WorldWideScience

Sample records for bulk deformation structures

  1. In-situ studies of bulk deformation structures: Static properties under load and dynamics during deformation

    DEFF Research Database (Denmark)

    Jakobsen, Bo

    2006-01-01

    The main goal of the study presented in this thesis was to perform in-situ investigations on deformation structures in plastically deformed polycrystalline copper at low degrees of tensile deformation (<5%). Copper is taken as a model system for cell forming pure fcc metals. Anovel synchrotron......-radiation based technique High Angular Resolution 3DXRD has been developed at the 1-ID beam-line at the Advanced Photon Source. The technique extents the 3DXRD approach, to 3D reciprocal space mapping with a resolution of ≈ 1 · 10−3Å−1 and allows for in-situmapping of reflections from deeply-embedded individual...... width of the peaks, and spatial scanning experiments it is concluded that the individual peaks arise from individual dislocation-free regions (the subgrains) in the dislocation structure. The cloud is attributed to the dislocation rich walls. Samples deformed to 2% tensile strain were investigated under...

  2. Superplasticity and structure of bulk metallic glass vit-1 by tensile plastic deformation in the supercooled liquid region

    International Nuclear Information System (INIS)

    It was investigated by tensile plastic deformation behavior of metallic glasses bulk (Zr41.25Ti13.75Ni10Cu12.5Be22.5) in the supercooled liquid region at different strain rates and temperatures. When the temperature rises to a value of 675 K test, which is near the crystallization temperature of the glass and decreasing the speed on the curves of test strain appears more pronounced hardening sites that suggest that under the action of deformation in a homogeneous vitreous material falls reinforcing particles of crystalline phases. Choosing the temperature-strain rate conditions of the metallic glass to a supercooled liquid region can be deformed samples up to several hundred percent to obtain a sample of the original material structure of the metallic glass, or a composite of glass and metal nanocrystalline secretions

  3. Structural aspects of elasto-plastic deformation of a Zr-based bulk metallic glass under uniaxial compression

    International Nuclear Information System (INIS)

    The structural rearrangements occurring during compressive deformation of a plastically deformable Zr52.5Ti5Cu18Ni14.5Al10 bulk metallic glass have been investigated in situ using high energy synchrotron X-rays. It was found that in the elastic regime, the atomic distances at both short and medium range order vary linearly with macroscopic stress where the atomic bonds in short range order appear significantly stiffer than medium range order. Upon elastic loading, a small fraction of bonds in the first shell is broken in the loading direction whereas some new bonds are formed in the transverse direction. Atomic strain–stress correlation at medium range order deviates from linearity at the onset of plastic deformation which was correlated to the activation of irreversible STZs. This was confirmed by quantifying the amount of atomic shear strain value during loading. The length scale of 12.5 Å indicated the largest shear strain and is thought to be the most effective length scale in the formation of STZs. The typical fracture angle of this BMG was explained by the orientation of maximum atomic shear strain at the onset of major shear band formation

  4. Fabrication of Fe-based bulk metallic glasses with plastic deformation and nanocrystalline alloys with Bs of 1.9 tesla by using structural heterogeneity

    International Nuclear Information System (INIS)

    An Fe-Metalloids-based Fe76Si9B10P5 (at%) bulk metallic glass (BMG) exhibits unusual combination of high saturation magnetic flux density (Bs) of 1.51 T due to high Fe content as well as high glass-forming ability leading to a glassy rod with a diameter of 2.5 mm despite not-containing any glass-forming metal elements. A small amount of Cu-added (Fe76Si9.4B8.4P6)99.9Cu0.1 BMG exhibits a yielding strength of 3.25 GPa and a large plastic deformation of about 4% in compression. The unusual deformation behavior with distinguishable highly dense multiple shear bands on the fracture surface could be due to the existence of a large number of α-Fe like clusters, less than 10 nm in diameter, embedded in a glassy matrix. The melt-spun Fe83.3-84.3Si4B8P3-4Cu0.7 alloys also have heterogeneous amorphous structures including a large amount of α-Fe clusters, 2-3 nm in diameter, due to the unusual effect of the simultaneous addition of the proper amounts of P and Cu. The hetero-amorphous alloys exhibit higher Bs of about 1.67 T than the representative amorphous and the nanocrystalline alloys, and the low coercivity (Hc) of 5-10 A/m. A homogeneous nanocrystalline structure composed of small α-Fe grains with a size of about 10 nm can be realized by crystallizing the hetero-amorphous alloys. The nanocrystalline alloys show extremely high Bs of 1.88-1.94 T almost comparable to the commercial Fe-3.5mass%Si crystalline soft magnetic alloys, and low Hc of 7-10 A/m due to the simultaneous realization of the homogeneous nanocrystalline structure and small magnetostriction of 2-3 x 10-6. In addition, these alloys have a great advantage of lower material cost for engineering and industry, and thus should make a contribution to energy saving, and conservation of earth resources and environment. (author)

  5. Bulk metallic glasses deform via slip avalanches.

    Science.gov (United States)

    Antonaglia, James; Wright, Wendelin J; Gu, Xiaojun; Byer, Rachel R; Hufnagel, Todd C; LeBlanc, Michael; Uhl, Jonathan T; Dahmen, Karin A

    2014-04-18

    For the first time in metallic glasses, we extract both the exponents and scaling functions that describe the nature, statistics, and dynamics of slip events during slow deformation, according to a simple mean field model. We model the slips as avalanches of rearrangements of atoms in coupled shear transformation zones (STZs). Using high temporal resolution measurements, we find the predicted, different statistics and dynamics for small and large slips thereby excluding self-organized criticality. The agreement between model and data across numerous independent measures provides evidence for slip avalanches of STZs as the elementary mechanism of inhomogeneous deformation in metallic glasses. PMID:24785049

  6. Nanoscale cracks at deformation twins stopped by grain boundaries in bulk and thin-film materials with nanocrystalline and ultrafine-grained structures

    International Nuclear Information System (INIS)

    Nanoscale fracture processes initiated at intersections of deformation twins and grain boundaries (GBs) in nanocrystalline and ultrafine-grained materials are theoretically described. Within the suggested description scheme, nanocracks are formed at GBs at which deformation twins are stopped and thereby produce specific GB defect configurations that create high local stresses initiating nanocracks. The conditions for realization of this new fracture mode in nanocrystalline and ultrafine-grained materials with face-centred cubic and body-centred cubic crystal lattices are calculated. The free-surface effect on crack generation at deformation twins stopped by GBs in thin-film nanocrystalline specimens is theoretically described. The critical parameters for crack generation in nanocrystalline and ultrafine-grained bulk materials and thin films are revealed. It is shown that in bulk nanomaterials nanocracks are generated at twin thicknesses of several nanometres and grow very fast with increasing twin thickness. At the same time, in thin-film nanomaterials, the equilibrium nanocrack lengths significantly decrease if the distance between the twin lamella and the closest film surface does not exceed several twin thicknesses. (paper)

  7. Extremely deformable structures

    CERN Document Server

    2015-01-01

    Recently, a new research stimulus has derived from the observation that soft structures, such as biological systems, but also rubber and gel, may work in a post critical regime, where elastic elements are subject to extreme deformations, though still exhibiting excellent mechanical performances. This is the realm of ‘extreme mechanics’, to which this book is addressed. The possibility of exploiting highly deformable structures opens new and unexpected technological possibilities. In particular, the challenge is the design of deformable and bi-stable mechanisms which can reach superior mechanical performances and can have a strong impact on several high-tech applications, including stretchable electronics, nanotube serpentines, deployable structures for aerospace engineering, cable deployment in the ocean, but also sensors and flexible actuators and vibration absorbers. Readers are introduced to a variety of interrelated topics involving the mechanics of extremely deformable structures, with emphasis on ...

  8. Layered Structures in Deformed Metals and Alloys

    DEFF Research Database (Denmark)

    Hansen, Niels; Zhang, Xiaodan; Huang, Xiaoxu

    2014-01-01

    Layered structures characterize metals and alloys deformed to high strain. The morphology is typical lamellar or fibrous and the interlamellar spacing can span several length scales down to the nanometer dimension. The layered structures can be observed in bulk or in surface regions, which is shown......-structure relationships. Finally, the results will be discussed based on universal principles for the evolution of microstructure and properties during plastic deformation of metals and alloys from low to high strain....

  9. Dynamic Plastic Deformation (DPD): A Novel Technique for Synthesizing Bulk Nanostructured Metals

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    While some superior properties of nanostructured materials (with structural scales below 100 nm) have attracted numerous interests of material scientists, technique development for synthesizing nanostructured metals and alloys in 3-dimensional (3D) bulk forms is still challenging despite of extensive investigations over decades.Here we report a novel synthesis technique for bulk nanostructured metals based on plastic deformation at high Zener-Hollomon parameters (high strain rates or low temperatures), i.e., dynamic plastic deformation (DPD).The basic concept behind this approach will be addressed together with a few examples to demonstrate the capability and characteristics of this method. Perspectives and future developments of this technique will be highlighted.

  10. Powder metallurgy processing and deformation characteristics of bulk multimodal nickel

    Energy Technology Data Exchange (ETDEWEB)

    Farbaniec, L., E-mail: lfarban1@jhu.edu [Université Paris 13, Sorbonne Paris Cité, LSPM, CNRS, 99 Avenue J.B. Clément, 93430 Villetaneuse (France); Dirras, G., E-mail: dirras@univ-paris13.fr [Université Paris 13, Sorbonne Paris Cité, LSPM, CNRS, 99 Avenue J.B. Clément, 93430 Villetaneuse (France); Krawczynska, A.; Mompiou, F. [Université Paul Sabatier, CEMES, CNRS, 29 rue Jeanne Marvig 31055 Toulouse (France); Couque, H. [Nexter Munitions, 7 route de Guerry, 18200 Bourges (France); Naimi, F.; Bernard, F. [Institut Carnot de Bourgogne, UMR 6303 CNRS, Université de Bourgogne, BP 47870, 21078 Dijon (France); Tingaud, D. [Université Paris 13, Sorbonne Paris Cité, LSPM, CNRS, 99 Avenue J.B. Clément, 93430 Villetaneuse (France)

    2014-08-15

    Spark plasma sintering was used to process bulk nickel samples from a blend of three powder types. The resulting multimodal microstructure was made of coarse (average size ∼ 135 μm) spherical microcrystalline entities (the core) surrounded by a fine-grained matrix (average grain size ∼ 1.5 μm) or a thick rim (the shell) distinguishable from the matrix. Tensile tests revealed yield strength of ∼ 470 MPa that was accompanied by limited ductility (∼ 2.8% plastic strain). Microstructure observation after testing showed debonding at interfaces between the matrix and the coarse entities, but in many instances, shallow dimples within the rim were observed indicating local ductile events in the shell. Dislocation emission and annihilation at grain boundaries and twinning at crack tip were the main deformation mechanisms taking place within the fine-grained matrix as revealed by in-situ transmission electron microscopy. Estimation of the stress from loop's curvature and dislocation pile-up indicates that dislocation emission from grain boundaries and grain boundary overcoming largely contributes to the flow stress. - Highlights: • Bulk multi-modal Ni was processed by SPS from a powder blend. • Ultrafine-grained matrix or rim observed around spherical microcrystalline entities • Yield strength (470 MPa) and ductility (2.8% plastic strain) were measured. • Debonding was found at the matrix/microcrystalline entity interfaces. • In-situ TEM showed twinning, dislocation emission and annihilation at grain boundaries.

  11. Powder metallurgy processing and deformation characteristics of bulk multimodal nickel

    International Nuclear Information System (INIS)

    Spark plasma sintering was used to process bulk nickel samples from a blend of three powder types. The resulting multimodal microstructure was made of coarse (average size ∼ 135 μm) spherical microcrystalline entities (the core) surrounded by a fine-grained matrix (average grain size ∼ 1.5 μm) or a thick rim (the shell) distinguishable from the matrix. Tensile tests revealed yield strength of ∼ 470 MPa that was accompanied by limited ductility (∼ 2.8% plastic strain). Microstructure observation after testing showed debonding at interfaces between the matrix and the coarse entities, but in many instances, shallow dimples within the rim were observed indicating local ductile events in the shell. Dislocation emission and annihilation at grain boundaries and twinning at crack tip were the main deformation mechanisms taking place within the fine-grained matrix as revealed by in-situ transmission electron microscopy. Estimation of the stress from loop's curvature and dislocation pile-up indicates that dislocation emission from grain boundaries and grain boundary overcoming largely contributes to the flow stress. - Highlights: • Bulk multi-modal Ni was processed by SPS from a powder blend. • Ultrafine-grained matrix or rim observed around spherical microcrystalline entities • Yield strength (470 MPa) and ductility (2.8% plastic strain) were measured. • Debonding was found at the matrix/microcrystalline entity interfaces. • In-situ TEM showed twinning, dislocation emission and annihilation at grain boundaries

  12. Deformation behaviour of rapidly solidified and bulk Zr based metallic glasses by ball impression testing

    International Nuclear Information System (INIS)

    In this study the deformation characteristics of rapidly solidified Zr-Ni alloys and Zr56.26Al9.7Cu17.46Ni13.58Nb3 bulk metallic glass are compared in terms of shear band formation behaviour. The rapidly solidified alloys have been melt spun under conditions which have yielded partly crystalline and fully amorphous ribbons. The deformation of rapidly solidified alloys was carried out in tension and bending where as that of the bulk glass has been examined by ball indentation. The structure of the defects responsible for deformation viz, the shear bands has been investigated by conventional and high resolution transmission electron microscopy in order to understand the structure of the shear bands. A comparison of the structure of the shear bands of the two types of alloys has been carried out. The role of the crystalline particles on the deformation behaviour and their interaction with the shear bands has been examined in case of both types of materials using transmission electron microscopy. The effect of the shear bands on the crystallization process in either types of material has also been examined. (author)

  13. Formation and subdivision of deformation structures during plastic deformation

    DEFF Research Database (Denmark)

    Jakobsen, B.; Poulsen, H.F.; Lienert, U.;

    2006-01-01

    of individual, deeply embedded dislocation structures. During tensile deformation of pure copper, dislocation-free regions were identified. They showed an unexpected intermittent dynamics, for example, appearing and disappearing with proceeding deformation and even displaying transient splitting...

  14. Deformation of coherent structures

    NARCIS (Netherlands)

    Fledderus, E.R.; Groesen, van E.

    1996-01-01

    In this review we investigate the mathematical description of the distortion of clearly recognisable structures in phenomenological physics. The coherent structures we will explicitly deal with are surface waves on a layer of fluid, kink transitions in magnetic material, plane vortices, swirling flo

  15. Producing Bulk Ultrafine-Grained Materials by Severe Plastic Deformation: Ten Years Later

    Science.gov (United States)

    Valiev, Ruslan Z.; Estrin, Yuri; Horita, Zenji; Langdon, Terence G.; Zehetbauer, Michael J.; Zhu, Yuntian

    2016-04-01

    It is now well established that the processing of bulk solids through the application of severe plastic deformation (SPD) leads to exceptional grain refinement to the submicrometer or nanometer level. Extensive research over the last decade has demonstrated that SPD processing also produces unusual phase transformations and leads to the introduction of a range of nanostructural features, including nonequilibrium grain boundaries, deformation twins, dislocation substructures, vacancy agglomerates, and solute segregation and clustering. These many structural changes provide new opportunities for fine tuning the characteristics of SPD metals to attain major improvements in their physical, mechanical, chemical, and functional properties. This review provides a summary of some of these recent developments. Special emphasis is placed on the use of SPD processing in achieving increased electrical conductivity, superconductivity, and thermoelectricity, an improved hydrogen storage capability, materials for use in biomedical applications, and the fabrication of high-strength metal-matrix nanocomposites.

  16. Large strain bulk deformation and brittle tough transitions in polyethylenes

    CERN Document Server

    Hillmansen, S

    2001-01-01

    Some tough, crystalline polymers can fail by fast brittle fracture. This thesis explores the role of ductile 'shear lips', which form at the fracture surface verges, in brittle-tough transitions. A new laboratory method was used to isolate this region, and to test its ability to draw rapidly, in polyethylenes. The test uses a conventional Charpy type specimen that is deeply notched and impact loaded in three-point bending by a single striker. The ligament, rapidly loaded in almost pure tension, first yields, and then necks down until failure. Initial results are encouraging and correlate well with the in-service performance. A fundamental study of large strain deformation, that avoids the complexity associated with impact tests, was then conducted with the aim of isolating the dominating influences that furnish a polymer with the ability to sustain rapid large strain deformation. True stress vs. true strain curves have been interpreted using the one dimensional spring dashpot model of Haward and Thackray (H-T...

  17. Deformation behavior of Fe-based bulk metallic glass during nanoindentation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Fe-based bulk metallic glasses (BMGs) normally exhibit super high strength but significant brittleness at ambient temperature. Therefore,it is difficult to investigate the plastic deformation behavior and mechanism in these alloys through conven-tional tensile and compressive tests due to lack of distinct macroscopic plastic strain. In this work,the deformation behavior of Fe52Cr15Mo9Er3C15B6 BMG was in-vestigated through instrumented nanoindentation and uniaxial compressive tests. The results show that serrated flow,the typical plastic deformation feature of BMGs,could not be found in as-cast and partially crystallized samples during nanoinden-tation. In addition,the deformation behavior and mechanical properties of the alloy are insensitive to the applied loading rate. The mechanism for the appearance of the peculiar deformation behavior in the Fe-based BMG is discussed in terms of the temporal and spatial characteristics of shear banding during nanoindentation.

  18. Direct non-destructive observation of bulk nucleation in 30% deformed aluminum

    DEFF Research Database (Denmark)

    West, Stine; Schmidt, Søren; Sørensen, Henning Osholm; Winther, Grethe; Poulsen, Henning Friis; Margulies, Lawrence; Gundlach, Carsten; Juul Jensen, Dorte

    2009-01-01

    A 30% deformed aluminum sample was mapped non-destructively using three-dimensional X-ray diffraction (3DXRD) before and after annealing to nucleation of recrystallization. Nuclei appeared in the bulk of the sample. Their positions and volumes were determined, and the crystallographic orientations...

  19. Compressive Deformation Induced Nanocrystallization of a Supercooled Zr-Based Bulk Metallic Glass

    Institute of Scientific and Technical Information of China (English)

    GUO Xiao-Lin; SHAN De-Bin; MA Ming-Zhen; GUO Bin

    2008-01-01

    The nanocrystallization behaviour of a bulk Zr-based metallic glass subjected to compressive stress is investigated in the supercooled liquid region. Compared with annealing treatments without compressive stress, compressive deformation promotes the development of nucleation and suppresses the coarsening of nanocrystallites at high ternperatures.

  20. Stochastic deformation of a thermodynamic symplectic structure

    Science.gov (United States)

    Kazinski, P. O.

    2009-01-01

    A stochastic deformation of a thermodynamic symplectic structure is studied. The stochastic deformation is analogous to the deformation of an algebra of observables such as deformation quantization, but for an imaginary deformation parameter (the Planck constant). Gauge symmetries of thermodynamics and corresponding stochastic mechanics, which describes fluctuations of a thermodynamic system, are revealed and gauge fields are introduced. A physical interpretation to the gauge transformations and gauge fields is given. An application of the formalism to a description of systems with distributed parameters in a local thermodynamic equilibrium is considered.

  1. Deformed metals - structure, recrystallisation and strength

    DEFF Research Database (Denmark)

    Hansen, Niels; Juul Jensen, Dorte

    2011-01-01

    It is shown how new discoveries and advanced experimental techniques in the last 25 years have led to paradigm shifts in the analysis of deformation and annealing structures of metals and in the way the strength of deformed samples is related to structural parameters. This is described in three s...

  2. Scratch-induced deformation in fine- and ultrafine-grained bulk alumina

    International Nuclear Information System (INIS)

    The nanoscratch behavior of two bulk α-alumina samples with 1.3 μm and 290 nm average grain sizes, respectively, was investigated using a nanoindenter in scratch mode, in combination with atomic force and scanning electron microscopy. A ductile to brittle transition was observed in the fine-grained sample, while the ultrafine-grained sample exhibited predominantly ductile deformation with a fish-bone feature indicative of a stick-slip mechanism. These findings suggest that grain refinement can increase the potential for plastic deformation in ceramics.

  3. Watching the growth of bulk grains during recrystallization of deformed metals

    DEFF Research Database (Denmark)

    Schmidt, Søren; Fæster Nielsen, Søren; Gundlach, C.;

    2004-01-01

    We observed the in situ growth of a grain during recrystallization in the bulk of a deformed sample. We used the three-dimensional x-ray diffraction microscope located at the European Synchrotron Radiation Facility in Grenoble, France. The results showed a very heterogeneous growth pattern......, contradicting the classical assumption of smooth and spherical growth of new grains during recrystallization. This type of in situ bulk measurement opens up the possibility of obtaining experimental data on scientific topics that before could only be analyzed theoretically on the basis of the statistical...

  4. Interactions between high temperature deformation and crystallization in zirconium based bulk metallic glasses

    OpenAIRE

    Gravier, Sébastien; Blandin, Jean-Jacques; Donnadieu, Patricia

    2008-01-01

    Abstract High temperature deformation of a ZrTiCuNiBe bulk metallic glass (BMG) is investigated by compression tests in the supercooled liquid region. When temperature is decreased or strain rate is increased, the amorphous alloy exhibits the usual Newtonian ? non Newtonian behavior transition. Owing to appropriate heat treatments, partially crystallized alloys are produced, the associated microstructures are characterized and the volume fractions of crystal are measured. The inter...

  5. Quasi-static and dynamic deformation behaviour of Zr-based bulk metallic glass

    International Nuclear Information System (INIS)

    Nano- and micro-indentation studies were carried out to characterise a plasticity mechanism through the evolution of localised shear bands that drive material's deformation at sub-micron length scale. Initial deformation of Zr-based bulk metallic glass (BMG) was investigated with nanoindentation tests using a spherical indenter. The indentation cycle reflects an elastic deformation with the yielding load of approx. 3 mN. For designed cycling indentation, hardening and softening phenomena were observed in nano- and micro-indentations, respectively. High-precision dynamic mechanical relaxation measurements were performed using a Dynamic Mechanical Analyzer (DMA), on decreasing frequency from 160 Hz to 0.1 Hz. A mechanical response of the BMG surface to a concentrated impact load was also studied. The obtained results indicated that the studied Zr-based BMG behaved as an elastic-perfectly plastic material at macroscale with discrete plasticity events at smaller length scales

  6. Perovskite oxides: Oxygen electrocatalysis and bulk structure

    Science.gov (United States)

    Carbonio, R. E.; Fierro, C.; Tryk, D.; Scherson, D.; Yeager, Ernest

    1987-01-01

    Perovskite type oxides were considered for use as oxygen reduction and generation electrocatalysts in alkaline electrolytes. Perovskite stability and electrocatalytic activity are studied along with possible relationships of the latter with the bulk solid state properties. A series of compounds of the type LaFe(x)Ni1(-x)O3 was used as a model system to gain information on the possible relationships between surface catalytic activity and bulk structure. Hydrogen peroxide decomposition rate constants were measured for these compounds. Ex situ Mossbauer effect spectroscopy (MES), and magnetic susceptibility measurements were used to study the solid state properties. X ray photoelectron spectroscopy (XPS) was used to examine the surface. MES has indicated the presence of a paramagnetic to magnetically ordered phase transition for values of x between 0.4 and 0.5. A correlation was found between the values of the MES isomer shift and the catalytic activity for peroxide decomposition. Thus, the catalytic activity can be correlated to the d-electron density for the transition metal cations.

  7. Preparation, glass forming ability, crystallization and deformation of (zirconium, hafnium)-copper-nickel-aluminum-titanium-based bulk metallic glasses

    Science.gov (United States)

    Gu, Xiaofeng

    Multicomponent Zr-based bulk metallic glasses are the most promising metallic glass forming systems. They exhibit great glass forming ability and fascinating mechanical properties, and thus are considered as potential structural materials. One potential application is that they could be replacements of the depleted uranium for making kinetic energy armor-piercing projectiles, but the density of existing Zr-based alloys is too low for this application. Based on the chemical and crystallographic similarities between Zr and Hf, we have developed two series of bulk metallic glasses with compositions of (HfxZr1-x) 52.5Cu17.9Ni14.6Al10Ti5 and (HfxZr1-x) 57Cu20Ni8Al10Ti5 ( x = 0--1) by gradually replacing Zr by Hf. Remarkably increased density and improved mechanical properties have been achieved in these alloys. In these glasses, Hf and Zr play an interchangeable role in determining the short range order. Although the glass forming ability decreases continuously with Hf addition, most of these alloys remain bulk glass-forming. Recently, nanocomposites produced from bulk metallic glasses have attracted wide attention due to improved mechanical properties. However, their crystalline microstructure (the grain size and the crystalline volume fraction) has to be optimized. We have investigated crystallization of (Zr, Hf)-based bulk metallic glasses, including the composition dependence of crystallization paths and crystallization mechanisms. Our results indicate that the formation of high number density nanocomposites from bulk metallic glasses can be attributed to easy nucleation and slowing-down growth processes, while the multistage crystallization behavior makes it more convenient to control the microstructure evolution. Metallic glasses are known to exhibit unique plastic deformation behavior. At low temperature and high stress, plastic flow is localized in narrow shear bands. Macroscopic investigations of shear bands (e.g., chemical etching) suggest that the internal

  8. Stability of bulk metallic glass structure

    Energy Technology Data Exchange (ETDEWEB)

    Jain, H.; Williams, D.B.

    2003-06-18

    The fundamental origins of the stability of the (Pd-Ni){sub 80}P{sub 20} bulk metallic glasses (BMGs), a prototype for a whole class of BMG formers, were explored. While much of the properties of their BMGs have been characterized, their glass-stability have not been explained in terms of the atomic and electronic structure. The local structure around all three constituent atoms was obtained, in a complementary way, using extended X-ray absorption fine structure (EXAFS), to probe the nearest neighbor environment of the metals, and extended energy loss fine structure (EXELFS), to investigate the environment around P. The occupied electronic structure was investigated using X-ray photoelectron spectroscopy (XPS). The (Pd-Ni){sub 80}P{sub 20} BMGs receive their stability from cumulative, and interrelated, effects of both atomic and electronic origin. The stability of the (Pd-Ni){sub 80}P{sub 20} BMGs can be explained in terms of the stability of Pd{sub 60}Ni{sub 20}P{sub 20} and Pd{sub 30}Ni{sub 50}P{sub 20}, glasses at the end of BMG formation. The atomic structure in these alloys is very similar to those of the binary phosphide crystals near x=0 and x=80, which are trigonal prisms of Pd or Ni atoms surrounding P atoms. Such structures are known to exist in dense, randomly-packed systems. The structure of the best glass former in this series, Pd{sub 40}Ni{sub 40}P{sub 20} is further described by a weighted average of those of Pd{sub 30}Ni{sub 50}P{sub 20} and Pd{sub 60}Ni{sub 20}P{sub 20}. Bonding states present only in the ternary alloys were found and point to a further stabilization of the system through a negative heat of mixing between Pd and Ni atoms. The Nagel and Tauc criterion, correlating a decrease in the density of states at the Fermi level with an increase in the glass stability, was consistent with greater stability of the Pd{sub x}Ni{sub (80-x)}P{sub 20} glasses with respect to the binary alloys of P. A valence electron concentration of 1.8 e/a, which

  9. Photoelectron spectroscopy bulk and surface electronic structures

    CERN Document Server

    Suga, Shigemasa

    2014-01-01

    Photoelectron spectroscopy is now becoming more and more required to investigate electronic structures of various solid materials in the bulk, on surfaces as well as at buried interfaces. The energy resolution was much improved in the last decade down to 1 meV in the low photon energy region. Now this technique is available from a few eV up to 10 keV by use of lasers, electron cyclotron resonance lamps in addition to synchrotron radiation and X-ray tubes. High resolution angle resolved photoelectron spectroscopy (ARPES) is now widely applied to band mapping of materials. It attracts a wide attention from both fundamental science and material engineering. Studies of the dynamics of excited states are feasible by time of flight spectroscopy with fully utilizing the pulse structures of synchrotron radiation as well as lasers including the free electron lasers (FEL). Spin resolved studies also made dramatic progress by using higher efficiency spin detectors and two dimensional spin detectors. Polarization depend...

  10. Free volume model: High-temperature deformation of a Zr-based bulk metallic glass

    International Nuclear Information System (INIS)

    The homogeneous deformation of a zirconium-based bulk metallic glass is investigated in the glass transition region. Compression tests at different temperatures and strain rates have been conducted. The mechanical behavior is analyzed in the framework of the free volume model, taking into account the dependence of the flow defect concentration on deformation. The activation volume is evaluated and allows one to gather the viscosity data (for the different strain rates and temperatures) on a unique master curve. It is also shown that, due to the relation between flow defect concentration and free volume, it is not possible to deduce the equilibrium flow defect concentration directly from mechanical measurements. However, if this parameter is arbitrarily chosen, mechanical measurements give access to the other parameters of the model, these parameters for the alloy under investigation being of the same order of magnitude as those for other metallic glasses

  11. Quasi-static and dynamic compressive deformation of a bulk nanolayered Ag–Cu eutectic alloy: Macroscopic response and dominant deformation mechanisms

    International Nuclear Information System (INIS)

    Nanostructured multilayered material systems offer an attractive method of increasing material strength. This work examines the response of a bulk eutectic silver–copper material (Ag60Cu40, subscripts indicating atomic percent) which has a hierarchical structure of alternating Ag and Cu layers with thicknesses down to 50 nm. The hierarchical structure consists of two primary arrangements of layers, eutectic colonies of parallel layers, most commonly found at the material interior, and “grains” consisting of alternating Ag and Cu layers which emanate from a central region in a radial pattern, most commonly found at the material exterior surface. We show that the hierarchical structure causes a significant increase in the measured strength response when comparing the Ag60Cu40 response to that of the constituent materials in their bulk nanograined or micrograined form. The deformation mechanisms of this material are studied under compressive loading over the quasi-static and dynamic regime (10−3–103 s−1) with strain between 5% and 50%

  12. Quasi-static and dynamic compressive deformation of a bulk nanolayered Ag–Cu eutectic alloy: Macroscopic response and dominant deformation mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Kingstedt, O.T., E-mail: kingste1@illinois.edu [Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, 306 Talbot Laboratory, MC-236, 104 South Wright Street, Urbana, IL 61801 (United States); Eftink, B. [Department of Material Science and Engineering, University of Illinois at Urbana-Champaign, 201 Materials Science and Engineering Building, 1304 West Green Street, Urbana, IL 61801 (United States); Lambros, J. [Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, 306 Talbot Laboratory, MC-236, 104 South Wright Street, Urbana, IL 61801 (United States); Robertson, I.M. [Department of Material Science and Engineering, University of Illinois at Urbana-Champaign, 201 Materials Science and Engineering Building, 1304 West Green Street, Urbana, IL 61801 (United States)

    2014-02-10

    Nanostructured multilayered material systems offer an attractive method of increasing material strength. This work examines the response of a bulk eutectic silver–copper material (Ag{sub 60}Cu{sub 40}, subscripts indicating atomic percent) which has a hierarchical structure of alternating Ag and Cu layers with thicknesses down to 50 nm. The hierarchical structure consists of two primary arrangements of layers, eutectic colonies of parallel layers, most commonly found at the material interior, and “grains” consisting of alternating Ag and Cu layers which emanate from a central region in a radial pattern, most commonly found at the material exterior surface. We show that the hierarchical structure causes a significant increase in the measured strength response when comparing the Ag{sub 60}Cu{sub 40} response to that of the constituent materials in their bulk nanograined or micrograined form. The deformation mechanisms of this material are studied under compressive loading over the quasi-static and dynamic regime (10{sup −3}–10{sup 3} s{sup −1}) with strain between 5% and 50%.

  13. Cellulose-wheat gluten bulk plastic materials produced from processing raw powders by severe shear deformation.

    Science.gov (United States)

    Zhang, Xiaoqing; Wu, Xiaolin; Xia, Kenong

    2013-02-15

    Cellulose-based renewable bulk plastics with significantly improved mechanical properties were produced by using a small proportion of wheat gluten (WG) as an additive to enhance the material processing capability. The strong shear-deformation during equal channel angular pressing (ECAP) generated effective chain penetration and strong intermolecular interactions between the amorphous cellulose and WG components. The micro-cracking of the obtained materials was minimized, and the processing temperature was reduced. The crystallinity of the cellulose component was also decreased, whereas the crystalline size and regularity was less modified. The present study has further demonstrated that ECAP is a promising methodology to produce renewable and biodegradable "wood plastics" from cellulose-based agricultural waste. PMID:23399278

  14. Repetitive forging (RF) using inclined punches as a new bulk severe plastic deformation method

    International Nuclear Information System (INIS)

    A new bulk severe plastic deformation method based on repetitive forging (RF) using inclined punches is proposed. This process consists of two half cycles. In the first half cycle, a square cross section deforms to parallelogram by forging with two inclined punches, and the parallelogram cross section is forged back to square using two flat punches in the second half cycle. This method was applied to commercially pure copper and significant grain refinement was achieved after four passes of RF. The results showed that significant improvement in the mechanical properties was obtained. Notable increase of yield and ultimate strengths corresponding to 358 MPa and 381 MPa after four passes of RF from the initial values of 121 MPa and 230.5 MPa is detectable. Microhardness increases to about 100 Hv after four passes of RF from the initial value of 53 Hv. Finite element (FE) results illustrate that RF is able to impose extremely high plastic strains to the materials. In the RF process, the processed samples have the same dimensions and geometry as those of the initial sample without any waste material and there is no need for back pressure.

  15. Micromechanical Modeling the Plastic Deformation of Particle-Reinforced Bulk Metallic Glass Composites

    Science.gov (United States)

    Jiang, Yunpeng; Shi, Xueping; Qiu, Kun

    2015-08-01

    A micromechanics model was employed to investigate the mechanical performance of particle-reinforced bulk metallic glass (BMG) composites. The roles of shear banding in the tensile deformation are accounted for in characterizing the strength and ductility of ductile particle-filled BMGs. For the sake of simplicity and convenience, shear band was considered to be a micro-crack in the present model. The strain-based Weibull probability distribution function and percolation theory were applied to describe the equivalent micro-crack evolution, which results in the progressive failure of BMG composites. Based on the developed model, the influences of shear bands on the plastic deformation were discussed for various microstructures. The predictions were in fairly good agreement with the experimental data from the literatures, which confirms that the developed analytical model is able to successfully describe the mechanical properties, such as yield strength, strain hardening, and stress softening elongation of composites. The present results will shed some light on optimizing the microstructures in effectively improving the tensile ductility of BMG composites.

  16. Fermionic and bosonic mass deformations of N=4 SYM and their bulk supergravity dual

    CERN Document Server

    Bena, Iosif; Kuperstein, Stanislav; Ntokos, Praxitelis; Petrini, Michela

    2015-01-01

    We examine the AdS-CFT dual of arbitrary (non)supersymmetric fermionic mass deformations of N=4 SYM, and investigate how the backreaction of the RR and NS-NS two-form potentials dual to the fermion masses contribute to Coulomb-branch potential of D3 branes, which we interpret as the bulk boson mass matrix. Using representation-theory and supergravity arguments we show that the fermion masses completely determine the trace of this matrix, and that on the other hand its traceless components have to be turned on as non-normalizable modes. Our result resolves the tension between the belief that the AdS bulk dual of the trace of the boson mass matrix (which is not a chiral operator) is a stringy excitation with dimension of order $(g_s N)^{1/4}$ and the existence of non-stringy supergravity flows describing theories where this trace is nonzero, by showing that the stringy mode does not parameterize the sum of the squares of the boson masses but rather its departure from the trace of the square of the fermion mass ...

  17. Calculation of structurally related properties of bulk and surface Si

    International Nuclear Information System (INIS)

    The self-consistent pseudopotential method is applied to study the bulk and surface structurally related properties of Si. Equilibrium configurations are determined by minimizing the total energy of the system; the calculated bulk properties and the surface relaxation of Si are found to be in good agreement with experiment. The surface energy and the surface reconstruction of Si are briefly discussed

  18. Synthesis, microstructure, and deformation mechanisms of CuZr-based bulk metallic glass composites

    OpenAIRE

    Song, Kaikai

    2013-01-01

    In the past, it has been found that CuZr-based BMG composites containing B2 CuZr crystals in the glassy matrix display significant plasticity with obvious work hardening. In this work, it was tried to provide a strategy for pinpointing the formation of CuZr-based BMG composites, to modify the microstructures of these composites, and to clarify their yielding and deformation mechanisms. In order to pinpoint the formation of CuZr-based BMG composites, the phase formation and structural evol...

  19. DEVIATIONS OF STRUCTURE BETWEEN BULK AND FIBER GLASSES

    OpenAIRE

    Stockhorst, H.; Brückner, R.

    1982-01-01

    Fibers from a silicate and a metaphosphate glass, produced by the nozzle drawing process are investigated with respect to their structural properties compared with bulk glass. The drawing parameters - nozzle temperature, mass flow and drawing speed - are varied in a wide range. The following properties are investigated : fiber density, thermal expansion-contraction-behaviour and optical birefringence. All these properties show characteristic deviations from the bulk glass values depending str...

  20. Plastic deformability and precipitation of nanocrystallites during compression for a Cu-Zr-Ti-Sn bulk metallic glass

    International Nuclear Information System (INIS)

    (Cu0.5Zr0.425Ti0.075)99Sn1 bulk metallic glass with a glass transition temperature of 683 K and a supercooled liquid region of 47 K was synthesized by copper mold casting. The bulk glassy alloy exhibits high strength of 1810 MPa and superior plasticity in uniaxial compression at ambient temperature. High resolution transmission electron microscopy for the bulk glassy sample subject to a plastic strain of 3% shows the formation of nanocrystallites in the glassy matrix. The plastic deformability of the (Cu0.5Zr0.425Ti0.075)99Sn1 bulk metallic glass is attributed to the in situ precipitation of nanocrystallites during the compression

  1. Nested structures approach for bulk 3D negative index materials

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Malureanu, Radu; Lavrinenko, Andrei

    2009-01-01

    We propose a generic conceptual idea to obtain bulk 3D negative index metamaterials, which exhibit isotropic properties. The design is based on the nested structures approach, when one element providing magnetic response is inserted into another design with negative dielectric constant. Both...

  2. Influence of thermal treatments and plastic deformation on the atomic mobility in Zr50.7Cu28Ni9Al12.3 bulk metallic glass

    International Nuclear Information System (INIS)

    Highlights: • Atomic mobility in Zr-based metallic glass were evaluated by DMA and nanoindentation. • Atomic mobility is reduced by physical aging while increased by plastic deformation. • The atomic mobility in metallic glasses are related to concentration of “defects”. • Value of the Kohlrausch exponent βKWW in the Zr-based metallic glass is around 0.5. - Abstract: The atomic mobility in Zr50.7Cu28Ni9Al12.3 bulk metallic glass has been evaluated as a function of temperature and the influence of different treatments (thermal annealing, plastic deformation) has been investigated using mechanical spectroscopy and nanoindentation technique. In particular the loss factor has been measured. This parameter is connected to the energy loss during the application of a periodic stress and therefore is sensitive to atomic movements. Master curves can be obtained, confirming the validity of the time–temperature superposition principle. The atomic mobility is reduced during physical aging (also called structural relaxation) but increased after a plastic deformation (a rejuvenation of the material is then induced). In the framework of the nanoindentation tests and mechanical spectroscopy, the concentration of “defects” in metallic glasses increases by deformation (i.e. cold-rolling) while decreases after structural relaxation and crystallization. These results are discussed using the concept of quasi-point defects, which assist the atomic movements

  3. Organic bulk heterojunction photovoltaic structures: design, morphology and properties

    International Nuclear Information System (INIS)

    Main approaches to the design of organic bulk heterojunction photovoltaic structures are generalized and systematized. Novel photovoltaic materials based on fullerenes, organic dyes and related compounds, graphene, conjugated polymers and dendrimers are considered. The emphasis is placed on correlations between the chemical structure and properties of materials. The effect of morphology of the photoactive layer on the photovoltaic properties of devices is analyzed. Main methods of optimization of the photovoltaic properties are outlined. The bibliography includes 338 references

  4. The Lagrangian Deformation Structure of Three-Dimensional Steady Flow

    CERN Document Server

    Lester, Daniel R; Borgne, Tanguy Le; de Barros, Felipe P J

    2016-01-01

    Fluid deformation and strain history are central to wide range of fluid mechanical phenomena ranging from fluid mixing and particle transport to stress development in complex fluids and the formation of Lagrangian coherent structures (LCSs). To understand and model these processes it is necessary to quantify Lagrangian deformation in terms of Eulerian flow properties, currently an open problem. To elucidate this link we develop a Protean (streamline) coordinate transform for steady three-dimensional (3D) flows which renders both the velocity gradient and deformation gradient upper triangular. This frame not only simplifies computation of fluid deformation metrics such as fi?nite-time Lyapunov exponents (FTLEs) and elucidates the deformation structure of the flow, but moreover explicitly recovers kinematic and topological constraints upon deformation such as those related to helicity density and the Poincar\\'{e}-Bendixson theorem. We apply this transform to several classes of steady 3D flow, including helical ...

  5. Evaluation of underground structure deformations caused by blasting load

    OpenAIRE

    Зуєвська, Наталя Валеріївна; Ванчак, Микола Іванович; Туровський, Микола Валерійович

    2015-01-01

    This paper treats the underground blast response of a metallic structure in a soil using LS - DYNA. Given the properties of the soil and the soil - structure interaction, the blast wave propagation in the soil is considered and stress zones and horizontal deformation of the metal structure are presented. The paper shows the dependency between the underground structure deformation and the distance from the source of the explosion. The results of this study provide information about the impact ...

  6. Mechanisms of Formation of Submicron Grain Structures by Severe Deformation

    OpenAIRE

    P.B. Prangnell, Y. Huang

    2007-01-01

    Keynote Presentation in Int. Symposium on Fundamentals of Deformation and Annealing, Manchester, September, 2006.The grain refinement mechanisms operating during severe deformation processes, like ECAE, are discussed using data obtained from model Al-alloys. Refinement occurs predominantly by orientation splitting, micro and macroshear banding, and the geometric requirement for high angle boundary area to increase with strain. The deformation structure evolution is affected strongly by the pr...

  7. Localization of plastic deformation along shear bands in Vitreloy bulk metallic glass during high pressure torsion

    Energy Technology Data Exchange (ETDEWEB)

    Kovács, Zsolt [Department of Materials Physics, Eötvös University, Budapest, H-1518, P.O. Box 32, Budapest (Hungary); Schafler, Erhard [Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, A-1090 Vienna, Boltzmanngasse 5 (Austria); Szommer, Péter [Department of Materials Physics, Eötvös University, Budapest, H-1518, P.O. Box 32, Budapest (Hungary); Révész, Ádám, E-mail: reveszadam@ludens.elte.hu [Department of Materials Physics, Eötvös University, Budapest, H-1518, P.O. Box 32, Budapest (Hungary)

    2014-04-01

    Highlights: • Shear bands were investigated in Vitreloy BMG disks subjected to HPT deformation. • FIB marker lines in an internal surface were analyzed. • Plastic deformation took place by short and wavy shear bands. • Healing of the two part HPT disk were observed along material pile-ups. - Abstract: Microscopic plastic behavior of high purity commercial Vitreloy 1b glassy disks subjected to high pressure torsion was investigated by analyzing the distortion of a marker grid produced by focused ion beam milling. Scanning electron microscopy and atomic force microscopy are applied to measure offsets of shear bands at the surface. Unlike in other macroscopic deformation tests, short and wavy shear bands with submicron offsets and substantial normal offset components are observed indicating concurrent formation of numerous bands. Material pile-ups along major shear bands result in healing of the glass counterparts.

  8. Deformation of spherical CR structures and the universal Picard variety

    OpenAIRE

    Cheng, Jih-Hsin; Tsai, I-Hsun

    1998-01-01

    We study deformation of spherical $CR$ circle bundles over Riemann surfaces of genus > 1. There is a one to one correspondence between such deformation space and the so-called universal Picard variety. Our differential-geometric proof of the structure and dimension of the unramified universal Picard variety has its own interest, and our theory has its counterpart in the Teichmuller theory.

  9. Deformation-strengthening during rolling Cu60Zr20Ti20 bulk metallic glass

    DEFF Research Database (Denmark)

    Cao, Q.P.; Li, J.F.; Hu, Yuyan;

    2007-01-01

    Mechanical strength evolutions during rolling the Cu60Zr20Ti20 bulk metallic glass (BMG) at room temperature (RT) and cryogenic temperature (CT) have been investigated by measuring the microhardness. The hardness slightly increases during the initial rolling stage as a result of the gradually...

  10. Bulk deformation of Ti-6.8Mo-4.5Fe-1.5Al (Timetal LCB) alloy

    International Nuclear Information System (INIS)

    Recently, a low-cost near-β titanium alloy (Timetal LCB Ti-6.8Mo-4.5Fe-1.5Al wt%) containing iron and molybdenum has been developed. This alloy is cold formable in the β microstructure and can be aged to high strengths by precipitating the α phase. Due to its combination of cold formability and high strength, the alloy is a potential replacement for steel components in the automotive industry. The current study was undertaken to evaluate the cold bulk forming characteristics of Timetal LCB for use in lightweight automotive applications. Room-temperature compression tests conducted over a strain-rate range of 0.01 to 5/s indicate that the bulk cold compression of the alloy is affected by two factors: the microstructure and the length-to-diameter aspect ratio of the specimen. In the aged condition, when the microstructure has α-phase particles distributed along flow lines the β-phase matrix, the alloy has the propensity for shear failure when deformed in compression in a direction parallel to the flow lines. In the solution-heat-treated condition, the microstructure consists of β grains with athermal ω phase. In this condition, the alloy can be cold compressed to 75% reduction in height using specimens with aspect ratio of 1.125, but fails by shear for a larger aspect ratio of 1.5. Plastic deformation of the material occurs initially by single slip in most grains, but changes to multiple slip at true plastic strains larger than about 0.15. At a slow strain rate, the deformation is uniform, and the material work hardens continuously

  11. Bulk band structure of Bi2Te3

    DEFF Research Database (Denmark)

    Michiardi, Matteo; Aguilera, Irene; Bianchi, Marco;

    2014-01-01

    The bulk band structure of Bi2Te3 has been determined by angle-resolved photoemission spectroscopy and compared to first-principles calculations. We have performed calculations using the local density approximation (LDA) of density functional theory and the one-shot GW approximation within the all......-electron full-potential linearized augmented-plane-wave (FLAPW) formalism, fully taking into account spin-orbit coupling. Quasiparticle effects produce significant changes in the band structure of Bi2Te3 when compared to LDA. Experimental and calculated results are compared in the spectral regions where...... distinct differences between the LDA and GW results are present. Overall a superior agreement with GW is found, highlighting the importance of many-body effects in the band structure of this family of topological insulators....

  12. Effect of rolling deformation on the microstructure of bulk Cu60Zr20Ti20 metallic glass and its crystallization

    DEFF Research Database (Denmark)

    Cao, Q.P.; Li, J.F.; Zhou, Y.H.; Horsewell, Andy; Jiang, J.Z.

    2006-01-01

    only phase separation at CT, indicating that lowering the temperature can effectively retard the deformation-driven crystallization, and that phase separation is the precursor of crystallization. The appearances of phase separation and especially nanocrystallization reduce the thermal stability of the...... glass since they create advantages in chemical composition and topological structure for the primary crystalline phase to nucleate and grow....

  13. A study of structural foot deformity in stroke patients

    OpenAIRE

    Jang, Gwon Uk; Kweon, Mi Gyoug; Park, Seol; Kim, Ji Young; Park, Ji Won

    2015-01-01

    [Purpose] The aim of this study was to evaluate the structural deformity of the foot joint on the affected side in hemiplegic patients to examine factors that affect this kind of structural deformity. [Subjects and Methods] Thirty-one hemiplegic patients and 32 normal adults participated. The foot posture index (FPI) was used to examine the shape of the foot, the modified Ashworth scale test was used to examine the degree of ankle joint rigidity, the navicular drop test was used to investigat...

  14. Structure of collective modes in transitional and deformed nuclei

    OpenAIRE

    Caprio, M. A.

    2005-01-01

    The collective structure of atomic nuclei intermediate between spherical and quadrupole deformed structure presents challenges to theoretical understanding. However, models have recently been proposed in terms of potentials which are soft with respect to the quadrupole deformation variable beta. To test these models, information is needed on low-spin states of transitional nuclei. The present work involves measurement of electromagnetic decay properties of low-spin states for nuclei in the A=...

  15. Carbon sequestration in coal-beds with structural deformation effects

    International Nuclear Information System (INIS)

    Carbon dioxide sequestration in a coal-bed is a profitable method to reduce the concentration of greenhouse gas in the atmosphere and to recover byproduct methane from the coal seam. The important factor to be considered is the stability of the coal-bed with the increased carbon dioxide injection. It is crucial to avoid carbon dioxide escaping from the coal seam caused by structural deformation. Meanwhile, structural deformation also depends on such properties of the geological coal basin as fracture state and phase equilibrium, especially the porosity, permeability and saturation of the coal seam. In this study, a structural deformation effect was simulated with the purpose of predicting carbon dioxide storage in the environment of a typical unmineable coal seam. As an example, Appalachian Basin is considered in the deformation analysis of carbon dioxide sequestration based on the variable saturation model. Moreover, the comparison between simulations with and without the account of structural deformation is given. The results indicate that modeling of structural deformation in carbon sequestration is feasible by directly coupling structure terms to a variable saturated model. Moreover, introducing structural deformation effects into carbon sequestration modeling is important because it affects the fluid flow and leads to a faster drop of the resulting capillary pressure and relative permeability of the gas phase. This faster drop directly results in the diminished carbon dioxide storage capacity in a coal-bed basin. In addition, structural deformation modeling in carbon sequestration simulations can provide important insights into how to avoid carbon leakage and seepage by monitoring the effective stress and displacement of coal-bed basin during carbon dioxide injection.

  16. Features of zirconium structure formation after severe plastic deformation

    International Nuclear Information System (INIS)

    Evolution of the texture and structural parameters of pure zirconium during the severe plastic deformation process by various methods has been investigated. It was found that the wire-drawing and combination of the ''compression-extrusion'' and wire-drawing are effective methods to obtain homogeneous Nanostructured state in pure zirconium. Possible mechanisms responsible for the observed structure transformation of zirconium during the deformation process are also discussed

  17. Structure of the copper under controlled deformation path conditions

    Directory of Open Access Journals (Sweden)

    D. Kuc

    2009-01-01

    Full Text Available Purpose: One of the methods of plastic deformation under complex deformation path conditions is compression with oscillatory torsion. The observable effects in the form of changing force parameters and structure changes confirm the possibility of deformation to a value many times higher than in the case of methods traditionally applied for forming. This article presents the results of the influence of compression with oscillatory torsion on structural phenomena occurring in copper deformed in such a way.Design/methodology/approach: The examinations were conducted at a compression/oscillatory torsion test stand. The structural examinations were conducted with the use of light and electron microscopy.Findings: In experimental investigations, a reduction of unit pressures was observed when compared to conventional compression. The structural examinations indicated substantial differences in the mechanisms of plastic deformation conducted in both conventional and combined way.Research limitations/implications: There are premises which show that a metallic material of a nanometric structure can be obtained in this way (top-down method, by the accumulation of great plastic deformation. Metallic materials characterized by grain size below 100nm are distinguished by unconventional properties. Further examinations should focus on conducting experiments in a way that would enable grain size reduction to a nanometric size. This will enable the cumulation of greater deformation in the material.Originality/value: The method of compression with oscillatory torsion is an original method developed at the Silesian University of Technology, owing to which it is possible to obtain high deformation values (SPD without risking the loss of cohesion of the material. Thorough understanding of the changes taking place in the structure of metals subjected to compression with oscillatory torsion will allow the optimal choice of process parameters in order to achieve a

  18. Structure of the copper under controlled deformation path conditions

    Directory of Open Access Journals (Sweden)

    G. Niewielski

    2009-03-01

    Full Text Available Purpose: One of the methods of plastic deformation under complex deformation path conditions is compression with oscillatory torsion. The observable effects in the form of changing force parameters and structure changes confirm the possibility of deformation to a value many times higher than in the case of methods traditionally applied for forming. This article presents the results of the influence of compression with oscillatory torsion on structural phenomena occurring in copper deformed in such a way.Design/methodology/approach: The examinations were conducted at a compression/oscillatory torsion test stand. The structural examinations were conducted with the use of light and electron microscopy.Findings: In experimental investigations, a reduction of unit pressures was observed when compared to conventional compression. The structural examinations indicated substantial differences in the mechanisms of plastic deformation conducted in both conventional and combined way.Research limitations/implications: There are premises which show that a metallic material of a nanometric structure can be obtained in this way (top-down method, by the accumulation of great plastic deformation. Metallic materials characterized by grain size below 100nm are distinguished by unconventional properties. Further examinations should focus on conducting experiments in a way that would enable grain size reduction to a nanometric size. This will enable the cumulation of greater deformation in the material.Originality/value: The method of compression with oscillatory torsion is an original method developed at the Silesian University of Technology, owing to which it is possible to obtain high deformation values (SPD without risking the loss of cohesion of the material. Thorough understanding of the changes taking place in the structure of metals subjected to compression with oscillatory torsion will allow the optimal choice of process parameters in order to achieve a

  19. Perovskite-type oxides - Oxygen electrocatalysis and bulk structure

    Science.gov (United States)

    Carbonio, R. E.; Fierro, C.; Tryk, D.; Scherson, D.; Yeager, E.

    1988-01-01

    Perovskite type oxides were considered for use as oxygen reduction and generation electrocatalysts in alkaline electrolytes. Perovskite stability and electrocatalytic activity are studied along with possible relationships of the latter with the bulk solid state properties. A series of compounds of the type LaFe(x)Ni1(-x)O3 was used as a model system to gain information on the possible relationships between surface catalytic activity and bulk structure. Hydrogen peroxide decomposition rate constants were measured for these compounds. Ex situ Mossbauer effect spectroscopy (MES), and magnetic susceptibility measurements were used to study the solid state properties. X ray photoelectron spectroscopy (XPS) was used to examine the surface. MES has indicated the presence of a paramagnetic to magnetically ordered phase transition for values of x between 0.4 and 0.5. A correlation was found between the values of the MES isomer shift and the catalytic activity for peroxide decomposition. Thus, the catalytic activity can be correlated to the d-electron density for the transition metal cations.

  20. Electronic structure and bulk ground state properties of the actinides

    International Nuclear Information System (INIS)

    The principal aim of this chapter is to examine in detail how the actinide elements fit into the periodic table. The actinides are neither a d transition series nor a series like the lanthanides. The electronic structure of the early part of the series finds a close conceptual parallel in a d transition series and the later part of the series is more like the lanthanides. The region of transition between the two parts of the series is of special interest and importance. Among the bulk properties of the elements there are three which are of particular importance; (a) the equilibrium volume, (b) the cohesive energy, and (c) the compressibility, or its inverse, the bulk modulus. The room temperature entropy of the actinides is discussed and its behaviour is related to the room temperature entropy of the other transition metal series. Finally, the ground state magnetism of the actinides is discussed in the context of our understanding of ground state magnetism across the periodic table. (Auth.)

  1. Late-Paleozoic-Mesozoic deformational and deformation related metamorphic structures of Kuznetsk-Altai region

    Science.gov (United States)

    Zinoviev, Sergei

    2014-05-01

    Kuznetsk-Altai region is a part of the Central Asian Orogenic Belt. The nature and formation mechanisms of the observed structure of Kuznetsk-Altai region are interpreted by the author as the consequence of convergence of Tuva-Mongolian and Junggar lithospheric block structures and energy of collision interaction between the blocks of crust in Late-Paleozoic-Mesozoic period. Tectonic zoning of Kuznetsk-Altai region is based on the principle of adequate description of geological medium (without methods of 'primary' state recovery). The initial indication of this convergence is the crust thickening in the zone of collision. On the surface the mechanisms of lateral compression form a regional elevation; with this elevation growth the 'mountain roots' start growing. With an approach of blocks an interblock elevation is divided into various fragments, and these fragments interact in the manner of collision. The physical expression of collision mechanisms are periodic pulses of seismic activity. The main tectonic consequence of the block convergence and collision of interblock units is formation of an ensemble of regional structures of the deformation type on the basis of previous 'pre-collision' geological substratum [Chikov et al., 2012]. This ensemble includes: 1) allochthonous and autochthonous blocks of weakly deformed substratum; 2) folded (folded-thrust) systems; 3) dynamic metamorphism zones of regional shears and main faults. Characteristic of the main structures includes: the position of sedimentary, magmatic and PT-metamorphic rocks, the degree of rock dynamometamorphism and variety rock body deformation, as well as the styles and concentrations of mechanic deformations. 1) block terranes have weakly elongated or isometric shape in plane, and they are the systems of block structures of pre-collision substratum separated by the younger zones of interblock deformations. They stand out among the main deformation systems, and the smallest are included into the

  2. Cascaded second-harmonic generation, summation of the wave vectors of the bulk defect-deformation waves, and generation of multimode micro- and nanostructures by laser irradiation of solids

    International Nuclear Information System (INIS)

    We consider for the first time three-wave interactions of bulk quasi-static defect-deformation (DD) waves (generation of the second DD harmonic and summation of the wave vectors), similar to three-wave interactions in nonlinear optics and acoustics, leading to cascaded broadening of the spectrum of spatial DD harmonics. Based on the theory developed, we interpret the recently observed effect of laser-induced generation of the bulk periodic structure of silver nanoparticles with a discrete spatial spectrum, extending from micro- to nanometres. (nonlinear optical phenomena)

  3. Cascaded second-harmonic generation, summation of the wave vectors of the bulk defect-deformation waves, and generation of multimode micro- and nanostructures by laser irradiation of solids

    Science.gov (United States)

    Emel'yanov, Vladimir I.

    2011-02-01

    We consider for the first time three-wave interactions of bulk quasi-static defect-deformation (DD) waves (generation of the second DD harmonic and summation of the wave vectors), similar to three-wave interactions in nonlinear optics and acoustics, leading to cascaded broadening of the spectrum of spatial DD harmonics. Based on the theory developed, we interpret the recently observed effect of laser-induced generation of the bulk periodic structure of silver nanoparticles with a discrete spatial spectrum, extending from micro- to nanometres.

  4. Stability of Bulk Metallic Glass Structure. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Jain, H.; Williams, D. B.

    2003-06-01

    The fundamental origins of the stability of the (Pd-Ni){sub 80}P{sub 20} bulk metallic glasses (BMGs), a prototype for a whole class of BMG formers, were explored. While much of the properties of their BMGs have been characterized, their glass-stability have not been explained in terms of the atomic and electronic structure. The local structure around all three constituent atoms was obtained, in a complementary way, using extended X-ray absorption fine structure (EXAFS), to probe the nearest neighbor environment of the metals, and extended energy loss fine structure (EXELFS), to investigate the environment around P. The occupied electronic structure was investigated using X-ray photoelectron spectroscopy (XPS). The (Pd-Ni){sub 80}P{sub 20} BMGs receive their stability from cumulative, and interrelated, effects of both atomic and electronic origin. The stability of the (Pd-Ni){sub 80}P{sub 20} BMGs can be explained in terms of the stability of Pd{sub 60}Ni{sub 20}P{sub 20} and Pd{sub 30}Ni{sub 50}P{sub 20}, glasses at the end of BMG formation. The atomic structure in these alloys is very similar to those of the binary phosphide crystals near x=0 and x=80, which are trigonal prisms of Pd or Ni atoms surrounding P atoms. Such structures are known to exist in dense, randomly-packed systems. The structure of the best glass former in this series, Pd{sub 40}Ni{sub 40}P{sub 20} is further described by a weighted average of those of Pd{sub 30}Ni{sub 50}P{sub 20} and Pd{sub 60}Ni{sub 20}P{sub 20}. Bonding states present only in the ternary alloys were found and point to a further stabilization of the system through a negative heat of mixing between Pd and Ni atoms. The Nagel and Tauc criterion, correlating a decrease in the density of states at the Fermi level with an increase in the glass stability, was consistent with greater stability of the Pd{sub x}Ni{sub 80-x}P{sub 20} glasses with respect to the binary alloys of P. A valence electron concentration of 1.8 e/a, which

  5. Changes of structure of austenitic steel caused by hot deformation

    International Nuclear Information System (INIS)

    microstructural parameters such as eg. grain elongation coefficient δ, etc. on enhancing precision of dependencies linking deformation with the structure obtained after recrystallization was found. The obtained results, contribute to the modelling of steel microstructure changes during and after hot deformation developing the thermomechanical models of the plastic working process. (author)

  6. Co2 injection into oil reservoir associated with structural deformation

    KAUST Repository

    El-Amin, Mohamed

    2012-01-01

    In this work, the problem of structural deformation with two-phase flow of carbon sequestration is presented. A model to simulate miscible CO2 injection with structural deformation in the aqueous phase is established. In the first part of this paper, we developed analytical solution for the problem under consideration with certain types of boundary conditions, namely, Dirichlet and Neumann boundary conditions. The second part concerns to numerical simulation using IMPDES scheme. A simulator based on cell-centered finite difference method is used to solve this equations system. Distributions of CO2 saturation, and horizontal and vertical displacements have been introduced.

  7. Structure modulated electrostatic deformable mirror for focus and geometry control.

    Science.gov (United States)

    Nam, Saekwang; Park, Suntak; Yun, Sungryul; Park, Bongje; Park, Seung Koo; Kyung, Ki-Uk

    2016-01-11

    We suggest a way to electrostatically control deformed geometry of an electrostatic deformable mirror (EDM) based on geometric modulation of a basement. The EDM is composed of a metal coated elastomeric membrane (active mirror) and a polymeric basement with electrode (ground). When an electrical voltage is applied across the components, the active mirror deforms toward the stationary basement responding to electrostatic attraction force in an air gap. Since the differentiated gap distance can induce change in electrostatic force distribution between the active mirror and the basement, the EDMs are capable of controlling deformed geometry of the active mirror with different basement structures (concave, flat, and protrusive). The modulation of the deformed geometry leads to significant change in the range of the focal length of the EDMs. Even under dynamic operations, the EDM shows fairly consistent and large deformation enough to change focal length in a wide frequency range (1~175 Hz). The geometric modulation of the active mirror with dynamic focus tunability can allow the EDM to be an active mirror lens for optical zoom devices as well as an optical component controlling field of view. PMID:26832237

  8. Analysing intracellular deformation of polymer capsules using structured illumination microscopy

    Science.gov (United States)

    Chen, Xi; Cui, Jiwei; Sun, Huanli; Müllner, Markus; Yan, Yan; Noi, Ka Fung; Ping, Yuan; Caruso, Frank

    2016-06-01

    Understanding the behaviour of therapeutic carriers is important in elucidating their mechanism of action and how they are processed inside cells. Herein we examine the intracellular deformation of layer-by-layer assembled polymer capsules using super-resolution structured illumination microscopy (SIM). Spherical- and cylindrical-shaped capsules were studied in three different cell lines, namely HeLa (human epithelial cell line), RAW264.7 (mouse macrophage cell line) and differentiated THP-1 (human monocyte-derived macrophage cell line). We observed that the deformation of capsules was dependent on cell line, but independent of capsule shape. This suggests that the mechanical forces, which induce capsule deformation during cell uptake, vary between cell lines, indicating that the capsules are exposed to higher mechanical forces in HeLa cells, followed by RAW264.7 and then differentiated THP-1 cells. Our study demonstrates the use of super-resolution SIM in analysing intracellular capsule deformation, offering important insights into the cellular processing of drug carriers in cells and providing fundamental knowledge of intracellular mechanobiology. Furthermore, this study may aid in the design of novel drug carriers that are sensitive to deformation for enhanced drug release properties.Understanding the behaviour of therapeutic carriers is important in elucidating their mechanism of action and how they are processed inside cells. Herein we examine the intracellular deformation of layer-by-layer assembled polymer capsules using super-resolution structured illumination microscopy (SIM). Spherical- and cylindrical-shaped capsules were studied in three different cell lines, namely HeLa (human epithelial cell line), RAW264.7 (mouse macrophage cell line) and differentiated THP-1 (human monocyte-derived macrophage cell line). We observed that the deformation of capsules was dependent on cell line, but independent of capsule shape. This suggests that the mechanical forces

  9. Features of deformation of poroelastic media with low structural strength

    Science.gov (United States)

    Goldstein, Robert; Gordeev, Yurii; Kornev, Konstantin

    Many natural and technological processes are associated with deformation and fracture of saturated or being saturated poroelastic media. Among such processes one can mention fluid soaking through a dam, fluid inflow to the cracks of hydraulic fracture, polishing using porous materials and special fluids, flow in catalytic pellets. All these processes are accompanied by deformation and fracture of a matrix with fluid flow. The effects at the interface porous body-fluid are essential for the processes. The specific features of deformation of poroelastic media with low structural strength are considered in this paper. The compressibility of the matrix skeleton is larger as compared to the compressibility of the saturating fluid in such media. It is shown that the oozing of the fluid at the surface of the poroelastic medium occurs in the consolidated flow regime under the action of `fluid piston' like loads if the structural strength of the medium is low. This result is obtained for both plane (deformation of a layer or halfinfinite medium) and centrally symmetric (deformation of a sphere) problems.

  10. Low temperature diffusion process using rare earth-Cu eutectic alloys for hot-deformed Nd-Fe-B bulk magnets

    Energy Technology Data Exchange (ETDEWEB)

    Akiya, T., E-mail: akiya.takahiro@nims.go.jp; Sepehri-Amin, H.; Ohkubo, T. [Elements Strategy Initiative Center for Magnetic Materials, National Institute for Materials Science, Tsukuba 305-0047 (Japan); Liu, J.; Hono, K. [Elements Strategy Initiative Center for Magnetic Materials, National Institute for Materials Science, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8577 (Japan); Hioki, K.; Hattori, A. [Daido Steel Co., LTD, Nagoya 457-8545 (Japan)

    2014-05-07

    The low temperature grain boundary diffusion process using RE{sub 70}Cu{sub 30} (RE = Pr, Nd) eutectic alloy powders was applied to sintered and hot-deformed Nd-Fe-B bulk magnets. Although only marginal coercivity increase was observed in sintered magnets, a substantial enhancement in coercivity was observed when the process was applied to hot-deformed anisotropic bulk magnets. Using Pr{sub 70}Cu{sub 30} eutectic alloy as a diffusion source, the coercivity was enhanced from 1.65 T to 2.56 T. The hot-deformed sample expanded along c-axis direction only after the diffusion process as RE rich intergranular layers parallel to the broad surface of the Nd{sub 2}Fe{sub 14}B are thickened in the c-axis direction.

  11. Low temperature diffusion process using rare earth-Cu eutectic alloys for hot-deformed Nd-Fe-B bulk magnets

    International Nuclear Information System (INIS)

    The low temperature grain boundary diffusion process using RE70Cu30 (RE = Pr, Nd) eutectic alloy powders was applied to sintered and hot-deformed Nd-Fe-B bulk magnets. Although only marginal coercivity increase was observed in sintered magnets, a substantial enhancement in coercivity was observed when the process was applied to hot-deformed anisotropic bulk magnets. Using Pr70Cu30 eutectic alloy as a diffusion source, the coercivity was enhanced from 1.65 T to 2.56 T. The hot-deformed sample expanded along c-axis direction only after the diffusion process as RE rich intergranular layers parallel to the broad surface of the Nd2Fe14B are thickened in the c-axis direction

  12. Internal structural evolution and enhanced tensile plasticity of Ti-based bulk metallic glass and composite via cold rolling

    International Nuclear Information System (INIS)

    Highlights: • Enhancement of tensile plasticity was achieved by cold rolling. • The malleable behavior of cold rolled samples is attributed to the atomic structural evolution and elastic property change. • Shear softened region act as a potential nucleation site of shear bands. - Abstract: The influence of cold rolling on the tensile mechanical properties and deformation behavior of Ti-based bulk metallic glass (BMG: Ti40Zr25Ni8Cu9Be18) and β-Ti dendrite reinforced bulk metallic glass matrix composite (BMGMC: Ti40.2Zr18Ni2.85Cu7.65Be12.3Nb19) has been investigated. The cold-rolled BMG and BMGMC samples with 20% thickness reduction ratio exhibit a pronounced tensile plasticity of 0.8% and 4%, respectively. The malleable behavior of the cold-rolled samples originates from the internal structural evolution and modulation of elastic properties

  13. Band Structure Modifications in Deformed InP Quantum Wires

    Directory of Open Access Journals (Sweden)

    V.V. Kuryliuk

    2014-11-01

    Full Text Available The work describes the features of the band structure of deformed InP nanowires with different diameters. It is shown that the bending of quantum wires is capable of creating local minima in the conduction and valence bands which are separated from the surface of the cylindrical wire. This result opens up new possibilities for controlling both the lifetime of photoexcited carriers by keeping them at these minima and the magnitude of the photovoltage in solar energy conversion devices based on quantum wires. The work lies within a common goal aiming to develop new methods of functionalization of nanostructured surfaces using mechanical deformations.

  14. Structural transformations of metastable α''-phase during cold deformation

    International Nuclear Information System (INIS)

    Phase transformations occuring during cold deformation in hardened α+β titanium alloy of the Ti-Al-Mo-Zr-Sn-Si system with 10% summary content of alloying elements are studied by X-ray diffraction analysis. Two stages of trapsformation of metastable α''-phase are found. A conclusiop is made that ability of the alloy containing α''-phase to cold deformation is determined by the presence of favourable texture, by high degree of metastability and by volume portion of α''-phase in the alloy structure

  15. Flat structures on the deformations of Gepner chiral rings

    CERN Document Server

    Belavin, A

    2016-01-01

    We propose a simple method for the computation of the flat coordinates and Saito primitive forms on Frobenius manifolds of the deformations of Jacobi rings associated with isolated singularities. The method is based on using a conjecture about integral representations for the flat coordinates and on the Saito cohomology theory. This reduces the computation to a simple linear problem. We consider the case of the deformed Gepner chiral rings. The knowledge of the flat structures of Frobenius manifolds can be used for exact solution of the models of the topological conformal field theories corresponding to these chiral rings.

  16. Nuclear structure. Volume II. Nuclear deformations

    International Nuclear Information System (INIS)

    Volume II, together with Volume I, contains a systematic treatment of the basis that has been gradually established during the last decades for understanding the vast body of data on nuclear properties and reactions. The presentation involves partly a development of the theoretical concepts and mathematical tools and partly a critical analysis of experimental results in terms of these concepts. While the first volume is concerned with single-particle motion and the formulation of symmetries, the second volume deals with collective rotational and vibrational motion as well as with the coupling of single-particle motion to the collective degrees of freedom. The discussion exploits several different levels of presentation, and this has motivated the division of the material into text, illustrative examples, and appendices. The text represents an attempt at a systematic development of the subject, in which each section is based on the concepts explained in previous sections. The comparison of theoretical concepts with the experimental evidence is contained in the illustrative examples; these examples are worked out in considerable detail and involve the full arsenal of available theoretical tools. The appendices are devoted to the development of general tools of quantal theory and to the analysis of idealized models that provide useful insight into various aspects of nuclear structure. This division of material contributes to making the book self-contained and at the same time provides the opportunity to elucidate the problems from several different points of view without destroying the unity of the concept. The presentation reflects the authors' view of nuclear physics as part of the broad development of concepts describing quantal many-body systems ranging from atoms and condensed matter to the structure of elementary particles

  17. A bounding technique for dynamic plastic deformations of damped structures

    International Nuclear Information System (INIS)

    This paper presents a bounding principle for obtaining bounds on plastic deformations of discrete-type structures subjected to dynamic (mechanical and/or thermal) external actions. The principle holds true for fully specified loading histories, as well as for unknown sequences of short-duration excitations of a given set, independently of whether the structure shakes down or not. The perturbation method herein used enables the principle to generate bounds on different types of deformations, such as plastic strains, residual displacements and plastic work produced within any portion of the structure - just by suitably choosing the perturbation parameters. With the aid of a time discretization, suboptimal and optimal bounds can be computed by means of LP, QP and NLP numerical procedures. The dynamic characteristics of the structure, i.e. its natural frequency and vibration modes, are shown to play a crucial role. A simple numerical example is also presented. (orig.)

  18. Nanolaminate - bulk multilayered Nb-Cu composite: technology, structure, properties

    International Nuclear Information System (INIS)

    The Cu-Nb multilayered composite as a ribbon 50 mm in width and 0,35 mm in thickness was produced by the following procedures constituting a technological cycle: integration of a packet of specific number of layers (16 layers 0,35 mm in thickness both for Cu and Nb), rolling of the packet in vacuum at a temperature of 750-800 oC, cold rolling in air down to the thickness equal to that of one initial layer constituting the composite. The structure of the composites was examined by optical and electron microscopy, x-ray diffraction at all the stages. The hardness was measured in the course of cold rolling for each of 3 technological cycles. Upon completion of 3 cycles a nanolaminate was produced consisting of 32768 layers of 11 nm in thickness, the ribbon thickness being 0,35 mm. A change in the hardness as a function of true deformation has an ordinary parabolic behavior in the first and second cycles. A significant growth of hardness and the change over from the parabolic to the linear behavior of the dependence is observable at a thickness of the layers less than 200 nm in the 3rd cycle. The hardness amounting to 350 HB was observed at layers thickness of 11 nm. Noticeable changes of the hardness and half width of x-ray peaks of Nb and Cu occur after annealing at temperatures above 400 oC. After annealing at 1000 oC copper grains of about 200 - 600 nm in size form which comprise niobium inclusions of about 1-10 nm in size. The hardness drops down to 135 HB. (author)

  19. Structural order in additive processed bulk heterojunction organic solar cells

    Science.gov (United States)

    Rogers, James Thomas

    Considerable academic and industrial efforts have been dedicated to resolving scientific and technological issues associated with the fabrication of efficient plastic solar cells via solution deposition techniques. The most successful strategy used to generate solution processable devices implements a two component donor-acceptor type system composed of a (p-type) narrow bandgap conjugated polymer donor blended with a (n-type) fullerene acceptor. Due to the limited exciton diffusion lengths (~10 nm) inherent to these materials, efficient photoinduced charge generation requires heterojunction formation (i.e. donor/acceptor interfaces) in close proximity to the region of exciton generation. Maximal charge extraction therefore requires that donor and acceptor components form nanoscale phase separated percolating pathways to their respective electrodes. Devices exhibiting these structural characteristics are termed bulk heterojunction devices (BHJ). Although the BHJ architecture highlights the basic characteristics of functional donor-acceptor type organic solar cells, device optimization requires internal order within each phase and proper organization relative to the substrate in order to maximize charge transport efficiencies and minimize charge carrier recombination losses. The economic viability of BHJ solar cells hinges upon the minimization of processing costs; thus, commercially relevant processing techniques should generate optimal structural characteristics during film formation, eliminating the need for additional post deposition processing steps. Empirical optimization has shown that solution deposition using high boiling point additives (e.g. octanedithiol (ODT)) provides a simple and widely used fabrication method for maximizing the power conversion efficiencies of BHJ solar cells. This work will show using x-ray scattering that a small percentage of ODT (~2%) in chlorobenzene induces the nucleation of polymeric crystallites within 2 min of deposition

  20. Improving the mechanical properties of Zr-based bulk metallic glass by controlling the activation energy for β-relaxation through plastic deformation

    Energy Technology Data Exchange (ETDEWEB)

    Adachi, Nozomu; Todaka, Yoshikazu, E-mail: todaka@me.tut.ac.jp; Umemoto, Minoru [Department of Mechanical Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku, Toyohashi, Aichi 441-8580 (Japan); Yokoyama, Yoshihiko [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan)

    2014-09-29

    The mechanism of plastic deformation in bulk metallic glasses (BMGs) is widely believed to be based on a shear transformation zone (STZ). This model assumes that a shear-induced atomic rearrangement occurs at local clusters that are a few to hundreds of atoms in size. It was recently postulated that the potential energy barrier for STZ activation, W{sub STZ}, calculated using the cooperative shear model, is equivalent to the activation energy for β-relaxation, E{sub β}. This result suggested that the fundamental process for STZ activation is the mechanically activated β-relaxation. Since the E{sub β} value and the glass transition temperature T{sub g} of BMGs have a linear relation, that is, because E{sub β} ≈ 26RT{sub g}, the composition of the BMG determines the ease with which the STZ can be activated. Enthalpy relaxation experiments revealed that the BMG Zr{sub 50}Cu{sub 40}Al{sub 10} when deformed by high-pressure torsion (HPT) has a lower E{sub β} of 101 kJ/mol. The HPT-processed samples accordingly exhibited tensile plastic elongation (0.34%) and marked decreases in their yield strength (330 MPa). These results suggest that mechanically induced structural defects (i.e., the free volume and the anti-free volume) effectively act to reduce W{sub STZ} and increase the number of STZs activated during tensile testing to accommodate the plastic strain without requiring a change in the composition of the BMG. Thus, this study shows quantitatively that mechanically induced structural defects can overcome the compositional limitations of E{sub β} (or W{sub STZ}) and result in improvements in the mechanical properties of the BMG.

  1. Production, structure, texture, and mechanical properties of severely deformed magnesium

    Science.gov (United States)

    Volkov, A. Yu.; Antonova, O. V.; Kamenetskii, B. I.; Klyukin, I. V.; Komkova, D. A.; Antonov, B. D.

    2016-05-01

    Methods of the severe plastic deformation (SPD) of pure magnesium at room temperature, namely, transverse extrusion and hydroextrusion in a self-destroyed shell, have been developed. The maximum true strain of the samples after the hydroextrusion was e ~ 3.2; in the course of transverse extrusion and subsequent cold rolling, a true strain of e ~ 6.0 was achieved. The structure and mechanical properties of the magnesium samples have been studied in different structural states. It has been shown that the SPD led to a decrease in the grain size d to ~2 μm; the relative elongation at fracture δ increased to ~20%. No active twinning has been revealed. The reasons for the high plasticity of magnesium after SPD according to the deformation modes suggested are discussed from the viewpoint of the hierarchy of the observed structural states.

  2. Tailoring of composite wing structures for elastically produced camber deformations

    Science.gov (United States)

    Rehfield, Lawrence W.; Chang, Stephen; Zischka, Peter J.; Pickings, Richard D.; Holl, Michael W.

    1991-01-01

    Structural concepts have been created which produce chordwise camber deformation that results in enhanced lift. A wing box can be tailored to utilize these concepts with composites. In attempting to optimize the aerodynamic benefits, it is found that there are two optimum designs that are of interest. There is a 'weight' optimum which corresponds to the maximum lift per unit structural weight. There is also a 'lift' optimum that corresponds to maximum absolute lift. Experience indicates that a large weight penalty accompanies the transition from weight to lift optimum designs. New structural models, the basic deformation mechanisms that are utilized and typical analytical results are presented. It appears that lift enhancements of sufficient magnitude can be produced to render this type of wing tailoring of practical interest.

  3. Deformations of Poisson structures by closed 3-forms

    OpenAIRE

    Mokhov, O. I.

    2009-01-01

    We prove that an arbitrary Poisson structure omega^{ij}(u) and an arbitrary closed 3-form T_{ijk}(u) generate the local Poisson structure A^{ij}(u,u_x) = M^i_s(u,u_x)omega^{sj}(u), where M^i_s(u,u_x)(delta^s_j + omega^{sp}(u)T_{pjk}(u)u^k_x) = delta^i_j, on the corresponding loop space. We obtain also a special graded epsilon-deformation of an arbitrary Poisson structure omega^{ij}(u) by means of an arbitrary closed 3-form T_{ijk}(u).

  4. Smart structures for deformable mirrors actuated by shape memory alloy

    Science.gov (United States)

    Riva, M.; Bettini, P.; Di Landro, L.; Sala, G.; Zerbi, F. M.

    2010-07-01

    Deformable mirrors actuated by smart structures are promising devices for next generation astronomical instrumentation. Thermal activated Shape Memory Alloys are materials able to recover their original shape, after an external deformation, if heated above a characteristic temperature. If the recovery of the shape is completely or partially prevented by the presence of constraints, the material can generate recovery stress. Thanks to this feature, these materials can be positively exploited in Smart Structures if properly embedded into host materials. This paper will show the technological processes developed for an efficient use of SMA-based actuators embedded in smart structures tailored to astronomical instrumentation. In particular the analysis of the interface with the host material. Some possible modeling approaches to the actuators behavior will be addressed taking into account trade-offs between detailed analysis and overall performance prediction as a function of the computational time. We developed a combined Finite Element and Raytracing analysis devoted to a parametric performance predictions of a SMA based substrate applicable to deformable mirrors. We took in detail into account the possibility to change the focal length of the mirror keeping a satisfactory image quality. Finally a possible approach with some preliminary results for an efficient control system for the strongly non-linear SMA actuators will be presented.

  5. ROLE OF UNDERGROUND STRUCTURE DEFORMATION VELOCITY IN THE ANALYSIS OF BLAST-RESISTANT STRUCTURES

    Institute of Scientific and Technical Information of China (English)

    赵晓兵; 方秦

    2002-01-01

    The structural deformation velocity plays a significant role in the dynamic calculation of underground blast-resistant structures. The motion differentiating equation of a structure system taking into account the role of deformation velocity of the structure will truthfully describe the actual situation of structural vibration. With the one-dimensional plane wave theory, the expression of load on the structural periphery is developed, and the generalized variation principle for the dynamic analysis of underground arched-bar structures is given. At the same time, the results of the numerical calculation are compared.

  6. ESD performance of LDMOS with source-bulk layout structure optimization

    International Nuclear Information System (INIS)

    To enhance the robustness of LDMOS ESD protection devices, the influence of a source-bulk layout structure is analyzed by theoretical analysis and numerical simulation. Novel structures with varied source-bulk layout structures are fabricated and compared. As demonstrated by TLP testing, the optimized structure has an 88% larger It2 than a conventional one, and its Vt1 is reduced from 55.53 to 50.69 V. (semiconductor devices)

  7. VLBI height corrections due to gravitational deformation of antenna structures

    Science.gov (United States)

    Sarti, P.; Negusini, M.; Abbondanza, C.; Petrov, L.

    2009-12-01

    From an analysis of regional European VLBI data we evaluate the impact of a VLBI signal path correction model developed to account for gravitational deformations of the antenna structures. The model was derived from a combination of terrestrial surveying methods applied to telescopes at Medicina and Noto in Italy. We find that the model corrections shift the derived height components of these VLBI telescopes' reference points downward by 14.5 and 12.2 mm, respectively. No other parameter estimates nor other station positions are affected. Such systematic height errors are much larger than the formal VLBI random errors and imply the possibility of significant VLBI frame scale distortions, of major concern for the International Terrestrial Reference Frame (ITRF) and its applications. This demonstrates the urgent need to investigate gravitational deformations in other VLBI telescopes and eventually correct them in routine data analysis.

  8. Deformation of Zr41 Ti14 CU12.5 Ni10 Be22.5 bulk amorphous alloy under isobaric pressure in super-cooled liquid region

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ke-qin; LU Qi-zhu

    2005-01-01

    The curve of crystallization transition during continuous heating for the Zr41Ti14Cu12.5Ni10Be22.5 bulk amorphous alloy was measured by means of dilatation(Fully automatic transformation recording/measuring instrument) and X-ray diffraction(XRD) method. The deformation behavior of the alloy at various heating rates in the supercooled liquid region was studied. The results show that the glass transition temperature of the alloy increases slightly and the supercooled liquid region(SLR) increases significantly with increasing heating rate. The deformation amount under isobaric pressure of 1 N for the alloy in the SLR increases with increasing heating rate. As the heating rate of the alloy increases from 5 to 100 ℃/min, the amount of deformation of the alloy increases from 8.3% to 45%.

  9. Discrete element simulations of gravitational volcanic deformation. 1; Deformation structures and geometries

    Science.gov (United States)

    Morgan, Julia K.; McGovern, Patrick J.

    2005-01-01

    We have carried out two-dimensional particle dynamics simulations of granular piles subject to frictional Coulomb failure criteria to gain a first-order understanding of different modes of gravitational deformation within volcanoes. Under uniform basal and internal strength conditions, granular piles grow self-similarly, developing distinctive stratigraphies, morphologies, and structures. Piles constructed upon cohesive substrates exhibit particle avalanching, forming outward dipping strata and angle of repose slopes. Systematic decreases in basal strength lead to progressively deeper and steeper internal detachment faults and slip along a basal decollement; landslide forms grade from shallow slumps to deep-seated landslide and, finally, to axial subsidence and outward flank displacements, or volcanic spreading. Surface slopes decrease and develop concave up morphologies with decreasing decollement strength; depositional layers tilt progressively inward. Spatial variations in basal strength cause lateral transitions in pile structure, stratigraphy, and morphology. This approximation of volcanoes as Coulomb granular piles reproduces the richness of deformational structures and surface morphologies in many volcanic settings. The gentle slopes of Hawaiian volcanoes and Olympus Mons on Mars suggest weak basal decollements that enable volcanic spreading. High-angle normal faults, favored above weak decollements, are interpreted in both settings and may explain catastrophic sector collapse in Hawaii and broad aureole deposits surrounding Olympus Mons. In contrast, steeper slopes and shallow detachment faults predominate in the Canary Islands, thought to lack a weak decollement, favoring smaller, more frequent slope failures than predicted for Hawaii. The numerical results provide a useful predictive tool for interpreting dynamic behavior and associated geologic hazards of active volcanoes.

  10. Smart structures for deformable mirrors actuated by piezocomposites

    Science.gov (United States)

    Riva, M.; Di Sanzo, D.; Airoldi, A.; Sala, G.; Zerbi, F. M.

    2010-07-01

    Deformable mirrors actuated by smart structures are promising devices for next generation astronomical instrumentation. The piezo technology and in particular piezoceramics is currently among the most investigated structural materials. Fragility makes Ceramic materials extremely vulnerable to accidental breakage during bonding and embedding processes and limits the ability to comply to curved surfaces (typical of mirrors). Moreover lead-based piezoceramics typically have relevant additional masses. To overcome these limitations, we studied the applicability of composites piezoceramics actuators to smart structures with these purposes. We developed a combined Finite Element and Raytracing analysis devoted to a parametric performance predictions of a smart Piezocomposites based substrate applicable to deformable mirrors. We took in detail into account the possibility to change the focal length of the mirror keeping a satisfactory image quality. In this paper we present a specific type of Piezocomposite actuators and numerical/experimental techniques purposely developed to integrate them into smart structures. We evaluated numerical and experimental results comparing bonding and embedding of these devices.

  11. Structure constants of β deformed super Yang-Mills

    Science.gov (United States)

    David, Justin R.; Sadhukhan, Abhishake

    2013-10-01

    We study the structure constants of the beta deformed theory perturbatively and at strong coupling. We show that the planar one loop corrections to the structure constants of single trace gauge invariant operators in the scalar sector is determined by the anomalous dimension Hamiltonian. This result implies that 3 point functions of the chiral primaries of the theory do not receive corrections at one loop. We then studythe structure constants at strong coupling using the Lunin-Maldacena geometry. We explicitly construct the supergravity mode dual to the chiral primary with three equal U(1) R-charges in the Lunin-Maldacena geometry. We show that the 3 point function of this supergravity mode with semi-classical states representing two other similar chiral primary states but with large U(1) charges to be independent of the beta deformation and identical to that found in the AdS 5 × S 5 geometry. This together with the one-loop result indicate that these structure constants are protected by a non-renormalization theorem. We also show that three point function of U(1) R-currents with classical massive strings is proportional to the R-charge carried by the string solution. This is in accordance with the prediction of the R-symmetry Ward identity.

  12. Efficient Video Stitching Based on Fast Structure Deformation.

    Science.gov (United States)

    Li, Jing; Xu, Wei; Zhang, Jianguo; Zhang, Maojun; Wang, Zhengming; Li, Xuelong

    2015-12-01

    In computer vision, video stitching is a very challenging problem. In this paper, we proposed an efficient and effective wide-view video stitching method based on fast structure deformation that is capable of simultaneously achieving quality stitching and computational efficiency. For a group of synchronized frames, firstly, an effective double-seam selection scheme is designed to search two distinct but structurally corresponding seams in the two original images. The seam location of the previous frame is further considered to preserve the interframe consistency. Secondly, along the double seams, 1-D feature detection and matching is performed to capture the structural relationship between the two adjacent views. Thirdly, after feature matching, we propose an efficient algorithm to linearly propagate the deformation vectors to eliminate structure misalignment. At last, image intensity misalignment is corrected by rapid gradient fusion based on the successive over relaxation iteration (SORI) solver. A principled solution to the initialization of the SORI significantly reduced the number of iterations required. We have compared favorably our method with seven state-of-the-art image and video stitching algorithms as well as traditional ones. Experimental results show that our method outperforms the existing ones compared in terms of overall stitching quality and computational efficiency. PMID:25561603

  13. Fast Detection of Material Deformation through Structural Dissimilarity

    Energy Technology Data Exchange (ETDEWEB)

    Ushizima, Daniela; Perciano, Talita; Parkinson, Dilworth

    2015-10-29

    Designing materials that are resistant to extreme temperatures and brittleness relies on assessing structural dynamics of samples. Algorithms are critically important to characterize material deformation under stress conditions. Here, we report on our design of coarse-grain parallel algorithms for image quality assessment based on structural information and on crack detection of gigabyte-scale experimental datasets. We show how key steps can be decomposed into distinct processing flows, one based on structural similarity (SSIM) quality measure, and another on spectral content. These algorithms act upon image blocks that fit into memory, and can execute independently. We discuss the scientific relevance of the problem, key developments, and decomposition of complementary tasks into separate executions. We show how to apply SSIM to detect material degradation, and illustrate how this metric can be allied to spectral analysis for structure probing, while using tiled multi-resolution pyramids stored in HDF5 chunked multi-dimensional arrays. Results show that the proposed experimental data representation supports an average compression rate of 10X, and data compression scales linearly with the data size. We also illustrate how to correlate SSIM to crack formation, and how to use our numerical schemes to enable fast detection of deformation from 3D datasets evolving in time.

  14. Deformed Structures and Shape Coexistence in Zr-98

    Science.gov (United States)

    Olaizola, Bruno; 8pi Collaboration

    2015-10-01

    The nuclear structure of the zirconium isotopes evolves from a mid-open neutron shell deformed region (80Zr), through a closed shell (90Zr), to a closed subshell (96Zr), and then to a sudden reappearance of deformation (100Zr). This rapid onset of deformation across the Zr isotopes is unprecedented, and the issue of how collectivity appears and disappears in these isotopes is of special interest. Until recently, only 98Zr (and maybe 100Zr) had indirect and weak evidence for shape coexistence, with only speculative interpretation of the experiments. Recent results from high precision B(E2) measurements provided direct evidence of shape coexistence in 94Zr and suggested that it may happen in many other nuclei in this region. In order to provide direct evidence of shape coexistence in 98Zr a high-statistical-quality γγ experiment was carried out with the 8 π spectrometer at ISAC-TRIUMF. The array consists of 20 Compton-suppressed hyper-pure germanium detectors plus β particle and conversion electron detectors. Excited states up to ~ 5 MeV in 98Zr were populated in the β- decay of 98Y Jπ = (0-) and 98mY J = (4,5). Preliminary results on key branching ratios will be presented. This work was supported by the Natural Sciences and Engineering Research Council of Canada and the National Research Council of Canada.

  15. A predictive structural model for bulk metallic glasses

    OpenAIRE

    Laws, K. J.; Miracle, D. B.; Ferry, M.

    2015-01-01

    Great progress has been made in understanding the atomic structure of metallic glasses, but there is still no clear connection between atomic structure and glass-forming ability. Here we give new insights into perhaps the most important question in the field of amorphous metals: how can glass-forming ability be predicted from atomic structure? We give a new approach to modelling metallic glass atomic structures by solving three long-standing problems: we discover a new family of structural de...

  16. Evolution of deformation structures under varying loading conditions followed in situ by high angular resolution 3DXRD

    DEFF Research Database (Denmark)

    Pantleon, Wolfgang; Wejdemann, Christian; Jakobsen, B.;

    2009-01-01

    With high angular resolution three-dimensional X-ray diffraction, individual subgrains are traced in the bulk of a polycrystalline specimen and their dynamics is followed in situ during varying loading conditions. The intensity distribution of single Bragg reflections from an individual grain is...... analyzed in reciprocal space. It consists of sharp high-intensity peaks arising from subgrains superimposed on a cloud of lower intensity arising from dislocation walls. Individual subgrains can be distinguished by their unique combination of orientation and elastic strain. The responses of polycrystalline...... copper to different loading conditions are presented: during uninterrupted tensile deformation, formation of subgrains can be observed concurrently with broadening of the Bragg reflection shortly after onset of plastic deformation. With continued tensile deformation, the subgrain structure develops...

  17. Ocean acidification causes structural deformities in juvenile coral skeletons.

    Science.gov (United States)

    Foster, Taryn; Falter, James L; McCulloch, Malcolm T; Clode, Peta L

    2016-02-01

    Rising atmospheric CO2 is causing the oceans to both warm and acidify, which could reduce the calcification rates of corals globally. Successful coral recruitment and high rates of juvenile calcification are critical to the replenishment and ultimate viability of coral reef ecosystems. Although elevated Pco2 (partial pressure of CO2) has been shown to reduce the skeletal weight of coral recruits, the structural changes caused by acidification during initial skeletal deposition are unknown. We show, using high-resolution three-dimensional x-ray microscopy, that ocean acidification (Pco2 ~900 μatm, pH ~7.7) not only causes reduced overall mineral deposition but also a deformed and porous skeletal structure in newly settled coral recruits. In contrast, elevated temperature (+3°C) had little effect on skeletal formation except to partially mitigate the effects of elevated Pco2. The striking structural deformities we observed show that new recruits are at significant risk, being unable to effectively build their skeletons in the Pco2 conditions predicted to occur for open ocean surface waters under a "business-as-usual" emissions scenario [RCP (representative concentration pathway) 8.5] by the year 2100. PMID:26989776

  18. Deformed structure in N = 50 medium mass nuclei

    International Nuclear Information System (INIS)

    The study of neutron rich nuclei at the drip-line and around closed shells gained momentum with recent advancements of experimental techniques using radioactive ion beams and fission fragment. Fission from fast particles has become an important tool and it has been the richest source of neutron-rich intermediate-mass nuclei. Fission of Uranium and neighbouring nuclei produce two neutron-rich fragments of unequal A ∼ 90 and 140, (besides a few neutrons). As the two fragments proceed to the point of separation they become quite deformed. It is thus essential to study the shapes and microscopic structures of these neutron-rich fragments in ground and excited configurations. In this work, the structures and shapes of 86Kr and 88Sr nuclei have been investigated using angular momentum projected Hartree-Fock (PHF) model. To study the possible structure of the ground band and excited deformed bands for closed shell nuclei, the potential energy surface in HF calculations is analyzed for various mass-quadrupole moments

  19. The Detection of Structural Deformation Errors in Attitude Determination

    Institute of Scientific and Technical Information of China (English)

    M. J. Moore; C. Rizos; J. Wang

    2003-01-01

    In the determination of the attitude parameters from a multi-antenna GPS array, one of the major assumptions is that the body frame is rigid at all times. If this assumption is not true then the derived attitude parameters will be in error. It is well known that in airborne platforms the wings often experience some displacement during flight, especially during periods of initializing maneouvres, such as taking off, landing,and banking. Often it is at these points in time that it is most critical to have the most precise attitude parameters.There are a number of techniques available for the detection of modeling errors.The CUSUM algorithm has successfully been implemented in the past to detect small persistent changes. In this paper the authors investigate different methods of generating the residuals, to be tested by the CUSUM algorithm, in an effort to determine which technique is best suited for the detection of structural deformation of an airborne platform. The methods investigated include monitoring the mean of the residuals generated from the difference between the known body frame coordinates, and those calculated from the derived attitude parameters. The generated residuals are then passed to a CUSUM algorithm to detect any small persistent changes. An alternative method involves transforming the generated residuals into the frequency domain through the use of the Fast Fourier Transform. The CUSUM algorithm is then used to detect any frequency changes. The final technique investigated involves transforming the generated residuals using the Haar wavelet. The wavelet coefficients are then monitored by the CUSUM algorithm in order to detect any significant change to the rigidity of the body frame.Detecting structural deformation, and quantifying the degree of deformation, during flight will ensure that these effects can be removed from the system, thus ensuring the most precise and reliable attitude parameter solutions. This paper, through a series

  20. Deformable registration of multi-modal data including rigid structures

    International Nuclear Information System (INIS)

    Multi-modality imaging studies are becoming more widely utilized in the analysis of medical data. Anatomical data from CT and MRI are useful for analyzing or further processing functional data from techniques such as PET and SPECT. When data are not acquired simultaneously, even when these data are acquired on a dual-imaging device using the same bed, motion can occur that requires registration between the reconstructed image volumes. As the human torso can allow non-rigid motion, this type of motion should be estimated and corrected. We report a deformation registration technique that utilizes rigid registration for bony structures, while allowing elastic transformation of soft tissue to more accurately register the entire image volume. The technique is applied to the registration of CT and MR images of the lumbar spine. First a global rigid registration is performed to approximately align features. Bony structures are then segmented from the CT data using semi-automated process, and bounding boxes for each vertebra are established. Each CT subvolume is then individually registered to the MRI data using a piece-wise rigid registration algorithm and a mutual information image similarity measure. The resulting set of rigid transformations allows for accurate registration of the parts of the CT and MRI data representing the vertebrae, but not the adjacent soft tissue. To align the soft tissue, a smoothly-varying deformation is computed using a thin platespline(TPS) algorithm. The TPS technique requires a sparse set of landmarks that are to be brought into correspondence. These landmarks are automatically obtained from the segmented data using simple edge-detection techniques and random sampling from the edge candidates. A smoothness parameter is also included in the TPS formulation for characterization of the stiffness of the soft tissue. Estimation of an appropriate stiffness factor is obtained iteratively by using the mutual information cost function on the result

  1. Deformable registration of multi-modal data including rigid structures

    Energy Technology Data Exchange (ETDEWEB)

    Huesman, Ronald H.; Klein, Gregory J.; Kimdon, Joey A.; Kuo, Chaincy; Majumdar, Sharmila

    2003-05-02

    Multi-modality imaging studies are becoming more widely utilized in the analysis of medical data. Anatomical data from CT and MRI are useful for analyzing or further processing functional data from techniques such as PET and SPECT. When data are not acquired simultaneously, even when these data are acquired on a dual-imaging device using the same bed, motion can occur that requires registration between the reconstructed image volumes. As the human torso can allow non-rigid motion, this type of motion should be estimated and corrected. We report a deformation registration technique that utilizes rigid registration for bony structures, while allowing elastic transformation of soft tissue to more accurately register the entire image volume. The technique is applied to the registration of CT and MR images of the lumbar spine. First a global rigid registration is performed to approximately align features. Bony structures are then segmented from the CT data using semi-automated process, and bounding boxes for each vertebra are established. Each CT subvolume is then individually registered to the MRI data using a piece-wise rigid registration algorithm and a mutual information image similarity measure. The resulting set of rigid transformations allows for accurate registration of the parts of the CT and MRI data representing the vertebrae, but not the adjacent soft tissue. To align the soft tissue, a smoothly-varying deformation is computed using a thin platespline(TPS) algorithm. The TPS technique requires a sparse set of landmarks that are to be brought into correspondence. These landmarks are automatically obtained from the segmented data using simple edge-detection techniques and random sampling from the edge candidates. A smoothness parameter is also included in the TPS formulation for characterization of the stiffness of the soft tissue. Estimation of an appropriate stiffness factor is obtained iteratively by using the mutual information cost function on the result

  2. Structure and properties of copper deformed by severe plastic deformation methods

    Directory of Open Access Journals (Sweden)

    M. Richert

    2011-01-01

    Full Text Available Purpose: The main object of this study is to establish the influence of severe plastic deformation on the microstructure evolution and properties of polycrystalline copper Cu99.99.Design/methodology/approach: Polycrystalline copper Cu99.99 was deformed by cyclic extrusion compression (CEC, equal channel angular pressing (ECAP and hydrostatic extrusion (HE. Additionally the combination of these methods were applying to the sample deformations. The microstructure and properties of samples after different kinds of severe mode of deformations (SPD were examined and compared as well as their properties. The microstructure was investigated by optical (MO and transmission electron microscopy (TEM. The microhardness was measured by PMT3 microhardness tester.Findings: It was found that increase of deformation diminishing the microstructure and leads to the increase of microhardness of samples.Practical implications: The results may be utilized for determination of a relation between microstructure and properties of the copper deformed in the severe plastic deformation process.Originality/value: The results contribute to evaluation properties of the polycrystalline copper deformed to very large strains exerting the typical range of deformations.

  3. FeCoSiBNbCu bulk metallic glass with large compressive deformability studied by time-resolved synchrotron X-ray diffraction

    International Nuclear Information System (INIS)

    By adding 0.5 at. % Cu to the strong but brittle [(Fe0.5Co0.5)0.75Si0.05B0.20]96Nb4 bulk metallic glass, fully amorphous rods with diameters up to 2 mm were obtained. The monolithic samples with 1 mm diameter revealed a fracture strain of 3.80% and a maximum stress of 4143 MPa upon compression, together with a slight work-hardening behavior. SEM micrographs of fractured samples did neither reveal any shear bands on the lateral surface nor the typical vein patterns which characterize ductile fracture. However, some layers appear to have flowed and this phenomenon took place before the brittle final fracture. An estimate of the temperature rise ΔT in the shear plane gives 1039 K, which is large enough to melt a layer of 120 nm. The overall performance and the macroscopic plastic strain depend on the interaction between cleavage-like and viscous flow-like features. Mechanical tests performed in-situ under synchrotron radiation allowed the calculation of the strain tensor components, using the reciprocal-space data and analyzing the shift of the first (the main) and the second broad peak positions in the X-ray diffraction patterns. The results revealed that each atomic shell may have a different stiffness, which may explain the macroscopic compressive plastic deformation. Also, there were no signs of (nano) crystallization induced by the applied stress, but the samples preserve a monolithic amorphous structure until catastrophic failure occurs

  4. Linking structure to fragility in bulk metallic glass-forming liquids

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Shuai, E-mail: shuai.wei@asu.edu, E-mail: m.stolpe@mx.uni-saarland.de [Department of Materials Science and Engineering, Saarland University, Campus C63, 66123 Saarbrücken (Germany); Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287 (United States); Stolpe, Moritz, E-mail: shuai.wei@asu.edu, E-mail: m.stolpe@mx.uni-saarland.de; Gross, Oliver; Gallino, Isabella; Hembree, William; Busch, Ralf [Department of Materials Science and Engineering, Saarland University, Campus C63, 66123 Saarbrücken (Germany); Evenson, Zach [Department of Materials Science and Engineering, Saarland University, Campus C63, 66123 Saarbrücken (Germany); Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln (Germany); Bednarcik, Jozef [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22603 Hamburg (Germany); Kruzic, Jamie J. [Material Science, School of Mechanical, Industrial, and Manufacturing Engineering, Oregon State University, Corvallis, Oregon 97331 (United States)

    2015-05-04

    Using in-situ synchrotron X-ray scattering, we show that the structural evolution of various bulk metallic glass-forming liquids can be quantitatively connected to their viscosity behavior in the supercooled liquid near T{sub g}. The structural signature of fragility is identified as the temperature dependence of local dilatation on distinct key atomic length scales. A more fragile behavior results from a more pronounced thermally induced dilatation of the structure on a length scale of about 3 to 4 atomic diameters, coupled with shallower temperature dependence of structural changes in the nearest neighbor environment. These findings shed light on the structural origin of viscous slowdown during undercooling of bulk metallic glass-forming liquids and demonstrate the promise of predicting the properties of bulk metallic glasses from the atomic scale structure.

  5. Linking structure to fragility in bulk metallic glass-forming liquids

    International Nuclear Information System (INIS)

    Using in-situ synchrotron X-ray scattering, we show that the structural evolution of various bulk metallic glass-forming liquids can be quantitatively connected to their viscosity behavior in the supercooled liquid near Tg. The structural signature of fragility is identified as the temperature dependence of local dilatation on distinct key atomic length scales. A more fragile behavior results from a more pronounced thermally induced dilatation of the structure on a length scale of about 3 to 4 atomic diameters, coupled with shallower temperature dependence of structural changes in the nearest neighbor environment. These findings shed light on the structural origin of viscous slowdown during undercooling of bulk metallic glass-forming liquids and demonstrate the promise of predicting the properties of bulk metallic glasses from the atomic scale structure

  6. Effect of deformation diagram on molybdenum structure and properties

    International Nuclear Information System (INIS)

    Effect of deformation diagram on a tendency to lamination and mechanical properties of disks made of molybdenum alloy is studied. Investigated samples were subjected to hot rolling or forging. X-ray structural analysis of texture is carried out along with estimation of the level of mechanical properties across item cross section. Sample mechanical bending tests were conducted. Sample microstructure is also studied. It is shown that rolled molybdenum has a tendency to lamination, but forged molybdenum is free of such a tendency. Forged sample ductility is practically equal in all directionse but rolled sample ductility in a surface layer is high and decreases with depth. A conclusion is drawn that forged sample grains in a setting surface are equiaxial, but distinct deformation texture is observed for rolled samples and their grains are elongated in the direction of rolling. A conclusion is made that a flow diagram of the process of disk fabrication by forging or stamping ppovides a necessary complex of physicomechanical properties of metal as compared to polling, and metal discharge coefficient decreases sharply in this case

  7. On Hopf algebroid structure of kappa-deformed Heisenberg algebra

    CERN Document Server

    Lukierski, Jerzy; Woronowicz, Mariusz

    2016-01-01

    The $(4+4)$-dimensional $\\kappa$-deformed quantum phase space as well as its $(10+10)$-dimensional covariant extension by the Lorentz sector can be described as Heisenberg doubles: the $(10+10)$-dimensional quantum phase space is the double of $D=4$ $\\kappa$-deformed Poincar\\'e Hopf algebra $\\mathbb{H}$ and the standard $(4+4)$-dimensional space is its subalgebra generated by $\\kappa$-Minkowski coordinates $\\hat{x}_\\mu$ and corresponding commuting momenta $\\hat{p}_\\mu$. Every Heisenberg double appears as the total algebra of a Hopf algebroid over a base algebra which is in our case the coordinate sector. We exhibit the details of this structure, namely the corresponding right bialgebroid and the antipode map. We rely on algebraic methods of calculation in Majid-Ruegg bicrossproduct basis. The target map is derived from a formula by J-H. Lu. The coproduct takes values in the bimodule tensor product over a base, what is expressed as the presence of coproduct gauge freedom.

  8. Modeling level structures of odd-odd deformed nuclei

    International Nuclear Information System (INIS)

    A technique for modeling quasiparticle excitation energies and rotational parameters in odd-odd deformed nuclei has been applied to actinide species where new experimental data have been obtained by use of neutron-capture gamma-ray spectroscopy. The input parameters required for the calculation were derived from empirical data on single-particle excitations in neighboring odd-mass nuclei. Calculated configuration-specific values for the Gallagher-Moszkowski splittings were used. Calculated and experimental level structures for 238Np, 244Am, and 250Bk are compared, as well as those for several nuclei in the rare-earth region. The agreement for the actinide species is excellent, with bandhead energies deviating 22 keV and rotational parameters 5%, on the average. Corresponding average deviations for five rare-earth nuclei are 47 keV and 7%. Several applications of this modeling technique are discussed. 18 refs., 5 figs., 4 tabs

  9. Chemical, electronic, and magnetic structure of LaFeCoSi alloy: Surface and bulk properties

    International Nuclear Information System (INIS)

    We investigate the chemical, electronic, and magnetic structure of the magnetocaloric LaFeCoSi compound with bulk and surface sensitive techniques. We put in evidence that the surface retains a soft ferromagnetic behavior at temperatures higher than the Curie temperature of the bulk due to the presence of Fe clusters at the surface only. This peculiar magnetic surface effect is attributed to the exchange interaction between the ferromagnetic Fe clusters located at the surface and the bulk magnetocaloric alloy, and it is used here to monitor the magnetic properties of the alloy itself.

  10. Comparing In Situ and Bulk Constitutive Properties of a Structural Adhesive

    OpenAIRE

    Grohs, Joshua Walter

    2007-01-01

    In the continuing quest for more efficient designs, structural adhesives are being used in place of, or with, traditional fastening methods; however designing with adhesives is refined as traditional methods. To obtain the adhesive design properties, tests are often performed on bulk tensile and bonded shear specimens. Questions remain about the relationship between properties obtained from in situ adhesive joints and bulk adhesive specimens. As a result, an experimental plan was developed...

  11. Deformation Quantization of Poisson Structures Associated to Lie Algebroids

    Directory of Open Access Journals (Sweden)

    Nikolai Neumaier

    2009-09-01

    Full Text Available In the present paper we explicitly construct deformation quantizations of certain Poisson structures on E*, where E → M is a Lie algebroid. Although the considered Poisson structures in general are far from being regular or even symplectic, our construction gets along without Kontsevich's formality theorem but is based on a generalized Fedosov construction. As the whole construction merely uses geometric structures of E we also succeed in determining the dependence of the resulting star products on these data in finding appropriate equivalence transformations between them. Finally, the concreteness of the construction allows to obtain explicit formulas even for a wide class of derivations and self-equivalences of the products. Moreover, we can show that some of our products are in direct relation to the universal enveloping algebra associated to the Lie algebroid. Finally, we show that for a certain class of star products on E* the integration with respect to a density with vanishing modular vector field defines a trace functional.

  12. Internal structural evolution and enhanced tensile plasticity of Ti-based bulk metallic glass and composite via cold rolling

    Energy Technology Data Exchange (ETDEWEB)

    Park, J.M., E-mail: jinman_park@hotmail.com [Global Technology Center, Samsung Electronics Co., Ltd., Suwon, Gyeonggi-do 443-742 (Korea, Republic of); Lim, K.R. [Light Metal Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsan-gu, Changwon, Gyeongnam 642-831 (Korea, Republic of); Park, E.S.; Hong, S.; Park, K.H. [Global Technology Center, Samsung Electronics Co., Ltd., Suwon, Gyeonggi-do 443-742 (Korea, Republic of); Eckert, J. [IFW Dresden, Institute for Complex Materials, P.O. Box 27 01 16, D-01171 Dresden (Germany); TU Dresden, Institute of Materials Science, D-01062 Dresden (Germany); Kim, D.H., E-mail: dohkim@yonsei.ac.kr [Center for Non-crystalline Materials, Department of Materials Science and Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)

    2014-12-05

    Highlights: • Enhancement of tensile plasticity was achieved by cold rolling. • The malleable behavior of cold rolled samples is attributed to the atomic structural evolution and elastic property change. • Shear softened region act as a potential nucleation site of shear bands. - Abstract: The influence of cold rolling on the tensile mechanical properties and deformation behavior of Ti-based bulk metallic glass (BMG: Ti{sub 40}Zr{sub 25}Ni{sub 8}Cu{sub 9}Be{sub 18}) and β-Ti dendrite reinforced bulk metallic glass matrix composite (BMGMC: Ti{sub 40.2}Zr{sub 18}Ni{sub 2.85}Cu{sub 7.65}Be{sub 12.3}Nb{sub 19}) has been investigated. The cold-rolled BMG and BMGMC samples with 20% thickness reduction ratio exhibit a pronounced tensile plasticity of 0.8% and 4%, respectively. The malleable behavior of the cold-rolled samples originates from the internal structural evolution and modulation of elastic properties.

  13. Incorporating mesh-insensitive structural stress into the fatigue assessment procedure of common structural rules for bulk carriers

    Directory of Open Access Journals (Sweden)

    Kim Seong-Min

    2015-01-01

    Full Text Available This study introduces a fatigue assessment procedure using mesh-insensitive structural stress method based on the Common Structural Rules for Bulk Carriers by considering important factors, such as mean stress and thickness effects. The fatigue assessment result of mesh-insensitive structural stress method have been compared with CSR procedure based on equivalent notch stress at major hot spot points in the area near the ballast hold for a 180 K bulk carrier. The possibility of implementing mesh-insensitive structural stress method in the fatigue assessment procedure for ship structures is discussed.

  14. Regularities of structure formation during hot deformation of austenite in alloy steels

    International Nuclear Information System (INIS)

    Regularities of substructure formation during hot working of austenite in 110Kh6 and 40Kh8G8 alloy steels, structural peculiarities and relations between structure development and a hot deformation curve were investigated. The possibility of structure formation modeling is also evaluated for deformation under commercial procedure conditions. Hot deformation during high temperatue thermomechanical treatment was carried out by rolling and compression. It is found that in alloy steel austenite during hot deformation up to 7-10% the processes of intensive strain hardening develop which result in formation of substructure with high density of dislocations either distributed uniformly or forming a cellular type substructure. Strain softening processes (dynamic polygonization) arise with a deformation degree increase. The relationship found between a hot deformation curve and structural changes during hot working of alloy steel austenite provides the option for conditions of high temperature thermomechanical treatment of commerical alloy steels softening according to a dynamic polygonization mechanism

  15. Dislocation Structures in Creep-deformed Polycrystalline MgO

    DEFF Research Database (Denmark)

    Bilde-Sørensen, Jørgen

    1972-01-01

    Secondary creep of polycrystalline MgO with grain sizes of 100 and 190 μm was investigated at 1300° to 1460°C under compressive loads of 2.5 to 5.5 kgf/mm2. The dependence of creep rate on load follows a power law with an exponent of 3.2±0.3. The process is thermally activated, with an activation...... energy of 76 ± 12 kcal/mol. The creep rate is independent of grain size. The dislocation structure was investigated by transmission electron microscopy. The total dislocation density follows the relation, σ=bG√ρ, commonly found for metals. The dislocations form a 3-dimensional network in which many...... dislocation segments lie in their slip or climb planes. On the basis of this structure, a model is proposed in which glide is the principal cause of deformation but the rate-limiting process, i.e. annealing of the network, is diffusion-controlled. Theoretical estimates and experimental results agree within 1...

  16. Multidisciplinary Aerodynamic-Structural Shape Optimization Using Deformation (MASSOUD)

    Science.gov (United States)

    Samareh, Jamshid A.

    2000-01-01

    This paper presents a multidisciplinary shape parameterization approach. The approach consists of two basic concepts: (1) parameterizing the shape perturbations rather than the geometry itself and (2) performing the shape deformation by means of the soft object animation algorithms used in computer graphics. Because the formulation presented in this paper is independent of grid topology, we can treat computational fluid dynamics and finite element grids in the same manner. The proposed approach is simple, compact, and efficient. Also, the analytical sensitivity derivatives are easily computed for use in a gradient-based optimization. This algorithm is suitable for low-fidelity (e.g., linear aerodynamics and equivalent laminate plate structures) and high-fidelity (e.g., nonlinear computational fluid dynamics and detailed finite element modeling) analysis tools. This paper contains the implementation details of parameterizing for planform, twist, dihedral, thickness, camber, and free-form surface. Results are presented for a multidisciplinary application consisting of nonlinear computational fluid dynamics, detailed computational structural mechanics, and a simple performance module.

  17. Computational mesh generation for vascular structures with deformable surfaces

    International Nuclear Information System (INIS)

    Computational blood flow and vessel wall mechanics simulations for vascular structures are becoming an important research tool for patient-specific surgical planning and intervention. An important step in the modelling process for patient-specific simulations is the creation of the computational mesh based on the segmented geometry. Most known solutions either require a large amount of manual processing or lead to a substantial difference between the segmented object and the actual computational domain. We have developed a chain of algorithms that lead to a closely related implementation of image segmentation with deformable models and 3D mesh generation. The resulting processing chain is very robust and leads both to an accurate geometrical representation of the vascular structure as well as high quality computational meshes. The chain of algorithms has been tested on a wide variety of shapes. A benchmark comparison of our mesh generation application with five other available meshing applications clearly indicates that the new approach outperforms the existing methods in the majority of cases. (orig.)

  18. Validation of Wing Deformation Simulations for the NASA CRM Model using Fluid-Structure Interaction Computations

    OpenAIRE

    Keye, Stefan; Rudnik, Ralf

    2015-01-01

    The virtual determination of static aeroelastic deformations of NASA’s Common Research Model at steady-state flow conditions is described. Aeroelastic equilibrium conditions are computed using a fluid-structure interaction simulation approach based on high-fidelity numerical fluid dynamics and structural analysis methods. The correlation of numerical and experimental results under varying aerodynamic loads and model deformations is investigated and the influence of aeroelastic deformations on wing...

  19. Large deformed structures in Ne-S nuclei near neutron drip-line

    OpenAIRE

    Patra, S. K.; Praharaj, C R

    2010-01-01

    The structure of Ne, Na, Mg, Al, Si and S nuclei near the neutron drip-line region is investigated in the frame-work of relativistic meannfield (RMF) and non-relativistic Skyrme Hartree-Fock formalisms. The drip-line of these nuclei are pointed out. We analysed the large deformation structures and many of these neutron rich nuclei are quite deformed. New magic number are seen for these deformed nuclei.

  20. Direct observation of grain boundary migration during recrystallization within the bulk of a moderately deformed aluminium single crystal

    DEFF Research Database (Denmark)

    Van Boxel, Steven; Schmidt, Søren; Ludwig, Wolfgang;

    2014-01-01

    planar boundary segments (facets) are analyzed using a method that determines the displacements of local boundary segments along parallel lines perpendicular to the facet plane. Facets are observed to form after a certain annealing time. They migrate at a constant rate for extended periods of time and...... remain planar during their migration. A change in the migration rate for one facet has been observed which is not related to changes in the experimental conditions and is most likely to be driven by the changes in grain orientation and/or the local deformation microstructure. The crystallography of the...

  1. Speckle photography applied to measure deformations of very large structures

    Science.gov (United States)

    Conley, Edgar; Morgan, Chris K.

    1995-04-01

    Fundamental principles of mechanics have recently been brought to bear on problems concerning very large structures. Fields of study include tectonic plate motion, nuclear waste repository vault closure mechanisms, the flow of glacier and sea ice, and highway bridge damage assessment and residual life prediction. Quantitative observations, appropriate for formulating and verifying models, are still scarce however, so the need to adapt new methods of experimental mechanics is clear. Large dynamic systems often exist in environments subject to rapid change. Therefore, a simple field technique that incorporates short time scales and short gage lengths is required. Further, the measuring methods must yield displacements reliably, and under oft-times adverse field conditions. Fortunately, the advantages conferred by an experimental mechanics technique known as speckle photography nicely fulfill this rather stringent set of performance requirements. Speckle seemed to lend itself nicely to the application since it is robust and relatively inexpensive. Experiment requirements are minimal -- a camera, high resolution film, illumination, and an optically rough surface. Perhaps most important is speckle's distinct advantage over point-by-point methods: It maps the two dimensional displacement vectors of the whole field of interest. And finally, given the method's high spatial resolution, relatively short observation times are necessary. In this paper we discuss speckle, two variations of which were used to gage the deformation of a reinforced concrete bridge structure subjected to bending loads. The measurement technique proved to be easily applied, and yielded the location of the neutral axis self consistently. The research demonstrates the feasibility of using whole field techniques to detect and quantify surface strains of large structures under load.

  2. Towards an understanding of tensile deformation in Ti-based bulk metallic glass matrix composites with BCC dendrites

    Science.gov (United States)

    Kolodziejska, Joanna A.; Kozachkov, Henry; Kranjc, Kelly; Hunter, Allen; Marquis, Emmanuelle; Johnson, William L.; Flores, Katharine M.; Hofmann, Douglas C.

    2016-03-01

    The microstructure and tension ductility of a series of Ti-based bulk metallic glass matrix composite (BMGMC) is investigated by changing content of the β stabilizing element vanadium while holding the volume fraction of dendritic phase constant. The ability to change only one variable in these novel composites has previously been difficult, leading to uninvestigated areas regarding how composition affects properties. It is shown that the tension ductility can range from near zero percent to over ten percent simply by changing the amount of vanadium in the dendritic phase. This approach may prove useful for the future development of these alloys, which have largely been developed experimentally using trial and error.

  3. High-Resolution Reciprocal Space Mapping for Characterizing Deformation Structures

    DEFF Research Database (Denmark)

    Pantleon, Wolfgang; Wejdemann, Christian; Jakobsen, Bo;

    2014-01-01

    -deformed copper, individual, almost dislocation-free subgrains are identified from high-intensity peaks and distinguished by their unique combination of orientation and elastic strain; dislocation walls manifest themselves as a smooth cloud of lower intensity. The elastic strain shows only minor variations within...... dynamics is followed in situ during varying loading conditions by reciprocal space mapping: during uninterrupted tensile deformation, formation of subgrains is observed concurrently with broadening of Bragg reflections shortly after the onset of plastic deformation. When the traction is terminated, stress...

  4. String field theory. Algebraic structure, deformation properties and superstrings

    International Nuclear Information System (INIS)

    This thesis discusses several aspects of string field theory. The first issue is bosonic open-closed string field theory and its associated algebraic structure - the quantum open-closed homotopy algebra. We describe the quantum open-closed homotopy algebra in the framework of homotopy involutive Lie bialgebras, as a morphism from the loop homotopy Lie algebra of closed string to the involutive Lie bialgebra on the Hochschild complex of open strings. The formulation of the classical/quantum open-closed homotopy algebra in terms of a morphism from the closed string algebra to the open string Hochschild complex reveals deformation properties of closed strings on open string field theory. In particular, we show that inequivalent classical open string field theories are parametrized by closed string backgrounds up to gauge transformations. At the quantum level the correspondence is obstructed, but for other realizations such as the topological string, a non-trivial correspondence persists. Furthermore, we proof the decomposition theorem for the loop homotopy Lie algebra of closed string field theory, which implies uniqueness of closed string field theory on a fixed conformal background. Second, the construction of string field theory can be rephrased in terms of operads. In particular, we show that the formulation of string field theory splits into two parts: The first part is based solely on the moduli space of world sheets and ensures that the perturbative string amplitudes are recovered via Feynman rules. The second part requires a choice of background and determines the real string field theory vertices. Each of these parts can be described equivalently as a morphism between appropriate cyclic and modular operads, at the classical and quantum level respectively. The algebraic structure of string field theory is then encoded in the composition of these two morphisms. Finally, we outline the construction of type II superstring field theory. Specific features of the

  5. Deformed configurations, band structures and spectroscopic properties of = 50 Ge and Se nuclei

    Indian Academy of Sciences (India)

    S K Ghorui; C R Praharaj

    2014-04-01

    The deformed configurations and rotational band structures in =50 Ge and Se nuclei are studied by deformed Hartree–Fock with quadrupole constraint and angular momentum projection. Apart from the `almost’ spherical HF solution, a well-deformed configuration occurs at low excitation. A deformed well-mixed = 1/2+ neutron orbit comes down in energy (from the shell above = 50) to break the = 50 spherical shell closure. A = 7− isomer is predicted in 84Se at fairly low excitation energy. At higher excitation energies (8 MeV), a deformed band with = 7/2+–1/2− (based on $h_{11/2}$) neutron 1p–1h excitation, for 82Ge and 84Se, is shown in our calculation. Our study gives insight into possible deformed structures at spherical shell closure.

  6. Formality theory from Poisson structures to deformation quantization

    CERN Document Server

    Esposito, Chiara

    2015-01-01

    This book is a survey of the theory of formal deformation quantization of Poisson manifolds, in the formalism developed by Kontsevich. It is intended as an educational introduction for mathematical physicists who are dealing with the subject for the first time. The main topics covered are the theory of Poisson manifolds, star products and their classification, deformations of associative algebras and the formality theorem. Readers will also be familiarized with the relevant physical motivations underlying the purely mathematical construction.

  7. Evaluation of soft sediment deformation structures along the Fethiye-Burdur Fault Zone, SW Turkey

    Science.gov (United States)

    Ozcelik, Mehmet

    2016-03-01

    Burdur city is located on lacustrine sedimentary deposits at the northeastern end of the Fethiye-Burdur Fault Zone (FBFZ) in SW Turkey. Fault steps were formed in response to vertical displacement along normal fault zones in these deposits. Soft sediment deformation structures were identified at five sites in lacustrine sediments located on both sides of the FBFZ. The deformed sediments are composed of unconsolidated alternations of sands, silts and clay layers and show different morphological types. The soft sediment deformation structures include load structures, flame structures, slumps, dykes, neptunian dykes, drops and pseudonodules, intercalated layers, ball and pillow structures, minor faults and water escape structures of varying geometry and dimension. These structures are a direct response to fluid escape during liquefaction and fluidization mechanism. The driving forces inferred include gravitational instabilities and hydraulic processes. Geological, tectonic, mineralogical investigations and age analysis were carried out to identify the cause for these soft sediment deformations. OSL dating indicated an age ranging from 15161±744 to 17434±896 years for the soft sediment deformation structures. Geological investigations of the soft sediment deformation structures and tectonic history of the basin indicate that the main factor for deformation is past seismic activity.

  8. Evaluation of soft sediment deformation structures along the Fethiye–Burdur Fault Zone, SW Turkey

    Indian Academy of Sciences (India)

    Mehmet Ozcelik

    2016-03-01

    Burdur city is located on lacustrine sedimentary deposits at the northeastern end of the Fethiye–Burdur Fault Zone (FBFZ) in SW Turkey. Fault steps were formed in response to vertical displacement along normal fault zones in these deposits. Soft sediment deformation structures were identified at five sitesin lacustrine sediments located on both sides of the FBFZ. The deformed sediments are composed of unconsolidated alternations of sands, silts and clay layers and show different morphological types. The soft sediment deformation structures include load structures, flame structures, slumps, dykes, neptuniandykes, drops and pseudonodules, intercalated layers, ball and pillow structures, minor faults and water escape structures of varying geometry and dimension. These structures are a direct response to fluid escape during liquefaction and fluidization mechanism. The driving forces inferred include gravitationalinstabilities and hydraulic processes. Geological, tectonic, mineralogical investigations and age analysis were carried out to identify the cause for these soft sediment deformations. OSL dating indicated an age ranging from 15161±744 to 17434±896 years for the soft sediment deformation structures. Geological investigations of the soft sediment deformation structures and tectonic history of the basin indicate that the main factor for deformation is past seismic activity.

  9. Towards an understanding of tensile deformation in Ti-based bulk metallic glass matrix composites with BCC dendrites

    Science.gov (United States)

    Kolodziejska, Joanna A; Kozachkov, Henry; Kranjc, Kelly; Hunter, Allen; Marquis, Emmanuelle; Johnson, William L; Flores, Katharine M; Hofmann, Douglas C

    2016-01-01

    The microstructure and tension ductility of a series of Ti-based bulk metallic glass matrix composite (BMGMC) is investigated by changing content of the β stabilizing element vanadium while holding the volume fraction of dendritic phase constant. The ability to change only one variable in these novel composites has previously been difficult, leading to uninvestigated areas regarding how composition affects properties. It is shown that the tension ductility can range from near zero percent to over ten percent simply by changing the amount of vanadium in the dendritic phase. This approach may prove useful for the future development of these alloys, which have largely been developed experimentally using trial and error. PMID:26932509

  10. Mechanical behavior and interphase structure in a silica-polystyrene nanocomposite under uniaxial deformation

    Science.gov (United States)

    Rahimi, Mohammad; Iriarte-Carretero, Irene; Ghanbari, Azadeh; Böhm, Michael C.; Müller-Plathe, Florian

    2012-08-01

    The mechanical behavior of polystyrene and a silica-polystyrene nanocomposite under uniaxial elongation has been studied using a coarse-grained molecular dynamics technique. The Young’s modulus, the Poisson ratio and the stress-strain curve of polystyrene have been computed for a range of temperatures, below and above the glass transition temperature. The predicted temperature dependence of the Young’s modulus of polystyrene is compared to experimental data and predictions from atomistic simulations. The observed mechanical behavior of the nanocomposite is related to the local structure of the polymer matrix around the nanoparticles. Local segmental orientational and structural parameters of the deforming matrix have been calculated as a function of distance from nanoparticle’s surface. A thorough analysis of these parameters reveals that the segments close to the silica nanoparticle’s surface are stiffer than those in the bulk. The thickness of the nanoparticle-matrix interphase layer is estimated. The Young’s modulus of the nanocomposite has been obtained for several nanoparticle volume fractions. The addition of nanoparticles results in an enhanced Young’s modulus. A linear relation describes adequately the dependence of Young’s modulus on the nanoparticle volume fraction.

  11. Mechanical behavior and interphase structure in a silica–polystyrene nanocomposite under uniaxial deformation

    International Nuclear Information System (INIS)

    The mechanical behavior of polystyrene and a silica–polystyrene nanocomposite under uniaxial elongation has been studied using a coarse-grained molecular dynamics technique. The Young’s modulus, the Poisson ratio and the stress–strain curve of polystyrene have been computed for a range of temperatures, below and above the glass transition temperature. The predicted temperature dependence of the Young’s modulus of polystyrene is compared to experimental data and predictions from atomistic simulations. The observed mechanical behavior of the nanocomposite is related to the local structure of the polymer matrix around the nanoparticles. Local segmental orientational and structural parameters of the deforming matrix have been calculated as a function of distance from nanoparticle’s surface. A thorough analysis of these parameters reveals that the segments close to the silica nanoparticle’s surface are stiffer than those in the bulk. The thickness of the nanoparticle–matrix interphase layer is estimated. The Young’s modulus of the nanocomposite has been obtained for several nanoparticle volume fractions. The addition of nanoparticles results in an enhanced Young’s modulus. A linear relation describes adequately the dependence of Young’s modulus on the nanoparticle volume fraction. (paper)

  12. A q-deformation of Virasoro and U(1) Kac-Moody algebras with Hopf structure

    International Nuclear Information System (INIS)

    Using a general formalism of a q-deformation of an arbitrary Lie algebra, new kinds of q-deformed centerless Virasoro and U(1) Kac-Moody algebras are found. This q-deformation is associated to an R-matrix of unit square satisfying the quantum Yang-Baxter equation and allows a nontrivial Hopf structure. The central extension is also incorporated in this formalism. (author)

  13. Preferential Acceleration of Coherent Magnetic Structures and Bursty Bulk Flows in Earth's Magnetotail

    CERN Document Server

    Chang, T; Angelopoulos, V; Chang, Tom; Wu, Cheng-chin; Angelopoulos, Vassilis

    2001-01-01

    Observations indicate that the magnetotail convection is turbulent and bi-modal, consisting of fast bursty bulk flows (BBF) and a nearly stagnant background. We demonstrate that this observed phenomenon may be understood in terms of the intermittent interactions, dynamic mergings and preferential accelerations of coherent magnetic structures under the influence of a background magnetic field geometry that is consistent with the development of an X-point mean-field structure.

  14. Exceptional surface and bulk electronic structures in a topological insulator, Bi2Se3

    Science.gov (United States)

    Biswas, Deepnarayan; Thakur, Sangeeta; Balakrishnan, Geetha; Maiti, Kalobaran

    2015-12-01

    The outstanding problem in topological insulators is the bulk metallicity underneath topologically ordered surface states and the appearance of Dirac point far away from the Fermi energy. Enormous efforts are being devoted to get the Dirac point at the Fermi level via exposure to foreign materials so that these materials can be used in technology and realize novel fundamental physics. Ironically, the conclusion of bulk metallicity in the electronic structure is essentially based on the angle resolved photoemission spectroscopy, a highly surface sensitive technique. Here, we employed state-of-the-art hard x-ray photoemission spectroscopy with judiciously chosen experiment geometry to delineate the bulk electronic structure of a topological insulator and a potential thermoelectric material, Bi2Se3. The results exhibit signature of insulating bulk electronic structure with tiny intensities at akin to defect/vacancy induced doped states in the semiconductors. The core level spectra exhibit intense plasmon peak associated to core level excitations manifesting the signature of coupling of electrons to the collective excitations, a possible case of plasmon-phonon coupling. In addition, a new loss feature appear in the core level spectra indicating presence of additional collective excitations in the system.

  15. A gradient structure for systems coupling reaction-diffusion effects in bulk and interfaces

    Science.gov (United States)

    Glitzky, Annegret; Mielke, Alexander

    2013-02-01

    We derive gradient-flow formulations for systems describing drift-diffusion processes of a finite number of species which undergo mass-action type reversible reactions. Our investigations cover heterostructures, where material parameter may depend in a nonsmooth way on the space variable. The main results concern a gradient-flow formulation for electro-reaction-diffusion systems with active interfaces permitting drift-diffusion processes and reactions of species living on the interface and transfer mechanisms allowing bulk species to jump into an interface or to pass through interfaces. The gradient flows are formulated in terms of two functionals: the free energy and the dissipation potential. Both functionals consist of a bulk and an interface integral. The interface integrals determine the interface dynamics as well as the self-consistent coupling to the model in the bulk. The advantage of the gradient structure is that it automatically generates thermodynamically consistent models.

  16. Laboratory approach to the study of dynamic and static bulk anisotropy in rock under high hydrostatic pressure by simultaneous P, S sounding and sample deformation measurements on spheres

    Czech Academy of Sciences Publication Activity Database

    Lokajíček, Tomáš; Svitek, Tomáš; Petružálek, Matěj

    s. l : American Rock Mechanics Association, 2014. ISBN N. [US Rock Mechanics/Geomechanics Symposium /48./. Minneapolis (US), 01.06.2014-04.06.2014] R&D Projects: GA ČR(CZ) GAP104/12/0915; GA ČR GA13-13967S; GA MŠk LH13102 Institutional support: RVO:67985831 Keywords : anisotropy * deformation measurements on spheres Subject RIV: DC - Siesmology, Volcanology, Earth Structure

  17. On the existence of deformed Lie-Poisson structures for quantized groups

    CERN Document Server

    Lyakhovsky, V D

    1996-01-01

    The geometrical description of deformation quantization based on quantum duality principle makes it possible to introduce deformed Lie-Poisson structure. It serves as a natural analogue of classical Lie bialgebra for the case when the initial object is a quantized group. The explicit realization of the deformed Lie-Poisson structure is a difficult problem. We study the special class of such constructions characterized by quite a simple form of tanjent vector fields. It is proved that in such a case it is sufficient to find four Lie compositions that form two deformations of the first order and four Lie bialgebras. This garantees the existence of two families of deformed Lie-Poisson structures due to the intrinsic symmetry of the initial compositions. The explicit example is presented.

  18. Stochastic dislocation kinetics and fractal structures in deforming metals probed by acoustic emission and surface topography measurements

    Energy Technology Data Exchange (ETDEWEB)

    Vinogradov, A. [Laboratory for the Physics of Strength of Materials and Intelligent Diagnostic Systems, Togliatti State University, Togliatti 445667 (Russian Federation); Laboratory of Hybrid Nanostructured Materials, NITU MISiS, Moscow 119490 (Russian Federation); Yasnikov, I. S. [Laboratory for the Physics of Strength of Materials and Intelligent Diagnostic Systems, Togliatti State University, Togliatti 445667 (Russian Federation); Estrin, Y. [Laboratory of Hybrid Nanostructured Materials, NITU MISiS, Moscow 119490 (Russian Federation); Centre for Advanced Hybrid Materials, Department of Materials Engineering, Monash University, Clayton, VIC 3800 (Australia)

    2014-06-21

    We demonstrate that the fractal dimension (FD) of the dislocation population in a deforming material is an important quantitative characteristic of the evolution of the dislocation structure. Thus, we show that peaking of FD signifies a nearing loss of uniformity of plastic flow and the onset of strain localization. Two techniques were employed to determine FD: (i) inspection of surface morphology of the deforming crystal by white light interferometry and (ii) monitoring of acoustic emission (AE) during uniaxial tensile deformation. A connection between the AE characteristics and the fractal dimension determined from surface topography measurements was established. As a common platform for the two methods, the dislocation density evolution in the bulk was used. The relations found made it possible to identify the occurrence of a peak in the median frequency of AE as a harbinger of plastic instability leading to necking. It is suggested that access to the fractal dimension provided by AE measurements and by surface topography analysis makes these techniques important tools for monitoring the evolution of the dislocation structure during plastic deformation—both as stand-alone methods and especially when used in tandem.

  19. Stochastic dislocation kinetics and fractal structures in deforming metals probed by acoustic emission and surface topography measurements

    International Nuclear Information System (INIS)

    We demonstrate that the fractal dimension (FD) of the dislocation population in a deforming material is an important quantitative characteristic of the evolution of the dislocation structure. Thus, we show that peaking of FD signifies a nearing loss of uniformity of plastic flow and the onset of strain localization. Two techniques were employed to determine FD: (i) inspection of surface morphology of the deforming crystal by white light interferometry and (ii) monitoring of acoustic emission (AE) during uniaxial tensile deformation. A connection between the AE characteristics and the fractal dimension determined from surface topography measurements was established. As a common platform for the two methods, the dislocation density evolution in the bulk was used. The relations found made it possible to identify the occurrence of a peak in the median frequency of AE as a harbinger of plastic instability leading to necking. It is suggested that access to the fractal dimension provided by AE measurements and by surface topography analysis makes these techniques important tools for monitoring the evolution of the dislocation structure during plastic deformation—both as stand-alone methods and especially when used in tandem.

  20. Study of BCC and FCC crystal atomic structure under instant plastic deformation

    International Nuclear Information System (INIS)

    Evolution of atomic structure of BCC and FCC crystals under conditions of pulsed external loads and great plastic deformations on the basis of computerized experiments is studied. Deformation of crystals was carried out stage-by-stage up to 32%. The results of computerized experiments showed that by instantaneous external loads plastic deformation, depending on its stage, may proceed either on the account of partial dislocations motion, or on account of twinning , or by means of atomic planes turn and shift. Regularities of the system potential energy turn angle of atomic planes change in dependence on the value of the crystal plastic deformation are determined

  1. Morphology, deformation, and defect structures of TiCr2 in Ti-Cr alloys

    International Nuclear Information System (INIS)

    The morphologies and defect structures of TiCr2 in several Ti-Cr alloys have been examined by optical metallography, x-ray diffraction, and transmission electron microscopy (TEM), in order to explore the room-temperature deformability of the Laves phase TiCr2. The morphology of the Laves phase was found to be dependent upon alloy composition and annealing temperature. Samples deformed by compression have also been studied using TEM. Comparisons of microstructures before and after deformation suggest an increase in twin, stacking fault, and dislocation density within the Laves phase, indicating some but not extensive room-temperature deformability

  2. Mapping the dislocation sub-structure of deformed polycrystalline Ni by scanning microbeam diffraction topography

    International Nuclear Information System (INIS)

    When subjected to plastic deformation, grains within ductile face-centred cubic polycrystals fragment into 'soft', low dislocation density cells separated by 'hard', dislocation-rich walls. Using a narrow-bandwidth, sub-micrometre X-ray beam, we have mapped the deformation structure inside a single grain within a deformed Ni polycrystal. Dislocation multiplication and entanglement was found to vary depending on the physical dimensions of the grain. The method we use overcomes current limitations in classical X-ray topography allowing topographic images to be formed from small, highly deformed grains.

  3. Internal Structure and Mineralogy of Differentiated Asteroids Assuming Chondritic Bulk Composition: The Case of Vesta

    Science.gov (United States)

    Toplis, M. J.; Mizzon, H.; Forni, O.; Monnereau, M.; Prettyman, T. H.; McSween, H. Y.; McCoy, T. J.; Mittlefehldt, D. W.; DeSanctis, M. C.; Raymond, C. A.; Russell, C. T.

    2012-01-01

    Bulk composition (including oxygen content) is a primary control on the internal structure and mineralogy of differentiated asteroids. For example, oxidation state will affect core size, as well as Mg# and pyroxene content of the silicate mantle. The Howardite-Eucrite-Diogenite class of meteorites (HED) provide an interesting test-case of this idea, in particular in light of results of the Dawn mission which provide information on the size, density and differentiation state of Vesta, the parent body of the HED's. In this work we explore plausible bulk compositions of Vesta and use mass-balance and geochemical modelling to predict possible internal structures and crust/mantle compositions and mineralogies. Models are constrained to be consistent with known HED samples, but the approach has the potential to extend predictions to thermodynamically plausible rock types that are not necessarily present in the HED collection. Nine chondritic bulk compositions are considered (CI, CV, CO, CM, H, L, LL, EH, EL). For each, relative proportions and densities of the core, mantle, and crust are quantified. Considering that the basaltic crust has the composition of the primitive eucrite Juvinas and assuming that this crust is in thermodynamic equilibrium with the residual mantle, it is possible to calculate how much iron is in metallic form (in the core) and how much in oxidized form (in the mantle and crust) for a given bulk composition. Of the nine bulk compositions tested, solutions corresponding to CI and LL groups predicted a negative metal fraction and were not considered further. Solutions for enstatite chondrites imply significant oxidation relative to the starting materials and these solutions too are considered unlikely. For the remaining bulk compositions, the relative proportion of crust to bulk silicate is typically in the range 15 to 20% corresponding to crustal thicknesses of 15 to 20 km for a porosity-free Vesta-sized body. The mantle is predicted to be largely

  4. An ultrasonic omni-directional sensor device for coverage structural deformation monitoring

    International Nuclear Information System (INIS)

    Underground space has to be monitored for regional coverage deformations. This issue remains a challenge for current deformation monitoring techniques. In this study, a new high-coverage regional monitoring method is presented to address underground space deformation by using the divergent feature of an ultrasonic sensor. The working principle for coverage regional monitoring, which uses the divergence feature of an ultrasonic beam to increase the monitoring area coverage, is proposed. Space and mathematical models for the ultrasonic beam are also established. An ultrasonic spherical sensor device is designed to achieve all-round monitoring of underground deformation. A longitude–latitude color map histogram is proposed, which enables automatic detection and tracking of omni-directional structural deformation. The new method is illustrated via experiments to determine its validity for deformation monitoring. (technical design note)

  5. Dispersive deformations of the Hamiltonian structure of Euler's equations

    CERN Document Server

    Casati, Matteo

    2015-01-01

    Euler's equations for a two-dimensional system can be written in Hamiltonian form, where the Poisson bracket is the Lie-Poisson bracket associated to the Lie algebra of divergence free vector fields. We show how to derive the Poisson brackets of 2d hydrodynamics of ideal fluids as a reduction from the one associated to the full algebra of vector fields. Motivated by some recent results about the deformations of Lie-Poisson brackets of vector fields, we study the dispersive deformations of the Poisson brackets of Euler's equation and show that, up to the second order, they are trivial.

  6. $L_{\\infty}$ algebra structures of Lie algebra deformations

    OpenAIRE

    Gao, Jining

    2004-01-01

    In this paper,we will show how to kill the obstructions to Lie algebra deformations via a method which essentially embeds a Lie algebra into Strong homotopy Lie algebra or $L_{\\infty}$ algebra. All such obstructions have been transfered to the revelvant $L_{\\infty}$ algebras which contain only three terms

  7. Defect structures and phase transitions of FeRh alloys deformed at high speed deformation

    Energy Technology Data Exchange (ETDEWEB)

    Oshima, Ryuichiro; Hori, Fuminobu; Kibata, Yasunori; Komatsu, Masao; Kiritani, Michio

    2003-06-15

    Fe-Rh alloys of Rh concentrations ranging from 40 to 50at.% and of B2 phase were deformed by use of a compression machine capable of running tests at high speeds of impact. Induced complicated substructures and phases were examined by X-ray diffraction (XRD), transmission electron microscopy (TEM), and positron annihilation spectroscopy (PAS). A characteristic arrangement of L1{sub 0} domains was observed, along with very small transformed A1 domains and dispersed in the residual B2 matrix. On the basis of the experimental results, we suggest a coupling of a pair of shears along {l_brace}112{r_brace}<11-1>{sub B2} for the transformation mechanisms from B2 to L1{sub 0} and A1 phases.

  8. The influence of large deformations on mechanical properties of sinusoidal ligament structures

    Science.gov (United States)

    Strek, Tomasz; Jopek, Hubert; Wojciechowski, Krzysztof W.

    2016-05-01

    Studies of mechanical properties of materials, both theoretical and experimental, usually deal with linear characteristics assuming a small range of deformations. In particular, not much research has been published devoted to large deformations of auxetic structures – i.e. structures exhibiting negative Poisson’s ratio. This paper is focused on mechanical properties of selected structures that are subject to large deformations. Four examples of structure built of sinusoidal ligaments are studied and for each geometry the impact of deformation size and geometrical parameters on the effective mechanical properties of these structures are investigated. It is shown that some of them are auxetic when compressed and non-auxetic when stretched. Geometrical parameters describing sinusoidal shape of ligaments strongly affect effective mechanical properties of the structure. In some cases of deformation, the increase of the value of amplitude of the sinusoidal shape decreases the effective Poisson’s ratio by 0.7. Therefore the influence of geometry, as well as the arrangement of ligaments allows for smart control of mechanical properties of the sinusoidal ligament structure being considered. Given the large deformation of the structure, both a linear elastic material model, and a hyperelastic Neo-Hookean material model are used.

  9. Micro and Macro-scale Thermo-mechanical Modelling of Bulk Deformation in Early-age Cement-based Materials

    Czech Academy of Sciences Publication Activity Database

    Kozák, Vladislav

    2011-01-01

    Roč. 465, - (2011), s. 111-114. ISSN 1013-9826. [MSMF6-Materials structure &Micromechanics of fracture. Brno, 28.06.2010-30.06.2010] R&D Projects: GA ČR GA101/08/1304 Institutional research plan: CEZ:AV0Z20410507 Keywords : cemen-based composites * scale bridging Subject RIV: JI - Composite Materials

  10. Surface states and bulk electronic structure in the candidate type-II Weyl semimetal WTe2

    OpenAIRE

    Bruno, F. Y.; Tamai, A.; Wu, Q. S.; Cucchi, I.; Barreteau, C.; A. de la Torre; Walker, S. McKeown; Riccò, S; Wang, Z.; Kim, T K; Hoesch, M.; Shi, M. (Mimi); Plumb, N. C.; Giannini, E; Soluyanov, A. A.

    2016-01-01

    We report angle-resolved photoemission experiments identifying an arc-like surface state connecting the bulk electron and hole pockets of the candidate type-II Weyl semimetal WTe2. This surface state can be isolated clearly on one of two distinct surface terminations observed experimentally, which we associate with the in-equivalent top and bottom surfaces of the non-centrosymmetric crystal structure. We further use the identification of the two different surfaces to clarify the number of bul...

  11. Micro and Macro-scale Thermo-mechanical Modelling of Bulk Deformation in Early-age Cement-based Materials

    Czech Academy of Sciences Publication Activity Database

    Kozák, Vladislav

    Brno : VUTIUM Brno, 2010 - (Šandera, P.). s. 53-53 ISBN 978-80-214-4112-5. [MSMF6-Materials structure &Micromechanics of fracture. 28.06.2010-30.06.2010, Brno] R&D Projects: GA ČR GA101/08/1304 Institutional research plan: CEZ:AV0Z20410507 Keywords : cemen-based composites * scale bridging * FEM Subject RIV: JI - Composite Materials

  12. Tailoring dislocation structures and mechanical properties of nanostructured metals produced by plastic deformation

    DEFF Research Database (Denmark)

    Huang, Xiaoxu

    2009-01-01

    The presence of a dislocation structure associated with low-angle dislocation boundaries and interior dislocations is a common and characteristic feature in nanostructured metals produced by plastic deformation, and plays an important role in determining both the strength and ductility of the nan...... nanostructured metals. The dislocation structure can be modified by post-process annealing and deformation which points to new ways of optimizing the mechanical properties. Such ways are demonstrated and discussed...

  13. The microphase-separated structure of polyurethane bulk and thin films

    International Nuclear Information System (INIS)

    The microphase-separated structure of polyurethane bulk and thin films were investigated using atomic force microscopy (AFM). The polyurethane (PUs) were synthesized with poly(oxytetramethylene) glycol (PTMG), 4,4'-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BD) by a prepolymer method. The hard segment contents were 34 and 45 wt%. Polarized optical microscopy (POM) revealed that the 34 wt% PUE is homogeneous at a macroscopic level, while the 45 wt% one is macrophase-separated into two phases. One phase forms spherulites of ca. 2-5 μm in diameter. AFM observation for the 34 wt% PUE showed the microphase-separated structure, consisting of hard segment domains and a soft segment matrix. In contrast, for the 45 wt% PUE, a lot of the hard segment domains were observed in the spherulite region, indicating that spherulites include much amount of hard segment component, in contrast, outside of spherulite exhibited similar structure to that of 34 wt% one. For the PU bulk, the different microphase-separated structure in the inside and outside of spherulite was successfully observed for the first time. Also, the microphase-separated structure of PU films was investigated as a function of the film thickness. The PU films exhibited similar microphase-separated structure. For the thicker film (∼200 nm), the interdomain spacing almost corresponded to bulk one. On the other hand, that for the film thickness below 7nm dramatically decreased. This seems to be simply related to a decreasing space. We obtained the experimental data, which the phase-separated domain size of multiblock copolymer decreased with decreasing film thickness. (author)

  14. Correlation between atomic structure evolution and strength in a bulk metallic glass at cryogenic temperature

    OpenAIRE

    Tan, J.; Wang, G.; Z. Y. LIU; Bednarčík, J.; Gao, Yan; Zhai, Q. J.; Mattern, N.; Eckert, J.

    2014-01-01

    A model Zr41.25Ti13.75Ni10Cu12.5Be22.5 (at.%) bulk metallic glass (BMG) is selected to explore the structural evolution on the atomic scale with decreasing temperature down to cryogenic level using high energy X-ray synchrotron radiation. We discover a close correlation between the atomic structure evolution and the strength of the BMG and find out that the activation energy increment of the concordantly atomic shifting at lower temperature is the main factor influencing the strength. Our res...

  15. Local atomic arrangements and electronic structure of Zr-Ni-Al bulk metallic glass

    International Nuclear Information System (INIS)

    Internal energy of a bulk metallic glass (BMG) was investigated by making full use of its relevant crystals. The local atomic arrangements commonly existing both in the BMG and the relevant crystals were identified using experimentally determined radial distribution functions. The electronic structure of the relevant crystals was investigated by discrete variational X alpha (DVXα) cluster calculations and high-resolution photoemission spectroscopy. The present analysis on the electronic structure revealed that the simultaneous formations of characteristic cluster levels and a pseudogap at the Fermi level effectively reduce the internal energy to stabilize BMGs

  16. Correlation between Structures of Bulk Amorphous Zr-Ti-Ni-Cu-Be Alloy in Different States

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The structures of the bulk amorphous Zr41Ti14Cu12.5Ni10.0Be22.5 alloy have been analyzed in solid, supercooled liquid and liquid with X-ray diffraction. The first coordination sphere radii and the first coordination numbers are 0.312 nm, 11.2 in solid state, 0.301 nm, 10.932 in supercooled liquid region and 0.305 nm, 11.296 in liquid state. The structures are the same in different states. But it shows some tendency to crystallizing that the first coordination sphere radius and the first coordination number drop in supercooled liquid region.

  17. Preparation, structure and properties of Fe-based bulk metallic glasses

    OpenAIRE

    R. Nowosielski; R. Babilas

    2010-01-01

    Purpose: The work presents preparation methods, structure characterization and chosen properties analysis of Fe-based bulk metallic glasses in as-cast state.Design/methodology/approach: The studies were performed on Fe43Co14Ni14B20Si5Nb4 metallic glass in form of rings, plates and rods. The amorphous structure of tested samples was examined by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) methods. The thermal properties of the glassy sa...

  18. Inner Structure of Boiling Nucleus and Interfacial Energy Between Nucleus and Bulk Liquid

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Dong; TIAN Yong; PENG Xiao-Feng; WANG Bu-Xuan

    2004-01-01

    @@ A model of two-region structure of a nucleus is proposed to describe nucleus evolution. The interfacial tension between bulk liquid phase and nucleus is dependent on the density gradient in the transition region and varies with the structure change of the transition region. With the interfacial tension calculated using this model, the predicted nucleation rate is very close to the experimental measurement. Furthermore, this model and associated analysis provide solid theoretical evidence to clarify the definition of nucleation rate and understand the nucleation phenomenon with insight into the physical nature.

  19. Dislocations structure in copper cyclically deformed in low amplitude of deformation

    International Nuclear Information System (INIS)

    The evolution of the dislocation structure during the fatigue life of copper, was observed. Fatigue tests were performed, in annealed polycristals, with constant plastic strain amplitude, and interrupted at different percentages of their fatigue lives. Optical and Scanning Electron Microscopy were used for surface analysis and Transmission Electron Microscopy for structural observations. (E.G.)

  20. Preparation, structure and properties of Fe-based bulk metallic glasses

    Directory of Open Access Journals (Sweden)

    R. Nowosielski

    2010-06-01

    Full Text Available Purpose: The work presents preparation methods, structure characterization and chosen properties analysis of Fe-based bulk metallic glasses in as-cast state.Design/methodology/approach: The studies were performed on Fe43Co14Ni14B20Si5Nb4 metallic glass in form of rings, plates and rods. The amorphous structure of tested samples was examined by X-ray diffraction (XRD, transmission electron microscopy (TEM and scanning electron microscopy (SEM methods. The thermal properties of the glassy samples was measured using differential scanning calorimetry (DSC. The soft magnetic properties examination of tested material contained coercive force, initial magnetic permeability and magnetic permeability relaxation measurements. Findings: The XRD and TEM investigations revealed that the studied as-cast samples were amorphous. Broad diffraction halo is typical for metallic amorphous structures that have a large degree of short-range order. The characteristics of the fractured surfaces showed different zones, which might correspond with different amorphous structures of studied materials. The temperature interval of the supercooled liquid region (ΔTx defined by the difference between Tg and Tx, is as large as 56 K for the rod with diameter of 3 mm. Differences in coercivity and magnetic permeability between samples with different thickness might be resulted by some difference of amorphous structure.Practical implications: The centrifugal casting method and the pressure die casting method are useful to produce bulk amorphous materials in form of rings, plats and rods.Originality/value: The preparation of studied Fe-based bulk metallic glass in form of rings, plates and rods is important for the future progress in research and practical application of that glassy materials.

  1. Deformation patterns in cross-sections of twisted bamboo-structured Au microwires

    International Nuclear Information System (INIS)

    In order to investigate an almost pure extrinsic size effect we propose an experimental approach to investigate the deformation structure within single crystalline cross-sections of twisted bamboo-structured Au microwires. The cross-sections of individual 〈1 0 0〉 oriented grains of 25 μm thick Au microwires have been characterized by Laue microdiffraction. The diffraction data were used to calculate the misorientation of each data point with respect to the neutral fiber in the center of the cross-section as well as the kernel average misorientation to map the global and local deformation structure as function of the imposed maximum plastic shear strain. The study is accompanied by crystal plasticity simulations which yield the equivalent plastic strain distributions in the cross-section of the wire. The global deformation structures are directly related to the activated slip systems, resulting from the real orientations of the investigated grains. When averaging the degree of deformation along ring segments, an almost continuous but non-linear increase of misorientation from the center toward the surface is observed, reflecting the overall strain gradient imposed by torsion. For the local deformation structure, pronounced and graded deformation traces are observed which often pass over the neutral fiber of the twisted wire and which are obviously reflecting domains of high geometrically necessary dislocations content

  2. Influence of strain on the copper structure under controlled deformation path conditions

    Directory of Open Access Journals (Sweden)

    G. Niewielski

    2006-04-01

    Full Text Available Purpose: One of the methods of plastic deformation under complex deformation path conditions is compression with oscillatory torsion. The observable effects in the form of changing force parameters and structure changes confirm the possibility of deformation to a value many times higher than in the case of methods traditionally applied for forming. This article presents the results of the influence of compression with oscillatory torsion on structural phenomena occurring in copper deformed in such a way.Design/methodology/approach: The examinations were conducted at a compression/oscillatory torsion test stand. The structural examinations were conducted with the use of light and electron microscopy.Findings: In experimental investigations, a reduction of unit pressures was observed when compared to conventional compression. The structural examinations indicated substantial differences in the mechanisms of plastic deformation conducted in both conventional and combined way.Research limitations/implications: There are premises which show that a metallic material of a nanometric structure can be obtained in this way (top-down method, by the accumulation of great plastic deformation. Metallic materials characterized by grain size below 100nm are distinguished by unconventional properties. Further examinations should focus on conducting experiments in a way that would enable grain size reduction to a nanometric size. This will enable the cumulation of greater deformation in the material.Originality/value: The method of compression with oscillatory torsion is an original method developed at the Silesian University of Technology, owing to which it is possible to obtain high deformation values (SPD without risking the loss of cohesion of the material. Thorough understanding of the changes taking place in the structure of metals subjected to compression with oscillatory torsion will allow the optimal choice of process parameters in order to achieve a

  3. Reconstructed PtFe Alloy Nanoparticles with Bulk-Surface Differential Structure for Methanol Oxidation

    International Nuclear Information System (INIS)

    The high cost of the catalyst material is a large obstacle for the commercialization of Direct Methanol Fuel Cells. In present work, the non-noble metal Fe was added to the conventional Pt/C catalyst in order to lowering the catalyst cost without sacrificing the catalytic performance. A chemically dealloying procedure was adopted to leach out the surface iron atoms and thereby increasing the stability of the catalyst. Through these procedures, the PtFe bulk-surface differential nano-catalyst was obtained. The shift in diffraction angles according to XRD spectra confirms the formation of the alloy structure between Pt and Fe. TEM results indicate that the chemically dealloyed PtFe/C nanoparticles are uniformly-dispersed with optimized average size. The PtFe bulk-surface differential structure is inferred from XPS as no surface Fe atoms are detected in spite of the change in Pt electronic structure. The existence of Fe atoms inside the nanoparticles is further confirmed by the ICP characterization. Electrochemical characterizations show that the catalytic activity is increased to 2.8 times, compared to the Pt/C catalyst, which can be ascribed to the electronic effect of Fe. A further evidence for the electronic effect comes from the CO stripping spectroscopy, in which the onset potential for CO oxidation shifts dramatically toward the negative potential side compared with Pt/C. Owing to the bulk-surface differential structure, the chemically dealloyed PtFe/C catalysts exhibits nearly the same stability compared to that of the Pt/C catalyst

  4. Structure and physical properties of silicon clusters and of vacancy clusters in bulk silicon

    International Nuclear Information System (INIS)

    In this thesis the growth-pattern of free silicon clusters and vacancy clusters in bulk silicon is investigated. The aim is to describe and to better understand the cluster to bulk transition. Silicon structures in between clusters and solids feature new interesting physical properties. The structure and physical properties of silicon clusters can be revealed by a combination of theory and experiment, only. Low-energy clusters are determined with different optimization techniques and a density-functional based tight-binding method. Additionally, infrared and Raman spectra, and polarizabilities calculated within self-consistent field density-functional theory are provided for the smaller clusters. For clusters with 25 to 35 atoms an analysis of the shape of the clusters and the related mobilities in a buffer gas is given. Finally, the clusters observed in low-temperature experiments are identified via the best match between calculated properties and experimental data. Silicon clusters with 10 to 15 atoms have a tricapped trigonal prism as a common subunit. Clusters with up to about 25 atoms follow a prolate growth-path. In the range from 24 to 30 atoms the geometry of the clusters undergoes a transition towards compact spherical structures. Low-energy clusters with up to 240 atoms feature a bonding pattern strikingly different from the tetrahedral bonding in the solid. It follows that structures with dimensions of several Angstroem have electrical and optical properties different from the solid. The calculated stabilities and positron-lifetimes of vacancy clusters in bulk silicon indicate the positron-lifetimes of about 435 ps detected in irradiated silicon to be related to clusters of 9 or 10 vacancies. The vacancies in these clusters form neighboring hexa-rings and, therefore, minimize the number of dangling bonds. (orig.)

  5. The structural relaxation effect on the nanomechanical properties of a Ti-based bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yongjiang, E-mail: yjhuang@hit.edu.cn [State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001 (China); School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Key Laboratory of Micro-Systems and Micro-Structures Manufacturing, Harbin Institute of Technology, Ministry of Education, Harbin 150001 (China); Zhou, Binjun [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Chiu, YuLung, E-mail: y.chiu@bham.ac.uk [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Fan, Hongbo [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wang, Dongjun [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Key Laboratory of Micro-Systems and Micro-Structures Manufacturing, Harbin Institute of Technology, Ministry of Education, Harbin 150001 (China); Sun, Jianfei; Shen, Jun [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2014-09-01

    Highlights: • The effect of structural relaxation on the nano-mechanical behaviors of BMGs is studied. • The indent load at first pop-in event, the hardness and Young’s modulus are enhanced after annealing. • The differences in nanomechanical properties can be attributed to their different atomic structure. - Abstract: Indentation experiments were performed on the as-cast and the annealed Ti-based bulk metallic glass samples to investigate the effect of structural relaxation on the nanomechanical behaviors of the material. The onset of pop-in event, Young’s modulus, and hardness were found to be sensitive to the structural relaxation of the testing material. The difference in nanomechanical properties between the as-cast and annealed BMG samples is interpreted in terms of free volume theory.

  6. Complex three-dimensional structures in Si{1 0 0} using wet bulk micromachining

    International Nuclear Information System (INIS)

    Complex three-dimensional structures for microelectromechanical systems (MEMS) are fabricated in Si{1 0 0} wafers using wet bulk micromachining. The structures are divided into two categories: fixed and freestanding. The fabrication processes for both types utilize single wafers with sequentially deposited nitride and oxide layers, local oxidation of silicon (LOCOS) and two steps of wet anisotropic etching. The fixed structures contain perfectly sharp edges. Thermally deposited oxide is used as the material for the freestanding structures. Wet etching is performed in tetramethyl ammonium hydroxide (TMAH) with and without Triton X-100 (C14H22O(C2H4O)n, n = 9–10). For the fixed structures, both etching steps are performed either in 25 wt% TMAH + Triton or pure TMAH or both, depending upon the type of the structures. In the case of freestanding systems, TMAH + Triton is utilized first, followed by pure TMAH. The fabrication methods enable densely arrayed structures, allowing the manufacture of corrugated diaphragms, compact size liquid (or gas) flow delivery systems, newly shaped mold for soft MEMS structures (e.g. PDMS (polydimethylsiloxane)) and other applications. The present research is an approach to fabricate advanced MEMS structures, extending the range of 3D structures fabricated by silicon anisotropic etching

  7. Structural deformation of metallic uranium surrounding hydride growth sites

    International Nuclear Information System (INIS)

    Highlights: • UH3 formation on uranium surfaces by a controlled uptake of hydrogen at 240 °C. • Large hydride growths (35–125 μm in diameter) form at the surface. • Confined hydride expansion during growth generates stress in the subsurface. • EBSD scans found micro-cracking and twins as forms of stress relief in the metal. - Abstract: Electron backscatter diffraction (EBSD) was utilised to probe the microstructure of uranium metal in the vicinity of surface corrosion pits, resulting from hydrogen exposure (5 × 104 Pa, at 240 °C). Microstructural analysis of the surface revealed a subtle increase of grain orientation variation for grains at the border of the hydride growths. Cross sectional analysis, at pit sites, revealed significant microstructure deformation in the form of crystal twinning and micro-cracking beneath the surface. These observations provide qualitative evidence that local stress intensities generated as a consequence of hydride growth and confinement, were sufficient to cause deformation within the parent metal

  8. Detailed analysis of surface asperity deformation mechanism in diffusion bonding of steel hollow structural components

    Science.gov (United States)

    Zhang, C.; Li, H.; Li, M. Q.

    2016-05-01

    This study focused on the detailed analysis of surface asperity deformation mechanism in similar diffusion bonding as well as on the fabrication of high quality martensitic stainless steel hollow structural components. A special surface with regular patterns was processed to be joined so as to observe the extent of surface asperity deformation under different bonding pressures. Results showed that an undamaged hollow structural component has been obtained with full interfacial contact and the same shear strength to that of base material. Fracture surface characteristic combined with surface roughness profiles distinctly revealed the enhanced surface asperity deformation as the applied pressure increases. The influence of surface asperity deformation mechanism on joint formation was analyzed: (a) surface asperity deformation not only directly expanded the interfacial contact areas, but also released deformation heat and caused defects, indirectly accelerating atomic diffusion, then benefits to void shrinkage; (b) surface asperity deformation readily introduced stored energy difference between two opposite sides of interface grain boundary, resulting in strain induced interface grain boundary migration. In addition, the influence of void on interface grain boundary migration was analyzed in detail.

  9. Experimental Investigation on Near-wall Turbulent Flow Structures over Deformable Roughness

    Science.gov (United States)

    Toloui, Mostafa; John, Nolan; Hong, Jiarong

    2015-11-01

    Wall-bounded turbulent flows over rough surfaces have been studied for almost a century. However, in most of the prior studies, little attention has been paid to the role of roughness mechanical properties, e.g. deformability, in altering the flow characteristics including both general turbulent statistics and near-wall flow structures. In this study, high resolution time-resolved digital in-line holographic PIV is employed to investigate the near-wall turbulent structures as well as turbulent statistics around and above deforming roughness structures. The rough wall samples consisting of tapered cylinders of size 0.5 mm in diameter and 3 mm in height are manufactured from transparent PDMS with similar geometrical features but various deformability levels. The experiments are conducted within an optically index-matched facility (using NaI solution) operating with different Reynolds numbers where roughness samples of different deformability are placed downstream of a 1.2 m long acrylic channel of 50 mm square cross section. The follow-up research envisions a large dataset including various Reynolds numbers and deformability to elucidate the role of roughness deformability on near-wall coherent structures and turbulent energy transport within and above the roughness sublayer. This work is supported by the startup package of Jiarong Hong and the MnDrive Fellowship of Mostafa Toloui from University of Minnesota.

  10. Novel deformation structures of pure titanium induced by room temperature equal channel angular pressing

    OpenAIRE

    Y. J. Chen; Li, Y. J.; Xu, X J; Hjelen, J.; Roven, H.J.

    2014-01-01

    Novel deformation structures of commercial pure (CP) Ti induced by equal channel angular pressing (ECAP) at room temperature have been studied by electron backscattering diffraction (EBSD). All the deformation twins occurring in CP Ti, {101?1}, {112?1}, {101?2} and {112?2} have been revealed surprisingly in one original grain as first, secondary or third generation twins. 3 variants of {101?2} twins have been identified. The deformation mechanism of CP-Ti during ECAP at room temperature in co...

  11. Plastic deformation modelling of tempered martensite steel block structure by a nonlocal crystal plasticity model

    Directory of Open Access Journals (Sweden)

    Martin Boeff

    2014-01-01

    Full Text Available The plastic deformations of tempered martensite steel representative volume elements with different martensite block structures have been investigated by using a nonlocal crystal plasticity model which considers isotropic and kinematic hardening produced by plastic strain gradients. It was found that pronounced strain gradients occur in the grain boundary region even under homogeneous loading. The isotropic hardening of strain gradients strongly influences the global stress–strain diagram while the kinematic hardening of strain gradients influences the local deformation behaviour. It is found that the additional strain gradient hardening is not only dependent on the block width but also on the misorientations or the deformation incompatibilities in adjacent blocks.

  12. Bulk-surface relationship of an electronic structure for high-throughput screening of metal oxide catalysts

    Science.gov (United States)

    Kweun, Joshua Minwoo; Li, Chenzhe; Zheng, Yongping; Cho, Maenghyo; Kim, Yoon Young; Cho, Kyeongjae

    2016-05-01

    Designing metal-oxides consisting of earth-abundant elements has been a crucial issue to replace precious metal catalysts. To achieve efficient screening of metal-oxide catalysts via bulk descriptors rather than surface descriptors, we investigated the relationship between the electronic structure of bulk and that of the surface for lanthanum-based perovskite oxides, LaMO3 (M = Ti, V, Cr, Mn, Fe, Co, Ni, Cu). Through density functional theory calculations, we examined the d-band occupancy of the bulk and surface transition-metal atoms (nBulk and nSurf) and the adsorption energy of an oxygen atom (Eads) on (001), (110), and (111) surfaces. For the (001) surface, we observed strong correlation between the nBulk and nSurf with an R-squared value over 94%, and the result was interpreted in terms of ligand field splitting and antibonding/bonding level splitting. Moreover, the Eads on the surfaces was highly correlated with the nBulk with an R-squared value of more than 94%, and different surface relaxations could be explained by the bulk electronic structure (e.g., LaMnO3 vs. LaTiO3). These results suggest that a bulk-derived descriptor such as nBulk can be used to screen metal-oxide catalysts.

  13. Influence of nickel on structure and hardness of Fe-Co bulk metallic glasses

    Directory of Open Access Journals (Sweden)

    R. Nowosielski

    2010-01-01

    Full Text Available Purpose: In the present paper, influence of Ni addition on structure and hardness Fe-based bulk metallic glass were investigated.Design/methodology/approach: The studies were performed on Fe36+xCo36-x-yNiyB19.2Si4.8Nb4 ( x= 0;1, y=0;10;15 glassy alloy in a form of rods with diameter up to 5 mm. The tests, carried out to obtain amorphous metallic glasses, were realized with the use pressure die casting method. The system includes a copper mould, high frequency power supply, quartz nozzle and a source of inert gas as argon. The following experimental techniques were used for the test of structure: X-ray diffraction (XRD phase analysis and scanning electron microscopy (SEM. Microhardness was examined by Vickers diamond testing machine.Findings: The X-ray diffraction revealed that all samples with thickness 2 mm were amorphous. The structural studies revealed that amorphous structure depended on thickness and nickel contents in a preliminary alloy.Research limitations/implications: The relationship between structure and microhardness can be useful for practical application of these alloys.Practical implications: The Fe-based bulk metallic glasses attracted great interest for a variety of application fields, for example structural materials, electric applications, precision machinery materials. These amorphous alloys exhibit high strength, a high elastic strain limit, high fracture toughness, and other useful mechanical properties which are attractive to many engineering applications.Originality/value: The originality of this paper are studies of changes of structure and hardness of Fe36+xCo36-x-yNiyB19.2Si4.8Nb4 ( x= 0;1, y=0;10;15 mainly depending on Ni addition in this alloy

  14. Fluid–structure interaction analysis of bioprosthetic heart valves: Significance of arterial wall deformation

    OpenAIRE

    Hsu, Ming-Chen; Kamensky, David; Bazilevs, Yuri; Sacks, Michael S; Hughes, Thomas J. R.

    2014-01-01

    We propose a framework that combines variational immersed-boundary and arbitrary Lagrangian–Eulerian (ALE) methods for fluid–structure interaction (FSI) simulation of a bioprosthetic heart valve implanted in an artery that is allowed to deform in the model. We find that the variational immersed-boundary method for FSI remains robust and effective for heart valve analysis when the background fluid mesh undergoes deformations corresponding to the expansion and contraction of the elastic artery....

  15. Influence of deformation on structural-phase state of weld material in St3 steel

    International Nuclear Information System (INIS)

    The structural-phase condition of the weld material subjected to the plastic deformation was investigated using the translucent diffraction electron microscopy method. The investigations were carried out near the joint of the weld and the base metal. The seam was done by the method of manual arc welding without artificial defects. The St3 steel was taken as the welded material. Influence of the plastic deformation on morphology, phase composition, defect structure and its parameters of weld metal was revealed. All investigations were done at the distance of 0.5 mm from the joint of the weld and the base metal at the deformation degrees from 0 to 5% and after destruction of a sample. It was established that deformation of the sample did not lead to qualitative changes in the structure (the structure is still presented by ferrite-pearlite mixture) but changed the quantitative parameters of the structure, namely, with the increase of plastic deformation a part of the pearlite component becomes more and more imperfect. In the beginning it turns into the destroyed pearlite then into ferrite, the volume fraction of pearlite is decreased. The polarization of dislocation structure takes place but it doesn’t lead to the internal stresses that can destroy the sample

  16. Influence of deformation on structural-phase state of weld material in St3 steel

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, Alexander, E-mail: galvas.kem@gmail.ru; Ababkov, Nicolay, E-mail: n.ababkov@rambler.ru; Ozhiganov, Yevgeniy, E-mail: zhigan84@mail.ru [Kuzbass State Technical University, 25-54, Krasnaya Str., 650000, Kemerovo (Russian Federation); LLC “Kuzbass Center of Welding and Control”, 33/2, Lenin Str., 650055, Kemerovo (Russian Federation); Kozlov, Eduard, E-mail: kozlov@tsuab.ru [Kuzbass State Technical University, 25-54, Krasnaya Str., 650000, Kemerovo (Russian Federation); Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Popova, Natalya, E-mail: natalya-popova-44@mail.ru [Kuzbass State Technical University, 25-54, Krasnaya Str., 650000, Kemerovo (Russian Federation); Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Institute of Strength Physics and Materials Science, SB RAS, 2/4, Akademicheskii Ave., 634021, Tomsk (Russian Federation); Nikonenko, Elena, E-mail: vilatomsk@mail.ru [Kuzbass State Technical University, 25-54, Krasnaya Str., 650000, Kemerovo (Russian Federation); Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 30, Lenin Str., 634050, Tomsk (Russian Federation); Zboykova, Nadezhda, E-mail: tezaurusn@gmail.com; Koneva, Nina, E-mail: koneva@tsuab.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation)

    2016-01-15

    The structural-phase condition of the weld material subjected to the plastic deformation was investigated using the translucent diffraction electron microscopy method. The investigations were carried out near the joint of the weld and the base metal. The seam was done by the method of manual arc welding without artificial defects. The St3 steel was taken as the welded material. Influence of the plastic deformation on morphology, phase composition, defect structure and its parameters of weld metal was revealed. All investigations were done at the distance of 0.5 mm from the joint of the weld and the base metal at the deformation degrees from 0 to 5% and after destruction of a sample. It was established that deformation of the sample did not lead to qualitative changes in the structure (the structure is still presented by ferrite-pearlite mixture) but changed the quantitative parameters of the structure, namely, with the increase of plastic deformation a part of the pearlite component becomes more and more imperfect. In the beginning it turns into the destroyed pearlite then into ferrite, the volume fraction of pearlite is decreased. The polarization of dislocation structure takes place but it doesn’t lead to the internal stresses that can destroy the sample.

  17. On RR couplings and bulk singularity structures of non-BPS branes

    Science.gov (United States)

    Hatefi, Ehsan

    2016-09-01

    We compute the five point world sheet scattering amplitude of a symmetric closed string Ramond-Ramond, a transverse scalar field, a world volume gauge field and a real tachyon in both world volume and transverse directions of brane in type IIA and IIB superstring theory. We provide the complete analysis of S-matrix and show that both u‧ = u +1/4 and t channel bulk singularity structures can also be examined by this S-matrix. Various remarks about new restricted Bianchi identities on world volume for the other pictures have also been made.

  18. Main Parameters Characterization of Bulk CMOS Cross-Like Hall Structures

    Directory of Open Access Journals (Sweden)

    Maria-Alexandra Paun

    2016-01-01

    Full Text Available A detailed analysis of the cross-like Hall cells integrated in regular bulk CMOS technological process is performed. To this purpose their main parameters have been evaluated. A three-dimensional physical model was employed in order to evaluate the structures. On this occasion, numerical information on the input resistance, Hall voltage, conduction current, and electrical potential distribution has been obtained. Experimental results for the absolute sensitivity, offset, and offset temperature drift have also been provided. A quadratic behavior of the residual offset with the temperature was obtained and the temperature points leading to the minimum offset for the three Hall cells were identified.

  19. Controlled Bulk Properties of Composite Polymeric Solutions for Extensive Structural Order of Honeycomb Polysulfone Membranes.

    Science.gov (United States)

    Gugliuzza, Annarosa; Perrotta, Maria Luisa; Drioli, Enrico

    2016-01-01

    This work provides additional insights into the identification of operating conditions necessary to overcome a current limitation to the scale-up of the breath figure method, which is regarded as an outstanding manufacturing approach for structurally ordered porous films. The major restriction concerns, indeed, uncontrolled touching droplets at the boundary. Herein, the bulk of polymeric solutions are properly managed to generate honeycomb membranes with a long-range structurally ordered texture. Water uptake and dynamics are explored as chemical environments are changed with the intent to modify the hydrophilic/hydrophobic balance and local water floatation. In this context, a model surfactant such as the polyoxyethylene sorbitan monolaurate is used in combination with alcohols at different chain length extents and a traditional polymer such as the polyethersufone. Changes in the interfacial tension and kinematic viscosity taking place in the bulk of composite solutions are explored and examined in relation to competitive droplet nucleation and growth rate. As a result, extensive structurally ordered honeycomb textures are obtained with the rising content of the surfactant while a broad range of well-sized pores is targeted as a function of the hydrophilic-hydrophobic balance and viscosity of the composite polymeric mixture. The experimental findings confirm the consistency of the approach and are expected to give propulsion to the commercially production of breath figures films shortly. PMID:27196938

  20. Automated hexahedral meshing of anatomic structures using deformable registration.

    Science.gov (United States)

    Grosland, Nicole M; Bafna, Ritesh; Magnotta, Vincent A

    2009-02-01

    This work introduces a novel method of automating the process of patient-specific finite element (FE) model development using a mapped mesh technique. The objective is to map a predefined mesh (template) of high quality directly onto a new bony surface (target) definition, thereby yielding a similar mesh with minimal user interaction. To bring the template mesh into correspondence with the target surface, a deformable registration technique based on the FE method has been adopted. The procedure has been made hierarchical allowing several levels of mesh refinement to be used, thus reducing the time required to achieve a solution. Our initial efforts have focused on the phalanx bones of the human hand. Mesh quality metrics, such as element volume and distortion were evaluated. Furthermore, the distance between the target surface and the final mapped mesh were measured. The results have satisfactorily proven the applicability of the proposed method. PMID:18688764

  1. Correlation between atomic structure evolution and strength in a bulk metallic glass at cryogenic temperature.

    Science.gov (United States)

    Tan, J; Wang, G; Liu, Z Y; Bednarčík, J; Gao, Y L; Zhai, Q J; Mattern, N; Eckert, J

    2014-01-01

    A model Zr41.25Ti13.75Ni10Cu12.5Be22.5 (at.%) bulk metallic glass (BMG) is selected to explore the structural evolution on the atomic scale with decreasing temperature down to cryogenic level using high energy X-ray synchrotron radiation. We discover a close correlation between the atomic structure evolution and the strength of the BMG and find out that the activation energy increment of the concordantly atomic shifting at lower temperature is the main factor influencing the strength. Our results might provide a fundamental understanding of the atomic-scale structure evolution and may bridge the gap between the atomic-scale physics and the macro-scale fracture strength for BMGs. PMID:24469299

  2. Electronic structure of CoPt based systems: from bulk to nanoalloys

    Science.gov (United States)

    Zosiak, L.; Goyhenex, C.; Kozubski, R.; Tréglia, G.

    2015-11-01

    An accurate description of the local electronic structure is necessary for guiding the design of materials with targeted properties in a controlled way. For complex materials like nanoalloys, self-consistent tight-binding calculations should be a good alternative to ab initio methods, for handling the most complex and large systems (hundreds to thousands of atoms), provided that these parameterized method is well founded from ab initio ones that they intend to replace. Ab initio calculations (density functional theory) enabled us to derive rules for charge distribution as a function of structural change and alloying effects in Co and Pt based systems, from bulk to nanoalloys. A general local neutrality rule per site, orbital and species was found. Based on it, self-consistent tight-binding calculations could be implemented and applied to CoPt nanoalloys. A very good agreement is obtained between tight-binding and DFT calculations in terms of local electronic structure.

  3. Flow-Induced Deformation of a Flexible Thin Structure as Manifestation of Heat Transfer Enhancement

    CERN Document Server

    Soti, Atul Kumar; Sheridan, John

    2015-01-01

    Flow-induced deformation of thin structures coupled with convective heat transfer has potential applications in energy harvesting and is important for understanding functioning of several biological systems. We numerically demonstrate large-scale flow-induced deformation as an effective passive heat transfer enhancement technique. An in-house, strongly-coupled fluid-structure interaction (FSI) solver is employed in which flow and structure solvers are based on sharp-interface immersed boundary and finite element method, respectively. In the present work, we validate convective heat transfer module of the in-house FSI solver against several benchmark examples of conduction and convective heat transfer including moving structure boundaries. The thermal augmentation is investigated as well as quantified for the flow-induced deformation of an elastic thin plate attached to lee side of a rigid cylinder in a heated channel laminar flow. We show that the wake vortices past the plate sweep higher sources of vorticity...

  4. Deformable meshes for medical image segmentation accurate automatic segmentation of anatomical structures

    CERN Document Server

    Kainmueller, Dagmar

    2014-01-01

    ? Segmentation of anatomical structures in medical image data is an essential task in clinical practice. Dagmar Kainmueller introduces methods for accurate fully automatic segmentation of anatomical structures in 3D medical image data. The author's core methodological contribution is a novel deformation model that overcomes limitations of state-of-the-art Deformable Surface approaches, hence allowing for accurate segmentation of tip- and ridge-shaped features of anatomical structures. As for practical contributions, she proposes application-specific segmentation pipelines for a range of anatom

  5. Mechanical strain energy shuttle for aircraft morphing via wing twist or structural deformation

    Science.gov (United States)

    Clingman, Dan J.; Ruggeri, Robert T.

    2004-07-01

    Direct structural deformation to achieve aerodynamic benefit is difficult because large actuators must supply energy for structural strain and aerodynamic loads. This ppaer presents a mechanism that allows most of the energy required to twist or deform a wing to be stored in descrete springs. When this device is used, only sufficient energy is provided to control the position of the wing. This concept allows lightweight actuators to perform wing twisting and other structural distortions, and it reduces the onboard mass of the wing-twist system. The energy shuttle can be used with any actuator and it has been adapted for used with shape memory alloy, piezoelectric, and electromagnetic actuators.

  6. Population structure of Staphylococcus aureus isolated from bulk tank goat's milk.

    Science.gov (United States)

    Spanu, Vincenzo; Scarano, Christian; Virdis, Salvatore; Melito, Sara; Spanu, Carlo; De Santis, Enrico Pietro Luigi

    2013-04-01

    The presence of Staphylococcus aureus in raw milk can represent a potential threat to human health, due to the introduction of pathogenic strains into dairy food supply chain. The present study was performed to investigate the genetic variation among S. aureus strains isolated from bulk tank goat's milk. The virulence profiles were also assessed to link the isolates with the potential source of milk contamination. A population study was performed on 60 strains using distance-based methods such as pulsed-field gel electrophoresis (PFGE), and the output was analyzed using Structure statistical software (University of Chicago; http://pritch.bsd.uchicago.edu/structure.html ). This Bayesian clustering model tool allows one to assign individuals into a population with no predefined structure. In order to assess partition of genetic variability among isolates, groups obtained by Structure were also investigated using analysis of molecular variance. S. aureus was recovered in 60 out of 78 samples (76.9%) collected from 26 farms. According to PFGE analysis, the strains were divided into 25 different pulsotypes and grouped into two main clusters. Restriction profiles, analyzed by Structure, allowed us to identify two distinct S. aureus genetic groups. Within each group, the strains showed a high coefficient of membership. A great part of genetic variability was attributable to within-groups variation. On the basis of the virulence profile, 45% of the isolates were linked to "animal" biovar, while 6.7% could be assigned to "human" biovar. Out of 60 strains, 27 were characterized by in vitro production of either enterotoxins A (5.0%), C (38.3%), or D (1.7%). The present study showed a high prevalence of bulk tank goat's milk contamination with S. aureus of animal origin. The presence in goat's milk of S. aureus strains able to produce enterotoxins and their potential introduction into dairy chain may represent a serious threat to human health. PMID:23458027

  7. Influence of Plastic Deformation Process on the Structure and Properties of Alloy WE43

    Directory of Open Access Journals (Sweden)

    Bednarczyk I.

    2016-03-01

    Full Text Available The paper describes the results of structure and properties tests of flat bars made of alloy WE43 obtained in the process of extrusion with the use of KOBO method. An analysis of structure changes was conducted both in initial state and after plastic deformation.

  8. Structural, compositional and magnetic characterization of bulk V2O5 doped ZnO system

    International Nuclear Information System (INIS)

    This paper investigates the structural, compositional and magnetic properties of vanadium doped ZnO bulk samples prepared by solid state reaction technique. The Rietveld refinement analysis for XRD results of samples showed small change in lattice parameters for 3 and 5% vanadium doped ZnO samples indicating the substitution of Zn2+ ions by vanadium ions in ZnO lattice. Raman spectroscopy reveals the change in ZnO modes positions due to vanadium doping. The appearance of E1 and E2 modes showed that the wurtzite structure of ZnO is still maintained after doping of vanadium oxide. XPS analysis confirms the presence of the different elements and oxidation states of vanadium ions. M-H curves obtained from VSM showed weak ferromagnetism in the samples. The observation of ferromagnetic behavior indicates the formation of ZnVO phase with V2+ ion substitution in the ZnO lattice. XPS scans of the etched bulk samples confirmed the 2+ oxidation state of vanadium ions in our samples explaining the origin of ferromagnetism.

  9. Core level shifts in Cu-Pd alloys as a function of bulk composition and structure

    Science.gov (United States)

    Boes, Jacob R.; Kondratyuk, Peter; Yin, Chunrong; Miller, James B.; Gellman, Andrew J.; Kitchin, John R.

    2015-10-01

    CuPd alloys are important materials in hydrogen purification, where they are used as dense Pd-based separation membranes. Cu is added to impart sulfur tolerance and improved mechanical properties. At intermediate compositions and T < 873 K, a BCC alloy (B2) phase occurs, which has superior separation characteristics to those of the FCC phases that form at high Cu and high Pd compositions. Identifying the composition and temperature window where the B2 phase forms is a critical need to enable the design of improved alloys. A composition spread alloy film of Cu and Pd was synthesized. The film was characterized by electron back scatter diffraction and X-ray photoelectron spectroscopy, providing the core level shifts as a function of bulk composition and bulk structure. An anomalous deviation in the Cu core level shift was observed in the composition range 0.33 < xPd < 0.55 over which the B2 phase occurs. Density functional theory calculations were used to simulate core level shifts in the FCC and B2 alloy structures. They suggest that the anomalous deviation in core level shift is due to formation of the ordered B2 phase in this composition range.

  10. Morpho-structural criteria for the identification of volcano deformation processes from analogue modeling

    Science.gov (United States)

    Rincon, Marta; Marquez, Alvaro; van Wyk de Vries, Benjamin; Herrera, Raquel; Granja Bruña, Jose Luis; Llanes, Pilar

    2014-05-01

    The morphology of volcanoes provides important information about edifice evolution. Volcanoes can deform by gravitational instability and intrusions. This deformation can compromise volcano structural stability, promoting flank collapse even at dormant edifices. Identification of past/active deformation processes is therefore important not only for the understanding of volcano evolution but also for volcanic hazards. Both deformation due to the flank spreading of a volcano over its weak core and due to the intrusion of a cryptodome in the volcano edifice can produce faulting and changes in the morphology of volcano flanks. These morpho-structural changes in the volcano open the possibility to identify potential deformed and unstable volcanoes using remote sensing techniques and DEMs. We have used analogue models of flank spreading and intrusion processes to make progress in the morpho-structural identification of deformation features which can provide criteria for distinguishing processes. We have geometrically and mechanically scaled two different sets of experiments using a sand-plaster mixture for volcano materials, silicone putty for weak core rocks and Golden Syrup for magma intrusions. For monitoring changes in the volcano morphology we have used a Kinect sensor (Microsoft), which provides us vertical displacements of volcano flanks several times per second with a 1 mm precision. We have synchronized the Kinect sensor with a digital camera for monitoring the spatio-temporal evolution of tectonic structures together with morphology. All experiments produce asymmetrical changes in volcano morphology, developing convex-concave geometries in the deformed flank. However, the spatial relationships of structures with changes in volcano flank curvature are different for the two processes, as noted by previous authors. The morphometric tools developed for analyzing volcano topography allow us to identify intrusion processes due to volcano volume increase. We have

  11. Neutron-halo structure of light nuclei studied with effects of deformations and orientations included

    International Nuclear Information System (INIS)

    Based on the cluster-core model, the effects of nuclear deformations and orientations on the halo structure of the observed and proposed cases of neutron-halo nuclei is analyzed. The calculations are performed for the deformed structures using quadrupole (β2) deformations with ‘optimum’ orientations as well as including higher multipole deformations (β2-β4) with the ‘compact’ (hot) orientations. The interesting result is that, although potential energy surfaces are modified with the inclusion of deformation effects up to β2, but the 1n- and 2n-halo nature remains intact for almost all cases investigated here, except for 17B and 22C nuclei. However, in some cases (22O, 26F, 27F), the choice of higher multipole deformations up to hexadecapole is shown to be rather sensitive. In addition, the relevance of the use of different nuclear proximity potentials is also explored in the context of the halo nature of neutron-rich light nuclei. The possible role of Q-value and angular momentum effects are also addressed. (paper)

  12. Deciphering the shape and deformation of secondary structures through local conformation analysis

    Directory of Open Access Journals (Sweden)

    Camproux Anne-Claude

    2011-02-01

    Full Text Available Abstract Background Protein deformation has been extensively analysed through global methods based on RMSD, torsion angles and Principal Components Analysis calculations. Here we use a local approach, able to distinguish among the different backbone conformations within loops, α-helices and β-strands, to address the question of secondary structures' shape variation within proteins and deformation at interface upon complexation. Results Using a structural alphabet, we translated the 3 D structures of large sets of protein-protein complexes into sequences of structural letters. The shape of the secondary structures can be assessed by the structural letters that modeled them in the structural sequences. The distribution analysis of the structural letters in the three protein compartments (surface, core and interface reveals that secondary structures tend to adopt preferential conformations that differ among the compartments. The local description of secondary structures highlights that curved conformations are preferred on the surface while straight ones are preferred in the core. Interfaces display a mixture of local conformations either preferred in core or surface. The analysis of the structural letters transition occurring between protein-bound and unbound conformations shows that the deformation of secondary structure is tightly linked to the compartment preference of the local conformations. Conclusion The conformation of secondary structures can be further analysed and detailed thanks to a structural alphabet which allows a better description of protein surface, core and interface in terms of secondary structures' shape and deformation. Induced-fit modification tendencies described here should be valuable information to identify and characterize regions under strong structural constraints for functional reasons.

  13. Structure and plasticity of the AZ31 magnesium alloy after hot deformation

    Directory of Open Access Journals (Sweden)

    D. Kuc

    2008-03-01

    Full Text Available Purpose: The favourable properties of magnesium account for the fact that it is applied not only in cast structural components but also in those subjected to plastic working. Currently, intensive works are conducted to optimize the processes of plastic working of these alloys The following work concentrates on the analysis of microstructure and plasticity of magnesium alloy AZ31 type during hot plastic deformation process.Design/methodology/approach: After rolling and annealing, alloy specimens were subjected to axial-symmetric compression in the Gleeble 3800 simulator at temperatures ranging from 200 to 450°C at 0.01 and 1.0 s-1 strain rates. In order to analyse the processes which take place during deformation, the specimens after deformation were intensely cooled with water. Structural examination was carried out using light microscopy.Findings: The processes of structural reconstruction such as dynamic recrystallization, which take place during hot - deformation, have been detected.Practical implications: The research carried out enabled the understanding of the phenomena taking place during deformation and annealing of the investigated AZ31 type alloy. The results will constitute the basis for modelling the structural changes.Originality/value: The results obtained are vital for designing an effective thermo - mechanical processing technology for the investigated Fe3Al-5Cr alloy.

  14. The impact of deformation on structural changes of the duplex steel

    Directory of Open Access Journals (Sweden)

    D. Kuc

    2007-07-01

    Full Text Available Purpose: Despite the many years’ research on the plasticity of duplex steels, it was impossible to conclusively determine the mechanisms for structure recovery during the plastic deformation. The paper will attempt to provide explanations for the changes taking place in the steel structure during the superplastic flow.Design/methodology/approach: After a solution heat treatment at 1250°C, the steel was subjected to cold deformation through rolling with the total 70% reduction. The specimens were tensioned in the “Instron” strength-testing machine at temperature 850°C at a rate of vr=15×10-3 mm/s in a 0.005Pa vacuum. Structural examination was carried out using light and electron microscopy. The micro-diffraction technique was applied to provide diffraction images with Kikuchi lines.Findings: A joint operation of structure reconstruction mechanisms during the deformation of the analyzed steel with the process of σ phase precipitation inhibiting further growth of the newly-formed grain has been determined.Practical implications: The capacity for increased deformability through combined thermo - mechanical processes, requiring a precise selection of the deformation parameters, has been indicatedOriginality/value: The results obtained are vital for designing an effective thermo - mechanical processing technology for the investigated steel.

  15. The influence of deformation on the plasticity and structure of Fe3Al - 5Cr alloy

    Directory of Open Access Journals (Sweden)

    D. Kuc

    2007-06-01

    Full Text Available Purpose: The major problem restricting universal employment of intermetallic phase base alloy is their low plasticity which leads to hampering their development as construction materials. The following work concentrates on the analysis of microstructure and plasticity of ordered Fe3Al D03 - structured alloy containing 28% at. of Al and 5%Cr at. during hot plastic deformation process.Design/methodology/approach: After casting and annealing, alloy specimens were subjected to axial-symmetric compression in the Gleeble 3800 simulator at temperatures ranging from 600 to 1200°C at 0.1, 0.01, 1.0, 10 s-1 strain rates. In order to analyse the processes which take place during deformation, the specimens after deformation were intensely cooled with water. Structural examination was carried out using light microscopy.Findings: The processes of structural reconstruction such as dynamic recrystallization, which take place during hot - deformation, have been detected.Practical implications: The research carried out enabled the understanding of the phenomena taking place during deformation and annealing of the investigated alloy. The results will constitute the basis for modelling the structural changes.Originality/value: The results obtained are vital for designing an effective thermo - mechanical processing technology for the investigated Fe3Al-5Cr alloy.

  16. Proximity induced superconductivity in bulk Cu-Nb composites: The influence of interface's structural quality

    International Nuclear Information System (INIS)

    The influence of the structural quality of a normal metal-superconductor interface on the strength of the proximity effect is studied for the cylindrical geometry of bulk Cu-Nb multifilamentary composite samples. In as-drawn Cu-Nb samples the superconducting properties induced to the Cu matrix due to its proximity with Nb filaments are manifested in the magnetization measurements through a pronounced peak positioned in the low-field regime. By systematic annealing in an extended temperature regime for various durations we changed the structural quality of the Cu-Nb interfaces and as a result their transparency to the superconducting carrier. The direct comparison of scanning electron microscopy images with magnetization data revealed that the distortion of the Cu-Nb interfaces is responsible for the suppression of the proximity effect

  17. Disentangling bulk from surface contributions in the electronic structure of black phosphorus

    Science.gov (United States)

    Golias, E.; Krivenkov, M.; Sánchez-Barriga, J.

    2016-02-01

    Most recently, black phosphorus has come into focus as a promising material for future applications in nanoelectronic devices due to its unique electronic and transport properties. Here, we use angle-resolved photoemission spectroscopy in conjunction with ab initio calculations within the framework of density-functional theory to disentangle surface from the bulk contributions in the electronic structure of black phosphorus. We find good agreement between our theoretical predictions for the intra- and interlayer energy-momentum dispersions and the experimentally obtained three-dimensional band structure of this material. Our results provide compelling evidence for the existence of surface-resonant states near the top of the valence band, which can play an important role in the performance of electronic devices based on black phosphorus.

  18. Bulk electronic structure of FeRh undergoing metamagnetic transition via hard x-ray photoemission

    Science.gov (United States)

    Gray, Alexander; Cooke, David; Kruger, Peter; Bordel, Catherine; Fullerton, Eric; Ueda, Shigenori; Kobayashi, Keisuke; Hellman, Frances; Fadley, Charles

    2012-02-01

    In this study changes in the electronic structure accompanying a temperature-induced metamagnetic transition from anti-ferromagnetic to ferromagnetic order are investigated in strained epitaxial FeRh thin films via valence-band and core-level hard x-ray photoelectron spectroscopy with a photon energy of 6 keV. At such high photon energy, the resulting inelastic mean-free paths of the photoemitted electrons and therefore the average probing depths are on the order of 60 å, corresponding to about 20 unit cells and ensuring truly bulk-sensitive measurement. Clear differences between the AFM and FM states are observed across the entire valence-band spectrum and these are well reproduced using density functional theory. Changes in the Fe 2p core-levels of Fe are also observed and interpreted using Anderson impurity model calculations. These results suggest that significant electronic structure changes are involved in this AFM-FM transition.

  19. Crystal structure and electronic properties of bulk and thin film brownmillerite oxides

    Science.gov (United States)

    Young, Joshua; Rondinelli, James M.

    2015-11-01

    The equilibrium structure and functional properties exhibited by brownmillerite oxides, a family of perovskite-derived structures with alternating layers of B O6 octahedra and B O4 tetrahedra, viz., ordered arrangements of oxygen vacancies, is dependent on a variety of competing crystal-chemistry factors. We use electronic structure calculations to disentangle the complex interactions in two ferrates, Sr2Fe2O5 and Ca2Fe2O5 , relating the stability of the equilibrium (strain-free) and thin film structures to both previously identified and herein newly proposed descriptors. We show that cation size and intralayer separation of the tetrahedral chains provide key contributions to the preferred ground state. We show the bulk ground-state structure is retained in the ferrates over a range of strain values; however, a change in the orientation of the tetrahedral chains, i.e., a perpendicular orientation of the vacancies relative to the substrate, is stabilized in the compressive region. The structure stability under strain is largely governed by maximizing the intraplane separation of the dipoles generated from rotations of the FeO4 tetrahedra. Lastly, we find that the electronic band gap is strongly influenced by strain, manifesting as an unanticipated asymmetric-vacancy alignment dependent response. This atomistic understanding establishes a practical route for the design of functional electronic materials in thin film geometries.

  20. Correlation between locally deformed structure and oxide film properties in austenitic stainless steel irradiated with neutrons

    Science.gov (United States)

    Chimi, Yasuhiro; Kitsunai, Yuji; Kasahara, Shigeki; Chatani, Kazuhiro; Koshiishi, Masato; Nishiyama, Yutaka

    2016-07-01

    To elucidate the mechanism of irradiation-assisted stress corrosion cracking (IASCC) in high-temperature water for neutron-irradiated austenitic stainless steels (SSs), the locally deformed structures, the oxide films formed on the deformed areas, and their correlation were investigated. Tensile specimens made of irradiated 316L SSs were strained 0.1%-2% at room temperature or at 563 K, and the surface structures and crystal misorientation among grains were evaluated. The strained specimens were immersed in high-temperature water, and the microstructures of the oxide films on the locally deformed areas were observed. The appearance of visible step structures on the specimens' surface depended on the neutron dose and the applied strain. The surface oxides were observed to be prone to increase in thickness around grain boundaries (GBs) with increasing neutron dose and increasing local strain at the GBs. No penetrative oxidation was observed along GBs or along surface steps.

  1. 3D segmentation of rodent brain structures using hierarchical shape priors and deformable models.

    Science.gov (United States)

    Zhang, Shaoting; Huang, Junzhou; Uzunbas, Mustafa; Shen, Tian; Delis, Foteini; Huang, Xiaolei; Volkow, Nora; Thanos, Panayotis; Metaxas, Dimitris N

    2011-01-01

    In this paper, we propose a method to segment multiple rodent brain structures simultaneously. This method combines deformable models and hierarchical shape priors within one framework. The deformation module employs both gradient and appearance information to generate image forces to deform the shape. The shape prior module uses Principal Component Analysis to hierarchically model the multiple structures at both global and local levels. At the global level, the statistics of relative positions among different structures are modeled. At the local level, the shape statistics within each structure is learned from training samples. Our segmentation method adaptively employs both priors to constrain the intermediate deformation result. This prior constraint improves the robustness of the model and benefits the segmentation accuracy. Another merit of our prior module is that the size of the training data can be small, because the shape prior module models each structure individually and combines them using global statistics. This scheme can preserve shape details better than directly applying PCA on all structures. We use this method to segment rodent brain structures, such as the cerebellum, the left and right striatum, and the left and right hippocampus. The experiments show that our method works effectively and this hierarchical prior improves the segmentation performance. PMID:22003750

  2. Effects of structural deformation on formation of coalbed methane reservoirs in Huaibei coalfield, China

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Bo; Qu, Zhenghui; Li, Ming [School of Resources and Earth Science, China University of Mining and Technology, Xuzhou 221116 (China); Key Laboratory of CBM Resource and Reservoir-generating Process, China Ministry of Education, Xuzhou 221116 (China); Wang, Geoff G.X. [School of Chemical Engineering, The University of Queensland, QLD 4072 (Australia)

    2010-06-01

    Tectonically deformed coal is defined as coal formed by superimposed reformations from tectonic stress. The Huaibei coalfield is typically composed of various tectonically deformed coals containing rich coalbed methane resources. However, the occurrence of coal seam in this area is complicated largely by the structural deformation, which has not yet been evaluated systematically for exploration and exploitation of coalbed methane. In this study, tectonism in Huaibei coalfield is discussed by combining systematic analyses on the occurrence of coal seams and the formation of coalbed methane reservoirs. The study shows that, with structural deformation in the study area, the coal seams in Huaibei coalfield are distributed in north-south tectonic blocks and east-west tectonic zones. North tectonic block of Huaibei coalfield is not favourable for exploitation of coalbed methane because of low gas content or disadvantageous structural conditions. Within the south tectonic block, the east Suzhou syncline contains high gas content but coal permeability is very low. This area is generally not suitable for exploitation of coalbed methane and is a dangerous mining area due to gas outburst because of the widely developed mylonitic coals. South Suzhou and Nanping synclines in the middle part of the south tectonic block are exposed to relatively weak structural deformations. These synclines contain coals with high gas content and moderate permeability, which are beneficial for exploration and exploitation of coalbed methane. Linhuan mining area in the south tectonic block is generally not suitable for exploitation of coalbed methane, mainly because of well developed normal faults and interlayer slip structure, and presence of mylonitic coal, resulting in low gas content and poor structural conditions for mining coalbed methane. In contrast, Guoyang mining area in the west part of the south tectonic block, where tectonically deformed coal was generally underdeveloped, is a

  3. Large-Deformation Displacement Transfer Functions for Shape Predictions of Highly Flexible Slender Aerospace Structures

    Science.gov (United States)

    Ko, William L.; Fleischer, Van Tran

    2013-01-01

    Large deformation displacement transfer functions were formulated for deformed shape predictions of highly flexible slender structures like aircraft wings. In the formulation, the embedded beam (depth wise cross section of structure along the surface strain sensing line) was first evenly discretized into multiple small domains, with surface strain sensing stations located at the domain junctures. Thus, the surface strain (bending strains) variation within each domain could be expressed with linear of nonlinear function. Such piecewise approach enabled piecewise integrations of the embedded beam curvature equations [classical (Eulerian), physical (Lagrangian), and shifted curvature equations] to yield closed form slope and deflection equations in recursive forms.

  4. Workpiece structure deformation caused by high speed cutting

    OpenAIRE

    Kopač, Janez

    2015-01-01

    The hard turning and grinding of High Speed Steel (HSS) materials with hardness of 61 HRC significantly changes structural properties. Estimators of the cutting conditions are surface roughness, dimensions, tolerances and required structure of the surface layer. Vacuum heat treatment of HSS for cold working applications was used as yielded material with greater toughness, while the hardness was maintained constant or even increased. HSS-BRM2 material that was vacuum quenched and tempered was ...

  5. Structure and properties of cerium oxides in bulk and nanoparticulate forms

    Energy Technology Data Exchange (ETDEWEB)

    Gangopadhyay, Shruba [NanoScience Technology Center, University of Central Florida, 12424 Research Parkway, Suite 400, Orlando, FL 32826 (United States); Department of Chemistry, University of Central Florida, 4111 Libra Drive, PS 255, Orlando, FL 32826 (United States); Frolov, Dmitry D. [NanoScience Technology Center, University of Central Florida, 12424 Research Parkway, Suite 400, Orlando, FL 32826 (United States); Department of Chemistry, Moscow M.V. Lomonosov State University, Leninskiye Gory, Moscow 119991 (Russian Federation); Masunov, Artëm E., E-mail: amasunov@ucf.edu [NanoScience Technology Center, University of Central Florida, 12424 Research Parkway, Suite 400, Orlando, FL 32826 (United States); Department of Chemistry, University of Central Florida, 4111 Libra Drive, PS 255, Orlando, FL 32826 (United States); Department of Physics, University of Central Florida, 4111 Libra Drive, PS 430, Orlando, FL 32826 (United States); Seal, Sudipta [Advanced Materials Processing and Analysis Center, University of Central Florida, 12760 Pegasus Drive, ENG1 381, Orlando, FL 32816 (United States); Department of Materials Science and Engineering, University of Central Florida, 12760 Pegasus Drive, ENG1 207, FL 32816 (United States); College of Medicine, University of Central Florida, 6850 Lake Nona Blvd, Orlando, FL 32827 (United States); NanoScience Technology Center, University of Central Florida, 12424 Research Parkway, Suite 400, Orlando, FL 32826 (United States)

    2014-01-25

    The experimental and computational studies on the cerium oxide nanoparticles, as well as stoichiometric phases of bulk ceria are reviewed. Based on structural similarities of these phases in hexagonal aspect, electroneutral and non-polar pentalayers are identified as building blocks of type A sesquioxide structure. The idealized core/shell structure of the ceria nanoparticles is described as dioxide core covered by a single pentalayer of sesquioxide, which explains the exceptional stability of subsurface vacancies in nanoceria. The density functional theory (DFT) predictions of the lattice parameters and elastic moduli for the Ce(IV) and Ce(III) oxides at the hybrid DFT level are also presented. The calculated values for both compounds agree with available experimental data and allow predicting changes in the lattice parameter with decreasing size of the nanoparticles. The lattice parameter is calculated as equilibrium between contraction of sesquioxide structure in the core, and expansion of dioxide structure in the shell of the nanoparticle. This is consistent with available XRD data on ceria NPs obtained in mild aqueous conditions. The core/shell model, however, breaks down when applied to the size dependence of lattice parameter in NPs obtained by the laser ablation techniques.

  6. Structure and properties of cerium oxides in bulk and nanoparticulate forms

    International Nuclear Information System (INIS)

    The experimental and computational studies on the cerium oxide nanoparticles, as well as stoichiometric phases of bulk ceria are reviewed. Based on structural similarities of these phases in hexagonal aspect, electroneutral and non-polar pentalayers are identified as building blocks of type A sesquioxide structure. The idealized core/shell structure of the ceria nanoparticles is described as dioxide core covered by a single pentalayer of sesquioxide, which explains the exceptional stability of subsurface vacancies in nanoceria. The density functional theory (DFT) predictions of the lattice parameters and elastic moduli for the Ce(IV) and Ce(III) oxides at the hybrid DFT level are also presented. The calculated values for both compounds agree with available experimental data and allow predicting changes in the lattice parameter with decreasing size of the nanoparticles. The lattice parameter is calculated as equilibrium between contraction of sesquioxide structure in the core, and expansion of dioxide structure in the shell of the nanoparticle. This is consistent with available XRD data on ceria NPs obtained in mild aqueous conditions. The core/shell model, however, breaks down when applied to the size dependence of lattice parameter in NPs obtained by the laser ablation techniques

  7. The interplay between dynamic heterogeneities and structure of bulk liquid water: A molecular dynamics simulation study

    International Nuclear Information System (INIS)

    In order to study the interplay between dynamical heterogeneities and structural properties of bulk liquid water in the temperature range 130–350 K, thus including the supercooled regime, we use the explicit trend of the distribution functions of some molecular properties, namely, the rotational relaxation constants, the atomic mean-square displacements, the relaxation of the cross correlation functions between the linear and squared displacements of H and O atoms of each molecule, the tetrahedral order parameter q and, finally, the number of nearest neighbors (NNs) and of hydrogen bonds (HBs) per molecule. Two different potentials are considered: TIP4P-Ew and a model developed in this laboratory for the study of nanoconfined water. The results are similar for the dynamical properties, but are markedly different for the structural characteristics. In particular, for temperatures higher than that of the dynamic crossover between “fragile” (at higher temperatures) and “strong” (at lower temperatures) liquid behaviors detected around 207 K, the rotational relaxation of supercooled water appears to be remarkably homogeneous. However, the structural parameters (number of NNs and of HBs, as well as q) do not show homogeneous distributions, and these distributions are different for the two water models. Another dynamic crossover between “fragile” (at lower temperatures) and “strong” (at higher temperatures) liquid behaviors, corresponding to the one found experimentally at T∗ ∼ 315 ± 5 K, was spotted at T∗ ∼ 283 K and T∗ ∼ 276 K for the TIP4P-Ew and the model developed in this laboratory, respectively. It was detected from the trend of Arrhenius plots of dynamic quantities and from the onset of a further heterogeneity in the rotational relaxation. To our best knowledge, it is the first time that this dynamical crossover is detected in computer simulations of bulk water. On the basis of the simulation results, the possible mechanisms of the

  8. Unified picture of spin-dependent transport in GMR multilayered structures and bulk ferromagnetic alloys

    Science.gov (United States)

    Schroeder, P. A.; Holody, P.; Loloee, R.; Vouille, C.; Barthelemy, A.; Fert, A.; Hsu, S. Y.

    1998-01-01

    We have observed a positive (inverse) CPP-MR in magnetic multilayers of the forms: (a) ( XY/Cu/Co/Cu) n with XY being the alloys FeCr, FeV, NiCr, CoCr, and (b) (Z/Cr/NiFe/Cr) n with Z = Fe and Co. For (a) the inverted results arise primarily from spin-dependent scattering in the bulk of the alloy, and are linked consistently to: (1) their magnetization; (2) band-structure calculations and (3) resistivity of bulk alloys. For (b) samples, the inverse MRs arise primarily from the scattering at the Fe/Cr and Co/Cr interfaces. Inverse MR for X/Y interfaces and XY alloys (eg. Fe/Cr and FeCr) arises from the similarity of the matching problem of X and Y d levels at interfaces and in alloys. For all XY the CIP-MR was negative, confirming that CIP-MR is strongly influenced by channeling effect and current inhomogenieties.

  9. Mesoscopic multiphase structures and the interfaces of block and graft copolymers in bulk

    International Nuclear Information System (INIS)

    Microphase-separated structures of copolymers with various architectures and their polymer/polymer interfaces were studied. They are SP diblock, PSP triblock, and SPP graft copolymers, where S and P denote polystyrene and poly(2-vinylpyridine), respectively. Morphological observations were carried out by means of transmission electron microscopy and small-angle X-ray scattering. Chain dimensions of component polymers were measured by small-angle neutron scattering and microphase-separated interfaces were observed by neutron reflectivity measurements using deuterium-labeled samples. It was clarified that morphological phase transitions among thermodynamically equilibrium structures for SP diblock and PSP triblock copolymers occur at almost the same compositions; however, those of SPP graft copolymers tend to occur at higher volume fraction of polystyrene, φs, than those for block copolymers. As for alternating lamellar structures it turned out to be clear that lamellar domain spacings, D's, were scaled as the 2/3 power of the molecular weight of polymers irrespective of their architectures. S block chains of SP diblock and PSP triblock copolymers in lamellar structures were both confirmed to be deformed toward the direction perpendicular to the lamellar interfaces, but it revealed that their volumes were preserved. Further, S/P interfacial thicknesses of SP and PSP were essentially the same to each other and the values defined as the FWHM of the error functions which express the segment density distributions of the interfaces were determined to be about 4 nm. (author)

  10. Real-time deformations of organ based on structural mechanics for surgical simulators

    Science.gov (United States)

    Nakaguchi, Toshiya; Tagaya, Masashi; Tamura, Nobuhiko; Tsumura, Norimichi; Miyake, Yoichi

    2006-03-01

    This research proposes the deformation model of organs for the development of the medical training system using Virtual Reality (VR) technology. First, the proposed model calculates the strains of coordinate axis. Secondly, the deformation is obtained by mapping the coordinate of the object to the strained coordinate. We assume the beams in the coordinate space to calculate the strain of the coordinate axis. The forces acting on the object are converted to the forces applied to the beams. The bend and the twist of the beams are calculated based on the theory of structural mechanics. The bend is derived by the finite element method. We propose two deformation methods which differ in the position of the beams in the coordinate space. One method locates the beams along the three orthogonal axes (x, y, z). Another method locates the beam in the area where the deformation is large. In addition, the strain of the coordinate axis is attenuated in proportion to the distance from the point of action to consider the attenuation of the stress which is a viscoelastic feature of the organs. The proposed model needs less computational cost compared to the conventional deformation method since our model does not need to divide the object into the elasticity element. The proposed model was implemented in the laparoscopic surgery training system, and a real-time deformation can be realized.

  11. Altering strength and plastic deformation behavior via alloying and laminated structure in nanocrystalline metals

    Energy Technology Data Exchange (ETDEWEB)

    Gu, C. [State Key Laboratory for Mechanical Behavior of Material, Xi' an Jiaotong University, Xi' an 710049 (China); Wang, F., E-mail: wangfei@mail.xjtu.edu.cn [State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an Jiaotong University, Xi' an 710049 (China); Huang, P., E-mail: huangping@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Material, Xi' an Jiaotong University, Xi' an 710049 (China); Lu, T.J. [State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an Jiaotong University, Xi' an 710049 (China); MOE Key Laboratory for Multifunctional Materials and Structures, Xi' an Jiaotong University, Xi' an 710049 (China); Xu, K.W. [State Key Laboratory for Mechanical Behavior of Material, Xi' an Jiaotong University, Xi' an 710049 (China)

    2015-07-29

    Nanoindentation and electron microscope techniques have been performed on sputtering deposited monolayered nanocrystalline CuNb and multilayered CuNb/Cu thin films. Microstructural features, hardness and surface morphologies of residual indentation have been evaluated to identify the effects of alloying and laminated structure on strength and plastic deformation behavior of nanocrystalline metals. By altering the content of Nb in CuNb alloy and adding crystalline Cu layers into CuNb alloy, the volume fraction of amorphous phase in CuNb alloy and interface structures changed dramatically, resulting in various trends that are related to hardness, indentation induced pileup and shear banding deformation. Based on the experimental results, the dominant deformation mechanisms of the CuNb and CuNb/Cu thin films with various Nb contents were proposed and extended to be discussed.

  12. A nonlinear elastic deformable template for soft structure segmentation: application to the heart segmentation in MRI

    Science.gov (United States)

    Rouchdy, Youssef; Pousin, Jérôme; Schaerer, Joël; Clarysse, Patrick

    2007-06-01

    This paper proposes a nonlinear 3D deformable model for the image segmentation of soft structures. The template is modelled as an elastic body which is deformed by forces derived from the image. It relies on a template, which is a topological, geometrical and material model of the structure to segment. This model is based on the nonlinear three-dimensional elasticity problem with a boundary condition of pure traction. In addition, the applied forces are successive, as they depend on the displacements. For computations, an incremental algorithm is proposed to minimize the global energy of template deformation. Sufficient conditions of the convergence for the incremental algorithm are given. Finally, a discrete algorithm using the finite element method is presented and evaluated on synthetic images and actual MR images of mouse hearts.

  13. Altering strength and plastic deformation behavior via alloying and laminated structure in nanocrystalline metals

    International Nuclear Information System (INIS)

    Nanoindentation and electron microscope techniques have been performed on sputtering deposited monolayered nanocrystalline CuNb and multilayered CuNb/Cu thin films. Microstructural features, hardness and surface morphologies of residual indentation have been evaluated to identify the effects of alloying and laminated structure on strength and plastic deformation behavior of nanocrystalline metals. By altering the content of Nb in CuNb alloy and adding crystalline Cu layers into CuNb alloy, the volume fraction of amorphous phase in CuNb alloy and interface structures changed dramatically, resulting in various trends that are related to hardness, indentation induced pileup and shear banding deformation. Based on the experimental results, the dominant deformation mechanisms of the CuNb and CuNb/Cu thin films with various Nb contents were proposed and extended to be discussed

  14. Damage evaluation of reinforced concrete underground structures after earthquake. Part 1. Relation between local deformation and performance as structural member

    International Nuclear Information System (INIS)

    The objective of this present series of researches is a development of damage level evaluation method for underground structures which have been subjected to large ground motion. The local deformations represented by crack width are observed in inspections after earthquakes. In the present report, a relationship between these local deformations and mechanical performance as a structural member was discussed through the image measurements for damaged reinforced concrete specimens. Based on the test results, the following two items were investigated. a) The procedure for evaluating the maximum displacement response during earthquakes was developed by using the width of residual flexural cracks, and was verified. The method, which focuses on remaining vertical displacement, is applicable to the structures subjected to reversed loading after maximum response. b) The criteria for shear failure were proposed as two deformation indices, i.e., increase of thickness and length of zone with increasing thickness. (author)

  15. Thermoluminescence Dynamics During Destructions of Porous Structures Formed by Nitrogen Nanoclusters in Bulk Superfluid Helium

    Science.gov (United States)

    Meraki, Adil; Mao, Shun; McColgan, Patrick T.; Boltnev, Roman E.; Lee, David M.; Khmelenko, Vladimir V.

    2016-03-01

    We studied the dynamics of thermoluminescence during destruction of porous structures formed by nanoclusters of nitrogen molecules containing high concentrations of stabilized nitrogen atoms. The porous structures were formed in bulk superfluid helium by injection of the products of discharges in nitrogen-helium gas mixtures through the liquid helium surface. Fast recombination of nitrogen atoms during warming-up led to explosive destruction of the porous structures accompanied by bright flashes. Intense emissions from the α -group of nitrogen atoms, the β -group of oxygen atoms and the Vegard-Kaplan bands of N_2 molecules were observed at the beginning of destruction. At the end of destruction the M- and β -bands of NO molecules as well as bands of O_2 molecules were also observed. Observation of the emissions from NO molecules at the end of destruction was explained by processes of accumulation of NO molecules in the system due to the large van der Waals interaction of NO molecules. For the first time, we observed the emission of the O_2 molecules at the end of destruction of the porous nitrogen structures as a result of the (NO)_2 dimer formation in solid nitrogen and subsequent processes leading to the appearance of excited O_2 molecules.

  16. Facile synthesis of tin phosphite nanosheets via exfoliated bulk crystals: Electronic structure and piezoelectric property.

    Science.gov (United States)

    Song, Jun-Ling; Zhang, Xi-Rui; Lu, Rui-Feng

    2016-08-01

    Tin phosphite nanosheets were synthesized by a facile exfoliation method. SnHPO3 nanosheets with a thickness of ∼2.6nm readily form a stable colloidal suspension in ethanol using ultrasonic method. Structures and optical properties of the obtained nanosheets were investigated. The prepared SnHPO3 nanosheets exhibit an obvious blue-shift in UV absorbance compared with bulk SnHPO3 crystal materials. Moreover, the piezoelectric coefficients of SnHPO3 monolayer were calculated based on density functional theory, which are larger than that of h-BN monolayer, indicating this material could be a good candidate for designing electro-optical nano-devices. PMID:27175829

  17. Anomalous absorption of bulk shear sagittal acoustic waves in a layered structure with viscous fluid

    CERN Document Server

    Gramotnev, D K; Nieminen, T A; Gramotnev, Dmitri K.; Mather, Melissa L.; Nieminen, Timo A.

    2003-01-01

    It is demonstrated theoretically that the absorptivity of bulk shear sagittal waves by an ultra-thin layer of viscous fluid between two different elastic media has a strong maximum (in some cases as good as 100%) at an optimal layer thickness. This thickness is usually much smaller than the penetration depths and lengths of transverse and longitudinal waves in the fluid. The angular dependencies of the absorptivity are demonstrated to have significant and unusual structure near critical angles of incidence. The effect of non-Newtonian properties and non-uniformities of the fluid layer on the absorptivity is also investigated. In particular, it is shown that the absorption in a thin layer of viscous fluid is much more sensitive to non-zero relaxation time(s) in the fluid layer than the absorption at an isolated solid-fluid interface.

  18. Study of substitution limit, structural, bulk magnetic and electrical properties of Ca2+ substituted magnesium ferrite

    International Nuclear Information System (INIS)

    The percentage substitution of large cation like Ca2+ for Mg2+ in MgFe2O4 without altering the cubic symmetry and its effect on structural, bulk magnetic and electrical properties have been investigated for Mg1-xCaxFe2O4 (x=0.0-0.35) spinel ferrite system by means of X-ray diffraction (XRD), magnetization, ac susceptibility and dc resistivity measurements. It is found that a maximum of 23% of Ca2+ can be substituted for Mg2+. The variation of magneton number with x can be explained on the basis of Neel's collinear spin model. The Neel temperature determined through ac susceptibility and dc resistivity measurements agree with those calculated theoretically. The variation of electrical resistivity go hand in hand with the variation of the activation energy with the Ca-content

  19. Perturbation approach to reconstructions of boundary deformations in waveguide structures

    OpenAIRE

    Dalarsson, Mariana

    2016-01-01

    In this thesis we develop inverse scattering algorithms towards the ultimate goal of online diagnostic methods. The aim is to detect structural changes inside power transformers and other major power grid components, like generators, shunt reactors etc. Power grid components, such as large power transformers, are not readily available from the manufacturers as standard designs. They are generally optimized for specific functions at a specific position in the power grid. Their replacement is v...

  20. THE DEFORMATION MACADAM-MASTIC JOINT FOR ENGINEERING STRUCTURE ON THE ROADS

    OpenAIRE

    Savenko, V.; Kaskiv, V.; Artemenko, K.

    2006-01-01

    The article is devoted to the deformation macadam-mastic joints for engineering structures on of road. The questions of advantage of the given type of joint and questions of technology of their construction are considered, the requirements to the mastics are resulted.

  1. Shear-deforming textile reinforced concrete for the construction of double-curved structures

    NARCIS (Netherlands)

    Woodington, W.; Bergsma, O.K.; Schipper, H.R.

    2015-01-01

    A composite textile reinforced concrete (TRC) material is developed to overcome the difficulties of constructing double-curved freeform structures. This is possible by shear-deformation of the woven reinforcement. It affects the direction of reinforcement and thickness, resulting in variable orthotr

  2. Modelling and Simulation of Structural Deformation of Isothermal Subsurface Flow and Carbon Dioxide Injection

    KAUST Repository

    El-Amin, M.F.

    2011-05-15

    Injection of CO2 in hydrocarbon reservoir has double benefit. On the one hand, it is a profitable method due to issues related to global warming, and on the other hand it is an effective mechanism to enhance hydrocarbon recovery. Such injection associates complex processes involving, e.g., solute transport of dissolved materials, in addition to local changes in density of the phases. Also, increasing carbon dioxide injection may cause a structural deformation of the medium, so it is important to include such effect into the model. The structural deformation modelling in carbon sequestration is important to evaluate the medium stability to avoid CO2 leakage to the atmosphere. On the other hand, geologic formation of the medium is usually heterogeneous and consists of several layers of different permeability. In this work we conduct numerical simulation of two-phase flow in a heterogeneous porous medium domain with dissolved solute transport as well as structural deformation effects. The solute transport of the dissolved component is described by concentration equation. The structural deformation for geomechanics is derived from a general local differential balance equation with neglecting the local mass balance of solid phase and the inertial force term. The flux continuity condition is used at interfaces between different permeability layers of the heterogeneous medium. We analyze the vertical migration of a CO2 plume injected into a 2D layered reservoir. Analysis of distribution of flow field components such as saturation, pressures, velocities, and CO2 concentration are presented.

  3. Bulk metallic glassy surface native oxide: Its atomic structure, growth rate and electrical properties

    International Nuclear Information System (INIS)

    Formation of a native oxide layer on the surface of bulk metallic glasses (BMGs) influences significantly the nanoscale tribological properties and mechanical behavior of the BMGs used in nanodevices. However, our knowledge of the native oxidation process on the BMG surface and structure of the corresponding oxides remains limited because the oxide layer is very thin. Here we conducted a combined state-of-the-art experimental technique study of the atomic structure, oxidations states and electrical conductivity of the native surface oxides on a Cu−Zr−Al BMG formed at ambient conditions by aberration-corrected scanning transmission electron microscopy (STEM), X-ray photoelectron spectroscopy (XPS) and conductive atomic force microscopy (AFM). This allowed shedding light on the atomic structure, metal oxidation state, growth behavior and nanoscale electrical properties of the surface oxide. The conductive AFM measurements reveal that the electrical conductivity of the native oxide layer transits from the initially metallic to a nonlinear one after some air exposure, and finally changes to insulative state. These findings represent a significant step forward in the knowledge of surface oxides and open up the possibility of fabricating nanoscale electrical devices based on BMGs with controllable conductivity

  4. Dislocation Structures in Creep-deformed Polycrystalline MgO

    DEFF Research Database (Denmark)

    Bilde-Sørensen, Jørgen

    1972-01-01

    Secondary creep of polycrystalline MgO with grain sizes of 100 and 190 μm was investigated at 1300° to 1460°C under compressive loads of 2.5 to 5.5 kgf/mm2. The dependence of creep rate on load follows a power law with an exponent of 3.2±0.3. The process is thermally activated, with an activation...... energy of 76 ± 12 kcal/mol. The creep rate is independent of grain size. The dislocation structure was investigated by transmission electron microscopy. The total dislocation density follows the relation, σ=bG√ρ, commonly found for metals. The dislocations form a 3-dimensional network in which many...

  5. Formation of ultrafine-grained (UFG structure and mechanical properties by severe plastic deformation (SPD

    Directory of Open Access Journals (Sweden)

    M. Besterci

    2008-10-01

    Full Text Available Commercial pure cooper (99,9% Cu was deformed by equal channel angular pressing (ECAP using up to 10 passes, route C. The evolution of microstructure and fracture character were observed by OM, SEM and TEM. The mean grain size decreased with increasing deformation, after 10 passes to 100 – 300 nm. TEM analysis suggested the possible nanostructure formation mechanism by the formation of cellular structure in grains, forming of subgrains and then forming of high angle nanograins with random orientation. Fractures of ECAP Cu material after 10 passes had transcrystalline ductile character with dimple morphology.

  6. Structural and electronic properties of bulk YN and of the YN/ScN superlattice

    International Nuclear Information System (INIS)

    The structural and electronic properties of YN are investigated using two different first principles methods, the full potential linear augmented plane waves (FPLAPW) method and a recent version of the first principles full potential linear muffin-tin orbitals method (FPLMTO) which enables an accurate treatment of the interstitial regions. Our calculations show that the ground state configuration of YN is the rocksalt (B1) structure and that it is a semiconductor. We have also investigated the A3 hexagonal structure which is nearly five-times coordinated and found it more stable than the previous wurtzite phase. So we confirm the presence of another local minimum, but in this A3 phase and not in the wurtzite (B4). Nevertheless, the transition from rocksalt (B1) to CsCl (B2) structure is found to be possible at high pressure. The zinc blende structure (B3) has also been investigated and is found to have a large and direct fundamental gap. The resemblances between YN and ScN and their small lattice mismatch led us to perform predictive investigations on rocksalt/rocksalt ScN/YN heterostructure superlattices. The latter shows interesting features: these systems constituted from indirect bandgap bulk materials are found to have a direct bandgap suggesting that the reason is probably the zone folding phenomena which is suspected to be at the origin of a similar effect observed in the popular Si/SiGe systems. To our knowledge, rocksalt/rocksalt superlattice systems have not received particular attention before. (author)

  7. Structural, thermodynamic, and mechanical properties of bulk La and A-La2O3

    International Nuclear Information System (INIS)

    Highlights: • GGA is more realistic to reflect properties of La and La2O3 than LDA. • Elastic anisotropy causes big anisotropy of thermal expansion of A-La2O3. • Elastic properties of La2O3 decease linearly with increase of temperature. • Covalent bonding of La2O3 is enhanced with the decrease of temperature. • Calculated results are in good agreement with experimental observations. - Abstract: First principles calculations are combined with the quasi-harmonic approximation and thermal electronic excitation, to have a systematic study of structural, thermodynamic (CV, CP, and αL), and mechanical (Cij, B, G, and E) properties of bulk La and A-La2O3. It is found that the generalized gradient approximation gives a much better reflection of the ground state properties than local density approximation, and that a very strong covalent bonding is formed in A-La2O3, mainly due to the pronounced hybridization between O 2p and La 5d as well as 5p states. Calculations also reveal that the electronic contribution to heat capacity of fcc La should be bigger than that of dhcp La, and that elastic anisotropy of A-La2O3 would cause the big difference of thermal expansion along the a and c axes. Moreover, the elastic properties of La and A-La2O3 decease almost linearly with the increase of temperature, and the descending sequence of bulk moduli is E → B → G within the entire temperature range. The strong covalent bonding of A-La2O3 would be enhanced (reduced) with the decrease (increase) of temperature, and the calculated results are in good agreement with experimental observations in the literature

  8. Structure and magnetism of bulk Fe and Cr: from plane waves to LCAO methods

    International Nuclear Information System (INIS)

    Magnetic, structural and energetic properties of bulk Fe and Cr were studied using first-principles calculations within density functional theory (DFT). We aimed to identify the dependence of these properties on key approximations of DFT, namely the exchange-correlation functional, the pseudopotential and the basis set. We found a smaller effect of pseudopotentials (PPs) on Fe than on Cr. For instance, the local magnetism of Cr was shown to be particularly sensitive to the potentials representing the core electrons, i.e. projector augmented wave and Vanderbilt ultrasoft PPs predict similar results, whereas standard norm-conserving PPs tend to overestimate the local magnetic moments of Cr in bcc Cr and in dilute bcc FeCr alloys. This drawback is suggested to be closely correlated to the overestimation of Cr solution energy in the latter system. On the other hand, we point out that DFT methods with very reduced localized basis sets (LCAO: linear combination of atomic orbitals) give satisfactory results compared with more robust plane-wave approaches. A minimal-basis representation of '3d' electrons comes to be sufficient to describe non-trivial magnetic phases including spin spirals in both fcc Fe and bcc Cr, as well as the experimental magnetic ground state of bcc Cr showing a spin density wave (SDW) state. In addition, a magnetic 'spd' tight binding model within the Stoner formalism was proposed and validated for Fe and Cr. The respective Stoner parameters were obtained by fitting to DFT data. This efficient semiempirical approach was shown to be accurate enough for studying various collinear and non-collinear phases of bulk Fe and Cr. It also enabled a detailed investigation of different polarization states of SDW in bcc Cr, where the longitudinal state was suggested to be the ground state, consistent with existing experimental data.

  9. Structure and magnetism of bulk Fe and Cr: from plane waves to LCAO methods.

    Science.gov (United States)

    Soulairol, R; Fu, Chu-Chun; Barreteau, C

    2010-07-28

    Magnetic, structural and energetic properties of bulk Fe and Cr were studied using first-principles calculations within density functional theory (DFT). We aimed to identify the dependence of these properties on key approximations of DFT, namely the exchange-correlation functional, the pseudopotential and the basis set. We found a smaller effect of pseudopotentials (PPs) on Fe than on Cr. For instance, the local magnetism of Cr was shown to be particularly sensitive to the potentials representing the core electrons, i.e. projector augmented wave and Vanderbilt ultrasoft PPs predict similar results, whereas standard norm-conserving PPs tend to overestimate the local magnetic moments of Cr in bcc Cr and in dilute bcc FeCr alloys. This drawback is suggested to be closely correlated to the overestimation of Cr solution energy in the latter system. On the other hand, we point out that DFT methods with very reduced localized basis sets (LCAO: linear combination of atomic orbitals) give satisfactory results compared with more robust plane-wave approaches. A minimal-basis representation of '3d' electrons comes to be sufficient to describe non-trivial magnetic phases including spin spirals in both fcc Fe and bcc Cr, as well as the experimental magnetic ground state of bcc Cr showing a spin density wave (SDW) state. In addition, a magnetic 'spd' tight binding model within the Stoner formalism was proposed and validated for Fe and Cr. The respective Stoner parameters were obtained by fitting to DFT data. This efficient semiempirical approach was shown to be accurate enough for studying various collinear and non-collinear phases of bulk Fe and Cr. It also enabled a detailed investigation of different polarization states of SDW in bcc Cr, where the longitudinal state was suggested to be the ground state, consistent with existing experimental data. PMID:21399309

  10. Structure and magnetism of bulk Fe and Cr: from plane waves to LCAO methods

    Energy Technology Data Exchange (ETDEWEB)

    Soulairol, R; Fu, Chu-Chun [CEA, DEN, Service de Recherches de Metallurgie Physique, F-91191 Gif-sur-Yvette (France); Barreteau, C, E-mail: chuchun.fu@cea.f [CEA Saclay, DSM/DRECAM/SPCSI, Batiment 462, F-91191 Gif-sur-Yvette (France)

    2010-07-28

    Magnetic, structural and energetic properties of bulk Fe and Cr were studied using first-principles calculations within density functional theory (DFT). We aimed to identify the dependence of these properties on key approximations of DFT, namely the exchange-correlation functional, the pseudopotential and the basis set. We found a smaller effect of pseudopotentials (PPs) on Fe than on Cr. For instance, the local magnetism of Cr was shown to be particularly sensitive to the potentials representing the core electrons, i.e. projector augmented wave and Vanderbilt ultrasoft PPs predict similar results, whereas standard norm-conserving PPs tend to overestimate the local magnetic moments of Cr in bcc Cr and in dilute bcc FeCr alloys. This drawback is suggested to be closely correlated to the overestimation of Cr solution energy in the latter system. On the other hand, we point out that DFT methods with very reduced localized basis sets (LCAO: linear combination of atomic orbitals) give satisfactory results compared with more robust plane-wave approaches. A minimal-basis representation of '3d' electrons comes to be sufficient to describe non-trivial magnetic phases including spin spirals in both fcc Fe and bcc Cr, as well as the experimental magnetic ground state of bcc Cr showing a spin density wave (SDW) state. In addition, a magnetic 'spd' tight binding model within the Stoner formalism was proposed and validated for Fe and Cr. The respective Stoner parameters were obtained by fitting to DFT data. This efficient semiempirical approach was shown to be accurate enough for studying various collinear and non-collinear phases of bulk Fe and Cr. It also enabled a detailed investigation of different polarization states of SDW in bcc Cr, where the longitudinal state was suggested to be the ground state, consistent with existing experimental data.

  11. Shell-structure of one-particle resonances in deformed potentials

    CERN Document Server

    Hamamoto, Ikuko

    2016-01-01

    Shell structure of low-lying neutron resonant levels in axially-symmetric quadrupole-deformed potentials is discussed, which seems analogous to that of weakly-bound neutrons. As numerical examples, nuclei slightly outside the neutron-drip-line, $^{39}_{12}$Mg$_{27}$ and $^{21}_{6}$C$_{15}$, are studied. For the lowest resonance I obtain $I^{\\pi}$ = $\\Omega^{\\pi}$ = 5/2$^{-}$ for $^{39}$Mg which is likely to be prolately deformed, while $I^{\\pi}$ = $\\Omega^{\\pi}$ = 1/2$^{+}$ may be assigned to the nucleus $^{21}$C which may be oblately deformed. Consequently, $^{21}$C will not be observed as a recognizable resonant state, in agreement with the experimental information.

  12. Local equivalent welding element to predict the welding deformations of plate-type structures

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Considering the Heat Affected Zone (HAZ) of welding joint, the residual strain be-haviors of material under constraint and temperature circulation, as well as the activating mechanism of welding process, this paper addresses a new type welding element for numerical simulation of welding deformation, which is called the LEWE (the local equivalent welding element). This element can describe the basic char-acteristics of welded seam: the local position points of inherent strain, the equiva-lent size, the bending radius (or bending angle) from inherent strain, etc. It could be used to predict the welding deformation of plate-type structure. The comparisons between the computed deflection of welded plate and its experiment measurement are present. The results showed that the LEWE possesses a potential to simulate the deformation of welding process high-efficiently and precisely.

  13. Inherited structures impact on co-seismic surface deformation pattern during the 2013 Balochistan, Pakistan, earthquake

    Science.gov (United States)

    Vallage, Amaury; Klinger, Yann; Grandin, Raphael; Delorme, Arthur; Pierrot-Deseilligny, Marc

    2016-04-01

    The understanding of earthquake processes and the interaction of earthquake rupture with Earth's free surface relies on the resolution of the observations. Recent and detailed post-earthquake measurements bring new insights on shallow mechanical behavior of rupture processes as it becomes possible to measure and locate surficial deformation distribution. The 2013 Mw 7.7 Balochistan earthquake, Pakistan, offers a nice opportunity to comprehend where and why surficial deformation might differs from at-depth localized slip. This earthquake ruptured the Hoshab fault over 200 km; the motion was mainly left lateral with a small and discontinuous vertical component in the southern part of the rupture. Using images with the finest resolution currently available, we measured the surface displacement amplitude and its orientation at the ground surface (including the numerous tensile cracks). We combined these measurements with the 1:500 scale ground rupture map to focus on the behavior of the frontal rupture in the area where deformation distributes. Comparison with orientations of inherited tectonic structures, visible in older rocks formation surrounding the actual 2013 rupture, shows the control exercised by such structures on co-seismic rupture distribution. Such observation raises the question on how pre-existing tectonic structures in a medium, mapped in several seismically active places around the globe; can control the co-seismic distribution of the deformation during earthquakes.

  14. Formation of a submicrocrystalline structure in metastable austenitic steels during severe plastic deformation and subsequent heating

    Science.gov (United States)

    Mal'tseva, L. A.; Mal'tseva, T. V.; Yurovskikh, A. S.; Raab, G. I.; Sharapova, V. A.; Vakhonina, K. D.

    2016-03-01

    The structure and the mechanical properties of metastable austenitic steels after severe plastic deformation by four or six passes of equal-channel angular pressing (ECAP) at a temperature of 400°C are studied. It is shown that ECAP results in strain hardening mainly due to the formation of a submicrocrystalline structure, which is retained after subsequent heating to 500°C.

  15. Analysis of shear deformation scheme efficiency in plastic structure formation processes

    Directory of Open Access Journals (Sweden)

    G. I. Raab

    2015-03-01

    Full Text Available The paper is devoted to the analysis of such an important factor as deformation behavior in the simple shear conditions.It is shown that non-monotonous character of material plastic flow exerts significant influence on the intensity of initial structure refinement. Induced non-monotonous character that ensures formation of equiaxed structural states plays an important role in the process.

  16. NANODIMENTIONAL STRUCTURAL PART FORMATION IN HIGH CARBON STEEL BY THERMAL AND DEFORMATION PROCESSING

    OpenAIRE

    CHUKIN MICHAIL VITAL,EVICH; Korchunov, Alexei; Gun, Gennadiy; Polyakova, Marina; Koptseva, Natalya

    2013-01-01

    On the example of high carbon steel of grade 80, updated by boron, the ability of forming nanodimensional structural constituents has been proved. Special types of thermal and deformation processing are used. The thinplate pearlite structure, obtained in this way, according to modern material science concept is considered to be a nanomaterial where interlamellar spacing in a ferrite-carbide mixture is a nanodimensional element. It is experimentally proved that interlamellar spacing decreasing...

  17. Atomistic tensile deformation mechanisms of Fe with gradient nano-grained structure

    Directory of Open Access Journals (Sweden)

    Wenbin Li

    2015-08-01

    Full Text Available Large-scale molecular dynamics (MD simulations have been performed to investigate the tensile properties and the related atomistic deformation mechanisms of the gradient nano-grained (GNG structure of bcc Fe (gradient grains with d from 25 nm to 105 nm, and comparisons were made with the uniform nano-grained (NG structure of bcc Fe (grains with d = 25 nm. The grain size gradient in the nano-scale converts the applied uniaxial stress to multi-axial stresses and promotes the dislocation behaviors in the GNG structure, which results in extra hardening and flow strength. Thus, the GNG structure shows slightly higher flow stress at the early plastic deformation stage when compared to the uniform NG structure (even with smaller grain size. In the GNG structure, the dominant deformation mechanisms are closely related to the grain sizes. For grains with d = 25 nm, the deformation mechanisms are dominated by GB migration, grain rotation and grain coalescence although a few dislocations are observed. For grains with d = 54 nm, dislocation nucleation, propagation and formation of dislocation wall near GBs are observed. Moreover, formation of dislocation wall and dislocation pile-up near GBs are observed for grains with d = 105 nm, which is the first observation by MD simulations to our best knowledge. The strain compatibility among different layers with various grain sizes in the GNG structure should promote the dislocation behaviors and the flow stress of the whole structure, and the present results should provide insights to design the microstructures for developing strong-and-ductile metals.

  18. Atomistic tensile deformation mechanisms of Fe with gradient nano-grained structure

    International Nuclear Information System (INIS)

    Large-scale molecular dynamics (MD) simulations have been performed to investigate the tensile properties and the related atomistic deformation mechanisms of the gradient nano-grained (GNG) structure of bcc Fe (gradient grains with d from 25 nm to 105 nm), and comparisons were made with the uniform nano-grained (NG) structure of bcc Fe (grains with d = 25 nm). The grain size gradient in the nano-scale converts the applied uniaxial stress to multi-axial stresses and promotes the dislocation behaviors in the GNG structure, which results in extra hardening and flow strength. Thus, the GNG structure shows slightly higher flow stress at the early plastic deformation stage when compared to the uniform NG structure (even with smaller grain size). In the GNG structure, the dominant deformation mechanisms are closely related to the grain sizes. For grains with d = 25 nm, the deformation mechanisms are dominated by GB migration, grain rotation and grain coalescence although a few dislocations are observed. For grains with d = 54 nm, dislocation nucleation, propagation and formation of dislocation wall near GBs are observed. Moreover, formation of dislocation wall and dislocation pile-up near GBs are observed for grains with d = 105 nm, which is the first observation by MD simulations to our best knowledge. The strain compatibility among different layers with various grain sizes in the GNG structure should promote the dislocation behaviors and the flow stress of the whole structure, and the present results should provide insights to design the microstructures for developing strong-and-ductile metals

  19. COUPLING COMPUTATION OF THE FLOW FIELD AND THE LARGE DEFORMATION OF MEMBRANE STRUCTURE OF STRATOSPHERE AIRSHIPS

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-min

    2008-01-01

    In this article, the mathematical model of the coupling of the three-dimensional fluid flow and the large deformation of membrane structure is established. The fluid-structure coupling interaction is simulated using the computational codes developed by the authors. By analyzing the interactions of membrane and flow field, the aeroelasticity of the airship is detailed. All the results are adopted in the focused study of the stratosphere airship in trimmed state.

  20. Radiative processes as a condensation phenomenon and the physical meaning of deformed canonical structures

    International Nuclear Information System (INIS)

    We study the radiative corrections of QED3 from the dual point of view and show that this process is the exact dual to the Julia-Toulouse mechanism introduced by Quevedo and Trugenberger [F. Quevedo, C.A. Trugenberger, Nucl. Phys. B 501 (1997) 143] some years ago. We discuss the physics behind this mechanism that involves condensation of topological defects. It is shown that the dual Stuckelberg mechanism is responsible for the 'rank-jump' phenomenon that transforms the scalar field (dual to Maxwell in this dimensionality) into the vectorial self-dual field. This phenomenon is studied using the ideas of noncommutative fields theory that examines possible deformations of the canonical structure of some well-known models in (2+1)D. A deformation is constructed linking the massless scalar field theory with the self-dual theory. This is the exact dual of the known deformation connecting the Maxwell theory with the Maxwell-Chern-Simons theory. Duality, radiative corrections, the Julia-Toulouse mechanism and canonical deformations are then used to establish a web of relations between the mentioned theories and to propose a physical picture of the deformation procedure adopted

  1. Large Deformation of an Elastic Rod with Structural Anisotropy Subjected to Fluid Flow

    Science.gov (United States)

    Hassani, Masoud; Mureithi, Njuki; Gosselin, Frederick

    2015-11-01

    In the present work, we seek to understand the fundamental mechanisms of three-dimensional reconfiguration of plants by studying the large deformation of a flexible rod in fluid flow. Flexible rods made of Polyurethane foam and reinforced with Nylon fibers are tested in a wind tunnel. The rods have bending-torsion coupling which induces a torsional deformation during asymmetric bending. A mathematical model is also developed by coupling the Kirchhoff rod theory with a semi-empirical drag formulation. Different alignments of the material frame with respect to the flow direction and a range of structural properties are considered to study their effect on the deformation of the flexible rod and its drag scaling. Results show that twisting causes the flexible rods to reorient and bend with the minimum bending rigidity. It is also found that the drag scaling of the rod in the large deformation regime is not affected by torsion. Finally, using a proper set of dimensionless numbers, the state of a bending and twisting rod is characterized as a beam undergoing a pure bending deformation.

  2. The interplay between dynamic heterogeneities and structure of bulk liquid water: A molecular dynamics simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Demontis, Pierfranco; Suffritti, Giuseppe B. [Dipartimento di Chimica e Farmacia, Università degli studi di Sassari, Sassari (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), Unità di ricerca di Sassari, Via Vienna, 2, I-07100 Sassari (Italy); Gulín-González, Jorge [Grupo de Matemática y Física Computacionales, Universidad de las Ciencias Informáticas (UCI), Carretera a San Antonio de los Baños, Km 21/2, La Lisa, La Habana (Cuba); Masia, Marco [Dipartimento di Chimica e Farmacia, Università degli studi di Sassari, Sassari (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), Unità di ricerca di Sassari, Via Vienna, 2, I-07100 Sassari (Italy); Istituto Officina dei Materiali del CNR, UOS SLACS, Via Vienna 2, 07100 Sassari (Italy); Sant, Marco [Dipartimento di Chimica e Farmacia, Università degli studi di Sassari, Sassari (Italy)

    2015-06-28

    In order to study the interplay between dynamical heterogeneities and structural properties of bulk liquid water in the temperature range 130–350 K, thus including the supercooled regime, we use the explicit trend of the distribution functions of some molecular properties, namely, the rotational relaxation constants, the atomic mean-square displacements, the relaxation of the cross correlation functions between the linear and squared displacements of H and O atoms of each molecule, the tetrahedral order parameter q and, finally, the number of nearest neighbors (NNs) and of hydrogen bonds (HBs) per molecule. Two different potentials are considered: TIP4P-Ew and a model developed in this laboratory for the study of nanoconfined water. The results are similar for the dynamical properties, but are markedly different for the structural characteristics. In particular, for temperatures higher than that of the dynamic crossover between “fragile” (at higher temperatures) and “strong” (at lower temperatures) liquid behaviors detected around 207 K, the rotational relaxation of supercooled water appears to be remarkably homogeneous. However, the structural parameters (number of NNs and of HBs, as well as q) do not show homogeneous distributions, and these distributions are different for the two water models. Another dynamic crossover between “fragile” (at lower temperatures) and “strong” (at higher temperatures) liquid behaviors, corresponding to the one found experimentally at T{sup ∗} ∼ 315 ± 5 K, was spotted at T{sup ∗} ∼ 283 K and T{sup ∗} ∼ 276 K for the TIP4P-Ew and the model developed in this laboratory, respectively. It was detected from the trend of Arrhenius plots of dynamic quantities and from the onset of a further heterogeneity in the rotational relaxation. To our best knowledge, it is the first time that this dynamical crossover is detected in computer simulations of bulk water. On the basis of the simulation results, the possible

  3. Lithospheric structure and deformation of the North American continent

    Science.gov (United States)

    Tesauro, Magdala; Kaban, Mikhail; Cloetingh, Sierd; Mooney, Walter

    2013-04-01

    We estimate the integrated strength and elastic thickness (Te) of the North American lithosphere based on thermal, density and structural (seismic) models of the crust and upper mantle. The temperature distribution in the lithosphere is estimated considering for the first time the effect of composition as a result of the integrative approach based on a joint analysis of seismic and gravity data. We do this via an iterative adjustment of the model. The upper mantle temperatures are initially estimated from the NA07 tomography model of Bedle and Van der Lee (2009) using mineral physics equations. This thermal model, obtained for a uniform composition, is used to estimate the gravity effect and to remove it from the total mantle gravity anomalies, which are controlled by both temperature and compositional variations. Therefore, we can predict compositional variations from the residual gravity anomalies and use them to correct the initial thermal model. The corrected thermal model is employed again in the gravity calculations. The loop is repeated until convergence is reached. The results demonstrate that the lithospheric mantle is characterized by strong compositional heterogeneity, which is consistent with xenolith data. Seismic data from the USGS database allow to define P-wave velocity and thickness of each crustal layer of the North American geological provinces. The use of these seismic data and of the new compositional and thermal models gives us the chance to estimate lateral variation of rheology of the main lithospheric layers and to evaluate coupling-decoupling conditions at the layers' boundaries. In the North American Cordillera the strength is mainly localized in the crust, which is decoupled from the mantle lithosphere. In the cratons the strength is chiefly controlled by the mantle lithosphere and all the layers are generally coupled. These results contribute to the long debates on applicability of the "crème brulée" or "jelly-sandwich" models for the

  4. Structure and properties of Fe-36% Ni alloy after heavy shear deformation

    International Nuclear Information System (INIS)

    A study was made into the influence of large shear strain by pressing on structure, mechanical and thermal properties of the Fe-36% Ni invar. The first pressing pass (70% reduction) is shown to result in formation of strip structure. An increase of the number of passes with changing shear deformation direction for reverse one at every even pressing p[ass promotes strip structure transformation into fragmented one. Yield strength of the alloy increases from 300 to 650 N/mm2 after the first pass. After 12 passes at attains the value of 800 N/mm2 due to strain hardening. A linear thermal expansion coefficient varies nonmonotonously with deformation, and after 12 passes preserves a permissible value. 17 refs., 10 figs

  5. Model of a thermo-elastic-inelastic process with large deformations and structural changes in material

    Science.gov (United States)

    Rogovoi, A. A.

    2015-09-01

    The dependence of a scalar measure of the structural changes occurring in a material under plastic deformation on a plastic strain measure and the dependence of a free energy measure on a structural change measure are constructed using experimental data that allow the expended plastic work to be divided into a latent part and a thermal part. The obtained dependences, kinematic relations, a constitutive equation, and a heat-conduction equation that satisfy the principles of thermodynamics and objectivity are used to construct a model of thermo-elastic-inelastic processes in the presence of finite deformations and structural changes in the material. The model is tested on the problem of temperature changes in the process of adiabatic elastic-plastic compression, which has experimental support.

  6. Nickel silicide thin films as masking and structural layers for silicon bulk micro-machining by potassium hydroxide wet etching

    International Nuclear Information System (INIS)

    This paper studies the feasibility of using titanium and nickel silicide thin films as mask materials for silicon bulk micro-machining. Thin films of nickel silicide were found to be more resistant to wet etching in potassium hydroxide. The use of nickel silicide as a structural material, by fabricating micro-beams of varying dimensions, is demonstrated. The micro-structures were realized using these thin films with wet etching using potassium hydroxide solution on (1 0 0) and (1 1 0) silicon substrates. These results show that nickel silicide is a suitable alternative to silicon nitride for silicon bulk micro-machining

  7. Fluid-Structure Interaction Study on a Pre-Buckled Deformable Flat Ribbon

    Science.gov (United States)

    Fovargue, Lauren; Shams, Ehsan; Watterson, Amy; Corson, Dave; Filardo, Benjamin; Zimmerman, Daniel; Shan, Bob; Oberai, Assad

    2015-11-01

    A Fluid-Structure Interaction study is conducted for the flow over a deformable flat ribbon. This mechanism, which is called ribbon frond, maybe used as a device for pumping water and/or harvesting energy in rivers. We use a lower dimensional mathematical model, which represents the ribbon as a pre-buckled structure. The surface forces from the fluid flow, dictate the deformation of the ribbon, and the ribbon in turn imposes boundary conditions for the incompressible Navier-Stokes equations. The mesh motion is handled using an Arbitrary Lagrangian-Eulerian (ALE) scheme and the fluid-structure coupling is handled by iterating over the staggered governing equations for the structure, the fluid and the mesh. Simulations are conducted at three different free stream velocities. The results, including the frequency of oscillations, show agreement with experimental data. The vortical structures near the surface of the ribbon and its deformation are highly correlated. It is observed that the ribbon motion exhibits deviation from a harmonic motion, especially at lower free stream velocities. The behavior of the ribbon is compared to swimming animals, such as eels, in order to better understand its performance. The authors acknowledge support from ONR SBIR Phase II, contract No. N0001412C0604 and USDA, NIFA SBIR Phase I, contract No. 2013-33610-20836 and NYSERDA PON 2569, contract No. 30364.

  8. The role of deformable structured surfaces on viscous forces during peeling

    Science.gov (United States)

    Dhong, Charles; Frechette, Joelle

    It is known that tree frogs are able to adhere well in flooded environments, presumably due to their interconnected network of drainage channels formed by hexagonal epithelial cells in their toe pads. To investigate this effect, a patterned surface of hexagonally arranged cylindrical posts was brought close to a stationary substrate in a submerged, viscous fluid via a normal load, and then peeled off to measure a retraction force. Because these structured surfaces were made from PDMS, they are able to deform throughout the process. We find that these deformable surfaces further reduce the work required to peel apart the two surfaces, even when compared to previous studies in the same system with rigid structures, and we isolated these contributions independent of conservative forces. We then conducted experiments to compare the effect of deformation on the viscous forces and conservative forces. We find that there are several regimes where deformation either increases or decreases the retraction force since we have found that elasticity decreases retraction forces when considering viscous contributions but is also known to increase adhesion in the context of conservative forces. Office of Naval Research, National Science Foundation, Hopkins Extreme Materials Institute.

  9. The influence of thermo - mechanical processing on deformability and structural changes of duplex steel

    Directory of Open Access Journals (Sweden)

    K. Radwański

    2007-01-01

    Full Text Available Purpose: In conventional hot deformation methods of duplex steels, low values of boundary strain are obtained,resulting from the disparate behaviour of ferrite and austenite. This paper analyses the capacity for enhancingdeformability of two-phase ferritic-austenitic steels of the “duplex” type via thermo mechanical processing.Design/methodology/approach: Steel specimens were subjected to cold deformation with a 70% rollingreduction. After a hot solution treatment beginning at 1350°C, the specimens were tensioned in the “Instron”strength-testing machine in temperatures ranging from 800 to 950°C at a rate of vr=15×10-3÷3×10-1mm/s ina 0.005Pa vacuum. Structural examination was carried out using light and electron microscopy. A quantitativeanalysis of structural changes was performed using the „MetIlo” image analysis programme.Findings: The process parameters at which the investigated steel shows the superplastic flow effect havebeen determined.Practical implications: The capacity for increased deformability through combined thermo - mechanicalprocesses, requiring a precise selection of the deformation parameters, has been indicated.Originality/value: The results obtained are vital for designing an effective thermo - mechanical processingtechnology for the investigated steel.

  10. Motion and deformation estimation from medical imagery by modeling sub-structure interaction and constraints

    KAUST Repository

    Sundaramoorthi, Ganesh

    2012-09-13

    This paper presents a novel medical image registration algorithm that explicitly models the physical constraints imposed by objects or sub-structures of objects that have differing material composition and border each other, which is the case in most medical registration applications. Typical medical image registration algorithms ignore these constraints and therefore are not physically viable, and to incorporate these constraints would require prior segmentation of the image into regions of differing material composition, which is a difficult problem in itself. We present a mathematical model and algorithm for incorporating these physical constraints into registration / motion and deformation estimation that does not require a segmentation of different material regions. Our algorithm is a joint estimation of different material regions and the motion/deformation within these regions. Therefore, the segmentation of different material regions is automatically provided in addition to the image registration satisfying the physical constraints. The algorithm identifies differing material regions (sub-structures or objects) as regions where the deformation has different characteristics. We demonstrate the effectiveness of our method on the analysis of cardiac MRI which includes the detection of the left ventricle boundary and its deformation. The experimental results indicate the potential of the algorithm as an assistant tool for the quantitative analysis of cardiac functions in the diagnosis of heart disease.

  11. Structural changes in Bi-43 wt % Sn eutectic alloy under superplastic deformation

    Science.gov (United States)

    Korshak, V. F.; Shapovalov, Yu. A.; Prymak, O.; Kryshtal, A. P.; Vasilenko, R. L.

    2015-08-01

    Methods of scanning electron microscopy have been used to study the microstructure of superplastically deformed samples of eutectic alloy Bi-43 wt % Sn. The observed specific features of the deformation relief of the samples reveal the active development of the viscous dislocation-diffusion flow under superplasticity conditions. The manifestation of the hydrodynamic mode of deformation has been revealed under these conditions. The opportunity of the realization of viscous mechanisms of the transport of substance and of the manifestation of the effect of superplasticity are explained by the appearance in the material of a state that is characterized by a high dislocation density and low strength properties. An additional increase in the dislocation density and softening under superplasticity conditions are attributed to the occurrence of structural and phase transformations stimulated by deformation, the relaxation of significant internal elastic stresses, and the instability of the structural state of the initially nonequilibrium alloy in the field of mechanical stresses. Factors responsible for the appearance of significant internal elastic stresses in the alloy are analyzed.

  12. Ab-initio investigation of structural, electronic and optical properties BSb compound in bulk and surface (110 states

    Directory of Open Access Journals (Sweden)

    H A Badehian

    2015-07-01

    Full Text Available In recent work the structural, electronic and optical properties of BSb compound in bulk and surface (110 states have been studied. Calculations have been performed using Full-Potential Augmented Plane Wave (FP-LAPW method by WIEN2k code in Density Functional Theory (DFT framework. The structural properties of the bulk such as lattice constant, bulk module and elastic constants have been investigated using four different approximations. The band gap energy of the bulk and the (110 surface of BSb were obtained about 1.082 and 0.38 eV respectively. Moreover the surface energy, the work function, the surface relaxation, surface state and the band structure of BSb (110 were investigated using symmetric and stoichiometric 15 layers slabs with the vacuum of 20 Bohr. In addition, the real and imaginary parts of the dielectric function of the bulk and the BSb (110 slab were calculated and compared to each other. Our obtained results have a good agreement with the available results.

  13. Predicting Welding Distortion in a Panel Structure with Longitudinal Stiffeners Using Inherent Deformations Obtained by Inverse Analysis Method

    Directory of Open Access Journals (Sweden)

    Wei Liang

    2014-01-01

    Full Text Available Welding-induced deformation not only negatively affects dimension accuracy but also degrades the performance of product. If welding deformation can be accurately predicted beforehand, the predictions will be helpful for finding effective methods to improve manufacturing accuracy. Till now, there are two kinds of finite element method (FEM which can be used to simulate welding deformation. One is the thermal elastic plastic FEM and the other is elastic FEM based on inherent strain theory. The former only can be used to calculate welding deformation for small or medium scale welded structures due to the limitation of computing speed. On the other hand, the latter is an effective method to estimate the total welding distortion for large and complex welded structures even though it neglects the detailed welding process. When the elastic FEM is used to calculate the welding-induced deformation for a large structure, the inherent deformations in each typical joint should be obtained beforehand. In this paper, a new method based on inverse analysis was proposed to obtain the inherent deformations for weld joints. Through introducing the inherent deformations obtained by the proposed method into the elastic FEM based on inherent strain theory, we predicted the welding deformation of a panel structure with two longitudinal stiffeners. In addition, experiments were carried out to verify the simulation results.

  14. Electronic structure of metals and semiconductors: bulk, surface, and interface properties

    International Nuclear Information System (INIS)

    A theoretical study of the electronic structure of various metals and semiconductors is presented with the emphasis on understanding the properties of these materials when they are subjected to extreme conditions and in various different configurations. Among the bulk systems studied, the properties of cesium under high pressure are discussed in terms of the electronic structure calculated at various cell volumes using the pseudopotential method. Local fields or umklapp processes in semiconductors are studied within the random phase approximation (RPA). Specifically the dielectric response matrix epsilon/sub GG'/ (q = 0,omega) is evaluated numerically to determine the effects of local-field corrections in the optical spectrum of Si. Also, some comments on the excitonic mechanism of superconductivity are presented and the role of local fields is discussed. The pseudo-potential method is next extended to calculate the electronic structure of a transition metal Nb. The calculation is performed self-consistently with the use of a non-local ionic potential determined from atomic spectra. Finally the theory of the superconducting transition temperature T/sub c/ is discussed in the strong-coupling formulation of the BCS theory. The Eliashberg equations in the Matsubara representation are solved analytically and a general T/sub c/ equation is obtained. A new method is developed using pseudopotentials in a self-consistent manner to describe non-periodic systems. The method is applicable to localized configurations such as molecules, surfaces, impurities, vacancies, finite chains of atoms, adsorbates, and solid interfaces. Specific applications to surfaces, metal-semiconductor interfaces and vacancies are presented

  15. Electronic structure of metals and semiconductors: bulk, surface, and interface properties

    Energy Technology Data Exchange (ETDEWEB)

    Louie, S.G.S.

    1976-09-01

    A theoretical study of the electronic structure of various metals and semiconductors is presented with the emphasis on understanding the properties of these materials when they are subjected to extreme conditions and in various different configurations. Among the bulk systems studied, the properties of cesium under high pressure are discussed in terms of the electronic structure calculated at various cell volumes using the pseudopotential method. Local fields or umklapp processes in semiconductors are studied within the random phase approximation (RPA). Specifically the dielectric response matrix epsilon/sub GG'/ (q = 0,omega) is evaluated numerically to determine the effects of local-field corrections in the optical spectrum of Si. Also, some comments on the excitonic mechanism of superconductivity are presented and the role of local fields is discussed. The pseudo-potential method is next extended to calculate the electronic structure of a transition metal Nb. The calculation is performed self-consistently with the use of a non-local ionic potential determined from atomic spectra. Finally the theory of the superconducting transition temperature T/sub c/ is discussed in the strong-coupling formulation of the BCS theory. The Eliashberg equations in the Matsubara representation are solved analytically and a general T/sub c/ equation is obtained. A new method is developed using pseudopotentials in a self-consistent manner to describe non-periodic systems. The method is applicable to localized configurations such as molecules, surfaces, impurities, vacancies, finite chains of atoms, adsorbates, and solid interfaces. Specific applications to surfaces, metal-semiconductor interfaces and vacancies are presented.

  16. Structural Characterization of Carbon Nanomaterial Film In Situ Synthesized on Various Bulk Metals

    Directory of Open Access Journals (Sweden)

    J. Y. Xu

    2014-01-01

    Full Text Available Carbon nanofiber films were prepared via a simple chemical vapor deposition (CVD method on various bulk metal substrates including bulk 316 L stainless steel, pure cobalt, and pure nickel treated by surface mechanical attrition treatment (SMAT. The microstructures of the carbon nanomaterial film were studied by SEM, TEM, XRD, and Raman spectroscopy. In this paper, bulk metallic materials treated by SMAT served as substrates as well as catalysts for carbon nanomaterial film formation. The results indicate that the carbon nanofiber films are formed concerning the catalytic effects of the refined metallic particles during CVD on the surface of SMAT-treated bulk metal substrates. However, distinguished morphologies of carbon nanomaterial film are displayed in the case of the diverse bulk metal substrates.

  17. Semantic modeling of the structural and process entities during plastic deformation of crystals and rocks

    Science.gov (United States)

    Babaie, Hassan; Davarpanah, Armita

    2016-04-01

    We are semantically modeling the structural and dynamic process components of the plastic deformation of minerals and rocks in the Plastic Deformation Ontology (PDO). Applying the Ontology of Physics in Biology, the PDO classifies the spatial entities that participate in the diverse processes of plastic deformation into the Physical_Plastic_Deformation_Entity and Nonphysical_Plastic_Deformation_Entity classes. The Material_Physical_Plastic_Deformation_Entity class includes things such as microstructures, lattice defects, atoms, liquid, and grain boundaries, and the Immaterial_Physical_Plastic_Deformation_Entity class includes vacancies in crystals and voids along mineral grain boundaries. The objects under the many subclasses of these classes (e.g., crystal, lattice defect, layering) have spatial parts that are related to each other through taxonomic (e.g., Line_Defect isA Lattice_Defect), structural (mereological, e.g., Twin_Plane partOf Twin), spatial-topological (e.g., Vacancy adjacentTo Atom, Fluid locatedAlong Grain_Boundary), and domain specific (e.g., displaces, Fluid crystallizes Dissolved_Ion, Void existsAlong Grain_Boundary) relationships. The dynamic aspect of the plastic deformation is modeled under the dynamical Process_Entity class that subsumes classes such as Recrystallization and Pressure_Solution that define the flow of energy amongst the physical entities. The values of the dynamical state properties of the physical entities (e.g., Chemical_Potential, Temperature, Particle_Velocity) change while they take part in the deformational processes such as Diffusion and Dislocation_Glide. The process entities have temporal parts (phases) that are related to each other through temporal relations such as precedes, isSubprocessOf, and overlaps. The properties of the physical entities, defined under the Physical_Property class, change as they participate in the plastic deformational processes. The properties are categorized into dynamical, constitutive

  18. A bulk metal/ceramic composite material with a cellular structure

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zhankui; YAO Kefu; LI Jingfeng

    2006-01-01

    A bulk metal/ceramic composite material with a honeycomb-like micro-cell structure has been prepared by sintering the spherical Al90Mn9Ce1 alloy powders clad by Al2O3 nano-powder with the spark plasma sintering (SPS) technique. The as-prepared material consists of Al90Mn9Ce1 alloy cell and closed Al2O3 ceramic cell wall. The diameter of the cells is about 20―40 μm, while a thickness of the cell wall is about 1―2 μm. The ultimate compressive strength of the as-sintered materials is about 514 MPa, while its fracture strain is up to about 0.65 %. This composite material might possess good anti-corrosion, thermal endurance and other potential properties due to its unique microstructure. The result shows that the Al90Mn9Ce1/Al2O3 composite powders can be sintered by spark plasma sintering technique despite the large difference in their sintering temperature. This work offers a way of designing and preparing metal/ceramic composite material with functional property.

  19. Flexible structured high-frequency film bulk acoustic resonator for flexible wireless electronics

    International Nuclear Information System (INIS)

    Flexible electronics have inspired many novel and very important applications in recent years and various flexible electronic devices such as diodes, transistors, circuits, sensors, and radiofrequency (RF) passive devices including antennas and inductors have been reported. However, the lack of a high-performance RF resonator is one of the key bottlenecks to implement flexible wireless electronics. In this study, for the first time, a novel ultra-flexible structured film bulk acoustic resonator (FBAR) is proposed. The flexible FBAR is fabricated on a flexible polyimide substrate using piezoelectric thin film aluminum nitride (AlN) for acoustic wave excitation. Both the shear wave and longitudinal wave can be excited under the surface interdigital electrodes configuration we proposed. In the case of the thickness extension mode, a flexible resonator with a working frequency as high as of 5.2325 GHz has been realized. The resonators stay fully functional under bending status and after repeated bending and re-flattening operations. This flexible high-frequency resonator will serve as a key building block for the future flexible wireless electronics, greatly expanding the application scope of flexible electronics. (paper)

  20. On Bulk Singularity Structures and all order $\\alpha'$ Contact Terms of BPS String Amplitudes

    CERN Document Server

    Hatefi, Ehsan

    2016-01-01

    The entire form of the amplitude of three SYM ( involving two transverse scalar fields, a gauge field) and a potential $C_{n-1}$ Ramond-Ramond (RR) form field is found out. We first derive $$ and then start constructing an infinite number of $t,s$ channel bulk singularity structures by means of all order $\\alpha'$ corrections to pull-back of brane in an Effective Field Theory (EFT). Due to presence of the complete form of S-matrix, several new contact interactions as well as new couplings are explored. It is also shown that these couplings can be verified at the level of EFT by either the combinations of Myers terms, pull-back, Taylor expanded of scalar fields or the mixed combination of the couplings of this paper as well as employed Bianchi identities. For the first time, we also derive the algebraic and the complete form of the integrations for some arbitrary combinations of Mandelstam variables and for the most general case $\\int d^2z |1-z|^{a} |z|^{b} (z - \\bar{z})^{c} (z + \\bar{z})^{3}$ on upper half pl...

  1. Electronic structure of Zr-TM-Al (TM=Ni, Cu) bulk metallic glasses

    International Nuclear Information System (INIS)

    The valence-band electronic structures of Zr-TM-Al (TM=Ni, Cu) bulk metallic glasses have been investigated by means of synchrotron-radiation photoelectron spectroscopy. Their valence-band spectra show Zr 4d-, Ni 3d- and Cu 3d-derived bands at the binding energies of 0.5, 2.0 and 3.6 eV, respectively. The Zr 4d-derived band becomes prominent around the excitation photon energy hv of 40 eV. It is found that the wider the supercooled liquid region ΔTx=Tx-Tg (Tx: the crystallization temperature, Tg: the glass transition temperature), the larger the peak binding energy of the Zr 4d-derived band becomes. For the photoexcitation at hv - 18 eV, where the Zr 4d states less contribute to the spectrum, the spectral intensity reduces towards the Fermi level. This may imply the formation of a pseudogap in the sp bands. It is also found that the width of the pseudogap for the occupied states becomes wider as ΔTx is increased. These spectral findings suggest that both the strength of the chemical bonding around Zr and the reduction in the electronic energy because of the pseudogap formation and the chemical bonding contribute to the large glass formation ability of the Zr-Cu-Al metallic glasses. (author)

  2. Structural basis of control of inward rectifier Kir2 channel gating by bulk anionic phospholipids.

    Science.gov (United States)

    Lee, Sun-Joo; Ren, Feifei; Zangerl-Plessl, Eva-Maria; Heyman, Sarah; Stary-Weinzinger, Anna; Yuan, Peng; Nichols, Colin G

    2016-09-01

    Inward rectifier potassium (Kir) channel activity is controlled by plasma membrane lipids. Phosphatidylinositol-4,5-bisphosphate (PIP2) binding to a primary site is required for opening of classic inward rectifier Kir2.1 and Kir2.2 channels, but interaction of bulk anionic phospholipid (PL(-)) with a distinct second site is required for high PIP2 sensitivity. Here we show that introduction of a lipid-partitioning tryptophan at the second site (K62W) generates high PIP2 sensitivity, even in the absence of PL(-) Furthermore, high-resolution x-ray crystal structures of Kir2.2[K62W], with or without added PIP2 (2.8- and 2.0-Å resolution, respectively), reveal tight tethering of the C-terminal domain (CTD) to the transmembrane domain (TMD) in each condition. Our results suggest a refined model for phospholipid gating in which PL(-) binding at the second site pulls the CTD toward the membrane, inducing the formation of the high-affinity primary PIP2 site and explaining the positive allostery between PL(-) binding and PIP2 sensitivity. PMID:27527100

  3. Internal structure of the nanogratings generated inside bulk fused silica by ultrafast laser direct writing

    International Nuclear Information System (INIS)

    The aim of the present work was to characterize the internal structure of nanogratings generated inside bulk fused silica by ultrafast laser processing and to study the influence of diluted hydrofluoric acid etching on their structure. The nanogratings were inscribed at a depth of 100 μm within fused silica wafers by a direct writing method, using 1030 nm radiation wavelength and the following processing parameters: E = 5 μJ, τ = 560 fs, f = 10 kHz, and v = 100 μm/s. The results achieved show that the laser-affected regions are elongated ellipsoids with a typical major diameter of about 30 μm and a minor diameter of about 6 μm. The nanogratings within these regions are composed of alternating nanoplanes of damaged and undamaged material, with an average periodicity of 351 ± 21 nm. The damaged nanoplanes contain nanopores randomly dispersed in a material containing a large density of defects. These nanopores present a roughly bimodal size distribution with average dimensions for each class of pores 65 ± 20 × 16 ± 8 × 69 ± 16 nm3 and 367 ± 239 × 16 ± 8 × 360 ± 194 nm3, respectively. The number and size of the nanopores increases drastically when an hydrofluoric acid treatment is performed, leading to the coalescence of these voids into large planar discontinuities parallel to the nanoplanes. The preferential etching of the damaged material by the hydrofluoric acid solution, which is responsible for the pores growth and coalescence, confirms its high defect density

  4. Creep deformation and rupture behavior of type 304/308 stainless steel structural weldments

    Energy Technology Data Exchange (ETDEWEB)

    McAfee, W.J.; Richardson, M.; Sartory, W.K.

    1977-05-12

    The creep deformation and rupture of type 304/308 stainless steel structural weldments at 593/sup 0/C (1100/sup 0/F) was experimentally investigated to study the comparative behavior of the base metal and weld metal constituents. The tests were conducted in support of ORNL's program to develop high-temperature structural design methods applicable to liquid-metal fast breeder reactor (LMFBR) system components that operate in the creep range. The specimens used were thin-walled, right circular cylinders capped with either flat or hemispherical heads and tested under internal gas pressure. Circumferential welds were located in different regions of the cylinder or head and, with one exception, were geometrically duplicated by all base metal regions in companion specimens. Results are presented on the comparative deformation and rupture behavior of selected points in the base metal and weldment regions of the different specimens and on the overall surface strains for selected specimens.

  5. Dislocation structure and crystallite size in severely deformed copper by X-ray peak profile analysis

    International Nuclear Information System (INIS)

    Copper specimens were severely deformed by equal channel angular pressing (ECAP) up to eight passes. The microstructure was studied by X-ray diffraction peak profile analysis as a function of strain (ε). It was found that the crystallite size is reduced to a few tens of nanometers already at ε = 0.7 and it does not change significantly during further deformation. At the same time, the dislocation density increases gradually up to ε = 4. The dipole character of the dislocation structure becomes stronger with increasing strain. The thermal stability of the microstructure is examined by differential scanning calorimetry (DSC). The temperature of the DSC peak related to the recovery of the microstructure decreases with increasing strain. At the beginning of the heat release, a bimodal grain structure develops indicated by a special double-peak shape of the diffraction line profiles

  6. The effect of high energy concentration source irradiation on structure and properties of Fe-based bulk metallic glass

    Science.gov (United States)

    Pilarczyk, Wirginia

    2016-06-01

    Metallic glasses exhibit metastable structure and maintain this relatively stable amorphous state within certain temperature range. High intensity laser beam was used for the surface irradiation of Fe-Co-B-Si-Nb bulk metallic glasses. The variable parameter was laser beam pulse energy. For the analysis of structure and properties of bulk metallic glasses and their surface after laser remelting the X-ray analysis, microscopic observation and test of mechanical properties were carried out. Examination of the nanostructure of amorphous materials obtained by high pressure copper mold casting method and the irradiated with the use of TITAN 80-300 HRTEM was carried out. Nanohardness and reduced Young's modulus of particular amorphous and amorphous-crystalline material zone of the laser beam were examined with the use of Hysitron TI950 Triboindenter nanoindenter and with the use of Berkovich's indenter. The XRD and microscopic analysis showed that the test material is amorphous in its structure before irradiation. Microstructure observation with electron transmission microscopy gave information about alloy crystallization in the irradiated process. Identification of given crystal phases allows to determine the kind of crystal phases created in the first place and also further changes of phase composition of alloy. The main value of the nanohardness of the surface prepared by laser beam has the order of magnitude similar to bulk metallic glasses formed by casting process irrespective of the laser beam energy used. Research results analysis showed that the area between parent material and fusion zone is characterized by extraordinarily interesting structure which is and will be the subject of further analysis in the scope of bulk metallic glasses amorphous structure and high energy concentration source. The main goal of this work is the results' presentation of structure and chosen properties of the selected bulk metallic glasses after casting process and after irradiation

  7. A review of undulated sediment features on Mediterranean prodeltas: distinguishing sediment transport structures from sediment deformation

    OpenAIRE

    Urgeles, Roger; Cattaneo, Antonio; PUIG Pere; Liquete, Camino; Mol, Ben; Amblas, David; Sultan, Nabil; Trincardi, Fabio

    2011-01-01

    Most Mediterranean prodeltas show undulated sediment features on the foresets of their Holocene wedges. These features have been described all along the Mediterranean for the last 30 years and interpreted as either soft sediment deformation and incipient landsliding, and more recently, as sediment transport structures. We perform a review and detailed analysis of these undulated sediment features using ultrahigh-resolution seismic and bathymetric data as well as geotechnical information and h...

  8. The Difference of Structural State and Deformation Behavior between Teenage and Mature Human Dentin

    OpenAIRE

    Peter Panfilov; Dmitry Zaytsev; Antonova, Olga V.; Victoria Alpatova; Kiselnikova, Larissa P.

    2016-01-01

    Objective. The cause of considerable elasticity and plasticity of human dentin is discussed in the relationship with its microstructure. Methods. Structural state of teenage and mature human dentin is examined by using XRD and TEM techniques, and their deformation behavior under compression is studied as well. Result. XRD study has shown that crystallographic type of calcium hydroxyapatite in human dentin (calcium hydrogen phosphate hydroxide Ca9HPO4(PO4)5OH; Space Group P63/m (176); a = 9,44...

  9. Plastic deformation modelling of tempered martensite steel block structure by a nonlocal crystal plasticity model

    OpenAIRE

    Martin Boeff; Anxin Ma; Alexander Hartmaier

    2014-01-01

    The plastic deformations of tempered martensite steel representative volume elements with different martensite block structures have been investigated by using a nonlocal crystal plasticity model which considers isotropic and kinematic hardening produced by plastic strain gradients. It was found that pronounced strain gradients occur in the grain boundary region even under homogeneous loading. The isotropic hardening of strain gradients strongly influences the global stress–strain diagram whi...

  10. Shear-deforming textile reinforced concrete for the construction of double-curved structures

    OpenAIRE

    Woodington, W.; Bergsma, O.K.; Schipper, H.R.

    2015-01-01

    A composite textile reinforced concrete (TRC) material is developed to overcome the difficulties of constructing double-curved freeform structures. This is possible by shear-deformation of the woven reinforcement. It affects the direction of reinforcement and thickness, resulting in variable orthotropic properties over the surface. The research translated the properties of aerospace materials to the scale and limitations of building construction materials. To accomplish this, knowledge about ...

  11. Low-dimensional structures generated by misfit dislocations in the bulk of Si1 - xGex/Si heteroepitaxial systems

    DEFF Research Database (Denmark)

    Shiryaev, Sergey Y.; Jensen, Flemming; Petersen, Jon Wulff;

    1997-01-01

    The capability of misfit dislocations to generate nanostructures in the bulk of Si1-xGex/Si heteroepitaxial systems is demonstrated. It is shown that dislocation slip originating from compositionally graded Si1-xGex layers can produce a range of low-dimensional structures including nanowires...

  12. X-ray microtomography analysis of soil structure deformation caused by centrifugation

    Science.gov (United States)

    Schlüter, S.; Leuther, F.; Vogler, S.; Vogel, H.-J.

    2016-01-01

    Centrifugation provides a fast method to measure soil water retention curves over a wide moisture range. However, deformation of soil structure may occur at high angular velocities in the centrifuge. The objective of this study was to capture these changes in soil structure with X-ray microtomography and to measure local deformations via digital volume correlation. Two samples were investigated that differ in texture and rock content. A detailed analysis of the pore space reveals an interplay between shrinkage due to drying and soil compaction due to compression. Macroporosity increases at moderate angular velocity because of crack formation due to moisture release. At higher angular velocities, corresponding to capillary pressure of ψ centrifugation method. A new protocol for digital volume correlation was developed to analyze the spatial heterogeneity of deformation. In both samples the displacement of soil constituents is highest in the top part of the sample and exhibits high lateral variability explained by the spatial distribution of macropores in the sample. Centrifugation should therefore only be applied after the completion of all other hydraulic or thermal experiments, or any other analysis that depends on the integrity of soil structure.

  13. Analysis of Structure and Deformation Mechanisms of Mineral Wool Slabs under Compression

    Directory of Open Access Journals (Sweden)

    Laimutis STEPONAITIS

    2012-06-01

    Full Text Available The products of mineral wool are widely used for thermal insulation of buildings, both at construction of new buildings and at renovation of old ones. The mechanical resistance and stability of them, as well as their energy saving and heat saving requirements are in most cases related to the essential specifications of the building. The mechanical characteristics of these products are subject to structure of material, density, content of binder in the product and to technology of production. Subject to the latter, mineral wool products with different fibrous structure are received, therefore, for the structure of each type, the individual structural models are developed attempting to describe the properties of fibrous systems. The deformability of mineral wool products is conditioned by mobility of fibrous structure, which shows up best under compression by short term loads. This study established the impact of various thicknesses and deformations on changes in structure of rock wool products. It also established that the thickness of mineral wool products conditions and influences considerable changes in their structure.DOI: http://dx.doi.org/10.5755/j01.ms.18.2.1926

  14. Ordered Nanopillar Structured Electrodes for Depleted Bulk Heterojunction Colloidal Quantum Dot Solar Cells

    KAUST Repository

    Kramer, Illan J.

    2012-03-30

    A bulk heterojunction of ordered titania nanopillars and PbS colloidal quantum dots is developed. By using a pre-patterned template, an ordered titania nanopillar matrix with nearest neighbours 275 nm apart and height of 300 nm is fabricated and subsequently filled in with PbS colloidal quantum dots to form an ordered depleted bulk heterojunction exhibiting power conversion efficiency of 5.6%. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. CFD simulations of flow erosion and flow-induced deformation of needle valve: Effects of operation, structure and fluid parameters

    International Nuclear Information System (INIS)

    Highlights: • A combined FSI–CFD and DPM computational method is used to investigate flow erosion and deformation of needle valve. • The numerical model is validated with the comparison of measured and predicted erosion rate. • Effects of operation, structure and fluid parameters on flow erosion and flow-induced deformation are discussed. • Particle diameter has the most significant effect on flow erosion. • Inlet rate has the most obvious effect on flow-induced deformation. - Abstract: A three-dimensional fluid–structure interaction (FSI) computational model coupling with a combined continuum and discrete model has been used to predict the flow erosion rate and flow-induced deformation of needle valve. Comparisons with measured data demonstrate good agreement with the predictions of erosion rate. The flow field distribution of gas-particle flow and the erosion rate and deformation of valve core are captured under different operating and structural conditions with different fluid parameters. The effects of inlet velocity, valve opening and inlet valve channel size, particle concentration, particle diameter and particle phase components are discussed in detail. The results indicate that valve tip has the most severe erosion and deformation, and flow field, erosion rate and deformation of valve are all sensitive to inlet condition changes, structural changes and fluid properties changes. The effect of particle diameter on erosion is the most significant, while the influence of inlet rate on deformation is the greatest one

  16. Direct investigations of deformation and yield induced structure transitions in polyamide 6 below glass transition temperature with WAXS and SAXS

    DEFF Research Database (Denmark)

    Guo, Huilong; Wang, Jiayi; Zhou, Chengbo;

    2015-01-01

    Deformation and yield induced structure transitions of polyamide 6 (PA6) were detected with the combination of the wide- and small-angle X-ray scattering (WAXS and SAXS) at 30 degrees C below glass transition temperature (T-g) of PA6. During deformation, gamma-alpha phase transition was found at ...

  17. Structural inheritance and selective reactivation in the central Andes: Cenozoic deformation guided by pre-Andean structures in southern Peru

    Science.gov (United States)

    Perez, Nicholas D.; Horton, Brian K.; Carlotto, Victor

    2016-03-01

    Structural, stratigraphic, and geochronologic constraints from the Eastern Cordillera in the central Andean plateau of southern Peru (14-15°S) demonstrate the existence and position of major pre-Andean structures that controlled the accumulation of Triassic synrift fill and guided subsequent Cenozoic deformation. The timing of initial clastic deposition of the Triassic Mitu Group is here constrained to ~ 242-233 Ma on the basis of detrital and volcanic zircon U-Pb geochronology. Regionally distinct provenance variations, as provided by U-Pb age populations from localized synrift accumulations, demonstrate Triassic erosion of multiple diagnostic sources from diverse rift-flank uplifts. Stratigraphic correlations suggest synchronous initiation of extensional basins containing the Mitu Group, in contrast with previous interpretations of southward rift propagation. Triassic motion along the NE-dipping San Anton normal fault accommodated up to 7 km of throw and hanging-wall deposition of a synrift Mitu succession > 2.5 km thick. The contrasting orientation of a non-reactivated Triassic normal fault suggests selective inversion of individual structures in the Eastern Cordillera was dependent on fault dip and strike. Selective preservation of a ~ 4 km thick succession of Carboniferous-Permian strata in the down-dropped San Anton hanging wall, beneath the synrift Mitu Group, suggests large-scale erosional removal in the uplifted footwall. Field and map observations identify additional pre-Andean thrust faults and folds attributed to poorly understood Paleozoic orogenic events preserved in the San Anton hanging wall. Selective thrust reactivation of normal and reverse faults during later compression largely guided Cenozoic deformation in the Eastern Cordillera. The resulting structural compartmentalization and across-strike variations in kinematics and deformation style highlight the influence of inherited Paleozoic structures and Triassic normal faults on the long

  18. Structure and magnetic properties of Fe36Co36B19Si5Nb4 bulk metallic glasses

    Directory of Open Access Journals (Sweden)

    R. Nowosielski

    2008-10-01

    Full Text Available Purpose: The work presents a microstructure characterization, thermal stability and soft magnetic properties analysis of Fe-based bulk metallic glasses.Design/methodology/approach: The studies were performed on bulk amorphous ribbons and rods. The amorphous structure of tested materials was examined by X-ray diffraction (XRD and transmission electron microscopy (TEM methods. The thermal properties associated with crystallization temperature of the glassy samples were measured using differential thermal analysis (DTA and differential scanning calorimetry (DSC. The magnetic properties were determined by the Maxwell-Wien bridge and VSM methods.Findings: The X-ray diffraction and transmission electron microscopy investigations have revealed that the studied as-cast bulk metallic glasses were amorphous. Based from the XRD analysis and TEM investigations of the Fe36Co36B19Si5Nb4 rod samples, it was believed that the tested alloy can be fabricated into a bulk glassy rod with the diameter of up to 4 mm. A two stage crystallization process was observed for studied bulk amorphous alloy. The changes of Curie temperatures, crystallization temperatures and magnetic properties as a function of glassy ribbons thickness (time of solidification were stated. The investigated magnetic properties allow to classify the studied metallic glasses as soft magnetic materials.Practical implications: The studied bulk metallic glasses are suitable materials for many electrical application in different elements of magnetic circuits and for manufacturing of sensors and precise current transformers.Originality/value: The obtained examination results confirm the utility of applied investigation methods in the microstructure, thermal and soft magnetic properties analysis of examined bulk amorphous alloys.

  19. 3D EBSD characterization of deformation structures in commercial purity aluminum

    International Nuclear Information System (INIS)

    A method to map the microstructure in deformed aluminum in three dimensions is presented. The method employs serial sectioning by mechanical polishing, and electropolishing to obtain a good surface quality, and orientation mapping of individual grains in each section by electron backscattered diffraction. Techniques to carefully align the sample and to accurately measure the thickness of the material removed in each serial section are described. A new method for stacking the two dimensional maps together to produce a three dimensional visualization of the microstructure is presented. The data are analyzed in terms of the deformation-induced orientation spread within each grain. In particular the advantage of using three dimensional data, as opposed to two dimensional data, is illustrated, by inclusion of information about the three dimensional morphology of a grain and its neighbors. - Research Highlights: The deformation structures in commercial purity aluminum were characterized in 3D. The method employs serial sectioning by mechanical polishing, and electropolishing to obtain a good surface quality, and orientation mapping of individual grains in each section by electron backscattered diffraction. Techniques to carefully align the sample and to accurately measure the thickness of the material removed in each serial section are described. A new method for stacking the two dimensional maps together to produce a three dimensional visualization of the microstructure is presented. The data are analyzed in terms of the deformation-induced orientation spread within each grain. In particular the advantage of using three dimensional data, as opposed to two dimensional data, is illustrated, by inclusion of information about the three dimensional morphology of a grain and its neighbors. The highlights of the paper include: → a method to obtain 3D EBSD data over a large volume → a modified method for section alignment based on characteristics of deformed grains

  20. 3D EBSD characterization of deformation structures in commercial purity aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Lin, F.X., E-mail: lnfe@risoe.dtu.dk [Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Danish-Chinese Center for Nanometals, Materials Research Division, Riso National Laboratory for Sustainable Energy, Technical University of Denmark, DK-4000 Roskilde (Denmark); Godfrey, A. [Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Jensen, D. Juul; Winther, G. [Danish-Chinese Center for Nanometals, Materials Research Division, Riso National Laboratory for Sustainable Energy, Technical University of Denmark, DK-4000 Roskilde (Denmark)

    2010-11-15

    A method to map the microstructure in deformed aluminum in three dimensions is presented. The method employs serial sectioning by mechanical polishing, and electropolishing to obtain a good surface quality, and orientation mapping of individual grains in each section by electron backscattered diffraction. Techniques to carefully align the sample and to accurately measure the thickness of the material removed in each serial section are described. A new method for stacking the two dimensional maps together to produce a three dimensional visualization of the microstructure is presented. The data are analyzed in terms of the deformation-induced orientation spread within each grain. In particular the advantage of using three dimensional data, as opposed to two dimensional data, is illustrated, by inclusion of information about the three dimensional morphology of a grain and its neighbors. - Research Highlights: The deformation structures in commercial purity aluminum were characterized in 3D. The method employs serial sectioning by mechanical polishing, and electropolishing to obtain a good surface quality, and orientation mapping of individual grains in each section by electron backscattered diffraction. Techniques to carefully align the sample and to accurately measure the thickness of the material removed in each serial section are described. A new method for stacking the two dimensional maps together to produce a three dimensional visualization of the microstructure is presented. The data are analyzed in terms of the deformation-induced orientation spread within each grain. In particular the advantage of using three dimensional data, as opposed to two dimensional data, is illustrated, by inclusion of information about the three dimensional morphology of a grain and its neighbors. The highlights of the paper include: {yields} a method to obtain 3D EBSD data over a large volume {yields} a modified method for section alignment based on characteristics of deformed

  1. Engineering the propagation of high-k bulk plasmonic waves in multilayer hyperbolic metamaterials by multiscale structuring

    DEFF Research Database (Denmark)

    Zhukovsky, Sergei; Lavrinenko, Andrei; Sipe, J. E.

    2013-01-01

    Propagation of large-wavevector bulk plasmonic waves in multilayer hyperbolic metamaterials (HMMs) with two levels of structuring is theoretically studied. It is shown that when the parameters of a subwavelength metal-dielectric multilayer (substructure) are modulated (superstructured) on a larger......, wavelength scale, the propagation of bulk plasmon polaritons in the resulting multiscale HMM is subject to photonic band gap phenomena. A great degree of control over such plasmons can be exerted by varying the superstructure geometry. As an example, Bragg reflection and Fabry-Pérot resonances are...... promising platform for using high-k bulk plasmonic waves as a new kind of information carriers, which can be used in far-field subwavelength imaging and plasmonic communication....

  2. Influence of Bulk Elasticity and Interfacial Tension on the Deformation of Gelled Water-in-Oil Emulsion Droplets: An AFM Study

    NARCIS (Netherlands)

    Filip, D.; Uricanu, V.I.; Duits, M.H.G.; Agterof, W.G.M.; Mellema, J.

    2005-01-01

    We used atomic force microscopy (AFM) to study the deformation and wetting behavior of large (50-250 m) emulsion droplets upon mechanical loading with a colloidal glass probe. Our droplets were obtained from water-in-oil emulsions. By adding gelatin to the water prior to emulsification, also droplet

  3. Combination of metamorphism and deformation affect the nano-scale pore structures and macromolecule characteristics of high-rank deformed coals

    Science.gov (United States)

    Zhang, W.; Li, H.; Ju, Y.

    2013-12-01

    Coal constitutes a large proportion of total energy supply in the world. Coalbed Methane (CBM) composes the greenhouse gases, which has attracted more and more scientists' concern and attention. The adsorption/desorption characteristics and mechanism of CBM on high-rank deformed coals are in favor of enhancing gas recovery, reducing coal mining accidents and carbon emission. Although the influence factors of CBM adsorption/desorption on different coals have been intensively studied, the combined action of metamorphism and deformation on high-rank coals have been rarely researched. Nevertheless. Metamorphism and deformation are the most fundamental driving forces that cause the changes of inner structures and compositions in coal strata, and then alter the adsorption/desorption capacities of CBM on different coalbeds. South of Qinshui Basin in Shanxi province developed with abundant high-rank coals is the first demonstrate area of CBM development in China. Meanwhile Southwest of Fujian province represents high metamorphic-deformed coals region due to the intense volcanic activities. Therefore samples were taken in both areas to elaborate the adsorption/desorption characteristics and mechanism of CBM. Based on hand specimens description, coal macerals testing, proximate analysis, ultimate analysis and vitrinite reflectance testing, the physical properties and composition characteristics of high-rank deformed coals have been studied. Combined with liquid nitrogen adsorption experiments, Transmission Electron Microscopy (TEM) observation, Fourier Transform Infrared Spectrometry (FTIR) and Nuclear Magnetic Resonance (NMR) experiments, the results show that nano-pores increase and become homogenization with metamorphic-deformation enhancement, stacking of the macromolecular basic structural units (BSU) enhances, aromatic compound increases while aliphatic chain compound and oxygen-containing function groups decrease. Comparing to coal adsorption/desorption isotherm

  4. Multi-trace deformations in AdS/CFT. Exploring the vacuum structure of the deformed CFT

    Energy Technology Data Exchange (ETDEWEB)

    Papadimitriou, I. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[Center for Mathematical Physics, Hamburg (Germany)

    2007-03-15

    We present a general and systematic treatment of multi-trace deformations in the AdS/CFT correspondence in the large N limit, pointing out and clarifying subtleties relating to the formulation of the boundary value problem on a conformal boundary. We then apply this method to study multi-trace deformations in the presence of a scalar VEV, which requires the coupling to gravity to be taken into account. We show that supergravity solutions subject to 'mixed' boundary conditions are in one-to-one correspondence with critical points of the holographic effective action of the dual theory in the presence of a multi-trace deformation, and we find a number of new exact analytic solutions involving a minimally or conformally coupled scalar field satisfying 'mixed' boundary conditions. These include the generalization to any dimension of the instanton solution recently found in hep-th/0611315. Finally, we provide a systematic method for computing the holographic effective action in the presence of a multi-trace deformation in a derivative expansion away from the conformal vacuum using Hamilton-Jacobi theory. Requiring that this effective action exists and is bounded from below reproduces recent results on the stability of the AdS vacuum in the presence of 'mixed' boundary conditions. (orig.)

  5. Multi-trace deformations in AdS/CFT. Exploring the vacuum structure of the deformed CFT

    International Nuclear Information System (INIS)

    We present a general and systematic treatment of multi-trace deformations in the AdS/CFT correspondence in the large N limit, pointing out and clarifying subtleties relating to the formulation of the boundary value problem on a conformal boundary. We then apply this method to study multi-trace deformations in the presence of a scalar VEV, which requires the coupling to gravity to be taken into account. We show that supergravity solutions subject to 'mixed' boundary conditions are in one-to-one correspondence with critical points of the holographic effective action of the dual theory in the presence of a multi-trace deformation, and we find a number of new exact analytic solutions involving a minimally or conformally coupled scalar field satisfying 'mixed' boundary conditions. These include the generalization to any dimension of the instanton solution recently found in hep-th/0611315. Finally, we provide a systematic method for computing the holographic effective action in the presence of a multi-trace deformation in a derivative expansion away from the conformal vacuum using Hamilton-Jacobi theory. Requiring that this effective action exists and is bounded from below reproduces recent results on the stability of the AdS vacuum in the presence of 'mixed' boundary conditions. (orig.)

  6. Low energy dislocation structures due to unidirectional deformation at low temperatures

    DEFF Research Database (Denmark)

    Hansen, Niels; Kuhlmann-Wilsdorf, D.

    1986-01-01

    are considered in this paper: (i) the sum of the energy stored in the dislocation line energy and the longer-range stresses is significantly smaller than some recently reported experimental values; (ii) subdivision of cells is discussed on the basis of observations in rolled aluminum showing a...... “hierarchical” cell structure; (iii) suggestions are made to account for microband formation on the basis of energy minimization. Finally, the relationship between surface markings and the underlying dislocation structure is discussed and related to slip processes taking place during uniaxial deformation....

  7. A solid-shell Cosserat point element ( SSCPE) for elastic thin structures at finite deformation

    Science.gov (United States)

    Jabareen, Mahmood; Mtanes, Eli

    2016-07-01

    The objective of this study is to develop a new solid-shell element using the Cosserat point theory for modeling thin elastic structures at finite deformations. The point-wise Green-Lagrange strain tensor is additively decomposed into homogeneous and inhomogeneous parts. Only the latter part of the strain tensor is modified by the assumed natural strain ANS concept to avoid both curvature-thickness locking and transverse shear locking. To the authors' knowledge, such modification has not been applied yet in the literature, and here it is referred to as the assumed natural inhomogeneous strain ANIS concept. Moreover, a new methodology for determining the constitutive coefficients of the strain energy function, which controls the inhomogeneous deformations, is proposed. The resulting coefficients ensure both accuracy, robustness, and elimination of all locking pathologies in the solid-shell Cosserat point element ( SSCPE). The performance of the developed SSCPE is verified and tested via various benchmark problems and compared to other solid, shell, and solid-shell elements. These examples demonstrate that the SSCPE is accurate, robust, stable, free of locking, and can be used for modeling thin structures at both small and finite deformations.

  8. A solid-shell Cosserat point element (SSCPE) for elastic thin structures at finite deformation

    Science.gov (United States)

    Jabareen, Mahmood; Mtanes, Eli

    2016-04-01

    The objective of this study is to develop a new solid-shell element using the Cosserat point theory for modeling thin elastic structures at finite deformations. The point-wise Green-Lagrange strain tensor is additively decomposed into homogeneous and inhomogeneous parts. Only the latter part of the strain tensor is modified by the assumed natural strain ANS concept to avoid both curvature-thickness locking and transverse shear locking. To the authors' knowledge, such modification has not been applied yet in the literature, and here it is referred to as the assumed natural inhomogeneous strain ANIS concept. Moreover, a new methodology for determining the constitutive coefficients of the strain energy function, which controls the inhomogeneous deformations, is proposed. The resulting coefficients ensure both accuracy, robustness, and elimination of all locking pathologies in the solid-shell Cosserat point element (SSCPE). The performance of the developed SSCPE is verified and tested via various benchmark problems and compared to other solid, shell, and solid-shell elements. These examples demonstrate that the SSCPE is accurate, robust, stable, free of locking, and can be used for modeling thin structures at both small and finite deformations.

  9. Optimal design and optimal control of structures undergoing finite rotations and elastic deformations

    CERN Document Server

    Ibrahimbegović, A; Kučerová, A; Villon, P; 10.1002/nme.1150

    2009-01-01

    In this work we deal with the optimal design and optimal control of structures undergoing large rotations. In other words, we show how to find the corresponding initial configuration and the corresponding set of multiple load parameters in order to recover a desired deformed configuration or some desirable features of the deformed configuration as specified more precisely by the objective or cost function. The model problem chosen to illustrate the proposed optimal design and optimal control methodologies is the one of geometrically exact beam. First, we present a non-standard formulation of the optimal design and optimal control problems, relying on the method of Lagrange multipliers in order to make the mechanics state variables independent from either design or control variables and thus provide the most general basis for developing the best possible solution procedure. Two different solution procedures are then explored, one based on the diffuse approximation of response function and gradient method and t...

  10. Subsurface tectonic structure and crustal deformation at Kalabsha fault, Aswan-Egypt

    International Nuclear Information System (INIS)

    Complete text of publication follows. Aswan region became tectonically interesting especially after the occurrence of the 14 November 1981 earthquake (M= 5.4), which occurred near Aswan reservoir. The seismically active area in Aswan is located beneath Kalabsha fault zone. Several study programs were performed in that area. Detailed land magnetic survey was carried out in selected profiles at the active part of Kalabsha fault. The analysis of the magnetic data is imaging the fault plane where the basement rocks are shallow. The crustal deformation round the active part of Kalabsha fault has been examined, using the seismological and GPS network during the period (1997 - 2007). These observations are important, based on studying the subsurface structures and tectonic elements around the northwestern part of the reservoir. The results from data sets (magnetic, seismic and GPS) are compared and combined in order to determine the main characteristics of the deformation and hazard estimation for the specified area in Aswan.

  11. First-principles study of electronic structure of deformed carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Kazuchika Iwami, Hidekazu Goto, Kikuji Hirose and Tomoya Ono

    2007-01-01

    Full Text Available On the basis of density functional theory, we study the electronic structures of five types of carbon nanotubes: the non-deformed (6,6 tube, the uniformly stretched tube along the tube axis, the uniformly compressed tube, the partially stretched tube and the partially compressed tube. The electron charge density increases at the compressed C–C bond of the partially stretched tube, while the density decreases at the stretched C–C bond of the partially stretched tube. In addition, the a1 and e1 states of the (6,6 tube contribute to the bonding along the tube axis and the a2 and e2 states are the bonds connecting the atoms in the same layers. Thus, the energy bands of the a1 and e1 states are sensitively affected by the deformation of the tubes along the tube axis.

  12. Dislocation structure evolution and its effects on cyclic deformation response of AISI 316L stainless steel

    International Nuclear Information System (INIS)

    Research highlights: → The cyclic deformation response of AISI 316L steel is investigated at 20 deg. C. → The corresponding microstructure evolution is characterised by electron microscopy. → A 3D representation of dislocation evolution is proposed based on the observation. → The 3D representation gives a good explanation of the microstructure complexity. → The cyclic deformation response is discussed based on the microstructure evolution. - Abstract: The cyclic deformation response of an austenitic stainless steel is characterised in terms of its cyclic peak tensile stress properties by three stages of behaviour: a hardening stage followed by a softening stage, and finally a stable stress response stage. A series of tests have been performed and interrupted at selected numbers of cycles in the different stages of mechanical response. At each interruption point, specimens have been examined by transmission electron microscopy (TEM) with different beam directions by means of the tilting function in order to investigate the formation and the development of dislocation structures from the as-received condition until the end of fatigue life. A new 3D representation of dislocation structure evolution during cyclic loading is proposed on the basis of the microstructural observations. The 3D representation provides a deeper insight into the development of dislocation structures in AISI 316L during low cycle fatigue loading at room temperature. By investigating the dislocation evolution, the study shows that the hardening response is mainly associated with an increase of total dislocation density, whereas the softening stage is a result of the formation of dislocation-free regions. Further development of the dislocation structure into a cellular structure is responsible for the stable stress response stage.

  13. Deformation analysis of a film-overlapped micro-pump membrane structure

    International Nuclear Information System (INIS)

    A novel approach is developed to study a film-overlapped membrane structure. Meanwhile, the established model is employed to design the micro-pump membrane structure and to evaluate its pumping efficiency. Two-dimensional coupling effects between the overlapping actuator films and the deformable membrane are thoroughly investigated, including the influences on the membrane from the overlapping films' elongation effects, Poisson's ratio effects and shear strain effects. Overall deformations and interactions for the three-layer membrane structures are accurately calculated through exercising the developed model, in contrast to what difficulties are usually encountered in carrying out FEM methods with very thin elements meshed for the actuator films. Furthermore, this study demonstrates that the high stiffness of the actuating metal films needs to be reflected in the equivalent stiffness of the membrane structures, especially when the sizes of the actuator films become compatible with the sizes of the membranes. Hence, the optimal micro-pumping efficiency of a membrane structure is acquired upon exercising the developed model, and larger sizes of the actuating films do not definitely obtain larger pumping efficiencies for the electromagnetically actuated micro-pumps

  14. Car Side Structure Crashworthiness in Pole and Moving Deformable Barrier Side Impacts

    Institute of Scientific and Technical Information of China (English)

    WANG Dazhi; DONG Guang; ZHANG Jinhuan; HUANG Shilin

    2006-01-01

    To clearly understand passenger car structure's crashworthiness in typical side impacts of pole and moving deformable barrier (MDB) impact modes, which could assist the establishment of Chinese vehicle side impact safety regulations, a full midsized car finite element model, calibrated by pole side impact test, was built and the pole side impact according to European New Car Assessment Program (EuroNCAP) and the MDB side impact according to ECE R95 regulations were simulated with LS-DYNA. The accelerations and the structure deformations from simulations were compared. It can be concluded that the pole side impact focuses primarily on side structure crashworthiness as a result of large intrusions, while the MDB side impact focuses primarily on full side structure crashworthiness. Accordingly, occupant protection strategies focus on different aspects to improve side impact safety. In the pole side impact the objective is to maintain the passenger compartment and protect the passenger's head from impacting the pole, while in the MDB side impact the objective is to protect the full human body. In the design of the car side structures, at least these two tests should be considered for assessing their side impact crashworthiness. Conducting these two side impact tests as certified tests provides insights into car safety during side impacts.

  15. Structure and deformation of the External Hellenides based on seismic data from offshore western Greece

    Energy Technology Data Exchange (ETDEWEB)

    Kamberis, E.; Marnelis, F.; Loucoyannakis, M. [Public Petroleum Corp. (Exploration and Exploitation of Hydrocarbons (S.A.), Athens (Greece)) (and others)

    1996-12-31

    A deep seismic reflection line of a total length of 180 km was recorded across the western margin of the Hellenic Arc during the STREAMERS acquisition campaign. The eastern part of this line is used, together with selected conventional seismic and geological data, to demonstrate the structural evolution of the folded belt of the outer Hellenides. Easterly dipping thrust faults and elongated anticlines were formed during the Lower Miocene, Lower Pliocene, and at the Pliocene-Quaternary boundary by compressional deformations. In some of these N-S trending structures, which extent from a few to several tens of kilometres, diapiric movements of Triassic evaporites have occurred since the Pliocene, forming narrow structures. Thrust faults have roots in the Triassic evaporitic layer which corresponds to a reflector at 6-7 km depth, and is interpreted as the ``decollement surface`` of the folded belt within the Triassic layer. Two alternative interpretations are proposed for the structural evolution of the External Hellenides in the area. In the first hypothesis the Ionian Zone is thrust over the Pre-Apulian Zone and the sedimentary cover in this case is 10-12 km thick. In the second case, the displacement of the structural units is not so important and the basement is considered to be involved in the deformation. (Author)

  16. Anti-deformed Polyacrylonitrile/Polysulfone Composite Membrane with Binary Structures for Effective Air Filtration.

    Science.gov (United States)

    Zhang, Shichao; Liu, Hui; Yin, Xia; Yu, Jianyong; Ding, Bin

    2016-03-01

    Airborne particle filtration proposed for fibers requires their assembly into porous structures with small pore size and low packing density. The ability to maintain structural stability upon deformation stress in service is essential to ensure a highly porous packing material that functions reliably; however, it has proven extremely challenging. Here, we report a strategy to create anti-deformed poly(ethylene oxide)@polyacrylonitrile/polysulfone (PEO@PAN/PSU) composite membranes with binary structures for effective air filtration by combining multijet electrospinning and physical bonding process. Our approach allows the ambigenous fiber framework including thin PAN nanofibers and fluffy PSU microfibers, through which run interpenetrating PEO bonding structures, to assemble into stable filtration medium with tunable pore size and packing density by facilely optimizing the bimodal fiber construction and benefiting from the PEO inspiration. With the integrated features of small pore size, high porosity, and robust mechanical properties (8.2 MPa), the resultant composite membrane exhibits high filtration efficiency of 99.992%, low pressure drop of 95 Pa, and desirable quality factor of 0.1 Pa(-1); more significantly, it successfully gets rid of the potential safety hazards caused by unexpected structural collapsing under service stress. The synthesis of PEO@PAN/PSU medium would not only make it a promising candidate for PM2.5 governance but also provide a versatile strategy to design and develop stable porous membranes for various applications. PMID:26958995

  17. Effect of a solid/liquid interface on bulk solution structures under flow

    International Nuclear Information System (INIS)

    It has been known for some time that a shear field can impart enough energy to a liquid system for it to exhibit a phase change. Not as well appreciated is the fact that non Newtonian solutions can be driven into a quasi phase separation due to the vastly different shear rates between the bulk and near surface regions. Using a variety of scattering techniques the authors have probed the interfacial and near surface region of a system of wormlike colloidal particles under flow separately from the bulk. They find that the hexagonal phase which forms under flow near the surface, does not persist into the bulk. They also present data showing substantial differences in the kinetics of alignment and relaxation of the two phases

  18. Deformation Structures associated with the emplacement of high level intrusions: A study of Trachyte Mesa Intrusion, Henry Mountains, Utah

    Science.gov (United States)

    Wilson, P. I. R.; McCaffrey, K. J. W.; Jarvis, I.; Murphy, P.; Davidson, J. P.

    2012-04-01

    Most studies of sill and laccolith complexes have focused on the internal architecture and thermal effects of these intrusions, while few have looked in detail at host rock deformation structures associated with their emplacement. Various sill and laccolith emplacement mechanisms have been proposed (e.g. radial growth/ bulldozing, and two-stage growth), each with their own distinct deformation style. Compressional structures likely dominate during radial growth (bulldozing) emplacement, while extensional structures are more likely to form during two-stage growth emplacement. In this study we focus on deformation structures (faults, deformation bands and joints) associated with emplacement of Tertiary sills and laccolith intrusions in the Henry Mountains, Utah. Trachyte Mesa, the most distal satellite intrusion to the Mt. Hilliers intrusive centre, is an elongate (NE-SW) laccolith concordant with the Entrada sandstone it intrudes. The intrusion is comprised of multiple, stacked intrusive sheets. Two structural transects across the northwest lateral margin have identified distinct structural domains within the host rock that reflect both temporal and kinematic variations in deformation. Three deformation phases are identified, interpreted to be pre-, syn- and late-emplacement structures. A background set of deformation bands (phase 1), trending oblique to the intrusion margin, is apparent across the entire area. A second set of deformation bands (phase 2) overprint the early phase. These are characterised by conjugate deformation bands that parallel the intrusion margin, and increase in intensity and spacing towards the intrusion. Within this same zone a series of calcite filled normal faults, striking parallel and perpendicular to the intrusion margin, are apparent. Due to their spatial, kinematic and overprinting relationships we interpret these to be linked to the emplacement of the intrusive body. Overprinting all other structures, are two sets of tensile joints

  19. PSP SAR interferometry monitoring of ground and structure deformations in the archeological site of Pompeii

    Science.gov (United States)

    Costantini, Mario; Francioni, Elena; Paglia, Luca; Minati, Federico; Margottini, Claudio; Spizzichino, Daniele; Trigila, Alessandro; Iadanza, Carla; De Nigris, Bruno

    2016-04-01

    The "Major Project Pompeii" (MPP) is a great collective commitment of different institututions and people to set about solving the serious problem of conservation of the largest archeological sites in the world. The ancient city of Pompeii with its 66 hectares, 44 of which are excaveted, is divided into 9 regiones (district), subdivided in 118 insulae (blocks) and almost 1500 domus (houses), and is Unesco site since 1996. The Italian Ministry for Heritage and Cultural Activities and Tourism (MiBACT) and Finmeccanica Group have sealed an agreement whereby the Finmeccanica Group will donate innovative technologies and services for monitoring and protecting the archaeological site of Pompeii. Moreover, the Italian Institute for Environment Protection and Research (ISPRA) - Geological Survey of Italy, was also involved to support the ground based analysis and interpretation of the measurements provided by the industrial team, in order to promote an interdisciplinary approach. In this work, we will focus on ground deformation measurements obtained by satellite SAR interferometry and on their interpretation. The satellite monitoring service is based on the processing of COSMO-SkyMed Himage data by the e-Geos proprietary Persistent Scatterer Pair (PSP) SAR interferometry technology. The PSP technique is a proven SAR interferometry method characterized by the fact of exploiting in the processing only the relative properties between close points (pairs) in order to overcome atmospheric artifacts (which are one of the main problems of SAR interferometry). Validations analyses showed that this technique applied to COSMO-SkyMed Himage data is able to retrieve very dense (except of course on vegetated or cultivated areas) millimetric deformation measurements with sub-metric localization. By means of the COSMO-SkyMed PSP SAR interferometry processing, a historical analysis of the ground and structure deformations occurred over the entire archaeological site of Pompeii in the

  20. Earthquake-related soft-sediment deformation structures in Palaeogene on the continental shelf of the East China Sea

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Earthquake,as disastrous events in geological history,can be recorded as soft-sediment deformation.In the Palaeogene of the East China Sea shelf,the soft-sediment deformation related to earthquake event is recognized as seismic micro-fractures,micro-corrugated laminations,liquefied veins,'vibrated liquefied layers',deformed cross laminations and convolute laminations,load structures,flame structures,brecciation,slump structures and seismodisconformity.There exists a lateral continuum,the wide spatial distribution and the local vertical continuous sequences of seismites including slump,liquefaction and brecciation.In the Palaeogene of East China Sea shelf,where typical soft-sediment deformation structures were developed,clastic deposits of tidal-flat,delta and river facies are the main background deposits of Middle-Upper Eocene Pinghu Formation and Oligocene Huagang Formation.This succession also records diagnostic marks of event deposits and basinal tectonic activities in the form of seismites.

  1. Deformation of the Nankai Trough inner accretionary prism: The role of inherited structures

    Science.gov (United States)

    Boston, Brian; Moore, Gregory F.; Jurado, María. José; Sone, Hiroki

    2016-02-01

    Accretionary prisms commonly grow seaward, with the strata of the inner prism consisting of older, previously accreted outer prism rocks overlain by thick fore-arc basin strata. We focus on the Nankai Trough inner accretionary prism using three-dimensional (3-D) seismic data and logging data from the Integrated Ocean Drilling Program (IODP). We update the 3-D seismic volume using well velocity data to better constrain deeper horizons. Interpretation of these horizons reveals multiple folds with axial surfaces that strike near parallel to modern outer prism thrust faults, and we interpret that these folds formed as a result of thrust faulting. Reactivation of one inner prism thrust fault continued until at least ˜0.44 Ma, after the modern fore-arc basin formed, indicating that the inner prism had continued deformation until that time. Structural restorations of these folded seismic horizons demonstrate that ˜580 m of slip occurred on this steeply dipping reactivated thrust after fore-arc basin formation. Structural interpretation and analysis of logging-while-drilling data, including borehole images, in the deep inner prism revealed intense deformation of a generally homogenous lithology characterized by bedding that dips steeply (60°-90°), intersected by faults and fractures that have a range of dips and densities. Our study of the deep Kumano Basin provides new insights into the structure of the inner prism and reveals that although the inner prism has partially preserved inherited outer prism structures, these older folds and faults are steeply rotated and cut by multiple fracture populations during subsequent deformation.

  2. Organozinc hydroxylamides: on the bulk-dependent interplay of nuclearity, structure and dynamics.

    Science.gov (United States)

    Ullrich, Matthias; Berger, Raphael J F; Jana, Surajit; Pape, Tania; Fröhlich, Roland; Mitzel, Norbert W

    2011-02-01

    The reactions of zinc dialkyls, R(2)Zn (1a-d; R = Me (a), Et (b), iPr (c) and tBu (d)), with N,N-dialkylhydroxylamines, HO-NR'(2) (2a-c; R' = Me (a), Et (b) and iPr (c)), afford organozinc hydroxylamides under alkane extrusion. Species of different nuclearity are observed, depending on the hydroxylamine 2 employed. The smaller 2a and 2b give pentanuclear complexes of the general formula Zn(RZn)(4)O-NR'(2))(6) (R = Me, Et, iPr and tBu; R' = Me and Et), whereas the derivatives of 2c are tetramers of the general formula (RZn)(4)(O-NR'(2))(4) (R = Me, Et and iPr; R' = iPr) as governed by bulk issues about the N-donor. Due to the ability of the double-donor unit O-NR(2) to change its bridging mode, two coordination isomers exist for both types of compounds. The pentanuclear species crystallise either in a heterofenestrane or an octahedroid motif. For these species, the central Zn atom exhibits either coordination number 4 or 6; in solution, a rapid change between coordination isomers is observed. Due to the absence of a central Zn atom in the tetranuclear species, these aggregate in heterocubane geometries or such derived thereof. They display the O-N units in either κ(3)O or κ(2)O;κ(1)N mode. The tetranuclear species are also yielded with the less sterically encumbered precursors under thermodynamic conditions (i.e. reflux), as exemplified by the reaction of Me(2)Zn (1a) with HO-NEt(2) (2b). They are non-dynamic in solution, showing that a central cation is mandatory for the fluxional behaviour observed for the pentanuclear derivatives. DFT studies on the O-NMe(2) series reveal that the relative energies of the pentazinc isomers become more similar with increasing RZn group size; possible conversions of these to their tetrazinc counterparts were also scrutinised. Two κ(3)O-bridged degradation products of hydroxylamide complexes could be structurally characterised. They were formed either by partial product hydrolysis, or by in situ oxygenation of the starting zinc

  3. Multi-Trace Deformations in AdS/CFT: Exploring the Vacuum Structure of the Deformed CFT

    CERN Document Server

    Papadimitriou, I

    2007-01-01

    We present a general and systematic treatment of multi-trace deformations in the AdS/CFT correspondence in the large N limit, pointing out and clarifying subtleties relating to the formulation of the boundary value problem on a conformal boundary. We then apply this method to study multi-trace deformations in the presence of a scalar VEV, which requires the coupling to gravity to be taken into account. We show that supergravity solutions subject to `mixed' boundary conditions are in one-to-one correspondence with critical points of the holographic effective action of the dual theory in the presence of a multi-trace deformation, and we find a number of new exact analytic solutions involving a minimally or conformally coupled scalar field satisfying `mixed' boundary conditions. These include the generalization to any dimension of the instanton solution recently found in hep-th/0611315. Finally, we provide a systematic method for computing the holographic effective action in the presence of a multi-trace deforma...

  4. Analysis of intelligent hinged shell structures: deployable deformation and shape memory effect

    Science.gov (United States)

    Shi, Guang-Hui; Yang, Qing-Sheng; He, X. Q.

    2013-12-01

    Shape memory polymers (SMPs) are a class of intelligent materials with the ability to recover their initial shape from a temporarily fixable state when subjected to external stimuli. In this work, the thermo-mechanical behavior of a deployable SMP-based hinged structure is modeled by the finite element method using a 3D constitutive model with shape memory effect. The influences of hinge structure parameters on the nonlinear loading process are investigated. The total shape memory of the processes the hinged structure goes through, including loading at high temperature, decreasing temperature with load carrying, unloading at low temperature and recovering the initial shape with increasing temperature, are illustrated. Numerical results show that the present constitutive theory and the finite element method can effectively predict the complicated thermo-mechanical deformation behavior and shape memory effect of SMP-based hinged shell structures.

  5. Analysis of intelligent hinged shell structures: deployable deformation and shape memory effect

    International Nuclear Information System (INIS)

    Shape memory polymers (SMPs) are a class of intelligent materials with the ability to recover their initial shape from a temporarily fixable state when subjected to external stimuli. In this work, the thermo-mechanical behavior of a deployable SMP-based hinged structure is modeled by the finite element method using a 3D constitutive model with shape memory effect. The influences of hinge structure parameters on the nonlinear loading process are investigated. The total shape memory of the processes the hinged structure goes through, including loading at high temperature, decreasing temperature with load carrying, unloading at low temperature and recovering the initial shape with increasing temperature, are illustrated. Numerical results show that the present constitutive theory and the finite element method can effectively predict the complicated thermo-mechanical deformation behavior and shape memory effect of SMP-based hinged shell structures. (paper)

  6. Lipid memberane:inelastic deformation of surface structure by an atomic force microscope

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The stability of the 1,2-Dioleoyl-sn-Glycero-3-[phospho-rac-1-Glycerol-Na] liposome in the liquid crystalline state have been investigated using an atomic force microscope(AFM),We have observed the inelastic deformation of the sample surface,The AFM tip causes persistent deformation of the surface of the lipid membrane,in which some of the lipid molecules are eventually pushed or dragged by the AFM tip.The experiment shows how the surface structure of the lipid membrane can be created by the interaction between the AFM tip and lipid membrane.When the operating force exceeds 10-8N,it leads to large deformations of the surface.A squareregion of about 1×1um2 is created by the scanning probe on the surface,When the operating force is between 10-11N and 10-8N,it can image the topography of the surface of the lipid membrane.The stability of the sample is related to the concentration of the medium in which the sample is prepared.

  7. Lipid membrane: inelastic deformation of surface structure by an atomic force microscope

    Institute of Scientific and Technical Information of China (English)

    张静; 孙润广

    2002-01-01

    The stability of the 1,2-Dioleoyl-sn-Glycero-3-[phospho-rac-1-Glycerol-Na] liposome in the liquid crystalline statehave been investigated using an atomic force microscope (AFM). We have observed the inelastic deformation of thesample surface. The AFM tip causes persistent deformation of the surface of the lipid membrane, in which some of thelipid molecules are eventually pushed or dragged by the AFM tip. The experiment shows how the surface structure ofthe lipid membrane can be created by the interaction between the AFM tip and lipid membrane. When the operatingforce exceeds 10-8 N, it leads to large deformations of the surface. A square region of about 1×1μm2 is created by thescanning probe on the surface. When the operating force is between 10-11N and 10-8N, it can image the topographyof the surface of the lipid membrane. The stability of the sample is related to the concentration of the medium in whichthe sample is prepared.

  8. Deformation microstructures

    DEFF Research Database (Denmark)

    Hansen, N.; Huang, X.; Hughes, D.A.

    2004-01-01

    Microstructural characterization and modeling has shown that a variety of metals deformed by different thermomechanical processes follows a general path of grain subdivision, by dislocation boundaries and high angle boundaries. This subdivision has been observed to very small structural scales...

  9. Dynamic of articulated systems with deformable or undeformable structures. Robotic application

    International Nuclear Information System (INIS)

    The rapid developments in robotics, as well as the increasing complexity of the associated mechanical devices, show the interest for a numerical code to handle mechanisms problems. It is necessary to take into account the specific properties of articulated systems. In particular, large displacements have to be considered, while quasi-rigid structures are related through various articulations, which have to be modeled. Deformability also becomes important, as soon as the spead increases. The developments now carried out in the PLEXUS code of the CASTEM Finite Element System, will allow this program to be suitable tool to handle mechanisms problems

  10. 3D visualization of deformation structures and potential fluid pathways at the Grimsel Test Site

    Science.gov (United States)

    Schneeberger, Raphael; Kober, Florian; Berger, Alfons; Spillmann, Thomas; Herwegh, Marco

    2015-04-01

    Knowledge on the ability of fluids to infiltrate subsurface rocks is of major importance for underground constructions, geothermal or radioactive waste disposal projects. In this study, we focus on the characterization of water infiltration pathways, their 3D geometries and origins. Based on surface and subsurface mapping in combination with drill core data, we developed by the use of MoveTM (Midland Valley Exploration Ltd.) a 3D structural model of the Grimsel Test Site (GTS). GTS is an underground laboratory operated by NAGRA, the Swiss organisation responsible for the management of nuclear waste. It is located within a suite of post-Variscan magmatic bodies comprising former granitic and granodioritic melts, which are dissected by mafic and aplitic dikes. During Alpine orogeny, the suite was tectonically overprinted within two stages of ductile deformation (Wehrens et al., in prep.) followed by brittle overprint of some of the shear zones during the retrograde exhumation history. It is this brittle deformation, which controls today's water infiltration network. However, the associated fractures, cataclasites and fault gouges are controlled themselves by aforementioned pre-existing mechanical discontinuities, whose origin ranges back as far as to the magmatic stage. For example, two sets of vertically oriented mafic dikes (E-W and NW-SE striking) and compositional heterogeneities induced by magmatic segregation processes in the plutonic host rocks served as nucleation sites for Alpine strain localization. Subsequently, NE-SW, E-W and NW-SE striking ductile shear zones were formed, in combination with high temperature fracturing while dissecting the host rocks in a complex 3D pattern (Wehrens et al, in prep.). Whether the ductile shear zones have been subjected to brittle reactivation and can serve as infiltration pathways or not, depends strongly on their orientations with respect to the principal stress field. Especially where deformation structures intersect

  11. Micro-Structural Response of DP 600 to High Strain Rate Deformation

    Science.gov (United States)

    Hamburg, Brian; Schneider, Judy; Jones, Stanley E.

    2008-01-01

    The object of this study was to investigate the micro-structural response of DP 600 subjected to high strain rate, ballistic impact tests. The ballistic tests were conducted using normal impact of a hardened steel penetrator into a 2 mm thick sheet of DP 600. The average strain rates produced from this test method are on the order of 10(exp 5)/s. Electron microscopy was used to investigate the microstructure before and after high strain rate deformation. A variation in material response was observed between tests conducted at 0.8 x 105 and 25 x 10(exp 5)/s.

  12. Photonic band structures of two-dimensional photonic crystals with deformed lattices

    Institute of Scientific and Technical Information of China (English)

    Cai Xiang-Hua; Zheng Wan-Hua; Ma Xiao-Tao; Ren Gang; Xia Jian-Bai

    2005-01-01

    Using the plane-wave expansion method, we have calculated and analysed the changes of photonic band structures arising from two kinds of deformed lattices, including the stretching and shrinking of lattices. The square lattice with square air holes and the triangular lattice with circular air holes are both studied. Calculated results show that the change of lattice size in some special ranges can enlarge the band gap, which depends strongly on the filling factor of air holes in photonic crystals; and besides, the asymmetric band edges will appear with the broken symmetry of lattices.

  13. Nondestructive observation of pore structure deformation behavior of functionally graded aluminum foam by X-ray computed tomography

    International Nuclear Information System (INIS)

    Cellular materials are expected to be used for the components of automobiles and as railway and building materials owing to their lightweight structures and desirable mechanical properties. The newest class of cellular materials consists of functionally graded aluminum (FG Al) foams, in which the properties vary with the position. In this study, closed-cell FG Al foam with a varying pore structure was fabricated and its deformation behavior during the compression tests was nondestructively observed by X-ray computed tomography (X-ray CT). The fabricated FG Al foam had different pore structures (different densities) in the same Al foam. The FG Al foam initially started to deform only in the low-density region, which was followed by deformation in the high-density region. The deformation of the FG Al foam indicated its novel mechanical properties, such as multiple plateau stresses, corresponding to the pore structures of the regions where deformation occurred. Consequently, it was shown that the FG Al foam with a varying pore structure and a seamless bonding interface has the potential to be deformed at a controlled and desired location and with a desired plateau stress.

  14. In situ characterization of the deformation and failure behavior of non-stochastic porous structures processed by selective laser melting

    International Nuclear Information System (INIS)

    Highlights: → The present study focused on deformation behavior and failure mechanisms in lattice structure produced by selective laser melting (SLM). → It is demonstrated that heat treatments can be used to increase the energy absorption of an SLM-processed structure. → An in situ testing procedure was introduced, where local strains were calculated by digital image correlation → Shear failure could be predicted by localization using Tresca strains. → The approach employed provides a means to understand the microstructure-mechanical property-local deformation relationship. - Abstract: Cellular materials are promising candidates for load adapted light-weight structures. Direct manufacturing (DM) tools are effective methods to produce non-stochastic structures. Many DM studies currently focus on optimization of the geometric nature of the structures obtained. The literature available so far reports on the mechanical properties but local deformation mechanisms are not taken into account. In order to fill this gap, the current study addresses the deformation behavior of a lattice structure produced by selective laser melting (SLM) on the local scale by means of a comprehensive experimental in situ approach, including electron backscatter diffraction, scanning electron microscopy and digital image correlation. SLM-processed as well as heat treated lattice structures made from TiAl6V4 alloy were employed for mechanical testing. It is demonstrated that the current approach provides means to understand the microstructure-mechanical property-local deformation relationship to allow for optimization of load adapted lattice structures.

  15. Symmetry Analysis of the Kohn-Sham Band Structure of Bulk Lithium Fluoride

    OpenAIRE

    Mathar, Richard J.

    2003-01-01

    Kohn-Sham orbitals of face-centered cubic lithium fluoride are calculated in prototypical local-density approximations to the exchange-correlation functional. The symmetry analysis of these Bloch functions in a LCAO basis on a path Gamma-X-W-K-Gamma-L-W through the Brillouin Zone is compiled into a list of errata to symmetry labels in the LiF literature, the bulk of which dates back to the 1970's.

  16. Simulation of CO2 Injection in Porous Media with Structural Deformation Effect

    KAUST Repository

    Negara, Ardiansyah

    2011-06-18

    Carbon dioxide (CO2) sequestration is one of the most attractive methods to reduce the amount of CO2 in the atmosphere by injecting it into the geological formations. Furthermore, it is also an effective mechanism for enhanced oil recovery. Simulation of CO2 injection based on a suitable modeling is very important for explaining the fluid flow behavior of CO2 in a reservoir. Increasing of CO2 injection may cause a structural deformation of the medium. The structural deformation modeling in carbon sequestration is useful to evaluate the medium stability to avoid CO2 leakage to the atmosphere. Therefore, it is important to include such effect into the model. The purpose of this study is to simulate the CO2 injection in a reservoir. The numerical simulations of two-phase flow in homogeneous and heterogeneous porous media are presented. Also, the effects of gravity and capillary pressure are considered. IMplicit Pressure Explicit Saturation (IMPES) and IMplicit Pressure-Displacements and an Explicit Saturation (IMPDES) schemes are used to solve the problems under consideration. Various numerical examples were simulated and divided into two parts of the study. The numerical results demonstrate the effects of buoyancy and capillary pressure as well as the permeability value and its distribution in the domain. Some conclusions that could be derived from the numerical results are the buoyancy of CO2 is driven by the density difference, the CO2 saturation profile (rate and distribution) are affected by the permeability distribution and its value, and the displacements of the porous medium go to constant values at least six to eight months (on average) after injection. Furthermore, the simulation of CO2 injection provides intuitive knowledge and a better understanding of the fluid flow behavior of CO2 in the subsurface with the deformation effect of the porous medium.

  17. Multiscale structural changes of atomic order in severely deformed industrial aluminum

    Science.gov (United States)

    Samoilenko, Z. A.; Ivakhnenko, N. N.; Pushenko, E. I.; Pashinskaya, E. G.; Varyukhin, V. N.

    2016-02-01

    The regularities of multiscale structural changes in the atomic order of the aluminum alloy AD-1 after a severe cold plastic deformation by conventional rolling in smooth rolls or in rolls with relief recesses favorable for shear deformation have been investigated. It has been found that there are four types of structural fractions that differ in scale and perfection of atomic order: crystallographic planes with a long-range order; nanoscale fragments of the planes ( D = 100-300 Å) with an incipient long-range order; smaller groups of atoms ( D = 20-30 Å) of amorphized structure; and the least ordered structural fraction of intercluster medium, keeping only a short-range atomic order (2-3 interatomic distances, 10 Å). The presence of diffuse halo bands in the region of intense Debye lines indicates phase transitions of the order → disorder type with the formation of one to three groups of amorphous clusters with the dominance, in the nanometer scale, of the atomic order characteristic of the family of planes (111), (220), and (311) of crystalline aluminum. We have found a dynamic phase transition with the changing crystallographic order of aluminum, with the matrix structure of a face-centered cubic (FCC) lattice, in the form of nanosized local groups of atoms, that is, the deformation clusters of aluminum with a simple cubic K6 lattice. In the case of conventional rolling, the development of large clusters 50-500 Å in size is observed; however, in the use of rolls with relief recesses, the difference in the sizes of the clusters is one half as much: 50-250 Å. Based on the analysis of the integrated intensity of incoherent X-ray scattering by the samples, we have elucidated the nature of the lowest measured density for the sample subjected to conventional rolling, which consists in the volume concentration of disorderly arranged atoms, the highest of the compared structures, which indicates the formation therein of the greatest amount of fluctuation "voids."

  18. N-body + Magnetohydrodynamical Simulations of Merging Clusters of Galaxies: Characteristic Magnetic Field Structures Generated by Bulk Flow Motion

    CERN Document Server

    Takizawa, Motokazu

    2008-01-01

    We present results from N-body + magnetohydrodynamical simulations of merging clusters of galaxies. We find that cluster mergers cause various characteristic magnetic field structures because of the strong bulk flows in the intracluster medium. The moving substructures result in cool regions surrounded by the magnetic field. These will be recognized as magnetized cold fronts in the observational point of view. A relatively ordered magnetic field structure is generated just behind the moving substructure. Eddy-like field configurations are also formed by Kelvin-Helmholtz instabilities. These features are similarly seen even in off-center mergers though the detailed structures change slightly. The above-mentioned characteristic magnetic field structures are partly recognized in Faraday rotation measure maps. The higher absolute values of the rotation measure are expected when observed along the collision axis, because of the elongated density distribution and relatively ordered field structure along the axis. T...

  19. Modelling and simulation of explosions in soil interacting with deformable structures

    Science.gov (United States)

    Zakrisson, Björn; Häggblad, Hans-Áke; Jonsén, Pär

    2012-12-01

    A detonating explosive interacting with a deformable structure is a highly transient and non-linear event. In field blast trials of military vehicles, a standard procedure is often followed in order to reduce the uncertainties and increase the quality of the test. If the explosive is buried in the ground, the state of the soil must meet specific demands. In the present work, laboratory experiments have been performed to characterize the behaviour of a soil material. Soil may be considered a three-phase medium, consisting of solid grains, water and air. Variations between the amounts of these phases affect the mechanical properties of the soil. The experimental outcome has formed input data to represent the soil behaviour included in a three-phase elastic-plastic cap model. This unified constitutive model for soil has been used for numerical simulations representing field blast trials, where the explosive load is interacting with a deformable structure. The blast trials included explosive buried at different depths in wet or dry sand. A dependence of the soil initial conditions can be shown, both in the past field trials along with the numerical simulations. Even though some deviations exist, the simulations showed in general acceptable agreement with the experimental results.

  20. On D-brane -anti D-brane effective actions and their all order bulk singularity structures

    Science.gov (United States)

    Hatefi, Ehsan

    2016-04-01

    All four point functions of brane anti brane system including their correct all order α' corrections have been addressed. All five point functions of one closed string Ramond-Ramond (RR), two real tachyons and either one gauge field or the scalar field in both symmetric and asymmetric pictures have also been explored. The entire analysis of is carried out. Not only does it fix the vertex operator of RR in asymmetric picture and in higher point functions of string theory amplitudes but also it confirms the fact that there is no issue of picture dependence of the mixed closed RR, gauge fields, tachyons and fermion fields in all symmetric or anti symmetric ones. We compute S-matrix in the presence of a transverse scalar field, two real tachyons and that reveals two different kinds of bulk singularity structures, involving an infinite number of u-channel gauge field and (u+s'+t')-channel scalar bulk poles. In order to produce all those bulk singularity structures, we define various couplings at the level of the effective field theory that involve the mixing term of Chern-Simons coupling (with C-potential field) and a covariant derivative of the scalar field that comes from the pull-back of brane. Eventually we explore their all order α' corrections in the presence of brane anti brane system where various remarks will be also pointed out.

  1. On D-brane-Anti D-brane Effective actions and their all order Bulk Singularity Structures

    CERN Document Server

    Hatefi, Ehsan

    2016-01-01

    All four point functions of brane anti brane system including their correct all order $\\alpha'$ corrections have been addressed. All five point functions of one closed string Ramond-Ramond (RR), two real tachyons and either one gauge field or the scalar field in both symmetric and asymmetric pictures have also been explored. The entire analysis of $$ is carried out. Not only does it fix the vertex operator of RR in asymmetric picture and in higher point functions of string theory amplitudes but also it confirms the fact that there is no issue of picture dependence of the mixed closed RR, gauge fields, tachyons and fermion fields in all symmetric or anti symmetric ones. We compute $$ S-matrix in the presence of a transverse scalar field, two real tachyons and that reveals two different kinds of bulk singularity structures, involving an infinite number of $u'$ gauge field and $(u+s'+t')$ bulk poles. In order to produce all those bulk singularity structures, we define various couplings at the level of the effect...

  2. Structural deformation upon protein-protein interaction: A structural alphabet approach

    OpenAIRE

    Lecornet Hélène; Regad Leslie; Martin Juliette; Camproux Anne-Claude

    2008-01-01

    Abstract Background In a number of protein-protein complexes, the 3D structures of bound and unbound partners significantly differ, supporting the induced fit hypothesis for protein-protein binding. Results In this study, we explore the induced fit modifications on a set of 124 proteins available in both bound and unbound forms, in terms of local structure. The local structure is described thanks to a structural alphabet of 27 structural letters that allows a detailed description of the backb...

  3. Magnetic characterisation of large grain, bulk Y–Ba–Cu–O superconductor–soft ferromagnetic alloy hybrid structures

    International Nuclear Information System (INIS)

    Highlights: • Large grain, bulk YBaCuO superconductor (SC) combined with ferromagnetic elements. • The flux lines curve outwards through the ferromagnet in the remanent state. • The trapped field in the SC is enhanced by the presence of the ferromagnet. • The effects of the SC and the ferromagnet add when the ferromagnet is saturated. - Abstract: Large grain, bulk Y–Ba–Cu–O (YBCO) high temperature superconductors (HTS) have significant potential for use in a variety of practical applications that incorporate powerful quasi-permanent magnets. In the present work, we investigate how the trapped field of such magnets can be improved by combining bulk YBCO with a soft FeNi, ferromagnetic alloy. This involves machining the alloy into components of various shapes, such as cylinders and rings, which are attached subsequently to the top surface of a solid, bulk HTS cylinder. The effect of these modifications on the magnetic hysteresis curve and trapped field of the bulk superconductor at 77 K are then studied using pick-up coil and Hall probe measurements. The experimental data are compared to finite element modelling of the magnetic flux distribution using Campbell’s algorithm. Initially we establish the validity of the technique involving pick-up coils wrapped around the bulk superconductor to obtain its magnetic hysteresis curve in a non-destructive way and highlight the difference between the measured signal and the true magnetization of the sample. We then consider the properties of hybrid ferromagnet/superconductor (F/S) structures. Hall probe measurements, together with the results of the model, establish that flux lines curve outwards through the ferromagnet, which acts, effectively, like a magnetic short circuit. Magnetic hysteresis curves show that the effects of the superconductor and the ferromagnet simply add when the ferromagnet is saturated fully by the applied field. The trapped field of the hybrid structure is always larger than that of the

  4. Magnetic characterisation of large grain, bulk Y–Ba–Cu–O superconductor–soft ferromagnetic alloy hybrid structures

    Energy Technology Data Exchange (ETDEWEB)

    Philippe, M.P., E-mail: M.Philippe@ulg.ac.be [SUPRATECS and Department of Electrical Engineering and Computer Science (B28), University of Liège, 4000 Liège (Belgium); Fagnard, J.-F.; Kirsch, S. [SUPRATECS and Department of Electrical Engineering and Computer Science (B28), University of Liège, 4000 Liège (Belgium); Xu, Z.; Dennis, A.R.; Shi, Y.-H.; Cardwell, D.A. [Bulk Superconductivity Group, Engineering Department, University of Cambridge, Cambridge CB2 1PZ (United Kingdom); Vanderheyden, B.; Vanderbemden, P. [SUPRATECS and Department of Electrical Engineering and Computer Science (B28), University of Liège, 4000 Liège (Belgium)

    2014-07-15

    Highlights: • Large grain, bulk YBaCuO superconductor (SC) combined with ferromagnetic elements. • The flux lines curve outwards through the ferromagnet in the remanent state. • The trapped field in the SC is enhanced by the presence of the ferromagnet. • The effects of the SC and the ferromagnet add when the ferromagnet is saturated. - Abstract: Large grain, bulk Y–Ba–Cu–O (YBCO) high temperature superconductors (HTS) have significant potential for use in a variety of practical applications that incorporate powerful quasi-permanent magnets. In the present work, we investigate how the trapped field of such magnets can be improved by combining bulk YBCO with a soft FeNi, ferromagnetic alloy. This involves machining the alloy into components of various shapes, such as cylinders and rings, which are attached subsequently to the top surface of a solid, bulk HTS cylinder. The effect of these modifications on the magnetic hysteresis curve and trapped field of the bulk superconductor at 77 K are then studied using pick-up coil and Hall probe measurements. The experimental data are compared to finite element modelling of the magnetic flux distribution using Campbell’s algorithm. Initially we establish the validity of the technique involving pick-up coils wrapped around the bulk superconductor to obtain its magnetic hysteresis curve in a non-destructive way and highlight the difference between the measured signal and the true magnetization of the sample. We then consider the properties of hybrid ferromagnet/superconductor (F/S) structures. Hall probe measurements, together with the results of the model, establish that flux lines curve outwards through the ferromagnet, which acts, effectively, like a magnetic short circuit. Magnetic hysteresis curves show that the effects of the superconductor and the ferromagnet simply add when the ferromagnet is saturated fully by the applied field. The trapped field of the hybrid structure is always larger than that of the

  5. Off-Yrast low-spin structure of deformed nuclei at mass number A∼150

    Energy Technology Data Exchange (ETDEWEB)

    Krugmann, Andreas

    2014-07-14

    -spinflip parts of the cross section has been done. Here, for the first time, the Pygmy Dipole Resonance (PDR) has been identified in the heavy deformed nucleus {sup 154}Sm that appears as a double-hump structure in the E1 response. A possible interpretation of this double-hump structure in terms of a deformation splitting analogously to the Giant Dipole Resonance (GDR) has been given. In case of the spinflip cross section, a broad distribution in the excitation energy range between 6 and 12 MeV has been observed. The distribution and the extracted sum strength are in good accordance with previous experiments.

  6. Potential of geodetic surveying as a guide for civil engineers in monitoring structural deformations

    Science.gov (United States)

    Nassar, Mohamed M.; El-Maghraby, Mohamed F.

    1988-03-01

    In a previous research performed by the senior author, the causes and implications of the earth's crustal movements in the Egyptian territory have been investigated. The reason was the increasing tendency of erecting huge engineering constructions in Egypt, like dams, bridges, towers, tunnels, nuclear power stations,… etc.). Such constructions, of course, represent a major part in the national economy, and hence, their safety is essential for both economical purposes as well as human security. The objective of this paper is to study the potential and resolution of geodetic surveying techniques in detecting the horizontal and vertical movements of different types of engineering constructions. This aims to help civil engineers monitor structural deformations during and after construction using precise geodetic surveying techniques, in order to overcome and master any defects due to local crustal movements and/or erection systems. The most suitable surveying technique for each type of structure is treated and analyzed for optimum results.

  7. Elasto-capillarity: deforming an elastic structure with a liquid droplet

    International Nuclear Information System (INIS)

    Although negligible at macroscopic scales, capillary forces become dominant as the sub-millimetric scales of micro-electro-mechanical systems (MEMS) are considered. We review various situations, not limited to micro-technologies, where capillary forces are able to deform elastic structures. In particular, we define the different length scales that are relevant for 'elasto-capillary' problems. We focus on the case of slender structures (lamellae, rods and sheets) and describe the size of a bundle of wet hair, the condition for a flexible rod to pierce a liquid interface or the fate of a liquid droplet deposited on a flexible thin sheet. These results can be generalized to similar situations involving adhesion or fracture energy, which widens the scope of possible applications from biological systems, to stiction issues in micro-fabrication processes, the manufacturing of 3D microstructures or the formation of blisters in thin film coatings. (topical review)

  8. Monte Carlo calculations on the magnetization profile and domain wall structure in bulk systems and nanoconstricitons

    Energy Technology Data Exchange (ETDEWEB)

    Serena, P. A. [Instituto de Ciencias de Materiales de Madrid, Madrid (Spain); Costa-Kraemer, J. L. [Instituto de Microelectronica de Madrid, Madrid (Spain)

    2001-03-01

    A Monte Carlo algorithm suitable to study systems described by an anisotropic Heisenberg Hamiltonian is presented. This technique has been tested successfully with 3D and 2D systems, illustrating how magnetic properties depend on the dimensionality and the coordination number. We have found that magnetic properties of constrictions differ from those appearing in bulk. In particular, spin fluctuations are considerable larger than those calculated for bulk materials. In addition, domain walls are strongly modified when a constriction is present, with a decrease of the domain-wall width. This decrease is explained in terms of previous theoretical works. [Spanish] Se presenta un algoritmo de Monte Carlo para estudiar sistemas discritos por un hamiltoniano anisotropico de Heisenburg. Esta tecnica ha sido probada exitosamente con sistemas de dos y tres dimensiones, ilustrado con las propiedades magneticas dependen de la dimensionalidad y el numero de coordinacion. Hemos encontrado que las propiedades magneticas de constricciones difieren de aquellas del bulto. En particular, las fluctuaciones de espin son considerablemente mayores. Ademas, las paredes de dominio son fuertemente modificadas cuando una construccion esta presente, originando un decrecimiento del ancho de la pared de dominio. Damos cuenta de este decrecimiento en terminos de un trabajo teorico previo.

  9. Structural deformation upon protein-protein interaction: A structural alphabet approach

    Directory of Open Access Journals (Sweden)

    Lecornet Hélène

    2008-02-01

    Full Text Available Abstract Background In a number of protein-protein complexes, the 3D structures of bound and unbound partners significantly differ, supporting the induced fit hypothesis for protein-protein binding. Results In this study, we explore the induced fit modifications on a set of 124 proteins available in both bound and unbound forms, in terms of local structure. The local structure is described thanks to a structural alphabet of 27 structural letters that allows a detailed description of the backbone. Using a control set to distinguish induced fit from experimental error and natural protein flexibility, we show that the fraction of structural letters modified upon binding is significantly greater than in the control set (36% versus 28%. This proportion is even greater in the interface regions (41%. Interface regions preferentially involve coils. Our analysis further reveals that some structural letters in coil are not favored in the interface. We show that certain structural letters in coil are particularly subject to modifications at the interface, and that the severity of structural change also varies. These information are used to derive a structural letter substitution matrix that summarizes the local structural changes observed in our data set. We also illustrate the usefulness of our approach to identify common binding motifs in unrelated proteins. Conclusion Our study provides qualitative information about induced fit. These results could be of help for flexible docking.

  10. Deformation of Aztec Sandstone at Valley of Fire of Nevada: failure modes, sequence of deformation, structural products and their interplay with paleo fluids

    Science.gov (United States)

    Aydin, A.

    2014-12-01

    The Valley of Fire State Park, 60 km NE of Las Vegas, is a beacon of knowledge for deformation of Aztec Sandstone, a cross-bedded quartz arenite deposited in the Aztec-Navajo-Nugget erg in early Jurassic. It displays great diversity of physical properties, different localization types and micromechanics. The two deformation episodes, the Sevier folding & thrusting and the Basin & Range extension affected the area. The appearance of compaction bands marks the earliest deformation structure and their distribution, orientation, and dimension are controlled by the depositional architecture and loading. The earliest shear structures in the area are the Muddy Mountain, Summit, and Willow Tank thrusts and numerous small-scale bed-parallel faults. They altogether produced several kilometers of E-SE transport and shortening in the late Cretaceous and display numerous shear bands in its damage zone within the Aztec Sandstone. Shear bands also occur along dune boundaries and cross-bed interfaces. These observations indicate that the early deformation of the sandstone was accommodated by strain localization with various kinematics. The younger generation of faults in the area is of mid-Miocene age, and crops out pervasively. It includes a series of small offset normal faults (less than a few ten meters) which can be identified at steep cliff faces. These faults are highly segmented and are surrounded by a dense population of splay fractures. A large number of these splays were later sheared sequentially resulting in a well-defined network of left- and right-lateral strike-slip faults with slip magnitudes up to a few kilometers in the Park. The formation mechanisms of both the normal and strike-slip faults can be characterized as the sliding along planes of initial weaknesses and the accompanying cataclastic deformation. Some of the initial weak planes are associated with the depositional elements such as interdune boundaries and cross-bed interfaces while others are joint

  11. Thermally assisted deformation of structural superplastics and nanostructured materials: A personal perspective

    Indian Academy of Sciences (India)

    K A Padmanabhan

    2003-02-01

    Optimal structural superplasticity and the deformation of nanostructured materials in the thermally activated region are regarded as being caused by the same physical process. In this analysis, grain/interphase boundary sliding controls the rate of deformation at the level of atomistics. Boundary sliding develops to a mesoscopic level by plane interface formation involving two or more boundaries and at this stage the rate controlling step is boundary migration. In other words, grain/interphase boundary sliding is viewed as a two-scale process. The non-zero, unbalanced shear stresses present at the grain/interphase boundaries ensure that near-random grain rotation is also a non-rate controlling concomitant of this mechanism. Expressions have been derived for the free energy of activation for the atomic scale rate controlling process, the threshold stress that should be crossed for the commencement of mesoscopic boundary sliding, the inverse Hall-Petch effect and the steady state rate equation connecting the strain rate to the independent variables of stress, temperature and grain size. Beyond the point of inflection in the log stress-log strain rate plot, climb controlled multiple dislocation motion within the grains becomes increasingly important and at sufficiently high stresses becomes rate controlling. The predictions have been validated experimentally.

  12. Structure of the N=59 nucleus 97Sr: Coexistence of spherical and deformed states

    International Nuclear Information System (INIS)

    A band with a rotational pattern based on a state at 585.1 keV has been identified in the N=59 neutron-rich nucleus 97Sr. Its properties lead to the 3/2 Nilsson-orbital assignment for the band head. There is evidence for a second band with the head at 644.7 keV and the configuration 3/2. Since the ground state and the lowest excited levels are spherical, shape coexistence is established for 97Sr. A deformed nature of several levels at 500-600 keV results also from QRPA-model calculations. The structure of the low-lying spherical levels has been studied in the frame of the IBF model. The results of the present investigations lead to a better understanding of the N=59 isotones which constitute the link between the spherical and deformed nuclei at A ≅ 100 as a species with shape coexistence but without any indications of particular softness. (orig.)

  13. Dislocation structure evolution and characterization in the compression deformed Mn-Cu alloy

    International Nuclear Information System (INIS)

    Dislocation densities and dislocation structure arrangements in cold compressed polycrystalline commercial M2052 (Mn-20Cu-5Ni-2Fe) high damping alloy with various strains were determined in scanning mode by X-ray peak profile analysis and electron backscatter diffraction (EBSD). The results indicate that the Mn-Cu-Ni-Fe alloy has an evolution behavior quite similar to the dislocation structure in copper. The dislocation arrangement parameter shows a local minimum in the transition range between stages III and IV that can be related to the transformation of the dislocation arrangement in the cell walls from a polarized dipole wall (PDW) into a polarized tile wall (PTW) structure. This evolution is further confirmed by the results of local misorientation determined by EBSD. In addition, during deformation, the multiplication of dislocation densities in the MnCu alloy is significantly slower than that in copper, and the transition of the dislocation structure is strongly retarded in the MnCu alloy compared with copper. These results can be explained by the mechanism of elastic anisotropy on the dislocation dynamics, as the elastic anisotropy in the MnCu alloy is larger than that in copper, which can strongly retard the multiplication of the dislocation population and the transformation of the dislocation structure. These results are important for research into the plastic working behavior of Mn-Cu-Ni-Fe high damping alloy

  14. Structure and soft magnetic properties of Fe72B20Si4Nb4 bulk metallic glasses

    Directory of Open Access Journals (Sweden)

    R. Nowosielski

    2009-01-01

    Full Text Available Purpose: The paper presents a microstructure characterization, thermal stability and soft magnetic properties analysis of Fe-based bulk amorphous materials.Design/methodology/approach: The studies were performed on Fe72B20Si4Nb4 glassy alloy in form of ribbons and rods. The amorphous structure of tested samples was examined by X-ray diffraction (XRD, transmission electron microscopy (TEM and scanning electron microscopy (SEM methods. The thermal properties of the glassy samples were measured using differential thermal analysis (DTA and differential scanning calorimetry (DSC. The magnetic properties were determined by the Maxwell-Wien bridge and VSM methods.Findings: The X-ray diffraction and transmission electron microscopy investigations have revealed that the studied as-cast bulk metallic glasses were amorphous. Broad diffraction halo can be seen for all tested samples, indicating the formation of a glassy phase with the diameters up to 2 mm. The fracture surface of rod samples appears to consist of small fracture zones, which leads to breaking of the samples into parts. A two stage crystallization process was observed for studied amorphous alloy. The changes of crystallization temperatures and magnetic properties as a function of glassy samples thickness were stated.Practical implications: The studied Fe-based alloy system has good glass-forming ability and thermal stability for casting bulk metallic glasses, which exhibit good soft magnetic properties, useful for many electric and magnetic applications.Originality/value: The obtained examination results confirm the utility of applied investigation methods in the microstructure, thermal and soft magnetic properties analysis of examined bulk amorphous alloys.

  15. Localized deformation of a Cu46.25Zr45.25Al7.5Er1 bulk metallic glass

    International Nuclear Information System (INIS)

    Using the cavity model and the concept of the plastic-hardening modulus, a simple relationship was established between the size of an indent and the size of a semi-spherical-shell softening zone. Indentation experiments of a Cu46.25Zr45.25Al7.5Er1 bulk-metallic glass (BMG) were performed over a range of indentation loads from 500 to 4000 mN, using a Vickers indenter. The indentation hardness decreased slightly with the increase in the indentation load from 5.21 GPa at an indentation load of 500 mN to 4.66 GPa at an indentation load of 4000 mN. The evolution of shear bands underneath the indentation was studied using an interface-bonded BMG sample. Shear bands of a semi-spherical-shell shape and a line-shape were observed underneath the indentation. The dependence of the size of the shear-banding zone on the size of the indent was examined, which qualitatively supported the analytical model. The inter-banding spacing decreased with the increase in the indentation load, associated with the release of the stored strain energy.

  16. Post-assessment of pre-stressed containment structures by evaluation of monitored long term deformation results

    International Nuclear Information System (INIS)

    The comparison of monitored long term deformations of containment structures with calculated values achieved by using design material parameters shows occasionally considerable deviations, partly caused by conservative assumptions in the containments design phase. Systematic post-assessment and adaption of the decisive parameters attains better coincidence. In the present investigation measured long-term deformations are first of all compared to pre-calculated values based on the material parameters defined in the design phase. Afterwards, the deformations deviations are minimized by repeating the calculation with assessed material parameters. This method appears to be a suitable method to predict the future containment structure long-term behavior and to achieve a possible life-time extension. The presented investigation was performed as part of NUGENIA ACCEPPT project which researches the ageing of concrete containment structures in nuclear power plants

  17. Thermal stability of structure of deformed filamentary Co(Cr, Ni)-TaC eutectic

    International Nuclear Information System (INIS)

    Thermal stability of the directional microstructure of the eutectic Co(Cr, Ni)-TaC after preliminary deformation and in the process of the long-term strength tests has been studied. Predeformed samples showed in annealing the following three types of structural modifications: spheroidizing of fibre fragments, merging short fragments in long ones with their subsequent breaking into a number of spherical particles, formation of belts where the lateral grain boundaries contact with the phase interface. Consideration is given to the kinetics of shape and size changes of fragments in annealing at 1100 deg C of varying durations. The eutectic m mocrostructure in the process of the long-term strength tests shows a high thermal stability except for the neck zone, where fragmentation of TaC fibres and formation of belts on their surface take place

  18. The Lattice Structure of Connection Preserving Deformations for q-Painlevé Equations I

    Science.gov (United States)

    Ormerod, Christopher M.

    2011-05-01

    We wish to explore a link between the Lax integrability of the q-Painlevé equations and the symmetries of the q-Painlevé equations. We shall demonstrate that the connection preserving deformations that give rise to the q-Painlevé equations may be thought of as elements of the groups of Schlesinger transformations of their associated linear problems. These groups admit a very natural lattice structure. Each Schlesinger transformation induces a Bäcklund transformation of the q-Painlevé equation. Each translational Bäcklund transformation may be lifted to the level of the associated linear problem, effectively showing that each translational Bäcklund transformation admits a Lax pair. We will demonstrate this framework for the q-Painlevé equations up to and including q-PVI.

  19. Simple tool to search quasi-magic structures in deformed nuclei

    International Nuclear Information System (INIS)

    Strutinsky method the smooth energy of the nucleus is obtained by a folding procedure of the single-particle (s.p.) energy density in the s.p. energy space e. An alternative way of energy smoothing is obtained by folding the s.p. energy sum in the particle-number space N. For non degenerated s.p. spectra both types of folding yield smooth energies which are close to each other. In the case of strongly degenerated spectra which appear at sphericity or in regions of shape isomers, the smooth energy obtained by the N-folding is a couple of MeV larger than the traditional average Strutinsky energy. It is shown that this smooth energy difference can serve as a simple tool to search for magic or quasi-magic structures in the s.p. spectra, e.g. to find shape isomers in the multidimensional deformation space. (author)

  20. Microscopic structure of deformed and superdeformed collective bands in rotating nuclei

    International Nuclear Information System (INIS)

    We investigate in self-consistent cranked Nilsson plus quasiparticle random-phase approximation the structure of 190,192,194Hg in their evolution from normal to superdeformation and from low to high rotational frequencies. The analysis of the energy levels suggests a splitting of few normally deformed bands into two or more branches. The investigation of the dynamical moments of inertia supports the octupole character of the low-lying negative parity superdeformed bands, in agreement with previous theoretical predictions and experimental findings. As a more direct confirm of their octupole nature, we obtain strong E1 transitions linking those bands to the yrast superdeformed band, in agreement with experiments. A similar result is shown to hold also for 152Dy. Like in 152Dy, the collectivity of the low-lying scissors mode gets enhanced with the onset of superdeformation

  1. Cell structure in cold worked and creep deformed phosphorus alloyed copper

    International Nuclear Information System (INIS)

    Transmission electron microscopy (TEM) examinations on as-received, cold worked, as well as cold worked and creep tested phosphorus-alloyed oxygen-free copper (Cu-OFP) have been carried out to study the role of the cell structure. The cell size decreased linearly with increasing plastic deformation in tension. The flow stress in the tests could also be correlated to the cell size. The observed relation between the flow stress and the cell size was in excellent agreement with previously published results. The dense dislocation walls that appeared after cold work in tension is likely to be the main reason for the dramatic increase in creep strength. The dense dislocation walls act as barriers against dislocation motion and their presence also reduces the recovery rate due to an unbalanced dislocation content

  2. Weak solutions for the motion of a self-propelled deformable structure in a viscous incompressible fluid

    OpenAIRE

    Nečasová, Š. (Šárka); T. Takahashi; Tucsnak, M.

    2011-01-01

    We consider the three-dimensional motion of a self-propelled deformable structure into a viscous incompressible fluid. The deformation of the solid is given whereas its position is unknown. Such a system could model the propulsion of fish-like swimmers. The equations of motion of the fluid are the Navier-Stokes equations and the equations for the structure are deduced from Newton's laws. The corresponding system is a free boundary problem and the main result of the paper is the existence of w...

  3. Correlation between structural, electrical and magnetic properties of GdMnO{sub 3} bulk ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Samantaray, S. [Institute of Materials Science, Planetarium Building, Bhubaneswar 751013, Odisha (India); Mishra, D.K. [Department of Physics, Institute of Technical Education and Research, S ‘O’ A University, Bhubaneswar 751030, Odisha (India); Pradhan, S.K. [Institute of Materials Science, Planetarium Building, Bhubaneswar 751013, Odisha (India); Mishra, P.; Sekhar, B.R. [Institue of Physics, Sachivalaya Marg, Bhubaneswar, Odisha (India); Behera, Debdhyan [Advanced Materials Technology Department, CSIR-Institute of Minerals and Materials Technology, Bhubaneswar 751013, Odisha (India); Rout, P.P.; Das, S.K. [Institute of Materials Science, Planetarium Building, Bhubaneswar 751013, Odisha (India); Sahu, D.R. [School of Physics, University of the Witwatersrand, Johannesburg (South Africa); Roul, B.K., E-mail: ims@iopb.res.in [Institute of Materials Science, Planetarium Building, Bhubaneswar 751013, Odisha (India)

    2013-08-15

    This paper reports the effect of sintering temperature on ferroelectric properties of GdMnO{sub 3} (GMO) bulk ceramics at room temperature prepared by the conventional solid state reaction route following slow step sintering schedule. Ferroelectric hysteresis loop as well as sharp dielectric anomaly in pure (99.999%) GMO sintered ceramics has been clearly observed. Samples sintered at 1350 °C become orthorhombic with Pbnm space group and showed frequency independent sharp dielectric anomalies at 373 K and a square type of novel ferroelectric hysteresis loop was observed at room temperature. Interestingly, dielectric anomalies and ferroelectric behavior were observed to be dependent upon sintering temperature of GdMnO{sub 3}. Room temperature dielectric constant (ε{sub r}) value at different frequencies is observed to be abnormally high. The magnetic field and temperature dependent magnetization show antiferromagnetic behavior at 40 K for both 1350 °C and 1700 °C sintered GMO. Present findings showed the possibility of application of GdMnO{sub 3} at room temperature as multifunctional materials. - Highlights: • Preparation of single-phasic polycrystalline GdMnO{sub 3} sample by the solid state sintering route. • Observation of square type P–E hysteresis loop with higher saturation and remnant polarization. • Observation of antiferromagnetic behavior at 40 K in polycrystalline GdMnO{sub 3}. • Possibility of room temperature application of GdMnO{sub 3} as multifunctional material.

  4. Correlation between structural, electrical and magnetic properties of GdMnO3 bulk ceramics

    Science.gov (United States)

    Samantaray, S.; Mishra, D. K.; Pradhan, S. K.; Mishra, P.; Sekhar, B. R.; Behera, Debdhyan; Rout, P. P.; Das, S. K.; Sahu, D. R.; Roul, B. K.

    2013-08-01

    This paper reports the effect of sintering temperature on ferroelectric properties of GdMnO3 (GMO) bulk ceramics at room temperature prepared by the conventional solid state reaction route following slow step sintering schedule. Ferroelectric hysteresis loop as well as sharp dielectric anomaly in pure (99.999%) GMO sintered ceramics has been clearly observed. Samples sintered at 1350 °C become orthorhombic with Pbnm space group and showed frequency independent sharp dielectric anomalies at 373 K and a square type of novel ferroelectric hysteresis loop was observed at room temperature. Interestingly, dielectric anomalies and ferroelectric behavior were observed to be dependent upon sintering temperature of GdMnO3. Room temperature dielectric constant (ɛr) value at different frequencies is observed to be abnormally high. The magnetic field and temperature dependent magnetization show antiferromagnetic behavior at 40 K for both 1350 °C and 1700 °C sintered GMO. Present findings showed the possibility of application of GdMnO3 at room temperature as multifunctional materials.

  5. Correlation between structural, electrical and magnetic properties of GdMnO3 bulk ceramics

    International Nuclear Information System (INIS)

    This paper reports the effect of sintering temperature on ferroelectric properties of GdMnO3 (GMO) bulk ceramics at room temperature prepared by the conventional solid state reaction route following slow step sintering schedule. Ferroelectric hysteresis loop as well as sharp dielectric anomaly in pure (99.999%) GMO sintered ceramics has been clearly observed. Samples sintered at 1350 °C become orthorhombic with Pbnm space group and showed frequency independent sharp dielectric anomalies at 373 K and a square type of novel ferroelectric hysteresis loop was observed at room temperature. Interestingly, dielectric anomalies and ferroelectric behavior were observed to be dependent upon sintering temperature of GdMnO3. Room temperature dielectric constant (εr) value at different frequencies is observed to be abnormally high. The magnetic field and temperature dependent magnetization show antiferromagnetic behavior at 40 K for both 1350 °C and 1700 °C sintered GMO. Present findings showed the possibility of application of GdMnO3 at room temperature as multifunctional materials. - Highlights: • Preparation of single-phasic polycrystalline GdMnO3 sample by the solid state sintering route. • Observation of square type P–E hysteresis loop with higher saturation and remnant polarization. • Observation of antiferromagnetic behavior at 40 K in polycrystalline GdMnO3. • Possibility of room temperature application of GdMnO3 as multifunctional material

  6. Surface and bulk electronic structure of unconventional superconductor Sr_2RuO_4: unusual splitting of the beta-band

    OpenAIRE

    Zabolotnyy, V. B.; Carleschi, E.; Kim, T K; Kordyuk, A. A.; Trinckauf, J.; Geck, J.; Evtushinsky, D. V.; Doyle, B.P.; Fittipaldi, R.; Cuoco, M.; Vecchione, A.; Buchner, B; Borisenko, S. V.

    2011-01-01

    We present an angle resolved photoemission study of the surface and bulk electronic structure of the single layer ruthenate Sr$_2$RuO$_4$. As the early studies of its electronic structure by photoemission and scanning tunneling microscopy were confronted with a problem of surface reconstruction, surface aging was previously proposed as a possible remedy to access the bulk states. Here we suggest an alternative way by demonstrating that, in the case of Sr$_2$RuO$_4$, circularly polarised light...

  7. Bulk and surface band structure of the new family of semiconductors BiTeX (X=I, Br, Cl)

    Energy Technology Data Exchange (ETDEWEB)

    Moreschini, L., E-mail: lmoreschini@lbl.gov [Advanced Light Source (ALS), Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Autès, G. [Institute of Theoretical Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Crepaldi, A. [Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Moser, S. [Advanced Light Source (ALS), Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Johannsen, J.C. [Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Kim, K.S. [Advanced Light Source (ALS), Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Department of Physics, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang 790-784 (Korea, Republic of); Berger, H.; Bugnon, Ph.; Magrez, A. [Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Denlinger, J.; Rotenberg, E.; Bostwick, A. [Advanced Light Source (ALS), Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Yazyev, O.V. [Institute of Theoretical Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); and others

    2015-05-15

    Highlights: • We provide an ARPES comparison between the three tellurohalides BiTeX (X = I, Br, Cl). • They present a similar band structure with namely spin-split bulk and surface states. • They offer, except for BiTeCl, the possibility of ambipolar conduction. • They can be easily doped. • From the data appeared so far, BiTeBr may be the most appealing for applications. - Abstract: We present an overview of the new family of semiconductors BiTeX (X = I, Br, Cl) from the perspective of angle resolved photoemission spectroscopy. The strong band bending occurring at the surface potentially endows them with a large flexibility, as they are capable of hosting both hole and electron conduction, and can be modified by inclusion or adsorption of foreign atoms. In addition, their trigonal crystal structure lacks a center of symmetry and allows for both bulk and surface spin-split bands at the Fermi level. We elucidate analogies and differences among the three materials, also in the light of recent theoretical and experimental work.

  8. Bulk and surface band structure of the new family of semiconductors BiTeX (X=I, Br, Cl)

    International Nuclear Information System (INIS)

    Highlights: • We provide an ARPES comparison between the three tellurohalides BiTeX (X = I, Br, Cl). • They present a similar band structure with namely spin-split bulk and surface states. • They offer, except for BiTeCl, the possibility of ambipolar conduction. • They can be easily doped. • From the data appeared so far, BiTeBr may be the most appealing for applications. - Abstract: We present an overview of the new family of semiconductors BiTeX (X = I, Br, Cl) from the perspective of angle resolved photoemission spectroscopy. The strong band bending occurring at the surface potentially endows them with a large flexibility, as they are capable of hosting both hole and electron conduction, and can be modified by inclusion or adsorption of foreign atoms. In addition, their trigonal crystal structure lacks a center of symmetry and allows for both bulk and surface spin-split bands at the Fermi level. We elucidate analogies and differences among the three materials, also in the light of recent theoretical and experimental work

  9. Measurements of deformations in osseous structures and implants by digital speckle interferometry (DSPI)

    Science.gov (United States)

    Salvador, Rosario; González-Peña, Rolando; Cibrián, Rosa; Buendía, Mateo; Mínguez, Fe; Laguía, Manuel; Molina, Teresa; Marti, Luis; Esteve, José; Caballero, José; Micó, Vicente; Sanjuan, Elena

    2006-09-01

    Knowledge of how osseous structures and implants behave under deforming stress is an interesting point when evaluating the response of an implanted prosthesis. The failure of an implant is not always due to the great stress a structure may be subjected to at a particular moment, but rather to the effects of deterioration associated with lesser stress but which is continuously applied. Therefore it is helpful to know how bones and implants respond to this lesser stress. Digital speckle interferometry (DSPI) is suitable for this type of determination, as it is a highly sensitive, non-invasive optical technique. In this study we present the results we obtained when determining the elasticity of a sample of a macerated human radius, a titanium implant and a titanium screw used to treat the fractures of this bone. The correlation ratios we obtained in determining Young's modulus were in the order of r=0.994. Models were made of these structures using the finite elements method (FEM) with the aid of the ANSYS 10.0 program, applying Young's modulus values determined by DSPI. With a view to monitoring the accuracy of the FEM models of the bone and the implant elements we designed a flexion experiment to obtain the DSPI values in and out of plane. The high degree of concordance between the results of both methods makes it possible to continue studying osseous samples with a fixed implant, and also other implants made of different alloys.

  10. Structural Analysis of Santa Cruz Island, Galapagos and Implications for Future Deformation

    Science.gov (United States)

    Schwartz, D. M.; Wilson, E. L.; Van Kirk, R.; Harpp, K.; Kattenhorn, S. A.

    2012-12-01

    Puerto Ayora is defined by two prominent faults, trending ~110 degrees with scarp heights of at least 30 m. Each fault is greater that 2 km in length and is composed of a number of linked segments. The Santa Cruz deformational structures, including prominent landslide scarps and normal faults, suggest that the current volcanic edifice may be unstable. We propose that these features are likely products of rift related normal faulting and flank failure, typical of large volcanoes. As there is evidence of significant deformational and mass wasting events in the past, there is a certain urgency to evaluate the island's future stability.

  11. Structural study of Zr-Cu-Ag bulk metallic glasses using the anomalous X-ray scattering method

    International Nuclear Information System (INIS)

    The structures of Zr45Cu45Ag10 and Zr40Cu40Ag20 bulk metallic glasses (BMGs) were investigated using the anomalous x-ray scattering and reverse Monte Carlo simulation (AXS-RMC) method. The fundamental structural features of Zr45Cu45Ag10 and Zr40Cu40Ag20 can be properly demonstrated through the common dense random packing of the hard spheres, and the addition of Ag appeared to result in no prominent formation of the particular chemical ordering units. A Voronoi analysis indicated that the fraction of the icosahedron-like coordination was the largest around the Cu in Zr45Cu45Ag10 BMG, where the best glass-forming ability was realized. The improvement in the glass-forming ability in a Zr-Cu-Ag system appears to be associated with the icosahedron-like local coordination.

  12. Study of local structure in hyper-eutectic Zr-Cu-Al bulk glassy alloys by positron annihilation techniques

    Science.gov (United States)

    Ishiyama, T.; Ishii, K.; Yokoyama, Y.; Konno, T. J.; Iwase, A.; Hori, F.

    2016-01-01

    The Zr-Cu-Al bulk glassy (BG) alloy, which has amorphous structure, possesses various properties such as high strength and toughness with compositional dependence. In the present study, density, positron annihilation lifetime and coincidence Doppler Broadening measurement have been performed for various compositional hyper-eutectic Zr-Cu-Al BG alloys. The density of hyper-eutectic Zr-Cu-Al BG alloys increases with decreasing of Zr fraction. In contrast, positron lifetime for all compositional alloys is almost constant about 165 psec. In addition, the CDB ratio profile is almost the same for hyper-eutectic alloys. This unchanging trend of CDB ratio profile is quite different from that of hypo-eutectic BG alloys. These results reveal that different internal structure exists in hyper and hypo-eutectic BG alloys.

  13. Growth and deformation structure of gradient and layer-gradient Ti-Al-Si-Cu-N coatings

    Energy Technology Data Exchange (ETDEWEB)

    Ovchinnikov, Stanislav V., E-mail: ovm@spti.tsu.ru; Pinzhin, Yurii P., E-mail: pinzhin@phys.tsu.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Korotaev, Alexandr D., E-mail: korotaev@phys.tsu.ru [National Research Tomsk State University, Tomsk, 634050 (Russian Federation)

    2014-11-14

    The features of the growth structure and modification of gradient and layer-gradient Ti-Al-Si-Cu-N coatings in the areas of deformation and fracture during indentation and scratch testing were investigated using transmission and scanning electron microscopy methods. The influence of the concentration of alloying elements and displacement potential in the substrate on the secondary sputtering, phase composition and the level of combined torsion and bending of the crystal lattice of doped TiN were determined. It was found out that the size of the crystals in deformation location bands grows with deformation of gradient nanocrystal coatings. The article shows that layer-gradient coatings combining submicrocrystalline and nanocrystalline structures have the increased plasticity and fracture toughness due to enhanced density of interfaces and formation of the soft metal phase (Cu) in the surface layer.

  14. Growth and deformation structure of gradient and layer-gradient Ti-Al-Si-Cu-N coatings

    International Nuclear Information System (INIS)

    The features of the growth structure and modification of gradient and layer-gradient Ti-Al-Si-Cu-N coatings in the areas of deformation and fracture during indentation and scratch testing were investigated using transmission and scanning electron microscopy methods. The influence of the concentration of alloying elements and displacement potential in the substrate on the secondary sputtering, phase composition and the level of combined torsion and bending of the crystal lattice of doped TiN were determined. It was found out that the size of the crystals in deformation location bands grows with deformation of gradient nanocrystal coatings. The article shows that layer-gradient coatings combining submicrocrystalline and nanocrystalline structures have the increased plasticity and fracture toughness due to enhanced density of interfaces and formation of the soft metal phase (Cu) in the surface layer

  15. Electronic structure of bulk ferromagnetic Ge0.86Mn0.14Te

    International Nuclear Information System (INIS)

    The electronic structure of polycrystalline Ge0.86Mn0.14Te-ferromagnetic semiconductor with TC=110 K, has been studied by means of resonant photoemission spectroscopy for photon energies close to the Mn 3p→3d excitation. The contribution of Mn 3d states to the electronic structure of the system was revealed and position of the Mn ions in the crystal, characteristic of GeTe-based diluted magnetic semiconductors was proved.

  16. Quantum mechanical ab initio calculations of the structural, electronic and optical properties of bulk gold nitrides

    Science.gov (United States)

    Suleiman, Mohammed S. H.; Joubert, Daniel P.

    2015-11-01

    In the present work, the atomic and the electronic structures of Au3N, AuN and AuN2 are investigated using first-principles density-functional theory (DFT). We studied cohesive energy vs. volume data for a wide range of possible structures of these nitrides. Obtained data were fitted to a Birch-Murnaghan third-order equation of state (EOS) so as to identify the most likely candidates for the true crystal structure in this subset of the infinite parameter space, and to determine their equilibrium structural parameters. The analysis of the electronic properties was achieved by the calculations of the band structure and the total and partial density of states (DOS). Some possible pressure-induced structural phase transitions have been pointed out. Further, we carried out GW0 calculations within the random-phase approximation (RPA) to the dielectric tensor to investigate the optical spectra of the experimentally suggested modification: Au3N(D09). Obtained results are compared with experiment and with some available previous calculations.

  17. Quantifying deformation in a magma reservoir - a rheology study of the Listino Ring Structure, Adamello Massif, N-Italy

    Science.gov (United States)

    Verberne, R.; Hodge, K. F.; Ulmer, P.; Muntener, O.

    2011-12-01

    The deformation and movement of magma in a reservoir during and after emplacement is vital for our understanding of the formation and evolution of such reservoirs. The general absence of marker beds and difficulties in interpreting foliation patterns [1] makes it difficult to trace and quantify deformation inside plutons. However, syn-plutonic dikes, sheets and enclaves can possibly be used as markers in order to quantify the deformation that occurred after the injection of magma from which they formed. Furthermore they provide a means to quantify the rheology of the magmas involved, providing quantitative insight into the deformation that goes on within magma chambers. A series of analog experiments [2] was conducted to mimic the deformation of a dike being injected into a crystal mush, using a cylindrical tank filled with corn syrup into which a tube of particle-fluid mixture is injected and subsequently sheared by rotating a rigid plate on top of the syrup. The experiments were designed to characterize the deformation of the tubes with respect to variations in yield strength of the injected material, buoyancy, and ambient flow behavior. Results show three possible deformation regimes: no break-up, boudinaged dikes or break up into enclaves. Here we present a case study of the Listino Ring Structure of the Adamello Batholith, N-Italy, where field evidence consisting of undeformed dikes to disaggregated dikes and sheets and enclave trains provides a clear indication of spatial and/or temporal changes of the deformation regime during pluton evolution. Both dike disaggregation and enclave formation were examined using equations derived from the experiments mentioned above, relating preserved length scales (dike width, enclave size) to the yield strength of the magmas and the chamber stirring velocity. This allows us to quantify the observed changes in the deformation regime in terms of changing magma rheology and strain rate. Results will be combined with petrologic

  18. Effect of cold deformation on structure and properties of aluminium alloy 1441 sheets

    International Nuclear Information System (INIS)

    The influence of tensile deformation on the 1441 alloy (Al-Cu-Mg-Li-Zr) in four states: quenched; quenched, straightened and naturally aged; annealed; quenched, straightened and artificially aged one, has been studied. It has been ascertained that deformation after quenching results in a considerable growth of yield strength. Artificial aging makes an insignificant contribution to stregthening of deformed sheet. 2 refs.; 4 figs

  19. Deformation-induced structural changes of amorphous Ni0.5Zr0.5 in molecular-dynamic simulations

    International Nuclear Information System (INIS)

    The present work investigates the plastic deformation of metallic glasses by the aid of molecular-dynamic simulations. The parameters for the model system are adapted to those for a NiZr-alloy. In particular, the composition Ni0.5Zr0.5 is used. The analyzed deformation simulations are conducted for small systems with 5184 atoms and large systems with 17500 atoms in a periodic simulation cell. The deformation simulations of pre-deformed samples are carried out either at constant shear-rate or at constant load, the latter mode modeling a creep experiment. Stress-strain curves for pre-deformed samples show a less pronounced stress-overshoot phenomenon. Creep-simulations of samples deformed beyond the yield region indicate a drastically reduced viscosity in these systems when compared to samples pre-deformed only up to the linear regime of the stress-strain curve. From analyzing the local atomic topology it is found that the transition from the highly viscous, hard-to-deform state of the undeformed or only weakly strained system into the easy-to-deform flow-state, present if the system is strained far beyond the yielding regime of the stress-strain curve, is connected with the formation of a region containing atoms with massive changes in their topology which is oriented along a diagonal plane of the simulation cell. The degree of localization of these deformation bands is influenced by temperature and shear-rate. In subsequent deformations of pre-deformed samples the regions with massive changes in the atomic topology are again susceptible to changes in the local atomic topology. By using methods from statistics, a significant difference in the distribution of atomic properties for the group of atoms with massive topology changes on the one hand and the group of atoms without changes in their topology on the other gets quantitatively ascertainable. From the differences in structural properties, e.g. potential energy, cage volumes, angular order parameters or atomic

  20. Structural and electrical properties of Si- and Ti-doped Cu2SnSe3 bulks

    Science.gov (United States)

    Wubet, Walelign; Kuo, Dong-Hau

    2015-07-01

    Silicon-doped (Cu2(Sn1-xSix)Se3 and titanium-doped (Cu2(Sn1-xTix)Se3 at x=0, 0.05, 0.1, 0.15, and 0.2 were prepared at 550 °C for 2 h with soluble sintering aids of volatile Sb2S3 and Te. Defect chemistry was studied by measuring structural and electrical properties of Si-doped and Ti-doped Cu2SnSe3 (CTSe) as a function of dopant concentration. Si-doped CTSe pellets show p-type at x=0 and 0.05 and n-type at x=0.1, 0.15, and 0.2, whereas Ti-doped CTSe pellets show p-type at x=0, 0.05 and 0.1 and n-type at x=0.15 and 0.2. The lowest hole concentration of 3.6×1017 cm-3 and the highest mobility of 1525 cm2 V-1 s-1 were obtained for the Si-doped (Cu2(Sn1-xSix)Se3 bulks at x=0.1 (10% Si), while they were 3.1×1017 cm-3 and 813 cm2 V-1 s-1 for the Ti-doped CTSe bulks at x=0.15 (15% Ti), as compared to 1.1×1018 cm-3 and 209 cm2 V-1 s-1 for undoped one. The explanations based upon antisite defects of Si-to-Sn, Ti-to-Sn, Cu-to-Sn, and Sn-to-Cu for the changes in electrical property were declared. The study in bulk Si-doped and Ti-doped CTSe is based upon defect state and is consistent and supported by the data of electrical property and lattice parameter.

  1. UMAT Implementation of Coupled, Multilevel, Structural Deformation and Damage Analysis of General Hereditary Materials

    Science.gov (United States)

    Arnold, S. M.; Saleeb, A. F.; Wilt, T. E.; Trowbridge, D.

    2000-01-01

    Extensive research efforts have been made over the years on the phenomenological representations of constitutive material behavior in the inelastic analysis and life assessment of structures composed of advanced monolithic and composite (CMC, MMC, and PMC) materials. Recently, emphasis has been placed on concurrently addressing three important and related areas of constitutive and degradation modeling; i.e. (i) mathematical formulation, (ii) algorithmic developments for the updating (integrating) of external (e.g. stress) and internal state variable, as well as (iii) parameter estimation for the characterization of the specific model. This concurrent perspective has resulted in; i) the formulation of a fully-associative viscoelastoplastic model (GVIPS), (ii) development of an efficient implicit integration and it's associative, symmetric, consistent tangent stiffness matrix algorithm for integration of the underlying rate flow/evolutionary equations, and iii) a robust, stand-alone, Constitutive Material Parameter Estimator (COMPARE) for automatically characterizing the various time-dependent, nonlinear, material models. Furthermore, to provide a robust multi-scale framework for the deformation and life analysis of structures composed of composite materials, NASA Glenn has aggressively pursued the development of a sufficiently general, accurate, and efficient micromechanics approach known as the generalized method of cells (GMC). This work has resulted in the development of MAC/GMC, a stand-alone micromechanics analysis tool that can easily and accurately design/analyze multiphase (composite) materials subjected to complex histories. MAC/GMC admits generalized, physically based, deformation and damage models for each constituent and provides "closed-form" expressions for the macroscopic composite response in terms of the properties, size, shape, distribution, and response of the individual constituents or phases that comprise the material. Consequently, MAC/GMC can

  2. Nanometer-Scale Heterogeneities of the Structure of Zirconium-Based Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Igor M. Mikhailovskij

    2012-11-01

    Full Text Available Structure of amorphous alloys ZrTiCuNiBe and ZrTiCuNiAl is studied by means of low-field ion and combined field-emission microscopy. In both alloys the structural heterogeneities of nanometer-scale are clearly revealed. The surface layers formed by field evaporation possess a cellular structure. The cells have polygonal shape with transverse size ranging from 2 nm to 20 nm. It is established that variance of the local energy of field evaporation is of 0%–5% in the cell body. A local minimum of the field evaporation energy is observed within the cell boundaries (intercluster boundaries. In the minimum the depth is measured to be of 0.8 eV.

  3. Relations between structural and superconducting properties of bulk and thin film high-Tc materials

    International Nuclear Information System (INIS)

    The structural ordering of oxygen deficient and Co-doped YBCO (YBa2Cu3-yCoyO6+x) have been studied experimentally, and by computer simulations of the oxygen ordering in the basal plane of the structure. The calculations are based on the two-dimensional ASYNNNI model and its modifications. Good agreement is established between the ASYNNNI calculations and the experimentally observed structural properties of the double cell ortho-II structure and the oxygen disordering process from Co-doping into the basal plane. A model that relates the superconducting transition temperature Tc(x) of undoped YBCO and Tc(y) of Co-doped YBCO to the formation of specific domains of the two orthorhombic ordered oxygen phases, ortho-I and ortho-II, shows a close agreement with experimental Tc(x) and Tc(y) data of samples prepared under equilibrium conditions. The structural changes as a result of metal ion substitutions and oxidation/reduction processes have been studied by neutron powder diffraction in Pb2Sr2Ln1-xCaxCu3O8+y (Ln = Y and Ho), Nd1.85Ce0.15CuO4+y, and chemically oxidized La2-xSrxCuO4+y 2Cu3-yAlyO6+x (y 2Cu3O6+x and Bi2Sr2CaCu2O8+x thin films deposited on SrTiO3 (001), MgO (001), LaAlO3 (001), and NdGaO3 (001) substrates has been studied by x-ray diffraction, TEM and RBS, and the structural ordering has been analysed in relation to their superconducting properties. (au) (30 ills., 29 refs.)

  4. Impact of acoustic velocity structure to measurement of ocean bottom crustal deformation

    Science.gov (United States)

    Ikuta, R.; Tadokoro, K.; Okuda, T.; Sugimoto, S.; Watanabe, T.; Eto, S.; Ando, M.

    2010-12-01

    We are developing a geodetic method of monitoring crustal deformation under the ocean using kinematic GPS and acoustic ranging. The goal of our research is to achieve sub-centimeter accuracy in measuring oceanic crustal deformation by a very short-time measurement like 10 hours. In this study, we focused on lateral variation of acoustic velocity structure in seawater and introduced an inclined acoustic velocity structure model to improve accuracy of the measurement. We have a few measurement sites along Nankai trough, Japan. In each sites, we deployed a trio of transponders on ocean floor (seafloor benchmark units) within distance comparable with the depth. An ultrasonic signal is generated from a surface vessel drifting over the benchmark unit, which is received and replied by the benchmark unit. In this system, both acoustic velocity structure and the benchmark unit positions were determined simultaneously for the each measurement using a tomographic technique. This tomographic technique was adopted on an assumption that the acoustic velocity structure is horizontally layered and changes only in time, not in space. Ikuta et al., (AGU fall meeting 2009) reported an approach to improve accuracy of benchmark positioning using a new additional assumption. The additional assumption was that the configuration of the transponders trio constituting one benchmark unit does not change. They determined the time evolution of weight center for the fixed transponder triangle between different measurements using all repetitively obtained data sets at once. This is contrasting to the previous method in which each data set for different measurement was solved independently. This assumption worked well in reducing number of unknown parameters. As a result, repeatability of benchmark positioning improved from 5 cm to 3 cm. We conducted numerical experiments synthesizing acoustic travel-time data to evaluate the robustness of this new approach. When acoustic travel-time data is

  5. The Hamiltonian structure of soliton equations and deformed scr(W)-algebras

    International Nuclear Information System (INIS)

    The Poisson bracket algebra corresponding to the second Hamiltonian structure of a large class of generalized KdV and mKdV integrable hierarchies is carefully analysed. These algebras are known to have conformal properties and their relation to scr(W)-algebras has been previously investigated in some particular cases. The class of equations that is considered includes practically all the generalizations of the Drinfel close-quote d endash Sokolov hierarchies constructed in the literature. In particular, it has been recently shown that it includes matrix generalizations of the Gelfand endash Dickey and the constrained KP hierarchies. Therefore, our results provide a unified description of the relation between the Hamiltonian structure of soliton equations and scr(W)-algebras, and it comprises almost all the results formerly obtained by other authors. The main result of this paper is an explicit general equation showing that the second Poisson bracket algebra is a deformation of the Dirac bracket algebra corresponding to the scr(W)-algebras obtained through Hamiltonian reduction. copyright 1997 Academic Press, Inc

  6. The Difference of Structural State and Deformation Behavior between Teenage and Mature Human Dentin.

    Science.gov (United States)

    Panfilov, Peter; Zaytsev, Dmitry; Antonova, Olga V; Alpatova, Victoria; Kiselnikova, Larissa P

    2016-01-01

    Objective. The cause of considerable elasticity and plasticity of human dentin is discussed in the relationship with its microstructure. Methods. Structural state of teenage and mature human dentin is examined by using XRD and TEM techniques, and their deformation behavior under compression is studied as well. Result. XRD study has shown that crystallographic type of calcium hydroxyapatite in human dentin (calcium hydrogen phosphate hydroxide Ca9HPO4(PO4)5OH; Space Group P63/m (176); a = 9,441 A; c = 6,881 A; c/a = 0,729; Crystallite (Scherrer) 200 A) is the same for these age groups. In both cases, dentin matrix is X-ray amorphous. According to TEM examination, there are amorphous and ultrafine grain phases in teenage and mature dentin. Mature dentin is stronger on about 20% than teenage dentin, while teenage dentin is more elastic on about 20% but is less plastic on about 15% than mature dentin. Conclusion. The amorphous phase is dominant in teenage dentin, whereas the ultrafine grain phase becomes dominant in mature dentin. Mechanical properties of human dentin under compression depend on its structural state, too. PMID:26989416

  7. Emergence of coherent localized structures in shear deformations of temperature dependent fluids

    KAUST Repository

    Katsaounis, Theodoros

    2014-11-22

    Shear localization occurs in various instances of material instability in solid mechanics and is typically associated with Hadamard-instability for an underlying model. While Hadamard instability indicates the catastrophic growth of oscillations around a mean state, it does not by itself explain the formation of coherent structures typically observed in localization. The latter is a nonlinear effect and its analysis is the main objective of this article. We consider a model that captures the main mechanisms observed in high strain-rate deformation of metals, and describes shear motions of temperature dependent non-Newtonian fluids. For a special dependence of the viscosity on the temperature, we carry out a linearized stability analysis around a base state of uniform shearing solutions, and quantitatively assess the effects of the various mechanisms affecting the problem: thermal softening, momentum diffusion and thermal diffusion. Then, we turn to the nonlinear model, and construct localized states - in the form of similarity solutions - that emerge as coherent structures in the localization process. This justifies a scenario for localization that is proposed on the basis of asymptotic analysis in \\\\cite{KT}.

  8. Nano-structuring, surface and bulk modification with a focused helium ion beam

    Directory of Open Access Journals (Sweden)

    Daniel Fox

    2012-08-01

    Full Text Available We investigate the ability of a focused helium ion beam to selectively modify and mill materials. The sub nanometer probe size of the helium ion microscope used provides lateral control not previously available for helium ion irradiation experiments. At high incidence angles the helium ions were found to remove surface material from a silicon lamella leaving the subsurface structure intact for further analysis. Surface roughness and contaminants were both reduced by the irradiation process. Fabrication is also realized with a high level of patterning acuity. Implantation of helium beneath the surface of the sample is visualized in cross section allowing direct observation of the extended effects of high dose irradiation. The effect of the irradiation on the crystal structure of the material is presented. Applications of the sample modification process are presented and further prospects discussed.

  9. Band structures tunability of bulk 2D phononic crystals made of magneto-elastic materials

    Directory of Open Access Journals (Sweden)

    J. O. Vasseur

    2011-12-01

    Full Text Available The feasibility of contactless tunability of the band structure of two-dimensional phononic crystals is demonstrated by employing magnetostrictive materials and applying an external magnetic field. The influence of the amplitude and of the orientation with respect to the inclusion axis of the applied magnetic field are studied in details. Applications to tunable selective frequency filters with switching functionnality and to reconfigurable wave-guides and demultiplexing devices are then discussed.

  10. Bulk properties and electronic structure of PuFeAsO

    Czech Academy of Sciences Publication Activity Database

    Klimczuk, T.; Shick, Alexander; Springell, R.; Walker, H.C.; Hill, A.H.; Colineau, E.; Griveau, J.C.; Bouexiere, D.; Eloirdi, R.; Caciuffo, R.

    2012-01-01

    Roč. 86, č. 17 (2012), "174510-1"-"174510-6". ISSN 1098-0121 R&D Projects: GA ČR(CZ) GAP204/10/0330; GA AV ČR IAA100100912 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetic materials * neutron scattering * electronic structure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.767, year: 2012

  11. Structural Factors That Affect the Performance of Organic Bulk Heterojunction Solar Cells

    KAUST Repository

    Vandewal, Koen

    2013-08-27

    The performance of polymer:fullerene solar cells is strongly affected by the active layer morphology and polymer microstructure. In this Perspective, we review ongoing research on how structural factors influence the photogeneration and collection of charge carriers as well as charge carrier recombination and the related open-circuit voltage. We aim to highlight unexplored research opportunities and provide some guidelines for the synthesis of new conjugated polymers for high-efficiency solar cells. © 2013 American Chemical Society.

  12. From monomer to bulk: appearance of the structural motif of solid iodine in small clusters.

    Science.gov (United States)

    Hulkko, Eero; Kiljunen, Toni; Kiviniemi, Tiina; Pettersson, Mika

    2009-01-28

    Formation of iodine clusters in a solid krypton matrix was studied using resonance Raman spectroscopy with a 1 cm(-1) resolution. The clusters were produced by annealing of the solid and recognized by appearance of additional spectral transitions. Two distinct regions, red-shifted from the fundamental vibrational wavenumber of the isolated I(2) at 211 cm(-1), were observed in the signal. The intermediate region spans the range 196-208 cm(-1), and the ultimate region consists of two peaks at 181 and 190 cm(-1) nearly identical to crystalline I(2). The experimental results were compared to DFT-D level electronic structure calculations of planar (I(2))(n) clusters (n = 1-7). The dimer, trimer, and tetramer structures, where the I(2) molecule is complexed from one end, were found to exhibit vibrational shifts corresponding to the intermediate size clusters. The larger, bulklike shift appears when the iodine molecule is coordinated from two opposite directions as in the case of a pentamer and higher clusters. Starting from the pentamer, the structural motif of crystalline iodine is clearly recognized in the clusters. PMID:19123809

  13. Internal state variable models for micro-structure in high temperature deformation of titanium alloys

    Institute of Scientific and Technical Information of China (English)

    LUO Jiao; LI MiaoQuan; LI XiaoLi

    2008-01-01

    There exists an interaction between microstructural evolution and deformation behavior in high temperature deformation of titanium alloys. And the microstruc-ture of titanium alloys is very sensitive to the process parameters of plastic de-formation process. In this paper, on the basis of plastic deformation mechanism of metals and alloys, a microstructural model including dislocation density rate equa-tion and grain growth rate equation is established with the dislocation density rate being an internal state variable. Applying the model to the high temperature de-formation process of Ti60 titanium alloy, the average relative errors of grain sizes between the experiments and the predictions are 9.47% for sampled data, and 13.01% for non-sampled data.

  14. Controlled Ag electroless deposition in bulk structures with complex three-dimensional profiles

    DEFF Research Database (Denmark)

    Malureanu, Radu; Zalkovskij, Maksim; Andryieuski, Andrei;

    2010-01-01

    In this work we show the possibility of controlled deposition of a nanometer-sized silver layer on three-dimensional 3D structures. The deposition takes place in liquid environment, allowing for an easy and fast processing with intrinsically isotropic characteristics. The obtained layers are of...... high uniformity, having an average roughness of about 4 nm. The characterization of the metal deposition is done using both the scanning electron microscopy technique as well as by atomic force microscope measurements. The electroless technique can be easily implemented, providing the effective and...... reliable metal deposition for fabrication of 3D samples in the broad range of plasmonics and photonics applications....

  15. Formation of SiNx:H by PECVD: optimization of the optical, bulk passivation and structural properties for photovoltaic applications

    International Nuclear Information System (INIS)

    The hydrogenated silicon nitride SiNx:H is widely used as antireflection coating and passivation layer in the manufacture of silicon photovoltaic cells. The aim of this work was to implement a low frequency (440 kHz) PECVD reactor and to characterize the obtained SiN layers. After having determined the parameters of the optimal deposition, the physico-chemical structure of the layers has been studied. The optical properties have been studied with the aim to improve the antireflection coating of the photovoltaic cells. The surface and bulk passivation properties, induced by the SiN layer in terms of its stoichiometry, have been analyzed and have revealed the excellent passivating efficiency of this material. At last, have been studied the formation conditions of the silicon nano-crystals in the SiN matrix. (O.M.)

  16. Studies on bulk growth, structural and microstructural characterization of 4-aminobenzophenone single crystal grown from vertical Bridgman technique

    Indian Academy of Sciences (India)

    S P Prabhakaran; R Ramesh Babu; G Bhagavannarayana; K Ramamurthi

    2014-02-01

    Bulk single crystal of 4-aminobenzophenone with a size of 25 mm dia. and 35 mm length has been grown by vertical Bridgman technique. The crystal system of the grown crystal was confirmed by X-ray diffraction analysis. Crystalline perfection was analysed by high resolution X-ray diffraction studies. Chemical etching was carried out for the first time in 4-aminobenzophenone single crystal to study the defects presented in the grown crystal and the growth mechanism involved. Several organic etchants were employed with different etching time to select suitable etchant for studying dislocation pattern and other structural defects existing in the grown crystal. Etch patterns such as spirals and striations observed for the selective etchants provide considerable information on growth mechanism of the crystal.

  17. Structure-induced resonant tail-state regime absorption in polymer: fullerene bulk-heterojunction solar cells

    Science.gov (United States)

    Pfadler, Thomas; Kiel, Thomas; Stärk, Martin; Werra, Julia F. M.; Matyssek, Christian; Sommer, Daniel; Boneberg, Johannes; Busch, Kurt; Weickert, Jonas; Schmidt-Mende, Lukas

    2016-05-01

    In this work, we present resonant tail-state regime absorption enhanced organic photovoltaics. We combine periodically structured TiO2 bottom electrodes with P3HT-PCBM bulk-heterojunction solar cells in an inverted device configuration. The wavelength-scale patterns are transferred to the electron-selective bottom electrodes via direct laser interference patterning, a fast method compatible with roll-to-roll processing. Spectroscopic and optoelectronic device measurements suggest polarization-dependent absorption enhancement along with photocurrent generation unambiguously originating from the population of tail states. We discuss the effects underlying these absorption patterns with the help of electromagnetic simulations using the discontinuous Galerkin time domain method. For this, we focus on the total absorption spectra along with spatially resolved power loss densities. Our simulations stress the tunability of the absorption resonances towards arbitrary wavelength regions.

  18. Dominance of interface chemistry over the bulk properties in determining the electronic structure of epitaxial metal/perovskite oxide heterojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, Scott A.; Du, Yingge; Gu, Meng; Droubay, Timothy C.; Hepplestone, Steven; Sushko, Petr

    2015-06-09

    We show that despite very similar crystallographic properties and work function values in the bulk, epitaxial Fe and Cr metallizations on Nb:SrTiO3(001) generate completely different heterojunction electronic properties. Cr is Ohmic whereas Fe forms a Schottky barrier with a barrier height of 0.50 eV. This contrast arises because of differences in interface chemistry. In contrast to Cr [Chambers, S. A. et al., Adv. Mater. 2013, 25, 4001.], Fe exhibits a +2 oxidation state and occupies Ti sites in the perovskite lattice, resulting in negligible charge transfer to Ti, upward band bending, and Schottky barrier formation. The differences between Cr and Fe are understood by performing first-principles calculations of the energetics of defect formation which corroborate the observed interface chemistry and structure.

  19. Electronic structure of reconstructed InAs(001) surfaces - identification of bulk and surface bands based on their symmetries

    Science.gov (United States)

    Olszowska, Natalia; Kolodziej, Jacek J.

    2016-02-01

    Using angle-resolved photoelectron spectroscopy (ARPES) band structures of indium- and arsenic-terminated InAs(001) surfaces are investigated. These surfaces are highly reconstructed, elementary cells of their lattices contain many atoms in different chemical configurations, and moreover, they are composed of domains having related but different reconstructions. These domain-type surface reconstructions result in the reciprocal spaces containing regions with well-defined k→∥-vector and regions with not-well-defined one. In the ARPES spectra most of the surface related features appear as straight lines in the indeterminate k→∥-vector space. It is shown that, thanks to differences in crystal and surface symmetries, the single photon energy ARPES may be successfully used for classification of surface and bulk bands of electronic states on complex, highly reconstructed surfaces instead of the most often used variable photon energy studies.

  20. Atomic-Scale Structural Evolution and Stability of Supercooled Liquid of a Zr-Based Bulk Metallic Glass

    International Nuclear Information System (INIS)

    In this Letter, direct experimental evidence is provided for understanding the thermal stability with respect to crystallization in the Zr41.2Ti13.8Cu12.5Ni10Be22.5 glass-forming liquid. Through high-resolution transmission electron microscopy, the atomic-structure evolution in the glass-forming liquid during the isothermal annealing process is clearly revealed. In contrast with the existing theoretical models, our results reveal that, prior to nanocrystallization, there exists a metastable state prone to forming icosahedralike atomic clusters, which impede the subsequent crystallization and hence stabilize the supercooled liquid. The outcome of the current research underpins the topological origin for the excellent thermal stability displayed by the Zr-based bulk metallic glass.

  1. A hybrid-exchange density functional study of the bonding and electronic structure in bulk CuFeS2

    Science.gov (United States)

    Martínez-Casado, Ruth; Chen, Vincent H.-Y.; Mallia, Giuseppe; Harrison, Nicholas M.

    2016-05-01

    The geometric, electronic, and magnetic properties of bulk chalcopyrite CuFeS2 have been investigated using hybrid-exchange density functional theory calculations. The results are compared with available theoretical and experimental data. The theoretical description of the bonding and electronic structure in CuFeS2 is analyzed in detail and compared to those computed for chalcocite (CuS2) and greigite (Fe3S4). In particular, the behavior of the 3d electrons of Fe3+ is discussed in terms of the Hubbard-Anderson model in the strongly correlated regime and found to be similarly described in both materials by an on-site Coulomb repulsion (U) of ˜8.9 eV and a transfer integral (t) of ˜0.3 eV.

  2. Direct band gap electroluminescence from bulk germanium at room temperature using an asymmetric fin type metal/germanium/metal structure

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dong, E-mail: wang.dong.539@m.kyushu-u.ac.jp; Maekura, Takayuki; Kamezawa, Sho [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Yamamoto, Keisuke; Nakashima, Hiroshi [Art, Science and Technology Center for Cooperative Research, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan)

    2015-02-16

    We demonstrated direct band gap (DBG) electroluminescence (EL) at room temperature from n-type bulk germanium (Ge) using a fin type asymmetric lateral metal/Ge/metal structure with TiN/Ge and HfGe/Ge contacts, which was fabricated using a low temperature (<400 °C) process. Small electron and hole barrier heights were obtained for TiN/Ge and HfGe/Ge contacts, respectively. DBG EL spectrum peaked at 1.55 μm was clearly observed even at a small current density of 2.2 μA/μm. Superlinear increase in EL intensity was also observed with increasing current density, due to superlinear increase in population of elections in direct conduction band. The efficiency of hole injection was also clarified.

  3. Structure, strength, and electric conductivity of a Cu-Cr copper-based alloy subjected to severe plastic deformation

    Science.gov (United States)

    Islamgaliev, R. K.; Nesterov, K. M.; Valiev, R. Z.

    2015-02-01

    The effect of severe plastic deformation on the structure, strength, and electric conductivity of a Cu-Cr copper-based alloy has been studied. In ultrafine-grained specimens produced by severe plastic deformation by torsion and equal-channel angular pressing, the average grain size has been determined and particles of precipitates have been identified. The dependences of the strength and electric conductivity on conditions of severe plastic deformation and subsequent heat treatment have been assessed. The effect of dynamic aging in the Cu-Cr alloy has been found that leads to an increase in both the strength and the electric conductivity. It has been found that the ultrafine-grained alloy can demonstrate a combination of a high ultimate strength (790-845 MPa) and an increased electric conductivity (81-85% IACS).

  4. Molecular Dynamics Simulation of Structural Characterization of Elastic and Inelastic Deformation in ZrCu Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Shidong Feng

    2014-01-01

    Full Text Available The nanoscopic deformation behaviors in a ZrCu metallic glass model during loading-unloading process under uniaxial compression have been analyzed on the basis of the molecular dynamics (MD. The reversible degree of shear origin zones (SOZs is used as the structural indicator to distinguish the elastic deformation and inelastic deformation of ZrCu metallic glass at the atomic level. We find that the formation of SOZs is reversible at the elastic stage but irreversible at the inelastic stage during the loading and unloading processes. At the inelastic stage, the full-icosahedra fraction in SOZs is quickly reduced with increased strain and the decreasing process is also irreversible during the unloading processes.

  5. Effect of severe plastic deformation on structural and phase transformations in Fe-Ni-Co-V-Mo maraging alloys

    International Nuclear Information System (INIS)

    By means of even-channel angular (ECA) compacting method one investigated into the effect of severe plastic deformation on structure and physical-and-mechanical properties of Fe-15%Ni-10%Co-5%Mo-5%V maraging alloy. Relaxation processes reducing essentially the level of internal stresses and the value of coercive force are shown to be of considerable importance in deformation. It is revealed that concentration of submicropores reaches very high value in the process of severe plastic deformation, and it results in about 0.5% increase of the parameter of α-phase crystalline lattice. One believes that applying adequate set of the ECA-compacting modes followed by tempering one may produce hybrid maraging alloys with the optimal combination of strength and magnetically hard properties

  6. Peculiarities of the structure, its deformation and destruction of condensed Cu-Mo-Zr-Y composite material of commercial purity

    Directory of Open Access Journals (Sweden)

    Mamuzić, I.

    2008-04-01

    Full Text Available The peculiarities of the morphology and structure defects of composite material in the Cu-Mo-Zr-Y system produced from commercially pure raw materials using method of electron-beam evaporation/condensation have been studied. The features of deformation and destruction of the composite have been investigated alongside with its mechanical properties and their change under action of structure defects.

  7. Bulk and interfacial molecular structure near liquid-liquid critical points

    Energy Technology Data Exchange (ETDEWEB)

    Manzanares-Papayanopoulos, Emilio

    2000-09-01

    Critical behaviour occurs when two coexisting phases merge identity without abrupt change in physical properties. The detail of this behaviour is nowadays considered universal, being dominated by the divergence of the correlation length {xi}. Following this universality, the detailed behaviour can be studied experimentally using any convenient system. For that reason, the study of fluids, and in particular fluid mixtures, offers a useful platform since critical behaviour in such systems can often be studied at convenient temperatures and pressures. Although criticality is a consequence of the divergence of {xi}, and so in a sense is a large-scale phenomenon, nevertheless it has an influence on events at molecular level. This aspect of criticality has received relatively little study compared to the enormous effort expended over the past thirty years in elucidating the macroscopic or phenomenological aspects of criticality. The signature of criticality at molecular level is the central theme running through this research.The aim of the work described in this thesis was to investigate the surface and transport properties of near-critical binary liquid mixtures. The surface properties mainly concerned the adsorption and wetting behaviour at the vapour-liquid and liquid-solid interfaces. The transport property studied was the shear viscosity at bulk or macroscopic level and the corresponding property at molecular or microscopic level, the micro viscosity. The work presented in this thesis comprises the experimental measurements and the theoretical interpretations drawn from the results. The experimental work was varied, using both classical and modern techniques. The theoretical interpretation was used as directed towards validating and comparing the results of the experimental programme with the predictions of the current classical critical-state theories. The systems investigated have been mostly alkane + perfluoroalkane mixtures or mixtures with very similar

  8. Electronic Structure of Fullerene Acceptors in Organic Bulk-Heterojunctions. A Combined EPR and DFT Study

    Energy Technology Data Exchange (ETDEWEB)

    Mardis, Kristy L. [Chicago State Univ., IL (United States); Webb, J. [Chicago State Univ., IL (United States); Holloway, Tarita [Chicago State Univ., IL (United States); Niklas, Jens [Argonne National Lab. (ANL), Argonne, IL (United States); Poluektov, Oleg G. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-11-16

    Organic photovoltaic (OPV) devices are a promising alternative energy source. Attempts to improve their performance have focused on the optimization of electron-donating polymers, while electron-accepting fullerenes have received less attention. Here, we report an electronic structure study of the widely used soluble fullerene derivatives PC61BM and PC71BM in their singly reduced state, that are generated in the polymer:fullerene blends upon light-induced charge separation. Density functional theory (DFT) calculations characterize the electronic structures of the fullerene radical anions through spin density distributions and magnetic resonance parameters. The good agreement of the calculated magnetic resonance parameters with those determined experimentally by advanced electron paramagnetic resonance (EPR) allows the validation of the DFT calculations. Thus, for the first time, the complete set of magnetic resonance parameters including directions of the principal g-tensor axes were determined. For both molecules, no spin density is present on the PCBM side chain, and the axis of the largest g-value lies along the PCBM molecular axis. While the spin density distribution is largely uniform for PC61BM, it is not evenly distributed for PC71BM.

  9. Electronic Structure of Fullerene Acceptors in Organic Bulk-Heterojunctions: A Combined EPR and DFT Study.

    Science.gov (United States)

    Mardis, Kristy L; Webb, Jeremy N; Holloway, Tarita; Niklas, Jens; Poluektov, Oleg G

    2015-12-01

    Organic photovoltaic (OPV) devices are a promising alternative energy source. Attempts to improve their performance have focused on the optimization of electron-donating polymers, while electron-accepting fullerenes have received less attention. Here, we report an electronic structure study of the widely used soluble fullerene derivatives PC61BM and PC71BM in their singly reduced state, that are generated in the polymer:fullerene blends upon light-induced charge separation. Density functional theory (DFT) calculations characterize the electronic structures of the fullerene radical anions through spin density distributions and magnetic resonance parameters. The good agreement of the calculated magnetic resonance parameters with those determined experimentally by advanced electron paramagnetic resonance (EPR) allows the validation of the DFT calculations. Thus, for the first time, the complete set of magnetic resonance parameters including directions of the principal g-tensor axes were determined. For both molecules, no spin density is present on the PCBM side chain, and the axis of the largest g-value lies along the PCBM molecular axis. While the spin density distribution is largely uniform for PC61BM, it is not evenly distributed for PC71BM. PMID:26569578

  10. Structure and performance of polymer-derived bulk ceramics determined by method of filler incorporation

    International Nuclear Information System (INIS)

    The effect of four distinct methods of incorporating fillers into a preceramic polymer matrix was investigated with respect to the structural and mechanical properties of the resulting materials. Investigations were conducted with a polysiloxane/Al2O3/ZrO2 model system used as a precursor for mullite/ZrO2 composites. A quantitative evaluation of the uniformity of filler distribution was obtained by employing a novel image analysis. While solvent-free mixing led to a heterogeneous distribution of constituents resulting in limited mechanical property values, a strong improvement of material homogeneity and properties was obtained by using solvent-assisted methods. The results demonstrate the importance of the processing route on final characteristics of polymer-derived ceramics

  11. Structure and performance of polymer-derived bulk ceramics determined by method of filler incorporation

    Science.gov (United States)

    Konegger, T.; Schneider, P.; Bauer, V.; Amsüss, A.; Liersch, A.

    2013-12-01

    The effect of four distinct methods of incorporating fillers into a preceramic polymer matrix was investigated with respect to the structural and mechanical properties of the resulting materials. Investigations were conducted with a polysiloxane/Al2O3/ZrO2 model system used as a precursor for mullite/ZrO2 composites. A quantitative evaluation of the uniformity of filler distribution was obtained by employing a novel image analysis. While solvent-free mixing led to a heterogeneous distribution of constituents resulting in limited mechanical property values, a strong improvement of material homogeneity and properties was obtained by using solvent-assisted methods. The results demonstrate the importance of the processing route on final characteristics of polymer-derived ceramics.

  12. Structural peculiarities and point defects of bulk-ZnO single crystals

    International Nuclear Information System (INIS)

    Highlights: • ZnO single crystals of different color were grown by the hydrothermal method. • Point defects in ZnO have been firstly investigated by neutron diffraction. • Presence of additional reflections caused by kinetic growth effects was revealed. • The relationship between the color and zinc and oxygen vacancies was found. • Photoinduced variation of transmittance versus the CW laser intensity was analyzed. - Abstract: ZnO single crystals are related to promising direct wide band gap semiconductor materials belonging to the AIIBVI type of compounds with wurtzite structure. “Unintentional” n-type conductivity in ZnO may be caused by zinc and oxygen vacancies, and interstitial zinc atoms. To date, the comprehensive structural investigation and analysis of point defects in ZnO is absent in literature. Green, light green and almost colorless ZnO single crystals grown by the hydrothermal method in concentrated alkali solutions 4M(KOH) + 1M(LiOH) + 0.1M(NH4OH) on monohedral seeds [0 0 0 1] at crystallization temperatures in the range of 330–350 °C and pressures in the range of 30–50 MPa have been firstly investigated by neutron diffraction. It was revealed the presence of additional reflections (∼12–∼16%) for all the crystals caused by kinetic growth effects that give grounds to assign them to the space group P3 rather than to P63mc. Analysis of the refined compositions together with the color of ZnO crystals does not rule out the relationship between the color and vacancies in the zinc and oxygen positions whose concentration decreases with the discoloration of the samples. The analysis of the photoinduced variation of the total and on-axis transmittance versus the CW laser intensity showed that the colored samples have profound deep defects related to oxygen vacancies

  13. Determination of the object surface function by structured light: application to the study of spinal deformities

    International Nuclear Information System (INIS)

    The projection of structured light is a technique frequently used to determine the surface shape of an object. In this paper, a new procedure is described that efficiently resolves the correspondence between the knots of the projected grid and those obtained on the object when the projection is made. The method is based on the use of three images of the projected grid. In two of them the grid is projected over a flat surface placed, respectively, before and behind the object; both images are used for calibration. In the third image the grid is projected over the object. It is not reliant on accurate determination of the camera and projector pair relative to the grid and object. Once the method is calibrated, we can obtain the surface function by just analysing the projected grid on the object. The procedure is especially suitable for the study of objects without discontinuities or large depth gradients. It can be employed for determining, in a non-invasive way, the patient's back surface function. Symmetry differences permit a quantitative diagnosis of spinal deformities such as scoliosis. (author)

  14. Calcium Sulfoaluminate Sodalite (Ca 4 Al 6 O 12 SO 4 ) Crystal Structure Evaluation and Bulk Modulus Determination

    KAUST Repository

    Hargis, Craig W.

    2013-12-12

    The predominant phase of calcium sulfoaluminate cement, Ca 4(Al6O12)SO4, was investigated using high-pressure synchrotron X-ray diffraction from ambient pressure to 4.75 GPa. A critical review of the crystal structure of Ca4(Al 6O12)SO4 is presented. Rietveld refinements showed the orthorhombic crystal structure to best match the observed peak intensities and positions for pure Ca4(Al6O 12)SO4. The compressibility of Ca4(Al 6O12)SO4 was studied using cubic, orthorhombic, and tetragonal crystal structures due to the lack of consensus on the actual space group, and all three models provided similar results of 69(6) GPa. With its divalent cage ions, the bulk modulus of Ca4(Al6O 12)SO4 is higher than other sodalites with monovalent cage ions, such as Na8(AlSiO4)6Cl2 or Na8(AlSiO4)6(OH)2·H 2O. Likewise, comparing this study to previous ones shows the lattice compressibility of aluminate sodalites decreases with increasing size of the caged ions. Ca4(Al6O12)SO4 is more compressible than other cement clinker phases such as tricalcium aluminate and less compressible than hydrated cement phases such as ettringite and hemicarboaluminate. © 2013 The American Ceramic Society.

  15. Flat structures on Frobenius Manifolds in the case of irrelevant deformations

    CERN Document Server

    Belavin, A

    2016-01-01

    In this paper we use the recently suggested conjecture about the integral representation for the flat coordinates on Frobenius manifolds, connected with the isolated singularities, to compute the flat coordinates and Saito primitive form on the space of the deformations of Gepner chiral ring $\\widehat{SU}(3)_4$. We verify this conjecture comparing the expressions for the flat coordinates obtained from the conjecture with the one found by direct computation. The considered case is of a particular interest since together with the relevant and marginal deformations it has one irrelevant deformation.

  16. Local structure controls the nonaffine shear and bulk moduli of disordered solids

    Science.gov (United States)

    Schlegel, M.; Brujic, J.; Terentjev, E. M.; Zaccone, A.

    2016-01-01

    Paradigmatic model systems, which are used to study the mechanical response of matter, are random networks of point-atoms, random sphere packings, or simple crystal lattices; all of these models assume central-force interactions between particles/atoms. Each of these models differs in the spatial arrangement and the correlations among particles. In turn, this is reflected in the widely different behaviours of the shear (G) and compression (K) elastic moduli. The relation between the macroscopic elasticity as encoded in G, K and their ratio, and the microscopic lattice structure/order, is not understood. We provide a quantitative analytical connection between the local orientational order and the elasticity in model amorphous solids with different internal microstructure, focusing on the two opposite limits of packings (strong excluded-volume) and networks (no excluded-volume). The theory predicts that, in packings, the local orientational order due to excluded-volume causes less nonaffinity (less softness or larger stiffness) under compression than under shear. This leads to lower values of G/K, a well-documented phenomenon which was lacking a microscopic explanation. The theory also provides an excellent one-parameter description of the elasticity of compressed emulsions in comparison with experimental data over a broad range of packing fractions.

  17. Effect of bimodal harmonic structure design on the deformation behaviour and mechanical properties of Co-Cr-Mo alloy.

    Science.gov (United States)

    Vajpai, Sanjay Kumar; Sawangrat, Choncharoen; Yamaguchi, Osamu; Ciuca, Octav Paul; Ameyama, Kei

    2016-01-01

    In the present work, Co-Cr-Mo alloy compacts with a unique bimodal microstructural design, harmonic structure design, were successfully prepared via a powder metallurgy route consisting of controlled mechanical milling of pre-alloyed powders followed by spark plasma sintering. The harmonic structured Co-Cr-Mo alloy with bimodal grain size distribution exhibited relatively higher strength together with higher ductility as compared to the coarse-grained specimens. The harmonic Co-Cr-Mo alloy exhibited a very complex deformation behavior wherein it was found that the higher strength and the high retained ductility are derived from fine-grained shell and coarse-grained core regions, respectively. Finally, it was observed that the peculiar spatial/topological arrangement of stronger fine-grained and ductile coarse-grained regions in the harmonic structure promotes uniformity of strain distribution, leading to improved mechanical properties by suppressing the localized plastic deformation during straining. PMID:26478398

  18. Study of the deformed structures in the reaction 123Sb + 37Cl at 190 MeV

    International Nuclear Information System (INIS)

    The aim of the present work is a search for the link between a dynamic deformation in a hot system at high spin in fusion evaporation reaction and a static deformation in cold system formed after emission of few charged particles from the compound system. It is a great interest to understand and to test experimentally if the population of high spin hyper-deformed structures is related to the emission of charged particles. For our study we have used the system 37Cl + 123Sb at 190 MeV incident energy provided by VIVITRON to obtain the compound nucleus 160Er. The charge particles and the gamma transitions occurring in the compound nucleus decay were observed by the experimental set-up resulting of the association of multidetectors DIAMANT and EUROGAM II. The reaction chains dominant in this experiment are (p5n) and (α4n). The experimental data analysis is under way and a particular care was attached to correct in an optimal mode for the Doppler shift due to the emission of charged particles for these reactions where the recoil velocity of the residual nucleus can reach an important value (β ∼ 3%). Given the very poor feeding of the hyper-deformed structure this method should improve very significant the observational limits

  19. Bulk nanoscale materials in steel products

    International Nuclear Information System (INIS)

    Although a number of nanoscale metallic materials exhibit interesting mechanical properties the fabrication paths are often complex and difficult to apply to bulk structural materials. However a number of steels which exhibit combinations of plasticity and phase transitions can be deformed to produce ultra high strength levels in the range 1 to 3 GPa. The resultant high stored energy and complex microstructures allow new nanoscale structures to be produced by combinations of recovery and recrystallisation. The resultant structures exhibit totally new combinations of strength and ductility to be achieved. In specific cases this also enables both the nature of the grain boundary structure and the spatial variation in structure to be controlled. In this presentation both the detailed microstructural features and their relation to the strength, work-hardening capacity and ductility will be discussed for a number of martensitic and austenitic steels.

  20. Review of the Structure of Bulk Power Markets Grid of the Future White Paper

    Energy Technology Data Exchange (ETDEWEB)

    Kirby, B.J.

    2000-05-02

    This paper is intended to provide an understanding of the needs of a restructured electricity market and some of the market methods and systems that have developed to address those needs. Chapter 2 discusses the historic market framework of vertically integrated utilities. Chapter 3 introduces the changes to the vertically integrated utility brought about by restructuring. It discusses generation and transmission planning, control and the regulatory process. It also summarizes reliability, security and adequacy. Chapter 4 discusses the basic structures of generation and transmission markets along with transmission-congestion contracts (TCCs) and transmission pricing principles. A discussion is given of the 12 ancillary services needed to reliably operate the power system. Chapter 4 also deals with the role of transmission in opening up markets to competition. In California increments (incs) and decrements (decs) are bid to overcome price differences in different zones caused by congestion. In PJM, any member can purchase Fixed Transmission Rights (FTRs) which allows the member to ''collect rent'' on congested lines and essentially obtain a hedge against congestion. There has been a worrisome slowdown in the growth of the transmission system in the United States since about the mid 70's. However, there are methods for providing incentives for construction of new transmission using tariffs. The California and PJM transmission planning processes are outlined. The Federal Energy Regulatory Commission (FERC) has recently issued a proposed rulemaking on Regional Transmission Organizations (RTOs) which stated that the traditional methods of grid management are showing signs of strain and may be inadequate to support efficient and reliable transmission operations. Chapter 5 provides examples of market implementations and a discussion of the price spikes seen in the Midwest in the summers of 1998 and 1999. An examination of six restructured market

  1. Cone-beam computed tomography based evaluation of rotational patterns of dentofacial structures in skeletal Class III deformity with mandibular asymmetry

    OpenAIRE

    Ryu, Hyeong-Seok; An, Ki-Yong; Kang, Kyung-Hwa

    2015-01-01

    Objective The purpose of this study was to assess rotational patterns of dentofacial structures according to different vertical skeletal patterns by cone-beam computed tomography (CBCT) and analyze their influence on menton deviation in skeletal Class III deformity with mandibular asymmetry. Methods The control group consisted of 30 young adults (15 men, 15 women) without any severe skeletal deformity. The asymmetry group included 55 adults (28 men, 27 women) with skeletal Class III deformity...

  2. Enhanced surface photovoltage response of ZnO nanorod based inorganic/organic hybrid junctions by constructing embedded bulk composite structures

    Science.gov (United States)

    Kang, Dawei; Liu, Aimin; Bian, Jiming; Hu, Zengquan; Liu, Yiting; Qiao, Fen

    2013-02-01

    Two kinds of inorganic/organic hybrid junctions based on ZnO nanorods (NRs), i.e. two-layer planar heterojunction and embedded bulk composite structures, were fabricated on ITO glass substrates. Surface photovoltage (SPV) methods based on a Kelvin probe and a lock-in amplifier were respectively utilized to study the photogenerated charges at the surface and the interface in the ZnO-based hybrid junctions. Results indicate that the lock-in SPV response of the bulk composite structure is much higher than its planar counterpart in terms of intensity and spectral range. Therefore, ZnO NR/PF (poly(9,9-di-n-octylfluorenyl-2,7-diyl)) embedded bulk composite structures are more suitable and preferred for photovoltaic application.

  3. Large-scale structure challenges dilaton gravity in a 5D brane scenario with AdS bulk

    International Nuclear Information System (INIS)

    We study a theory of dilaton gravity in a five-dimensional brane scenario, with a non-minimal coupling of the dilaton to the matter content of the universe localized on the brane. The effective gravitational equations at the brane are derived in the Einstein frame in the covariant approach, addressing certain misconceptions in the literature. We then investigate whether the observed large-scale structure of the universe can exist on the brane in this dilaton gravity scenario with an exact anti de Sitter bulk, assuming that the matter energy–momentum tensor has the form of an inhomogeneous perfect fluid. The corresponding constraint on the spatial derivative of the matter energy density is derived, and subsequently quantified using the current limits resulting from searches for variation of the Newton's constant. By confronting it with the observational data from galaxy surveys, we show that up to scales of the order of 104 Mpc, the derived bound on the spatial derivative of the matter energy density does not allow for the existence of the large-scale structure as observed today. Thus, such a dilaton gravity brane scenario is ruled out. (paper)

  4. Refinement of atomic and magnetic structures using neutron diffraction for synthesized bulk and nano-nickel zinc gallate ferrite

    Science.gov (United States)

    Ata-Allah, S. S.; Balagurov, A. M.; Hashhash, A.; Bobrikov, I. A.; Hamdy, Sh.

    2016-01-01

    The parent NiFe2O4 and Zn/Ga substituted spinel ferrite powders have been prepared by solid state reaction technique. As a typical example, the Ni0.7Zn0.3Fe1.5Ga0.5O4 sample has been prepared by sol-gel auto combustion method with the nano-scale crystallites size. X-ray and Mössbauer studies were carried out for the prepared samples. Structure and microstructure properties were investigated using the time-of-flight HRFD instrument at the IBR-2 pulsed reactor, at a temperatures range 15-473 K. The Rietveld refinement of the neutron diffraction data revealed that all samples possess cubic symmetry corresponding to the space group Fd3m. Cations distribution show that Ni2+ is a complete inverse spinel ion, while Ga3+ equally distributed between the two A and B-sublattices. The level of microstrains in bulk samples was estimated as very small while the size of coherently scattered domains is quite large. For nano-structured sample the domain size is around 120 Å.

  5. Thermoelectric power factor enhancement of AZO/In-AZO quantum well multilayer structures as compared to bulk films

    International Nuclear Information System (INIS)

    Highlights: ► Al-doped Zno/(In, Al)-co-doped ZnO quantum wells were deposited via sputtering. ► Multilayers were verified to be poly-crystalline with low interface roughness. ► Quantum well structure reduced electrical resistivity and enhanced Seebeck coeff. ► Thermopower is increased by 3x at 650 K for 2 at.% indium doped quantum wells. ► A model is derived to correlate interface roughness and thermoelectric performance. - Abstract: This study investigates and demonstrates the enhancement in thermoelectric power factor for n-type AlZnO/InAlZnO multilayer quantum wells as compared to their counterpart bulk films. A 10–20% improvement is observed for operating temperatures <700 °C. Fabricated structures are composed of 50 periods, with targeted individual layer thicknesses of 10 nm. The best performing multilayer shows an electrical resistivity and Seebeck coefficient of 1000 μV/K and at 700 °C. In addition, a theoretical relationship is derived between the thermoelectric performance and correlating microstructure that demonstrates the deterioration of electronic transport properties at increased interface roughness levels. To determine the microstructure and interface roughness of the films, X-ray and spectroscopy techniques were used. The proposed model is based on how quantum well-width fluctuations caused by increased interface roughness leads to the localization of carriers and thus a decrease in electrical conductivity.

  6. Influence of bulk pre-straining on the size effect in nickel compression pillars

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, A.S., E-mail: Andreas.schneider@inm-gmbh.de [INM-Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbruecken (Germany); Kiener, D. [University of Leoben, Department of Materials Physics, Jahnstr. 12, 8700 Leoben (Austria); Yakacki, C.M. [Department of Mechanical Engineering, University of Colorado Denver, Denver 80217 (United States); Maier, H.J. [University of Paderborn, Lehrstuhl fuer Werkstoffkunde (Materials Science), 33098 Paderborn (Germany); Gruber, P.A. [Karlsruhe Institute of Technology, Institute for Applied Materials, Kaiserstr. 12, 76131 Karlsruhe (Germany); Tamura, N.; Kunz, M. [Advanced Light Source (ALS), Lawrence Berkeley National Laboratory (LBNL), 1 Cyclotron Road, Berkeley, CA 94720 (United States); Minor, A.M. [Department of Materials Science and Engineering, University of California, Berkeley, and National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Frick, C.P. [University of Wyoming, Mechanical Engineering Department, 1000 East University Avenue, Laramie, WY 82071 (United States)

    2013-01-01

    Micro-compression tests were performed on pre-strained nickel (Ni) single crystals in order to investigate the influence of the initial dislocation arrangement on the size dependence of small-scale metal structures. A bulk Ni sample was grown using the Czochralski method and sectioned into four compression samples, which were then pre-strained to nominal strains of 5, 10, 15 and 20%. Bulk samples were then characterized using transmission electron microscopy (TEM), micro-Laue diffraction, and electron backscatter diffraction. TEM results show that a dislocation cell structure was present for all deformed samples, and Laue diffraction demonstrated that the internal strain increased with increased amount of pre-straining. Small-scale pillars with diameters from 200 nm to 5 {mu}m were focused ion beam (FIB) machined from each of the four deformed bulk samples and further compressed via a nanoindenter equipped with a flat diamond punch. Results demonstrate that bulk pre-straining inhibits the sample size effect. For heavily pre-strained bulk samples, the deformation history does not affect the stress-strain behavior, as the pillars demonstrated elevated strength and rather low strain hardening over the whole investigated size range. In situ TEM and micro-Laue diffraction measurements of pillars confirmed little change in dislocation density during pillar compression. Thus, the dislocation cell walls created by heavy bulk pre-straining become the relevant internal material structure controlling the mechanical properties, dominating the sample size effect observed in the low dislocation density regime.

  7. Steel Processing Properties and Their Effect on Impact Deformation of Lightweight Structures

    Energy Technology Data Exchange (ETDEWEB)

    Simunovic, S

    2003-09-23

    The objective of the research was to perform a comprehensive computational analysis of the effects of material and process modeling approaches on performance of UltraLight Steel Auto Body (ULSAB) vehicle models. The research addressed numerous material related effects, impact conditions as well as analyzed the performance of the ULSAB vehicles in crashes against designs representing the current US vehicle fleet. This report is organized into three main sections. The first section describes the results of the computational analysis of ULSAB crash simulations that were performed using advanced material modeling techniques. The effects of strain-rate sensitivity on a high strength steel (HSS) intensive vehicle were analyzed. Frontal and frontal offset crash scenarios were used in a finite element parametric study of the ULSAB body structure. Comparisons are made between the crash results using the piece-wise-linear isotropic plasticity strain-rate dependent material model, and the isotropic plasticity material model based on quasi-static properties. The simulation results show the importance of advanced material modeling techniques for vehicle crash simulations due to strain-rate sensitivity and rapid hardening characteristics of advanced high strength steels. Material substitution was investigated for the main frontal crush structure using the material of similar yield stress a significantly different strain-rate and hardening characteristics. The objective of the research presented in Section 2 was to assess the influence of stamping process on crash response of ULSAB vehicle. Considered forming effects included thickness variations and plastic strain hardening imparted in the part forming process. The as-formed thickness and plastic strain for front crash parts were used as input data for vehicle crash analysis. Differences in structural performance between crash models with and without forming data were analyzed in order to determine the effects and feasibility of

  8. Coupling GSM/ALE with ES-FEM-T3 for fluid-deformable structure interactions

    Science.gov (United States)

    Wang, S.; Khoo, B. C.; Liu, G. R.; Xu, G. X.; Chen, L.

    2014-11-01

    In light of the effectiveness of the edge-based smoothed finite element method (ES-FEM-T3) and arbitrary Lagrangian-Eulerian gradient smoothing method (GSM/ALE) in, respectively, solving the pure solid and fluid flow problems using three-node triangular elements, they are coupled together in the present study to solve the more challenging fluid-deformable structure interaction (FSI) problems based on the weak coupling algorithm. Specifically, the fluid flow is tracked over the moving mesh with the well developed GSM/ALE and the transient response of the solid part is solved by the newly developed explicit ES-FEM-T3. The solutions from these two parts are “linked” together by the carefully formulated FSI coupling conditions on the FSI interface. Detailed procedures are summarized to illustrate the implementations of the GSM/ALE with ES-FEM-T3 in an FSI analysis. Three benchmarks are employed to validate the proposed coupled smoothed method in solving both transient and steady-state FSI problems. The mesh sensitivity analysis is further carried out showing that the results of an FSI system appear more sensitive to the change in the solid mesh as compared to the fluid mesh, thus suggesting a more refined mesh for the solid part. Another significant finding is that the present method can still produce reliable results even on the extremely distorted mesh near the FSI interface. The successful coupling GSM/ALE with ES-FEM-T3 for solving FSI problems serves as a good start for further implementing the family of smoothed methods in solving more complex cross-area problems.

  9. Effects of FeSb6 octahedral deformations on the electronic structure of LaFe4Sb12

    KAUST Repository

    Pulikkotil, Jiji Thomas Joseph

    2011-09-01

    First-principles density functional based electronic structure calculations are performed in order to clarify the influence of FeSb6 octahedral deformations on the structural and electronic structure properties of LaFe 4Sb12. Our results show that octahedral tiltings correlate with the band dispersions and, consequently, the band masses. While total energy variation points at an enhanced role of lattice anharmonicity, flat bands emerge from a redistribution of the electronic states. © 2011 Elsevier B.V. All rights reserved.

  10. A finite element formulation based on an enhanced first order shear deformation theory for composite and sandwich structures

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Jin Ho; Cho, Maeng Hyo [Seoul National University, Seoul (Korea, Republic of); Kim, Jun Sik [Pennsylvania State University, University Park (United States); Grediac, Michel [Campus de Clermont-Ferrand-Les Cezeaux, AUBIERE CEDEX (France)

    2008-05-15

    A finite element formulation based on an enhanced first order shear deformation theory is developed to accurately and efficiently predict the behavior of laminated composite and sandwich structures. An enhanced first order shear deformation theory is systematically derived by minimizing the least-squared energy error between the first order shear deformable plate theory and a higher order shear deformable plate theory. In this way, the strain energy of a higher order theory is transformed to that of the Reissner-Mindlin plate theory. This minimization procedure yields a relationship between them that is also used to improve the accuracy of predicted stresses and displacements. The key feature of the proposed theory is in that it can be implemented to commercial FEM packages by simply changing the input, and the results obtained can be also enhanced by post-processing them via a differential quadrature method. Thus, a proposed finite element formulation can be widely used in various application problems. Through numerical examples, the accuracy and robustness of the present formulation are demonstrated

  11. Effects of Structural Deformations of the Crank-Slider Mechanism on the Estimation of the Instantaneous Engine Friction Torque

    Science.gov (United States)

    CHALHOUB, N. G.; NEHME, H.; HENEIN, N. A.; BRYZIK, W.

    1999-07-01

    The focus on the current study is to assess the effects of structural deformations of the crankshaft/connecting-rod/piston mechanism on the computation of the instantaneous engine friction torque. This study is performed in a fully controlled environment in order to isolate the effects of structural deformations from those of measurement errors or noise interference. Therefore, a detailed model, accounting for the rigid and flexible motions of the crank-slider mechanism and including engine component friction formulations, is considered in this study. The model is used as a test bed to generate the engine friction torque,Tfa, and to predict the rigid and flexible motions of the system in response to the cylinder gas pressure. The torsional vibrations and the rigid body angular velocity of the crankshaft, as predicted by the detailed model of the crank-slider mechanism, are used along with the engine load torque and the cylinder gas pressure in the (P-ω) method to estimate the engine friction torque,Tfe. This method is well suited for the purpose of this study because its formulation is based on the rigid body model of the crank-slider mechanism. The digital simulation results demonstrate that the exclusion of the structural deformations of the crank-slider mechanism from the formulation of the (P-ω) method leads to an overestimation of the engine friction torque near the top-dead-center (TDC) position of the piston under firing conditions. Moreover, for the remainder of the engine cycle, the estimated friction torque exhibits large oscillations and takes on positive numerical values as if it is inducing energy into the system. Thus, the adverse effects of structural deformations of the crank-slider mechanism on the estimation of the engine friction torque greatly differ in their nature from one phase of the engine cycle to another.

  12. Internal state variable models for micro- structure in high temperature deformation of titanium alloys

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    There exists an interaction between microstructural evolution and deformation behavior in high temperature deformation of titanium alloys. And the microstruc- ture of titanium alloys is very sensitive to the process parameters of plastic de- formation process. In this paper, on the basis of plastic deformation mechanism of metals and alloys, a microstructural model including dislocation density rate equa- tion and grain growth rate equation is established with the dislocation density rate being an internal state variable. Applying the model to the high temperature de- formation process of Ti60 titanium alloy, the average relative errors of grain sizes between the experiments and the predictions are 9.47% for sampled data, and 13.01% for non-sampled data.

  13. Various aspects of the Deformation Dependent Mass model of nuclear structure

    CERN Document Server

    Petrellis, D; Minkov, N

    2015-01-01

    Recently, a variant of the Bohr Hamiltonian was proposed where the mass term is allowed to depend on the beta variable of nuclear deformation. Analytic solutions of this modified Hamiltonian have been obtained using the Davidson and the Kratzer potentials, by employing techniques from supersymmetric quantum mechanics. Apart from the new set of analytic solutions, the newly introduced Deformation-Dependent Mass (DDM) model offered a remedy to the problematic behaviour of the moment of inertia in the Bohr Hamiltonian, where it appears to increase proportionally to the square of beta. In the DDM model the moments of inertia increase at a much lower rate, in agreement with experimental data. The current work presents an application of the DDM-model suitable for the description of nuclei at the point of shape/phase transitions between vibrational and gamma-unstable or prolate deformed nuclei and is based on a method that was successfully applied before in the context of critical point symmetries.

  14. Ultrafine-grained structure development and deformation behavior of aluminium processed by constrained groove pressing

    International Nuclear Information System (INIS)

    The severe plastic deformation method known as constrained groove pressing was used to produce ultrafine-grained microstructure in recrystallized aluminium (99.99%) at room temperature. The impact of repeated groove pressing, upon microstructure refinement was investigated by transmission electron microscopy of thin foils. Changes in mechanical properties measured by tensile and by hardness tests were related to microstructure development. The formation of banded subgrain microstructure with dislocation cells, and appearance of polygonal subgrains was a common feature observed in deformed plate subjected to the first pass. The substantial impact of strain upon strength increase was observed after the first pressings. The yield stress and ultimate tensile strength reached a maximum after four passes. A loss of ductility was observed in all processed plates. Hardness values measured in different areas of the deformed plates indicated heterogeneous strain distribution even after large degrees of straining

  15. Near-field and far-field effects of elastic structure on coseismic deformation of the 2011 Tohoku earthquake, Japan

    Science.gov (United States)

    Hashima, Akinori; Becker, Thorsten; Freed, Andy; Sato, Hiroshi; Okaya, David; Suito, Hisashi; Yarai, Hiroshi; Ishiyama, Tatsuya; Iwasaki, Takaya

    2016-04-01

    Coseismic deformation due to the 2011 Tohoku earthquake, Japan, was detected by dense GPS network of over 1200 stations and several seafloor stations. Using these observations, we investigated effects of elastic structure on coseismic deformation with a 3-D finite element model incorporating geometry of the regional plate boundaries and elastic structures. First, we computed displacement fields for different elastic models with the same coseismic slip distribution to understand the effect of elastic structures. We assumed the three structure models: (a) Homogeneous model, (b) two-layered model considering crust-mantle structure (rigidity of 35 and 65 GPa, respectively) (Layered model), (c) crust-mantle model with cold subducting slab (85 GPa) (Slab model). We found the two contradicting effects: (1) In the far field (mostly at onshore stations), the amount of displacement decreases with the increase of the average rigidity. (2) In the near field at offshore stations, the amount of surface displacement increases with the increase of rigidity across the faults. This is because the stiffer (less deformable) footwall requires more movement of the hanging wall to accommodate the slip. Next, we inverted the observed displacements to obtain slip distribution for three elastic structures. The patterns of inverted slip distribution are basically similar for all three models but the amount of maximum slip is not simply related to average rigidity of structure models. The maximum slip increases from 39 m in Homogeneous model to 40 m in Layered model and then falls to 38 m in Slab model. These changes show that crust-mantle layering is more effective on far field while slab effect is more important in the near field.

  16. SURFACE STRUCTURE AND BULK PROPERTIES OF FLUORINATED POLY(ETHER URETHANE)S AND POLY(ETHER URETHANE) BLENDS

    Institute of Scientific and Technical Information of China (English)

    Hong Tan; Min Guo; Rong-ni Du; Xing-yi Xie; Jie-hua Li; Yin-ping Zhong; Qiang Fu

    2004-01-01

    It has been well known that fluorinated polyurethanes exhibit uniquely low surface energy, biocompatibility and biostability, thermal and oxidative stability and nonsticking behavior. Consequently, these polymers have attracted considerable interest. However, the mechanical properties of fluorinated polyurethanes usually decline with increasing fluorine contents. The blending of fluorinated polyurethanes with normal polyurethane was carried out to achieve balanced mechanical and surface properties. It was found that polyurethane with good mechanical properties and low surface energy can be obtained by adding a small amount of fluorinated polyurethane. The fluorinated side chains can easily migrate to uppermost surfaces of the blends untill the fluorine level at the surface becomes almost saturated. It has been shown from contact angle, XPS and AFM measurements that only as little as 0.34 wt% of fluorine level is enough to produce a surface saturated with fluorine, and the fluorine level at the uppermost surface is one hundred times higher than that in the blend bulk. The final outer surface structures of the polyurethane blend were independent of the content of the fluorinated polyurethane in the blends due to the surfaces saturated by fluorine.

  17. Crustal structure and deformation associated with seamount subduction at the north Manila Trench represented by analog and gravity modeling

    Science.gov (United States)

    Li, Fucheng; Sun, Zhen; Hu, Dengke; Wang, Zhangwen

    2013-12-01

    We investigated the deformation in the accretionary wedge associated with subducted seamounts in the northern Manila Trench by combining observations from seismic profiles and results from laboratory sandbox experiments. From three seismic reflection profiles oriented approximately perpendicular to the trench, we observed apparent variations in structural deformation along the trench. A number of back-thrust faults were formed in the accretionary wedge where subducted seamounts were identified. In contrast, observable back-thrusts were quite rare along the profile without seamounts, indicating that seamount subduction played an important role in deformation of the accretionary wedge. We then conducted laboratory sandbox experiments to investigate the effects of subducted seamounts on the structural deformation of the accretionary wedge. From the analog modeling results we found that seamount subduction could cause well-developed back-thrusts, gravitational collapse, and micro-fractures in the wedge. We also found that a seamount may induce normal faults in the wedge and that normal faults may be eroded by subsequent seamount subduction. In addition, we constrained the crustal structure of the South China Sea plate from modeling free-air gravity data. The dip angle of the subducting plate, which was constrained by hypocenters of available earthquakes, increased from south to north in the northern Manila Trench. We found a laterally heterogeneous density distribution of the oceanic crust according to the gravity data. The density of subducted crust is ~2.92 g/cm3, larger than that of the South China Sea crust (2.88 g/cm3).

  18. ARPES investigation on the surface vs bulk electronic structures of correlated topological insulators YbB6 and other rare earth hexaborides

    Science.gov (United States)

    Xu, Nan; Matt, C. E.; Pomjakushina, E.; Dil, J. H.; Landolt, G.; Ma, J. Z.; Shi, X.; Dhaka, R. S.; Plumb, N. C.; Radovic, M.; Rogalev, V.; Strocov, V.; Kim, T. K.; Hoesch, M.; Conder, K.; Mesot, J.; Ding, H.; Shi, Ming

    2015-03-01

    Using ARPES performed in wide photon energy range we systematically studied the bulk and surface electronic structures of a topological mixed- valence insulator candidate, YbB6. The bulk B-2p states are probed with bulk-sensitive soft X-ray ARPES, exhibiting strong three-dimensionality with the band top locating 80 meV below the EF at the X point. The measured bulk Yb-4f states are located at 1 and 2.3 eV below EF, which hybridize with the dispersive B-2p states. The bulk band structures obtained by experiments are substantially different from the first principle calculations, but it can be better described by adding a correlation parameter U = 7 eV, indicating YbB6 is a correlated system. Using surface-sensitive VUV ARPES, we revealed two-dimensional surface states which form three electron-like FSs with Dirac-cone-like dispersions. The odd number of surface FSs gives the first indication that the surface states are topological non-trivial. The spin-resolved ARPES measurements provide further evidence that these surface states are spin polarized with spin locked to the crystal momentum. Recent results on the TI phase in other rare earth hexaborides will also be shown.

  19. Structural and electrical properties of Si- and Ti-doped Cu2SnSe3 bulks

    International Nuclear Information System (INIS)

    Silicon-doped (Cu2(Sn1−xSix)Se3 and titanium-doped (Cu2(Sn1−xTix)Se3 at x=0, 0.05, 0.1, 0.15, and 0.2 were prepared at 550 °C for 2 h with soluble sintering aids of volatile Sb2S3 and Te. Defect chemistry was studied by measuring structural and electrical properties of Si-doped and Ti-doped Cu2SnSe3 (CTSe) as a function of dopant concentration. Si-doped CTSe pellets show p-type at x=0 and 0.05 and n-type at x=0.1, 0.15, and 0.2, whereas Ti-doped CTSe pellets show p-type at x=0, 0.05 and 0.1 and n-type at x=0.15 and 0.2. The lowest hole concentration of 3.6×1017 cm−3 and the highest mobility of 1525 cm2 V−1 s−1 were obtained for the Si-doped (Cu2(Sn1−xSix)Se3 bulks at x=0.1 (10% Si), while they were 3.1×1017 cm−3 and 813 cm2 V−1 s−1 for the Ti-doped CTSe bulks at x=0.15 (15% Ti), as compared to 1.1×1018 cm−3 and 209 cm2 V−1 s−1 for undoped one. The explanations based upon antisite defects of Si-to-Sn, Ti-to-Sn, Cu-to-Sn, and Sn-to-Cu for the changes in electrical property were declared. The study in bulk Si-doped and Ti-doped CTSe is based upon defect state and is consistent and supported by the data of electrical property and lattice parameter. - Graphical abstract: Cu2SnSe3 (CTSe) semiconductor is interesting because of its adjustable electrical properties by extrinsic doping. Si and Ti doping in CTSe leads to high carrier mobility above 800 cm2 V−1 s−1. - Highlights: • Cu2SnSe3 (CTSe) is an interesting semiconductor because of its adjustable electrical properties. • Cu(In,Ga)Se2, on the contrary, is difficult to change its electrical properties. • Si and Ti doping can change p-CTSe to n-CTSe. • The lowest electron concentration in doped CTSe had the highest mobility above 800 cm2 V−1 s−1. • The defects of Si-to-Sn, Ti-to-Sn, Cu-to-Sn, and Sn-to-Cu in Si- and Ti-doped CTSe were proposed

  20. Structural and electrical properties of Si- and Ti-doped Cu{sub 2}SnSe{sub 3} bulks

    Energy Technology Data Exchange (ETDEWEB)

    Wubet, Walelign; Kuo, Dong-Hau, E-mail: dhkuo@mail.ntust.edu.tw

    2015-07-15

    Silicon-doped (Cu{sub 2}(Sn{sub 1−x}Si{sub x})Se{sub 3} and titanium-doped (Cu{sub 2}(Sn{sub 1−x}Ti{sub x})Se{sub 3} at x=0, 0.05, 0.1, 0.15, and 0.2 were prepared at 550 °C for 2 h with soluble sintering aids of volatile Sb{sub 2}S{sub 3} and Te. Defect chemistry was studied by measuring structural and electrical properties of Si-doped and Ti-doped Cu{sub 2}SnSe{sub 3} (CTSe) as a function of dopant concentration. Si-doped CTSe pellets show p-type at x=0 and 0.05 and n-type at x=0.1, 0.15, and 0.2, whereas Ti-doped CTSe pellets show p-type at x=0, 0.05 and 0.1 and n-type at x=0.15 and 0.2. The lowest hole concentration of 3.6×10{sup 17} cm{sup −3} and the highest mobility of 1525 cm{sup 2} V{sup −1} s{sup −1} were obtained for the Si-doped (Cu{sub 2}(Sn{sub 1−x}Si{sub x})Se{sub 3} bulks at x=0.1 (10% Si), while they were 3.1×10{sup 17} cm{sup −3} and 813 cm{sup 2} V{sup −1} s{sup −1} for the Ti-doped CTSe bulks at x=0.15 (15% Ti), as compared to 1.1×10{sup 18} cm{sup −3} and 209 cm{sup 2} V{sup −1} s{sup −1} for undoped one. The explanations based upon antisite defects of Si-to-Sn, Ti-to-Sn, Cu-to-Sn, and Sn-to-Cu for the changes in electrical property were declared. The study in bulk Si-doped and Ti-doped CTSe is based upon defect state and is consistent and supported by the data of electrical property and lattice parameter. - Graphical abstract: Cu{sub 2}SnSe{sub 3} (CTSe) semiconductor is interesting because of its adjustable electrical properties by extrinsic doping. Si and Ti doping in CTSe leads to high carrier mobility above 800 cm{sup 2} V{sup −1} s{sup −1}. - Highlights: • Cu{sub 2}SnSe{sub 3} (CTSe) is an interesting semiconductor because of its adjustable electrical properties. • Cu(In,Ga)Se{sub 2}, on the contrary, is difficult to change its electrical properties. • Si and Ti doping can change p-CTSe to n-CTSe. • The lowest electron concentration in doped CTSe had the highest mobility above 800 cm{sup 2} V{sup

  1. Structures and hot deformation of Al-V{sub 2}O{sub 5} mechanically alloyed composite

    Energy Technology Data Exchange (ETDEWEB)

    Blaz, L.; Sierpinski, Z.; Tumidajewicz, M.; Kaneko, J.; Sugamata, M

    2004-09-22

    A very fine structure of mechanically alloyed Al-V{sub 2}O{sub 5} composite was tested by means of transmission electron microscopy and X-ray energy disperse spectrum (EDS) analysis. Annealing of the composite was found to result in the intermetallic grains growth and an increase of the material porosity due to chemical reaction between components. Hot compression tests of as extruded and annealed samples confirmed high mechanical properties of the material at high deformation temperatures that result from very fine-grained and stable structure of the composite.

  2. Change of shell structure and magnetic moments of odd-N deformed nuclei towards the neutron drip line

    OpenAIRE

    Hamamoto, Ikuko

    2010-01-01

    Abstract Examples of the change of neutron shell-structure in both weakly-bound and resonant neutron one-particle levels in nuclei towards the neutron drip line are exhibited. It is shown that the shell-structure change due to the weak binding may lead to the deformation of those nuclei with the neutron numbers N ? 8, 20, 28 and 40, which are known to be magic numbers in stable nuclei. Nuclei in the " island of inversion " are most easily and in a simple manner understood in terms of defor...

  3. 3D EBSD charactyerization of deformation structures in commercial purity aluminum

    DEFF Research Database (Denmark)

    Fengxiang, Lin; Godfrey, A.; Juul Jensen, Dorte;

    2010-01-01

    A method to map the microstructure in deformed aluminum in three dimensions is presented. The method employs serial sectioning by mechanical polishing, and electropolishing to obtain a good surface quality, and orientation mapping of individual grains in each section by electron backscattered...

  4. Structural coarsening during annealing of an aluminum plate heavily deformed using ECAE

    DEFF Research Database (Denmark)

    Mishin, Oleg V.; Zhang, Yubin; Godfrey, A.

    2015-01-01

    The microstructure and softening behaviour have been investigated in an aluminum plate heavily deformed by equal channel angular extrusion and subsequently annealed at 170 °C. It is found that at this temperature the microstructure evolves by coarsening with no apparent signs of recrystallization...

  5. A model for the calculation of elastic-plastic deformation of beam structures loaded with impact loads

    International Nuclear Information System (INIS)

    A model for the calculation of the elastic-plastic behaviour of beams loaded with impact loads in the longitudinal and the transverse direction is developed. The description of the thrust and bending deformation due to dynamic material stresses is done using Timoshenko's beam model. The basic equations lead to systems of hyperbolic partial differential equations, which are quasi-linear in the case of plastic deformation. They describe the spread of normal, bending and thrust waves in the beam. In order to solve the partial differential equations, a numerical process is built up using the characteristic method, which permits the calculation of the dynamic behaviour of general structures consisting of various beams. (orig./HP)

  6. A continuum model of deformation, transport and irreversible changes in atomic structure in amorphous lithium–silicon electrodes

    International Nuclear Information System (INIS)

    Recent experiments and atomic scale computations indicate that the standard continuum models of diffusion in stressed solids do not accurately describe transport, deformation and stress in Li–Si alloys. We suggest that this is because classical models do not account for the irreversible changes in atomic structure of Si that are known to occur during a charge–discharge cycle. A more general model of diffusion in an amorphous solid is described, which permits unoccupied Si lattice sites to be created or destroyed. This may occur as a thermally activated process; or as a result of irreversible plastic deformation under stress. The model predicts a range of phenomena observed in experiment that cannot be captured using classical models, including irreversible changes in volume resulting from a charge–discharge cycle, asymmetry between the tensile and compressive yield stress, and a slow evolution in mechanical and electrochemical response over many charge–discharge cycles

  7. The formation, structure, and properties of the Au-Co alloys produced by severe plastic deformation under pressure

    Science.gov (United States)

    Tolmachev, T. P.; Pilyugin, V. P.; Ancharov, A. I.; Chernyshov, E. G.; Patselov, A. M.

    2016-02-01

    The mechanical alloying of Au-Co mixtures, which are systems with high positive mixing enthalpy, is studied following high-pressure torsion deformation at room and cryogenic temperatures. X-ray diffractometry in synchrotron radiation and scanning microscopy are used to investigate the sequence of structural changes in the course of deforming the mixtures up to the end state of the fcc substitutional solid solution based on gold. The mechanical properties of the alloys are measured both during mixture processing and after mechanical alloying. Microfractographic studies are performed. Factors that facilitate the solubility of Co in Au, namely, increased processing pressure, cobalt concentration in a charge mixture, true strain, and temperature decreased to cryogenic level have been identified.

  8. Bulk undercooling

    Science.gov (United States)

    Kattamis, T. Z.

    1984-01-01

    Bulk undercooling methods and procedures will first be reviewed. Measurement of various parameters which are necessary to understand the solidification mechanism during and after recalescence will be discussed. During recalescence of levitated, glass-encased large droplets (5 to 8 mm diam) high speed temperature sensing devices coupled with a rapid response oscilloscope are now being used at MIT to measure local thermal behavior in hypoeutectic and eutectic binary Ni-Sn alloys. Dendrite tip velocities were measured by various investigators using thermal sensors or high speed cinematography. The confirmation of the validity of solidification models of bulk-undercooled melts is made difficult by the fineness of the final microstructure, the ultra-rapid evolution of the solidifying system which makes measurements very awkward, and the continuous modification of the microstructure which formed during recalescence because of precipitation, remelting and rapid coarsening.

  9. Evolution of dislocation structure and deformation resistance in creep exemplified on single crystals of CaF2

    International Nuclear Information System (INIS)

    Single crystals of CaF2 oriented along for glide on three equally stressed slip systems were used to study the evolution of the dislocation structure during deformation at temperatures from 873 to 1315 K. Structure quantification was done by the etch pit method using atomic force microscopy for high resolution. Evolution begins with free dislocations forming a cellular structure. The average spacings of free dislocations and of cell boundaries are generally close to their stress-dependent steady state values. The subgrain structure develops more slowly with strain. As it superimposes on the free dislocations, the crystals work harden and the creep rate decreases. The rates of change of the characteristic spacings of subgrain and cell boundaries, of free dislocations and of dislocations in subgrain boundaries are formulated as functions of stress, strain and the empirical steady state values of spacings. Combining the laws of structure evolution with those of deformation kinetics in the framework of the composite model, the creep behavior is modeled in a large range of homologous temperatures in consistence with the general picture of plasticity of crystalline materials.

  10. MAPPING FLOW LOCALIZATION PROCESSES IN DEFORMATION OF IRRADIATED REACTOR STRUCTURAL ALLOYS - FINAL REPORT. Nuclear Energy Research Initiative Program No. MSF99-0072. Period: August 1999 through September 2002. (ORNL/TM-2003/63)

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, K.

    2003-09-26

    Metals that can sustain plastic deformation homogeneously throughout their bulk tend to be tough and malleable. Often, however, if a metal has been hardened it will no longer deform uniformly. Instead, the deformation occurs in narrow bands on a microscopic scale wherein stresses and strains become concentrated in localized zones. This strain localization degrades the mechanical properties of the metal by causing premature plastic instability failure or by inducing the formation of cracks. Irradiation with neutrons hardens a metal and makes it more prone to deformation by strain localization. Although this has been known since the earliest days of radiation damage studies, a full measure of the connection between neutron irradiation hardening and strain localization is wanting, particularly in commercial alloys used in the construction of nuclear reactors. Therefore, the goal of this project is to systematically map the extent of involvement of strain localization processes in plastic deformation of three reactor alloys that have been neutron irradiated. The deformation processes are to be identified and related to changes in the tensile properties of the alloys as functions of neutron fluence (dose) and degree of plastic strain. The intent is to define the role of strain localization in radiation embrittlement phenomena. The three test materials are a tempered bainitic A533B steel, representing reactor pressure vessel steel, an annealed 316 stainless steel and annealed Zircaloy-4 representing reactor internal components. These three alloys cover the range of crystal structures usually encountered in structural alloys, i.e. body-centered cubic (bcc), face-centered cubic (fcc), and close-packed hexagonal (cph), respectively. The experiments were conducted in three Phases, corresponding to the three years duration of the project. Phases 1 and 2 addressed irradiations and tensile tests made at near-ambient temperatures, and covered a wide range of neutron fluences

  11. The Values of Strain Components and Their Role in Formation of Ultrafine-Grained and Nanosized Structure in Materials by Means of Severe Plastic Deformation

    Science.gov (United States)

    Utyashev, F. Z.; Sukhorukov, R. U.; Nazarov, A. A.; Potekaev, A. I.

    2015-05-01

    Using equal-channel angular pressing as an example, the effect of metal-flow kinematics under condition of severe plastic deformation of metals on the value of strain and features of structural changes is considered. The role of shear and rotational strain in the formation of ultrafine-grained structures is shown and the contribution into the total deformation is defined. Using equal-channel angular pressing as an example, the effect of metal-flow kinematics under condition of severe plastic deformation of metals on the value of strain and features of structural changes is considered. The role of shear and rotational strain in the formation of ultrafine-grained structures is shown and the contribution into the total deformation is defined.

  12. Significance of settling model structures and parameter subsets in modelling WWTPs under wet-weather flow and filamentous bulking conditions.

    Science.gov (United States)

    Ramin, Elham; Sin, Gürkan; Mikkelsen, Peter Steen; Plósz, Benedek Gy

    2014-10-15

    Current research focuses on predicting and mitigating the impacts of high hydraulic loadings on centralized wastewater treatment plants (WWTPs) under wet-weather conditions. The maximum permissible inflow to WWTPs depends not only on the settleability of activated sludge in secondary settling tanks (SSTs) but also on the hydraulic behaviour of SSTs. The present study investigates the impacts of ideal and non-ideal flow (dry and wet weather) and settling (good settling and bulking) boundary conditions on the sensitivity of WWTP model outputs to uncertainties intrinsic to the one-dimensional (1-D) SST model structures and parameters. We identify the critical sources of uncertainty in WWTP models through global sensitivity analysis (GSA) using the Benchmark simulation model No. 1 in combination with first- and second-order 1-D SST models. The results obtained illustrate that the contribution of settling parameters to the total variance of the key WWTP process outputs significantly depends on the influent flow and settling conditions. The magnitude of the impact is found to vary, depending on which type of 1-D SST model is used. Therefore, we identify and recommend potential parameter subsets for WWTP model calibration, and propose optimal choice of 1-D SST models under different flow and settling boundary conditions. Additionally, the hydraulic parameters in the second-order SST model are found significant under dynamic wet-weather flow conditions. These results highlight the importance of developing a more mechanistic based flow-dependent hydraulic sub-model in second-order 1-D SST models in the future. PMID:25003213

  13. Structural, chemical, and thermoelectric properties of Bi2Te3 Peltier materials. Bulk, thin films, and superlattices

    International Nuclear Information System (INIS)

    In this work, the nature of the natural nanostructure (nns) was analysed and the correlations to the transport coefficients, particularly the lattice thermal conductivity, is discussed. Experimental methods are presented for the first time, yielding an accurate quantitative analysis of the chemical composition and of stress fields in Bi2Te3 and in compounds with similar structural and chemical microstructures. This work can be subdivided as follows: (I) N-type Bi2(Te0.91Se0.09)3 and p-type (Bi0.26Sb0.74)1.98(Te0.99Se0.01)3.02 bulk materials synthesised by the Bridgman technique. (II) Bi2Te3 thin films and Bi2Te3/Bi2(Te0.88Se0.12)3 superlattices epitaxially grown by molecular beam epitaxy (MBE) on BaF2 substrates with periods of δ-12 nm at the Fraunhofer-Institut fuer Physikalische Messtechnik (IPM). (III) Experimental methods, i.e., TEM specimen preparation, high-accuracy quantitative chemical analysis by EDX in the TEM, and image simulations of dislocations and the nns according to the two-beam dynamical diffraction theory. The nns was analysed in detail by stereomicroscopy and by image simulation and was found to be a pure sinusoidal displacement field with (i) a displacement vector parallel to and an amplitude of about 10 pm and (ii) a wave vector parallel to {1,0,10} and a wavelength of 10 nm. The results obtained here showed a significant amount of stress in the samples, induced by the nns which was still not noticed and identified. Both kinds of nanostructures, artificial (ans) and natural (nns) nanostructures, yielded in thermoelectric materials a low lattice thermal conductivity which was beneficial for the thermoelectric figure of merit ZT. (orig.)

  14. Evolution of orientations and deformation structures within individual grains in cold rolled columnar grained nickel

    Energy Technology Data Exchange (ETDEWEB)

    Wu, G.L., E-mail: wugl@bit.edu.cn [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Center for Fundamental Research: Metal Structures in Four Dimensions, Materials Research Division, Riso National Laboratory for Sustainable Energy, Technical University of Denmark, DK-4000 Roskilde (Denmark); Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Godfrey, A. [Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Winther, G.; Juul Jensen, D. [Center for Fundamental Research: Metal Structures in Four Dimensions, Materials Research Division, Riso National Laboratory for Sustainable Energy, Technical University of Denmark, DK-4000 Roskilde (Denmark); Danish-Chinese Center for Nanometals, Materials Research Division, Riso National Laboratory for Sustainable Energy, Technical University of Denmark, DK-4000 Roskilde (Denmark); Liu, Q. [School of Materials Science and Engineering, Chongqing University, Chongqing 400045 (China)

    2011-08-15

    Columnar grained Ni is used as a model material allowing simultaneous non-surface investigations of the evolution of crystallographic orientations and deformation microstructures within individual grains as a function of rolling strain up to {epsilon} = 0.7. Electron channelling contrast and electron backscattered diffraction are used to visualise microstructures and crystallographic orientations. It is found that both the microstructural and the textural development depend strongly on the initial grain orientation. A grain size effect is observed on the deformation-induced orientation scatter within the grains. Large grains have microstructure and orientation scatters similar to those observed in single crystals of similar orientation. The observations are interpreted based on a slip system analysis, considering the relative effects of the initial grain orientation and the interaction between neighbouring grains as well.

  15. Evolution of orientations and deformation structures within individual grains in cold rolled columnar grained nickel

    International Nuclear Information System (INIS)

    Columnar grained Ni is used as a model material allowing simultaneous non-surface investigations of the evolution of crystallographic orientations and deformation microstructures within individual grains as a function of rolling strain up to ε = 0.7. Electron channelling contrast and electron backscattered diffraction are used to visualise microstructures and crystallographic orientations. It is found that both the microstructural and the textural development depend strongly on the initial grain orientation. A grain size effect is observed on the deformation-induced orientation scatter within the grains. Large grains have microstructure and orientation scatters similar to those observed in single crystals of similar orientation. The observations are interpreted based on a slip system analysis, considering the relative effects of the initial grain orientation and the interaction between neighbouring grains as well.

  16. A crystal plasticity model of a formation of a deformation band structure

    Czech Academy of Sciences Publication Activity Database

    Kratochvíl, J.; Kružík, Martin

    2015-01-01

    Roč. 95, č. 32 (2015), s. 3621-3639. ISSN 1478-6435 Grant ostatní: GA ČR(CZ) GAP107/12/0121 Institutional support: RVO:67985556 Keywords : deformation substructure * rigid-plastic crystal plasticity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.825, year: 2014 http://library.utia.cas.cz/separaty/2015/MTR/kruzik- 0456300.pdf

  17. Theoretical investigation of the electronic structures and magnetic properties of the bulk and surface (001) of the quaternary Heusler alloy NiCoMnGa

    Energy Technology Data Exchange (ETDEWEB)

    Al-zyadi, Jabbar M. Khalaf, E-mail: Jabbar_alzyadi@yahoo.com [Department of Physics, College of Education, University of Basrah, Basrah 6100 (Iraq); Gao, G.Y. [School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Yao, Kai-Lun [School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); International Center of Materials Physics, Chinese Academy of sciences, Shenyang 110015 (China)

    2015-03-15

    In this paper, we study the electronic structures, magnetic properties, and half-metallicity of the bulk and (001) surface of Heusler alloy NiCoMnGa. Our first-principles calculations exhibit that, within the generalized gradient approximation (GGA) of the electronic exchange–correlation functional, the quaternary Heusler alloy NiCoMnGa is a half-metallic ferromagnet at the equilibrium lattice constant of 5.795 Ǻ with a total spin magnetic moment of 5 μ{sub B} per formula unit. The calculated total atomic magnetic moment follows the Slater–Pauling rule. At the same equilibrium lattice constant, the half-metallicity confirmed in the bulk NiCoMnGa, is destroyed at both MnGa- and NiCo-terminated (001) surfaces and subsurfaces. Based on the magnetic property calculations, the magnetic moments of Co, Mn, and Ga atoms at the NiCo- and MnGa-terminated surfaces increase with respect to the corresponding bulk values while the atomic magnetic moment of Ni at the NiCo-terminated surface decreases. - Highlights: • The bulk NiCoMnGa quaternary-Heusler alloy is found to be a half-metallic ferromagnet. • Surface studies show that the half-metallicity of bulk NiCoMnGa is destroyed. • The magnetic moments are increased (decreased) at the (001) surface. • The quaternary-Heusler alloy follows a Slater–Pauling behavior.

  18. Mechanical Simulation of the Localized Deformation in the Aluminum Foams: A Three-dimensional (3D) Structure Based Study

    Science.gov (United States)

    Kai, Zhu; Enyu, Guo; Wenqian, Zhou; Sansan, Shuai; Tao, Jing; Hongliang, Hou; Yanjin, Xu

    2015-06-01

    Metal-foam materials have been used increasingly in industry for their low-density, high-toughness and high impact resistance properties. Understanding the macro-scale mechanical properties of these materials is essential to evaluate their actual performance and thus to optimize the structures and properties accordingly. Synchrotron radiation X-ray microtomographytechnique is a promising method to study 3D structures at small length scales, which provides high spatial resolution and allows the researchers to observe the change of structures/features in situ without destroying the original objects. In this work, the real 3D structure of closed-cell aluminum foam was obtained by using synchrotron radiation X-ray microtomography. The reconstructed 3D model of the foam was further utilized as input for the subsequent mechanical study to investigate the localized deformation behaviors and evolution process of the foam under longitudinal quasi-static uniaxial compressive loading. By analyzing the simulated results, it is demonstrated that the deformation bands always initiate and propagate along the cell walls which are finally folded upon loading. And the large spherical cells are more susceptible to yielding, as well as to the stress concentration than the cells with other shapes. This finding is consistent with the experimental results.

  19. Seismically induced soft-sediment deformation structures revealed by X-ray computed tomography of boring cores

    Science.gov (United States)

    Nakashima, Yoshito; Komatsubara, Junko

    2016-06-01

    X-ray computed tomography (CT) allows us to visualize three-dimensional structures hidden in boring cores nondestructively. We applied medical X-ray CT to cores containing seismically induced soft-sediment deformation structures (SSDSs) obtained from the Kanto region of Japan, where the 2011 off the Pacific coast of Tohoku Earthquake occurred. The CT images obtained clearly revealed various types of the seismically induced SSDSs embedded in the cores: a propagating sand dyke bent complexly by the preexisting geological structure, deformed laminations of fluidized sandy layers, and two types of downward mass movement (ductile downward folding and brittle normal faulting) as compensation for upward sand transport through sand dykes. Two advanced image analysis techniques were applied to the sand dyke CT images for the first time. The GrowCut algorithm, a specific digital image segmentation technique that uses cellular automata, was used successfully to extract the three-dimensional complex sand dyke structures embedded in the sandy sediments, which would have been difficult to achieve using a conventional image processing technique. Local autocorrelation image analysis was performed to detect the flow pattern aligned along the sand dykes objectively. The results demonstrate that X-ray CT coupled with advanced digital image analysis techniques is a promising approach to studying the seismically induced SSDSs in boring cores.

  20. Towards quantitative modelling of surface deformation of polymer micro-structures under tactile scanning measurement

    International Nuclear Information System (INIS)

    Contact stylus-based surface profilometry is capable of topography measurement whilst being independent of the physical, electrical and optical properties of the materials under test, and has therefore become an indispensable tool for dimensional measurement of transparent specimens. However, large measurement deviations will appear when soft specimens, especially specimens made of polymers, are measured by contact stylus profilometry. In this paper the surface deformation behaviour of two polymers for molding and one photoresist, i.e. Ormocomp, Ormoclad and SU-8, under different tactile measurement conditions have been experimentally investigated. An empirical analytical model is hereby proposed for the prediction of surface deformation of soft specimens under tactile (sliding) contact. Preliminary experimental results demonstrate that the proposed five-parameter model is applicable for describing the deformation behaviour of these thermoplastic materials under the scanning speed ranging from 2 to 200 μm s−1 and the probing force varying from 5 to 500 μN. In addition, thanks to quantitative topographical measurements of the layer thickness of the aforementioned photoresists, the scratch behaviour and the time-dependent mechanical properties of these materials have also been experimentally determined. (paper)

  1. Influence of deformation temperature on structural variation and shape-memory effect of a thermoplastic semi-crystalline multiblock copolymer

    Directory of Open Access Journals (Sweden)

    W. Yan

    2015-07-01

    Full Text Available A multiblock copolymer termed as PCL-PIBMD, consisting of crystallizable poly(ε-caprolactone (PCL segments and crystallizable poly(3S-isobutyl-morpholine-2,5-dione (PIBMD segments, has been reported as a material showing a thermally-induced shape-memory effect. While PIBMD crystalline domains act as netpoints to determine the permanent shape, both PCL crystalline domains and PIBMD amorphous domains, which have similar transition temperatures (Ttrans can act as switching domains. In this work, the influence of the deformation temperature (Tdeform = 50 or 20°C, which was above or below Ttrans, on the structural changes of PCL-PIBMD during uniaxial deformation and the shapememory properties were investigated. Furthermore, the relative contribution of crystalline PCL and PIBMD amorphous phases to the fixation of the temporary shape were distinguished by a toluene vapor treatment approach. The results indicated that at 50°C, both PCL and PIBMD amorphous phases can be orientated during deformation, resulting in thermallyinduced crystals of PCL domains and joint contribution to the switching domains. In contrast at 20°C, the temporary shape was mainly fixed by PCL crystals generated via strain-induced crystallization.

  2. Apparatus and method for determining stress and strain in pipes, pressure vessels, structural members and other deformable bodies

    International Nuclear Information System (INIS)

    A method and apparatus for measuring stress and strain associated with a pipe, pressurized vessel, structural member or deformable body containing a flaw or stress concentration utilizes a laser beam to illuminate a surface being analyzed and an optical data digitizer to sense a signal provided by a speckle pattern produced by the light beam reflected from the illuminated surface. One signal is received from the surface in a reference condition and subsequent signals are received from the surface after surface deformation. The optical data digitizer provides the received signal to an image processor, and the processor stores the signals and correlates the deformed image received with the reference image and then sends this correlated information to a minicomputer which performs mathematical analyses of the signal to determine stress and strain associated with the surface. The apparatus is constructed as one integral unit, and further includes a digital and tape display, as well as a television monitor and an electro-optic range indicator. (author) 15 figs

  3. Development and structural characterization of exchange-spring-like nanomagnets in (Fe,Co)-Pt bulk nanocrystalline alloys

    Science.gov (United States)

    Crisan, O.; Crisan, A. D.; Mercioniu, I.; Nicula, R.; Vasiliu, F.

    2016-03-01

    FePt-based alloys are currently under scrutiny for their possible use as materials for perpendicular magnetic recording. Another possible application is in the field of permanent magnets without rare-earths, magnets that may operate at higher temperatures than the classic Nd-Fe-B magnets. Within this study, FeCoPt alloys prepared by rapid solidification from the melt are structurally and magnetically characterized. In the as-cast FeCoPt ribbons, a three-phase structure comprising well-ordered CoFePt and CoPt L10 phases embedded in a disordered fcc FePt matrix was evidenced by XRD, HREM and SAED. Extended transmission electron microscopy analysis demonstrates the incipient formation of ordered L10 phases. X-ray diffraction was used to characterize the phase structure and to obtain the structural parameters of interest for L10 ordering. In the as-cast state, the co-existence of hard magnetic CoFePt and CoPt L10 tetragonal phases with the soft fcc FePt phase is obtained within a refined microstructure made of alternatively disposed grains (grain sizes from 1 to 7 nm). Following a thermal treatment of 1 h at 670 °C, the soft magnetic fcc matrix phase transforms to tetragonal L10 phases (disorder-order transition). The resulting CoPt and CoFePt L10 phases have grains of around 5-20 nm in size. In the as-cast state, magnetic measurements show a quite large remanence (0.75 T), close to the value of the parent L10 FePt phase. Coercive fields of about 200 kA/m at 5 K were obtained, comparable with those reported for some FePt-based bulk alloys. Upon annealing both remanence and coercivity are increased and values of up to 254 kA/m at 300 K are obtained. The polycrystalline structure of the annealed FeCoPt samples, as well as the formation of multiple c-axis domains in different CoPt and CoFePt regions (which leads to a reduction of the magneto-crystalline anisotropy) may account for the observed coercive fields that are lower than in the case of very thin FeCoPt films. A

  4. Impact of network geometry, observation schemes and telescope structure deformations on local ties: simulations applied to Sardinia Radio Telescope

    Science.gov (United States)

    Abbondanza, Claudio; Sarti, Pierguido

    2012-03-01

    The 64-m Sardinia Radio Telescope (SRT) is currently under construction in Sardinia (Italy). To ensure future surveying and monitoring operations at an utmost level of accuracy, we aim at selecting the optimal design and the most cost-effective solution for the establishment of the local ground control network (LGCN). We simulate and test 45 data sets corresponding to 5 different network configurations. We investigate the influence of 2 LGCN geometries (14 or 8 ground markers) and 3 terrestrial observation schemes (based on redundant forward intersections or side shots) on the precision and accuracy of the conventional reference point (CRP) of SRT and the simulated tie vector with a global navigation satellite system (GNSS) station. In addition, thermal and gravitational deformations of the radio telescope structure are simulated as systematic errors introduced into the observations and their effects on the CRP estimates are quantified. The state-of-the-art of CRP surveying and computation, based on terrestrial indirect methods, is applied. We show how terrestrial indirect methods can estimate the position of the radio telescope CRP to the millimeter precision level. With our simulations, we prove that limiting the LGCN to a 8-point configuration ensures the same precision on the CRP obtained with a 14-point network. Furthermore, we demonstrate that in the absence of telescope deformations, side shots, despite the lower redundancy, preserve a precision similar to that of redundant forward intersections. We show that the deformations due to gravitational flexure and thermal expansion of the radio telescope cannot be neglected in the tie vector computation, since they may bias the CRP estimate by several millimeters degrading its accuracy but not impacting on its formal precision. We highlight the dependency of the correlation matrices of the solutions on the geometry of the network and the observation schemes. Similarly, varying the extent of telescope deformations

  5. Comparison of computer simulated and observed force deformation characteristics of anti-seismic devices and isolated structures

    International Nuclear Information System (INIS)

    The paper discusses the finite element analysis of the force deformation characteristics of high damping rubber bearings, lead rubber bearings and natural rubber bearings. The dynamic response of structures isolated using bearings is also presented. The general purpose finite element program ABAQUS has been used for the numerical predictions under monotonic loads. For computing the dynamic response, a simplified model of the rubber bearing in the form of elasto-plastic system is used. This equivalent model is implemented using the computer code CASTEM-2000 and the dynamic response is obtained. The numerical results are found to match well with the experimental results. (author)

  6. Extraction and scattering analyses of 2D and bulk carriers in epitaxial graphene-on-SiC structure

    OpenAIRE

    Lisesivdin, S. B.; Atmaca, G.; ARSLAN, E.; Cakmakyapan, S; Kazar, O; Butun, S.; ul-Hassan, Jawad; Janzén, Erik; E. Ozbay

    2014-01-01

    Hall effect measurements of a graphene-on-SiC system were carried out as a function of temperature (1.8-200 K) at a static magnetic field (0.51) With the analysis of temperature dependent single-field Hall data with the Simple Parallel Conduction Extraction Method (SPCEM), bulk and two-dimensional (2D) carrier densities and mobilities were extracted successfully. Bulk carrier is attributed to SIC substrate and 2D carrier is attributed to the graphene layer. For each SPCEM extracted carrier da...

  7. Surface, interface and bulk electronic structure of some Pd-Ti systems by a tight-binding method

    OpenAIRE

    Pick, Š.; Mikušik, P.

    1992-01-01

    Properties of the bulk and (111) surface of the Pd3Ti alloy and some related Ti-Pd systems are studied by using a simple LCAO model. The sign and magnitude of core level shifts (CLS) at particular atoms are correlated with initial state effects. Considerable positive CLS are predicted for the surface and especially for the bulk Ti and Pd atoms, respectively, in the Pd3Ti phase. Origin of these CLS as well as their relation to experimental findings are discussed. Local densities of electronic ...

  8. Palaeoseismicity in relation to basin tectonics as revealed from soft-sediment deformation structures of the Lower Triassic Panchet formation, Raniganj basin (Damodar valley), eastern India

    Indian Academy of Sciences (India)

    Abhik Kundu; Bapi Goswami; Patrick G Eriksson; Abhijit Chakraborty

    2011-02-01

    The Raniganj basin in the Damodar valley of eastern India is located within the riftogenic Gondwana Master-Basin. The fluvio-lacustrine deposits of the Lower Triassic Panchet Formation of the Damodar valley in the study area preserve various soft-sediment deformation structures such as slump folds, convolute laminae, flame structures, dish-and-pillar structures, sandstone dykes, pseudonodules and syn-sedimentary faults. Although such soft-sediment deformation structures maybe formed by various processes, in the present area the association of these structures, their relation to the adjacent sedimentary rocks and the tectonic and depositional setting of the formation suggest that these structures are seismogenic. Movements along the basin margin and the intra-basinal faults and resultant seismicity with moderate magnitude (2–5 on Richter scale) are thought to have been responsible for the soft-sediment deformations.

  9. Soft-sediment deformation structures in seismically affected deep-sea Miocene turbidites (Cilento Basin, southern Italy

    Directory of Open Access Journals (Sweden)

    Valente Alessio

    2014-07-01

    Full Text Available Soft-sediment deformation structures (SSDS are widespread in the upper part of the S. Mauro Formation (Cilento Group, Middle-Late Miocene. The succession is represented mainly by thick and very thick, massive, coarse-grained sandstones, deposited by rapid sedimentation of high-density turbidity currents. The most common SSDS are short pillars, dishes, sedimentary sills and convolutions. They occur mostly in the upper parts of sandstone beds. Vertical tubes of 4-5 cm in diameter and up to 50 cm long constitute the most striking structures. They begin in the middle part of sandstone beds, which are basically massive or contain faint dish structures. These tubes can bifurcate upwards and/ or pass into bedding-parallel veins or dikes. The vertical tubes sometimes form sand volcanoes on the then sedimentary surface.

  10. STRENGTH AND DEFORMABILITY OF STRUCTURAL ELEMENTS OF TRANSPORT FACILITIES ON THE BASIS OF FINE-GRAINED FIBROUS STEEL SLAG CONCRETE

    Directory of Open Access Journals (Sweden)

    R. N. Chernousov

    2011-11-01

    Full Text Available Problem statement. Application of steel fibrous concrete in structures of transport facilities providesfor their reliable and durable operation, however, along with the indisputable advantages,steel fibrous concrete has significant drawback. Its application in transport construction is very expensive.The use of cast slag crushed stone screenings, along with fibers from waste products oflocal factories, as a filler of concrete matrix will significantly reduce the costs of production oftransport facility structures and their elements with the use of steel fibrous concrete.Results and conclusions. According to the results of experimental studies formulae for practical estimationof shrinkage deformations of concrete matrix of fibrous steel slag concrete are obtained. Theanalytical relationships for fibrous steel slag concrete are derived. These relationships involve ultimatecompression and tensile strength, increase in compression and bending strength with time, longtermcompression strength, low cycle tensile fatigue, wearability. Based on experimental studies theuse of fibrous steel slag concrete in structural elements of transport facilities is suggested.

  11. Tensorial structure of a q-deformed sp(4,R) superalgebra

    International Nuclear Information System (INIS)

    A supersymmetric quantum algebra is generated by irreducible tensor operators in respect to the algebra suq(2). The even generators are realized as tensor products of q-boson creation and annihilation operators, transforming as suq(2) spinors and acting as odd generators. In this way the transformation properties of all the algebra's generators in respect to the q-deformed algebra of the angular momentum are simultaneously preserved, which is important in view of future applications in physics. In the limit q → 1 the classical Lie superalgebra sp(4,R) or the osp(1|4) is recovered. (author). 27 refs

  12. Interfacial structure of {101‾2} twin tip in deformed magnesium alloy

    International Nuclear Information System (INIS)

    A typical {101¯2} twin tip, which contains straight {101¯2} twinning planes and basal–prismatic interfaces, is characterized in deformed Mg–3% Al–1% Zn alloy by transmission electron microscopy (TEM) and high-resolution TEM. The existence of basal–prismatic interfaces is responsible for the deviation of the actual {101¯2} twinning boundary in the vicinity of the twin tip from the theoretical one. The process of twinning dislocation gliding around the twin tip boundary is described

  13. Evolution of orientations and deformation structures within individual grains in cold rolled columnar grained nickel

    DEFF Research Database (Denmark)

    Wu, G.L.; Godfrey, A.; Winther, Grethe; Juul Jensen, Dorte; Liu, Q.

    2011-01-01

    Columnar grained Ni is used as a model material allowing simultaneous non-surface investigations of the evolution of crystallographic orientations and deformation microstructures within individual grains as a function of rolling strain up to ε=0.7. Electron channelling contrast and electron...... grains. Large grains have microstructure and orientation scatters similar to those observed in single crystals of similar orientation. The observations are interpreted based on a slip system analysis, considering the relative effects of the initial grain orientation and the interaction between...

  14. Temperature–pressure induced nano-structural inhomogenities for vortex pinning in bulk MgB2 of different connectivity

    International Nuclear Information System (INIS)

    Highlights: • We studied correlations between structure of MgB2 and SC characteristics. • B- and O-enriched inhomogeneities can act as pinning centers in bulk MgB2. • The role of point pinning increases with the increase in manufacturing temperature. • The jc increase due to O localization and decrease of sizes of B-enriched inclusions. - Abstract: Higher critical current densities, jc, (up to 1.6–0.15 MA/cm2 at 10–35 K) at low magnetic fields can be attained in MgB2-based materials, if a high manufacturing temperature (1050 °C) is used, while low temperatures (600–800 °C) usually lead to higher critical currents in high magnetic fields (10–4 kA/cm2 in 6–10 T at 10 K). This tendency was observed for MgB2-based materials having 55–99% density and 17–98% connectivity, which were prepared by different methods from different precursors in a wide range of pressure (0.1 MPa–2 GPa). The variation of the manufacturing temperature led to a redistribution of the magnesium, boron, and impurity oxygen. At 2 GPa, its increase results in the segregation of the oxygen in MgB2 and the transformation of 15–20 nm thick layers of MgB0.6–0.8O0.8–0.9 into separate MgB0.9–3.5O1.6–2 grains and to a reduction of the size of MgB11–13O0.2–0.3 inclusions located in the MgB2 (MgB2.2–1.7O0.4–0.6) matrix. The size reduction of B-enriched inclusions and the localization of O in MgB2 seem to be the reason for the increase of jc in low fields and for the shift from grain boundary to point pinning of vortices witnessed by an increase of the k-ratio

  15. Formation of the soft-sediment deformation structures and its constraints on dinosaur fossil burial of the Cretaceous in Zhucheng, Shandong province, East China

    Science.gov (United States)

    He, Bizhu; Qiao, Xiufu; Cai, Zhihui; Tian, Hongshui; Chen, Shuqing

    2013-04-01

    The triangular-shaped Zhucheng depression is located in the southwestern part of the Jiaolai basin, Jiaodong peninsula, East China. Various soft-sediment deformation structures are recognized in the southern Zhucheng depression, which have behaviour are plastic and/or brittle. Soft-sediment deformation structures mainly include undulate fold, mound and sag, diapir, convolute deformation and seismic-unconformity in the Lower Cretaceous, which are composed of fine-grained sediments in lacustrine environment, while load structure, ball and pillow structure, plunged sediment mixtures structure, fault-graded occurred in the Upper Cretaceous, which formed in a conglomeratic or coarse arenaceous alluvial fan and flood-plain setting. These soft-sediment deformation structures are proposed triggered by paleoearthquake. The deformed layers and undeformed layers developed in intervals, suggesting frequent seismic activities. In studied area, numerous giant hadrosaurid skeleton fossils have been found in the Upper Cretaceous Wangshi Group science 1958, and unusual and abundant dinosaur track fossils have been discovered in the Lower Cretaceous Yangzhuang Formation of Laiyang Group. The widespread identified soft-sediment deformation structures are proximately underlying or overlying these dinosaur fossil bearing strata. The depositional setting changed while multiple paleo-seismic events and tectonic activity happened. In the Early Cretaceous, after the occurrence of paleo-earthquakes and environmental changes, dinosaurs migrated and a lot of tracks with similar orientation on lacustrine offshore were preserved. In the Late Cretaceous, a large-scale dinosaur fossil layers and paleo-earthquake records occurred in intervals, indicating that the dinosaur fossils may be associated with large-scale debris flow and frequent earthquake events. Based on regional tectonic setting, distribution of soft-sediment deformation structures and predicted magnitude of paleo-earthquakes, the

  16. Structural analysis of nanocrystals and their role in the coercivity mechanism of Nd–Fe–Al–Dy bulk amorphous ferromagnets

    International Nuclear Information System (INIS)

    The magnetic property and microstructure of Nd60−xFe30Al10Dyx (x=0, 2, 4) bulk ferromagnets have been investigated. At room temperature, each alloy sample shows hard magnetic behavior, and the intrinsic coercivity increases significantly with increasing Dy content. Transmission electron microscopy (TEM) and Atom probe tomography (APT) results show nanocrystals of width 5–20 nm embedded in the Fe-rich amorphous matrix. The coercivity mechanism of the Nd60−xFe30Al10Dyx (x=0, 2, 4) amorphous alloys is discussed in the context of Gaunt's strong pinning model of domain walls. The crystallographic phases of nanocrystals identified by high-resolution TEM can act as pinning centers. Our findings give further insight into the coercivity mechanism of Nd-based bulk amorphous alloys through a better understanding of the nanostructural environment. - Highlights: • Study of the crystallographic phases present in the nanocrystals in Nd–Fe–Al–Dy bulk ferromagnets. • The phase composition of the nanocrystals varies with Dy content. • Shows the amorphous matrix is Fe-rich by atom probe tomography. • This work gives further insight into the coercivity mechanism of Nd-based bulk amorphous alloys through a better understanding of the nanostructural environment

  17. Multi-matrix loop equations: algebraic and differential structures and an approximation based on deformation quantization

    International Nuclear Information System (INIS)

    Large-N multi-matrix loop equations are formulated as quadratic difference equations in concatenation of gluon correlations. Though non-linear, they involve highest rank correlations linearly. They are underdetermined in many cases. Additional linear equations for gluon correlations, associated to symmetries of action and measure are found. Loop equations aren't differential equations as they involve left annihilation, which doesn't satisfy the Leibnitz rule with concatenation. But left annihilation is a derivation of the commutative shuffle product. Moreover shuffle and concatenation combine to define a bialgebra. Motivated by deformation quantization, we expand concatenation around shuffle in powers of q, whose physical value is 1. At zeroth order the loop equations become quadratic PDEs in the shuffle algebra. If the variation of the action is linear in iterated commutators of left annihilations, these quadratic PDEs linearize by passage to shuffle reciprocal of correlations. Remarkably, this is true for regularized versions of the Yang-Mills, Chern-Simons and Gaussian actions. But the linear equations are underdetermined just as the loop equations were. For any particular solution, the shuffle reciprocal is explicitly inverted to get the zeroth order gluon correlations. To go beyond zeroth order, we find a Poisson bracket on the shuffle algebra and associative q-products interpolating between shuffle and concatenation. This method, and a complementary one of deforming annihilation rather than product are shown to give over and underestimates for correlations of a gaussian matrix model

  18. Structural Properties of Bulk and Aqueous Systems of PEO-PIB-PEO Triblock Copolymers as Studied by Small-Angle Neutron Scattering and Cryo-Transmission Electron Microscopy

    DEFF Research Database (Denmark)

    Mortensen, Kell; Talmon, Yeshayahu; Gao, Bo; Kops, Jørgen

    1997-01-01

    aggregates probably have a more disclike shape, as the micelles organize in lamellar structure. The 30% solution forms a bulk lamellar structure which, upon shear, organizes in a monodomain crystal. The bulk, PEO-PIB-PEO block copolymer forms at low temperatures a lamellar ordered phase induced by the PEO...... crystallization into lamellar sheets of PEO chains, presumably in helical form with a single fold. In a temperature regime near the transition temperature of T-c approximate to 45 degrees C, the PEO chains unfold, giving rise to significant swelling of the lamellar. Above T-c approximate to 45 degrees C, a strong...... correlation peak is observed corresponding to that observed in amorphous block copolymer systems, but it is still not clear whether this peak reflects strong concentration fluctuations of a disordered phase or the Bragg scattering of an ordered mesophase of amorphous blocks....

  19. Structural variation of proterozoic dikes in central Superior Province: A possible reflection of post-Archean shield deformation

    Science.gov (United States)

    Ernst, R. E.

    1983-01-01

    Preliminary work is reported on the use of two structural parameters, dike dip and thickness, as possible depth-of-exposure indicators in the Central Superior Province. The data demonstrate systematic variations in the dip and thickness of 2.6 and 1.14 Ga. dikes across the Central Superior Province and are tentatively interpreted to result from post intrusion deformation. Combination of these results with additional structural and paleomagnetic data from dikes of all gas may permit detailed mapping both spatially and temporally of crustal deformation in this part of the Canadian Shield. Although dike dip and thickness data apparently reflect crustal exposure level as given by host rock metamorphic grade (ranging from subgreenschist to granulite), these post-orogenic dikes themselves are at most only weakly metamorphosed. This requires that regional isotherms dropped dramatically after the Kenoran orogeny (2.65 Ga.) and prior to emplacement of the earlist post-orogenic swarm (Matachewan-Hearst) at 2.6 Ga.

  20. Long-term simulation of large deformation, mechano-chemical fluid-structure interactions in ALE and fully Eulerian coordinates

    Science.gov (United States)

    Frei, S.; Richter, T.; Wick, T.

    2016-09-01

    In this work, we develop numerical schemes for mechano-chemical fluid-structure interactions with long-term effects. We investigate a model of a growing solid interacting with an incompressible fluid. A typical example for such a situation is the formation and growth of plaque in blood vessels. This application includes two particular difficulties: First, growth may lead to very large deformations, up to full clogging of the fluid domain. We derive a simplified set of equations including a fluid-structure interaction system coupled to an ODE model for plaque growth in Arbitrary Lagrangian Eulerian (ALE) coordinates and in Eulerian coordinates. The latter novel technique is capable of handling very large deformations up to contact. The second difficulty stems from the different time scales: while the dynamics of the fluid demand to resolve a scale of seconds, growth typically takes place in a range of months. We propose a temporal two-scale approach using local small-scale problems to compute an effective wall stress that will enter a long-scale problem. Our proposed techniques are substantiated with several numerical tests that include comparisons of the Eulerian and ALE approaches as well as convergence studies.

  1. THE STRUCTURE OF THE LITHOSPHERIC MANTLE OF THE SIBERAIN CRATON AND SEISMODYNAMICS OF DEFORMATION WAVES IN THE BAIKAL SEISMIC ZONE

    Directory of Open Access Journals (Sweden)

    A. A. Stepashko

    2015-09-01

    Full Text Available  The evolution and specific features of seismogynamics of the Baikal zones are reviewed in the context of interactions between deep deformation waves and the regional structure of the lithospheric mantle. The study is based on a model of the mantle structure with reference to chemical compositions of mantle peridotites from ophiolotic series located in the south-western framing of the Siberian craton (Fig. 1. The chemical zonation of the lithospheric mantle at the regional scale is determined from results of analyses of the heterogeneity of compositions of peridotites (Fig. 2, Table 1 and variations of contents of whole rock major components, such as iron, magnesium and silica (Fig. 3. According to spatial variations of the compositions of peridotites, the mantle has the concentric zonal structure, and the content of SiO2 is regularly decreasing, while concentrations of FeO∑ and MgO are increasing towards the centre of such structure (Fig. 4. This structure belongs to the mantle of the Siberian craton, which deep edge extends beyond the surface contour of the craton and underlies the north-western segment of the Central Asian orogenic belt.Results of the studies of peridotites of the Baikal region are consistent with modern concepts [Snyder, 2002; O’Reilly, Griffin, 2006; Chen et al., 2009] that suggest that large mantle lenses underlie the Archaean cratons (Fig. 5. The lenses are distinguished by high-density ultrabasic rocks and compose high-velocity roots of cratons which have remained isolated from technic processes. Edges of the mantle lenses may extend a few hundred kilometers beyond the limits of the cratons and underlie orogenic belts that frame the cratons, and this takes place in the south-western segment of the Siberian craton.The revealed structure of the lithospheric mantle is consistent with independent results of seismic and magmatectonical studies of the region. The Angara geoblock is located above the central part of the

  2. -Deformed nonlinear maps

    Indian Academy of Sciences (India)

    Ramaswamy Jaganathan; Sudeshna Sinha

    2005-03-01

    Motivated by studies on -deformed physical systems related to quantum group structures, and by the elements of Tsallis statistical mechanics, the concept of -deformed nonlinear maps is introduced. As a specific example, a -deformation procedure is applied to the logistic map. Compared to the canonical logistic map, the resulting family of -logistic maps is shown to have a wider spectrum of interesting behaviours, including the co-existence of attractors – a phenomenon rare in one-dimensional maps.

  3. Multistep structural transition of hydrogen trititanate nanotubes into TiO2-B nanotubes: a comparison study between nanostructured and bulk materials

    International Nuclear Information System (INIS)

    H-trititanate nanotubes obtained by alkali hydrothermal treatment of TiO2 followed by proton exchange were compared to their bulk H2Ti3O7 counterpart with respect to their thermally induced structural transformation paths. As-synthesized and heat-treated samples were characterized by XRD, TEM/SAED, DSC and spectroscopy techniques, indicating that H2Ti3O7 nanotubes showed the same sequence of structural transformations as their bulk counterpart obtained by conventional solid state reaction. Nanostructured H2Ti3O7 converts into TiO2(B) via multistep transformation without losing its nanotubular morphology. The transformation occurs between 120 and 400 deg. C through topotactic mechanisms with the intermediate formation of nanostructured H2Ti6O13 and H2Ti12O25, which are more condensed layered titanates eventually rearranging to TiO2(B). Our results suggest that the intermediate tunnel structure H2Ti12O25 is the final layered intermediate phase, on which TiO2(B) nucleates and grows. The conversion of nanostructured TiO2(B) into anatase is completed at a much lower temperature than its bulk counterpart and is accompanied by loss of the nanotubular morphology

  4. Glass formation ability, structure and magnetocaloric effect of a heavy rare-earth bulk metallic glassy Gd55Co20Fe5Al20 alloy

    International Nuclear Information System (INIS)

    The glass formation ability, the structure and the magnetocaloric effect of the bulk metallic glassy Gd55Co20Fe5Al20 alloy were investigated. Bulk metallic glassy (BMGs) alloys were prepared by a copper-mold casting method. The glass forming ability and their structure were studied by using X-ray diffraction (XRD) and differential scanning calorimeter (DSC). The XRD analysis revealed that the as-cast cylinder of Gd55Co20Fe5Al20 alloy showed fully amorphous structure in 2 mm diameter. The DSC revealed that the bulk cylinder of the Gd55Co20Fe5Al20 alloy showed a distinct glass transition temperature and a relatively wide supercooled liquid region before crystallization. SQUID investigated the magnetic properties and the entropy changes. The Curie temperature of Gd55Co20Fe5Al20 BMGs alloy was about 130 K, but the maximum magnetic entropy changes(-ΔSM) showed at about 125 K, a little lower than the Curie temperature 130 K. The reason could probably be due to the presence of a little amount of nanocrystalline particles between amorphous phases. The BMG alloy has the characteristic of second-order transition (SOT) on Arrott plots. The results showed that the amorphous sample had a relatively improved magnetocaloric effect, indicating that the amorphous alloy could be considered as a candidate for magnetic refrigeration applications in the temperature interval range of 100-200 K

  5. A combined experimental and theoretical study of the structural, electronic and vibrational properties of bulk and few-layer Td-WTe2

    Science.gov (United States)

    Jana, Manoj K.; Singh, Anjali; Late, Dattatray J.; Rajamathi, Catherine R.; Biswas, Kanishka; Felser, Claudia; Waghmare, Umesh V.; Rao, C. N. R.

    2015-07-01

    The recent discovery of non-saturating giant positive magnetoresistance has aroused much interest in Td-WTe2. We have investigated structural, electronic and vibrational properties of bulk and few-layer Td-WTe2 experimentally and theoretically. Spin-orbit coupling is found to govern the semi-metallic character of Td-WTe2 and its structural link with the metallic 1 T form provides an understanding of its structural stability. There is a metal-to-insulator switch-over in the electrical conductivity and a change in the sign of the Seebeck coefficient around 373 K. Lattice vibrations of Td-WTe2 have been analyzed using first-principles calculations. Out of the 33 possible zone-center Raman active modes, five distinct Raman bands are observed around 112, 118, 134, 165 and 212 cm-1 in bulk Td-WTe2. Based on symmetry analysis and calculated Raman tensors, we assign the intense bands at 165 cm-1 and 212 cm-1 to the A1\\prime and A1\\prime\\prime modes, respectively. Most of the Raman bands stiffen with decreasing thickness, and the ratio of the integrated intensities of the A1\\prime\\prime to A1\\prime bands decreases in the few-layer sample, while all the bands soften in both the bulk and few-layer samples with increasing temperature.

  6. Soft-sediment deformation structures in Cambrian Series 2 tidal deposits (NW Estonia): implications for identifying endogenic triggering mechanisms in ancient sedimentary record

    Science.gov (United States)

    Põldsaar, Kairi

    2015-04-01

    Soft-sediment deformation structures (SSDS) are documented in several horizons within silt- and sandstones of the Cambrian Series 2 (Dominopolian Stage) Tiskre Formation, and some in the below-deposited argillaceous deposits of the Lükati Formation (northern part of the Baltoscandian Palaeobasin, NW Estonia). The aim of this study was to map, describe, and analyze these deformation features, discuss their deformation mechanism and possible triggers. Load structures (simple load casts, pillows, flame structures, convoluted lamination) with varying shapes and sizes occur in the Tiskre Fm in sedimentary interfaces within medium-bedded peritidal rhythmites (siltstone-argillaceous material) as well as within up to 3 m thick slightly seaward inclined stacked sandstone sequences. Homogenized beds, dish-and-pillar structures, and severely deformed bedding are also found within these stacked units and within a large tidal runoff channel infill. Autoclastic breccias and water-escape channels are rare and occur only in small-scale -- always related to thin, horizontal tidal laminae. Profound sedimentary dykes, sand volcanoes, and thrust faults, which are often related to earthquake triggered soft sediment deformation, were not observed within the studied intervals. Deformation horizon or horizons with large flat-topped pillows often with elongated morphologies occur at or near the boundary between the Tiskre and Lükati formations. Deformation mechanisms identified in this study for the various deformation types are gravitationally unstable reversed density gradient (especially in case of load features that are related to profound sedimentary interfaces) and lateral shear stress due to sediment current drag (in case of deformation structures that not related to loading at any apparent sedimentary interface). Synsedimentary liquefaction was identified as the primary driving force in most of the observed deformation horizons. Clay thixotropy may have contributed in the

  7. Engineering the Propagation of High-k Bulk Plasmonic Waves in Multilayer Hyperbolic Metamaterials by Multiscale Structuring

    DEFF Research Database (Denmark)

    Zhukovsky, Sergei; Lavrinenko, Andrei; Sipe, John E.

    layers. These high-k waves can have anomalously short wavelength, which underlies the concept of far-field subwavelength imaging (hyperlensing) in HMMs. In this work, we show that propagation of these high-k bulk plasmons can be controlled by modulating, or superstructuring, the filling fraction of metal...... feature exotic physical effects such as broadband singularity in the photonic density of states. It was shown that these photonic states are mainly populated by propagating high-k bulk plasmons, stemming from hybridization of short-range surface plasmon polaritons (SRSPPs) supported by individual metallic...... in a subwavelength metal-dielectric stack on a longer, wavelength scale. The basic superstructure geometry is a hybrid multiscale HMM where the modulation itself is periodic, forming a photonic band gap (PBG) for the high-k waves according to the same principles as in conventional photonic crystals...

  8. Contrasting Structures and Deformational History of Syntectonic Granites of Campina Grande and Serra Redonda, Borborema Province, NE Brazil

    Directory of Open Access Journals (Sweden)

    Sérgio Wilians de Oliveira Rodrigues

    2011-04-01

    Full Text Available The Campina Grande and Serra Redonda Granites are intrusive along the contact of the Paleoproterozoic basement(Alto Moxotó Domain with the Tonian gneisses (Alto Pajeú Domain of the Borborema Province (northeast Brazil. TheCampina Grande Granite (U-Pb age = 581± 2 Ma shows a concentric oval-shaped structure whereas the Serra RedondaGranite (U-Pb age = 576 ± 3 Ma has a tabular shape, elongated in the NE-SW direction. The plutons are separated bythe left-lateral Galante transcurrent shear zone. In this study, the anisotropy of magnetic susceptibility (AMS was appliedto 64 outcrops of granites to determine the internal structures of these plutons and to explore the relationship betweenmagmatism and deformation in an orogenic setting. The magnetic fabrics are concordant with the metamorphic structure ofthe host rocks. Strike-slip shear zones controlled the emplacement of the Serra Redonda Granite, as indicated by sigmoidalfoliation, defining shear bands associated with the Galante shear zone. In contrast, the magmatic/magnetic fabric of theCampina Grande granite seems to have been produced by body (ascensional forces. The pluton displays an inward dipping, concentric planar fabric parallel to the wall rock contact and lineations highly oblique to the foliation trend. The fabric of the Campina Grande pluton is consistent with a magma moving over a ramp dipping to southwest, with the lineation at high angle to the NE-trending flow direction. The contrasting structures of the plutons reflect the episodic nature of orogenic deformation, which was punctuated by the alternation of weak and strong strains, affecting the fabric development of the syntectonic intrusions.

  9. Fully exploitation of SBAS-DInSAR deformation time series for assessing structural damage: the case study of Rome, Italy

    Science.gov (United States)

    Bonano, Manuela; Arangio, Stefania; Calò, Fabiana; Di Mauro, Maria; Marsella, Maria; Manunta, Michele

    2014-05-01

    Remote sensing techniques have demonstrated to be effective tools to support natural and man-made risk mitigation activities. Among these, the Differential Synthetic Aperture Radar (SAR) Interferometry (DInSAR) technology is largely exploited in geoscience, oil and gas extraction, and landslide fields. Recently, thanks to the large availability of high resolution SAR systems (10 m or less), as well as to the development of advanced data processing techniques, DInSAR products have also started to be effectively used for applications in urban areas to detect localized displacements affecting single buildings and infrastructures. The advanced DInSAR technique referred to as Small Baseline Subset (SBAS) (Lanari et al., 2004) allows us to generate very long deformation time series, by exploiting large SAR datasets spanning up to 20 years (Bonano et al., 2012). Thanks to its capability to investigate wide areas, the SBAS-DInSAR technique is particularly suitable to remotely analyse the structural conditions of buildings located in densely urbanized zones. In this work, we fully exploit the results achieved over the city of Rome, Italy, through the well-established SBAS-DInSAR approach, aimed at performing a quantitative assessment of structural damage in urban areas affected by ground deformation (Arangio et al., 2013). More in details, we present an innovative methodology that integrates the SBAS-DInSAR measurements within an existing model, in order to assess the damage, and possibly estimate the future structural conditions, of single buildings affected by significant foundation settlements. In particular, a semi-empirical approach, based on a laminated beam model (Finno et al., 2005), is applied to investigate the damage of buildings located in the southern part of the city. The obtained results are in substantial agreement with in situ surveys, proving that the presented approach is an effective tool for the preliminary evaluation of the structural conditions in

  10. Recuperation d'energie issue des deformations de structures aeronautiques a l'aide de materiaux piezoelectriques

    Science.gov (United States)

    Debeaux, Sebastien

    Aerospace structural maintenance (fuselage, wings) is a major component of operational costs which requires aircraft to be grounded and some of its parts to be dismantled in order to proceed to inspection. In order to allow in situ monitoring, Structural Health Monitoring (SHM) has been proposed where sensors and actuators are integrated on the structure. To avoid extensive wiring of the nodes, wireless sensors and actuators are attractive but should be self powered to fully benefit from them. One idea is to convert the mechanical energy (vibrations) available all over an aircraft into electricity using piezoelectric materials. This work investigates the potential of strain-based energy harvesters (as opposed to inertial harvesters) to supply wireless nodes on typical aircraft structures. A simple model is used to describe typical dynamic behavior of aircraft components: a beam representing the whole wing subjected to aerodynamic loading and a plate representing a fuselage panel subjected to pressure fields (jet noise and turbulent boundary layer). Various configurations of piezoelectric materials are tested such as bulk PZT, PZT fiber composite and Polyvinylidene Fluoride (PVDF) in order to evaluate the influence of their characteristics (size, polarization, electrodes' shape, capacitance...) on the harvested power. The results show that for a typical aerospace excitation of the beam (10 Hz and 56 μdef), the energy produced is up to 40 mJ with bulk PZT for a 7 minutes loading time. From the literature, this appears sufficient for RF transmission (25 μJ). For other excitation sources (for instance jet noise), the energy produced is up to only 1 mJ with bulk PZT for a 25 minutes loading time. The drawback is that we should wait for several seconds in order to charge the harvester's battery. And, considering that many other components than the RF transceiver will require energy in the meantime, the time laps between two' measures could increase to several minutes

  11. Control over structure-specific flexibility improves anatomical accuracy for point-based deformable registration in bladder cancer radiotherapy

    International Nuclear Information System (INIS)

    Purpose: Future developments in image guided adaptive radiotherapy (IGART) for bladder cancer require accurate deformable image registration techniques for the precise assessment of tumor and bladder motion and deformation that occur as a result of large bladder volume changes during the course of radiotherapy treatment. The aim was to employ an extended version of a point-based deformable registration algorithm that allows control over tissue-specific flexibility in combination with the authors’ unique patient dataset, in order to overcome two major challenges of bladder cancer registration, i.e., the difficulty in accounting for the difference in flexibility between the bladder wall and tumor and the lack of visible anatomical landmarks for validation. Methods: The registration algorithm used in the current study is an extension of the symmetric-thin plate splines-robust point matching (S-TPS-RPM) algorithm, a symmetric feature-based registration method. The S-TPS-RPM algorithm has been previously extended to allow control over the degree of flexibility of different structures via a weight parameter. The extended weighted S-TPS-RPM algorithm was tested and validated on CT data (planning- and four to five repeat-CTs) of five urinary bladder cancer patients who received lipiodol injections before radiotherapy. The performance of the weighted S-TPS-RPM method, applied to bladder and tumor structures simultaneously, was compared with a previous version of the S-TPS-RPM algorithm applied to bladder wall structure alone and with a simultaneous nonweighted S-TPS-RPM registration of the bladder and tumor structures. Performance was assessed in terms of anatomical and geometric accuracy. The anatomical accuracy was calculated as the residual distance error (RDE) of the lipiodol markers and the geometric accuracy was determined by the surface distance, surface coverage, and inverse consistency errors. Optimal parameter values for the flexibility and bladder weight

  12. Structural and mechanical behaviour of severe plastically deformed high purity aluminium sheets processed by constrained groove pressing technique

    International Nuclear Information System (INIS)

    Highlights: • High purity aluminium sheets constrained groove pressed up to plastic strain of 5.8. • Microstructural evolution studied by TEM and X-ray diffraction profile analysis. • Ultrafine grained structure with grain size ∼900 nm achieved in sheets. • Yield strength increased by 5.3 times and tensile strength doubled after first pass. • Enhanced deformation homogeneity seen with increased accumulated plastic strain. - Abstract: High purity aluminium sheets (∼99.9%) are subjected to intense plastic straining by constrained groove pressing method successfully up to 5 passes thereby imparting an effective plastic strain of 5.8. Transmission electron microscopy studies of constrained groove pressed sheets divulged significant grain refinement and the average grain sizes obtained after five pass is estimated to be ∼0.9 μm. In addition to that, microstructural evolution of constrained groove pressed sheets is characterized by X-ray diffraction peak profile analysis employing Williamson–Hall method and the results obtained fairly concur with electron microscopy findings. The tensile behaviour evolution with increased straining indicates substantial improvement of yield strength by ∼5.3 times from 17 MPa to 90 MPa during first pass corroborated to grain refinement observed. Marginal increase in strengths is noticed during second pass followed by minor drop in strengths attributed to predominance of dislocation recovery is noticed in subsequent passes. Quantitative assessment of degree of deformation homogeneity using microhardness profiles reveal relatively better strain homogeneity at higher number of passes

  13. Deformable Simplicial Complexes

    DEFF Research Database (Denmark)

    Misztal, Marek Krzysztof

    In this dissertation we present a novel method for deformable interface tracking in 2D and 3D|deformable simplicial complexes (DSC). Deformable interfaces are used in several applications, such as fluid simulation, image analysis, reconstruction or structural optimization. In the DSC method, the...... triangles/tetrahedra marked as outside from those marked as inside. Such an approach allows for robust topological adaptivity. Among other advantages of the deformable simplicial complexes there are: space adaptivity, ability to handle and preserve sharp features, possibility for topology control. We...

  14. Formation of diapiric structure in the deformation zone, central Indian Ocean: A model from gravity and seismic reflection data

    Indian Academy of Sciences (India)

    K S Krishna; D Gopala Rao; Yu P Neprochnov

    2002-03-01

    Analyses of bathymetry, gravity and seismic reflection data of the diffusive plate boundary in the central Indian Ocean reveal a new kind of deformed structure besides the well-reported structures of long-wavelength anticlinal basement rises and high-angle reverse faults. The structure (basement trough) has a length of about 150 km and deepens by up to 1 km from its regional trend (northward dipping). The basement trough includes a rise at its center with a height of about 1.5 km. The rise is about 10 km wide with rounded upper surface and bounded by vertical faults. A broad free-air gravity low of about 20 mGal and a local high of 8 mGal in its center are associated with the identified basement trough and rise structure respectively. Seismic results reveal that the horizontal crustal compression prevailing in the diffusive plate boundary might have formed the basement trough possibly in early Pliocene time. Differential loading stresses have been generated from unequal crust/sediment thickness on lower crustal and upper mantle rocks. A thin semi-ductile serpentinite layer existing near the base of the crust that is interpreted to have been formed at mid-ocean ridge and become part of the lithosphere, may have responded to the downward loading stresses generated by the sediments and crustal rocks to inject the serpentinites into the overlying strata to form a classic diapiric structure.

  15. Impact of Bulk Aggregation on the Electronic Structure of Streptocyanines: Implications for the Solid-State Nonlinear Optical Properties and All-Optical Switching Applications

    KAUST Repository

    Gieseking, Rebecca L.

    2014-10-16

    Polymethine dyes in dilute solutions show many of the electronic and optical properties required for all-optical switching applications. However, in the form of thin films, their aggregation and interactions with counterions do generally strongly limit their utility. Here, we present a theoretical approach combining molecular-dynamics simulations and quantum-chemical calculations to describe the bulk molecular packing of streptocyanines (taken as representative of simple polymethines) with counterions of different hardness (Cl and BPh4 ) and understand the impact on the optical properties. The accuracy of the force field we use is verified by reproducing experimental crystal parameters as well as the configurations of polymethine/counterion complexes obtained from electronic-structure calculations. The aggregation characteristics can be understood in terms of both polymethinecounterion and polymethinepolymethine interactions. The counterions are found to localize near one end of the streptocyanine backbones, and the streptocyanines form a broad range of aggregates with significant electronic couplings between neighboring molecules. As a consequence, the linear and nonlinear optical properties are substantially modified in the bulk. By providing an understanding of the relationship between the molecular interactions and the bulk optical properties, our results point to a clear strategy for designing polymethine and counterion molecular structures and optimizing the materials properties for all-optical switching applications.

  16. Basal Complex and Basal Venation of Odonata Wings: Structural Diversity and Potential Role in the Wing Deformation.

    Science.gov (United States)

    Rajabi, H; Ghoroubi, N; Malaki, M; Darvizeh, A; Gorb, S N

    2016-01-01

    Dragonflies and damselflies, belonging to the order Odonata, are known to be excellent fliers with versatile flight capabilities. The ability to fly over a wide range of speeds, high manoeuvrability and great agility are a few characteristics of their flight. The architecture of the wings and their structural elements have been found to play a major role in this regard. However, the precise influence of individual wing components on the flight performance of these insects remains unknown. The design of the wing basis (so called basal complex) and the venation of this part are responsible for particular deformability and specific shape of the wing blade. However, the wing bases are rather different in representatives of different odonate groups. This presumably reflects the dimensions of the wings on one hand, and different flight characteristics on the other hand. In this article, we develop the first three-dimensional (3D) finite element (FE) models of the proximal part of the wings of typical representatives of five dragonflies and damselflies families. Using a combination of the basic material properties of insect cuticle, a linear elastic material model and a nonlinear geometric analysis, we simulate the mechanical behaviour of the wing bases. The results reveal that although both the basal venation and the basal complex influence the structural stiffness of the wings, it is only the latter which significantly affects their deformation patterns. The use of numerical simulations enabled us to address the role of various wing components such as the arculus, discoidal cell and triangle on the camber formation in flight. Our study further provides a detailed representation of the stress concentration in the models. The numerical analysis presented in this study is not only of importance for understanding structure-function relationship of insect wings, but also might help to improve the design of the wings for biomimetic micro-air vehicles (MAVs). PMID:27513753

  17. Numerical modeling anti-personnel blast mines coupled to a deformable leg structure

    Science.gov (United States)

    Cronin, Duane; Worswick, Mike; Williams, Kevin; Bourget, Daniel; Pageau, Gilles

    2001-06-01

    The development of improved landmine protective footwear requires an understanding of the physics and damage mechanisms associated with a close proximity blast event. Numerical models have been developed to model surrogate mines buried in soil using the Arbitrary Lagrangian Eulerian (ALE) technique to model the explosive and surrounding air, while the soil is modeled as a deformable Lagrangian solid. The advantage of the ALE model is the ability to model large deformations, such as the expanding gases of a high explosive. This model has been validated using the available experimental data [1]. The effect of varying depth of burial and soil conditions has been investigated with these numerical models and compares favorably to data in the literature. The surrogate landmine model has been coupled to a numerical model of a Simplified Lower Leg (SLL), which is designed to mimic the response and failure mechanisms of a human leg. The SLL consists of a bone and tissue simulant arranged as concentric cylinders. A new strain-rate dependant hyperelastic material model for the tissue simulant, ballistic gelatin, has been developed to model the tissue simulant response. The polymeric bone simulant material has been characterized and implemented as a strain-rate dependent material in the numerical model. The numerical model results agree with the measured response of the SLL during experimental blast tests [2]. The numerical model results are used to explain the experimental data. These models predict that, for a surface or sub-surface buried anti-personnel mine, the coupling between the mine and SLL is an important effect. In addition, the soil properties have a significant effect on the load transmitted to the leg. [1] Bergeron, D., Walker, R. and Coffey, C., 1998, “Detonation of 100-Gram Anti-Personnel Mine Surrogate Charges in Sand”, Report number SR 668, Defence Research Establishment Suffield, Canada. [2] Bourget, D., Williams, K., Pageau, G., and Cronin, D.,

  18. Hydrostatic and shear behavior of frictionless granular assemblies under different deformation conditions

    NARCIS (Netherlands)

    Imole, O.I.; Kumar, N.; Magnanimo, V.; Luding, S.

    2013-01-01

    Stress- and structure-anisotropy (bulk) responses to various deformation modes are studied for dense packings of linearly elastic, frictionless, polydisperse spheres in the (periodic) triaxial box element test configuration. The major goal is to formulate a guideline for the procedure of how to cali

  19. Curved Space-Times from Strict Deformations?

    CERN Document Server

    Much, Albert

    2016-01-01

    We use a deformed differential structure and the Rieffel deformation to obtain a curved metric by deforming the flat space-time. In particular, a deformed Friedmann-Robertson-Walker and an ultra-static space-time emerge from this strict deformation scheme.

  20. The increasement of the properties of structural low–carbon steel 10G2FB after deformation in the intercritical temperature interval and the accelerated cooling

    OpenAIRE

    Tkach, T

    2015-01-01

    Problem definition. With an increase of construction rate the necessity of mechanical properties of structural steel improvement has arised. The development of new modes of rolling can solve the problem of increasement the properties of structural low–carbon steels.Purpose: to increase the properties of sheet metal by determining the effect of deformation in the intercritical interval (ICI) temperatures and subsequent cooling on the structure and properties of structural low–carbon low alloy ...

  1. Structural and metamorphic evidence of local extension along the Vivero fault coeval with bulk crustal shortening in the Variscan chain (NW Spain)

    Science.gov (United States)

    Martínez, F. J.; Carreras, J.; Arboleya, M. L.; Dietsch, C.

    1996-01-01

    The Vivero fault is a W-dipping, N-S-striking ductile shear zone separating the Ollo de Sapo antiform in its western hangingwall and the Lugo dome in its eastern footwall. Two stages of deformation ( F1 and F2) produced nearly coaxial folds with sub-horizontal axes. A crenulation cleavage S2 transposes an older S1. Three sets of shear bands in the hangingwall define a pervasive fabric consistent with an E-W bulk shortening perpendicular to a composite S1-2 foliation and NNE-stretching parallel to L2. The Vivero fault zone is marked by a mylonitic foliation with a steeply NW-plunging stretching lineation and extensional crenulation cleavage (ECC) indicating normal slip. In the vicinity of the fault, sub-horizontal NNE-trending F3 folds, with a crenulation cleavage S3, deform earlier-formed fabrics, including a mylonitic foliation. Pressure-temperature conditions obtained from mineral assemblages on both sides of the Vivero fault yield a minimum throw of 5.5 km. Andalusite-bearing pelite in the hangingwall was infolded by an F2 synform into the kyanite field at 450-500°C. The eastern edge of these rocks was later accreted to the footwall and heated to andalusite-staurolite conditions at ˜600°C. Slip on the Vivero and Valdoviño faults is kinematically related. East-west shortening during F2 involved folding and sinistral strike-slip on the Valdoviño fault which induced local extension along the newly generated Vivero fault. Synkinematic emplacement of granitoids along the Vivero fault is favoured by extension. Coeval slip on both faults took place during the later stages of F2 folding. Geometrical constraints caused northwards escape of the crustal block bounded by the Valdoviño and Vivero faults, recorded by NNE-stretching defined by L2.

  2. Structural Relaxation of Pd39Ni10Cu30P21 Bulk Metallic Glass Under High Pressure

    Institute of Scientific and Technical Information of China (English)

    WANG Li-Min; ZHAN Zai-Ji; SUN Li-Ling; LI Gong; WANG Wen-Kui

    2001-01-01

    The Pd39Ni10Cu30P21 bulk metallic glass is isothermally relaxed under various pressures. The degree of thestructural relaxation is evaluated in terms of the enthalpy recovery behaviours involved in the irreversible glasstransition processes by using a temperature-modulated differential scanning calorimetry technique. A roughlylinear increase of the recovery enthalpy is observed within the experimental pressure range from 2.67 to 4.45 Gpa,whih reflects the release of the frozen-in enthalpy in the as-quenched glass withincreasing relaxation pressure.The pressure dependence of the timescale of the enthalpy recovery processes is also exhibited.

  3. Micro-beam and pulsed laser beam techniques for the micro-fabrication of diamond surface and bulk structures

    International Nuclear Information System (INIS)

    Micro-fabrication in diamond is applicable in a wide set of emerging technologies, exploiting the exceptional characteristics of diamond for application in bio-physics, photonics and radiation detection. Micro ion-beam irradiation and pulsed laser irradiation are complementary techniques, which permit the implementation of complex geometries, by modification and functionalization of surface and/or bulk material, modifying the optical, electrical and mechanical characteristics of the material. In this article we summarize the work done in Florence (Italy), concerning ion beam and pulsed laser beam micro-fabrication in diamond

  4. An X-ray absorption spectroscopy investigation of the local atomic structure in Cu-Ni-Si alloy after severe plastic deformation and ageing

    Science.gov (United States)

    Azzeddine, H.; Harfouche, M.; Hennet, L.; Thiaudiere, D.; Kawasaki, M.; Bradai, D.; Langdon, T. G.

    2015-08-01

    The local atomic structure of Cu-Ni-Si alloy after severe plastic deformation (SPD) processing and the decomposition of supersaturated solid solution upon annealing were investigated by means of X-ray absorption spectroscopy. The coordination number and interatomic distances were obtained by analyzing experimental extend X-ray absorption fine structure data collected at the Ni K-edge. Results indicate that the environment of Ni atoms in Cu-Ni-Si alloy is strongly influenced by the deformation process. Moreover, ageing at 973 K affects strongly the atomic structure around the Ni atoms in Cu-Ni-Si deformed by equal channel angular pressing and high pressure torsion. This influence is discussed in terms of changes and decomposition features of the Cu-Ni-Si solid solution.

  5. Deformation of Ordered Mesoporous Silica Structures on Exposure to High Temperatures

    Directory of Open Access Journals (Sweden)

    John B. Lowe

    2014-01-01

    Full Text Available Ordered mesoporous silica materials are of interest for a wide range of applications. In many of these, elevated temperatures are used either in the preparation of the material or during its use. Therefore, an understanding of the effect of high temperature treatments on these materials is desirable. In this work, a detailed structural study is performed on silicas with three representative pore structures: a 2-D hexagonal pore arrangement (SBA-15, a continuous 3D cubic bimodal pore structure (KIT-6, and a 3D large cage pore structure (FDU-12. Each silica is studied as prepared and after treatment at a series of temperatures between 300 and 900°C. Pore structures are imaged using Transmission Electron Microscopy. This technique is used in conjunction with Small-Angle X-ray Diffraction, gas physisorption, and 29Si solid state Nuclear Magnetic Resonance. Using these techniques, the pore size distributions, the unit cell dimensions of the mesoporous structures, and the relative occupancy of the distinct chemical environments of Si within them are cross correlated for the three silicas and their evolution with treatment temperature is elucidated. The physical and chemical properties before, during, and after collapse of these structures at high temperatures are described as are the differences in behavior between the three silica structures.

  6. Fine Structure in the Decay of the Highly Deformed Proton Emitter E number-sign131u

    International Nuclear Information System (INIS)

    Fine structure in the ground-state proton radioactive decay of highly deformed 131Eu has been identified. In addition to the previously observed ground-state line, measured here with a proton energy of 932(7) keV, a second proton peak with energy 811(7) keV was observed. We interpret this line as proton decay from the 131Eu ground state to the first excited 2+ state of the daughter nucleus 130Sm . Comparing the measured branching ratio with calculations enables the ground-state configuration of 131Eu to be unambiguously assigned to the 3/2+ [411] Nilsson configuration. copyright 1999 The American Physical Society

  7. Structural-scale levels of development of inelastic martensitic deformation during isothermal loading of submicrocrystalline titanium nickelide in premartensitic condition

    International Nuclear Information System (INIS)

    The results are presented of an experimental investigation into the regularities and mechanisms of the development of thermoelastic martensitic transformation in submicrocrystalline alloy Ti49.4Ni50.6 with different ways of thermo-power actions using the methods of optical microscopy in situ and X-ray diffraction. The peculiarities of localization of martensite transformation at the meso- and macroscale levels in this alloy with submicrocrystalline structure are considered. Experimental data on the relay mechanism of propagation of the martensitic transformation are presented. The interrelation between the localization of the martensitic transformation on the meso-and macroscale levels and deformation behavior under isothermal loading alloy Ti49.4Ni50.6 in submicrocrystalline condition are shown and discussed

  8. Texture Evaluation of a Bi-Modal Structure During Static Recrystallization of Hot-Deformed Mg-Al-Sn Alloy

    Science.gov (United States)

    Kabir, Abu Syed Humaun; Su, Jing; Yue, Stephen

    2016-02-01

    In this study, Mg-Al-Sn alloy was hot compressed at 523 K (250 °C) and annealed at 623 K (350 °C) for various times. The initial as-deformed microstructure was partially dynamic recrystallized with strain-induced precipitates on the recrystallized grain boundaries. After annealing at 623 K (350 °C), static recrystallization (SRX) of the bimodal microstructure took place where, at this temperature, no static precipitates formed. The goal of this work was to study the effect of dynamic precipitation on the texture evolution during the SRX process. Progressive texture evolution was studied during annealing by electron backscattered diffraction technique through a microstructure-tracking process. It was found that the grain-coarsening mechanism during the early stage of annealing is not totally controlled by the basal-oriented grains. Also, it was found that the dynamic precipitates may have significant influence in the early texture weakening during annealing of a bimodal structure.

  9. Structural Stability and Deformation of Solvated Sm@C2(45)-C90 under High Pressure

    Science.gov (United States)

    Cui, Jinxing; Yao, Mingguang; Yang, Hua; Liu, Ziyang; Liu, Shijie; Du, Mingrun; Li, Quanjun; Liu, Ran; Cui, Tian; Liu, Bingbing

    2016-08-01

    Solvated fullerenes recently have been shown to exhibit novel compression behaviors compared with the pristine fullerenes. However, less attention has been focused on the large cage endohedral metallofullerenes. Here, we have firstly synthesized solvated Sm@C90 microrods by a solution drop-drying method, and then studied the transformations under high pressure. The pressure-induced structural evolutions of Sm@C90 molecules both undergo deformation and collapse. The band gaps of both samples decrease with increasing pressure. The trapped Sm atom plays a role in restraining the compression of the adjacent bonds. The solvent plays a role in protecting Sm@C90 against collapse in the region of 12–20 GPa, decreasing and postponing the change of band gap. Above 30 GPa, the carbon cages collapse. Released from 45 GPa, the compressed solvated Sm@C90 forms a new ordered amorphous carbon cluster (OACC) structure with metal atoms trapped in the units of amorphous carbon clusters, which is different from the OACC structure formed by compressing solvated C60 and C70. This discovery opens the door for the creation of new carbon materials with desirable structural and physical properties when suitable starting materials are selected.

  10. Structural Stability and Deformation of Solvated Sm@C2(45)-C90 under High Pressure.

    Science.gov (United States)

    Cui, Jinxing; Yao, Mingguang; Yang, Hua; Liu, Ziyang; Liu, Shijie; Du, Mingrun; Li, Quanjun; Liu, Ran; Cui, Tian; Liu, Bingbing

    2016-01-01

    Solvated fullerenes recently have been shown to exhibit novel compression behaviors compared with the pristine fullerenes. However, less attention has been focused on the large cage endohedral metallofullerenes. Here, we have firstly synthesized solvated Sm@C90 microrods by a solution drop-drying method, and then studied the transformations under high pressure. The pressure-induced structural evolutions of Sm@C90 molecules both undergo deformation and collapse. The band gaps of both samples decrease with increasing pressure. The trapped Sm atom plays a role in restraining the compression of the adjacent bonds. The solvent plays a role in protecting Sm@C90 against collapse in the region of 12-20 GPa, decreasing and postponing the change of band gap. Above 30 GPa, the carbon cages collapse. Released from 45 GPa, the compressed solvated Sm@C90 forms a new ordered amorphous carbon cluster (OACC) structure with metal atoms trapped in the units of amorphous carbon clusters, which is different from the OACC structure formed by compressing solvated C60 and C70. This discovery opens the door for the creation of new carbon materials with desirable structural and physical properties when suitable starting materials are selected. PMID:27503144

  11. Microstructure, plastic deformation and strengthening mechanisms of an Al–Mg–Si alloy with a bimodal grain structure

    Energy Technology Data Exchange (ETDEWEB)

    Shakoori Oskooie, M. [Department of Materials Engineering, University of Tabriz, Tabriz 51666-16471 (Iran, Islamic Republic of); Asgharzadeh, H., E-mail: asgharzadeh@tabrizu.ac.ir [Department of Materials Engineering, University of Tabriz, Tabriz 51666-16471 (Iran, Islamic Republic of); Kim, H.S. [Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of)

    2015-05-25

    Highlights: • Al6063 with bimodal grain structures was fabricated by a powder metallurgy route. • The bimodal alloys showed a reasonable ductility together with a high strength. • Grain boundary strengthening was reduced at higher fraction of coarse grains. • The enhanced tensile ductility was attributed to crack blunting and delamination. - Abstract: Al6063 alloys with bimodal grain size distributions comprised of ultrafine-grained (UFG) and coarse-grained (CG) regions were produced via mechanical milling followed by hot extrusion. High-energy planetary ball milling for 22.5 h with a rotational speed of 350 rpm was employed for the synthesis of nanocrystalline Al6063 powders. The as-milled Al6063 powders were mixed with 15, 30, and 45 vol.% of the unmilled powders and then the powder mixtures were consolidated via extrusion at 450 °C with an extrusion ratio of 9:1. The microstructure of the bimodal extrudates was investigated using optical microscope, transmission electron microscope (TEM) and field emission scanning electron microscope equipped with an electron backscattered diffraction (EBSD) detector. The deformation behavior was investigated by means of uniaxial tensile tests. The bimodal Al6063 exhibited balanced mechanical properties, including high yield stress and ultimate tensile strength resulting from the UFG regions together with reasonable ductility attained from the CG areas. The fracture surfaces demonstrated a ductile fracture mode, in which the dimple size was correlated with the grain structure. The strengthening mechanisms are discussed based on the dislocation models and the functions of the CGs in the deformation behavior and ductility enhancement of bimodal Al6063 are explored.

  12. Linearly polarized, Q-switched, erbium-doped fiber laser incorporating a bulk-structured bismuth telluride/polyvinyl alcohol saturable absorber

    Science.gov (United States)

    Lee, Jinho; Lee, Junsu; Koo, Joonhoi; Chung, Hojai; Lee, Ju Han

    2016-07-01

    We experimentally demonstrate a linearly polarized, passively Q-switched, erbium (Er)-doped fiber laser using a saturable absorber (SA) based on a composite consisting of a bulk-structured bismuth telluride (Bi2Te3) topological insulator (TI) and polyvinyl alcohol (PVA). The SA was constructed on a polarization maintaining (PM) fiber ferrule platform, which had a sandwich structure. Its saturation intensity and modulation depth were measured to be ˜ and ˜4.1%, respectively. Using the prepared Bi2Te3/PVA SA in a PM Er-doped fiber ring laser, stable Q-switched pulses with a degree of polarization of ˜98.6% and an azimuth angle of ˜-0.34 deg were demonstrated. The minimum pulse width was measured to be ˜1.58 μs at a repetition rate of 47.1 kHz. This experimental demonstration verifies that a thin film based on a bulk-structured Bi2Te3 TI can fit into a sandwich-structured SA based on PM fiber ferrules.

  13. Structures of bulk amorphous Zr41Ti14Ni10Cu12.5Be22.5 alloy in amorphous, crystalline, supercooled liquid and liquid states

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The amorphous and crystal structures of Zr41Ti14Ni10Cu12.5Be22.5 alloy have been analyzed with X-ray diffractometer. The structures of bulk amorphous Zr41Ti14Ni10Cu12.5B22.5 alloy in solid, supercooled liquid and liquid states are almost of the same structure. The RDFs (Radius Distribution Function), the first coordination number, the first coordination radius, the correlation radius and atom number of the cluster were calculated for bulk amorphous Zr41Ti14Ni10Cu12.5B22.5 alloy in different states. The first coordination sphere radii and the first coordination numbers are 0.312nm, 11.2 in solid state, 0.301nm, 10.932 in supercooled liquid region and 0.305nm, 11.296 in liquid state. The crystal structure of Zr41Ti14Ni10Cu12.5B22.5 alloy is consisted of several intermetallic compounds which are CuZr2, Be2Zr, etc. The reason of formation glass for this alloy is that there is a larger resistance for atoms to rearrange and form intermetallic compounds in a long range order.

  14. Deformation mechanisms in experimentally deformed Boom Clay

    Science.gov (United States)

    Desbois, Guillaume; Schuck, Bernhard; Urai, Janos

    2016-04-01

    Bulk mechanical and transport properties of reference claystones for deep disposal of radioactive waste have been investigated since many years but little is known about microscale deformation mechanisms because accessing the relevant microstructure in these soft, very fine-grained, low permeable and low porous materials remains difficult. Recent development of ion beam polishing methods to prepare high quality damage free surfaces for scanning electron microscope (SEM) is opening new fields of microstructural investigation in claystones towards a better understanding of the deformation behavior transitional between rocks and soils. We present results of Boom Clay deformed in a triaxial cell in a consolidated - undrained test at a confining pressure of 0.375 MPa (i.e. close to natural value), with σ1 perpendicular to the bedding. Experiments stopped at 20 % strain. As a first approximation, the plasticity of the sample can be described by a Mohr-Coulomb type failure envelope with a coefficient of cohesion C = 0.117 MPa and an internal friction angle ϕ = 18.7°. After deformation test, the bulk sample shows a shear zone at an angle of about 35° from the vertical with an offset of about 5 mm. We used the "Lamipeel" method that allows producing a permanent absolutely plane and large size etched micro relief-replica in order to localize and to document the shear zone at the scale of the deformed core. High-resolution imaging of microstructures was mostly done by using the BIB-SEM method on key-regions identified after the "Lamipeel" method. Detailed BIB-SEM investigations of shear zones show the following: the boundaries between the shear zone and the host rock are sharp, clay aggregates and clastic grains are strongly reoriented parallel to the shear direction, and the porosity is significantly reduced in the shear zone and the grain size is smaller in the shear zone than in the host rock but there is no evidence for broken grains. Comparison of microstructures

  15. The Structural Evolution of the Calabrian Forearc: A Multidisciplinary Approach to Investigating Time-Transgressive Deformation in a Subduction-Rollback System

    Science.gov (United States)

    Reitz, Margaret A.

    This dissertation investigates the temporal and spatial variations in deformation of the Calabrian forearc during the evolution of the subduction-rollback system. In addition to contributing new data to the area, I develop three strategies for understanding recent and active deformation by linking long-term structural data with short-term geomorphological data. First, setting a "baseline" of deformation is important when studying plate boundaries. Through the structural mapping of an uplifted forearc basin, I conclude that rapid rollback is characterized by tectonic quiescence in the Calabrian forearc when it is located far from collision (from ~12 Ma -- ~5 Ma). This "baseline" provides a framework from which I interpret younger phases of deformation. In the middle Pliocene (~5-4 Ma), an arc-parallel shortening event characterizes the first stage of forearc collision in my field area. These folded sediments are later tilted, but structural data from the field cannot constrain the age or structure responsible for this youngest phase of deformation. The Neto River dissects this tilted surface opening up the possibly of linking structural data with geomorphic data from river erosion. I collected a transect of river sediment samples for 10Be analysis to determine variation in catchment-wide erosion rates through the modern day deformation. I, then, developed a numerical model that describes changes in erosion rate through time with the structural growth of the tilted surface. The model is the first of its kind to use catchment-wide erosion rates to constrain a structural model. The model results constrain the age of the beginning of deformation to 850 ka and suggest that a fold with a migrating hinge caused tilting of the surface. The model provides the basis for my hypothesis that the forearc is experiencing an arc-perpendicular shortening strain, which contradicts conclusions from GPS data and the well-documented extension in the western part of the forearc. To

  16. Microstructure of Cu60Zr20Ti20 bulk metallic glass rolled at different strain rates

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The structural evolution of Cu60Zr20Ti20 bulk metallic glass during rolling at different strain rates and cryogenic temperature was investigated by X-ray diffraction (XRD),differential scanning calorimetry (DSC) and high-resolution transmission electron microscopy (HRTEM). It is revealed that the deformation-induced transformation is strongly dependent on the strain rate. At the lowest experimental strain rate of 1.0×10-4 s-1,no phase transformation occurs until the highest deformation degree reaches 95%. In a strain rate range of 5.0×10-4-5.0×10-2 s-1,phase separation oc-curs in a high deformation degree. As the strain rate reaches 5.0×10-1 s-1,phase separation and nanocrystallization concur. The critical deformation degree for oc-currence of phase transformation decreases with the strain rate increasing.

  17. Ferromagnetic bulk glassy alloys

    International Nuclear Information System (INIS)

    This paper deals with the review on the formation, thermal stability and magnetic properties of the Fe-based bulk glassy alloys in as-cast bulk and melt-spun ribbon forms. A large supercooled liquid region over 50 K before crystallization was obtained in Fe-(Al, Ga)-(P, C, B, Si), Fe-(Cr, Mo, Nb)-(Al, Ga)-(P, C, B) and (Fe, Co, Ni)-Zr-M-B (M=Ti, Hf, V, Nb, Ta, Cr, Mo and W) systems and bulk glassy alloys were produced in a thickness range below 2 mm for the Fe-(Al, Ga)-(P, C, B, Si) system and 6 mm for the Fe-Co-(Zr, Nb, Ta)-(Mo, W)-B system by copper-mold casting. The ring-shaped glassy Fe-(Al, Ga)-(P, C, B, Si) alloys exhibit much better soft magnetic properties as compared with the ring-shaped alloy made from the melt-spun ribbon because of the formation of the unique domain structure. The good combination of high glass-forming ability and good soft magnetic properties indicates the possibility of future development as a new bulk glassy magnetic material

  18. Structural properties of the active layer of discotic hexabenzocoronene/perylene diimide bulk hetero junction photovoltaic devices: The role of alkyl side chain length

    International Nuclear Information System (INIS)

    We investigate thin blend films of phenyl-substituted hexa-peri-hexabenzocoronenes (HBC) with various alkyl side chain lengths ((CH2)n, n = 6, 8, 12 and 16)/perylenediimide (PDI). These blends constitute the active layers in bulk-hetero junction organic solar cells we studied recently [1]. Their structural properties are studied by both scanning electron microscopy and X-ray diffraction measurements. The results support the evidence for the formation of HBC donor-PDI acceptor complexes in all blends regardless of the side chain length of the HBC molecule. These complexes are packed into a layered structure parallel to the substrate for short side chain HBC molecules (n = 6 and 8). The layered structure is disrupted by increasing the side chain length of the HBC molecule and eventually a disordered structure is formed for long side chains (n > 12). We attribute this behavior to the size difference between the aromatic parts of the HBC and PDI molecules. For short side chains, the size difference results in a room for the side chains of the two molecules to fill in the space around the aromatic cores. For long side chains (n > 12), the empty space will not be enough to accommodate this increase, leading to the disruption of the layered structure and a rather disordered structure is formed. Our results highlight the importance of the donor-acceptor interaction in a bulk heterojunction active layer as well as the geometry of the two molecules and their role in determining the structure of the active layer and thus their photovoltaic performance.

  19. On the global structure of deformed Yang-Mills theory and QCD(adj) on {{R}}^3× {{S}}^1

    Science.gov (United States)

    Anber, Mohamed M.; Poppitz, Erich

    2015-10-01

    Spatial compactification on {{R}}^3× {{S}}_L^1 at small {{S}}^1 -size L often leads to a calculable vacuum structure, where various "topological molecules" are responsible for confinement and the realization of the center and discrete chiral symmetries. Within this semiclassically calculable framework, we study how distinct theories with the same SU({N}_c)/{{Z}}_k gauge group (labeled by "discrete θ-angles") arise upon gauging of appropriate {{Z}}_k subgroups of the one-form global center symmetry of an SU( N c ) gauge theory. We determine the possible {{Z}}_k actions on the local electric and magnetic effective degrees of freedom, find the ground states, and use domain walls and confining strings to give a physical picture of the vacuum structure of the different SU({N}_c)/{{Z}}_k theories. Some of our results reproduce ones from earlier supersymmetric studies, but most are new and do not invoke supersymmetry. We also study a further finite-temperature compactification to {{R}}^2× {{S}}_{β}^1× {{S}}_L^1 . We argue that, in deformed Yang-Mills theory, the effective theory near the deconfinement temperature β c ≫ L exhibits an emergent Kramers-Wannier duality and that it exchanges high- and low-temperature theories with different global structure, sharing features with both the Ising model and S-duality in N=4 supersymmetric Yang-Mills theory.

  20. Significance of settling model structures and parameter subsets in modelling WWTPs under wet-weather flow and filamentous bulking conditions

    DEFF Research Database (Denmark)

    Ramin, Elham; Sin, Gürkan; Mikkelsen, Peter Steen;

    2014-01-01

    settling parameters to the total variance of the key WWTP process outputs significantly depends on the influent flow and settling conditions. The magnitude of the impact is found to vary, depending on which type of 1-D SST model is used. Therefore, we identify and recommend potential parameter subsets for...... (SSTs) but also on the hydraulic behaviour of SSTs. The present study investigates the impacts of ideal and non-ideal flow (dry and wet weather) and settling (good settling and bulking) boundary conditions on the sensitivity of WWTP model outputs to uncertainties intrinsic to the one-dimensional (1-D...... WWTP model calibration, and propose optimal choice of 1-D SST models under different flow and settling boundary conditions. Additionally, the hydraulic parameters in the second-order SST model are found significant under dynamic wet-weather flow conditions. These results highlight the importance of...