EBSD analysis of subgrain boundaries and dislocation slip systems in Antarctic and Greenland ice
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
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
Hamers, M. F.; Pennock, G. M.; Drury, M. R.
2017-04-01
The study of deformation features has been of great importance to determine deformation mechanisms in quartz. Relevant microstructures in both growth and deformation processes include dislocations, subgrains, subgrain boundaries, Brazil and Dauphiné twins and planar deformation features (PDFs). Dislocations and twin boundaries are most commonly imaged using a transmission electron microscope (TEM), because these cannot directly be observed using light microscopy, in contrast to PDFs. Here, we show that red-filtered cathodoluminescence imaging in a scanning electron microscope (SEM) is a useful method to visualise subgrain boundaries, Brazil and Dauphiné twin boundaries. Because standard petrographic thin sections can be studied in the SEM, the observed structures can be directly and easily correlated to light microscopy studies. In contrast to TEM preparation methods, SEM techniques are non-destructive to the area of interest on a petrographic thin section.
Flow stress, subgrain size, and subgrain stability at elevated temperature
International Nuclear Information System (INIS)
Sherby, O.D.; Klundt, R.H.; Miller, A.K.
1977-01-01
Well defined subgrain boundaries dominate the microstructural changes occurring during plastic flow of polycrystalline metals at elevated temperature. The quantitative influence of subgrain size on elevated-temperature plastic flow is considered. Based on the results of tests under constant-stress and constant-structure conditions, and equation is developed which predicts the creep rate as a function of subgrain size, stress, diffusion coefficient, and elastic modulus. In general, the subgrain size is a unique function of the current modulus-compensated flow stress, but if fine subgrains can be introduced and stabilized, large increases in creep strength may result. The applicability of the phenomenological relation developed to the behavior of dispersion-strengthened materials (where the second-phase particles may predetermine the effective subgrain size) is discussed. When subgrain effects are included, it is shown that the creep rate is less dependent on stacking fault energy than has been previously thought
Accurate electron channeling contrast analysis of a low angle sub-grain boundary
International Nuclear Information System (INIS)
Mansour, H.; Crimp, M.A.; Gey, N.; Maloufi, N.
2015-01-01
High resolution selected area channeling pattern (HR-SACP) assisted accurate electron channeling contrast imaging (A-ECCI) was used to unambiguously characterize the structure of a low angle grain boundary in an interstitial-free-steel. The boundary dislocations were characterized using TEM-style contrast analysis. The boundary was determined to be tilt in nature with a misorientation angle of 0.13° consistent with the HR-SACP measurements. The results were verified using high accuracy electron backscatter diffraction (EBSD), confirming the approach as a discriminating tool for assessing low angle boundaries
International Nuclear Information System (INIS)
Kassner, M.E.; Miller, A.K.; Sherby, O.D.
1982-01-01
Tests on 304 stainless steel were conducted involving first warm working in torsion, then cold working in torsion, and finally measurement of the elevated-temperature yield strength in compression. These tests permitted separation of the effects of subgrain size and forest dislocation density on the isotropic part of the flow stress. Forest dislocation strengthening appears to dominate in this material. Th results are best fitted by a root-mean-square summation of strength terms representing the contributions of solutes, forest dislocations, and subgrain boundaries. The same equation successfully predicts the flow stress during elevated-temperature transient deformation (under both constant strain rate and variable strain rate) from the transient dislocation substructure
Hydrogenation of GaAs covered by GaAlAs and subgrain boundary passivation
Djemel, A.; Castaing, J.; Chevallier, J.; Henoc, P.
1992-12-01
Cathodoluminescence (CL) has been performed to study the influence of hydrogen on electronic properties of GaAs with and without a GaAlAs layer. Recombination at sub-boundaries has been examined. These extended defects have been introduced by high temperature plastic deformation. The results show that they are passivated by hydrogen. The penetration of hydrogen is slowed down by the GaAlAs layer. La cathodoluminescence (CL) a été utilisée pour étudier l'influence de l'hydrogène sur les propriétés électroniques de GaAs nu et recouvert d'une couche de GaAlAs. Le caractère recombinant des sous-joints de grains a été examiné. Ces défauts étendus ont été introduits par déformation plastique à chaud. Les résultats montrent que l'hydrogène passive ces défauts. La pénétration de l'hydrogène à l'intérieur de GaAs est retardée par la présence de la couche de GaAlAs.
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
The evolution of disorientations for several types of boundaries
DEFF Research Database (Denmark)
Pantleon, W.
2001-01-01
During plastic deformation dislocation boundaries appear separating regions of different orientation. A model for the occurrence of disorientations across these boundaries is proposed and discussed with emphasis on several types of boundaries. For incidental dislocation boundaries a statistical...... 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...
Three Types of Earth's Inner Core Boundary
Tian, D.; Wen, L.
2017-12-01
The Earth's inner core boundary (ICB) is the site where the liquid outer core solidifies and the solid inner core grows. Thus, the fine-scale structure of the ICB is important for our understanding of the thermo-compositional state of the Earth's core. In this study, we collect a large set of seismic records with high-quality pre-critical PKiKP and PcP phase pairs, recorded by two dense seismic arrays, Hi-net in Japan and USArray in US. This dataset samples the ICB regions beneath East Asia, Mexico and the Bering Sea. We use differential travel times, amplitude ratios and waveform differences between PKiKP and PcP phases to constrain fine-scale structure of the ICB. The sampled ICB can be grouped into three types based on their seismic characteristics: (1) a simple ICB with a flat and sharp boundary, (2) a bumpy ICB with topographic height changes of 10 km, and (3) a localized mushy ICB with laterally varying thicknesses of 4-8 km. The laterally varying fine-scale structure of the ICB indicates existence of complex small-scale forces at the surface and a laterally varying solidification process of the inner core due to lateral variation of thermo-compositional condition near the ICB.
Twin boundary cavitation in aged type 304 stainless steel
International Nuclear Information System (INIS)
Sikka, V.K.; Swindeman, R.W.; Brinkman, C.R.
1975-10-01
A transition from grain to twin boundary cavitation was observed in aged-and-creep-tested type 304 stainless steel. Evidence of twin boundary cavitation has also been observed for unaged material under certain test conditions. This same behavior was also found in aged type 316 stainless steel. Several possible reasons have been suggested for the absence of frequently observed grain boundary cavitation
The causal boundary of wave-type spacetimes
International Nuclear Information System (INIS)
Flores, J.L.; Sanchez, M.
2008-01-01
A complete and systematic approach to compute the causal boundary of wave-type spacetimes is carried out. The case of a 1-dimensional boundary is specially analyzed and its critical appearance in pp-wave type spacetimes is emphasized. In particular, the corresponding results obtained in the framework of the AdS/CFT correspondence for holography on the boundary, are reinterpreted and very widely generalized. Technically, a recent new definition of causal boundary is used and stressed. Moreover, a set of mathematical tools is introduced (analytical functional approach, Sturm-Liouville theory, Fermat-type arrival time, Busemann-type functions)
Discrete transparent boundary conditions for Schroedinger-type equations
International Nuclear Information System (INIS)
Schmidt, F.; Yevick, D.
1997-01-01
We present a general technique for constructing nonlocal transparent boundary conditions for one-dimensional Schroedinger-type equations. Our method supplies boundary conditions for the θ-family of implicit one-step discretizations of Schroedinger's equation in time. The use of Mikusinski's operator approach in time avoids direct and inverse transforms between time and frequency domains and thus implements the boundary conditions in a direct manner. 14 refs., 9 figs
DEFF Research Database (Denmark)
Jakobsen, Bo; Poulsen, Henning Friis; Lienert, U.
2007-01-01
A novel synchrotron-based technique "high angular resolution 3DXRD" is presented in detail, and applied to the characterization of oxygen-free, high-conductivity copper at a tensile deformation of 2%. The position and shape in reciprocal space of 14 peaks originating from deeply embedded individual...... subgrains is reported. From this dataset the density of redundant dislocations in the individual subgrains is inferred to be below 12 × 1012 m-2 on average. It is found that the subgrains on average experience a reduction in strain of 0.9 × 10-4 with respect to the mean elastic strain of the full grain...
Boundary Observability and Stabilization for Westervelt Type Wave Equations without Interior Damping
International Nuclear Information System (INIS)
Kaltenbacher, Barbara
2010-01-01
In this paper we show boundary observability and boundary stabilizability by linear feedbacks for a class of nonlinear wave equations including the undamped Westervelt model used in nonlinear acoustics. We prove local existence for undamped generalized Westervelt equations with homogeneous Dirichlet boundary conditions as well as global existence and exponential decay with absorbing type boundary conditions.
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.
Nonlinear Dynamics of Vortices in Different Types of Grain Boundaries
Sheikhzada, Ahmad K.
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.
Boundary stabilization of memory-type thermoelasticity with second sound
Mustafa, Muhammad I.
2012-08-01
In this paper, we consider an n-dimensional thermoelastic system of second sound with a viscoelastic damping localized on a part of the boundary. We establish an explicit and general decay rate result that allows a wider class of relaxation functions and generalizes previous results existing in the literature.
Phase-transformation and subgrain-deformation characteristics in a cobalt-based superalloy
International Nuclear Information System (INIS)
Benson, M.L.; Reetz, B.; Liaw, P.K.; Reimers, W.; Choo, H.; Brown, D.W.; Saleh, T.A.; Klarstrom, D.L.
2011-01-01
Research highlights: → The mechanical behavior of a cobalt-based superalloy was investigated. → Two diffraction techniques were used to study deformation mechanisms of materials. → In-situ neutron diffraction provides the volume-averaged information. → The peak-profile analysis reveals the information on a subgrain level. → The material exhibited a transformation texture for the HCP phase under loading. - Abstract: A complimentary set of experiments, in situ neutron diffraction and ex situ synchrotron X-ray diffraction, were used to study the phase-transformation and subgrain-deformation characteristics of a cobalt-based superalloy. The neutron diffraction indicated a strain-induced phase transformation in the cobalt-based superalloy under uniaxial tension and compression. The synchrotron X-ray diffraction revealed stacking-fault accumulation and twinning under the same loading conditions. The extent of transformation was found to be greater under tension than under compression. Tensile plastic strains below 2% were accommodated by the stacking-fault creation, while those greater than 2% were accommodated by the phase transformation. Twinning was found to be more active under compressive loading than under tensile loading.
Vragov’s boundary value problem for an implicit equation of mixed type
Egorov, I. E.
2017-10-01
We study a Vragov boundary value problem for a third-order implicit equation of mixed type with an arbitrary manifold of type switch. These Sobolev-type equations arise in many important applied problems. Given certain constraints on the coefficients and the right-hand side of the equation, we demonstrate, using nonstationary Galerkin method and regularization method, the unique regular solvability of the boundary value problem. We also obtain an error estimate for approximate solutions of the boundary value problem in terms of the regularization parameter and the eigenvalues of the Dirichlet spectral problem for the Laplace operator.
Nonlinear $q$-fractional differential equations with nonlocal and sub-strip type boundary conditions
Directory of Open Access Journals (Sweden)
Bashir Ahmad
2014-06-01
Full Text Available This paper is concerned with new boundary value problems of nonlinear $q$-fractional differential equations with nonlocal and sub-strip type boundary conditions. Our results are new in the present setting and rely on the contraction mapping principle and a fixed point theorem due to O'Regan. Some illustrative examples are also presented.
Heat conduction in a plate-type fuel element with time-dependent boundary conditions
International Nuclear Information System (INIS)
Faya, A.J.G.; Maiorino, J.R.
1981-01-01
A method for the solution of boundary-value problems with variable boundary conditions is applied to solve a heat conduction problem in a plate-type fuel element with time dependent film coefficient. The numerical results show the feasibility of the method in the solution of this class of problems. (Author) [pt
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.
Microstructural analysis of the type-II boundary region in Alloy 152 weld
Energy Technology Data Exchange (ETDEWEB)
Yoo, Seung Chang; Choi, Kyoung Joon; Kim, Ji Hyun [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)
2014-10-15
The weld metals are more susceptible to SCC growth and that most cracks are blunted by the fusion boundary. However, they also found that some cracking occurs along the fusion boundary, often in an area with high hardness. Nelson et al. investigated a DMW of Monel 409 stainless steel and American Iron and Steel Institute (AISI) 1080 alloy and found a type-II boundary, which exists parallel to the fusion boundary in the dilution zone. They conclude that the type-II boundary is a potential path for crack growth. While there are several theories for the mechanisms of the type-II boundary formation, they conclude that the type-II boundary forms from the allotropic δ-γ transformation at the base metal in the elevated austenitic temperature range. As the operation time of nuclear power plants using DMWs of Alloy 152 and A533 Gr. B increases, these DMWs must be evaluated for their resistance to SCC for long-term operations. However, only few studies have investigated the thermal aging effects induced by long-term operations at high temperature. Type-II boundary is known as a potential crack path from the results of crack growth test at DMW without any heat treatment. So the analysis about type-II boundary with applying heat treatment could be helpful to evaluate the susceptibility to SCC of structural materials. The objective of this study is to analyze the detailed microstructure of the type-II boundary region in the DMW of Alloy 152 and A533 Gr. B, after applying heat treatment simulating thermal aging effect of a nuclear power plant operation condition to evaluate the susceptibility of this region to SCC. The microstructure of the type-II boundary region in the DMW of Alloy 152 and A533 Gr. B were analyzed with an energy dispersive x-ray spectroscope attached to a scanning electron microscope (SEM-EDS), electron backscatter diffraction (EBSD), and a nanoindentation test. Microstructural, grain boundary orientation, nanohardness analysis were conducted in the type
Microstructural analysis of the type-II boundary region in Alloy 152 weld
International Nuclear Information System (INIS)
Yoo, Seung Chang; Choi, Kyoung Joon; Kim, Ji Hyun
2014-01-01
The weld metals are more susceptible to SCC growth and that most cracks are blunted by the fusion boundary. However, they also found that some cracking occurs along the fusion boundary, often in an area with high hardness. Nelson et al. investigated a DMW of Monel 409 stainless steel and American Iron and Steel Institute (AISI) 1080 alloy and found a type-II boundary, which exists parallel to the fusion boundary in the dilution zone. They conclude that the type-II boundary is a potential path for crack growth. While there are several theories for the mechanisms of the type-II boundary formation, they conclude that the type-II boundary forms from the allotropic δ-γ transformation at the base metal in the elevated austenitic temperature range. As the operation time of nuclear power plants using DMWs of Alloy 152 and A533 Gr. B increases, these DMWs must be evaluated for their resistance to SCC for long-term operations. However, only few studies have investigated the thermal aging effects induced by long-term operations at high temperature. Type-II boundary is known as a potential crack path from the results of crack growth test at DMW without any heat treatment. So the analysis about type-II boundary with applying heat treatment could be helpful to evaluate the susceptibility to SCC of structural materials. The objective of this study is to analyze the detailed microstructure of the type-II boundary region in the DMW of Alloy 152 and A533 Gr. B, after applying heat treatment simulating thermal aging effect of a nuclear power plant operation condition to evaluate the susceptibility of this region to SCC. The microstructure of the type-II boundary region in the DMW of Alloy 152 and A533 Gr. B were analyzed with an energy dispersive x-ray spectroscope attached to a scanning electron microscope (SEM-EDS), electron backscatter diffraction (EBSD), and a nanoindentation test. Microstructural, grain boundary orientation, nanohardness analysis were conducted in the type
National Research Council Canada - National Science Library
Chu, Peter C; Chen, Yuchun; Lu, Shihua
2001-01-01
... (Russell et al,, 1995) was used to verify the validity of Haney-type surface thermal boundary condition, which linearly connects net downward surface heat flux Q to air / sea temperature difference DeltaT by a relaxation coefficient K...
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.
Subgrain and dislocation structure changes in hot-deformed high-temperature Fe-Ni austenitic alloy
International Nuclear Information System (INIS)
Ducki, K.J.; Rodak, K.; Hetmanczyk, M.; Kuc, D.
2003-01-01
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 -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
DEFF Research Database (Denmark)
Wejdemann, Christian; Poulsen, Henning Friis; Lienert, U.
2009-01-01
to additional 5% strain is performed in situ while mapping a selected X-ray reflection from one particular bulk grain with high angular resolution. The reciprocal space maps are analyzed with a recently developed fitting method, and a correlation is found between the evolution of the subgrain volume fraction...
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.
Grain-size distributions and grain boundaries of chalcopyrite-type thin films
International Nuclear Information System (INIS)
Abou-Ras, D.; Schorr, S.; Schock, H.W.
2007-01-01
CuInSe 2 , CuGaSe 2 , Cu(In,Ga)Se 2 and CuInS 2 thin-film solar absorbers in completed solar cells were studied in cross section by means of electronbackscatter diffraction. From the data acquired, grain-size distributions were extracted, and also the most frequent grain boundaries were determined. The grain-size distributions of all chalcopyrite-type thin films studied can be described well by lognormal distribution functions. The most frequent grainboundary types in these thin films are 60 - left angle 221 right angle tet and 71 - left angle 110 right angle tet (near) Σ3 twin boundaries. These results can be related directly to the importance of {112} tet planes during the topotactical growth of chalcopyrite-type thin films. Based on energetic considerations, it is assumed that the most frequent twin boundaries exhibit a 180 - left angle 221 right angle tet constellation. (orig.)
Application of the perturbation iteration method to boundary layer type problems.
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.
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.
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.
GENERAL DECAY FOR A DIFFERENTIAL INCLUSION OF KIRCHHOFF TYPE WITH A MEMORY CONDITION AT THE BOUNDARY
Institute of Scientific and Technical Information of China (English)
Jum-Ran KANG
2014-01-01
In this article, we consider a differential inclusion of Kirchhoff type with a memory condition at the boundary. We prove the asymptotic behavior of the corresponding solutions. For a wider class of relaxation functions, we establish a more general decay result, from which the usual exponential and polynomial decay rates are only special cases.
M. Denche; A. L. Marhoune
2003-01-01
In this paper, we study a mixed problem with integral boundary conditions for a high order partial differential equation of mixed type. We prove the existence and uniqueness of the solution. The proof is based on energy inequality, and on the density of the range of the operator generated by the considered problem.
Role of strained nano-regions in the formation of subgrains in CaCu3Ti4O12
Fang, Tsang-Tse; Wang, Yong-Huei; Kuo, Jui-Chao
2011-07-01
Single-phase CaCu3Ti4O12 (CCTO) was synthesized by solid-state reaction. Electron backscatter diffraction, scanning electron microscopy, and atomic force microscopy were adopted to characterize the grain orientation, microstructure, and surface morphology of the CCTO samples with or without thermal etching. Bump strained nano-regions induced by the local compositional disorder at a nano-scale have been discovered, being the origin of the formation of subgrains in CCTO. The proposed mechanism for the formation of subgrains involves the formation of etched pits and subboundaries pertaining to the strained nano-regions rather than dislocation displacement. The dielectric response inside the grains of CCTO relevant to the strained nano-regions is also discussed.
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....
Subgrain Rotation Behavior in Sn3.0Ag0.5Cu-Sn37Pb Solder Joints During Thermal Shock
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.
International Nuclear Information System (INIS)
Makhan'kov, V.G.; Slavov, S.I.
1989-01-01
Vector nonlinear Schroedinger equations (VS3) is investigated under quasi-constant boundary conditions. New two-soliton solutions are obtained with such non-trivial dynamics that they may be called the breather solutions. A version of the basic Novikov-Dubrovin-Krichever algebro-geometrical approach is applied to obtain breather like solutions existing for all types of internal symmetry is specified are formulated in terms of the soliton velocity expressed via the parameters of the problem. 4 refs
International Nuclear Information System (INIS)
Ahmedabadi, Parag M.; Kain, Vivekanand; Dangi, Bhupinder Kumar; Samajdar, I.
2013-01-01
Highlights: ► Low-level of residual strain improved resistance to sensitisation. ► High fraction of special boundaries did not always reduce sensitisation. ► Area attacked during the EPR test correlated well with degree of sensitisation. ► Volume loss during the EPR test also correlated well with degree of sensitisation. - Abstract: The effects of residual strain and grain boundary character distribution on sensitisation of type 304 stainless steel at 525 °C were evaluated using electrochemical potentiokinetic reactivation (EPR) technique. The results indicated that a very low level of residual strain and a high fraction of annealing twins significantly improved the resistance to sensitisation. Image analysis indicated that the fraction of area attacked during the EPR test correlated well with the EPR data. The volume loss, calculated using atomic force microscopic examinations, during the EPR tests also correlated well with the EPR results.
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.
Role of grain boundaries in the conduction of Eu–Ni substituted Y-type hexaferrites
Energy Technology Data Exchange (ETDEWEB)
Ali, Irshad, E-mail: irshadalibzu@gmail.com [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Islam, M.U. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Naeem Ashiq, Muhammad, E-mail: naeemashiqqau@yahoo.com [Institute of Chemical Sciences, Bahauddin Zakariya University, Multan 60800 (Pakistan); Asif Iqbal, M. [National University of Sciences and Technology, EME College, Islamabad (Pakistan); Khan, Hasan M. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Murtaza, G. [Centre for Advanced Studies in Physics, Government College University, Lahore 54000 (Pakistan)
2014-08-01
Single phase nanostructured (Eu–Ni) substituted Y-type hexaferrites with nominal composition of Sr{sub 2}Co{sub 2−x}Ni{sub x}Eu{sub y}Fe{sub 12−y}O{sub 22} (x=0.0–1, y=0.0–0.1) were synthesized by the microemulsion method. Temperature dependent DC electrical conductivity and drift mobility were found in good agreement with each other, reflecting semiconducting behavior. The presence of Debye peaks in imaginary electric modulus curves confirmed the existence of relaxation phenomena in given frequency range. The AC conductivity follows power law, with exponent (n) value, ranges from 0.81–0.97, indicating that the mechanism is due to polaron hopping. In the present ferrite system, Cole–Cole plots were used to separate the grain and grain boundary effects. Eu–Ni substitution leads to a remarkable rise of grain boundary resistance as compared to the grain resistance. As both AC conductivity and Cole–Cole plots are the functions of concentration, they reveal the dominant contribution of grain boundaries in the conduction mechanism. It was also observed that the AC activation energy is lower than the DC activation energy. Appreciable improved values of quality factor suggested the possible use of these synthesized materials for power applications and high frequency multilayer chip inductors. - Highlights: • Single phase nanostructures were synthesized by the micro-emulsion method. • Substitution leads to a remarkable rise of grain boundary resistance. • The AC activation energy is lower than the DC activation energy. • Improved values of quality factor make these materials useful for high frequency multilayer chip inductors.
Boundary layer effects on the vortex shedding in a Donaldson- type hydrofoil
International Nuclear Information System (INIS)
Fontanals, A; Guardo, A; Egusquiza, E; Zobeiri, A; Farhat, M; Avellan, F
2014-01-01
Fluid - Structure Interaction (FSI) phenomena is becoming a relevant study field for the design or revamping of hydropower plants. The generalized trend of increasing flow rates and reducing rotor blades/stay vanes thickness in order to improve the efficiency of the machine together with a major push from plant owners/operators for production flexibility (partial load operation is more common nowadays) make the FSI between the vortex shedding phenomenon and the vanes/blades of the machine an area of interest. From a design point of view, the machine structure has to resist all the hydrodynamic forces generated and maintain tension stresses under the fatigue limit to ensure a machine lifetime of several decades. To accomplish that goal, designers have to assure there is no presence of strong coupling phenomena (lock-in) between the vortex shedding frequency and the eigenfrequencies of the structure. As the vortex street is directly related to the state of the boundary layer along the hydrofoil, in this paper the effect of the boundary layer on the vortex shedding in a Donaldson-type hydrofoil is studied using Computational Fluid Dynamics (CFD). The development of the boundary layer along the Donaldson trailing edge hydrofoil chord is presented under lock-off conditions. The results are validated against previously obtained experimental results. Since the Donaldson trailing edge is non-symmetric, the boundary layer velocity profiles are reported for the suction and pressure side of the hydrofoil. In addition, the effect of the Donaldson trailing edge on laminar-to-turbulent transition on both sides of the hydrofoil is studied
International Nuclear Information System (INIS)
Itagaki, Masafumi; Sahashi, Naoki.
1997-01-01
The multiple reciprocity boundary element method has been applied to three-dimensional two-group neutron diffusion problems. A matrix-type boundary integral equation has been derived to solve the first and the second group neutron diffusion equations simultaneously. The matrix-type fundamental solutions used here satisfy the equation which has a point source term and is adjoint to the neutron diffusion equations. A multiple reciprocity method has been employed to transform the matrix-type domain integral related to the fission source into an equivalent boundary one. The higher order fundamental solutions required for this formulation are composed of a series of two types of analytic functions. The eigenvalue itself is also calculated using only boundary integrals. Three-dimensional test calculations indicate that the present method provides stable and accurate solutions for criticality problems. (author)
Development of mapped stress-field boundary conditions based on a Hill-type muscle model.
Cardiff, P; Karač, A; FitzPatrick, D; Flavin, R; Ivanković, A
2014-09-01
Forces generated in the muscles and tendons actuate the movement of the skeleton. Accurate estimation and application of these musculotendon forces in a continuum model is not a trivial matter. Frequently, musculotendon attachments are approximated as point forces; however, accurate estimation of local mechanics requires a more realistic application of musculotendon forces. This paper describes the development of mapped Hill-type muscle models as boundary conditions for a finite volume model of the hip joint, where the calculated muscle fibres map continuously between attachment sites. The applied muscle forces are calculated using active Hill-type models, where input electromyography signals are determined from gait analysis. Realistic muscle attachment sites are determined directly from tomography images. The mapped muscle boundary conditions, implemented in a finite volume structural OpenFOAM (ESI-OpenCFD, Bracknell, UK) solver, are employed to simulate the mid-stance phase of gait using a patient-specific natural hip joint, and a comparison is performed with the standard point load muscle approach. It is concluded that physiological joint loading is not accurately represented by simplistic muscle point loading conditions; however, when contact pressures are of sole interest, simplifying assumptions with regard to muscular forces may be valid. Copyright © 2014 John Wiley & Sons, Ltd.
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.
International Nuclear Information System (INIS)
Jacobs, A.J.; Wozadlo, G.P.; Nakata, K.
1994-01-01
Scanning transmission electron microscopy (STEM) analyses, in-reactor swelling mandrel tests, and laboratory constant extension rate tensile (CERT) tests were conducted on nine custom type 348 (UNS S34800) stainless steel (SS) alloys in an attempt to correlate grain boundary composition with irradiation-assisted stress corrosion cracking (IASCC) resistance. Phosphorus (P) enrichment showed the best correlation with in-reactor test results, and chromium (Cr) depletion showed the best correlation with laboratory results. Silicon (Si) and P enrichment were found to depend quantitatively on the bulk concentrations of these elements. The amount of Cr depletion seemed dependent at least partially on the amounts of Si and/or P enrichment. Si and P enrichment and Cr depletion were suppressed by higher carbon (C) contents, such as that present in commercial-purity type 348 SS
DEFF Research Database (Denmark)
Borthwick, V. E.; Schmidt, Søren; Piazolo, S.
2012-01-01
Here we present the first four dimensional (time and three dimensional space resolved) experiment on a strongly deformed geological material. Results show that even complicated microstructures with large continuous and discontinuous changes in crystallographic orientation can be resolved...... quantitatively. The details that can be resolved are unprecedented and therefore the presented technique promises to become influential in a wide range of geoscientific investigations. Grain and subgrain scale processes are fundamental to mineral deformation and associated Earth Dynamics, and time resolved...... been questioned. Our study shows that, although the nature of recovery processes are the same, the area swept by subgrain boundaries is up to 5 times larger in the volume than observed on the surface. We suggest this discrepancy is due to enhanced drag force on subgrain boundaries by thermal surface...
Directory of Open Access Journals (Sweden)
M. Collaud Coen
2011-06-01
Full Text Available Fourteen years of meteorological parameters, aerosol variables (absorption and scattering coefficients, aerosol number concentration and trace gases (CO, NO_{x}, SO_{2} measured at the Jungfraujoch (JFJ, 3580 m a.s.l. have been analyzed as a function of different synoptic weather types. The Schüepp synoptic weather type of the Alps (SYNALP classification from the Alpine Weather Statistics (AWS was used to define the synoptic meteorology over the whole Swiss region. The seasonal contribution of each synoptic weather type to the aerosol concentration was deduced from the aerosol annual cycles while the planetary boundary layer (PBL influence was estimated by means of the diurnal cycles. Since aerosols are scavenged by precipitation, the diurnal cycle of the CO concentration was also used to identify polluted air masses. SO_{2} and NO_{x} concentrations were used as precursor tracers for new particle formation and growth, respectively. The aerosol optical parameters and number concentration show elevated loadings during advective weather types during the December–March period and for the convective anticyclonic and convective indifferent weather types during the April–September period. This study confirms the consensus view that the JFJ is mainly influenced by the free troposphere during winter and by injection of air parcels from the PBL during summer. A more detailed picture is, however, drawn where the JFJ is completely influenced by free tropospheric air masses in winter during advective weather types and largely influenced by the PBL also during the night in summer during the subsidence weather type. Between these two extreme situations, the PBL influence at the JFJ depends on both the time of year and the synoptic weather type. The fraction of PBL air transported to the JFJ was estimated by the relative increase of the specific humidity and CO.
Discrete Boltzmann Method with Maxwell-Type Boundary Condition for Slip Flow
Zhang, Yu-Dong; Xu, Ai-Guo; Zhang, Guang-Cai; Chen, Zhi-Hua
2018-01-01
The rarefied effect of gas flow in microchannel is significant and cannot be well described by traditional hydrodynamic models. It has been known that discrete Boltzmann model (DBM) has the potential to investigate flows in a relatively wider range of Knudsen number because of its intrinsic kinetic nature inherited from Boltzmann equation. It is crucial to have a proper kinetic boundary condition for DBM to capture the velocity slip and the flow characteristics in the Knudsen layer. In this paper, we present a DBM combined with Maxwell-type boundary condition model for slip flow. The tangential momentum accommodation coefficient is introduced to implement a gas-surface interaction model. Both the velocity slip and the Knudsen layer under various Knudsen numbers and accommodation coefficients can be well described. Two kinds of slip flows, including Couette flow and Poiseuille flow, are simulated to verify the model. To dynamically compare results from different models, the relation between the definition of Knudsen number in hard sphere model and that in BGK model is clarified. Support of National Natural Science Foundation of China under Grant Nos. 11475028, 11772064, and 11502117 Science Challenge Project under Grant Nos. JCKY2016212A501 and TZ2016002
International Nuclear Information System (INIS)
Tarasov, Yu.V.; Shostenko, L.D.
2015-01-01
A unified theory for the conductance of an infinitely long multimode quantum wire whose finite segment has randomly rough lateral boundaries is developed. It enables one to rigorously take account of all feasible mechanisms of wave scattering, both related to boundary roughness and to contacts between the wire rough section and the perfect leads within the same technical frameworks. The rough part of the conducting wire is shown to act as a mode-specific randomly modulated effective potential barrier whose height is governed essentially by the asperity slope. The mean height of the barrier, which is proportional to the average slope squared, specifies the number of conducting channels. Under relatively small asperity amplitude this number can take on arbitrary small, up to zero, values if the asperities are sufficiently sharp. The consecutive channel cut-off that arises when the asperity sharpness increases can be regarded as a kind of localization, which is not related to the disorder per se but rather is of entropic or (equivalently) geometric origin. The fluctuating part of the effective barrier results in two fundamentally different types of guided wave scattering, viz., inter- and intramode scattering. The intermode scattering is shown to be for the most part very strong except in the cases of (a) extremely smooth asperities, (b) excessively small length of the corrugated segment, and (c) the asperities sharp enough for only one conducting channel to remain in the wire. Under strong intermode scattering, a new set of conducting channels develops in the corrugated waveguide, which have the form of asymptotically decoupled extended modes subject to individual solely intramode random potentials. In view of this fact, two transport regimes only are realizable in randomly corrugated multimode waveguides, specifically, the ballistic and the localized regime, the latter characteristic of one-dimensional random systems. Two kinds of localization are thus shown to
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.
Directory of Open Access Journals (Sweden)
Patrick Terriault
2017-01-01
Full Text Available Emergent additive manufacturing processes allow the use of metallic porous structures in various industrial applications. Because these structures comprise a large number of ordered unit cells, their design using conventional modeling approaches, such as finite elements, becomes a real challenge. A homogenization technique, in which the lattice structure is simulated as a fully dense volume having equivalent material properties, can then be employed. To determine these equivalent material properties, numerical simulations can be performed on a single unit cell of the lattice structure. However, a critical aspect to consider is the boundary conditions applied to the external faces of the unit cell. In the literature, different types of boundary conditions are used, but a comparative study is definitely lacking. In this publication, a diamond-type unit cell is studied in compression by applying different boundary conditions. If the porous structure’s boundaries are free to deform, then the periodic boundary condition is found to be the most representative, but constraint equations must be introduced in the model. If, instead, the porous structure is inserted in a rigid enclosure, it is then better to use frictionless boundary conditions. These preliminary results remain to be validated for other types of unit cells loaded beyond the yield limit of the material.
International Nuclear Information System (INIS)
Field, Kevin G.; Yang, Ying; Allen, Todd R.; Busby, Jeremy T.
2015-01-01
Radiation induced segregation (RIS) is a well-studied phenomena which occurs in many structurally relevant nuclear materials including austenitic stainless steels. RIS occurs due to solute atoms preferentially coupling with mobile point defect fluxes that migrate and interact with defect sinks. Here, a 304 stainless steel was neutron irradiated up to 47.1 dpa at 320 °C. Investigations into the RIS response at specific grain boundary types were used to determine the sink characteristics of different boundary types as a function of irradiation dose. A rate theory model built on the foundation of the modified inverse Kirkendall (MIK) model is proposed and benchmarked to the experimental results. This model, termed the GiMIK model, includes alterations in the boundary conditions based on grain boundary structure and expressions for interstitial binding. This investigation, through experiment and modeling, found specific grain boundary structures exhibiting unique defect sink characteristics depending on their local structure. Such interactions were found to be consistent across all doses investigated and to have larger global implications, including precipitation of Ni–Si clusters near different grain boundary types
Effects of thermal aging on the microstructure of Type-II boundaries in dissimilar metal weld joints
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.
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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.
CSIR Research Space (South Africa)
Shatalov, MY
2007-04-01
Full Text Available with different types of electric boundary conditions Michael Y. Shatalov*, Arthur G. Every**, Alfred S. Yenwong –Fai*** *Sensor Science and Technology (SST) of CSIR Material Science and Manufacturing, P.O. Box 395, Pretoria 0001, CSIR, South Africa...
Denche, M.; Marhoune, A. L.
2001-01-01
We study a mixed problem with integral boundary conditions for a third-order partial differential equation of mixed type. We prove the existence and uniqueness of the solution. The proof is based on two-sided a priori estimates and on the density of the range of the operator generated by the considered problem.
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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.
International Nuclear Information System (INIS)
Atteridge, D.G.; Wood, W.E.; Advani, A.H.; Bruemmer, S.M.
1990-01-01
Deformation induces an acceleration in the kinetics and reduction in the thermodynamic barrier to carbide precipitation and grain boundary chromium depletion (GBCD) development of a high carbon Type 316 stainless steel (SS). This was observed in a study on strain effects on GBCD (or sensitization) development in the range of 575 degree C to 775 degree C. Grain boundary chromium depletion behavior of SS was examined using the indirect electrochemical potentiokinetic reactivation (EPR) test and supported by studies on carbide precipitation using transmission electron microscopy (TEM). 99 refs., 84 figs., 9 tabs
On Existence of Solutions to the Caputo Type Fractional Order Three-Point Boundary Value Problems
Directory of Open Access Journals (Sweden)
B.M.B. Krushna
2016-10-01
Full Text Available In this paper, we establish the existence of solutions to the fractional order three-point boundary value problems by utilizing Banach contraction principle and Schaefer's fixed point theorem.
Computer generated structures of grain boundaries in Li2-type ordered alloys
International Nuclear Information System (INIS)
DeHosson, J.Th.M.; Pestman, B.J.; Schapink, F.W.; Tichelaar, F.D.
1988-01-01
In recent years, the influence of the establishment of long-range order in cubic alloys on the structure of grain boundaries in Li 2 alloys has been considered. Thus, for example, for the Σ = 5 (310) tilt boundary the various possible structures have been investigated that are generated upon ordering, starting from plausible structures in the disordered state. However, apart from some rough energy estimates based upon nearest neighbor interactions, no reliable energy calculations have been performed of these different possible structures. In this paper, computer calculations based upon interatomic pair potentials constructed in such a way that the Li 2 structure is stable with respect to disordering, are reported for the Σ = 5 (310) boundary. The relative stability of various possible structures, with associated different boundary compositions, has been investigated
Smith, Emily M; Lajoie, Bryan R; Jain, Gaurav; Dekker, Job
2016-01-07
Three-dimensional genome structure plays an important role in gene regulation. Globally, chromosomes are organized into active and inactive compartments while, at the gene level, looping interactions connect promoters to regulatory elements. Topologically associating domains (TADs), typically several hundred kilobases in size, form an intermediate level of organization. Major questions include how TADs are formed and how they are related to looping interactions between genes and regulatory elements. Here we performed a focused 5C analysis of a 2.8 Mb chromosome 7 region surrounding CFTR in a panel of cell types. We find that the same TAD boundaries are present in all cell types, indicating that TADs represent a universal chromosome architecture. Furthermore, we find that these TAD boundaries are present irrespective of the expression and looping of genes located between them. In contrast, looping interactions between promoters and regulatory elements are cell-type specific and occur mostly within TADs. This is exemplified by the CFTR promoter that in different cell types interacts with distinct sets of distal cell-type-specific regulatory elements that are all located within the same TAD. Finally, we find that long-range associations between loci located in different TADs are also detected, but these display much lower interaction frequencies than looping interactions within TADs. Interestingly, interactions between TADs are also highly cell-type-specific and often involve loci clustered around TAD boundaries. These data point to key roles of invariant TAD boundaries in constraining as well as mediating cell-type-specific long-range interactions and gene regulation. Copyright © 2016 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.
International Nuclear Information System (INIS)
Woo, Wan Chuck; Ungar, Tomas; Feng, Zhili; Kenik, Edward A.; Clausen, B.
2009-01-01
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 x 10 14 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 x 10 15 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
Analytic solutions to a family of boundary-value problems for Ginsburg-Landau type equations
Vassilev, V. M.; Dantchev, D. M.; Djondjorov, P. A.
2017-10-01
We consider a two-parameter family of nonlinear ordinary differential equations describing the behavior of a critical thermodynamic system, e.g., a binary liquid mixture, of film geometry within the framework of the Ginzburg-Landau theory by means of the order-parameter. We focus on the case in which the confining surfaces are strongly adsorbing but prefer different components of the mixture, i.e., the order-parameter tends to infinity at one of the boundaries and to minus infinity at the other one. We assume that the boundaries of the system are positioned at a finite distance from each other and give analytic solutions to the corresponding boundary-value problems in terms of Weierstrass and Jacobi elliptic functions.
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Weidong Lv
2015-01-01
Full Text Available By means of Schauder’s fixed point theorem and contraction mapping principle, we establish the existence and uniqueness of solutions to a boundary value problem for a discrete fractional mixed type sum-difference equation with the nonlinear term dependent on a fractional difference of lower order. Moreover, a suitable choice of a Banach space allows the solutions to be unbounded and two representative examples are presented to illustrate the effectiveness of the main results.
General boundary stabilization result of memory-type thermoelasticity with second sound
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Fairouz Boulanouar
2014-09-01
Full Text Available In this article we consider an n-dimensional system of visco-thermoelasticity with second sound, where a viscoelastic dissipation is acting on a part of the boundary. We prove an explicit general decay rate result without imposing $u_0=0$ as in [17]. This allows a larger class of relaxation functions and initial data, hence, generalizes some previous results existing in the literature.
Tangential boundary values of Laplace transforms. Applications to Muntz-Szasz type approximation
Sedletskii, A. M.
2003-02-01
We consider the Laplace transforms (LT) of functions in L^q(\\mathbb R_+), 1, with a slowly varying weight. We prove that if the weight satisfies certain conditions, then each LT of this class has tangential boundary values almost everywhere on the imaginary axis, and the structure of the corresponding neighbourhoods depends on the weight only. This result is applied to distinguish a wide class of weighted L^p spaces on the half-line such that the Szasz condition is not necessary for the completeness of the system \\exp(-\\lambda_n t) in these spaces.
Tangential boundary values of Laplace transforms. Applications to Muntz-Szasz type approximation
Energy Technology Data Exchange (ETDEWEB)
Sedletskii, A M [M.V. Lomonosov Moscow State University, Moscow (Russian Federation)
2003-02-28
We consider the Laplace transforms (LT) of functions in L{sup q}(R{sub +}), 1boundary values almost everywhere on the imaginary axis, and the structure of the corresponding neighbourhoods depends on the weight only. This result is applied to distinguish a wide class of weighted L{sup p} spaces on the half-line such that the Szasz condition is not necessary for the completeness of the system exp(-{lambda}{sub n}t) in these spaces.
Extension Theory and Krein-type Resolvent Formulas for Nonsmooth Boundary Value Problems
DEFF Research Database (Denmark)
Abels, Helmut; Grubb, Gerd; Wood, Ian Geoffrey
2014-01-01
The theory of selfadjoint extensions of symmetric operators, and more generally the theory of extensions of dual pairs, was implemented some years ago for boundary value problems for elliptic operators on smooth bounded domains. Recently, the questions have been taken up again for nonsmooth domains....... In the present work we show that pseudodifferential methods can be used to obtain a full characterization, including Kreĭn resolvent formulas, of the realizations of nonselfadjoint second-order operators on
Kovalenko, S. S.
2014-01-01
We present the group classification of one class of (1+3)-dimensional nonlinear boundary-value problems of the Stefan type that simulate the processes of melting and evaporation of metals. The results obtained are used for the construction of the exact solution of one boundary-value problem from the class under study.
Koyama, Y.; Hatano, M.; Tanimura, M.
1996-05-01
Features of the striped-type superstructure in γ-brass Cu-Al alloys have been investigated mainly by transmission electron microscopy in order to understand the role of a rhombohedral distortion in its stability. From dark field images taken from alloys exhibiting the superstructure, it was found that there exist two types of ferroelastic rhombohedral domains, which are in a twin relation. In other words, the superstructure is characterized by a periodic array of the ferroelastic domains as well as inversion antiphase boundaries. Because charge density waves should be responsible for the formation of the superstructure, as suggested in our previous paper [Phys. Rev. B 40, 5378 (1989)], the rhombohedral distortion must play a crucial role in their appearance. Presumably the distortion enlarges parallel portions of the Fermi surface. On the basis of the present experimental data, the interplay between the striped-type superstructure and the rhombohedral γ-brass structure is also discussed.
A simplified treatment of the boundary conditions of the k- ε model in coarse-mesh CFD-type codes
International Nuclear Information System (INIS)
Analytis, G.Th.; Andreani, M.
1999-01-01
In coarse-mesh, CFD-type codes such as the containment analysis code GOTHIC, one of the options that can be used for modelling of turbulence is the k - ε model. However, in contrast to most other CFD codes which are designed to perform detailed CFD calculations with a large number of spatial meshes, codes such as GOTHIC are primarily aimed at simplified calculation of transients in large spaces (e.g., reactor containments), and generally use coarse meshes. The solution of the two parabolic equations for the k - ε model requires the definition of boundary conditions at physical boundaries and this, in turn, requires very small spatial meshes near these boundaries. Hence, while in codes like CFX this is done in a rigorous and consistent manner, codes like GOTHIC adopt an indirect and heuristic approach, due to the fact that the spatial meshes are usually large. This can have adverse consequences during the calculation of a transient and in this work, we shall give some examples of this and outline a method by which this problem can be avoided. (author)
Dappiaggi, Claudio; Ferreira, Hugo R. C.; Juárez-Aubry, Benito A.
2018-04-01
We study a real, massive Klein-Gordon field in the Poincaré fundamental domain of the (d +1 )-dimensional anti-de Sitter (AdS) spacetime, subject to a particular choice of dynamical boundary conditions of generalized Wentzell type, whereby the boundary data solves a nonhomogeneous, boundary Klein-Gordon equation, with the source term fixed by the normal derivative of the scalar field at the boundary. This naturally defines a field in the conformal boundary of the Poincaré fundamental domain of AdS. We completely solve the equations for the bulk and boundary fields and investigate the existence of bound state solutions, motivated by the analogous problem with Robin boundary conditions, which are recovered as a limiting case. Finally, we argue that both Robin and generalized Wentzell boundary conditions are distinguished in the sense that they are invariant under the action of the isometry group of the AdS conformal boundary, a condition which ensures in addition that the total flux of energy across the boundary vanishes.
M. Collaud Coen; E. Weingartner; M. Furger; S. Nyeki; A. S. H. Prévôt; M. Steinbacher; U. Baltensperger
2011-01-01
Fourteen years of meteorological parameters, aerosol variables (absorption and scattering coefficients, aerosol number concentration) and trace gases (CO, NO_{x}, SO_{2}) measured at the Jungfraujoch (JFJ, 3580 m a.s.l.) have been analyzed as a function of different synoptic weather types. The Schüepp synoptic weather type of the Alps (SYNALP) classification from the Alpine Weather Statistics (AWS) was used to define the synoptic meteorology over the wh...
M. Collaud Coen; E. Weingartner; M. Furger; S. Nyeki; A. S. H. Prévôt; M. Steinbacher; U. Baltensperger
2011-01-01
Fourteen years of meteorological parameters, aerosol variables (absorption and scattering coefficients, aerosol number concentration) and trace gases (CO, NO_{x}, SO_{2}) measured at the Jungfraujoch (JFJ, 3580 m a.s.l.) have been analyzed as a function of different synoptic weather types. The Alpine Weather Statistics (AWS) classification was used to define the synoptic meteorology over the whole Swiss region. The seasonal contribution of each syn...
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...... pinning. The discrepancies between the experimental and theoretical results can be rationalised in terms of the limited nature of the physical effects modelled in the Zener analysis....
Cyclically induced softening due to low-angle boundary annihilation in a martensitic steel
International Nuclear Information System (INIS)
Sauzay, Maxime; Brillet, Helene; Monnet, Isabelle; Mottot, Michel; Barcelo, Francoise; Fournier, Benjamin; Pineau, Andre
2005-01-01
Martensitic steels are known for their softening during cyclic tests carried out at high temperature. The softening has been at least partially explained by lath and sub-grain boundary elimination. This article is dedicated to an attempt at modelling both phenomena. Thanks to mechanical tests it is shown that the softening is mainly due to a decrease of the backstress. Transmission electron microscopy allows us to propose a mechanism of low-angle boundary elimination. Annihilation between dislocations of low-angle boundaries and incident mobile dislocations is modelled. The macroscopic backstress is finally computed using a Hall-Petch law and the Taylor model
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.
Gesztesy, Fritz; Mitrea, Marius
2008-01-01
We study generalized Robin boundary conditions, Robin-to-Dirichlet maps, and Krein-type resolvent formulas for Schr\\"odinger operators on bounded Lipschitz domains in $\\bbR^n$, $n\\ge 2$. We also discuss the case of bounded $C^{1,r}$-domains, $(1/2)
Numerical simulation of X-wing type biplane flapping wings in 3D using the immersed boundary method
International Nuclear Information System (INIS)
Tay, W B; Van Oudheusden, B W; Bijl, H
2014-01-01
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
Shimada, Alisa; Nakano, Hiroki; Sakai, Tôru; Yoshimura, Kazuyoshi
2018-03-01
The S = 1/2 triangular-lattice Heisenberg antiferromagnet with distortion is investigated by the numerical-diagonalization method. The examined distortion type is √{3} × √{3} . We study the case when the distortion connects the undistorted triangular lattice and the dice lattice. For the intermediate phase reported previously in this system, we obtain results of the boundaries of the intermediate phase for a larger system than those in the previous report and examine the system size dependence of the boundaries in detail. We also report the specific heat of this system, which shows a marked peak structure related to the appearance of the intermediate state.
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.
Energy Technology Data Exchange (ETDEWEB)
Jamet, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1967-07-01
This report gives a general presentation of barrier theory for finite difference operators, with its applications to some boundary value problems. (author) [French] Ce rapport est un expose synthetique de la theorie des barrieres pour les operateurs aux differences finies et ses applications a certaines classes de problemes lineaires elliptiques du 'type de Dirichlet'. (auteur)
Czech Academy of Sciences Publication Activity Database
Neustupa, Jiří; Al Baba, Hind
2018-01-01
Roč. 463, č. 1 (2018), s. 222-234 ISSN 0022-247X R&D Projects: GA ČR(CZ) GA17-01747S Institutional support: RVO:67985840 Keywords : Navier-Stokes equation * Navier-type boundary conditions * interior regularity Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 1.064, year: 2016 https://www. science direct.com/ science /article/pii/S0022247X18302233?via%3Dihub
Czech Academy of Sciences Publication Activity Database
Neustupa, Jiří; Al Baba, Hind
2018-01-01
Roč. 463, č. 1 (2018), s. 222-234 ISSN 0022-247X R&D Projects: GA ČR(CZ) GA17-01747S Institutional support: RVO:67985840 Keywords : Navier-Stokes equation * Navier-type boundary conditions * interior regularity Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 1.064, year: 2016 https://www.sciencedirect.com/science/article/pii/S0022247X18302233?via%3Dihub
Pradhan, S. K.; Bhuyan, P.; Kaithwas, C.; Mandal, Sumantra
2018-07-01
Strain-annealing based thermo-mechanical processing has been performed to promote grain boundary engineering (GBE) in an extra-low carbon type austenitic stainless steel without altering the grain size and residual strain to evaluate its sole influence on intergranular corrosion. Single-step processing comprising low pre-strain ( 5 and 10 pct) followed by annealing at 1273 K for 1 hour have resulted in a large fraction of Σ3 n boundaries and significant disruption in random high-angle grain boundaries (RHAGBs) connectivity. This is due to the occurrence of prolific multiple twinning in these specimens as confirmed by their large twin-related domain and twin-related grain size ratio. Among the iterative processing, the schedule comprising two cycles of 10 and 5 pct deformation followed by annealing at 1173 K for 1 hour has yielded the optimum GBE microstructure with the grain size and residual strain akin to the as-received condition. The specimens subjected to the higher number of iterations failed to realize GBE microstructures due to the occurrence of partial recrystallization. Owing to the optimum grain boundary character distribution, the GBE specimen has exhibited remarkable resistance against sensitization and intergranular corrosion as compared to the as-received condition. Furthermore, the lower depth of percolation in the GBE specimen is due to the significant disruption of RHAGBs connectivity as confirmed from its large twin-related domain and lower fractal dimension.
Energy Technology Data Exchange (ETDEWEB)
Peralta, Pedro
2018-04-16
Techniques were developed to measure properties at sub-grain scales using depleted Uranium Oxide (d-UO2) samples heat-treated to obtain different grain sizes and oxygen stoichiometries, through three main tasks: 1) sample processing and characterization, 2) microscale and conventional testing and 3) modeling. Grain size and crystallography were characterized using Scanning Electron Microscopy (SEM), in conjunction with Electron Backscattering Diffraction (EBSD) and Electron Channeling Contrast Imaging (ECCI). Grains were then carefully selected based on their crystallographic orientations to perform ex-situ micromechanical tests with samples machined via Focused Ion Beam (FIB), with emphasis on micro-cantilever bending. These experiments were performed under controlled atmospheres, to insure stoichiometry control, at temperatures up to 700 °C and allowed measurements involving elastic (effective Young’s modulus), plastic (critical resolved shear stresses) and creep (creep strain rates) behavior. Conventional compression experiments were performed simultaneously to compare with the ex-situ measurements and study potential size effects. Modeling was implemented using anisotropic elasticity and inelastic constitutive relations for plasticity and creep based on kinematics and kinetics of dislocation glide that account for the effects of crystal orientation, and stress. The models will be calibrated and validated using the experimental data. This project provided insight on correlations among stoichiometry, crystallography and mechanical behavior in advanced oxide fuels, provided valuable experimental data to validate and calibrate mesoscale fuel performance codes and also a framework to measure sub-grain scale mechanical properties that should be suitable for use with irradiated samples due to small volumes required. The goals and metrics of the ongoing study of thermo-mechanical behavior in depleted uranium dioxide (d-UO2) outlined in this project have been
International Nuclear Information System (INIS)
Zhang Zaiyun; Miao Xiujin; Chen Yuezhong; Liu Zhenhai
2011-01-01
In this paper, we prove the existence, uniqueness, and uniform stability of strong and weak solutions of the nonlinear generalized Klein-Gordon equation (1.1) 1 (see Sec. I) in bounded domains with nonlinear damped boundary conditions given by (1.1) 3 (see Sec. I) with some restrictions on function f(u), h(∇u), g(u t ), and b(x), we prove the existence and uniqueness by means of nonlinear semigroup method and obtain the uniform stabilization by using the multiplier technique.
Kashiwabara, Takahito
Strong solutions of the non-stationary Navier-Stokes equations under non-linearized slip or leak boundary conditions are investigated. We show that the problems are formulated by a variational inequality of parabolic type, to which uniqueness is established. Using Galerkin's method and deriving a priori estimates, we prove global and local existence for 2D and 3D slip problems respectively. For leak problems, under no-leak assumption at t=0 we prove local existence in 2D and 3D cases. Compatibility conditions for initial states play a significant role in the estimates.
International Nuclear Information System (INIS)
Zhu, X; Xu, W
2017-01-01
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. (paper)
Kojitani, Hiroshi; Yamazaki, Monami; Kojima, Meiko; Inaguma, Yoshiyuki; Mori, Daisuke; Akaogi, Masaki
2018-06-01
Heat capacity (C P) of rutile and α-PbO2 type TiO2 (TiO2-II) were measured by the differential scanning calorimetry and thermal relaxation method. Using the results, standard entropies at 1 atm and 298.15 K of rutile and TiO2-II were determined to be 50.04(4) and 46.54(2) J/mol K, respectively. Furthermore, thermal expansivity (α) determined by high-temperature X-ray diffraction measurement and mode Grüneisen parameters obtained by high-pressure Raman spectroscopy suggested the thermal Grüneisen parameter (γ th) for TiO2-II of 1.7(1). By applying the obtained low-temperature C P and γ th, the measured C P and α data of TiO2-II were extrapolated to higher temperature region using a lattice vibrational model calculation, as well as rutile. Internally consistent thermodynamic data sets of both rutile and TiO2-II assessed in this study were used to thermodynamically calculate the rutile‒TiO2-II phase equilibrium boundary. The most plausible boundary was obtained to be P (GPa) = 0.0074T (K) - 1.7. Our boundary suggests that the crystal growth of TiO2-II observed below 5.5 GPa and 900 K in previous studies advanced in its stability field. The phase boundary calculation also suggested small, exothermic phase transition enthalpy from rutile to TiO2-II at 1 atm and 298.15 K of - 0.5 to - 1.1 kJ/mol. This implies that the thermodynamic stability of rutile at 1 atm above room temperature is due to larger contribution of entropy term.
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.
International Nuclear Information System (INIS)
Polley, M.V.
1981-02-01
Diffusion in type 316 stainless steel was studied by depositing 60 Co and 54 Mn on flat polished surfaces and heating. Diffusion profiles, obtained after gamma-counting slices removed by hand grinding, were analysed using Suzuoka's ''instantaneous source'' model. (author)
Substructures developed during creep and cyclic tests of type 304 stainless steel (heat 9T2796)
International Nuclear Information System (INIS)
Swindeman, R.W.; Bhargava, R.K.; Sikka, V.K.; Moteff, J.
1977-09-01
Substructures developed in tested specimens of a reference heat of type 304 stainless steel (heat 9T2796) are examined. Data include dislocation densities, cell and subgrain sizes, and carbide precipitate sizes. Testing conditions range for temperatures from 482 to 649 0 C, for stresses from 28 to 241 MPa, and for times from 4 to 15,000 hr. As expected, it is observed that temperature, stress, and time have strong influences on substructure. The change in the dislocation density is too small to measure for conditions which produce less than 1 percent monotonic strain. No cells form, and the major alteration of substructure is the precipitation of M 23 C 6 carbides on grain boundaries, on twin boundaries, and on some dislocations. At stresses ranging from 69 to 172 MPa and at temperatures ranging from 482 to 593 0 C, the dislocation density increases with increasing stress and is generally higher than expected from studies made at higher temperatures. Dislocations are arranged in fine networks stabilized by carbides. At stresses above 172 MPa and temperatures to 649 0 C, the dislocation density is too great to measure. Cells develop which are finer in size than cells developed at similar stresses but at higher temperatures. Dislocation densities and cell sizes for cyclic specimens are comparable to data for creep-tested specimens. On the basis of the observed substructures, recommendations are made regarding further studies which would assist in the development of constitutive equations for high-temperature inelastic analysis of reactor components
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.
DEFF Research Database (Denmark)
Løvschal, Mette
2014-01-01
of temporal and material variables have been applied as a means of exploring the processes leading to their socioconceptual anchorage. The outcome of this analysis is a series of interrelated, generative boundary principles, including boundaries as markers, articulations, process-related devices, and fixation...
DEFF Research Database (Denmark)
Brodkin, Evelyn; Larsen, Flemming
2013-01-01
project that is altering the boundary between the democratic welfare state and the market economy. We see workfare policies as boundary-changing with potentially profound implications both for individuals disadvantaged by market arrangements and for societies seeking to grapple with the increasing...
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......, 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.......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...
International Nuclear Information System (INIS)
Seo, Moo Hong; Chun, Byong Sun; Oh, Yong Jun; Ryu, Woo Seog; Hong, Jun Hwa
1998-01-01
The precipitation and sensitization behavior of nitrogen added type 316L Stainless Steels (SS) were investigated by using specimens cold worked for 0∼40%. The alloys had a variation in nitrogen content from 0.04 to 0.15%. To quantify the degree of sensitization, Double-Loop Electrochemical Potentiokinetic Reactivation (DL-EPR) test was performed in a 0.1M H 2 SO 4 + 0.01M KSCN solution at 30 .deg. C. The addition of nitrogen increased sensitization resistance by retarding the onset of M 23 C 6 precipitation and shifted Time-Temperature-Sensitization(TTS) curve to higher temperature and longer time range. Cold work accelerated the M 23 C 6 precipitation and sensitization kinetic due to the increase in dislocation density. However, the acceleration of sensitization was found to depend on the added nitrogen content in the alloys. The alloys with high nitrogen(>0.1%N) content exhibited higher acceleration of the sensitization as a function of the cold work than that with low nitrogen content. From the microstructural analysis, this was found to be attributed to the development of intensive slip bands during cold work and retardation of dislocation annihilation during subsequent aging in the alloys with high nitrogen content
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...... approach with pattern matching is a way to shed light on the tacit local knowledge that organizational actors cannot articulate and that an exclusively inductive research is not likely to unveil....
DEFF Research Database (Denmark)
Neergaard, Ulla; Nielsen, Ruth
2010-01-01
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...... and distributive justice at national level....
Wang, Bin; Liu, Fangmeng; Yang, Xue; Guan, Yehui; Ma, Ce; Hao, Xidong; Liang, Xishuang; Liu, Fengmin; Sun, Peng; Zhang, Tong; Lu, Geyu
2016-07-06
A well-ordered porous three-phase boundary (TPB) was prepared with a polystyrene sphere as template and examined to improve the sensitivity of yttria-stabilized zirconia (YSZ)-based mixed-potential-type NO2 sensor due to the increase of the electrochemical reaction active sites. The shape of pore array on the YSZ substrate surface can be controlled through changing the concentration of the precursor solution (Zr(4+)/Y(3+) = 23 mol/L/4 mol/L) and treatment conditions. An ordered hemispherical array was obtained when CZr(4+) = 0.2 mol/L. The processed YSZ substrates were used to fabricate the sensors, and different sensitivities caused by different morphologies were tested. The sensor with well-ordered porous TPB exhibited the highest sensitivity to NO2 with a response value of 105 mV to 100 ppm of NO2, which is approximately twice as much as the smooth one. In addition, the sensor also showed good stability and speedy response kinetics. All these enhanced sensing properties might be due to the structure and morphology of the enlarged TPB.
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.
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....
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
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.
International Nuclear Information System (INIS)
Yoon, Kyung Ho; Lee, Kang Hee; Kang, Heung Seok; Song, Kee Nam
2006-01-01
Characterization tests (load vs. displacement curve) are conducted for the springs of Zirconium alloy spacer grids for an advanced LWR fuel assembly. Twofold testing is employed: strap-based and assembly-based tests. The assembly-based test satisfies the in situ boundary conditions of the spring within the grid assembly. The aim of the characterization test via the aforementioned two methods is to establish an appropriate assembly-based test method that fulfills the actual boundary conditions. A characterization test under the spacer grid assembly boundary condition is also conducted to investigate the actual behavior of the spring in the core. The stiffness of the characteristic curve is smaller than that of the strap-wised boundary condition. This phenomenon may cause the strap slit condition. A spacer grid consists of horizontal and vertical straps. The strap slit positions are differentiated from each other. They affords examination of the variation of the external load distribution in the grid spring. Localized regions of high stress and their values are analyzed, as they may be affected by the spring shape. Through a comparison of the results of the test and FE analysis, it is concluded that the present assembly-based analysis model and procedure are reasonably well conducted and can be used for spring characterization in the core. Guidelines for improving the mechanical integrity of the spring are also discussed
The Boundary Function Method. Fundamentals
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.
Conformal boundary loop models
International Nuclear Information System (INIS)
Jacobsen, Jesper Lykke; Saleur, Hubert
2008-01-01
We study a model of densely packed self-avoiding loops on the annulus, related to the Temperley-Lieb algebra with an extra idempotent boundary generator. Four different weights are given to the loops, depending on their homotopy class and whether they touch the outer rim of the annulus. When the weight of a contractible bulk loop x≡q+q -1 element of (-2,2], this model is conformally invariant for any real weight of the remaining three parameters. We classify the conformal boundary conditions and give exact expressions for the corresponding boundary scaling dimensions. The amplitudes with which the sectors with any prescribed number and types of non-contractible loops appear in the full partition function Z are computed rigorously. Based on this, we write a number of identities involving Z which hold true for any finite size. When the weight of a contractible boundary loop y takes certain discrete values, y r ≡([r+1] q )/([r] q ) with r integer, other identities involving the standard characters K r,s of the Virasoro algebra are established. The connection with Dirichlet and Neumann boundary conditions in the O(n) model is discussed in detail, and new scaling dimensions are derived. When q is a root of unity and y=y r , exact connections with the A m type RSOS model are made. These involve precise relations between the spectra of the loop and RSOS model transfer matrices, valid in finite size. Finally, the results where y=y r are related to the theory of Temperley-Lieb cabling
International Nuclear Information System (INIS)
Horton, C.A.P.; Lai, J.K.L.; Skelton, R.P.
Comparisons have been made between microstructures in Type 316 steel after high strain fatigue or creep at 625 deg. C and which had been subjected to various pre-test ageing treatments. The microstructures observed in the specimens generally consisted of a three dimensional dislocation network together with 'cells' delineated by dislocation sub-boundaries. In fatigue, under strain control conditions, pre-ageing reduced the dislocation density and coarsened the cell structure produced during test. This was related to less solute hardening and strain induced precipitation after pre-ageing and was accompanied by a lower rate of cyclic strain hardening. During fatigue with dwell, the dislocations introduced led to five times more precipitation than that observed during stress free ageing solution treated material. The 'cell' structure produced by fatigue was retained even after solution treatment at 1050 deg. C. In creep, under constant loads, a coarser and more clearly defined dislocation sub-grain structure developed and its size was not influenced by pre-ageing. However, creep testing after various pre-treatments, including fatigue, demonstrated that the creep resistance was dependent on a combination of solution strengthening, cell size and dislocation density. Consequently prior fatigue considerably increased the creep resistance. The work has demonstrated the microstructural aspects of creep-fatigue interaction and that the use of creep data obtained from solution treated material is likely to lead to errors in creep-fatigue life fraction summations
Pressure effect on grain boundary diffusion
International Nuclear Information System (INIS)
Smirnova, E.S.; Chuvil'deev, V.N.
1997-01-01
The influence of hydrostatic pressure on grain boundary diffusion and grain boundary migration in metallic materials is theoretically investigated. The model is suggested that permits describing changes in activation energy of grain boundary self-diffusion and diffusion permeability of grain boundaries under hydrostatic pressure. The model is based on the ideas about island-type structure of grain boundaries as well as linear relationship of variations in grain boundary free volume to hydrostatic pressure value. Comparison of theoretical data with experimental ones for a number of metals and alloys (α-Zr, Sn-Ge, Cu-In with Co, In, Al as diffusing elements) shows a qualitative agreement
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
International Nuclear Information System (INIS)
Payri, Raul; López, J. Javier; Martí-Aldaraví, Pedro; Giraldo, Jhoan S.
2016-01-01
Highlights: • LES in a non-reacting jet with co-flow is performed with OpenFoam. • Smagorinsky (SMAG) and One Equation Eddy (OEE) approaches are compared. • A turbulent pipe is used to generate and map coherent inlet turbulence structure. • Fluctuating inlet boundary condition requires much less computational cost. - Abstract: In this paper, the behavior and turbulence structure of a non-reacting jet with a co-flow stream is described by means of Large Eddy Simulations (LES) carried out with the computational tool OpenFoam. In order to study the influence of the sub-grid scale (SGS) model on the main flow statistics, Smagorinsky (SMAG) and One Equation Eddy (OEE) approaches are used to model the smallest scales involved in the turbulence of the jet. The impact of cell size and turbulent inlet boundary condition in resulting velocity profiles is analyzed as well. Four different tasks have been performed to accomplish these objectives. Firstly, the simulation of a turbulent pipe, which is necessary to generate and map coherent turbulence structure into the inlet of the non-reacting jet domain. Secondly, a structured mesh based on hexahedrons has been built for the jet and its co-flow. The third task consists on performing four different simulations. In those, mapping statistics from the turbulent pipe is compared with the use of fluctuating inlet boundary condition available in OpenFoam; OEE and SMAG approaches are contrasted; and the effect of changing cell size is investigated. Finally, as forth task, the obtained results are compared with experimental data. As main conclusions of this comparison, it has been proved that the fluctuating boundary condition requires much less computational cost, but some inaccuracies were found close to the nozzle. Also, both SGS models are capable to simulate this kind of jets with a co-flow stream with exactitude.
DEFF Research Database (Denmark)
Bødker, Susanne; Kristensen, Jannie Friis; Nielsen, Christina
2003-01-01
.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......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...... seem a core issue when dealing with technology for boundaries....
Klimova, Margarita; Stepanov, Nikita; Shaysultanov, Dmitry; Chernichenko, Ruslan; Yurchenko, Nikita; Sanin, Vladimir; Zherebtsov, Sergey
2017-12-29
The effect of cold rolling on the microstructure and mechanical properties of an Al- and C-containing CoCrFeNiMn-type high-entropy alloy was reported. The alloy with a chemical composition (at %) of (20-23) Co, Cr, Fe, and Ni; 8.82 Mn; 3.37 Al; and 0.69 C was produced by self-propagating high-temperature synthesis with subsequent induction. In the initial as-cast condition the alloy had an face centered cubic single-phase coarse-grained structure. Microstructure evolution was mostly associated with either planar dislocation glide at relatively low deformation during rolling (up to 20%) or deformation twinning and shear banding at higher strain. After 80% reduction, a heavily deformed twinned/subgrained structure was observed. A comparison with the equiatomic CoCrFeNiMn alloy revealed higher dislocation density at all stages of cold rolling and later onset of deformation twinning that was attributed to a stacking fault energy increase in the program alloy; this assumption was confirmed by calculations. In the initial as-cast condition the alloy had low yield strength of 210 MPa with yet very high uniform elongation of 74%. After 80% rolling, yield strength approached 1310 MPa while uniform elongation decreased to 1.3%. Substructure strengthening was found to be dominated at low rolling reductions (<40%), while grain (twin) boundary strengthening prevailed at higher strains.
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......: whether an innovation idea is created internally or externally and whether an innovation process relies on external knowledge resources. This yields four possible types of innovation, which represent the nuanced variation of outside-in innovations. Using historical data from Canada for 1945...
International Nuclear Information System (INIS)
Assous, F.; Ciarlet, P.; Sonnendruker, E.
1996-01-01
This study addresses the resolution of Maxwell equations in the case of a non-regular boundary and non-convex domain (presence of inner corners) which requires a notably locally refined mesh to obtain an acceptable numerical solution. The authors focus on a 2D problem which may physically correspond to a 3D problem, for example when the electromagnetic field is independent of one the three space variables (for example an infinite cylinder when the field does not depend on the variable associated with the cylinder axis). Model problems are presented: the steady problem, and the evolution problem. The solution is then decomposed into a regular part and a singular one. The authors report the solution calculation, and then the study of the model problems
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.
Mixed basin boundary structures of chaotic systems
International Nuclear Information System (INIS)
Rosa, E. Jr.; Ott, E.
1999-01-01
Motivated by recent numerical observations on a four-dimensional continuous-time dynamical system, we consider different types of basin boundary structures for chaotic systems. These general structures are essentially mixtures of the previously known types of basin boundaries where the character of the boundary assumes features of the previously known boundary types at different points arbitrarily finely interspersed in the boundary. For example, we discuss situations where an everywhere continuous boundary that is otherwise smooth and differentiable at almost every point has an embedded uncountable, zero Lebesgue measure set of points at which the boundary curve is nondifferentiable. Although the nondifferentiable set is only of zero Lebesgue measure, the curve close-quote s fractal dimension may (depending on parameters) still be greater than one. In addition, we discuss bifurcations from such a mixed boundary to a 'pure' boundary that is a fractal nowhere differentiable curve or surface and to a pure nonfractal boundary that is everywhere smooth. copyright 1999 The American Physical Society
Yuan, Shifei; Jiang, Lei; Yin, Chengliang; Wu, Hongjie; Zhang, Xi
2017-06-01
To guarantee the safety, high efficiency and long lifetime for lithium-ion battery, an advanced battery management system requires a physics-meaningful yet computationally efficient battery model. The pseudo-two dimensional (P2D) electrochemical model can provide physical information about the lithium concentration and potential distributions across the cell dimension. However, the extensive computation burden caused by the temporal and spatial discretization limits its real-time application. In this research, we propose a new simplified electrochemical model (SEM) by modifying the boundary conditions for electrolyte diffusion equations, which significantly facilitates the analytical solving process. Then to obtain a reduced order transfer function, the Padé approximation method is adopted to simplify the derived transcendental impedance solution. The proposed model with the reduced order transfer function can be briefly computable and preserve physical meanings through the presence of parameters such as the solid/electrolyte diffusion coefficients (Ds&De) and particle radius. The simulation illustrates that the proposed simplified model maintains high accuracy for electrolyte phase concentration (Ce) predictions, saying 0.8% and 0.24% modeling error respectively, when compared to the rigorous model under 1C-rate pulse charge/discharge and urban dynamometer driving schedule (UDDS) profiles. Meanwhile, this simplified model yields significantly reduced computational burden, which benefits its real-time application.
International Nuclear Information System (INIS)
Mekhtiyev, M.A.; Kalina, V.A.
1980-01-01
The conditions of appearance of tamm surface states and their energy spectrum on the boundary of semimetals and narrow-gap semiconductors are considered. By the Green function method the equation for surface state energy is obtained. The solution of the latter is analyzed in particular cases when energy of heavy hole zones of the semimetal and semiconductor is the same and when the heavy hole gap of the semiconductor is shifted down relatively to the semimetal of the same name gap as well as accurate computer calculation. It is shown that neither in parabolic limits, nor in cases of a strongly unparabolic semiconductor (semimetal) and a parabolic semimetal (semiconductor) the equation obtained has no solutions at small quasipulse values i.e. there are no surface states. In the case when the heavy hole zone of a semiconductor is shifted down for the value of the order of narrow-gap semiconductor the effective mass of surface states turns to be twice heavier than that of the semimetal volumetrical electrons [ru
Rigid supersymmetry with boundaries
Energy Technology Data Exchange (ETDEWEB)
Belyaev, D.V. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Van Nieuwenhuizen, P. [State Univ. of New York, Stony Brook, NY (United States). C.N. Yang Inst. for Theoretical Physics
2008-01-15
We construct rigidly supersymmetric bulk-plus-boundary actions, both in x-space and in superspace. For each standard supersymmetric bulk action a minimal supersymmetric bulk-plus-boundary action follows from an extended F- or D-term formula. Additional separately supersymmetric boundary actions can be systematically constructed using co-dimension one multiplets (boundary superfields). We also discuss the orbit of boundary conditions which follow from the Euler-Lagrange variational principle. (orig.)
Pushing Boundaries while Maintaining Stability
DEFF Research Database (Denmark)
Lippke, Lena; Wegener, Charlotte
at the same time. The exploration of transforming practices shows how disturbances in relation to the ‘normal’ practices are created and thus makes invisible conventions which are taken for granted visible. Thus, this paper addresses two types of invisibility: the unnoticed boundary-pushing practices...
Gong, Yixiao; Lazaris, Charalampos; Sakellaropoulos, Theodore; Lozano, Aurelie; Kambadur, Prabhanjan; Ntziachristos, Panagiotis; Aifantis, Iannis; Tsirigos, Aristotelis
2018-02-07
The metazoan genome is compartmentalized in areas of highly interacting chromatin known as topologically associating domains (TADs). TADs are demarcated by boundaries mostly conserved across cell types and even across species. However, a genome-wide characterization of TAD boundary strength in mammals is still lacking. In this study, we first use fused two-dimensional lasso as a machine learning method to improve Hi-C contact matrix reproducibility, and, subsequently, we categorize TAD boundaries based on their insulation score. We demonstrate that higher TAD boundary insulation scores are associated with elevated CTCF levels and that they may differ across cell types. Intriguingly, we observe that super-enhancers are preferentially insulated by strong boundaries. Furthermore, we demonstrate that strong TAD boundaries and super-enhancer elements are frequently co-duplicated in cancer patients. Taken together, our findings suggest that super-enhancers insulated by strong TAD boundaries may be exploited, as a functional unit, by cancer cells to promote oncogenesis.
Prodosic cues to discourse boundaries in experimental dialogues
Geluykens, R.; Swerts, M.G.J.
1994-01-01
In a dialogue, there are at least two sorts of boundaries between discourse units. One type of boundary signals the end of a topical unit; another type of boundary the end of a turn at talk. These two do not necessarily coincide, as a speaker may wish to a new topical unit without wanting to be
Directory of Open Access Journals (Sweden)
Yong Cheng
2017-01-01
Full Text Available The hydroelastic behaviour of a pontoon-type VLFS subjected to unsteady external loads in wave condition is investigated in the context of the time-domain modal expansion theory, in which the boundary element method (BEM based on time domain Kelvin sources is used for hydrodynamic forces and the finite element method (FEM is adopted for solving the deflections of the VLFS. In this analysis, the interpolation-tabulation scheme is applied to assess rapidly and accurately the free-surface Green function in finite water depth, and the boundary integral equation of a quarter VLFS model is further established taking advantage of symmetry of flow field and structure. The VLFS is modelled as an equivalent solid plate based on the Mindlin plate theory. The coupled plate-water model is performed to determine the wave-induced responses and transient behaviour under external loads such as a huge mass impact onto the structure and moving loads of an airplane, respectively. These results are verified with existing numerical results and experimental test. Then, the developed numerical tools are used in the study of the combined action taking into account of the mass drop/airplane landing as well as forward or reverse incident wave action. The deflections of the runway, the time history of vertical positions and the trajectory of the airplane are also presented through a systematic time-domain simulation, which illustrates the usefulness of the presently developed numerical solutions.
Political State Boundary (National)
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...
Allegheny County Municipal Boundaries
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...
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...
State Agency Administrative Boundaries
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...
Boundary conditions in random sequential adsorption
Cieśla, Michał; Ziff, Robert M.
2018-04-01
The influence of different boundary conditions on the density of random packings of disks is studied. Packings are generated using the random sequential adsorption algorithm with three different types of boundary conditions: periodic, open, and wall. It is found that the finite size effects are smallest for periodic boundary conditions, as expected. On the other hand, in the case of open and wall boundaries it is possible to introduce an effective packing size and a constant correction term to significantly improve the packing densities.
International Nuclear Information System (INIS)
Doikou, Anastasia
2010-01-01
We examine the symmetry breaking of superalgebras due to the presence of appropriate integrable boundary conditions. We investigate the boundary breaking symmetry associated with both reflection algebras and twisted super-Yangians. We extract the generators of the resulting boundary symmetry as well as we provide explicit expressions of the associated Casimir operators.
Quantum walk with one variable absorbing boundary
International Nuclear Information System (INIS)
Wang, Feiran; Zhang, Pei; Wang, Yunlong; Liu, Ruifeng; Gao, Hong; Li, Fuli
2017-01-01
Quantum walks constitute a promising ingredient in the research on quantum algorithms; consequently, exploring different types of quantum walks is of great significance for quantum information and quantum computation. In this study, we investigate the progress of quantum walks with a variable absorbing boundary and provide an analytical solution for the escape probability (the probability of a walker that is not absorbed by the boundary). We simulate the behavior of escape probability under different conditions, including the reflection coefficient, boundary location, and initial state. Moreover, it is also meaningful to extend our research to the situation of continuous-time and high-dimensional quantum walks. - Highlights: • A novel scheme about quantum walk with variable boundary is proposed. • The analytical results of the survival probability from the absorbing boundary. • The behavior of survival probability under different boundary conditions. • The influence of different initial coin states on the survival probability.
Kopf, Achim
2013-11-01
The location of the seaward tip of a subduction thrust controls material transfer at convergent plate margins, and hence global mass balances. At approximately half of those margins, the material of the subducting plate is completely underthrust so that no accretion or even subduction erosion takes place. Along the remaining margins, material is scraped off the subducting plate and added to the upper plate by frontal accretion. We here examine the physical properties of subducting sediments off Costa Rica and Nankai, type examples for an erosional and an accretionary margin, to investigate which parameters control the level where the frontal thrust cuts into the incoming sediment pile. A series of rotary-shear experiments to measure the frictional strength of the various lithologies entering the two subduction zones were carried out. Results include the following findings: (1) At Costa Rica, clay-rich strata at the top of the incoming succession have the lowest strength (μres = 0.19) while underlying calcareous ooze, chalk and diatomite are strong (up to μres = 0.43; μpeak = 0.56). Hence the entire sediment package is underthrust. (2) Off Japan, clay-rich deposits within the lower Shikoku Basin inventory are weakest (μres = 0.13-0.19) and favour the frontal proto-thrust to migrate into one particular horizon between sandy, competent turbidites below and ash-bearing mud above. (3) Taking in situ data and earlier geotechnical testing into account, it is suggested that mineralogical composition rather than pore-pressure defines the position of the frontal thrust, which locates in the weakest, clay mineral-rich (up to 85 wt.%) materials. (4) Smectite, the dominant clay mineral phase at either margin, shows rate strengthening and stable sliding in the frontal 50 km of the subduction thrust (0.0001-0.1 mm/s, 0.5-25 MPa effective normal stress). (5) Progressive illitization of smectite cannot explain seismogenesis, because illite-rich samples also show velocity
Feynman Integrals with Absorbing Boundaries
Marchewka, A.; Schuss, Z.
1997-01-01
We propose a formulation of an absorbing boundary for a quantum particle. The formulation is based on a Feynman-type integral over trajectories that are confined to the non-absorbing region. Trajectories that reach the absorbing wall are discounted from the population of the surviving trajectories with a certain weighting factor. Under the assumption that absorbed trajectories do not interfere with the surviving trajectories, we obtain a time dependent absorption law. Two examples are worked ...
International Nuclear Information System (INIS)
Dimitrov, O.
1975-01-01
Well-established aspects of grain-boundary migration are first briefly reviewed (influences of driving force, temperature, orientation and foreign atoms). Recent developments of the experimental methods and results are then examined, by considering the various driving of resistive forces acting on grain boundaries. Finally, the evolution in the theoretical models of grain-boundary motion is described, on the one hand for ideally pure metals and, on the other hand, in the presence of solute impurity atoms [fr
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 ...
Heat Kernel Asymptotics of Zaremba Boundary Value Problem
Energy Technology Data Exchange (ETDEWEB)
Avramidi, Ivan G. [Department of Mathematics, New Mexico Institute of Mining and Technology (United States)], E-mail: iavramid@nmt.edu
2004-03-15
The Zaremba boundary-value problem is a boundary value problem for Laplace-type second-order partial differential operators acting on smooth sections of a vector bundle over a smooth compact Riemannian manifold with smooth boundary but with discontinuous boundary conditions, which include Dirichlet boundary conditions on one part of the boundary and Neumann boundary conditions on another part of the boundary. We study the heat kernel asymptotics of Zaremba boundary value problem. The construction of the asymptotic solution of the heat equation is described in detail and the heat kernel is computed explicitly in the leading approximation. Some of the first nontrivial coefficients of the heat kernel asymptotic expansion are computed explicitly.
Inference of boundaries in causal sets
Cunningham, William J.
2018-05-01
We investigate the extrinsic geometry of causal sets in (1+1) -dimensional Minkowski spacetime. The properties of boundaries in an embedding space can be used not only to measure observables, but also to supplement the discrete action in the partition function via discretized Gibbons–Hawking–York boundary terms. We define several ways to represent a causal set using overlapping subsets, which then allows us to distinguish between null and non-null bounding hypersurfaces in an embedding space. We discuss algorithms to differentiate between different types of regions, consider when these distinctions are possible, and then apply the algorithms to several spacetime regions. Numerical results indicate the volumes of timelike boundaries can be measured to within 0.5% accuracy for flat boundaries and within 10% accuracy for highly curved boundaries for medium-sized causal sets with N = 214 spacetime elements.
Shifting boundaries in telecare
DEFF Research Database (Denmark)
Nickelsen, Niels Christian Mossfeldt; Elkjær, Bente
2017-01-01
Purpose Telecare is a growing practice defined as diagnosis, treatment and monitoring among doctors, nurses and patients, which is mediated through ICT and without face-to-face interaction. The purpose of this article is to provide empirically based knowledge about the organization of the use of ...... to clinical decision makers. The notion of ‘paradoxical accountability’ is developed to account for this dilemma. Keywords (max 8) Telecare, infrastructure, practice oriented analysis, healthcare professionals, accountability, boundaries Paper type Case study......Purpose Telecare is a growing practice defined as diagnosis, treatment and monitoring among doctors, nurses and patients, which is mediated through ICT and without face-to-face interaction. The purpose of this article is to provide empirically based knowledge about the organization of the use...... of ICT and dilemmas of this increasingly common practice in healthcare. Findings Telecare embraces new standards and possibilities for professional responsibility and accountability for nurses, but also alters the relationship between doctors and nurses. This leads to a dilemma we characterize...
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
Quigley, Hervey C.; Anderson, Seth B.; Innis, Robert C.
1960-01-01
A flight investigation has been conducted to study how pilots use the high lift available with blowing-type boundary-layer control applied to the leading- and trailing-edge flaps of a 45 deg. swept-wing airplane. The study includes documentation of the low-speed handling qualities as well as the pilots' evaluations of the landing-approach characteristics. All the pilots who flew the airplane considered it more comfortable to fly at low speeds than any other F-100 configuration they had flown. The major improvements noted were the reduced stall speed, the improved longitudinal stability at high lift, and the reduction in low-speed buffet. The study has shown the minimum comfortable landing-approach speeds are between 120.5 and 126.5 knots compared to 134 for the airplane with a slatted leading edge and the same trailing-edge flap. The limiting factors in the pilots' choices of landing-approach speeds were the limits of ability to control flight-path angle, lack of visibility, trim change with thrust, low static directional stability, and sluggish longitudinal control. Several of these factors were found to be associated with the high angles of attack, between 13 deg. and 15 deg., required for the low approach speeds. The angle of attack for maximum lift coefficient was 28 deg.
Development of boundary layers
International Nuclear Information System (INIS)
Herbst, R.
1980-01-01
Boundary layers develop along the blade surfaces on both the pressure and the suction side in a non-stationary flow field. This is due to the fact that there is a strongly fluctuating flow on the downstream blade row, especially as a result of the wakes of the upstream blade row. The author investigates the formation of boundary layers under non-stationary flow conditions and tries to establish a model describing the non-stationary boundary layer. For this purpose, plate boundary layers are measured, at constant flow rates but different interferent frequency and variable pressure gradients. By introducing the sample technique, measurements of the non-stationary boundary layer become possible, and the flow rate fluctuation can be divided in its components, i.e. stochastic turbulence and periodical fluctuation. (GL) [de
Migration mechanisms of a faceted grain boundary
Hadian, R.; Grabowski, B.; Finnis, M. W.; Neugebauer, J.
2018-04-01
We report molecular dynamics simulations and their analysis for a mixed tilt and twist grain boundary vicinal to the Σ 7 symmetric tilt boundary of the type {1 2 3 } in aluminum. When minimized in energy at 0 K , a grain boundary of this type exhibits nanofacets that contain kinks. We observe that at higher temperatures of migration simulations, given extended annealing times, it is energetically favorable for these nanofacets to coalesce into a large terrace-facet structure. Therefore, we initiate the simulations from such a structure and study as a function of applied driving force and temperature how the boundary migrates. We find the migration of a faceted boundary can be described in terms of the flow of steps. The migration is dominated at lower driving force by the collective motion of the steps incorporated in the facet, and at higher driving forces by the step detachment from the terrace-facet junction and propagation of steps across the terraces. The velocity of steps on terraces is faster than their velocity when incorporated in the facet, and very much faster than the velocity of the facet profile itself, which is almost stationary. A simple kinetic Monte Carlo model matches the broad kinematic features revealed by the molecular dynamics. Since the mechanisms seem likely to be very general on kinked grain-boundary planes, the step-flow description is a promising approach to more quantitative modeling of general grain boundaries.
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.
Helmholtz bright and boundary solitons
International Nuclear Information System (INIS)
Christian, J M; McDonald, G S; Chamorro-Posada, P
2007-01-01
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
Administrative Area Boundaries 2 (State Boundaries), Region 9, 2010, NAVTEQ
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...
Administrative Area Boundaries 4 (City Boundaries), Region 9, 2010, NAVTEQ
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...
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...
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...
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...
Allegheny County Parcel Boundaries
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...
Boundary representation modelling techniques
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.
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...
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...
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...
State Park Statutory Boundaries
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...
Study of some properties of point defects in grain boundaries
International Nuclear Information System (INIS)
Martin, Georges
1973-01-01
With the aim of deducing simple informations on the grain boundary core structure, we investigated self diffusion under hydrostatic pressure, impurity diffusion (In and Au), electromigration (Sb) along certain types of grain boundaries in Ag bicrystals, and the Moessbauer effect of 57 Co located in the grain boundaries of polycrystalline Be. Our results lead to the following conclusions: the formation of a vacancy like defects is necessary to grain boundary diffusion; solute atoms may release most of their elastic energy of dissolution as they segregate at the boundary; in an electrical field, the drift of Sb ions parallel to the boundary takes place toward the anode as in the bulk. The force on the grain boundary ions is larger than in the bulk; Moessbauer spectroscopy revealed the formation of Co-rich aggregates, which may proves important in the study of early stages of grain boundary precipitation. (author) [fr
Direct imaging of grain boundaries
International Nuclear Information System (INIS)
Gronsky, R.
1979-09-01
There are currently two types of microscopes which, in principle, are capable of imaging atom positions at grain boundaries. One, the field ion microscope (FIM), yields a projection of the specimen surface (approximately stereographic) by field ionization of an imaging gas at protruding atom sites, and provides topographic information in high-index pole regions which may be interpreted atom-by-atom. The other, a transmission electron microscope (TEM), yields a projection (approximately linear) of the entire specimen thickness by electron optical imaging, and provides atomic resolution detail throughout the illuminated area. In this paper, both methods are described and compared, using examples from practical materials systems
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.
Grain boundary structure and properties
International Nuclear Information System (INIS)
Balluffi, R.W.
1979-01-01
An attempt is made to distinguish those fundamental aspects of grain boundaries which should be relevant to the problem of the time dependent fracture of high temperature structural materials. These include the basic phenomena which are thought to be associated with cavitation and cracking at grain boundaries during service and with the more general microstructural changes which occur during both processing and service. A very brief discussion of the current state of our knowledge of these fundamentals is given. Included are the following: (1) structure of ideal perfect boundaries; (2) defect structure of grain boundaries; (3) diffusion at grain boundaries; (4) grain boundaries as sources/sinks for point defects; (5) grain boundary migration; (6) dislocation phenomena at grain boundaries; (7) atomic bonding and cohesion at grain boundaries; (8) non-equilibrium properties of grain boundaries; and (9) techniques for studying grain boundaries
International Nuclear Information System (INIS)
Gol'dshtejn, Ya.E.; Shmatko, M.N.; Chuvatina, S.N.
1976-01-01
With the concept that the state of grain and subgrain boundaries influences the hot plasticity of corrosion resistant steel as a starting point, the study was undertaken of the effect of boron microalloying up on the intergranular strength and of the action boron exerts upon the distribution (redistribution) of other phases present in austenitic 03Kh16N14M3 steels. An electron microscope study of the composition of redundant phases and that of the fine structure of steel have shown the effect of small additions of boron upon the hot plasticity of steel to be linked directly to its influence upon austenite disintegration and the precipitation along the boundaries of crystals of redundant phases in the course of hot plastic deformation. The action of boron upon the process plasticity of steel depends on the temperature and the rate of deformation which govern the kinetics of the precipitation of the redundant phases
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.
Trowbridge, John H.; Lentz, Steven J.
2018-01-01
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.
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)
Minnesota County Boundaries - lines
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....
DEFF Research Database (Denmark)
Bossen, Claus; Jensen, Lotte Groth; Udsen, Flemming Witt
2014-01-01
implementation, which also coupled the work of medical secretaries more tightly to that of other staff, and led to task drift among professions. Medical secretaries have been relatively invisible to health informatics and CSCW, and we propose the term ‘boundary-object trimming’ to foreground and conceptualize...
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....
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.
Structure of grain boundaries in hexagonal materials
International Nuclear Information System (INIS)
Sarrazit, F.
1998-05-01
The work presented in this thesis describes experimental and theoretical aspects associated with the structure of grain boundaries in hexagonal materials. It has been found useful to classify grain boundaries as low-angle, special or general on the basis of their structure. High-angle grain boundaries were investigated in tungsten carbide (WC) using conventional electron microscopy techniques, and three examples characteristic of the interfaces observed in this material were studied extensively. Three-dimensionally periodic patterns are proposed as plausible reference configurations, and the Burgers vectors of observed interfacial dislocations were predicted using a theory developed recently. The comparison of experimental observations with theoretical predictions proved to be difficult as contrast simulation techniques require further development for analysis to be completed confidently. Another part of this work involves the characterisation of high-angle grain boundaries in zinc oxide (ZnO) using circuit mapping. Two boundaries displayed structural features characteristic of the 'special' category, however, one boundary presented features which did not conform to this model. It is proposed that the latter observation shows a structural transition from the special to a more general type. Material fluxes involved in defect interactions were considered using the topological framework described in this work. A genera) expression was derived for the total flux arising which allows the behaviour of line-defects to be studied in complex interfacial processes. (author)
Boundary layer energies for nonconvex discrete systems
Scardia, L.; Schlömerkemper, A.; Zanini, C.
2011-01-01
In this work we consider a one-dimensional chain of atoms which interact through nearest and next-to-nearest neighbour interactions of Lennard-Jones type. We impose Dirichlet boundary conditions and in addition prescribe the deformation of the second and last but one atoms of the chain. This
Interactions between Dislocations and Grain Boundaries
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
Persistent Identifiers as Boundary Objects
Parsons, M. A.; Fox, P. A.
2017-12-01
In 1989, Leigh Star and Jim Griesemer defined the seminal concept of `boundary objects'. These `objects' are what Latour calls `immutable mobiles' that enable communication and collaboration across difference by helping meaning to be understood in different contexts. As Star notes, they are a sort of arrangement that allow different groups to work together without (a priori) consensus. Part of the idea is to recognize and allow for the `interpretive flexibility' that is central to much of the `constructivist' approach in the sociology of science. Persistent Identifiers (PIDs) can clearly act as boundary objects, but people do not usually assume that they enable interpretive flexibility. After all, they are meant to be unambiguous, machine-interpretable identifiers of defined artifacts. In this paper, we argue that PIDs can fill at least two roles: 1) That of the standardized form, where there is strong agreement on what is being represented and how and 2) that of the idealized type, a more conceptual concept that allows many different representations. We further argue that these seemingly abstract conceptions actually help us implement PIDs more effectively to link data, publications, various other artifacts, and especially people. Considering PIDs as boundary objects can help us address issues such as what level of granularity is necessary for PIDs, what metadata should be directly associated with PIDs, and what purpose is the PID serving (reference, provenance, credit, etc.). In short, sociological theory can improve data sharing standards and their implementation in a way that enables broad interdisciplinary data sharing and reuse. We will illustrate this with several specific examples of Earth science data.
Grain Boundary Segregation in Metals
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.
A physical approach to the numerical treatment of boundaries in gas dynamics
Moretti, G.
1981-01-01
Two types of boundaries are considered: rigid walls, and artificial (open) boundaries which were arbitrarily drawn somewhere across a wider flow field. A set of partial differential equations (typically, the Euler equations) has an infinite number of solutions, each one defined by a set of initial and boundary conditions. The initial conditions remaining the same, any change in the boundary conditions will produce a new solution. To pose the problem well, a necessary and sufficient number of boundary conditions are prescribed.
Reactor pressure boundary materials
International Nuclear Information System (INIS)
Hong, Jun Hwa; Chi, S. H.; Lee, B. S.
2002-04-01
With a long-term operation of nuclear power plants, the component materials are degraded under severe reactor conditions such as neutron irradiation, high temperature, high pressure and corrosive environment. It is necessary to establish the reliable and practical technologies for improving and developing the component materials and for evaluating the mechanical properties. Especially, it is very important to investigate the technologies for reactor pressure boundary materials such as reactor vessel and pipings in accordance with their critical roles. Therefore, this study was focused on developing and advancing the microstructural/micro-mechanical evaluation technologies, and on evaluating the neutron irradiation characteristics and radiation effects analysis technology of the reactor pressure boundary materials, and also on establishing a basis of nuclear material property database
2014-05-01
Cantwell et al. / Acta Materialia 62 (2014) 1–48 challenging from a scientific perspective, but it can also be very technologically rewarding , given the...energy) is a competing explanation that remains to be explored. Strategies to drive the grain boundary energy toward zero have produced some success...Thompson AM, Soni KK, Chan HM, Harmer MP, Williams DB, Chabala JM, et al. J Am Ceram Soc 1997;80:373. [172] Behera SK. PhD dissertation, Materials Science
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.
Spectral asymmetry for bag boundary conditions
International Nuclear Information System (INIS)
Beneventano, C G; Santangelo, E M; Wipf, A
2002-01-01
We give an expression, in terms of boundary spectral functions, for the spectral asymmetry of the Euclidean Dirac operator in two dimensions, when its domain is determined by local boundary conditions and the manifold is of product type. As an application, we explicitly evaluate the asymmetry in the case of a finite-length cylinder and check that the outcome is consistent with our general result. Finally, we study the asymmetry in a disc, which is a non-product case, and propose an interpretation
The Atmospheric Boundary Layer
Garratt, J. R.
1994-05-01
A comprehensive and lucid account of the physics and dynamics of the lowest one to two kilometers of the Earth's atmosphere in direct contact with the Earth's surface, known as the atmospheric boundary layer (ABL). Dr. Garratt emphasizes the application of the ABL problems to numerical modeling of the climate, which makes this book unique among recent texts on the subject. He begins with a brief introduction to the ABL before leading to the development of mean and turbulence equations and the many scaling laws and theories that are the cornerstone of any serious ABL treatment. Modeling of the ABL is crucially dependent for its realism on the surface boundary conditions, so chapters four and five deal with aerodynamic and energy considerations, with attention given to both dry and wet land surfaces and the sea. The author next treats the structure of the clear-sky, thermally stratified ABL, including the convective and stable cases over homogeneous land, the marine ABL, and the internal boundary layer at the coastline. Chapter seven then extends this discussion to the cloudy ABL. This is particularly relevant to current research because the extensive stratocumulus regions over the subtropical oceans and stratus regions over the Arctic have been identified as key players in the climate system. In the final chapters, Dr. Garratt summarizes the book's material by discussing appropriate ABL and surface parameterization schemes in general circulation models of the atmosphere that are being used for climate stimulation.
International Nuclear Information System (INIS)
Zavatsky, S.; Phaneuf, P.; Topaz, D.; Ward, D.
1978-02-01
The NRC Office of Inspection and Enforcement (IE) has elected to evaluate the effectiveness and efficiency of its existing regional boundary alignment because of the anticipated future growth of nuclear power generating facilities and corresponding inspection requirements. This report documents a management study designed to identify, analyze, and evaluate alternative regional boundary configurations for the NRC/IE regions. Eight boundary configurations were chosen for evaluation. These configurations offered alternatives ranging from two to ten regions, and some included the concepts of subregional or satellite offices. Each alternative configuration was evaluated according to three major criteria: project workload, cost, and office location. Each major criterion included elements such as management control, program uniformity, disruption, costs, and coordination with other agencies. The conclusion reached was that regional configurations with regions of equal and relatively large workloads, combined with the concepts of subregional or satellite offices, may offer a significant benefit to the Office of Inspection and Enforcement and the Commission and are worthy of further study. A phased implementation plan, which is suitable to some configurations, may help mitigate the disruption created by realignment
DEFF Research Database (Denmark)
Winthereik, Brit Ross
2008-01-01
Purpose – The paper seeks to examine how an online maternity record involving pregnant women worked as a means to create shared maternity care. Design/methodology/approach – Ethnographic techniques have been used. The paper adopts a theoretical/methodological framework based on science and techno......Purpose – The paper seeks to examine how an online maternity record involving pregnant women worked as a means to create shared maternity care. Design/methodology/approach – Ethnographic techniques have been used. The paper adopts a theoretical/methodological framework based on science...... and technology studies. Findings – The paper shows how a version of “the responsible patient” emerges from the project which is different from the version envisioned by the project organisation. The emerging one is concerned with the boundary between primary and secondary sector care, and not with the boundary......, IT designers and project managers should attend to the specific ways in which boundaries are inevitably enacted and to the ways in which care is already shared. This will provide them with opportunities to use the potentials of new identities and concerns that emerge from changing the organisation...
International Nuclear Information System (INIS)
Moteff, J.
1976-01-01
Ratio of the subgrain boundary dislocations to those contributing to creep deformation was found to be independent of applied stress and creep strain after the steady-state creep stage is reached. The observed cell or subgrain sizes are correlated with flow stress in Type 304 ss, and the deformation rate-stress relation obeys the equation epsilon =β lambda 3 (sigma/sub T//E)/sub n/ exp (-Q/sub c//RT), where lambda = subgrain size, sigma/sub T/ = effective true stress, E = Young modulus, and Q/sub c/ = 85 kcal/mole. Well-developed subgrains were observed in TEM on 304 ss tested in creep at 704 0 C. Role of twin boundary-grain boundary intersections in microcracking behavior of 304 ss deformed in slow tension and creep at 650 0 C was investigated. Grain shape analysis show that intragranular deformation becomes more predominant in the grains with the larger intercept distances, and that grain boundary sliding becomes important as the strain rate decreases. RT mechanical properties of austenitic ss are enhanced by subgrains formed during high-temperature deformation. The substructural development during high-temperature low-cycle fatigue of 304 ss was studied using TEM. Fatigue properties of Incoloy 800 tested in bend and push-pull modes are being compared. Effects of hold time on fatigue substructure and fracture of 304 ss are being studied. 31 figures, 53 references
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...
Cell boundary fault detection system
Archer, Charles Jens [Rochester, MN; Pinnow, Kurt Walter [Rochester, MN; Ratterman, Joseph D [Rochester, MN; Smith, Brian Edward [Rochester, MN
2009-05-05
A method determines a nodal fault along the boundary, or face, of a computing cell. Nodes on adjacent cell boundaries communicate with each other, and the communications are analyzed to determine if a node or connection is faulty.
Boundary scattering in the ϕ{sup 4} model
Energy Technology Data Exchange (ETDEWEB)
Dorey, Patrick [Department of Mathematical Sciences, Durham University,Durham DH1 3LE (United Kingdom); Halavanau, Aliaksei [Department of Theoretical Physics and Astrophysics,BSU, Minsk Independence Avenue 4 (Belarus); Fermi National Laboratory,Pine St. and Kirk Rd., ZIP 60511, Mail Station 221, Batavia, Illinois (United States); Mercer, James [Department of Mathematical Sciences, Durham University,Durham DH1 3LE (United Kingdom); Deloitte MCS Limited,Hill House, 1 Little New Street, London, EC4A 3TR (United Kingdom); Romanczukiewicz, Tomasz [Institute of Physics, Jagiellonian University,Lojasiewicza 11, 30-348 Krakow (Poland); Shnir, Yasha [Department of Theoretical Physics and Astrophysics,BSU, Minsk Independence Avenue 4 (Belarus); BLTP, JINR,141980 Dubna (Russian Federation); Institute of Physics, Oldenburg University,Postfach 2503 D-26111 Oldenburg (Germany)
2017-05-19
We study boundary scattering in the ϕ{sup 4} model on a half-line with a one-parameter family of Neumann-type boundary conditions. A rich variety of phenomena is observed, which extends previously-studied behaviour on the full line to include regimes of near-elastic scattering, the restoration of a missing scattering window, and the creation of a kink or oscillon through the collision-induced decay of a metastable boundary state. We also study the decay of the vibrational boundary mode, and explore different scenarios for its relaxation and for the creation of kinks.
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...... uncertain than low-entropy contexts. Because phrase boundaries tend to afford high-entropy continuations, thus generating uncertain expectations in the listener, one possibility is that boundary perception is directly related to entropy. In other words, it may be hypothesized that entropy underlies...... on predictive uncertainty to the timing domain, as well as potentially answer key questions relating to boundary perception in musical listening....
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.)
Dynamical simulation of structural multiplicity in grain boundaries
International Nuclear Information System (INIS)
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 Σ = 5 36.87 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 Σ = 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
International Nuclear Information System (INIS)
Ohyabu, N.
1995-05-01
We have proposed a new boundary control scheme (SHC boundary), which could allow simultaneous achievement of the H-mode type confinement improvement and radiative cooling with wide heat flux distribution. In our proposed configuration, a low m island layer sharply separates a plasma confining region from an open 'ergodic' boundary. The degree of openness in the ergodic boundary must be high enough to make the plasma pressure constant along the field line, which in turn separates low density plasma just outside the plasma confining region (the key external condition for achieving a good H-mode discharge) from very high density, cold radiative plasma near the wall (required for effective edge radiative cooling). Examples of such proposed SHC boundaries for Heliotron typed devices and tokamaks are presented. (author)
DEFF Research Database (Denmark)
Nørgaard, Nina
2004-01-01
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...... 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...
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...
Transcending Organizational Boundaries
DEFF Research Database (Denmark)
Kringelum, Louise Tina Brøns
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......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...... the roles of port authorities evolve. This contribution is made by combining the two fields, where the study of business model innovation is used as an analytical concept for understanding the evolution of port authorities, and where the study of port authorities is used as a contextual setting...
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.
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
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
International Nuclear Information System (INIS)
Nishimura, M.
1998-04-01
To predict thermal-hydraulic phenomena in actual plant under various conditions accurately, adequate simulation of laminar-turbulent flow transition is of importance. A low Reynolds number turbulence model is commonly used for a numerical simulation of the laminar-turbulent transition. The existing low Reynolds number turbulence models generally demands very thin mesh width between a wall and a first computational node from the wall, to keep accuracy and stability of numerical analyses. There is a criterion for the distance between the wall and the first computational node in which non-dimensional distance y + must be less than 0.5. Due to this criterion the suitable distance depends on Reynolds number. A liquid metal sodium is used for a coolant in first reactors therefore, Reynolds number is usually one or two order higher than that of the usual plants in which air and water are used for the work fluid. This makes the load of thermal-hydraulic numerical simulation of the liquid sodium relatively heavier. From above context, a new method is proposed for providing wall boundary condition of turbulent kinetic energy dissipation rate ε. The present method enables the wall-first node distance 10 times larger compared to the existing models. A function of the ε wall boundary condition has been constructed aided by a direct numerical simulation (DNS) data base. The method was validated through calculations of a turbulent Couette flow and a fully developed pipe flow and its laminar-turbulent transition. Thus the present method and modeling are capable of predicting the laminar-turbulent transition with less mesh numbers i.e. lighter computational loads. (J.P.N.)
Computation of airfoil buffet boundaries
Levy, L. L., Jr.; Bailey, H. E.
1981-01-01
The ILLIAC IV computer has been programmed with an implicit, finite-difference code for solving the thin layer compressible Navier-Stokes equation. Results presented for the case of the buffet boundaries of a conventional and a supercritical airfoil section at high Reynolds numbers are found to be in agreement with experimentally determined buffet boundaries, especially at the higher freestream Mach numbers and lower lift coefficients where the onset of unsteady flows is associated with shock wave-induced boundary layer separation.
Boundary fluxes for nonlocal diffusion
Cortazar, Carmen; Elgueta, Manuel; Rossi, Julio D.; Wolanski, Noemi
We study a nonlocal diffusion operator in a bounded smooth domain prescribing the flux through the boundary. This problem may be seen as a generalization of the usual Neumann problem for the heat equation. First, we prove existence, uniqueness and a comparison principle. Next, we study the behavior of solutions for some prescribed boundary data including blowing up ones. Finally, we look at a nonlinear flux boundary condition.
Diversified boundaries of the firm
Kimura, Koichiro
2012-01-01
We analyze diversification of boundaries of local firms in developing countries under the economic globalization. The globalization has an aspect of homogenization of the world economy, but also has another aspect of diversification through international economic activities. Focusing on boundary-level of the firm, this article shows that the diversification from a comparison with boundaries of foreign firms in developed countries is brought by a disadvantage of technology deficit and a home a...
Analysis of turbulent boundary layers
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
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.
Constraint-preserving boundary treatment for a harmonic formulation of the Einstein equations
Energy Technology Data Exchange (ETDEWEB)
Seiler, Jennifer; Szilagyi, Bela; Pollney, Denis; Rezzolla, Luciano [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Golm (Germany)
2008-09-07
We present a set of well-posed constraint-preserving boundary conditions for a first-order in time, second-order in space, harmonic formulation of the Einstein equations. The boundary conditions are tested using robust stability, linear and nonlinear waves, and are found to be both less reflective and constraint preserving than standard Sommerfeld-type boundary conditions.
Constraint-preserving boundary treatment for a harmonic formulation of the Einstein equations
International Nuclear Information System (INIS)
Seiler, Jennifer; Szilagyi, Bela; Pollney, Denis; Rezzolla, Luciano
2008-01-01
We present a set of well-posed constraint-preserving boundary conditions for a first-order in time, second-order in space, harmonic formulation of the Einstein equations. The boundary conditions are tested using robust stability, linear and nonlinear waves, and are found to be both less reflective and constraint preserving than standard Sommerfeld-type boundary conditions
Dirac-like operators on the Hilbert space of differential forms on manifolds with boundaries
Pérez-Pardo, Juan Manuel
The problem of self-adjoint extensions of Dirac-type operators in manifolds with boundaries is analyzed. The boundaries might be regular or non-regular. The latter situation includes point-like interactions, also called delta-like potentials, in manifolds of dimension higher than one. Self-adjoint boundary conditions for the case of dimension 2 are obtained explicitly.
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...
African boundary politics: a case of Ethiopian-Eritrean boundary ...
African Journals Online (AJOL)
This paper examined the boundary discord between Ethiopia and Eritrea over the region around Badme which started as a result of artificial boundaries created by the Italian imperialists. The study depicts the evolution of Italian colonialism in Ethiopia between 1936 and 1941. It exposes the differentials existing between the ...
Diffusion processes in the magnetopause boundary layer
International Nuclear Information System (INIS)
Tsurutani, B.T.; Thorne, R.M.
1982-01-01
Anomalous cross-field diffusion of magnetosheath ions and electrons is a direct consequence of cyclotron-resonant scattering by electrostatic and electromagnetic emissions which are continuously present within the magnetopause boundary layer. Expressions for the rate of cross-field diffusion involving either type of wave are developed and expressed in terms of the absolute upper limit referred to as Bohm diffusion. For the typical average intensity of waves observed in the boundary layer, resonant electron cross-field diffusion is always insignificant. However, magnetosheath ions, resonant with low frequency electrostatic waves, may be transported inward at a rate approaching one tenth the Bohm rate (D/sub perpendiculartsperpendicular/roughly-equal10 3 km 2 /s). While this is not the only mechanism capable of explaining the presence of the low latitude boundary layer it is adequate to account for the typical boundary layer thickness and it should occur at all local times and under all interplanetary conditions. It consequently provides a continuous mechanism for significant mass and momentum transfer across the magnetopause under conditions when field merging is inoperative
Diamagnetic boundary layers: a kinetic theory
International Nuclear Information System (INIS)
Lemaire, J.; Burlaga, L.F.
1976-01-01
A kinetic theory for boundary layers associated with MHD tangential 'discontinuities' in a collisionless magnetized plasma such as those observed in the solar wind is presented. The theory consists of finding self-consistent solutions of Vlasov's equation and Maxwell's equation for stationary, one-dimensional boundary layers separating two Maxwellian plasma states. Layers in which the current is carried by electrons are found to have a thickness of the order of a few electron gyroradii, but the drift speed of the current-carrying electrons is found to exceed the Alfven speed, and accordingly such layers are not stable. Several types of layers, in which the current is carried by protons are discussed; in particular, cases in which the magnetic field intensity and/or direction changed across the layer were considered. In every case, the thickness was of the order of a few proton gyroradii and the field changed smoothly , although the characteristics depended somewhat on the boundary conditions. The drift speed was always less than the Alfven speed, consistent with stability of such structures. The results are consistent with the observations of boundary layers in the solar wind near 1 AU. (Auth.)
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
Boundary methods for mode estimation
Pierson, William E., Jr.; Ulug, Batuhan; Ahalt, Stanley C.
1999-08-01
This paper investigates the use of Boundary Methods (BMs), a collection of tools used for distribution analysis, as a method for estimating the number of modes associated with a given data set. Model order information of this type is required by several pattern recognition applications. The BM technique provides a novel approach to this parameter estimation problem and is comparable in terms of both accuracy and computations to other popular mode estimation techniques currently found in the literature and automatic target recognition applications. This paper explains the methodology used in the BM approach to mode estimation. Also, this paper quickly reviews other common mode estimation techniques and describes the empirical investigation used to explore the relationship of the BM technique to other mode estimation techniques. Specifically, the accuracy and computational efficiency of the BM technique are compared quantitatively to the a mixture of Gaussian (MOG) approach and a k-means approach to model order estimation. The stopping criteria of the MOG and k-means techniques is the Akaike Information Criteria (AIC).
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...
Cell boundary fault detection system
Archer, Charles Jens [Rochester, MN; Pinnow, Kurt Walter [Rochester, MN; Ratterman, Joseph D [Rochester, MN; Smith, Brian Edward [Rochester, MN
2011-04-19
An apparatus and program product determine a nodal fault along the boundary, or face, of a computing cell. Nodes on adjacent cell boundaries communicate with each other, and the communications are analyzed to determine if a node or connection is faulty.
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...
Yao, Zhuo-sen; Qin, Ke-zhang; Xue, Sheng-chao
2017-12-01
The deformation features (e.g., undulose extinction and subgrain boundaries) and low Ca content (causing the widespread deformation observed in Ca-depleted olivine from Poyi and other intrusions. What is more important, this work fills the gaps in the interpretation of this type of olivine in volcanic rocks.
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...
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......) and it is found that to a large extent the dislocations screen each other’s elastic stress fields [3]. The present contribution aims at advancing the previous theoretical analysis of a boundary on a known crystallographic plane to actual prediction of this plane as well as other boundary characteristics....... 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...
Energy Technology Data Exchange (ETDEWEB)
Shibata, T.; Hasegawa, Y. [Tohoku Univ., Sendai (Japan)
2010-07-01
Grain boundary precipitation strengthening is expected to be a decisive factor in developing ferritic creep resistant steels. This study examined the grain boundary precipitation strengthening mechanism extracting the effect of the tempered martensitic microstructure and precipitates on the high angle grain boundary in M{sub 23}C4{sub 6} type carbide and the Fe{sub 2}W type Laves phase effect of the creep deformation fixing the grain boundary according to transmission electron microscope (TEM) observation. A creep test was carried out at high temperature in order to evaluate the high angle boundary strengthening effect simulating the long-term creep deformation microstructure by the lath structure disappearance. The correlation of the creep rupture time and the grain boundary shielding ratio were found to be independent of precipitate type. The creep deformation model represents block boundary shielding by precipitates as the decisive factor for W containing ferritic creep resistant steels. (orig.)
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.
Subgroup report on grain boundary and interphase boundary structure and properties
International Nuclear Information System (INIS)
Balluffi, R.W.; Cannon, R.M.; Clarke, D.R.; Heuer, A.H.; Ho, P.S.; Kear, B.H.; Vitek, V.; Weertman, J.R.; White, C.L.
1979-01-01
In many high temperature structural applications, the performance characteristics of a materials system are largely controlled by the properties of its grain and interphase boundaries. Failure in creep and fatigue frequently occurs by cavitation, or cracking along grain boundaries. In a few special cases, this failure problem has been overcome by directional alignment of grain and interphase boundaries by various types of metallurgical processing such as directional solidification and directional recrystallization. A good example is to be found in the application of directionally aligned structures in high performance gas-turbine airfoils. However, where fine, equiaxed grain structures are desirable, other methods of controlling grain boundary properties have been developed. Important among these has been the introduction of improvements in primary melting practices, designed to control important impurities. This is of decisive importance because even traces of certain impurity elements present in grain boundaries in high temperature materials can seriously affect properties. Impurities are deleterious and need to be removed. However, in certain cases, (e.g., creep fracture) controlled impurity additions can be beneficial and result in improved properties
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.
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.
Boundaries, transitions and passages
Koenderink, Jan; van Doorn, Andrea J.; Pinna, Baingio; Wagemans, Johan
2016-01-01
Many pictures are approximately piecewise uniform quilts. The patches meet in transitional areas that have a vague, ribbon-like geometry. These borders may occasionally get lost and sometimes pick up again, creating a 'passage' that partly blends adjacent patches. This type of structure is widely
Grain boundary precipitation in an austenitic stainless steel
International Nuclear Information System (INIS)
Jones, A.R.; Howell, P.R.; Ralph, B.
The precipitation of second phase particles of niobium carbide in an austenitic stainless steel is shown to be considerably influenced by the degree of deformation introduced prior to the ageing treatment. Sites for the nucleation of second phase particles are identified and the importance of one type of nucleation site, extrinsic dislocations, to the evolution of the final boundary precipitate distributions is emphasized. Further, it is shown that the presence of a grain boundary can effect precipitation processes for some considerable distance into the matrix on either side of the boundary. (author)
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.
A finite difference method for free boundary problems
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.
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.)
Optimal boundary control and boundary stabilization of hyperbolic systems
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.
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...
Easy boundary definition for EGUN
International Nuclear Information System (INIS)
Becker, R.
1989-01-01
The relativistic electron optics program EGUN has reached a broad distribution, and many users have asked for an easier way of boundary input. A preprocessor to EGUN has been developed that accepts polygonal input of boundary points, and offers features such as rounding off of corners, shifting and squeezing of electrodes and simple input of slanted Neumann boundaries. This preprocessor can either be used on a PC that is linked to a mainframe using the FORTRAN version of EGUN, or in connection with the version EGNc, which also runs on a PC. In any case, direct graphic response on the PC greatly facilitates the creation of correct input files for EGUN. (orig.)
Easy boundary definition for EGUN
Becker, R.
1989-06-01
The relativistic electron optics program EGUN [1] has reached a broad distribution, and many users have asked for an easier way of boundary input. A preprocessor to EGUN has been developed that accepts polygonal input of boundary points, and offers features such as rounding off of corners, shifting and squeezing of electrodes and simple input of slanted Neumann boundaries. This preprocessor can either be used on a PC that is linked to a mainframe using the FORTRAN version of EGUN, or in connection with the version EGNc, which also runs on a PC. In any case, direct graphic response on the PC greatly facilitates the creation of correct input files for EGUN.
Easy boundary definition for EGUN
Energy Technology Data Exchange (ETDEWEB)
Becker, R. (Frankfurt Univ. (Germany, F.R.). Inst. fuer Angewandte Physik)
1989-06-01
The relativistic electron optics program EGUN has reached a broad distribution, and many users have asked for an easier way of boundary input. A preprocessor to EGUN has been developed that accepts polygonal input of boundary points, and offers features such as rounding off of corners, shifting and squeezing of electrodes and simple input of slanted Neumann boundaries. This preprocessor can either be used on a PC that is linked to a mainframe using the FORTRAN version of EGUN, or in connection with the version EGNc, which also runs on a PC. In any case, direct graphic response on the PC greatly facilitates the creation of correct input files for EGUN. (orig.).
Allegheny County Zip Code Boundaries
Allegheny County / City of Pittsburgh / Western PA Regional Data Center — This dataset demarcates the zip code boundaries that lie within Allegheny County.If viewing this description on the Western Pennsylvania Regional Data Center’s open...
Allegheny County School District Boundaries
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...
Sublayer of Prandtl Boundary Layers
Grenier, Emmanuel; Nguyen, Toan T.
2018-03-01
The aim of this paper is to investigate the stability of Prandtl boundary layers in the vanishing viscosity limit {ν \\to 0} . In Grenier (Commun Pure Appl Math 53(9):1067-1091, 2000), one of the authors proved that there exists no asymptotic expansion involving one of Prandtl's boundary layer, with thickness of order {√{ν}} , which describes the inviscid limit of Navier-Stokes equations. The instability gives rise to a viscous boundary sublayer whose thickness is of order {ν^{3/4}} . In this paper, we point out how the stability of the classical Prandtl's layer is linked to the stability of this sublayer. In particular, we prove that the two layers cannot both be nonlinearly stable in L^∞. That is, either the Prandtl's layer or the boundary sublayer is nonlinearly unstable in the sup norm.
Boundary Layer Control on Airfoils.
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)
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 stabili...... stabilizability. It is shown that it is possible to use the calculus to consider more general feedback systems in a variational setup.......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...
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...
Analytic invariants of boundary links
Garoufalidis, Stavros; Levine, Jerome
2001-01-01
Using basic topology and linear algebra, we define a plethora of invariants of boundary links whose values are power series with noncommuting variables. These turn out to be useful and elementary reformulations of an invariant originally defined by M. Farber.
County Boundaries with Shorelines (National)
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...
The laminar boundary layer equations
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.
Discussion of boundary-layer characteristics near the casing of an axial-flow compressor
Mager, Artur; Mahoney, John J; Budinger, Ray E
1951-01-01
Boundary-layer velocity profiles on the casing of an axial-flow compressor behind the guide vanes and rotor were measured and resolved into two components: along the streamline of the flow and perpendicular to it. Boundary-layer thickness and the deflection of the boundary layer at the wall were the generalizing parameters. By use of these results and the momentum-integral equations, the characteristics of boundary on the walls of axial-flow compressor are qualitatively discussed. Important parameters concerning secondary flow in the boundary layer appear to be turning of the flow and the product of boundary-layer thickness and streamline curvature outside the boundary layer. Two types of separation are shown to be possible in three dimensional boundary layer.
Grain boundary structure and properties
International Nuclear Information System (INIS)
Balluffi, R.W.
1979-05-01
An attempt is made to distinguish those fundamental aspects of grain boundaries which should be relevant to the problem of the time dependent fracture of high temperature structural materials. These include the basic phenomena which are thought to be associated with cavitation and cracking at grain boundaries during service and with the more general microstructural changes which occur during both processing and service. A very brief discussion of the current state of knowledge of these fundamentals is given
Directory of Open Access Journals (Sweden)
Damir Josipovič
2012-06-01
Full Text Available Boundary-making in Istria is an old undertaking. It has actually never ceasesed, not even today. Istrian peninsula has thus undergone substantial boundary shifts during the last couple of centuries (especially after the Venetian demise in 1797. But Istria carries its worldwide fame also due to one of probably the harshest disputes on the post-war European grounds – the Trieste territory dispute. In author's perspective, this dispute is one of the four main corner-stones of the current Slovenian-Croatian boundary dispute. The remaining three include the Kozler's boundary around Dragonja (Rokava River, the ungraspable notions of Austrian censuses in Istria, and the narratives of partisan settlements on military jurisdiction. However, there are other very important aspects which significantly shaped the development of the dispute, but we will focus at assessing the importance of the aforementioned ones. In this sense, the analysis of the effects of the outcome of the Trieste dispute and its implications to the contemporary interstate dispute is set forth. By unveiling its material and consequently its psychological effects upon the contemporary bilateral relations, its analyses simultaneously reveals backgrounds of never answered question, why Kozler's proposed linguistic boundary around Dragonja (Rokava River turned out to become a boundary of national character. Though nowadays disputed, there is absolutely no chance for both involved parties to substantially draw away from once decisively drawn line of a layman. Despite the fierce battle of words in Slovenian public media on whether should the interstate boundary be placed on Mirna (Quieto or Dragonja Rivers, it will be argued here that the actual choice of the Valley of Dragonja as a boundary is by all means Slovenian. The arguments are based on extensive analyses of cartographic materials, relevant literature, documents, and statistical data.
Directory of Open Access Journals (Sweden)
Damir Josipovič
2012-01-01
Full Text Available Boundary-making in Istria is an old undertaking. It has actually never ceasesed, not even today. Istrian peninsula has thus undergone substantial boundary shifts during the last couple of centuries (especially after the Venetian demise in 1797. But Istria carries its worldwide fame also due to one of probably the harshest disputes on the post-war European grounds – the Trieste territory dispute. In author's perspective, this dispute is one of the four main corner-stones of the current Slovenian-Croatian boundary dispute. The remaining three include the Kozler's boundary around Dragonja (Rokava River, the ungraspable notions of Austrian censuses in Istria, and the narratives of partisan settlements on military jurisdiction. However, there are other very important aspects which significantly shaped the development of the dispute, but we will focus at assessing the importance of the aforementioned ones. In this sense, the analysis of the effects of the outcome of the Trieste dispute and its implications to the contemporary interstate dispute is set forth. By unveiling its material and consequently its psychological effects upon the contemporary bilateral relations, its analyses simultaneously reveals backgrounds of never answered question, why Kozler's proposed linguistic boundary around Dragonja (Rokava River turned out to become a boundary of national character. Though nowadays disputed, there is absolutely no chance for both involved parties to substantially draw away from once decisively drawn line of a layman. Despite the fierce battle of words in Slovenian public media on whether should the interstate boundary be placed on Mirna (Quieto or Dragonja Rivers, it will be argued here that the actual choice of the Valley of Dragonja as a boundary is by all means Slovenian. The arguments are based on extensive analyses of cartographic materials, relevant literature, documents, and statistical data.
Removing Boundary Layer by Suction
Ackeret, J
1927-01-01
Through the utilization of the "Magnus effect" on the Flettner rotor ship, the attention of the public has been directed to the underlying physical principle. It has been found that the Prandtl boundary-layer theory furnishes a satisfactory explanation of the observed phenomena. The present article deals with the prevention of this separation or detachment of the flow by drawing the boundary layer into the inside of a body through a slot or slots in its surface.
Tokamak plasma boundary layer model
International Nuclear Information System (INIS)
Volkov, T.F.; Kirillov, V.D.
1983-01-01
A model has been developed for the limiter layer and for the boundary region of the plasma column in a tokamak to facilitate analytic calculations of the thickness of the limiter layers, the profiles and boundary values of the temperature and the density under various conditions, and the difference between the electron and ion temperatures. This model can also be used to analyze the recycling of neutrals, the energy and particle losses to the wall and the limiter, and other characteristics
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...
On the elastic stiffness of grain boundaries
International Nuclear Information System (INIS)
Zhang Tongyi; Hack, J.E.
1992-01-01
The elastic softening of grain boundaries is evaluated from the starting point of grain boundary energy. Several examples are given to illustrate the relationship between boundary energy and the extent of softening. In general, a high grain boundary energy is associated with a large excess atomic volume in the boundary region. The consequent reduction in grain boundary stiffness can represent a significant fraction of that observed in bulk crystals. (orig.)
Identifying deformation mechanisms in the NEEM ice core using EBSD measurements
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
Quantum effective action in spacetimes with branes and boundaries
International Nuclear Information System (INIS)
Barvinsky, A.O.; Nesterov, D.V.
2006-01-01
We construct quantum effective action in spacetime with branes/boundaries. This construction is based on the reduction of the underlying Neumann type boundary value problem for the propagator of the theory to that of the much more manageable Dirichlet problem. In its turn, this reduction follows from the recently suggested Neumann-Dirichlet duality which we extend beyond the tree-level approximation. In the one-loop approximation this duality suggests that the functional determinant of the differential operator subject to Neumann boundary conditions factorizes into the product of its Dirichlet counterpart and the functional determinant of a special operator on the brane--the inverse of the brane-to-brane propagator. As a byproduct of this relation we suggest a new method for surface terms of the heat kernel expansion. This method allows one to circumvent well-known difficulties in the heat kernel theory on manifolds with boundaries for a wide class of generalized Neumann boundary conditions. In particular, we easily recover several lowest-order surface terms in the case of Robin and oblique boundary onditions. We briefly discuss multiloop applications of the suggested Dirichlet reduction and the prospects of constructing the universal background-field method for systems with branes/boundaries, analogous to the Schwinger-DeWitt technique
Spark formation as a moving boundary process
Ebert, Ute
2006-03-01
The growth process of spark channels recently becomes accessible through complementary methods. First, I will review experiments with nanosecond photographic resolution and with fast and well defined power supplies that appropriately resolve the dynamics of electric breakdown [1]. Second, I will discuss the elementary physical processes as well as present computations of spark growth and branching with adaptive grid refinement [2]. These computations resolve three well separated scales of the process that emerge dynamically. Third, this scale separation motivates a hierarchy of models on different length scales. In particular, I will discuss a moving boundary approximation for the ionization fronts that generate the conducting channel. The resulting moving boundary problem shows strong similarities with classical viscous fingering. For viscous fingering, it is known that the simplest model forms unphysical cusps within finite time that are suppressed by a regularizing condition on the moving boundary. For ionization fronts, we derive a new condition on the moving boundary of mixed Dirichlet-Neumann type (φ=ɛnφ) that indeed regularizes all structures investigated so far. In particular, we present compact analytical solutions with regularization, both for uniformly translating shapes and for their linear perturbations [3]. These solutions are so simple that they may acquire a paradigmatic role in the future. Within linear perturbation theory, they explicitly show the convective stabilization of a curved front while planar fronts are linearly unstable against perturbations of arbitrary wave length. [1] T.M.P. Briels, E.M. van Veldhuizen, U. Ebert, TU Eindhoven. [2] C. Montijn, J. Wackers, W. Hundsdorfer, U. Ebert, CWI Amsterdam. [3] B. Meulenbroek, U. Ebert, L. Schäfer, Phys. Rev. Lett. 95, 195004 (2005).
On the Boussinesq-Burgers equations driven by dynamic boundary conditions
Zhu, Neng; Liu, Zhengrong; Zhao, Kun
2018-02-01
We study the qualitative behavior of the Boussinesq-Burgers equations on a finite interval subject to the Dirichlet type dynamic boundary conditions. Assuming H1 ×H2 initial data which are compatible with boundary conditions and utilizing energy methods, we show that under appropriate conditions on the dynamic boundary data, there exist unique global-in-time solutions to the initial-boundary value problem, and the solutions converge to the boundary data as time goes to infinity, regardless of the magnitude of the initial data.
EBSD in Antarctic and Greenland Ice
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
Solution of moving boundary problems with implicit boundary condition
International Nuclear Information System (INIS)
Moyano, E.A.
1990-01-01
An algorithm that solves numerically a model for studying one dimensional moving boundary problems, with implicit boundary condition, is described. Landau's transformation is used, in order to work with a fixed number of nodes at each instant. Then, it is necessary to deal with a parabolic partial differential equation, whose diffusive and convective terms have variable coefficients. The partial differential equation is implicitly discretized, using Laasonen's scheme, always stable, instead of employing Crank-Nicholson sheme, as it has been done by Ferris and Hill. Fixed time and space steps (Δt, Δξ) are used, and the iteration is made with variable positions of the interface, i.e. varying δs until a boundary condition is satisfied. The model has the same features of the oxygen diffusion in absorbing tissue. It would be capable of estimating time variant radiation treatments of cancerous tumors. (Author) [es
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 �...
Event boundaries and anaphoric reference.
Thompson, Alexis N; Radvansky, Gabriel A
2016-06-01
The current study explored the finding that parsing a narrative into separate events impairs anaphor resolution. According to the Event Horizon Model, when a narrative event boundary is encountered, a new event model is created. Information associated with the prior event model is removed from working memory. So long as the event model containing the anaphor referent is currently being processed, this information should still be available when there is no narrative event boundary, even if reading has been disrupted by a working-memory-clearing distractor task. In those cases, readers may reactivate their prior event model, and anaphor resolution would not be affected. Alternatively, comprehension may not be as event oriented as this account suggests. Instead, any disruption of the contents of working memory during comprehension, event related or not, may be sufficient to disrupt anaphor resolution. In this case, reading comprehension would be more strongly guided by other, more basic language processing mechanisms and the event structure of the described events would play a more minor role. In the current experiments, participants were given stories to read in which we included, between the anaphor and its referent, either the presence of a narrative event boundary (Experiment 1) or a narrative event boundary along with a working-memory-clearing distractor task (Experiment 2). The results showed that anaphor resolution was affected by narrative event boundaries but not by a working-memory-clearing distractor task. This is interpreted as being consistent with the Event Horizon Model of event cognition.
Asymptotic analysis and boundary layers
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...
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 ...
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....
Critical effects of downstream boundary conditions on vortex breakdown
Kandil, Osama; Kandil, Hamdy A.; Liu, C. H.
1992-01-01
The unsteady, compressible, full Navier-Stokes (NS) equations are used to study the critical effects of the downstream boundary conditions on the supersonic vortex breakdown. The present study is applied to two supersonic vortex breakdown cases. In the first case, quasi-axisymmetric supersonic swirling flow is considered in a configured circular duct, and in the second case, quasi-axisymmetric supersonic swirling jet, that is issued from a nozzle into a supersonic jet of lower Mach number, is considered. For the configured duct flow, four different types of downstream boundary conditions are used, and for the swirling jet flow from the nozzle, two types of downstream boundary conditions are used. The solutions are time accurate which are obtained using an implicit, upwind, flux-difference splitting, finite-volume scheme.
Coupling the Gaussian Free Fields with Free and with Zero Boundary Conditions via Common Level Lines
Qian, Wei; Werner, Wendelin
2018-06-01
We point out a new simple way to couple the Gaussian Free Field (GFF) with free boundary conditions in a two-dimensional domain with the GFF with zero boundary conditions in the same domain: Starting from the latter, one just has to sample at random all the signs of the height gaps on its boundary-touching zero-level lines (these signs are alternating for the zero-boundary GFF) in order to obtain a free boundary GFF. Constructions and couplings of the free boundary GFF and its level lines via soups of reflected Brownian loops and their clusters are also discussed. Such considerations show for instance that in a domain with an axis of symmetry, if one looks at the overlay of a single usual Conformal Loop Ensemble CLE3 with its own symmetric image, one obtains the CLE4-type collection of level lines of a GFF with mixed zero/free boundary conditions in the half-domain.
Humor styles and symbolic boundaries
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
DEFF Research Database (Denmark)
Bødker, Susanne
This position paper takes its starting point in the definitions of work, and of boundaries often found in CSCW and HCI literature. By looking back at the case of parental leave planning and on my writings from the past 10 years, I discuss how these definitions need to be reconsidered, and I...
Dynamics of Coronal Hole Boundaries
Energy Technology Data Exchange (ETDEWEB)
Higginson, A. K.; Zurbuchen, T. H. [Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Antiochos, S. K.; DeVore, C. R. [Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Wyper, P. F. [Universities Space Research Association, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States)
2017-03-10
Remote and in situ observations strongly imply that the slow solar wind consists of plasma from the hot, closed-field corona that is released onto open magnetic field lines. The Separatrix Web theory for the slow wind proposes that photospheric motions at the scale of supergranules are responsible for generating dynamics at coronal-hole boundaries, which result in the closed plasma release. We use three-dimensional magnetohydrodynamic simulations to determine the effect of photospheric flows on the open and closed magnetic flux of a model corona with a dipole magnetic field and an isothermal solar wind. A rotational surface motion is used to approximate photospheric supergranular driving and is applied at the boundary between the coronal hole and helmet streamer. The resulting dynamics consist primarily of prolific and efficient interchange reconnection between open and closed flux. The magnetic flux near the coronal-hole boundary experiences multiple interchange events, with some flux interchanging over 50 times in one day. Additionally, we find that the interchange reconnection occurs all along the coronal-hole boundary and even produces a lasting change in magnetic-field connectivity in regions that were not driven by the applied motions. Our results show that these dynamics should be ubiquitous in the Sun and heliosphere. We discuss the implications of our simulations for understanding the observed properties of the slow solar wind, with particular focus on the global-scale consequences of interchange reconnection.
Current Sinkhole Boundaries in Iowa
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...
Science beyond the Classroom Boundaries
Feasey, Rosemary; Bianchi, Lynne
2011-01-01
There have been many years of innovation in primary science education. Surprisingly, however, most of this has taken place within the confines of the classroom. What primary science has not yet done with universal success is step outside the classroom boundaries to use the school grounds for teaching and learning across all aspects of the science…
Benthic boundary layer modelling studies
International Nuclear Information System (INIS)
Richards, K.J.
1984-01-01
A numerical model has been developed to study the factors which control the height of the benthic boundary layer in the deep ocean and the dispersion of a tracer within and directly above the layer. This report covers tracer clouds of horizontal scales of 10 to 100 km. The dispersion of a tracer has been studied in two ways. Firstly, a number of particles have been introduced into the flow. The trajectories of these particles provide information on dispersion rates. For flow conditions similar to those observed in the abyssal N.E. Atlantic the diffusivity of a tracer was found to be 5 x 10 6 cm 2 s -1 for a tracer within the boundary layer and 8 x 10 6 cm 2 s -1 for a tracer above the boundary layer. The results are in accord with estimates made from current meter measurements. The second method of studying dispersion was to calculate the evolution of individual tracer clouds. Clouds within and above the benthic boundary layer often show quite different behaviour from each other although the general structure of the clouds in the two regions were found to have no significant differences. (author)
A Novel Mesh Quality Improvement Method for Boundary Elements
Directory of Open Access Journals (Sweden)
Hou-lin Liu
2012-01-01
Full Text Available In order to improve the boundary mesh quality while maintaining the essential characteristics of discrete surfaces, a new approach combining optimization-based smoothing and topology optimization is developed. The smoothing objective function is modified, in which two functions denoting boundary and interior quality, respectively, and a weight coefficient controlling boundary quality are taken into account. In addition, the existing smoothing algorithm can improve the mesh quality only by repositioning vertices of the interior mesh. Without destroying boundary conformity, bad elements with all their vertices on the boundary cannot be eliminated. Then, topology optimization is employed, and those elements are converted into other types of elements whose quality can be improved by smoothing. The practical application shows that the worst elements can be eliminated and, with the increase of weight coefficient, the average quality of boundary mesh can also be improved. Results obtained with the combined approach are compared with some common approach. It is clearly shown that it performs better than the existing approach.
Changes in grain boundary composition induced by neutron irradiation of austenitic stainless steels
International Nuclear Information System (INIS)
Asano, K.; Nakata, K.; Fukuya, K.; Kodama, M.
1992-01-01
The radiation induced segregation of solutes to the grain boundary in austenitic stainless steels were studied. Type 304 and type 316 steel samples neutron irradiated at 561K up to 9.2x10 25 n/m 2 were obtained and minute compositional profiles across grain boundaries were examined using an analytical scanning transmission electron microscope equipped with a field emission electron gun. Chromium was slightly enriched at grain boundaries at the lowest irradiation dose but decreased with increasing fluence. Higher fluence irradiation resulted in depletion in chromium and molybdenum, and enrichment in nickel, silicon and phosphorus. These changes in grain boundary chemistry were limited within about 5nm of the boundary. Significant depletion of chromium and enrichment of impurities on the grain boundary occurred at fluences roughly coincidental with that of SCC susceptibility change obtained from another project
Initializing a Mesoscale Boundary-Layer Model with Radiosonde Observations
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.
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...... of homogeneous distributions, tensor products and halfspace extensions have been revised. Examples include the von Karman equation....
Open membranes in a constant C-field background and noncommutative boundary strings
International Nuclear Information System (INIS)
Kawamoto, Shoichi; Sasakura, Naoki
2000-01-01
We investigate the dynamics of open membrane boundaries in a constant C-field background. We follow the analysis for open strings in a B-field background, and take some approximations. We find that open membrane boundaries do show noncommutativity in this case by explicit calculations. Membrane boundaries are one dimensional strings, so we face a new type of noncommutativity, that is, noncommutative strings. (author)
The influence of boundary features on grassland-edge communities of Alta Murgia
Cassano, Stefania; Alignier, Audrey; Forte, Luigi; Labadessa, Rocco; Mairota, Paola
2016-01-01
Many studies suggest the importance of boundary features on plant community dynamics. Our aim was to investigate the influence of boundary features on edge plant assemblages in semi-natural dry grasslands. For this purpose we selected 16 grassland edges in the central portion of the Natura 2000 site Murgia Alta, in southeastern Italy. These sites were selected according to a combination of boundary features, i.e. the adjoining land use type (road or cereal crop), slope (grassland tilted towar...
Contrasting Boundary Scavenging in two Eastern Boundary Current Regimes
Anderson, R. F.; Fleisher, M. Q.; Pavia, F. J.; Vivancos, S. M.; Lu, Y.; Zhang, P.; Cheng, H.; Edwards, R. L.
2016-02-01
We use data from two US GEOTRACES expeditions to compare boundary scavenging intensity in two eastern boundary current systems: the Canary Current off Mauritania and the Humboldt Current off Peru. Boundary scavenging refers to the enhanced removal of trace elements from the ocean by sorption to sinking particles in regions of greater than average particle abundance. Both regimes experience high rates of biological productivity and generation of biogenic particles, with rates of productivity potentially a little greater off Peru, whereas dust fluxes are an order of magnitude greater off NW Africa (see presentation by Vivancos et al., this meeting). Despite greater productivity off Peru, we find greater intensity of scavenging off NW Africa as measured by the residence time of dissolved 230Th integrated from the surface to a depth of 2500 m (10-11 years off NW Africa vs. 15-17 years off Peru). Dissolved 231Pa/230Th ratios off NW Africa (Hayes et al., Deep Sea Res.-II 116 (2015) 29-41) are nearly twice the values observed off Peru. We attribute this difference to the well-known tendency for lithogenic phases (dust) to strongly fractionate in favor of Th uptake during scavenging and removal, leaving the dissolved phase enriched in Pa. This behavior needs to be considered when interpreting sedimentary 231Pa/230Th ratios as a paleo proxy.
EXAMINING FLORISTIC BOUNDARIES BETWEEN GARDEN TYPES AT THE GLOBAL SCALE
Directory of Open Access Journals (Sweden)
Josep Padullés Cubino
2014-01-01
Full Text Available Los jardines son una importante fuente de bienes y servicios para los residentes de un hogar. Su función se traduce directamente en el tipo de plantas que en ellos se cultiva. Por otro lado, la terminología usada para denominar los distintos tipos de jardín en inglés (garden, homegarden, forest garden, etc. varía según su función y propósito. Los factores que explican la diferenciación y distribución de los jardines a escala global no habían sido previamente explorados hasta ahora. En este estudio se han analizado los inventarios florísticos de 44 conjuntos de jardines de to do el mundo para explorar sus similitudes taxonómicas y los factores que configuran la distribución de su flora. Para ello, se escogieron distintas variables biofísicas y socioeconómicas a una escala apropiada de trabajo. Como resultado, los factores biofísicos y climáticos (temperatura, precipitación, evapotranspiración potencial y distancia entre asentamientos se hallaron significativamente relacionados con la distribución de las especies; no obstante, todos estos factores resultaron ser menos importantes que el GDP (PIB per cápita, utilizado aquí como indicador de los ingresos del hogar, y que se obtuvo como el principal impulsor de la composición de los jardines. También el resto de factores sociales y culturales incluidos en el análisis, como son la similitud entre las lenguas de los distintos asentamientos o la densidad de población, se encontraron como variables significativas. Cabe señalar que el presente análisis omite cierto número de variables debido a la no disponibilidad de datos. Algunas de estas variables son el tamaño del jardín o el género de su dueño, las cuales han sido reconocidas previamente como agentes influyentes en la composición vegetal de los jardines. El estudio concluye que los géneros vegetales cultivados en los conjuntos de jardines son muy diferentes entre sí y que, por lo tanto, las distinciones entre tipologías de jardín son difíciles de establecer a partir de tan solo datos florísticos. Por último, se discuten también las implicaciones que podrían tener posibles futuras fluctuaciones en el nivel de la renta (causadas por una severa crisis económica o el cambio climático, sobre la diversidad bio-cultural y la seguridad alimentaria.
Boundary Conditions for a New Type of Design Task
DEFF Research Database (Denmark)
McAloone, Tim C.
2011-01-01
Manufacturing companies have traditionally focused their efforts on developing and producing physical products for the market. Currently, however, many companies are rethinking their business strategies, from selling products to providing services. In place of the product alone, the activity...... the field to industrial manufacturing companies....
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.
Is boundary extension emotionally selective?
Ménétrier, Emmanuelle; Didierjean, André; Vieillard, Sandrine
2013-01-01
When they have to memorize a picture, people usually build a memory trace including more extensive boundaries than the original picture, a phenomenon known as boundary extension or BE. This article looks at whether the emotion category expressed (i.e., happiness, pleasure, irritation, or anger) by actors in short films could have an influence on the BE effect. The results showed that positively valenced emotions (happiness, pleasure) led to an extension effect, while the negatively valenced ones (anger, irritation) did not produce any significant memory distortion. The arousal dimension of emotions had no significant effect on BE. The current results were discussed in the light of previous studies on the links between BE and emotions.
Boundary Spanners in Global Partnerships
DEFF Research Database (Denmark)
Søderberg, Anne-Marie; Romani, Laurence
2017-01-01
Western companies’ outsourcing of projects to emergent markets is increasingly being replaced by strategic partnerships that require close collaboration between clients and vendors. This study focuses on interorganizational boundary-spanning activities in the context of global information...... 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......-spanning activities that are reported. The analysis demonstrates the coexistence of transactive and transformative modes of collaboration in the studied case. It reveals both the importance of partner status and the impact of that status on the forms of boundary-spanning activities in which the partners engage...
Plasma boundary phenomena in tokamaks
International Nuclear Information System (INIS)
Stangeby, P.C.
1989-06-01
The focus of this review is on processes occurring at the edge, and on the connection between boundary plasma - the scrape-off layer (SOL) and the radiating layer - and central plasma processes. Techniques used for edge diagnosis are reviewed and basic experimental information (n e and T e ) is summarized. Simple models of the SOL are summarized, and the most important effects of the boundary plasma - the influence on the fuel particles, impurities, and energy - on tokamak operation dealt with. Methods of manipulating and controlling edge conditions in tokamaks and the experimental data base for the edge during auxiliary heating of tokamaks are reviewed. Fluctuations and asymmetries at the edge are also covered. (9 tabs., 134 figs., 879 refs.)
Applied thermodynamics: Grain boundary segregation
Czech Academy of Sciences Publication Activity Database
Lejček, Pavel; Zheng, L.; Hofmann, S.; Šob, Mojmír
2014-01-01
Roč. 16, č. 3 (2014), s. 1462-1484 ISSN 1099-4300 R&D Projects: GA ČR(CZ) GAP108/12/0311; GA ČR GAP108/12/0144; GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68378271 ; RVO:68081723 Keywords : interfacial segregation * Gibbs energy of segregation * enthalpy * entropy * volume * grain boundaries * iron Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.502, year: 2014
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....
Experimental measurements and modelling of the WEGA boundary layer plasma
International Nuclear Information System (INIS)
El Shaer, M.; Ichtchenko, G.
1983-02-01
The boundary layer of the WEGA Tokamak has been investigated by using specific diagnostics: movable 4 mm microwave interferometer, several types of movable and fixed probes, Katsumata probe, and multigrid electrostatic analyzer. During the RF heating at the lower hybrid frequency, some modifications in the parameters of the boundary layer are observed which are interpreted by the ponderomotive force effects. A comparison between the measured reflection coefficients of the grill waveguides and their predicted values by a coupling theory (not taking into account the real conditions facing the Grill) is presented. A diffusion model was also made to describe this particular region and to fit the experimental results
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.
Lovelock action with nonsmooth boundaries
Cano, Pablo A.
2018-05-01
We examine the variational problem in Lovelock gravity when the boundary contains timelike and spacelike segments nonsmoothly glued. We show that two kinds of contributions have to be added to the action. The first one is associated with the presence of a boundary in every segment and it depends on intrinsic and extrinsic curvatures. We can think of this contribution as adding a total derivative to the usual surface term of Lovelock gravity. The second one appears in every joint between two segments and it involves the integral along the joint of the Jacobson-Myers entropy density weighted by the Lorentz boost parameter, which relates the orthonormal frames in each segment. We argue that this term can be straightforwardly extended to the case of joints involving null boundaries. As an application, we compute the contribution of these terms to the complexity of global anti-de Sitter space in Lovelock gravity by using the "complexity =action " proposal and we identify possible universal terms for arbitrary values of the Lovelock couplings. We find that they depend on the charge a* controlling the holographic entanglement entropy and on a new constant that we characterize.
Voting based object boundary reconstruction
Tian, Qi; Zhang, Like; Ma, Jingsheng
2005-07-01
A voting-based object boundary reconstruction approach is proposed in this paper. Morphological technique was adopted in many applications for video object extraction to reconstruct the missing pixels. However, when the missing areas become large, the morphological processing cannot bring us good results. Recently, Tensor voting has attracted people"s attention, and it can be used for boundary estimation on curves or irregular trajectories. However, the complexity of saliency tensor creation limits its applications in real-time systems. An alternative approach based on tensor voting is introduced in this paper. Rather than creating saliency tensors, we use a "2-pass" method for orientation estimation. For the first pass, Sobel d*etector is applied on a coarse boundary image to get the gradient map. In the second pass, each pixel puts decreasing weights based on its gradient information, and the direction with maximum weights sum is selected as the correct orientation of the pixel. After the orientation map is obtained, pixels begin linking edges or intersections along their direction. The approach is applied to various video surveillance clips under different conditions, and the experimental results demonstrate significant improvement on the final extracted objects accuracy.
Boundary determinations for trivariate solids
International Nuclear Information System (INIS)
Duchaineau, M; Joy, K I
1999-01-01
The trivariate tensor-product B-spline solid is a direct extension of the B-spline patch and has been shown to be useful in the creation and visualization of free-form geometric solids. Visualizing these solid objects requires the determination of the boundary surface of the solid, which is a combination of parametric and implicit surfaces. This paper presents a method that determines the implicit boundary surface by examination of the Jacobian determinant of the defining B-spline function. Using an approximation to this determinant, the domain space is adaptively subdivided until a mesh can be determined such that the boundary surface is close to linear in the cells of the mesh. A variation of the marching cubes algorithm is then used to draw the surface. Interval approximation techniques are used to approximate the Jacobian determinant and to approximate the Jacobian determinant gradient for use in the adaptive subdivision methods. This technique can be used to create free-form solid objects, useful in geometric modeling applications
Event boundaries and memory improvement.
Pettijohn, Kyle A; Thompson, Alexis N; Tamplin, Andrea K; Krawietz, Sabine A; Radvansky, Gabriel A
2016-03-01
The structure of events can influence later memory for information that is embedded in them, with evidence indicating that event boundaries can both impair and enhance memory. The current study explored whether the presence of event boundaries during encoding can structure information to improve memory. In Experiment 1, memory for a list of words was tested in which event structure was manipulated by having participants walk through a doorway, or not, halfway through the word list. In Experiment 2, memory for lists of words was tested in which event structure was manipulated using computer windows. Finally, in Experiments 3 and 4, event structure was manipulated by having event shifts described in narrative texts. The consistent finding across all of these methods and materials was that memory was better when the information was distributed across two events rather than combined into a single event. Moreover, Experiment 4 demonstrated that increasing the number of event boundaries from one to two increased the memory benefit. These results are interpreted in the context of the Event Horizon Model of event cognition. Copyright © 2015 Elsevier B.V. All rights reserved.
Scientific advice and public policy: expert advisers' and policymakers' discourses on boundary work
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
Application of He's variational iteration method to the fifth-order boundary value problems
International Nuclear Information System (INIS)
Shen, S
2008-01-01
Variational iteration method is introduced to solve the fifth-order boundary value problems. This method provides an efficient approach to solve this type of problems without discretization and the computation of the Adomian polynomials. Numerical results demonstrate that this method is a promising and powerful tool for solving the fifth-order boundary value problems
Negotiating the Boundaries Between Mathematics and Physics
Radtka, Catherine
2015-07-01
This paper examines physics and mathematics textbooks published in France at the end of the 1950s and at the beginning of the 1960s for children aged 11-15 years old. It argues that at this "middle school" level, textbooks contributed to shape cultural representations of both disciplines and their mutual boundaries through their contents and their material aspect. Further, this paper argues that far from presenting clearly delimited subjects, late 1950s textbooks offered possible connections between mathematics and physics. It highlights that such connections depended upon the type of schools the textbooks aimed at, at a time when educational organization still differentiated pupils of this age. It thus stresses how the audience and its projected aptitudes and needs, as well as the cultural teaching traditions of the teachers in charge, were inseparable from the diverse conceptions of mathematics and physics and their relationships promoted through textbooks of the time.
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...
Integrability and boundary conditions of supersymmetric systems
International Nuclear Information System (INIS)
Yue Ruihong; Liang Hong
1996-01-01
By studying the solutions of the reflection equations, we find out a series of integrable supersymmetric systems with different boundary conditions. The Hamiltonian contains four free parameters which describe the contribution of the boundary terms
International Nuclear Information System (INIS)
Kung, H.; Sass, S.L.
1992-01-01
This paper discusses the dislocation structure of small angle tilt and twist boundaries in ordered Ni 3 Al, with and without boron, investigated using transmission electron microscopy. Dislocation with Burgers vectors that correspond to anti-phase boundary (APB)-coupled superpartials were found in small angle twist boundaries in both boron-free and boron-doped Ni 3 Al, and a small angle tilt boundary in boron-doped Ni 3 Al. The boundary structures are in agreement with theoretical models proposed by Marcinkowski and co-workers. The APB energy determined from the dissociation of the grain boundary dislocations was lower than values reported for isolated APBs in Ni 3 Al. For small angle twist boundaries the presence of boron reduced the APB energy at the interface until it approached zero. This is consistent with the structure of these boundaries containing small regions of increased compositional disorder in the first atomic plane next to the interface
Practical boundary surveying legal and technical principles
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 ...
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...
Cal State Park Boundaries 2011/2012
California Natural Resource Agency — This is a GIS version of California State Park (CSP) operational boundaries and does not represent official property boundary determinations. This GIS version is...
Grain boundary cavity growth under applied stress and internal pressure
International Nuclear Information System (INIS)
Mancuso, J.F.
1977-08-01
The growth of grain boundary cavities under applied stress and internal gas pressure was investigated. Methane gas filled cavities were produced by the C + 4H reversible CH4 reaction in the grain boundaries of type 270 nickel by hydrogen charging in an autoclave at 500 0 C with a hydrogen pressure of either 3.4 or 14.5 MPa. Intergranular fracture of nickel was achieved at a charging temperature of 300 0 C and 10.3 MPa hydrogen pressure. Cavities on the grain boundaries were observed in the scanning electron microscope after fracture. Photomicrographs of the cavities were produced in stereo pairs which were analyzed so as to correct for perspective distortion and also to determine the orientational dependence of cavity growth under an applied tensile stress
Stability and boundary stabilization of 1-D hyperbolic systems
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...
Defects and boundary layers in non-Euclidean plates
International Nuclear Information System (INIS)
Gemmer, J A; Venkataramani, S C
2012-01-01
We investigate the behaviour of non-Euclidean plates with constant negative Gaussian curvature using the Föppl–von Kármán reduced theory of elasticity. Motivated by recent experimental results, we focus on annuli with a periodic profile. We prove rigorous upper and lower bounds for the elastic energy that scales like the thickness squared. In particular we show that are only two types of global minimizers—deformations that remain flat and saddle shaped deformations with isolated regions of stretching near the edge of the annulus. We also show that there exist local minimizers with a periodic profile that have additional boundary layers near their lines of inflection. These additional boundary layers are a new phenomenon in thin elastic sheets and are necessary to regularize jump discontinuities in the azimuthal curvature across lines of inflection. We rigorously derive scaling laws for the width of these boundary layers as a function of the thickness of the sheet. (paper)
Two-point boundary correlation functions of dense loop models
Directory of Open Access Journals (Sweden)
Alexi Morin-Duchesne, Jesper Lykke Jacobsen
2018-06-01
Full Text Available We investigate six types of two-point boundary correlation functions in the dense loop model. These are defined as ratios $Z/Z^0$ of partition functions on the $m\\times n$ square lattice, with the boundary condition for $Z$ depending on two points $x$ and $y$. We consider: the insertion of an isolated defect (a and a pair of defects (b in a Dirichlet boundary condition, the transition (c between Dirichlet and Neumann boundary conditions, and the connectivity of clusters (d, loops (e and boundary segments (f in a Neumann boundary condition. For the model of critical dense polymers, corresponding to a vanishing loop weight ($\\beta = 0$, we find determinant and pfaffian expressions for these correlators. We extract the conformal weights of the underlying conformal fields and find $\\Delta = -\\frac18$, $0$, $-\\frac3{32}$, $\\frac38$, $1$, $\\tfrac \\theta \\pi (1+\\tfrac{2\\theta}\\pi$, where $\\theta$ encodes the weight of one class of loops for the correlator of type f. These results are obtained by analysing the asymptotics of the exact expressions, and by using the Cardy-Peschel formula in the case where $x$ and $y$ are set to the corners. For type b, we find a $\\log|x-y|$ dependence from the asymptotics, and a $\\ln (\\ln n$ term in the corner free energy. This is consistent with the interpretation of the boundary condition of type b as the insertion of a logarithmic field belonging to a rank two Jordan cell. For the other values of $\\beta = 2 \\cos \\lambda$, we use the hypothesis of conformal invariance to predict the conformal weights and find $\\Delta = \\Delta_{1,2}$, $\\Delta_{1,3}$, $\\Delta_{0,\\frac12}$, $\\Delta_{1,0}$, $\\Delta_{1,-1}$ and $\\Delta_{\\frac{2\\theta}\\lambda+1,\\frac{2\\theta}\\lambda+1}$, extending the results of critical dense polymers. With the results for type f, we reproduce a Coulomb gas prediction for the valence bond entanglement entropy of Jacobsen and Saleur.
Boundary induced nonlinearities at small Reynolds numbers
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
78 FR 15883 - Standard Time Zone Boundaries
2013-03-13
...] RIN 2105-AE20 Standard Time Zone Boundaries AGENCY: Office of the Secretary (OST), Department of... time zone boundaries regulations to reflect changes that Congress made to the Uniform Time Act. The... regulations on standard time zone boundaries, 49 CFR Part 71, need to be updated in order to ensure their...
VT 1990 Census County Boundaries and Statistics
Vermont Center for Geographic Information — (Link to Metadata) DemoCensus_CNTY1990 is derived from BoundaryCounty_CNTY250. BoundaryCounty_CNTY250 was derived from BoundaryTown_TB250 (TB250 was archived 6/2003...
Integrable boundary conditions and modified Lax equations
International Nuclear Information System (INIS)
Avan, Jean; Doikou, Anastasia
2008-01-01
We consider integrable boundary conditions for both discrete and continuum classical integrable models. Local integrals of motion generated by the corresponding 'transfer' matrices give rise to time evolution equations for the initial Lax operator. We systematically identify the modified Lax pairs for both discrete and continuum boundary integrable models, depending on the classical r-matrix and the boundary matrix
Competing Grain Boundary and Interior Deformation Mechanisms with Varying Sizes
Energy Technology Data Exchange (ETDEWEB)
Zhang, Wei [University of Tennessee (UT); Gao, Yanfei [ORNL; Nieh, T. G. [University of Tennessee, Knoxville (UTK)
2018-01-01
In typical coarse-grained alloys, the dominant plastic deformations are dislocation gliding or climbing, and material strengths can be tuned by dislocation interactions with grain boundaries, precipitates, solid solutions, and other defects. With the reduction of grain size, the increase of material strengths follows the classic Hall-Petch relationship up to nano-grained materials. Even at room temperatures, nano-grained materials exhibit strength softening, or called the inverse Hall-Petch effect, as grain boundary processes take over as the dominant deformation mechanisms. On the other hand, at elevated temperatures, grain boundary processes compete with grain interior deformation mechanisms over a wide range of the applied stress and grain sizes. This book chapter reviews and compares the rate equation model and the microstructure-based finite element simulations. The latter explicitly accounts for the grain boundary sliding, grain boundary diffusion and migration, as well as the grain interior dislocation creep. Therefore the explicit finite element method has clear advantages in problems where microstructural heterogeneities play a critical role, such as in the gradient microstructure in shot peening or weldment. Furthermore, combined with the Hall-Petch effect and its breakdown, the above competing processes help construct deformation mechanism maps by extending from the classic Frost-Ashby type to the ones with the dependence of grain size.
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.
Boundary singularities produced by the motion of soap films.
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.
Impurity effects on the grain boundary cohesion in copper
Li, Yunguo; Korzhavyi, Pavel A.; Sandström, Rolf; Lilja, Christina
2017-12-01
Segregated impurities at grain boundaries can dramatically change the mechanical behavior of metals, while the mechanism is still obscure in some cases. Here, we suggest a unified approach to investigate segregation and its effects on the mechanical properties of polycrystalline alloys using the example of 3 s p impurities (Mg, Al, Si, P, or S) at a special type Σ 5 (310 )[001 ] tilt grain boundary in Cu. We show that for these impurities segregating to the grain boundary, the strain contribution to the work of grain boundary decohesion is small and that the chemical contribution correlates with the electronegativity difference between Cu and the impurity. The strain contribution to the work of dislocation emission is calculated to be negative, while the chemical contribution is calculated to be always positive. Both the strain and chemical contributions to the work of dislocation emission generally become weaker with the increasing electronegativity from Mg to S. By combining these contributions together, we find, in agreement with experimental observations, that a strong segregation of S can reduce the work of grain boundary separation below the work of dislocation emission, thus embrittling Cu, while such an embrittlement cannot be produced by a P segregation because it lowers the energy barrier for dislocation emission relatively more than for work separation.
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.
Stability, interaction and influence of domain boundaries in Ge/Si(111)-5 × 5
International Nuclear Information System (INIS)
Ondráček, Martin; Mutombo, Pingo; Chvoj, Zdeněk; Chromcová, Zdeňka; Jelínek, Pavel; Mark, Andrew G; McLean, Alastair B
2012-01-01
We present a theoretical investigation of the influence of domain boundaries on the Ge/Si(111)-5 × 5 phase using both large-scale DFT simulations and an analytical model. It is shown that different boundary types modify the atomic and electronic structure of the adjoining 5 × 5 domains in very different ways. A simple theoretical model, that describes the energy interaction J between the boundaries and the 5 × 5 phase, is presented and the interaction energy decay J(x) ≈ x -n for different domain boundaries is estimated. Additionally, the influence of the boundaries on the atomic and electronic structure of adatoms in the parental 5 × 5 phase is analyzed and it is argued that the presence of domain boundaries may strongly affect not only the physical but also the chemical properties of the Ge/Si(111)-5 × 5 phase.
Do professional boundaries limit trust?
Smythe, Elizabeth; Hennessy, Julia; Abbott, Max; Hughes, Frances
2018-02-01
The present study uses stories of mental health support workers talking about their relationship with clients to wonder about how trust might be limited by the professional boundaries of nursing. The writing arose out of an appreciative inquiry study looking at the role of mental health support workers. Participants talked about how they worked with their clients. As researchers, we were struck by the depth of trust that was built between worker and client. We have brought a phenomenological lens to wonder about the nature of trust, as shown in the data. The original research sought to identify what was working well for mental health support workers. The present study brings a phenomenological interpretive approach to four stories from the discovery phase of the study, with our thinking informed by Heidegger and van Manen. Interviews were conducted with 26 mental health support workers and six stakeholders in 2012-2103. For this paper, we drew from those transcripts stories of three mental health support workers and one stakeholder. Through a process of talking together, writing, and rewriting, we wondered about the meaning within these stories, with a strong focus on how trust was enacted. We saw that mental health support workers in this study, by not carrying the boundaries of being 'professional', seemed free to grow a stronger relationship of trust which was therapeutic. We ask: Is it time to rethink how professional boundaries limit the level of trust achieved with clients to the detriment of impactful care? © 2017 Australian College of Mental Health Nurses Inc.
BOUNDARY CONDITIONS IN GAP GEOMETRY
Energy Technology Data Exchange (ETDEWEB)
Rothenstein, W.; Helholtz, J.
1963-11-15
The procedure for calculnting the monoenergetic angular flux density in lattice cells including voids between fuel and moderator is discussed. Boundary conditions describThe thermal energy of a nuclear reactor may be conserved by using as the reactor coolant a hydrocarbon fraction boiling within the range 220 to 650 deg C (preferably 340 to 550 deg C) and containing not more than 5% of extraneous materials having neutron cross sections of > 10 barns. The hot coolant may either be cracked outside of the reactor or used to heat another petroleum hydrocarbon which is to be converted. (D.L.C.)
Review: the atmospheric boundary layer
Garratt, J. R.
1994-10-01
An overview is given of the atmospheric boundary layer (ABL) over both continental and ocean surfaces, mainly from observational and modelling perspectives. Much is known about ABL structure over homogeneous land surfaces, but relatively little so far as the following are concerned, (i) the cloud-topped ABL (over the sea predominantly); (ii) the strongly nonhomogeneous and nonstationary ABL; (iii) the ABL over complex terrain. These three categories present exciting challenges so far as improved understanding of ABL behaviour and improved representation of the ABL in numerical models of the atmosphere are concerned.
Plasma transport through magnetic boundaries
International Nuclear Information System (INIS)
Treumann, R.A.
1992-01-01
We examine the overall plasma diffusion processes across tangential discontinuities of which the best known example is the Earth's magnetopause during northward interplanetary magnetic field conditions. The existence of the low latitude boundary layer (LLBL) adjacent to the magnetopause during those periods is ample evidence for the presence of so far poorly defined and understood entry processes acting at the magnetopause. We conclude that microscopic instabilities are probably not efficient enough to account for the LLBL. They affect only a small number of resonant particles. It is argued that macroscopic nonresonant turbulence is the most probable mechanism for plasma transport
Applied Thermodynamics: Grain Boundary Segregation
Directory of Open Access Journals (Sweden)
Pavel Lejček
2014-03-01
Full Text Available Chemical composition of interfaces—free surfaces and grain boundaries—is generally described by the Langmuir–McLean segregation isotherm controlled by Gibbs energy of segregation. Various components of the Gibbs energy of segregation, the standard and the excess ones as well as other thermodynamic state functions—enthalpy, entropy and volume—of interfacial segregation are derived and their physical meaning is elucidated. The importance of the thermodynamic state functions of grain boundary segregation, their dependence on volume solid solubility, mutual solute–solute interaction and pressure effect in ferrous alloys is demonstrated.
The detection of boundaries in leaky aquifers
International Nuclear Information System (INIS)
Cook, A.J.
1989-01-01
Geological faults in sedimentary basins can affect the regional and local groundwater flow patterns by virtue of their enhanced permeability properties. Faults can be regarded as vertical flow boundaries and potentially important routes for radionuclide migration from a theoretical radioactive waste repository. This report investigates the hydraulic testing methods currently available which may be used to locate vertical hydraulic discontinuities (boundaries) within an aquifer. It aims to define the theoretical limitations to boundary detection by a single pumping test, to determine the optimum design of a pumping test for locating boundaries, and to define the practical limitations to boundary detection by a pumping test. (author)
Tricritical Ising model with a boundary
International Nuclear Information System (INIS)
De Martino, A.; Moriconi, M.
1998-03-01
We study the integrable and supersymmetric massive φ (1,3) deformation of the tricritical Ising model in the presence of a boundary. We use constraints from supersymmetry in order to compute the exact boundary S-matrices, which turn out to depend explicitly on the topological charge of the supersymmetry algebra. We also solve the general boundary Yang-Baxter equation and show that in appropriate limits the general reflection matrices go over the supersymmetry preserving solutions. Finally, we briefly discuss the possible connection between our reflection matrices and boundary perturbations within the framework of perturbed boundary conformal field theory. (author)
International Nuclear Information System (INIS)
Ozgener, B.
1998-01-01
A boundary integral equation (BIE) is developed for the application of the boundary element method to the multigroup neutron diffusion equations. The developed BIE contains no explicit scattering term; the scattering effects are taken into account by redefining the unknowns. Boundary elements of the linear and constant variety are utilised for validation of the developed boundary integral formulation
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.
Urban CO2 emissions in China: Spatial boundary and performance comparison
International Nuclear Information System (INIS)
Cai, Bofeng; Zhang, Lixiao
2014-01-01
Different names/concepts and therefore different spatial boundaries for cities in China are responsible for the conflicting and confusing results associated with urban CO 2 emissions accounting. In this study, four types of urban boundaries, i.e., city administrative boundary (UB 1 ), city district boundary (UB 2 ), city built-up area (UB 3 ) and urban proper (UB 4 ), were identified and defined. Tianjin was subsequently selected as the case city to illustrate the different performances of CO 2 emissions with respect to these four boundaries using a 1-km grid dataset built bottom-up by point-emission sources. Different urban boundaries can induce a difference in CO 2 emissions as large as 654%. UB 1 and UB 2 are not the appropriate proxies for urban boundaries in the analysis of urban CO 2 emissions, although UB 1 is a widely adopted boundary. UB 3 is a good representative of city clusters and urban sprawl in a certain region, whereas UB 4 is the appropriate system boundary for such issues as urban CO 2 emissions in light of landscape characteristics and pertinent human activities, as well as the comparability to counterparts in developed countries. These results provide sound policy implications for the improvement of urban energy management and carbon emission abatement in China. - highlights: • Four types of urban boundaries in China were clarified and defined. • Different urban boundaries will induce deviation in CO 2 emissions as large as 654%. • The UB 4 stands for appropriate urban boundary for urban CO 2 emissions analysis. • Gridded data proves to be supplementary tools for urban CO 2 emissions accounting
Fiat or bona fide boundary--a matter of granular perspective.
Directory of Open Access Journals (Sweden)
Lars Vogt
Full Text Available Distinguishing bona fide (i.e. natural and fiat (i.e. artificial physical boundaries plays a key role for distinguishing natural from artificial material entities and is thus relevant to any scientific formal foundational top-level ontology, as for instance the Basic Formal Ontology (BFO. In BFO, the distinction is essential for demarcating two foundational categories of material entity: object and fiat object part. The commonly used basis for demarcating bona fide from fiat boundary refers to two criteria: (i intrinsic qualities of the boundary bearers (i.e. spatial/physical discontinuity, qualitative heterogeneity and (ii mind-independent existence of the boundary. The resulting distinction of bona fide and fiat boundaries is considered to be categorial and exhaustive.By Referring to various examples from biology, we demonstrate that the hitherto used distinction of boundaries is not categorial: (i spatial/physical discontinuity is a matter of scale and the differentiation of bona fide and fiat boundaries is thus granularity-dependent, and (ii this differentiation is not absolute, but comes in degrees. By reducing the demarcation criteria to mind-independence and by also considering dispositions and historical relations of the bearers of boundaries, instead of only considering their spatio-structural properties, we demonstrate with various examples that spatio-structurally fiat boundaries can nevertheless be mind-independent and in this sense bona fide.We argue that the ontological status of a given boundary is perspective-dependent and that the strictly spatio-structural demarcation criteria follow a static perspective that is ignorant of causality and the dynamics of reality. Based on a distinction of several ontologically independent perspectives, we suggest different types of boundaries and corresponding material entities, including boundaries based on function (locomotion, physiology, ecology, development, reproduction and common history
International Nuclear Information System (INIS)
Li Xicheng; Xu Mingyu; Wang Shaowei
2008-01-01
In this paper, we give similarity solutions of partial differential equations of fractional order with a moving boundary condition. The solutions are given in terms of a generalized Wright function. The time-fractional Caputo derivative and two types of space-fractional derivatives are considered. The scale-invariant variable and the form of the solution of the moving boundary are obtained by the Lie group analysis. A comparison between the solutions corresponding to two types of fractional derivative is also given
Boundary element simulation of petroleum reservoirs with hydraulically fractured wells
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
Fusion boundary microstructure evolution in aluminum alloys
Kostrivas, Anastasios Dimitrios
2000-10-01
A melting technique was developed to simulate the fusion boundary of aluminum alloys using the GleebleRTM thermal simulator. Using a steel sleeve to contain the aluminum, samples were heated to incremental temperatures above the solidus temperature of a number of alloys. In alloy 2195, a 4wt%Cu-1wt%Li alloy, an equiaxed non-dendritic zone (EQZ) could be formed by heating in the temperature range from approximately 630 to 640°C. At temperatures above 640°C, solidification occurred by the normal epitaxial nucleation and growth mechanism. Fusion boundary behavior was also studied in alloys 5454-H34, 6061-T6, and 2219-T8. Additionally, experimental alloy compositions were produced by making bead on plate welds using an alloy 5454-H32 base metal and 5025 or 5087 filler metals. These filler metals contain zirconium and scandium additions, respectively, and were expected to influence nucleation and growth behavior. Both as-welded and welded/heat treated (540°C and 300°C) substrates were tested by melting simulation, resulting in dendritic and EQZ structures depending on composition and substrate condition. Orientation imaging microscopy (OIM(TM)) was employed to study the crystallographic character of the microstructures produced and to verify the mechanism responsible for EQZ formation. OIM(TM) proved that grains within the EQZ have random orientation. In all other cases, where the simulated microstructures were dendritic in nature, it was shown that epitaxy was the dominant mode of nucleation. The lack of any preferred crystallographic orientation relationship in the EQZ supports a theory proposed by Lippold et al that the EQZ is the result of heterogeneous nucleation within the weld unmixed zone. EDS analysis of the 2195 on STEM revealed particles with ternary composition consisted of Zr, Cu and Al and a tetragonal type crystallographic lattice. Microdiffraction line scans on EQZ grains in the alloy 2195 showed very good agreement between the measured Cu
Stabilization of the hypersonic boundary layer by finite-amplitude streaks
Ren, Jie; Fu, Song; Hanifi, Ardeshir
2016-02-01
Stabilization of two-dimensional disturbances in hypersonic boundary layer flows by finite-amplitude streaks is investigated using nonlinear parabolized stability equations. The boundary-layer flows at Mach numbers 4.5 and 6.0 are studied in which both first and second modes are supported. The streaks considered here are driven either by the so-called optimal perturbations (Klebanoff-type) or the centrifugal instability (Görtler-type). When the streak amplitude is in an appropriate range, i.e., large enough to modulate the laminar boundary layer but low enough to not trigger secondary instability, both first and second modes can effectively be suppressed.
Working with boundaries in systems psychodynamic consulting
Directory of Open Access Journals (Sweden)
Henk Struwig
2012-03-01
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.
Compressible stability of growing boundary layers using parabolized stability equations
Chang, Chau-Lyan; Malik, Mujeeb R.; Erlebacher, Gordon; Hussaini, M. Y.
1991-01-01
The parabolized stability equation (PSE) approach is employed to study linear and nonlinear compressible stability with an eye to providing a capability for boundary-layer transition prediction in both 'quiet' and 'disturbed' environments. The governing compressible stability equations are solved by a rational parabolizing approximation in the streamwise direction. Nonparallel flow effects are studied for both the first- and second-mode disturbances. For oblique waves of the first-mode type, the departure from the parallel results is more pronounced as compared to that for the two-dimensional waves. Results for the Mach 4.5 case show that flow nonparallelism has more influence on the first mode than on the second. The disturbance growth rate is shown to be a strong function of the wall-normal distance due to either flow nonparallelism or nonlinear interactions. The subharmonic and fundamental types of breakdown are found to be similar to the ones in incompressible boundary layers.
Delineation of peatland lagg boundaries from airborne LiDAR
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.
Moho vs crust-mantle boundary: Evolution of an idea
O'Reilly, Suzanne Y.; Griffin, W. L.
2013-12-01
The concept that the Mohorovicic Discontinuity (Moho) does not necessarily coincide with the base of the continental crust as defined by rock-type compositions was introduced in the early 1980s. This had an important impact on understanding the nature of the crust-mantle boundary using information from seismology and from deep-seated samples brought to the surface as xenoliths in magmas, or as tectonic terranes. The use of empirically-constrained P-T estimates to plot the locus of temperature vs depth for xenoliths defined a variety of geotherms depending on tectonic environment. The xenolith geotherms provided a framework for constructing lithological sections through the deep lithosphere, and revealed that the crust-mantle boundary in off-craton regions commonly is transitional over a depth range of about 5-20 km. Early seismic-reflection data showed common layering near the Moho, correlating with the petrological observation of multiple episodes of basaltic intrusion around the crust-mantle boundary. Developments in seismology, petrophysics and experimental petrology have refined interpretation of lithospheric domains. The expansion of in situ geochronology (especially zircon U-Pb ages and Hf-isotopes; Os isotopes of mantle sulfides) has defined tectonic events that affected whole crust-mantle sections, and revealed that the crust-mantle boundary can change in depth through time. However, the nature of the crust-mantle boundary in cratonic regions remains enigmatic, mainly due to lack of key xenoliths or exposed sections. The observation that the Moho may lie significantly deeper than the crust-mantle boundary has important implications for modeling the volume of the crust. Mapping the crust using seismic techniques alone, without consideration of the petrological problems, may lead to an overestimation of crustal thickness by 15-30%. This will propagate to large uncertainties in the calculation of elemental mass balances relevant to crust-formation processes
Outer Magnetospheric Boundaries Cluster Results
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 ...
Exploring the magnetospheric boundary layer
International Nuclear Information System (INIS)
Hapgood, M.A.; Bryant, D.A.
1992-01-01
We show how, for most crossings of the boundary layer, one can construct a 'transition parameter', based on electron density and temperature, which orders independent plasma measurements into well-defined patterns which are consistent from case to case. We conclude that there is a gradual change in the balance of processes which determine the structure of the layer and suggest that there is no advantage in dividing the layer into different regions. We further conclude that the mixing processes in layer act in an organised way to give the consistent patterns revealed by the transition parameter. More active processes must sometimes take to give the extreme values (e.g. in velocity) which are seen in some crossings
Boundary works of Grindr research
DEFF Research Database (Denmark)
Jørgensen, Kristian Møller
Boundary works of Grindr research: Sociological and queer perspectives on shame and intimacy As a newly minted PhD student I am eager to explain to my colleagues what hook-up apps are and why we should care to look at them. One day at the University campus talking to a colleague I find myself out...... The issues at play in the above vignette (Humphreys 2005) represent at least two familiar issues: The media scholar working ethnographically finding that there seems to be “two there’s there” (Schegloff 2002); and the queer, insider researcher coming into academia and moving back into the queer cultural...... ethnographers face both a quantitative increase and a qualitatively changed situation. In the vignette, the fact that the Grindr app, by way of its locative abilities, displays users nearby ties directly into the felt discomfort: The fact that the community that is “exposed” comprises of students and faculty...
Plasma transport near material boundaries
International Nuclear Information System (INIS)
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
Czech Academy of Sciences Publication Activity Database
Orlová, Alena; Dobeš, Ferdinand
2008-01-01
Roč. 567-568, - (2008), s. 173-176 ISSN 0255-5476. [MSMF /5./. Brno, 27.06.2007-29.06.2007] R&D Projects: GA AV ČR 1QS200410502 Institutional research plan: CEZ:AV0Z20410507 Keywords : creep * internal stress * subgrain * dislocation density Subject RIV: BM - Solid Matter Physics ; Magnetism
Microstructure changes in the low stacking fault energy steel
International Nuclear Information System (INIS)
Rodak, K.; Kuc, D.; Niewielski, G.; Hetmanczyk, M.
1999-01-01
A Cr-Ni austenitic steel (type 304) was investigated using TEM. It is shown that some structural parameters (dislocations density within the subgrains and the subgrains size) change with temperature and strain rate after hot temperature deformation. The subgrain microstructure was characterized quantitatively for different characteristics. (author)
Topology and boundary shape optimization as an integrated design tool
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.
A Method for Extracting Road Boundary Information from Crowdsourcing Vehicle GPS Trajectories.
Yang, Wei; Ai, Tinghua; Lu, Wei
2018-04-19
Crowdsourcing trajectory data is an important approach for accessing and updating road information. In this paper, we present a novel approach for extracting road boundary information from crowdsourcing vehicle traces based on Delaunay triangulation (DT). First, an optimization and interpolation method is proposed to filter abnormal trace segments from raw global positioning system (GPS) traces and interpolate the optimization segments adaptively to ensure there are enough tracking points. Second, constructing the DT and the Voronoi diagram within interpolated tracking lines to calculate road boundary descriptors using the area of Voronoi cell and the length of triangle edge. Then, the road boundary detection model is established integrating the boundary descriptors and trajectory movement features (e.g., direction) by DT. Third, using the boundary detection model to detect road boundary from the DT constructed by trajectory lines, and a regional growing method based on seed polygons is proposed to extract the road boundary. Experiments were conducted using the GPS traces of taxis in Beijing, China, and the results show that the proposed method is suitable for extracting the road boundary from low-frequency GPS traces, multi-type road structures, and different time intervals. Compared with two existing methods, the automatically extracted boundary information was proved to be of higher quality.
A Method for Extracting Road Boundary Information from Crowdsourcing Vehicle GPS Trajectories
Directory of Open Access Journals (Sweden)
Wei Yang
2018-04-01
Full Text Available Crowdsourcing trajectory data is an important approach for accessing and updating road information. In this paper, we present a novel approach for extracting road boundary information from crowdsourcing vehicle traces based on Delaunay triangulation (DT. First, an optimization and interpolation method is proposed to filter abnormal trace segments from raw global positioning system (GPS traces and interpolate the optimization segments adaptively to ensure there are enough tracking points. Second, constructing the DT and the Voronoi diagram within interpolated tracking lines to calculate road boundary descriptors using the area of Voronoi cell and the length of triangle edge. Then, the road boundary detection model is established integrating the boundary descriptors and trajectory movement features (e.g., direction by DT. Third, using the boundary detection model to detect road boundary from the DT constructed by trajectory lines, and a regional growing method based on seed polygons is proposed to extract the road boundary. Experiments were conducted using the GPS traces of taxis in Beijing, China, and the results show that the proposed method is suitable for extracting the road boundary from low-frequency GPS traces, multi-type road structures, and different time intervals. Compared with two existing methods, the automatically extracted boundary information was proved to be of higher quality.
Quantum Gravitational Effects on the Boundary
James, F.; Park, I. Y.
2018-04-01
Quantum gravitational effects might hold the key to some of the outstanding problems in theoretical physics. We analyze the perturbative quantum effects on the boundary of a gravitational system and the Dirichlet boundary condition imposed at the classical level. Our analysis reveals that for a black hole solution, there is a contradiction between the quantum effects and the Dirichlet boundary condition: the black hole solution of the one-particle-irreducible action no longer satisfies the Dirichlet boundary condition as would be expected without going into details. The analysis also suggests that the tension between the Dirichlet boundary condition and loop effects is connected with a certain mechanism of information storage on the boundary.
Grain Boundary Engineering of Electrodeposited Thin Films
DEFF Research Database (Denmark)
Alimadadi, Hossein
is not yet well-understood. This, at least partly, owes to the lack of robust characterization methods for analyzing the nature of grain boundaries including the grain boundary plane characteristics, until recently. In the past decade, significant improvements in the 2-dimensional and 3-dimensional analysis...... 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...... thermal stability and growth twins annihilate by thermal treatment at 600 degree C. In contrast, for oriented grains, growth nano-twins which are enveloped within columnar grains show a high thermal stability even after thermal treatment at 600 degree C. In order to exploit the high thermal...
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...... impacting macroscopic ferroelectric properties in polycrystalline systems. However detailed studies of such correlated domain structures across grain boundaries are limited. In this work, we have developed the mathematical requirements for domain wall plane matching at grain boundaries of any given...... 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...
Boundary layers of the earth's outer magnetosphere
Eastman, T. E.; Frank, L. A.
1984-01-01
The magnetospheric boundary layer and the plasma-sheet boundary layer are the primary boundary layers of the earth's outer magnetosphere. Recent satellite observations indicate that they provide for more than 50 percent of the plasma and energy transport in the outer magnetosphere although they constitute less than 5 percent by volume. Relative to the energy density in the source regions, plasma in the magnetospheric boundary layer is predominantly deenergized whereas plasma in the plasma-sheet boundary layer has been accelerated. The reconnection hypothesis continues to provide a useful framework for comparing data sampled in the highly dynamic magnetospheric environment. Observations of 'flux transfer events' and other detailed features near the boundaries have been recently interpreted in terms of nonsteady-state reconnection. Alternative hypotheses are also being investigated. More work needs to be done, both in theory and observation, to determine whether reconnection actually occurs in the magnetosphere and, if so, whether it is important for overall magnetospheric dynamics.
Boundary layers of the earth's outer magnetosphere
International Nuclear Information System (INIS)
Eastman, T.E.; Frank, L.A.
1984-01-01
The magnetospheric boundary layer and the plasma-sheet boundary layer are the primary boundary layers of the earth's outer magnetosphere. Recent satellite observations indicate that they provide for more than 50 percent of the plasma and energy transport in the outer magnetosphere although they constitute less than 5 percent by volume. Relative to the energy density in the source regions, plasma in the magnetospheric boundary layer is predominantly deenergized whereas plasma in the plasma-sheet boundary layer has been accelerated. The reconnection hypothesis continues to provide a useful framework for comparing data sampled in the highly dynamic magnetospheric environment. Observations of flux transfer events and other detailed features near the boundaries have been recently interpreted in terms of nonsteady-state reconnection. Alternative hypotheses are also being investigated. More work needs to be done, both in theory and observation, to determine whether reconnection actually occurs in the magnetosphere and, if so, whether it is important for overall magnetospheric dynamics. 30 references
Hamiltonian boundary term and quasilocal energy flux
International Nuclear Information System (INIS)
Chen, C.-M.; Nester, James M.; Tung, R.-S.
2005-01-01
The Hamiltonian for a gravitating region includes a boundary term which determines not only the quasilocal values but also, via the boundary variation principle, the boundary conditions. Using our covariant Hamiltonian formalism, we found four particular quasilocal energy-momentum boundary term expressions; each corresponds to a physically distinct and geometrically clear boundary condition. Here, from a consideration of the asymptotics, we show how a fundamental Hamiltonian identity naturally leads to the associated quasilocal energy flux expressions. For electromagnetism one of the four is distinguished: the only one which is gauge invariant; it gives the familiar energy density and Poynting flux. For Einstein's general relativity two different boundary condition choices correspond to quasilocal expressions which asymptotically give the ADM energy, the Trautman-Bondi energy and, moreover, an associated energy flux (both outgoing and incoming). Again there is a distinguished expression: the one which is covariant
Grain boundary segregation and intergranular failure
International Nuclear Information System (INIS)
White, C.L.
1980-01-01
Trace elements and impurities often segregate strongly to grain boundaries in metals and alloys. Concentrations of these elements at grain boundaries are often 10 3 to 10 5 times as great as their overall concentration in the alloy. Because of such segregation, certain trace elements can exert a disproportionate influence on material properties. One frequently observed consequence of trace element segregation to grain boundaries is the occurrence of grain boundary failure and low ductility. Less well known are incidences of improved ductility and inhibition of grain boundary fracture resulting from trace element segregation to grain boundaries in certain systems. An overview of trace element segregation and intergranular failure in a variety of alloy systems as well as preliminary results from studies on Al 3% Li will be presented
Boundary fluxes for non-local diffusion
Cortazar, C.; Elgueta, M.; Rossi, J. D.; Wolanski, N.
2006-01-01
We study a nonlocal diffusion operator in a bounded smooth domain prescribing the flux through the boundary. This problem may be seen as a generalization of the usual Neumann problem for the heat equation. First, we prove existence, uniqueness and a comparison principle. Next, we study the behavior of solutions for some prescribed boundary data including blowing up ones. Finally, we look at a nonlinear flux boundary condition.
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.
The complex variable boundary element method: Applications in determining approximative boundaries
Hromadka, T.V.
1984-01-01
The complex variable boundary element method (CVBEM) is used to determine approximation functions for boundary value problems of the Laplace equation such as occurs in potential theory. By determining an approximative boundary upon which the CVBEM approximator matches the desired constant (level curves) boundary conditions, the CVBEM is found to provide the exact solution throughout the interior of the transformed problem domain. Thus, the acceptability of the CVBEM approximation is determined by the closeness-of-fit of the approximative boundary to the study problem boundary. ?? 1984.
The surface roughness and planetary boundary layer
Telford, James W.
1980-03-01
Applications of the entrainment process to layers at the boundary, which meet the self similarity requirements of the logarithmic profile, have been studied. By accepting that turbulence has dominating scales related in scale length to the height above the surface, a layer structure is postulated wherein exchange is rapid enough to keep the layers internally uniform. The diffusion rate is then controlled by entrainment between layers. It has been shown that theoretical relationships derived on the basis of using a single layer of this type give quantitatively correct factors relating the turbulence, wind and shear stress for very rough surface conditions. For less rough surfaces, the surface boundary layer can be divided into several layers interacting by entrainment across each interface. This analysis leads to the following quantitatively correct formula compared to published measurements. 1 24_2004_Article_BF00877766_TeX2GIFE1.gif {σ _w }/{u^* } = ( {2/{9Aa}} )^{{1/4}} ( {1 - 3^{{1/2}{ a/k{d_n }/z{σ _w }/{u^* }z/L} )^{{1/4}} = 1.28(1 - 0.945({{σ _w }/{u^* }}}) {{z/L}})^{{1/4 where u^* = ( {{tau/ρ}}^{{1/2}}, σ w is the standard deviation of the vertical velocity, z is the height and L is the Obukhov scale lenght. The constants a, A, k and d n are the entrainment constant, the turbulence decay constant, Von Karman's constant, and the layer depth derived from the theory. Of these, a and A, are universal constants and not empirically determined for the boundary layer. Thus the turbulence needed for the plume model of convection, which resides above these layers and reaches to the inversion, is determined by the shear stress and the heat flux in the surface layers. This model applies to convection in cool air over a warm sea. The whole field is now determined except for the temperature of the air relative to the water, and the wind, which need a further parameter describing sea surface roughness. As a first stop to describing a surface where roughness elements
Jang, Hae-Won; Ih, Jeong-Guon
2012-04-01
The time domain boundary element method (BEM) is associated with numerical instability that typically stems from the time marching scheme. In this work, a formulation of time domain BEM is derived to deal with all types of boundary conditions adopting a multi-input, multi-output, infinite impulse response structure. The fitted frequency domain impedance data are converted into a time domain expression as a form of an infinite impulse response filter, which can also invoke a modeling error. In the calculation, the response at each time step is projected onto the wave vector space of natural radiation modes, which can be obtained from the eigensolutions of the single iterative matrix. To stabilize the computation, unstable oscillatory modes are nullified, and the same decay rate is used for two nonoscillatory modes. As a test example, a transient sound field within a partially lined, parallelepiped box is used, within which a point source is excited by an octave band impulse. In comparison with the results of the inverse Fourier transform of a frequency domain BEM, the average of relative difference norm in the stabilized time response is found to be 4.4%.
Diffusion mechanisms in grain boundaries in solids
International Nuclear Information System (INIS)
Peterson, N.L.
1982-01-01
A critical review is given of our current knowledge of grain-boundary diffusion in solids. A pipe mechanism of diffusion based on the well-established dislocation model seems most appropriate for small-angle boundaries. Open channels, which have atomic configurations somewhat like dislocation cores, probably play a major role in large-angle grain-boundary diffusion. Dissociated dislocations and stacking faults are not efficient paths for grain-boundary diffusion. The diffusion and computer modeling experiments are consistent with a vacancy mechanism of diffusion by a rather well-localized vacancy. The effective width of a boundary for grain-boundary diffusion is about two atomic planes. These general features of grain-boundary diffusion, deduced primarily from experiments on metals, are thought to be equally applicable for pure ceramic solids. The ionic character of many ceramic oxides may cause some differences in grain-boundary structure from that observed in metals, resulting in changes in grain-boundary diffusion behavior. 72 references, 5 figures
Conformal boundary state for the rectangular geometry
Energy Technology Data Exchange (ETDEWEB)
Bondesan, R., E-mail: roberto.bondesan@cea.fr [Institute de Physique Theorique, CEA Saclay, F-91191 Gif-sur-Yvette (France); LPTENS, Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris (France); Institut Henri Poincare, 11 rue Pierre et Marie Curie, 75231 Paris (France); Dubail, J. [Department of Physics, Yale University, P.O. Box 208120, New Haven, CT 06520-8120 (United States); Jacobsen, J.L. [LPTENS, Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris (France); Institut Henri Poincare, 11 rue Pierre et Marie Curie, 75231 Paris (France); Universite Pierre et Marie Curie, 4 place Jussieu, 75252 Paris (France); Saleur, H. [Institute de Physique Theorique, CEA Saclay, F-91191 Gif-sur-Yvette (France); Institut Henri Poincare, 11 rue Pierre et Marie Curie, 75231 Paris (France); Physics Department, USC, Los Angeles, CA 90089-0484 (United States)
2012-09-11
We discuss conformal field theories (CFTs) in rectangular geometries, and develop a formalism that involves a conformal boundary state for the 1+1d open system. We focus on the case of homogeneous boundary conditions (no insertion of a boundary condition changing operator), for which we derive an explicit expression of the associated boundary state, valid for any arbitrary CFT. We check the validity of our solution, comparing it with known results for partition functions, numerical simulations of lattice discretizations, and coherent state expressions for free theories.
Consistent boundary conditions for open strings
International Nuclear Information System (INIS)
Lindstroem, Ulf; Rocek, Martin; Nieuwenhuizen, Peter van
2003-01-01
We study boundary conditions for the bosonic, spinning (NSR) and Green-Schwarz open string, as well as for (1+1)-dimensional supergravity. We consider boundary conditions that arise from (1) extremizing the action, (2) BRST, rigid or local supersymmetry, or κ(Siegel)-symmetry of the action, (3) closure of the set of boundary conditions under the symmetry transformations, and (4) the boundary limits of bulk Euler-Lagrange equations that are 'conjugate' to other boundary conditions. We find corrections to Neumann boundary conditions in the presence of a bulk tachyon field. We discuss a boundary superspace formalism. We also find that path integral quantization of the open string requires an infinite tower of boundary conditions that can be interpreted as a smoothness condition on the doubled interval; we interpret this to mean that for a path-integral formulation of open strings with only Neuman boundary conditions, the description in terms of orientifolds is not just natural, but is actually fundamental
Boundary correlators in supergroup WZNW models
Energy Technology Data Exchange (ETDEWEB)
Creutzig, T.; Schomerus, V.
2008-04-15
We investigate correlation functions for maximally symmetric boundary conditions in the WZNW model on GL(11). Special attention is payed to volume filling branes. Generalizing earlier ideas for the bulk sector, we set up a Kac-Wakimotolike formalism for the boundary model. This first order formalism is then used to calculate bulk-boundary 2-point functions and the boundary 3-point functions of the model. The note ends with a few comments on correlation functions of atypical fields, point-like branes and generalizations to other supergroups. (orig.)
Integral Method of Boundary Characteristics: Neumann Condition
Kot, V. A.
2018-05-01
A new algorithm, based on systems of identical equalities with integral and differential boundary characteristics, is proposed for solving boundary-value problems on the heat conduction in bodies canonical in shape at a Neumann boundary condition. Results of a numerical analysis of the accuracy of solving heat-conduction problems with variable boundary conditions with the use of this algorithm are presented. The solutions obtained with it can be considered as exact because their errors comprise hundredths and ten-thousandths of a persent for a wide range of change in the parameters of a problem.
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...
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...... actors, and how knowledge is integrated across organizational boundaries. We discuss implications of our findings for managers and researchers in a business-to-business context...
Contaminant Boundary at the Faultless Underground Nuclear Test
International Nuclear Information System (INIS)
Greg Pohll; Karl Pohlmann; Jeff Daniels; Ahmed Hassan; Jenny Chapman
2003-01-01
The U.S. Department of Energy (DOE) and the Nevada Division of Environmental Protection (NDEP) have reached agreement on a corrective action strategy applicable to address the extent and potential impact of radionuclide contamination of groundwater at underground nuclear test locations. This strategy is described in detail in the Federal Facility Agreement and Consent Order (FFACO, 2000). As part of the corrective action strategy, the nuclear detonations that occurred underground were identified as geographically distinct corrective action units (CAUs). The strategic objective for each CAU is to estimate over a 1,000-yr time period, with uncertainty quantified, the three-dimensional extent of groundwater contamination that would be considered unsafe for domestic and municipal use. Two types of boundaries (contaminant and compliance) are discussed in the FFACO that will map the three-dimensional extent of radionuclide contamination. The contaminant boundary will identify the region wi th 95 percent certainty that contaminants do not exist above a threshold value. It will be prepared by the DOE and presented to NDEP. The compliance boundary will be produced as a result of negotiation between the DOE and NDEP, and can be coincident with, or differ from, the contaminant boundary. Two different thresholds are considered for the contaminant boundary. One is based on the enforceable National Primary Drinking Water Regulations for radionuclides, which were developed as a requirement of the Safe Drinking Water Act. The other is a risk-based threshold considering applicable lifetime excess cancer-risk-based criteria The contaminant boundary for the Faultless underground nuclear test at the Central Nevada Test Area (CNTA) is calculated using a newly developed groundwater flow and radionuclide transport model that incorporates aspects of both the original three-dimensional model (Pohlmann et al., 1999) and the two-dimensional model developed for the Faultless data decision
From boundaries to boundary work: middle managers creating inter-organizational change.
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.
Towards Adaptive Grids for Atmospheric Boundary-Layer Simulations
van Hooft, J. Antoon; Popinet, Stéphane; van Heerwaarden, Chiel C.; van der Linden, Steven J. A.; de Roode, Stephan R.; van de Wiel, Bas J. H.
2018-02-01
We present a proof-of-concept for the adaptive mesh refinement method applied to atmospheric boundary-layer simulations. Such a method may form an attractive alternative to static grids for studies on atmospheric flows that have a high degree of scale separation in space and/or time. Examples include the diurnal cycle and a convective boundary layer capped by a strong inversion. For such cases, large-eddy simulations using regular grids often have to rely on a subgrid-scale closure for the most challenging regions in the spatial and/or temporal domain. Here we analyze a flow configuration that describes the growth and subsequent decay of a convective boundary layer using direct numerical simulation (DNS). We validate the obtained results and benchmark the performance of the adaptive solver against two runs using fixed regular grids. It appears that the adaptive-mesh algorithm is able to coarsen and refine the grid dynamically whilst maintaining an accurate solution. In particular, during the initial growth of the convective boundary layer a high resolution is required compared to the subsequent stage of decaying turbulence. More specifically, the number of grid cells varies by two orders of magnitude over the course of the simulation. For this specific DNS case, the adaptive solver was not yet more efficient than the more traditional solver that is dedicated to these types of flows. However, the overall analysis shows that the method has a clear potential for numerical investigations of the most challenging atmospheric cases.
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.
Role of Grain Boundaries under Long-Time Radiation
Zhu, Yichao; Luo, Jing; Guo, Xu; Xiang, Yang; Chapman, Stephen Jonathan
2018-06-01
Materials containing a high proportion of grain boundaries offer significant potential for the development of radiation-resistant structural materials. However, a proper understanding of the connection between the radiation-induced microstructural behavior of a grain boundary and its impact at long natural time scales is still missing. In this Letter, point defect absorption at interfaces is summarized by a jump Robin-type condition at a coarse-grained level, wherein the role of interface microstructure is effectively taken into account. Then a concise formula linking the sink strength of a polycrystalline aggregate with its grain size is introduced and is well compared with experimental observation. Based on the derived model, a coarse-grained formulation incorporating the coupled evolution of grain boundaries and point defects is proposed, so as to underpin the study of long-time morphological evolution of grains induced by irradiation. Our simulation results suggest that the presence of point defect sources within a grain further accelerates its shrinking process, and radiation tends to trigger the extension of twin boundary sections.
Prosodic Boundaries in Writing: Evidence from a Keystroke Analysis.
Fuchs, Susanne; Krivokapić, Jelena
2016-01-01
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 overt 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 overt 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.
International Nuclear Information System (INIS)
Karlsson, L.; Norden, H.
1988-01-01
The distribution of elements and the precipitation behaviour at grain boundaries have been studied in boron containing AISI 316L and ''Mo-free AISI 316L'' type austenitic stainless steels. A combination of microanalytical techniques was used to study the boundary regions after cooling at 0.29-530 0 C/s from 800, 1075 or 1250 0 C. Tetragonal M/sub 2/B, M/sub 5/B/sub 3/ and M/sub 3/B/sub 2/, all rich in Fe, Cr and Mo, precipitated in the ''high B'' (40 ppm) AISI 316L steel whereas orthorhombic M/sub 2/B, rich in Cr and Fe was found in the ''Mo-free steel'' with 23 ppm B. In the ''high B steel'' a thin (<2nm), continuous layer, containing B, Cr, Mo and Fe and having a stoichiometry of typically M/sub 9/B, formed at boundaries after cooling at intermediate cooling rates. For both types of steels a boundary zone was found, after all heat treatments, with a composition differing significantly from the bulk composition. The differences were most marked after cooling at intermediate cooling rates. In both types of steel boundary depletion of Cr and enrichment of B and C occurred. It was found that non-equilibrium grain boundary segregation of boron can affect the precipitation behaviour by making the boundary composition enter a new phase field ''Non-equilibrium phases'' might also form. The synergistic effect of B and Mo on the boundary composition and precipitation behaviour, and the observed indications of C non-equilibrium segregation are discussed
Louisiana Territorial Boundary, Geographic NAD83, LDOTD (1999) [state_boundary_la_LDOTD_1999
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...
Boundary Conditions of Methamphetamine Craving
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
Perceptions of boundary ambiguity in the process of leaving an abusive partner.
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.
DEFF Research Database (Denmark)
Hong, Chuanshi; Huang, Xiaoxu; Winther, Grethe
2013-01-01
Previous studies have revealed that dislocation structures in metals with medium-to-high stacking fault energy, depend on the grain orientation and therefore on the slip systems. In the present work, the dislocations in eight slip-plane-aligned geometrically necessary boundaries (GNBs) in three...... expected active dominate. The dislocations predicted inactive are primarily attributed to dislocation reactions in the boundary. Two main types of dislocation networks in the boundaries were identified: (1) a hexagonal network of the three dislocations in the slip plane with which the boundary was aligned......; two of these come from the active slip systems, the third is attributed to dislocation reactions (2) a network of three dislocations from both of the active slip planes; two of these react to form Lomer locks. The results indicate a systematic boundary formation process for the GNBs. Redundant...
Composition-Driven Phase Boundary and Piezoelectricity in Potassium-Sodium Niobate-Based Ceramics.
Zheng, Ting; Wu, Jiagang; Xiao, Dingquan; Zhu, Jianguo; Wang, Xiangjian; Lou, Xiaojie
2015-09-16
The piezoelectricity of (K,Na)NbO3 ceramics strongly depends on the phase boundary types as well as the doped compositions. Here, we systematically studied the relationships between the compositions and phase boundary types in (K,Na) (Nb,Sb)O3-Bi0.5Na0.5AO3 (KNNS-BNA, A=Hf, Zr, Ti, Sn) ceramics; then their piezoelectricity can be readily modified. Their phase boundary types are determined by the doped elements. A rhombohedral-tetragonal (R-T) phase boundary can be driven in the compositions range of 0.035≤BNH≤0.040 and 0.035≤BNZ≤0.045; an orthorhombic-tetragonal (O-T) phase boundary is formed in the composition range of 0.005≤BNT≤0.02; and a pure O phase can be only observed regardless of BNS content (≤0.01). In addition, the phase boundary types strongly affect their corresponding piezoelectricities. A larger d33 (∼440-450 pC/N) and a higher d33* (∼742-834 pm/V) can be attained in KNNS-BNA (A=Zr and Hf) ceramics due to the involvement of R-T phase boundary, and unfortunately KNNS-BNA (A=Sn and Ti) ceramics possess a relatively poor piezoelectricity (d33≤200 and d33*piezoelectricity and phase boundary types were also discussed. We believe that comprehensive research can design more excellent ceramic systems concerning potassium-sodium niobate.
Horses for courses: analytical tools to explore planetary boundaries
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).
2010-01-01
... cutting across the heads of Nitnat, Juan de Fuca and Quinault Canyons. The coastal boundary of the Sanctuary is the mean higher high water line when adjacent to Federally managed lands cutting across the... from the Sanctuary boundary shoreward of the International Collision at Sea regulation (Colreg...
Recent advances in boundary element methods
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).
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.
Modelling stable atmospheric boundary layers over snow
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
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...
Grain boundaries in high temperature superconductors
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
Comments on Hypersonic Boundary-Layer Transition
1990-09-01
mechanism by which boundary-layer disturbance growth is generally initiated and establishes the initial distur- banca amplitude at the onset of disturbance...Patankar, S. V., and Spalding, P. B., Heat and Mass Transfer in Boundary Lavers, CRC Press , Cleveland, Ohio, 1968. 87. Neumann, R. D., and Patterson, .J. 1
Finite-volume discretizations and immersed boundaries
Y.J. Hassen (Yunus); B. Koren (Barry)
2009-01-01
htmlabstractIn this chapter, an accurate method, using a novel immersed-boundary approach, is presented for numerically solving linear, scalar convection problems. As is standard in immersed-boundary methods, moving bodies are embedded in a fixed `Cartesian' grid. The essence of the present method
Finite-volume discretizations and immersed boundaries
Y.J. Hassen (Yunus); B. Koren (Barry)
2010-01-01
textabstractIn this chapter, an accurate method, using a novel immersed-boundary approach, is presented for numerically solving linear, scalar convection problems. As is standard in immersed-boundary methods, moving bodies are embedded in a fixed Cartesian grid. The essence of the present method is
Polyakov's quantized string with boundary terms
International Nuclear Information System (INIS)
Durhuus, B.; Olesen, P.; Petersen, J.L.
1981-11-01
The authors compute the boundary terms needed in Polyakov's method for calculating averages of functionals defined on surfaces. The method used is due to Seeley, who found recursive relations yielding the boundary terms. These relations are solved for a general second order elliptic differential operator. This solution is then applied to Polyakov's problem. (Auth.)
Polyakov's quantized string with boundary terms
International Nuclear Information System (INIS)
Durhuus, B.; Olesen, P.; Petersen, J.L.
1982-01-01
We compute the boundary terms due to the conformal anomaly which are needed in Polyakov's method of calculating averages of functionals defined on surfaces. The method we use is due to Seeley, who found recursive relations yielding the boundary terms. We solve these relations for a general second-order elliptic differential operator. This solution is then applied to Polyakov's problem. (orig.)
Chromoproteinoids and their ability to form boundary
International Nuclear Information System (INIS)
Heinz, B.
1992-01-01
Model systems for boundary structures and cellular systems, particularly when they are a result of natural simulation experiments, are always valuable for the study of the ''Origins of Life''. Lyophilization of chromoproteinoids - peptide like molecules containing prosthetic groups - leads to the formation of boundary structures
Boundary Management for Cognitive Behavioral Therapies
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…
Suction of MHD boundary layer flows
International Nuclear Information System (INIS)
Rao, B.N.
1985-01-01
The boundary layer growth with tensor electrical conductivity and the transpiration number has been examined using local nonsimilarity solutions method. It is found that suction will cause the increase in wall shearing stress and decrease in thicknesses of the boundary layer. (Auth.)
Professional boundary violations: a literature review.
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.
2010-01-01
... a distance of approximately six nmi from the following islands and offshore rocks: San Miguel Island... Rock (the Islands). The seaward boundary coordinates are listed in Appendix A to this subpart. [74 FR... MARINE SANCTUARY PROGRAM REGULATIONS Channel Islands National Marine Sanctuary § 922.70 Boundary. The...
2010-01-01
..., surrounding the Farallon Islands (and Noonday Rock) off the northern coast of California. The northernmost... MARINE SANCTUARY PROGRAM REGULATIONS Gulf of the Farallones National Marine Sanctuary § 922.80 Boundary. The Gulf of the Farallones National Marine Sanctuary (Sanctuary) boundary encompasses a total area of...
DYNAMIC SURFACE BOUNDARY-CONDITIONS - A SIMPLE BOUNDARY MODEL FOR MOLECULAR-DYNAMICS SIMULATIONS
JUFFER, AH; BERENDSEN, HJC
1993-01-01
A simple model for the treatment of boundaries in molecular dynamics simulations is presented. The method involves the positioning of boundary atoms on a surface that surrounds a system of interest. The boundary atoms interact with the inner region and represent the effect of atoms outside the
Model-based estimation with boundary side information or boundary regularization
International Nuclear Information System (INIS)
Chiao, P.C.; Rogers, W.L.; Fessler, J.A.; Clinthorne, N.H.; Hero, A.O.
1994-01-01
The authors have previously developed a model-based strategy for joint estimation of myocardial perfusion and boundaries using ECT (Emission Computed Tomography). The authors have also reported difficulties with boundary estimation in low contrast and low count rate situations. In this paper, the authors propose using boundary side information (obtainable from high resolution MRI and CT images) or boundary regularization to improve both perfusion and boundary estimation in these situations. To fuse boundary side information into the emission measurements, the authors formulate a joint log-likelihood function to include auxiliary boundary measurements as well as ECT projection measurements. In addition, the authors introduce registration parameters to align auxiliary boundary measurements with ECT measurements and jointly estimate these parameters with other parameters of interest from the composite measurements. In simulated PET O-15 water myocardial perfusion studies using a simplified model, the authors show that the joint estimation improves perfusion estimation performance and gives boundary alignment accuracy of <0.5 mm even at 0.2 million counts. The authors implement boundary regularization through formulating a penalized log-likelihood function. The authors also demonstrate in simulations that simultaneous regularization of the epicardial boundary and myocardial thickness gives comparable perfusion estimation accuracy with the use of boundary side information
Chiao, P C; Rogers, W L; Fessler, J A; Clinthorne, N H; Hero, A O
1994-01-01
The authors have previously developed a model-based strategy for joint estimation of myocardial perfusion and boundaries using ECT (emission computed tomography). They have also reported difficulties with boundary estimation in low contrast and low count rate situations. Here they propose using boundary side information (obtainable from high resolution MRI and CT images) or boundary regularization to improve both perfusion and boundary estimation in these situations. To fuse boundary side information into the emission measurements, the authors formulate a joint log-likelihood function to include auxiliary boundary measurements as well as ECT projection measurements. In addition, they introduce registration parameters to align auxiliary boundary measurements with ECT measurements and jointly estimate these parameters with other parameters of interest from the composite measurements. In simulated PET O-15 water myocardial perfusion studies using a simplified model, the authors show that the joint estimation improves perfusion estimation performance and gives boundary alignment accuracy of <0.5 mm even at 0.2 million counts. They implement boundary regularization through formulating a penalized log-likelihood function. They also demonstrate in simulations that simultaneous regularization of the epicardial boundary and myocardial thickness gives comparable perfusion estimation accuracy with the use of boundary side information.
A two-dimensional embedded-boundary method for convection problems with moving boundaries
Y.J. Hassen (Yunus); B. Koren (Barry)
2010-01-01
htmlabstractIn this work, a two-dimensional embedded-boundary algorithm for convection problems is presented. A moving body of arbitrary boundary shape is immersed in a Cartesian finite-volume grid, which is fixed in space. The boundary surface is reconstructed in such a way that only certain fluxes
Boundary conditions for the gravitational field
International Nuclear Information System (INIS)
Winicour, Jeffrey
2012-01-01
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') (topical review)
BSLIC: SLIC Superpixels Based on Boundary Term
Directory of Open Access Journals (Sweden)
Hai Wang
2017-02-01
Full Text Available A modified method for better superpixel generation based on simple linear iterative clustering (SLIC is presented and named BSLIC in this paper. By initializing cluster centers in hexagon distribution and performing k-means clustering in a limited region, the generated superpixels are shaped into regular and compact hexagons. The additional cluster centers are initialized as edge pixels to improve boundary adherence, which is further promoted by incorporating the boundary term into the distance calculation of the k-means clustering. Berkeley Segmentation Dataset BSDS500 is used to qualitatively and quantitatively evaluate the proposed BSLIC method. Experimental results show that BSLIC achieves an excellent compromise between boundary adherence and regularity of size and shape. In comparison with SLIC, the boundary adherence of BSLIC is increased by at most 12.43% for boundary recall and 3.51% for under segmentation error.
Boundary element method for modelling creep behaviour
International Nuclear Information System (INIS)
Zarina Masood; Shah Nor Basri; Abdel Majid Hamouda; Prithvi Raj Arora
2002-01-01
A two dimensional initial strain direct boundary element method is proposed to numerically model the creep behaviour. The boundary of the body is discretized into quadratic element and the domain into quadratic quadrilaterals. The variables are also assumed to have a quadratic variation over the elements. The boundary integral equation is solved for each boundary node and assembled into a matrix. This matrix is solved by Gauss elimination with partial pivoting to obtain the variables on the boundary and in the interior. Due to the time-dependent nature of creep, the solution has to be derived over increments of time. Automatic time incrementation technique and backward Euler method for updating the variables are implemented to assure stability and accuracy of results. A flowchart of the solution strategy is also presented. (Author)
Boundary Hamiltonian Theory for Gapped Topological Orders
Hu, Yuting; Wan, Yidun; Wu, Yong-Shi
2017-06-01
We report our systematic construction of the lattice Hamiltonian model of topological orders on open surfaces, with explicit boundary terms. We do this mainly for the Levin-Wen string-net model. The full Hamiltonian in our approach yields a topologically protected, gapped energy spectrum, with the corresponding wave functions robust under topology-preserving transformations of the lattice of the system. We explicitly present the wavefunctions of the ground states and boundary elementary excitations. The creation and hopping operators of boundary quasi-particles are constructed. It is found that given a bulk topological order, the gapped boundary conditions are classified by Frobenius algebras in its input data. Emergent topological properties of the ground states and boundary excitations are characterized by (bi-) modules over Frobenius algebras.
The boundary characteristics of lucid dreamers.
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.
Optimization of boundary controls of string vibrations
Energy Technology Data Exchange (ETDEWEB)
Il' in, V A; Moiseev, E I [Department of Computing Mathematics and Cybernetics, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)
2005-12-31
For a large time interval T boundary controls of string vibrations are optimized in the following seven boundary-control problems: displacement control at one end (with the other end fixed or free); displacement control at both ends; elastic force control at one end (with the other end fixed or free); elastic force control at both ends; combined control (displacement control at one end and elastic force control at the other). Optimal boundary controls in each of these seven problems are sought as functions minimizing the corresponding boundary-energy integral under the constraints following from the initial and terminal conditions for the string at t=0 and t=T, respectively. For all seven problems, the optimal boundary controls are written out in closed analytic form.
A question of fit: reflections on boundaries, organizations and social-ecological systems.
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
Analytic Solution to Shell Boundary – Value Problems
Directory of Open Access Journals (Sweden)
Yu. I. Vinogradov
2015-01-01
Full Text Available Object of research is to find analytical solution to the shell boundary – value problems, i.e. to consider the solution for a class of problems concerning the mechanics of hoop closed shells strain.The objective of work is to create an analytical method to define a stress – strain state of shells under non-axisymmetric loading. Thus, a main goal is to derive the formulas – solutions of the linear ordinary differential equations with variable continuous coefficients.The partial derivative differential equations of mechanics of shells strain by Fourier's method of variables division are reduced to the system of the differential equations with ordinary derivatives. The paper presents the obtained formulas to define solutions of the uniform differential equations and received on their basis formulas to define a particular solution depending on a type of the right parts of the differential equations.The analytical algorithm of the solution of a boundary task uses an approach to transfer the boundary conditions to the randomly chosen point of an interval of changing independent variable through the solution of the canonical matrix ordinary differential equation with the subsequent solution of system of algebraic equations for compatibility of boundary conditions at this point. Efficiency of algorithm is based on the fact that the solution of the ordinary differential equations is defined as the values of Cauchy – Krylova functions, which meet initial arbitrary conditions.The results of researches presented in work are useful to experts in the field of calculus mathematics, dealing with solution of systems of linear ordinary differential equations and creation of effective analytical computing methods to solve shell boundary – value problems.
On some boundary value problems in quantum statistical mechanics
International Nuclear Information System (INIS)
Angelescu, N.
1978-01-01
The following two topics of equilibrium quantum statistical mechanics are discussed in this thesis: (i) the independence of the thermodynamic limit of grand-canonical pressure on the boundary conditions; (ii) the magnetic properties of free quantum gases. Problem (i) is handled with a functional integration technique. Wiener-type conditional measures are constructed for a given domain and a general class of mixed conditions on its boundary, these measures are used to write down Feynman-Kac formulae for the kernels of exp(-βH), where H is the Hamiltonian of N interacting particles in the given domain. These measures share the property that they assign the same mass as the usual Wiener measure to any set of trajectories not intersecting the boundary. Local estimates on the kernels of exp(-βH) are derived, which imply independence of the pressure on the boundary conditions in the thermodynamic limit. Problem (ii) has a historical development: since Landau's work (1930), much discussion has been devoted to the influence of the finite size on the susceptibility. In finite volume, Dirichlet boundary conditions are imposed, on the ground that they ensure gauge invariance. The thermodynamic limit of the pressure is proved, using again functional integration. The functional measure is now complex but absolutely continuous with respect to Wiener measure, so the usual local estimates hold true. The controversy in the literature was concentrated on the commutativity of the operations of H-derivation and thermodynamic limit, so the existence of this limit for the zero-field susceptibility and its surface term are proved separately, demonstrating this commutativity. The proof relies on the following result of independent interest: the perturbation theory of self-adjoint trace-class semigroups is trace-class convergent and analytic. (author)
Influences of triple junctions on stress-assisted grain boundary motion in nanocrystalline materials
International Nuclear Information System (INIS)
Aramfard, Mohammad; Deng, Chuang
2014-01-01
Stress-assisted grain boundary motion is among the most studied modes of microstructural evolution in crystalline materials. In this study, molecular dynamics simulations were used to systematically investigate the influences of triple junctions on the stress-assisted motion of symmetric tilt grain boundaries in Cu by considering a honeycomb nanocrystalline model. It was found that the grain boundary motion in nanocrystalline models was highly sensitive to the loading mode, and a strong coupling effect which was prevalent in bicrystal models was only observed when simple shear was applied. In addition, the coupling factor extracted from the honeycomb model was found to be larger and more sensitive to temperature change than that from bicrystal models for the same type of grain boundary under the same loading conditions. Furthermore, the triple junctions seemed to exhibit unusual asymmetric pinning effects to the migrating grain boundary and the constraints by the triple junctions and neighboring grains led to remarkable non-linear grain boundary motion in directions both parallel and normal to the applied shear, which was in stark contrast to that observed in bicrystal models. In addition, dislocation nucleation and propagation, which were absent in the bicrystal model, were found to play an important role on shear-induced grain boundary motion when triple junctions were present. In the end, a generalized model for shear-assisted grain boundary motion was proposed based on the findings from this research. (paper)
Study of rapid grain boundary migration in a nanocrystalline Ni thin film
International Nuclear Information System (INIS)
Kacher, Josh; Robertson, I.M.; Nowell, Matt; Knapp, J.; Hattar, Khalid
2011-01-01
Research highlights: → Abnormal growth is distributed randomly in the foil and initiates at different times. → Growth occurs from seemingly uncorrelated regions of the grain boundary. → Growth twins are created during all stages of abnormal grain growth. → Grain growth patterns are qualitatively similar to a vacancy diffusion model. → Grain boundaries and orientations evolve during growth to minimize system energy. - Abstract: Grain boundary migration associated with abnormal grain growth in pulsed-laser deposited Ni was studied in real time by annealing electron transparent films in situ in the transmission electron microscope. The resulting texture evolution and grain boundary types produced were evaluated by ex situ electron backscatter diffraction of interrupted anneals. The combination of these two techniques allowed for the investigation of grain growth rates, grain morphologies, and the evolution of the orientation and grain boundary distributions. Grain boundaries were found to progress in a sporadic, start/stop fashion with no evidence of a characteristic grain growth rate. The orientations of the abnormally growing grains were found to be predominately //ND throughout the annealing process. A high fraction of twin boundaries developed during the annealing process. The intermittent growth from different locations of the grain boundary is discussed in terms of a vacancy diffusion model for grain growth.
Long-lived force patterns and deformation waves at repulsive epithelial boundaries
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.
Grain-boundary microchemistry and intergranular cracking of irradiated austenitic stainless steels
International Nuclear Information System (INIS)
Chung, H.M.; Ruther, W.E.; Sanecki, J.E.; Kassner, T.F.
1993-01-01
Constant-extension-rate tensile tests and grain-boundary analysis by Auger electron spectroscopy were conducted on high and commercial-purity (HP and CP) Type 304 stainless steel (SS) specimens from irradiated boiling-water reactor (BWR) components to identify the mechanisms of irradiation-assisted stress corrosion cracking (IASCC). Contrary to previous beliefs, susceptibility to intergranular fracture could not be correlated with radiation-induced segregation of impurities such as Si, P, C, or S, but a correlation was obtained with grain-boundary Cr concentration, indicating a role for Cr depletion. Detailed analysis of grain-boundary chemistry was conducted on BWR neutron absorber tubes that were fabricated from two similar heats of HP Type 304 SS of virtually identical bulk chemical composition but exhibiting a significant difference in susceptibility to IASCC after irradiation to ∼2 x 10 21 n/cm 2 (E > 1 MeV). Grain-boundary concentrations of Cr Ni, Si, P, S, and C of the cracking-resistant and -susceptible HP heats were virtually identical. However, grain boundaries of the cracking-resistant material contained less N and more B and Li than those of the cracking-susceptible material. This observation indicates that, besides the deleterious effect of grain-boundary Cr depletion, a synergism between grain-boundary segregation of N and B and transmutation to H and Li plays an important role in IASCC
An(1) affine Toda field theories with integrable boundary conditions revisited
International Nuclear Information System (INIS)
Doikou, Anastasia
2008-01-01
Generic classically integrable boundary conditions for the A n (1) affine Toda field theories (ATFT) are investigated. The present analysis rests primarily on the underlying algebra, defined by the classical version of the reflection equation. We use as a prototype example the first non-trivial model of the hierarchy i.e. the A 2 (1) ATFT, however our results may be generalized for any A n (1) (n > 1). We assume here two distinct types of boundary conditions called some times soliton preserving (SP), and soliton non-preserving (SNP) associated to two distinct algebras, i.e. the reflection algebra and the (q) twisted Yangian respectively. The boundary local integrals of motion are then systematically extracted from the asymptotic expansion of the associated transfer matrix. In the case of SNP boundary conditions we recover previously known results. The other type of boundary conditions (SP), associated to the reflection algebra, are novel in this context and lead to a different set of conserved quantities that depend on free boundary parameters. It also turns out that the number of local integrals of motion for SP boundary conditions is 'double' compared to those of the SNP case.
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.
Boundary-value problems with free boundaries for elliptic systems of equations
Monakhov, V N
1983-01-01
This book is concerned with certain classes of nonlinear problems for elliptic systems of partial differential equations: boundary-value problems with free boundaries. The first part has to do with the general theory of boundary-value problems for analytic functions and its applications to hydrodynamics. The second presents the theory of quasiconformal mappings, along with the theory of boundary-value problems for elliptic systems of equations and applications of it to problems in the mechanics of continuous media with free boundaries: problems in subsonic gas dynamics, filtration theory, and problems in elastico-plasticity.
Matrix factorisations for rational boundary conditions by defect fusion
International Nuclear Information System (INIS)
Behr, Nicolas; Fredenhagen, Stefan
2015-01-01
A large class of two-dimensional N=(2,2) superconformal field theories can be understood as IR fixed-points of Landau-Ginzburg models. In particular, there are rational conformal field theories that also have a Landau-Ginzburg description. To understand better the relation between the structures in the rational conformal field theory and in the Landau-Ginzburg theory, we investigate how rational B-type boundary conditions are realised as matrix factorisations in the SU(3)/U(2) Grassmannian Kazama-Suzuki model. As a tool to generate the matrix factorisations we make use of a particular interface between the Kazama-Suzuki model and products of minimal models, whose fusion can be realised as a simple functor on ring modules. This allows us to formulate a proposal for all matrix factorisations corresponding to rational boundary conditions in the SU(3)/U(2) model.
Boundary Control of Linear Evolution PDEs - Continuous and Discrete
DEFF Research Database (Denmark)
Rasmussen, Jan Marthedal
2004-01-01
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...... of literature exists in the area of theoretical results concerning control of partial differential equations. The results have included existence and uniqueness of controls, minimum time requirements, regularity of domains, and many others. Another huge research field is that of control theory for ordinary di...... 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...
Vortex Formation During Unsteady Boundary-Layer Separation
Das, Debopam; Arakeri, Jaywant H.
1998-11-01
Unsteady laminar boundary-layer separation is invariably accompanied by the formation of vortices. The aim of the present work is to study the vortex formation mechanism(s). An adverse pressure gradient causing a separation can be decomposed into a spatial component ( spatial variation of the velocity external to the boundary layer ) and a temporal component ( temporal variation of the external velocity ). Experiments were conducted in a piston driven 2-D water channel, where the spatial component could be be contolled by geometry and the temporal component by the piston motion. We present results for three divergent channel geometries. The piston motion consists of three phases: constant acceleration from start, contant velocity, and constant deceleration to stop. Depending on the geometry and piston motion we observe different types of unsteady separation and vortex formation.
Matrix factorisations for rational boundary conditions by defect fusion
Energy Technology Data Exchange (ETDEWEB)
Behr, Nicolas [Department of Mathematics, Heriot-Watt University,Riccarton, Edinburgh, EH14 4AS (United Kingdom); Maxwell Institute for Mathematical Sciences,Edinburgh (United Kingdom); Fredenhagen, Stefan [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut,D-14424 Golm (Germany)
2015-05-11
A large class of two-dimensional N=(2,2) superconformal field theories can be understood as IR fixed-points of Landau-Ginzburg models. In particular, there are rational conformal field theories that also have a Landau-Ginzburg description. To understand better the relation between the structures in the rational conformal field theory and in the Landau-Ginzburg theory, we investigate how rational B-type boundary conditions are realised as matrix factorisations in the SU(3)/U(2) Grassmannian Kazama-Suzuki model. As a tool to generate the matrix factorisations we make use of a particular interface between the Kazama-Suzuki model and products of minimal models, whose fusion can be realised as a simple functor on ring modules. This allows us to formulate a proposal for all matrix factorisations corresponding to rational boundary conditions in the SU(3)/U(2) model.
Diffusive boundary layers at the bottom of gaps and cracks
Etzold, Merlin A.; Landel, Julien R.; Dalziel, Stuart B.
2017-11-01
This work is motivated by the chemical decontamination of droplets of chemical warfare agents trapped in the gaps and cracks found in most man-made objects. We consider axial laminar flow within gaps with both straight and angled walls. We study the diffusive mass transfer from a source (e.g. a droplet surface) located at the bottom of the gap. This problem is similar to boundary layers and Graetz-type problems (heat transfer in pipe flow) with the added complication of a non-uniform lateral concentration profile due to the lateral variation of the velocity profile. We present 3D solutions for the diffusive boundary layer and demonstrate that a 2D mean-field model, for which we calculate series and similarity solutions, captures the essential physics. We demonstrate the immediate practical relevance of our findings by comparing decontamination of a droplet located in a gap and on an exposed surface.
High-Reynolds Number Viscous Flow Simulations on Embedded-Boundary Cartesian Grids
2016-05-05
AFRL-AFOSR-VA-TR-2016-0192 High- Reynolds Number Viscous Flow Simulations on Embedded-Boundary Cartesian Grids Marsha Berger NEW YORK UNIVERSITY Final...TO THE ABOVE ORGANIZATION. 1. REPORT DATE (DD-MM-YYYY) 30/04/2016 2. REPORT TYPE Final 3. DATES COVERED (From - To) High- Reynolds 4. TITLE AND...SUBTITLE High- Reynolds Number Viscous Flow Simulations on Embedded-Boundary Cartesian Grids 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-13-1
Grain boundary corrosion of copper canister material
International Nuclear Information System (INIS)
Fennell, P.A.H.; Graham, A.J.; Smart, N.R.; Sofield, C.J.
2001-03-01
The proposed design for a final repository for spent fuel and other long-lived residues in Sweden is based on the multi-barrier principle. The waste will be encapsulated in sealed cylindrical canisters, which will then be placed in granite bedrock and surrounded by compacted bentonite clay. The canister design is based on a thick cast inner container fitted inside a corrosion-resistant copper canister. During fabrication of the outer copper canisters there will be some unavoidable grain growth in the welded areas. As grains grow they will tend to concentrate impurities within the copper at the new grain boundaries. The work described in this report was undertaken to determine whether there is any possibility of enhanced corrosion at grain boundaries within the copper canister. The potential for grain boundary corrosion was investigated by exposing copper specimens, which had undergone different heat treatments and hence had different grain sizes, to aerated artificial bentonite-equilibrated groundwater with two concentrations of chloride, for increasing periods of time. The degree of grain boundary corrosion was determined by atomic force microscopy (AFM) and optical microscopy. AFM showed no increase in grain boundary 'ditching' for low chloride groundwater. In high chloride groundwater the surface was covered uniformly with a fine-grained oxide. No increases in oxide thickness were observed. No significant grain boundary attack was observed using optical microscopy either. The work suggests that in aerated artificial groundwaters containing chloride ions, grain boundary corrosion of copper is unlikely to adversely affect SKB's copper canisters
Critical boundary sine-Gordon revisited
International Nuclear Information System (INIS)
Hasselfield, M.; Lee, Taejin; Semenoff, G.W.; Stamp, P.C.E.
2006-01-01
We revisit the exact solution of the two space-time dimensional quantum field theory of a free massless boson with a periodic boundary interaction and self-dual period. We analyze the model by using a mapping to free fermions with a boundary mass term originally suggested in Ref. [J. Polchinski, L. Thorlacius, Phys. Rev. D 50 (1994) 622]. We find that the entire SL (2, C) family of boundary states of a single boson are boundary sine-Gordon states and we derive a simple explicit expression for the boundary state in fermion variables and as a function of sine-Gordon coupling constants. We use this expression to compute the partition function. We observe that the solution of the model has a strong-weak coupling generalization of T-duality. We then examine a class of recently discovered conformal boundary states for compact bosons with radii which are rational numbers times the self-dual radius. These have simple expression in fermion variables. We postulate sine-Gordon-like field theories with discrete gauge symmetries for which they are the appropriate boundary states
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...... and polycrystals of fcc metals in three deformation modes (rolling, tension and torsion). In the macroscopic system, boundaries lie close to the macroscopically most stressed planes. In the crystallographic system, the boundary plane depends on the grain/crystal orientation. The boundary planes in both co......-ordinate systems are rationalised based on the slip. The more the slip is concentrated on a slip plane, the closer the boundaries lie to this. The macroscopic preference arises from the macroscopic directionality of the slip. The established relations are applied to (a) prediction of boundary planes from slip...
From affine Hecke algebras to boundary symmetries
International Nuclear Information System (INIS)
Doikou, Anastasia
2005-01-01
Motivated by earlier works we employ appropriate realizations of the affine Hecke algebra and we recover previously known non-diagonal solutions of the reflection equation for the U q (gl n -bar ) case. The corresponding N site spin chain with open boundary conditions is then constructed and boundary non-local charges associated to the non-diagonal solutions of the reflection equation are derived, as coproduct realizations of the reflection algebra. With the help of linear intertwining relations involving the aforementioned solutions of the reflection equation, the symmetry of the open spin chain with the corresponding boundary conditions is exhibited, being essentially a remnant of the U q (gl n -bar ) algebra. More specifically, we show that representations of certain boundary non-local charges commute with the generators of the affine Hecke algebra and with the local Hamiltonian of the open spin chain for a particular choice of boundary conditions. Furthermore, we are able to show that the transfer matrix of the open spin chain commutes with a certain number of boundary non-local charges, depending on the choice of boundary conditions
Lattice Boltzmann methods for moving boundary flows
International Nuclear Information System (INIS)
Inamuro, Takaji
2012-01-01
The lattice Boltzmann methods (LBMs) for moving boundary flows are presented. The LBM for two-phase fluid flows with the same density and the LBM combined with the immersed boundary method are described. In addition, the LBM on a moving multi-block grid is explained. Three numerical examples (a droplet moving in a constricted tube, the lift generation of a flapping wing and the sedimentation of an elliptical cylinder) are shown in order to demonstrate the applicability of the LBMs to moving boundary problems. (invited review)
Lattice Boltzmann methods for moving boundary flows
Energy Technology Data Exchange (ETDEWEB)
Inamuro, Takaji, E-mail: inamuro@kuaero.kyoto-u.ac.jp [Department of Aeronautics and Astronautics, and Advanced Research Institute of Fluid Science and Engineering, Graduate School of Engineering, Kyoto University, Kyoto 606-8501 (Japan)
2012-04-01
The lattice Boltzmann methods (LBMs) for moving boundary flows are presented. The LBM for two-phase fluid flows with the same density and the LBM combined with the immersed boundary method are described. In addition, the LBM on a moving multi-block grid is explained. Three numerical examples (a droplet moving in a constricted tube, the lift generation of a flapping wing and the sedimentation of an elliptical cylinder) are shown in order to demonstrate the applicability of the LBMs to moving boundary problems. (invited review)
More on boundary holographic Witten diagrams
Sato, Yoshiki
2018-01-01
In this paper we discuss geodesic Witten diagrams in general holographic conformal field theories with boundary or defect. In boundary or defect conformal field theory, two-point functions are nontrivial and can be decomposed into conformal blocks in two distinct ways; ambient channel decomposition and boundary channel decomposition. In our previous work [A. Karch and Y. Sato, J. High Energy Phys. 09 (2017) 121., 10.1007/JHEP09(2017)121] we only consider two-point functions of same operators. We generalize our previous work to a situation where operators in two-point functions are different. We obtain two distinct decomposition for two-point functions of different operators.
Identifying Phase Space Boundaries with Voronoi Tessellations
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.
Boundary value problems and partial differential equations
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
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.
Measurements in a synthetic turbulent boundary layer
Arakeri, J. H.; Coles, D. E.
Some measurements in a synthetic turbulent boundary layer (SBL) are reported. The main diagnostic tool is an X-wire probe. The velocity of the large eddies is determined to be 0.842 times the freestream velocity. The mean properties of the SBL are reasonably close to those of a natural turbulent boundary layer. The large eddy in the SBL appears to be a pair of counterrotating eddies in the stream direction, inclined at a shallow angle and occupying much of the boundary-layer thickness.
Crossing Boundaries in Global Software Development
DEFF Research Database (Denmark)
Søderberg, Anne-Marie; Romani, Laurence
across cultures, languages, organizational boundaries, time zones and geographical distances. The paper revises a framework of boundary spanning leadership practices developed for MNCs and adapts it to an offshore outsourcing context. It also contributes with reflections on how imbalances of resources......Western companies´ offshore outsourcing is increasingly being replaced by strategic partnerships that require closer collaboration between client and vendor. This paper addresses the question: How does a vendor company from an emergent market deal with inter-organizational boundary spanning...
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.
Optimal Wentzell Boundary Control of Parabolic Equations
International Nuclear Information System (INIS)
Luo, Yousong
2017-01-01
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.
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.
Longitudinal vortices in a transitioning boundary layer
International Nuclear Information System (INIS)
Anders, J.B.; Backwelder, R.F.
1980-01-01
Naturally occurring spanwise variations of the streamwise velocity component, characteristic of longitudinal vortices embedded in a transitioning boundary layer were explored using hot-wire anemometers. A vibrating ribbon introduced stable or unstable Tollmien-Schlichting waves into the laminar boundary layer. These damped or growing disturbances always developed a strong three-dimensional pattern even though no spanwise perturbations were artificially induced. Changing the radius of the leading edge and other modifications to the flat plate, wind tunnel and boundary layer did not alter the spanwise wavelength of the vortices. (orig.)
Fundamental solutions and dual boundary element methods for fracture in plane Cosserat elasticity.
Atroshchenko, Elena; Bordas, Stéphane P A
2015-07-08
In this paper, both singular and hypersingular fundamental solutions of plane Cosserat elasticity are derived and given in a ready-to-use form. The hypersingular fundamental solutions allow to formulate the analogue of Somigliana stress identity, which can be used to obtain the stress and couple-stress fields inside the domain from the boundary values of the displacements, microrotation and stress and couple-stress tractions. Using these newly derived fundamental solutions, the boundary integral equations of both types are formulated and solved by the boundary element method. Simultaneous use of both types of equations (approach known as the dual boundary element method (BEM)) allows problems where parts of the boundary are overlapping, such as crack problems, to be treated and to do this for general geometry and loading conditions. The high accuracy of the boundary element method for both types of equations is demonstrated for a number of benchmark problems, including a Griffith crack problem and a plate with an edge crack. The detailed comparison of the BEM results and the analytical solution for a Griffith crack and an edge crack is given, particularly in terms of stress and couple-stress intensity factors, as well as the crack opening displacements and microrotations on the crack faces and the angular distributions of stresses and couple-stresses around the crack tip.
Wang, Lei; Dai, Cheng; Xue, Liang
2018-04-01
This study presents a Laplace-transform-based boundary element method to model the groundwater flow in a heterogeneous confined finite aquifer with arbitrarily shaped boundaries. The boundary condition can be Dirichlet, Neumann or Robin-type. The derived solution is analytical since it is obtained through the Green's function method within the domain. However, the numerical approximation is required on the boundaries, which essentially renders it a semi-analytical solution. The proposed method can provide a general framework to derive solutions for zoned heterogeneous confined aquifers with arbitrarily shaped boundary. The requirement of the boundary element method presented here is that the Green function must exist for a specific PDE equation. In this study, the linear equations for the two-zone and three-zone confined aquifers with arbitrarily shaped boundary is established in Laplace space, and the solution can be obtained by using any linear solver. Stehfest inversion algorithm can be used to transform it back into time domain to obtain the transient solution. The presented solution is validated in the two-zone cases by reducing the arbitrarily shaped boundaries to circular ones and comparing it with the solution in Lin et al. (2016, https://doi.org/10.1016/j.jhydrol.2016.07.028). The effect of boundary shape and well location on dimensionless drawdown in two-zone aquifers is investigated. Finally the drawdown distribution in three-zone aquifers with arbitrarily shaped boundary for constant-rate tests (CRT) and flow rate distribution for constant-head tests (CHT) are analyzed.
Cordell Bank National Marine Sanctuary Boundary (polygon)
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...
New Mexico HUC-10 Boundaries - 2013
Earth Data Analysis Center, University of New Mexico — This data set is a complete digital hydrologic unit boundary layer to the watershed (10-digit) 10th level for the State of New Mexico. This data set consists of...
Lubricated immersed boundary method in two dimensions
Fai, Thomas G.; Rycroft, Chris H.
2018-03-01
Many biological examples of fluid-structure interaction, including the transit of red blood cells through the narrow slits in the spleen and the intracellular trafficking of vesicles into dendritic spines, involve the near-contact of elastic structures separated by thin layers of fluid. Motivated by such problems, we introduce an immersed boundary method that uses elements of lubrication theory to resolve thin fluid layers between immersed boundaries. We demonstrate 2nd-order accurate convergence for simple two-dimensional flows with known exact solutions to showcase the increased accuracy of this method compared to the standard immersed boundary method. Motivated by the phenomenon of wall-induced migration, we apply the lubricated immersed boundary method to simulate an elastic vesicle near a wall in shear flow. We also simulate the dynamics of a vesicle traveling through a narrow channel and observe the ability of the lubricated method to capture the vesicle motion on relatively coarse fluid grids.
Exploring the planetary boundary for chemical pollution
DEFF Research Database (Denmark)
Diamond, Miriam L.; de Wit, Cynthia A.; Molander, Sverker
2015-01-01
Rockström et al. (2009a, 2009b) have warned that humanity must reduce anthropogenic impacts defined by nine planetary boundaries if "unacceptable global change" is to be avoided. Chemical pollution was identified as one of those boundaries for which continued impacts could erode the resilience...... of ecosystems and humanity. The central concept of the planetary boundary (or boundaries) for chemical pollution (PBCP or PBCPs) is that the Earth has a finite assimilative capacity for chemical pollution, which includes persistent, as well as readily degradable chemicals released at local to regional scales......, which in aggregate threaten ecosystem and human viability. The PBCP allows humanity to explicitly address the increasingly global aspects of chemical pollution throughout a chemical's life cycle and the need for a global response of internationally coordinated control measures. We submit that sufficient...
New Mexico HUC-8 Boundaries - 2013
Earth Data Analysis Center, University of New Mexico — This data set is a complete digital hydrologic unit boundary layer to the Subbasin (8-digit) 8th level for the State of New Mexico. This data set consists of...
Improving Land Tenure Security through Customary Boundary ...
African Journals Online (AJOL)
Michael
2017-06-01
Jun 1, 2017 ... Through Customary Boundary Demarcation – A Case Study", Vol. 17, No. 1, pp. 1 - 8. ... “allodial” or permanent title from which all lesser titles on .... including both quantitative and qualitative data, a .... administration easy.
Public Land Survey Township Boundaries of Iowa
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...
Monterey Bay National Marine Sanctuary Boundary (polygon)
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...
Monitor National Marine Sanctuary Boundary (polygon)
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...
Thunder Bay National Marine Sanctuary Boundary (polygon)
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...
Channel Islands National Marine Sanctuary Boundary (polygons)
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...
Religion's relationship with social boundaries surrounding gender ...
African Journals Online (AJOL)
Religion's relationship with social boundaries surrounding gender. ... is associated with segregation, marginalization and differentiation between men and women. ... are necessary in the society it should not be mistaken for gender inequality.
Olympic Coast National Marine Sanctuary Boundary (polygon)
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...
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.
National Marine Sanctuary Digital Boundary Files
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...
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...... may impact these variables and change efficient firm boundaries. The various theories of the firm have difficulties explaining how firms efficiently adapt their boundaries to such prominent characteristics of economic crisis as declining demand and increased costs of external finance. However, all...... these theories stress uncertainty as an antecedent of firm organization, and as uncertainty is also an important characteristic of an economic crisis I examine how uncertainty is allowed to play out in the various theories in order to identify what predictions we can derive from the theory regarding changes...
Boundary rings and N=2 coset models
International Nuclear Information System (INIS)
Lerche, W.; Walcher, J.
2002-01-01
We investigate boundary states of N=2 coset models based on Grassmannians Gr(n,n+k), and find that the underlying intersection geometry is given by the fusion ring of U(n). This is isomorphic to the quantum cohomology ring of Gr(n,n+k+1), which in turn can be encoded in a 'boundary' superpotential whose critical points correspond to the boundary states. In this way the intersection properties can be represented in terms of a soliton graph that forms a generalized, Z n+k+1 symmetric McKay quiver. We investigate the spectrum of bound states and find that the rational boundary CFT produces only a small subset of the possible quiver representations
Interorganizational Boundary Spanning in Global Software Development
DEFF Research Database (Denmark)
Søderberg, Anne-Marie; Romani, Laurence
, and which skills and competencies they draw on in their efforts to deal with emerging cross-cultural issues in a way that paves ground for developing a shared understanding and common platform for the client and vendor representatives. A framework of boundary spanning leadership practices is adapted...... to virtuality and cultural diversity. This paper, which draws on a case study of collaborative work in a global software development project, focuses on key boundary spanners in an Indian vendor company, who are responsible for developing trustful and sustainable client relations and coordinating complex...... projects across multiple cultures, languages, organisational boundaries, time zones and geographical distances. It looks into how these vendor managers get prepared for their complex boundary spanning work, which cross-cultural challenges they experience in their collaboration with Western clients...
Ground observations of magnetospheric boundary layer phenomena
International Nuclear Information System (INIS)
McHenry, M.A.; Clauer, C.R.; Friis-Christensen, E.; Newell, P.T.; Kelly, J.D.
1990-01-01
Several classes of traveling vortices in the dayside ionospheric convection have been detected and tracked using the Greenland magnetometer chain (Friis-Christensen et al., 1988, McHenry et al., 1989). One class observed during quiet times consists of a continuous series of vortices moving generally anti-sunward for several hours at a time. The vortices strength is seen to be approximately steady and neighboring vortices rotate in opposite directions. Sondrestrom radar observations show that the vortices are located at the ionospheric convection reversal boundary. Low altitude DMSP observations indicate the vortices are on field lines which map to the inner edge of the low latitude boundary layer. Because the vortices are conjugate to the boundary layer, repeat in a regular fashion and travel antisunward, the authors argue that this class of vortices is caused by the Kelvin-Helmholtz instability of the inner edge of the magnetospheric boundary layer
Florida Keys National Marine Sanctuary Boundary (polygon)
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...
International Boundary United States Mexico Minute 315
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...
Quadratic Functionals with General Boundary Conditions
International Nuclear Information System (INIS)
Dosla, Z.; Dosly, O.
1997-01-01
The purpose of this paper is to give the Reid 'Roundabout Theorem' for quadratic functionals with general boundary conditions. In particular, we describe the so-called coupled point and regularity condition introduced in terms of Riccati equation solutions
Superfund National Priority List (NPL) Site Boundaries
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...
State Wildlife Management Area Boundaries - Publicly Accessible
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...
Stability of spatially developing boundary layers
Govindarajan, Rama
1993-07-01
A new formulation of the stability of boundary-layer flows in pressure gradients is presented, taking into account the spatial development of the flow. The formulation assumes that disturbance wavelength and eigenfunction vary downstream no more rapidly than the boundary-layer thickness, and includes all terms of O(1) and O(R(exp -1)) in the boundary-layer Reynolds number R. Although containing the Orr-Sommerfeld operator, the present approach does not yield the Orr-Sommerfeld equation in any rational limit. In Blasius flow, the present stability equation is consistent with that of Bertolotti et al. (1992) to terms of O(R(exp -1)). For the Falkner-Skan similarity solutions neutral boundaries are computed without the necessity of having to march in space. Results show that the effects of spatial growth are striking in flows subjected to adverse pressure gradients.
International boundary experiences by the United Nations
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
Interplanetary sector boundaries 1971--1973
International Nuclear Information System (INIS)
Klein, L.; Burlaga, L.F.
1980-01-01
Eighteen interplanetary sector boundary crossings observed at 1 AU during the period January 1971 to January 1974 by the magnetometer on the Imp 6 spacecraft was discussed. The events were examined on many different time scales ranging from days on either side of the boundary to high-resolution measurements of 12.5 vectors per second. Two categories of boundaries were found, one group being relatively thin (averaging approx. =10 4 km) and the other being thick (averaging approx. =10 6 km). In many cases the field vector rotated in a plane from polarity to the other. Only two of the transitions were null sheets. Using the minimum variance analysis to determine the normals to the plane of rotationa and assuming that this is the same as the normal to the sector boundary surface, it was found that the normals were close to ( 0 ) the ecliptic plane. The high inclination of the sector boundary surfaces during 1971--1973 verifies a published prediction and may be related to the presence of large equatorial coronal holes at this time. An analysis of tangential discontinuities contained in 4-day periods about our events showed that their orientations were generally not related to the orientations of the sector boundary surface, but rather their characteristics were about the same as those for discontinuities outside the sector boundaries. Magnetic holes were found in thick sector boundaries, at a rate about 3 times that elsewhere. The holes were especially prevalent near stream interfaces, suggesting that they might be related to the convergence and/or slip of adjacent solar wind streams
Inference of Boundaries in Causal Sets
Cunningham, William
2017-01-01
We investigate the extrinsic geometry of causal sets in $(1+1)$-dimensional Minkowski spacetime. The properties of boundaries in an embedding space can be used not only to measure observables, but also to supplement the discrete action in the partition function via discretized Gibbons-Hawking-York boundary terms. We define several ways to represent a causal set using overlapping subsets, which then allows us to distinguish between null and non-null bounding hypersurfaces in an embedding space...
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 in...... approach with pattern matching is a way to shed light on the tacit local knowledge that organizational actors cannot articulate and that an exclusively inductive research is not likely to unveil....
A variable K - planetary boundary layer model
International Nuclear Information System (INIS)
Misra, P.K.
1976-07-01
The steady-state, homogeneous and barotropic equations of motion within the planetary boundary layer are solved with the assumption that the coefficient of eddy viscosity varies as K(Z) = K 0 (1-Z/h)sup(p), where h is the height of the boundary layer and p a parameter which depends on the atmospheric stability. The solutions are compared with the observed velocity profiles based on the Wangara data. They compare favourably. (author)
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 are...... 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....
Research, Boundaries, and Policy in Networked Learning
DEFF Research Database (Denmark)
This book presents cutting-edge, peer reviewed research on networked learning organized by three themes: policy in networked learning, researching networked learning, and boundaries in networked learning. The "policy in networked learning" section explores networked learning in relation to policy...... networks, spaces of algorithmic governance and more. The "boundaries in networked learning" section investigates frameworks of students' digital literacy practices, among other important frameworks in digital learning. Lastly, the "research in networked learning" section delves into new research methods...
On form factors of boundary changing operators
Energy Technology Data Exchange (ETDEWEB)
Bajnok, Z., E-mail: bajnok.zoltan@wigner.mta.hu [MTA Lendület Holographic QFT Group, Wigner Research Centre for Physics, P.O.B. 49, H-1525 Budapest 114 (Hungary); Hollo, L., E-mail: hollo.laszlo@wigner.mta.hu [MTA Lendület Holographic QFT Group, Wigner Research Centre for Physics, P.O.B. 49, H-1525 Budapest 114 (Hungary); Laboratoire de Physique Théorique, École Normale Supérieure, 24, rue Lhomond, 75005 Paris (France)
2016-04-15
We develop a form factor bootstrap program to determine the matrix elements of local, boundary condition changing operators. We propose axioms for these form factors and determine their solutions in the free boson and Lee–Yang models. The sudden change in the boundary condition, caused by an operator insertion, can be interpreted as a local quench and the form factors provide the overlap of any state before the quench with any outgoing state after the quench.
Fernholz, H. H.; Krause, E.
Papers are presented on recent research concerning three-dimensional turbulent boundary layers. Topics examined include experimental techniques in three-dimensional turbulent boundary layers, turbulence measurements in ship-model flow, measurements of Reynolds-stress profiles in the stern region of a ship model, the effects of crossflow on the vortex-layer-type three-dimensional flow separation, and wind tunnel investigations of some three-dimensional separated turbulent boundary layers. Also examined are three-dimensional boundary layers in turbomachines, the boundary layers on bodies of revolution spinning in axial flows, the effect on a developed turbulent boundary layer of a sudden local wall motion, three-dimensional turbulent boundary layer along a concave wall, the numerical computation of three-dimensional boundary layers, a numerical study of corner flows, three-dimensional boundary calculations in design aerodynamics, and turbulent boundary-layer calculations in design aerodynamics. For individual items see A83-47012 to A83-47036
Behaviour of boundary functions for quantum billiards
International Nuclear Information System (INIS)
Baecker, A; Fuerstberger, S; Schubert, R; Steiner, F
2002-01-01
We study the behaviour of the normal derivative of eigenfunctions of the Helmholtz equation inside billiards with Dirichlet boundary condition. These boundary functions are of particular importance because they uniquely determine the eigenfunctions inside the billiard and also other physical quantities of interest. Therefore, they form a reduced representation of the quantum system, analogous to the Poincare section of the classical system. For the normal derivatives we introduce an equivalent to the standard Green function and derive an integral equation on the boundary. Based on this integral equation we compute the first two terms of the mean asymptotic behaviour of the boundary functions for large energies. The first term is universal and independent of the shape of the billiard. The second one is proportional to the curvature of the boundary. The asymptotic behaviour is compared with numerical results for the stadium billiard, different limacon billiards and the circle billiard, and good agreement is found. Furthermore, we derive an asymptotic completeness relation for the boundary functions
The energetic ion substorm injection boundary
International Nuclear Information System (INIS)
Lopez, R.E.; Sibeck, D.G.; McEntire, R.W.; Krimigis, S.M.
1990-01-01
The substorm injection boundary model has enjoyed considerable success in explaining plasma signatures in the near-geosynchronous region. However, the injection boundary has remained primarily a phenomenological model. In this paper the authors examine 167 dispersionless energetic ion injections which were observed by AMPTE CCE. The radial and local time distribution of the events as a function of Kp is qualitatively similar to that envisioned in the injection boundary model of Mauk and McIlwain (1974). They argue that particles observed during dispersionless injections are locally energized during the disruption of the cross-tail current sheet. Therefore they identify the injection boundary, as derived from the spatial distribution of dispersionless injections, with the earthward edge of the region of the magnetotail which undergoes current sheet disruption during the substorm expansion phase. The authors show that this qualitative model for the generation of the injection boundary can provide an explanation for the dispersionless nature, the double spiral shape, and the Kp dependence of the boundary
Boundary-layer effects in droplet splashing
Riboux, Guillaume; Gordillo, Jose Manuel
2017-11-01
A drop falling onto a solid substrate will disintegrate into smaller parts when its impact velocity exceeds the so called critical velocity for splashing. Under these circumstances, the very thin liquid sheet ejected tangentially to the solid after the drop touches the substrate, lifts off as a consequence of the aerodynamic forces exerted on it and finally breaks into smaller droplets, violently ejected radially outwards, provoking the splash. Here, the tangential deceleration experienced by the fluid entering the thin liquid sheet is investigated making use of boundary layer theory. The velocity component tangent to the solid, computed using potential flow theory provides the far field boundary condition as well as the pressure gradient for the boundary layer equations. The structure of the flow permits to find a self similar solution of the boundary layer equations. This solution is then used to calculate the boundary layer thickness at the root of the lamella as well as the shear stress at the wall. The splash model presented in, which is slightly modified to account for the results obtained from the boundary layer analysis, provides a very good agreement between the measurements and the predicted values of the critical velocity for the splash.
DNR Division of Parks and Trails District Boundaries
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...
Sierra Nevada Subregional Boundary - Sierra Nevada Conservancy [ds542
California Natural Resource Agency — 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...
Protected-area boundaries as filters of plant invasions.
Foxcroft, Llewellyn C; Jarošík, Vojtěch; Pyšek, Petr; Richardson, David M; Rouget, Mathieu
2011-04-01
Human land uses surrounding protected areas provide propagules for colonization of these areas by non-native species, and corridors between protected-area networks and drainage systems of rivers provide pathways for long-distance dispersal of non-native species. Nevertheless, the influence of protected-area boundaries on colonization of protected areas by invasive non-native species is unknown. We drew on a spatially explicit data set of more than 27,000 non-native plant presence records for South Africa's Kruger National Park to examine the role of boundaries in preventing colonization of protected areas by non-native species. The number of records of non-native invasive plants declined rapidly beyond 1500 m inside the park; thus, we believe that the park boundary limited the spread of non-native plants. The number of non-native invasive plants inside the park was a function of the amount of water runoff, density of major roads, and the presence of natural vegetation outside the park. Of the types of human-induced disturbance, only the density of major roads outside the protected area significantly increased the number of non-native plant records. Our findings suggest that the probability of incursion of invasive plants into protected areas can be quantified reliably. ©2010 Society for Conservation Biology.
Formation of intra-island grain boundaries in pentacene monolayers.
Zhang, Jian; Wu, Yu; Duhm, Steffen; Rabe, Jürgen P; Rudolf, Petra; Koch, Norbert
2011-12-21
To assess the formation of intra-island grain boundaries during the early stages of pentacene film growth, we studied sub-monolayers of pentacene on pristine silicon oxide and silicon oxide with high pinning centre density (induced by UV/O(3) treatment). We investigated the influence of the kinetic energy of the impinging molecules on the sub-monolayer growth by comparing organic molecular beam deposition (OMBD) and supersonic molecular beam deposition (SuMBD). For pentacene films fabricated by OMBD, higher pentacene island-density and higher polycrystalline island density were observed on UV/O(3)-treated silicon oxide as compared to pristine silicon oxide. Pentacene films deposited by SuMBD exhibited about one order of magnitude lower island- and polycrystalline island densities compared to OMBD, on both types of substrates. Our results suggest that polycrystalline growth of single islands on amorphous silicon oxide is facilitated by structural/chemical surface pinning centres, which act as nucleation centres for multiple grain formation in a single island. Furthermore, the overall lower intra-island grain boundary density in pentacene films fabricated by SuMBD reduces the number of charge carrier trapping sites specific to grain boundaries and should thus help achieving higher charge carrier mobilities, which are advantageous for their use in organic thin-film transistors.
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...
A boundary-fitted staggered difference method for incompressible flow using Riemann geometry
International Nuclear Information System (INIS)
Koshizuka, Seiichi; Kondo, Shunsuke; Oka, Yoshiaki.
1990-01-01
A boundary-fitted staggered difference method (BFSDM) is investigated for incompressible flow in nuclear plants. BFSDM employs control cells for scalars, staggered location of velocity components, and integrated formulation of div=0. Governing equations are written as coordinate-free forms using Riemann geometry. Flow velocity is represented with contravariant physical components in the present method. Connection terms emerge as source terms in the coordinate-free governing equations. These terms are studied from the viewpoints of physical meaning, numerical stability, and conservative property. Some flows on a round or slant boundary are solved using boundary-fitted curvilinear (BFC) grids and rectangular grids to compare the present method and the rectangular-type (R-type) staggered difference method (SDM). Supercomputing of the present method, including vector processing, is also discussed compared with the R-type method. (author)
Nier, Francis
2018-01-01
This article is concerned with the maximal accretive realizations of geometric Kramers-Fokker-Planck operators on manifolds with boundaries. A general class of boundary conditions is introduced which ensures the maximal accretivity and some global subelliptic estimates. Those estimates imply nice spectral properties as well as exponential decay properties for the associated semigroup. Admissible boundary conditions cover a wide range of applications for the usual scalar Kramer-Fokker-Planck equation or Bismut's hypoelliptic laplacian.
The Casimir effect for pistons with transmittal boundary conditions
Fucci, Guglielmo
2017-11-01
This work focuses on the analysis of the Casimir effect for pistons subject to transmittal boundary conditions. In particular we consider, as piston configuration, a direct product manifold of the type I × N where I is a closed interval of the real line and N is a smooth compact Riemannian manifold. By utilizing the spectral zeta function regularization technique, we compute the Casimir energy of the system and the Casimir force acting on the piston. Explicit results for the force are provided when the manifold N is a d-dimensional sphere.
High speed observation of HIFU-induced cavitation cloud near curved rigid boundaries
International Nuclear Information System (INIS)
Zuo, Z G; Wang, F B; Liu, S H; Wu, S J
2015-01-01
This paper focuses on the experimental study of the influence of surface curvature to the behaviour of HIFU-induced cavitation cloud. A Q-switched ruby pulse laser is used to induce cavitation nuclei in deionized water. A piezoelectric ultrasonic transducer (1.7 MHz) provides a focused ultrasound field to inspire the nucleus to cavitation cloud. A PZT probe type hydrophone is applied for measuring the HIFU sound field. It was observed that the motion of cavitation cloud located near the boundary is significantly influenced by the distance between cloud and boundary, as well as the curvature of the boundary. The curvature was defined by parameters λ and ξ. Convex boundary, concave boundary, and flat boundary correspond to ξ <1, ξ >1 and ξ = 1, respectively. Different behaviours of the cloud, including the migration of the cloud, the characteristics of oscillation, etc., were observed under different boundary curvatures by high-speed photography. Sonoluminescence of the acoustic cavitation bubble clouds were also studied to illustrate the characteristics of acoustic streaming
GRAIN-BOUNDARY PRECIPITATION UNDER IRRADIATION IN DILUTE BINARY ALLOYS
Institute of Scientific and Technical Information of China (English)
S.H. Song; Z.X. Yuan; J. Liu; R.G.Faulkner
2003-01-01
Irradiation-induced grain boundary segregation of solute atoms frequently bring about grain boundary precipitation of a second phase because of its making the solubility limit of the solute surpassed at grain boundaries. Until now the kinetic models for irradiation-induced grain boundary precipitation have been sparse. For this reason, we have theoretically treated grain boundary precipitation under irradiation in dilute binary alloys. Predictions ofγ'-Ni3Si precipitation at grain boundaries ave made for a dilute Ni-Si alloy subjected to irradiation. It is demonstrated that grain boundary silicon segregation under irradiation may lead to grain boundaryγ'-Ni3 Si precipitation over a certain temperature range.
Boundary control of fluid flow through porous media
DEFF Research Database (Denmark)
Hasan, Agus; Foss, Bjarne; Sagatun, Svein Ivar
2010-01-01
The flow of fluids through porous media can be described by the Boussinesq’s equation with mixed boundary conditions; a Neumann’s boundary condition and a nonlinear boundary condition. The nonlinear boundary condition provides a means to control the fluid flow through porous media. In this paper,......, some stabilizing controllers are constructed for various cases using Lyapunov design.......The flow of fluids through porous media can be described by the Boussinesq’s equation with mixed boundary conditions; a Neumann’s boundary condition and a nonlinear boundary condition. The nonlinear boundary condition provides a means to control the fluid flow through porous media. In this paper...
Boundary layer turbulence in transitional and developed states
Park, George Ilhwan; Wallace, James M.; Wu, Xiaohua; Moin, Parviz
2012-03-01
Using the recent direct numerical simulations by Wu and Moin ["Transitional and turbulent boundary layer with heat transfer," Phys. Fluids 22, 85 (2010)] of a flat-plate boundary layer with a passively heated wall, statistical properties of the turbulence in transition at Reθ ≈ 300, from individual turbulent spots, and at Reθ ≈ 500, where the spots merge (distributions of the mean velocity, Reynolds stresses, kinetic energy production, and dissipation rates, enstrophy and its components) have been compared to these statistical properties for the developed boundary layer turbulence at Reθ = 1840. When the distributions in the transitional regions are conditionally averaged so as to exclude locations and times when the flow is not turbulent, they closely resemble the distributions in the developed turbulent state at the higher Reynolds number, especially in the buffer layer. Skin friction coefficients, determined in this conditional manner at the two Reynolds numbers in the transitional flow are, of course, much larger than when their values are obtained by including both turbulent and non-turbulent information there, and the conditional averaged values are consistent with the 1/7th power law approximation. An octant analysis based on the combinations of signs of the velocity and temperature fluctuations, u, v, and θ shows that the momentum and heat fluxes are predominantly of the mean gradient type in both the transitional and developed regions. The fluxes appear to be closely associated with vortices that transport momentum and heat toward and away from the wall in both regions of the flow. The results suggest that there may be little fundamental difference between the nonlinear processes involved in the formation of turbulent spots that appear in transition and those that sustain the turbulence when it is developed. They also support the view that the transport processes and the vortical structures that drive them in developed and transitional boundary
Pressure Fluctuations Induced by a Hypersonic Turbulent Boundary Layer
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.
Predictions and Verification of an Isotope Marine Boundary Layer Model
Feng, X.; Posmentier, E. S.; Sonder, L. J.; Fan, N.
2017-12-01
A one-dimensional (1D), steady state isotope marine boundary layer (IMBL) model is constructed. The model includes meteorologically important features absent in Craig and Gordon type models, namely height-dependent diffusion/mixing and convergence of subsiding external air. Kinetic isotopic fractionation results from this height-dependent diffusion which starts as pure molecular diffusion at the air-water interface and increases linearly with height due to turbulent mixing. The convergence permits dry, isotopically depleted air subsiding adjacent to the model column to mix into ambient air. In δD-δ18O space, the model results fill a quadrilateral, of which three sides represent 1) vapor in equilibrium with various sea surface temperatures (SSTs) (high d18O boundary of quadrilateral); 2) mixture of vapor in equilibrium with seawater and vapor in the subsiding air (lower boundary depleted in both D and 18O); and 3) vapor that has experienced the maximum possible kinetic fractionation (high δD upper boundary). The results can be plotted in d-excess vs. δ18O space, indicating that these processes all cause variations in d-excess of MBL vapor. In particular, due to relatively high d-excess in the descending air, mixing of this air into the MBL causes an increase in d-excess, even without kinetic isotope fractionation. The model is tested by comparison with seven datasets of marine vapor isotopic ratios, with excellent correspondence; >95% of observational data fall within the quadrilateral area predicted by the model. The distribution of observations also highlights the significant influence of vapor from the nearby converging descending air on isotopic variations in the MBL. At least three factors may explain the affect the isotopic composition of precipitation. The model can be applied to modern as well as paleo- climate conditions.
Bifurcation of solutions to Hamiltonian boundary value problems
McLachlan, R. I.; Offen, C.
2018-06-01
A bifurcation is a qualitative change in a family of solutions to an equation produced by varying parameters. In contrast to the local bifurcations of dynamical systems that are often related to a change in the number or stability of equilibria, bifurcations of boundary value problems are global in nature and may not be related to any obvious change in dynamical behaviour. Catastrophe theory is a well-developed framework which studies the bifurcations of critical points of functions. In this paper we study the bifurcations of solutions of boundary-value problems for symplectic maps, using the language of (finite-dimensional) singularity theory. We associate certain such problems with a geometric picture involving the intersection of Lagrangian submanifolds, and hence with the critical points of a suitable generating function. Within this framework, we then study the effect of three special cases: (i) some common boundary conditions, such as Dirichlet boundary conditions for second-order systems, restrict the possible types of bifurcations (for example, in generic planar systems only the A-series beginning with folds and cusps can occur); (ii) integrable systems, such as planar Hamiltonian systems, can exhibit a novel periodic pitchfork bifurcation; and (iii) systems with Hamiltonian symmetries or reversing symmetries can exhibit restricted bifurcations associated with the symmetry. This approach offers an alternative to the analysis of critical points in function spaces, typically used in the study of bifurcation of variational problems, and opens the way to the detection of more exotic bifurcations than the simple folds and cusps that are often found in examples.
A numerical solution of a singular boundary value problem arising in boundary layer theory.
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.
Boundary element analysis of earthquake induced hydrodynamic pressures in a water reservoir
International Nuclear Information System (INIS)
Jablonski, A.M.
1988-11-01
The seismic analysis of concrete gravity and arch dams is affected by the hydrodynamic pressures in the water reservoir. Boundary element method (BEM) formulations are derived for the hydrodynamic pressures arising in a gravity dam-reservoir-foundation system, treating both 2- and 3-dimensional cases. The formulations are based on the respective mathematical models which are governed by two- and three-dimensional Helmholtz equations with appropriate boundary conditions. For infinite reservoirs, loss of energy due to pressure waves moving away toward infinity strongly influence response. Since it is not possible to discretize an infinite extent, the radiation damping due to outgoing waves is accounted for by incorporating special boundary conditions at the far end, and in a similar manner the loss of energy due to absorption of waves by a flexible bottom of reservoir and banks can be accounted for by a special condition along the boundaries. Numerical results are obtained and compared with available classical solutions and convergence of numerical results with the size and number of boundary elements is studied. It is concluded that the direct boundary element method is an effective tool for the evaluation of the hydrodynamic pressures in finite and infinite dam-reservoir-foundation systems subjected to harmonic-type motion, and can easily be extended to any type of random motion with fast Fourier transform techniques. 82 refs., 65 figs., 25 tabs
Cadmium Telluride and Grain Boundaries: A Preliminary Study
Liao, Michael Evan
roughness for direct wafer bonding. High resolution x-ray diffraction is used to study the strain of the CdTe epilayer at the epilayer-substrate interface by generating reciprocal space maps of the (004), (115), and (335) crystallographic planes. It is found that CdTe grown on an (001) InSb substrate at a low growth temperature exhibits nearly 0% relaxation. As a result, the in-plane lattice parameter of the CdTe layer is maximally strained to match the smaller lattice parameter of the InSb substrate. Consequently, the CdTe lattice is tetragonally strained normal to the substrate surface, which causes the out-of-plane lattice parameter of CdTe to be larger than its intrinsic value. Lastly, a CdCl2-treated CdTe-CdS (p-type CdTe on n-type CdS) solar cell structure is simulated using a semiconductor-heterojunction simulation program. In literature, it has been reported that chlorine atoms from the treatment segregate along grain boundaries in polycrystalline CdTe and cause the formation of local p-n junctions by inverting the grain boundaries to n-type. The simulated structure includes one grain and 2 grain boundaries. The grain/bulk CdTe material is p-type while the grain boundaries are made to be n-type with varying doping concentrations. Both the conduction band and valence band energy exhibit downward sloping from the CdTe surface to the CdTe-CdS interface. This structure assumes that the grain boundaries are parallel to the CdTe-CdS interface. While these simulations do not prove the existence of the local type-inversion hypothesis, they do entertain a novel possibility for future devices fabrication methods.
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.
Directory of Open Access Journals (Sweden)
Zunnunov R.T.
2010-04-01
Full Text Available In this paper the existence and uniqueness of the solution of the nonlocal boundary value problem for the mixed type equation in unbounded domain are proved.In this paper the existence and uniqueness of the solution of the non-local boundary value problem for the mixed type equation in unbounded domain are proved.
A New Spectral Local Linearization Method for Nonlinear Boundary Layer Flow Problems
Directory of Open Access Journals (Sweden)
S. S. Motsa
2013-01-01
Full Text Available We propose a simple and efficient method for solving highly nonlinear systems of boundary layer flow problems with exponentially decaying profiles. The algorithm of the proposed method is based on an innovative idea of linearizing and decoupling the governing systems of equations and reducing them into a sequence of subsystems of differential equations which are solved using spectral collocation methods. The applicability of the proposed method, hereinafter referred to as the spectral local linearization method (SLLM, is tested on some well-known boundary layer flow equations. The numerical results presented in this investigation indicate that the proposed method, despite being easy to develop and numerically implement, is very robust in that it converges rapidly to yield accurate results and is more efficient in solving very large systems of nonlinear boundary value problems of the similarity variable boundary layer type. The accuracy and numerical stability of the SLLM can further be improved by using successive overrelaxation techniques.
International Nuclear Information System (INIS)
Merkle, K.L.; Huang, Y.
1998-01-01
The electric transport of high-temperature superconductors, such as YBa 2 Cu 3 O 7-x (YBCO), can be strongly restricted by the presence of high-angle grain boundaries (GB). This weak-link behavior is governed by the macroscopic GB geometry and the microscopic grain boundary structure and composition at the atomic level. Whereas grain boundaries present a considerable impediment to high current applications of high T c materials, there is considerable commercial interest in exploiting the weak-link-nature of grain boundaries for the design of microelectronic devices, such as superconducting quantum interference devices (SQUIDs). The Josephson junctions which form the basis of this technology can also be formed by introducing artificial barriers into the superconductor. The authors have examined both types of Josephson junctions by EM techniques in an effort to understand the connection between microstructure/chemistry and electrical transport properties. This knowledge is a valuable resource for the design and production of improved devices
Formation of incoherent deformation twin boundaries in a coarse-grained Al-7Mg alloy
Jin, S. B.; Zhang, K.; Bjørge, R.; Tao, N. R.; Marthinsen, K.; Lu, K.; Li, Y. J.
2015-08-01
Deformation twinning has rarely been observed in coarse grained Al and its alloys except under some extreme conditions such as ultrahigh deformation strain or strain rates. Here, we report that a significant amount of Σ3 deformation twins could be generated in a coarse-grained Al-7 Mg alloy by dynamic plastic deformation (DPD). A systematic investigation of the Σ3 boundaries shows that they are Σ3{112} type incoherent twin boundaries (ITBs). These ITBs have formed by gradual evolution from copious low-angle deformation bands through -twist Σ boundaries by lattice rotation. These findings provide an approach to generate deformation twin boundaries in high stacking fault energy metallic alloys. It is suggested that high solution content of Mg in the alloy and the special deformation mode of DPD played an important role in formation of the Σ and ITBs.
Off-wall boundary conditions for turbulent flows obtained from buffer-layer minimal flow units
Garcia-Mayoral, Ricardo; Pierce, Brian; Wallace, James
2012-11-01
There is strong evidence that the transport processes in the buffer region of wall-bounded turbulence are common across various flow configurations, even in the embryonic turbulence in transition (Park et al., Phys. Fl. 24). We use this premise to develop off-wall boundary conditions for turbulent simulations. Boundary conditions are constructed from DNS databases using periodic minimal flow units and reduced order modeling. The DNS data was taken from a channel at Reτ = 400 and a zero-pressure gradient transitional boundary layer (Sayadi et al., submitted to J . FluidMech .) . Both types of boundary conditions were first tested on a DNS of the core of the channel flow with the aim of extending their application to LES and to spatially evolving flows. 2012 CTR Summer Program.
Mechanism for boundary crises in quasiperiodically forced period-doubling systems
International Nuclear Information System (INIS)
Kim, Sang-Yoon; Lim, Woochang
2005-01-01
We investigate the mechanism for boundary crises in the quasiperiodically forced logistic map which is a representative model for quasiperiodically forced period-doubling systems. For small quasiperiodic forcing ε, a chaotic attractor disappears suddenly via a 'standard' boundary crisis when it collides with the smooth unstable torus. However, when passing a threshold value of ε, a basin boundary metamorphosis occurs, and then the smooth unstable torus is no longer accessible from the interior of the basin of the attractor. For this case, using the rational approximations to the quasiperiodic forcing, it is shown that a nonchaotic attractor (smooth torus or strange nonchaotic attractor) as well as a chaotic attractor is destroyed abruptly through a new type of boundary crisis when it collides with an invariant 'ring-shaped' unstable set which has no counterpart in the unforced case
Mechanism for boundary crises in quasiperiodically forced period-doubling systems
Energy Technology Data Exchange (ETDEWEB)
Kim, Sang-Yoon [Department of Physics, Kangwon National University, Chunchon, Kangwon-Do 200-701 (Korea, Republic of)]. E-mail: sykim@kangwon.ac.kr; Lim, Woochang [Department of Physics, Kangwon National University, Chunchon, Kangwon-Do 200-701 (Korea, Republic of)]. E-mail: wclim@kwnu.kangwon.ac.kr
2005-01-10
We investigate the mechanism for boundary crises in the quasiperiodically forced logistic map which is a representative model for quasiperiodically forced period-doubling systems. For small quasiperiodic forcing {epsilon}, a chaotic attractor disappears suddenly via a 'standard' boundary crisis when it collides with the smooth unstable torus. However, when passing a threshold value of {epsilon}, a basin boundary metamorphosis occurs, and then the smooth unstable torus is no longer accessible from the interior of the basin of the attractor. For this case, using the rational approximations to the quasiperiodic forcing, it is shown that a nonchaotic attractor (smooth torus or strange nonchaotic attractor) as well as a chaotic attractor is destroyed abruptly through a new type of boundary crisis when it collides with an invariant 'ring-shaped' unstable set which has no counterpart in the unforced case.
Chern-Simons supergravity plus matter near the boundary of AdS3
International Nuclear Information System (INIS)
Deger, N.S.; Kaya, A.; Sezgin, E.; Sundell, P.; Tanii, Y.
2001-01-01
We examine the boundary behaviour of the gauged N=(2,0) supergravity in D=3 coupled to an arbitrary number of scalar supermultiplets which parametrize a Kaehler manifold. In addition to the gravitational coupling constant, the model depends on two parameters, namely the cosmological constant and the size of the Kaehler manifold. It is shown that regular and irregular boundary conditions can be imposed on the matter fields depending on the size of the sigma model manifold. It is also shown that the super AdS transformations in the bulk produce the transformations of the N=(2,0) conformal supergravity and scalar multiplets on the boundary, containing fields with nonvanishing Weyl weights determined by the ratio of the sigma model and the gravitational coupling constants. Various types of (2,0) superconformal multiplets are found on the boundary and in one case the superconformal symmetry is shown to be realized in an unconventional way
Algebraic structures in generalized Clifford analysis and applications to boundary value problems
Directory of Open Access Journals (Sweden)
José Játem
2015-12-01
Full Text Available The present article has a threefold purpose: First it is a survey of the algebraic structures of generalized Clifford-type algebras and shows the main results of the corresponding Clifford-type analysis and its application to boundary value problems known so far. Second it is aimed to implement algorithms to provide the fast and accurate computation of boundary value problems for inhomogeneous equations in the framework of the generalized Clifford analysis. Finally it is also aimed to encourage the development of a generalized discrete Clifford analysis.