interesting and important observation of the velocity fields from immersed boundary lattice Boltzmann methods (IB-LBM). The computed velocity profiles can deviate from theoretical predictions greatly even for very simple flow situations, both in the immersed boundary layer and the bulk region. A rigorous analysis of the IB-LBM simulated velocity for a symmetric shear flow is carried out, and the analytical solutions indicate a strong dependence of velocity on the relaxation parameter (kinetic viscosity). Also our simulations demonstrate that simply increasing the immersed boundary layer thickness is not an efficient approach to reduce such velocity discrepancy. We hope this work will bring the awareness of this essential issue to people using IB-LBM for various flow situations.

  18. The boundary-scan handbook

    CERN Document Server

    Parker, Kenneth P

    2016-01-01

    Aimed at electronics industry professionals, this 4th edition of the Boundary Scan Handbook describes recent changes to the IEEE1149.1 Standard Test Access Port and Boundary-Scan Architecture. This updated edition features new chapters on the possible effects of the changes on the work of the practicing test engineers and the new 1149.8.1 standard. Anyone needing to understand the basics of boundary scan and its practical industrial implementation will need this book. Provides an overview of the recent changes to the 1149.1 standard and the effect of the changes on the work of test engineers;   Explains the new IEEE 1149.8.1 subsidiary standard and applications;   Describes the latest updates on the supplementary IEEE testing standards. In particular, addresses: IEEE Std 1149.1                      Digital Boundary-Scan IEEE Std 1149.4                      Analog Boundary-Scan IEEE Std 1149.6                      Advanced I/O Testing IEEE Std 1149.8.1           �...

  19. Undulatory microswimming near solid boundaries

    Science.gov (United States)

    Schulman, R. D.; Backholm, M.; Ryu, W. S.; Dalnoki-Veress, K.

    2014-10-01

    The hydrodynamic forces involved in the undulatory microswimming of the model organism C. elegans are studied in proximity to solid boundaries. Using a micropipette deflection technique, we attain direct and time-resolved force measurements of the viscous forces acting on the worm near a single planar boundary as well as confined between two planar boundaries. We observe a monotonic increase in the lateral and propulsive forces with increasing proximity to the solid interface. We determine normal and tangential drag coefficients for the worm, and find these to increase with confinement. The measured drag coefficients are compared to existing theoretical models. The ratio of normal to tangential drag coefficients is found to assume a constant value of 1.5 ± 0.1(5) at all distances from a single boundary, but increases significantly as the worm is confined between two boundaries. In response to the increased drag due to confinement, we observe a gait modulation of the nematode, which is primarily characterized by a decrease in the swimming amplitude.

  20. Function Substitution in Partial Differential Equations: Nonhomogeneous Boundary Conditions

    Directory of Open Access Journals (Sweden)

    T. V. Oblakova

    2017-01-01

    Full Text Available The paper considers a mixed initial-boundary value problem for a parabolic equation with nonhomogeneous boundary conditions. The classical approach to search for analytical solution of such problems in the first phase involves variable substitution, leading to a problem with homogeneous boundary conditions. Reference materials [1] give, as a rule, the simplest types of variable substitutions where new and old unknown functions differ by a term, linear in the spatial variable. The form of this additive term depends on the type of the boundary conditions, but is in no way related to the equation under consideration. Moreover, in the case of the second boundary-value problem, it is necessary to use a quadratic additive, since a linear substitution for this type of conditions may be unavailable. The courseware [2] - [4], usually, ends only with the first boundary-value problem generally formulated.The paper considers a substitution that takes into account, in principle, the form of a linear differential operator. Namely, as an additive term, it is proposed to use the parametrically time-dependent solution of the boundary value problem for an ordinary differential equation obtained from the original partial differential equation by the method of separation of the Fourier variables.The existence of the proposed substitution for boundary conditions of any type is proved by the example of a non-stationary heat-transfer equation with the heat exchange available with the surrounding medium. In this case, the additive term is a linear combination of hyperbolic functions. It is shown that, in addition to the "insensitivity" to the type of boundary conditions, the advantages of a new substitution in comparison with the traditional linear (or quadratic one include a much simpler structure of the solution obtained. Just the described approach allows us to obtain a solution with a clearly distinguished stationary component, in case a stationarity occurs, for

  1. Asymptotic analysis and boundary layers

    CERN Document Server

    Cousteix, Jean

    2007-01-01

    This book presents a new method of asymptotic analysis of boundary-layer problems, the Successive Complementary Expansion Method (SCEM). The first part is devoted to a general comprehensive presentation of the tools of asymptotic analysis. It gives the keys to understand a boundary-layer problem and explains the methods to construct an approximation. The second part is devoted to SCEM and its applications in fluid mechanics, including external and internal flows. The advantages of SCEM are discussed in comparison with the standard Method of Matched Asymptotic Expansions. In particular, for the first time, the theory of Interactive Boundary Layer is fully justified. With its chapter summaries, detailed derivations of results, discussed examples and fully worked out problems and solutions, the book is self-contained. It is written on a mathematical level accessible to graduate and post-graduate students of engineering and physics with a good knowledge in fluid mechanics. Researchers and practitioners will estee...

  2. Free boundary ballooning mode representation

    Science.gov (United States)

    Zheng, Linjin

    2012-03-01

    Considerable efforts have been made in this field to develop a free boundary ballooning mode representation, which can incorporate the peeling mode stability criterion. Those efforts have not succeeded, simply because the so-called ballooning mode invariance is broken toward plasma edge. This makes 1D description of high n modes at plasma edge become impossible, where n is toroidal mode number. Nevertheless, we prove that the existence of ``half" ballooning mode invariance toward plasma core enables an 1.δ-dimentional representation of the modes, where δ˜O(1/n). This considerably reduces the complicity in investigating high n modes at plasma edge and can be used to study peeling-ballooning modes. This technique can also be useful to extend the 1D calculation of fixed boundary ballooning modes for free boundary ballooning modes. Numerical example will also be presented together with the topological symmetry analysis.

  3. Boundary Value Problems and Approximate Solutions ...

    African Journals Online (AJOL)

    In this paper, we discuss about some basic things of boundary value problems. Secondly, we study boundary conditions involving derivatives and obtain finite difference approximations of partial derivatives of boundary value problems. The last section is devoted to determine an approximate solution for boundary value ...

  4. Boundary Spanners as supports of social capital

    DEFF Research Database (Denmark)

    Vincenti, Gordon

    2016-01-01

    Boundary Spanners are important agenets of supporting the capacity building of local neighbourhoods and of sustainable social captial the article focuses on the skills and competnces adn role of Boundary Spanners.......Boundary Spanners are important agenets of supporting the capacity building of local neighbourhoods and of sustainable social captial the article focuses on the skills and competnces adn role of Boundary Spanners....

  5. Boundary Transgressions: An Issue In Psychotherapeutic Encounter ...

    African Journals Online (AJOL)

    Boundary transgressions tend to be conceptualized on a continuum ranging from boundary crossings to boundary violations. Boundary crossings (e.g. accepting an inexpensive holiday gift from a client, unintentionally encountering a client in public, or attending a client's special event) are described in the literature as ...

  6. Drawing boundaries : boundary arrangements of the IPCC working groups

    NARCIS (Netherlands)

    Christel van Eck

    2016-01-01

    The present research investigates how the IPCC’s Working Groups safeguard their scientific character while communicating with policymakers. Due to the different nature of Working Groups’ assessments, all Working Groups make different boundary arrangements of how science is defined; what is

  7. An updated digital model of plate boundaries

    Science.gov (United States)

    Bird, Peter

    2003-03-01

    A global set of present plate boundaries on the Earth is presented in digital form. Most come from sources in the literature. A few boundaries are newly interpreted from topography, volcanism, and/or seismicity, taking into account relative plate velocities from magnetic anomalies, moment tensor solutions, and/or geodesy. In addition to the 14 large plates whose motion was described by the NUVEL-1A poles (Africa, Antarctica, Arabia, Australia, Caribbean, Cocos, Eurasia, India, Juan de Fuca, Nazca, North America, Pacific, Philippine Sea, South America), model PB2002 includes 38 small plates (Okhotsk, Amur, Yangtze, Okinawa, Sunda, Burma, Molucca Sea, Banda Sea, Timor, Birds Head, Maoke, Caroline, Mariana, North Bismarck, Manus, South Bismarck, Solomon Sea, Woodlark, New Hebrides, Conway Reef, Balmoral Reef, Futuna, Niuafo'ou, Tonga, Kermadec, Rivera, Galapagos, Easter, Juan Fernandez, Panama, North Andes, Altiplano, Shetland, Scotia, Sandwich, Aegean Sea, Anatolia, Somalia), for a total of 52 plates. No attempt is made to divide the Alps-Persia-Tibet mountain belt, the Philippine Islands, the Peruvian Andes, the Sierras Pampeanas, or the California-Nevada zone of dextral transtension into plates; instead, they are designated as "orogens" in which this plate model is not expected to be accurate. The cumulative-number/area distribution for this model follows a power law for plates with areas between 0.002 and 1 steradian. Departure from this scaling at the small-plate end suggests that future work is very likely to define more very small plates within the orogens. The model is presented in four digital files: a set of plate boundary segments; a set of plate outlines; a set of outlines of the orogens; and a table of characteristics of each digitization step along plate boundaries, including estimated relative velocity vector and classification into one of 7 types (continental convergence zone, continental transform fault, continental rift, oceanic spreading ridge

  8. Boundary works of Grindr research

    DEFF Research Database (Denmark)

    Jørgensen, Kristian Møller

    . It can be understood as arising from boundary works (Jamieson 2005, [Auhor of this paper] forthcoming) and thus be ontologically entangled with the meeting of the prospect of boundary transgression that marks the end of intimacy. Lauren Berlant on the other hand sees intimacy as: …the processes by which....... Communications, 36(1), 91–111. Lundby, K. (ed.) (2014). Mediatization of Communication: Handbooks of Communication Science, vol. 21. Berlin: De Gruyter Mouton. Marwick, A., & Boyd, D. (2014). Networked privacy: How teenagers negotiate context in social media. New Media & Society. Markham, A., & Buchanan, E...

  9. Boundary effect in electrorheological fluids.

    Science.gov (United States)

    Gong, X L; Yang, F; Xuan, S H; Zong, L H; Zhu, W; Jiang, W Q

    2011-12-01

    The effect of the boundary friction coefficient on the rheological properties of the electrorheological (ER) fluids in quasistatic and dynamic states is investigated by computer simulation. The relation between the shear stress and the boundary friction coefficient in quasistatic and dynamic states is discussed qualitatively and quantitatively, and the trend matches the previously reported experimental results well. The flow curves of ER fluids, under different friction coefficients, are calculated, and it is found that the friction coefficient affects the flow curves. In two dimensions, the transitions in structure corresponding to the shear stress variations are presented to understand the mechanism of ER fluids.

  10. Information dynamics of boundary perception

    DEFF Research Database (Denmark)

    Kragness, Haley; Hansen, Niels Christian; Vuust, Peter

    It has long been noted that expert musicians lengthen notes at phrase boundaries in expressive performance. Recently, we have extended research on this phenomenon by showing that undergraduates with no formal musical training and children as young as 3 years lengthen phrase boundaries during self......-paced listening to chord sequences in a lab setting (the musical dwell-time effect). However, the origin of the musical dwell-time effect is still unknown. Recent work has demonstrated that musicians and non-musicians are sensitive to entropy in musical sequences, experiencing high-entropy contexts as more...

  11. Tropical cyclone boundary layer shocks

    OpenAIRE

    Slocum, Christopher J.; Williams, Gabriel J.; Taft, Richard K.; Wayne H. Schubert

    2014-01-01

    This paper presents numerical solutions and idealized analytical solutions of axisymmetric, $f$-plane models of the tropical cyclone boundary layer. In the numerical model, the boundary layer radial and tangential flow is forced by a specified pressure field, which can also be interpreted as a specified gradient balanced tangential wind field $v_{\\rm gr}(r)$ or vorticity field $\\zeta_{\\rm gr}(r)$. When the specified $\\zeta_{\\rm gr}(r)$ field is changed from one that is radially concentrated i...

  12. Effect of secondary relaxations on diffraction from high-Σ [001] twist boundaries

    Science.gov (United States)

    Bristowe, P. D.; Balluffi, R. W.

    1984-08-01

    The types of diffraction effects which may be expected from secondary relaxations in high-Σ [001] twist boundaries are calculated and discussed. An idealized two-plane model is used which incorporates secondary relaxations by rotating patches of boundary about coincident site lattice elements normal to the boundary. Local relaxations within the patches are also employed using rotational relaxations about local O-lattice elements in a manner consistent with earlier results. The main effect of secondary relaxations is the splitting of grain boundary reflections into small clusters which fall on a "grain boundary dislocation lattice". This localized splitting is significant only when the deviation of the boundary from a nearby low-Σ misorientation becomes sufficiently large. Under these circumstances a noticeable distortion of the diffraction pattern can also occur. The results are compared with some X-ray diffraction observations from twist boundaries in gold.

  13. Negotiation of territorial boundaries in a songbird.

    Science.gov (United States)

    Vehrencamp, Sandra L; Ellis, Jesse M; Cropp, Brett F; Koltz, John M

    2014-11-01

    How do territorial neighbors resolve the location of their boundaries? We addressed this question by testing the predictions of 2 nonexclusive game theoretical models for competitive signaling: the sequential assessment game and the territorial bargaining game. Our study species, the banded wren, is a neotropical nonmigratory songbird living in densely packed territorial neighborhoods. The males possess repertoires of approximately 25 song types that are largely shared between neighbors and sequentially delivered with variable switching rates. Over 3 days, boundary disputes among pairs of neighboring males were synchronously recorded, their perch positions were marked, and their behavioral interactions were noted. For each countersinging interaction between 2 focal males, we quantified approach and retreat order, a variety of song and call patterns, closest approach distance, distance from the territorial center, and female presence. Aggressors produced more rattle-buzz songs during the approaching phase of interactions, whereas defenders overlapped their opponent's songs. During the close phase of the interaction, both males matched frequently, but the key determinant of which one retreated first was song-type diversity-first retreaters sang with a higher diversity. Retreaters also produced more unshared song types during the interaction, and in the retreating phase of the interaction, they overlapped more. A negative correlation between song-type diversity asymmetry and contest duration suggested sequential assessment of motivational asymmetry. The use of this graded signal, which varied with distance from the center and indicated a male's motivation to defend a particular position, supported the bargaining model. The bargaining game could be viewed as a series of sequential assessment contests.

  14. Computer simulation study of the structure of vacancies in grain boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Brokman, A.; Bristowe, P.D.; Balluffi, R.W.

    1981-10-01

    The structure of vacancies in grain boundaries has been investigated by computer molecular statics employing pairwise potentials. In order to gain an impression of the vacancy structures which may occur generally, a number of variables was investigated, including metal type, boundary type, degree of lattice coincidence, and choice of boundary site. In all cases the vacancies remained as distinguishable point defects in the relatively irregular boundary structures. However, it was found that the vacancy often induced relatively large atomic displacements in the core of the boundary. These displacements often occurred only in the direct vicinity of the vacancy, but in certain cases they were widely distributed in the boundary, sometimes at surprisingly large distances. In certain cases the displacements included a large inward relaxation of one, or more, of the atoms neighboring the vacancy, and the initial vacant site became effectively ''split''.

  15. Computer simulation study of the structure of vacancies in grain boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Brokman, A.; Bristowe, P.D.; Balluffi, R.W.

    1981-01-01

    The structure of vacancies in grain boundaries has been investigated by computer molecular statics employing pairwise potentials. In order to gain an impression of the vacancy structures which may occur generally, a number of variables was investigated including: metal type, boundary type, degree of lattice coincidence and choice of boundary site. In all cases the vacancies remained as distinguishable point defects in the relatively irregular boundary structures. However, it was found that the vacancy often induced relatively large atomic displacements in the core of the boundary. These displacements often occurred only in the direct vicinity of the vacancy, but in certain cases they were widely distributed in the boundary, sometimes at surprisingly large distances.

  16. Onset of Grain Boundary Migration and Drastic Weakening of Quartzite during increasing grade of Metamorphism in the Contact Aureole surrounding the Eureka Valley-Joshua Flat-Beer Creek pluton, California, USA

    Science.gov (United States)

    Morgan, S. S.; Student, J. J.; Jakeway, J.

    2015-12-01

    The Eureka Valley-Joshua Flat-Beer Creek (EJB) pluton in eastern California is surrounded by a ~1.3 km wide intensely deformed concordant aureole of metasedimentary rocks. South of the pluton, the Harkless Quartzite can be mapped from where it is located outside the aureole, with its regional strike through the transition into the aureole and concordancy with the pluton. The transition into concordancy, which is fairly abrupt, occurs over a distance of less than 100 m. Across this transition the bedding rotates close to 90° to become subvertical. Here the metasedimentary formations in the aureole have undergone 65% shortening. A suite of Harkless Quartzite samples was collected starting at 2.3 km south of the pluton, across the transition into concordancy at 1.3 km, and to within 450m from the pluton contact. Microstructurally, the transition is defined by changes in the dominant recrystallization mechanisms. At 2.3 km from the pluton, subgrain rotation recrystallization (SGR) plus grain boundary migration (GBM) operate together and many sedimentary grains (rounded grain boundaries) exist. As the pluton is approached, SGR decreases, GBM increases, and rounded grain boundaries slowly disappear. The abrupt transition into concordancy is marked by the final disappearance of SGR and rounded grain boundaries and extensive GBM. The transition is not completely smooth, and other variables such as pinning and amount of fluid inclusions seem to have a strong local affect on the dominant recrystallization mechanism. We suspect that the onset of extensive GBM allows for the diffusion of water into the crystal lattice which results in the drastic weakening and rotation of metasedimentary formations into concordancy.

  17. Plant communities of field boundaries in Finnish farmland

    Directory of Open Access Journals (Sweden)

    S. TARMI

    2008-12-01

    Full Text Available To determine the importance of field boundary habitats for farmland biodiversity, we surveyed a total of 193 boundaries from four climatically and agriculturally dissimilar regions in Finland. We measured the current plant species richness and composition of the boundaries, and based on the differences in vegetation characteristics, we describe six boundary types. The observed plant species were mainly indicators of fresh to wet soils and moderate to rich mineral nitrogen content. The most frequent species were tall, perennial monocots and dicots indicating the high productivity of thevegetation. Moreove, herbicide-tolerant species were common. No species rare for Finland were found.In animal husbandry regions, the most frequent species were sown grassland species and typical grassland weeds. In cereal production regions, fast-spreading root weeds tolerant of herbicides were the most frequent. Mean species richness was highest in the cluster Ca-lamagrostis-Phalaris (24 species (s/boundary (b, which we considered as representative of moist sites with some disturbance by agricultural practices. Most species-poor were the clusters Elymus-Anthriscus (14 s/band Elymus-Cirsium (16 s/b,both found predominantly in cereal production regions in southern Finland. Our results suggest that the biodiversity value of boundaries is lowest in the most intensive cereal production areas and highest in areas of mixed farming.;

  18. Seismic link at plate boundary

    Indian Academy of Sciences (India)

    ... tested using the coherence of time series to determine the causality and related orientation. The resulting link orientations at the plate boundary conditions indicate that causal triggering seems to be localized along a major fault, as a stress transfer between two major faults, and parallel to the geothermal area extension.

  19. Current Sinkhole Boundaries in Iowa

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This dataset is a polygon coverage of the sinkhole boundaries as determined by using LiDAR data. The polygons relate to the point coverage using the KPolyID field in...

  20. Humor styles and symbolic boundaries

    NARCIS (Netherlands)

    Kuipers, G.

    2009-01-01

    Humor is strongly related to group boundaries. Jokes and other humorous utterances often draw on implicit references and inside knowledge; they tend to refer to sensitive topics which may offend people; and they ideally incite laughter, one of the strongest markers of social solidarity and emotional

  1. On Boundaries in Linguistic Continua.

    Science.gov (United States)

    Jorgensen, J. Normann; Kristensen, Kjeld

    1995-01-01

    Discusses the notion of regional standards of a language with regard to modern Danish. Regional and national standards of a language as well as local dialect are defined. The article shows that, for a geographical entity, a statistically determined boundary can be established in the range between the extremes of a regional dialect and national…

  2. 'Regime shopping' across (blurring) boundaries

    NARCIS (Netherlands)

    Houwerzijl, M.S.; Evju, Stein

    2014-01-01

    This book chapter identifies and explores the (blurring) boundaries between the legal regimes for labour mobility across the EU. In the context of - what is sometimes called - 'regime shopping' a close look is taken into the law on freedom of movement within the EU. Several categories of

  3. the Martian atmospheric boundary layer

    DEFF Research Database (Denmark)

    Petrosyan, A.; Galperin, B.; Larsen, Søren Ejling

    2011-01-01

    The planetary boundary layer (PBL) represents the part of the atmosphere that is strongly influenced by the presence of the underlying surface and mediates the key interactions between the atmosphere and the surface. On Mars, this represents the lowest 10 km of the atmosphere during the daytime...

  4. BRIDGES ACROSS AFRICA'S INTERNATIONAL BOUNDARIES ...

    African Journals Online (AJOL)

    The empirical data for this paper is drawn from the ethnic minorities divided along and astride the Cross River borderlands with southern Cameroon. Scholars who have studied the Nigeria Cameroon Boundary tend to lay more emphasis on the state centric perspective that continues to operate largely within the framework ...

  5. Editorial: Environmentalists without Boundaries | Ogunseitan ...

    African Journals Online (AJOL)

    African Journal of Environmental Science and Technology. Journal Home · ABOUT · Advanced Search · Current Issue · Archives · Journal Home > Vol 3, No 3 (2009) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register. Editorial: Environmentalists without Boundaries.

  6. Initializing a Mesoscale Boundary-Layer Model with Radiosonde Observations

    Science.gov (United States)

    Berri, Guillermo J.; Bertossa, Germán

    2018-01-01

    A mesoscale boundary-layer model is used to simulate low-level regional wind fields over the La Plata River of South America, a region characterized by a strong daily cycle of land-river surface-temperature contrast and low-level circulations of sea-land breeze type. The initial and boundary conditions are defined from a limited number of local observations and the upper boundary condition is taken from the only radiosonde observations available in the region. The study considers 14 different upper boundary conditions defined from the radiosonde data at standard levels, significant levels, level of the inversion base and interpolated levels at fixed heights, all of them within the first 1500 m. The period of analysis is 1994-2008 during which eight daily observations from 13 weather stations of the region are used to validate the 24-h surface-wind forecast. The model errors are defined as the root-mean-square of relative error in wind-direction frequency distribution and mean wind speed per wind sector. Wind-direction errors are greater than wind-speed errors and show significant dispersion among the different upper boundary conditions, not present in wind speed, revealing a sensitivity to the initialization method. The wind-direction errors show a well-defined daily cycle, not evident in wind speed, with the minimum at noon and the maximum at dusk, but no systematic deterioration with time. The errors grow with the height of the upper boundary condition level, in particular wind direction, and double the errors obtained when the upper boundary condition is defined from the lower levels. The conclusion is that defining the model upper boundary condition from radiosonde data closer to the ground minimizes the low-level wind-field errors throughout the region.

  7. Initializing a Mesoscale Boundary-Layer Model with Radiosonde Observations

    Science.gov (United States)

    Berri, Guillermo J.; Bertossa, Germán

    2017-08-01

    A mesoscale boundary-layer model is used to simulate low-level regional wind fields over the La Plata River of South America, a region characterized by a strong daily cycle of land-river surface-temperature contrast and low-level circulations of sea-land breeze type. The initial and boundary conditions are defined from a limited number of local observations and the upper boundary condition is taken from the only radiosonde observations available in the region. The study considers 14 different upper boundary conditions defined from the radiosonde data at standard levels, significant levels, level of the inversion base and interpolated levels at fixed heights, all of them within the first 1500 m. The period of analysis is 1994-2008 during which eight daily observations from 13 weather stations of the region are used to validate the 24-h surface-wind forecast. The model errors are defined as the root-mean-square of relative error in wind-direction frequency distribution and mean wind speed per wind sector. Wind-direction errors are greater than wind-speed errors and show significant dispersion among the different upper boundary conditions, not present in wind speed, revealing a sensitivity to the initialization method. The wind-direction errors show a well-defined daily cycle, not evident in wind speed, with the minimum at noon and the maximum at dusk, but no systematic deterioration with time. The errors grow with the height of the upper boundary condition level, in particular wind direction, and double the errors obtained when the upper boundary condition is defined from the lower levels. The conclusion is that defining the model upper boundary condition from radiosonde data closer to the ground minimizes the low-level wind-field errors throughout the region.

  8. Approximate solution to a singular perturbed boundary value problem of thermal shielding

    Science.gov (United States)

    Latypov, I. I.

    2017-11-01

    The paper aims to investigate the problem of distribution of a non-regular, non-steady-state thermal field in the porous thermal shield material irradiated by a high flow of energy. A mathematical model of the original problem is stated in the form of a singular perturbed boundary value problem of a thermal conductivity equation with the nonlinear boundary conditions on moving boundaries. Its solution is obtained as asymptotic Poincare-type expansions in powers of small parameters.

  9. Molecular dynamics simulation of grain-boundary diffusion of vacancies in bcc iron

    Science.gov (United States)

    Kwok, T.; Ho, P. S.; Yip, S.; Balluffi, R.; Brokman, A. W.; Bristowe, P. D.

    1981-06-01

    The jumping of vacancies in a bcc iron sigma = 5 tilt boundary was simulated by computer molecular dynamics. The data yielded a reasonable value of the activation energy for migration and showed that the jump processes are highly structure dependent. The use of a temperature dependent transition probability matrix to describe the diffusion of the vacancies in the grain boundary is suggested. Formation of one type of boundary interstitial was observed which was found to be immobile.

  10. Molecular dynamics simulation of grain-boundary diffusion of vacancies in bcc iron

    Energy Technology Data Exchange (ETDEWEB)

    Kwok, T.; Ho, P. S.; Yip, S.; Balluffi, R. W.; Bristowe, P. D.; Brokman, A.

    1981-06-01

    The jumping of vacancies in a bcc iron ..sigma.. = 5 tilt boundary was simulated by computer molecular dynamics. The data yielded a reasonable value of the activation energy for migration and showed that the jump processes are highly structure-dependent. The use of a temperature dependent transition probability matrix to describe the diffusion of the vacancies in the grain boundary is suggested. Formation of one type of boundary interstitial was observed which was found to be immobile.

  11. Periodic and boundary value problems for second order differential ...

    Indian Academy of Sciences (India)

    Abstract. In this paper we study second order scalar differential equations with. Sturm–Liouville and periodic boundary conditions. The vector field fًt; x; yق is. Caratheodory and in some instances the continuity condition on x or y is replaced by a monotonicity type hypothesis. Using the method of upper and lower solutions as ...

  12. Nonlinear initial boundary-value problems with Riesz fractional derivative

    Directory of Open Access Journals (Sweden)

    Martin P. Arciga-Alejandre

    2015-11-01

    Full Text Available We consider an initial boundary-value problem for a nonlinear partial differential equation with fractional derivative of Riesz type on a half-line. We study local and global existence of solutions in time, as well as the asymptotic behavior of solutions for large time.

  13. Grain Boundary Engineering of Electrodeposited Thin Films

    DEFF Research Database (Denmark)

    Alimadadi, Hossein

    of the favorable boundaries that break the network of general grain boundaries. Successful dedicated synthesis of a textured nickel film fulfilling the requirements of grain boundary engineered materials, suggests improved boundary specific properties. However, the textured nickel film shows fairly low......Grain boundary engineering aims for a deliberate manipulation of the grain boundary characteristics to improve the properties of polycrystalline materials. Despite the emergence of some successful industrial applications, the mechanism(s) by which the boundary specific properties can be improved...... to engineer new materials. In this study, one of the most widely used electrolytes for electrodeposition is chosen for the synthesis of nickel films and based on thorough characterization of the boundaries the potentials in grain boundary engineering are outlined. The internal structure of the nickel films...

  14. Structural unit/grain boundary dislocation model for grain boundary structure

    Science.gov (United States)

    Balluffi, R. W.; Bristowe, P. D.

    1983-12-01

    The applicability of the structural unit/grain boundary dislocation (GBD) model to recently calculated core structures of a number of series of boundaries is considered. The following questions are posed: (1) Is there a best choice of structural units? (2) Can the distortions of these units be understood in a systematic way? (3) Are the distortions of the units of a given type sufficiently small to justify the model? Questions (1) and (2) are discussed in detail and answered affirmatively. The answer to Question (3) is qualified. Relaxations occur in all boundaries tested which tend to improve the uniformity of the units, localize the corresponding GBDs and, hence, increase the applicability of the model. The model therefore stands as the most physically viable model for representing the systmatics of the computed core structures. However, in some cases, these relaxations are relatively weak, the units exhibit significant systematic distortions, and the corresponding GBDs are partially delocalized. In such cases the model must be considered an approximation, particularly for many quantitative purposes.

  15. Structural unit/grain boundary dislocation model for grain boundary structure

    Energy Technology Data Exchange (ETDEWEB)

    Balluffi, R.W.; Bristowe, P.D.

    1983-12-01

    The applicability of the structural unit/grain boundary dislocation (GBD) model to recently calculated core structures of a number of series of boundaries is considered. The following questions are posed: (1) Is there a best choice of structural units. (2) Can the distortions of these units be understood in a systematic way. (3) Are the distortions of the units of a given type sufficiently small to justify the model. Questions (1) and (2) are discussed in detail and answered affirmatively. The answer to Question (3) is qualified. It is pointed out that relaxations occur in all boundaries tested which tend to improve the uniformity of the units, localize the corresponding GBDs and, hence, increase the applicability of the model. The model therefore stands as the most physically viable model for representing the systematics of the computed core structures. However, in some cases, these relaxations are relatively weak, the units exhibit significant systematic distortions, and the corresponding GBDs are partially delocalized. In such cases the model must be considered an approximation, particularly for many quantitative purposes.

  16. Memory boundary feedback stabilization for Schrodinger equations with variable coefficients

    Directory of Open Access Journals (Sweden)

    Abdesselam Nawel

    2017-05-01

    Full Text Available First we consider the boundary stabilization of Schrodinger equations with constant coefficient memory feedback. This is done by using Riemannian geometry methods and the multipliers technique. Then we explore the stabilization limits of Schrodinger equations whose elliptical part has a variable coefficient. We established the exponential decay of solutions using the multipliers techniques. The introduction of dissipative boundary conditions of memory type allowed us to obtain an accurate estimate on the uniform rate of decay of the energy for Schrodinger equations.

  17. A Method of Computing Electric Field Parameters on Boundaries between Two Media

    Science.gov (United States)

    Rizhov, Alexander

    2010-01-01

    Many problems of electric field strength on a boundary between two media require college-level mathematical analysis. However, when the boundary between media is represented by a sphere or a flat plane, these types of problems can be solved algebraically, placing them within reach of high school students. This article presents a solution analysis…

  18. Scientific advice and public policy: expert advisers' and policymakers' discourses on boundary work

    NARCIS (Netherlands)

    Hoppe, Robertus

    2008-01-01

    This article reports on considerable variety and diversity among discourses on their own jobs of boundary workers of several major Dutch institutes for science-based policy advice. Except for enlightenment, all types of boundary arrangements/work in the Wittrock-typology (Social knowledge and public

  19. Social Entrepreneurship: Definition and Boundaries

    Directory of Open Access Journals (Sweden)

    Samer Abu-Saifan

    2012-02-01

    Full Text Available While individuals may be publicly recognized as social entrepreneurs for their contributions to improve the welfare of communities, the field of social entrepreneurship continues to struggle to gain academic legitimacy. Social entrepreneurship is a term in search of a good definition. The current use of the term seems vague and limitless; it needs boundaries to demarcate its function. The lack of a common definition hinders research and raises questions about which social or profit-making activities fall within the spectrum of social entrepreneurship. To become an important stream in the entrepreneurship literature, social entrepreneurship needs to be properly defined and it requires a theoretical framework that links it to the theory of entrepreneurship. This article builds on the literature to define social entrepreneurship, discusses the boundaries of socially-oriented entrepreneurial activities, and positions the social entrepreneur in the spectrum of entrepreneurship.

  20. Defining Our National Cyberspace Boundaries

    Science.gov (United States)

    2010-02-17

    took place within our national cyberspace boundaries. 14. ABSTRACT Cyber Borders, Cyberspace National Policy, Convention On The Law Of Cyberspace... The Law Of Cyberspace, Cyberspace Law, Cyberspace Theory CLASSIFICATION: Unclassified In February 2009, the Obama Administration...Justinian” to the more recent United Nations “Convention on the Law of the Sea” approved in 1982 by 150 12 countries.22 Risk is an area that is not as

  1. Equilibrium composition of interphase boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Wynblatt, P.

    1990-01-01

    Two modeling approaches have been used to investigate segregation effects at interphase boundaries. The first approach is based on the nearest neighbor bond model, used in conjunction with the regular solution approximation, and is an extension of an earlier framework developed to address segregation phenomena at free surfaces. In order to model a semicoherent interphase boundary, we have employed a second modeling approach, based on Monte Carol simulation, in conjunction with the embedded atom method (EAM). The EAM is a powerful new method for describing interatomic interactions in metallic systems. It includes certain many-body interactions that depend on the local environment of an atom. The Monte Carol approach has been applied to semicoherent interphase boundaries in Cu-Ag-Au alloys dilute in Au. These alloys consist of coexisting Cu-rich and Ag-rich phases, which differ in lattice constant by about 12%, such that good matching across in interface occurs when nine structural units of the Cu-rich phase are opposed to eight structural units of the Ag-rich phase. Thus far, interfaces with two different orientations have been studied: {l brace}001{r brace}-Cu//{l brace}001{r brace}-Ag, {l angle}110{r angle}-Cu//{l angle}110{r angle}-Ag; and {l brace}111{r brace}-Cu//{l brace}111{r brace}-Ag, {l angle}110{r angle}-Cu//{l angle}110{r angle}-Ag. These two interfaces will be referred to as the (001) and (111) interphase boundaries, for short. 18 refs.

  2. Bridging boundaries: CORBA in perspective.

    OpenAIRE

    Cahill, Vinny; Baker, Sean; Nixon, Paddy

    1997-01-01

    peer-reviewed peer-reviewed applications that cross the boundaries of different computing machines, operating systems, and programming languages are increasingly the norm. As a result, the need for what might be called ???bridging technologies??? to develop software that works across heterogeneous environments has become more compelling. The Common Object Request Broker Architecture is one such technology that is both robust and commercially available. CORBA essentially describes...

  3. Bridging boundaries: CORBA in perspective.

    OpenAIRE

    Cahill, Vinny

    1997-01-01

    PUBLISHED pplications that cross the boundaries of different computing machines, operating systems, and programming languages are increasingly the norm. As a result, the need for what might be called ?bridging technologies? to develop software that works across heterogeneous environments has become more compelling. The Common Object Request Broker Architecture is one such technology that is both robust and commercially available. CORBA essentially describes how client app...

  4. Working across Boundaries in Design

    DEFF Research Database (Denmark)

    Clausen, Christian; Yoshinaka, Yutaka

    The paper addresses how insights from the social shaping tradition and political process theory may contribute to an understanding of design as staging of sociotechnical relations and processes cutting across boundaries of diverse organisational, political and knowledge domains. This idea is purs...... organisational practices. One implication of this approach includes an attention towards what (and how) ar-eas may be rendered open to negotiation and transformation in technological design, implementation, and change processes....

  5. Teacher professional boundaries: online & offline

    OpenAIRE

    Morris, Zoe Anna

    2017-01-01

    The 21st century has emerged as an era of accountability and standardisation for the teaching profession (Mikulec & Miller, 2012). The current research is comprised of 4 interrelated empirical studies which measure and explore individual differences in perceptions of teacher-student boundaries in the secondary school context from an ethical perspective. This research is timely given it has been 8 years since the Teacher Code of Conduct was introduced in Victoria (The Institute, 2008). While t...

  6. Modelling near subsurface temperature with mixed type boundary ...

    Indian Academy of Sciences (India)

    geothermal data to extract both climate and groundwater flow signals. 1. Introduction. There is great interest to know past climate, especially to infer any anthropogenic signals in present climate by inter-comparison. The obser- vations of subsurface thermal regime in boreholes have been used to infer earth's thermal history.

  7. Borders, boundaries and desirable wishes

    Directory of Open Access Journals (Sweden)

    Luca Pinciaroli

    2015-05-01

    Full Text Available “Borders, boundaries and desirable wishes” is the title of the residential workshop offered to a group of young adults (aged 18-25 of the Centro di Salute Mentale (Mental Health Center of the DSM Basaglia of ASL TO2 in Turin. The idea of the workshop, the definition of the objectives and the topics, which are clearly expressed in the title, come from the work of the team dedicated to group psychotherapies, which has been offering group psychodrama sessions to young adults of this age since 2008. In the delicate move to the adult age, these young adults are lost and stuck in static realities where it is not possible to open up to the dimension of desire nor to the transforming encounter with the Other, since they didn’t have the experience of boundaries and lack. These two elements are necessary to acquire the ability to make projects for oneself. During the workshop the following instruments were used: group, psychodrama and art therapy. The group, as a paternal function, ensured the presence of safe boundaries enabling individuals to experiment; psychodrama and art therapy enabled the bodies to experience encounters and transformations, using doing as a metaphor for the movement against the inhibition of doing and as a way to show oneself to the Other and be able to see the Other. 

  8. Boundary detection via dynamic programming

    Science.gov (United States)

    Udupa, Jayaram K.; Samarasekera, Supun; Barrett, William A.

    1992-09-01

    This paper reports a new method for detecting optimal boundaries in multidimensional scene data via dynamic programming (DP). In its current form the algorithm detects 2-D contours on slices and differs from other reported DP-based algorithms in an essential way in that it allows freedom in 2-D for finding optimal contour paths (as opposed to a single degree of freedom in the published methods). The method is being successfully used in segmenting object boundaries in a variety of medical applications including orbital volume from CT images (for craniofacial surgical planning), segmenting bone in MR images for kinematic analysis of the joints of the foot, segmenting the surface of the brain from the inner surface of the cranial vault, segmenting pituitary gland tumor for following the effect of a drug on the tumor, segmenting the boundaries of the heart in MR images, and segmenting the olfactory bulb for verifying hypotheses related to the size of this bulb in certain disease states.

  9. Morality and boundaries in Paul

    Directory of Open Access Journals (Sweden)

    Bert Jan Lietaert Peerbolte

    2012-01-01

    Full Text Available In the Pauline communities, ethics, ethos and identity were closely intertwined. This essay analyses the way in which Paul emphasised the mental boundaries of the Christ communities to turn them into moral boundaries. In this process, the fencing off of these communities over against their past and their present was a fundamental feature of Paul’s reasoning. The communities thus became fenced off from their past, because the Christ event was seen as causing a major change in history. This change affected both Gentile and Jewish believers. At the same time, Paul stressed the boundaries with the outside world: he characterised the inside world as the loyal remnant of Israel, consisting of Jews and Gentiles alike, and pointed out that this group is the group of the elect ‘saints’. The perspective with which Paul looked at ethics and morality inside this group was strongly coloured by the assumed identity of this group as ‘Israel’. Even though the Mosaic Law was no longer the focal point for the identity of this eschatological Israel, the ethical demands Paul mentioned over against the members of this new Israel were highly influenced by the morality of the law. For Paul, sanctification was a fundamental ideal, and this ideal reflected the spirituality of the Holiness Code of Leviticus. This particular ethical model was framed by the awareness that Paul (and Christ before him was ‘sent’ by God, much in the same way the prophets of Israel themselves had been sent.

  10. Effective nonlinear Neumann boundary conditions for 1D nonconvex Hamilton-Jacobi equations

    Science.gov (United States)

    Guerand, Jessica

    2017-09-01

    We study Hamilton-Jacobi equations in [ 0 , + ∞) of evolution type with nonlinear Neumann boundary conditions in the case where the Hamiltonian is not necessarily convex with respect to the gradient variable. In this paper, we give two main results. First, we prove for a nonconvex and coercive Hamiltonian that general boundary conditions in a relaxed sense are equivalent to effective ones in a strong sense. Here, we exhibit the effective boundary conditions while for a quasi-convex Hamiltonian, we already know them (Imbert and Monneau, 2016). Second, we give a comparison principle for a nonconvex and nonnecessarily coercive Hamiltonian where the boundary condition can have constant parts.

  11. Large time behavior of solutions to parabolic equations with Neumann boundary conditions

    Science.gov (United States)

    da Lio, Francesca

    2008-03-01

    In this paper we are interested in the large time behavior as t-->+[infinity] of the viscosity solutions of parabolic equations with nonlinear Neumann type boundary conditions in connection with ergodic boundary problems which have been recently studied by Barles and the author in [G. Barles, F. Da Lio, On the boundary ergodic problem for fully nonlinear equations in bounded domains with general nonlinear Neumann boundary conditions, Ann. Inst. H. Poincaré Anal. Non Linèaire 22 (5) (2005) 521-541].

  12. Evidence for Vacancy Mechanism in Grain Boundary Diffusion in bcc Iron: A Molecular-Dynamics Study

    Science.gov (United States)

    Kwok, Thomas; Ho, P. S.; Yip, Sidney; Balluffi, R. W.; Bristowe, P. D.; Brokman, A.

    1981-10-01

    The dominance of vacancy migration in grain boundary self-diffusion has been established by molecular-dynamics simulation of a bcc iron Σ=5 tilt boundary. The data yielded a reasonable value of the activation energy for migration and showed that the jump processes are highly structure dependent. The use of a temperature-dependent transition-probability matrix to describe the diffusion of the vacancies in the grain boundary is suggested. Formation of one type of boundary interstitial was observed, and the interstitial was found to be immobile during its lifetime.

  13. Sage-grouse Conservation Assessment Boundary

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Boundary of the conservation assessment of Greater Sage-grouse and sagebrush habitat conducted by the Western Association of Fish and Wildlife Agencies. The boundary...

  14. Boundary of the State of Iowa

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This coverage contains polygons representing the Iowa Boundary, it was derived from a coverage of county boundaries, called COUNTIES, of the state of Iowa. COUNTIES...

  15. Cal State Park Boundaries 2011/2012

    Data.gov (United States)

    California Department of Resources — This is a GIS version of California State Park (CSP) operational boundaries and does not represent official property boundary determinations. This GIS version is...

  16. Practical boundary surveying legal and technical principles

    CERN Document Server

    Gay, Paul

    2015-01-01

    This guide to boundary surveying provides landowners, land surveyors, students and others with the necessary foundation to understand boundary surveying techniques and the common legal issues that govern boundary establishment.  Boundary surveying is sometimes mistakenly considered a strictly technical discipline with simple and straightforward technical solutions.  In reality, boundary establishment is often a difficult and complex matter, requiring years of experience and a thorough understanding of boundary law.  This book helps readers to understand the challenges often encountered by boundary surveyors and some of the available solutions. Using only simple and logically explained mathematics, the principles and practice of boundary surveying are demystified for those without prior experience, and the focused coverage of pivotal issues such as easements and setting lot corners will aid even licensed practitioners in untangling thorny cases. Practical advice on using both basic and advanced instruments ...

  17. On filter boundary conditions in topology optimization

    DEFF Research Database (Denmark)

    Clausen, Anders; Andreassen, Erik

    2017-01-01

    Most research papers on topology optimization involve filters for regularization. Typically, boundary effects from the filters are ignored. Despite significant drawbacks the inappropriate homogeneous Neumann boundary conditions are used, probably because they are trivial to implement. In this paper...

  18. A comparison of [0 0 1] low-angle tilt grain boundaries of (1 0 0) and (1 1 0) grain boundary planes in YBa 2Cu 3O 7- δ coated conductors

    Science.gov (United States)

    Kung, H.; Hirth, J. P.; Foltyn, S. R.; Arendt, P. N.; Jia, Q. X.; Maley, M. P.

    2001-08-01

    The microstructure and grain boundary structure in YBa 2Cu 3O 7- δ (YBCO) thick film coated conductors are characterized by transmission electron microscopy. The films contain low-angle [0 0 1] tilt grain boundaries with periodic arrays of edge dislocations parallel to the c-axis. A majority of the grain boundary planes are of either the (1 0 0) or the (1 1 0) type. Grain boundary dislocations (GBDs) with a [1 0 0] Burgers vector were observed in tilt boundaries with (1 0 0) boundary planes. However, partial dislocations, separated by stacking faults, were found at boundaries with near (1 1 0) grain boundary planes. Extensive g· b and g· R analyses confirmed the partials to be of 1/2[1 1 0] type. These results suggest that the characteristics of dislocation structures, which have been proposed in various grain boundary-based flux-pinning models, depend not only on the misorientation angle θ, but also on the types of grain boundary plane. The effect of dissociated GBDs on the transport properties of low angle grain boundaries in YBCO coated conductors is discussed.

  19. Stability and boundary stabilization of 1-D hyperbolic systems

    CERN Document Server

    Bastin, Georges

    2016-01-01

    This monograph explores the modeling of conservation and balance laws of one-dimensional hyperbolic systems using partial differential equations. It presents typical examples of hyperbolic systems for a wide range of physical engineering applications, allowing readers to understand the concepts in whichever setting is most familiar to them. With these examples, it also illustrates how control boundary conditions may be defined for the most commonly used control devices. The authors begin with the simple case of systems of two linear conservation laws and then consider the stability of systems under more general boundary conditions that may be differential, nonlinear, or switching. They then extend their discussion to the case of nonlinear conservation laws and demonstrate the use of Lyapunov functions in this type of analysis. Systems of balance laws are considered next, starting with the linear variety before they move on to more general cases of nonlinear ones. They go on to show how the problem of boundary...

  20. Video Shot Boundary Recognition Based on Adaptive Locality Preserving Projections

    Directory of Open Access Journals (Sweden)

    Yongliang Xiao

    2013-01-01

    Full Text Available A novel video shot boundary recognition method is proposed, which includes two stages of video feature extraction and shot boundary recognition. Firstly, we use adaptive locality preserving projections (ALPP to extract video feature. Unlike locality preserving projections, we define the discriminating similarity with mode prior probabilities and adaptive neighborhood selection strategy which make ALPP more suitable to preserve the local structure and label information of the original data. Secondly, we use an optimized multiple kernel support vector machine to classify video frames into boundary and nonboundary frames, in which the weights of different types of kernels are optimized with an ant colony optimization method. Experimental results show the effectiveness of our method.

  1. SILICON CARBIDE GRAIN BOUNDARY DISTRIBUTIONS, IRRADIATION CONDITIONS, AND SILVER RETENTION IN IRRADIATED AGR-1 TRISO FUEL PARTICLES

    Energy Technology Data Exchange (ETDEWEB)

    Lillo, T. M.; Rooyen, I. J.; Aguiar, J. A.

    2016-11-01

    Precession electron diffraction in the transmission electron microscope was used to map grain orientation and ultimately determine grain boundary misorientation angle distributions, relative fractions of grain boundary types (random high angle, low angle or coincident site lattice (CSL)-related boundaries) and the distributions of CSL-related grain boundaries in the SiC layer of irradiated TRISO-coated fuel particles. Two particles from the AGR-1 experiment exhibiting high Ag-110m retention (>80%) were compared to a particle exhibiting low Ag-110m retention (<19%). Irradiated particles with high Ag-110m retention exhibited a lower fraction of random, high angle grain boundaries compared to the low Ag-110m retention particle. An inverse relationship between the random, high angle grain boundary fraction and Ag-110m retention is found and is consistent with grain boundary percolation theory. Also, comparison of the grain boundary distributions with previously reported unirradiated grain boundary distributions, based on SEM-based EBSD for similarly fabricated particles, showed only small differences, i.e. a greater low angle grain boundary fraction in unirradiated SiC. It was, thus, concluded that SiC layers with grain boundary distributions susceptible to Ag-110m release were present prior to irradiation. Finally, irradiation parameters were found to have little effect on the association of fission product precipitates with specific grain boundary types.

  2. Dislocation structure and energy of high angle (001) twist boundaries: A computer simulation study

    Science.gov (United States)

    Schwartz, D.; Bristowe, P. D.; Vitek, V.

    1987-06-01

    High angle (001) twist boundaries have been investigated experimentally and the presence of grain boundary dislocations (GBD's) and associated cusps in the dependence of the boundary energy on misorientation, is in this case well established. However, in previous computer simulations neither localized GBD's nor distinct energy cusps have been identified. The aim of this study is to clarify this discrepancy between observations and computer modelling. For this purpose the structure and energy of a number of long period (high Sigma) twist boundaries with misorientations very close to Sigma - 5 have been calculated using empirical pair and n-body potentials to describe interatomic forces. Furthermore, an isolated GBD embedded into a Sigma - 5 boundary has been modeled. Well-defined cusps at Sigma - 5 misorientation and localized GBD's have been found but the reference Sigma - 5 structure is always the lowest energy structure which, in general, does not possess the symmetry of the coincidence site lattice. The misorientation dependence of the boundary energy is then discussed using coincidence site lattice. The misorientation dependence of the boundary energy is then discussed using a Read-Shockley type model. The cusps are always very shallow and may have an unconventional shape which is related to the dependence of the elastic energy on misorientation that is not the same for twist and tilt boundaries, contrary to what is usually assumed. Finally, some remaining discrepancies between observed types of GBD's and those found in the present study are discussed in the light of the previously proposed multiplicities of boundary structures.

  3. Dislocation structure and energy of high angle (001) twist boundaries: A computer simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, D.; Bristowe, P.D.; Vitek, V.

    1987-06-01

    High angle (001) twist boundaries have been frequently investigated experimentally and the presence of grain boundary dislocations (gbd's) and associated cusps in the dependence of the boundary energy on misorientation, is in this case well established. However, in previous computer simulations of these boundaries neither localized gbd's nor distinct energy cusps have been identified. Aim of the present study is to clarify this discrepancy between observations and computer modelling. For this purpose the structure and energy of a number of long period (high ) twist boundaries with misorientations very close to = 5 have been calculated using empirical pair and n-body potentials to describe interatomic forces. Furthermore, an isolated gbd embedded into an = 5 boundary has been modeled. Well-defined cusps at = 5 misorientation and localized gbd's have been found but the reference = 5 structure is always the lowest energy structure which, in general, does not possess the symmetry of the coincidence site lattice. The misorientation dependence of the boundary energy is then discussed using a Read-Shockley type model. The cusps are always very shallow and may have an unconventional shape which is related to the dependence of the elastic energy on misorientation that is not the same for twist and tilt boundaries, contrary to what is usually assumed. Finally, some remaining discrepancies between observed types of gbd's and those found in the present study are discussed in the light of the previously proposed multiplicities of boundary structures.

  4. Deformation of Honeycomb with Finite Boundary Subjected to Uniaxial Compression

    Directory of Open Access Journals (Sweden)

    Dai-Heng Chen

    2013-11-01

    Full Text Available In this paper, the crushing behavior of hexagonal honeycomb structures with finite boundaries (finite width and height subjected to in-plane uniaxial compressive loading is studied based on the nonlinear finite element analysis. It is found that stress-strain responses for the honeycombs with finite boundaries can be classified into two types: Type I and Type II. Such a characteristic is affected by the wall thickness, the work-hardening coefficient and the yield stress for the honeycombs. Furthermore, a transition from the symmetric to asymmetric deformation mode can be observed in Type I, and these deformed cells were localized in a horizontal layer. However, for the case of Type II response, the symmetric and asymmetric deformation modes can be observed simultaneously, and the region of the asymmetric mode was formed by the cell layer along the diagonal direction. As a result, the shear deformation behavior was developed along that direction. Moreover, the effect of work-hardening on the deformation behavior for the honeycombs with finite boundaries can be explained from that for infinite honeycombs.

  5. Boundary induced nonlinearities at small Reynolds numbers

    NARCIS (Netherlands)

    Sbragaglia, M.; Sugiyama, K.

    2007-01-01

    We investigate the importance of boundary slip at finite Reynolds numbers for mixed boundary conditions. Nonlinear effects are induced by the non-homogeneity of the boundary condition and change the symmetry properties of the flow with an overall mean flow reduction. To explain the observed drag

  6. Boundary controllability of integrodifferential systems in Banach ...

    Indian Academy of Sciences (India)

    the regularity of optimal boundary controls for parabolic equations with quadratic cost criterion. Recently Han and Park [7] derived a set of sufficient conditions for the boundary controllability of a semilinear system with a nonlocal condition. The purpose of this paper is to study the boundary controllability of nonlinear ...

  7. Boundary crossings and violations in clinical settings.

    Science.gov (United States)

    Aravind, V K; Krishnaram, V D; Thasneem, Z

    2012-01-01

    Principles of beneficence, autonomy, and nonmaleficence, compassion along with fiduciary partnership are the core concepts in the doctor-patient relationship in therapeutic settings. There are varieties of reasons for boundary problems. Physicians ignorance, exploitative character, emotional vulnerability moral weakness and similar factors may pave the way for boundary issues resulting in nonsexual or sexual boundary crossings and violations.

  8. Determination of grain boundary geometry using TEM

    NARCIS (Netherlands)

    Jang, H.; Farkas, D.; Hosson, J.T.M. De

    An experimental method to obtain the grain boundary geometry using the transmission electron microscope is presented. The method allows Σ determination including grain boundary plane orientation. In order to determine the specialness of the grain boundary, three different criteria for maximum

  9. Free-Boundary Resistive Modes in Tokamaks

    NARCIS (Netherlands)

    Huysmans, G. T. A.; Goedbloed, J. P.; Kerner, W.

    1993-01-01

    There exist a number of observations of magnetohydrodynamic (MHD) activity that can be related to resistive MHD modes localized near the plasma boundary. To study the stability of these modes, a free boundary description of the plasma is essential. The resistive plasma-vacuum boundary conditions

  10. Working with boundaries in systems psychodynamic consulting

    Directory of Open Access Journals (Sweden)

    Henk Struwig

    2012-01-01

    Full Text Available Orientation: The researcher described the systems psychodynamics of boundary management in organisations. The data showed how effective boundary management leads to good holding environments that, in turn, lead to containing difficult emotions.Research purpose: The purpose of the research was to produce a set of theoretical assumptions about organisational boundaries and boundary management in organisations and, from these, to develop a set of hypotheses as a thinking framework for practising consulting psychologists when they work with boundaries from a systems psychodynamic stance.Motivation for the study: The researcher used the belief that organisational boundaries reflect the essence of organisations. Consulting to boundary managers could facilitate a deep understanding of organisational dynamics.Research design, approach and method: The researcher followed a case study design. He used systems psychodynamic discourse analysis. It led to six working hypotheses.Main findings: The primary task of boundary management is to hold the polarities of integration and differentiation and not allow the system to become fragmented or overly integrated. Boundary management is a primary task and an ongoing activity of entire organisations.Practical/managerial implications: Organisations should work actively at effective boundary management and at balancing integration and differentiation. Leaders should become aware of how effective boundary management leads to good holding environments that, in turn, lead to containing difficult emotions in organisations.Contribution/value-add: The researcher provided a boundary-consulting framework in order to assist consultants to balance the conceptual with the practical when they consult.

  11. Boundary singularities produced by the motion of soap films.

    Science.gov (United States)

    Goldstein, Raymond E; McTavish, James; Moffatt, H Keith; Pesci, Adriana I

    2014-06-10

    Recent work has shown that a Möbius strip soap film rendered unstable by deforming its frame changes topology to that of a disk through a "neck-pinching" boundary singularity. This behavior is unlike that of the catenoid, which transitions to two disks through a bulk singularity. It is not yet understood whether the type of singularity is generally a consequence of the surface topology, nor how this dependence could arise from an equation of motion for the surface. To address these questions we investigate experimentally, computationally, and theoretically the route to singularities of soap films with different topologies, including a family of punctured Klein bottles. We show that the location of singularities (bulk or boundary) may depend on the path of the boundary deformation. In the unstable regime the driving force for soap-film motion is the mean curvature. Thus, the narrowest part of the neck, associated with the shortest nontrivial closed geodesic of the surface, has the highest curvature and is the fastest moving. Just before onset of the instability there exists on the stable surface the shortest closed geodesic, which is the initial condition for evolution of the neck's geodesics, all of which have the same topological relationship to the frame. We make the plausible conjectures that if the initial geodesic is linked to the boundary, then the singularity will occur at the boundary, whereas if the two are unlinked initially, then the singularity will occur in the bulk. Numerical study of mean curvature flows and experiments support these conjectures.

  12. Inside Out: Organizations as Service Systems Equipped with Relational Boundaries

    Directory of Open Access Journals (Sweden)

    María Jimena Crespo Garrido

    2017-04-01

    Full Text Available Currently, literature on organizational boundaries is at the center of a heated debate, characterized by a shift from a transactional approach to a broader immaterial perspective centered on the concept of boundless organizations. However, the overestimation of the effects of contemporary dematerialization on business processes can lead to the progressive neglect of the existence of corporate borders. In light of this consideration, the present work aims at proposing a new type of criterion for defining organizational boundaries, halfway between the conception of the firm’s total openness and total closure. To this end, the authors envisage the use of a new interpretive logic defined as “relational”, resulting from the specification of the systemic view (and as the sum of the logic underlying the viable systems approach (VSA. This approach views the definition of boundaries. Therefore, in the large and intricate scenery of the studies dedicated to organizational boundaries, this work contributes to a better understanding of border selection as an interactive and changeable process capable of pushing organizations towards a greater awareness of their strategic dimension. This paper also offers some insights for future research, suggesting that both scholars and professionals investigate, firstly, new frontiers for the identification of organizational boundaries and, secondly, the possible positive repercussions that new organizational redesign modes could determine for a greater competitive success.

  13. Microstructural characteristics of new type γ-γ` Co-9Al-9W cobalt-based superalloys in as-cast state

    Directory of Open Access Journals (Sweden)

    A. Tomaszewska

    2018-01-01

    Full Text Available The paper presented deals primary with the structure characteristics of a new type of cobalt-based superalloys Co-9Al-9W type, casted via induction melting process with partially dosing of Common problems described in literature are focused on difficulties in obtaining uniform distribution of tungsten, particularly in interdendritic areas. That was the reason for the modified casting process to be applied. The method of tungsten dosing into liquid melts of Co and Al allows to obtain microstructure characterized by considerably decreased microsegregation. The material obtained was analyzed by standard methods such as light and scanning microscopy with analysis of chemical composition in micro-areas. Additionally, the detailed analysis of the sub-grain level was made by S/TEM on thin foils collected from equiaxed grains zone of the ingot.

  14. Evaluation of outflow boundary conditions for two-phase lattice Boltzmann equation.

    Science.gov (United States)

    Lou, Qin; Guo, Zhaoli; Shi, Baochang

    2013-06-01

    Outflow boundary condition (OBC) is a critical issue in computational fluid dynamics. As a type of numerical method for fluid flows, the lattice Boltzmann equation (LBE) method has gained much success in a variety of complex flows, and certain OBCs have been suggested for the LBE in simulating simple single-phase flows. However, very few discussions on the OBCs have been made for the two-phase LBE method. In this work, three types of OBCs that are widely used in the LBE for single-phase flows, i.e., the Neumann boundary condition, the convective boundary condition, and the extrapolation boundary condition, are extended to a two-phase LBE method and their performances are investigated. The comprehensive results of several two-phase flows show that these boundary conditions behave quite differently in the simulations of two-phase flows. Specifically, it is found that the Neumann boundary condition and the extrapolation boundary condition give rather poor predictions, while the type of convective boundary conditions work well, although the choice of the convection velocity has some slight influences on the results. We also apply these OBC schemes to some other two-phase models, and similar observations are found.

  15. Structural unit/grain boundary dislocation model for twist boundaries in cubic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Bristowe, P.D.; Balluffi, R.W.

    1984-10-01

    The systematics of (001) twist boundary structure is presented formally in terms of a structural unit/grain boundary dislocation hierarchical model and the earlier model of Sutton is generalized. By comparison with experimental observation and atomistic calculation using pair-potential models the physical significance of the individual members of the hierarchy is determined. Comparison which experiment indicates a strong <110> type primary relaxation for theta less than or equal to 36.9/sup 0/ and a significant secondary relaxation near ..sigma..5 which must result from oblique perturbations in the array of primary GBD's. On the other hand, comparison with available calculated results indicates a strong <110> type primary relaxation at low angles but a progressively weaker relaxation at higher angles. Also, no evidence is found for any significant secondary relaxations when at least one pair potential is employed. However, very recent studies indicate stronger secondary relaxations with other potentials, and this, in future work, should lead to better agreement between calculations and experiment.

  16. Experimental characterization of dislocations in deformation induced planar boundaries of rolled aluminium

    DEFF Research Database (Denmark)

    Hong, Chuanshi; Huang, Xiaoxu; Winther, Grethe

    2012-01-01

    Dislocations in 2 geometrically necessary boundaries in a grain near the 45°-ND rotated cube orientation in 10% rolled 99.996% pure Al were investigated by detailed transmission electron microscopy. In these two boundaries dislocations with all six Burgers vectors of the ½ type expected...... for fcc crystals were observed but dislocations from the four most active slip systems dominated. The dislocations with Burgers vectors not corresponding to one of the expected active slip systems are primarily interpreted as being the result of dislocation reactions in the boundary. Two main types...... of dislocation networks in the boundaries were observed: (1) 3 sets of dislocations in a hexagonal network all having Burgers vectors in the slip plane with which the boundary aligned. Two of these come from the active slip systems, the third is attributed to dislocation reactions. (2) 4 sets of dislocations...

  17. The Community Boundary De-paradoxifyed

    DEFF Research Database (Denmark)

    Dragsdahl Lauritzen, Ghita; Salomo, Søren

    2012-01-01

    . In order to improve connections and collaborations across interfaces, it is therefore necessary to improve our understanding of the community boundary construct. Existing studies of community boundaries within the user innovation literature predominantly describe boundaries as incentives for user...... participation without a clear distinction of what is part of the community and what is not. This gap is intensified by the emergence of virtual communities, where the notion of boundary is even more distorted. The paper suggests a new construct of virtual community boundaries that sets up the distinction...... between community and its environment differently from existing studies of virtual communities. Instead of taking its starting point in the users, the paper takes an organizational approach and focuses on the function of the community boundary construct. Hereby, the paper shows how community boundaries...

  18. Quantitative Characterization of Boundary Roughness in Metals

    DEFF Research Database (Denmark)

    Sun, Jun

    The boundary migration during recrystallization is by nature a heterogeneous process and local structural variations form on recrystallization boundaries, as revealed from modern techniques such as synchrotron X-rays and advanced electron microscopy. The local structural variations, in the form...... of protrusions and retrusions, can provide a dragging/driving force due to the local boundary curvature and affect the further migration of recrystallization boundaries through the deformed matrix. In order to develop new understandings and models for boundary migration that take the heterogeneous local...... structural aspects into account, a detailed characterization is essential of partly recrystallized microstructures focusing on the local shapes of the boundaries, in particular on whether protrusions and retrusions are formed or not. Quantification of the “amount” of boundary roughness in the form...

  19. Boundary element simulation of petroleum reservoirs with hydraulically fractured wells

    Science.gov (United States)

    Pecher, Radek

    The boundary element method is applied to solve the linear pressure-diffusion equation of fluid-flow in porous media. The governing parabolic partial differential equation is transformed into the Laplace space to obtain the elliptic modified-Helmholtz equation including the homogeneous initial condition. The free- space Green's functions, satisfying this equation for anisotropic media in two and three dimensions, are combined with the generalized form of the Green's second identity. The resulting boundary integral equation is solved by following the collocation technique and applying the given time-dependent boundary conditions of the Dirichlet or Neumann type. The boundary integrals are approximated by the Gaussian quadrature along each element of the discretized domain boundary. Heterogeneous regions are represented by the sectionally-homogeneous zones of different rock and fluid properties. The final values of the interior pressure and velocity fields and of their time-derivatives are found by numerically inverting the solutions from the Laplace space by using the Stehfest's algorithm. The main extension of the mostly standard BEM-procedure is achieved in the modelling of the production and injection wells represented by internal sources and sinks. They are treated as part of the boundary by means of special single-node and both-sided elements, corresponding to the line and plane sources respectively. The wellbore skin and storage effects are considered for the line and cylindrical sources. Hydraulically fractured wells of infinite conductivity are handled directly according to the specified constraint type, out of the four alternatives. Fractures of finite conductivity are simulated by coupling the finite element model of their 1D-interior with the boundary element model of their 2D- exterior. Variable fracture width, fractures crossing zone boundaries, ``networking'' of fractures, fracture-tip singularity handling, or the 3D-description are additional advanced

  20. Boundary breaking for interdisciplinary learning

    Directory of Open Access Journals (Sweden)

    Adi Kidron

    2015-10-01

    Full Text Available The purpose of this work is to contribute to the body of knowledge on processesby which students develop interdisciplinary understanding of contents, as well as to suggest technology-enhanced means for supporting them in these processes in the context of higher education. In doing so, we suggest a rethinking of three traditional practices that tend to characterise typical higher education instruction: (1 compartmentalisation of disciplines; (2 traditional pedagogy; and (3 traditional hierarchies based on levels of expertise. Our high-level conjecture was that meaningful dialogue with peers and experts supports both the deepening of ideas in one knowledge domain and the formation of connections between ideas from several domains, both of which are required for the development of interdisciplinary understanding. We developed the Boundary Breaking for Interdisciplinary Learning (BBIL model, which harnesses technology to break boundaries between disciplines, learners and organisational levels of hierarchy. Findings indicate that 36 undergraduate students who participated in an interdisciplinary online course that implemented the BBIL model have significantly improved their interdisciplinary understanding of the course contents. This study illustrates how innovative use of available, free and low-cost technology can produce a ‘positive disruption’ in higher education instruction.

  1. Emission of dislocations from grain boundaries by grain boundary dissociation

    Science.gov (United States)

    Hoagland, Richard G.; Valone, Steven M.

    2015-01-01

    In this article, we examine the conditions that favour the emission of Shockley partial dislocations (SPDs) that standoff from a grain boundary (GB) plane by a few lattice parameters as part of the atomic structure of some GBs. To do so, we consider GBs to be formed by the operation of arrays of intrinsic grain boundary dislocations (GBDs) that create the tilt and twist misorientation, and the lattice mismatch between the two crystal grains adjoining the GB. The conditions to be considered that favour SPDs are the following: (1) Frank's rule, (2) the proper sequential arrangement of partial dislocations to bound an intrinsic stacking fault and (3) the equilibrium stand-off distance (ESD). We apply an isotropic elasticity analysis to compute the ESD, in the absence of an applied stress, for SPDs emerging from asymmetric tilt GBs in two FCC metals, Cu and Al. The ESD is shown to be dependent on the glide plane orientation relative to the GB plane and on the position of the glide planes, relative to the position of the GBDs. An applied stress increases the ESD up to a critical stress that removes the SPDs without limit from the GB. We examine the effect of the stacking fault energy on the ESD and critical stress. The critical stress is effectively linearly dependent on the stacking fault energy. Finally, we present results of atomistic simulations of asymmetric tilt Σ11[1 0 1]{4 1 4}||{2 5 2} GBs in Cu bicrystal models subject to shock loading that behave in a manner similar to the elasticity predictions. The atomistic simulations reveal additional behaviour associated with elastic incompatibility between the two grains in the bicrystal models.

  2. Nature, theory and modelling of geophysical convective planetary boundary layers

    Science.gov (United States)

    Zilitinkevich, Sergej

    2015-04-01

    Geophysical convective planetary boundary layers (CPBLs) are still poorly reproduced in oceanographic, hydrological and meteorological models. Besides the mean flow and usual shear-generated turbulence, CPBLs involve two types of motion disregarded in conventional theories: 'anarchy turbulence' comprised of the buoyancy-driven plumes, merging to form larger plumes instead of breaking down, as postulated in conventional theory (Zilitinkevich, 1973), large-scale organised structures fed by the potential energy of unstable stratification through inverse energy transfer in convective turbulence (and performing non-local transports irrespective of mean gradients of transporting properties). C-PBLs are strongly mixed and go on growing as long as the boundary layer remains unstable. Penetration of the mixed layer into the weakly turbulent, stably stratified free flow causes turbulent transports through the CPBL outer boundary. The proposed theory, taking into account the above listed features of CPBL, is based on the following recent developments: prognostic CPBL-depth equation in combination with diagnostic algorithm for turbulence fluxes at the CPBL inner and outer boundaries (Zilitinkevich, 1991, 2012, 2013; Zilitinkevich et al., 2006, 2012), deterministic model of self-organised convective structures combined with statistical turbulence-closure model of turbulence in the CPBL core (Zilitinkevich, 2013). It is demonstrated that the overall vertical transports are performed mostly by turbulence in the surface layer and entrainment layer (at the CPBL inner and outer boundaries) and mostly by organised structures in the CPBL core (Hellsten and Zilitinkevich, 2013). Principal difference between structural and turbulent mixing plays an important role in a number of practical problems: transport and dispersion of admixtures, microphysics of fogs and clouds, etc. The surface-layer turbulence in atmospheric and marine CPBLs is strongly enhanced by the velocity shears in

  3. Delineation of peatland lagg boundaries from airborne LiDAR

    Science.gov (United States)

    Langlois, Melanie N.; Richardson, Murray C.; Price, Jonathan S.

    2017-09-01

    In Canada, peatlands are the most common type of wetland, but boundary delineation in peatland complexes has received little attention in the scientific literature. Typically, peatland boundaries are mapped as crisp, absolute features, and the transitional lagg zone—the ecotone found between a raised bog and the surrounding mineral land—is often overlooked. In this study, we aim (1) to advance existing approaches for detecting and locating laggs and lagg boundaries using airborne LiDAR surveys and (2) to describe the spatial distribution of laggs around raised bog peatlands. Two contrasting spatial analytical approaches for lagg detection were tested using five LiDAR-derived topographic and vegetation indices: topography, vegetation height, topographic wetness index, the standard deviation of the vegetation's height (as a proxy for the complexity of the vegetation's structure), and local indices of elevation variance. Using a dissimilarity approach (edge-detection, split-moving window analysis), no one variable accurately depicted both the lagg-mineral land and bog-lagg boundaries. Some indicators were better at predicting the bog-lagg boundary (i.e., vegetation height) and others at finding the lagg-mineral land boundary (i.e., topography). Dissimilarity analysis reinforces the usefulness of derived variables (e.g., wetness indices) in locating laggs, especially for those with weak topographic and vegetation gradients. When the lagg was confined between the bog and the adjacent upland, it took a linear form, parallel to the peatland's edge and was easier to predict. When the adjacent mineral land was flat or sloping away from the peatland, the lagg was discontinuous and intermittent and more difficult to predict.

  4. The new boundaries of the "boundaryless" company.

    Science.gov (United States)

    Hirschhorn, L; Gilmore, T

    1992-01-01

    In an economy founded on innovation and change, one of the premier challenges of management is to design more flexible organizations. For many executives, a single metaphor has come to embody this managerial challenge and to capture the kind of organization they want to create: the "corporation without boundaries." According to Larry Hirschhorn and Thomas Gilmore of the Wharton Center for Applied Research, managers are right to break down the boundaries that make organizations rigid and unresponsive. But they are wrong if they think that doing so eliminates the need for boundaries altogether. Once the traditional boundaries of hierarchy, function, and geography disappear, a new set of boundaries becomes important. These new boundaries are more psychological than organizational. They aren't drawn on a company's organizational chart but in the minds of its managers and employees. And instead of being reflected in a company's structure, they must be "enacted" over and over again in a manager's relationships with bosses, subordinates, and peers. In this article, Hirschhorn and Gilmore provide a guide to the boundaries that matter in the "boundaryless" company. They explain how these new boundaries are essential for both managers and employees in coping with the demands of flexible work. They describe the typical mistakes that managers make in their boundary relationships. And they show how executives can become effective boundary managers by paying attention to a source of data they have often overlooked in the past: their own gut feelings about work and the people with whom they do it.

  5. Structural disjoining potential for grain-boundary premelting and grain coalescence from molecular-dynamics simulations

    Science.gov (United States)

    Fensin, Saryu J.; Olmsted, David; Buta, Dorel; Asta, Mark; Karma, Alain; Hoyt, J. J.

    2010-03-01

    We describe a molecular-dynamics framework for the direct calculation of the short-ranged structural forces underlying grain-boundary premelting and grain coalescence in solidification. The method is applied in a comparative study of (i) a Σ9⟨115⟩120° twist and (ii) a Σ9⟨110⟩{411} symmetric tilt boundary in a classical embedded-atom model of elemental Ni. Although both boundaries feature highly disordered structures near the melting point, the nature of the temperature dependence of the width of the disordered regions in these boundaries is qualitatively different. The former boundary displays behavior consistent with a logarithmically diverging premelted layer thickness as the melting temperature is approached from below, while the latter displays behavior featuring a finite grain-boundary width at the melting point. It is demonstrated that both types of behavior can be quantitatively described within a sharp-interface thermodynamic formalism involving a width-dependent interfacial free energy, referred to as the disjoining potential. The disjoining potential for boundary (i) is calculated to display a monotonic exponential dependence on width, while that of boundary (ii) features a weak attractive minimum. The results of this work are discussed in relation to recent simulation and theoretical studies of the thermodynamic forces underlying grain-boundary premelting.

  6. Computer simulation study of the structure of vacancies in grain boundaries

    Science.gov (United States)

    Brokman, A.; Bristowe, P. D.; Balluffi, R. W.

    1981-10-01

    The structure of vacancies in grain boundaries has been investigated by computer molecular statics employing pairwise potentials. In order to gain an impression of the vacancy structures which may occur generally, a number of variables was investigated, including metal type, boundary type, degree of lattice coincidence, and choice of boundary site. In all cases the vacancies remained as distinguishable point defects in the relatively irregular boundary structures. However, it was found that the vacancy often induced relatively large atomic displacements in the core of the boundary. These displacements often occurred only in the direct vicinity of the vacancy, but in certain cases they were widely distributed in the boundary, sometimes at surprisingly large distances. In certain cases the displacements included a large inward relaxation of one, or more, of the atoms neighboring the vacancy, and the initial vacant site became effectively ″split″. These results were classified and discussed in relation to the variables listed above. Several binding energies to the boundary were also calculated. Finally, the relevance of the results to the mechanism of boundary self-diffusion was discussed.

  7. Parametrices and exact paralinearization of semi-linear boundary problems

    DEFF Research Database (Denmark)

    Johnsen, Jon

    2008-01-01

    The subject is parametrices for semi-linear problems, based on parametrices for linear boundary problems and on non-linearities that decompose into solution-dependent linear operators acting on the solutions. Non-linearities of product type are shown to admit this via exact paralinearization. The...... of homogeneous distributions, tensor products and halfspace extensions have been revised. Examples include the von Karman equation....

  8. Topology and boundary shape optimization as an integrated design tool

    Science.gov (United States)

    Bendsoe, Martin Philip; Rodrigues, Helder Carrico

    1990-01-01

    The optimal topology of a two dimensional linear elastic body can be computed by regarding the body as a domain of the plane with a high density of material. Such an optimal topology can then be used as the basis for a shape optimization method that computes the optimal form of the boundary curves of the body. This results in an efficient and reliable design tool, which can be implemented via common FEM mesh generator and CAD type input-output facilities.

  9. Outer Magnetospheric Boundaries Cluster Results

    CERN Document Server

    Paschmann, Goetz; Schwartz, S J

    2006-01-01

    When the stream of plasma emitted from the Sun (the solar wind) encounters Earth's magnetic field, it slows down and flows around it, leaving behind a cavity, the magnetosphere. The magnetopause is the surface that separates the solar wind on the outside from the Earth's magnetic field on the inside. Because the solar wind moves at supersonic speed, a bow shock must form ahead of the magnetopause that acts to slow the solar wind to subsonic speeds. Magnetopause, bow shock and their environs are rich in exciting processes in collisionless plasmas, such as shock formation, magnetic reconnection, particle acceleration and wave-particle interactions. They are interesting in their own right, as part of Earth's environment, but also because they are prototypes of similar structures and phenomena that are ubiquitous in the universe, having the unique advantage that they are accessible to in situ measurements. The boundaries of the magnetosphere have been the target of direct in-situ measurements since the beginning ...

  10. Plasma transport near material boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Singer, C.E.

    1985-06-01

    The fluid theory of two-dimensional (2-d) plasma transport in axisymmetric devices is reviewed. The forces which produce flow across the magnetic field in a collisional plasma are described. These flows may lead to up-down asymmetries in the poloidal rotation and radial fluxes. Emphasis is placed on understanding the conditions under which the known 2-d plasma fluid equations provide a valid description of these processes. Attempts to extend the fluid treatment to less collisional, turbulent plasmas are discussed. A reduction to the 1-d fluid equations used in many computer simulations is possible when sources or boundary conditions provide a large enough radial scale length. The complete 1-d fluid equations are given in the text, and 2-d fluid equations are given in the Appendix.

  11. Experimental investigation of wave boundary layer

    DEFF Research Database (Denmark)

    Sumer, B. Mutlu

    2003-01-01

    A review is presented of experimental investigation of wave boundary layer. The review is organized in six main sections. The first section describes the wave boundary layer in a real-life environment and its simulation in the laboratory in an oscillating water tunnel and in a water tank...... with an oscillating seabed. A brief account is given of measured quantities, measurement techniques (LDA, PIV, flow visualization) and limitations/constraints in the experimental investigation of the wave boundary layer in the laboratory. The second section concentrates on uniform oscillating boundary layers...... with a smooth bed. The boundary layer process is described over the entire range of the Reynolds number (Re from practically nil to Re = O(107)), from the laminar regime to the transitional regime and to the fully developed turbulent regime. The third section focuses on the effect of the boundary roughness...

  12. Physical modeling of the atmospheric boundary layer in the UNH Flow Physics Facility

    Science.gov (United States)

    Taylor-Power, Gregory; Gilooly, Stephanie; Wosnik, Martin; Klewicki, Joe; Turner, John

    2016-11-01

    The Flow Physics Facility (FPF) at UNH has test section dimensions W =6.0m, H =2.7m, L =72m. It can achieve high Reynolds number boundary layers, enabling turbulent boundary layer, wind energy and wind engineering research with exceptional spatial and temporal instrument resolution. We examined the FPF's ability to experimentally simulate different types of the atmospheric boundary layer (ABL) using upstream roughness arrays. The American Society for Civil Engineers defines standards for simulating ABLs for different terrain types, from open sea to dense city areas (ASCE 49-12). The standards require the boundary layer to match a power law shape, roughness height, and power spectral density criteria. Each boundary layer type has a corresponding power law exponent and roughness height. The exponent and roughness height both increase with increasing roughness. A suburban boundary layer was chosen for simulation and a roughness element fetch was created. Several fetch lengths were experimented with and the resulting boundary layers were measured and compared to standards in ASCE 49-12: Wind Tunnel Testing for Buildings and Other Structures. Pitot tube and hot wire anemometers were used to measure average and fluctuating flow characteristics. Velocity profiles, turbulence intensity and velocity spectra were found to compare favorably.

  13. Reaction diffusion equations with boundary degeneracy

    Directory of Open Access Journals (Sweden)

    Huashui Zhan

    2016-03-01

    Full Text Available In this article, we consider the reaction diffusion equation $$ \\frac{\\partial u}{\\partial t} = \\Delta A(u,\\quad (x,t\\in \\Omega \\times (0,T, $$ with the homogeneous boundary condition. Inspired by the Fichera-Oleinik theory, if the equation is not only strongly degenerate in the interior of $\\Omega$, but also degenerate on the boundary, we show that the solution of the equation is free from any limitation of the boundary condition.

  14. Absorption boundary conditions for geomertical acoustics

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho

    2012-01-01

    Defining accurate acoustical boundary conditions is of crucial importance for room acoustic simulations. In predicting sound fields using phased geometrical acoustics methods, the absorption coefficients or surface impedances of the boundary surfaces can be used, but no guideline has been developed...... solutions. Two rectangular rooms with uniform and non-uniform absorption distributions are tested. It is concluded that the impedance and random incidence absorption boundary conditions produce reasonable results with some exceptions at low frequencies for acoustically soft materials....

  15. Theoretical investigation of twist boundaries in germanium

    Energy Technology Data Exchange (ETDEWEB)

    Payne, M.C.; Bristowe, P.D.; Joannopoulos, J.D.

    1987-01-01

    Results of the first completely ab-initio investigation of the microscopic structure of a grain boundary in a semiconductor are presented. Using the molecular dynamics simulated annealing method for performing total energy calculations within the LDA and pseudopotential approximations, the ..sigma.. = 5(001) twist boundary in germanium is studied. A low energy structure is identified which exhibits a rigid body translation and a small contraction at the boundary.

  16. Boundary definition of a multiverse measure

    OpenAIRE

    Bousso, Raphael; Freivogel, Ben; Leichenauer, Stefan; Rosenhaus, Vladimir

    2010-01-01

    We propose to regulate the infinities of eternal inflation by relating a late time cut-off in the bulk to a short distance cut-off on the future boundary. The light-cone time of an event is defined in terms of the volume of its future light-cone on the boundary. We seek an intrinsic definition of boundary volumes that makes no reference to bulk structures. This requires taming the fractal geometry of the future boundary, and lifting the ambiguity of the conformal factor. We propose to work in...

  17. Gauge Fields as Composite Boundary Excitations

    CERN Document Server

    Ferrara, Sergio; Ferrara, Sergio; Fronsdal, Christian

    1998-01-01

    We investigate representations of the conformal group that describe "massless" particles in the interior and at the boundary of anti-de Sitter space. It turns out that massless gauge excitations in anti-de Sitter are gauge "current" operators at the boundary. Conversely, massless excitations at the boundary are topological singletons in the interior. These representations lie at the threshold of two "unitary bounds" that apply to any conformally invariant field theory. Gravity and Yang-Mills gauge symmetry in anti-De Sitter is translated to global translational symmetry and continuous R-symmetry of the boundary superconformal field theory.

  18. A Neumann boundary term for gravity

    Science.gov (United States)

    Krishnan, Chethan; Raju, Avinash

    2017-05-01

    The Gibbons-Hawking-York (GHY) boundary term makes the Dirichlet problem for gravity well-defined, but no such general term seems to be known for Neumann boundary conditions. In this paper, we view Neumann not as fixing the normal derivative of the metric (“velocity”) at the boundary, but as fixing the functional derivative of the action with respect to the boundary metric (“momentum”). This leads directly to a new boundary term for gravity: the trace of the extrinsic curvature with a specific dimension-dependent coefficient. In three dimensions, this boundary term reduces to a “one-half” GHY term noted in the literature previously, and we observe that our action translates precisely to the Chern-Simons action with no extra boundary terms. In four dimensions, the boundary term vanishes, giving a natural Neumann interpretation to the standard Einstein-Hilbert action without boundary terms. We argue that in light of AdS/CFT, ours is a natural approach for defining a “microcanonical” path integral for gravity in the spirit of the (pre-AdS/CFT) work of Brown and York.

  19. Management of professional boundaries in rural practice.

    Science.gov (United States)

    Brooks, Kathleen D; Eley, Diann S; Pratt, Rebekah; Zink, Therese

    2012-08-01

    Rural physicians wrestle with professional boundary issues routinely in everyday interactions, and their situation differs from the experience of their urban colleagues. Medical students receive limited exposure to professional boundary management in preclinical training. Increasingly, schools are implementing rural longitudinal clinical clerkships which expose students to rural boundary setting. This qualitative study explored the management of professional boundaries integral to rural practice and how this management may differ from their urban colleagues. Semistructured interviews were conducted in 2010 with 12 rural physicians across Minnesota exploring their perceptions of professionalism in rural practice. A social constructivist approach to grounded theory was used to analyze the data. Five primary themes regarding rural professionalism emerged from the data: centrality of care, rural influences on choice, individualization of boundary setting, advantages of dual relationships, and disadvantages of them. These themes served to illustrate rural boundary management. This study's findings indicate that rural physicians are routinely confronted with professional boundary issues in everyday situations, and these circumstances do not always reflect those of their urban colleagues. Given the increase in longitudinal immersion clinical clerkship programs to nurture student interest in future rural practice, acknowledgment and acceptance of the nuances of dual relationships and boundary setting in different clinical learning contexts are vital to help students identify their personal needs for privacy and be better prepared to negotiate the realities of rural practice. These findings may inform future medical education initiatives on professional boundary setting as an aspect of professionalism.

  20. Detonation Shock Dynamics Modelling with Arbitrary Boundaries

    Science.gov (United States)

    Hodgson, Alexander

    2017-06-01

    The Detonation Shock Dynamics (DSD) model can be used to predict detonation wave propagation in a high explosive (HE). The detonation wave is prescribed a velocity that depends on its curvature. Additionally, the angle between the wave and the HE boundary may not exceed a specified ``boundary angle'', the value of which depends on the HE and its confining material(s). The level-set method is commonly used to drive DSD computation. Boundary conditions are applied to the level-set field at the charge edges to maintain the explosive boundary angle criteria. The position of the boundary must be accurate and continuous across adjacent cells to achieve accurate and robust results. This is mainly an issue for mixed material meshes where the boundary does not coincide with the cell boundaries. For such meshes, a set of volume fractions defines the amount of material in each cell. The boundary is defined implicitly by the volume fractions, and must be reconstructed to an explicit form for use in DSD. This work describes a novel synthesis of the level-set method and simulated annealing, an optimisation method used to reconstruct the boundary. The accuracy and robustness of the resulting DSD calculation are evaluated with a range of test problems.

  1. Ferroelectric domain continuity over grain boundaries

    DEFF Research Database (Denmark)

    Mantri, Sukriti; Oddershede, Jette; Damjanovic, Dragan

    2017-01-01

    Formation and mobility of domain walls in ferroelectric materials is responsible for many of their electrical and mechanical properties. Domain wall continuity across grain boundaries has been observed since the 1950's and is speculated to affect the grain boundary-domain interactions, thereby...... orientation. We have also incorporated the effect of grain boundary ferroelectric polarization charge created when any two domains meet at the grain boundary plane. The probability of domain wall continuity for three specific grain misorientations is studied. Use of this knowledge to optimize processing...

  2. Projections and residues on manifolds with boundary

    DEFF Research Database (Denmark)

    Gaarde, Anders Borg

    2008-01-01

    It is a well-known result that the noncommutative residue of a pseudodifferential projection is zero on a compact manifold without boundary. Equivalently, the value of the zeta-function of P at zero, ¿¿(P, 0), is independent of ¿ for any elliptic operator P. Here ¿ denotes the angle of a ray where...... the resolvent of P has minimal growth. In this thesis, we consider the analogous questions on a compact manifold with boundary. We show that the noncommutative residue is zero for any projection in Boutet de Monvel’s calculus of pseudodifferential boundary problems. For an elliptic boundary problem {P+ + G, T...

  3. Boundary layer thickness effect on boattail drag

    Science.gov (United States)

    Blaha, B. J.; Chamberlain, R.; Bober, L. J.

    1976-01-01

    A combined experimental and analytical program was conducted to investigate the effects of boundary layer changes on the flow over high angle boattail nozzles. The tests were run on an isolated axisymmetric sting mounted model. Various boattail geometries were investigated at high subsonic speeds over a range of boundary layer thicknesses. In general, boundary layer effects were small at speeds up to Mach 0.8. However, at higher speeds significant regions of separated flow were present on the boattail. When separation was present large reductions in boattail drag resulted with increasing boundary layer thickness. The analysis predicts both of these trends.

  4. Prosodic boundaries in writing: Evidence from a keystroke analysis

    Directory of Open Access Journals (Sweden)

    Susanne Fuchs

    2016-11-01

    Full Text Available The aim of the paper is to investigate duration between successive keystrokes during typing in order to examine whether prosodic boundaries are expressed in the process of writing. In particular, we are interested in interkey durations that occur next to punctuation marks (comma and full stops while taking keystrokes between words as a reference, since these punctuation marks are often realized with minor or major prosodic boundaries during reading. A two-part experiment was conducted: first, participants’ keystrokes on a computer keyboard were recorded while writing an email to a close friend (in two conditions: with and without time pressure. Second, participants read the email they just wrote. Interkey durations were compared to pause durations at the same locations during read speech. Results provide evidence of significant differences between interkey durations between words, at commas and at full stops (from shortest to longest. These durations were positively correlated with silent pause durations during reading. A more detailed analysis of interkey durations revealed patterns that can be interpreted with respect to prosodic boundaries in speech production, namely as phrase-final and phrase-initial lengthening occurring at punctuation marks. This work provides initial evidence that prosodic boundaries are reflected in the writing process.

  5. The collapse of turbulence in the atmospheric boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Van de Wiel, B J H; Clercx, H J H [Department of Physics, Eindhoven University of Technology (Netherlands); Moene, A F [Department of Meteorology and Air Quality, Wageningen University and Research Centre (Netherlands); Jonker, H J J, E-mail: b.j.h.v.d.wiel@tue.nl [Department of Multi-scale Pysics, Delft University of Technology (Netherlands)

    2011-12-22

    A well-known phenomenon in the atmospheric boundary layer is the fact that winds may become very weak in the evening after a clear sunny day. In these quiet conditions usually hardly any turbulence is present. Consequently this type of boundary layer is referred to as the quasi-laminar boundary layer. In spite of its relevance, the appearance of laminar boundary layers is poorly understood and forms a long standing problem in meteorological research. Here we investigate an analogue problem in the form of a stably stratified channel flow. The flow is studied with a simplified atmospheric model as well as with Direct Numerical Simulations. Both models show remarkably similar behaviour with respect to the mean variables such as temperature and wind speed. The similarity between both models opens new way for understanding and predicting the laminarization process. Mathematical analysis on the simplified model shows that relaminarization can be understood from the existence of a definite limit in the maximum sustainable heat flux under stably stratified conditions. This fascinating aspect will be elaborated in future work.

  6. From boundaries to boundary work: middle managers creating inter-organizational change.

    Science.gov (United States)

    Oldenhof, Lieke; Stoopendaal, Annemiek; Putters, Kim

    2016-11-21

    Purpose In healthcare, organizational boundaries are often viewed as barriers to change. The purpose of this paper is to show how middle managers create inter-organizational change by doing boundary work: the dual act of redrawing boundaries and coordinating work in new ways. Design/methodology/approach Theoretically, the paper draws on the concept of boundary work from Science and Technology Studies. Empirically, the paper is based on an ethnographic investigation of middle managers that participate in a Dutch reform program across health, social care, and housing. Findings The findings show how middle managers create a sense of urgency for inter-organizational change by emphasizing "fragmented" service provision due to professional, sectoral, financial, and geographical boundaries. Rather than eradicating these boundaries, middle managers change the status quo gradually by redrawing composite boundaries. They use boundary objects and a boundary-transcending vocabulary emphasizing the need for societal gains that go beyond production targets of individual organizations. As a result, work is coordinated in new ways in neighborhood teams and professional expertise is being reconfigured. Research limitations/implications Since boundary workers create incremental change, it is necessary to follow their work for a longer period to assess whether boundary work contributes to paradigm change. Practical implications Organizations should pay attention to conditions for boundary work, such as legitimacy of boundary workers and the availability of boundary spaces that function as communities of practice. Originality/value By shifting the focus from boundaries to boundary work, this paper gives valuable insights into "how" boundaries are redrawn and embodied in objects and language.

  7. Secondary flows in turbulent boundary layers over longitudinal surface roughness

    Science.gov (United States)

    Hwang, Hyeon Gyu; Lee, Jae Hwa

    2018-01-01

    Direct numerical simulations of turbulent boundary layers over longitudinal surface roughness are performed to investigate the impact of the surface roughness on the mean flow characteristics related to counter-rotating large-scale secondary flows. By systematically changing the two parameters of the pitch (P) and width (S) for roughness elements in the ranges of 0.57 ≤P /δ ≤2.39 and 0.15 ≤S /δ ≤1.12 , where δ is the boundary layer thickness, we find that the size of the secondary flow in each case is mostly determined by the value of P - S, i.e., the valley width, over the ridge-type roughness. However, the strength of the secondary flows on the cross-stream plane relative to the flow is increased when the value of P increases or when the value of S decreases. In addition to the secondary flows, additional tertiary and quaternary flows are observed both above the roughness crest and in the valley as the values of P and S increase further. Based on an analysis using the turbulent kinetic energy transport equation, it is shown that the secondary flow over the ridge-type roughness is both driven and sustained by the anisotropy of turbulence, consistent with previous observations of a turbulent boundary layer over strip-type roughness [Anderson et al., J. Fluid Mech. 768, 316 (2015), 10.1017/jfm.2015.91]. Careful inspection of the turbulent kinetic energy budget reveals that the opposite rotational sense of the secondary flow between the ridge- and strip-type roughness elements is primarily attributed to the local imbalance of energy budget created by the strong turbulent transport term over the ridge-type roughness. The active transport of the kinetic energy over the ridge-type roughness is closely associated with the upward deflection of spanwise motions in the valley, mostly due to the roughness edge.

  8. Perceptions of boundary ambiguity in the process of leaving an abusive partner.

    Science.gov (United States)

    Khaw, Lyndal; Hardesty, Jennifer L

    2015-06-01

    The process of leaving an abusive partner has been theorized using the Stages of Change Model. Although useful, this model does not account for changes in relational boundaries unique to the process of leaving. Using family stress and feminist perspectives, this study sought to integrate boundary ambiguity into the Stages of Change Model. Boundary ambiguity is defined as a perception of uncertainty as to who is in or out of a family system (Boss & Greenberg, 1984). Twenty-five mothers who had temporarily or permanently left their abusers were interviewed. Data were analyzed using constructivist grounded theory methods. Results identify types, indicators of, and mothers' responses to boundary ambiguity throughout the five stages of change. Most mothers and abusers fluctuated between physical and psychological presence and absence over multiple separations. The integration of boundary ambiguity into the Stages of Change Model highlights the process of leaving an abusive partner as systemic, fluid, and nonlinear. © 2014 Family Process Institute.

  9. Louisiana Territorial Boundary, Geographic NAD83, LDOTD (1999) [state_boundary_la_LDOTD_1999

    Data.gov (United States)

    Louisiana Geographic Information Center — The dataset defines the state 'territorial' boundary of Louisiana. The state boundary extends 3 miles out into the Gulf of Mexico from the coastline. This data set...

  10. A Boundary Control Problem for the Viscous Cahn–Hilliard Equation with Dynamic Boundary Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Colli, Pierluigi, E-mail: pierluigi.colli@unipv.it; Gilardi, Gianni, E-mail: gianni.gilardi@unipv.it [Universitá di Pavia and Research Associate at the IMATI – C.N.R. PAVIA, Dipartimento di Matematica “F. Casorati” (Italy); Sprekels, Jürgen, E-mail: juergen.sprekels@wias-berlin.de [Weierstrass Institute (Germany)

    2016-04-15

    A boundary control problem for the viscous Cahn–Hilliard equations with possibly singular potentials and dynamic boundary conditions is studied and first order necessary conditions for optimality are proved.

  11. Grain boundaries. Progress report, February 15, 1990--October 15, 1990

    Energy Technology Data Exchange (ETDEWEB)

    Balluffi, R.W.; Bristowe, P.D.

    1990-12-31

    The following are reported: structural studies (dislocation structure of Ni/Ag interphase boundary, structural complexity in grain boundaries with covalent bonding, relation between microscopic properties of two semiconducting grain boundaries and their orientations, diffraction effects due to double positioning in (111) Au bicrystals, sensitivity of diffraction profiles to grain boundary segregation, solute segregation at grain boundaries in Au, 4-body interatomic potential for Si for defect calculations); boundary migration studies (molecular dynamics study of grain boundary migration without participation of grain boundary dislocations); study of short-circuit diffusion along grain boundaries and its dependence on boundary structure; and thin-film deposition/bonding apparatus for manufacturing high-purity bicrystals.

  12. Solution of one-dimensional moving boundary problem with periodic boundary conditions by variational iteration method

    Directory of Open Access Journals (Sweden)

    Rai Nath Kabindra Rajeev

    2009-01-01

    Full Text Available In this paper, the solution of the one dimensional moving boundary problem with periodic boundary conditions is obtained with the help of variational iterational method. By using initial and boundary values, the explicit solutions of the equations have been derived, which accelerate the rapid convergence of the series solution. The method performs extremely well in terms of efficiency and simplicity. The temperature distribution and the position of moving boundary are evaluated and numerical results are presented graphically.

  13. The Arctic Circumpolar Boundary Current

    Science.gov (United States)

    Aksenov, Yevgeny; Ivanov, Vladimir V.; Nurser, A. J. George; Bacon, Sheldon; Polyakov, Igor V.; Coward, Andrew C.; Naveira-Garabato, Alberto C.; Beszczynska-Moeller, Agnieszka

    2011-09-01

    We present high-resolution simulations and observational data as evidence of a fast current flowing along the shelf break of the Siberian and Alaskan shelves in the Arctic Ocean. Thus far, the Arctic Circumpolar Boundary Current (ACBC) has been seen as comprising two branches: the Fram Strait and Barents Sea Branches (FSB and BSB, respectively). Here we describe a new third branch, the Arctic Shelf Break Branch (ASBB). We show that the forcing mechanism for the ASBB is a combination of buoyancy loss and non-local wind, creating high pressure upstream in the Barents Sea. The potential vorticity influx through the St. Anna Trough dictates the cyclonic direction of flow of the ASBB, which is the most energetic large-scale circulation structure in the Arctic Ocean. It plays a substantial role in transporting Arctic halocline waters and exhibits a robust seasonal cycle with a summer minimum and winter maximum. The simulations show the continuity of the FSB all the way around the Arctic shelves and the uninterrupted ASBB between the St. Anna Trough and the western Fram Strait. The BSB flows continuously along the Siberian shelf as far as the Chukchi Plateau, where it partly diverges from the continental slope into the ocean interior. The Alaskan Shelf break Current (ASC) is the analog of the ASBB in the Canadian Arctic. The ASC is forced by the local winds and high upstream pressure in Bering Strait, caused by the drop in sea surface height between the Pacific and Arctic Oceans.

  14. Boundary Conditions of Methamphetamine Craving

    Science.gov (United States)

    Lopez, Richard B.; Onyemekwu, Chukwudi; Hart, Carl L.; Ochsner, Kevin N.; Kober, Hedy

    2015-01-01

    Methamphetamine use has increased significantly and become a global health concern. Craving is known to predict methamphetamine use and relapse following abstinence. Some have suggested that cravings are automatic, generalized, and uncontrollable, but experimental work addressing these claims is lacking. In two exploratory studies we tested the boundary conditions of methamphetamine craving by asking: (1) is craving specific to users’ preferred route of administration? and (2) can craving be regulated by cognitive strategies? Two groups of methamphetamine users were recruited. In Study 1, participants were grouped by their preferred route of administration (intranasal vs. smoking), and rated their craving in response to photographs and movies depicting methamphetamine use (via the intranasal vs. smoking route). In Study 2, methamphetamine smokers implemented cognitive regulation strategies while viewing photographs depicting methamphetamine smoking. Strategies involved either focusing on the positive aspects of smoking methamphetamine or the negative consequences of doing so – the latter strategy based on treatment protocols for addiction. In Study 1, we found a significant interaction between group and route of administration, such that participants who preferred to smoke methamphetamine reported significantly stronger craving for smoking stimuli, whereas those who preferred the intranasal route reported stronger craving for intranasal stimuli. In Study 2, participants reported significantly lower craving when focusing on the negative consequences associated with methamphetamine use. Taken together, these findings suggest that strength of craving for methamphetamine is moderated by users’ route of administration and can be reduced by cognitive strategies. This has important theoretical, methodological, and clinical implications. PMID:26302338

  15. Environmental boundaries to energy development

    Energy Technology Data Exchange (ETDEWEB)

    Trivelpiece, A.W.

    1989-01-01

    Public concern about the environment, health and safety consequences of energy technology has been growing steadily for more than two decades in the United States. This concern forms an important boundary condition as the United States seeks to develop a new National Energy Strategy. Furthermore, the international aspects of the energy/environment interface such as acid rain global climate change and stratospheric ozone depletion are very prominent in US thinking. In fact, the energy systems of the world are becoming more closely coupled environmentally and otherwise. Now where is this coupling more important than that between the industrialized and developing world; the choices made by each will have profound effects on the other. The development of energy technologies compatible with both economic growth and improving and sustaining environmental quality represents a major R D challenge to the US and USSR. Decision about adoption of new technology and R D priorities can be improved by better measurements of how energy sources and uses are changing throughout the world and better methods to project the potential consequences of these decisions. Such projection require understanding relative risks of alternating existing and evolving technologies. All of these R D areas, technology improvement energy system monitoring and projection and comparative risk assessment are the topics of this seminar. Progress in each may be enhanced by collaboration and cooperation between our two countries. 7 refs., 27 figs., 5 tabs.

  16. A question of fit: reflections on boundaries, organizations and social-ecological systems.

    Science.gov (United States)

    Sternlieb, Faith; Bixler, R Patrick; Huber-Stearns, Heidi; Huayhuaca, Ch'aska

    2013-11-30

    Although there is acknowledgment that the complexity of social-ecological systems governance demands representation from diverse perspectives, there is little agreement in the literature on how to cross both fiat (human-demarcated) and bona fide (physical) boundaries to address such complexities. As a cohort of interdisciplinary scholars, we navigate the boundary between science and practice to address the question of fit regarding the role of organizations in transcending boundaries. We found there is a need to rectify discrepancies between theories about boundaries and theories about organizations. To this end, we propose a conceptual framework to analyze transboundary organizations, an umbrella term to group the literature on boundary organizations, intermediaries and bridging organizations; we introduce this term to illustrate they are not mutually exclusive and to facilitate interdisciplinary research. We first examine social-ecological systems (SES), a framework intended to improve understandings of boundaries and governance. We then continue to unpack the complexity of boundaries and organizations, specifically through important transboundary concepts such as scale and organizational learning. This helps frame our examination of the literature on: 1) boundary organizations; 2) bridging organizations (third-party entities); and 3) intermediaries (distinguished by their position between other actors). Our review identifies a number of discrepancies that pertain to the types of boundaries discussed and the roles assigned to organizations governing SES. Important characteristics have emerged from our review of transboundary organizations including legitimacy, saliency, urgency, and credibility. In developing a conceptual framework, we argue that transboundary organizations: 1) expand upon the boundary spectrum, 2) incorporate transboundary concepts, and 3) hybridize characteristics of boundary, bridging, and intermediary organizations. We conclude with a number

  17. Horses for courses: analytical tools to explore planetary boundaries

    Science.gov (United States)

    van Vuuren, Detlef P.; Lucas, Paul L.; Häyhä, Tiina; Cornell, Sarah E.; Stafford-Smith, Mark

    2016-03-01

    There is a need for more integrated research on sustainable development and global environmental change. In this paper, we focus on the planetary boundaries framework to provide a systematic categorization of key research questions in relation to avoiding severe global environmental degradation. The four categories of key questions are those that relate to (1) the underlying processes and selection of key indicators for planetary boundaries, (2) understanding the impacts of environmental pressure and connections between different types of impacts, (3) better understanding of different response strategies to avoid further degradation, and (4) the available instruments to implement such strategies. Clearly, different categories of scientific disciplines and associated model types exist that can accommodate answering these questions. We identify the strength and weaknesses of different research areas in relation to the question categories, focusing specifically on different types of models. We discuss that more interdisciplinary research is need to increase our understanding by better linking human drivers and social and biophysical impacts. This requires better collaboration between relevant disciplines (associated with the model types), either by exchanging information or by fully linking or integrating them. As fully integrated models can become too complex, the appropriate type of model (the racehorse) should be applied for answering the target research question (the race course).

  18. African colonial boundaries and nation-building

    African Journals Online (AJOL)

    HDS 10

    Britain, France, Germany, Portugal and Belgium. The aim was to stop the issue from degenerating into open war (Afigbo. 1990:129). One major aspect of Africa's colonial heritage is colonial boundaries. Many colonial boundaries in Africa date back to the Berlin conference of 1884-1885, which climaxed the scramble and ...

  19. A note on Weak Stability Boundaries

    OpenAIRE

    García González, Fernando; Gómez Muntané, Gerard

    2006-01-01

    This paper is devoted to clarify the algorithmic definition of the weak stability boundary in the framework of the planar Restricted Three Body Problem. The role of the invariant hyperbolic manifolds associated to the central manifolds of the libration points L1 and L2, as boundary of the weak stability region, is shown Peer Reviewed

  20. Grain boundaries in high temperature superconductors

    NARCIS (Netherlands)

    Hilgenkamp, Johannes W.M.; Mannhart, J.

    2002-01-01

    Since the first days of high-Tc superconductivity, the materials science and the physics of grain boundaries in superconducting compounds have developed into fascinating fields of research. Unique electronic properties, different from those of the grain boundaries in conventional metallic

  1. Boundary Management for Cognitive Behavioral Therapies

    Science.gov (United States)

    Gottlieb, Michael C.; Younggren, Jeffrey N.; Murch, Kevin B.

    2009-01-01

    In recent years, the scholarship regarding professional boundaries has increased significantly in a variety of areas. Despite many advances in this line of research, less attention has been devoted to the question of boundary maintenance and its relationship to theoretical orientation. In this article we examine these issues for…

  2. Classical BV theories on manifolds with boundary

    NARCIS (Netherlands)

    Cattaneo, A.S.; Mnev, P.; Reshetikhin, N.

    2014-01-01

    In this paper we extend the classical BV framework to gauge theories on spacetime manifolds with boundary. In particular, we connect the BV construction in the bulk with the BFV construction on the boundary and we develop its extension to strata of higher codimension in the case of manifolds with

  3. Modelling stable atmospheric boundary layers over snow

    NARCIS (Netherlands)

    Sterk, H.A.M.

    2015-01-01

    Thesis entitled: Modelling Stable Atmospheric Boundary Layers over Snow H.A.M. Sterk Wageningen, 29th of April, 2015 Summary The emphasis of this thesis is on the understanding and forecasting of the Stable Boundary Layer (SBL) over snow-covered surfaces. SBLs typically form at night and in polar

  4. Effect of grain boundary misorientation on discontinuous ...

    Indian Academy of Sciences (India)

    Administrator

    showed that the discontinuous precipitation (DP) reaction rate was dependent on the geometry of the grain boundary in ... 80% thickness reduction) had no effect on the frequency of special-grain boundaries. Keywords. AZ91 alloy .... increasing solute concentration, the influence of the ener- getics and kinetics is diminished ...

  5. Green's functions for Neumann boundary conditions

    OpenAIRE

    Franklin, Jerrold

    2012-01-01

    Green's functions for Neumann boundary conditions have been considered in Math Physics and Electromagnetism textbooks, but special constraints and other properties required for Neumann boundary conditions have generally not been noticed or treated correctly. In this paper, we derive an appropriate Neumann Green's function with these constraints and properties incorporated.

  6. Knowledge Sharing Across Global-Local Boundaries

    DEFF Research Database (Denmark)

    Zølner, Mette

    The paper explores how locals span boundaries between corporate and local levels. The aim is to better comprehend potentialities and challenges when MNCs draws on locals’ culture specific knowledge. The study is based on an in-depth, interpretive case study of boundary spanning by local actors...

  7. Boundary Value Problems and Approximate Solutions

    African Journals Online (AJOL)

    Tadesse

    2. METHODOLOGY. The finite difference method for the solution of a two point boundary value problem consists in replacing the derivatives present in the differential equation and the boundary conditions with the help of finite difference approximations and then solving the resulting linear system of equations by a standard ...

  8. Professional boundary violations: a literature review.

    Science.gov (United States)

    Manfrin-Ledet, Linda; Porche, Demetrius J; Eymard, Amanda S

    2015-06-01

    The purpose of this article is to review the nursing literature related to professional boundary violations in nursing. A search was conducted using CINAHL, MEDLINE, Ebscohost, and NCSBN. The key words searched were professional boundaries, boundary violation, boundary crossings, nurse, home health nurses, and home nursing. The search returned over 40 publications related specifically to boundary violations and nursing although only four of them are published research studies and one as a dissertation. Seven common characteristics emerged from the nonresearch nursing articles on professional boundaries: (1) Dual relations/role reversal, (2) Gifts and money, (3) Excessive self-disclosure, (4) Secretive behavior, (5) Excessive attention/overinvolvement, (6) Sexual behavior, and (7) Social media. Additional nursing research is greatly needed in the area of professional boundaries. The nurse-patient relationship should always be maintained for the benefit of the patient and not the personal gain of the nurse. Ongoing education in nursing practice regarding professional boundaries is needed. Nurses need to be mindful of state practice acts, codes of conduct, and employer policies.

  9. Recent advances in boundary element methods

    CERN Document Server

    Manolis, GD

    2009-01-01

    Addresses the needs of the computational mechanics research community in terms of information on boundary integral equation-based methods and techniques applied to a variety of fields. This book collects both original and review articles on contemporary Boundary Element Methods (BEM) as well as on the Mesh Reduction Methods (MRM).

  10. Millennial Values and Boundaries in the Classroom

    Science.gov (United States)

    Espinoza, Chip

    2012-01-01

    Students' relationships with authority and information are changing rapidly, and this presents a new set of interpersonal boundary challenges for faculty. The topic of setting boundaries often conjures up thoughts of how to protect oneself. The intent of this chapter is to explore how good rapport between teacher and student can be developed and…

  11. Flexibility of event boundaries in autobiographical memory.

    Science.gov (United States)

    Hohman, Timothy J; Peynircioğlu, Zehra F; Beason-Held, Lori L

    2013-01-01

    Events have clear and consistent boundaries that are defined during perception in a manner that influences memory performance. The natural process of event segmentation shapes event definitions during perception, and appears to play a critical role in defining distinct episodic memories at encoding. However, the role of retrieval processes in modifying event definitions is not clear. We explored how such processes changed event boundary definitions at recall. In Experiment 1 we showed that distance from encoding is related to boundary flexibility. Participants were more likely to move self-reported event boundaries to include information reported beyond those boundaries when recalling more distant events compared to more recent events. In Experiment 2 we showed that age also influenced boundary flexibility. Older Age adults were more likely to move event boundaries than College Age adults, and the relationship between distance from encoding and boundary flexibility seen in Experiment 1 was present only in College Age and Middle Age adults. These results suggest that factors at retrieval have a direct impact on event definitions in memory and that, although episodic memories may be initially defined at encoding, these definitions are not necessarily maintained in long-term memory.

  12. Structure and Dynamics at Colloidal Boundaries

    NARCIS (Netherlands)

    de Villeneuve, V.W.A.

    2008-01-01

    This thesis is made up of several studies of boundaries occurring in colloidal hard sphere crystals and phase separated colloid-polymer mixtures. These boundaries can be studied on the particle level, in real space and in real time by confocal microscopy. A general introduction on the experimental

  13. How do Economic Crises Impact Firm Boundaries?

    DEFF Research Database (Denmark)

    Foss, Kirsten

    2010-01-01

    How economic crises impact the boundaries of firms has been offered virtually no attention in the literature on the theory of the firm. I review the best-known theories of the firm and identify the variables that matter for the explanation of firm boundaries. I then examine how an economic crisis...

  14. The transactional approach in company boundaries

    Directory of Open Access Journals (Sweden)

    Bruno Chaihuaque Dueñas

    2009-12-01

    Full Text Available This article shows the relationship between market and firms through the theory of transactional cost and the relationsthat determine the structure and boundaries of the firm. Using the assumptions from the transactional cost approach,this article proposes some variables that determine optimal organizational structures and their boundaries.

  15. Magnetohydrodynamic cross-field boundary layer flow

    Directory of Open Access Journals (Sweden)

    D. B. Ingham

    1982-01-01

    Full Text Available The Blasius boundary layer on a flat plate in the presence of a constant ambient magnetic field is examined. A numerical integration of the MHD boundary layer equations from the leading edge is presented showing how the asymptotic solution described by Sears is approached.

  16. Assessing housing growth when census boundaries change

    Science.gov (United States)

    Alexandra D. Syphard; Susan I. Stewart; Jason McKeefry; Roger B. Hammer; Jeremy S. Fried; Sherry Holcomb; Volker C. Radeloff

    2009-01-01

    The US Census provides the primary source of spatially explicit social data, but changing block boundaries complicate analyses of housing growth over time. We compared procedures for reconciling housing density data between 1990 and 2000 census block boundaries in order to assess the sensitivity of analytical methods to estimates of housing growth in Oregon. Estimates...

  17. Prior Information in Inverse Boundary Problems

    DEFF Research Database (Denmark)

    Garde, Henrik

    the change in distinguishability of inclusions (support of an inhomogeneity) as they are placed closer towards the measurement boundary. This is done by determining eigenvalue bounds for differences of pseudodifferential operators on the boundary of the domain. Ultimately, the bounds serves as insight...

  18. Theraputic relationship versus boundary transgressions: Lessons for ...

    African Journals Online (AJOL)

    No therapy exists in a vacuum. It involves striking relationship between the therapists and clients. Such relationships are relationships of trust and are therefore meant to be maintained religiously by adhering strictly to ethnical codes of conduct. However, most times, boundary transgression are inevitable. While boundary ...

  19. Acoustic reflection from the boundary of anisotropic ...

    Indian Academy of Sciences (India)

    MS received 10 December 2008; revised 4 May 2009. Abstract. Vertical slownesses of waves at a boundary of an anisotropic thermoviscoelastic medium are calculated as roots of a polynomial equation of degree eight. Out of the corresponding eight waves, the four, which travel towards the boundary are identified as ...

  20. Boundary conditions for the gravitational field

    Science.gov (United States)

    Winicour, Jeffrey

    2012-06-01

    A review of the treatment of boundaries in general relativity is presented with the emphasis on application to the formulations of Einstein's equations used in numerical relativity. At present, it is known how to treat boundaries in the harmonic formulation of Einstein's equations and a tetrad formulation of the Einstein-Bianchi system. However, a universal approach valid for other formulations is not in hand. In particular, there is no satisfactory boundary theory for the 3+1 formulations which have been highly successful in binary black hole simulation. I discuss the underlying problems that make the initial-boundary-value problem much more complicated than the Cauchy problem. I review the progress that has been made and the important open questions that remain. Science is a differential equation. Religion is a boundary condition. (Alan Turing, quoted in J D Barrow, ‘Theories of Everything’)

  1. The boundary characteristics of lucid dreamers.

    Science.gov (United States)

    Galvin, F

    1990-06-01

    Based on the previously established personality correlates of frequent lucid dreaming and frequent nightmare dreaming, several hypotheses were generated regarding the boundary characteristics of these dreamers relative to each other and to a control group of non-lucid and comparatively nightmare-free dreamers. The data from Hartmann's Boundary Questionnaire obtained from 40 subjects in each dreamer group (who were individually matched for sex, age, and background as far as possible) were analyzed. The results of the study give evidence that lucid dreamers have "thin" boundaries in many of the same senses that nightmare sufferers do, but can be differentiated from nightmare dreamers by the greater degree of coherence of their psychological sense of self as measured on the Self-Coherence Subscale of the Boundary Questionnaire. The suggestion is made that, given the similarity of "thin" boundaries, perhaps nightmare sufferers could become lucid dreamers and possibly resolve their nightmare condition while in the dream state.

  2. Properties of a cusp diamagnetic cavity boundary

    Directory of Open Access Journals (Sweden)

    B. M. Walsh

    2008-11-01

    Full Text Available While crossing through the high-altitude dayside cusp on 29 September 1978 and again on 30 October 1978, the ISEE-1 spacecraft observed enhanced energetic particle flux and a depressed and turbulent magnetic field, the signature characteristics of a cusp diamagnetic cavity. As ISEE-1 approached the cavity during each event, a boundary sounding technique was used to measure properties of an emitting boundary. Sounding over multiple energy channels reveals an energy dependent boundary with lower energy particles filling a larger cavity than higher energy particles. Relative motion of the boundary as well as boundary orientation are also measured. The two cusp events were measured at different locations and during different geomagnetic and solar wind conditions; however, they show similar results.

  3. Properties of a cusp diamagnetic cavity boundary

    Science.gov (United States)

    Walsh, B. M.; Fritz, T. A.; Chen, J.

    2008-11-01

    While crossing through the high-altitude dayside cusp on 29 September 1978 and again on 30 October 1978, the ISEE-1 spacecraft observed enhanced energetic particle flux and a depressed and turbulent magnetic field, the signature characteristics of a cusp diamagnetic cavity. As ISEE-1 approached the cavity during each event, a boundary sounding technique was used to measure properties of an emitting boundary. Sounding over multiple energy channels reveals an energy dependent boundary with lower energy particles filling a larger cavity than higher energy particles. Relative motion of the boundary as well as boundary orientation are also measured. The two cusp events were measured at different locations and during different geomagnetic and solar wind conditions; however, they show similar results.

  4. Long-lived force patterns and deformation waves at repulsive epithelial boundaries

    Science.gov (United States)

    Rodríguez-Franco, Pilar; Brugués, Agustí; Marín-Llauradó, Ariadna; Conte, Vito; Solanas, Guiomar; Batlle, Eduard; Fredberg, Jeffrey J.; Roca-Cusachs, Pere; Sunyer, Raimon; Trepat, Xavier

    2017-10-01

    For an organism to develop and maintain homeostasis, cell types with distinct functions must often be separated by physical boundaries. The formation and maintenance of such boundaries are commonly attributed to mechanisms restricted to the cells lining the boundary. Here we show that, besides these local subcellular mechanisms, the formation and maintenance of tissue boundaries involves long-lived, long-ranged mechanical events. Following contact between two epithelial monolayers expressing, respectively, EphB2 and its ligand ephrinB1, both monolayers exhibit oscillatory patterns of traction forces and intercellular stresses that tend to pull cell-matrix adhesions away from the boundary. With time, monolayers jam, accompanied by the emergence of deformation waves that propagate away from the boundary. This phenomenon is not specific to EphB2/ephrinB1 repulsion but is also present during the formation of boundaries with an inert interface and during fusion of homotypic epithelial layers. Our findings thus unveil a global physical mechanism that sustains tissue separation independently of the biochemical and mechanical features of the local tissue boundary.

  5. Grain Boundary Sliding in Deforming Wehrlite: Rheology and Microstructure

    Science.gov (United States)

    Zhao, N.; Hirth, G.; Cooper, R. F.; Kruckenberg, S. C.

    2016-12-01

    Elastic anisotropy of Earth's upper mantle used to be attributed exclusively to dislocation creep. However, recent experimental results suggest that crystallographic preferred orientation (CPO) in olivine, which contributes to elastic anisotropy, could also form during grain boundary sliding [e.g., 1-3]. Nevertheless, the fundamental problem of how CPO forms during grain boundary sliding is not fully understood. Our current efforts examine the grain-size-sensitive flow of wehrlite, to characterize the influence of the second phase (clinopyroxene) both on olivine CPO formation as well as the propensity of grain boundary sliding and accumulated strain to effect solid-state phase separation (i.e., metamorphic layering). Creep tests on fine-grain-size (2-5 µm) olivine and clinopyroxene aggregates (T =1100-1200ºC; P = 1.5 GPa; γ=3-7) have been conducted. These reveal strong type-B fabric for olivine. Characterization of effects of grain size, temperature and applied strain rate reveal the grain size dependence, stress exponent and activation energy of the flow kinetics of wehrlite. The stress exponent, which is similar to stress exponent for harzburgite reported by Sundberg & Cooper [1], and grain-size dependence suggest that the dominant deformation mechanism in our experiments may be grain boundary sliding. A large stress drop in early segments of experiments suggest an evolution of microstructure. The Fourier transform of backscatter images demonstrates that there exists a direction of foliation, defined by Ol-Cpx heterophase boundaries, which may be the key to understand the development of CPO formation. [1] Sundberg, M. & Cooper, R. F., J. Geophys. Res., 2008. [2] Miyazaki, T., Sueyoshi, K., and Hiraga, T., Nature, 2013. [3] Tielke, J. A., L. N. Hansen, M. Tasaka, C. Meyers, M. E. Zimmerman, and D. L. Kohlstedt, J. Geophys. Res., 2016.

  6. Polarity of translation boundaries in antiferroelectric PbZrO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Xian-Kui, E-mail: xiankui.wei@epfl.ch [Ceramics Laboratory, EPFL–Swiss Federal Institute of Technology, Lausanne 1015 (Switzerland); Peter Grünberg Institute and Ernst Ruska Center for Microscopy and Spectroscopy with Electrons, Research Center Jülich, 52425 Jülich (Germany); Jia, Chun-Lin [Peter Grünberg Institute and Ernst Ruska Center for Microscopy and Spectroscopy with Electrons, Research Center Jülich, 52425 Jülich (Germany); International Centre of Dielectric Research, The School of Electronic and Information Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Roleder, Krystian [Institute of Physics, University of Silesia, Katowice 40007 (Poland); Setter, Nava [Ceramics Laboratory, EPFL–Swiss Federal Institute of Technology, Lausanne 1015 (Switzerland)

    2015-02-15

    Graphical abstract: Strain-free rigid model and aberration-corrected transmission electron microscopes are used to investigate the polarity of translation boundaries in antiferroelectric PbZrO{sub 3}. - Highlights: • Domain boundaries in antiferroelectric PbZrO{sub 3} show polar and antipolar property. • The antiphase boundary can split into “sub-domains”. • Polarization reversal possibly exists inside the translation boundaries. • Thermal treatment can alter morphology and density of the translation boundaries. - Abstract: The polarity of translation boundaries (TBs) in antiferroelectric PbZrO{sub 3} is investigated. We show that previous experimentally reported polar property of R{sub III-1} type TB can be well approximated by a strain-free rigid model. Based on this, the modeling investigation suggests that there are two additional polar TBs, three antipolar-like TBs and one antipolar antiphase boundary. High-resolution scanning-transmission-electron-microscopy study reveals that the straight R{sub III-1} type TB can split into “sub-domains” with possible polarization reversal, suggesting the occurrence of ferroic orders at the TBs. In addition, dependence of morphology and density of the TBs on thermal treatments is discussed according to our results.

  7. A Genetic Algorithm and Fuzzy Logic Approach for Video Shot Boundary Detection.

    Science.gov (United States)

    Thounaojam, Dalton Meitei; Khelchandra, Thongam; Manglem Singh, Kh; Roy, Sudipta

    2016-01-01

    This paper proposed a shot boundary detection approach using Genetic Algorithm and Fuzzy Logic. In this, the membership functions of the fuzzy system are calculated using Genetic Algorithm by taking preobserved actual values for shot boundaries. The classification of the types of shot transitions is done by the fuzzy system. Experimental results show that the accuracy of the shot boundary detection increases with the increase in iterations or generations of the GA optimization process. The proposed system is compared to latest techniques and yields better result in terms of F1score parameter.

  8. In Situ Studies on the Irradiation-Induced Twin Boundary-Defect Interactions in Cu

    Science.gov (United States)

    Fan, C.; Li, Jin; Fan, Zhe; Wang, H.; Zhang, X.

    2017-11-01

    Polycrystalline Cu films with nanoscale annealing twins are subjected to in situ Kr++ ion irradiation at room temperature inside a transmission electron microscope up to a dose of 1 displacement-per-atom. Radiation induces prominent migration of incoherent twin boundaries. Depending on twin thickness, three types of twin boundary evolutions are observed, including rapid detwinning, gradual detwinning, and self-healing. The mechanism of twin thickness-dependent evolution of microstructures is discussed. This study provides further evidence on twin boundary-defect interactions and may assist the design of radiation-tolerant twinned metallic materials.

  9. Toward the Approximate Solution for Fractional Order Nonlinear Mixed Derivative and Nonlocal Boundary Value Problems

    Directory of Open Access Journals (Sweden)

    Hammad Khalil

    2016-01-01

    Full Text Available The paper is devoted to the study of operational matrix method for approximating solution for nonlinear coupled system fractional differential equations. The main aim of this paper is to approximate solution for the problem under two different types of boundary conditions, m^-point nonlocal boundary conditions and mixed derivative boundary conditions. We develop some new operational matrices. These matrices are used along with some previously derived results to convert the problem under consideration into a system of easily solvable matrix equations. The convergence of the developed scheme is studied analytically and is conformed by solving some test problems.

  10. Structure of high angle grain boundaries in metals and ceramic oxides

    Energy Technology Data Exchange (ETDEWEB)

    Balluffi, R.W.; Bristowe, P.D.; Sun, C.P.

    1979-12-01

    A critical review is given of the state of our current knowledge of the structure of high angle grain boundaries in metals and in ceramic oxides. Particular attention is given to effects due to differences in the bonding and crystal structure in these solid types. The results of recent experimental work and efforts to model grain boundary structure using computer simulation methods are described. Important characteristic features of boundaries in these materials are discussed. Difficulties which are presently being encountered in efforts to determine their structure are pointed out.

  11. On the Derivation of Boundary Conditions for Continuum Dislocation Dynamics

    Directory of Open Access Journals (Sweden)

    Thomas Hochrainer

    2017-07-01

    Full Text Available Continuum dislocation dynamics (CDD is a single crystal strain gradient plasticity theory based exclusively on the evolution of the dislocation state. Recently, we derived a constitutive theory for the average dislocation velocity in CDD in a phase field-type description for an infinite domain. In the current work, so-called rational thermodynamics is employed to obtain thermodynamically consistent boundary conditions for the dislocation density variables of CDD. We find that rational thermodynamics reproduces the bulk constitutive equations as obtained from irreversible thermodynamics. The boundary conditions we find display strong parallels to the microscopic traction conditions derived by Gurtin and Needleman (M.E. Gurtin and A. Needleman, J. Mech. Phys. Solids 53 (2005 1–31 for strain gradient theories based on the Kröner–Nye tensor.

  12. Boundary-layer turbulence as a kangaroo process

    Science.gov (United States)

    Dekker, H.; de Leeuw, G.; Maassen van den Brink, A.

    1995-09-01

    A nonlocal mixing-length theory of turbulence transport by finite size eddies is developed by means of a novel evaluation of the Reynolds stress. The analysis involves the contruct of a sample path space and a stochastic closure hypothesis. The simplifying property of exhange (strong eddies) is satisfied by an analytical sampling rate model. A nonlinear scaling relation maps the path space onto the semi-infinite boundary layer. The underlying near-wall behavior of fluctuating velocities perfectly agrees with recent direct numerical simulations. The resulting integro-differential equation for the mixing of scalar densities represents fully developed boundary-layer turbulence as a nondiffusive (Kubo-Anderson or kangaroo) type of stochastic process. The model involves a scaling exponent ɛ (with ɛ-->∞ in the diffusion limit). For the (partly analytical) solution for the mean velocity profile, excellent agreement with the experimental data yields ɛ~=0.58.

  13. Finite difference numerical methods for boundary control problems governed by hyperbolic partial differential equations

    Science.gov (United States)

    Chen, G.; Zheng, Q.; Coleman, M.; Weerakoon, S.

    1983-01-01

    This paper briefly reviews convergent finite difference schemes for hyperbolic initial boundary value problems and their applications to boundary control systems of hyperbolic type which arise in the modelling of vibrations. These difference schemes are combined with the primal and the dual approaches to compute the optimal control in the unconstrained case, as well as the case when the control is subject to inequality constraints. Some of the preliminary numerical results are also presented.

  14. Elliptic Boundary Value Problems with Fractional Regularity Data: The First Order Approach

    OpenAIRE

    Amenta, Alex; Auscher, Pascal

    2016-01-01

    We study well-posedness of boundary value problems of Dirichlet and Neumann type for elliptic systems on the upper half-space with coefficients independent of the transversal variable, and with boundary data in fractional Besov-Hardy-Sobolev (BHS) spaces. Our approach uses minimal assumptions on the coefficients, and in particular does not require De Giorgi-Nash-Moser estimates. Our results are completely new for the Hardy-Sobolev case, and in the Besov case they extend results recently obtai...

  15. Dislocation Nucleation on Grain Boundaries: Low Angle Twist and Asymmetric Tilt Boundaries

    Directory of Open Access Journals (Sweden)

    Erman Guleryuz

    2016-07-01

    Full Text Available We investigate the mechanisms of incipient plasticity at low angle twist and asymmetric tilt boundaries in fcc metals. To observe plasticity of grain boundaries independently of the bulk plasticity, we simulate nanoindentation of bicrystals. On the low angle twist boundaries, the intrinsic grain boundary (GB dislocation network deforms under load until a dislocation segment compatible with glide on a lattice slip plane is created. The half loops are then emitted into the bulk of the crystal. Asymmetric twist boundaries considered here did not produce bulk dislocations under load. Instead, the boundary with a low excess volume nucleated a mobile GB dislocation and additional GB defects. The GB sliding proceeded by motion of the mobile GB dislocation. The boundary with a high excess volume sheared elastically, while bulk-nucleated dislocations produced plastic relaxation.

  16. Boundary definition of a multiverse measure

    Science.gov (United States)

    Bousso, Raphael; Freivogel, Ben; Leichenauer, Stefan; Rosenhaus, Vladimir

    2010-12-01

    We propose to regulate the infinities of eternal inflation by relating a late time cutoff in the bulk to a short-distance cutoff on the future boundary. The light-cone time of an event is defined in terms of the volume of its future light cone on the boundary. We seek an intrinsic definition of boundary volumes that makes no reference to bulk structures. This requires taming the fractal geometry of the future boundary and lifting the ambiguity of the conformal factor. We propose to work in the conformal frame in which the boundary Ricci scalar is constant. We explore this proposal in the Friedmann-Robertson-Walker approximation for bubble universes. Remarkably, we find that the future boundary becomes a round three-sphere, with smooth metric on all scales. Our cutoff yields the same relative probabilities as a previous proposal that defined boundary volumes by projection into the bulk along timelike geodesics. Moreover, it is equivalent to an ensemble of causal patches defined without reference to bulk geodesics. It thus yields a holographically motivated and phenomenologically successful measure for eternal inflation.

  17. Tectonics of oblique plate boundary systems

    Science.gov (United States)

    Díaz-Azpiroz, Manuel; Brune, Sascha; Leever, Karen A.; Fernández, Carlos; Czeck, Dyanna M.

    2016-12-01

    The relative displacement between lithospheric plates normally results in obliquely deforming plate boundaries. This is simply caused by the fact that, on plate tectonics basis, irregularly shaped plate boundaries are rarely perpendicular or parallel to small-circle rotation paths, which describe plate motion on a sphere (Fig. 1a). Global current relative plate motions estimated from geological data (DeMets et al., 2010; Argus et al., 2011) and GPS measurements (e.g., Kreemer et al., 2003; Argus et al., 2010) provide insight to the prevalent degrees of obliquity on Earth's surface. Based on these global data sets, Philippon and Corti (2016), statistically show that current orthogonal boundaries (obliquity angle smaller than 10°) represent around 8% of the total boundary length whereas strike-slip boundaries (obliquity angle larger than 80°) are encountered in plate boundaries present oblique relative motions. Furthermore, changes in plate kinematics leading to migration or jumps in the rotation poles necessarily cause obliquity along former pure strike-slip or convergent/divergent boundaries (Fig. 1b).

  18. 78 FR 44596 - Minor Boundary Revision at Yosemite National Park

    Science.gov (United States)

    2013-07-24

    ... National Park Service Minor Boundary Revision at Yosemite National Park AGENCY: National Park Service, Interior. ACTION: Notification of Boundary Revision. SUMMARY: The boundary of Yosemite National Park is... boundary of Yosemite National Park. DATES: The effective date of this boundary revision is July 24, 2013...

  19. Symmetries and Boundary Conditions with a Twist

    Science.gov (United States)

    Zawadzki, Krissia; D'Amico, Irene; Oliveira, Luiz N.

    2017-10-01

    Interest in finite-size systems has risen in the last decades, due to the focus on nanotechnological applications and because they are convenient for numerical treatment that can subsequently be extrapolated to infinite lattices. Independently of the envisioned application, special attention must be given to boundary condition, which may or may not preserve the symmetry of the infinite lattice. Here, we present a detailed study of the compatibility between boundary conditions and conservation laws. The conflict between open boundary conditions and momentum conservation is well understood, but we examine other symmetries, as well: we discuss gauge invariance, inversion, spin, and particle-hole symmetry and their compatibility with open, periodic, and twisted boundary conditions. In the interest of clarity, we develop the reasoning in the framework of the one-dimensional half-filled Hubbard model, whose Hamiltonian displays a variety of symmetries. Our discussion includes analytical and numerical results. Our analytical survey shows that, as a rule, boundary conditions break one or more symmetries of the infinite-lattice Hamiltonian. The exception is twisted boundary condition with the special torsion Θ = πL/2, where L is the lattice size. Our numerical results for the ground-state energy at half-filling and the energy gap for L = 2-7 show how the breaking of symmetry affects the convergence to the L → ∞ limit. We compare the computed energies and gaps with the exact results for the infinite lattice drawn from the Bethe-Ansatz solution. The deviations are boundary-condition dependent. The special torsion yields more rapid convergence than open or periodic boundary conditions. For sizes as small as L = 7, the numerical results for twisted condition are very close to the L → ∞ limit. We also discuss the ground-state electronic density and magnetization at half filling under the three boundary conditions.

  20. Twin boundaries in d-wave superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Feder, D.L.; Beardsall, A.; Berlinsky, A.J.; Kallin, C. [Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1 (Canada)

    1997-09-01

    Twin boundaries in orthorhombic d-wave superconductors are investigated numerically using the Bogoliubov{endash}deGennes formalism within the context of an extended Hubbard model. The twin boundaries are represented by tetragonal regions of variable width, with a reduced chemical potential. For sufficiently large twin boundary width and change in chemical potential, an induced s-wave component may break time-reversal symmetry at a low temperature T{sup {asterisk}}. The temperature T{sup {asterisk}}, and the magnitude of the imaginary component, are found to depend strongly on electron density. The results are compared with recent tunneling measurements. {copyright} {ital 1997} {ital The American Physical Society}

  1. Boundary Value Problems Arising in Kalman Filtering

    Directory of Open Access Journals (Sweden)

    Bashirov Agamirza

    2008-01-01

    Full Text Available The classic Kalman filtering equations for independent and correlated white noises are ordinary differential equations (deterministic or stochastic with the respective initial conditions. Changing the noise processes by taking them to be more realistic wide band noises or delayed white noises creates challenging partial differential equations with initial and boundary conditions. In this paper, we are aimed to give a survey of this connection between Kalman filtering and boundary value problems, bringing them into the attention of mathematicians as well as engineers dealing with Kalman filtering and boundary value problems.

  2. Boundary Value Problems Arising in Kalman Filtering

    Directory of Open Access Journals (Sweden)

    Sinem Ertürk

    2009-01-01

    Full Text Available The classic Kalman filtering equations for independent and correlated white noises are ordinary differential equations (deterministic or stochastic with the respective initial conditions. Changing the noise processes by taking them to be more realistic wide band noises or delayed white noises creates challenging partial differential equations with initial and boundary conditions. In this paper, we are aimed to give a survey of this connection between Kalman filtering and boundary value problems, bringing them into the attention of mathematicians as well as engineers dealing with Kalman filtering and boundary value problems.

  3. Optimal Wentzell Boundary Control of Parabolic Equations

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Yousong, E-mail: yousong.luo@rmit.edu.au [RMIT University, School of Mathematical and Geospatial Sciences (Australia)

    2017-04-15

    This paper deals with a class of optimal control problems governed by an initial-boundary value problem of a parabolic equation. The case of semi-linear boundary control is studied where the control is applied to the system via the Wentzell boundary condition. The differentiability of the state variable with respect to the control is established and hence a necessary condition is derived for the optimal solution in the case of both unconstrained and constrained problems. The condition is also sufficient for the unconstrained convex problems. A second order condition is also derived.

  4. Generalizations of the Abstract Boundary singularity theorem

    CERN Document Server

    Whale, Ben E; Scott, Susan M

    2015-01-01

    The Abstract Boundary singularity theorem was first proven by Ashley and Scott. It links the existence of incomplete causal geodesics in strongly causal, maximally extended spacetimes to the existence of Abstract Boundary essential singularities, i.e., non-removable singular boundary points. We give two generalizations of this theorem: the first to continuous causal curves and the distinguishing condition, the second to locally Lipschitz curves in manifolds such that no inextendible locally Lipschitz curve is totally imprisoned. To do this we extend generalized affine parameters from $C^1$ curves to locally Lipschitz curves.

  5. A global climatology of boundary layer ventilation

    Science.gov (United States)

    McNamara, David; Plant, Robert; Belcher, Stephen

    2013-04-01

    The general circulation pattern of the Earth's atmosphere is well known, however there has been relatively little effort to quantify the climatological effects of the buffer zone known as the atmospheric boundary layer. Turbulent motions in the atmospheric boundary layer act to mix the layer along with its constituent pollutants, below a temperature inversion which separates it from the free troposphere. Exchanges between the boundary layer and free troposphere can occur through the mechanisms of convection, isentropic uplift, and coastal and orographic venting. In particular the rate at which pollutants are removed from the atmosphere can be different depending on whether or not they are resident within the boundary layer or the free troposphere. Thus the limiting factor on the concentrations of, for example, certain eg NOx, pollutants in the free troposphere will be the rate at which they are vented from the boundary layer. A global climatology (spanning 10 years between 1995 and 2005) of boundary layer venting is presented here using the ERA-interim dataset which has a grid scale resolution of 0.7 degrees x 0.7 degrees. The boundary layer height is first calculated using a bulk Richardson number method and then an associated vertical velocity is found by linearly interpolating between the two model levels either side of the boundary layer height. This value along with the change in height of the boundary layer over a 3 hour period is used to give an estimate of the rate of venting. The climatology of this rate allows us to describe and quantify the areas of the globe that are responsible for boundary layer entrainment and boundary layer venting, which could be used as a basis for further comparisons with other suitable datasets. We will also present results for the climatology of the boundary layer height itself. [possibly? That could be attractive for a BL audience anyway] Furthermore we will present and discuss results from a method designed to isolate the

  6. Boundary value problems and partial differential equations

    CERN Document Server

    Powers, David L

    2005-01-01

    Boundary Value Problems is the leading text on boundary value problems and Fourier series. The author, David Powers, (Clarkson) has written a thorough, theoretical overview of solving boundary value problems involving partial differential equations by the methods of separation of variables. Professors and students agree that the author is a master at creating linear problems that adroitly illustrate the techniques of separation of variables used to solve science and engineering.* CD with animations and graphics of solutions, additional exercises and chapter review questions* Nearly 900 exercises ranging in difficulty* Many fully worked examples

  7. Fully nonlinear boundary value problems with impulse

    Directory of Open Access Journals (Sweden)

    Paul Eloe

    2011-04-01

    Full Text Available An impulsive boundary value problem with nonlinear boundary conditions for a second order ordinary differential equation is studied. In particular, sufficient conditions are provided so that a compression - expansion cone theoretic fixed point theorem can be applied to imply the existence of positive solutions. The nonlinear forcing term is assumed to satisfy usual sublinear or superlinear growth as $t\\rightarrow\\infty$ or $t\\rightarrow 0^+$. The nonlinear impulse terms and the nonlinear boundary terms are assumed to satisfy the analogous asymptotic behavior.

  8. Identifying Phase Space Boundaries with Voronoi Tessellations

    CERN Document Server

    Debnath, Dipsikha; Kilic, Can; Kim, Doojin; Matchev, Konstantin T.; Yang, Yuan-Pao

    2016-11-24

    Determining the masses of new physics particles appearing in decay chains is an important and longstanding problem in high energy phenomenology. Recently it has been shown that these mass measurements can be improved by utilizing the boundary of the allowed region in the fully differentiable phase space in its full dimensionality. Here we show that the practical challenge of identifying this boundary can be solved using techniques based on the geometric properties of the cells resulting from Voronoi tessellations of the relevant data. The robust detection of such phase space boundaries in the data could also be used to corroborate a new physics discovery based on a cut-and-count analysis.

  9. Modelling classroom conditions with different boundary conditions

    DEFF Research Database (Denmark)

    Marbjerg, Gerd Høy; Jeong, Cheol-Ho; Brunskog, Jonas

    2014-01-01

    A model that combines image source modelling and acoustical radiosity with complex boundary condition, thus including phase shifts on reflection has been developed. The model is called PARISM (Phased Acoustical Radiosity and Image Source Model). It has been developed in order to be able to model...... are done using different boundary conditions in order to investigate the influence of phase shifts in reflections, the angle dependence of the reflection coefficient and the scattering coefficient. The focus of the simulations is to investigate the influence of the boundary condition on room acoustic...

  10. Maintaining professional boundaries: keep your distance.

    Science.gov (United States)

    Griffith, Richard; Tengnah, Cassam

    2013-01-01

    Maintaining professional boundaries is essential to an effective nurse-patient relation whose sole focus must be on the care and treatment needs of the patient. Complaints about failures to maintain professional boundaries are increasing, with the Nursing and Midwifery Council reporting some 247 new cases in the year 2012-12. The article outlines the scope of the nurse-patient relationship, what activity is considered to be outside the professional and considers the consequences for community nurses if they are found to have breached a professional boundary.

  11. Dislocation structure and energy of high angle (001) twist boundaries: A computer simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, D.; Bristowe, P.D.; Vitek, V.

    1988-03-01

    High angle (001) twist boundaries have been frequently investigated experimentally and the presence of grain boundary dislocations (gbd's) and associated cusps in the dependence of the boundary energy on misorientation is in this case well established. However, in previous computer simulations of these boundaries neither localised gbd's nor distinct energy cusps have been identified. The principal aim of the present study is to clarify this discrepancy between observations and computer modelling. For this purpose the structure and energy of a number of long period (high ..sigma..) twist boundaries with misorientations very close to ..sigma.. = 5 have been calculated using empirical pair and n-body potentials to describe interatomic forces. Furthermore, an isolated gbd embedded into a ..sigma.. = 5 boundary has been modelled. Well defined cusps at ..sigma.. = 5 misorientation and localised gbd's have been found but the reference ..sigma.. = 5 structure is always the lowest energy structure which, in general, does not possess the symmetry of the coincidence site lattice. The misorientation dependence of the boundary energy is then discussed using a Read-Shockley type model. The cusps are always very shallow and may have an uncoventional shape which is related to the dependence of the elastic energy on misorientation that is not the same for twist and tilt boundaries, contrary to what is usually assumed. Finally, some remaining discrepancies between observed types of gbd's and those found in the present study are discussed in the light of the previously proposed multiplicities of boundary structures.

  12. The VOT Category Boundary in Word-Initial Stops: Counter-Evidence Against Rate Normalization in English Spontaneous Speech

    Directory of Open Access Journals (Sweden)

    Satsuki Nakai

    2016-10-01

    Full Text Available Some languages, such as many varieties of English, use short-lag and long-lag VOT to distinguish word- and syllable-initial voiced vs. voiceless stop phonemes. According to a popular view, the optimal VOT category boundary between the two types of stops moves towards larger values as articulation rate becomes slower (and speech segments longer, and listeners accordingly shift the perceptual VOT category boundary. According to an alternative view, listeners do not shift the VOT category boundary with a change in articulation rate, because the same category boundary remains optimal acrossdifferent rates of articulation in normal speech, although a shift in the optimal boundary location can be induced in the laboratory by instructing speakers to use artificially extreme articulation rates. In this study we compared the effectiveness of rate-independent VOT category boundaries applied to word-initial stop phonemes in spontaneous English speech, against the effectiveness of Miller et al.’s (1986 rate-dependent VOT category boundary applied to laboratory speech. The effectiveness of the two types of category boundaries were comparable, when spontaneous speech data were controlled for factors other than articulation rate. Our results suggest that perceptual VOT category boundaries need not shift with a change in articulation rate under normal circumstances.

  13. The FSP Boundary Science Driver Plan

    Energy Technology Data Exchange (ETDEWEB)

    Rognlien, T. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Whyte, D. G. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Brooks, J. N. [Purdue Univ., West Lafayette, IN (United States); Canik, J. M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Greenwald, M. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Stotler, D. P. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Tang, X. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tautges, T. J. [Argonne National Lab. (ANL), Argonne, IL (United States); Wirth, B. D. [Univ. of Tennessee, Knoxville, TN (United States)

    2011-02-18

    This report describes the boundary region in a fusion device. This includes a narrow region where plasma parameters change very rapidly and the near surface of adjoining materials know as plasma-facing components.

  14. Antietam National Battlefield Tract and Boundary Data

    Data.gov (United States)

    National Park Service, Department of the Interior — These ESRI shape files are of National Park Service tract and boundary data that was created by the Land Resources Division. Tracts are numbered and created by the...

  15. International Boundary United States Mexico Minute 315

    Data.gov (United States)

    International Boundary & Water Commission — This dataset was created to provide resource managers, public officials, researchers, and the general public with ready access to the location of the international...

  16. Mojave National Preserve Tract and Boundary Data

    Data.gov (United States)

    National Park Service, Department of the Interior — These ESRI shape files are of National Park Service tract and boundary data that was created by the Land Resources Division. Tracts are numbered and created by the...

  17. Buffalo National River Tract and Boundary Data

    Data.gov (United States)

    National Park Service, Department of the Interior — These ESRI shape files are of National Park Service tract and boundary data that was created by the Land Resources Division. Tracts are numbered and created by the...

  18. Catoctin Mountain Park Tract and Boundary Data

    Data.gov (United States)

    National Park Service, Department of the Interior — These ESRI shape files are of National Park Service tract and boundary data that was created by the Land Resources Division. Tracts are numbered and created by the...

  19. Spanning organizational boundaries to manage creative processes:

    DEFF Research Database (Denmark)

    Andersen, Poul Houman; Kragh, Hanne; Lettl, Christopher

    2013-01-01

    In order to continue to be innovative in the current fast-paced and competitive environment, organizations are increasingly dependent on creative inputs developed outside their boundaries. The paper addresses the boundary spanning activities that managers undertake to a) select and mobilize...... creative talent, b) create shared identity, and c) combine and integrate knowledge in innovation projects involving external actors. We study boundary spanning activities in two creative projects in the LEGO group. One involves identifying and integrating deep, specialized knowledge, the other focuses...... on the use of external actors as a source of broad, not necessarily fully developed ideas. We find that the boundary spanning activities in these two projects differ in respect, among other things, of how the firm selects participants, formulates problems, and aligns the expectations of internal and external...

  20. State Wildlife Management Area Boundaries - Publicly Accessible

    Data.gov (United States)

    Minnesota Department of Natural Resources — This polygon theme contains boundaries for approximately 1392 Wildlife Management Areas (WMAs) across the state covering nearly 1,288,000 acres. WMAs are part of the...

  1. Pinnacles National Monument Tract and Boundary Data

    Data.gov (United States)

    National Park Service, Department of the Interior — These ESRI shape files are of National Park Service tract and boundary data that was created by the Land Resources Division. Tracts are numbered and created by the...

  2. Bridging Boundaries in Networked Military Organizations

    NARCIS (Netherlands)

    Kleij, R. van der; Broek, J. van den; Cornelissen, M.; Essens, P.J.D.M.

    2010-01-01

    One of the challenges facing networked military organizations is to coordinate and integrate activities of organization components. Several studies have demonstrated the importance of boundary spanning as integrative mechanism, and, more specifically, individual communication holes within

  3. Cordell Bank National Marine Sanctuary Boundary (polygon)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Office of National Marine Sanctuaries manages a system of sanctuaries and other managed areas around the country. The legal boundaries of These sanctuaries are...

  4. Florida Keys National Marine Sanctuary Boundary (polygon)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Office of National Marine Sanctuaries manages a system of sanctuaries and other managed areas around the country. The legal boundaries of These sanctuaries are...

  5. Monterey Bay National Marine Sanctuary Boundary (polygon)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Office of National Marine Sanctuaries manages a system of sanctuaries and other managed areas around the country. The legal boundaries of These sanctuaries are...

  6. Grays Reef National Marine Sanctuary Boundary (polygon)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Office of National Marine Sanctuaries manages a system of sanctuaries and othermanaged areas around the country. The legal boundaries of These sanctuaries are...

  7. Noatak National Preserve Tract and Boundary Data

    Data.gov (United States)

    National Park Service, Department of the Interior — These ESRI shape files are of National Park Service tract and boundary data that were created by the Land Resources Division. Tracts are numbered and created by the...

  8. Vietnam Vetrans Memorial Tract and Boundary Data

    Data.gov (United States)

    National Park Service, Department of the Interior — These ESRI shape files are of National Park Service tract and boundary data that was created by the Land Resources Division. Tracts are numbered and created by the...

  9. Public Land Survey Township Boundaries of Iowa

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This coverage contains polygons representing the PLSS township boundaries of the state of Iowa. TOWNSHIP was developed from a set of 99 individual county coverages...

  10. Superfund National Priority List (NPL) Site Boundaries

    Data.gov (United States)

    U.S. Environmental Protection Agency — A set of site boundaries for each site in EPA Region 1 (Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont) on EPA's Superfund National...

  11. Continental Shelf Boundary - Alaska NAD83

    Data.gov (United States)

    Bureau of Ocean Energy Management, Department of the Interior — This data set contains Continental Shelf Boundaries (CSB) lines in ESRI shapefile format for the BOEM Alaska Region. The CSB defines the seaward limit of federally...

  12. EnviroAtlas Community Boundaries Web Service

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset shows the boundaries of all EnviroAtlas Communities. It represents the outside edge of all the block groups included in each EnviroAtlas...

  13. Universal Quantum Computation with Gapped Boundaries

    Science.gov (United States)

    Cong, Iris; Cheng, Meng; Wang, Zhenghan

    2017-10-01

    This Letter discusses topological quantum computation with gapped boundaries of two-dimensional topological phases. Systematic methods are presented to encode quantum information topologically using gapped boundaries, and to perform topologically protected operations on this encoding. In particular, we introduce a new and general computational primitive of topological charge measurement and present a symmetry-protected implementation of this primitive. Throughout the Letter, a concrete physical example, the Z3 toric code [D (Z3)], is discussed. For this example, we have a qutrit encoding and an abstract universal gate set. Physically, gapped boundaries of D (Z3) can be realized in bilayer fractional quantum Hall 1 /3 systems. If a practical implementation is found for the required topological charge measurement, these boundaries will give rise to a direct physical realization of a universal quantum computer based on a purely Abelian topological phase.

  14. Atlantic NAD 83 Continental Shelf Boundary (CSB)

    Data.gov (United States)

    Bureau of Ocean Energy Management, Department of the Interior — This data set contains Continental Shelf Boundary (CSB) lines in ESRI shapefile format for the BOEM Atlantic Region. The CSB defines the seaward limit of federally...

  15. Coronado National Memorial Tract and Boundary Data

    Data.gov (United States)

    National Park Service, Department of the Interior — These ESRI shape files are of National Park Service tract and boundary data that was created by the Land Resources Division. Tracts are numbered and created by the...

  16. Badlands National Park Tract and Boundary Data

    Data.gov (United States)

    National Park Service, Department of the Interior — These ESRI shape files are of National Park Service tract and boundary data that was created by the Land Resources Division. Tracts are numbered and created by the...

  17. Channel Islands National Marine Sanctuary Boundary (polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Office of National Marine Sanctuaries manages a system of sanctuaries and other managed areas around the country. The legal boundaries of these sanctuaries are...

  18. Optimum switching boundaries for space vehicle control.

    Science.gov (United States)

    Brock, H. I.; Thompson, Z.

    1972-01-01

    Description of a new scheme using parabolic switching boundaries as opposed to the current method of linear switching to improve the fuel consumption of manned orbital space vehicles. Fuel consumption during error recovery and limit cycle phases are both considered.

  19. Adminstrative Boundary for Glacier National Park, Montana

    Data.gov (United States)

    National Park Service, Department of the Interior — The current administrative boundary of Glacier National Park, Montana. This data is based on 1:24000 scale USGS quad mapping published in 1968, but was revised in...

  20. US Fish and Wildlife Service Regional Boundaries

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Boundaries of the management Regions of the U.S. Fish and Wildlife Service. The U.S. Fish and Wildlife Service is organized into 8 geographic Regions.

  1. National Marine Sanctuary Digital Boundary Files

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Office of National Marine Sanctuaries manages a system of sanctuaries and other managed areas around the country. The legal boundaries of these sanctuaries are...

  2. Pressure and ion composition boundaries at Mars

    National Research Council Canada - National Science Library

    Xu, Shaosui; Liemohn, Michael W; Dong, Chuanfei; Mitchell, David L; Bougher, Stephen W; Ma, Yingjuan

    2016-01-01

    This study analyzes results from a multifluid MHD simulation to investigate the shape and structure of the pressure and composition boundaries at Mars, which can provide physical insight for the observational analysis...

  3. Boundary Controllability of Nonlinear Fractional Integrodifferential Systems

    Directory of Open Access Journals (Sweden)

    Ahmed HamdyM

    2010-01-01

    Full Text Available Sufficient conditions for boundary controllability of nonlinear fractional integrodifferential systems in Banach space are established. The results are obtained by using fixed point theorems. We also give an application for integropartial differential equations of fractional order.

  4. Volume dependence of computed grain boundary energy

    Energy Technology Data Exchange (ETDEWEB)

    Bristowe, P.D.; Brokman, A.

    1980-08-01

    Over the past five years there have been numerous studies of grain boundary structure using the method of computer molecular statics which assume pairwise central potentials for the interatomic interaction. Emphasis is usually placed on relative grain boundary energies but these may be inaccurate due to various, but related, approximations and constraints implicity imposed on the calculation-namely central forces, finite model size, fixed border conditions and volume dependent contributions to the energy of the system. It is the purpose of this work to clarify how these particular properties of the model can affect the computed grain boundary energy and demonstrate instances in which the quoted energy has strictly been inaccurate. The implication of these results, especially on how they affect the method of relaxation and the resulting grain boundary structure is discussed.

  5. International boundary experiences by the United Nations

    Science.gov (United States)

    Kagawa, A.

    2013-12-01

    Over the last few decades, the United Nations (UN) has been approached by Security Council and Member States on international boundary issues. The United Nations regards the adequate delimitation and demarcation of international boundaries as a very important element for the maintenance of peace and security in fragile post-conflict situations, establishment of friendly relationships and cross-border cooperation between States. This paper will present the main principles and framework the United Nations applies to support the process of international boundary delimitation and demarcation activities. The United Nations is involved in international boundary issues following the principle of impartiality and neutrality and its role as mediator. Since international boundary issues are multi-faceted, a range of expertise is required and the United Nations Secretariat is in a good position to provide diverse expertise within the multiple departments. Expertise in different departments ranging from legal, political, technical, administrative and logistical are mobilised in different ways to provide support to Member States depending on their specific needs. This presentation aims to highlight some of the international boundary projects that the United Nations Cartographic Section has been involved in order to provide the technical support to different boundary requirements as each international boundary issue requires specific focus and attention whether it be in preparation, delimitation, demarcation or management. Increasingly, the United Nations is leveraging geospatial technology to facilitate boundary delimitation and demarcation process between Member States. Through the presentation of the various case studies ranging from Iraq - Kuwait, Israel - Lebanon (Blue Line), Eritrea - Ethiopia, Cyprus (Green Line), Cameroon - Nigeria, Sudan - South Sudan, it will illustrate how geospatial technology is increasingly used to carry out the support. In having applied a range

  6. DNR Division of Parks and Trails District Boundaries

    Data.gov (United States)

    Minnesota Department of Natural Resources — This data shows the DNR Division of Parks and Trails District Boundaries as of May 2010. The boundaries were created by the Division Leadership Team. Boundaries are...

  7. Sierra Nevada Subregional Boundary - Sierra Nevada Conservancy [ds542

    Data.gov (United States)

    California Department of Resources — Sierra Nevada Conservancy (SNC) boundary. The boundary was mapped to correspond with statute AB 2600 (2004) and as re-defined in AB 1201 (2005). Work on the boundary...

  8. Local boundary migration during recrystallization in pure aluminium

    DEFF Research Database (Denmark)

    Zhang, Yubin; Godfrey, Andrew; Juul Jensen, Dorte

    2011-01-01

    Boundary migration during recrystallization has been followed by an ex situ electron channelling contrast technique, and protrusions/retrusions formed locally on recrystallization boundaries have been quantified. The results show that the motion of recrystallization boundaries is much more comple...

  9. Slip patterns and preferred dislocation boundary planes

    DEFF Research Database (Denmark)

    Winther, G.

    2003-01-01

    The planes of deformation induced extended planar dislocation boundaries are analysed in two different co-ordinate systems, namely the macroscopic system defined by the deformation axes and the crystallographic system given by the crystallographic lattice. The analysis covers single and polycryst......The planes of deformation induced extended planar dislocation boundaries are analysed in two different co-ordinate systems, namely the macroscopic system defined by the deformation axes and the crystallographic system given by the crystallographic lattice. The analysis covers single...

  10. Reconsideration of the planetary boundary for phosphorus

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, Stephen R [Center for Limnology, University of Wisconsin, Madison, WI 53706 (United States); Bennett, Elena M, E-mail: srcarpen@wisc.edu, E-mail: Elena.Bennett@mcgill.ca [Department of Natural Resource Sciences and McGill School of Environment, McGill University, 21 111 Lakeshore Road, Ste-Anne de Bellevue, QC, H9X 3V9 (Canada)

    2011-01-15

    Phosphorus (P) is a critical factor for food production, yet surface freshwaters and some coastal waters are highly sensitive to eutrophication by excess P. A planetary boundary, or upper tolerable limit, for P discharge to the oceans is thought to be ten times the pre-industrial rate, or more than three times the current rate. However this boundary does not take account of freshwater eutrophication. We analyzed the global P cycle to estimate planetary boundaries for freshwater eutrophication. Planetary boundaries were computed for the input of P to freshwaters, the input of P to terrestrial soil, and the mass of P in soil. Each boundary was computed for two water quality targets, 24 mg P m{sup -3}, a typical target for lakes and reservoirs, and 160 mg m{sup -3}, the approximate pre-industrial P concentration in the world's rivers. Planetary boundaries were also computed using three published estimates of current P flow to the sea. Current conditions exceed all planetary boundaries for P. Substantial differences between current conditions and planetary boundaries demonstrate the contrast between large amounts of P needed for food production and the high sensitivity of freshwaters to pollution by P runoff. At the same time, some regions of the world are P-deficient, and there are some indications that a global P shortage is possible in coming decades. More efficient recycling and retention of P within agricultural ecosystems could maintain or increase food production while reducing P pollution and improving water quality. Spatial heterogeneity in the global P cycle suggests that recycling of P in regions of excess and transfer of P to regions of deficiency could mitigate eutrophication, increase agricultural yield, and delay or avoid global P shortage.

  11. Boundary Correct Real-Time Soft Shadows

    DEFF Research Database (Denmark)

    Jacobsen, Bjarke; Christensen, Niels Jørgen; Larsen, Bent Dalgaard

    2004-01-01

    This paper describes a method to determine correct shadow boundaries from an area light source using umbra and penumbra volumes. The light source is approximated by a circular disk as this gives a fast way to extrude the volumes. The method also gives a crude estimate of the visibility of the area...... for implementation on most programmable hardware. Though some crude approximations are used in the visibility function, the method can be used to produce soft shadows with correct boundaries in real time....

  12. Free boundary ballooning mode representation and its application

    Science.gov (United States)

    Zheng, Linjin

    2012-10-01

    Free boundary ballooning mode representation is developed in this paper. This representation allows the two dimensional problem of peeling ballooning modes to be treated in one dimensional formalism. In contrast to the conventional ballooning representation, which requires the translational invariance of the Fourier components of the perturbations, the new invariance reflects that the independent solutions of the high n mode equations are translationally invariant from one radial interval surrounding a single singular surface to the other intervals. The conventional ballooning mode invariance breaks down at the vicinity of plasma edge, since the Fourier components with rational surfaces in vacuum region are completely different from those with rational surfaces in plasma region. But, the new type of invariance remains valid. This overcomes the limitation of the conventional ballooning mode representation for studying free boundary modes. Since the current formalism is adaptable to the cases with various sharp boundary changes, it therefore can be also generalized to study the piece-wise equilibrium cases, for example, the H-mode pedestal and X-point physics.

  13. Nondestructive optical visualisation of graphene domains and boundaries.

    Science.gov (United States)

    Wu, Xingyi; Zhong, Guofang; Robertson, John

    2016-09-15

    The domain boundaries of polycrystalline graphene produced by chemical vapor deposition (CVD) adversely influence the graphene transporting properties. The existing domain visualisation methods for large area graphene always cause detrimental damage or contamination. Here we report a nondestructive method for spatial visualisation of the domains and boundaries of large area continuous graphene grown on Cu foils (Gr/Cu) by CVD. Using a rationally modified optical microscope, we can directly observe novel star-like bright line sets of Gr/Cu in an enhanced dark field mode. Each set of the bright lines is identified as the ridges of one Cu surface pyramid which arises beneath one enlarging graphene domain due to slower evaporation of graphene-covered Cu than that of graphene-free Cu. This one to one correspondence thereby enables nondestructive visualisation. This method offers an advantageous pathway for monitoring the spatial distribution of the graphene domains and boundaries. We have further discovered for the first time various types of star-like ridge structures which are governed by the underlying Cu crystallographic orientations. This gives rise to a new phenomenon for research on the complex 2D material-metal interfacing.

  14. High resolution electron microscopy studies of twin boundary structures in B19{prime} martensite in the Ti-Ni shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Nishida, M.; Itai, I.; Ohgi, H.; Chiba, A. [Kumamoto Univ. (Japan). Dept. of Materials Science and Resource Engineering; Yamauchi, K. [Tokin Corp., Sendai (Japan). Materials Science and Development Lab.

    1995-03-01

    The boundary structure of the <011> Type II, {l_brace}11{bar 1}{r_brace} Type I, {l_brace}011{r_brace} Type I, (100) compound and (001) compound twins in the B19{prime} martensite in the Ti-Ni shape memory alloy was observed in the edge-on state by high resolution electron microscopy (HREM). The lattice images of the Type I and the compound twins exhibit the well-defined crystallographic features of those boundaries. Lattice image of the <011> Type II twin taken from the unique {eta}{sub 1} axis suggests that neither ledge nor step structures are present at the irrational boundary.

  15. Understanding the Effect of Grain Boundary Character on Dynamic Recrystallization in Stainless Steel 316L

    Science.gov (United States)

    Beck, Megan; Morse, Michael; Corolewski, Caleb; Fritchman, Koyuki; Stifter, Chris; Poole, Callum; Hurley, Michael; Frary, Megan

    2017-08-01

    Dynamic recrystallization (DRX) occurs during high-temperature deformation in metals and alloys with low to medium stacking fault energies. Previous simulations and experimental research have shown the effect of temperature and grain size on DRX behavior, but not the effect of the grain boundary character distribution. To investigate the effects of the distribution of grain boundary types, experimental testing was performed on stainless steel 316L specimens with different initial special boundary fractions (SBF). This work was completed in conjunction with computer simulations that used a modified Monte Carlo method which allowed for the addition of anisotropic grain boundary energies using orientation data from electron backscatter diffraction (EBSD). The correlation of the experimental and simulation work allows for a better understanding of how the input parameters in the simulations correspond to what occurs experimentally. Results from both simulations and experiments showed that a higher fraction of so-called "special" boundaries ( e.g., Σ3 twin boundaries) delayed the onset of recrystallization to larger strains and that it is energetically favorable for nuclei to form on triple junctions without these so-called "special" boundaries.

  16. On the detection of expansion at large angle grain boundaries using electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Balluffi, R.W.; Bristowe, P.D.

    1984-06-01

    A model of the type shown by Brokman and Balluffi in this article, should hold for grain boundary reflections from twist boundaries occurring at positions in reciprocal space on elements of the ''boundary diffraction lattice'' (BDL) which do not contain lattice reflections. In such cases, the intensities scattered by the boundary region and the two unperturbed lattices can be separated to a good approximation, and the scattering from the boundary region can be considered independently. However, in the present case, where the intensity from the grain boundary region, considered separately, would appear close to lattice reflections on the same element of the BDL, it is not clear that this is the case. It may be necessary to perform a more complicated analysis taking account of the total scattering from the grain boundary region and the two adjoining lattices. The purpose of this article is to present such an analysis. The results show that the more complicated analysis is required and a more realistic explanation of the observed result is discussed.

  17. Large eddy simulation of atmospheric boundary layer over wind farms using a prescribed boundary layer approach

    Science.gov (United States)

    Sarlak, H.; Sørensen, J. N.; Mikkelsen, R.

    2012-09-01

    Large eddy simulation (LES) of flow in a wind farm is studied in neutral as well as thermally stratified atmospheric boundary layer (ABL). An approach has been practiced to simulate the flow in a fully developed wind farm boundary layer. The approach is based on the Immersed Boundary Method (IBM) and involves implementation of an arbitrary prescribed initial boundary layer (See [1]). A prescribed initial boundary layer profile is enforced through the computational domain using body forces to maintain a desired flow field. The body forces are then stored and applied on the domain through the simulation and the boundary layer shape will be modified due to the interaction of the turbine wakes and buoyancy contributions. The implemented method is capable of capturing the most important features of wakes of wind farms [1] while having the advantage of resolving the wall layer with a coarser grid than typically required for such problems.

  18. The relationship between grain boundary structure, defect mobility, and grain boundary sink efficiency

    Science.gov (United States)

    Uberuaga, Blas Pedro; Vernon, Louis J.; Martinez, Enrique; Voter, Arthur F.

    2015-01-01

    Nanocrystalline materials have received great attention due to their potential for improved functionality and have been proposed for extreme environments where the interfaces are expected to promote radiation tolerance. However, the precise role of the interfaces in modifying defect behavior is unclear. Using long-time simulations methods, we determine the mobility of defects and defect clusters at grain boundaries in Cu. We find that mobilities vary significantly with boundary structure and cluster size, with larger clusters exhibiting reduced mobility, and that interface sink efficiency depends on the kinetics of defects within the interface via the in-boundary annihilation rate of defects. Thus, sink efficiency is a strong function of defect mobility, which depends on boundary structure, a property that evolves with time. Further, defect mobility at boundaries can be slower than in the bulk, which has general implications for the properties of polycrystalline materials. Finally, we correlate defect energetics with the volumes of atomic sites at the boundary. PMID:25766999

  19. Large eddy simulation of atmospheric boundary layer over wind farms using a prescribed boundary layer approach

    DEFF Research Database (Denmark)

    Chivaee, Hamid Sarlak; Sørensen, Jens Nørkær; Mikkelsen, Robert Flemming

    2012-01-01

    Large eddy simulation (LES) of flow in a wind farm is studied in neutral as well as thermally stratified atmospheric boundary layer (ABL). An approach has been practiced to simulate the flow in a fully developed wind farm boundary layer. The approach is based on the Immersed Boundary Method (IBM......) and involves implementation of an arbitrary prescribed initial boundary layer (See [1]). A prescribed initial boundary layer profile is enforced through the computational domain using body forces to maintain a desired flow field. The body forces are then stored and applied on the domain through the simulation...... and the boundary layer shape will be modified due to the interaction of the turbine wakes and buoyancy contributions. The implemented method is capable of capturing the most important features of wakes of wind farms [1] while having the advantage of resolving the wall layer with a coarser grid than typically...

  20. Approximation of full-boundary data from partial-boundary electrode measurements

    Science.gov (United States)

    Hauptmann, Andreas

    2017-12-01

    Measurements on a subset of the boundary are common in electrical impedance tomography, especially because any electrode model can be interpreted as a partial-boundary problem. The information obtained is different to full-boundary measurements as modelled by the ideal continuum model. In this study we discuss an approach to approximate full-boundary data from partial-boundary measurements that is based on the knowledge of the involved projections. The approximate full-boundary data can then be obtained as the solution to a suitable optimization problem on the coefficients of the Neumann-to-Dirichlet map. By this procedure we are able to improve the reconstruction quality of continuum model-based algorithms, in particular we present the effectiveness with a D-bar method. Reconstructions are presented for noisy simulated and real measurement data.

  1. On the structural unit/grain boundary dislocation model for grain boundary structure

    Science.gov (United States)

    Balluffi, R. W.; Bristowe, P. D.

    1984-08-01

    The applicability of the structural unit/grain boundary dislocation (GBD) model to the atomistic structures of [001] and [011] tilt boundary series recently calculated by Sutton, Vitek and Wang is studied in detail. It is found that a hierarchy of structural unit/GBD descriptions exists which may be used to describe such boundaries. Each description corresponds to a different choice of "delimiting boundary" structural units which are mixed together to make up all boundaries in the series. In all cases the structural units exhibit systematic distortions as the tilt angle changes. As the number of delimiting boundaries in a series is increased, and the range of structures is "quantized" on a finer scale, the distortions of the structural units decreases, but the amount of information regarding the GBD structure is decreased. It is pointed out that different members of the hierarchy of descriptions can be used advantageously for different purposes.

  2. Mechanically induced grain boundary motion in Al-bicrystals

    Energy Technology Data Exchange (ETDEWEB)

    Gorkaya, Tatiana; Molodov, Dmitri A.; Gottstein, Guenter [Institut fuer Metallkunde und Metallphysik der RWTH Aachen (Germany)

    2010-07-01

    The mechanically induced migration of planar grain boundaries in Al-bicrystals was experimentally measured. The novel tensile/compression module for scanning electron microscope was utilized for in-situ measurements of grain boundary motion at elevated temperatures. From the measured temperature dependence of boundary mobility the migration activation parameters for investigated boundaries were determined. Normal boundary motion was observed to be coupled to a shear of the crystal in the region traversed by the grain boundary during its motion. The measured ratios of the normal grain boundary motion to the lateral translation of grains were compared with geometrical models of stress induced boundary migration.

  3. Periodic boundary value problems of second order random differential equations

    Directory of Open Access Journals (Sweden)

    Bapurao Dhage

    2009-04-01

    Full Text Available In this paper, an existence and the existence of extremal random solutions are proved for a periodic boundary value problem of second order ordinary random differential equations. Our investigations have been placed in the space of real-valued functions defined and continuous on closed and bounded intervals of real line together with the applications of the random version of a nonlinear alternative of Leray-Schauder type and an algebraic random fixed point theorem of Dhage. An example is also indicated for demonstrating the realizations of the abstract theory developed in this paper.

  4. Grain Boundary Phase Transformations in Nanostructured Conducting Oxides

    Science.gov (United States)

    Straumal, B. B.; Myatiev, A. A.; Straumal, P. B.; Mazilkin, A. A.

    Nanostructured conducting oxides are very promising for various applications like varistors (doped zinc oxide), electrolytes for the solid oxide fuel cells (SOFC) (ceria, zirconia, yttria), semipermeable membranes, and sensors (perovskite-type oxides). Grain boundary (GB) phases crucially determine the properties of nanograined oxides. GB phase transformations (wetting, prewetting, pseudopartial wetting) proceed in the conducting oxides. Novel GB lines appear in the conventional bulk phase diagrams. They can be used for the tailoring of properties of nanograined conducting oxides, particularly by using the novel synthesis method of liquid ceramics.

  5. Dislocation-Pairing Transitions in Hot Grain Boundaries

    Science.gov (United States)

    Olmsted, David L.; Buta, Dorel; Adland, Ari; Foiles, Stephen M.; Asta, Mark; Karma, Alain

    2011-01-01

    We report the finding of a novel grain-boundary structural phase transition in both molecular-dynamics and phase-field-crystal simulations of classical models of bcc Fe. This transition is characterized by pairing of individual dislocations with mixed screw and edge components. We demonstrate that this type of transition is driven by a combination of factors including elastic softening, core interaction, and core disordering. At high homologous temperatures the occurrence of this transition is shown to prevent premelting at misorientation angles where it would otherwise be expected.

  6. Faceting of twin grain boundaries in polysilicon films

    Energy Technology Data Exchange (ETDEWEB)

    Nakhodkin, Nikolay; Rodionova, Tatyana [Department of Radiophysics, Kiev National Taras Shevchenko University (Ukraine); Kulish, Nikolay [Department of Physics, Kiev National Taras Shevchenko University (Ukraine)

    2010-02-15

    The faceting of grain boundaries (GB) under annealing in phosphorus-doped polysilicon films, produced by low-pressure chemical vapor deposition, has been investigated by transmission electron microscopy. It has been shown that the facet types and facet density depend on annealing temperature. It has been found that GB facets are generally parallel with close-packed planes in coincidence site lattice. A correlation between GB faceting and grain-growth mechanisms has been considered. It has been shown that faceting takes place both under normal and abnormal grain growth. It is revealed that twinning plays the key role for GB faceting under normal grain growth. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  7. Boundary controllability of Maxwell's equations in a spherical region

    Science.gov (United States)

    Kime, Katherine A.

    1987-02-01

    This paper examines the question of control of electromagnetic fields in a three dimensional spherical region by means of control currents on the boundary of that region. Results of this type are significant in connection with the theory of waveguides, electromagnetic pulse devices, and stealth technology, as well as being of independent mathematical interest. The necessary theory of divergence-free solutions of the vector wave equation is developed. By use of eigenfunctions of the vector Laplacian in appropriate divergence-free domains and moment problem techniques, sufficient conditions for controllability are set forth.

  8. Approximate solution for an inverse problem of multidimensional elliptic equation with multipoint nonlocal and Neumann boundary conditions

    OpenAIRE

    Charyyar Ashyralyyev; Gulzipa Akyuz; Mutlu Dedeturk

    2017-01-01

    In this work, we consider an inverse elliptic problem with Bitsadze-Samarskii type multipoint nonlocal and Neumann boundary conditions. We construct the first and second order of accuracy difference schemes (ADSs) for problem considered. We stablish stability and coercive stability estimates for solutions of these difference schemes. Also, we give numerical results for overdetermined elliptic problem with multipoint Bitsadze-Samarskii type nonlocal and Neumann boundary...

  9. Structure of Grain Boundaries and Aspects of Deformation Behavior in Nickel-Aluminum Alloys.

    Science.gov (United States)

    Kerans, Ronald James

    The structures of two grain boundaries in Ni _3Al were determined using transmission electron microscopy (TEM). The line directions and spacings of secondary grain boundary dislocations (gbds) were calculated for coincidence site lattice (CSL) relationships near the experimentally determined misorientations. The structures of the boundaries were found to be in good agreement with Sigma 9 and Sigma 31b relationships of the ordered lattice. The grain boundary dislocations were found to be characteristic of the ordered structure. No grouping of partial gbds was observed. Lattice dislocations consisting of pairs of 1/3 (112) superpartials bounding extended superlattice intrinsic stacking faults (SISFs) were observed by TEM. They were found to independently react to APB coupled 1/2 (110) pairs in the commonly observed pure screw orientation. Implications with regard to Kear-Wilsdorf type locking mechanisms and deformation behavior are discussed. Boron was observed to have strong effects upon the population of boundary types, grain size, and grain growth. In addition, small amounts of B completely eliminate widely extended stacking faults. It is concluded that effects of B other than influencing boundary cohesion are important.

  10. Pressure Fluctuations Induced by a Hypersonic Turbulent Boundary Layer

    Science.gov (United States)

    Duan, Lian; Choudhari, Meelan M.; Zhang, Chao

    2016-01-01

    Direct numerical simulations (DNS) are used to examine the pressure fluctuations generated by a spatially-developed Mach 5.86 turbulent boundary layer. The unsteady pressure field is analyzed at multiple wall-normal locations, including those at the wall, within the boundary layer (including inner layer, the log layer, and the outer layer), and in the free stream. The statistical and structural variations of pressure fluctuations as a function of wall-normal distance are highlighted. Computational predictions for mean velocity pro les and surface pressure spectrum are in good agreement with experimental measurements, providing a first ever comparison of this type at hypersonic Mach numbers. The simulation shows that the dominant frequency of boundary-layer-induced pressure fluctuations shifts to lower frequencies as the location of interest moves away from the wall. The pressure wave propagates with a speed nearly equal to the local mean velocity within the boundary layer (except in the immediate vicinity of the wall) while the propagation speed deviates from the Taylor's hypothesis in the free stream. Compared with the surface pressure fluctuations, which are primarily vortical, the acoustic pressure fluctuations in the free stream exhibit a significantly lower dominant frequency, a greater spatial extent, and a smaller bulk propagation speed. The freestream pressure structures are found to have similar Lagrangian time and spatial scales as the acoustic sources near the wall. As the Mach number increases, the freestream acoustic fluctuations exhibit increased radiation intensity, enhanced energy content at high frequencies, shallower orientation of wave fronts with respect to the flow direction, and larger propagation velocity.

  11. Microstructure evolution in a 2618 aluminium alloy during creep-fatigue tests

    Energy Technology Data Exchange (ETDEWEB)

    Novy, Frantisek; Hadzima, Branislav [Zilina Univ. (Slovakia). Dept. of Materials Engineering; Janecek, Milos; Kral, Robert [Charles Univ., Prague (Czech Republic). Dept. of Physics of Materials

    2012-06-15

    Microstructure changes in the 2 618 aluminium alloy during creep-fatigue tests were studied. These tests simulate the conditions of the application of this alloy in devices for the exhaustion of hot gasses generated during fire in closed or difficultly accessible areas. Creep-fatigue tests result in high dislocation density in subgrains and narrow subgrain boundaries, in contrast to creep tests reported in our previous work where large subgrains were observed with relatively wide subgrain boundaries and relatively low dislocation density in grains. Extensive precipitation occurred with denuded (precipitate-free) zones along grain boundaries. The coherent S-phase (Al{sub 2}CuMg) transformed into partially coherent needle-shaped S' precipitates. Superior stress amplitude caused reduced lifetime and wider denuded zones. A model of the formation of denuded zones along (sub)-grain boundaries was proposed. (orig.)

  12. Seismic Detectability of the Postperovskite Boundary (Invited)

    Science.gov (United States)

    Shim, S.; Catalli, K.; Prakapenka, V.

    2009-12-01

    The depth range where both perovskite (Pv) and postperovskite (PPv) phases exist (mixed phase region or boundary thickness) strongly influence the seismic detectability of the PPv boundary and convection in the D" layer. We measured the thickness of the postperovskite (PPv) boundary in (Mg0.91Fe0.09)SiO3, (Mg0.9Fe0.1)(Al0.1Si0.9)O3, and (Mg0.91Fe0.09)(Fe0.09Si0.91)O3 in the laser-heated diamond-anvil cell at in situ high pressure-temperature conditions up to 3000 K and 145 GPa. Both Fe2+ and Fe3++Al increase the PPv boundary thickness to 400~600±100 km which is substantially larger than the thickness of the D" discontinuity (<30 km) [Lay 2008], while Fe3+ alone does not increase the thickness. Calculations using our PPv boundary results and recent element partitioning studies show that the Fe2+ buffering effect of ferropericlase (Fp) may increase the PPv transition pressure and decrease the PPv boundary thickness in an Al-free system. However, the magnitude of the buffering effect is not sufficient to fit the PPv boundary thickness to the thickness of the D" discontinuity for pyrolite. Furthermore, Al increases the PPv boundary thickness, and the rapid temperature increase in the D" layer suppresses the nonlinearity in the PPv phase fraction profile and prevents the completion of the PPv transition in Earth's mantle. The PPv boundary will be particularly thick in regions with elevated Al content and/or low Mg/Si ratio (such as basaltic materials), reducing the effects of the large positive Clapeyron slope of the PPv boundary on the buoyancy of thermal anomalies and stabilizing the compositional heterogeneities at the lowermost mantle. If the PPv transition is the source of the D" discontinuity, regions with sharp discontinuities require distinct compositions, such as a higher Mg/Si ratio or low Al content.

  13. Can inequality be tamed through boundary work? A qualitative study of health promotion aimed at reducing health inequalities.

    Science.gov (United States)

    Pedersen, Pia Vivian; Hjelmar, Ulf; Høybye, Mette Terp; Rod, Morten Hulvej

    2017-07-01

    This paper examines the organisational dynamics that arise in health promotion aimed at reducing health inequalities. The paper draws on ethnographic fieldwork among public health officers in Danish municipalities and qualitative interviews from an evaluation of health promotion programmes targeting homeless and other marginalised citizens. Analytically, we focus on 'boundary work', i.e. the ways in which social and symbolic boundaries are established, maintained, transgressed and negotiated, both at the administrative level and among frontline professionals. The paper discusses three types of boundary work: (i) demarcating professional domains; (ii) setting the boundaries of the task itself; and (iii) managing administrative boundaries. The main argument is that the production, maintenance and transgression of these three types of boundaries constitute central and time-consuming aspects of the practices of public health professionals, and that boundary work constitutes an important element in professional practices seeking to 'tame a wicked problem', such as social inequalities in health. A cross-cutting feature of the three types of boundary work is the management of the divide between health and social issues, which the professionals seemingly seek to uphold and transgress at the same time. The paper thus contributes to ongoing discussions of intersectoral action to address health inequalities. Furthermore, it extends the scope and application of the concept of boundary work in the sociology of public health by suggesting that the focus in previous research on professional demarcation be broadened in order to capture other types of boundaries that shape, and are shaped by, professional practices. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. A numerical solution of a singular boundary value problem arising in boundary layer theory.

    Science.gov (United States)

    Hu, Jiancheng

    2016-01-01

    In this paper, a second-order nonlinear singular boundary value problem is presented, which is equivalent to the well-known Falkner-Skan equation. And the one-dimensional third-order boundary value problem on interval [Formula: see text] is equivalently transformed into a second-order boundary value problem on finite interval [Formula: see text]. The finite difference method is utilized to solve the singular boundary value problem, in which the amount of computational effort is significantly less than the other numerical methods. The numerical solutions obtained by the finite difference method are in agreement with those obtained by previous authors.

  15. Characteristic Boundary Conditions for Numerical Magnetohydrodynamic (MHD) Simulation of Solar and Laboratory Plasma Flows

    Science.gov (United States)

    Wu, S. T.; Wang, A. H.; Cassibry, J.

    2010-09-01

    We discuss the self-consistent time-dependent numerical boundary conditions for magnetohydrodynamic (MHD) simulation to study the solar and laboratory plasma dynamics. It is well known that these plasma flows cover from the sub-sonic and sub-Alfvénic to super-sonic and super-Alfvénic region. Mathematically, the set of governing differential equations is transited from elliptical to hyperbolic type. In order to assure self-consistency, characteristic boundary conditions need to be used because the information propagating according to these characteristics will affect the solutions inside the computational domain. To illustrate the importance of the characteristic boundary conditions, two examples are given; one for solar plasma which is to study the energy and magnetic flux from the sub-photosphere to the corona, and the other one concerns laboratory plasma flow for the investigation of sub-Alfvénic inlet boundary conditions of an MHD nozzle flow.

  16. Effects of microscopic boundary conditions on plastic deformations of small-sized single crystals

    DEFF Research Database (Denmark)

    Kuroda, Mitsutoshi; Tvergaard, Viggo

    2009-01-01

    for uniaxial plane strain compression of a single crystal block and for uniform pure bending of a single crystal foil. The compressed block has loading surfaces that are penetrable or impenetrable to dislocations. This allows for a study of the two types of higher-order boundaries available, and a significant......The finite deformation version of the higher-order gradient crystal plasticity model proposed by the authors is applied to solve plane strain boundary value problems, in order to obtain an understanding of the effect of the higher-order boundary conditions. Numerical solutions are carried out...... effect of higher-order boundary conditions on the overall deformation mode of the block is observed. The bent foil has free surfaces through which dislocations can go out of the material, and we observe a strong size-dependent mechanical response resulting from the surface condition assumed....

  17. An energy absorbing far-field boundary condition for the elastic wave equation

    Energy Technology Data Exchange (ETDEWEB)

    Petersson, N A; Sjogreen, B

    2008-07-15

    The authors present an energy absorbing non-reflecting boundary condition of Clayton-Engquist type for the elastic wave equation together with a discretization which is stable for any ratio of compressional to shear wave speed. They prove stability for a second order accurate finite-difference discretization of the elastic wave equation in three space dimensions together with a discretization of the proposed non-reflecting boundary condition. The stability proof is based on a discrete energy estimate and is valid for heterogeneous materials. The proof includes all six boundaries of the computational domain where special discretizations are needed at the edges and corners. The stability proof holds also when a free surface boundary condition is imposed on some sides of the computational domain.

  18. Effect of riblets on the streaky structures excited by free stream tip vortices in boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Boiko, Andrey V. [Siberian Branch of the Russian Academy of Science, Novosibirsk (Russian Federation); Jung, Kwang Hyo; Chun, Ho Hwan; Lee, Inwon [Pusan National University, Busan (Korea, Republic of)

    2007-03-15

    In this study, experimental investigations were made regarding the effect of riblets on the streak instability in boundary layer. The streak instability is now regarded as a major source of the self-regeneration mechanism for the hairpin type coherent structures in turbulent boundary layer flow. Thus, it is important to control the instability to suppress the drag-inducing vortical structure in terms of drag reduction. Toward enhancing the measurement accuracy and spatial resolution, an enlarged version of riblets was applied to a streak which was artificially induced by a microwing in a laminar boundary layer. It is found that the riblets have attenuation effect on the streak instability, i.e., to reduce the spanwise velocity gradient of the quasi-streamwise streak in boundary layer.

  19. Effect of riblets on the streaky structures excited by free stream tip vortices in boundary layer

    Energy Technology Data Exchange (ETDEWEB)

    Boiko, Andrey V. [Siberian Branch of the Russian Academy of Science, Novosibirsk (Russian Federation); Jung, Kwang Hyo; Chun, Ho Hwan; Lee, In Won [Pusan National University, Busan (Korea, Republic of)

    2007-01-15

    In this study, experimental investigations were made regarding the effect of riblets on the streak instability in boundary layer. The streak instability is now regarded as a major source of the self-regeneration mechanism for the hairpin type coherent structures in turbulent boundary layer flow. Thus, it is important to control the instability to suppress the drag-inducing vortical structure in terms of drag reduction. Toward enhancing the measurement accuracy and spatial resolution, an enlarged version of riblets was applied to a streak which was artificially induced by a microwing in a laminar boundary layer. It is found that the riblets have attenuation effect on the streak instability, i.e., to reduce the spanwise velocity gradient of the quasi-streamwise streak in boundary layer

  20. Exact solution for the fractional cable equation with nonlocal boundary conditions

    Science.gov (United States)

    Bazhlekova, Emilia; Dimovski, Ivan

    2013-10-01

    The fractional cable equation is studied on a bounded space domain. One of the prescribed boundary conditions is of Dirichlet type, the other is of a general form, which includes the case of nonlocal boundary conditions. In real problems nonlocal boundary conditions are prescribed when the data on the boundary can not be measured directly. We apply spectral projection operators to convert the problem to a system of integral equations in any generalized eigenspace. In this way we prove uniqueness of the solution and give an algorithm for constructing the solution in the form of an expansion in terms of the generalized eigenfunctions and three-parameter Mittag-Leffler functions. Explicit representation of the solution is given for the case of double eigenvalues. We consider some examples and as a particular case we recover a recent result. The asymptotic behavior of the solution is also studied.